JPH1034666A - Molding apparatus for molding part with hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding apparatus for molding a part with a hole which is provided with a core being movable from a hollow part with a curved shape and being repeatedly usable and can shorten time cycle of molding and can decrease remarkably manufacturing cost. SOLUTION: A plurality of core blocks 5 consisting of the first small piece 5a provided with a wedge-like projection 5d on one side and the second small piece 5b being connected freely rotatably each other and a core being divided into end blocks positioned on their both end parts are arranged in an apparatus and the end blocks and each core block 5 are brought into tight contact with each other and the end block and the wedge-like projection 5d of each core block 5 are inserted into a gap 5e formed between the first and the second small pieces 5a and 5b of the adjoining core block 5 and under above described condition, the outer shape of the core is made to coincide with the shape of the hollow part of a part with a hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus used for, for example, injection molding of plastics, and more particularly to a perforated part used for molding a perforated part having a hollow portion such as a tubular part. The present invention relates to a molding apparatus.

[0002]

2. Description of the Related Art For example, a meltable core method has been conventionally used for injection molding a tubular part having a hollow portion.

[0003] That is, the meltable core method uses a molten core made of a low melting point alloy having a melting point lower than the fluidization temperature of the resin material to be molded.
As shown in FIG. 10A, first, a molten core 103 is set in a cavity 102 formed between a fixed mold 100 and a movable mold 101, and the mold is closed. Then, as shown in FIG. Then, the resin is injected into the cavity 102. Then, as shown in FIG. 10 (c), the molded article 104 integrated with the core 103 is taken out of the molds 100 and 101, and the temperature is higher than the melting point of the core 103 and lower than the fluidization temperature of the resin. As shown in FIG. 10D, the molten core 103 is immersed in the oil tank 105 held in
Melts out and is removed from the inside of the hollow portion to obtain a hollow tubular resin product 106.

[0004]

However, in the conventional molding method described above, the core 103 must be set for each molding, and after molding, the core 103 is immersed in the oil bath 105 to melt the core 103. Is required, so that not only the molding cycle time becomes longer, but also the melting core 103
In addition, there is a problem that an increase in product cost is unavoidable due to an increase in molding cost of the core and equipment costs for melting the core 103, and solving these problems is a problem of forming such a tubular part. This has been a challenge.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the molding of a conventional perforated part, and the molded perforated part can be pulled out from a hollow portion and can be used repeatedly. Provided with a core, which eliminates the need for equipment and man-hours required for manufacturing, setting and melting and removing the molten core, and provides a molding machine for forming perforated parts that can reduce cycle time and cost significantly. It is intended to be.

[0006]

According to a first aspect of the present invention, there is provided a molding apparatus for forming a perforated part, comprising: a core block divided into a plurality of parts; and an end block located at an end of the core block. The core block is divided into shapes each capable of passing through the hollow portion of the perforated part, and the core block and the end block are in close contact with each other. The present invention is characterized in that a peripheral surface is formed, and the configuration of such a molding apparatus for forming a perforated part is a means for solving the above-mentioned conventional problems.

According to a second aspect of the present invention, there is provided a molding apparatus for forming a perforated component, wherein each core block is divided into two parts in the core pulling-out direction and at a position close to the outer periphery. The first and second small pieces are rotatably connected to each other and have wedge-shaped projections. When each core block and the end block are in close contact with each other, The wedge-shaped projections provided on the end block and the wedge-shaped projections of the core block are the first and second core blocks adjacent to each other.
The molding device according to claim 2 is characterized in that it is configured to be fitted into a gap formed between the small pieces and into a fitting recess provided in the other end block, respectively. In the molding apparatus for forming a perforated component, one end block is connected to a cylinder having a stroke exceeding the entire length of the perforated component hollow portion, and the end block and each core block are each slightly shorter than the length of the wedge-shaped projection. The molding apparatus for forming a perforated part according to claim 4, wherein the wedge-like projections of one end block and each core block are formed by a core block. The core block has an angle that secures the amount of radial movement of the core block that exceeds the amount of undercut consisting of the length of the hollow part of the perforated part and the curvature of the hollow part. The gap formed between the first and second small pieces of the rack has a size exceeding the undercut amount, and such a configuration in the forming apparatus for forming a perforated part is solved by the conventional problem described above. It is characterized by means for solving the problem.

According to a fifth aspect of the present invention, there is provided a forming apparatus for forming a perforated part, wherein each of the core blocks has a first surface inclined with respect to a direction in which the core is pulled out; 6. A molding device according to claim 5, wherein the first surface is inclined in a direction opposite to the first surface and is divided by a second surface intersecting the first surface. In the molding apparatus for forming a perforated component according to No. 6, one end block is connected to a cylinder having a stroke exceeding the entire length of the hollow portion of the perforated component, and the end block is separated from each core block by a predetermined distance. The molding apparatus according to claim 7, wherein the intersection of the first and second surfaces exceeds the amount of undercut in the drawing direction of the hollow part having a hole. It is characterized in that from the law only the maximum width of the hollow inner surface positioned and configured to be offset.

Further, as an embodiment of the forming apparatus for forming a perforated part according to the present invention, the forming apparatus according to claim 8 is as follows.
The other end of the wire whose one end is connected to the core block located at the end on the opposite side of the core withdrawing direction is configured to be connected to the traction means through the through hole formed in the other core block. The configuration of such a forming apparatus for forming perforated parts is a means for solving the above-mentioned conventional problems.

[0010]

According to the first aspect of the present invention, there is provided a molding apparatus for forming a perforated component, having the above configuration, that is, a core formed by combining a plurality of divided core blocks and end blocks. Since the core block and the end block are adapted to form the inner surface of the hollow portion of the perforated component in a state in which they are in close contact with each other, by setting them in the cavity in a state in which they are in close contact with each other, It is possible to obtain a perforated part having a hollow part, and since each of the core blocks has a shape that can pass through the hollow part of the molded perforated part, the core blocks are separated from each other after the molding is completed. Each core block can be separated from the inner surface of the hollow part of the perforated part and pulled out from the hollow part, so that the core can be used repeatedly. Compared with the core method, equipment and man-hours related to the production and setting of the molten core and the removal of the molten core after molding are not required, and together with the shortening of the cycle time, the production cost of perforated parts can be significantly reduced. This is an extremely excellent effect that can be achieved.

According to the second aspect of the present invention, there is provided a molding apparatus for forming a perforated part, which defines a specific structure of a core. In the molding apparatus, each core block is divided into a first small piece and a second small piece along the core withdrawing direction, and the first and second small pieces are rotatably connected at a position near the outer periphery. Together with a wedge-shaped projection on one of the first and second small pieces,
In a state where each core block and the end block are in close contact with each other, the wedge-shaped projections of the end block and each core block are fitted into gaps formed between the first and second small pieces of the adjacent core blocks. It has become.
That is, when the end block and the core block are in close contact with each other, the wedge-shaped projections enter the gap between the first and second small pieces of the adjacent core block, so that the first and second small pieces are centered on the connection shaft. By rotating in the opening direction, each core block retains the hollow shape of the perforated component, while in a state where each core block and the end block are separated from each other, a wedge-shaped projection is formed from the gap. By getting out, the first of the core block
And since the second small piece rotates in the closing direction about the connecting shaft, each separated core block becomes smaller than the hollow portion width dimension of the molded perforated part, and the perforated part is curved. The core can be pulled out from the hollow portion even if it has a tapered portion in the direction opposite to the drawing direction.

On the other hand, in the molding apparatus according to the fifth aspect, each core block is inclined in a direction opposite to the first surface with respect to the direction in which the core is pulled out. Since it is divided by the second surface that is inclined and intersects on the first surface, the shape of the hollow part of the perforated component is maintained while the core blocks are in close contact with each other,
When the core blocks are separated from each other, each core block moves toward the center of the perforated component along the first surface and the second surface and is smaller than the hollow portion width dimension of the perforated component. Therefore, each core block is separated from the inner surface of the hollow part of the molded perforated part, and can be pulled out from the hollow part in the same manner as the core of the molding apparatus according to the second aspect.

According to a second aspect of the present invention, in the molding apparatus according to the third aspect, one of the end blocks and each of the core blocks are slightly longer than the length of the wedge-shaped projection. A long distance, i.e., a wedge-shaped projection is detachably connected to the core block so that the wedge-shaped projection can be separated from the first and second small pieces of the adjacent core block, and one end block has the entire length of the hollow part having a hole. Since the cylinder is connected to a cylinder having a stroke exceeding, after the molding is completed, the cylinder is retracted, whereby the end block and each core block can be pulled out from the hollow portion of the perforated part while separating, This makes it possible to automate the process. A molding apparatus for forming a perforated part according to claim 4 as an embodiment,
It shows a dimensional condition of the core block in the molding apparatus according to claim 2 or 3, wherein the wedge-shaped projection only secures a radial movement amount of the core block exceeding an undercut amount. Since the gap formed between the first and second small pieces of the core block has an angle exceeding the undercut amount, the end block and the core block are separated from each other, and the wedge-shaped protrusion is formed. In a state in which the core blocks are separated from the gap between the first and second small pieces, each core block can be made to have a size sufficient to be pulled out from the hollow portion of the perforated component.

According to a fifth aspect of the present invention, there is provided a molding apparatus for forming a perforated part according to a sixth aspect of the present invention, wherein one end block is provided with a cylinder having a stroke exceeding the entire length of the hollow part of the perforated part. Since the end block and each core block are connected so that one end block and each core block can be separated from each other to a predetermined distance, after the molding is completed, the cylinder is retracted to operate the end block and each core block. It can be automatically pulled out from the hollow part of the perforated part while separating,
Similarly, as an embodiment, a molding device according to claim 7 indicates the dimensional condition of the core block in the molding device according to claim 5 or 6, wherein an intersection of the first and second surfaces is present. Since the hole is offset from the position of the maximum width of the inner surface of the hollow part by a size exceeding the amount of undercut in the drawing direction of the hollow part, sufficient movement in the center direction of the hollow part with the core blocks separated from each other The quantity can be secured and each core block can be of a size sufficient to be pulled out of the hollow part of the perforated component.

Further, as an embodiment of the forming apparatus for forming perforated parts according to the present invention, in the forming apparatus according to claim 8, one end of the wire connected to the core block located at the end on the opposite side in the drawing direction. Since the other end is connected to the traction means through the through hole formed in the other core block, each core block is separated and extracted from the hollow portion of the perforated component, and then the traction means is operated to operate each of the core blocks. By pulling the core blocks, the separated core blocks can be brought into close contact with each other and restored to the shape of the hollow part of the perforated part, so that an extremely excellent effect that the core set can be automated can be achieved. It is.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

Embodiment 1 FIGS. 1 to 4 illustrate a first embodiment of a forming apparatus for forming perforated parts according to the present invention. FIG. 1 (a) shows the forming apparatus. 1 is a sectional view showing the structure of FIG.
(B) is an enlarged view of a main part showing the dimensional relationship.

1 (a) is an apparatus for injection-molding a curved tubular part as a perforated part, comprising a lower mold 2 (fixed side) and an upper mold. 3 (movable side) and a core 4 which is set in a space formed between the lower mold 2 and the upper mold 3 and forms the inner peripheral surface of the hollow portion of the tubular component.

In this embodiment, the core 4 comprises four core blocks 5 and end blocks 6 and 7 located at both ends of the four core blocks 5. The end block 6 located at
It is connected to.

As shown in FIGS. 2 (a) and 2 (b), each core block 5 is provided with a first small piece 5a along the direction in which the core 4 is pulled out, that is, along the axis of the tubular part P1 to be formed. It is vertically divided into two parts with a second small piece 5b, and is rotatably connected to each other by a shaft 5c at an outer peripheral side position of the division surface.

Further, each core block 5 has a first small piece 5
a or wedge-shaped protrusions 5d on the side of the second small piece 5b, respectively, and these wedge-shaped protrusions 5d are formed between the first and second small pieces 5a and 5b of the adjacent core block 5. , Respectively. Note that the first small piece 5a and the second small piece 5b of the core block 5 located on the left side in the drawing, that is, the leading end in the drawing direction.
Between the end block 6 and the pull-out direction end block 6.
The wedge-shaped projection 6a formed on the right side in the figure is fitted.
That is, the core block 5 located at the end of the drawing direction
The wedge-shaped protrusions 5d are adapted to be fitted into fitting recesses 7a provided in the end block 7 on the side opposite to the pull-out direction, and these core blocks 5 and end blocks 6, 7 are in close contact with each other, and each wedge is formed. Projections 6a and 5d
Are the first small piece 5a and the second small piece 5 of the adjacent core block 5.
When the core 4 is completely fitted in the gap 5e between the core 4b and the fitting recess 7a of the end block 7, the outer shape of the core 4 matches the shape of the hollow portion of the tubular part P1 to be molded. ing.

As shown in FIGS. 4A and 4B, between each core block 5 and the end block 6 on the drawing direction side, a rod 10 urged by a coil spring 9 in the drawing direction is provided. Connected by a wedge-shaped projection 6
The wedge-shaped projections 6a and 5d are separated from each other to a distance slightly longer than the lengths of the core blocks 5a and 5d, that is, are separated from the gaps 5e of the respective core blocks 5, and one end of the core blocks 5 is located at the end of the drawing direction. The other end of the wire 11 connected to the core block 5 is connected to a winding device 12 as a traction means through through holes 5f and 6b provided in the other core block 5 and the end block 6. (See FIG. 3).

Each of the core blocks 5 is shown in FIG.
As shown in (b), the angle has an angle α that satisfies the amount of movement in the radial direction D exceeding the amount of undercut U determined by the length of the core block 5 and the curvature of the tubular part P1, and the first small piece 5a and the The gap distance G between the two small pieces 5b exceeds the undercut amount U. Accordingly, the first small piece 5a and the second small piece 5b of the core block 5 in which the wedge-shaped projection 5d on the left side in FIG.
Of the second small piece 5 by a distance G larger than the undercut amount U
Since b moves, the diameter of the core blocks 5 is reduced as shown by the imaginary line in FIG. 2B, so that by separating the core blocks 5 from each other, each core block 5 It can be separated from the inner surface of the formed tubular part P1 and pulled out from the hollow part.

The procedure of injection molding of the tubular part P1 using the molding apparatus 1 having such a structure will be briefly described below.

First, as shown in FIG. 1, the mold is closed in a state where each core block 5 and the end blocks 6 and 7 are in close contact with each other, and the resin material is filled in the formed cavity C at a predetermined temperature and pressure. By injection, a tubular part P1 having a desired shape is obtained.

Next, as shown in FIG. 3, when the molding apparatus 1 is opened, the cylinder 8 is pulled in, and the pull-out end block 6 is pulled, as shown in FIG. The first small piece 5a and the second small piece 5 of the core block 5 next to it.
b begins to fall out of the gap 5e formed between the first small pieces 5
a moves in the direction of the arrow in the figure, and the core block 5 separates from the inner surface of the tubular part P1.

Then, as shown in FIG. 4 (b), the end block 6
When the wedge-shaped projection 6a is completely separated from the gap 5e of the core block 5, the core block 5 is completely separated from the inner surface of the tubular part P1, and the core block 5 is connected via the rod 10 as described above. Since it is connected to the end block 6, the wedge-shaped protrusion 5d moves in the drawing direction together with the end block 6, and the wedge-shaped projection 5d is a gap 5e between the first and second small pieces 5a and 5b of the core block 5 on the right side in the drawing. , The width of the core block 5 is reduced and separated from the inner surface of the tubular part P1.

As shown in FIG. 3, the respective core blocks 5 are successively separated from the inner surface of the tubular part P1, and all the core blocks 5 are discharged from the hollow portion as shown in FIG. After that, the tubular part P1 remaining in the lower mold 2 is recovered as a product, and at the same time, the cylinder 8 is pushed out and actuated, and the mold is closed again to prepare for the next molding.

At this time, the wire 11 is wound by the operation of the winding device 12, and the four core blocks 5 are pulled toward the end block 6, so that each core block 5 and the end block 6 are brought into close contact with each other. Thus, the shape of the separated core 4 can be restored to the hollow shape of the tubular part P1.

Embodiment 2 FIGS. 5 to 9 show a second embodiment of a forming apparatus for forming perforated parts according to the present invention. FIG. 5 is a sectional view showing the structure of the forming apparatus. FIG. 6 is an explanatory view showing the dimensional relationship.

The forming apparatus 20 for forming perforated parts shown in FIG.
The present invention relates to a device for injection molding a tubular component having a hollow portion whose cross-sectional dimension decreases at a constant rate in a core drawing direction as a perforated component. Similarly to the device 1, the lower die 21 (fixed side), the upper die 22 (movable side), and the inner peripheral surface of the hollow portion of the tubular part set in the space formed between the lower die 21 and the upper die 22 Is formed mainly from the core 23 that forms

In the present embodiment, the cores 23 are formed into five core blocks 24 and an end block 25 located on the right side of the five core blocks 24 in the drawing, that is, on the front side in the drawing direction of the core 23. The end block 25 is connected to a cylinder 26 having a stroke longer than the entire length of the hollow portion of the tubular part P2 to be formed, and the core block 24 and the end block 25 are in close contact with each other. , The tubular part P2 to be molded
The inner peripheral surface of the hollow portion is formed.

As shown in FIG. 6, each core block 24 has a first surface F1 inclined with respect to the direction in which the core 23 is pulled out, and a direction opposite to the first surface F1 with respect to the drawing direction. And is divided by a second surface F2 which intersects the first surface F1 at a point P with respect to the first surface F1, and is formed integrally with the adjacent core block 24 as shown in FIG. And a pin hole 24c having a diameter sufficiently larger than the diameter of the pin 24b and receiving the pin 24b with a clearance K.
And separated from each other by a predetermined distance based on the clearance K. The position of the intersection point P of the second surface F2 with respect to the first surface F1 is determined by the dimension exceeding the undercut amount U in the drawing direction of the tubular part P2 from the maximum width position M of the inner surface of the tubular part P2 to the upper side in FIG. , So that the formed tubular part P2 can be pulled out from the hollow part. Also, the core block 2 located at the top in the pulling-out direction
Similarly, the end block 4 and the end block 25 are connected to each other by a predetermined distance by a pin 25b provided in the end block 25 and a pin hole 24c provided in the core block 24.

7 except for the core block 24 located at the end of the pulling-out direction.
The through hole 24d is provided as shown in FIG.
Through 4d, the other end of the wire 27 whose one end is connected to the core block 24 located at the end of the drawing direction is connected to the winding device 28 (see FIG. 9).

In the molding apparatus 20 provided with the core 23 having such a structure, the core block 24 and the end block 25 are formed in such a manner that the mold is closed as shown in FIG. By injecting the resin material into the cavity C, a tubular part P2 is obtained.

Then, by opening the mold of the molding apparatus 20 and starting the retraction operation of the cylinder 26, the molding apparatus 20 shown in FIG.
First, as shown in FIG.
It moves away from the adjacent core block 24 within the range permitted by the clearance K between the pin 5b and the pin hole 24c, and separates from the inner peripheral surface of the tubular part P2.

Further, the core block 2 connected to the end block 25 by the retraction operation of the cylinder 26
4 moves together with the end block 25, and thus each core block 24 moves away from the inner peripheral surface of the tubular part P2 one after another. As shown in FIG. And the tubular part P2 is recovered from the lower mold 21 as a product. At this time, as described above, each core block 24 has the first surface F1 and the second surface F2 which are inclined in directions opposite to each other with respect to the drawing direction.
Therefore, the size of each core block 24 does not exceed the width of the hollow portion, and the core block 24 is smoothly discharged as shown in FIG.

The molding apparatus 1 according to the first embodiment
Similarly to the above, the winding device 28 is operated, and the core 27 is drawn to the end block 25 by winding the wire 27, and the core 2 is brought into close contact with each other.
3 is restored to the shape of the hollow portion of the tubular part P2, and the core 23 is set on the lower mold 21 by the pushing operation of the cylinder 26, the upper mold 22 is lowered to close the mold, and the next molding is performed. Prepare.

In this embodiment, the core block 24 and the end block 25 are connected to each other by a pin having a clearance and a pin hole so as to be separated from each other by a predetermined distance. It is also possible to connect with a coil spring and a rod, or with a flexible wire or chain.

As described above, in the above-described forming apparatuses 1 and 20 for forming a perforated component, the core for forming the inner surface of the hollow portion is constituted by the core block divided into a plurality of parts and the end block. By separating after molding, it can be easily discharged from the hollow part of the molded product,
In addition, the operation of the winding device can automatically restore the inner surface shape of the hollow portion, so that the molding cycle can be shortened and the molten core can be formed in a shorter time than the conventional meltable core method using a molten core. Since the equipment and man-hours required for manufacturing, setting in a mold, and melting and discharging after molding are not required, the manufacturing cost can be significantly reduced.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a structure of a forming apparatus for forming a perforated component according to a first embodiment of the present invention. (B) It is an expanded sectional view showing the shape of the core block in the molding device shown in Drawing 1 (a).

FIG. 2A is a perspective view illustrating the shape of a core block in the molding apparatus shown in FIG. (B) It is a cross-sectional view about the cutting line BB of FIG.2 (a).

FIG. 3 is a cross-sectional view showing a mold opening state of the molding apparatus shown in FIG.

4 (a) and 4 (b) are enlarged cross-sectional views sequentially showing a state in which a core is pulled out of a hollow portion of a formed perforated component.

FIG. 5 is a sectional view showing the structure of a forming apparatus for forming a perforated part according to a second embodiment of the present invention.

FIG. 6 is an explanatory view showing a shape of a core block in the molding apparatus shown in FIG.

FIGS. 7A and 7B are perspective views showing the structure of a core block in the molding apparatus shown in FIG.

FIGS. 8A and 8B are cross-sectional views sequentially showing the state of detachment of a core from a molded hollow part with a hole.

FIG. 9 is a cross-sectional view showing a state in which a core is pulled out from a hollow portion of a formed perforated component.

10 (a) to 10 (d) are process diagrams for sequentially explaining the procedure for forming a tubular part by a conventional meltable core method.

[Explanation of symbols]

 1,20 Molding apparatus for forming perforated parts 4,23 Core 5,24 Core block 5a First small piece 5a Second small piece 5d Wedge-shaped projection 6,7,25 End block 6a Wedge-shaped projection 8,26 Cylinder 11, 27 Wire 12,28 Winding device (traction means) P1, P2 Tubular part (perforated part)

Claims (8)

[Claims] 1. A core comprising a plurality of divided core blocks and an end block located at an end of the core block, wherein the core block can pass through a hollow portion of a perforated component. And forming an inner peripheral surface of the perforated component in a state where the core block and the end block are in close contact with each other. 2. Each core block is divided into two parts in a direction in which the core is pulled out, and comprises a first small piece and a second small piece rotatably connected to each other at a position close to the outer periphery. Alternatively, the second piece has a wedge-shaped projection,
In a state where each core block and the end block are in close contact with each other, a wedge-shaped projection provided on one end block and a wedge-shaped projection of the core block are formed between the first and second small pieces of the adjacent core blocks. 2. The molding device for forming a perforated component according to claim 1, wherein the molding device is fitted in a gap to be formed and a fitting recess provided in the other end block. 3. One end block is connected to a cylinder having a stroke exceeding the entire length of the hollow part with a hole, and the end block and each core block are separated from each other by a distance slightly longer than the length of the wedge-shaped projection. 3. The molding device for forming a perforated component according to claim 2, wherein the molding device is connected so as to be possible. 4. The wedge-shaped projection of one of the end blocks and each core block has a radial movement amount of the core block exceeding an undercut amount consisting of the length of the core block and the curvature of the hollow part of the perforated part. And a gap formed between the first and second small pieces of the core block has a size exceeding the undercut amount. The molding apparatus for molding perforated parts according to the above. 5. A first surface in which each core block inclines with respect to a core withdrawing direction, and a first surface inclining in a direction opposite to the first surface with respect to a core withdrawing direction and a first surface. The molding device for forming a perforated component according to claim 1, wherein the molding device is divided by a second surface intersecting the surface. 6. One end block is connected to a cylinder having a stroke exceeding the entire length of the hollow part having a hole, and the end block and each core block are connected so as to be separated from each other by a predetermined distance. The molding apparatus for forming perforated parts according to claim 5, characterized in that: 7. An intersecting point of the first and second surfaces is offset from a position having a maximum width of the inner surface of the hollow part by a dimension exceeding an undercut amount in a drawing direction of the hollow part with a hole. The molding apparatus for forming a perforated part according to claim 5 or 6. 8. The other end of the wire having one end connected to the core block located at the end of the core opposite to the pulling direction is connected to the traction means through a through hole formed in another core block. 9. The method according to claim 1, wherein
The molding apparatus for molding perforated parts according to any one of the above.