JP2013240903A - Transfer molding apparatus, and method of manufacturing rubber product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently separate a piston die from a pot die in a transfer molding die, while suppressing a molded article from degating.SOLUTION: A transfer molding apparatus includes a transfer molding die, and a separation means. The transfer molding die includes: a mold body having a cavity; a pot part for throwing molding materials; a pot die having an injection hole in communication with the cavity from the pot part; and a piston die for injecting the molding materials inside the pot part by pushing the material by lowering. The separation means includes a pressing plate that horizontally advances to the pot die from a stand-by position, and abuts with an upper surface of the pot die by line contact at an advancing position.

Description

  The present invention relates to a transfer molding apparatus capable of efficiently separating a piston mold and a pot mold in a transfer molding die while suppressing gate breakage of a molded product, and a rubber product manufacturing method using the transfer molding apparatus.

  Transfer molding is widely known as a method for producing rubber products such as rubber rollers (see, for example, Patent Document 1). As conceptually shown in FIG. 6 (A), a mold a used for transfer molding includes a mold body c having a molding cavity b, a pot mold d sequentially placed thereon, and a piston. A type e is included.

  The pot mold d is provided with a potting portion d1 for injecting a molding material that is recessed on the upper surface thereof, and an injection hole d2 that leads from the pot portion d1 to the cavity b. The piston mold e protrudes from the lower surface thereof with a plunger portion e1 that fits into the pot portion d1. The piston mold e is supported by a lifting platform (not shown) of a press machine via a platen plate f so as to be movable up and down, and the mold body c is fixed on a pressing machine (not shown) via a platen plate f. ) Is supported. Then, as shown in FIG. 5B, the molding material G put in the pot part d1 is pushed by the lowering of the piston mold e by a press machine, and injected into the cavity b through the injection hole d2. As a result, the rubber product W is molded.

  In addition, after the molding, in order to take out the rubber product W, it is necessary to first lift only the piston mold e and separate it from the pot mold d. As shown in FIG. Used. The holding plate h1 is advanced by the air cylinder h2 and comes into contact with the upper surface ds of the pot mold d, thereby preventing the pot mold d from adhering to the piston mold e and rising together. Separate from d.

  However, as shown in FIG. 4D, when the piston mold e rises and separates from the pot mold d, the internal rubber product W expands due to the release of compression or temperature rise, and lifts the pot mold d. For this reason, the resistance between the pot mold d and the pressing plate h1 increases, and the air cylinder h2 becomes insufficient in force, and the pressing plate h1 cannot be moved back to the standby position.

  Therefore, in the prior art, as shown in FIG. 7A, the pressing plate h1 is inserted in advance at a distance L from the upper surface ds of the pot mold d, thereby reducing the resistance at the time of backward movement. However, in this case, when the piston mold e is raised, a gap j is generated between the pot mold d and the mold body c. As a result, the rubber product W is cut out of the gate, which causes a problem that the efficiency of taking out the rubber product W from the cavity b is lowered.

Japanese Patent Laid-Open No. 2001-121583

  The present invention is based on the fact that the upper surface of the pot mold and the pressing plate are brought into contact with each other by line contact, and the resistance of the pressing plate can be reduced, and the operation when the pressing plate is retracted while suppressing the gate breakage of the molded product. It is an object of the present invention to provide a transfer molding apparatus capable of preventing defects and a method for producing a rubber product using the same.

In order to solve the above-mentioned problems, the invention of claim 1 of the present application is a mold body having a molding cavity, a pot for placing molding material placed on the mold body and recessed in the upper surface. And a pot mold having an injection hole that leads from the pot part to the cavity, and a molding material that is placed on the pot mold and pushed into the pot part by being lowered, and then passes through the injection hole. A transfer mold having a piston mold to be injected into the cavity
In addition, when the piston mold is raised after molding, it comprises separation means for separating the piston mold from the pot mold,
The separating means includes a holding plate that advances horizontally from the standby position outside the pot mold toward the pot mold and prevents the pot mold from rising by contacting the upper surface of the pot mold at the advanced position. And a moving tool for horizontally moving the pressing plate, and the contact is a line contact.

  According to a second aspect of the present invention, the moving tool is an air cylinder.

  According to a third aspect of the present invention, the abutting surface on the pot mold side that abuts is a horizontal surface, and the abutting surface on the pressing plate side is an inclined surface that is inclined upward in the forward direction.

  According to a fourth aspect of the present invention, the abutting surface on the pot mold side that abuts is an inclined surface that is inclined upward in the forward direction, and the abutting surface on the pressing plate side is a horizontal plane.

  A fifth aspect of the present invention is a method for producing a rubber product, characterized in that it has a molding step using the transfer molding apparatus according to any one of the first to fourth aspects.

  In the present invention, as described above, the pressing plate and the upper surface of the pot mold are brought into contact with each other by line contact. The line contact can be achieved, for example, by setting one of the contact surface on the pot mold side and the contact surface on the holding plate side as a horizontal surface and the other as an inclined surface that is inclined upward in the forward direction. .

  And by this line contact, resistance of a pressing board and a pot type | mold can be reduced. As a result, it is possible to suppress the occurrence of malfunctions such as the movable plate having a weak operating force, such as an air cylinder, by reliably moving the pressing plate backward. In addition, since it is not necessary to insert the holding plate so as to float from the upper surface of the pot mold, it is possible to suppress the gate breakage of the molded product and to maintain the efficiency of taking out the molded product from the cavity.

It is sectional drawing which shows one Example of the transfer molding apparatus of this invention. It is sectional drawing which decomposes | disassembles and shows a metal mold body. It is sectional drawing which shows a transfer molding apparatus when a pressing plate advances. (A) is explanatory drawing which shows the effect of the isolation | separation means of this invention, (B) is explanatory drawing which shows the effect of the conventional separation means. It is a perspective view which shows the other Example of the isolation | separation means. (A)-(D) are sectional drawings explaining the operating state of the conventional transfer molding apparatus. (A), (B) is sectional drawing explaining the problem of the conventional transfer molding apparatus.

Hereinafter, embodiments of the present invention will be described in detail.
In FIG. 1, a transfer molding apparatus 1 according to this embodiment includes a transfer molding die 2 and a separating unit 3. In this example, the case where the transfer molding apparatus 1 forms a rubber product W which is a paper feed rubber roller used in a copying machine or the like is exemplified.

  The transfer mold 2 includes a mold body 4 having a molding cavity 10, a pot mold 5 that is sequentially placed on the mold body 4, and a piston mold 6.

  As shown in FIG. 2, the mold body 4 of this example is composed of a lower mold part 4L and an upper mold part 4U. The lower mold part 4L is formed on the bottom plate part 7 with a rubber product W (in this example, a rubber roller). The cored bar portion 8 is formed upright. The bottom plate portion 7 is supported by a fixing base (not shown) of the press machine via a platen plate f. The upper mold part 4U is formed with a plurality of holes 9 concentrically inserted into the cored bar parts 8, and the cavity 10 is defined by a space between the hole 9 and the cored bar part 8. Forming.

  The pot mold 5 has a block-shaped base body 11, and a pot portion 12 for charging the molding material G is recessed in the upper surface 5S. An injection hole 13 that leads from the pot portion 12 to the cavity 10 is formed between the bottom surface of the pot portion 12 and the lower surface of the base 11. The structures of the cavity 10 and the injection hole 13 are appropriately set according to the shape, size, number of formations (number of removals) of the rubber product W to be molded.

  As shown in FIG. 1, the piston mold 6 has a block-shaped base 14, and a plunger portion 15 that projects into the pot portion 12 protrudes from the lower surface thereof. The piston mold 6 is supported by a lifting table (not shown) of a press machine through a platen plate f so as to be movable up and down. Then, when the piston mold 6 is lowered, the molding material G put into the pot portion 12 is pushed in and injected into the cavity 10 through the injection hole 13. That is, the rubber product W is molded.

  Next, the separating means 3 separates the piston mold 6 from the pot mold 5 when the piston mold 6 is lifted and removed after molding. Specifically, the separating means 3 advances horizontally from the standby position Y1 outside the pot mold 5 toward the pot mold 5 and at the advance position Y2 (shown in FIG. 3). A pressing plate 20 that contacts the upper surface 5S of the mold 5 and a moving tool 21 that horizontally moves the pressing plate 20 are configured. In the present example, an air cylinder having a weak operating force is employed as the moving tool 21.

  The pressing plate 20 can prevent the pot mold 5 from sticking to the piston mold 6 and rising together by contacting the upper surface 5S of the pot mold 5, and can separate the piston mold 6 from the pot mold 5. .

  At this time, the pressing plate 20 and the upper surface 5S of the pot mold 5 are in contact with each other by line contact. In this example, the contact surface 5Sa on the pot mold 5 side is a horizontal surface 22, and the contact surface 20Sa on the holding plate 20 side is an inclined surface 23 that is inclined upward in the forward direction. Accordingly, the contact surfaces 5Sa and 20Sa can be brought into line contact with each other in the direction perpendicular to the forward direction.

As shown in FIG. 4 (A), when one contact surface is the inclined surface 23, the upward force F0 acting on the pressing plate 20 from the pot mold 5 is the amount of the direction in which the pressing plate 20 is retracted. It is decomposed into a force Fa and a component force Fb in a direction orthogonal to the inclined surface 23. Therefore, the drag (resistance) when the presser plate 20 is retracted can be expressed by the following equation. However, the symbol μ is a friction coefficient between the pot mold 5 and the pressing plate 20.
Drag = Friction force A-Component force Fa
(Friction force A = μ × Fb)
On the other hand, as shown in FIG. 4B, the conventional drag is expressed by the following equation.
Drag = friction force B
(Friction force B = μ × F0)

  Therefore, in the separating means 3 of the present invention, the drag (resistance) when the presser plate 20 is moved backward can be greatly reduced, and the presser plate can be reliably moved backward even by a moving tool having a weak operating force such as an air cylinder. Occurrence of malfunction such as being able to be moved can be suppressed.

  Note that the angle θ of the inclined surface 23 with respect to the horizontal plane 22 is not particularly defined, but if it is too small, the presser plate 20 becomes a sword tip and causes a decrease in strength, and conversely, if it is too large, the resistance reduction effect is insufficient. . From such a viewpoint, the angle θ is preferably about 45 ° ± 15 °.

  FIG. 5 shows another embodiment of the separating means 3. In this example, the contact surface 5Sa on the pot mold 5 side is formed as an inclined surface 23 inclined upward in the forward direction, and the contact surface 20Sa on the holding plate 20 side is formed as a horizontal surface 22. Also in this case, the drag (resistance) when the presser plate 20 is retracted can be similarly reduced.

  The rubber product W is formed by a manufacturing method having a molding process using the transfer molding apparatus 1.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  In order to confirm the effect of the present invention, a transfer molding die having the structure shown in FIG. 1 was used to form a rubber roller for a copying machine. The rubber roller has an outer diameter of 16 mm, an inner diameter of 11 mm, and a length of 90 mm. The additive (calcium carbonate 10 phr, titanium oxide 2 phr, oil 50 phr, carbon black 1 phr) with respect to 100 parts by mass of ethylene propylene rubber (EPDM) as a molding material. 1 phr peroxide) was used. In addition, the transfer mold used can mold 100 rubber rollers at a time.

The molding conditions are as follows.
Vulcanization temperature: 160 ° C
Vulcanization time: 20 minutes Injection time: 30 seconds Press pressure: 150t

  In Example 1, the separating unit shown in FIG. 3 is used, in Example 2, the separating unit shown in FIG. 5 is used, and in Comparative Example 1, the separating unit shown in FIG. 7 is used. Note that the angle θ of the inclined surface in Examples 1 and 2 is 45 °. In Comparative Example 1, the separation distance L between the press plate and the pot mold upper surface was 2 mm.

  In each of Examples 1 and 2 and Comparative Example 1, molding was performed 100 times, and when the number of rubber rollers that caused gate breakage during one molding was less than 10% (less than 10), OK, 10% The above (10 or more) cases were evaluated as NG. The one where the number of times of OK molding is large is superior.

DESCRIPTION OF SYMBOLS 1 Transfer molding apparatus 2 Transfer molding die 3 Separation means 4 Mold main body 5 Pot die 5S Upper surface 6 Piston die 10 Cavity 12 Pot part 13 Injection hole 20 Holding plate 21 Moving tool 22 Horizontal surface 23 Inclined surface G Molding material Y1 Standby position Y2 Advance position

Claims (5)

A mold body having a cavity for molding,
A pot mold that is placed on the mold main body and has a pot portion for molding material that is recessed on the upper surface, and an injection hole that leads from the pot portion to the cavity,
And a transfer mold including a piston mold that is placed on the pot mold and that pushes the molding material that is put into the pot portion by lowering to inject into the cavity through the injection hole,
In addition, when the piston mold is raised after molding, it comprises separation means for separating the piston mold from the pot mold,
The separating means includes a holding plate that advances horizontally from the standby position outside the pot mold toward the pot mold and prevents the pot mold from rising by contacting the upper surface of the pot mold at the advanced position. A transfer molding apparatus comprising: a moving tool for horizontally moving the pressing plate; and the contact is a line contact.   The transfer molding apparatus according to claim 1, wherein the moving tool is an air cylinder.   3. The abutting surface on the pot mold side that abuts is a horizontal plane, and the abutting surface on the pressing plate side is an inclined surface that is inclined upward in the forward direction. Transfer molding equipment.   3. The contact surface on the pot mold side that abuts is an inclined surface that is inclined upward in the forward direction, and the contact surface on the holding plate side is a horizontal surface. Transfer molding equipment.   A method for producing a rubber product, comprising a molding step using the transfer molding apparatus according to claim 1.

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