JPH09239770A - Method and apparatus for producing injection-molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce a plurality of injection-molded products by changing over the resin passages connected to respective cavities during one injection operation of an injection molding means and successively performing the injection of a resin at every predetermined cavities. SOLUTION: When the completion of the injection of a resin into a cavity C1 and the completion of the filling of the cavity C1 with a resin are grasped by a control unit 40, the injection operation of an injection molding means 20 is temporarily stopped and the passage changeover means 30a on the side of the cavity C1 is closed and the passage changeover means 30b on the side of a cavity C2 is opened. Continuously, the injection operation of the injection molding means 20 is resumed and a resin is injected into the other cavity C2 according to the optimum injection molding condition in the preset cavity C2. When the injection and filling of the resin to the cavity C2 are completed, a mold 10 is opened to take out an injection-molded product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for manufacturing injection-molded products, and more particularly to a method for manufacturing a plurality of injection-molded products in one mold closing cycle using a mold having a plurality of cavities having different shapes. And equipment.

[0002]

2. Description of the Related Art Conventionally, an injection molding die having two or more cavities and an injection molding machine have been used to simultaneously manufacture a plurality of injection molded products in one mold closing cycle of the die. It is being appreciated.

[0003]

However, in the prior art, since resin is simultaneously injected into all of a plurality of cavities by one injection operation of an injection molding machine, when products of different kinds and sizes are set, That is, when the sizes and shapes of the cavities are different, quality defects such as short shots may occur due to differences in product thickness and shapes.

In order to prevent the occurrence of such quality defects, injection conditions such as speed and pressure are set in multiple stages at the time of injection. However, since the resin is injected into all the cavities at the same time, individual injection is performed. It was difficult to set the best condition for the cavity, and the setting was complicated.

Therefore, the present invention provides a method and apparatus capable of injecting and filling a resin into each cavity under the most desirable conditions in the cavity and stably producing a plurality of injection molded products. It is intended to be provided.

[0006]

In order to achieve the above object, a method of manufacturing an injection molded product according to the present invention uses a mold having a plurality of cavities to manufacture a plurality of injection molded products in one mold closing cycle. In this case, the injection operation of the injection molding means is temporarily determined by switching the resin flow path connected to each cavity during one injection operation of the injection molding means or during the one injection operation of the injection molding means. By stopping the number of times and switching the resin flow path connected to each cavity during the suspension of the injection operation,
It is characterized in that a plurality of injection-molded products are obtained by sequentially injecting resin for each predetermined cavity.

Further, the apparatus for manufacturing an injection-molded article according to the present invention is
A resin flow passage switching means capable of sequentially switching the resin flow passages connected to the plurality of cavities is provided, and in addition to the resin flow passage switching means, an injection operation capable of temporarily stopping the injection operation at a predetermined position. It is characterized in that it is provided with a molding means.

Further, according to the present invention, as the injection molding means, one which can set different injection molding conditions in advance for each injection operation into a predetermined cavity is used, and different injection molding conditions are set in advance for each predetermined cavity. In addition, after detecting the injection operation data to the predetermined cavity and grasping the injection of the resin into the cavity and the completion of the resin filling into the cavity, the resin flow by the flow path switching means is detected. It is characterized in that the path is switched and the injection operation of the injection molding means is temporarily stopped.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of an injection-molded article manufacturing apparatus of the present invention, FIGS. 2 to 7 are explanatory views showing an example of the form of flow path switching means, and FIG. 8 is an example of a condition setting pattern of injection molding conditions. FIGS. 9 to 12 are explanatory views showing an example of arrangement of the cavity and the flow path switching means.

First, as shown in FIG. 1, this injection molded article manufacturing apparatus comprises a mold 10 having a plurality of cavities C1 and C2, and an injection molding means 20 for injecting a resin into the mold 10. Flow path switching means 30a provided in the mold 10,
And 30b.

The mold 10 comprises a fixed mold 11 and a movable mold 12 which form cavities C1 and C2. The mold 10 has a sprue S connected to an injection molding means 20.
And the gate G of each cavity branched from the sprue S
And a flow path switching means 30a, 30b provided in the middle of the runner R.

The injection molding means 20 has a screw 22 arranged in a cylinder 21 so that it can be moved forward and backward, a hydraulic unit 23 for moving the screw 22 forward and backward, and a cylinder, as in a known injection molding machine. 21 includes a hopper 24 for supplying resin and a heater 25 for heating the cylinder 21.
Resin is injected into the mold 10 from the nozzle 26 at the tip of the.

A control device 40 for controlling these operations is connected to the hydraulic unit 23 and the flow path switching means 30a and 30b. The control device 40 includes injection molding conditions such as injection pressure, holding pressure, injection speed, speed switching position, pressure switching position, injection time, pressure holding time, temporary stop position, and flow path switching means 30a in the injection operation.
The switching timing of 30b is set in advance, and injection operation data such as time, screw position, pressure change, speed change, and cavity internal pressure are input as detection values.

For example, as shown in FIG. 2, the flow path switching means 30a and 30b are provided with a cock 31 having a resin flow path 31a in the middle of a runner R, and the cock 31 is rotated by a predetermined angle. As a result, the resin flow path of the runner R is opened and closed, and as shown in FIG. 3, a retractable shield member 32 is disposed in the middle of the runner R.
Of the type in which the resin flow path of the runner R is opened and closed by moving the runner R, as shown in FIG. 4, a heating part 33 is provided in the middle of the runner R, and when the heating part 33 is in a non-operating state, Of a type in which the resin is cooled and solidified to close the resin flow path, and the heating unit 33 is operated to heat the resin in the runner R, thereby giving fluidity to the resin and allowing the resin to flow. As shown in FIG. 5, a passage 34a formed in the middle of the runner R or in the gate portion of the cavity can be opened and closed by a rod-shaped heater 34, and the heater 34 is operated to heat and melt the surrounding resin and retreat the heater 34. Of the type that allows the passage 34a to open, and as shown in FIG.
A top 35 having a resin flow path 35a is rotatably provided around a portion or the like, and the top 35 is rotated to rotate the resin flow path 35a.
Suitable for the structure of the mold 10, the length and thickness of the runner R, the installation position of the flow path switching means, the injection pressure, etc., such as the type of switching the runner R1 or R2 in any direction. As shown in FIG. 7, the nozzle 26 of the injection molding means 20 is branched so as to correspond to the predetermined cavities C1 and C2, and the branched portions 26a,
The flow path switching means 30a and 30b may be provided in 26b, respectively. Any drive means such as hydraulic pressure, pneumatic pressure, and electric drive may be used as the drive means for these flow path switching means.

Next, a procedure for producing a plurality of injection-molded products in one mold closing cycle using the mold 10 having the two cavities C1 and C2 will be described. First, as shown in FIG.
In the single injection molding process CT, the first stage T after mold closing
1, the flow path switching means 30a on the cavity C1 side is opened,
The flow path switching means 30b on the side of the cavity C2 is closed, and the injection molding means 20 is operated according to the optimum injection molding condition (for example, pressure / speed) in the cavity C1 set in advance to inject the resin into one cavity C1. .

At this time, by selecting a cavity of a thick product which requires a long cooling time as the cavity C1 for injection first, it is possible to achieve a balance in one mold closing cycle and efficiently perform injection molding. It can be carried out.

Then, the controller 40 controls the injection of the resin into the cavity C1 and the completion of the filling of the resin into the cavity C1.
Then, in the second stage T2, the injection operation of the injection molding means 20 is temporarily stopped, the flow path switching means 30a on the cavity C1 side is closed, and the flow path switching means 30b on the cavity C2 side is switched to open.

Then, in the third step T3, the injection operation of the injection molding means 20 is restarted, and the resin is injected into the other cavity C2 according to the preset optimum injection molding conditions in the cavity C2. When the injection and the filling of the resin into the cavity C2 are completed, the injection molding means 20 measures the resin for the next injection operation at the fourth step T4, and the mold 10 is opened to take out the injection molded product.
The time of the fourth step T4 can be appropriately set according to the cooling time of the injection-molded product, the time required for measuring the injection-molding means 20, and the like.

In this way, the predetermined cavities C1 and C2 are
By sequentially injecting the resin for each to manufacture a plurality of injection-molded products, it is possible to reliably fill the resin into each of the cavities C1 and C2 and prevent the occurrence of quality defects such as short shots. it can.

Furthermore, by setting the optimum injection molding conditions for each of the cavities C1 and C2, a high quality product can be stably manufactured. Further, by detecting the injection operation data of the cavity C1 in which the injection molding is performed first, the injection operation can be temporarily stopped or the flow path can be switched at a timely timing, so that defective products can be prevented from occurring and production efficiency can be improved. It can be improved.

Further, by selecting an appropriate flow path switching means, the resin flow paths can be switched without stopping the injection operation of the injection molding means 20, and the resin can be sequentially injected into each predetermined cavity. Is.

The relationship between the number of cavities and the flow path switching means is not limited to the two flow path switching means 30a and 30b provided for the two cavities C1 and C2 as described above. As shown in FIG. 9, three flow path switching means 30 are provided for the three cavities C1, C2, C3.
a, 30b, 30c are provided respectively, and injection molding means 20 is provided.
It is also possible to suspend the injection twice in the middle and inject in three stages. As shown in FIG. 10, the three cavities C1 and C
Two of the cavities C1 and C2 of the two C2 and C3 are provided as a set and two flow path switching means 30a and 30b are provided, and three injection molded products are obtained in two stages of the cavities C1 and C2 and the cavity C3. You may do it.

Further, as shown in FIG. 11, four flow path switching means 30a, 30b, 30c, 30d are provided corresponding to the four cavities C1, C2, C3, C4, respectively, thereby providing four steps. Injection may be performed with
As shown in 2, a set of two cavities C1 and C2,
The cavities C3 and C4 may be set as one set, and the flow path switching means 30a and 30b may be provided for each set. further,
In the case of having four cavities, two cavities are set as one set and the other two cavities are made independent, and three flow path switching means are provided, or three cavities are set as one set. There is also a mode in which individual cavities are made independent, and an appropriate mode can be selected according to the product type, size, and the like. Similarly, even in a mold having five or more cavities, the relationship between each cavity and the flow path switching means can be set in an optimal state.

[0024]

As described above, according to the present invention, since the resin is sequentially and repeatedly injected into a plurality of cavities in the mold, it is possible to prevent the occurrence of quality defects such as short shots. In addition, by setting the optimum injection molding conditions for each cavity, quality can be stabilized, quality defects can be more reliably prevented, and even when products with significant differences in wall thickness, shape, etc. are set. It is possible to stably manufacture high quality injection molded products.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an injection-molded article manufacturing apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a form example of a flow path switching unit.

FIG. 3 is an explanatory view showing another embodiment of the flow path switching means.

FIG. 4 is an explanatory view showing another embodiment of the flow path switching means.

FIG. 5 is an explanatory view showing another embodiment of the flow path switching means.

FIG. 6 is an explanatory view showing another embodiment of the flow path switching means.

FIG. 7 is an explanatory view showing another embodiment of the flow path switching means.

FIG. 8 is a diagram showing an example of a condition setting pattern of injection molding conditions.

FIG. 9 is an explanatory diagram showing an arrangement example of cavities and flow path switching means.

FIG. 10 is an explanatory view showing another arrangement example of the cavity and the flow path switching means.

FIG. 11 is an explanatory view showing another arrangement example of the cavity and the flow path switching means.

FIG. 12 is an explanatory view showing another arrangement example of the cavity and the flow path switching means.

[Explanation of symbols]

10 ... Mold, 20 ... Injection molding means, 21 ... Cylinder,
22 ... Screw, 23 ... Hydraulic unit, 30a, 30
b ... flow path switching means, 40 ... control device, C1, C2 ... cavity, R ... runner

Claims (9)

[Claims] 1. When manufacturing a plurality of injection-molded articles in a mold closing cycle using a mold having a plurality of cavities, a resin flow path connected to each cavity is formed during one injection operation of the injection molding means. A method for manufacturing an injection-molded product, characterized in that a plurality of injection-molded products are obtained by switching and sequentially injecting a resin for each predetermined cavity. 2. When manufacturing a plurality of injection-molded articles in a mold closing cycle using a mold having a plurality of cavities, the injection operation of the injection-molding means is temporarily performed during one injection operation of the injection-molding means. A plurality of injection-molded products by stopping the resin a predetermined number of times and switching the resin flow paths connected to the respective cavities during the temporary suspension of the injection operation, and sequentially injecting the resin into each of the predetermined cavities. And a method of manufacturing an injection-molded article. 3. The method for manufacturing an injection-molded article according to claim 1, wherein different injection molding conditions are set in advance for each of the predetermined cavities. 4. The resin flow path is switched after detecting the injection operation data into the predetermined cavity and grasping the injection of the resin into the cavity and the completion of the filling of the resin into the cavity. The method for producing an injection-molded article according to claim 1, which is characterized in that. 5. An apparatus for manufacturing a plurality of injection-molded articles in a single mold closing cycle using a mold having a plurality of cavities, wherein resin flow paths connected to the plurality of cavities from an injection molding means are sequentially formed. An apparatus for manufacturing an injection-molded article, comprising a flow path switching means that can be switched. 6. An apparatus for manufacturing a plurality of injection-molded articles in a single mold closing cycle using a mold having a plurality of cavities, the injection-molding means capable of temporarily stopping an injection operation at a predetermined position, and the plurality of injection-molding means. And a flow path switching means capable of sequentially switching the resin flow paths connected to the cavities. 7. The apparatus for manufacturing an injection-molded article according to claim 5, wherein the injection-molding means can set different injection-molding conditions in advance for each injection operation into a predetermined cavity. . 8. The flow path switching means performs the flow path switching operation based on operation data obtained by detecting the injection of resin into a predetermined cavity and the filling state of the resin into the cavity. 5. An apparatus for manufacturing an injection-molded article according to item 5. 9. The injection molding means temporarily suspends the injection operation based on operation data obtained by detecting the injection of resin into a predetermined cavity and the filling state of resin into the cavity,
The apparatus for manufacturing an injection-molded article according to claim 6, wherein the flow path switching means performs a flow path switching operation when the injection molding means is temporarily stopped.