Cylinder overhanging part formation method

Abstract

To stabilize a shape of an overhanging part when providing a large overhanging part to a cylindrical object.SOLUTION: A cylinder overhanging part formation method comprises a circular truncated conical shape formation process S302, and a prescribed shape formation process S304. In the circular truncated conical shape formation process S302, a circular truncated conical region 250 is formed on an outer periphery of a cylindrical part 20 of a raw shape material 12 prior to the prescribed shape formation process S304. In the prescribed shape formation process S304, the circular truncated conical region 250 formed on the outer peripheral of the cylindrical part 20 is surrounded by an inner peripheral surface of a prescribed shape of an overhanging part formation die 152. In the prescribed shape formation process S304, a pressure is applied to an inner peripheral surface of the cylindrical part 20 and the cylindrical part 20 is pressed against the overhanging part formation die 152, whereby an overhanging part 252 is formed on the cylindrical part 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for forming a tubular protrusion. [Background technology]

[0002] Patent Document 1 discloses a bulge processing method for a beaded pipe. In the bulge processing method, a tubular workpiece is inserted into a die and internal pressure is applied to the tubular workpiece to form a bead. The die has a bead forming surface on the inner circumferential surface and can be separated at a diameter line. The bulge processing method comprises a first step and a second step. In the first step, bulge processing is performed by a first die and a rubber punch. The first die has a deep bead forming surface in the center and a pair of shallow bead forming surfaces on both sides. In the second step, a second die and a rubber punch are used. In the second step, the rubber punch is pressed when each die piece is approaching each other. The second die has deep bead forming surfaces in the center and on both sides, and includes die pieces that are divided between adjacent bead forming surfaces and in the middle of each bead forming surface. According to the bulge processing method disclosed in Patent Document 1, a pipe with a three-ridge bead can be formed using a normal press machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-154569 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the invention disclosed in Patent Document 1 has a problem in that when attempting to provide a large protruding portion on a cylindrical object, it is difficult to stabilize the shape of the protruding portion.

[0005] An object of the present invention is to provide a method for forming a tubular protrusion that stabilizes the shape of a large protrusion when attempting to provide a tubular object with such a protrusion. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, according to one aspect of the present invention, the tubular protrusion forming method includes a predetermined shape forming step S304. In the predetermined shape forming step S304, the tubular portion 20 of the base material 12 having the tubular portion 20 is surrounded by the protrusion forming die 152. In the predetermined shape forming step S304, pressure is applied to the inner peripheral surface of the tubular portion 20 surrounded by the protrusion forming die 152. In the predetermined shape forming step S304, the tubular portion 20 is pressed against the protrusion forming die 152 as pressure is applied to the inner peripheral surface of the tubular portion 20, thereby forming a protrusion 252 on the tubular portion 20. The protrusion forming die 152 has an inner peripheral surface of a predetermined shape. In the predetermined shape forming step, the tubular portion 20 is pressed against the inner peripheral surface of the protrusion forming die 152 having a predetermined shape. The tubular protrusion forming method includes a truncated cone shape forming step S302 in addition to the predetermined shape forming step S304. In the truncated cone shape forming step S302, prior to the predetermined shape forming step S304, a truncated cone region 250 is formed on the outer periphery of the tubular portion 20. In this case, in the predetermined shape forming step S304, the truncated cone region 250 formed on the outer periphery of the tubular portion 20 is surrounded by the inner peripheral surface of the predetermined shape of the protrusion forming mold 152.

[0007] When pressure is applied to the inner circumferential surface of the cylindrical portion 20 surrounded by the protruding portion forming mold 152, the pressure that the truncated cone region 250 receives can be divided into a direction along the central axis 290 of the cylindrical portion 20 and a direction perpendicular to the central axis 290. As a result, when pressure is applied to the inner circumferential surface of the cylindrical portion 20 surrounded by the protruding portion forming mold 152, the pressure applied to the inner circumferential surface in the direction perpendicular to the central axis 290 of the cylindrical portion 20 is smaller than that in the case where the truncated cone region 250 is not formed in the cylindrical portion 20. Since the pressure is smaller, the truncated cone region 250 is suppressed from being pushed and expanded in the protruding portion forming mold 152 by the pressure. By providing the truncated cone region 250 in this manner, it is possible to suppress the pushing and expanding of the region of the cylindrical portion 20 that is not desired to be pushed and expanded significantly before other regions. As a result of being able to suppress such expansion, when attempting to provide a large protruding portion 252 on a cylindrical object, the shape of the protruding portion 252 can be stabilized.

[0008] In the above-described frustum-shaped forming step S302, it is preferable that the frustum-shaped region 250 is formed on the outer periphery of the tubular portion 20 by the following steps. One of these steps is that the tubular portion 20 of the base material 12 is surrounded by a frustum-shaped forming die 120 that forms a frustum-shaped space. Another is that pressure is applied to the inner circumferential surface of the tubular portion 20 surrounded by the frustum-shaped forming die 120. The other is that the tubular portion 20 is pressed against the frustum-shaped forming die 120 as pressure is applied to the inner circumferential surface of the tubular portion 20.

[0009] When the truncated cone region 250 is formed on the outer periphery of the cylindrical portion 20, the cylindrical portion 20 is pressed against the truncated cone shape forming mold 120 as pressure is applied to the inner circumferential surface of the cylindrical portion 20. This makes it easy to increase the diameter of the bottom of the truncated cone region 250. When increasing the diameter, there is no great need to increase the height of the truncated cone region 250, i.e., the distance from one end to the other end of the truncated cone region 250 in the direction of the central axis 290 of the cylindrical portion 20. If the height of the truncated cone region 250 is not generally large and the diameter of the bottom is large, the truncated cone region 250 is more likely to receive a large component force in the direction of the central axis 290 of the cylindrical portion 20 when pressure is applied to the inside of the truncated cone region 250 in the predetermined shape forming step S304, compared to when the diameter is not large. When such a large component force is applied, the truncated cone region 250 is expanded so that the bottom vicinity rises. When the truncated cone region 250 is expanded so as to rise near the bottom, the likelihood that any particular portion of the formed protrusion 252 will be particularly thin is reduced compared to when the tubular portion 20 simply bulges in a direction perpendicular to its central axis 290.

[0010] Moreover, in the above-described truncated cone shape forming step S302, it is preferable that the elastic body 100 is disposed inside the cylindrical portion 20, and that the elastic body 100 deformed by receiving a force applies pressure to the inner peripheral surface of the cylindrical portion 20. In this case, it is preferable that the elastic body 100 receives a force along the direction of the central axis 290 of the cylindrical portion 20 in the truncated cone shape forming step S302. In this case, it is preferable that the truncated cone-shaped space formed by the truncated cone shape forming mold 120 in the truncated cone shape forming step S302 narrows as the elastic body 100 approaches the place where it receives the force.

[0011] When the elastic body 100 applies pressure to the inner circumferential surface of the cylindrical portion 20, it is difficult to apply a uniform pressure to the inner circumferential surface of the cylindrical portion 20, compared to when a liquid applies pressure to the inner circumferential surface of the cylindrical portion 20. Compared to when a liquid applies pressure to the inner circumferential surface of the cylindrical portion 20, the pressure is likely to be higher at a location on the inner circumferential surface of the cylindrical portion 20 close to the location where the elastic body 100 receives the force than at a location far from the location. In the truncated cone shape forming step S302, when the truncated cone-shaped space formed by the truncated cone shape forming mold 120 narrows as the elastic body 100 approaches the location where the force is received, the expansion of the location on the inner circumferential surface of the cylindrical portion 20 where the pressure is likely to be high is suppressed. When the expansion of the location where the pressure is likely to be high is suppressed, the possibility that the location where the pressure is likely to be high will be expanded beyond the expected level is reduced. When the possibility is reduced, the shape of the truncated cone region 250 formed in the cylindrical portion 20 can be stabilized.

[0012] Furthermore, in the above-mentioned predetermined shape forming step S304, when the truncated cone region 250 is surrounded by the inner circumferential surface of the predetermined shape of the protrusion forming mold 152, it is desirable to arrange the portion of the truncated cone region 250 with the largest outer diameter facing the portion of the inner circumferential surface of the predetermined shape of the protrusion forming mold 152 with the largest inner diameter.

[0013] The portion of the inner circumferential surface of the predetermined shape of the protrusion forming mold 152 having the largest inner diameter faces the portion of the truncated cone region 250 having the largest outer diameter. This makes it possible to suppress the amount of expansion of the tubular portion 20 in the direction perpendicular to the central axis 290 of the tubular portion 20 when pressure is applied to the inner circumferential surface of the tubular portion 20 in the predetermined shape forming step S304. Effect of the Invention

[0014] According to the present invention, when attempting to provide a large protruding portion on a cylindrical object, the shape of the protruding portion can be stabilized. [Brief description of the drawings]

[0015] [Figure 1] 4 is a flowchart showing each step of a method for forming a tubular protrusion according to an embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view of a shape forming apparatus according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a conceptual diagram showing the cross-sectional shapes of a cylindrical elastic body and a truncated cone mold according to an embodiment of the present invention. [Figure 4] FIG. 2 is a conceptual diagram showing the cross-sectional shape of a tapered elastic body and a protrusion forming mold according to an embodiment of the present invention. [Diagram 5] FIG. 1 is an external view of a base material according to an embodiment of the present invention. [Figure 6] 10 is a conceptual diagram showing a state in which one driving cam is pushing one driven cam according to an embodiment of the present invention; FIG. [Figure 7] 1 is a conceptual diagram showing a state in which one frustum cone surface mold and one bottom surface mold according to an embodiment of the present invention are in contact with a base material. FIG. [Figure 8] 10 is a conceptual diagram showing a state in which one holding body has entered a notch at an upper end of a one-side notch-forming member according to an embodiment of the present invention. FIG. [Figure 9] 1 is a conceptual diagram showing a state in which a cylindrical elastic body according to an embodiment of the present invention presses a cylindrical portion against the inner peripheral surfaces of one truncated cone surface mold and one bottom surface mold of a truncated cone shape forming mold. FIG. [Figure 10] 1 is an external view of a base material having a protruding portion formed thereon according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are the same. Therefore, detailed descriptions thereof will not be repeated.

[0017] [Steps of forming the tube extension part] 1 is a flow chart showing each step of the method for forming a tubular protrusion according to the present embodiment, each step of which will be described with reference to FIG.

[0018] The tubular protrusion forming method according to this embodiment includes a base material forming step S300, a truncated cone shape forming step S302, and a predetermined shape forming step S304.

[0019] In the preform forming step S300, a preform 12 is formed. In this embodiment, the preform 12 includes a cylindrical tubular portion 20 and a flange portion 22. The specific procedure is well known, so the detailed description thereof will not be repeated here.

[0020] In the truncated cone shape forming step S302, a truncated cone region 250 is formed on the outer periphery of the tubular portion 20. A detailed description thereof will be given later.

[0021] In the predetermined shape forming step S304, a protruding portion 252 is formed on the tubular portion 20 of the base material 12. A detailed description of this will be given later.

[0022] [Explanation of the configuration of the device used when carrying out the tubular protrusion forming method] 2 is a cross-sectional view of the predetermined shape forming device according to this embodiment. In this embodiment, the truncated cone shape forming device used in the truncated cone shape forming step S302 and the predetermined shape forming device used when the predetermined shape forming step S304 is performed differ in the following respect. The truncated cone shape forming device includes a cylindrical elastic body 100 and a truncated cone shape forming die 120, whereas the predetermined shape forming device includes a tapered elastic body 150 and a protruding portion forming die 152 instead of the cylindrical elastic body 100 and the truncated cone shape forming die 120. Here, the configuration common to the truncated cone shape forming device and the predetermined shape forming device will be described based on FIG. 2.

[0023] In this embodiment, the predetermined shape forming device includes a mounting table 70, a one-side driving cam 72, a one-side driven cam 74, a one-side base member 76, a one-side notch forming member 78, a one-side retraction mechanism portion not shown, a other-side driving cam 80, a other-side driven cam 82, a cam drive mechanism not shown, a other-side base member 84, a other-side notch forming member 86, a other-side retraction mechanism portion not shown, a split mold holding and pressing mold 88, and a split mold holding and pressing mold drive mechanism not shown.

[0024] The base 70 is placed on the base 70. In this way, the base 70 supports the base 70.

[0025] The one-side driving cam 72 applies a force to the one-side driven cam 74. When the one-side driven cam 74 receives a force from the one-side driving cam 72, it moves so as to approach the mounting table 70. The one-side base member 76 moves in conjunction with the movement of the one-side driven cam 74. The one-side notch forming member 78 is placed on the one-side base member 76. The one-side notch forming member 78 is disposed so as to be in contact with the one-side driven cam 74. The one-side notch forming member 78 also moves in conjunction with the movement of the one-side driven cam 74. In this embodiment, a notch 190 is formed in the upper end of the one-side notch forming member 78. The one-side retraction mechanism applies a force to the one-side base member 76 so as to move the one-side base member 76 away from the mounting table 70.

[0026] The other driving cam 80 applies a force to the other driven cam 82. When the other driven cam 82 receives a force from the other driving cam 80, it moves so as to approach the mounting table 70. The other base member 84 moves in conjunction with the movement of the other driven cam 82. The other notch forming member 86 is placed on the other base member 84. The other notch forming member 86 is disposed so as to be in contact with the other driven cam 82. The other notch forming member 86 also moves in conjunction with the movement of the other driven cam 82. In this embodiment, a notch 192 is formed in the upper end of the other notch forming member 86. The other retraction mechanism applies a force to the other base member 84 so that the other base member 84 moves away from the mounting table 70.

[0027] The cam drive mechanism drives the one drive cam 72 and the other drive cam 80 to move up and down. In this embodiment, when the one drive cam 72 and the other drive cam 80 move up and down, the split mold holding presser mold 88 also moves up and down.

[0028] The split mold holding and pressing mold 88 holds the cylindrical portion 20 in position and compresses it as described below when the cylindrical portion 20 is pressed against it.

[0029] In this embodiment, the split mold holding and pressing mold 88 has a first holding body 110 , an second holding body 112 , and an elastic compression body 114 .

[0030] The one holding member 110 and the other holding member 112 hold the position as described below. The elastic compression member 114 performs compression as described below.

[0031] The split mold holding and pressing mold drive mechanism drives the one holder 110, the other holder 112 and the elastic compression body 114 so that they move up and down.

[0032] As described above, the truncated cone shape forming device also includes the mounting table 70, the one-side driving cam 72, the one-side driven cam 74, the one-side base member 76, the one-side notch forming member 78, the one-side retraction mechanism (not shown), the other-side driving cam 80, the other-side driven cam 82, the cam drive mechanism (not shown), the other-side base member 84, the other-side notch forming member 86, the other-side retraction mechanism (not shown), the split mold holding and pressing mold 88, and the split mold holding and pressing mold drive mechanism (not shown). A detailed description thereof will not be repeated here.

[0033] 3 is a conceptual diagram showing the cross-sectional shapes of the cylindrical elastic body 100 and the truncated cone shape forming mold 120 according to this embodiment. Further configuration of the truncated cone shape forming device according to this embodiment will be described with reference to FIG.

[0034] The truncated cone shape forming device according to this embodiment further includes a cylindrical elastic body 100 and a truncated cone shape forming mold 120 .

[0035] The cylindrical elastic body 100 is placed on the mounting table 70 together with the base material 12. As a result, the mounting table 70 also supports the cylindrical elastic body 100. The cylindrical elastic body 100 is fixed to the mounting table 70. When the base material 12 is placed on the mounting table 70, it penetrates the cylindrical elastic body 100. As the cylindrical elastic body 100 receives a force and undergoes elastic deformation, it presses the base material 12, which it penetrates, against the truncated cone forming die 120.

[0036] When the base material 12 is pressed against the frustum-shaped forming mold 120, it forms a frustum-shaped space. When the base material 12 is pressed against the frustum-shaped forming mold 120, a frustum-shaped region 250 is formed on the outer periphery of the tubular portion 20. In this embodiment, the frustum-shaped forming mold 120 has one frustum-shaped surface mold 130, one bottom surface mold 132, the other frustum-shaped surface mold 134, and the other bottom surface mold 136.

[0037] The one-side truncated cone surface mold 130 has an inner circumferential surface 210 formed along the above-mentioned truncated cone-shaped space. A part of the cylindrical portion 20 is pressed against the inner circumferential surface 210. In the case of this embodiment, the part of the cylindrical portion 20 pressed against the one-side truncated cone surface mold 130 thereby becomes part of the truncated cone region 250. In the case of this embodiment, the inner circumferential surface 210 narrows as it approaches the upper end, i.e., as it moves away from the mounting table 70. In addition, in the case of this embodiment, the one-side truncated cone surface mold 130 can be lowered when pressed by the one-side holder 110.

[0038] The one bottom surface mold 132 is placed below the one truncated cone surface mold 130. The one bottom surface mold 132 has a concave curved surface 212 formed therein. A part of the tubular portion 20 is pressed against the curved surface 212. As a result, the part of the tubular portion 20 pressed against the one bottom surface mold 132 becomes a curved surface. The curved surface is adjacent to the truncated cone region 250.

[0039] The other truncated cone surface mold 134 is disposed so as to face the one truncated cone surface mold 130 across the cylindrical elastic body 100. The other truncated cone surface mold 134 also has an inner circumferential surface 214 formed along the above-mentioned truncated cone-shaped space. A part of the cylindrical part 20 is pressed against the inner circumferential surface 214. In the case of this embodiment, the part of the cylindrical part 20 pressed against the other truncated cone surface mold 134 thereby becomes the remaining part of the truncated cone region 250. In the case of this embodiment, the inner circumferential surface 214 narrows as it approaches the upper end, i.e., as it moves away from the mounting table 70. In this embodiment, the other truncated cone surface mold 134 can be lowered when pressed by the other holder 112.

[0040] The other bottom mold 136 is disposed so as to face the one bottom mold 132 with the cylindrical elastic body 100 in between. The other bottom mold 136 is disposed below the other truncated cone mold 134. The other bottom mold 136 has a recessed curved surface 216 formed thereon. A part of the tubular portion 20 is pressed against the curved surface 216. As a result, the part of the tubular portion 20 pressed against the other bottom mold 136 becomes a curved surface. The curved surface is adjacent to the truncated cone region 250.

[0041] 4 is a conceptual diagram showing the cross-sectional shapes of the tapered elastic body 150 and the protrusion forming die 152 according to this embodiment. Based on FIG. 4, a further configuration of the predetermined shape forming device according to this embodiment will be described.

[0042] The predetermined shape forming apparatus according to this embodiment further includes a tapered elastic body 150 and a protrusion forming die 152 .

[0043] The tapered elastic body 150 is placed on the mounting table 70 together with the preform 12. As a result, the mounting table 70 also supports the tapered elastic body 150. The tapered elastic body 150 is fixed to the mounting table 70. When the preform 12 having the frustum cone region 250 formed in the tubular portion 20 is placed on the mounting table 70, the tapered elastic body 150 penetrates the preform 12. As the tapered elastic body 150 receives a force and elastically deforms, it presses the preform 12, which it penetrates, against the protrusion forming mold 152.

[0044] The extension portion forming mold 152 forms a space of a predetermined shape. The shape follows the outer shape of the tubular portion 20 after the extension portion 252 has been formed by the tubular extension portion forming method according to this embodiment. Therefore, by pressing the tubular portion 20 of the base material 12 against the extension portion forming mold 152, the extension portion 252 of the predetermined shape is formed on the outer periphery of the tubular portion 20. In this embodiment, the extension portion forming mold 152 has one predetermined upper surface mold 170, one predetermined lower surface mold 172, the other predetermined upper surface mold 174, and the other predetermined lower surface mold 176.

[0045] The one-sided predetermined upper surface die 170 has an inner peripheral surface 230, which will be described below. The inner peripheral surface 230 corresponds to the outer peripheral surface that is to be finally formed on the base material 12 in the tubular protrusion forming method according to this embodiment. A part of the tubular portion 20 is pressed against the inner peripheral surface 230 of the one-sided predetermined upper surface die 170. As a result, the part of the tubular portion 20 pressed against the one-sided predetermined upper surface die 170 becomes part of the protrusion 252.

[0046] The one-side predetermined lower surface die 172 is disposed below the one-side predetermined upper surface die 170. The one-side predetermined lower surface die 172 has an inner peripheral surface 232, which will be described below. The inner peripheral surface 232 conforms to the outer peripheral surface that is to be finally formed on the base material 12 in the tubular protrusion forming method according to this embodiment. A part of the tubular portion 20 is pressed against the inner peripheral surface 232 of the one-side predetermined lower surface die 172. As a result, the part of the tubular portion 20 pressed against the one-side predetermined lower surface die 172 becomes part of the protrusion portion 252. This part is adjacent to the part of the tubular portion 20 pressed against the inner peripheral surface 230 of the one-side predetermined upper surface die 170.

[0047] The other specified upper surface die 174 is disposed so as to face the one specified upper surface die 170 with the tapered elastic body 150 in between. The other specified upper surface die 174 also has an inner peripheral surface 234, which will be described below. The inner peripheral surface 234 conforms to the outer peripheral surface that is to be finally formed on the base material 12 in the tubular protrusion forming method according to this embodiment. A part of the tubular portion 20 is pressed against the inner peripheral surface 234 of the other specified upper surface die 174. As a result, the part of the tubular portion 20 pressed against the other specified upper surface die 174 also becomes part of the protrusion 252.

[0048] The other predetermined lower surface die 176 is disposed so as to face the one predetermined lower surface die 172 with the tapered elastic body 150 interposed therebetween. The other predetermined lower surface die 176 is disposed below the other predetermined upper surface die 174. The other predetermined lower surface die 176 is formed with an inner peripheral surface 236, which will be described below. The inner peripheral surface 236 is aligned with the outer peripheral surface that is to be finally formed on the blank 12 in the tubular protrusion forming method according to this embodiment. A part of the tubular portion 20 is pressed against the inner peripheral surface 236 of the other predetermined lower surface die 176. As a result, the part of the tubular portion 20 pressed against the other predetermined lower surface die 176 becomes part of the protrusion portion 252. This part is adjacent to the part of the tubular portion 20 pressed against the inner peripheral surface 234 of the other predetermined upper surface die 174.

[0049] In this embodiment, the height of the boundary between the one truncated cone surface mold 130 and the one bottom surface mold 132 from the mounting table 70 in the vertical direction when they come into contact with each other satisfies the following requirement. The requirement is that the height is equal to the height in the vertical direction from the mounting table 70 of the most recessed part of their inner circumferential surfaces when the one specified upper surface mold 170 and the one specified lower surface mold 172 come into contact with each other. Similarly, in this embodiment, the height of the boundary between the other truncated cone surface mold 134 and the other bottom surface mold 136 in the vertical direction when they come into contact with each other satisfies the following requirement. The requirement is that the height is equal to the height in the vertical direction from the mounting table 70 of the most recessed part of their inner circumferential surfaces when the other specified upper surface mold 174 and the other specified lower surface mold 176 come into contact with each other.

[0050] [Description of the operations in each step when the method for forming the tubular protrusion is carried out] FIG. 5 is an external view of the preform 12 according to this embodiment. In the figure, a part of the preform 12 is cut out. FIG. 6 is a conceptual diagram showing a state in which the one driving cam 72 according to this embodiment is pressing the one driven cam 74. FIG. 7 is a conceptual diagram showing a state in which the one truncated cone surface die 130 and the one bottom surface die 132 according to this embodiment are in contact with the preform 12. FIG. 8 is a conceptual diagram showing a state in which the one holding body 110 enters the notch 190 at the upper end of the one notch forming member 78 according to this embodiment. FIG. 9 is a conceptual diagram showing a state in which the cylindrical elastic body 100 according to this embodiment presses the cylindrical portion 20 against the inner peripheral surface of the one truncated cone surface die 130 and the one bottom surface die 132 of the truncated cone shape forming die 120. FIG. 10 is an external view of the preform 12 on which the protruding portion 252 according to this embodiment is formed. Specific contents of each step when the cylindrical protruding portion forming method according to this embodiment is carried out will be described based on FIG. 1 to FIG. 10.

[0051] A person who carries out the tubular protrusion forming method (hereinafter referred to as the "practitioner") forms a base material 12 having a cylindrical tubular portion 20 and a flange portion 22 (S300). In the case of this embodiment, a later-described protrusion portion 252 is formed in a location near one end of the tubular portion 20 in a later process. The flange portion 22 is disposed on the outer edge of the other end of the tubular portion 20. In this embodiment, the flange portion 22 has an annular shape. The flange portion 22 extends perpendicular to the extension direction of the central axis 290 of the tubular portion 20. FIG. 5 shows the appearance of the base material 12 according to this embodiment.

[0052] Next, the worker attaches the preform 12 to the truncated cone shape forming device. More specifically, the worker places the preform 12 on the mounting table 70 of the truncated cone shape forming device so that the cylindrical elastic body 100 of the truncated cone shape forming device enters the cylindrical portion 20 of the preform 12.

[0053] When the blank 12 is placed on the platform 70 of the truncated cone shape forming device, the operator controls a cam drive mechanism (not shown) so that the one drive cam 72 and the other drive cam 80 move down.

[0054] When the one-side driving cam 72 descends under this control, the one-side driving cam 72 pushes the one-side driven cam 74. Figure 6 shows a state in which the one-side driving cam 72 is pushing the one-side driven cam 74. The pushed one-side driven cam 74 moves so as to approach the preform 12. The one-side base member 76 and the one-side notch forming member 78 move in conjunction with the movement of the one-side driven cam 74. The one-side truncated cone surface die 130 and the one-side bottom die 132, which are placed on the one-side base member 76, move in conjunction with the movement of the one-side base member 76 in such a way as to approach the preform 12. Figure 7 shows a state in which the one-side truncated cone surface die 130 and the one-side bottom die 132 come into contact with the preform 12.

[0055] When the other driving cam 80 descends, similar to the one driving cam 72, the other driving cam 80 pushes the other driven cam 82. The pushed other driven cam 82 moves closer to the base material 12. The other base member 84 and the other notch forming member 86 move in conjunction with the movement of the other driven cam 82. The other truncated cone surface die 134 and the other bottom surface die 136 placed on the other base member 84 move closer to the base material 12 in conjunction with the movement of the other base member 84.

[0056] In this manner, the one base member 76 , the one notch forming member 78 , the other base member 84 and the other notch forming member 86 approach the preform 12 , so that the cylindrical portion 20 of the preform 12 is surrounded by the frustum-shaped forming die 120 .

[0057] When the cylindrical portion 20 of the preform 12 is surrounded by the truncated cone shape forming die 120, the operator controls the split mold holding and pressing die 88 so that it descends. The one-side holding body 110 of the split mold holding and pressing die 88 descends accordingly, and enters the notch 190 formed at the upper end of the one-side notch forming member 78. This fixes the one-side notch forming member 78. As a result, the one-side truncated cone surface die 130 and the one-side bottom surface die 132 are fixed. FIG. 8 shows a state in which the one-side holding body 110 has entered the notch 190 at the upper end of the one-side notch forming member 78. The other-side holding body 112 of the split mold holding and pressing die 88 enters the notch 192 formed at the upper end of the other-side notch forming member 86. This fixes the other-side notch forming member 86. As a result, the other-side truncated cone surface die 134 and the other-side bottom surface die 136 are fixed.

[0058] Next, the elastic compression body 114 of the split mold holding presser 88 comes into contact with the upper end of the preform 12. The upper end of the preform 12 fits into the groove 270 formed in the lower end of the elastic compression body 114. The elastic compression body 114 of the split mold holding presser 88 then descends. As a result, the elastic compression body 114 of the split mold holding presser 88 presses down the upper end of the preform 12 and compresses the cylindrical elastic body 100. As a result of this compression, the outer periphery of the cylindrical elastic body 100 expands. That is, the cylindrical elastic body 100 is deformed by the force of the elastic compression body 114. On the other hand, the truncated cone surface mold 130 is pushed down by the elastic compression body 114. On the other hand, the truncated cone surface mold 134 is also pushed down by the elastic compression body 114. As the outer periphery of the cylindrical elastic body 100 expands, pressure is applied from the cylindrical elastic body 100 to the inner periphery of the tubular portion 20 of the preform 12. As pressure is applied to the inner periphery of the tubular portion 20, the tubular portion 20 is pressed against the truncated cone shape forming mold 120 having one truncated cone surface mold 130 and one bottom surface mold 132 (S302). As a result, a truncated cone region 250 is formed in the preform 12. Figure 9 shows a state in which the expanded cylindrical elastic body 100 presses the tubular portion 20 against the inner periphery of the one truncated cone surface mold 130 and one bottom surface mold 132 of the truncated cone shape forming mold 120.

[0059] When the cylindrical portion 20 is pressed against the truncated cone shape forming die 120 and expands, the operator controls the split mold holding and pressing die drive mechanism so that the split mold holding and pressing die 88 rises. In response to this, the elastic compression body 114 of the split mold holding and pressing die 88 rises first. Next, the one holder 110 and the other holder 112 rise. As they rise, the one holder 110 comes out of the notch 190 formed at the upper end of the one notch forming member 78. The other holder 112 comes out of the notch 192 formed at the upper end of the other notch forming member 86.

[0060] Next, the practitioner controls the cam drive mechanism so that the one drive cam 72 and the other drive cam 80 rise. When the one drive cam 72 rises by this control, the one base member 76, the one notch forming member 78, the one truncated cone surface die 130, and the one bottom die 132 become movable. When the other drive cam 80 rises by this control, the other base member 84, the other notch forming member 86, the other truncated cone surface die 134, and the other bottom die 136 become movable. The practitioner controls the one retraction mechanism and the other retraction mechanism so that they retract. When the truncated cone shape forming die 120 is separated from the base material 12 by this control, the practitioner removes the base material 12 from the truncated cone shape forming device.

[0061] Next, the worker attaches the preform 12 to a predetermined shape forming device. More specifically, the worker places the preform 12 on the mounting table 70 of the predetermined shape forming device so that the tapered elastic body 150 of the predetermined shape forming device enters the tubular portion 20 of the preform 12.

[0062] When the base material 12 is placed on the mounting table 70 of the predetermined shape forming device, the operator controls the cam drive mechanism so that the one drive cam 72 and the other drive cam 80 of the predetermined shape forming device descend. Thereafter, the extension portion forming mold 152 surrounds the tubular portion 20 of the base material 12 in a similar procedure to that in the truncated cone shape forming device. In this embodiment, this results in the truncated cone region 250 formed on the outer periphery of the tubular portion 20 being surrounded by the inner circumferential surface of the predetermined shape of the extension portion forming mold 152.

[0063] As described above, in the present embodiment, the height of the boundary between the one truncated cone surface mold 130 and the one bottom surface mold 132 in the vertical direction from the mounting table 70 when they come into contact with each other satisfies the following requirement. The requirement is that the height is equal to the height in the vertical direction from the mounting table 70 of the most recessed part of their inner circumferential surfaces when the one specified upper surface mold 170 and the one specified lower surface mold 172 come into contact with each other. Similarly, in the present embodiment, the height of the boundary between the other truncated cone surface mold 134 and the other bottom surface mold 136 in the vertical direction from the mounting table 70 when they come into contact with each other satisfies the following requirement. The requirement is that the height is equal to the height in the vertical direction from the mounting table 70 of the most recessed part of their inner circumferential surfaces when the other specified upper surface mold 174 and the other specified lower surface mold 176 come into contact with each other. For this reason, in the case of this embodiment, when the truncated cone region 250 is surrounded by the inner surface of the predetermined shape of the protrusion forming mold 152, the part of the truncated cone region 250 with the largest outer diameter is positioned opposite the part of the inner surface of the predetermined shape of the protrusion forming mold 152 with the largest inner diameter.

[0064] After the truncated cone region 250 of the tubular portion 20 is surrounded by the inner peripheral surface of the predetermined shape of the protrusion forming mold 152, the tubular portion 20 of the preform 12 is pressed against the protrusion forming mold 152 in a similar procedure to that used for processing the preform 12 by the truncated cone shape forming device. The specific procedure is similar to that used for processing the preform 12 by the truncated cone shape forming device. Therefore, a detailed description thereof will not be repeated here. This pressing adjusts the shape of the tubular portion 20. As a result, a protrusion 252 is formed in the tubular portion 20 (S304).

[0065] When the shape of the cylindrical portion 20 is adjusted, the operator removes the preform 12 from the predetermined shape forming device in a similar procedure to that for removing the preform 12 from the truncated cone shape forming device. This completes the method for forming a tubular protrusion according to this embodiment. Figure 10 shows the appearance of the preform 12 with the protrusion 252 formed therein.

[0066] [Effects of the method for forming a tubular protrusion according to this embodiment] According to the method for forming a tubular protrusion in accordance with the present embodiment, when attempting to provide a large protrusion 252 on a tubular object, the shape of the protrusion 252 can be stabilized.

[0067] Furthermore, according to the method for forming a tubular protrusion according to this embodiment, the possibility that a specific portion of the formed protrusion 252 will become particularly thin is reduced.

[0068] Furthermore, according to the method for forming the tubular protrusion according to this embodiment, the shape of the truncated cone region 250 formed in the tubular portion 20 can be stabilized.

[0069] Furthermore, according to the method for forming a tubular protrusion according to this embodiment, the amount of expansion of the tubular portion 20 in the direction perpendicular to the central axis 290 of the tubular portion 20 can be suppressed.

[0070] The embodiments disclosed herein are illustrative in all respects. The scope of the present invention is not limited to the above-described embodiments. Of course, various design changes may be made without departing from the spirit of the present invention.

[0071] For example, the position of the truncated cone region 250 when the truncated cone region 250 is surrounded by the inner peripheral surface of a predetermined shape of the protrusion-forming mold 152 is not limited to what has been described above. In addition, the shape of the truncated cone shape forming mold 120 and the shape of the protrusion-forming mold 152 are not limited to what has been described above. The specific means for forming the truncated cone region 250 is also not limited to what has been described above. [Explanation of symbols]

[0072] 12…Materials 20...Cylindrical part 22…Flange 70…Placement table 72...One-way driving cam 74...One-way driven cam 76...One-side base member 78...One-sided notch forming member 80...Other driving cam 82...Other driven cam 84...other base member 86...other notch forming member 88... Split mold holding mold 100...Cylindrical elastic body 110...One side holder 112...Other holding body 114... Elastic compression body 120…Truncated cone shape mold 130...One side truncated cone type 132…One side bottom type 134...Other truncated cone type 136...Other bottom type 150...Tapered elastic body 152…Protrusion forming mold 170...One side specified upper surface type 172...One side specified bottom type 174...Other predetermined upper surface type 176...Other predetermined bottom type 190,192…Notch 210,214,230,232,234,236…Inner surface 212,216…Curved surface 250…Truncated cone area 252...Protrusion 270...Groove 290…Central axis

Claims

1. a predetermined shape forming step in which a tubular portion of a base material having a tubular portion is surrounded by an overhang portion forming die, pressure is applied to an inner peripheral surface of the tubular portion surrounded by the overhang portion forming die, and the tubular portion is pressed against the overhang portion forming die as pressure is applied to the inner peripheral surface of the tubular portion, thereby forming an overhang portion on the tubular portion, The protrusion forming die has an inner circumferential surface of a predetermined shape, In the predetermined shape forming step, the cylindrical portion is pressed against an inner circumferential surface of the predetermined shape of the protrusion forming mold, a truncated cone shape forming step in which a truncated cone region is formed on an outer periphery of the cylindrical portion prior to the predetermined shape forming step, in addition to the predetermined shape forming step; A method for forming a tubular extension portion, characterized in that in the predetermined shape forming step, the inner peripheral surface of the predetermined shape of the extension portion forming mold surrounds the truncated cone region formed on the outer periphery of the tubular portion.

2. 2. The method for forming a tubular protrusion as described in claim 1, characterized in that, in the truncated cone shape forming process, the tubular portion of the base material is surrounded by a truncated cone shape forming mold that forms a truncated cone shaped space, pressure is applied to the inner surface of the tubular portion surrounded by the truncated cone shape forming mold, and as the pressure is applied, the tubular portion is pressed against the truncated cone shape forming mold, thereby forming the truncated cone region on the outer periphery of the tubular portion.

3. In the truncated cone shape forming step, an elastic body is disposed inside the cylindrical portion, and the elastic body is deformed by receiving a force and applies the pressure to an inner peripheral surface of the cylindrical portion; In the truncated cone shape forming step, the elastic body receives the force along a central axis of the cylindrical portion, 3. The method for forming a tubular protrusion portion according to claim 2, characterized in that, in the truncated cone shape forming process, the truncated cone-shaped space formed by the truncated cone shape forming mold narrows as the elastic body approaches the point where it receives the force.

4. The method for forming a tubular extension portion according to claim 1, characterized in that, in the predetermined shape forming process, when the truncated cone region is surrounded by the inner surface of the predetermined shape of the extension portion forming mold, the portion of the truncated cone region with the largest outer diameter is positioned to face the portion of the inner surface of the predetermined shape of the extension portion forming mold with the largest inner diameter.

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