JPH09141708A - Gate cutting structure of injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gate cutting structure capable of certainly shearing a gate part and capable of performing gate cutting in the same mold only by altering a mold structure. SOLUTION: A second ejector plate 28 is arranged on a movable side and energized in an advance direction by a coil spring 29. A second return pin 30 is fixed to the second ejector plate 28 and the energizing force accumulated in the coil spring 29 is released simultaneously with the opening of a runner part PL to advance the second ejector plate 28. A cutting pin 31 is fixed to the second ejector plate 28 and ejected into a runner 19 along with the gate cutter 31α provided to the end part thereof by the advance of the plate 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate cut structure for cutting, for example, a side gate portion of a molded product molded by injecting a resin from a side gate in an injection molding die.

[0002]

2. Description of the Related Art For example, a side gate molding die is used when a large number of molded products are to be taken. However, after the molded product is taken out of the mold, it is necessary to manually cut the side gate portion with a nipper or the like, resulting in high processing cost.

Therefore, conventionally, various methods for cutting the side gate portion in the molding die have been proposed. For example, in the technique disclosed in Japanese Utility Model Laid-Open No. 59-112626, when the runner portion and the molded product are extruded from the mold, the extruding timings are shifted to relatively separate the two, and the side gate portion is formed. Is to shear.

Further, a method has been proposed in which a pin is pushed into the side gate and the side gate portion is sheared before the resin is solidified.

[0005]

However, in the above-mentioned prior art, the following problems have occurred. Actual opening 5
For example, when the molded product has a thin shape, the resistance when the molded product is separated from the cavity is small. For this reason, even when the runner portion was pushed out, the molded product floated up from the cavity, and the side gate portion could not be sheared.

The latter conventional technique: A dedicated actuator or the like for pushing the pin into the side gate is required irrespective of the mold opening operation, which cannot be dealt with only by changing the mold structure. Therefore, it is necessary to modify the existing equipment such as the mold clamping device, and the cost for performing the above-described in-mold gate cutting becomes high. In addition, the resin in the side gate is pushed into the cavity by pushing the pin, so that the density of the connection portion with the side gate in the molded product becomes high. As a result, problems such as galling on the side surface of the molded product and an increase in residual stress have occurred.

The present invention has been made by paying attention to the problems existing in the above-mentioned prior art, and the purpose thereof is to be able to reliably shear the gate portion and to cut the gate cut in the same mold with a metal. An object of the present invention is to provide a gate cut structure in an injection molding die that can be implemented only by changing the die structure.

[0008]

In order to achieve the above object, in the invention of claim 1, a plate disposed on the movable side and biased to the fixed side by the biasing means, and fixed to the plate, the runner At the same time that the parting line of the part is opened, the accumulated biasing force of the biasing means is released and the plate is advanced to the fixed side; and a return pin fixed to the plate and provided at the end of the plate by advancing the plate. And a cut pin protruding into the runner with a gate cutter.

According to a second aspect of the invention, in the injection molding die, a mold opening control for delaying the opening of the parting line of the molded product portion at the time of opening the mold from the opening of the parting line of the runner portion. A mechanism is provided.

According to the third aspect of the invention, the clearance between the gate cutter and the runner is controlled to the minimum that does not prevent the gate cutter from protruding into the runner. (Operation) In the invention of claim 1 having the above-mentioned structure, the return pin is unlocked by releasing the parting line of the runner portion when the mold is opened, and the accumulated biasing force of the biasing means is released. It Therefore, the plate is advanced to the fixed side, and the cut pin fixed to the plate is projected into the runner by the gate cutter. The protrusion of the gate cutter into the runner pushes the runner portion out of the runner.

Here, in the main molding die, the parting line of the runner part and the parting line of the molded product part can be opened respectively. In other words, it has a three-piece mold configuration. Therefore, when the runner part is pushed out from the inside of the runner to the fixed side by the gate cutter, the movement of the molded product to the fixed side is locked by the parting surface of the molded product part. As a result, the runner portion and the molded product are reliably separated from each other, and the gate portion is sheared.

According to the second aspect of the present invention, the opening of the parting line of the molded product portion at the time of opening the mold is delayed by the opening control mechanism of the mold as compared with the opening of the parting line of the runner portion. Therefore, when the runner portion is extruded by the gate cutter described above, the molded product is held in the cavity.

In the third aspect of the invention, the clearance between the gate cutter and the runner is controlled to a minimum value that does not prevent the gate cutter from protruding into the runner. Therefore, it is excellent in terms of a good balance between the smooth protrusion of the gate cutter into the runner and the shearing of the gate portion without generating burrs on the molded product.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. FIG. 1 is a vertical cross-sectional view showing an injection molding die having a gate cut structure according to this embodiment. The movable side mold plate 11 is fixed to the movable side mounting plate 13 via a spacer block 12. The movable side template 11,
The spacer block 12 and the movable side mounting plate 13 are arranged on the mold clamping device side (not shown).

The runner plate 14 is arranged on the fixed side mounting plate 15. The runner plate 14 and the fixed side mounting plate 15 are arranged on the injection device side (not shown). The fixed mold plate 16 is arranged between the movable mold plate 11 and the runner plate 14.

The cavity 17 is formed between the movable side mold plate 11 and the fixed side mold plate 16. The sprue bush 18 is fixed to the fixed side mounting plate 15. Runner 19
Is formed on the fixed-side template 16, one end of which is connected to the sprue 20 of the sprue bush 18 and the other end of which is connected to the cavity 17 via a side gate 21. Then, the resin is injected into the cavity 1 through the sprue 20, the runner 19 and the side gate 21 by the injection device.
Injected into 7.

The runner lock pin 22 is mounted on the fixed side mounting plate 15
It is fixed to the runner 19 and its front end faces the runner 19. The mold opening control mechanism 23 is disposed over the movable side mold plate 11, the fixed side mold plate 16 and the fixed side mounting plate 15, and when the mold is opened by the mold clamping device, the molded product part PL (parting line) is opened. Is delayed with respect to the opening of the runner part PL.

The first ejector plate 25 is arranged in the spacer block 12. The first ejector plate 25 can be moved forward (moved to the left in the drawing) from the regular position shown in FIG. 1 by an actuator provided in a mold clamping device (not shown). The first return pin 26 is fixed to the first ejector plate 25. When the molded product portion PL is opened, the tip of the first return pin 26 is projected from the parting surface of the movable side mold plate 11 by the advance of the first ejector plate 25 by the actuator. Further, the first return pin 26 is pushed by the fixed-side mold plate 16 when the molded product portion PL is closed, and is moved to a position where its tip end surface is substantially flush with the parting surface. Therefore, the first ejector plate 25 in the forward position is returned to the regular position.

The ejector pin 27 is fixed to the first ejector plate 25. Then, when the molded product portion PL is opened, the ejector pin 27 has its tip portion projected into the cavity 17 by the forward movement of the first ejector plate 25 to release the molded product 101 from the mold.

The second ejector plate 28 as a plate is arranged in the spacer block 12 and is urged by the coil spring 29 as an urging means in a direction of moving forward in the spacer block 12. The second return pin 30 as a return pin is fixed to the second ejector plate 28. The second return pin 30 releases the accumulated biasing force of the coil spring 29 when the runner portion PL is opened. Therefore, the second ejector plate 28 is advanced by the biasing force of the coil spring 29. In addition, when the runner portion PL is closed, the tip of the second return pin 30 is pushed by the runner plate 14, and the tip surface of the second return pin 30 is the runner portion PL.
It is pushed back to a position that is substantially flush with the parting surface of. Therefore, the second ejector plate 28 is returned to the normal position (the state shown in FIG. 1) against the biasing force of the coil spring 29.

The cut pin 31 is fixed to the second ejector plate 28. Same cut pin 3
1 is projected into the runner 19 by the second ejector plate 28, which is advanced in conjunction with the opening of the runner part PL, by the gate cutter 31α formed at its tip. As shown in the enlarged circle of FIG. 2A, the clearance K between the gate cutter 31α and the inlet 19α of the runner 19 is a minimum (for example, the protrusion of the gate cutter 31α into the runner 19). , 1/100 mm ~ 1
/ 1000 mm order).

The molding die of this embodiment is designed to take a large number of molded products 101. Although not shown, the first ejector pins 27 are provided in the same number as the molded products 101. ing. In addition, two molded products 101 are connected to each runner part 103 via side gate parts 102. Therefore, the cut pin 31 is the molded product 10.
Half of the number of 1 is provided.

Next, the operation of the present embodiment will be described.
As shown in FIG. 2A, after the resin is solidified, the mold clamping mechanism is operated to open the mold for the main injection molding mold. Here, as shown in FIG. 2B, the runner portion PL is first opened by the control of the mold opening control mechanism 23. Therefore, the accumulated biasing force of the coil spring 29 is released, and the second ejector plate 28 is advanced from the regular position. Therefore, the cut pin 31 is advanced and the gate cutter 31α is projected into the runner 19.

At this time, the molded product part PL is the mold opening control mechanism 2
Since it is closed by 3, the molded product 101 is in a state of being constrained in the cavity 17. Therefore, the above-described protrusion of the gate cutter 31α into the runner 19 pushes the runner portion 103 in the direction away from the molded product 101. As a result, both 101 and 103 are relatively separated from each other,
The side gate portion 102 is sheared.

Then, the runner portion 103 is pushed out by the cut pin 31, and the runner plate 1
It is released from the runner 19 by the pulling action of the runner lock pin 22 arranged on the fourth side.

After the side gate cut is completed (after a predetermined period is completed), the fixed relationship between the fixed side mold plate 16 and the movable side mold plate 11 is released by the control of the mold opening control mechanism 23, and the molded product portion PL is opened. It Then, the first ejector plate 25 is moved forward by the actuator, the ejector pin 27 is pushed into the cavity 17, and the molded product 10
1 is released.

The present embodiment having the above-described structure has the following effects. (1) The molding die having the above-mentioned configuration is a so-called three-piece construction die. That is, the runner portion PL is opened separately from the molded product portion PL. Accordingly, when the runner portion 103 is pushed out of the runner 19 by the gate cutter 31α, the molded product 101 is brought into contact with the parting surface of the stationary-side mold plate 16 to prevent further movement toward the stationary side. As a result, the runner portion 103 is reliably separated from the molded product 101, and the runner portion 103 and the molded product 101 are reliably sheared by the side gate portion 102.

(2) When the side gate 102 is sheared, the molding part PL is closed by the control of the mold opening control mechanism 23. Therefore, when the runner part 103 is pushed by the gate cutter 31α, the molded product 101 is
The side gate portion 102 of the above (1) is stably sheared while being restrained inside.

(3) The cut pin 31 is fixed to the second ejector plate 28 which is interlocked with the opening and closing of the runner portion PL. Therefore, a dedicated actuator for operating the cut pin 31 in response to opening and closing of the runner portion PL is not required. As a result, it is not necessary to modify the existing mold clamping device, etc. when installing the cut pin configuration,
In-mold gate cutting can be performed at low cost simply by changing the mold configuration.

(4) The clearance K between the gate cutter 31α and the entrance 19α of the runner 19 is controlled to the minimum that does not prevent the gate cutter 31α from smoothly protruding into the runner 19. Therefore, the movement of the cut pin 31 can be made smooth, and at the time of shearing the side gate portion 102 due to the minute clearance K, it is possible to suppress the occurrence of burrs in the molded product 101.

It should be noted that, for example, the side gate 102 of the overlap gate type may be changed to a standard gate or a spoke spider gate according to the shape of the molded product without departing from the spirit of the present invention.

The technical idea that can be understood from the above embodiment will be described. This is a three-piece mold, and with the parting line of the molded part closed, the parting line of the runner part is opened and at the same time, the gate cutter 31α of the cut pin 31 is inserted into the runner 19. A gate cut method in which the runner portion 103 is protruded to protrude.

In this way, the gate 102 can be reliably sheared.

[0034]

According to the invention of claim 1 having the above structure, the gate can be cut surely. Further, since the gate cutting in the mold is possible only by changing the mold structure, the existing equipment can be used as it is and the cost can be reduced.

According to the second aspect of the present invention, when the gate part is pushed by the gate cutter, the molded product can be restrained in the cavity, and the gate part is stably sheared. According to the third aspect of the invention, it is excellent in terms of achieving a smooth protrusion of the gate cutter into the runner and suppressing burr generation of the molded product.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of an injection molding die.

FIG. 2 is a diagram showing a side gate cutting operation,
(A) shows a state where the runner portion PL is closed, and (b) shows a state where the runner portion PL is opened.

[Explanation of symbols]

Reference numeral 19 ... Runner, 28 ... Second ejector plate as plate, 29 ... Coil spring as biasing means, 30 ... Second return pin as return pin,
31 ... Cut pin, 31α ... Gate cutter.

Claims (3)

[Claims] 1. An injection molding die capable of opening a parting line of a runner part and a parting line of a molded product part, wherein the plate is arranged on a movable side and is biased to a fixed side by a biasing means. , A return pin fixed to the plate, which simultaneously releases the parting line of the runner section, releases the accumulated urging force of the urging means, and advances the plate toward the fixed side; A gate cut structure provided with a cut pin that is projected into the runner by a gate cutter provided at an end portion of the forward movement. 2. The mold for injection molding is provided with a mold opening control mechanism for delaying the opening of the parting line of the molded product portion at the time of opening the mold from the opening of the parting line of the runner portion. The gate cut structure according to claim 1. 3. The gate cut structure according to claim 1, wherein the clearance between the gate cutter and the runner is controlled to a minimum so as not to prevent the gate cutter from protruding into the runner.