KR101972468B1 - Auto vent for foam molds - Google Patents

Abstract

The present invention discloses an auto vent for a foaming mold. The purpose of the present invention is to provide a vent which facilitates stable discharge of gas generated within the mold, removal of formed within the vent, and installation of the vent in the foaming mold. According to the present invention, the auto vent includes: a cylinder which is installed on an outer portion of the mold, has a pair of air hose coupling holes longitudinally formed in the side surface thereof, and has a first coupling unit formed in the bottom side thereof wherein a first moving hole is formed in the center of the first coupling unit, and a plurality of hemispherical position alignment grooves are formed at equal intervals in an outer circumferential surface of the first coupling unit; a piston of which one end side is positioned within the cylinder, and which is driven by a pneumatic pressure supplied to the cylinder; a gas discharge unit which is formed in the other end side of the piston, and includes a hemispherical rounded contact unit formed on an end portion of the piston and exposed to the inside of the foaming mold and a plurality of flutes processed to be round and formed to be extended to the contact unit along the longitudinal direction of the piston; and a piston guide which fixes the cylinder to the mold and guides driving of the piston at the same time by including a first coupling unit coupled to the first coupling unit and a third coupling unit formed to be extended from the second coupling unit, having a second moving hole which is formed in the center thereof and into which the piston can be inserted, and having a screw thread formed on an outer circumferential surface thereof to be installed and fixed to the foaming mold. Therefore, the auto vent performs removal of burr formed when a foaming solution flows into the flutes and is cured within the flutes by enabling the piston to be repeatedly driven instantaneously promptly through the cylinder after withdrawing a molded product from the foaming mold.

Description

[0001] The present invention relates to an auto vent for foam molds,

The present invention relates to a blowing mold vent, and more particularly, to a blowing mold vent which is capable of easily discharging gas generated in a mold during a foaming process to the outside and, at the same time, which can be easily removed from the mold.

In general, a foam molding product such as a cushioning material is produced by injecting a liquid foamed liquid into a mold having the shape of the product, foaming it, and injecting it.

However, a large amount of gas is generated in the process of injecting the foamed liquid into the mold or in the process of foaming, and the gas generated in the mold can not be discharged to the outside and exists inside the mold.

The gas present inside the mold generally induces an increase in the pressure inside the mold, so that the foaming in the mold can not be uniformly formed and the gas can not be formed in a uniform structure, or gas is concentrated at a specific position in the mold, The foaming is not carried out at a concentrated position, resulting in defective molding such as deforming the shape of the product.

Today, in order to minimize the defective molding rate by installing a vent in the mold to discharge the gas inside the mold, a foaming mold vent such as Korean Patent No. 10-0809867 (hereinafter referred to as "prior art") has been proposed.

In the conventional vent structure shown in FIG. 1, the piston moves according to the amount or pressure of the gas existing in the mold, the amount of gas is controlled and discharged, and the foamed liquid flows into the vent during the gas discharge process through the vent Thereby reducing the incidence of defects.

However, such a conventional vent has a problem that gas is discharged through the vent while the foaming liquid does not flow. However, as long as there is a space or gap through which gas can flow, It can be introduced into the space or the gap. In other words, the structure in which only the gas is discharged through the conventional vent structure and the foamed liquid does not flow is practically impossible, and the structure of the conventional vent also has a structure in which the foamed liquid must flow into the interior of the vent, .

Another problem with the conventional vent is that the internal pressure of the cylinder is reduced in accordance with the amount of gas that changes based on the degree of foaming of the foamed liquid to move the peristaltic portion to regulate the degree of gas discharge, There is a difficult problem in ease.

Specifically, the foam molds have various structures depending on the foam molding products, and even the foam molds having the same structure can be installed at different positions. 2, there may be a difference in gas discharge pressure exiting through each vent depending on the installation position of the vent, and a different time difference may be obtained until the gas discharge is completed. That is, when the vents X and Y are present in FIG. 2, there is a time difference until the exhaust of the gas through the vest of the minimum quantities is completed.

As shown in FIG. 3, a plurality of vents are formed on the foam mold based on the above-described contents. There is a problem that it is necessary to control the pressure for moving the peristaltic parts of the vents according to their installation positions. A pump, an air supply line, an intermittent valve, and the like, and when the foam mold is changed, there is a problem that the setting for pressure control must be repeated for each mold.

In addition, a conventional foam mold vent including a conventional vent structure has a structure in which an air hose for controlling the internal pressure of the cylinder is vertically coupled to the cylinder. When the vent is installed, the air hose is fixed to the mold by screwing. It is not easy to install the vent on the mold due to the interference with the ridge and when the position of the air hose coupling hole and the air hose face the ridge accurately by the screw coupling method, the vent itself can not be fixed firmly .

Further, as mentioned above, there is a bur in the known vent including the conventional vent. In order to remove such bur, there is a fundamental problem that the vent is periodically removed from the mold and then reinstalled after cleaning. There is a problem repeatedly caused by interferences between the air cleaner and the air cleaner.

DISCLOSURE Technical Problem The present invention has been devised to solve the above-mentioned various problems, and it is an object of the present invention to provide a method of manufacturing a foam molding machine capable of stably discharging gas generated in a mold, To provide a foaming mold vent.

According to the present invention, a pair of air hose fastening holes are formed in the longitudinal direction on the side surface, a first moving hole is formed in the center at the center, and a plurality of hemispherical alignment grooves are formed at equal intervals on the outer peripheral surface. A cylinder in which a fastening part is formed; A piston whose one end is located inside the cylinder and is driven by a pneumatic pressure supplied to the cylinder; A round-shaped contact portion formed at the other end of the piston and formed in the end portion of the piston and exposed to the inside of the foaming mold, a plurality of flutes, rounded and extended to the contact portion along the longitudinal direction of the piston, a gas discharge portion in which flutes are formed; And a second moving hole extending from the second fastening portion and capable of receiving the piston at a center thereof. The outer peripheral surface of the second moving hole is threaded to be fixed to the foaming mold. A piston guide formed as a third fastening portion to fix the cylinder to the mold and to guide driving of the piston; , And after the molded product is taken out from the foaming mold, the piston is instantaneously repetitively driven instantaneously through the cylinder so that the burr generated by flowing the foamed liquid into the flute and hardening is removed May be provided for the foam mold.

Since the automatic vent according to the present invention can automatically remove burrs flowing into the vent, the number of times of stopping the molding process, removing the vent and reinstalling the burr for removing burrs can be minimized, Based on the increase in process utilization rate, overall product productivity can be increased.

In addition, since the overall operation for gas discharge and burr removal through the air vent is performed only by supply of air without separate precise sensing and control, it does not consider the precise and expensive configuration (equipment) for sensing and control, And has superior merits in versatility and applicability in process and industry.

In addition, when installing the auto vent mold, the direction of the air hose coupling hole and the direction of the air hose can be easily set and fixed, which makes it possible to install the vent without regard to the type of the mold. There is an advantage that it can be re-installed in the installed form or direction.

In addition, when the one-touch quick coupling is applied, separation and recombination of the air hose are not required at the time of installation and separation of the vent, and there is an advantage that it is quick and easy.

Furthermore, it is easy to drive and manage a plurality of vents in a situation where several to dozens of vents can be formed in the blowing mold, and even when a point where the gas is required to be locally discharged from the existing mold is generated, There is an easy advantage.

1 is a view showing a conventional vent mold for a foamed mold.
Fig. 2 is a view for explaining a difference according to the installation position of the vent in the foam metal mold.
3 is a photograph showing a state where a vent is installed in a conventional foam mold having a ridge.
4 is a view showing an Auto Vent for a foamed mold according to the present invention.
5 is a cross-sectional view of Fig.
6 is an exploded perspective view of an auto vent for a foamed mold according to the present invention.
7A to 7C are views for explaining the gas and burr removal process by the Auto Vent for a foamed mold according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following detailed description of the operation principle of the preferred embodiment of the present invention, if it is determined that a detailed description of known functions or configurations related to the related art may unnecessarily obscure the gist of the present invention, do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the specification, and for the convenience of explanation, some of the drawings are exaggerated.

4 is a view showing an Auto Vent for a foamed mold according to the present invention. 5 is a cross-sectional view of Fig. 6 is an exploded perspective view of an auto vent for a foamed mold according to the present invention.

4 to 6, a plurality of Auto Vent for foaming mold according to the present invention (hereinafter, abbreviated as "Auto Vent") according to the present invention is installed in an upper mold of a foaming mold to discharge a gas generated in a mold during a foaming process. do. Such an auto vent may be formed in various positions depending on the type of the mold according to the foam molding product, and may be installed in different positions even though the same mold is used.

The auto vent according to the present invention comprises a cylinder 10, a piston 20, and a piston guide 30.

First, the cylinder 10 is a cylindrical member provided outside the metal mold. A pair of air hose fastening holes 11, 12 are formed on the upper and lower sides in the same line along the longitudinal direction. An air hose (not shown) is fastened to the fastening holes 11 and 12, respectively, so that air can be supplied into or discharged from the cylinder 10.

A first coupling part 13 formed integrally with the piston guide 30 is formed at a lower side of the cylinder 10 so as to have a diameter smaller than the diameter of the cylinder and is integrally formed with the center of the first coupling part 13 A piston first moving hole 14 which can be fastened so that the piston can move is formed, and hemispherical alignment grooves 15 are formed at equal intervals on the side surface. The first moving hole 14 is further provided with a sealing ring 16 so that the piston 20 can be moved and the inside of the cylinder is sealed.

The piston 20 is connected to the cylinder 10 and driven in a manner that it is drawn into and drawn out of the cylinder 10 according to the pressure forming state inside the cylinder 10. The piston 20 is generally formed in a cylindrical shape. A moving plate 21 is formed at one end positioned inside the cylinder 10 and a gas discharging unit 22 may be formed at the other end positioned outside the cylinder 10.

Specifically, the moving plate 21 formed at one end of the cylinder 10 is formed in a circular plate shape so as to be able to move in close contact with the inner wall of the cylinder 10, and is provided between the pair of air hose fastening holes 11 and 12 . Accordingly, the piston 20 is moved in the up / down direction inside the cylinder 10 by the pair of air hoses connected to the cylinder 10 according to the pressure forming state of the upper and lower sides with respect to the moving plate 21, So as to be drawn in and drawn out from the cylinder (10). Of course, the moving distance of the moving plate 21 is limited by the distance between which the pair of air hose fastening holes 11 and 12 are formed.

The gas discharge portion 22 is formed to have a predetermined length at the other end of the piston 20 so as to facilitate discharge of the gas present in the mold 20. The gas discharge portion 22 is formed in a hemispherical shape at the lower end A rounded contact portion 22a is machined, and a plurality of flutes 22b are formed on the outer circumferential surface.

The contact portion 22a guides the flow of the gas and the foamed liquid so that the discharge through the flute 22b is performed, and at the same time facilitates the separation from the foamed molded product S. That is, the contact portion 22a, which is the end of the piston 20, is located inside the mold and is directly brought into contact with the gas generated by the foaming of the foaming liquid and moved downward from the upward direction. At this time, if the contact portion 22a is formed flat without being rounded, the gas moving in the downward direction and the contact portion collide with each other when the pressure is high, So that gas movement and discharge of the flute passage 22b can not be performed smoothly. In addition, some surplus foamed liquid must flow naturally through the flute 22b due to foaming, but the surplus foaming liquid flowing into the flute 22b can not flow into the flute 22b smoothly, The contact points of the contact surface become uncluttered. In addition, since the contact portion is formed in a planar contact with the foamed molded product S, when the foamed molded product S is pulled out from the mold, separation from the contact portion is not uniformly performed at the position where the contact portion is located, There is a problem that additional remaining portion removing processing or defective molding occurs due to the fact that the surplus foamed liquid remains in a protruding form at the point.

However, since the contact portion 22a according to the present invention is rounded in a hemispherical shape, the gas and surplus foamed liquid naturally move along the rounded outer surface of the contact portion 22a, The liquid naturally flows into the flute 22b formed around the contact portion 22a. Therefore, even when the gas is rapidly generated and the foaming takes place rapidly rapidly during the foaming process, the discharge and flow of the gas and the excess foaming liquid into the flute 22b can be smoothly performed.

In addition, when the foam molded product S and the contact portion 22a are separated from each other, the contact portion 22a is formed in a hemispherical shape, so that the foam molded product S can be separated from the foam molded product S uniformly and smoothly. The remaining part protruding from the surface of the molded product S is not formed due to the contact with the molded product S from the surface of the foamed molded product S, The incidence rate can also be reduced.

 The plurality of flutes 22b are formed for smooth gas discharge and extend to the contact portions 22a and roundly drawn from the outer surface of the piston 20. Each of the flutes 22b has a predetermined angle As shown in FIG. 4 and 6, each flute 22b is formed on the outer surface of the other end of the piston 20, and the front ends thereof are formed at equal intervals along the rim of the contact portion 22a, 22b are positioned at the same position as the positions of the front ends of the adjacent other flutes, so that all the flutes 22b are equally twisted. These twisted flutes 22b have a distinct structure and difference from the thread-like structure formed on a drill bit or a screw or the like.

Each flute 22b is formed so that its depth tends to decrease so as to minimize the outflow of the foamed liquid flowing into the flute 22b through the flute 22b from the front end to the rear end. More specifically, the foamed liquid flowing in and flowing through the flute 22b flows out to the rear end side of the flute 22b, which is the rear side of the gas discharge portion 22, and is cured to thereby block the flute rear end, So that smoothness can not be achieved. Therefore, there is a need to continuously remove the cured foamed liquid after flowing out to the rear end side of the flute 22b. To this end, it is troublesome for the operator to perform the process after the entire process is stopped and the vent is manually removed from the mold .

Thus, by forming the rear end depth of the flute 22b smaller than the front end, the surplus foamed liquid through the shear end does not greatly change the inflow, while the flow out amount of the foamed liquid through the rear end side of the flute 22b is minimized, 22b to maximally delay the removal cycle of the cured foamed liquid. Therefore, the number of times of stopping the manufacturing process, removing the vent, etc. for removing the cured foamed liquid may be minimized, or may be unnecessary at all, resulting in an increase in the overall productivity of the product based on the increase in the operation efficiency and the process operation rate .

In addition, the depth of the flute 22b for the above-described contents may preferably be formed within a range of 0.12 to 0.15 mm in the front end and 0.1 to 0.05 mm in the rear end, which is shallower than the front end. At this time, when the depth of the flute 22b is 0.12 mm or less, the inflow of gas is not smooth. If the flute 22b is 0.15 mm or more, a large amount of gas flows instantaneously quickly and the pressure in the mold is reduced to be below the reference value. It is not possible to form a tissue state conforming to the good quality standard of the molded product S, and so on. In the case of the depth of the rear end, when the depth is not less than 0.1 mm, the difference between the depth and the shear depth is small, and the outflow of the gas and the foamed liquid through the flute 22b is drastically reduced Lt; / RTI >

Meanwhile, the piston 20 of the auto vent according to the present invention may be further formed with a growth preventing groove 23 for preventing the growth of the foamed liquid flowing out through the rear end of the flute 22b. At this time, the growth preventing groove 23 has a shape in which a point on the rear end side of the flute 22b is machined along the outer circumferential surface of the piston 20 so as to have a smaller diameter than the diameter of the piston 20, The foamed liquid flowing out through the cylinder 10 can not grow in the direction of the upward cylinder 10 and at the same time it forms a droplet shape in the growth preventing grooves 23 to stably drive the piston 20 along the cylinder 10, It is possible to facilitate the removal of the cured foamed liquid.

The piston guide 30 serves to secure the linear movement of the piston 20 and to fix the vent to the mold. The piston guide 30 is largely divided into a second fastening portion 31 and a third fastening portion 32 .

First, the second fastening portion 31 is for fastening the piston guide to the cylinder, and can have a one-touch quick coupling structure. At this time, the one-touch type quick coupling includes a body for connecting pipes such as a tube and a hose, a plurality of balls provided in the body, and a ball formed of a sleeve movable around the ball. Since this is a lock quick coupling, which is widely used today, a detailed detailed description will be omitted.

On the other hand, the one-touch type quick coupling is generally composed of a pair of female / male. In the case of the present invention, the first fastening portion 13 is a male coupling and the second fastening portion 31 is an arm coupling . However, the first and second fastening portions 13 and 31 of the present invention may be arranged such that when the balls 31a of the second fastening portions 31 are aligned with the first fastening portions 13 Since the air hose fastening holes 11 and 12 formed in the cylinder 10 can be set and fixed in the direction setting state by selectively positioning and being fixed to the groove 15 There is a difference. Therefore, the auto vent according to the present invention can be installed at a position where interference with the ridge of the mold, which may occur in the direction of the air hose fastening holes 11 and 12, It is easy to install the vent considering the position where the air hose is easily integrated or the position of the air hose which does not interfere with the operation and the operation of the operator. Furthermore, when the installed vent is removed and reinstalled, stable reinstallation can always be possible in the initial (set) state (direction).

Meanwhile, the second connection part 31 may be provided with a gas discharge hole 31b for discharging the gas flowing into the auto vent through the gas discharge part 22 to the outside. The gas discharge hole 31b is formed in a side surface of the second fastening part 31 and is formed at a position and a size such that the rear end of the flute 22b and the growth preventing groove 23 are exposed. The gas discharge holes 31b allow the gas flowing into the vent to be discharged to the outside of the vent and flow out through the rear end of the flute 22b to facilitate removal of the foamed liquid hardened in the growth preventing groove 23 . That is, the vent can be removed from the mold, that is, the cylinder 10 can be removed through the gas discharge hole 31b without removing the cylinder 10 from the cylinder guide 30 when the foamed liquid solidified in the growth preventing groove 23 is removed. have.

The third fastening portion 32 is provided to fix the piston guide 30 to the metal mold. The outer circumferential surface of the third fastening portion 32 is threaded to be engageable with a fixing hole formed in the metal mold. 2 moving hole 32a is operated. At this time, the second moving hole 32a is formed to have a diameter enough to allow movement of the piston, and unlike the first moving hole 14, a sealing ring is not formed therein.

Hereinafter, the process of discharging the gas of the foamed mold using the Auto Vent according to the present invention will be described based on the above description.

7A to 7C are views for explaining the gas and burr removal process by the Auto Vent for a foamed mold according to the present invention.

7A, an auto vent is installed at a position where gas is required to be discharged from the foam metal mold 1. The piston 20 is connected to the lower air hose fastening hole The lower reference pressure of the moving plate 21 of the piston 20 is increased by the air hose connected to the piston 12 relatively to the upper side. The gas discharge portion 22 of the piston 20 is located inside the piston guide 30 and only the contact portion 22a is exposed by being protruded from the piston guide 30.

In this state, when the foaming in the mold 1 is performed, the gas is produced and discharged (A), and when the foaming liquid B is increased and at the same time the foaming is completed, The foamed liquid B flows into the openings 22b and the foamed liquid B flowing into the flutes 22b is cured to exist as burrs. At this time, when the gas pressure in the mold 1 is high or the amount of the foamed liquid B supplied is large, the foamed liquid B is prevented from being accumulated in the growth preventing groove 23 in the form of droplets It is cured and is present.

After completion of the foaming in the mold 1, the operator removes the foam molded product S from the mold 1 as shown in Fig. 7B, and then removes the burr T existing in the flute 22b The auto vent is driven as shown in Fig. 7C. At this time, the driving of the auto vent causes high-pressure air to be alternately repeatedly supplied through the air hose connected to the upper side and the lower side of the cylinder 10 so that the piston 20 can be reciprocated quickly and effectively for a short time .

Thus, the burr T in which the foamed liquid B has hardened in the flute 22b is removed and removed from the flute 22b during the impact reciprocating movement of the piston 20, and falls into the mold 1 , And the burr (T) dropped into the mold (1) is included in the foamed liquid (B) to be supplied for molding the next product. On the other hand, even when the hardened foamed liquid B is present in the growth preventing groove 23, as the growth preventing groove 23 is moved to the inside of the groove of the piston guide 30, the piston 20 reciprocates The second moving hole 32a collides with the inner bottom surface of the second fastening portion 31 to be separated and removed from the growth preventing groove 23 and the removed cured foamed liquid B is discharged through the gas discharge hole 31b. At this time, the cured foamed liquid B which is collided with the inner bottom surface of the second fastening part 31 and separated from the growth preventing groove 23 may temporarily exist in the inner bottom surface of the second fastening part 31, And the gas is discharged through the gas discharge hole 31b by the driving of the repeated auto vent.

In connection with the drive of the auto vent, the drive of the auto vent is generated by blowing the foamed liquid (B), that is, the foamed liquid (B) into the flute (22b) Is driven to remove the burr (T).

At this time, the structure of the flute 22b is a structure that is twisted at a predetermined angle as described above, so that the burr T can be removed. For example, when the shape of the flute 22b is formed in a straight line, there is a problem that the amount of inflow of the foamed liquid B into the auto vent is significantly increased, and the burr T existing along the flute 22b And is fixed to the inner wall of the second moving hole 32a. Thus, even if the piston 20 is operated quickly and impacted by driving the auto vent to remove the burr T, the burr T hardened in the flute 22b only moves back and forth by the piston 20, So that it is in a state of being fixed to the inner wall of the moving hole 32a, so that the burr T of the flute can not be removed.

On the other hand, when the shape of the flute 22b is formed in the spiral shape formed on the conventional technique or the conventional screw, when the air vent is driven to remove the burr T, the burr T existing in the flute 22b, There is no problem caused by the fixing of the moving hole 32a to the inner wall. However, even if the burr T existing in the flute 22b is not detached from the flute 22b but remains in the flute 22b, that is, even if it is not fixed to the flute 22b, Problems arise.

Therefore, as described in the present invention, the flute 22b is formed so as to be twisted so as to be in line with the front end adjacent to the rear end, which is not a straight line or a spiral, so that the burr T existing in the flute 22b and the second moving hole 32a The burr T can be separated and removed from the flute 22b by driving of the air vent without a problem of sticking to the inner wall of the flute 22b and not leaving the flute 22b.

If the burrs T are sequentially removed by the mold 1, the product separation, and the drive of the auto vent, the mold 1 may be set to the initial state and then the foam molding may be repeated.

As described above, the automatic vent for a foamed mold according to the present invention can automatically remove burrs flowing into a vent, and therefore, the number of times of stopping the molding process, removing the vent, and reinstalling May be minimized, or may be unnecessary at all, so that the overall productivity of the product can be increased based on the increase of the operation efficiency and the process operation rate.

In addition, since the overall operation for gas discharge and burr removal through the air vent is performed only by supply of air without separate precise sensing and control, it does not consider the precise and expensive configuration (equipment) for sensing and control, And has superior merits in versatility and applicability in process and industry.

In addition, since the direction of the air hose coupling hole, that is, the direction of the air hose, can be easily set and fixed at the time of installing the mold of the auto vent, there is an advantage that it can be installed without being dependent on the kind of the mold, There is an advantage that it can be re-installed in the form that was first installed even after re-installation.

In addition, in order to install and separate the vent from the mold in the conventional screw type, it is necessary to separate the air hoses from the cylinder to prevent the air hoses from being twisted. However, in the case of the auto vent according to the present invention, Type quick coupling, it is not necessary to separate and recombine the air hose, and there is a quick and simple advantage.

Furthermore, it is easy to drive and manage a plurality of vents installed in a situation where the vent can be formed in a foaming mold by several to several tens (see FIG. 3), and even when a point where a discharge of a local gas is required in the existing mold occurs And the installation and application of the vent is easy.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. The present invention is not limited to the drawings, and all or some of the embodiments may be selectively combined so that various modifications may be made.

Claims (5)

A pair of air hose fastening holes are formed in the side surface of the mold, and a first fastening portion having a first moving hole at the center and a plurality of hemispherical alignment grooves formed at equal intervals at the center is formed on the bottom surface side cylinder;
A piston disposed inside the cylinder at one end and being capable of being driven into the cylinder by a pneumatic pressure supplied to the cylinder;
A semi-spherical rounded contact portion formed at an end of the piston, the rounded contact portion being formed at the other end side of the piston and exposed to the inside of the foaming mold, and a contact portion along the length direction of the piston, A gas discharge portion in which a plurality of flutes extending from the gas discharge portion are formed; And
A piston guide formed in a ball-locking quick-coupling structure and having a second fastening portion connected to the first fastening portion in a detachable manner to guide the driving of the piston while fixing the cylinder to the mold; Lt; / RTI >
The plurality of flutes are formed so that the front ends of the respective flutes are arranged at equal intervals along the rim of the contact portion and the rear end is positioned at a position where the positions of the front ends of the adjacent other flutes are aligned with the longitudinal direction of the piston Is generally formed in a twisted structure at a predetermined angle in the circumferential direction,
Wherein the piston is rapidly and instantaneously and rapidly repetitively driven to remove a bur existing in the flute after the molded product is taken out from the foam mold. The method according to claim 1,
Wherein a growth preventing groove is formed at a rear end point of the gas discharging portion so as to communicate with a rear end of the flute and to have a diameter smaller than a diameter of the piston, the grooves being formed along the outer circumferential surface of the piston. The method according to claim 1,
The piston guide
And a third fastening part formed on the outer circumferential surface of the second fastening part and having a screw thread for fastening to the foaming mold. The method of claim 3,
Wherein the depth of each of the flutes decreases from the front end side to the rear end side. The method of claim 2,
Wherein the second fastening portion is formed with a gas discharge hole for discharging the gas flowing through the gas discharging portion and the foaming liquid cured in the growth preventing groove.

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