JPS60255409A - Injection mold - Google Patents

Abstract

PURPOSE:To provide an injection mold, wherein gate cutting secondary processing was dispensed with, capable of obtaining a smooth surface free from a gate sink mark or a gate dimple, constituted so that an injection molded product according to a pinpoint gate system is cut by the gate in a mold. CONSTITUTION:A rotor core 3, which is processed so that a second sprue hole 16 and a gate hole 17 are made eccentric to a rotary center axis, is inlaid with a 3# plate 2 in a freely rotatable manner. One end of the rotor core 1 forms a part of a cavity 18 while the other end thereof is directly faced to a 1# plate 4 or can be freely slid on the surface of the 3# plate 2 at the opening time of a mold and constituted so as to be contacted with the movable plate located and fixed with respect to the 1# plate 4 and the 1# plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an injection mold for in-mold gate cutting using a bin point gate method in plastic injection molding.

[Prior art]

The gate cutting method of the molding die using the bin point gate method in conventional plus injection molding is as shown in FIG. After completion of the mold clamping process in the injection molding process 2 Forcibly open the space between the plates 515 and 2 with the spring 9 and open the second sprue 16 with the 3 plate 2
The method involved tensing and breaking the gate portion 17 at the same time as it was pulled out, and the state of breakage was not consistent. Figure 6.

FIGS. 7 and 8 show various states of a so-called gate-bottom phenomenon that occurs on a molded product processed using a bin point gate type molding die. Also the 9th
The figure shows a state in which a part of the molded product was gouged out when the gate part was broken. Gate bombs are harmful to the functionality and appearance of molded products. The condition where a part of the molded product is gouged out can also be a problem in printed circuit boards where additive processing is applied to the surface of the molded product, and in addition, in thin molded products with a thickness of 0.5 tan or less, holes may form at the gate as shown in Figure 10. often penetrates. The current countermeasures against these gate holes and gouges are to designate a gate location where there will be no problem even if gate holes or gouges occur, or to make the gate part on the molded product concave in advance, as shown in Figure 11. However, there may be more gate bogs than expected,
If the selection of the gate location is not allowed and it is not possible to make it even more concave, the gate bottom portion is re-cut or secondary processing such as hot pressing is performed to correct it. In general, the pinpoint gate method can employ multiple points and is applied to relatively thin and large molded products, but the current situation is that it is always difficult to control the gate height. Furthermore, in the conventional bin point gate method, the gate part 17 is tensilely broken due to the biting force of the runner lock bin 10 into the runner 15, so the gate diameter cannot be made too large, making it difficult to make thick-walled molded products. has been avoided and the side gate method and direct gate method have been mainly applied, but the molded products obtained by these methods are premised on secondary gate cutting processing.

〔the purpose〕

The present invention is intended to solve the above-mentioned problems, and its purpose is to cut an injection molded product using the pinpoint gate method using the in-mold gate, to obtain a smooth surface without gate holes or gate gouges, and to obtain a pinpoint gate cut. The purpose is to make the gate method applicable to molded products with large walls, eliminate the need for secondary gate cutting processing, and obtain a high-quality gate cut surface.

〔overview〕

The injection molding mold of the present invention is a pinpoint gate type injection molding mold in which the rotary body core, in which the second sprue hole and the gate hole are eccentrically processed with respect to the central axis of the rotary body, is inside the 5# plate. One end of the rotating body core 1 constitutes a part of the cavity, and the other end constitutes a part of the cavity.
Directly facing the plate or 3# when opening the mold
An injection mold that is configured to be able to freely slide on a plate surface and to be in contact with a movable plate that is positioned and fixed relative to the 1# plate and 6# plate when the mold is closed. It is.

〔Example〕

The present invention will be described in detail below based on examples.

FIG. 1 (α) shows an embodiment according to the present invention in which the mold clamping process in the injection molding process is completed and the mold clamping pressure is unloaded.
Plates 4 and 3 This figure shows a state in which the space between plates 2 is pushed apart by a spring 9. At this time, as shown in the figure, the runner 15 is still connected to the molded product through the gate 17, and due to the adhesive force of the second sprue 16, the rotating body core holder comes to the plate 22 side. Next gate 17
The central axis is the rotation axis and the gate diameter 23 in Fig. 1 Cb)
The rotor core 1, which is eccentric by 72 or more, is rotated by the operating force of the pneumatic or hydraulic cylinder 7 using the pinion 8 and rack 6 fixed on the circumference of the rotor core 1 as a driving force transmission path, and the second sprue is rotated by the operating force of the pneumatic or hydraulic cylinder 7. There is relative slippage between the mold inner surface and the resin surface, and the center of the gate 17 is centered on the rotating body core 1.
The connecting portion between the molded product 18 and the gate 17 is cut off by shearing stress. In the case of a multi-point gate, as shown in No. 21i4(a), the rotating body core 1
The number of gates installed is the same as the number of gates, but as shown in Figure 2C
As shown in h), the eccentricity 25 and phase angle 26 of the central axis 21 of the second sprue 16 and the rotating shaft 2o of the rotating body core 1 must be set to be the same for all rotating body cores. Due to the operation of the pneumatic or hydraulic cylinder 7, all the rotor cores 3 begin to rotate in the same direction at the same time and the central axis 21 of the second sprue
performs a small circular motion around the rotating shaft 20 and moves to 21', the runner center axis 24 moves to 24', and the runner 15 slides against the rotating body receiving plate 22. As the rotor core 1 rotates, gate cutting is completed and the mold is opened, and as the 2# plate 2 moves away from the 1# plate 4,
A part of the runner 15 hits the runner piece 11, and the second sprue is pulled out from the rotating body core 1, and the runner falls. Since the runner 15 and the second sprue 16 are released from the mold surface when the rotor core 1 rotates, the second sprue 16 can be easily pulled out. After the mold opening is completed, the rotor core 1 is rotated in the reverse direction by the return stroke of the cylinder 7, and the positions of each gate are returned to their predetermined positions.

FIG. 3 shows another embodiment of the present invention, in which a lever 12 is fixed to the circumferential portion of the rotor core 1, and one end of the lever 12 protrudes from the 5" plate 2, and a cam plate 13 fixed to the 1" plate 4. The 2# plate 15 is held in place by the 2# plate holder 14 so that it can slide between the 5# plate 2 and the 5# plate 2 with an appropriate clearance. A mold opening regulating piece 19 is set at the end of the mold opening regulating piece 19, and a part thereof is inserted into the mold opening regulating groove of the cam plate 16. When the mold opening process of the injection molding process starts, the 6" plate 2 and the 4# plate 5 move back together by the mold opening regulating piece 19, and the space between the 1# plate 4, the 2# plate, and 15 opens. Then, the lever 12 in the groove of the cam plate 13 is actuated, and the rotating body core 1 starts rotating.The rotational movement is achieved through the second sprue 16 by simultaneously rotating the plate 15 and the runner 15 attached thereto. The rotating body core 1 rotates smoothly.

The rotating body core 1 is rotated by an amount set by the waste rate 13, and the gate portion is cut. Next, the mold opening regulating piece 19 between #5 plates 2 and #4 plates 5 is slid by the cam plate 13 in the direction of releasing the restriction, and the space between #3 # plates 2 and #4 plates 5 is opened. When the first plate 4 and the second plate come into contact with each other in the mold closing process, the position of the second plate 15 is determined by the runner hook 11.

〔effect〕

As described above, according to the present invention, in the rotor core having the sprue and the gate hole, at least the gate hole is made eccentric, and means for rotating the rotor core for cutting the gate is provided, so the bin point gate method is used. Even with injection molding, the gate part of the molded product has a smooth surface that is uniform with the surrounding surface, and there is no need for re-cutting the gate boss or pressing. In addition, holes in the gate portion often occurred in conventional thin-walled molded products, but this can be avoided by applying the present invention. When setting the position and size of the gate in the product design of a molded product, we are concerned about deterioration of appearance and functionality due to gate holes and gouges, so we place the gate in an inconspicuous place or a position unrelated to its function, or place it as small as possible. Although gates and four gate holes are installed, these all have a negative effect on the resin filling ability and pressure holding ability during molding, and in other words, they are a compromise between molding quality and product quality. Application of the invention makes it possible to consider molding quality and product quality independently. In other words, the upper molding trowel can be set at the most effective position and with the most effective gate size, and there is no need to worry about deterioration of the appearance or function of the molded product due to the gate.

Among resins, polyamide, polyester thread, urethane, etc., are extremely susceptible to gate blobs, and the present invention is highly effective in molding these resins. Among molded products, the gaps are relatively thin and the area is large, and surface function is important. For example, it is effective for molding injection printed circuit boards.

Furthermore, as mentioned above, thick molded products require sufficient holding pressure with a large gate, so gate cutting 2 is often required.
Direct gate methods and side gate methods that require subsequent processing have been used, but according to the present invention, even the bin point gate method can accommodate molded products with large wall thicknesses, and the secondary processing of gate cutting is not required.

As described above, the present invention is applicable to a wide range of fields and expands the range of applicability of the bin point gate method, and the effects of the present invention are extremely large.

[Brief explanation of the drawing]

FIG. 1 (α) shows one embodiment of the present invention,
FIG. 1(A) is an enlarged view of section C in FIG. 1(α). FIG. 2 is a sectional view taken along line AA in FIG. 1 (α). FIG. 2 Ch) is a diagram showing the relationship between the second sprue and the runner when the rotating body core rotates. Figure 3 shows another embodiment of the present invention.
The figure is a BB sectional view in FIG. 3. FIG. 5 is a sectional view showing a typical example of a pinpoint gate type mold structure according to the prior art. Figure 6, Figure 7, Figure 8,
9 and 10 are enlarged views of the vicinity of the gate of a molded product processed by a conventional pinpoint gate type molding die. Figure 11 shows one of the countermeasures against gatebots using conventional technology.
It is a sectional view showing an example. 1...Rotating body core 2...5# plate 3...2# plate 4...1 #Plate 5...4 #Plate 6...Rack 7...Cylinder 8...Binion 9.・・・・・・Flip 10・・・Runner lock pin 11・・・Runner hook is piece 1 2 ・・・・・・ Shi Noku -13・・・・・・
・Cam plate 14...2# plate holder 15...
・Runner 16...Second sprue 17...Gate 18...Molded product 19...Mold opening regulation piece 20...Rotating body core The rotation center axis 21...
...Second sprue gate center axis 22...Rotating body core holder is plate 23...Gate diameter 24...Runner center axis 24'...Runner center axis 25...・・・・・・Eccentricity 26・・・・・・Phase angle or more Applicant Suzu Co., Ltd. p=9 joint agent Patent attorney Tsutomu Mogami. Figure 1 (b) Figure 2 Figure 3 B Figure 4 Figure 5

Claims (1)

[Claims] In a bin point gate type injection mold, at least the gate hole is eccentrically processed with respect to the center axis of the rotating body so that the rotating body core having the second sprue can freely rotate within the 3# plate. one end of the rotary core constitutes a part of the cavity, the other end forms an injection molding material feeding section, and the rotary core is fitted into the rotor core for gate cutting. An injection mold characterized in that it is configured to have rotation means for rotating the mold.