JPH06206242A - Check valve of mold for closed injection - Google Patents

Abstract

PURPOSE:To prevent a foaming material certainly from flowing backwards by a method wherein a head is enabled to leave from a metal mold just after injection when the foaming material is injected into a closed mold. CONSTITUTION:In a metal mold for closed injection which injects a foaming material into a metal mold by making a head 22 abut against a sprue 20 formed on a partition face of the metal mold, a first valve half body 24 which is set to a bottom force sprue and in which a first diaphragm 30 blockading the sprue is formed, and a second valve half body 26 which is set to a top force sprue and in which a second diaphragm 36 blockading the sprue is formed, are provided. Both valve half bodies are stuck close to each other in closing of the metal mold to form a part 42 on an interface of both diaphragms. Further, both diaphragms are deformed by pressure of the foaming material from the head and allows the foaming material to enter from the split part. Besides, when injection of the foaming material from the head is stopped, the split part is closed and comes to have strength how it is not opened by foaming pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of releasing a material injection head from a sprue of a mold immediately after material injection when pressure-injecting a foam material such as polyurethane into a cavity of a divided mold. The present invention also relates to a check valve of a closed injection mold that can surely prevent the backflow of the foam material without inserting the plug uncertainly.

[0002]

2. Description of the Related Art For example, a foamed polyurethane product is molded by injecting a catalyst for curing reaction, a foaming agent, a foam stabilizer, etc. into the mold cavity into the main components of diisocyanate and polyol. Means for injecting these materials for foam molding (hereinafter referred to as "foam material") into a mold are roughly classified into an open injection method and a closed injection method. That is, in the open injection method, in a split mold including an upper mold and a lower mold, a foam material is injected into a cavity of the lower mold with the mold opened, and then the upper mold and the lower mold are closed to form the cavity. In this, the foaming reaction proceeds. In the closed pouring method, the pouring material pouring head is pressed against the sprue of the split mold in which the upper mold and the lower mold are closed, and the foaming material is injected into the cavity while the mold is sealed. Is.

Since the present invention relates to a check valve which can be preferably used in carrying out the latter closed injection method, the characteristics of the closed injection method will be briefly described. As described above, in the closed injection method, the injection head is pressed against the sprue of the split mold to inject the foam material into the cavity. When the injection head is immediately removed from the sprue after completion of this injection, and the plug (plug) is not inserted into the sprue, the gas generated from the foamed material and the residual air in the cavity are initially exposed through the sprue. Escape to. Following this, the foamed material that gelled,
It is pushed by the foaming pressure and flows back from the sprue to the outside. In this case, since the foaming pressure does not act uniformly inside the cavity, a desired good foam molded article cannot be obtained. Therefore, in practice, in order to prevent the foamed material after injection from flowing backward from the sprue, a plug is closely fitted to the sprue, or the injection head is used for a required time even after the injection of the foamed material is completed. Is pressed against the sprue and so on. Further, an attempt has also been made to intentionally heat the circumference of the sprue to promote the reaction of the foamed material so that the foamed material having a high viscosity stays in the sprue, and thereby substitutes for the plug. .

[0004]

As described above, the method of inserting the plug into the sprue of the mold after injecting the foam material is as follows.
There is no resistance in the runner that connects the sprue and the cavity,
It is often used when the foamed material is relatively smoothly fed into the cavity and does not stay near the sprue. Even in this case, the timing of inserting the plug into the sprue should be set as late as possible in order to sufficiently release the gas generated from the foam material. However, considering that there are variations in molding conditions, this timing cannot be delayed too much, and there is a unavoidable situation in which there is no choice but to set it too early, and at this time, the degassing is often insufficient. . Also, since the movement of plugging is usually performed by a simple device, the force of pressing the plug against the sprue is weak, and if the foamed material remains on the sealing surface, the sealing performance deteriorates. In some cases, the foam material may leak and the foaming pressure may decrease, resulting in defective molding. Also, since the plug is inserted into the sprue by a simple device, the pressing force of the plug is generally weak. For this reason, if the foamed material remains on the sealing surface between the sprue and the plug, the sealing performance may deteriorate, and in some cases the foamed material may flow back due to the foaming pressure to push the plug away, causing the material to leak or the foaming pressure to decrease. It is also known that molding defects also occur.

The method of keeping the injection head pressed against the sprue after material injection is mainly used in the case of high pressure injection. At this time, since the foamed material continues from the sprue of the mold to the runner connecting the cavities, when the injection head is detached from the sprue, the foamed material immediately overflows from the sprue. Therefore, it is pointed out that the injection head cannot be separated from the mold for a certain period of time until the reaction of the foamed material settles down, and sometimes the sprue of the injection head is clogged with the reacted foamed material. This is a major limitation in designing a production line for foam-molded products. Further, unlike the case of low-pressure injection, it is impossible to perform degassing from the sprue, and another method must be taken for degassing.

[0006]

It is an object of the present invention, for example, to perform closed injection of polyurethane foam material into the cavities of a split mold, the material injection head being disengaged from the mold sprue immediately after injection of the foam material, and An object of the present invention is to provide a check valve capable of reliably preventing the backflow of foamed material without relying on an uncertain plug insertion.

[0007]

SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems and achieve an intended object, the present invention closes a lower mold and an upper mold constituting a split mold and forms them on the mold dividing surface. In a closed injection mold in which a foam material injection head is brought into contact with the sprue, and the foam material is pressure-injected into the cavity through the sprue and runner, the spout is detachably set to the lower mold sprue. And a first valve half body having a first diaphragm that closes the sprue facing the surface facing the outside of the mold, and the upper mold sprue, and is detachably set to direct the outside of the mold. And a second valve half body having a second diaphragm formed to close the sprue so as to face the surface to be closed. When the lower mold and the upper mold are closed, the first valve half and the second valve half are closed. The valve halves correspondingly adhere to each other A split portion is formed on a joint surface between the ram and the second diaphragm, and the first diaphragm and the second diaphragm are deformed by the pressure of the foam material injected from the injection head to open the split portion. When the foam material is allowed to enter the runner and the injection of the foam material from the injection head is stopped, the split portion returns to its original shape and closes, so that the injected foam material It is characterized in that the strength is set so as not to open depending on the foaming pressure.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A check valve for a closed injection mold according to the present invention will be described below with reference to the accompanying drawings with reference to preferred embodiments. First, FIG. 1 shows a split mold 10 for closed injection in which a check valve according to an embodiment is preferably used.
FIG. 2 is a perspective view of the upper mold 1 with respect to the lower mold 12.
4 is opened upward so that the cavity 16 formed inside the mold 10 can be exposed. Lower mold 12
A runner 18 whose one end communicates with the cavity 16 is horizontally recessed in the divided surface 12a of the runner 1.
The other end of 8 also communicates with a sprue 20 formed at the side end of the lower mold dividing surface 12a. Correspondingly, the same runner (not shown) and sprue 20 are correspondingly formed on the split surface of the upper mold 14, and by sealing the lower mold 12 and the upper mold 14, the upper and lower runners and sprue are separated. Correspondingly positioned to form an inflow path for the foam material. An injection head 22 of a foam material, which will be described later with reference to FIGS. 3 and 8, is brought into contact with and separated from the sprue 20. Then, the closed injection of the foam material is performed by closing the upper mold 14 and the lower mold 12, and then pressing the injection head 22 against the sprue 20 opening on the side surface of the split mold 10. The foamed material injected into the head 22
From under pressure via sprue 20 and runner 18 into the cavity 16.

1 to 4 show a split mold 10 which employs a check valve according to a first embodiment of the present invention. In particular, as can be seen from FIG. Split surface 1
The cavity 16 formed in 2a and the sprue 20 are connected by a runner 18. The sprue 20 is formed as an open groove having a semicircular cross section.
A first valve half body 24 forming a half body of a check valve 28 described later can be accommodated therein. The first valve half 24 is configured as a semi-circular member obtained by dividing a hollow cylinder into two along the longitudinal center line, and has an excellent releasability from polyurethane (for example, silicone, ethylene propylene rubber, ethylene). Propylene diene rubber etc.) is used as the material. Inside the first valve half 24, a flow path 24a having a semicircular cross section is recessed, and when the valve half 24 is detachably set on the sprue 20, the lower mold 12
A first diaphragm 30 is formed to face the surface of the sprue 20 facing outward (the function of the first diaphragm 30 will be described later). Further, as shown in FIG. 1, a fitting piece 32 formed of a circular protrusion is provided on the back surface of the first valve half 24.
Are integrally formed along the longitudinal direction. Then, by fitting the fitting piece 32 into the fitting groove 34 provided in the bottom of the sprue 20 in the longitudinal direction of the lower mold 12, the first valve half 24 is non-rotatably attached to the lower mold 12. It is possible. Further, the first valve half 24 is attached to the sprue 2
When set to 0, the dividing surface 24b of the valve body 24 and the dividing surface 12a of the lower die 12 are set to be flatly aligned.

The sprue 20 of the upper mold 14 can also accommodate a second valve half 26 which forms a half of a check valve 28, which will be described later. The specifications of the second valve half 26 are as follows. Is exactly the same as the first valve half 24. Ie the second
Inside the valve half 26, a flow path 26a having a semicircular cross section is formed.
Is recessed, and the valve half 26 is attached to the sprue 20.
The second diaphragm 36 is formed so as to face the outer directional surface of the upper mold 14 and close the sprue 20 when set to 1. On the back surface of the second valve half 26, a fitting piece 38 formed of a circular ridge is integrally formed in the longitudinal direction. Then, by fitting the fitting piece 38 into a fitting groove 40 provided in the bottom of the sprue 20 in the longitudinal direction of the upper mold 14, the second valve half 26 is non-rotatably attached to the upper mold 14. It is possible. Further, when the second valve half body 26 is set on the sprue 20, the split surface of the valve body 26 and the split surface of the upper die 14 are set to be flatly aligned.

Then, as shown in FIG. 2, when the lower mold 12 and the upper mold 14 are closed, the first valve half 24 and the second valve half 26 are correspondingly brought into close contact with each other, and Diaphragm 3
A split portion 42 (split surface portion) which is always in intimate contact with each other is formed on the joint surface between 0 and the second diaphragm 36. The first valve half 24 and the second
By setting the outer dimensions of the valve halves 26 to be slightly larger than the internal dimensions of the corresponding sprue 20, the check valves 28 formed by the two valve halves 24, 26 when the split mold 10 is closed. And a good seal between each sprue 20 is achieved. Further, as shown in FIGS. 2 to 4, the first valve half 24 set in the lower mold 12 and the second valve half set in the upper mold 14
In order to prevent the valve half body 26 from dropping outward in the axial direction, the arcuate plates 44 and 46 divided into two are fixed to the side surface of the mold with, for example, bolts 48. Therefore, when performing the closed injection, as shown in FIG.
The injection head 22 is pressed against the sprue 20 through the center through hole 6.

Further, the strength of the first diaphragm 30 and the second diaphragm 36 is such that when the pressure of the foam material injected from the injection head 22 is applied, the diaphragm itself has a check valve 28, as shown in FIG. When the injection of the foam material from the injection head 22 is stopped and the foam material is allowed to enter the runner 18, the split portion 42 is opened by deforming to the inner side of FIG. As shown in FIG. 5, the split portion 42 is set to a size such that the split portion 42 returns to its original shape by self-elasticity to be closed and is not opened by the foaming pressure generated from the injected foam material. That is, since the first valve half body 24 and the second valve half body 26 are made of an elastomer such as silicon, ethylene propylene rubber, ethylene propylene diene rubber as described above, they can be elastically deformed when a required stress is applied. In addition, when the stress is released, the original shape can be elastically restored. Of course, the injection pressure of the foam material from the injection head 22 is higher than the foam pressure generated from the injected foam material.

Next, FIGS. 5 to 11 show a second embodiment of the check valve according to the present invention. Regarding the basic structure, the first embodiment shown in FIGS. 1 to 4 is shown. Same as the example. However, in the second embodiment, a right-angled triangular reinforcing piece 50 is integrally formed upright in the internal flow path 24a of the first valve half 24, and the vertical side of the reinforcing piece 50 is the first side.
It is integrally connected to the back surface side of the diaphragm 30 (see FIGS. 5, 6 and 11). Similarly, the second valve half 26
Further, a right-angled triangular reinforcing piece 52 is integrally formed in the internal flow path 26a, and a vertical side of the reinforcing piece 52 is integrally connected to the back side of the second diaphragm 36.
These reinforcing pieces 50, 52 have a fear that the first diaphragm 30 and the second diaphragm 36 are deformed by the foaming pressure generated from the injected foam material to open the split portion 42 depending on the thickness and material thereof. , Is used as a reinforcement. That is, the reinforcing piece 5
0 and 52 are deformed together with the diaphragms 30 and 36 by the injection pressure of the foam material from the injection head 22 as shown in FIG. 8 and FIG. 9, but with respect to the foam pressure generated from the injected foam material. Against this, deformation of the diaphragms 30 and 36 is prevented. Therefore, the thickness or strength of the reinforcing pieces 50 and 52 is easily buckled and deformed by the injection pressure of the foam material, but the corresponding diaphragms 30 and 36 are not deformed by the foam pressure from the foam material and may be deformed. It is set to a specification that can prevent this.

[0014]

Operation of the Embodiment Next, the operation of the check valve according to the first embodiment and the second embodiment constructed as above will be described.
First, in the first embodiment, the upper mold 14 is opened with respect to the lower mold 12, a mold release agent is applied to the cavity 16, and the sprue 20 of each of the lower mold 12 and the upper mold 14 has a first valve half 24. And the second valve half 26 is correspondingly set detachably. When the upper mold 14 is closed with respect to the lower mold 12, the first valve half body 24 and the second valve half body 26 come into compressive contact with each sprue 20 to achieve a good seal. At this time, as shown in FIG. 2, the first valve half 24 and the second valve half 24
The valve half body 26 is correspondingly adhered to form a complete check valve 28, and the split portion 42 (in the closed state) formed on the joint surface between the first diaphragm 30 and the second diaphragm 36 is The sprue 20 is closed. In this state, the injection head 22 is pressed against the sprue 20 to start the injection of the foam material. At this time, the pressure of the foam material causes the first diaphragm 30 and the second diaphragm 36 to
However, as shown in FIG. 3, it deforms to the inside of the check valve 28 and opens the split portion 42. As a result, the foamed material enters the runner 18 through the internal flow paths 24a and 26a of the check valve 28 and is supplied to the cavity 16 as it is.

Immediately after the injection of the foam material by the injection head 22 is completed, the head 22 is immediately removed from the sprue 20. As a result, the pressure applied from the outside to the first diaphragm 30 and the second diaphragm 36 disappears,
The diaphragms 30 and 36 return to their original shape by self-elasticity. That is, the split portion 42 also returns to its original shape and closes again. At this time, the foaming material injected into the cavity 16 generates a foaming pressure as the foaming reaction proceeds, and this pressure acts to deform the first diaphragm 30 and the second diaphragm 36. However, as described above, since the strength of the first diaphragm 30 and the second diaphragm 36 is preset to a size that does not deform due to this foaming pressure, the split portion 42 will not open. Therefore, even if the foaming reaction in the cavity 16 progresses, the disadvantage that the foaming material flows backward due to the foaming pressure is completely prevented. When the required time has passed and the foam molding is completely completed, the upper mold 14 is opened with respect to the lower mold 12, and the molded product formed in the cavity 16 is taken out, thereby completing one foaming cycle.

The case of the second embodiment is basically the same as that of the first embodiment. However, in the second embodiment, when the injection head 22 is pressed against the sprue 20 and the injection of the foamed material is started, the injection pressure acts on the first diaphragm 30 and the second diaphragm 36. The reinforcing pieces 50 and 52 are also deformed as shown in FIG. 8 to open the split portion 42. And injection head 22
When the head 22 is removed from the sprue 20 after the injection of the foam material from the above is completed, both diaphragms 30 and 36 return to the original shape by the self-elasticity, and as shown in FIGS. Close. Then, the foaming pressure generated from the injected foam material is applied to the inner surfaces of both the diaphragms 30 and 36. At this time, since the reinforcing pieces 50 and 52 resist the foaming pressure, the both diaphragms 30 and 36 are directed outward. There is no deformation towards. Therefore, the split portion 42 is not opened, and the disadvantage that the foam material in the cavity 16 flows backward due to the foaming pressure is prevented.

[0017]

As described above, according to the check valve of the closed injection mold according to the present invention, the injection head is pressed against the sprue of the mold to inject the pressure, and immediately thereafter the injection head is detached. be able to. Therefore, the injection head can be moved to the next mold and the operation of injecting the foaming material therein can be sequentially performed, so that the cycle time is shortened and the production efficiency is increased. Further, since the structure is extremely simple, the check valve can be taken out when the upper die is opened with respect to the lower die, and cleaning and maintenance thereof can be performed very easily. Moreover, since the check valve of the present invention can be manufactured at a low cost by using an elastomer molded product, if the wear is caused by repeated use or the polyurethane is strongly adhered,
It is possible to replace with new parts in units of the valve half, and it is possible to keep running costs low. Further, there is an advantage that it is possible to surely prevent the backflow of the foamed material without having to rely on the uncertain insertion of the plug which has been carried out in the prior art.

[Brief description of drawings]

FIG. 1 is a perspective view of a closed injection mold in which a check valve according to a first embodiment of the present invention is preferably used, in which an upper mold opens upward with respect to a lower mold to expose a cavity. Shows the closed state.

FIG. 2 is a vertical cross-sectional view of a split mold that uses a check valve according to the first embodiment.

FIG. 3 is a plan view of a lower mold in a split mold that employs the check valve according to the first embodiment, in which the first and second diaphragms are deformed by the injection pressure of the foam material, and the material is reversed. It shows the state of flowing into the stop valve.

FIG. 4 is a plan view of a lower mold in a split mold that employs the check valve according to the first embodiment, which is the first mold depending on the foaming pressure
Also, the second diaphragm is not deformed.

FIG. 5 is a perspective view of a closed injection mold in which the check valve according to the second embodiment of the present invention is preferably used, in which the upper mold is opened upward with respect to the lower mold to expose the cavity. Shows the closed state.

FIG. 6 is a plan view of a lower mold in a split mold that uses a check valve according to a second embodiment.

7 is a vertical sectional view taken along line 7-7 of FIG.

FIG. 8 is a vertical cross-sectional view of the check valve according to the second embodiment,
The injection pressure of the foam material deforms the first and second diaphragms to show the material flowing into the check valve.

FIG. 9 is a perspective view showing a state in which both the first diaphragm and the reinforcing piece are deformed by the injection pressure of the foam material.

FIG. 10 is a vertical cross-sectional view of the check valve according to the second embodiment, showing a state in which the first and second diaphragms are not deformed by the foaming pressure.

FIG. 11 is a perspective view showing a state in which the first diaphragm and the reinforcing piece are not deformed even when a foaming pressure is applied.

[Explanation of symbols]

 10 split mold 12 lower mold 14 upper mold 16 cavity 18 runner 20 sprue 22 injection head 24 first valve half body 26 second valve half body 30 first diaphragm 32 fitting piece 34 fitting groove 36 second diaphragm 38 fitting Piece 40 Fitting groove 42 Split portion 50 Reinforcement piece 52 Reinforcement piece

Claims (3)

[Claims] 1. A sprue formed on a mold dividing surface by closing a lower mold (12) and an upper mold (14) which constitute the divided mold (10).
A closed injection gold, in which a foam material injection head (22) is brought into contact with (20), and the foam material is pressure injected into the cavity (16) through the sprue (20) and runner (18). In the mold, detachably set on the sprue (20) of the lower mold (12),
A first valve half (24) having a first diaphragm (30) for closing the sprue (20) facing the surface facing the outside of the mold.
And, it is detachably set on the sprue (20) of the upper mold (14),
A second valve half (26) having a second diaphragm (36) for closing the sprue (20) facing the surface facing the outside of the mold, the lower mold (12) and the upper mold. When closing (14), the first
The valve half body (24) and the second valve half body (26) correspondingly adhere to each other to form a split portion (42) on the joint surface between the first diaphragm (30) and the second diaphragm (36). The first diaphragm (30) and the second diaphragm (36)
Is deformed by the pressure of the foam material injected from the injection head (22) to open the split portion (42), thereby allowing the foam material to enter the runner (18), When the injection of the foam material from the injection head (22) is stopped, the split portion (42) returns to its original shape and closes, and the strength is set so that it does not open depending on the foaming pressure of the injected foam material. A check valve of a mold for closed injection characterized by being provided. 2. A diaphragm (30,36) in each of said valve halves (24,26) is connected to a reinforcing piece (50,52) formed inside said valve halves (24,26), The reinforcing pieces (50, 52) are deformed together with the diaphragm (30, 36) by the injection pressure of the foam material from the injection head (22) and resist the foam pressure generated from the injected foam material. A check valve for a closed injection mold according to claim 1, wherein deformation of the diaphragm (30, 36) is prevented. 3. The first valve half (24) has a mating piece on the back surface.
(32) is integrally formed, and the fitting piece (32) is fitted into the fitting groove (34) recessed in the lower mold (12) to rotate the first valve half (24). It can be fixedly attached to the lower mold (12), and the second valve half (26) also has a fitting piece (38) integrally formed on the back surface thereof. Fitting groove recessed in the upper mold (14)
The first valve half body (26) can be non-rotatably attached to the upper mold (14) by being fitted to the (40).
Alternatively, the check valve of the closed injection mold according to 2 above.