JP2549544B2 - METHOD FOR PRODUCING FOAM MOLDED ARTICLE AND FORM FOR MAKING FOAM MOLDED ARTICLE USED IN THE METHOD - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a cavity-shaped foamed molded product by injecting a foaming raw material into a mold cavity, and a foamed molded product manufacturing mold used for the method.

(Prior Art) As a method for producing a foam molded article used for a seat cushion or the like, a foam raw material such as a polyurethane raw material is injected into a cavity of a mold for producing a foam molded article, and the foam raw material is foamed into a cavity shape. There is a manufacturing method that allows

By the way, the foaming raw material injected into the cavity fills the cavity by foaming and becomes a foam molded article. Therefore, if there is a gas reservoir in the cavity, the foaming material cannot be completely filled in the cavity due to the gas reservoir, resulting in defects such as voids (holes) and lack of thickness in the foam molded product at the gas reservoir portion. .

Therefore, in the conventional case, the foaming gas generated from the air and the foaming raw material existing in the cavity in advance,
When the foaming raw material is foamed, it escapes to the outside of the cavity, and therefore the following is performed during the production of the foamed molded product. A gas vent hole is provided in the upper mold, and the gas in the cavity is discharged to the outside through the gas vent hole. Provide a gas vent hole in the upper mold, and then attach a valve biased by a spring to the gas vent hole, and when the pressure inside the cavity exceeds a certain level, lift the valve by that pressure and open the gas vent hole. Open and discharge the gas in the cavity to the outside. For example, a gate or the like is provided on the divided surface of the mold, and gas is allowed to escape to the outside of the cavity through the gate or the like.

(Problems to be solved by the invention) However, in all of the above, since the foaming raw material enters the degassing hole or the gate to form burrs and foam and harden, the foamed cured product around the degassing hole and the gate is removed in each case. It has to be removed manually, which is a time-consuming task. Further, in order to facilitate the removal of the foamed cured product, a mold release agent must be applied in advance in the gas vent hole or the like, which requires additional work.

Therefore, the present invention is directed to a method for producing a foamed molded product capable of easily removing an unnecessary foamed cured product adhering to the periphery of a gas vent hole during the production of the foamed molded product, and the production of the foamed molded product used for carrying out the manufacturing method. It is intended to provide a usage pattern.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a method for producing a foam-molded article, in which a foaming raw material is injected into a mold cavity to foam-mold a cavity-shaped foam. From the mold to a gas vent hole that communicates with the outside of the mold, insert a piston with a diameter slightly smaller than the diameter of the gas vent hole into the gas vent hole, foam the foaming raw material in the cavity, and after the foaming is completed. By sliding the piston in the gas vent hole, the foamed hardened material attached to the periphery of the piston is pushed out from the gas vent hole.

Further, in order to enable the implementation of the manufacturing method, a gas vent hole communicating from the inside of the mold cavity to the outside of the mold is provided in the mold, and a piston having a diameter 1/100 to 1/5 mm smaller than the diameter of the gas vent hole, It was slidably inserted into the gas vent hole to form a foam molding product manufacturing mold.

(Function) The foaming raw material injected into the mold cavity fills the cavity by foaming. At that time, the air existing in the cavity in advance and the foaming gas generated from the foaming raw material are driven to the upper part of the cavity as the foaming raw material fills the cavity, and the gap between the inner peripheral surface of the gas vent hole and the outer peripheral surface of the piston. Escape through the cavity.

On the other hand, the foaming raw material cannot enter the gap because the gap between the inner peripheral surface of the gas vent hole and the outer peripheral surface of the piston is small.
Further, even if it intrudes into the gap, the invasion is from the cavity surface to a portion slightly behind and does not leak out of the cavity. Especially, the diameter of the piston inserted in the gas vent hole is 1/100 of the diameter of the gas vent hole.
When the size is about 1/5 mm, only the gas can escape to the outside of the cavity efficiently. Therefore, the foaming raw material is foamed in the cavity without leaking out of the cavity, and becomes a cavity-shaped foam molded article.

Then, the cavity-shaped foamed molded product is taken out of the mold. At this time, in the gap between the inner peripheral surface of the gas vent hole and the outer peripheral surface of the piston, a part of the cured product of foam may remain as burr. Therefore, the piston inserted in the gas vent hole is slid by an air cylinder or the like to push out the foamed cured material attached to the periphery of the piston from the gas vent hole. The extruded foamed cured product is blown off by blowing air or the like. As a result, the cleaning around the gas vent hole is completed, and the production of the foamed molded product can be repeated.

(Example) An example of the present invention will be described below.

1 to 6 are sectional views of a manufacturing mold 10 for manufacturing a foam-molded article according to an embodiment of the present invention.

The mold 10 is composed of an upper mold 12 and a lower mold 14, and has a cavity 16 composed of an upper mold inner surface and a lower mold inner surface inside. A gas vent hole 18 is formed in the upper mold 12, and a piston 20 that slides up and down is inserted in the gas vent hole 18. The piston 20 is a second enlarged view of the portion A of FIG.
As shown, the diameter a is 1/10 of the diameter b of the gas vent hole 18.
0 to 1/5 (optimum value is 1/50 to 1/25) mm small. Then, the piston 20 is released from the gas vent hole 18 by the expansion and contraction of the air cylinder 22 or other vertical movement means (not shown).
Is designed to slide up and down. The gas vent hole 18 in this example has a structure in which a metal collar 26 is fitted in the upper die 12 to prevent abrasion of the inner surface of the gas vent hole due to sliding of the piston 20, but depending on the material of the die, the collar 26 may be omitted.

As shown in FIG. 1, a foam material 24 such as a polyurethane material is injected into the cavity 16 of the mold 10 to manufacture a foam molded article. At this time, the tip end surface 28 of the piston 20 is substantially at the same position as the cavity surface 30 of the upper mold as shown in FIG.

The foaming raw material 24 injected into the cavity 16 foams and fills the cavity 16. Then, the foaming gas generated at that time, the air that was previously present in the cavity, etc. are driven to the upper part of the cavity 16 as the foaming raw material 24 fills the cavity 16, and the inner peripheral surface of the gas vent hole 18 and the piston 20. It escapes to the outside of the cavity 16 through the gap 32 with the outer peripheral surface.

Then, the foaming raw material finally completely fills the inside of the cavity, and as shown in FIG.
become. During this foaming reaction, the foaming gas in the cavity is discharged to the outside of the cavity through the gap 32 between the gas vent hole and the piston as described above. On the other hand, the foaming raw material also tries to leak out of the cavity through the gap 32 after filling the cavity. However, the gap is a difference (b-a or less) between the diameter b of the gas vent hole and the diameter a of the piston, and is extremely narrow. Therefore, even if the gas can pass through, most of the foaming raw material having high viscosity enters. I can't. Further, even if the foaming raw material may enter the gap, the foaming raw material 24 may enter first from a point slightly inside the gap 32, as shown in FIG. I can't. Therefore, the foaming raw material foams in the cavity without leaking through the gap 32 to the outside of the cavity.

Thereafter, the mold 10 is opened and the foamed molded product 34 is taken out from the mold as shown in FIG. Then, the piston 20 inserted in the gas vent hole 18 is slid up and down by the operation of the air cylinder 22. FIG. 6 is an enlarged view of the C portion at that time, and the sliding of the piston 20 cures the foaming raw material that has been slightly clogged in the gap 32 between the inner peripheral surface of the gas vent hole and the outer peripheral surface of the piston. Object 36 is pushed out of vent hole 18. Next, air containing a release agent is blown around the gas vent hole 18 to blow off the foaming material cured product 36 extruded by the piston, and the cleaning of the periphery of the gas vent hole is completed and the application of the release agent is completed. .

This allows the mold 10 to be used again in the production of foam molded articles.

7 is a sectional view of the same portion as FIG. 6 for explaining the piston 38 according to another embodiment. The piston 38 has a small diameter c on the tip side and a large diameter d on the base side at a position slightly protruding from the outer surface of the mold. During foaming, a small-diameter portion having a diameter c is positioned in the gas vent hole 18 to facilitate degassing, and after foaming, the piston 38 is slid so that the large-diameter portion having a diameter d blocks the gap 32. The cured product 36 is ejected. Further, at this time, if the spiral groove 40 is provided on the surface of the large diameter portion having the diameter d, the cured product 36 in the gap can be more effectively pushed out by the groove 40.

(Effect) In the present invention, since the gas vent hole is cleaned by sliding the piston as described above, the gas vent hole can be easily cleaned, and the cleaning work does not take any trouble. Furthermore, if the piston is slid by automatic control, the gas vent hole can be automatically cleaned, and labor can be saved.

Also, because a piston with a diameter that is 1/100 to 1/5 mm smaller than the diameter of the gas vent hole is slidably inserted into the gas vent hole to form a foam molded product mold, the inner peripheral surface of the ass vent hole and the piston The foaming raw material hardly penetrates into the gap between the outer peripheral surfaces, and even if it penetrates into the gap, the amount of penetration is small, so that the gas vent hole can be easily cleaned by sliding the piston.

[Brief description of drawings]

FIG. 1 to FIG. 6 are sectional views at the time of manufacturing a foamed molded product in one embodiment of the present invention, in which FIG. 1, FIG. 3 and FIG. 5 are sectional views of a mold for manufacturing a foamed molded product, Also, FIG. 2 and FIG.
6 and 6 are enlarged cross-sectional views of a portion A, a portion B and a portion C, and FIG. 7 is a sectional view similar to FIG. 6 in another embodiment of the present invention. 18: Gas vent hole, 20: Piston, a: Piston diameter, b: Gas vent hole diameter

Claims (2)

(57) [Claims] 1. A method for producing a foamed molded product in which a foaming raw material is injected into a mold cavity to foam-mold a cavity-shaped foamed body, wherein a gas vent hole communicating from the inside of the cavity to the outside of the mold is provided in the mold. Insert a piston with a diameter slightly smaller than the diameter of the gas vent hole into the gas vent hole, foam the foaming raw material in the cavity, and slide the piston in the gas vent hole after completion of foaming to attach it around the piston. The method for producing a foam-molded article is characterized by extruding the foamed cured product from the degassing hole. 2. In a mold for producing a foamed molded product having a cavity inside, a gas vent hole communicating from the inside of the cavity to the outside of the mold is provided, and a piston having a diameter 1/100 to 1/5 mm smaller than the diameter of the gas vent hole. A mold for producing a foamed molded product, wherein the mold is slidably inserted into a gas vent hole.