Injection molding device

Abstract

The problem to be solved by the present invention is to provide an injection molding device capable of injection molding a cylindrical molded article having a fixed inner diameter by using a core having a simple structure and having no mold draft. In order to solve the problem, the present invention provides an injection molding device for injection-molding a cylindrical molded article having a fixed inner diameter, the injection molding device being provided with: a first mold and a second mold for forming a cavity in a closed state; a first core and a second core formed by dividing a cylindrical core disposed in the cavity, the first core and the second core having a dividing surface inclined with respect to the axial direction of the core and divided from one end to the other end of the cavity in the axial direction; and a sliding mechanism for sliding the first core or the second core to be inserted into and pulled out of the cavity. The sliding mechanism causes the first core or the second core to slide in a direction in which an angle with respect to the axial center direction is greater than 0 degree and less than the inclination angle of the dividing surface in a cross-sectional view that includes the axial center and is orthogonal to the dividing surface.

Description

Technical Field

[0001] The present invention relates to an injection molding device. Background Art

[0002] In the injection molding method, a fluid material such as molten resin injected from an injection machine is filled into a cavity formed by closing a mold, and the fluid material is cooled and solidified to form a molded product corresponding to the shape of the cavity.

[0003] When forming a cylindrical part with a fixed inner diameter, a core is used in addition to the mold to form the hollow part of the cylindrical part. Specifically, a cylindrical core with the same shape as the hollow part is set in the mold, and a fluid material is filled in the cavity formed between the mold and the core, and the material is cooled and solidified. Thereafter, the core is extracted from the molded product to form the hollow part.

[0004] In the past, cores required a draft. This is to facilitate the removal of the core from the molded product by providing a tapered surface in the axial direction of the cylindrical core and pulling the core from the large diameter side with a large cross-sectional area in a direction perpendicular to the axial direction. In addition, this is because materials such as resins shrink in volume as they cool and fit tightly to the mold or core, so it is difficult to demold a straight core with a fixed outer diameter that contacts the material.

[0005] The hollow part of the same diameter cylindrical component formed by using a core provided with a draft angle has a tapered surface. Therefore, in the case of a product having a straight through hole such as a pipe, another process such as boring machining is required.

[0006] Therefore, a die casting machine is proposed, which comprises: a first hole-forming pin having a left-right symmetrical tapered surface and a convex portion provided in the middle of the tapered surface; and a second hole-forming pin provided on both sides of the first hole-forming pin, having tapered surfaces with the same inclination as the tapered surface on the inner circumference, and having a concave portion that engages with the convex portion of the first hole-forming pin to limit the relative movement of the two pins (see Patent Document 1). According to this technology, the hole-forming pin can be easily pulled out without providing a draft angle, and other processes such as boring machining are not required.

[0007] [Prior Technical Literature]

[0008] (Patent Document)

[0009] Patent Document 1: Japanese Patent Application Publication No. 2002-346723 Summary of the invention

[0010] [Problems to be solved by the invention]

[0011] However, in the technology of Patent Document 1, the drilling pin must be composed of a complicated component divided into three.

[0012] An object of the present invention is to provide an injection molding device that can injection mold a cylindrical molded product with a constant inner diameter by using a core with a simple structure and no draft.

[0013] [Technical means to solve the problem]

[0014] (1) An injection molding device of the present invention (e.g., an injection molding device 1 described later) performs injection molding on a cylindrical molded product (e.g., a molded product P described later) having a fixed inner diameter, and comprises: a first mold (e.g., a first mold 21 described later) and a second mold (e.g., a second mold 22 described later) that form a cavity (e.g., a cavity C described later) in a mold clamping state;

[0015] The first core (for example, the first core 41 described later) and the second core (for example, the second core 42, 42B described later) are formed by dividing a cylindrical core (for example, the divided core 4 described later) arranged in the aforementioned cavity, and have a dividing surface (for example, the dividing surface 411, 421, 421B described later) inclined relative to the axial direction of the aforementioned core (for example, the axial center O1 described later) and dividing from one end of the aforementioned cavity in the aforementioned axial direction to the other end; and,

[0016] A sliding mechanism (e.g., the sliding mechanism 3 described later) causes the first core or the second core to slide and move to be inserted or removed from the cavity;

[0017] The sliding mechanism causes the first core or the second core to slide in a direction (for example, arrow SD described later) within a range where the angle formed with the axis direction exceeds 0 degrees and is less than the inclination angle of the dividing surface (for example, angle r1-1 or angle r1-2 described later) in a cross-section view including the axis and orthogonal to the dividing surface.

[0018] In the present device, a first core and a second core are used to divide a cylindrical core arranged in a cavity, and the core has a dividing surface that is inclined relative to the axial direction of the core and divides the cavity from one end to the other end in the axial direction. In this way, the core can be divided and slid. In addition, in the present device, there is a sliding mechanism, which allows the first core or the second core to slide in a direction within a range where the angle with the axial direction exceeds 0 degrees and is less than the inclination angle of the dividing surface in a cross-section that includes the axis and is orthogonal to the dividing surface. Thus, by moving the core in the direction within the above range, a gap is generated between the molded product and the core, similarly to a core provided with a draft angle, so that the core can be smoothly pulled out of the molded product.

[0019] (2) The injection molding device according to (1) above, further comprising an air supply mechanism (for example, the air supply mechanism 6 described later) for supplying air to the divided surface.

[0020] In this device, by supplying air to the divided surfaces of the two split cores formed by splitting the core by the air supply mechanism, the divided surfaces can be moved away from each other more quickly, so that the core can slide smoothly and be pulled out from the molded product.

[0021] (3) An injection molding device according to the above (2), wherein at least one of the above-mentioned first core and the above-mentioned second core has a groove portion (for example, the groove portions 51 and 52 described later) in the axial direction of the above-mentioned dividing surface, and the above-mentioned air supply mechanism supplies air to the above-mentioned groove portion.

[0022] In the present device, by providing a groove on the dividing surface of at least one of the two cores, air can be supplied from one end of the core to the other end in the same manner through the groove. Therefore, the dividing surfaces can be more effectively moved away from each other, so that the core can slide more smoothly and be pulled out from the molded product.

[0023] (Effects of the Invention)

[0024] According to the present invention, a cylindrical molded product having a constant inner diameter can be injection molded by using a core having a simple structure without a draft angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a perspective view showing the external appearance structure of the injection molding device according to the first embodiment.

[0026] Figure 2 It is an exploded perspective view of a molded product and split cores molded by the injection molding apparatus according to the first embodiment.

[0027] Figure 3 It shows the state of the material being cured. Figure 1 Cross-sectional view along line III-III.

[0028] Figure 4 is Figure 3 A cross-sectional view showing the sliding direction of the sliding mechanism is shown in FIG.

[0029] Figure 5 It is a cross-sectional view showing a state where the split core is slid.

[0030] Figure 6 It is a perspective view showing the external appearance structure of the injection molding device according to the second embodiment. DETAILED DESCRIPTION

[0031] [First embodiment]

[0032] Hereinafter, the injection molding device of the first embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, the axis of the split core 4, the axis of the cavity C and the axis of the molded product P in the injection molding device of this embodiment are the same, so these axes are set as the axis O1 for description below.

[0033] Figure 1 1 is a perspective view showing the appearance structure of the injection molding device 1 according to the first embodiment. Figure 1 In FIG. 1 , the mold 2 is shown by a double-dashed virtual line. The outer shape of the mold 2 is a structure divided into two and is not limited to a cubic shape. The inner shape of the mold 2 after the mold is closed corresponds to the shape of the cavity C.

[0034] The injection molding device 1 includes a mold 2 , a cavity C, a split core 4 , and a slide mechanism 3 .

[0035] The mold 2 is composed of a fixed mold and a movable mold that can move forward and backward relative to the fixed mold, namely a first mold 21 and a second mold 22. In the present embodiment, any mold can be both a fixed mold and a movable mold. A cavity C is formed between the first mold 21 and the second mold 22 as a hollow space for filling with a molding material ejected from an injection machine not shown in the figure. The molding material injected from the resin injection port not shown in the figure provided in the mold 2 is filled in the cavity C through the sprue, runner and gate not shown in the figure provided in the mold 2. The molding material filled in the cavity C is cooled and solidified, and the molded product P is formed.

[0036] Figure 2 It is an exploded perspective view of a molded product P and a split core 4 molded by the injection molding device 1 .

[0037] like Figure 2 As shown, the molded product P of this embodiment is a cylindrical component. The cylindrical molded product P with a constant inner diameter has a through hole Ph, and the wall thickness of the molded product P is uniform. The cavity C is a cylindrical shape that is the same as the outer shape of the molded product P.

[0038] return Figure 1 The split core 4 is formed by splitting a cylindrical core. Figure 1 As shown, the split core 4 is a combination of a first core 41 and a second core 42 in contact with each other and is arranged in the cavity C. The center portion of the split core 4 in the combined state is a cylindrical shape having the same shape as the through hole Ph of the molded product P and a constant outer diameter.

[0039] like Figure 2As shown, the first core 41 has a dividing surface 411 inclined with respect to the axial direction of the molded product P, a bottom surface 412, and an upper surface 413. The second core 42 has a dividing surface 421 inclined with respect to the axial direction of the molded product P, a horizontal portion 422 continuous with the dividing surface 421, and an upper surface 423. The dividing surface 421 of the second core 42 is a surface of the same shape as the dividing surface 411 of the first core 41, and is an inclined surface that can abut against the dividing surface 411 without a gap.

[0040] The sliding mechanism 3 has the following function, namely, to slide the first core 41 or the second core 42 in a cross-section including the axis O1 and orthogonal to the aforementioned dividing plane in a direction in which the angle formed with the axis O1 direction exceeds 0 degrees and is less than the inclination angle of the aforementioned dividing plane. The sliding mechanism 3 is connected to the lower end of the second core 42 to slide the second core 42. As a specific example, an air cylinder or a hydraulic cylinder can be envisioned, but it is not limited to these, and any mechanism can be applied as long as it has the function of sliding the core.

[0041] Next, a specific method of injection molding a cylindrical molded product P having a constant inner diameter using the split core 4 having a simple structure without a draft angle by the injection molding apparatus 1 configured as above will be described.

[0042] Figure 3 yes Figure 1 The III-III line cross-sectional view is a cross-sectional view including the axis O1 and perpendicular to the aforementioned dividing plane. The cross-sectional view shows a state where the molding material injected from the resin injection port (not shown) provided in the mold 2 is solidified in the cavity C.

[0043] like Figure 3 As shown, the split surface 411 of the first core 41 abuts against the split surface 421 of the second core 42 without a gap, and abuts against the bottom surface 412 of the first core 41 in a manner covering the horizontal portion 422 of the second core 42. The split core 4 is vertically long relative to the mold 2, and is configured so that the upper end and the lower end of the split core 4 protrude from the mold 2. Both ends of the molded product P are covered by the mold 2 without a gap.

[0044] The first core 41 has an angle r1-1 with the intersection point V1 of the axis O1 and a line O2 obtained by extending the inclined surface of the dividing surface 411 as a vertex. The angle r1-1 is the inclination angle of the dividing surface 411.

[0045] Figure 4 It is a cross-sectional view showing the direction SD in which the sliding mechanism 3 slides the second core 42 .

[0046] like Figure 4As shown, the point at the upper end of the dividing surface 411 is the vertex V2, and the extended line O2 and the perpendicular line O3 extending vertically downward from V2 have an angle r1-2. The angle r1-1 and the angle r1-2 are equal angles and are the inclination angles of the dividing surface 411.

[0047] The sliding mechanism 3 has the following function, namely, to slide the split core 42 in a direction where the angle formed with the axis O1 direction exceeds 0 degrees and is smaller than the inclination angles r1-1 and r1-2 of the split surface 411. With respect to the vertex V2 of the second core 42, the midpoint of the upper surface portion 423 is set as V5, and the point of the opposite end is set as the vertex V3. The intersection point V4 is the intersection point of the vertical line O4 extending upward from the vertex V3 and the extension line O2. With the intersection point V4 as the vertex, the angle formed by the vertical line O4 and the extension line O2 is equal to the angle r1-1 and the angle r1-2, and is the inclination angle of the split surface 411 and the split surface 421. The arrow SD starts from the intersection point V4, passes through the midpoint V5, and extends in the direction of the sliding mechanism 3. The angle r2 formed by the extension line O4 extending from the intersection point V4 and the arrow SD is within the range of more than 0 degrees and less than the inclination angle r1-2.

[0048] Figure 5 3 is a diagram showing a state in which the second core 42 is slid in the direction of the arrow SD by the sliding mechanism 3. Figure 5 In the figure, the range surrounded by the dotted line is enlarged and shown on the right.

[0049] The second core 42-1 and the second core 42-2 indicated by the double-dashed line show the evolution of the change of the second core 42 moved by the sliding mechanism 3. The sliding mechanism 3 slides the second core 42 in the direction of the arrow SD within the range of more than 0 degrees and less than the inclination angle r1-2, thereby moving the second core 42 to the position of the second core 42-1. By this movement, a gap S1 is generated between the dividing surface 411 of the first core 41 and the dividing surface 421-1 of the second core 42-1, and a gap S2 is generated between the arcuate outer peripheral surface of the second core 42-1 in a plan view and the through hole Ph of the molded product P. By generating the gaps S1 and S2 in this way, the second core 42 can be smoothly slid to the position of the second core 42-2, similarly to the core provided with a draft angle. By further sliding the second core 42 in the same direction by the sliding mechanism 3, the second core 42 can be pulled out from the molded product P.

[0050] Regarding the sliding direction of the sliding mechanism 3, for example, when the second core 42 is slid vertically in the direction of 0 degrees, the above-mentioned gap S2 is not generated, so it is difficult to pull out the second core 42. In addition, when the second core 42 is slid in the direction of an angle equal to the inclination angle of the dividing surface 411 of the first core 41, the above-mentioned gap S1 is not generated, so it is also difficult to pull out the second core 42. Therefore, as the range of the sliding direction for generating the gaps S1 and S2, it is necessary to be within the range where the angle formed with the axis O1 direction exceeds 0 degrees and is smaller than the inclination angle of the dividing surface 411 of the first core 41.

[0051] According to the injection molding device 1 of this embodiment, the following effects are achieved.

[0052] The injection molding device 1 of this embodiment comprises: a first core 41 and a second core 42, which are formed by dividing a cylindrical split core 4 arranged in a cavity C, and have a dividing surface 411 and a dividing surface 421 that are inclined relative to the axial direction of the split core 4 and divide the cavity C from one end to the other end in the axial direction of the split core 4; and a sliding mechanism 3, which allows the first core 41 or the second core 42 to slide and be inserted and pulled out of the cavity C.

[0053] Thus, the split surfaces 411 and 421 of the first core 41 and the second core 42 formed by splitting the split core 4 without a draft angle can be slid, and the second core 42 can be slid and moved to be inserted and removed from the cavity C by the sliding mechanism 3 .

[0054] In addition, the sliding mechanism 3 of this embodiment causes the second core 42 to slide in a direction where the angle formed with the axis O1 direction of the split core 4 exceeds 0 degrees and is less than the inclination angle r1-1 of the split surface 411 of the first core in a cross-section including the axis O1 of the split core 4 and orthogonal to the aforementioned split surface.

[0055] Thus, the second core 42 can be easily inserted and removed from the cavity C by the sliding mechanism 3, and after the split core 4 is removed from the mold 2, the first mold 21 and the second mold 22 can be opened to remove the cylindrical molded product P with a fixed inner diameter.

[0056] In addition, in the present embodiment, the sliding direction is set in the direction of the angle r2 passing through the midpoint of the upper surface portion 423 of the second core 42, but the sliding direction of the sliding mechanism 3 is not limited to the angle r2. As long as the sliding movement is within the range where the angle formed with the axis O1 direction exceeds 0 degrees and is smaller than the inclination angle of the dividing surface 411 of the first core 41 as described above, the same effect will be achieved.

[0057] In addition, in the present embodiment, the sliding mechanism 3 is connected to the lower end of the split core 4 and slides in the lower direction of the mold 2, but the arrangement of the sliding mechanism 3 is not limited to the lower part of the mold 2. The sliding mechanism 3 may also be connected to the upper end of the first core 41 so that the first core 41 slides upward to be demolded. In the present invention, either the first core 41 or the second core 42 may be slid by the sliding mechanism 3.

[0058] In addition, in the present embodiment, the axis O1 direction of the cavity C and the split core 4 is set relative to the vertical direction of the mold 2, but the device of the present invention is not limited thereto. For example, the axis O1 direction of the cavity C may be set relative to the horizontal direction of the mold 2, and the cavity C and the split core 4 may be set at all angles of the mold 2.

[0059] In the present embodiment, the second core 42 is slidably moved by the slide mechanism 3 in the mold closing state, but the present invention is not limited thereto. The second core 42 may be slidably moved by the slide mechanism 3 after the mold opening.

[0060] In addition, the molded product P of this embodiment is a cylindrical component with a fixed outer diameter, but a cylindrical molded product with a fixed inner diameter can be molded by the present invention, and the outer shape is not limited. As a specific example, a cylindrical molded product with a fixed inner diameter can be molded, in which a tapered surface is provided on the side surface of the component, or a hollow portion whose inner diameter is not a through hole but a hole whose end is closed, and a bottomed cylindrical molded product with a fixed inner diameter can be molded.

[0061] [Second embodiment]

[0062] Next, the second embodiment of the present invention will be described in detail with reference to the accompanying drawings. The second embodiment differs from the first embodiment in that it includes an air supply pipe 6A provided in the second mold 22B, an air supply mechanism 6, and a groove 51 and a groove 52 provided in the second core 42B. As for other structures, since they are the same as the injection molding device 1 in the first embodiment, the description is omitted.

[0063] Figure 6 4B is a three-dimensional diagram showing the state of the split core 4B being assembled. Figure 6 In the figure, the first core 41 and the mold 2 are shown by double-dashed lines. The outer shape of the mold 2B presents a structure divided into two, not limited to a cubic shape, and the inner shape of the mold 2B after the mold is closed corresponds to the shape of the cavity C. The arrow A shown in the figure is the direction of the air supplied by the air supply mechanism 6.

[0064] like Figure 6As shown in FIG. 2 , the mold 2B is composed of a first mold 21 and a second mold 22B. The second mold 22B is provided with an air supply pipe 6A extending in the horizontal direction, for example, to supply air to the grooves 51 and 52 formed on the dividing surface 421B of the second core 42. The air supply mechanism 6 is connected to the end of the air supply pipe 6A formed to penetrate the mold 22B.

[0065] The air supply mechanism 6 has the function of supplying air in the direction of arrow A. Specifically, an air supply source such as an air compressor can be envisioned, but it is not limited thereto, and any mechanism can be applied as long as it has the function of supplying air. In addition, as described above, an air cylinder can be used for the sliding mechanism 3. In the case of using an air cylinder, the air supply mechanism 6 can be shared, so that the device can be operated efficiently.

[0066] As described above, the groove 51 and the groove 52 are provided on the dividing surface 421B of the second core 42B. The horizontal cross-sectional shape of the groove 51 is a semicircular shape, and the groove is provided from the upper end to the lower end relative to the axial direction of the dividing surface 421B. Similarly, the groove 52 is provided from the upper end to the lower end of the dividing surface 421B and is parallel to the groove 51.

[0067] If the first core 41 and the second core 42B are combined, Figure 6 As shown in the figure, two hollow parts with a semicircular cross-section in the horizontal direction are formed by the dividing surface 411 of the first core 41 and the grooves 51 and 52 of the second core 42B. The air groove 5 is composed of the two hollow parts formed. The upper end of the air groove 5 is open relative to the upper surface 423B of the second core 42B, and the lower end is closed by the dividing surface 411 of the first core 41.

[0068] Next, a specific method of injection molding a cylindrical molded product P having a constant inner diameter using the injection molding apparatus 1B of the second embodiment configured as above will be described.

[0069] After the molding material injected from the resin injection port (not shown) provided in the mold 2 is filled into the cavity C, the air supply mechanism 6 is operated while the molding material is cooled and solidified in the cavity C. The operation before the air supply mechanism 6 is operated is the same as that of the first embodiment.

[0070] Air is supplied in the direction of arrow A by the air supply mechanism 6 toward the dividing surface 411 of the first core 41. The air flow supplied from the direction of arrow A flows from the upper side of the air groove 5 to the lower side of the air groove 5 whose end is closed, along the dividing surface 411 of the first core 41, and is retained inside the air groove 5. The wind pressure of the air retained inside the air groove 5 is expanded similarly to the surface where the dividing surface 411 of the first core 41 and the second core 42B abut against each other, and the dividing surface 421B of the second core 42B is promoted to be separated from the dividing surface 411 of the first core 41 by the force that causes the dividing surfaces to repel each other.

[0071] According to the injection molding device 1B of this embodiment, the following effects are achieved.

[0072] The injection molding device 1B of this embodiment also includes an air supply mechanism 6 for supplying air to the dividing surface 411 of the first core 41 and the dividing surface 421B of the second core 42B. The dividing surface 421B of the second core 42B has grooves 51 and 52 in the axial direction. The air supply mechanism 6 supplies air to the grooves 51 and 52.

[0073] Thus, the slide mechanism 3 can utilize the effect of the air supplied by the air supply mechanism 6 to more smoothly pull the second core 42B out of the cavity C. The grooves 51 and 52 enhance the effect of spreading air uniformly over the abutting dividing surfaces 411 and 421B.

[0074] The air groove 5 is not limited to the above-mentioned embodiment, and can also be provided in any one of the first core and the second core. In addition, the same effect can be achieved when the air groove 5 is provided in both. The shapes of the grooves 51 and 52 are not limited to semicircular shapes, and can be provided in various hollow parts such as triangular grooves having one side on the dividing surface of the core. In addition, in the present embodiment, the grooves are composed of two, but the number of the grooves can be increased or decreased according to the divided cores.

[0075] In addition, in the present embodiment, the air supply pipe 6A is provided parallel to the horizontal plane of the mold 2B, but the present invention is not limited thereto. The air supply structure 6 may be provided at any position according to the shape of the mold, and the air supply pipe 6A may be arranged in a curved or bent manner accordingly. As long as the function of supplying air to the dividing surface 411B of the first core 41 is provided, the shape of the present embodiment is not limited thereto.

[0076] The preferred embodiment of the present invention has been described above. However, the present description is not limited to the above embodiment, and can be appropriately changed within the scope of the present invention. For example, in the second embodiment, grooves 51 and 52 are provided, but it is also possible to set a structure in which these grooves 51 and 52 are not provided, and air is directly supplied to the dividing surface 411 and the dividing surface 421B by the air supply pipe 6A.

[0077] Reference numerals

[0078] C-type cavity

[0079] P Molded Products

[0080] 1Injection molding device

[0081] 21First Mold

[0082] 22 Second mold

[0083] 3 Sliding mechanism

[0084] 41 First core

[0085] 42, 42B second core

[0086] 411, 421, 421B dividing surface

[0087] 51, 52 slots

Claims

1. An injection molding device for injection molding a cylindrical molded product with a fixed inner diameter, and comprising: The first mold and the second mold form a cavity in a mold-clamping state; The first core and the second core are formed by dividing a cylindrical core arranged in the aforementioned cavity, and have a dividing surface inclined relative to the axial direction of the aforementioned core and dividing the aforementioned cavity from one end to the other end in the aforementioned axial direction; and, A sliding mechanism, which makes the first core or the second core slide and move to be inserted or pulled out from the cavity; The sliding mechanism slides the first core or the second core in a direction whose angle with the axial direction exceeds 0 degrees and is smaller than the inclination angle of the dividing surface in a cross-section including the axial center and perpendicular to the dividing surface.

2. The injection molding device according to claim 1, further comprising an air supply mechanism for supplying air to the divided surface.

3. The injection molding device according to claim 2, wherein: At least one of the first core and the second core has a groove in the axial direction of the dividing surface. The air supply mechanism supplies air to the groove portion.

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