JPS58980B2 - Undercut mold with screw removal mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an undercut mold having a screw extraction mechanism, and more particularly to a mold for injection molding a product having a threaded portion on the undercut surface at the same time.

For example, when a molded product is integrally molded using an injection mold, if a part of the product has an undercut surface, a part of the mold should be set as a slide core to make it possible to eject the product. This is commonly done.

Further, when a molded product is integrally molded using an injection mold, if a threaded portion is present in a part of the product, it is common to mechanically remove the screw using a rotating mechanism.

When a molded product is integrally molded using an injection mold, if a part of the product has an undercut surface and a threaded part at the same time, the slide core is equipped with a removable threaded core and the threaded core is attached to the product. Conventionally, the slide core is moved back in the fitted state, the product is ejected, and then the screw core is manually removed by an operator.

When injection molding a product in which an undercut surface and a threaded portion are present on the same surface at the same time, there has been no mold that combines a slide core set with a rotary screw extraction mechanism.

A conventional example of manually extracting the screw core will be described below.

FIG. 1 is a perspective view showing a camera body integrally formed with a mold, and has a threaded portion 2 on an undercut surface 1. As shown in FIG.

FIG. 2 is a cross-sectional view schematically showing a mold when a molded product as shown in FIG. 1 is ejected from the mold by being ejected in the direction of arrow A.

In the figure, 3 is a movable template, and 4 is a fixed template.

5 is a slide core, part of the core 5 on the undercut surface
a is formed and is slidably held on the movable template 3.

A screw core 6 is provided with a screw 6a and is detachably held in the slide core 5.

7 is a molded product, 8 is an angular pin, and 9 is an ejector pin.

In order to take out the molded product 7 from the state in which resin injection has been completed as shown in FIG. 2, as shown in FIG. The undercut surface core portion 5a is then slid back and removed.

At this time, the screw core 6 remains attached and screwed to the molded product 7.

Thereafter, when the mold plate 34 is further opened, the ejector pins 9 eject the molded product 7 and it is ejected from the mold.

Since the screw core 6 is attached to the molded product discharged from the mold, the operator manually rotates the screw core 6 and pulls it out.

On the other hand, a screw core 6 is similarly fitted into the slide core 5 by an operator in preparation for the next injection molding.

Hereinafter, since the closing operation of the template is well known, the explanation will be omitted.

However, the conventional method described above has the disadvantage that the injection molding process involves a manual step by the operator, which increases the time required for one molding cycle.
This inevitably led to an increase in the cost per unit.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, it is an object of the present invention to provide a mold that can fully automatically mold even a product in which a threaded portion is broken on an undercut surface.

The feature of the present invention is that it combines a slide core and a rotating shaft having a part of a screw core, and the rotating shaft is guided by the slide core and can move forward and backward while rotating. The reason is that it has a structure that allows it to slide.

Another feature of the invention is that the rotating shaft is guided by the slide core and can move forward and backward while rotating, but is not affected by the sliding movement of the slide core.

The present invention will be explained below based on one embodiment shown in the drawings.

FIG. 4 is a simplified cross-sectional view of the movable side, showing the state immediately before resin injection is completed.

In the figure, M is a molded product, and an undercut surface and threaded portion Ma are molded therein.

10 is a movable template, the shape of which is omitted.

A slide core 20 is formed with a core portion 20a for the undercut surface, and is composed of a bearing 21, a thrust ball bearing 22, a screw bush 23, a countersunk spring 24, a grease tap 25, a ball bush 26, and a retaining screw 27. It is slidably held on the side template 10.

The screw bush 23 is formed with a screw 23a having the same lead as the lead of the threaded portion Ma of the molded product M, and although rotation is prevented by a key, it is movable in the sliding direction of the slide core 20. It is.

However, normally it is suppressed by the countersunk 24.

30 is a screw core, which corresponds to the screw voice part Ma of the molded product M.
A threaded portion 30a corresponding to the rotary shaft 31, which will be described later, is formed.
is integrally held.

In this embodiment, it is fixedly held by a dowel pin or the like so that it can be replaced.

Reference numeral 31 denotes a rotating shaft, which has a key groove 31b in the thrust direction of a threaded portion 31a1 that is screwed into the threaded portion 23a of the threaded bushing 23, and is rotatably and slidably held by a ball bushing 26°46.

40 is a gear box, gear train 41, 42° 43.4
4, a motor 45, a ball bush 46, thrust ball bearings 47, 48, a nut 49, and a washer 50, and is integral with the movable mold plate 10.

The gear 44 is connected to the keyway 31b of the rotating shaft 31 by a key 44a.

Reference numeral 51 denotes a slide block which forms a contact surface 51a and is guided by a guide 52 and is slidable in a direction perpendicular to the plane of the paper.

Next, the operation of the above configuration will be explained.

FIG. 4 shows the state just before the injection of resin is completed, where the slide core 20 is pressed by the slope of the stationary template (indicated by the two-dot chain line), and the rotating shaft 31 is at the end of the slide block 51. It is pressed by the contact surface 51a.

Therefore, the injection pressure of the resin can be resisted, and an accurate cavity can be formed and maintained.

Thereafter, when the injection is completed, the motor 45 is activated by the completion signal, and the rotary shaft 31 is rotated via the gear train 41, 42, 43, 44, the key 44a1, and the keyway 31b.

Therefore, as shown in FIG. 5, the screw core 30 and the rotating shaft 3
1 is rotated and retreated by the threaded bush 23, and the threaded portion 30a of the threaded core 30 is extracted from the molded product M.

At this time, the slide block 51 is slid and retracted downward perpendicular to the plane of the drawing in conjunction with the operation of a plunger or the like (not shown) before the motor 45 is activated.

When the screw removal is completed, the mold begins to open, and in conjunction with this, as shown in FIG. 6, the slide core 20 retreats and a portion of the undercut surface core 20a is extracted.

As the slide core 20 slides, the rotating shaft 31 connects the key groove 31b with the key 44a1 and the ball bush 4.
6 and slides in the thrust direction.

The backward sliding movement of the slide core 20 is interlocked with the rotating shaft 31 by the threaded engagement of the screws 23a and 31a.

Thereafter, when the mold is further opened, the ejector pins eject and eject the molded product M, completing one molding cycle.

During the above-mentioned molding cycle, the rotary shaft 31 is moved in the thrust direction or expanded by, for example, resin pressure or heat acting on the end face of the screw core 30, and the threaded portion of the screw bush 23 and the rotary shaft 31 are If a situation where galling or damage is about to occur, the screw bush 23 slides against the pressure of the disc spring 24, making it possible to prevent these situations from occurring.

The above is a configuration in which the undercut surface is generally removed after the screw is removed.Next, another invention in which the screw removal and the undercut surface are removed simultaneously will be described.

FIG. 7 is a simplified cross-sectional view of an embodiment of another invention, 100
is the movable side template.

120 is a slide core, and a core part 120a for an undercut surface is formed.

Reference numeral 131 denotes a rotating shaft, which includes a screw core part 131a, a screw 131b with the same glue as the screw core part 131a, and a key groove (
(not shown) is formed.

Reference numeral 123 designates a threaded bushing having a threaded bush 123a that is threadedly engaged with the threaded thread 131b.

124 is a disc spring, 122 is a thrust ball bearing, 126 is a ball bushing, and 127 is a nut, which are arranged on one side of the gear box 140.

Although the configuration of the gear box 140 is omitted,
It has the same configuration as FIG. 4.

The operation of the above structure is almost the same as that of the structure shown in FIG. 4, but since the slide core 120 and the rotating shaft 131 are not screwed together, they can each operate independently.

Therefore, simultaneously with the injection end signal, the mold can be opened, the slide core 120 can be slid backward, and at the same time, the motor can be rotated to remove screws.

As described above, since the present invention has a configuration in which a slide core set and a screw removal mechanism are combined, even a molded product in which a slide core surface and a threaded portion are present at the same time can be molded fully automatically.

Therefore, it is possible to shorten one molding cycle.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a molded product having a threaded part on the undercut surface, Fig. 2 is a sectional view schematically showing a conventional mold, Fig. 3 is an explanatory diagram of the operation of Fig. 2, and Fig. 4 is a simplified sectional view of a mold according to the present invention, FIGS. 5 and 6 are explanatory diagrams of the operation of FIG. 4, and FIG. 7 is a simplified sectional view of a mold according to another invention with some parts omitted. be. M, M'...Mold product, 10,100...Movable side template,
20.120...Slide core, 20a. 120a... Part of the core for the undercut surface, 23° 123
...screw bush, 30...screw core, 31°131...rotating shaft, 131a...part of screw core, 40°140...gear box, 45...motor.

Claims (1)

[Scope of Claims] 1. A fixed side template, a movable side template, which is capable of reciprocating sliding in a direction orthogonal to the opening/closing operation in conjunction with the opening/closing operation of both templates, and has an undercut surface. A part of the core and a through hole parallel to the sliding direction are formed, and a threaded bush movable in the thrust direction is provided in the through hole, in which a threaded part of the lead that is the same as the threaded part of the molded product is formed. a rotational drive source having a gear train and held by the template on the side having the slide core; a part of the screw core at the tip and a screw portion of the slide core that screws with the screw bushing; a rotating shaft that is formed in the slide core, passes through the through hole of the slide core, and is held so as to be movable in the thrust direction and interlocked with the rotation of the gears constituting the gear train; By rotating the rotating shaft in conjunction with the gear train,
A mold for undercuts having a screw extraction mechanism characterized in that first, a portion of the screw core is rotated backward and extracted, and then a portion of the undercut core is extracted by sliding the read slide core backward. 2. A fixed side template, a movable side template, which is capable of reciprocating sliding in a direction orthogonal to the opening/closing operation in conjunction with the opening/closing operation of both the templates, and has a portion of the undercut surface core and the movable side template. A slide core in which a through hole parallel to the sliding direction is formed, and a through hole held in the template on the side having the slide core and in the same window as the through hole of the slide core, A member is provided with a threaded bush movable in the thrust direction in which a threaded part of the same lead as the threaded part of the molded product is formed in the through hole, and a member is held by the template on the side having the slide core. a rotational drive source having a gear train; a threaded portion that is threadedly engaged with a portion of the threaded core at the tip and a threaded bushing of the member, and passes through the through hole of both the slide core and the member; and a rotating shaft held movably in the thrust direction and interlocked with the rotation of the gears constituting the gear train, and removing a part of the core for the undercut surface by sliding the slide core backward; A mold for undercuts having a screw extraction mechanism capable of simultaneously extracting a part of the screw core by rotating the rotating shaft backward.