JP2579797B2 - Manufacturing method of foam molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of injecting a foaming material into a mold cavity,
The present invention relates to a method for manufacturing a foam molded article, which foams a foam having a cavity shape.

(Prior Art) Conventionally, there is the following manufacturing method as a method of manufacturing a foam molded article such as a seat cushion body.

It is a method of injecting a foaming material having a free foaming volume equal to or greater than the mold cavity volume into a mold cavity, filling the mold material with the foaming pressure, and producing a foam molded product made of a cavity-shaped foam. is there.

On the other hand, a mold used for manufacturing the above-mentioned foamed molded product is a split mold having a product-shaped cavity, and the mold is provided with a vent hole called a vent hole. The vent hole discharges a foaming gas generated from the foaming material, air trapped in the cavity at the time of closing the mold, and the like out of the cavity at the time of foaming of the foaming material, and forms a gas reservoir on the surface of the foam molded article. This is to prevent voids (depressions) from being formed.

(Problems to be Solved by the Invention) However, since the vent hole remains open, the foaming material leaks from the vent hole when filling the cavity, and the foaming material in the cavity becomes insufficient. In some cases, the foamed molded product may be underfilled. In addition, there is also a disadvantage that the foaming material is wasted due to the leakage. further,
Since the leaked foaming material hardens and closes the gas vent hole, it is necessary to clean the gas vent hole and remove the foamed hardened material when manufacturing a foam molded product using the mold again. There is also a problem.

Therefore, the present invention is to provide a method of manufacturing a foam molded article which can prevent leakage of foamed raw material from a vent hole, eliminate underfill and loss of raw material of the foam molded article, and eliminate cleaning of the vent hole. It is assumed that.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention relates to a method for producing a foam molded product, which comprises injecting a foaming material into a mold cavity to foam-mold a foam having a cavity shape. A vent hole communicating between the inside and outside of the cavity is provided at the top of the cavity,
Further, the temperature detecting means is provided at a predetermined position of the cavity so as to be located below the vent hole, and when the foaming material foams and rises to the position of the temperature detecting means, the temperature of the foaming material is detected and the foaming material is detected. The position of the surface is captured, and the venting hole is closed before the foaming raw material reaches the gas venting hole, thereby foaming the foaming raw material.

Also, when the shape of the mold cavity is complicated, etc.,
In order to effectively discharge gas (air, foaming gas, etc.) in the cavity to the outside of the cavity, a plurality of pairs of gas vent holes and temperature detecting means are provided in the mold, and the temperature detecting means located at the lower position of the cavity are sequentially arranged. When the foaming raw material foams to the position of the temperature detecting means, the temperature of the foaming raw material is detected, the surface position of the foaming raw material is sequentially captured, and the gas vent hole paired with the temperature detecting means is vented. Before the foaming material reaches the hole, the foaming material is foamed by closing the cavity in order from a lower position.

(Operation) The foaming raw material injected into the cavity starts foaming with the gas vent hole opened, and rises in the cavity. At the same time, the foaming material generates heat and becomes high in temperature. Then, the foaming gas generated from the foaming raw material and the air and the like remaining in the cavity at the time of injection of the foaming raw material are discharged out of the cavity through the gas vent hole.

The surface of the foaming material rises in the cavity as the foaming reaction proceeds. When the surface of the foaming material rises to the temperature detecting device located at a lower position than the gas vent hole and touches the temperature detecting means, the temperature detecting means detects a high temperature of the foaming material. From the temperature detection, it can be seen that the surface of the foaming raw material has risen to the position of the temperature detecting means and has approached the vent hole. Then, immediately or slightly later, the vent hole is closed to prevent the foaming material from leaking out of the vent hole when the surface of the foaming raw material rises to the position of the vent hole.

Thereafter, the foamed raw material is further foamed, and finally fills the cavity completely, thereby forming a foamed molded article having a cavity shape.

In this way, the vent hole is not closed at the beginning of foaming of the foaming material, but is closed after the foaming reaction has progressed considerably and the foaming material surface has risen to the position of the temperature detecting means. Therefore, the foaming gas generated from the foaming raw material after the gas vent hole is closed, and the air and the like existing in the cavity when the gas vent hole is closed, remain in the cavity thereafter. However, by providing the gas vent hole in the upper part of the cavity and bringing the temperature detecting means close to the gas vent hole, the gas vent hole can be closed when the foaming material has foamed near the top of the cavity. The gas can be extremely reduced.

As a result, voids and the like on the surface of the foam molded article caused by the residual gas can be almost eliminated.

Further, a plurality of gas vent holes and temperature detecting means are provided in pairs in the mold, and the temperature of the foaming material foamed up to the position of the temperature detecting means is detected in order from the temperature detecting means located at the lower position of the cavity, and the temperature of the cavity is detected. If the gas vent holes are closed in order from the lower position, gas can be efficiently discharged out of the cavity even if the cavity has a complicated shape.

(Example) Hereinafter, an example of the present invention will be described.

1 to 3 are cross-sectional views of a mold showing a process of manufacturing a foam molded article in one embodiment. First, the mold and device used will be described.

The mold 10 is a split mold that is separated into upper and lower parts, and has a product-shaped cavity 12 inside. The upper die 10a is provided with two gas vent holes 14 substantially at the top.
Thus, the inside and the outside of the cavity 12 communicate with each other. Further, the gas vent hole 14 can be opened and closed by attaching and detaching the plug 18. The number of gas vent holes is appropriately determined depending on the shape of the cavity and the like.

The plug 18 is attached to an expansion / contraction device 16 such as an air cylinder or a vertical movement device (not shown). It comes out of 14.

Further, at a position slightly below the gas vent hole 14 of the upper mold, a temperature detecting means 20 made of a thermocouple or the like is directed into the cavity 12.
Is provided. The temperature detecting means 20 detects the temperature of the foamed raw material when the foamed raw material injected into the cavity 12 sequentially fills the cavity by foaming and touches the temperature detecting means 20 during the production of the foam molded article. It is for. The control device 22 is connected to the temperature detecting means 20.

The control device 22 extends the telescopic device 16 based on the temperature detection of the foaming raw material by the temperature detecting means 20, and thereby the plug 18
Is lowered to fit into the gas vent hole 14, to close the gas vent hole, and after the production of the foam molded article,
This is for retracting the expansion / contraction means to raise the plug 18 and opening the gas vent hole 14 withdrawn from the gas vent hole 14. The control device is, for example, a device that electrically switches the expansion and contraction of the air cylinder.

Next, the production of a foam molded product using the mold 10 and the like will be described.

First, as shown in FIG. 1, the telescopic device 16 is contracted, and the plug 18 is held above the upper die 10a with the plug 18 being pulled out of the gas vent hole 14.
Then, in this state, a foaming raw material 24 such as a polyurethane raw material is injected into the mold 10. The injection of the foaming raw material 24 is performed according to the structure of the mold 10, with the mold 10 kept open or with the upper mold 10 a and the lower mold 1.
This is performed under the condition where 0b is added. In the former case, the upper mold 10a and the lower mold 10b are combined after the injection of the foaming raw material 24. In the latter case, a raw material injection port (not shown) is formed in the upper mold 10a, and the upper mold 10a and the lower mold 10a are formed. With the mold 10b fitted, the foaming raw material 24 is injected into the cavity using the raw material injection port.

The foaming raw material 24 injected into the cavity 12 starts a foaming reaction and expands to fill the cavity 12 in order from the bottom. At that time, the foaming raw material 24 generates heat and becomes high temperature.

Then, when the surface of the foaming material rises to the position of the temperature detecting means 20 (the position of the dashed line) and touches the temperature detecting means 20,
The temperature detecting means 20 is rapidly heated to detect the temperature of the foaming raw material. As a result, the control device 22 connected to the temperature detection means 20 starts the extension of the extension device 18. When the telescopic device 18 is extended, the plug 18 descends as shown in FIG. 2 to fit into the gas vent hole 14 and close the gas vent hole 14.

The point at which the vent hole 14 is closed is determined by the temperature detection means.
Since 20 is located lower than the vent hole 14, the foaming raw material 24
Before the surface has reached the gas vent hole 14.

Thereafter, the foaming raw material 24 further foams and reaches the position of the gas vent hole 14. However, at that time, the vent hole 14 has already been plugged.
The foam material is closed by the gas vent holes 14
There is no danger of leakage out of the cavity.

And the foaming material finally fills the cavity,
The resulting foam 25 has a cavity shape as shown in the figure. Thereafter, if the foam 25 is taken out of the mold 10, a desired foam molded product can be obtained.

4 to 6 are cross-sectional views showing the steps of manufacturing a foam molded product according to another embodiment of the present invention. First, the mold 26 and the like to be used will be described, and then a method of manufacturing a foam molded product will be described.

The mold 26 used in this embodiment includes an upper mold 26a and a lower mold 26b. The upper mold 26a has three vent holes 28a, 28b, 28c.
And temperature detecting means 30a, 30b, 30c paired with them. These temperature sensing means are located slightly lower than the pair of vent holes. Further, a control device (not shown) is connected to each temperature detecting means, and the expansion and contraction devices 32a, 32b, and 32c start expanding and contracting by the control device. And the plug pair 34 at the tip of the telescopic device
The a, 34b, and 34c move up and down due to expansion and contraction of the expansion and contraction device, come out of the gas vent holes 28a, 28b, and 28c, or fit into the gas vent holes, thereby opening and closing the gas vent holes.

Using the mold 26 and the like, a foam molded product is manufactured as follows.

First, the foaming raw material 24 is injected into the mold cavity 36. At this time, all the telescopic devices 32a, 32b and 32c are contracted as shown in FIG. 4, and all the plugs 34a, 34b and 34c are
a, 28b, and 28c, and the gas vent hole is open.

The foaming raw material 24 injected into the cavity foams and fills the cavity 36 from below while generating heat. Then, the surface of the foaming material rises to the temperature detecting means 30a at a low position of the cavity, and when the temperature detecting means 30a is touched, the temperature of the foaming material is detected by the temperature detecting means 30a. At the same time, the expansion and contraction device 32a is extended by a control device (not shown) connected to the temperature detecting means 30a, and the plug 34b is fitted into the gas vent hole 28a as shown in FIG. Close the hole 28a.

After that, the foaming raw material 24 further foams, passes through the already closed gas vent hole 28a, and rises to the next temperature detecting means 30b. When the surface of the foaming raw material touches the temperature detecting means 30b, the temperature of the foaming raw material surface is detected, and the control device (not shown) connected to the temperature detecting means 30b starts the extension of the telescopic device 32b. And the sixth
As shown, the plug 34b fits into the gas vent hole 28b. Thereby, the vent hole 28b is closed.

Subsequently, the surface of the foaming raw material 24 rises, crosses the position of the already closed gas vent hole 28b, and the temperature detecting means 30c thereon.
Leads to. And the temperature of the foaming material surface is detected,
The expansion and contraction device 32c extends in the same manner as described above, and the gas vent hole 28c is closed by the plug 34c.

During this time, the foaming gas generated from the foaming material and the air and the like remaining in the cavity are repelled to the upper portion of the cavity as the surface of the foaming material rises, and each gas vent hole (28
a, 28b, 28c) are discharged out of the cavity. At this time, since a plurality of gas vent holes are provided from the low position to the high position of the cavity, gas can be discharged out of the cavity extremely efficiently. Moreover, each vent hole is closed before the surface of the foaming raw material reaches the vent hole. Therefore, the foaming material does not leak from the vent hole.

The foaming raw material then completely fills the cavity to form a cavity-shaped foam. The desired foam molded article can be obtained by removing the foam from the mold.

(Effect) As described above, according to the present invention, when foaming material injected into the cavity is foamed, the position of the surface of the foaming material rising in the cavity is caught by the temperature detecting means,
Before the surface of the foaming material rises to the position of the gas vent hole, the gas vent hole is closed to foam the foam material.

Therefore, there is no danger that the foaming material leaks from the gas vent hole, and there is an effect that a good foamed molded product without underfill is obtained. In addition, there is an effect that the foaming material does not flow out of the cavity and is wasted. Furthermore, since the foaming raw material does not flow into the gas vent hole and undergoes foaming hardening, there are also operational advantages such that the gas vent hole is not clogged and the gas vent hole does not need to be cleaned.

Also, even when the cavity shape is complicated, by providing a plurality of gas vent holes and closing the gas vent holes in order from the lower position of the cavity, the foaming gas and the like can be efficiently discharged to the outside of the cavity, and the foam molded article can be formed. There is also an effect that voids due to gas accumulation can be prevented.

[Brief description of the drawings]

1 to 3 are cross-sectional views showing manufacturing steps in one embodiment of the present invention, and FIGS. 4 to 6 are cross-sectional views showing manufacturing steps in another embodiment of the present invention. 14, 28a, 28b, 28c: Gas vent hole, 20 , 30a, 30b, 30c: Temperature detection means

Claims (2)

(57) [Claims] 1. A method for producing a foamed molded product, comprising: injecting a foaming material into a mold cavity and foam-forming a foam having the cavity shape, wherein a gas vent hole communicating between the inside and outside of the cavity is provided at an upper portion of the cavity. Temperature detection means is provided at a predetermined position of the cavity below the vent hole, and when the foaming material foams and rises to the position of the temperature detection means, the temperature of the foaming material is detected and the surface position of the foaming material is captured, A foaming raw material is foamed by closing the gas vent hole before the foam raw material reaches the gas vent hole in accordance with the method described above. 2. A plurality of gas vent holes and temperature detecting means are provided in pairs in a mold, and when the foaming raw material foams up to the position of the temperature detecting means in order from the temperature detecting means at the lower position of the cavity, The temperature is detected, the surface position of the foaming material is captured in order, and accordingly, before the foaming material reaches the gas venting hole paired with the temperature detecting means, the gas venting holes are sequentially closed from the lower position of the cavity. The method for producing a foam molded article according to claim 1, wherein the foaming raw material is foamed.