JPH05104591A - Gate cutter in injection molding die - Google Patents

Abstract

PURPOSE:To provide a gate cutter also ejecting a molded form by a gate cut pin in the perforated molded form. CONSTITUTION:A slidable gate cutter with a gate end section 31 forming a gate G together with a sprue bush 20 while being positioned in the sprue bush 20 at the position of the hole of a molded form, a gate cut section 32 formed continuously in size larger than the end section 31, and a discharging section 33 continued to the gate cut section 32 and formed in size larger than the hole is used as a gate cutter S in an injection molding die. The gate cutter S is composed of structure, in which a gate is cut by the gate cut section 32 after injection while the cut-pin tip section 31 is abutted against an engaging surface 20b as the base of the sprue bush 20, and a fixed quantity of the discharging section is projected to the outside of the mold after the mold is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus, and more particularly to a gate cutting apparatus for performing gate cutting and projecting a molded product.

[0002]

2. Description of the Related Art Conventionally, in an injection molding device, a gate cutting device for gate cutting and a molding product ejecting device using an ejector pin or the like for ejecting a molding product have been formed separately.

That is, FIG. 5 shows a conventional technique.
As shown in FIG. 5, the injection compression molding die 50 includes a movable die 5
1, a fixed mold 52, and a cavity 53, and the spool projection 56 is provided inside the cut pin 57.
Is configured to be slidable by the hydraulic device 56a.
Further, at this time, the gate cut pin 57 is also slidably arranged and operated by the hydraulic ejector of the molding machine. An ejector pin 58 for projecting a product is slidably arranged on the outer periphery of the gate cut pin 57.

[0004]

According to the above-mentioned prior art, the gate cut pin 57 and the ejector pin 58 for ejecting the molded product are separate and not only need to be operated separately. However, there is a problem that the number of parts is large, the number of man-hours for processing and assembling parts is large, and it takes time to assemble the mold. Further, it is necessary to operate the ejector pin 58 for ejecting the product after operating the gate cut pin 57, which requires an operating device for ejecting the product.

An object of the present invention is to provide a gate cut device which can eject a product from a molded product having a hole by means of a gate cut pin.

[0006]

SUMMARY OF THE INVENTION A gate cutting device for an injection molding die according to the present invention is a gate end for forming a gate together with a sprue bush at the position of a hole of a molded product and inside the sprue bush. A slidable gate cutting device comprising: a gate cutting portion formed continuously larger than an end portion thereof; and a discharge portion formed continuously larger than the hole, the discharging portion being larger than the hole. This gate cutting device has a structure in which the gate is cut by the gate cutting portion after injection, the tip end of the cutting pin is in contact with the bottom surface of the sprue bush, and after the mold is opened, the discharging portion is projected to the outside of the mold by a predetermined amount.

[0007]

The gate cutting device according to the present invention, after injection,
When the cut pin is advanced and the gate is cut by the gate cut portion, the tip end of the cut pin contacts the bottom surface of the sprue bush and the stroke is restricted. further,
After the mold is opened, the discharge part, which is continuously formed in the gate cut part and is larger than the hole of the molded product, moves to the outside of the mold by a predetermined amount to eject the molded product.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The members, arrangements, etc. described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention. The present invention will be described below based on an example in which it is applied to an injection molding apparatus for a substrate for an optical disc such as a compact disc or a video disc having a hole formed in the central portion.

FIG. 1 is a sectional view of an essential part of an injection molding machine die according to the present invention in an injection state. It has a fixed die 1 and a movable die 2, and the fixed die 1 is mounted on a fixed plate 5. It is fixed, and the movable mold is fixed to a movable plate (not shown). Each of the molds 1 and 2 has mirror plates 3 and 4 on the opposite surface sides,
A cavity 10 is formed by these mirror plates 3 and 4.

Further, the fixed mold 1 of the present embodiment is provided with a sprue bush 20 in a state of penetrating through the center of the fixed plate 5, the mold body 6 and the mirror surface plate 3. The sprue bush 20 is arranged coaxially with a gate cutting device S, which will be described later, and the base end (fixed plate 5 side) thereof is fixed to the fixed plate 5.

The cavity 10 side of the sprue bush 20 of this embodiment has an opening 20a. Opening 2 of this example
Reference numeral 0a is a circular concave portion opened to the cavity 10 side, and an engagement surface 20b which is an opening bottom surface of the sprue bush 20 is formed on the injection molding machine nozzle (not shown) side of the opening portion 20a. There is.

The mold bodies 6 and 7 of this example have circular recesses 6a and 7a concentrically in the portions facing each other, and the portions of the recesses 6a and 7a located at the peripheral edges of the openings are annular planes. 6
b and 7b, the annular flat surfaces 6b and 7b are opposed to each other in the fixed mold 1 and the movable mold 2. Further, in the movable mold 2, a center fixing sleeve 11 is embedded in the center of the side facing the fixed mold 1, and the center of the stamper (not shown) is inserted into the center fixing sleeve 11. By inserting the stamper, the stamper is attached to the mirror surface plate 4. A gate cutting device S is arranged so as to penetrate the movable mold 2 while being slidably fitted to the inner peripheral surface of the central portion fixing sleeve 11.

The gate cutting device S of this embodiment comprises a tip portion 31 of the gate cutting pin 30, a gate cutting portion 32, and a discharging portion 33. The discharging portion 33 is provided on the cavity 10 side of the cutting pin 30. A gate cut portion 32 and a cut pin tip portion 31 are formed, and the other end side is connected to a molding machine hydraulic device 34 so as to be slidable.

The tip portion 31 of the cut pin of this embodiment is located in the opening 20a of the sprue bush 20 and forms the gate G together with the opening 20a of the sprue bush 20. The width of the gate G in this example is about 0.4 mm.

The gate cut portion 32 of the present example is formed continuously larger than the tip portion 31 of the cut pin 30, and is adapted to fit within the width of the opening 20a of the sprue bush 20. That is, as described above, the gate G is 0.4
In the case of mm, the distance between the edge portion of the gate cut portion 32 of the cut pin 30 and the edge portion of the opening portion 20a of the spool bush 20 is set to 0.4 mm as the gate G. In order to form, it protrudes in the cavity 10 in the shape of a core pin.

The discharge end portion 33 of this example is the gate cut portion 3
2 is formed continuously and larger than the hole of the molded product. This discharge part 33 has the same function as a conventional product ejector, and can project to the cavity 10 side with a predetermined dimension. After the mold is opened, it projects to the cavity 10 side to release the molded product from the mold. To do.

The gate cut hydraulic device 34 of this embodiment can be a normal hydraulic device of an injection molding machine, and the stroke when the mold is closed is the tip 3 of the cut pin 30.
1 and the engaging surface 20 which is the opening bottom of the sprue bush 20
When the die is open, the tip is not limited when the die is open, so it is possible to slide until it is limited by the piston end surface of the cut pin 30, and the molded product can be released from the mold. Become.

The mold of this example has a plate thickness adjusting mechanism 14
Is provided on the outer periphery of the fixed mold body 6. The plate thickness adjusting mechanism 14 of the present example is configured to include an outer peripheral holder 15 that comes into contact with the stamper and a plurality of coil springs 16. The outer peripheral holder 15 has an annular shape, and the fixed mirror surface plate 3 is fixed. It is fitted on the outer circumference. A plurality of spring accommodating holes 17 are concentrically formed in a portion of the mold body 6 on the fixed side corresponding to the position where the outer peripheral holder 15 is provided. A part of the coil spring 16 is housed in the spring housing hole 17. On the other hand, one end of the coil spring 16 contacts the end surface of the outer peripheral holder 15 on the mold body 6 side to press the outer peripheral holder 15 in the movable mold 2 direction. Also,
An annular notch 18 is formed on the outer peripheral surface of the mirror surface plate 3 from the end surface on the mold body 6 side, and a bearing 19 is housed in this notch 18 to facilitate movement of the outer peripheral holder 15.

The end face of the outer peripheral holder 15 on the stamper side is an annular flat surface 15a. The annular flat surface 15a receives the pressing force of the coil spring 16 and abuts against the peripheral edge of the stamper to move the stamper. I try to keep it on the mirror surface.

Next, the operation in the case of injection molding with the above construction will be described. First, the movable mold 2 is pressed toward the fixed mold 1 by a compression cylinder (not shown) or the like. Then, the movable mold 2 moves toward the fixed mold 1 until the annular flat surfaces 6b and 7b come into contact with each other.

On the other hand, when the fixed mold 1 and the movable mold 2 are sufficiently separated from each other, the outer peripheral holder 15 is projected from the fixed mirror surface 3a by the elastic force of the coil spring 16. ing. Then, the fixed mold 1 of the movable mold 2
As the movement in the direction progresses, the outer peripheral holder 15 contacts the stamper with the annular flat surface 15a, and thereafter, the outer peripheral holder 15 moves to the mold body 6 side as the movable mold 2 moves to the fixed mold 1. fall back. And, as shown in FIG.
The annular flat surfaces 6b and 7b come into contact with each other, the movable mold 2 stops, and the outer peripheral holder 15 also stops moving backward.

When the so-called mold matching of the fixed mold 1 and the movable mold 2 is completed as described above, the sprue bush 20 is inserted into the cavity 10 formed between the stamper and the fixed mirror plate 3. The resin material 9 is injected with a predetermined resin pressure, and the movable mold 2 is retracted with the resin pressure. When the amount of retreat reaches a desired value, the injection is stopped, and at the same time, the hydraulic device 34 is operated to operate the cut pin 30.
The tip end portion 31 of is moved into the opening portion 20a of the sprue bush 20 to stop the molten resin. FIG. 3 shows the state at this time, and the movement of the cut pin 30 is stopped by the cut pin tip 31 contacting the engagement surface 20b. At this point, the operation of the hydraulic device 34 is stopped,
The movement of the cut pin 30 is stopped, but the movement amount is X in FIG.
The movement amount is 1. Then, the mold clamping force is increased (compression operation), and as the molded product shrinks due to cooling, the movable mold 2 again
Moves toward the fixed mold 1 and stops at the position of the desired plate thickness of the molded product. When the resin is filled in the cavity 10, the injection pressure of the resin into the cavity 10 is
Although the pressure in the mold opening direction (pressure to the movable mold 2 side) is large, the pressure in the lateral direction of the outer peripheral holder 15 (vertical pressure in FIG. 1) is sufficient compared to the pressure in the mold opening direction. Since it is small, the urging force of the outer peripheral holder 15 is sufficient.

Immediately after the compression operation is completed, or after a certain cooling period, the molds 1 and 2 are opened by a predetermined amount from the state shown in FIG. 1. Also, the outer circumference holder 15 projects in the direction of the movable mold 2 as the movable mold 2 is separated while being in contact with the stamper.

After the mold opening is completed, the hydraulic pin 34 is operated again to move the cut pin 30 into the cavity 10.
Move to the side. The movement amount of the cut pin 30 is shown in FIG.
It is limited to the movement amount of X shown by. FIG. 4 shows a state in which the cut pin 30 is moved to the maximum, and in this state, the molded product is taken out of the mold. In addition, in the above-described embodiment, the example in which the plate pressure adjusting mechanism 14 is provided is shown, but in the present invention, mold closing-high pressure mold clamping-injection (injection of molten resin into the cavity) -gate cut-cooling-mold opening. Needless to say, it can be applied to the general molding process of a molded product with holes, such as product removal.

[0025]

As described above, according to the present invention, the conventional ejector device for ejecting a molded product is unnecessary, and the operations of the gate cut and the ejector pin for ejecting the molded product are separately performed. You do n’t have to
The number of parts can be reduced, and the time for processing and assembling parts can be shortened. Further, the malfunction of the protruding piston of the molded product, which has been problematic in the past, is eliminated.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an injection molding device according to the present invention.

FIG. 2 is an enlarged view of a main part in FIG.

FIG. 3 is a schematic cross-sectional view showing a state in which a gate is cut.

FIG. 4 is a schematic cross-sectional view showing a protruding state of a molded product.

FIG. 5 is a schematic cross-sectional view showing a conventional example.

[Explanation of symbols]

 1, 2 Mold 10 Cavity 20 Sprue Bush 20a Opening 20b Engaging surface 30 Cut pin 31 Gate end 32 Gate cut 33 Discharge 34 Hydraulic system G Gate S Gate cut device

Claims (1)

[Claims] 1. An injection-molding die for injection-molding a molded article having a hole, wherein a gate is provided together with a sprue bush at a position of the hole of the molded article and within a sprue bush of the injection-molding die. A slidable gate provided with a gate end portion to be formed, a gate cut portion formed continuously larger than the end portion, and a discharge portion formed continuously from the gate cut portion and larger than the hole. It consists of a cutting device, the gate cutting device performs gate cutting by the gate cutting part after injection, and the tip of the cutting pin contacts the bottom part of the sprue bushing, the stroke is restricted, and the discharging part is moved out of the mold after the mold is opened. A gate cutting device in an injection molding device, which is characterized by moving a predetermined amount.