JP7388866B2 - Injection molding machine - Google Patents

Description

The present invention relates to an injection molding machine that injects a resin material into a mold cavity to form a molded product.

A conventional injection molding machine is disclosed in Patent Document 1. The injection molding machine disclosed in Patent Document 1 has a screw arranged in a heating cylinder so as to be rotatable and movable back and forth. The injection molding machine plasticizes the resin material supplied to the rear end of the screw and transfers it forward, and stores the plasticized resin material at the front end of the screw. The injection molding machine moves a screw forward to inject plasticized resin material into a mold cavity. Then, the injection molding machine applies a holding force from the screw to the resin material in the cavity via the resin material called a cushion amount remaining on the tip side of the screw.

In such an injection molding machine, the quality of a molded product is sometimes determined based on the amount of cushioning. For example, if the amount of cushioning is small, burrs may occur on the product due to resin material leaking outside the cavity, or a large amount of resin material may fill into the cavity due to missing insert parts in insert molding. It is possible that it has been done. In this case, the molded product is determined to be defective, and after the molded product is removed from the mold, it is rejected as a defective product.

JP2008-307857A

However, for example, if the cavity is not sufficiently filled with resin material, the contact area between the mold and the resin material will be small, so heat exchange with the mold will not take place properly, and the resin material will not be cooled properly. Sometimes enough is enough. Furthermore, if the cavity is filled with a large amount of resin material, it takes a long time to cool down the resin material, which may result in insufficient cooling of the resin material. Therefore, when the mold was opened, the molded product sometimes stuck to the mold other than the mold from which the molded product was taken out by the automatic machine. As a result, it is necessary to temporarily stop the molding operation and remove the molded product, which may reduce the production efficiency of the molded product.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an injection molding machine that can effectively suppress a decrease in production efficiency of molded products.

In order to achieve the above object, an injection molding machine according to one aspect of the present invention includes a fixed die plate to which a fixed die is attached, a movable die plate to which a movable die is attached, and a fixed die plate to which a movable die is attached. an injection device that injects a resin material into a cavity formed by the movable side mold; and an injection device that injects a resin material into the cavity; a control device that controls the injection device to perform a pressure holding operation that applies a holding force; the control device cools the resin material in the cavity based on the amount of cushion acquired in the pressure holding operation; It is characterized by being configured to change the setting of the cooling time used in the cooling operation.

In the present invention, the control device sets the first cooling time as the cooling time when the cushion amount is greater than or equal to a reference value, and sets the first cooling time as the cooling time when the cushion amount is smaller than the reference value. It is preferable to set a longer second cooling time.

According to the present invention, the setting of the cooling time for cooling the resin material in the cavity is changed based on the amount of cushioning acquired in the pressure holding operation. By doing this, for example, if there is an abnormality in the amount of cushioning, the cooling time can be set so that the molded product remains in the mold from which the molded product is taken out by the automatic machine when the mold is opened. Therefore, there is no need to temporarily stop the molding operation, and it is possible to effectively suppress a decrease in production efficiency of molded products.

1 is a front view of an injection molding machine and an automatic machine according to an embodiment of the present invention. 2 is a plan view of the injection molding machine and automatic machine of FIG. 1. FIG. 2 is a diagram illustrating functional blocks and a storage device of the injection molding machine of FIG. 1. FIG. 2 is a sequence diagram illustrating an example of the operation of the injection molding machine of FIG. 1. FIG.

An injection molding machine according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1 and 2 are a front view and a plan view of an injection molding machine and an automatic machine according to an embodiment of the present invention. FIG. 3(a) is a diagram illustrating functional blocks of the injection molding machine of FIG. 1. FIG. 3(b) is a diagram illustrating a storage device included in the control device of the injection molding machine shown in FIG. FIG. 4 is a sequence diagram illustrating an example of the operation of the injection molding machine of FIG. 1.

The injection molding machine 1 of this embodiment injects and fills a plasticized resin material into a cavity 84 formed by an upper mold 81 and a lower mold 82, and cools and solidifies the resin material and insert parts. This is a method of molding (insert molding) a molded product in which the two are integrated. The injection molding machine 1 may mold a molded product made only of resin material. Note that this embodiment shows an example of a configuration in which the present invention is applied to an injection molding machine that opens and closes an upper mold 81 and a lower mold 82 in the vertical direction. In addition to this, the injection molding machine has a fixed die plate to which a fixed die is attached and a movable die plate to which a movable die is attached, and which opens and closes the fixed die and movable die in the horizontal direction. The present invention may also be applied.

As shown in FIGS. 1 to 3, the injection molding machine 1 includes a mold clamping device 10 that clamps an upper mold 81 and a lower mold 82, an injection device 20 that injects a resin material into a cavity 84, and a mold. It has a control device 30 that controls the tightening device 10 and the injection device 20. The injection molding machine 1 operates in cooperation with an automatic machine 50 consisting of, for example, a six-axis articulated robot. The automatic machine 50 takes out the molded product from the lower mold 82 and installs the insert part K in the lower mold 82 at a molded product take-out station P2, which will be described later. The injection molding machine 1 and the automatic machine 50 constitute an injection molding system. The lower mold 82 is provided with an ejector mechanism (not shown) that projects an ejector pin into the cavity 84 and extrudes the molded product from the cavity 84. The lower mold 82 is a mold in which the molded product remains when the mold is opened, and is a take-out mold from which the molded product is taken out.

The mold clamping device 10 includes a rotary table 11 and a movable die plate 12 arranged vertically facing the rotary table 11. The mold clamping device 10 also includes a rotary drive mechanism 13 that drives the rotary table 11 to rotate clockwise intermittently by a predetermined angle, and an upper mold 81 and a lower mold 82 by the rotary table 11 and the movable die plate 12. The mold clamping drive mechanism 14 generates mold clamping force by clamping the mold in the vertical direction. The rotary table 11 corresponds to a fixed die plate. The upper mold 81 corresponds to a movable mold, and the lower mold 82 corresponds to a fixed mold.

Two lower molds 82 are attached to the upper surface 11a of the rotary table 11 at intervals of 180 degrees. Note that three or more lower molds 82 may be attached to the upper surface 11a of the rotary table 11. The two lower molds 82 are positioned at two work stations: an injection station P1 and a molded article removal station P2. An upper mold 81 is attached to the lower surface of the movable die plate 12.

The injection station P1 is an injection position where the upper mold 81 and the lower mold 82 are clamped and a plasticized resin material is injected into the cavity 84. Further, at the injection station P1, a predetermined pressure (holding force) is applied to the resin material in the cavity 84, and a cooling time C is set so that the resin material is cooled. The molded product take-out station P2 is located at the 6 o'clock position when the injection station P1 is set to the 0 o'clock position, and is a molded product take-out position for taking out the molded product from the lower mold 82. The molded product removal station P2 is also a component installation position where the insert component K is installed in the lower mold 82.

The injection device 20 is arranged so as to be movable horizontally relative to the mold clamping device 10. The injection device 20 includes a heating cylinder 21 and a screw (not shown) accommodated in the heating cylinder 21. The injection device 20 touches the nozzle 21a of the heating cylinder 21 to the lower mold 82 (or upper mold 81) in the injection station P1, advances the screw, and injects the plasticized resin material into the cavity 84 ( injection operation). Further, after injecting the resin material into the cavity 84, the injection device 20 pushes the screw forward to apply a holding force to the resin material in the cavity 84 (pressure holding operation).

The injection device 20 also includes a position sensor that outputs a signal according to the position of the screw, and detects the position of the screw based on the signal from the position sensor. The injection device 20 detects the position of the screw during the pressure holding operation and obtains the amount of cushioning.

The control device 30 controls the operation of the injection molding machine 1 as a whole. The control device 30 includes a microcomputer. The control device 30 controls the operations of the rotational drive mechanism 13 and the mold clamping drive mechanism 14 of the mold clamping device 10, and various drive mechanisms such as the injection device 20. The control device 30 cooperates with an automatic machine 50.

Specifically, in the molding operation, the control device 30
(1) Controlling the rotational drive mechanism 13 to move the plurality of lower molds 82 installed on the rotary table 11 to the injection station P1 and the molded product removal station P2,
(2) controlling the mold clamping drive mechanism 14 to clamp the upper mold 81 and the lower mold 82 in the injection station P1;
(3) controlling the injection device 20 to inject the plasticized resin material into the cavities 84 of the clamped upper mold 81 and lower mold 82;
(4) controlling the injection device 20 to apply a holding force to the resin material within the cavity 84;
(5) After the cooling time C has elapsed since the completion of holding pressure, the mold clamping drive mechanism 14 is controlled to open the clamped upper mold 81 and lower mold 82.

Further, the control device 30
(6) Receive the table rotation timing signal Sa indicating the timing at which the rotary table 11 can rotate from the automatic machine 50;
(7) A molded product removal timing signal Sb indicating the timing at which the molded product should be taken out from the lower mold 82 in the molded product removal station P2 is transmitted to the automatic machine 50.

In this embodiment, the table rotation timing signal Sa is a signal indicating whether or not the timing is such that the rotary table 11 can rotate based on the voltage level (H level/L level), but is not limited to this. . The table rotation timing signal Sa may be, for example, a message format signal used in a predetermined communication protocol. The molded product take-out timing signal Sb is also similar to the table rotation timing signal Sa.

Further, the control device 30 has a storage device 31 composed of, for example, a nonvolatile memory or a hard disk device. The storage device 31 has a first cooling time storage area 311 and a second cooling time storage area 312.

The first cooling time storage area 311 stores a first cooling time C1 that is set as the cooling time C when it is determined that the molded product is a non-defective product. The second cooling time storage area 312 stores a second cooling time C2 that is set as the cooling time C when it is determined that the molded product is defective. The second cooling time C2 is longer than the first cooling time C1 (C2>C1).

Next, an example of the molding operation in the injection molding machine 1 of this embodiment described above will be described with reference to FIG. 4.

First, the automatic machine 50 installs the insert part K in the lower mold 82 at the molded product removal station P2 (S110), and then transmits a table rotation timing signal Sa to the control device 30 of the injection molding machine 1 (S120). ). When the mold opening is completed and the control device 30 receives the table rotation timing signal Sa, the control device 30 controls the rotation drive mechanism 13 to rotate the rotary table 11 by 180 degrees (S130), and then outputs the molded product removal timing signal Sb. is transmitted to the automatic machine 50 (S140).

Next, the control device 30 controls the mold clamping drive mechanism 14 to clamp the upper mold 81 and the lower mold 82 in which the insert part K is installed, and then controls the injection device 20 to close the mold. Plasticized resin material is injected into the cavities 84 of the tightened upper mold 81 and lower mold 82 (S150, injection operation). The control device 30 controls the injection device 20 to apply a holding force to the resin material filled in the cavity 84 (S160, holding pressure operation).

Next, the control device 30 acquires the amount of cushioning during the pressure holding operation, and changes the setting of the cooling time C based on the acquired amount of cushioning (S170). Specifically, when the acquired cushion amount is equal to or greater than a predetermined reference value, the control device 30 determines that the molded product is a good product, and sets the first cooling time C1 as the cooling time C. Alternatively, when the obtained cushion amount is smaller than a predetermined reference value, the control device 30 determines that the molded product is a defective product, and sets the second cooling time C2 as the cooling time C.

Then, the control device 30 cools the resin material in the cavity 84 for a cooling time C after the pressure holding operation is completed (S180, cooling operation). That is, if the molded product is a good product, the resin material in the cavity 84 is cooled during the first cooling time C1. Alternatively, if the molded product is defective, the resin material in the cavity 84 is cooled during the second cooling time C2. After the cooling time C has elapsed, the control device 30 controls the mold clamping drive mechanism 14 to open the clamped upper mold 81 and lower mold 82. When the control device 30 receives the mold opening completion signal from the mold clamping drive mechanism 14, it recognizes that the mold opening has been completed.

When the automatic machine 50 receives the molded product removal timing signal Sb, it takes out the molded product from the lower mold 82 located at the molded product removal station P2 (S190). After this, steps S110 to S190 described above are repeatedly executed.

As described above, according to the injection molding machine 1 of this embodiment, the setting of the cooling time C used in the cooling operation for cooling the resin material in the cavity 84 is changed based on the cushion amount acquired in the pressure holding operation. Specifically, when the cushion amount is equal to or greater than the reference value, the first cooling time C1 is set as the cooling time C. Alternatively, when the cushion amount is smaller than the reference value, the second cooling time C2, which is longer than the first cooling time C1, is set as the cooling time C. Based on this, if the cushion amount is smaller than the standard value, the molded product is determined to be defective, and the cooling time C is set so that the molded product remains in the lower mold 82 when the mold is opened. Can be set. Therefore, there is no need to temporarily stop the molding operation, and it is possible to effectively suppress a decrease in production efficiency of molded products.

Although the embodiments of the present invention have been described above, the present invention is not limited to these examples. For example, the present invention may be applied to a molding machine such as a die-casting machine, and a person skilled in the art may appropriately add, delete, or change the design of the above-mentioned embodiments, or the features of the embodiments. Appropriate combinations of these are also included within the scope of the present invention as long as they do not go against the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1... Injection molding machine, 10... Mold clamping device, 11... Rotary table, 11a... Upper surface, 12... Movable die plate, 13... Rotation drive mechanism, 14... Mold clamping drive mechanism, 20... Injection device, 21... Heating cylinder, 21a... Nozzle, 30... Control device, 31... Storage device, 311... First cooling time storage area, 312... Second cooling time storage area, 50... Automatic machine, 81... Upper mold, 82... Lower mold, 84... Cavity, Sa... Table rotation timing signal, Sb... Molded product removal timing signal, C... Cooling time, C1... First cooling time, C2... Second cooling time

Claims (2)

A fixed die plate to which a fixed die is attached, a movable die plate to which a movable die is attached, and an injection device that injects a resin material into a cavity formed by the fixed die and the movable die. An injection molding machine having
a control device that controls the injection device to perform an injection operation for injecting a resin material into the cavity, and a pressure holding operation for applying a holding force to the resin material in the cavity;
The control device,
performing a cooling operation to cool the resin material in the cavity during a cooling time after the pressure holding operation is completed;
An injection molding machine characterized in that the setting of the cooling time used in the cooling operation is changed based on the cushion amount obtained in the pressure holding operation. The control device includes:
When the cushion amount is equal to or greater than a reference value, setting a first cooling time as the cooling time,
The injection molding machine according to claim 1, wherein when the cushion amount is smaller than a reference value, a second cooling time longer than the first cooling time is set as the cooling time.

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