JP2003117967A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding provided with an air ejection demolding mechanism for controlling the deformation of a molding. SOLUTION: A truncated cane-shaped recessed part 15 is formed in the cavity 6 of the mold, and an air ejection hole 16 is formed in the bottom part of the recessed part. Air ejected from the air ejection hole flows from the circular part of a conical apex part along an inclined surface and is expanded radially between the molding 16 and the cavity 6 to demold the molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die, and more particularly to an improvement of an injection molding die having a mechanism for releasing a molded body by jetting air.

[0002]

2. Description of the Related Art Conventionally, as a structure for automatically releasing a molded body in an injection molding die, there has been known a structure utilizing jetting of air. For example, Japanese Unexamined Patent Publication No. 5-245880 discloses a structure shown in FIGS. In the drawing, reference numeral 1 is a first mold, 2 is a central valve that moves in the left-right direction, and 3 is an inflow hole for allowing air to flow into a cavity (a space on the right side of the first mold in the drawing). (A) of the figure shows the state when the resin is filled into the mold 1, and (b) of the figure shows the state when the molded body is released from the mold 1 after molding. At the time of resin filling, as shown in FIG.
The inflow hole 3 is closed by the central valve 3, while at the time of mold release, the central valve 2 is retracted in the direction of arrow a as shown in (b) of the figure, and air is ejected from the inflow hole 3 into the cavity (arrow b). ), The mold is released. It is described that such a method of extruding a molded body with air has an advantage of not causing scratches, because a protrusion pin or the like is not brought into direct contact with the molded body.

[0003]

In such an air ejecting and releasing structure, particularly in the case where the molded body is formed of a soft elastic material such as a thermoplastic elastomer resin, a portion directly contacted with the ejected air. Deformation such as dents may occur.

The present invention has been made in view of the above problems, and provides an injection molding die provided with an air jetting and releasing mechanism which hardly deforms.

[0005]

The present invention (Claim 1) includes:
An injection-molding die having a cavity into which heat-melted resin is injected and provided with an air ejection hole for ejecting air for releasing a molded body at a portion facing the cavity, A frustoconical recess is formed, and the air ejection hole is formed at the bottom of the recess. With this configuration, when the molded body is released from the mold, the air ejected from the air ejection holes flows into the cavity along the inclined surface of the frustoconical projection formed on the molded body. The flow becomes smooth and no large pressure is locally applied to the molded body.

According to the present invention (claim 2), the injection molding die comprises a fixed die, a movable die, and a slide die which is opened in association with opening movement of the movable die. The recess is formed in a portion facing the cavity, and an opening / closing valve that opens / closes the air ejection hole formed in the movable mold is formed in the slide mold.
In such a structure, when the movable die is opened, the slide die is opened in conjunction with this. As a result, the on-off valve of the air ejection hole is opened, air is ejected between the cavity surface and the molded body, and the molded body is released.

According to the present invention (claim 3), the slide die is slidably attached to the movable die, and an angular pin provided on the fixed die is used to move the movable die when the die is opened. It is interlocked and slides in the direction of the central axis of the movable die to open the air ejection hole. In such a structure, when the mold is opened, the molded body adhered to the movable mold is released from the air blown onto the movable mold adhered surface.

According to the present invention (claim 4), when the on-off valve is opened, the air ejected from the air ejection hole is prevented from flowing into the space where the slide die slides in the movable die. A sealing material is attached between the movable die and the slide die. In this structure, the slide valve slides in the direction of the movable central axis, the on-off valve is opened, and air is ejected from the air ejection hole. At this time, air leaks from the gap between the contact surfaces of the slide mold and the movable mold, and even if the air tries to flow into the space where the slide mold slides in the movable mold, it is prevented by the sealing material.

[0009]

1 to 4, reference numeral 4 is a fixed die, 5 is a movable die which moves downward with respect to the fixed die 4, and 6
Is a cavity formed between the molds 4 and 5, and the resin material heated and melted is injected and injected from the runner 7 formed between the fixed mold 4 and the movable mold 5. Reference numeral 8 is a slide type attached to the movable die 5 and is slidable laterally (left-right direction in the drawing). Reference numeral 9 is a space provided between the movable die 5 and the slide die 9, and is a slide die 8
Slides in this space 9. Reference numeral 10 is a seal material attached to the upper end of the space 9 on the movable die 5 side. Since the slide die 8 must be slidable with respect to the movable die 5, a slight gap is formed between the upper end surface S of the slide die 8 and the inner surface of the movable die 5 opposite to the upper end surface S. Space 11 of time slide type 8
The air flowing into (FIG. 3) is leaked into the slide space 9 through this gap. The sealing material 10 closes this gap when the slide die 8 slides, and acts to prevent air leakage. Note that FIG. 3A is an enlarged cross-sectional view of the main part X of FIG. 2, and is a partially enlarged cross-sectional view of FIG. 3A.

Reference numeral 12 is an angular pin attached to the fixed die 4, which passes through the through hole 13 of the slide die 8 and enters the concave hole 14 of the movable die 5 to form the three dies 4, 5, 5.
8 has a function of positioning and sliding the slide mold 8 in the mold central axis P direction when the mold is opened. The fixed mold 4, the movable mold 5, and the slide mold 8 constitute an injection molding die, which are attached to an injection molding machine (not shown). Note that these molds are two-cavity molds and are configured symmetrically about the center axis P of the mold. Only the right half is shown in the figure.

Reference numeral 15 is a cavity 6 of the movable mold 5.
Corresponding to the concave portion 15 on one surface of the molded body 16 (the surface in contact with the cavity surface of the movable die 5) as shown in FIG. A plurality of raised protrusions 17 are formed. 18 is this recess 1
5 is an air ejection hole formed in the bottom portion (the truncated surface of the truncated cone), which is also formed in an elongated truncated cone shape. That is, two truncated cone-shaped spaces are formed so that their truncated surfaces abut each other.

A plurality of recesses 15 are formed dispersedly on the surface of the molded body 16 so that when the molded body 16 is released from the mold, the operation of the molded body 16 can be performed smoothly. The number of recesses 15 is set according to the size or shape of the molded body 16 itself. That is, if the molded body 16 is small or has a shape that allows easy mold release, a sufficient release force can be obtained with one recess 15, but if the area of the molded body 16 adhered to the mold 5 is large, or When the shape is complicated, such as having an undercut, by appropriately disposing a plurality of recesses 15,
It is possible to release the mold without increasing the pressure of the air A ejected from each recess 15 so much. Recess 15
By increasing the number of, it is possible to reduce the air jet output from each recess 15 and suppress the deformation. In the example shown in FIG. 4, the molded body 16 has a structure in which it is uniformly distributed.

Reference numeral 19 denotes a metal on-off valve that conforms to the shape of the air ejection hole 18, and can be integrally formed as a part of the slide die 8. Reference numeral 20 is an air supply hole for sending the air A to the space 11 (FIG. 3A) in which a plurality of these on-off valves 19 are formed. High pressure air is constantly supplied to the air supply hole 20 from an air compressor (not shown). Slide type 8
The sliding movement causes the on-off valve 19 to close (FIG. 1) or open (FIG. 2) the air ejection hole 18.

Next, a molding method using the above molding die will be described. As shown in FIG. 1, in a state where the respective molds 4, 5 and 8 are clamped, the molten resin is injected and injected into the cavity 6 through the runner 7 from the nozzle (not shown) of the injection molding machine. . At this time, the slide die 8 is moving in the direction away from the central axis P (right side in the figure), and the opening / closing valve 19 is in a state in which the air ejection hole 18 is closed.

After molding, the movable die 5 moves downward as shown in FIG. At this time, the molded body 16 is in a state of being adhered to the movable mold 5 because the surface of the fixed mold 4 side is smooth and the plurality of convex portions 17 are present on the surface of the movable mold 5 side. Angular pin 12 as the movable die 5 moves
Causes the slide die 8 to slide in the central axis P direction (left side in the drawing), the opening / closing valve 19 retracts in the central axis P direction, the air ejection hole 18 opens, and the convex portion of the molded body 16 is indicated by the arrow A. Air is radially ejected into the cavity through the inclined surface. As a result, the molded body is stripped from the surface of the movable mold and released. At this time, the air A smoothly flows from the inclined surface of the convex portion 17 toward the surface of the molded body 16,
The air A does not hit strongly locally, and the deformation of the air A due to the pressure is suppressed. The size and height of the convex portion 17 and the angle of the inclined surface can be changed according to the size of the air jet output.

The molded body 16 can be, for example, an elastic sheet material used as an automobile part. A thermoplastic elastomer resin such as a polyolefin-based thermoplastic elastomer or a polyurethane-based thermoplastic elastomer is often used as a material for the elastic sheet material for automobile parts. The formation of the convex portion is not always necessary depending on the use of the molded body such as the elastic sheet material, but when the sheet is in full contact with the surfaces of the other parts and the two are in sliding contact,
The contact at the convex portion can fulfill the function of suppressing the contact resistance and the like, which is suitable as, for example, a covering sheet material for a seat rotating portion of an automobile. In the above example, the case where the molded body is an elastomer resin material has been described,
It can also be applied to molding of a general resin having no elasticity.

[0017]

According to the present invention (Claim 1), the air ejected from the air ejection holes at the time of release is radiated from the truncated circular portion of the convex portion of the truncated cone shape along the slope of the cone. Since the air flows smoothly, it is possible to avoid the phenomenon that the air hits the compact as if it collides with the compact, and the deformation of the compact due to the pressure of the jet air is minimized.

According to the present invention (Claim 2), when the mold is opened by the movement of the movable mold, the slide mold slides sideways in association with the movable mold to open the air ejection hole, and the high pressure air is moved. It is ejected between the molded body adhered to the substrate and the adhered surface of the movable mold cavity, and the molded body is automatically released immediately after the mold is opened.

According to the present invention (Claim 3), when the movable die moves, the slide die slides by the angular pin attached to the fixed die, and the on-off valve is retracted and opened like retracting into the movable die. As a result, air is ejected and the molded body is released. At this time, since the on-off valve does not come into contact with the molded body, there is no possibility that it will damage the molded body. In addition, the air jet is inside the movable mold (the central axis side of the movable mold).
From the above, the molded body released from the mold is discharged into the open outer space, falls, and is accumulated at a predetermined position.

According to the present invention (Claim 4), air does not leak into the slide space due to the presence of the sealing material.
All the high-pressure air will be ejected to the cavity, and the decrease in air pressure due to air leakage and the accompanying decrease in release pressure can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an injection molding die (closed state) according to an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of an injection molding die (opened state) according to the embodiment of the present invention.

3 (a) is an enlarged cross-sectional view of a main part of FIG. 2, and FIG. 3 (b) is a partially enlarged cross-sectional view of FIG. 3 (a).

FIG. 4 is a perspective view showing a molded body.

FIG. 5 is a cross-sectional view for explaining a conventional example.

[Explanation of symbols]

4 fixed type 5 movable 6 cavities 7 sprue 8 slide type 9 slide space 10 Seal material 11 space 12 Angular Pin 13 through holes 14 recess 15 recess 16 molded products 17 convex 18 Air ejection holes 19 open / close valve 20 Air supply hole

Claims (4)

[Claims] 1. An injection-molding die having a cavity into which heat-melted resin is injected and provided with an air ejection hole for ejecting air for releasing a molding from a portion facing the cavity. 2. An injection molding die according to claim 1, wherein a recess having a frustoconical shape is formed in the cavity, and the air ejection hole is formed in the bottom of the recess. 2. The injection molding die includes a fixed die, a movable die, and a slide die that opens in association with the opening movement of the movable die, and the injection die is provided at a portion facing the cavity of the movable die. The injection molding die according to claim 1, wherein a recess is formed and an opening / closing valve that opens and closes the air ejection hole formed in the movable mold is formed in the slide mold. 3. The center of the movable die is linked to the movement of the movable die when the die is opened by an angular pin provided on the fixed die slidably attached to the movable die. The injection molding die according to claim 2, wherein the air ejection hole is opened by sliding in the axial direction. 4. A seal member for preventing the air ejected from the air ejection holes from flowing into the space in which the slide die slides in the movable die when the on-off valve is opened, when The injection molding die according to claim 3, wherein the die is mounted between the slide dies.