JP2001150457A - Split core and molded article molded by using this core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily pull out a core member by eliminating the friction resistance between a molded article and the core member when the core member is pulled out of the molded article in a split core capable of molding the molded article having a pulling gradient on its inner surface. SOLUTION: A core 1 for molding the inner surface of a square cylindrical resin molded article is formed as a rectangular parallelepiped comprising six surfaces and constituted of a pair of core members 2, 3 the same in shape. The parting surfaces 27 of the core members 2, 3 are flat surfaces straddling six surfaces and formed as inclined surfaces inclined with respect to the outer surfaces (horizontal and vertical surfaces) of the core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split core used for molding, for example, a cylindrical resin molded product and a molded product molded using the core. In particular, the present invention relates to an improvement of a core for performing a molding operation favorably when molding a molded article having an internal space having no draft on an inner surface.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 9-18223
As disclosed in Japanese Patent Application Publication No. 8 (1996) -108, when molding a cylindrical resin molded product, a split type type comprising a plurality of core members is used as a core for molding the inner surface of the molded product. ing. In this kind of core, a draft surface is formed on a molding surface for molding the inner surface of the molded product, thereby facilitating the operation of extracting the core member from the molded product after molding.

More specifically, as shown in FIG. 8 (a molded product a is shown by imaginary lines, and each core member b, c is shown by a solid line), a rectangular cylindrical molded product a having both ends opened is shown. Core d
, The mating surfaces b1, c of the respective core members b, c
1 (hereinafter referred to as a parting surface) is orthogonal to the direction in which the core members b and c are pulled out (see arrows in the drawing). Also, the molding surfaces b2, c2 of the core members b, c for molding the inner surface of the molded product a are formed as inclined surfaces that incline outward as the distance from the parting surfaces b1, c1 increases. That is, a draft angle of a predetermined angle (for example, 1 °) is provided on each of the molding surfaces b2 and c2. Thus, if the core members b and c are slightly pulled out of the molded product a (the state shown in FIG. 8), the molding surfaces b2 and c2 of the core members b and c and the inner surface of the molded product a are removed. A gap is generated, and the frictional resistance between the two is lost, so that the core members b and c can be easily pulled out.

[0004]

However, as described above, when the draft surfaces are provided on the molding surfaces b2 and c2 of the core members b and c, the inner surface of the molded product a has an angle of the draft angle. It is formed as an inclined surface that is only inclined. That is, as shown in FIG. 9A (cross-sectional view along the line AA in FIG. 8), the width of the inner space of the molded product a is larger at both ends on the open side than the central portion (dimension W0). Part (Dimension W
1, W2) is slightly larger. Similarly, FIG.
(B) As shown in FIG. 8 (a cross-sectional view taken along the line BB in FIG. 8), the height of the inner space of the molded article a is larger at both ends (dimensions H0) than at the center (dimension H0). H1, H2
) Is slightly larger. That is, the cross-sectional shape of the internal space of the molded article a cannot be made uniform over the entire molded article a.

As a result, for example, as shown by phantom lines in FIGS. 9 (a) and 9 (b), when a rectangular parallelepiped box The shape is defined as the smallest cross-sectional shape (width W0,
The height dimension must be set in accordance with H0).
Therefore, when the box e is fitted into the molded article a, a gap f is formed between the outer surface of the box e and the inner surface of the molded article a at the open end of the molded article a. However, there is a problem that the appearance deteriorates.

In order to solve this problem, it is necessary to make the cross-sectional shape inside the molded product a uniform over the entire molded product a. However, in order to realize this, it is necessary to prevent the core members b and c from having a draft. In this case, when the core members b and c are pulled out of the molded product a, no gap is formed between the molding surfaces b2 and c2 of the core members b and c and the inner surface of the molded product a. The frictional resistance is increased, causing the following problems.

The work of pulling out the core members b and c from the molded product a becomes difficult. -In order to forcibly pull out the core members b and c, FIG.
In the state where a plurality of pins g, g,... Are in contact with the end face a1 of the molded product a as shown in FIG. (Direction indicated by). However, in this case, the contact force of the pin g against the molded product a becomes large, and the end face a of the molded product a
As shown in FIG. 10B, there is a possibility that burrs h, h,... May occur at the contact portions of the pins g, g,.

When the core members b and c are forcibly pulled out as described above, the load acting on the core members b and c is large, so that the life of the core members b and c is shortened. It will lead to conversion.

In order to easily pull out the core members b and c, it is conceivable to apply a release agent in advance to the molding surfaces b2 and c2 of the core members b and c. There is a possibility that the inner surface of the molded article a is stained by the release agent.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a molded product, which is capable of forming a molded product having no draft on the inner surface, with respect to a split type core. An object of the present invention is to eliminate the frictional resistance between the molded product and the core member when the core member is pulled out of the core member, and to facilitate the core member to be pulled out.

[0011]

Means for Solving the Problems-Summary of the Invention-In order to achieve the above object, the present invention relates to a split type core capable of forming a molded product having no draft on the inner surface. By improving the parting surfaces of the plurality of core members constituting the core, if at least one core member is moved in a direction in which the core members are pulled out of the molded product, the parting surfaces of the core members are separated from each other. Thus, a gap for easily pulling out the core member is formed.

-Solution Means- Specifically, a first solution means taken by the present invention is based on the premise that a split core is used for molding a molded article having an inner space having no draft on the inner surface. . This core is constituted by a plurality of core members. Further, each of these core members is provided with a parting surface capable of abutting against a parting surface of another core member and a molding surface for molding the inner surface. Furthermore, if the at least one core member is moved in the direction of pulling out from the molded product after the molding of the molded product, the parting surfaces of the core members are separated from each other, and only by the space dimension formed by the separation. The parting surface of each core member is set such that the molding surface of each core member can be retracted from the inner surface of the molded product.

According to this specific matter, a core is formed by combining the respective core members, and after the molded product is formed by the core, when the core is pulled out from the molded product, at least one core member is formed. If it is moved in the direction in which the core member is pulled out, the parting surfaces of the core members are separated from each other. Due to this separation, the molding surface of each core member can be retracted from the inner surface of the molded product by the dimension of the space formed between the parting surfaces. That is, each core member has almost no frictional resistance between the other core member and the inner surface of the molded product, and the pull-out operation can be easily performed.

The second to fourth means specifically specify the shape of the parting surface. In other words, the second solution is that, in the first solution, the parting surface of each core member is inclined with respect to the core removal direction from the molded product.

According to a third aspect of the present invention, in the second aspect, the core is formed as a rectangular parallelepiped having six surfaces by integrally combining a pair of core members. And the parting surface of each core member is formed by a flat surface extending over the six surfaces.

According to a fourth aspect of the present invention, in the second aspect, the core is formed into a rectangular parallelepiped having six faces by integrally combining a pair of core members. The parting surface of each core member is formed as a flat surface that straddles four of the six surfaces and extends from one edge to the other edge in the core drawing direction in the internal space of the molded product. .

In particular, according to the third solution, if the core member is moved in the direction in which the core member is pulled out of the molded product, the parting surfaces of the core members are aligned with each other in the horizontal and vertical directions of the core. A gap is created in For this reason, in each core member, the entire outer surface (molding surface and parting surface) can be retracted from the inner surface of the molded product, and the frictional resistance between the core member and the inner surface of the molded product can be reduced. Disappears. For this reason, the core member can be pulled out of the molded product with almost no pulling load applied to the core.

The fifth solution relates to a core which is applied to a case where a part without a draft exists partially on the inner surface of a molded product. Specifically, it is assumed that a split core is used for molding a molded product having an internal space having a draft on a part of the inner surface and having no draft on the other inner surface. For the core, a forming surface for forming the inner surface having the draft is formed by an inclined surface inclined with respect to the core drawing direction. On the other hand, of the core, a portion for forming the inner surface having no draft is constituted by a plurality of core members.
Further, each of these core members is provided with a parting surface which can abut against a parting surface of another core member. Furthermore,
If at least one core member is moved in the direction of pulling out of the molded product after molding of the molded product, the parting surfaces of the core members are separated from each other, and each core is separated by the space dimension formed by this separation. The parting surface of each core member is set such that the molding surface of the member can be retracted from the inner surface having no draft.

According to this specific matter, the space formed by moving the core member in the direction in which the core member is pulled out from the molded product to separate the parting surfaces from each other, and the space between the inner surface of the molded product and the core due to the presence of the draft angle. Due to the space formed between the core and the molding surface, a gap exists between the entire molding surface of the core and the inner surface of the molded product. For this reason, the frictional resistance between the two is almost eliminated, and the core can be easily pulled out.

A sixth aspect of the present invention relates to a molded product formed by the split core according to the first or fifth aspect. That is, by using the core, it is possible to mold a molded article having an inner surface having no draft in at least a part of the internal space without deteriorating the appearance.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. In the following first and second embodiments, a core for molding a rectangular cylindrical resin molded product whose both ends are open (for example, used as a casing of a remote controller (for home appliances or security systems)). The case where the present invention is applied will be described.

(First Embodiment) FIG. 1 shows a core 1 in which a pair of core members 2 and 3 are assembled.
FIG. 2 is a perspective view showing a state in which the resin molded product 4 is molded by the above method (a mold for molding the outer surface of the molded product 4 is omitted in this drawing). FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4 is a perspective view showing one first core member 2 constituting the core 1 by a solid line and the other second core member 3 by a virtual line (two-dot chain line). For example, the core 1 has a length of 60 mm, a width of 40 mm, and a thickness of 17 mm. The core according to the present invention is not limited to this size, and can be applied to a core having any size and shape.

-Description of Shape of Core Members 2 and 3 As shown in FIG. 4, the core members 2 and 3 have the same shape. Here, only the shape of one first core member 2 (shown by a solid line in FIG. 4) will be described.

As shown in FIG. 4, the first core member 2 has a plurality of molding surfaces 21 for molding the inner surface 41 of the molded product 4.
22, 23, 24, open side end faces 25, 26 facing the open portion of the molded product 4, and a parting surface 27 to be superimposed on the second core member 3 on the mating side.

Each molding surface 21, 22, 23, 24 is shown in FIG.
The upper surface 21 and the right side surface 22 are formed in a triangular shape, and the other molding surfaces (the left side surface 23 and the lower surface 24 in the figure) are formed in a pentagonal shape (not shown in the figure). Specifically, the shape of the upper surface (rectangular flat surface) of the core 1 excluding the molding surface 21 (the molding surface forming the upper surface of the first core member 2) is the same as the molding surface 24 (the first core member 2). (A molding surface that forms the lower surface of). The shape of the side surface of the core 1 excluding the molding surface 22 (the molding surface forming the right side surface of the first core member 2) forms the molding surface 23 (the left side surface of the first core member 2). (Molding surface).

Similarly, the open side end faces 25, 26 are such that the front side face 25 in FIG. 4 is triangular and the rear side face 26 is pentagonal. Also in the open end faces 25 and 26, the shape excluding the open end face 25 (front open end face) on the end face (rectangular flat face) of the core 1 is the open end face 26 (back open end face). Side end face).

The parting surface 27 is formed as a hexagonal flat surface straddling each outer surface (six surfaces) of the core 1. That is, the parting surface 27 is formed as an inclined surface that is inclined with respect to the outer surface (horizontal plane and vertical plane) of the core 1.

The second core member 3 has the same shape as the first core member 2 and is shown by a solid line (first core member 2) and a virtual line (second core member 3) in FIG. As described above, in a state where the parting surfaces 27 of the two core members 2 and 3 are overlapped and integrally assembled, the molding surfaces 22 and 23 on the left and right sides of the first core member 2 and the second core The left and right molding surfaces 33 and 32 of the member 3 form continuous flat surfaces (rectangular flat surfaces). Thereby, both right and left sides of the outer surface of the core 1 are formed. Similarly, the upper molding surface 21 (triangular molding surface) of the first core member 2 and the upper molding surface 34 (pentagonal molding surface) of the second core member 3 are continuous flat surfaces (pentagonal molding surfaces). Thus, the upper surface of the outer surface of the core 1 is formed. Furthermore, the lower molding surface 24 (pentagonal molding surface) of the first core member 2
The lower molding surface 31 (triangular molding surface) on the lower side of the core member 3 forms a continuous flat surface (rectangular flat surface), whereby the lower surface of the outer surface of the core 1 is formed. .

Further, the first core member 2 and the second core member 3
Similarly, the open-side end faces 25 and 36 on the front side constitute continuous flat faces (rectangular flat faces matching the opening shape of the molded product 4), and A flat surface continuous between the open-side end surfaces 26 and 35 (similarly, a rectangular flat surface that matches the opening shape of the molded product 4)
Is composed. Thereby, both end surfaces of the core 1 facing the open portion of the molded product 4 are formed. As described above,
A rectangular parallelepiped core 1 composed of six surfaces orthogonal to each other is configured.

As a structure for maintaining the state in which the first core member 2 and the second core member 3 are assembled, a parting surface 27 on one side of the core members 2 and 3 is provided. A groove (not shown) whose cross section is corrugated or rectangular is formed, and a convex portion that fits into the groove is formed on the other parting surface. The relative position between the child member 2 and the second core member 3 may be determined. It is necessary to set the shapes of the grooves and the convex portions so that the core members 2 and 3 can be pulled out after the molded product 4 is formed.

-Explanation of molding operation of molded article 4- Next, molded article 4 using core 1 configured as described above.
Will be described. First, a rectangular parallelepiped core 1 in which the first core member 2 and the second core member 3 are assembled is placed inside a mold (not shown) of, for example, a split type for molding the outer surface of the molded product 4. Insert this mold and core 1
The resin material is injected into the cavity between. By cooling the mold after the injection, a rectangular cylindrical molded product 4 as shown in FIG. 1 is molded.

When the molded product 4 is to be die-cut, first, the mold for molding the outer surface of the molded product 4 is divided, and the mold is released from the outer surface of the molded product 4. Thereafter, the operation proceeds to the operation of pulling out the core 1. In this drawing operation, in the state shown in FIG.
The first core member 2 is pulled out to the rear side in the figure, and the second core member 3 is pulled out to the front side in the figure (see the arrow in FIG. 1). As described above, the parting surface 27 of each of the core members 2 and 3 is
Are inclined with respect to the outer surfaces (horizontal plane and vertical plane) of the core members, so that when at least one of the core members 2 and 3 is slightly pulled out, the parting surfaces 27 of the core members 2 and 3 Separated. The phantom lines in FIG. 2 and FIG.
A state where both core members 2 and 3 are slightly pulled out from the molded product 4 is shown. Due to the existence of the space obtained by this separation, each core member 2, 3 can be moved vertically and horizontally in the interior space of the molded product 4 without being restrained in position by the partner core members 3, 2. It can be moved in any direction.

For this reason, each core member 2, 3 can obtain a gap between the other core member 3, 2 and the inner surface 41 of the molded product 4. The frictional resistance between the mating core members 3 and 2 and the inner surface 41 of the molded product 4 is almost eliminated, and the drawing operation can be easily performed.

The molding operation of the molded article 4 is completed by pulling out the core members 2 and 3 from the molded article 4 in this manner.

As described above, in this embodiment, the parting surfaces 27 of the core members 2 and 3 are inclined with respect to the outer surface of the core 1 so that at least one of the core members 2 , 3 can be pulled out of the molded product 4 without frictional resistance. When the draft is not provided in the conventional core member, a plurality of pins are brought into contact with the end face of the molded product in order to forcibly perform the drawing (see FIG. 10A). As a result, burrs were generated on the end face of the molded product or whitening was caused. In this embodiment, since it is not necessary to forcibly pull out the core members 2 and 3, it is possible to obtain a molded article having a good appearance without deteriorating the appearance of the end face of the molded article. Further, the load acting on the core members 2 and 3 can be greatly reduced.
Life can be extended. Further, the core members 2, 3
Since the mold release can be easily performed without applying a mold release agent to each of the molding surfaces 21 to 24, the inner surface 41 of the molded product 4 is not stained by the mold release agent. Good appearance of the product 4 can be obtained.

(Modification) Next, a modification of the first embodiment will be described. The present modified example has core members 2 and 3
Is a modified form. Other configurations and forming operations are the same as those of the above-described first embodiment, and therefore, only the shapes of the core members 2 and 3 will be described here.

FIG. 5A shows a molded product 4 in this modification.
It is a top view which shows the state which was molded. In this figure, the first core member 2 is indicated by a solid line, the second core member 3 is indicated by a one-dot chain line, and the molded product 4 is indicated by a two-dot chain line.

As shown in this figure, the first core member 2
The open end face located on the lower side in the figure is extended,
It protrudes downward from the molded product 4 in the figure. The dashed line in FIG. 4 shows the protruding portion 28.

On the other hand, as shown in FIG. 5 (b), the second core member 3 has a base portion 38 for molding the lower end surface of the molded product 4 in FIG. 5 (a). This base part 38
Further, a recess 38a for inserting the protruding portion 28 of the first core member 2 is formed.

Since the respective core members 2 and 3 are formed as described above, when the two core members 2 and 3 are combined, the protruding portion 28 of the first core member 2 becomes the second core member. 3 fits into the concave portion 38a of the base portion 38,
3 are determined. For this reason, both core members 2,
3 can be easily and accurately positioned. Further, in the above-described first embodiment, the grooves and the protrusions are formed on the parting surfaces 27 of the core members 2 and 3 so as to position them. However, if the configuration of this example is adopted. ,
This groove is not always necessary.

(Second Embodiment) This embodiment is also a modification of the core member. Other configurations and molding operations are the same as those of the above-described first embodiment.
Only the shape of the core member will be described.

FIG. 6 is a perspective view showing one of the first core members 7 constituting the core 6 by a solid line and the other second core member 8 by a virtual line (two-dot chain line). As shown in this figure, each core member 7, 8 according to the present embodiment has the same shape as each other. Here, only the shape of the first core member 7 will be described.

The first core member 7 is formed on the inner surface 4 of the molded product 4.
A plurality of molding surfaces 71, 72, 73 for molding 1;
It has open-side end surfaces 74 and 75 facing the open portion of the molded product 4 and a parting surface 76 to be superimposed on the second core member 8 on the other side.

The left and right side surfaces 71, 72 in FIG. 6 are formed in a trapezoidal shape, and the other forming surfaces (the lower surface 73 in the figure) are rectangular (not shown in the figure). Is formed. Specifically, the shape excluding the molding surface 71 (the molding surface forming the right side surface of the first core member 7) on the side surface of the core 6 forms the molding surface 72 (the left side surface of the first core member 7). Molding surface).

The open end faces 74 and 75 are both rectangular. Also at the open side end faces 74 and 75, the open side end face 74 (the front open side end face) at the end face of the core 6.
The shape excluding the above corresponds to the open end face 75 (the open end face on the back side).

The parting surface 76 is formed of a rectangular flat surface which straddles the left and right side surfaces of the core 6 and the four open end surfaces. In other words, the parting surface 76 extends over four of the six surfaces constituting the outer surface of the core 6, and extends from one edge to the other edge of the inner space of the molded product 4 in the core withdrawal direction. The surface is formed. Further, the parting surface 76 is formed as an inclined surface that gradually inclines downward from the open side end surface 75 on the far side in the figure toward the open side end surface 74 on the near side in the figure.

The second core member 8 has the same shape as the first core member 7 and is shown by a solid line (first core member 7) and a virtual line (second core member 8) in FIG. As described above, in a state where the parting surfaces 76 of the two core members 7 and 8 are overlapped and integrally assembled, the molding surfaces 71 and 72 on the left and right sides of the first core member 7 and the second core The left and right molding surfaces 82 and 81 of the member 8 form continuous flat surfaces (rectangular flat surfaces). Thereby, both right and left sides of the outer surface of the core 6 are formed.

The first core member 7 and the second core member 8
Similarly, the open side end faces 74, 85 on the front side constitute a continuous flat surface (rectangular flat surface), and the open side end faces 75, 84 on the back side.
They constitute a continuous flat surface. by this,
Both end surfaces of the core 6 facing the open portion of the molded product 4 are formed. As described above, a rectangular parallelepiped core 6 composed of six surfaces orthogonal to each other is formed.

The structure for maintaining the assembled state of the first core member 7 and the second core member 8 is similar to that of the first embodiment described above. By forming grooves and projections on the parting surfaces 76 of 7, 8,
Positioning the relative position between the first core member 7 and the second core member 8 is raised.

As another positioning method, a protruding portion 78 is formed by extending the open-side end face portion of the first core member 7 as in the above-described modified example (see the dashed line in FIG. 6). ). On the other hand, the second core member 8 is provided with a base portion (not shown) for molding one end surface of the molded product 4, and the projection portion 78 of the first core member 7 is inserted into the base portion. A concave portion may be formed.

According to the core members 7 and 8 of this embodiment, by slightly pulling out at least one of the core members 7 and 8, the parting surfaces 76 thereof are separated from each other in the height direction of FIG. Is done. Due to the existence of the space obtained by the separation, each of the core members 7 and 8 can move vertically in the internal space of the molded product 4. For this reason, the frictional resistance at the time of pulling out each of the core members 7 and 8 from the molded product 4 can be reduced, and the pulling-out operation can be easily performed.

As described above, in the present embodiment as well, the work of pulling out the core members 7 and 8 becomes easy, so that a molded article having a better appearance can be obtained as compared with the conventional one in which the pulling out is forcibly performed. And the life of the core members 7, 8 can be extended.

(Third Embodiment) In the first and second embodiments described above, the case where the present invention is applied to a core for molding a rectangular cylindrical molded product having both open ends has been described. The third embodiment is a case where the present invention is applied to a core for molding a molded article having a shape other than the above.

FIG. 7A shows a resin molded product 10 formed by a core 9.
Is a cross-sectional view showing a molded state, and b is VII-VI in a.
As shown in a cross-sectional view of a portion corresponding to the line I), the molded product 10 to which the present embodiment is applied includes a rectangular cylindrical upper portion 11,
A rectangular cylindrical lower part 12 which is continuous with the upper part 11 and has both a width dimension and a depth dimension set to be larger than that of the upper part 11 is provided. Are continuous.

The inner surface 11a forming the inner space of the upper part 11 is not provided with a draft, whereas the inner surface 12a forming the inner space of the lower part 12 is provided with a draft. That is, the technique of the present invention is used for forming the internal space of the upper part 11, and the conventional technique is used for forming the internal space of the lower part 12.

Hereinafter, the core 9 used in this embodiment will be described. As shown in FIGS. 7A and 7B, the core 9 includes an upper core member 91 and a lower core member 92. The upper core member 91 is for molding a part of the inner surface 11 a of the upper part 11 of the molded product 10. On the other hand, the lower core member 92 includes an upper molded portion 93 for molding a part of the inner surface 11a of the upper portion 11 of the molded product 10 and a molded product 10.
And a lower molding portion 94 for molding the entire inner surface 12a of the lower portion 12 of the lower portion.

The upper core member 91 and the upper molded portion 93 of the lower core member 92 are formed in the same shape as the core in each of the above-described embodiments (the shape of any of the embodiments). Can also be adopted). That is, the upper core member 9
1 and the upper molded portion 93 of the lower core member 92 are
If at least one of the upper core member 91 and the lower core member 92 is slightly pulled out of the molded product 10, the parting of both parts is performed. The surfaces 95 are separated from each other. Therefore, the frictional resistance when the upper core member 91 and the upper molded portion 93 of the lower core member 92 are pulled out from the molded product 10 can be reduced, and the pulling-out operation can be easily performed.

On the other hand, the lower molded portion 9 of the lower core member 92
4 is provided with a draft angle of a predetermined angle (for example, 1 °).
If the lower core member 92 is slightly pulled out from the lower core member 92, a gap is formed between the molding surface 94a of the lower molding portion 94 and the inner surface 12a of the molded product 10, and frictional resistance between them is lost, and the lower core member 92 is pulled out. Can be easily performed.

As described above, in the present embodiment, the parting surface 9
5 is inclined with respect to the outer surface of the core 9 so that the core 9
(A technical means according to the present invention) for reducing the frictional resistance at the time of pulling out, and a technique (a conventionally known technical means) for reducing the frictional resistance at the time of pulling out by providing a draft in the core 9. By using them together, the core 9 can be easily pulled out.

-Other Embodiments- In each of the above-described embodiments, the case where the present invention is applied to a core for forming a molded product having a closed-section structure has been described. The present invention is not limited to this, and is also applicable to a core for molding a molded product such as a C-channel that is partially open.

Although the core is constituted by a pair of core members, the core may be constituted by three or more core members. Further, the shape of the core is not limited to a rectangular parallelepiped shape, and various shapes such as a cubic shape, a triangular prism shape, a pentagonal prism shape, and a column shape can be adopted.

[0062]

As described above, according to the present invention, the following effects are exhibited.

According to the first aspect of the present invention, the parting surfaces of a plurality of core members constituting the core are different from those of the split-type core which can mold a molded product having no draft on the inner surface. By improving, if at least one core member is moved in the direction of pulling out from the molded product, the parting surfaces of each core member are separated from each other, and thereby a gap for easily pulling out the core member is provided. To be formed. For this reason, when a draft is not provided in the conventional core member, a plurality of pins are brought into contact with the end surface of the molded product in order to forcibly pull out the core member. Burrs were generated and whitening was caused. In the present invention, since it is not necessary to forcibly pull out the core member, it is possible to obtain a molded article having a good appearance without deteriorating the appearance of the end face of the molded article. Further, the load acting on the core member can be significantly reduced, the life of the core member can be extended, and the maintenance cost of the mold can be reduced. Furthermore, since the mold release can be easily performed without applying a mold release agent to each molding surface of the core member, the inner surface of the molded product is not contaminated by the mold release agent. Good appearance of the product can be obtained, and the commercial value of the molded product can be increased.

According to the second aspect of the present invention, the parting surface of each core member is inclined with respect to the core pull-out direction from the molded product. In a third aspect of the present invention, a rectangular parallelepiped core having six surfaces is constituted by a pair of core members, and a parting surface of each core member is formed by a flat surface extending over the six surfaces. ing. Further, in the invention according to claim 4,
A rectangular parallelepiped core composed of six surfaces is constituted by a pair of core members, and a parting surface of each core member straddles four surfaces of the six surfaces, and core extraction in an internal space of a molded product. It is formed of a flat surface extending from one edge to the other edge in the direction. Therefore, the configuration of the parting surface for achieving the effect according to the first aspect of the present invention can be specifically obtained. In particular, according to the third aspect of the present invention, if the core member is moved in a direction in which the core member is pulled out of the molded product, the parting surfaces of the core members have gaps in the horizontal and vertical directions of the core. Will happen. As a result, the entire outer surface of each core member can be retracted from the inner surface of the molded product, and there is no frictional resistance between the other core members and the inner surface of the molded product. It can be done easily.

According to the fifth aspect of the present invention, there is provided a core applicable to a case where a part without a draft exists partially on the inner surface of a molded article.
Conventionally known means using a draft angle are used in combination. Even with this configuration, there is a gap between the entire molding surface of the core and the inner surface of the molded product, there is almost no frictional resistance between the two, and the core can be easily pulled out. it can.

A sixth aspect of the present invention relates to a molded article formed by the core according to the first or fifth aspect of the present invention. That is, by using the core, it is possible to mold a molded article having an inner surface having no draft in at least a part of the internal space without deteriorating the appearance. That is, the molded product according to the present invention has high commercial value.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a resin molded product is molded by a core according to a first embodiment.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a perspective view showing a first core member by a solid line and a second core member by a virtual line.

FIG. 5A is a plan view showing a state in which a molded article is formed in a modified example. (B) is a perspective view showing a second core member.

FIG. 6 is a perspective view showing a first core member by a solid line and a second core member by a virtual line in the second embodiment.

FIG. 7A is a cross-sectional view showing a state in which a resin molded product is molded by a core in the third embodiment, and FIG.
FIG. 4 is a cross-sectional view of a portion corresponding to line VII-VII in FIG.

FIG. 8 is a perspective view showing a molded product by a virtual line and each core member by a solid line in a conventional example.

9A is a sectional view taken along line AA in FIG. 8, and FIG. 9B is a sectional view taken along line BB in FIG.

FIG. 10 is a diagram for explaining a conventional example in which a core is forcibly pulled out using a pin.

[Explanation of symbols]

1,6,9 Core 2,6 First core member 3,8 Second core member 21-24,31-34,71-73,81,82,9
4a molding surface 27, 76, 95 parting surface 4, 10 molded product 41, 11a, 12a inner surface 91 upper core member 92 lower core member

Claims (6)

[Claims] 1. A split core for molding a molded article having an internal space having no draft on an inner surface, the core being composed of a plurality of core members, each of which is a core member.
It has a parting surface capable of contacting the parting surface of another core member and a molding surface for molding the inner surface. After molding the molded product, pull out at least one core member from the molded product If moved in the direction, the parting surfaces of the core members are separated from each other, and the molding surface of each core member can be retracted from the inner surface of the molded product by the space dimension formed by this separation, A split core, wherein a parting surface of each core member is set. 2. The split core according to claim 1, wherein a parting surface of each core member is inclined with respect to a core withdrawal direction from the molded product. . 3. The split core according to claim 2, wherein the pair of core members are integrally combined,
A split-type core, which is formed in a rectangular parallelepiped shape having six surfaces, and wherein a parting surface of each core member is formed of a flat surface extending over the six surfaces. 4. The split core according to claim 2, wherein the pair of core members are integrally combined,
The parting surface of each core member straddles four of the six surfaces, and extends from one edge to the other edge in the core drawing direction in the internal space of the molded product. A split core having a flat surface extending therethrough. 5. A split core for molding a molded product having an internal space having a draft on a part of an inner surface and not having a draft on another inner surface, said core having a draft. The molding surface for molding the inner surface is formed by an inclined surface inclined with respect to the core drawing direction, while the portion for molding the inner surface having no draft is constituted by a plurality of core members. The core member has a parting surface that can abut against a parting surface of another core member. After molding of the molded product, at least one core member is moved in a direction of pulling out the molded product. For example, each core member is separated so that the parting surfaces of the core members are separated from each other, and the molding surface of each core member can be retracted from the inner surface having no draft by the space dimension formed by the separation. That the parting surface of Split core to butterflies. 6. A molded product characterized by being formed by the split mold core according to claim 1 or 5 so as to have an inner surface having no draft in at least a part of the internal space.