JPH10660A - Undercut extracting mechanism for injection molding mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce mold thickness, to improve durability, to leave no pressing trace on the surface of an insert, and to enable the use without the insert by reciprocating a center block in the opening/closing direction of a mold having sliding vertical surfaces and sliding inclined surfaces. SOLUTION: A center block 300 has corresponding sliding vertical surfaces 301a, 301b which slide with the sliding vertical surfaces 312a, 312b of the first side blocks 310a, 310b and corresponding sliding inclined surfaces 302a, 302b narrowed downward which slide with the sliding inclined surfaces 322a, 322b of the second side blocks 320a, 320b and is reciprocated by a prescribed position in the opening/closing direction of a mold by an ejector mechanism, a spring, etc., together with the opening/closing direction of the mold. An undercut extracting mechanism 10 for an injection molding mold can extract an undercut of the whole circumferential direction, can reduce mold thickness not to need a large molding machine, and does not leave no pressing trace on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an undercut removal mechanism for an injection mold capable of removing an undercut in all circumferential directions.

[0002]

2. Description of the Related Art Conventionally, as a structure for removing an undercut in an entire circumferential direction of an injection mold, a "collapsible core" in which an outer diameter of a core portion is contracted by using opening and closing operations of the mold is known. . This collapsible core is provided with a segment portion so as to be automatically narrowed on the outer periphery of the core. By inserting a center pin outside the core, the segment portion is expanded to a required shape and dimensions. .

Further, Japanese Patent Application No. 8-3464 discloses a first side split block which has an undercut portion at the top and which opens and closes in the left and right direction, and a phase split block having an undercut portion at the top. A second side split block that opens and closes in a corresponding fore-and-aft direction, and an undercut removal mechanism including a center block, wherein a lower opening outer inclined surface of the second side split block that moves up and down, An undercut for an injection mold in which the first side split block opens and closes and the second side split block that moves up and down is opened and closed in the front-rear direction by an upper open outer inclined surface of the center block at a fixed position. An extraction mechanism is described.

[0004]

However, since the above-mentioned collapsible core has an inevitably long overall length, the thickness of the mold is large, a large molding machine is inevitably required, and the cost of manufacturing the mold is high. In addition, when the segment portion that automatically shrinks has poor durability or is damaged, it is difficult to repair only the segment portion, and it has been necessary to replace the entire collapsible core.

[0005] Further, the undercut removal mechanism described in Japanese Patent Application No. 8-3464 is a system in which an insert product is held by a center block, and cannot be used when there is no insert product. In some cases, the center block retainer marks were left on the surface of the insert.

The present invention has solved the above-mentioned problem of the conventional undercut removal mechanism, and can reduce the thickness of the mold.
An object of the present invention is to provide an undercut removal mechanism for an injection mold in all circumferential directions which has high durability, does not form a pressing mark on the surface of an insert product, and can be used without an insert product.

[0007]

According to the present invention, FIG.
As shown in (b) and (c), two corresponding halves having an undercut portion (110a and 110b) at the upper side and a contact inclined surface (120a and 120b) extending downward at the center portion, First side plate (100a and 100b) that opens and closes in a direction perpendicular to the mold opening and closing direction
And an undercut portion (210a and 210b) upward
A second side plate (200a and 200b) having a sliding vertical surface (220a and 220b) at the center and opening and closing in a direction perpendicular to the opening and closing direction of the first side plate. ) And a downwardly extending contact inclined surface (311a and 311b) that contacts the contact inclined surface (120a and 120b) of the first side plate on the outside.
And a corresponding first side block (310a) having sliding vertical surfaces (312a and 312b) on the inside and corresponding to each other.
And 310b), and a sliding vertical surface (321a and 321b) sliding on the sliding vertical surface (220a and 220b) of the second side plate on the outside, and a sliding inclined surface (322a and 322a) narrowing downward on the inside. A second side block (320a and 320b) having a corresponding halving and having a corresponding opening / closing operation in a direction perpendicular to the mold opening / closing direction.
And a corresponding sliding vertical surface (301) sliding on the sliding vertical surface (312a and 312b) of the first side block.
a and 301b), and reciprocatingly move in the opening and closing direction of a mold having corresponding sliding inclined surfaces (302a and 302b) narrowed downward and sliding with sliding inclined surfaces (322a and 322b) of the second side block. Center block (30
(0). An undercut removal mechanism (10) for an injection mold.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An undercut removal mechanism (10) for an injection mold according to the present invention can remove undercuts in all circumferential directions, and FIGS. 1 (a), (b) and (c). ), The center block (30
0) is sandwiched between the corresponding first and second side blocks (310a and 310b) and the second side blocks (320a and 320b). The first side plate (100a and 10a) having a split undercut portion at the upper center
0b) and the second side plate (200a and 200b)
And is assembled into a movable side mold in a required state by a spring or the like in a required state.

Next, each of the above components will be described in more detail. Center block (300)
Is a first side block (3) as shown in FIG.
10a and 310b) (312a and 31)
2b) and corresponding sliding vertical surfaces (301a and 301b), and as shown in FIG. 1C, the sliding inclined surfaces (322a and 322a) of the second side blocks (320a and 320b). 322b) has corresponding sliding slopes (302a and 302b) of downward constriction sliding with 322b).
As the mold is opened and closed, the ejector mechanism and a spring reciprocate a predetermined position in the mold opening and closing direction.

The first side blocks (310a and 310)
FIG. 1 (b) shows the corresponding two halves as shown in FIG. 1 (b), and the first side plates (100a and 100a)
b) has a downwardly extending contact inclined surface (311a and 311b) in contact with the contact inclined surface (120a and 120b), and slides inside on the sliding vertical surface (301a and 301b) of the center block (300). Vertical sliding surface (31
2a and 312b), which are fixed at predetermined positions when the mold is opened and closed.

The second side blocks (320a and 320)
FIG. 1 (b) shows the corresponding two halves as shown in FIG. 1 (c).
b) has a sliding vertical surface (321a and 321b) that slides with the sliding vertical surface (220a and 220b), and the lower side that slides with the sliding inclined surface (302a and 302b) of the center block (300) inside. Narrow sliding slope (322
a and 322b), which are opened / closed in a direction perpendicular to the mold opening / closing direction by a spring or the like when the mold is opened / closed.

The first side plates (100a and 100a)
As shown in FIG. 1 (b), b) is a corresponding halving, has undercut portions (110a and 110b) whose outer peripheral surfaces are undercut, and has a second portion in the center. It has a contact inclined surface (120a and 120b) which spreads downward in contact with the contact inclined surface (311a and 311b) of the one side block (310a and 310b), and the inclined pins (11a and 11b) and the spring as the mold is opened and closed. The opening / closing operation is performed in a direction perpendicular to the opening / closing direction of the mold.

As shown in FIG. 1 (c), the second side plates (200a and 200b) are correspondingly divided into two, and the undercut portion (the upper surface of which is undercut) 210a and 210b) and a second side block (320a and 320b) in the center.
b) has a sliding vertical surface (321a and 321b) and a sliding vertical surface (220a and 220b) that slides, and the first side plate (100a and 100b) is formed by an inclined pin or a spring when the mold is opened and closed. It opens and closes in a direction perpendicular to the opening and closing direction.

Next, the opening and closing operation of the undercut portion accompanying the opening and closing of the mold when the undercut removal mechanism for an injection mold according to the present invention is incorporated in the mold (movable side) will be described in detail. FIG. 1B is an explanatory view showing a state of a cross section taken along line AA ′ in FIG. 1A when the mold is clamped. Corresponding halves of the first side plate (100
a and 100b) are respectively brought into contact with the inclined surfaces (120) by guiding the inclined pins (11a and 11b) at the time of mold clamping.
a and 120b) to the abutment inclined surfaces (311a and 311) outside the first side blocks (310a and 310b).
b), and is located at the lowest position in the figure when the mold clamping is completed. Therefore, the first side plate (1
00a and 100b) above the undercut portion (11
0a and 110b) are open.

FIG. 2A is an explanatory view showing a state of a cross section taken along the line AA 'in FIG. 1A when the mold is opened. Corresponding halves of the first side plate (10
0a and 100b) are the internal springs (1) when the mold is opened.
5a and 15b) move upward in the figure,
The contact inclined surfaces (120a and 120b) are separated from the contact inclined surfaces (311a and 311b) outside the first side blocks (310a and 310b), and at the same time, inclined pins (11a and 11
By the guidance of b), when the mold opening is completed, the undercut portions (110a and 110b) above the first side plates (100a and 100b) are closed.

FIG. 1C is an explanatory view showing a state of a cross section taken along the line BB 'in FIG. 1A when the mold is clamped. Corresponding halves of the second side plate (200
a and 200b) respectively slide the vertical sliding surfaces (220a and 220b) into the second side blocks (32
0a and 320b), and are slid on the sliding vertical surfaces (321a and 321b) outside, and are located at the lowest position in the figure when the mold clamping is completed. At this time, the sliding inclined surface (3) inside the second side block (320a and 320b)
Since the center block (300) having the sliding slopes (302a and 302b) narrowing downward and sliding with the second side blocks (320a and 322b) is disposed at the lowest position in the drawing. 320
b) is in an open state, so that the undercut portions (210a and 210b) above the second side plates (200a and 200b) are in an open state.

FIG. 2B is an explanatory view showing a state of a cross section taken along line BB 'in FIG. 1A when the mold is opened. When the mold is opened, the ejector plate (12) rises in the figure by the spring provided therein, and the center pin (13) connected to the ejector plate slides the sliding inclined surfaces (302a and 302b) into the second side block (3).
20a and 320b) (322a and 32b).
2b) and slide up in the figure,
The side block is pushed toward the center by the spring provided therein, and is brought into a closed state. Therefore, the second side blocks (320a and 320b) sliding on the sliding vertical surfaces (321a and 321b) outside the second side block are in a closed state, and the upper undercut portions (210a and 210b) are closed. State. 14a and 14b are return pins for returning the ejector plate when the mold is clamped.

The collapsible core, which is a conventional undercut removal mechanism for injection molding dies, is provided with a segment portion provided inside the core so as to be automatically narrowed on the outer periphery.
This is a mechanism to protrude the segment portion by inserting the center pin, which requires a stroke for moving the center pin, and the mold thickness is inevitably increased. In addition, the structure may be complicated and the durability may be poor. On the other hand, as described above, the undercut removal mechanism for the injection mold according to the present invention basically includes the sliding inclined surface of the first side plate and the sliding inclined surface outside the first side block. Since the undercut portion is opened and closed with the opening and closing of the mold by sliding and sliding between the sliding inclined surface of the center block and the sliding inclined surface inside the second side block, the mold thickness can be reduced, Further, the structure is simple and the durability is good.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, undercut cut portions (110a and 110b) whose outer peripheral surfaces are undercut as shown in FIGS. Corresponding halves of the first side plate (100a) having the contact inclined surfaces (120a and 120b).
100b) and an undercut cut portion (210a and 210b) having an undercut on the outer peripheral surface above the center, and a sliding vertical surface (220a and 22b) at the center.
0b), the corresponding two-part second side plates (200a and 200b) and the downwardly extending contact slopes (311a) that are in contact with the contact slopes (120a and 120b) of the first side plate on the outside. And 311b)
Corresponding split first side blocks (310a and 31) having sliding vertical surfaces (312a and 312b) inside
0b) and the sliding vertical surface of the second side plate (2
20a and 220b) and a sliding vertical surface (321a)
And 321b), the corresponding two-sided second side blocks (320a and 320b) having sliding inclined surfaces (322a and 322b) narrowed downward inward, and a sliding vertical surface (1) of the first side block. 312a and 312b) and corresponding sliding vertical surfaces (301a and 301)
b) and the sliding inclined surface (322) of the second side block.
a and 322b) and a center block (300) having corresponding sliding inclined surfaces (302a and 302b) of downward narrowing sliding, and then the outer periphery of the central center block is correspondingly formed. A first side plate and a second side plate which are sandwiched between two first side blocks and a second side block, and further, the outer circumferences of the first side block and the second side block each have a corresponding undercut portion at the upper center. Then, the necessary portion was urged by a spring or the like at a necessary position, and the undercut removal mechanism for the injection mold of the present embodiment was incorporated into the movable mold.

Next, a mold incorporating the undercut removal mechanism of this embodiment is attached to the movable mounting plate of the injection molding machine, and as shown in FIG. 3A, the first side plate ( When the undercut portions (110a and 110b) of the second side plate (not shown) and the undercut portions (not shown) of the second side plate (not shown) are closed, the lower end of the peripheral wall (411) and the bottom wall ( 412), the bottom of a paper cup (410) having a polyethylene layer on the inner and outer surfaces forming an undercut was mounted with an insert device. Next, when the mold is clamped, as shown in FIG. 3B, the undercut portions (110a and 110b) of the first side plates (100a and 100b) and the undercut portions (110) of the second side plate (not shown). (Not shown), and the undercut in the entire circumferential direction at the bottom of the paper cup (410) was clogged. Inject polyethylene in this state,
As shown in FIG. 3 (c), a reinforcing frame (420) is heat-sealed at the same time as the reinforcing frame (420) at the opening peripheral portion, the back bonding portion, and the trunk bottom bonding portion of the paper cup (410), and the cup-shaped composite container (400)
Was prepared. When the mold was opened, the undercut portion was closed, the undercut at the bottom of the paper cup was released, and the cup-shaped composite container could be taken out. The continuous operation was repeated again, but no abnormality occurred in the undercut removal mechanism of the present embodiment. In addition, there was no pressing mark on the lower surface of the bottom wall of the cup-shaped composite container.

The undercut removal mechanism for an injection mold according to the present embodiment has, for example, an insert (512) made of paper, film, or the like on the top surface as shown in FIG. It can also be used for a wide mouth lid (500) having a screw portion (511) on the inner surface of the side wall (510).

[0022]

The undercut removal mechanism for an injection mold according to the present invention can remove undercuts in all circumferential directions and requires a large molding machine because the mold thickness can be reduced as compared with the conventional collapsible core. The durability is strong, and there is no pressing mark on the surface of the insert product.
It can also be used without inserts.

[Brief description of the drawings]

FIG. 1A is a plan view of an undercut removal mechanism according to an example of the present invention, FIG. 1B is an explanatory view illustrating a structure taken along a line AA ′ of FIG. 1, and FIG. It is explanatory drawing which shows the structure in BB 'line cross section.

FIG. 2A is an explanatory view showing a state when the mold is opened in a cross section taken along line AA ′ of FIG. 1A, and FIG.
FIG. 4 is an explanatory diagram showing a state when the mold is opened in a cross section taken along line BB ′.

FIG. 3 (a) shows a state in which the undercut bottom of a paper cup is attached to a closed undercut portion when the mold is opened, in an undercut removal mechanism of an example of the present invention incorporated in a mold. It is explanatory drawing which shows the state which the undercut part opened and the undercut was packed at the time of mold clamping, and (c) is an explanatory view of the composite cup which formed the reinforcing frame in the paper cup in that state. It is a perspective view.

FIG. 4 is a cross-sectional view of a wide-mouthed lid having a threaded portion on the inside of a peripheral wall, which can be manufactured by using the undercut removal mechanism of the present invention.

[Explanation of symbols]

 10 Undercut removal mechanism 11, 13, 14 Pin 12 Ejector plate 15, 16, 17 Spring 100, 200 Side plate 110, 210 Undercut section 120, 311 Contact Inclined surface 220, 301, 312, 321 Sliding vertical surface 300 Center block 302, 322 Sliding inclined surface 310, 320 Side block 400 Composite container 410 Paper cup 420 Reinforcement frame 500 wide mouth 510 peripheral wall 511 screw part 512 insert

Claims (1)

[Claims] 1. A first side which has an undercut portion at an upper portion, has a contact inclined surface extending downward at a center portion, and is opened and closed in a direction perpendicular to the opening and closing direction of a mold by a corresponding half. A second plate, which has an undercut portion at the top and a sliding vertical surface at the center and has a sliding vertical surface, and which opens and closes in a direction perpendicular to the opening and closing direction of the first side plate.
A side plate, a split first side block having a downwardly extending contact inclined surface in contact with the contact inclined surface of the first side plate on the outside, a sliding vertical surface on the inside, and a corresponding first side block; A sliding vertical surface that slides with the sliding vertical surface of the second side plate, and a corresponding half with a sliding inclined surface that narrows downward inside, and is perpendicular to the opening and closing direction of the mold. A second side block that opens and closes in a direction, and a corresponding sliding vertical surface that slides on a sliding vertical surface of the first side block, and a downward narrowing that slides on a sliding inclined surface of the second side block. And a center block that reciprocates in the opening and closing direction of the mold having a sliding inclined surface corresponding to the above.