JPH07266354A - Molding of press molded product having throughhole - Google Patents

Abstract

PURPOSE:To form a perfect through-hole to a press molded product simultaneously with molding. CONSTITUTION:In a press molding apparatus 11 consisting of lower and upper molds 12, 13 and constituted so that the rod-shaped member 21 corresponding to at least a part of the through-hole of a molded product is provided to the part corresponding to the through-hole of the lower mold 12 in a protruding state so as to be energized in the direction of the upper mold 13 by a coil spring 23, a molten resin 32 is supplied to the molding recessed part 19 of the lower mold 12 and the molds 12, 13 are clamped to perform press molding. At the time of mold clamping, since the rod-shaped member 21 is elastically brought into contact with the protruding part 31 of the upper mold 13 under pressure, the molten resin 32 is prevented from entering the gap between the rod-shaped member 21 and the protruding part 31 of the upper mold 13 and a perfect through-hole can be formed simultaneously with press molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a press-formed product having a through hole.

[0002]

BACKGROUND ART For example, a plastic pallet is manufactured by a press molding method in which a molten resin is supplied to a molding recess of a lower mold and then a mold is clamped between an upper mold and a lower mold. The press molding method is a molding method suitable for low-volume molding, low mold cost, and wide application range of fluidity of resin, and therefore suitable for low-volume production. While the press molding method has such advantages, it is difficult to form the through holes at the same time as molding. Therefore, when a through hole for attaching a non-slip rubber or the like is required for the molded product, a predetermined portion of the molded product is drilled after the molding. On the other hand, as shown in FIGS. 7 and 8, in recent years, a rod-shaped projection 4 corresponding to at least a part of the through hole 3 is formed in a direction corresponding to the through hole 3 of the molded product 2 of the lower mold 1 in the direction of the upper mold 5. In addition, a method has also been proposed in which the molten resin 7 is supplied to the molding recess 6 of the lower mold 1 and then the mold is clamped to form the through hole 3 of the press-molded product 2.

[0003]

According to the method of forming the through hole 3 of the molded product 2 simultaneously with the press molding, the rod-shaped projection 4 of the lower mold 1 and the inner surface of the upper mold 5 are accurately aligned when the mold is clamped. However, a gap often occurs between the rod-shaped projection 4 and the inner surface of the upper die 5 depending on the accuracy of the member.
In this case, as shown in FIG. 8, there is a problem in that the resin 7 remains in the form of a thin skin in the portion of the molded product 2 that is to be the through hole 3 and the through hole 3 is blocked. Therefore, it is an object of the present invention to provide a method for forming a press-formed product, which can form a complete through hole at the same time as forming.

[0004]

A first aspect of the present invention is a method for forming a press-formed product having a through hole, which comprises a pair of upper and lower molds, one of the molds having the through hole. Using a press molding device in which a bar-shaped member corresponding to at least a part of the through hole projects in the corresponding portion in a biased state toward the other mold, a molten resin is supplied to the molding recess of the mold. After that, the mold is clamped and press-molded.

As described above, since the rod-shaped member is provided on one of the molds so as to project in the direction of the other mold, the rod-shaped member surely abuts the other mold when the molds are clamped. be able to. As a result, the molten resin does not enter between the rod-shaped member and the other mold, and the rod-shaped member and the other mold can form a complete through-hole at the same time as press molding. Like The urging means for urging the rod-shaped member is arbitrary, but for example, a coil spring, a hydraulic urging mechanism, a gas pressure urging mechanism,
An electromagnetic biasing mechanism or the like can be used.

According to a second aspect of the present invention, in the molding method of the first aspect, the one die is a lower die, and the other die has a penetrating portion corresponding to the through hole of the upper die. It is characterized in that a convex portion corresponding to at least a part of the hole is formed. A third invention of the present invention is the molding method according to the first invention, wherein the one die is a lower die and the rod-shaped member is provided in a portion corresponding to the through hole of an upper die which is the other die. It is characterized in that a concave portion into which the portion is fitted is formed.

According to a fourth aspect of the present invention, in the molding method according to the first aspect of the present invention, the one die is an upper die, and the other die is a penetrating portion corresponding to the through hole of the lower die. It is characterized in that a bar-shaped projection corresponding to at least a part of the hole is formed. That is, in this case, a bar-shaped member corresponding to at least a part of the through hole is urged toward the lower mold in a portion corresponding to the through hole of the upper mold so as to project. In the first to fourth inventions, when the molten resin is supplied into the cavity, the tip of the rod-shaped projection of the lower die is not covered with the molten resin.

A fifth invention of the present invention is a method for molding a press-formed product having a through hole, comprising a pair of lower mold and upper mold, wherein the through hole is formed in a portion corresponding to the through hole of the lower mold. A press forming apparatus is used in which a bar-shaped projection corresponding to at least a part of the bar-shaped projection protrudes in the upper mold direction, and a hole portion into which a part of the bar-shaped projection is fitted is formed in a portion of the upper mold where a through hole is to be formed. Then, after the molten resin is supplied to the molding recess of the lower mold, the mold is clamped and press molding is performed.

It is preferable that the diameter of the rod-shaped projection is substantially equal to the diameter of the hole so that no gap is formed between the rod-shaped projection and the hole. In the case of the molding method according to the fifth aspect of the present invention, since the rod-shaped member of the lower mold is inserted into the hole of the upper mold when the mold is clamped, the molten resin does not exist in the portion corresponding to the through hole. With the rod-shaped projection, a complete through hole can be formed simultaneously with press molding.

[0010]

EXAMPLE A method of forming a press-formed product having a through hole according to the first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the press molding apparatus 11 used in this embodiment is configured to include a lower mold 12 that is one mold and an upper mold 13 that is the other mold. Lower mold 12
Has a cavity forming portion 14, a base 15 and a supporting portion 16 for the cavity forming portion 14.

The cavity forming portion 14 is formed with a recess 19 corresponding to a molded product (see FIG. 3) 18 having a through hole 17 to be molded. This cavity forming part
In a portion corresponding to the through hole 17 of 14, a bar-shaped member 21 for forming a part of the through hole 17 is provided in a protruding manner,
Moreover, the rod-shaped member 21 is provided so as to project toward the upper mold 13 in a biased state. As a specific structure, the rod-shaped member 21 is provided at a position corresponding to the through hole 17 of the cavity forming portion 14.
A through-hole portion 22 that can move up and down is formed.
A coil spring 23, which is an urging means for the rod-shaped member 21, is inserted in the cylindrical portion 24 below the. In the lower part of the rod-shaped member 21,
Stopper portion 25 locked to the lower surface of the cavity forming portion 14
Are formed.

As shown in FIG. 3, the through hole 17 of the molded product 18 has a large diameter portion 26 on one end (upper end) side and a small diameter portion 27 in the middle.
And a large diameter portion 28 on the other end (lower end) side. The rod-shaped member 21 is for forming an intermediate small-diameter portion 27 which is a part of the through hole 17. A convex portion 29 corresponding to the large diameter portion 28 on the other end side is formed around the upper side of the through hole portion 22.

On the other hand, in the portion of the upper die 12 corresponding to the through hole 17, a convex portion 31 corresponding to the large diameter portion 26 on one end side of the through hole 17 is formed. In order to prevent a gap from being formed between the rod-shaped member 21 and the convex portion 31 of the upper die 12 when the rod-shaped member 21 is clamped, the rod-shaped member 21 is placed before the upper die 13 contacts the lower die 12. The member 21 needs to be able to contact the convex portion 31 of the upper mold 12. Therefore, the length of the rod-shaped member 21 or the degree of protrusion is appropriately adjusted in this way.

Next, the molding method of this embodiment using the press molding apparatus 11 will be described. First, as shown in FIG. 1, in the lower mold 12, the rod-shaped member 21 is replaced by a coil spring.
It is located at the top by the elastic force of 23. In this state, after supplying the molten resin 32 into the recess 19 of the lower mold 12,
As shown in FIG. 2, the upper die 12 is lowered and the die is clamped. When the molten resin 32 is supplied, the tip of the rod-shaped member 21 is not covered with the molten resin 32.

At the time of this mold clamping, after the rod-shaped member 21 comes into contact with the convex portion 31 of the upper mold 13, the rod-shaped member 21 is made into the convex portion.
The rod-shaped member 21 stops moving when the upper die 13 comes into contact with the lower die 12 and the die is closed by being pushed down against the repulsive force of the coil spring 23 by 31. Therefore, at the time of this press molding, since there is no gap between the rod-shaped member 21 and the convex portion 31 so that the molten resin 32 can enter, the thin-skin resin is formed in the portion to be the through hole as in the conventional case. There is no possibility that it will remain and the through hole will be blocked. As shown in FIG. 3, the press-formed product 18 thus obtained has a through hole 17 formed in a complete state. This press molded product
In the through hole 17 of 18, for example, a pair of rubber anti-slip members 30A,
Install so that 30B is fitted.

According to the method for forming the press-formed product 18 having the through-holes 17 according to the above-mentioned embodiment, since the bar-shaped member 21 is provided on the lower mold 12 in the biased state toward the upper mold 13, When tightening, the rod-shaped member 21 is elastically pressed against the convex portion 31 of the upper mold 13. As a result, the molten resin 32 does not enter between the rod-shaped member 21 and the convex portion 31 of the upper mold 13,
With the rod-shaped member 21 and the upper mold 13, a complete through hole 17 can be formed in the molded product 18 simultaneously with press molding.

Since the urging force of the rod-shaped member 21 is obtained by the coil spring 23 inserted in the cylindrical portion 24 of the cavity forming portion 14, the structure is simple. Further, the rod-shaped member 21, the convex portion 29 of the cavity forming portion 14, and the upper mold
By changing the shape of the convex portion 31 of 13, the through hole 17 of an arbitrary shape can be formed in a perfect state simultaneously with the press molding of the molded product 18.

Next, a method of forming a press-formed product having through holes according to the second embodiment of the present invention will be described with reference to FIG. The press molding apparatus 33 used in this embodiment is
Although the lower mold 12 and the upper mold 13 are provided as in the first embodiment, the structure of the upper mold 13 is slightly different. That is, in the case of the upper mold 13 of the present embodiment, the recess 34 into which a part of the rod-shaped member 21 is fitted is formed in the portion corresponding to the through hole of the molded product of the upper mold 13. The diameter of the recess 34 is substantially equal to the diameter of the portion into which the rod-shaped member 21 is fitted.

When press-molding using such a press-molding device 33, the tip end portion of the rod-shaped member 21 has the concave portion 34.
When the rod-shaped member 21 is pressed into the recess 34 by the coil spring 23, the upper die 13 continues to contact the lower die 12 to close the die. Therefore, also in this embodiment, since the molten resin 32 does not exist in the portion to be the through hole of the molded product, the complete through hole can be formed in the molded product simultaneously with the press molding. In the case of the bar-shaped member 21 shown in the drawing, through holes are formed in a cylindrical shape having the same diameter in the obtained press-formed product. However, by changing the shape of the bar-shaped member 21 or the like, for example, the first embodiment Through holes having the same shape can be arbitrarily formed.

Next, a method of forming a press-formed product having through holes according to the third embodiment of the present invention will be described with reference to FIG. The press molding device 35 used in this embodiment is
Contrary to the first embodiment, the rod-shaped member 36 in the biased state is provided so as to project toward the upper mold 13, and the rod-shaped projection 37 in the fixed state is provided at the lower side. The rod-shaped member 36 of the upper mold 13 is a molded product as shown in FIG.
When molding 18, one end (upper end) that is part of the through hole 17
This is for forming the large diameter portion 26 on the side.

As a concrete structure, the through hole of the upper mold 13
A coil spring 23 as an urging means is housed in a recess 38 formed in a portion where the 17 is located, and a part of the rod-shaped member 36 is guided to the recess 38 at the tip (lower end) of the coil spring 23. Is installed as. On the other hand, a stepped rod-shaped projection 37 formed in the portion of the lower die 12 where the through hole 17 is located.
Is for forming the intermediate small-diameter portion 27 and the large-diameter portion 28 on the other end side. Even in the case of performing press molding in the same manner as in the above embodiment using the press molding apparatus 35, the pressure contact state between the rod-shaped member 36 and the rod-shaped projection 37 is obtained,
Since the molten resin 32 does not enter between the both 36 and 37, a complete through hole can be formed in the molded product simultaneously with the press molding.

Next, a method of forming a press-formed product having through holes according to the fourth embodiment of the present invention will be described with reference to FIG. The press molding device 41 used in this embodiment is
A pair of lower mold 12 and upper mold 13 is provided. At the portion corresponding to the through hole of the molded product of the lower mold 12, a stepped rod-shaped projection 42 for forming an intermediate small-diameter portion and a large-diameter portion on the other end side is formed in the upper mold, as in the third embodiment. It is formed in 13 directions.

On the other hand, a hole portion 43 into which a part of the rod-shaped member 42 is fitted is formed in a portion of the upper die 13 where the through hole is to be formed.
Are formed. The hole portion 43 is a through hole that is cut out on the upper surface side of the upper mold 13. The height of the tip of the rod-shaped member 42 is set so that it is fitted into the hole 43 when the mold is closed. Further, the diameter of the rod-shaped member 42 is set so that a gap is not formed between the rod-shaped member 42 and the hole 43 to be fitted therein.
Is approximately equal to the diameter of.

When such a press molding apparatus 41 is used, when the mold is clamped, first, the tip end of the rod-shaped projection 42 is moved to the upper mold.
The upper mold 13 is fitted into the hole 43 of the mold 13, and subsequently the upper mold 13 is brought into contact with the lower mold 12 to close the mold. Therefore, since the molten resin 32 does not exist in the portion corresponding to the through hole of the molded product,
As in the fourth to fourth embodiments, a complete through hole can be formed in the molded product simultaneously with press molding.

[0025]

According to the method for forming a press-formed product having a through hole according to the first to fourth aspects of the present invention, the portion corresponding to the through hole of one mold has a rod shape corresponding to at least a part of the through hole. Since the member is molded using the press molding device in which the member projects in the other mold direction in a biased state, it is possible to form a complete through hole at the same time as molding. Further, according to the method for forming a press-formed product having a through hole according to the fifth aspect of the present invention, a bar-shaped projection corresponding to at least a part of the through hole projects in the upper mold direction at a portion corresponding to the through hole of the lower mold. Formed using a press molding machine in which a hole for inserting a part of the rod-shaped projection is formed in the portion where the through hole of the upper die is to be formed, so a complete through hole is formed at the same time as molding can do.

[Brief description of drawings]

FIG. 1 is a sectional view of a press molding apparatus used in a molding method according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a press molding apparatus showing a molding method according to the first embodiment.

FIG. 3 is a cross-sectional view of a molded product obtained by the molding method according to the first embodiment.

FIG. 4 is a cross-sectional view of a press molding apparatus used in the molding method according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a press molding apparatus used in the molding method according to the third embodiment of the present invention.

FIG. 6 is a cross-sectional view of a press molding apparatus used in a molding method according to a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view of a press molding apparatus used in a molding method according to a conventional example.

FIG. 8 is a cross-sectional view of a molded product obtained by a molding method according to a conventional example.

[Explanation of symbols]

 11,33,35,41 Press molding equipment 12 Lower mold 13 Upper mold 14 Cavity forming part 17 Molded product through hole 18 Molded product 19 Molding recess 21 Lower mold bar member 22 Through hole part 23 Coil as biasing means Spring 32 Molten resin 36 Upper mold bar-shaped member 37,42 Lower mold bar-shaped projection 43 Upper mold hole

Claims (5)

[Claims] 1. A method of molding a press-formed product having a through hole, comprising a pair of upper and lower molds, and a rod-shaped part corresponding to at least a part of the through hole in a part of one mold corresponding to the through hole. Using a press molding device in which a member is projected in a biased state in the other mold direction, after supplying molten resin to the molding recess of the mold, the mold is clamped for press molding. Forming method of a press-formed product having a through hole. 2. The method for forming a press-formed product having a through hole according to claim 1, wherein the one die is a lower die and the other die is a portion corresponding to the through hole of an upper die. A method of forming a press-formed product having a through hole, characterized in that a convex portion corresponding to at least a part of the through hole is formed in the. 3. The method for forming a press-formed product having a through hole according to claim 1, wherein the one die is a lower die and the other die is a portion corresponding to the through hole of an upper die. A method for forming a press-formed product having a through hole, characterized in that a recess is formed in which a part of the rod-shaped member is fitted. 4. The method for molding a press-formed product having a through hole according to claim 1, wherein the one die is an upper die and a portion corresponding to the through hole of a lower die which is the other die. A method for forming a press-formed product having a through hole, characterized in that a bar-shaped projection corresponding to at least a part of the through hole is formed in the. 5. A method of molding a press-molded article having a through hole, comprising a pair of lower mold and upper mold, wherein a portion of the lower mold corresponding to the through hole has a rod shape corresponding to at least a part of the through hole. Using a press molding apparatus in which a protrusion is provided in the direction of the upper mold and a hole portion into which a part of the rod-shaped protrusion is fitted is formed in a portion of the upper mold where a through hole is to be formed, A method for molding a press-molded article having a through hole, comprising: supplying a molten resin to a molding recess and then clamping the die for press-molding.