JPS6194733A - Gateless mold for injection molding - Google Patents

Abstract

PURPOSE:To separate a runner part and a product part through shearing from each other, by a method wherein a gate cutting pin is inserted into a gate part while resin is in a molten state after injection molding and the shearing is performed by a rising part of a mold of the gate part and the gate cutting pin. CONSTITUTION:After the inside of a mold has been filled with plasticized resin, shearing is started by actuating a gate cutting pin 11 and separation through the shearing is completed by inserting the gate cutting pin into a gate part 13. Neither the molten resin remains at all in a sliding part between the gate cutting pin 11 and a rising part of the mold of the gate part 13 nor burrs are generated at all on a product obtained.

Description

[Detailed description of the invention] The present invention relates to a gateless mold for injection molding.

Gateless molds are made by inserting a gate cut pin into the gate part of the mold while the resin in the gate part is in a molten state after the mold is filled with resin to remove the resin in the gate part. By performing shirring and separating the product part from the runner, a high-quality product with a direct gate can be obtained.

Conventionally, gateless gold 1 is manufactured by simply inserting the gate cut pin (1) into the gate part (3) to separate the drying product part (4) and the launch (2), as shown in Figures 1 and 2. This has the drawback that the resin remains on the tip of the gate cut pin, and the resin comes off, causing damage to the molded product.

The present invention provides a gateless mold that has complete gate separation and does not leave any debris on the gate portion of the molded product.

The present invention has a gate cut pin that is inserted into the gate part of a mold while the resin in the gate part is in a molten state after injection molding of plasticized resin, When inserted into the mold, the resin in the first gate part is removed, and shirring is performed between the mold stand-up part of the gate part and the gate cut pin, and the runner part and the product part are separated by shirring, and the gate on the product part side is completely closed. An injection molding gate characterized by being arranged so as to eliminate the
・Less mold.

In the present invention, the gate cut pin inserted into the gate part is usually provided on the fixed side template or the movable side template of the injection mold so that the gate cut pin slides, and this pin is inserted into the gate part. Like the protrusion plate that protrudes the product part, it is fixed to a push-up plate that operates independently of the protrusion plate.

This lift plate is actuated by a hydraulic cylinder or similar drive. Either the hydraulic cylinder is built into the push-up plate part of the mold, or it is installed on the KM type mounting plate to push out the back side of the push-up plate, or the hydraulic cylinder for the ejector of the injection molding machine (the push-up bar for ejection). In this case, a method such as directly poking the back side of the push-up plate is used.

Further, the gate cut pin can be opened (retracted) by driving it with the same hydraulic cylinder or by inserting a spring between the template plate and the push-up plate. It is also possible to use both the extrusion plate and the protrusion plate.

On the other hand, the present invention is characterized by the structure of the gate portion.

That is, the gate part has a shirring separation structure in which when the gate cut pin is inserted into the gate part, the gate cut pin is inserted into the gate part while being shirred by the gate cut pin and the mold rising part of the gate part. It has become.

Specific examples of the present invention are shown below.

3 to 5 show one example, and FIG. 6 shows a molded product obtained in this example (αl is a gate mark). Figure 3 shows the state before the gate cut pin is activated, Figure 4 shows the state where the gate cut pin has started shearing with the mold rising part of the gate part, and Figure 5 shows the gate cut pin after shearing and separation has been completed. Indicates the condition. In this example, gate part a
3 continues with the product part (14) and extends downward in the same direction of operation of the gate cut pin 0, communicating with the launch aX6. The gate cut pin (lυ is a square or cylindrical column, and the tip inserted into the gate part has a cross section that matches the cross section of the gate part.) The gate cut pin starts operating from the state shown in Figure 3, and
The gate cut pin starts shearing in the state shown in the figure,
As shown in FIG. 5, it is further inserted into the gate portion to complete the shearing separation.

7 to 9 show other examples, and FIG. 10 shows a molded product obtained in this example. Figure 7 shows the state before the gate cut pin is activated, Figure 8 shows the state where the gate cut pin has started shearing while being inserted into the gate, and Figure 9 shows the state where the gate cut pin has completed shearing separation. . It extends below and communicates with the runner mouth. The gate cut pin 23) is a prismatic or cylindrical column, and the shape of the tip is the gate part (end) into which the gate cut pin is inserted and the product part 124).Shirring of the gate part is started in the state shown in Fig. 8, and then the shearing of the gate part is started in the state shown in Fig. 9. It is inserted into the gate part until it reaches , and the shearing separation is completed.

Next, another example will be shown. Figure 10 is a modification of the case in Figure 3, in which the nested wire is sheared to form the gate part.
＋餞 Δ−Rumor 也 1 FIG. 11 is another modification of FIG. 3, in which a plate-shaped gate cut pin (5) is used.

The gateless mold of the present invention reliably separates the molded product and the launch, and does not generate any flakes. In conventional gateless molds, the separation of the product part and launch by gate cutting is compression separation, whereas the gateless mold of the present invention uses shirring separation, in which the gate part is cut off at one end and the gate cut pin is further removed. Since the gate part is inserted, there is no molten resin left in the sliding part between the gate cut pin and the mold rising part of the gate part, and the resulting molded product does not have any flakes. .

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of conventional gate molds. Figures 3 to 5, Figures 7 to 9, Figures 11 and 12 are schematic cross-sectional views of the gateless mold of the present invention. -t ☆)H Sobutton M star) is an AA or BB sectional view. 1.11.21.27: Gate cut pin 2.12.2
2: Runner 3.13.23: Gate section 4.14.24: Product section

Claims (1)

[Claims] After injection molding of plasticized resin, the gate cut pin is inserted into the gate part of the mold while the resin in the gate part is in a molten state, and the gate cut pin is inserted into the gate part. Sometimes, while removing the resin in the gate part, shirring is performed between the mold rising part of the gate part and the gate cut pin, and the runner part and the product part are separated by shirring, and the gate on the product part side is completely eliminated. Gateless mold for injection molding.