JP2949317B2 - Mold structure for injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold structure for molding an injection-molded article, and more particularly to a large-sized molded article or a thin-walled molded article having a good appearance without leaving a gate mark on the surface of the molded article. It relates to a suitable mold structure.

[0002]

2. Description of the Related Art An injection-molded article is formed by pouring a molten resin at a high pressure and a high speed into a mold having a product-shaped space attached to an injection molding machine, and cooling and solidifying the resin in the mold.

As shown in FIG. 12, the injection molding machine includes a mold clamping section A, an injection section B for melting, kneading and injecting resin, a hydraulic drive control section C for driving and controlling them, and an electric control section D.
Consists typically clamping unit in a mold movable side M ₁ the boundary of the mold M A, On the other hand, a injection unit B is disposed on the fixed side M _2,
When the molded product is released from the mold M on the mold clamping portion A side, an ejector pin for projecting the molded product from the mold M
An ejector rod (not shown) for driving the ejector board is provided.

[0004] In the above injection molding machine, the injection section B
Conventionally, as shown in FIG. 13, a mold M structure disposed between the mold clamping portion A and the mold clamping portion A includes a fixed-side mounting plate 51 for connecting a mold body and a molding machine, and a movable-side mounting plate 52. Are fixed at both ends, and a fixed-side mold plate 54 is provided between the two on the fixed-side mounting plate 51 side via a runner leash plate 53, while the movable-side mounting plate 52 side is provided with a receiving plate 55 via a receiving plate 55. Template 5
6 are respectively mounted to form a product-shaped space (cavity) 57 as a product part between the two mold plates 54 and 56, and the center of the locate ring 58 fitted in the center of the fixed-side mounting plate 51 is formed. Spool bush 59 installed in the section
The molten resin injected from the injection section B through the spool 60 is allowed to flow into the space 57 of the product shape through the runner 61 and the gate 62, and the ejector board 63 is provided on the opposite movable side mounting board 52 side. And the ejector pin 64 is fixed thereto, and the ejector pin 6 is fixed within a range regulated by the core pin 65.
When the molded product is detached from the mold by making the molded product 4 protrudable, the molded product can be protruded.

[0005]

However, in the above-described mold structure, as described above, the ejector pins and the ejector board and the ejector rod for moving the ejector pins are arranged on the mold-clamping side. Shape space 57
Surface side of, i.e., the spool 60 is a passage of molten resin to the front surface side P ₁ Product product shape space 57, the runner 61, the gate 62, whereas the mold a molded article on the back side P ₂ Product When detaching from the device, it is necessary in terms of design to arrange a molded product ejecting mechanism such as an ejector pin 64 and an ejector board 63 for ejecting the molded product. In particular, it is natural that the ejector pin is set on the back side of the molded product because the protrusion mark remains as a dent in the product.

In the case of large molded products and thin molded products,
At the gate at the point, the flow stops because of pressure loss generated when the molten resin flows into the mold and cooling and solidification due to heat transfer of the molten resin to the mold. For this reason, in the case of these molded products, gates are usually set at multiple points, but after molding, the molded product is separated from the runner from the gate portion, so that gate marks are formed on the surface of the molded product. This left the appearance significantly impaired. Therefore, in the past, when the product was partly manufactured, attempts were made to consider the setting position, such as setting the gate at a position hidden behind other parts and becoming invisible. It is very difficult depending on the number, and there is a problem in design, such as changing the shape to make the gate trace inconspicuous.

The present invention addresses the actual situation as described above, and pays particular attention to the arrangement of the respective parts in the mold structure, in particular, the gate arrangement position. In addition to improving the appearance of the product without leaving traces on the surface of the molded product, it is particularly applicable to large-sized molded products and thin-walled molded products that are difficult to mold with a single-point gate due to the flow length of the resin. An object of the present invention is to make it easier to produce the above-mentioned good appearance product in a molded product.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a mold to be mounted on an injection molding machine. Let's place it. Further, the ejector mechanism necessary for releasing the molded product is defined as the fixed side of the die (in this case, the injection portion side of the die, that is, the back side of the molded product.
The mechanism is provided by a movable side (in this case, the mold clamping side of the mold, that is, the surface side of the molded product; hereinafter, referred to as a movable side) and a pulling mechanism such as a chain, a bolt, and a link. The ejector mechanism is driven by a mechanism interlocked so that the mold is pulled for the first time when the mold is opened to a preset distance, and the mold is released.

The arrangement of the gate on the back side of the molded product means that the spool, the runner, and the gate, which are the passages of the molten resin, are all disposed on the fixed side in addition to the ejector mechanism. Numerous mechanisms such as bolts and cooling holes for fixing other mold parts are also arranged on the fixed side.

[0010]

When the above-mentioned mold structure is used, the gate is set on the back surface with a multipoint gate, so that no trace of the gate is left on the surface of the molded product, a good appearance can be obtained, and when the gate is set at one point. In comparison, the pressure distribution difference in the molded product is reduced,
Distortion such as residual stress in a molded article is reduced to reduce deformation. In addition, by setting the gate as a multipoint gate on the back side, it is possible to optimally arrange the gate to fill the molded resin in consideration of the resin flow, and to provide large molded products and thin molded products with good overall appearance. Makes molding easier. Further
As a structure to protrude the molded product, a molded product delivery board is provided,
Push out the rising part of the molded product and pay out
Using the fact that the board and the fixed mold are opened,
By moving the slide mechanism provided, the back side of the molded product (gate
(Constant side) by projecting it over a wide surface,
Prevent shape. Also, by assembling the molded product with other parts
If a mounting boss is required,
Using the opening between the platen and the fixed mold plate, the molded product is ejected
First, pull out the center pin of the boss first, then start
To facilitate release of molded products.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0012] Figure 1 is an example of a mold structure according to the present invention, reference numeral 1 denotes a fixed-side mounting plate, 2 a movable side mounting plate, locating ring 3 is fitted to the center of the stationary side mounting plate 1 It is deposited, that have been further spool bush 4 is fitted at its center.

[0013] Between the fixed-side mounting plate 1 and the movable-side mounting plate 2, a runner levitating plate 5 and a fixed-side mold plate 6 are sequentially arranged on the inner surface of the fixed-side mounting plate 1. Spool 7 and runner 8
And a gate 9 are provided in the same manner as in the known case, and a movable mold plate 10 is mounted on the inner surface of the movable mounting plate 2 on the opposite side.

In the above-described mold structure, the gate 9 is composed of a multi-point gate, and the product shape space 11 of the mold body formed by the fixed mold plate 6 and the movable mold plate 10 is a molded product whose movable side is a molded product. The spool 7, the runner 8 and the multipoint gate 9, which are the runners for flowing the molten resin to the product shape space 11, are all formed so that the front side and the fixed side of the molded product are the rear side of the molded product. It is arranged on the back side of the molded product.

[0015] Then, et Jekutapin in FIG. 1 as the ejector mechanism products leprosy out plate 16 is used as the ejector mechanism 14 particularly provided with Orazu, instead, the slide member 15 (see Figure 3) the in leprosy As compared with the case where the ejector board is interlocked with the ejector board 16, the reliability and workability are improved without providing complicated holes and inclined pins in the mold part as compared with the case where the ejector board is interlocked. It achieves space saving and secures a fixed space for the gate structure on the back side.

[0016] In this case, as the drive mechanism of the ejector mechanism 14 is driven by the slide member 15 is performed.

[0017] FIGS. 2-5 are details of the molded article ejection mechanism of the ejector mechanism 14 with the slide member 15, FIG. 2 shows in a mold clamping state, FIG. 2 is a state open runner type, 3 state runner runner was paid in leprosy Release, 4 product parting the opened state, FIG. 5 shows a state the product unit product was paid in leprosy out board.

That is, as shown in the drawings, a slide member 15 is accommodated in the ejector mechanism 14 in an inclined state inside a product dispensing board 16.
The product advances in an inwardly inclined manner on the inner surface of the unwinding plate 16 along the guide groove 17 on the outer periphery of the mold portion of the fixed-side mold plate 6 so that the molded product protrudes from the fixed-side mold plate 6 and can be removed. I have.

[0019] This will be described in more detail according to the sequence, Figure 1
In the mold clamping state, the molten resin flows into the mold body having the product-shaped space 11, and when the molding is completed, first, the runner 5 on the inner surface of the fixed-side mounting plate 1 is left and the fixed-side mold plate 6 is movable. The mold body portion made of the side mold plate 10 is detached.
(FIG. 2 ) At this point, the runner 8 is taken out.
(FIG. 3 ) Next, when the runner is taken out, the product part is opened to separate the fixed mold plate 6 and the movable mold plate 10 (FIG. 4 ). Is held in.

In this state, the product opening plate 16 having the fixed mold plate 6 and the ejector mechanism 14 is further separated, and the product opening plate 16 responds to the tilting movement of the internal slide member 15 along the guide groove 17. A gap is formed between the fixed side mold plate 6 and the undercut portion and the slide member 1.
5 to facilitate removal of the product P (Fig. 5 ).

In FIGS. 2 to 5 , parts that are not necessary for explanation of the operation are omitted, and only the necessary range is shown.
In the drawings, the same reference numerals denote the same parts.

FIGS. 6 to 10 show an embodiment in which the ejector mechanism according to the present invention is modified so as to reduce the release resistance of the boss portion. Instead of the slide member described above, a spring 19 urged to the fixed side is provided. A boss portion removing pin 18 is provided. The spring 19 is suppressed by a holding plate 20 and the tip of the pin is inserted into the boss portion 21 at the time of mold clamping.

FIG. 6 shows a state in which the mold is clamped. In this state, the molten resin passes through the passage and passes through the product shape space 11.
And molding is performed. Then, after the solidification and cooling, when the molding is completed, first, the fixed side mounting plate 1 is separated from the mold side with the runner levitating plate 5 attached as in the case described above. (FIG. 7 ) At this time, the back of the spring 19 is released, and the spring 19 returns to the position of the holding plate 20 by the urging force of the spring. At the same time, the tip of the pin 18 comes off from the boss 21.

On the other hand, the runner levitating board 5 separates from the fixed side mounting board 1 and the runner 8 is taken out (FIG. 8 ).
Further, the movable mold plate 10 separates from the fixed mold plate 6, and the product part parting (the mold opening surface of the molded product) is opened. (Figure
9 ) After that, the product unwinding board 16 separates from the fixed side mold plate 6, and the molded product P is separated from the mold plate 6 and taken out. (FIG. 10 )

In the above case, since the pins inside the boss come off before the product part parting of the molded product is opened, the size of the mold can be further reduced.

As described above, the molten resin flows into the product shape space through the spool, the runner, and the gate on the back side of the molded product as described above, and at the same time, the ejector mechanism can be arranged on the back surface of the molded product to perform molding. Even in the case of a multipoint gate, the gate can be set at an optimal position for flow regardless of the appearance of the molded product.

Although the drawings according to the above description use the cold runner system, the same applies to the hot runner system.

[0028]

According to the present invention, there is provided a mold for producing an injection-molded article as described above,
A runner and a multi-point gate are arranged on the back side of the molded product in the same way as the ejector mechanism. Since the gate is set on the back side of the molded product with a multi-point gate, the molded product is compared to the case where the gate is set at one point. Because the pressure distribution in the inside, that is, the pressure loss increases as the distance from the gate increases, the pressure distribution at the gate part where the pressure is the highest and the pressure at the final filling position where the pressure tends to be the lowest decreases, and the residual stress in the molded product decreases. Not only the distortion is reduced and the warpage is reduced, but also the gate traces that have not been solved conventionally, especially the gate traces of multi-point gates, are left without leaving the ejector traces on the surface of the molded product.
It has a remarkable effect that a large molded product and a thin molded product having a very good appearance can be obtained.

When the multipoint gate is arranged on the back side of the molded product, the ejector mechanism is changed. When a slide member is provided and the slide member is interlocked with the product dispensing board, the conventional ejector board is interlocked. space is not necessary in comparison with the case that has been allowed to provide a complicated holes or inclined pin mechanism in the mold portion is facilitated, which is preferable to ensure the fixed side space of the gate structure of the molded article back side.

Further, when a boss portion provided with a boss portion is used as a substitute for an ejector, when the runner portion mold is opened, the rear portion of the boss removed pin inside the boss is no longer suppressed, and the biasing force of the spring is returned. Therefore, the pin comes off before the mold opening surface of the molded product is opened, so that the mold can be reliably released.

It should be noted that the mold structure of the present invention is effective for producing a good-looking product even in a large-sized molded product or a thin-walled molded product, in which molding is considered difficult due to the flow length of the resin particularly at a single point gate. is there.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part showing a mold structure having an ejector mechanism of a slide mechanism in another embodiment according to the present invention.

FIG. 2 is a view showing a runner part mold open state of the mold structure shown in FIG. 1 ;

3 is a diagram showing a state in which paid runner portion from the state shown in FIG. 2.

4 is a diagram further showing a state in which the product portion parting opening than the state shown in FIG. 3.

FIG. 5 is a view showing a state in which the product section has been separated from the product dispenser, following FIG. 4 ;

FIG. 6 is a view showing a mold clamping state of a mold structure according to still another embodiment of the present invention having an ejector mechanism having a boss part removing structure.

FIG. 7 is a view showing a state in which a runner portion of the mold structure of FIG. 6 is opened;

8 is a view showing a state in which the runner portion has been separated by a runner disc in the mold structure of FIG. 6 ;

FIG. 9 is a view showing a state where a product part of the mold structure of FIG. 6 is opened.

FIG. 10 is a view showing a state in which a product part is separated by a product separating board in the mold structure of FIG. 6 ;

FIG. 11 is a schematic diagram showing a general configuration of an injection molding machine.

FIG. 12 is a schematic view of a main part showing an example of a conventional mold structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed-side mounting board 2 Movable-side mounting board 5 Runner separating board 6 Fixed-side template 7 Spool 8 Runner 9 Gate 10 Movable-side template 11 Product shape space 12 Ejector board 13 Ejector pin 14 Ejector mechanism 15 Slide member 16 Product ejection Board 17 Guide groove 18 Boss removing pin 19 Spring 21 Boss

Continuation of the front page (56) References JP-A-4-151222 (JP, A) JP-A-4-67923 (JP, A) JP-A-47-16554 (JP, A) JP-A-63-237920 (JP) JP-A-63-15723 (JP, A) JP-A-60-212321 (JP, A) JP-A-56-169047 (JP, A) Japanese Utility Model Laid-open No. 53-96068 (JP, U) (58) Surveyed field (Int.Cl. ⁶ , DB name) B29C 45/26-45/44

Claims (2)

(57) [Claims] In a mold for molding an injection-molded product, a product-disconnecting plate is inserted between a fixed-side mold plate and a movable-side mold plate so that a convex portion of the fixed-side mold plate is inserted into the center of the mold plate. A spool, a runner, and a gate for pouring the molten resin into the product shape space formed by the above are arranged on the back side of the molded product, and the gate is a multipoint gate of two or more points, and
An ejector mechanism including a slide member that inclines and slides inward in order toward the movable side is provided between the inner periphery of the fixed-side template convex part insertion part at the center of the protruding board and the outer periphery of the fixed-side template convex part. A mold structure for molding an injection-molded product, comprising: 2. A mold for molding an injection-molded article, wherein a protruding plate for inserting a convex portion of a fixed-side mold plate into a central portion is interposed between a fixed-side mold plate and a movable-side mold plate. A spool, a runner, and a gate for pouring the molten resin into the product shape space formed by the above are arranged on the back side of the molded product, and the gate is a multipoint gate of two or more points, and
A boss-extraction pin having a spring biased to the fixed side is installed over the unloading plate and the fixed-side mold plate. When the pin tip is closed, the boss is inserted into the boss on the back side of the molding and the mold is opened. A mold structure for molding an injection-molded article, wherein the pin returns inside the boss before the mold-opening surface of the molded article opens, when the rear portion is no longer held down.