Mold device

Abstract

To provide a mold device which does not require any draft in manufacturing a cast product having an inner surface having a circular cross section.SOLUTION: A mold device 100 includes a first mold 101, a second mold 102, and a cylindrical core part 230 having a cylindrical shape having an inner peripheral surface and an outer peripheral surface by combining a plurality of split cores 171 and 172, and a cylindrical cavity 107 is formed by combining them. The cylindrical core part 230 includes the first split cores 171 and the second split cores 172 arranged between the first split cores 171, and is formed by alternately combining the first split core 171 and the second split core 172. At the time of mold release, the first split core 171 and the second split core 172 are obliquely retracted toward a center axis C1 while maintaining an attitude of the cylindrical core part 230 with respect to the center axis C1 to disassemble the cylindrical core part 230.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a die apparatus having a core. [Background technology]

[0002] Die casting is one of the mass production techniques using a die assembly. In die casting, a cavity is provided between a pair of dies consisting of a fixed die and a movable die. After the molten metal injected into the cavity solidifies, the two dies are separated to form a cast product. The molten metal used is, for example, aluminum.

[0003] When using die casting to manufacture a cast part (e.g., a cylindrical member) with a hollow part having a circular cross section, a cylindrical core is placed in a cavity formed by a metal mold. In this case, a draft angle is generally provided on the outer periphery of the core to make it easier to pull out the core, which is tightened by contraction when the molten metal solidifies, during demolding (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-34092 A Summary of the Invention [Problem to be solved by the invention]

[0005] When a draft angle is provided on the outer periphery of the core, a gradient is formed on the inner surface of the hollow part of the cast part. Therefore, after casting, it is necessary to cut off the excess material and process the inner surface of the hollow part to make it the same inner diameter. This increases the manufacturing process and reduces product yields, which increases the manufacturing cost of the cast part.

[0006] The present invention has been made in consideration of the above circumstances, and its main object is to provide a mold device that eliminates the need for a draft angle when manufacturing a cast product having an inner surface that is circular in cross section. [Means for solving the problem]

[0007] In order to solve the above problems, the mold device of the present invention is A die apparatus including a first die, a second die, and a cylindrical core portion having an inner peripheral surface and an outer peripheral surface formed by combining a plurality of split cores, the die apparatus being configured to form a cylindrical cavity by combining the first die, The cylindrical core portion is A plurality of first split cores arranged at predetermined intervals in a circumferential direction; a plurality of second split cores disposed between each of the first split cores; The first split cores and the second split cores are alternately combined to form the first split cores, the first split core and the second split core each have an outer arcuate surface that forms the outer circumferential surface of the cylindrical core portion, The mold is provided with a split core moving mechanism which, during demolding, retracts the first split core and the second split core obliquely toward the central axis side while maintaining their orientation relative to the central axis of the cylindrical core portion to disassemble the cylindrical core portion, or moves them forward from the retracted position to form the cylindrical core portion.

[0008] Here, in the present invention, the first split core and the second split core maintaining their respective postures means that both the following first state and second state are maintained.

[0009] The first state refers to a state in which, when a virtual line is assumed on the outer arcuate surface that passes through the center in the arc direction and is parallel to the central axis of the cylindrical core portion, the virtual line on each of the outer arcuate surfaces of the first and second split cores is parallel to the central axis of the cylindrical core portion at the time of demolding. The second state refers to a state in which, when a virtual cross section is assumed that includes the virtual line and extends in the radial direction of the arc on the outer arcuate surface, the central axis is on an extension of the virtual cross section. Effect of the Invention

[0010] According to the die device of the present invention, when molten metal is introduced into the cavity, a cast part having an inner surface with a circular cross section is formed. When the cylindrical core part is released from the inner surface, the first and second split cores forming the cylindrical core part recede while maintaining their orientation relative to the central axis of the cylindrical core part and dropping toward the central axis. In this case, since the first and second split cores are not receded along the central axis of the hollow part, the first and second split cores can be released even if no draft is formed on the outer periphery of the cylindrical core part. This eliminates the need to cut off excess material after casting at the part where the cylindrical core part is provided to make the inner surface of the cast part have the same inner diameter, which contributes to reducing the manufacturing cost of the cast part. [Brief description of the drawings]

[0011] [Figure 1] FIG. 4 is a cross-sectional view showing a state where mold clamping is completed in the mold apparatus of the first embodiment. [Diagram 2] Cross section taken along line AA in FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] Cross-sectional view taken along CC in FIG. 5 . [Figure 7] FIG. 4 is a perspective view showing the front side of a first main body portion of the first slide die. [Figure 8]FIG. [Figure 9] FIG. [Figure 10] FIG. 13 is a perspective view showing the front side of the second main body portion of the second slide die. [Figure 11] 1A and 1B are perspective views showing the operation of forming a cylindrical core, in which (a) shows the state in which the first slide die and the second slide die are separated, (b) shows the state in which the two dies are close to each other, and (c) shows the state in which the two dies are clamped. [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. 4 is a cross-sectional view showing a first slide die (cross-section BB in FIG. 3). [Figure 15] FIG. [Figure 16] FIG. 9 is a cross-sectional view showing a second slide die (cross-section taken along line DD in FIG. 8). [Figure 17] FIG. 4 is an enlarged cross-sectional view showing the first split core being released from the mold. [Figure 18] 16A and 16B are cross-sectional views showing how split cores are released from the mold, where (a) shows the first split core (EE cross-section in FIG. 14) and (b) shows the second split core (FF cross-section in FIG. 16). [Figure 19] FIG. 13 is a perspective view showing the state in which only the first split core is released from the mold. [Figure 20] Cross section along line G in FIG. [Figure 21] FIG. 11 is a cross-sectional view showing a state where mold clamping is completed in the mold apparatus of the second embodiment. [Figure 22] H-H cross section in Figure 21. [Figure 23] FIG. [Figure 24] FIG. [Diagram 25] FIG. 13 shows a first split core, where (a) is a perspective view and (b) is a longitudinal sectional view of the JJ in (a). [Figure 26]FIG. 13 is a diagram showing a second split core, (a) being a perspective view, and (b) being a KK longitudinal sectional view of (a). [Figure 27] FIG. 4 is a perspective view showing the assembled state of the core portion, the first split core, and the second split core. [Figure 28] FIG. [Figure 29] FIG. 4 is a perspective view showing a first split core and a first extension portion. [Diagram 30] FIG. 4 is a perspective view showing a second split core and a second extension portion. [Diagram 31] FIG. 4 is a perspective view showing the cylindrical core portion, the extension cylindrical portion, the core portion, and the front end disk portion assembled together. [Diagram 32] Cross-sectional view II in Figure 23 (note that the angle of II is 135°). [Diagram 33] FIG. 33 is an enlarged view of the slider in FIG. 32. [Diagram 34] FIG. 4 is a rear view of the bonding surface at the front of the slider. [Diagram 35] FIG. 4 is a front view of the front end surface of the front part of the slider; [Diagram 36] 23A is a cross-sectional view showing a state in which the first split core and the first extension portion are released from the mold (cross-sectional view taken along II in FIG. 23). [Figure 37] 23A is a cross-sectional view showing the second split core and the second extension portion being released from the mold (cross-sectional view taken along II in FIG. 23). [Figure 38] 37A and 37B are cross-sectional views showing how the first split core and the second split core are released from the mold, where (a) is an L-L cross-sectional view in Fig. 32, (b) is an L-L cross-sectional view in Fig. 36, and (c) is an L-L cross-sectional view in Fig. 37. Cast parts are omitted in (b) and (c). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a first embodiment and a second embodiment, which are specific embodiments of the die apparatus of the present invention, will be described with reference to the drawings. The die apparatus 100 and 200 of each embodiment are used for die casting using molten aluminum, for example.

[0013] (Embodiment 1) First, a description will be given of a die apparatus 100 according to a first embodiment. This die apparatus 100 is used to manufacture a cast part Z1, which is a cylindrical member.

[0014] (Overall configuration of the mold device) As shown in FIG. 1, the mold device 100 includes a first mold 101, a second mold 102, a first slide mold 103, and a second slide mold 104. The first mold 101 and the second mold 102 are provided so as to be movable in a direction in which they approach and separate from each other. One of the first mold 101 and the second mold 102 is a fixed mold, and the other is a movable mold. The first slide mold 103 and the second slide mold 104 are provided so as to be movable in a direction perpendicular to the direction in which the first mold 101 and the second mold 102 approach and separate from each other, and approach and separate from each other. When the mold clamping is completed as shown in the figure, the first mold 101, the second mold 102, the first slide mold 103, and the second slide mold 104 are combined to form a molding space 105. Hereinafter, the direction in which the first die 101 and the second die 102 move toward and away from each other will be referred to as a first direction, and the direction in which the first slide die 103 and the second slide die 104 move toward and away from each other will be referred to as a second direction.

[0015] As shown in FIG. 2, the molding space 105 is formed by a first molding surface 101b and a second molding surface 102b. The first molding surface 101b is formed on a joining surface 101a of the first mold 101 with the second mold 102, and is a concave surface having a semi-cylindrical space. The second molding surface 102b is formed on a joining surface 102a of the second mold 102 with the first mold 101, and is a concave surface having a semi-cylindrical space. When the mold clamping is completed, the cross section of the molding space 105 formed by combining the first mold 101 and the second mold 102 is circular. The molding space 105 has an axis along the second direction as a central axis C1.

[0016] As shown in Figs. 1 and 2, a cylindrical core 106 is disposed in the molding space 105. The cylindrical core 106 is formed by combining a part of the first slide die 103 and a part of the second slide die 104, which are close to each other and clamped. No draft is provided on the outer periphery of the cylindrical core 106. The central axis C1 of the cylindrical core 106 extends along the second direction and is the same as the central axis C1 of the molding space 105. By disposing the cylindrical core 106 in the molding space 105, a cylindrical cavity 107 is formed. The cylindrical cavity 107 has a central axis C1 that is the same as the central axis C1 of the molding space 105 and the cylindrical core 106.

[0017] In the following description, the side of the first slide die 103 that faces the second slide die 104 is referred to as the front, and the opposite side in the second direction is referred to as the rear. Similarly, the side of the second slide die 104 that faces the first slide die 103 is referred to as the front, and the opposite side in the second direction is referred to as the rear. In the first slide die 103, a part that forms the cylindrical core 106 is provided on its front side, and in the second slide die 104, a part that forms the cylindrical core 106 is provided on its front side.

[0018] (Cylindrical core) Next, the cylindrical core 106 will be described in more detail. As shown in Fig. 1, the cylindrical core 106 has a cylindrical core portion 170 and a core portion 180 provided inside the cylindrical core portion 170. As shown in Fig. 2, the cylindrical core portion 170 is configured by combining a first split core 171 and a second split core 172 alternately along the circumferential direction. As shown in Fig. 1, the core portion 180 is formed by butting a first core support protrusion 120 and a second core support protrusion 150 together. The core portion 180 supports the cylindrical core portion 170 from its inside. The core portion 180 corresponds to an inner support portion.

[0019] As shown in FIG. 3, the first split core 171 forming the cylindrical core portion 170 protrudes from the front end surface 111 of the first main body portion 110 of the first slide die 103. A plurality of first split cores 171 are provided. As shown in FIG. 8, the second split core 172 forming the cylindrical core portion 170 protrudes from the front end surface 141 of the second main body portion 140 of the second slide die 104. A plurality of second split cores 172 are provided. As shown in FIG. 4 and FIG. 9, the front end surface 111 of the first slide die 103 and the front end surface 141 of the second slide die 104 are circular in front view. The centers of the front end surfaces 111, 141 are on the central axis C1 of the molding space 105 and the cylindrical core 106.

[0020] The first split cores 171 and the second split cores 172 have the same configuration, and the same number of each are provided. In other words, if the cylindrical core portion 170 is equally divided vertically into an even number of four or more, half of the divided cores will be first split cores 171, and the remaining half will be second split cores 172. In this first embodiment, as an example, four each of the first split cores 171 and second split cores 172 are provided. The cylindrical core portion 170 is formed by alternating combinations of four first split cores 171 and four second split cores 172.

[0021] 5, the first split core 171 has an annular sector-shaped cross section, which tapers toward the front while maintaining the cross-sectional shape, i.e., the dimension in the width direction becomes shorter. Here, the width direction refers to the direction perpendicular to the direction in which the first split core 171 extends, in a plan view of an outer arc-shaped surface 171-1 on the outside of the first split core 171. In addition to the outer arc-shaped surface 171-1 described above, the first split core 171 has an inner inclined surface 171-2, a pair of split side surfaces 171-3, and a front end surface 171-4 that is parallel to the front end surface 111 of the first slide die 103.

[0022] The outer arc-shaped surface 171-1 is an outer surface that constitutes part of the outer circumferential surface of the cylindrical core portion 170 when it is formed, and has an arc shape. As shown in Fig. 4, in a front view, the outer arc-shaped surface 171-1 is an arc centered on the center of the front end surface 111. As shown in Figs. 3 and 4, assuming that a virtual cylinder VC11 is formed by the outer arc-shaped surfaces 171-1 of the four first split cores 171, the virtual cylinder VC11 becomes the cylindrical core 106. As shown in Figs. 5 and 6, the inner inclined surface 171-2 is a flat surface that inclines gradually away from the outer arc-shaped surface 171-1 from the front to the rear of the first split core 171.

[0023] As shown in Fig. 5, in any cross section, the straight edge L12 of the inner inclined surface 171-2 is perpendicular to a virtual line VL11 that connects a widthwise center point P11 of the arcuate edge L11 of the outer arcuate surface 171-1 and a widthwise center point P12 of the straight edge L12 of the inner inclined surface 171-2. This configuration is the same for the front end surface 171-4. As shown in Fig. 6, the inclination angle θ1 of the inner inclined surface is preferably 1.5 degrees to 2 degrees with respect to the virtual line VL12 (see Fig. 5) that passes through the widthwise center of the outer arcuate surface 171-1, and the inclination angle θ1 in this first embodiment is set to 2 degrees. 4 and 5, the pair of divided side surfaces 171-3 are side surfaces that connect the outer arcuate surface 171-1 and the inner inclined surface 171-2 on both sides in the width direction, and are inclined from the outer arcuate surface 171-1 side toward the inner inclined surface 171-2 side so that the distance between the divided side surfaces 171-3 narrows. Also, the pair of divided side surfaces 171-3 are provided so as to approach each other toward the front.

[0024] 4, a top-bottom virtual line VL13 and a left-right virtual line VL14 are assumed to be based on the drawing and pass through the center of the front end face 111. In a front view, two of the four first split cores 171 are arranged on the top-bottom virtual line VL13 so as to be point-symmetrical about the center of the front end face 111. The top-bottom virtual line VL13 passes through the widthwise center of the arcuate edge L11 of the outer arcuate surface 171-1 and passes through the widthwise center of the straight edge L12 of the inner inclined surface 171-2 at the front end face 111 of the first split core 171. The remaining two first split cores 171 are arranged on the left-right virtual line VL14 and are arranged so as to be point-symmetrical about the center of the front end face 111. The left-right imaginary line VL14 passes through the widthwise center of the arcuate edge L11 of the outer arcuate surface 171-1 and passes through the widthwise center of the straight edge L12 of the inner inclined surface 171-2 at the front end faces 171-4 of the remaining two first split cores 171. In this manner, the four first split cores 171 are arranged side by side at equal intervals of 90 degrees in the circumferential direction.

[0025] As shown in Figures 3 and 4, the first split core 171 is supported from its inside by a first core support protrusion 120 which is part of the core portion 180 of the cylindrical core 106. The first core support protrusion 120 is provided on the first main body portion 110, and its front end face 111 protrudes from a central region surrounded by the four first split cores 171. The first core support protrusion 120 shares a central axis C1 with the molding space 105, and its protruding length is set to half the protruding length of the first split core 171. As shown in Figures 4 and 7, the first core support protrusion 120 is formed in an octagonal prism shape. The first core support protrusions 120 have a prismatic shape equal to the number of prisms into which the cylindrical core portion 170 is divided.

[0026] When the first core support protrusion 120 is viewed as an octagonal prism, half of the eight side surfaces are the first split core rear support surface 121, and the other half are the second split core front support surface 122. The first split core rear support surface 121 supports the rear half of the first split core 171. The second split core front support surface 122 supports the front half of the second split core 172 when the cylindrical core portion 170 is formed. The first split core rear support surface 121 and the second split core front support surface 122 are alternately provided in the circumferential direction. The first split core rear support surface 121 abuts against and supports the rear half of the inner inclined surface 171-2 of the first split core 171. The first split core rear support surface 121 is inclined from the front to the rear so as to approach the central axis C1 of the first core support protrusion 120. On the other hand, the second split core front support surface 122 is inclined from the front to the rear so as to move away from the central axis C1 of the first core support protrusion 120.

[0027] Next, the second split core 172, which forms the cylindrical core portion 170 together with the first split core 171, has the same configuration as the first split core 171, except that its orientation is reversed. That is, as shown in Figs. 8 and 9, it has an outer arc-shaped surface 172-1, an inner inclined surface 172-2, a pair of split side surfaces 172-3, and a front end surface 172-4. The imaginary cylinder VC12 formed by the four outer arc-shaped surfaces 172-1 becomes the cylindrical core 106. Since each of these components is the same as that of the first split core 171, repeated explanations will be omitted. However, the arrangement of the second split core 172 on the front end surface 141 of the second main body portion 140 is different from the arrangement of the first split core 171 in the first main body portion 110. Specifically, the second split core 172 is provided at a position shifted 45 degrees in the circumferential direction from the position where the first split core 171 is provided.

[0028] As shown in Fig. 9, in a front view, a right-inclined imaginary line VL15 and a left-inclined imaginary line VL16 are assumed to be at an angle of 45 degrees with respect to the top-bottom imaginary line VL13 and the left-right imaginary line VL14. Two of the four second split cores 172 are arranged on the right-inclined imaginary line VL15 so as to be point-symmetrical with respect to the center of the front end face 141. The right-inclined imaginary line VL15 passes through the widthwise center of the arc-shaped edge L13 of the outer arc-shaped surface 172-2 and passes through the widthwise center of the straight edge L14 of the inner inclined surface 172-2 at the front end face 172-4 of the second split core 172. The remaining two second split cores 172 are arranged on the left-inclined imaginary line VL16 and are point-symmetrical with respect to the center of the front end face 141. The left inclined imaginary line VL16 passes through the widthwise center of the arcuate edge L13 of the outer arcuate surface 172-1 and passes through the widthwise center of the straight edge L14 of the inner inclined surface 172-2 at the front end faces 172-4 of the remaining two second split cores 172. In this way, the four second split cores 172 are arranged at equal intervals in the circumferential direction every 90 degrees, shifted 45 degrees from the arrangement of the first split cores 171.

[0029] As shown in Figures 8 and 9, the second split core 172 is supported from its inside by a second core support protrusion 150 which is part of the core 180 of the cylindrical core 106. As shown in Figure 8, the second core support protrusion 150 is provided on the second main body 140, and its front end face 141 protrudes from a central region surrounded by the four second split cores 172. The second core support protrusion 150 shares a central axis C1 with the molding space 105, and its protruding length is set to half the protruding length of the second split core 172. As shown in Figures 9 and 10, the second core support protrusion 150 is formed in an octagonal prism shape. The second core support protrusions 150 also have a prismatic shape equal to the number of parts into which the cylindrical core portion 170 is divided.

[0030] When the second core support protrusion 150 is viewed as an octagonal prism, half of the eight side surfaces are second split core rear support surfaces 151, and the other half are first split core front support surfaces 152. The second split core rear support surface 151 supports the rear half of the second split core 172. The first split core front support surface 152 supports the front half of the first split core 171 when the cylindrical core portion 170 is formed. The second split core rear support surface 151 and the first split core front support surface 152 are alternately provided in the circumferential direction. The second split core rear support surface 151 abuts against and supports the rear half of the inner inclined surface 172-2 of the second split core 172. The second split core rear support surface 151 is inclined from the front to the rear so as to approach the central axis C1 of the second core support protrusion 150. On the other hand, the first split core front support surface 152 is inclined from the front to the rear so as to move away from the central axis C1 of the second core support protrusion 150.

[0031] The cylindrical core portion 170 is formed by combining the first split core 171 of the first slide die 103 and the second split core 172 of the second slide die 104 configured as described above. When the first slide die 103 and the second slide die 104 move from a separated state as shown in FIG. 11(a) to a direction approaching each other as shown in FIG. 11(b), one of the first split core 171 and the second split core 172 enters between the other. Then, as shown in FIG. 11(c), the two are alternately combined in the circumferential direction to form the cylindrical core portion 170. The outer peripheral surface of the cylindrical core portion 170 is formed by combining the outer arc-shaped surface 171-1 of the first split core 171 and the outer arc-shaped surface 172-1 of the second split core 172 without any gaps. Also, at this time, as shown in FIG. 2, the divided side surface 171-3 of the adjacent first split core 171 and the divided side surface 172-3 of the adjacent second split core 172 abut each other without any gaps over the entire area in the axial direction of the cylindrical core portion 170.

[0032] 11(c), in a state where the cylindrical core portion 170 is formed, the front end surface 171-4 of the first split core 171 abuts against a portion between the second split cores 172 in the front end surface 141 of the second main body portion 140 of the second slide die 104. A positioning protrusion 171-5 is provided on the front end surface 171-4 of the first split core 171 (see FIG. 5), and the positioning protrusion 171-5 is inserted into a positioning recess 141-1 (see FIG. 10) provided in the aforementioned portion of the front end surface 141 of the second main body portion 140, thereby positioning the first split core 171.

[0033] The front end surface 172-4 of the second split core 172 abuts against a portion between the first split cores 171 on the front end surface 111 of the first main body portion 110 of the first slide die 103. A positioning protrusion 172-5 (see FIG. 8) is provided on the front end surface 172-4 of the second split core 172, and the positioning protrusion 172-5 is inserted into the positioning recess 111-1 (see FIGS. 5 and 7) to position the second split core 172. The positioning recess 111-1 is provided in the above-mentioned portion of the front end surface 111 of the first main body portion 110. The cylindrical state of the cylindrical core portion 170 is maintained by positioning the first split core 171 and the second split core 172, respectively.

[0034] As shown in Figure 12, when the cylindrical core portion 170 is molded, the protruding end face 123 of the first core support protrusion 120 and the protruding end face 153 of the second core support protrusion 150 come into contact. The protruding end face 123 of the first core support protrusion 120 is provided with a positioning protrusion 124 (see Figure 7), and the positioning protrusion 124 is inserted into the positioning recess 154 (see Figure 10) provided on the protruding end face 153 of the second core support protrusion 150, thereby positioning the core support protrusions 120, 150 relative to each other.

[0035] As the protruding end faces 123, 153 of both core support projections 120, 150 abut against each other, both core support projections 120, 150 combine to form a core section 180 that supports the cylindrical core section 170 from the inside. A first split core support surface 181 is formed in the core section 180. The first split core support surface 181 continues from the first split core rear support surface 121 of the first core support projection 120 to the first split core front support surface 152 of the second core support projection 150. The first split core support surface 181 is inclined away from the central axis C1 from the first split core rear support surface 121 to the first split core front support surface 152. The first split core support surface 181 abuts against the inner inclined surface 171-2 of the first split core 171, and supports the first split core 171 from its inside.

[0036] In addition, a second split core support surface 182 is also formed on the core portion 180. The second split core support surface 182 continues from the second split core rear support surface 151 of the second core support projection 150 to the second split core front support surface 122 of the first core support projection 120. The second split core support surface 182 is inclined away from the central axis C1 from the second split core rear support surface 151 to the second split core front support surface 122. The second split core support surface 182 abuts against the inner inclined surface 172-2 of the second split core 172, supporting the second split core 172 from its inside.

[0037] (Cylindrical cavity) When the mold clamping is completed, the cylindrical core 106 formed as described above is arranged in a molding space 105 formed by the first molding surface 101b of the first mold 101 and the second molding surface 102b of the second mold 102 with the central axis C1 being the same, as shown in Fig. 1. Then, in the front end surface 111 of the first slide mold 103 and the front end surface 141 of the second slide mold 104, annular portions 111-2, 141-2 (see Figs. 4 and 9) which are on the outer periphery side of the outer periphery surface of the cylindrical core 106, respectively, define a cylindrical cavity 107. The cylindrical cavity 107 is formed by the molding space 105, the cylindrical core 106, and the annular portions 111-1, 141-2 of the front end surfaces 111, 141.

[0038] (Explosion structure of cylindrical core part) Next, a detailed description will be given of the configuration for releasing the cylindrical core portion 170 formed by combining the first split core 171 and the second split core 172 as described above from the inner surface of the cylindrical cast part Z1 after casting.

[0039] The release of the cylindrical core portion 170 is not performed by simply moving the first slide die 103 and the second slide die 104 in a direction away from each other. The release is performed in two stages. In the first stage of the release, the first split core 171 and the second split core 172 are respectively sunk while maintaining the positions of the first slide die 103 and the second slide die 104 at the time of completion of the clamping, without being moved backward, to disassemble the cylindrical core portion 170. In the sunk, the split cores 171 and 172 are not simply moved in the second direction, but are sunk at an angle while being retracted, without changing the state in which the imaginary line VL12 (see FIG. 5) passing through the width direction center of the outer arcuate surfaces 171-1 and 172-1 is parallel to the central axis C1. Thereafter, in the second stage of demolding, the first slide die 103 and the second slide die 104 are moved (retracted) in directions in which they are separated from each other, thereby completing the demolding.

[0040] Therefore, first, the configuration for immersing each split core 171, 172 into the main body parts 110, 140 in the first demolding stage, that is, the first split core moving mechanism, will be described in detail. The configuration is divided into a configuration possessed by the split cores 171, 172 and a configuration possessed by the main body parts 110, 140 of the slide dies 103, 104, and each will be described separately. Note that the first main body part 110 of the first slide die 103, into which the first split core 171 is immersed, and the second main body part 140 of the second slide die 104, into which the second split core 172 is immersed, have the same mechanism. Therefore, the description of the second main body part 140 of the second slide die 104, which will be described later, will be simplified.

[0041] First, the configuration of the first split core 171 will be described. As shown in Fig. 13, a first extension portion 130 is provided on the rear side of the first split core 171. The first extension portion 130 is provided so as to extend the first split core 171 to the rear side in the longitudinal direction. The first extension portion 130 is integrated with the first split core 171 to form a single long part. Unlike the first split core 171 which has a tapered shape, the first extension portion 130 has the same cross section along the longitudinal direction.

[0042] The first extension portion 130 has an extended outer arcuate surface 131, an extended inner inclined surface 132, a pair of extended side surfaces 133, and a retaining portion 134. The extended outer arcuate surface 131 is a portion extended from the boundary with the outer arcuate surface 171-1 of the first split core 171. The radius of the arc in the extended outer arcuate surface 131 is the same as the radius of the arc in the outer arcuate surface 171-1 of the first split core 171. If a virtual line VL17 is imagined on the extended outer arcuate surface 131 that passes through the center in the width direction and follows the direction in which the first extension portion 130 extends, the virtual line VL17 is inclined so as to be parallel to the inclination of the inner inclined surface 171-2 of the first split core 171. Note that, in a plan view of the extended outer arcuate surface 131, this refers to a direction perpendicular to the direction in which the first extension portion 130 extends.

[0043] The extended inner inclined surface 132 is formed so as to be flush with the inner inclined surface 171-2 of the first divided core 171, and is inclined in the same manner. The pair of extended side surfaces 133 are extended from the boundary with the pair of divided side surfaces 171-3, and are side surfaces that connect the extended outer arcuate surface 131 and the extended inner inclined surface 132 on both sides in the width direction. An equal distance is maintained between the pair of extended side surfaces 133. As described later, the slip-out prevention portion 134 is a portion that prevents the first extension portion 130 from slipping out of the first main body portion 110. The slip-out prevention portion 134 is provided at the rear end portion of the first extension portion 130, and is in the form of a plate that is formed slightly larger than the cross section of the first extension portion 130.

[0044] As described above, the first split core 171 has a tapered shape, while the first extension portion 130 has the same cross section along its longitudinal direction. The degree of tapering of the first split core 171 with respect to the first extension portion 130 is as follows. That is, as shown in Fig. 13, each split side surface 171-3 of the first split core 171 forms a predetermined angle α1 with respect to the imaginary plane VF11. When the inclination angle of the inner inclined surface 171-2 and the extended inner inclined surface 132 is θ1 and the number of the first split core 171 and the second split core 172 are the same number N, this angle α1 satisfies the following formulas (1) and (2).

[0045] The imaginary plane VF11 is a side surface along the radial direction of each imaginary divided body when the cylindrical core portion 170 is assumed to be equally divided into the total number of first divided cores 171 and second divided cores 172. In this embodiment 1, the cylindrical core portion 170 is divided into a total of eight parts, four first divided cores 171 and four second divided cores 172. Therefore, when the cylindrical core portion 230 is assumed to be equally divided into eight parts, the imaginary side surface of each imaginary divided body becomes the imaginary plane VF11. The extended side surface 133 is provided so as to follow this imaginary plane VF11.

[0046] Formula (1) tanθ1×sin(360° / 4N)=tanB Formula (2) α1>B For example, in this first embodiment, the inclination angle θ1 of the inner inclined surface 171-2 and the extended inner inclined surface 132 is set to 2 degrees, and four first divided cores 171 and four second divided cores 172 are provided. When this is applied to formulas (1) and (2), B = 0.76 (rounded down to two decimal places). Therefore, the angle α1 of the divided side surface 171-3 with respect to the virtual plane VF11 is set to a numerical value larger than this. However, it is preferable to set the angle α1 to 3 degrees with some leeway, rather than setting it to a numerical value close to B.

[0047] Next, the configuration of the first body part 110 of the first slide die 103 will be described. The first body part 110 is provided so as to be movable along the second direction, which is the moving direction of the first slide die 103, by using a cylinder or other known driving means. When the entire first slide die 103 is moved along the second direction, the first body part 110 is moved. As shown in FIG. 3 and FIG. 14, the first body part 110 has a first rear body part 112, a first slider 113, and a first front body part 114. The first rear body part 112 accommodates the first slider 113. The first front body part 114 is provided on the front side of the first rear body part 112, and the first body part 110 is formed by integrating the first body part 110 with the first body part 114. The front end surface of the first front body part 114 is the front end surface 111 of the first body part 110.

[0048] 14, the first rear main body portion 112 has a base portion 112-1 and a front plate portion 112-2 provided so as to be perpendicular to the second direction with respect to the base portion 112-1. The front plate portion 112-2 has an assembly surface 112-3 perpendicular to the second direction. The first front main body portion 114 also has an assembly surface 114-1 perpendicular to the second direction, and the first front main body portion 114 is assembled to the first rear main body portion 112 with the assembly surfaces 112-3, 114-1 abutting against each other, and the two are integrated.

[0049] The first slider 113 is provided on the base portion 112-1 so as to be movable along the second direction independently of the first rear main body portion 112 by using a known driving means. The first slider 113 is provided on the rear side opposite the first front main body portion 114, with the front plate portion 112-2 in between. In the front plate portion 112-2, the opposite side of the assembly surface 112-3 with the first front main body portion 114 is a slider abutment surface 112-4 perpendicular to the second direction. The front end of the first slider 113 has a front end abutment surface 113-1 perpendicular to the second direction, and the front end abutment surface 113-1 can abut against the slider abutment surface 112-4. The first slider 113 has a reference position in which its front end contact surface 113-1 contacts the slider contact surface 112-4 of the front plate portion 112-2. When mold clamping is completed, the first slider 113 is disposed at the reference position. The first slider 113 in the reference position is movable in a direction away from the front plate portion 112-2.

[0050] The first slider 113 is provided with a rear end of the first extension portion 130. The front part of the first slider 113 is provided with a rear end insertion portion 113-2 into which the rear end of the first extension portion 130 is inserted. The opening cross-sectional shape of the rear end insertion portion 113-2 is formed to be substantially the same as the cross-sectional shape of the first extension portion 130. A retaining portion 113-3 that is slightly larger than the opening cross-sectional shape of the rear end insertion portion 113-2 is provided at the back of the rear end insertion portion 113-2. The retaining portion 134 provided at the rear end of the first extension portion 130 abuts against the front end side inner wall 113-4 of the first extension portion 130 that forms the retaining portion 113-3, thereby preventing the first extension portion 130 from falling off the first slider 113.

[0051] The first extension portion 130 and the first divided core 171 protrude from the front end abutment surface 113-1 of the first slider 113. An extension portion insertion hole 112-5 is provided in the front plate portion 112-2 of the first rear main body portion 112. The first extension portion 130 protruding from the front end abutment surface 113-1 of the first slider 113 is inserted through the extension portion insertion hole 112-5. The extension portion insertion hole 112-5 in the front plate portion 112-2 penetrates between the assembly surface 114-1 with the first front main body portion 114 and the slider abutment surface 112-4.

[0052] The rear end insertion portion 113-2 of the first slider 113 is formed slightly larger than the cross section of the first extension portion 130, and the first extension portion 130 is inserted with a margin around the first extension portion 130. The retaining portion 113-3 is also formed to a size that allows a margin around the retaining portion 134. Therefore, the rear end of the first extension portion 130 is connected to the first slider 113 with a margin. The extension portion insertion hole 112-5 is also formed slightly larger than the cross section of the first extension portion 130, and the first extension portion 130 is inserted with a margin around the first extension portion 130. Therefore, the rear end insertion portion 113-2, the retaining portion 113-3, and the extension portion insertion hole 112-5 allow the movement of the first extension portion 130 within the range of the margin relative to the first slider 113.

[0053] The first front main body portion 114 is provided with a first guide hole 114-2 that guides the movement of the first extension portion 130 accompanying the movement of the first slider 113. The first guide hole 114-2 penetrates the mounting surface 114-1 of the first front main body portion 114 and the front end surface 111 (the front end surface 111 of the first main body portion 110) on the opposite side, and is open at both of them. The first extension portion 130 protruding from the extension portion insertion hole 112-5 of the front plate portion 112-2 is inserted into this first guide hole 114-2. As shown in FIG. 3 and FIG. 14, when the first slider 113 is arranged in the reference position, the front end of the first extension portion 130 (the boundary portion with the first divided core 171) is present at the front end opening of the first guide hole 114-2, and the first divided core 171, not the first extension portion 130, protrudes from the first guide hole 114-2.

[0054] 7, the opening cross section of the first guide hole 114-2 is annular sector shape over the entire hole to match the cross section of the first extension portion 130. The inner surface dimensions of the first guide hole 114-2 are approximately the same as the cross section dimensions of the first extension portion 130, with a difference in dimensions to the extent that the first extension portion 130 can move along the first guide hole 114-2. The first guide hole 114-2 has an arc-shaped inner surface 114-3, an inclined inner surface 114-4, and a pair of inner sides 114-5.

[0055] The arc-shaped inner surface 114-3 is a surface formed to form an arc having the same curvature as the extended outer arc-shaped surface 131 of the first extension portion 130. The extended outer arc-shaped surface 131 of the first extension portion 130 inserted into the first guide hole 114-2 abuts against the arc-shaped inner surface 114-3. When the arc-shaped inner surface 114-3 is viewed from the outside in a plan view, the direction perpendicular to the direction in which the first guide hole 114-2 extends is defined as the width direction. If a virtual line VL18 is assumed to extend through the center of the width direction on the arc-shaped inner surface 114-3 in the direction in which the first guide hole 114-2 extends, the virtual line VL18 is inclined so as to be parallel to the inclination of the inner inclined surface 171-2 of the first split core 171. A cross section cut along this virtual line VL18 is shown in FIG. 14.

[0056] Returning to Fig. 7, the inclined inner surface 114-4 is a flat surface that inclines from the front end surface 111 of the first front main body portion 114 toward the assembly surface 114-1 with the first rear main body portion 112 along the extended inner inclined surface 132 of the first extension portion 130. The inclined inner surface 114-4 extends while maintaining an inclination from the first split core rear support surface 121 of the first core support projection 120. The extended inner inclined surface 132 of the first extension portion 130 inserted into the first guide hole 114-2 abuts against the inclined inner surface 114-4.

[0057] The pair of inner side surfaces 114-5 are side surfaces that connect the arcuate inner surface 114-3 and the inclined inner surface 114-4 on both sides in the width direction. The inner side surfaces 114-5 are inclined from the arcuate inner surface 114-3 side toward the inclined inner surface 114-4 side so that the distance between the inner side surfaces 114-5 narrows. When the first extension portion 130 is inserted into the first guide hole 114-2, the pair of inner side surfaces 114-5 abut against a pair of extension side surfaces 133 of the first extension portion 130. The first guide hole 114-2 having such a configuration extends in a direction in which the inclined inner surface 114-4 inclines toward the central axis C1 of the first front main body portion 114 (the same as the central axis C1 of the molding space 105 and the cylindrical core 106), as shown in FIG.

[0058] Next, we will explain the configuration of the second slide die 104 that immerses the second split core 172 into the second main body portion 140. As mentioned above, the second slide die 104 has the same mechanism as the first slide die 103 that immerses the first split core 171 into the first main body portion 110, so we will explain it simply.

[0059] First, as shown in FIG. 15, a second extension 160 is provided on the rear side of the second split core 172. The second extension 160 is provided so as to extend the second split core 172 rearward in the longitudinal direction. The second extension 160 is integrated with the second split core 172 to form one long part. The second extension 160 has the same configuration as the first extension 130, only the orientation is reversed. That is, the second extension 160 also has an extended outer arcuate surface 161, an extended inner inclined surface 162, a pair of extended side surfaces 163, and a retaining portion 164. Each element is the same as the element of the first extension 130, and the second extension 160 is simply the first extension 130 reversed as the protruding direction of the second split core 172 is reversed relative to the first split core 171. Therefore, the description of each element is omitted.

[0060] Next, the second body portion 140 of the second slide die 104 has a second rear body portion 142, a second slider 143, and a second front body portion 144, as shown in Fig. 8 and Fig. 16. These correspond to the first rear body portion 112, the first slider 113, and the first front body portion 114 in the first slide die 103, respectively, and have substantially the same configurations. Also, the assembly configuration of the second extension portion 160 in the second body portion 140 is the same as the assembly configuration of the first extension portion 130 in the first body portion 110. The outline is as follows, and the explanation of the first body portion 110 applies to the details.

[0061] The second rear body portion 142 that houses the second slider 143 and the second front body portion 144 are integrated with their respective mounting surfaces 142-3, 144-1 mated to each other to form the second body portion 140. The second rear body portion 142 has a base portion 142-1 and a front plate portion 142-2. The second slider 143 is provided on the base portion 142-1 so as to be movable along the second direction separately from the second body portion 140. A state in which the front end abutment surface 143-1 of the second slider 143 abuts against the slider abutment surface 142-4 of the front plate portion 142-2 is set as a reference position of the second slider 143, and the second slider 143 is provided so as to be movable in a direction away from the front plate portion 142-2. The rear end of the second extension portion 160 is provided on the second slider 143 with some play and in a state where it is prevented from coming off. The second extension portion 160 protrudes from a front end abutment surface 143-1 of the second slider 143. The second extension portion 160 protruding from the front end abutment surface 143-1 of the second slider 143 is inserted into the extension portion insertion hole 142-5 of the front plate portion 142-2.

[0062] The second front body portion 144 is provided with a second guide hole 144-2 that guides the movement of the second extension portion 160 accompanying the movement of the second slider 143. The second extension portion 160 protruding from the extension portion insertion hole 142-5 of the front plate portion 142-2 is inserted into this second guide hole 144-2. When the second slider 143 is placed in the reference position, the second divided core 172 protrudes from the second guide hole 144-2. As shown in FIG. 10, the opening cross section of the second guide hole 144-2 is annular and sectorial in shape in accordance with the cross section of the second extension portion 160 over the entire hole area. The inner surface dimension of the second guide hole 144-2 is approximately the same as the cross section dimension of the second extension portion 160, and a difference in dimension is provided to the extent that the second extension portion 160 can move along the second guide hole 144-2. The second guide hole 144-2 has an arcuate inner surface 144-3 against which the extended outer arcuate surface 161 of the second extension portion 160 abuts, an inclined inner surface 144-4 against which the extended inner inclined surface 162 abuts, and a pair of inner surfaces 144-5 against which a pair of extended side surfaces 163 abut.

[0063] However, in the second front main body portion 144, the arrangement of the second guide hole 144-2, through which the second extension portion 160 is inserted to guide its movement, differs from that of the first guide hole 114-2 due to the difference in the arrangement of the first split core 171 and the second split core 172. That is, as shown in Fig. 10, the second guide hole 144-2 is provided at a position shifted 45 degrees in the circumferential direction from the first guide hole 114-2. And, the inclined inner surface 144-4 of the second guide hole 144-2 extends from the second split core rear support surface 151 of the second core support protrusion 150 while maintaining the inclination.

[0064] (Disassembly and removal of the cylindrical core) With the above-described configuration, in the first demolding stage, the cylindrical core portion 170 is disassembled by the following operation and is demolded from the inner surface of the cylindrical casting part Z1.

[0065] First, the operation of the first slide mold 103 will be described. At the beginning of demolding, as shown in FIG. 14, the first slider 113 abuts against the front plate 112-2 of the first rear main body 112. In the first stage of demolding, as shown by the imaginary line in FIG. 14, the first main body 110 is not moved, and only the first slider 113 is moved back from the reference position along the second direction. Accordingly, the first extension 130 moves back along the first guide hole 114-2 in the direction in which the inclined inner surface 114-4 is inclined. The moving back direction of the first extension 130 is not parallel to the second direction in which the first slider 113 moves. However, the rear end of the first extension 130 is connected to the first slider 113 with some play, and the extension insertion hole 112-5 provided in the front plate 112-2 also has an opening cross section that allows a margin around the first extension 130. Furthermore, the inclination angle θ1 of the inclined inner surface 114-4 is set to 2 degrees, which is a relatively small angle with respect to the second direction. Therefore, even if the first slider 113 retreats in the second direction, the first extension portion 130 can retreat obliquely while being guided by the first guide hole 114-2.

[0066] As shown in FIG. 17 and FIG. 18(a), as the first extension part 130 retreats, the first split core 171, while maintaining its posture with respect to the central axis C1, retreats while dropping inward (toward the central axis C1) in the direction in which the first extension part 130 moves. It retreats obliquely toward the central axis C1. At this time, the first split core 171 maintains a state in which a virtual line VL12 extending in the longitudinal direction at the center of the width direction is parallel to the central axis C1. Furthermore, when a virtual cross section VF12 including the virtual line VL12 and extending in the radial direction of the arc on the outer arc-shaped surface 171-1 is assumed, the central axis C1 is maintained on the extension of the virtual cross section VF12. Note that in FIG. 18(a), for ease of understanding, the amount of movement of the first split core 171 is shown larger than it actually is.

[0067] The first split core 171 retracts while its inner inclined surface 171-2 abuts against the first split core rear support surface 121 of the first core support projection 120 and the first split core front support surface 152 of the second core support projection 150. The first split core 171 sinks into the first guide hole 114-2 by the amount that it retracts while dropping inward. In addition, because the base end of the first extension portion 130 is connected to the first slider 113 with play, this play allows the first extension portion 130 and the first split core 171 to drop. As a result, the first split core 171 is released from the inner surface of the cylindrical cast part Z1, and the cylindrical core portion 170 is disassembled.

[0068] In the second slide die 104, the second split core 172 and the second extension 160 are arranged differently from the first split core 171 and the first extension 130, and their movements are the same as those in the first slide die 103. That is, as shown by the imaginary line in Fig. 16, when the second slider 143 is moved back from the reference position in the second direction without moving the second main body 140, the second extension 160 moves back along the second guide hole 144-2 in the direction in which the inclined inner surface 144-4 is inclined. As shown in Fig. 18(b), the second extension 160 moves back, so that the second split core 172 moves back while dropping inward (towards the central axis C1) in the direction in which the second extension 160 moves, while maintaining its posture with respect to the central axis C1. At this time, the second split core 172 maintains a state in which the imaginary line VL12 is parallel to the central axis C1, and also maintains a state in which the central axis C1 exists on an extension of the imaginary cross section VF12. Note that in Figure 18(b), for ease of understanding, the amount of movement of the second split core 172 is shown to be larger than it actually is.

[0069] The second split core 172 sinks into the second guide hole 144-2 by the amount that the second split core 172 retreats while dropping inward. In addition, because the base end of the second extension portion 160 is connected to the second slider 143 with some play, this play allows the second extension portion 160 and the second split core 172 to drop. As a result, the second split core 172 is released from the inner surface of the cylindrical cast part Z1, and the cylindrical core portion 170 is disassembled. This release state is the same as the state in which FIG. 17 is flipped left to right, so it is not shown in the figure.

[0070] In the first stage of demolding, the first slider 113 and the second slider 143 usually retract at the same time. However, even in this case, due to demolding resistance on the inner surface of the cast part Z1, the demolding of the first split core 171 and the demolding of the second split core 172 may not occur at the same time, and there may be a difference in the timing of each demolding. In this case, one of them remains attached to the inner surface of the cast part Z1, while the other falls inward and retreats to be demolded. Figures 19 and 20 show an example in which only the first split core 171 retracts. The cast part Z1 is omitted in Figure 19.

[0071] 19 and 20, even if the second split core 172 maintains a state of adhering to the inner surface of the cast part Z1, only the first split core 171 can move back while dropping inward. This is because the first split core 171 and the second split core 172 are formed to have a tapered shape, and the split side surfaces 171-3, 172-3 of each split core 171, 172 are set to form an angle α1 with respect to the imaginary plane VF11 (extended side surface 133). For example, if only the first split core 171 tries to move back while dropping inward, a gap G1 is generated between the split side surface 171-3 of the first split core 171 and the split side surface 172-3 of the second split core 172, and this gap G1 allows it to drop inward.

[0072] (Second stage of demolding and clamping) After the first demolding stage is completed, in the second demolding stage, the first body portion 110 and the second body portion 140 are moved backward in the second direction away from each other, thereby completing the demolding from the cast part Z1.

[0073] When casting is to be performed again after the cast part Z1 is removed, a mold clamping operation is performed. In the mold clamping operation, the first mold 101 and the second mold 102 are moved in a direction approaching each other to form a cylindrical molding space 105. At the same time or at different times, the first body part 110 of the first slide mold 103 and the second body part 140 of the second slide mold 104, which are in the retreated position, are advanced in a direction approaching each other. At this time, the first slider 113 of the first slide mold 103 and the second slider 143 of the second slide mold 104 are returned to their respective reference positions. As a result, the first divided core 171 protrudes entirely from the first guide hole 114-2 of the first slide mold 103, and the second divided core 172 protrudes entirely from the second guide hole 144-2 of the second slide mold 104.

[0074] As the first slide die 103 and the second slide die 104 advance, the second split core 172 enters between the adjacent first split cores 171, and the first split cores 171 and the second split cores 172 combine alternately in the circumferential direction to form a cylindrical core portion 170. Additionally, the first core support protrusions 120 and the second core support protrusions 150 combine to form a core portion 180 that supports the cylindrical core portion 170 from the inside. The cylindrical core portion 170 and the core portion 180 form a cylindrical core 106. The cylindrical core 106 is placed in the molding space 105, and a cylindrical cavity 107 is formed. By introducing molten metal into the cylindrical cavity 107, a cylindrical cast part Z1 is cast.

[0075] According to the die apparatus 100 of the first embodiment described above in detail, the following effects can be obtained.

[0076] (1) When the cylindrical core portion 170 is released from the inner surface of the cast part Z1, the first split core 171 and the second split core 172 forming the cylindrical core portion 170 recede while dropping toward the central axis C1 while maintaining their orientation relative to the central axis C1 of the cylindrical core portion 170. In this case, since the first split core 171 and the second split core 172 are not receded along the central axis C1 of the cylindrical cavity 107, the first split core 171 and the second split core 172 can be released even if a draft is not formed on the outer periphery of the cylindrical core portion 170. This eliminates the need to cut off excess material after casting to make the inner surface of the cast part Z1 have the same inner diameter, which contributes to reducing manufacturing costs.

[0077] (2) A core portion 180 is provided at the center of the cylindrical core portion 170, and the two together form the cylindrical core 106. The cylindrical core portion 170 is supported from the inner periphery by the core portion 180. Therefore, even if the cylindrical core portion 170 is tightened due to contraction when the molten metal solidifies, the cylindrical state formed by combining the first split core 171 and the second split core 172 can be maintained.

[0078] (3) The die assembly 100 includes a first slide die 103 and a second slide die 104. The first slide die 103 and the second slide die 104 are provided so as to be movable in a second direction in which they approach and separate from each other. The first split core 171 is provided on the first slide die 103, and the second split core 172 is provided on the second slide die 104. When the first slide die 103 and the second slide die 104 move in a direction in which they approach each other, the first split core 171 and the second split core 172 are combined to form a cylindrical core portion 170. The first slide die 103 and the second slide die 104 are moved backward while dropping while maintaining their respective postures, whereby both are released from the inner surface of the cast part Z1. This allows the production of a cast part Z1 having a hollow portion with openings on both sides.

[0079] (4) The moving mechanism for moving the first split core 171 backward includes a first extension 130 provided on the first split core 171, a first guide hole 114-2 provided on the first main body 110 of the first slide die 103, and a first slider 113 to which the rear end of the first extension 130 is connected. The first extension 130 is provided integrally with the first split core 171 and extends along the moving direction thereof. The first slider 113 is provided so as to be movable along the second direction independently of the first main body 110, and a play is provided in the connection with the first extension 130 to allow the first extension 130 to move obliquely toward the central axis C1. Similarly, the second split core 172 includes a second extension 160, a second guide hole 144-2, and a second slider 143. Similarly, play is provided in the connection between the second extension portion 160 and the second slider 143.

[0080] When the first slider 113 moves in the second direction, the first split core 171 moves with the first extension 130 guided by the first guide hole 114-2. When the second slider 143 moves in the opposite direction to the first slider 113, the second split core 172 moves with the second extension 160 guided by the second guide hole 144-2. The movement direction of the first split core 171 and the first extension 130 is non-parallel to the movement direction of the first slider 113, and the movement direction of the second split core 172 and the second extension 160 is also non-parallel to the movement direction of the second slider 143. Even in this case, the first extension 130 is connected to the first slider 113 and the second extension 160 is connected to the second slider 143 with play, so that the deviation in the movement direction can be absorbed by the play.

[0081] (5) If there is a discrepancy between the timing at which the first split core 171 and the second split core 172 recede due to the mold release resistance of the inner surface of the cast part Z1, one of them will remain attached to the inner surface of the cast part Z1, and only the other will recede first. Even in this case, the first split core 171 and the second split core 172 each have a tapered shape, and the split side surfaces 171-3, 172-3 are formed to form an angle α1 with respect to the imaginary plane VF11. Therefore, even if only one of them recede while sinking, a gap G1 is generated between the two split side surfaces 171-3, 172-3. This allows only one of them to recede due to the gap G1.

[0082] The mold device 100 of the first embodiment is not limited to the above-described configuration, and may be modified, for example, as follows.

[0083] (a) In the die device 100, in the die clamping operation, the first slider 113 and the second slider 143 are returned to their respective reference positions, and the first divided core 171 and the second divided core 172 are advanced, while the first slide die 103 and the second slide die 104 are moved in a direction approaching each other. Alternatively, the first slide die 103 and the second slide die 104 are moved first, while the first divided core 171 and the second divided core 172 are retreated. Then, after the core portion 180 is formed by the first core support protrusion 120 and the second core support protrusion 150, the first divided core 171 and the second divided core 172 may be advanced. As a result, the first divided core 171 and the second divided core 172 are supported by the first divided core support surface 181 and the second divided core support surface 182, respectively, during all of their movements from the retreated position to the reference position. Therefore, the cylindrical core portion 170 can be formed reliably and smoothly by the first split core 171 and the second split core 172.

[0084] (b) The first split core 171 and the second split core 172 may be formed to have an overall tapered shape including the first extension portion 130, like the first split core 231 in the mold device 200 of the second embodiment described later.

[0085] (c) In the above die apparatus 100, a cooling mechanism for cooling the cylindrical core portion 170 is omitted. When a cooling mechanism is provided, for example, a refrigerant passage for circulating a refrigerant may be provided inside each of the first split core 171 and the second split core 172. In this case, passages communicating with the refrigerant passage are also provided in the first extension portion 130 and the second extension portion 160, and a refrigerant is supplied to these passages from the outside. In addition, a refrigerant passage may also be provided in the first core support protrusion 120 and the second core support protrusion 150.

[0086] (d) In the above mold device 100, a mechanism is employed in which the rear end of the first extension portion 130 is connected to the first slider 113, and the rear end of the second extension portion 160 is connected to the second slider 143, and the first divided core 171 and the second divided core 172 are moved backward by the movement of the sliders 113, 143. Alternatively, a mechanism may be employed in which a cylinder or other known driving means is connected to each of the first extension portion 130 and the second extension portion 160, and the operation is controlled individually.

[0087] (e) The die assembly 100 of the first embodiment is for casting a casting part Z1 which is a cylindrical member. When casting a cylindrical portion provided as a part of the casting part after changing the configurations of the first die 101 and the second die 102, a configuration in which a cylindrical core 106 is formed by the first slide die 103 and the second slide die 104 may be applied.

[0088] (Embodiment 2) Next, a description will be given of a die apparatus 200 according to a second embodiment. This die apparatus 200 is used to manufacture a cast part Z2, which is a bottomed cylindrical member.

[0089] (Overall configuration of the mold device) As shown in FIG. 21, the mold device 200 includes a first mold 201, a second mold 202, and a slide mold 203. The first mold 201 and the second mold 202 are provided so as to be movable in a direction in which they approach and separate from each other. One of the first mold 201 and the second mold 202 is a fixed mold, and the other is a movable mold. The slide mold 203 is provided so as to be movable in a direction perpendicular to the approach and separation direction of the first mold 201 and the second mold 202. When the illustrated mold clamping is completed, the first mold 201, the second mold 202, and the slide mold 203 are combined to form a molding space 204. Hereinafter, the approach and separation direction of the first mold 201 and the second mold 202 will be described as a first direction, and the movement direction of the slide mold 203 will be described as a second direction.

[0090] As shown in FIG. 21 and FIG. 22, the molding space 204 is formed by the first molding surface 201b and the second molding surface 202b. The first molding surface 201b is formed on the joint surface 201a of the first mold 201 with the second mold 102, and is a concave surface having a bottomed semi-cylindrical space. One end of the first molding surface 201b is provided with a molding back surface 201c. The second molding surface 202b is formed on the joint surface 202a of the second mold 202 with the first mold 201, and is a concave surface having a bottomed semi-cylindrical space. One end of the second molding surface 202b is provided with a molding back surface 202c. When the first mold 201 and the second mold 202 are combined at the completion of mold clamping, the molding surfaces 201b, 202b and the molding back surfaces 201c, 202c form a molding space 204 having a bottomed cylindrical shape.

[0091] The molding space 204 has a central axis C2 that is an axis along the second direction. A cylindrical core 205 is disposed in the molding space 204. The cylindrical core 205 is provided at the front end of the slide die 203 and protrudes from the front end. The "front" here refers to the side of the slide die 203 on which the cylindrical core 205 is provided. The central axis C2 of the cylindrical core 205 extends along the second direction and is common to the central axis C2 of the molding space 204. By providing the cylindrical core 205 in the molding space 204, a bottomed cylindrical cavity 206 is formed. The bottomed cylindrical cavity 206 has the same central axis C2 as the central axis C2 of the molding space 204 and the cylindrical core 205.

[0092] (Cylindrical core) Next, the cylindrical core 205 will be described in more detail. As shown in Fig. 21, the cylindrical core 205 has a cylindrical core portion 230, a core portion 240 provided at the center of the cylindrical core portion 230, and a front end disk portion 250. As shown in Figs. 22 and 23, the cylindrical core portion 230 is configured by combining a first split core 231 and a second split core 232. No draft is provided on the outer periphery of the cylindrical core portion 230. The front end disk portion 250 corresponds to a disk-shaped core portion.

[0093] Incidentally, the first split core 231 and the second split core 232 each have extensions 221, 222 provided inside the main body 210 of the slide die 203, as shown in FIG. 23. Each split core 231, 232 and the corresponding extensions 221, 222 are integrated to form one long part. The first split core 231 and the second split core 232 are provided on the front side of the long part. The extensions 221, 222 of each split core 231, 232 are combined to form the extended cylindrical part 220. The configurations of the extensions 221, 222 and the extended cylindrical part 220 will be described later, and first the split cores 231, 232 will be described.

[0094] As shown in FIG. 23, the first split core 231 forming the cylindrical core portion 230 is provided in a plurality of parts, protruding from the front end surface 211 of the main body 210 of the slide die 203. The second split core 232 forming the cylindrical core portion 230 is also provided in a plurality of parts, protruding from the front end surface 211 of the main body 210 of the slide die 203. As also shown in FIG. 24, the front end surface 211 of the slide die 203 is annular in front view. The center of the front end surface 211 is on the central axis C2 of the molding space 204 and the cylindrical core portion 230. The number of the first split cores 231 and the number of the second split cores 232 are the same. In this second embodiment, four of each are provided. The cylindrical core portion 230 is formed by alternately combining the first split cores 231 and the second split cores 232 in the circumferential direction. Conversely, when the cylindrical core portion 230 is vertically divided into an even number of four or more, half of the divided portions become the first divided core 231 and the remaining half become the second divided core 232.

[0095] 25(a), the first split core 231 has an annular sector-shaped cross section, which tapers toward the front end while maintaining the cross-sectional shape, that is, the dimension in the width direction becomes shorter toward the front end. The width direction refers to the direction perpendicular to the direction in which the first split core 231 extends in a plan view of an outer arc-shaped surface 231-1 on the outside of the first split core 231. In addition to the outer arc-shaped surface 231-1 described above, the first split core 231 has an inner inclined surface 231-2, a pair of split side surfaces 231-3, and a front end surface 231-4 that is parallel to the front end surface 211 of the slide die 203.

[0096] The outer arcuate surface 231-1 is an outer surface that constitutes a part of the outer peripheral surface of the cylindrical core portion 230 when the cylindrical core portion 230 is formed, and has an arc shape. As shown in FIG. 24, in a front view, the outer arcuate surface 231-1 is an arc centered on the center of the front end surface 211. As shown in FIG. 25(a) and (b), the inner inclined surface 231-2 is a flat surface that inclines in a direction gradually moving away from the outer arcuate surface 231-1 from the front to the rear of the first split core 231. As shown in FIG. 25(a), in any cross section, the straight edge L22 of the inner inclined surface 231-2 is perpendicular to a virtual line VL21 that connects a widthwise center point P21 of the arcuate edge L21 of the outer arcuate surface 231-1 and a widthwise center point P22 of the straight edge L22 of the inner inclined surface 231-2.

[0097] As shown in FIG. 25(b), the inclination angle θ2 of the inner inclined surface 231-2 with respect to a virtual line VL22 (see FIG. 25(a)) passing through the widthwise center of the outer arcuate surface 231-1 is preferably 1.5 degrees to 2 degrees, and is set to 2 degrees in this second embodiment. As shown in FIG. 25(a), the pair of divided side surfaces 231-3 are side surfaces that connect the outer arcuate surface 231-1 and the inner inclined surface 231-2 on both sides in the width direction, and are inclined so that the distance between the divided side surfaces 231-3 narrows from the outer arcuate surface 231-1 side toward the inner inclined surface 231-2 side. In addition, the pair of divided side surfaces 231-3 are provided so as to approach each other toward the front end side.

[0098] 24, a vertical imaginary line VL23 and a horizontal imaginary line VL24 are assumed to be based on the drawing and pass through the center of the front end face 211. In a front view, two of the four first split cores 231 are arranged on the vertical imaginary line VL23 so as to be point symmetrical about the center of the front end face 211. The vertical imaginary line VL23 passes through the widthwise center of the arcuate edge L21 of the outer arcuate surface 231-1 at the front end face 231-4 of the first split core 231, and also passes through the widthwise center of the straight edge L22 of the inner inclined surface 231-2. The remaining two first split cores 231 are arranged on the horizontal imaginary line VL24 and are arranged so as to be point symmetrical about the center of the front end face 211. The left-right imaginary line VL24 passes through the widthwise center of the arcuate edge L21 of the outer arcuate surface 231-1 and also passes through the widthwise center of the straight edge L22 of the inner inclined surface 231-2 at the front end faces 231-4 of the remaining two first split cores 231. In this way, the four first split cores 231 are arranged side by side at equal intervals of 90 degrees in the circumferential direction.

[0099] Next, the second split core 232, which forms the cylindrical core portion 230 together with the first split core 231, has an annular sector-shaped cross section as shown in Fig. 26(a), and becomes wider toward the front end while maintaining the cross-sectional shape. The width direction refers to the direction perpendicular to the direction in which the second split core 232 extends in a plan view of an outer arc-shaped surface 232-1 on the outside of the second split core 232. In addition to the outer arc-shaped surface 232-1 described above, the second split core 232 has an inner inclined surface 232-2, a pair of split side surfaces 232-3, and a front end surface 232-4 that is parallel to the front end surface 211 of the slide die 203.

[0100] The outer arcuate surface 232-1 is an outer surface that constitutes a part of the outer peripheral surface of the cylindrical core portion 230 when the cylindrical core portion 230 is formed, and has an arc shape. As shown in FIG. 24, in a front view, the outer arcuate surface 232-1 is a circular arc centered on the center of the front end surface 211. As shown in FIG. 26(a) and (b), the inner inclined surface 232-2 is a flat surface that inclines in a direction gradually moving away from the outer arcuate surface 232-1 from the front to the rear of the second split core 232. In any cross section, the straight edge L24 of the inner inclined surface 232-2 is perpendicular to a virtual line VL25 that connects a widthwise center point P23 of the arcuate edge L23 of the outer arcuate surface 232-1 and a widthwise center point P24 of the straight edge L24 of the inner inclined surface 232-2. As shown in Figure 26(b), the inclination angle θ2 of the inner inclined surface 232-2 with respect to a virtual line VL26 (see Figure 26(a)) passing through the widthwise center of the outer arcuate surface 232-1 is preferably 1.5 degrees to 2 degrees, and in this second embodiment is set to 2 degrees.

[0101] 26(a), the pair of divided side surfaces 232-3 are side surfaces that connect the outer arcuate surface 232-1 and the inner inclined surface 232-2 on both sides in the width direction, and are inclined so that the distance between the divided side surfaces 232-3 narrows from the outer arcuate surface 232-1 side toward the inner inclined surface 232-2 side. Also, the pair of divided side surfaces 232-3 are provided so as to move away from each other toward the front end side.

[0102] 24, two inclined imaginary lines VL27, VL28 are assumed to pass through the center of the front end face 211 and are based on the drawing. Each of the inclined imaginary lines VL27, VL28 is located between the top-bottom imaginary line VL23 and the left-right imaginary line VL24, and forms an angle of 45 degrees with these two imaginary lines VL23, VL24.

[0103] In front view, two of the four second split cores 232 are arranged on one inclined virtual line VL27 so as to be point symmetrical with respect to the center of the front end face 211. At the front end face 232-4 of the second split core 232, the inclined virtual line VL27 passes through the width direction center of the arcuate edge L23 of the outer arcuate surface 232-1 and also passes through the width direction center of the straight edge L24 of the inner inclined surface 232-2. The remaining two second split cores 232 are arranged on the other inclined virtual line VL28 and arranged so as to be point symmetrical with respect to the center of the front end face 211. At the front end faces 232-4 of the remaining two second split cores 232, the inclined virtual line VL28 passes through the width direction center of the arcuate edge L23 of the outer arcuate surface 232-1 and also passes through the width direction center of the straight edge L24 of the inner inclined surface 232-2. In this manner, the four second split cores 232 are arranged side by side at equal intervals of 90 degrees in the circumferential direction.

[0104] The cylindrical core section 230 is formed by combining the first split core 231 and the second split core 232 configured as described above. As shown in Figs. 23 and 24, one of the first split core 231 and the second split core 232 is disposed between the other, and the two are combined alternately in the circumferential direction to form the cylindrical core section 230. The outer peripheral surface of the cylindrical core section 230 is formed by combining an outer arc-shaped surface 231-1 of the first split core 231 and an outer arc-shaped surface 232-1 of the second split core 232 without any gaps. At this time, as shown in Fig. 24, the divided side surface 231-3 of the adjacent first split core 231 and the divided side surface 232-3 of the second split core 232 abut on each other without any gaps over the entire axial direction of the cylindrical core section 230.

[0105] As shown in FIG. 24, the core 240, which constitutes the cylindrical core 205 together with the cylindrical core portion 230, supports the cylindrical core portion 230 from its inside (center side). The core portion 240 corresponds to an inner support portion. As shown in FIG. 21 and FIG. 24, the core portion 240 is provided at the center of the cylindrical core portion 230 and extends along the axial direction. The core portion 240 and the cylindrical core portion 230 share a central axis C2. As shown in FIG. 27, the core portion 240 is formed into an octagonal prism having a regular octagonal cross section and gradually narrowing from the front end side to the rear end side. The core portion 240 has a regular prism shape equal to the number of divided cylindrical core portions 230. Of the eight side surfaces of the core portion 240, half are first support surfaces 241 and the other half are second support surfaces 242.

[0106] The first support surface 241 and the second support surface 242 are alternately provided along the circumferential direction. The inclination angle of the first support surface 241 from the front to the rear is set to be the same as the inclination angle θ2 of the inner inclined surface 231-2 of the first divided core 231. The entire area of ​​the inner inclined surface 231-2 of the first divided core 231 abuts against the first support surface 241 and supports the inner inclined surface 231-2. The inclination angle of the second support surface 242 from the front to the rear is set to be the same as the inclination angle θ2 of the inner inclined surface 232-2 of the second divided core 232. The entire area of ​​the inner inclined surface 232-2 of the second divided core 232 abuts against the second support surface 242 and supports the inner inclined surface 232-2. Incidentally, only the front side of the entire core 240 is shown in FIG. 27. The configuration of the rear side of the core 240 will be described later.

[0107] The front end disk portion 250, which constitutes the cylindrical core 205 together with the cylindrical core portion 230 and the core portion 240, is provided at the front end of the core portion 240 as shown in Figs. 21 and 23. The core portion 240 and the front end disk portion 250 are integrally provided as one part. The front end disk portion 250 is shaped like a truncated cone and has a slightly smaller diameter than the front end surface 233 of the cylindrical core portion 230. The outer periphery of the front end disk portion 250 is formed so as to have a gradually smaller diameter toward the front end side. The inclination of the outer periphery 256 of the front end disk portion 250 becomes a draft gradient when the front end disk portion 250 is released from the inner surface side of the cast part Z2. The front end disk portion 250 has a flat front end surface 251 and a back side abutment surface 252 provided on the opposite side. The front end surface 251 and the back contact surface 252 are perpendicular to the central axis C2 of the core portion 240. The back contact surface 252 abuts against a front end surface 233 of the cylindrical core portion 230. The front end surface 233 of the cylindrical core portion 230 is formed by a front end surface 231-4 of the first split core 231 and a front end surface 232-4 of the second split core 232.

[0108] As shown in Fig. 28, the back contact surface 252 has a cylinder-holding groove 253 provided around the core 240 (see also Fig. 21). An outer peripheral groove inner surface 254 forming the cylinder-holding groove 253 has an annular shape. An inner peripheral groove inner surface 255 forming the cylinder-holding groove 253 is formed by extending each of the support surfaces 241, 242 of the core 240 while maintaining an inclination toward the front.

[0109] On the other hand, as shown in Fig. 25, a first cylinder retaining protrusion 231-5 is provided on the inner side of the front end surface 231-4 of the first split core 231. Also, as shown in Fig. 26, a second cylinder retaining protrusion 232-5 is provided on the inner side of the front end surface 232-4 of the second split core 232. Both cylinder retaining protrusions 231-5, 232-5 have arcuate protrusions 231-6, 232-6 on the outside and inclined protrusions 231-7, 232-7 on the inside. As shown in Figs. 24 and 31, when the cylindrical core part 230 is formed by the first split core 231 and the second split core 232, a front end protrusion 234 is formed on the front end surface 233 of the first split core 231 by the first cylinder retaining protrusion 231-5 and the second cylinder retaining protrusion 232-5. An annular circumferential surface 235 is formed on the outer periphery of the front end projection 234. The annular circumferential surface 235 is formed by an arcuate projection 231-6 of the first cylinder holding projection 231-5 and an arcuate projection 232-6 of the second cylinder holding projection 232-5.

[0110] 21 and 28, when the front end surface 233 of the cylindrical core portion 230 abuts against the back abutment surface 252 of the front end disk portion 250, the first cylinder retaining projection 231-5 of the first split core 231 and the second cylinder retaining projection 232-5 of the second split core 232 are inserted into the cylinder retaining groove portion 253 of the back abutment surface 252. When the insertion is complete, the annular circumferential surface 235 abuts against the outer circumferential groove inner surface 254 of the cylinder retaining groove portion 253. Also, the inclined projections 231-7, 232-7 of the cylinder retaining projections 231-5, 232-5 abut against the inner circumferential groove inner surface 255 of the cylinder retaining groove portion 253. This maintains the state in which the first split core 231 and the second split core 232 are combined to form the cylindrical core portion 230. The front end projection 234 corresponds to a shape-retaining projection, and the cylindrical retention groove 253 corresponds to a shape-retaining groove.

[0111] (Cylindrical cavity with bottom) When the mold clamping is completed, the cylindrical core 205 formed as described above is placed in the molding space 204 with the central axis C2 aligned, as shown in Fig. 21. The front end surface 211 of the main body 210 of the slide mold 203 defines a bottomed cylindrical cavity 206. The front end surface 251 of the front end disk portion 250 faces the molding rear surfaces 201c, 202c which define the molding space 204. The bottomed cylindrical cavity 206 is defined by the molding space 204, the cylindrical core 205, and the front end surface 211 of the slide mold 203.

[0112] (Explosion structure of cylindrical core part) Next, a detailed description will be given of the configuration for releasing the cylindrical core portion 230 formed by combining the first split core 231 and the second split core 232 as described above from the inner surface of the bottomed cylindrical cast part Z2 after casting.

[0113] The release of the cylindrical core part 230 is not performed by simply retracting the slide die 203. The release is roughly divided into two stages. In the first stage of the release, the first split core 231 and the second split core 232 are respectively immersed while maintaining the position of the slide die 203 at the time of completion of the clamping, and the cylindrical core part 230 is first disassembled. In the immersion, the split cores 231, 232 are not simply moved in the second direction, but are immersed at an angle while being retracted while maintaining the state that the imaginary lines VL22, VL26 (see Figs. 25 and 26) passing through the width direction center of the outer arcuate surfaces 231-1, 232-1 are parallel to the central axis C2. After that, in the second stage of the release, the slide die 203 is retracted to complete the release. Therefore, first, the configuration for immersing the split cores 231, 232 in the first stage of the release, that is, the second split core moving mechanism, will be described in detail.

[0114] First, the configuration of the first split core 231 will be described. As shown in Fig. 29, a first extension 221 is provided on the rear side of the first split core 231. The first extension 221 is provided so as to extend the first split core 231 in its longitudinal direction. The first extension 221 is integrated with the first split core 231 to form a single long part. This part has a shape that tapers overall from the rear end of the first extension 221 towards the front end of the first split core 231.

[0115] The first extension portion 221 has an extended outer arcuate surface 221-1, an extended inner inclined surface 221-2, a pair of extended side surfaces 221-3, and an outer protrusion 221-4. The extended outer arcuate surface 221-1 is a portion extended from the boundary with the outer arcuate surface 231-1 of the first split core 231, and is an outer surface forming an arc shape. The radius of the arc in the extended outer arcuate surface 221-1 is the same as the radius of the arc in the outer arcuate surface 231-1 of the first split core 231. As described later, the second split core 232 also has a second extension portion 222, and the second extension portion 222 has an extended outer arcuate surface 222-1. As shown in FIG. 31, the first extension portion 221 and the second extension portion 222 form an extended cylindrical portion 220. The extended outer arcuate surface 221-1 of the first extended portion 221 constitutes a part of the outer circumferential surface of the extended cylindrical portion 220.

[0116] If we imagine a virtual line VL29 that passes through the center in the width direction on the extended outer arcuate surface 221-1 and extends along the first extension portion 221, the virtual line VL29 is inclined so as to be parallel to the inclination of the inner inclined surface 231-2 of the first split core 231. Note that the width direction refers to the direction perpendicular to the extension direction of the first extension portion 221 in a plan view of the extended outer arcuate surface 221-1.

[0117] The extended inner inclined surface 221-2 is formed to be flush with the inner inclined surface 231-2 of the first split core 231 and is inclined in the same manner. The pair of extended side surfaces 221-3 extend from the boundary with the pair of split side surfaces 231-3 of the first split core 231 and are side surfaces that connect the extended outer arcuate surface 221-1 and the extended inner inclined surface 221-2 on both sides in the width direction. A rear end recess 221-5 is provided at the rear end of each of the pair of extended side surfaces 221-3. The rear end recess 221-5 is recessed so as to form a semi-cylindrical space.

[0118] The outer protrusion 221-4 is a portion that protrudes further outward from the extended outer arcuate surface 221-1. The outer protrusion 221-4 protrudes outward over the entire area of ​​the extended outer arcuate surface 221-1 in the arc direction. The outer protrusion 221-4 has a protruding arcuate surface 221-6, and a protruding step surface 221-7 perpendicular to the second direction is formed between the protruding arcuate surface 221-6 and the extended outer arcuate surface 221-1. The rear end surface 221-8 of the first extension 221 is perpendicular to the second direction.

[0119] As described above, the first split core 231 and the first extension 221 are tapered from the rear end to the front end. The degree of tapering is as follows. That is, as shown in FIG. 29, assuming a virtual plane VF21, the split side surface 231-3 and the extended side surface 221-3 form a predetermined angle α2 with the virtual plane VF21. The virtual line VL30 shown in FIG. 29 is on the virtual plane VF21, and the virtual line VL31 is on the split side surface 231-3 and the extended side surface 221-3. This angle α2 satisfies the following formulas (1) and (2). In each formula, the inclination angle of the inner inclined surface 231-2 and the extended inner inclined surface 221-2 is θ2, the numbers of first divided cores 231 and second divided cores 232 are the same number N, the movement amount of the first divided core 231 in the second direction is C, and the movement amount of the second divided core 232 in the same direction is D.

[0120] The virtual plane VF21 refers to the following virtual plane. That is, it is assumed that the cylindrical core portion 230 is equally divided into the total number of the first divided cores 231 and the second divided cores 232 on a virtual plane in the radial direction passing through the center. Virtual side faces of each virtual divided body formed thereby are further assumed. In this case, the virtual plane VF21 is a virtual plane along the virtual side faces. In this embodiment 2, the cylindrical core portion 230 is divided into a total of eight parts, four first divided cores 231 and four second divided cores 232. Therefore, when it is assumed that the cylindrical core portion 230 is equally divided into eight parts, the virtual plane VF21 is a virtual plane along the virtual side faces of each virtual divided body.

[0121] Formula (1) (C+D)×tanθ2×sin(360 / 4N) / (CD)=tanB Formula (2) α2>B For example, in this second embodiment, the inclination angle of the inner inclined surface 231-2 and the extended inner inclined surface 221-2 is set to 2 degrees, and four first divided cores 231 and four second divided cores 232 are provided. When this is applied to formulas (1) and (2), B = 2.29 (rounded down to two decimal places). Therefore, the angle α2 of the divided side surface 231-3 and the extended side surface 221-3 with respect to the virtual plane VF21 is set to a numerical value larger than this. However, it is preferable to set the angle α2 to 3 degrees with a margin rather than setting it to a numerical value close to B.

[0122] Next, the configuration of the second split core 232 will be described. As shown in Fig. 30, a second extension portion 222 is provided on the rear side of the second split core 232. The second extension portion 222 is provided so as to extend the second split core 232 in its longitudinal direction. The second extension portion 222 is integrated with the second split core 232 to form a single long part. This part has a shape that gradually becomes wider from the rear end of the second extension portion 222 toward the front end of the second split core 232.

[0123] The second extension portion 222 has an extended outer arcuate surface 222-1, an extended inner inclined surface 222-2, a pair of extended side surfaces 222-3, and an outer protrusion 222-4. The extended outer arcuate surface 222-1 is a portion extended from the boundary with the outer arcuate surface 232-1 of the second split core 232, and is an outer surface forming an arc shape. The radius of the arc in the extended outer arcuate surface 222-1 is the same as the radius of the arc in the outer arcuate surface 232-1 of the second split core 232. As shown in FIG. 31, when the extended cylindrical portion 220 is formed together with the first extension portion 221, the extended outer arcuate surface 222-1 forms a part of the outer peripheral surface of the extended cylindrical portion 220. If we imagine a virtual line VL32 that passes through the center in the width direction on the extended outer arcuate surface 222-1 and extends along the second extension portion 222, the virtual line VL32 is inclined so as to be parallel to the inclination of the inner inclined surface 232-2 of the second split core 232. Note that the width direction refers to the direction perpendicular to the direction in which the second extension portion 222 extends in a plan view of the extended outer arcuate surface 222-1.

[0124] The extended inner inclined surface 222-2 is formed to be flush with and similarly inclined to the inner inclined surface 232-2 of the second split core 232. The pair of extended side surfaces 222-3 extend from the boundary with the pair of split side surfaces 232-3 of the second split core 232, and are side surfaces that connect the extended outer arcuate surface 222-1 and the extended inner inclined surface 222-2 on both sides in the width direction.

[0125] The outer protrusion 222-4 is a portion that protrudes further outward from the extended outer arcuate surface 222-1. The outer protrusion 222-4 protrudes outward over the entire area of ​​the arc direction of the extended outer arcuate surface 222-1. The outer protrusion 222-4 has a protruding arcuate surface 222-6, and a protruding step surface 222-7 perpendicular to the second direction is formed between the protruding arcuate surface 222-6 and the extended outer arcuate surface 222-1. The outer protrusion 222-4 of the second extension 222 has the same length L25 in the second direction as the outer protrusion 221-4 of the first extension 221. The rear end surface 222-8 of the second extension 222 is perpendicular to the second direction.

[0126] As described above, the second split core 232 and the second extension portion 222 are formed so as to become wider from the rear end to the front end. The degree of the widening is as follows. That is, as shown in FIG. 30, assuming the above-mentioned imaginary plane VF21, the split side surface 232-3 and the extended side surface 222-3 form a predetermined angle α2 with respect to the imaginary plane VF21. The imaginary line VL30 shown in FIG. 30 is on the imaginary plane VF21, and the imaginary line VL33 is on the split side surface 232-3 and the extended side surface 222-3. This angle α2 is the same as the angle α2 that the split side surface 231-3 of the first split core 231 and the extended side surface 221-3 of the first extension portion 221 form with respect to the imaginary plane VF21.

[0127] In the state where the first split core 231 and the second split core 232 are combined to form the cylindrical core portion 230, as shown in Fig. 31, the first extension portion 221 of the first split core 231 and the second extension portion 222 of the second split core 232 are combined to form the extended cylindrical portion 220. The outer periphery of the extended cylindrical portion 220 is formed by combining the extended outer arc-shaped surface 221-1 of the first extension portion 221 and the extended outer arc-shaped surface 222-1 of the second extension portion 222 without any gaps. The rear end surface 223 of the extended cylindrical portion 220 is formed by the rear end surface 221-8 of the first extension portion 221 and the rear end surface 222-8 of the second extension portion 222. The rear end surface 223 of the extended cylindrical portion 220 is flush with the entire surface.

[0128] As described above, the extended outer arcuate surface 221-1 of the first extension portion 221 is inclined toward the central axis C2 while remaining the same arc as the outer arcuate surface 231-1 of the first split core 231. The extended outer arcuate surface 222-1 of the second extension portion 222 is also inclined toward the central axis C2 while remaining the same arc as the outer arcuate surface 232-1 of the second split core 232. Therefore, the outer peripheral edge in a cross section (cross section perpendicular to the central axis C2) of the extended cylindrical portion 220 is not a circle. On the outer periphery of the extended cylindrical portion 220, a step is formed between the extended outer arcuate surface 221-1 of the first extension portion 221 and the extended outer arcuate surface 222-1 of the second extension portion 222, and the step becomes more prominent toward the rear side.

[0129] The annular protrusion 224 is provided at the rear end of the extended cylindrical portion 220. The annular protrusion 224 is formed by combining an outer protrusion 221-4 provided at the rear end of the first extended portion 221 and an outer protrusion 222-4 provided at the rear end of the second extended portion 222. The annular protrusion 224 protrudes outward from the outer periphery of the extended cylindrical portion 220. In the annular protrusion 224, a protrusion arc surface 221-6 of the outer protrusion 221-4 of the first extended portion 221 and a protrusion arc surface 222-6 of the outer protrusion 222-4 of the second extended portion 222 are combined to form an annular outer periphery surface centered on the central axis C2 of the cylindrical core portion 230 and the extended cylindrical portion 220. The annular protrusion 224 protrudes with the same diameter along the front-rear direction. Between the outer circumferential surface of the annular protrusion 224 and the outer circumferential portion of the extended cylindrical portion 220, an annular step surface 225 is formed that is perpendicular to the second direction.

[0130] The core 240 is inserted through the center of the extended cylindrical portion 220 and supports the extended cylindrical portion 220 from the inside (center side). The core 240 extends rearward from the portion supporting the cylindrical core portion 230. The cross section of the extended portion is also a regular octagon, and the core 240 is formed into an octagonal prism that gradually narrows toward the rear end. Therefore, the first support surface 241 and the second support surface 242 each extend to the rear end at the same inclination angle. In the first extended portion 221 of the first split core 231 constituting the extended cylindrical portion 220, the extended inner inclined surface 221-2 abuts against the extended portion of the first support surface 241, and the first extended portion 221 is supported by the extended portion of the first support surface 241. In the second extension portion 222 of the second split core 232, the extended inner inclined surface 222-2 abuts against the extended portion of the second support surface 242, and the second extension portion 222 is supported by the extended portion of the second support surface 242. The core portion 240 protrudes significantly from the rear end of the extended cylindrical portion 220. The core portion 240 also corresponds to the extended inner support portion.

[0131] Next, the configuration of the main body 210 of the slide die 203 will be described. As shown in FIG. 32, the main body 210 holds the cylindrical core portion 230, the extended cylindrical portion 220, and the core portion 240 configured as described above. The main body 210 is provided so as to be movable along the second direction, which is the moving direction of the slide die 203, using a cylinder or other known driving means. When moving the entire slide die 203 along the second direction, the main body 210 is moved. The main body 210 has a main body rear portion 212, a main body middle portion 213, a main body front portion 214, and a slider 215. The main body middle portion 213 is provided with an internal housing portion 213-1 that houses the slider 215. The internal housing portion 213-1 has a space along the second direction and opens at the rear end side of the main body middle portion 213. The opening of the internal housing portion 213-1 is closed by the main body rear portion 212. A rear body portion 212, a middle body portion 213, and a front body portion 214 are combined and integrated.

[0132] The main body front part 214 has an assembly plate part 214-1 with the main body middle part 213, and a main body cylindrical part 214-2 provided on the front end side of the assembly plate part 214-1. The front end of the main body cylindrical part 214-2 forms the front end surface 211 of the main body part 210. The internal space of the main body cylindrical part 214-2 penetrates at the rear end side of the assembly plate part 214-1. A hole penetrating the assembly plate part 214-1 from the main body cylindrical part 214-2 is a front insertion hole 214-3, through which the extension cylindrical part 220 and the core part 240 are inserted. In the first extension portion 221 and the second extension portion 222 forming the extended cylindrical portion 220, the extended outer arcuate surfaces 221-1, 222-1 of the first extension portion 221 and the second extension portion 222 are in contact with the inner surface of the front insertion hole 214-3 over the entire area in the front-rear direction at the portion inserted into the front insertion hole 214-3. The front insertion hole 214-3 corresponds to the cylindrical portion insertion hole.

[0133] A middle insertion hole 213-2 is provided in the main body middle part 213. The middle insertion hole 213-2 communicates between the front insertion hole 214-3 of the main body front part 214 and the internal storage part 213-1 of the main body middle part 213, and like the front insertion hole 214-3, the extension cylindrical part 220 and the core part 240 are inserted through the middle insertion hole 213-2. The middle insertion hole 213-2 is formed slightly larger than the outer periphery of the part of the extension cylindrical part 220 that is inserted through the middle insertion hole 213-2, and a small gap is provided between the outer periphery and the inner surface of the hole of the middle insertion hole 213-2.

[0134] The extension cylindrical portion 220 and the core portion 240, which are inserted through the front insertion hole 214-3 and the middle insertion hole 213-2, have their rear ends provided in the internal housing portion 213-1. In the internal housing portion 213-1, the rear end of the core portion 240 protruding from the rear end of the extension cylindrical portion 220 extends to the main body rear portion 212 and is fixed to the main body rear portion 212 by a fixing means 212-1 such as a screw. In this manner, when the rear end of the core portion 240 is fixed to the main body rear portion 212, the front end of the extension cylindrical portion 220 is present in the front insertion hole 214-3 of the main body front portion 214, and the cylindrical core 205 protrudes from the front end surface 211 of the main body portion 210. Since the rear end of core portion 240 is fixed to rear body portion 212, the position of the tip end of core portion 240 and the position of front end disk portion 250 relative to main body portion 210 are fixed, and core portion 240 does not move in the second direction relative to main body portion 210.

[0135] The slider 215 has a rectangular prism shape as a whole and is accommodated in the internal accommodation section 213-1 of the main body middle section 213. The slider 215 is provided in the internal accommodation section 213-1 so as to be movable along the second direction separately from the main body middle section 213 using a cylinder or other known driving means. In the main body middle section 213, a front plate section 213-3 is provided at the front end side of the internal accommodation section 213-1 so as to be perpendicular to the second direction. The front plate section 213-3 is provided with a slider abutment surface 213-4 that forms the inner surface of the internal accommodation section 213-1. The front end surface 215-1 of the slider 215 is provided so as to be able to abut against this slider abutment surface 213-4. Both the front end surface 215-1 and the slider abutment surface 213-4 of the slider 215 are perpendicular to the second direction.

[0136] A central through-hole 213-2, through which the extension cylindrical portion 220 and the core portion 240 are inserted, is provided in this front plate portion 213-3. The slider 215 has a reference position in which its front end surface 215-1 abuts against a slider abutment surface 213-4 of the front plate portion 213-3. When mold clamping is completed, the slider 215 is disposed in the reference position. The slider 215 in the reference position is movable in a direction away from the front plate portion 213-3.

[0137] The slider 215 is formed by combining two parts, a slider front part 215-2 and a slider rear part 215-4. The slider front part 215-2 has a joint surface 215-3 with the slider rear part 215-4. The slider rear part 215-4 has a joint surface 215-5 with the slider front part 215-2. Both joint surfaces 215-3, 215-5 are perpendicular to the second direction. The joint surfaces 215-3, 215-5 are joined together to combine and integrate the two to form the slider 215. The surface on the front end side of the slider front part 215-2 is the front end surface 215-1 of the slider 215. When the slider 215 is in the reference position, the rear end surface 223 of the extension cylindrical portion 220 is flush with the joint surface 215-3 of the slider front portion 215-2.

[0138] As shown in FIG. 33, the slider front part 215-2 is provided with a rear end insertion hole 215-6. A part of the rear end of the extension cylindrical part 220, which protrudes from the middle insertion hole 213-2 toward the internal housing part 213-1, is inserted into the rear end insertion hole 215-6. The rear end insertion hole 215-6 penetrates the slider front part 215-2 along the second direction. The inner surface of the rear end insertion hole 215-6 is substantially circular, and more specifically, the inner surface of the hole is formed to match the outer periphery of the extension cylindrical part 220 inserted into the rear end insertion hole 215-6. In addition, the rear end insertion hole 215-6 is formed slightly larger than the outer periphery of the extension cylindrical part 220, and a slight gap is provided between the outer periphery and the inner surface of the rear end insertion hole 215-6.

[0139] A hole expansion portion 215-7 is provided over the entire circumferential area on the rear end side of the rear end insertion hole 215-6. The hole expansion portion 215-7 expands the hole from the inner surface of the rear end insertion hole 215-6 outward. The hole cross section of the hole expansion portion 215-7 is circular. The annular protrusion 224 provided at the rear end of the extension cylindrical portion 220 is housed in the hole expansion portion 215-7. The inner diameter of the opening cross section of the hole expansion portion 215-7 is larger than the outer diameter of the annular protrusion 224.

[0140] The depth (length in the second direction) L26 of the hole expansion portion 215-7 is the same as the length L25 in the second direction of the annular protrusion 224. Due to the difference between the opening diameter of the hole expansion portion 215-7 and the opening diameter of the rear end insertion hole 215-6, a restricting step surface 215-8 is formed on the front side of the hole expansion portion 215-7. The restricting step surface 215-8 is perpendicular to the second direction. The restricting step surface 215-8 is abutted against the annular step surface 225 of the annular protrusion 224, thereby restricting the extension cylindrical portion 220 from moving further forward relative to the slider front portion 215-2. With the annular step surface 225 of the extension cylindrical portion 220 in contact with the restriction step surface 215-8, the rear end surface 223 of the extension cylindrical portion 220 is flush with a joint surface 215-3 of the slider front portion 215-2 with the slider rear portion 215-4.

[0141] In addition, an inner surface groove 215-9 extending along the second direction is formed on the inner surface of the rear end insertion hole 215-6. As shown in FIG. 34, the inner surface groove 215-9 is provided at a position where the second extension portion 222 is disposed in the circumferential direction when the rear end insertion hole 215-6 is viewed from the rear side. The groove surface 215-10 of the inner surface groove 215-9 is an arc-shaped inner surface having the same diameter as the inner diameter of the hole expansion portion 215-7. The groove deep surface 215-11 forming the inner surface groove 215-9 is provided on the inner side of the restriction step surface 215-8 of the hole expansion portion 215-7 in the illustrated state. The groove deep surface 215-11 is perpendicular to the second direction (see FIG. 33). The extension cylindrical portion 220 is formed by alternately combining the first extension portion 221 and the second extension portion 222 in the circumferential direction. Because the inner surface groove portion 215-9 is provided, the regulating step surface 215-8 of the hole expansion portion 215-7 is arranged at a position where the first extension portion 221 is positioned, and the groove inner surface 215-11 of the inner surface groove portion 215-9 is arranged at a position where the second extension portion 222 is positioned, so that they are alternately arranged in the circumferential direction.

[0142] The circumferential length of the restricting step surface 215-8 of the hole expansion portion 215-7 and the groove deep surface 215-11 of the inner surface groove portion 215-9 are both approximately the same, and have a length equal to the total number of the first extension portions 221 and the second extension portions 222 constituting the extended cylindrical portion 220. In this embodiment, since four each of the first extension portions 221 and the second extension portions 222 are provided, the length is approximately equal to eight equal parts. The circumferential length of the inner surface groove portion 215-9 is longer than the length in the arc direction of the outer protrusion 222-4 of the second extension portion 222.

[0143] 33, when the slider 215 is in the reference position, not the entire annular step surface 225 of the annular protrusion 224 abuts against the restricting step surface 215-8, but only the protruding step surface 221-7 of the first extension portion 221 abuts against the restricting step surface 215-8. The protruding step surface 222-7 of the second extension portion 222 is disposed rearward of the groove deep surface 215-11 of the inner surface groove portion 215-9 and faces the groove deep surface 215-11 in a spaced-apart state.

[0144] The slider rear portion 215-4 has a core insertion hole 215-12 at its center. The core insertion hole 215-12 penetrates the slider rear portion 215-4 along the second direction, and has a substantially rectangular opening cross section with rounded corners as shown in Fig. 35. The opening cross section of the core insertion hole 215-12 is formed to be larger than the cross section of the core 240 protruding from the rear end surface 223 of the extension cylindrical portion 220 to the rear end side.

[0145] The joining surface 215-5 of the slider rear portion 215-4 is provided with a spring accommodating recess 215-13. The spring accommodating recess 215-13 is provided at a position where the second extension portion 222 is disposed when viewed from the front of the joining surface 215-5 of the slider rear portion 215-4. Therefore, four spring accommodating recesses 215-13 are provided on the joining surface 215-5. A coil spring 215-14 is provided inside the spring accommodating recess 215-13. As shown in FIG. 32, when the front end surface 232-4 of the second divided core 232 abuts against the back abutment surface 252 of the front end disc portion 250 and the rear end surface 222-8 of the second extension portion 222 is flush with the joining surface 215-5 of the slider rear portion 215-4, the coil spring 215-14 is provided in a compressed state. Therefore, the coil spring 215-14 biases the second split core 232 and the second extension portion 222 forward.

[0146] As shown in FIG. 34, a rear end recess 221-5 is formed at the rear end of the first extension portion 221 (see FIG. 29), so that the rear end does not interfere with the coil spring 215-14 accommodated in the spring accommodating portion 215-13.

[0147] (Disassembly and removal of the cylindrical core) With the above-described configuration, in the first demolding stage, the cylindrical core portion 230 is disassembled by the following operation and is demolded from the inner surface of the cylindrical cast part Z2 having a bottom.

[0148] At the beginning of demolding, the slider 215 abuts against the front plate portion 213-3 in the internal housing portion 213-1, as shown in Fig. 32. Also, as shown in Fig. 38(a), the first split core 231 and the second split core 232 form a cylindrical core portion 230, the inside of which is supported by the core portion 240. In the cylindrical core portion 230, the split side surface 231-3 of the first split core 231 and the split side surface 232-3 of the second split core 232 abut against each other with no gap between them.

[0149] In the first demolding stage, as shown in Fig. 36, the main body 210 is not moved, and only the slider 215 is moved back from the reference position along the second direction. As shown in Fig. 33, when the slider 215 is arranged at the reference position, the protruding step surface 221-7 of the first extension 221 abuts against the restricting step surface 215-8 of the hole expansion portion 215-7. Therefore, when the slider 215 moves back from the reference position along the second direction, as shown in Fig. 36, the abutment of the step surfaces 221-7 and 215-8 causes the first extension 221 to move back in the direction in which the extended inner inclined surface 221-2 is inclined along the inner surface of the front insertion hole 214-3 and the first support surface 241 of the core 240. The moving back direction of the first extension 221 is not parallel to the second direction in which the slider 215 moves. However, the inclination angle θ2 of the first extension portion 221 in the retreating direction is set to 2 degrees with respect to the second direction, and since the inclination angle θ2 is relatively small, even if the slider 215 retreats in the second direction, the first extension portion 221 can retreat diagonally, guided by the inner surface of the front insertion hole 214-3 and the first support surface 241 of the core portion 240.

[0150] As shown in Fig. 33, when the slider 215 is in the reference position, the protruding step surface 222-7 of the second extension portion 222 does not face the restricting step surface 215-8 of the hole expansion portion 215-7. In addition, the protruding step surface 222-7 of the second extension portion 222 does not abut against the groove deep surface 215-11 of the inner surface groove portion 215-9 in the slider front portion 215-2, but faces each other at a distance. As shown in Fig. 32, the second split core 232 and the second extension portion 222 are biased forward by the coil spring 215-14, and the biasing force maintains the front end surface 232-4 of the second split core 232 in abutment against the front end disc portion 250. Therefore, even if the slider 215 starts to retract from the reference position, the second extension portion 222 does not retract, and as shown in Fig. 36, the front end surface 232-4 of the second split core 232 remains in contact with the front end disk portion 250. As a result, only the first extension portion 221 retracts as the slider 215 moves.

[0151] As the first extension portion 221 retreats, the first split core 231, while maintaining its posture relative to the central axis C2, retreats while dropping inward (toward the central axis C2) in the direction in which the second extension portion 222 moves, as shown in Fig. 38(b). At this time, the first split core 231 maintains a state in which a virtual line VL22 extending in the longitudinal direction at the center in the width direction is parallel to the central axis C2. Furthermore, when a virtual cross section VF23 is imagined that includes the virtual line VL22 and extends in the radial direction of the arc on the outer arc-shaped surface 231-1, the central axis C2 is also maintained in an extension of the virtual cross section VF23.

[0152] The first split core 231 and the first extension portion 221 have a tapered shape overall, while the second split core 232 and the second extension portion 222 are formed to have a shape that becomes wider overall toward the front end. In addition, as shown in Figures 29 and 30, the split side surfaces 231-3, 232-3 of the split cores 231, 232 and the extended side surfaces 221-3, 222-3 of the extension portions 221, 222 are formed to form an angle α2 with respect to the imaginary planes VF1, VF2.

[0153] 38(b), even if the second split core 232 and the second extension portion 222 are arranged in their original positions, when the first split core 231 and the first extension portion 221 sink and retreat, a gap G2 is formed between the split side surfaces 231-3, 232-3 and between the extended side surfaces 221-3, 222-3. This gap G2 enables the first split core 231 and the first extension portion 221 to sink inward and retreat.

[0154] The first split core 231 and the first extension portion 221 recede while their inner inclined surface 231-2 and extended inner inclined surface 221-2 come into contact with the first support surface 241 of the core portion 240. The first split core 231 sinks into the front insertion hole 214-3 of the main body front portion 214 by an amount that the first split core 231 and the first extension portion 221 recede while dropping inward. In addition, the front end surface 231-4 of the first split core 231 moves away from the front end disk portion 250. As a result, the first split core 231 is released from the inner surface of the bottomed cylindrical cast part Z2, and the cylindrical core portion 230 is disassembled.

[0155] Thereafter, when the slider 215 is further moved backward, the first extension portion 221 and the first divided core 231 move backward together with the slider 215, while the distance between the protruding step surface 222-7 of the second extension portion 222 and the groove deep surface 215-11 of the inner surface groove portion 215-9 gradually decreases, and the two come into contact as shown in Fig. 36. During that time, the compressed coil spring 215-14 gradually expands while maintaining the forward biasing force. After the protruding step surface 222-7 of the second extension portion 222 comes into contact with the groove deep surface 215-11 of the inner surface groove portion 215-10, the slider 215 is further moved backward from there.

[0156] 37, the second extension 222 moves back along the inner surface of the front insertion hole 214-3 and the second support surface 242 of the core 240 in the direction in which the extended inner inclined surface 222-2 is inclined, due to the abutment of the protruding step surface 222-7 and the groove deep surface 215-11. The retraction direction of the second extension 222 is also non-parallel to the second direction in which the slider 215 moves. However, since the inclination angle θ2 of the retraction direction of the second extension 222 is set to 2 degrees with respect to the second direction and the inclination angle θ2 is small, even if the slider 215 moves back in the second direction, the second extension 222 can move back obliquely while being guided by the inner surface of the front insertion hole 214-3 and the second support surface 242 of the core 240.

[0157] As the second extension 222 retreats, the second split core 232, while maintaining its posture relative to the central axis C2, retreats inward (toward the central axis C2) in the direction in which the second extension 222 moves, as shown in FIG. 38(c). At this time, the second split core 232 maintains a state in which a virtual line VL26 extending in the longitudinal direction at the center of the width direction is parallel to the central axis C2. Furthermore, when a virtual section VF24 including the virtual line VL26 and extending in the radial direction of the arc on the outer arc-shaped surface 232-1 is assumed, the central axis C2 is maintained on the extension of the virtual section VF24. In this case, the first extension 221 and the first split core 231 retreat first, and a gap G2 is formed between the divided side surfaces 231-3, 232-3 and between the extended side surfaces 221-3, 222-3, as shown in FIG. 38(b). Using this gap G2, the second split core 232 and the second extension portion 222 can retreat while dropping inward, as shown in FIG. 38(c).

[0158] The second split core 232 retreats while its inner inclined surface 232-2 abuts against the second support surface 242 of the core portion 240. The second split core 232 sinks into the front insertion hole 214-3 by the amount that the second split core 232 retreats while dropping inward. In addition, the front end surface 231-4 of the first split core 231 moves away from the front end disk portion 250. As a result, the second split core 232 is released from the inner surface of the bottomed cylindrical cast part Z2. As a result, the entire cylindrical core portion 230 is disassembled.

[0159] (Second stage of demolding) After the above-mentioned first demolding stage is completed, in the second demolding stage, the main body 210 of the slide die 203 is retracted. Since the outer periphery 256 of the front end disk portion 250 has a draft angle, the front end disk portion 250 is also demolded from the cast part Z2 by the retraction of the main body 210. This completes the demolding from the bottomed cylindrical cast part Z2. After the demolding, the excess material in the area where the front end disk portion 250 was located is removed from the inner surface of the cast part Z2 to make the inner surface have the same inner diameter.

[0160] (Mold clamping operation) When casting is to be performed again after the cast part Z2 is removed, a mold clamping operation is performed which is the reverse of the mold releasing operation described above. In the mold clamping operation, the first mold 201 and the second mold 202 are moved in a direction approaching each other to form a molding space 204. At the same time or at a different time, the slide mold 203 in the retreated position is advanced. At this time, the slider 215 is advanced and returned to the reference position. As shown in FIG. 37, which illustrates a state in which the cast part Z2 is not present, and in FIG. 38(c), at the beginning of mold clamping, the first split core 231 and the second split core 232 are separated from the front end disk portion 250. From there, the slider 215 is advanced.

[0161] Then, in the first split core 231, the rear end surface 221-8 of the first extension portion 221 abuts against the joint surface 215-5 of the slider rear portion 215-4 with the slider front portion 215-2. Therefore, the first split core 231 advances while gradually spreading outward along the inner surface of the front insertion hole 214-3 and the first support surface 241 of the core portion 240. Also, in the second split core 232, the protruding step surface 222-7 of the outer protruding portion 222-4 of the second extension portion 222 is maintained in abutment against the groove deep surface 215-11 of the inner surface groove portion 215-9 of the slider front portion 215-2 by the biasing force of the coil spring 215-14. Therefore, the second split core 232 also advances while gradually spreading outward along the inner surface of the front insertion hole 214-3 and the second support surface 242 of the core portion 240.

[0162] In Fig. 36, it is assumed that the cast part Z2 is not present. As shown in this and Fig. 38(b), when the slider 215 is further advanced, the front end surface 232-4 of the second split core 232 first comes into contact with the back abutment surface 252 of the front end disk portion 250. As a result, the second split core 232 is disposed in a position to form the cylindrical core portion 230. When the slider 215 is further advanced from there, the slider 215 advances while compressing the coil spring 215-14. At this time, the groove deep surface 215-11 of the inner groove portion 215-9 of the slider front portion 215-2 gradually moves away from the protruding step surface 222-7 of the outer protruding portion 222-4 of the second extension portion 222.

[0163] Next, as shown in Figures 32 and 38(a), when the slider 215 returns to the reference position, the front end surface 231-4 of the first split core 231 abuts against the back abutment surface 252 of the front end disk portion 250. As a result, the first split core 231 is positioned to form the cylindrical core portion 230 together with the second split core 232. In the slide die 203, the cylindrical core 205 protrudes from the front insertion hole 214-3 of the main body portion 210. As the slide die 203 advances, the cylindrical core 205 is placed in the molding space 204, and a bottomed cylindrical cavity 206 is formed. By introducing molten metal into the bottomed cylindrical cavity 206, a cast part Z2 having a bottomed cylindrical shape is cast.

[0164] According to the mold apparatus 200 of the second embodiment described above in detail, the following effects can be obtained.

[0165] (1) When the cylindrical core portion 230 is released from the inner surface of the cast part Z2, the first split core 231 and the second split core 232 forming the cylindrical core portion 230 recede while dropping toward the central axis C2 while maintaining their posture with respect to the central axis C2 of the cylindrical core portion 230. In this case, since the first split core 231 and the second split core 232 are not receded along the central axis C2 of the bottomed cylindrical cavity 206, the first split core 231 and the second split core 232 can be released even if a draft is not formed on the outer periphery of the cylindrical core portion 230. As a result, at least in the portion where the cylindrical core portion 230 is provided, it is not necessary to cut off the excess material after casting to make the inner surface of the cast part Z2 have the same inner diameter, which contributes to reducing manufacturing costs.

[0166] A draft is provided on the outer periphery 256 of the front end disk portion 250 constituting the cylindrical core 205. However, the front end disk portion 250 is provided at the front end portion of the cylindrical core 205, and most of the cylindrical core 205 is occupied by the cylindrical core portion 230. Compared to the conventional technology in which a draft is provided on the entire outer periphery of the core, even if there is a draft on only a part of the bottom side of the cast part Z1, it can contribute to reducing manufacturing costs.

[0167] (2) A core portion 240 is provided at the center of the cylindrical core portion 230, and the core portion 240 is also a component that forms the cylindrical core 205. The cylindrical core portion 230 is supported from the inner circumferential side by the core portion 240. Therefore, even if the cylindrical core portion 230 is tightened due to contraction when the molten metal solidifies, the cylindrical state formed by combining the first split core 231 and the second split core 232 can be maintained.

[0168] (3) The slide die 203 is provided with the first split core 231 and the second split core 232. In the second direction, which is the moving direction of the slide die 203, the first split core 231 and the second split core 232 are configured to be retracted from the bottomed cylindrical cavity 206 toward the same side. In this way, since the first split core 231 and the second split core 232 are retracted toward the same side, it is possible to provide the molding rear surfaces 201c, 202c in the bottomed cylindrical cavity 206 on the side opposite to the side where the two split cores 231, 232 retract. By providing the molding rear surfaces 201c, 202c, the bottomed cylindrical cavity 206 is formed, and the cast part Z2 having a bottomed hollow portion can be manufactured.

[0169] (4) A front end disk portion 250 is provided on the front end side of the cylindrical core portion 230, and the cylindrical core 205 is formed including this front end disk portion 250 together with the cylindrical core portion 230 and the core portion 240. The front end disk portion 250 abuts against a front end surface 233 of the cylindrical core portion 230, and the center portion of the cylindrical core portion 230 is blocked by the front end disk portion 250. This makes it possible to prevent molten metal from entering between the first split core 231 and the second split core 232 forming the cylindrical core portion 230 from the front end side of the cylindrical core portion 230 and into the internal space of the cylindrical core portion 230 when molten metal is poured into the bottomed cylindrical cavity 206.

[0170] (5) An annular front end projection 234 is provided on the front end surface 233 of the cylindrical core portion 230, and a cylinder holding groove 253 is provided on a back abutment surface 252 of the front end disk portion 250 which abuts against the front end surface 233. The front end projection 234 is inserted into the cylinder holding groove 253, and the arcuate projection surfaces 231-6, 232-6 of the front end projection 234 abut against an outer periphery groove inner surface 254 of the cylinder holding groove portion 253, and the inclined projection surfaces 231-7, 232-7 of the front end projection 234 abut against an inner periphery groove inner surface 255 of the cylinder holding groove portion 253. This positions the first split core 231 and the second split core 232, and the cylindrical shape of the cylindrical core portion 230 can be held more reliably.

[0171] (6) The outer periphery 256 of the front end disk portion 250 is provided with a draft gradient for pulling the front end disk portion 250 toward the side where the first split core 231 and the second split core 232 recede. This makes it easier to pull the front end disk portion 250 out of the hollow portion of the cast part Z2. As described above, even if the outer periphery 256 of the front end disk portion 250 has a draft gradient, unlike the prior art in which a draft gradient is provided over the entire inner surface of the hollow portion, the front end disk portion 250 is provided only on a part of the bottom side of the hollow portion. Therefore, the problem of increased manufacturing costs of the cast part Z2 due to the presence of a draft gradient can be sufficiently improved.

[0172] (7) The moving mechanism for moving the first split core 231 and the second split core 232 backward has the following configuration. The first split core 231 has a first extension 221 and the second extension 222 has a second extension 222. The first extension 221 and the second extension 222 are combined to form the extended cylindrical portion 220. The extended cylindrical portion 220 is supported from its inner circumferential surface by a portion extended from the core 240 at the center of the extended cylindrical portion 220. The main body 210 of the slide die 203 is provided with a middle through-hole 213-2 and a front through-hole 214-3 through which the extended cylindrical portion 220 is inserted. The first extension 221 and the second extension 222 move while being guided by the inner surface of the front through-hole 214-3 and the core 240, respectively. Accordingly, the first split core 231 and the second split core 232 can retreat while dropping toward the central axis C2 while maintaining their respective postures.

[0173] (8) The first split core 231 and the first extension 221 have a tapered shape as a whole, and the second split core 232 and the second extension 222 have a shape that gradually becomes wider as a whole. The split side surfaces 231-3, 232-3 and the extended side surfaces 221-3, 222-3 are set to form an angle α2 with respect to the imaginary plane VF21. Therefore, if the first split core 231 and the first extension 221 retreat while dropping toward the center axis C2 before the second split core 232 and the second extension 222, a gap G2 is generated between the split side surfaces 231-3, 232-3 and the extended side surfaces 221-3, 222-3. The generation of the gap G2 allows only the first split core 231 and the first extension 221 to retreat while dropping toward the center axis C2.

[0174] (9) To disassemble the cylindrical core portion 230, as described in (8) above, not only is it necessary to set the angles of the divided side surfaces 231-3, 232-3 and the extended side surfaces 221-3, 222-3, but it is also necessary to move the first divided core 231 and the first extended portion 221 back before the second divided core 232 and the second extended portion 222. Therefore, in this embodiment 2, when the slider 215 is in the reference position, the protruding step surface 221-7 of the first extended portion 221 abuts against the restricting step surface 216-8 of the slider 215 that faces it, while the protruding step surface 222-7 of the second extended portion 222 is separated from the groove inner surface 215-11 of the slider 215 that faces it. In addition, the second divided core 232 and the second extended portion 222 are biased forward inside the slider 215.

[0175] Because such a configuration is adopted, when the slider 215 retracts, the first split core 231 and the first extension portion 221 retract together with the slider 215, and the second split core 232 and the second extension portion 222 maintain a state of abutting against the front end disk portion 250. When the slider 215 retracts further and the protruding step surface 222-7 of the second extension portion 222 abuts against the groove deep surface 215-11 of the slider 215, thereafter the second split core 232 and the second extension portion 222 also retract together with the slider 215. In other words, the first split core 231 and the first extension portion 221 can be retracted before the second split core 232 and the second extension portion 222.

[0176] The mold device 200 of the second embodiment is not limited to the above-described configuration, and may be modified, for example, as follows.

[0177] (a) In the above die device 200, a cooling mechanism for cooling the cylindrical core portion 230 is omitted. When a cooling mechanism is provided, for example, a refrigerant passage for circulating a refrigerant may be provided inside each of the first split core 231 and the second split core 232. In this case, a passage communicating with the refrigerant passage is also provided in the first extension portion 221 and the second extension portion 222, and a refrigerant is supplied to these passages from the outside. A refrigerant passage may also be provided in the core portion 240.

[0178] (b) In the above die device 200, a mechanism is employed in which the rear ends of the first extension portion 221 and the second extension portion 222 are connected to the slider 215, and the first divided core 231 and the second divided core 232 are moved backward or shifted by the movement of the slider 215. Alternatively, a mechanism may be employed in which a cylinder or other known driving means is connected to each of the first extension portion 221 and the second extension portion 222, and the operation is controlled individually.

[0179] (c) A die assembly 200 of a second embodiment is for casting a cast part Z2 which is a bottomed cylindrical member. When casting a bottomed cylindrical part provided as a part of the cast part after changing the configurations of a first die 201 and a second die 202, the configuration of a slide die 203 having a cylindrical core 205 may be applied. (d) In the die device 200 of the second embodiment, the circumferential lengths of the regulating step surface 215-8 of the hole expansion portion 215-7 and the groove deep surface 215-11 of the inner surface groove portion 215-9 are both set to be approximately the same. However, they are not always set to be approximately the same, and may vary depending on the dimensions of the cylindrical core portion 230 and the number of divisions. [Explanation of symbols]

[0180] (Embodiment 1) 101...first mold, 102...second mold, 103...first slide mold, 104...second slide mold, 107...cylindrical cavity, 110...first main body portion, 113...first slider, 114-2...first guide hole, 130...first extension portion, 131...extended outer arcuate surface, 132...extended inner inclined surface, 133...extended side surface, 140...second main body portion, 143...second slider, 144-2... 2nd guide hole, 160...2nd extension part, 170...cylindrical core part, 171...1st split core, 171-1...outer arcuate surface, 171-2...inner inclined surface, 171-3...divided side surface, 172...2nd portion Split core, 172-1...outer arcuate surface, 172-2...inner inclined surface, 172-3...divided side surface, 180...core (inner support part), C1...center axis line, VF11...imaginary plane, VL12...imaginary line.

[0181] (Embodiment 2) 201...first mold, 202...second mold, 206...bottomed cylindrical cavity, 210...main body, 213-2...middle insertion hole (cylindrical portion insertion hole), 214-3...front insertion hole (cylindrical portion insertion hole), 215...slider, 220...extended cylindrical portion, 221...first extension portion, 221-1...extended outer arc surface, 221-2...extended inner inclined surface, 221-3...extended side surface, 222...second extension portion, 222-1...extended outer arc surface, 222-2...extended inner inclined surface, 222-3...extended side surface, 230...cylindrical core portion, 2 31...first split core, 231-1...outer arcuate surface, 231-2...inner inclined surface, 231-3...divided side surface, 232...second split core, 232-1...outer arcuate surface, 232-2...inner inclined surface, 232-3...divided side surface, 234...front end protrusion (shape retention) 240...Core part (inner support part, extension inner support part), 250...Front end disk part (disc-shaped core part), 253...Cylinder holding groove part (shape holding groove part), C2...Central axis line, VF21...Virtual plane (virtual side surface), VL22, VL26...Virtual line.

Claims

1. A die apparatus including a first die, a second die, and a cylindrical core portion having an inner peripheral surface and an outer peripheral surface formed by combining a plurality of split cores, the die apparatus being configured to form a cylindrical cavity by combining the first die, The cylindrical core portion is a plurality of first split cores arranged at predetermined intervals in a circumferential direction; a plurality of second split cores disposed between the first split cores; The first split cores and the second split cores are alternately combined to form the first split cores, the first split core and the second split core each have an outer arcuate surface that forms the outer circumferential surface of the cylindrical core portion, A mold device equipped with a split core moving mechanism which, during demolding, moves the first split core and the second split core diagonally back toward the central axis of the cylindrical core portion while maintaining their orientation relative to the central axis of the cylindrical core portion to disassemble the cylindrical core portion, or moves them forward from the backed up position to form the cylindrical core portion.

2. A pair of slide dies are provided so as to be movable in a direction in which the first die and the second die approach and separate from each other in a direction perpendicular to the direction in which the first die and the second die approach and separate from each other, the first split core is provided in a first slide die which is one of the pair of slide dies and protrudes toward a second slide die which is the other of the pair of slide dies; The second split core is provided in the second slide die and protrudes toward the first slide die, the cylindrical core portion is formed by combining the first split core of the first slide die and the second split core of the second slide die, The die apparatus according to claim 1 , wherein the split core moving mechanism is provided for each of the slide dies.

3. 3. The mold apparatus according to claim 2, wherein the center of the cylindrical core portion is provided with an inner support portion that abuts against the inner circumferential surfaces of the first split core and the second split core and supports the cylindrical core portion from the inner circumferential surface side.

4. A first split core moving mechanism provided in the first slide die and moving the first split core backward or forward, and a second split core moving mechanism provided in the second slide die and moving the second split core backward or forward, an extension portion provided on the first split core or the second split core and extending along the respective moving directions; a guide hole provided in a main body of the first slide die or the second slide die, the guide hole allowing the extension portion to pass therethrough and guiding the movement of the extension portion; a slider provided in the main body portion so as to be movable along a direction in which the pair of slide dies approach and separate from each other independently of the main body portion, the slider being connected to a rear end portion of the extension portion; Equipped with 4. The mold apparatus according to claim 3, wherein the slider is connected to the extension with a play that allows the extension to move obliquely toward the central axis.

5. The first split core and the second split core are tapered toward a protruding direction, and each of them has the outer arcuate surface, a flat inner inclined surface inclined along the direction of movement; A pair of divided side surfaces provided so as to approach each other in a protruding direction; The cross section is formed to be an annular sector shape, The extension portion is an extended outer arcuate surface that is extended from a boundary with the outer arcuate surface and inclines along an inclination angle of the inner inclined surface while maintaining the arc of the outer arcuate surface; an extended inner inclined surface that is flush with the inner inclined surface; A pair of extended side surfaces extending from the boundary between the pair of divided side surfaces and extending at equal intervals; The cross section is formed to be an annular sector shape, the split side surfaces of adjacent split cores are brought into contact with each other to form the cylindrical core portion, The mold apparatus according to claim 4, wherein when the inclination angle of the inner inclined surface is A and the numbers of the first divided core and the second divided core are the same N, an angle α1 of the divided side surface with respect to a virtual plane along the extended side surface satisfies the following mathematical formulas (1) and (2). (1) tanA×sin(360° / 4N)=tanB (2) α1>B

6. The mold apparatus according to claim 1, wherein the core moving mechanism retracts the first split core and the second split core to the same side in a direction perpendicular to the direction in which the first mold and the second mold are brought together and separated.

7. The mold apparatus according to claim 6, wherein the center of the cylindrical core portion is provided with an inner support portion that abuts against the inner circumferential surfaces of the first split core and the second split core and supports the cylindrical core portion from the inner circumferential surface side.

8. 7. The die apparatus according to claim 6, wherein the cylindrical core portion is provided with a disk-shaped core portion on an end face opposite to a side where the first split core and the second split core retract.

9. a ring-shaped shape-retaining protrusion provided on the end surface of the cylindrical core portion and formed along a circumferential direction of the cylinder; a circular shape-retaining groove portion, the circular shape-retaining groove portion being provided on a contact surface of the cylindrical core portion with the end surface, into which the shape-retaining protrusion portion is inserted; The mold apparatus according to claim 8 , comprising:

10. 9. The die apparatus according to claim 8, wherein an outer periphery of the disk-shaped core portion is provided with a draft slope for withdrawing the disk-shaped core toward the side where the first split core and the second split core recede.

11. The core moving mechanism includes: a first extension portion provided on the first split core so as to extend along the moving direction of the first split core; a second extension portion provided on the second split core so as to extend along the moving direction of the second split core; an extended cylindrical portion formed by alternatingly combining a plurality of the first extended portions and a plurality of the second extended portions in a circumferential direction and having an inner circumferential surface and an outer circumferential surface; A main body portion into which the extension cylindrical portion is inserted; a cylindrical portion insertion hole provided in the main body portion and having an inner surface that abuts against the outer circumferential surface; an extended inner support portion which is an extended portion of the inner support portion and is provided at a center of the extended cylindrical portion, and which abuts against the inner circumferential surfaces of the first extension portion and the second extension portion to support the extended cylindrical portion from the inner circumferential surface side; a slider connected to the extended cylindrical portion on a side opposite to a side on which the first split core and the second split core are provided, the slider being movable in a direction perpendicular to the approaching and separating direction; Equipped with The mold apparatus according to claim 7 , wherein the movements of the first extension portion and the second extension portion are guided by the inner surface of the cylindrical portion insertion hole and the extended inner support portion.

12. The first split core and the second split core each have the outer arcuate surface, a flat inner inclined surface inclined along the direction of movement; A pair of split sides; The cross section is formed to be an annular sector shape, The first extension portion and the second extension portion each have an extended outer arcuate surface extending from a boundary with the outer arcuate surface and forming an outer circumferential surface of the extended cylindrical portion; an extended inner inclined surface that is flush with the inner inclined surface; A pair of extended side surfaces that are flush with the pair of divided side surfaces; The cross section is formed to be an annular sector shape, The first split core and the first extension portion have a shape that gradually tapers from a rear end of the first extension portion toward a front end of the first split core, The second split core and the second extension portion have a shape that gradually becomes wider from a rear end of the second extension portion toward a front end of the second split core, The split side surfaces of adjacent split cores are brought into contact with each other to form the cylindrical core portion, The extended cylindrical portion is formed by the extended side surfaces of the adjacent extended portions being in contact with each other, In the first split core and the first extension portion or the second split core and the second extension portion, the inclination angle of the inner inclined surface and the extended inner inclined surface, respectively, is defined as A, the number of the first split cores and the number of the second split cores, respectively, is defined as N, the amount of movement of the first split core is defined as C, and the amount of movement of the second split core is defined as D, Assuming that the cylindrical core portion is equally divided into 2N parts by a virtual surface in a radial direction passing through the center of the cylindrical core portion, and further assuming virtual side surfaces of each virtual divided body formed thereby, The mold apparatus according to claim 11 , wherein an angle α2 of the divided side surface and the extended side surface with respect to a virtual plane along the virtual side surface satisfies the following formulas (1) and (2). (1) (C+D) x tanA x sin (360° / 4N) / (C-D) = tanB (2) α2>B

13. The die apparatus according to claim 12 , wherein the core moving mechanism retracts the second split core and the second extension portion later than the first split core and the first extension portion.

Images