JPH08267525A - Controlling method for mold clamping force of toggle type mold clamping device and device therefor - Google Patents

Abstract

PURPOSE: To realize easy setting work of a mold clamping fore even when a toggle type mold clamping device is used for injection compression molding. CONSTITUTION: Initial mold clamping force is set within the range, in which the output of a toggle type mold clamping device 10 and is in near proportion to mold clamping force, so ass to supply the initial mold clamping pressure, which is obtained by multiplying the initial mold clamping force by the predetermined conversion factor, to the mold clamping side oil chamber A of a mold clamping cylinder 12. After the end of initial mold clamping, injection is executed. By supplying the maximum mold clamping pressure corresponding to the predetermined final mold clamping force to the mold clamping side oil chamber A of the mold clamping cylinder 12 during injection or after the end of injection, compression molding is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toggle type mold clamping device, and more particularly to a mold clamping force control method and device for a toggle type mold clamping device used in an injection compression device.

[0002]

2. Description of the Related Art As a conventional injection compression molding apparatus, there is one disclosed in Japanese Patent Application Laid-Open No. 61-283520. The injection compression molding device shown in this figure has what is called a direct-acting type mold clamping device.The movable platen is directly attached to the piston rod of the mold clamping cylinder, and the movable platen has the same speed (same movement amount as the piston rod). ) Can be moved.

[0003]

However, in the injection compression molding apparatus having the above-mentioned conventional direct-acting type mold clamping device, for example, when decelerating in the vicinity of the mold clamping position, it flows into the mold clamping cylinder. Since it is necessary to directly adjust the amount of hydraulic oil to be used, there is a problem that the control performance of the speed and position of the movable plate is poor. As a solution to this, it is conceivable to use a toggle type mold clamping device. Due to the characteristics of the toggle mechanism, a speed characteristic that gradually decelerates near the mold clamping position is obtained. In the toggle type mold clamping device, since the toggle mechanism is interposed between the mold clamping cylinder and the movable plate, a complicated mold clamping force adjusting work is required as compared with the case of the direct-acting type mold clamping device. As a mold clamping force control method, Japanese Patent Laid-Open No. 6-285
There is one disclosed in Japanese Patent No. 934. The mold clamping force control method for this toggle type mold clamping device is such that the movable side mold is a mold touch or a mold by rotating the tie bar nut while maintaining this state with the toggle mechanism extended to a predetermined position. A mold position setting process that sets the position of the entire movable part such as the movable plate so that it is located just before touching, and a position where the mold is set after supplying a predetermined amount of molten resin to the mold cavity during mold clamping. It is configured to include a test molding step in which compression molding is carried out on a trial basis by arranging it at a position, and a compression amount setting step in which the mold clamping position of the entire movable part is determined based on the dimensions of the test molded product. However,
In the conventional mold clamping force control method for the toggle type mold clamping device as described above, not only it is necessary to calculate the relationship between the position of the mold clamping cylinder and the mold clamping force, but also the control becomes complicated. There is a problem that the cost is expensive to implement. The present invention
The purpose is to solve such problems.

[0004]

According to the present invention, in injection compression molding, it is necessary that the initial mold clamping force is smaller than the final mold clamping force, and also in the toggle type mold clamping mechanism,
Paying attention to the fact that the output of the mold clamping cylinder and the mold clamping force are almost in proportion to each other when the mold clamping force range is below a predetermined range, the setting region of the initial mold clamping force is set to the output of the mold clamping cylinder and the mold clamping force. The above-mentioned problem is solved by limiting to a range in which is substantially proportional. That is, a mold clamping force control method for a toggle type mold clamping device according to claim 1 of the present invention is a mold clamping force control method for a toggle type mold clamping device used in an injection compression device, which comprises: In the state where the initial mold clamping force is set and the fluid pressure proportional to this initial mold clamping force is supplied to the mold clamping side oil chamber of the mold clamping cylinder, the initial mold clamping force is limited to the range in which the mold clamping force is almost proportional. It is characterized in that the injection is started, and a fluid pressure corresponding to a predetermined final mold clamping force is supplied to the mold clamping side oil chamber of the mold clamping cylinder during or after the injection. The apparatus according to claim 2 for carrying out the above method is an apparatus for controlling a mold clamping force of a toggle type mold clamping device (10) used in an injection compression device, the mold clamping cylinder (12) being clamped. A mold clamping side pipe (32) whose one end is connected to the side oil chamber (A), and a mold opening side pipe (42) whose one end is connected to the mold opening side oil chamber (B) of the mold clamping cylinder (12). ) And a main switching valve (14) for switching the supply of fluid to both pipes (32, 42), and the other end of the mold opening side pipe (42) is Pilot check that is connected to one supply port (b) of the switching valve (14) and is connected to the other end of the mold clamping side pipe (32) and opens toward the mold clamping side pipe (32) Connect the valve (16) to its upstream port and the other supply port (a) of the main switching valve (14). Continuation pipe (36), branch pipe (38) branched from connection pipe (36), pressure control valve (18) provided in branch pipe (38), and pilot check valve (16) pilot pipe (34) ), And a solenoid valve (20) for driving the pilot check valve provided in the pilot pipe (34),
It is characterized by having. Further, in the apparatus according to claim 3, in the apparatus according to claim 2, instead of providing the branch pipe (38) and the pressure control valve (18), a branch is made from the mold clamping side pipe (32). The branched pipe (39) and the pressure control valve (19) provided in the branched pipe (39) are featured. The reference numerals in parentheses indicate the corresponding members of the embodiment.

[0005]

[Function] The fluid pressure obtained by setting the initial mold clamping force within a range where the output of the toggle type mold clamping device and the mold clamping force are in a substantially proportional relationship and multiplying the initial mold clamping force by a predetermined conversion coefficient. Is supplied to the mold clamping side oil chamber of the mold clamping cylinder. After the initial mold clamping, injection is performed, and during or after the injection, the maximum mold clamping pressure corresponding to the predetermined final mold clamping force is supplied to the mold clamping side oil chamber to perform compression molding. To do.

[0006]

【Example】

(First Embodiment) FIG. 1 shows a hydraulic circuit of the present invention and a simplified toggle type mold clamping device. One end of the mold clamping side pipe 32 is connected to the mold clamping side oil chamber A of the mold clamping cylinder 12 of the toggle type mold clamping device 10, and the other end of the mold clamping side pipe 32 is connected to the mold clamping side. The outlet side of the pilot check valve 16 that opens toward the oil chamber A is connected. On the inlet side of the pilot check valve 16, the main solenoid valve (main switching valve) 14 is arranged in parallel via a connection pipe 36 and a branch pipe 38 branched from this.
And the pressure control valve 18 are connected. That is, the port a of the main solenoid valve 14 is connected to the connection pipe 36, and the branch pipe 38 is connected to the pressure control valve 18. The port b of the main solenoid valve 14 is connected to the mold opening side oil chamber B of the mold clamping cylinder 12 via the mold opening side pipe 42, and the port P is connected to the main circuit 44 via the pipe 40. Further, the tank port T is connected to the pipe 46.
It is connected to the tank 48 via. The pilot check valve driving solenoid valve 20 is connected to the pilot pipe 34 of the pilot check valve 16.

Next, a toggle type mold clamping device to which the present invention is applied will be described. The cylinder body 12a of the mold clamping cylinder 12 described above is fixed to the housing 22, and the piston 12b is connected to the crosshead 28a of the toggle mechanism 28 via the piston rod 12c. One end of the link 28b is connected to the housing 22, and the other end thereof is connected to one end of the link 28c. The other end of the link 28c is connected to the movable plate 24. The link 28b is connected to the crosshead 28a via a link 28d. A fixed plate 26 is arranged at a position facing the movable plate 24. The housing 22 and the fixed platen 26 are connected by a total of four tie bars 30 (only two of which are visible in the drawing). The movable platen 24 is adapted to be guided to move in the axial direction by a tie bar 30 penetrating the movable platen 24. A movable side mold 25 is attached to the movable plate 24, and a fixed side mold 27 is attached to the fixed plate 26.

Next, the method for setting the mold clamping force according to the first embodiment will be described. First, the initial mold clamping force is set. In a general toggle mechanism, the output of the mold clamping cylinder and the mold clamping force have the relationship shown in FIG. That is,
In the range indicated by a in the figure, the mold clamping force increases corresponding to the increase in the output of the mold clamping cylinder 12, but in the range indicated by b in the figure, the mold clamping force is reduced even if the output of the mold clamping cylinder 12 decreases. The tightening force will increase. In addition, the range indicated by c in the figure (a in the figure
In the range indicated by (1), the output of the mold clamping cylinder and the mold clamping force are in a substantially proportional relationship. Therefore, if the initial mold clamping force is set within this range c, the setting work can be significantly simplified.
That is, in FIG. 1, the main solenoid valve 14 is switched to the symbol position on the left side of the drawing, and the main circuit 44, the pipe 40, the main solenoid valve 14, the connection pipe 36, the pilot check valve 16 and the mold closing are controlled by the pressure control valve 18. The fluid pressure that flows into the mold clamping side oil chamber A of the mold clamping cylinder 12 via the side pipe 32 is adjusted, and the pressure at which the initial mold clamping force is generated is stored as the initial set pressure. This initial set pressure can be easily obtained by multiplying a predetermined initial mold clamping force by a predetermined conversion coefficient determined by the cylinder pressure receiving area, although it is approximate. Next, with the links 28b and 28c of the toggle mechanism 28 fully extended,
The fluid pressure flowing into the mold clamping side oil chamber A of the mold clamping cylinder 12 is adjusted in the same manner as the conventional one so that the final mold clamping force is obtained.
That is, with the main solenoid valve 14 in the symbol position on the left side in the figure, the pressure control valve 18 is used to move the mold clamping cylinder 12
The fluid pressure that flows into the mold clamping side oil chamber A is adjusted and the fluid pressure when the final mold clamping force is generated is stored as the maximum set pressure. As a result, the final mold clamping force is set.

Next, the procedure of the injection compression molding operation by this apparatus will be described. First, with the mold open, the pressure control valve 18
Is maintained at the maximum set pressure (the final mold clamping force is set at the end of the previous molding cycle), the main solenoid valve 14 is switched from the neutral position shown in the drawing to the symbol position on the left side in the drawing,
The fluid pressure from the main circuit 44 is caused to flow into the mold clamping side oil chamber A of the mold clamping cylinder 12. As a result, the mold clamping operation is performed until the mold is touched while extending the links 28b and 28c of the toggle mechanism 28. When the die is touched, the pressure control valve 18 is changed to the initial set pressure. As a result, the piston 12b of the mold clamping cylinder 12 advances even after the mold is touched, and mold clamping is started, the fluid pressure in the mold clamping side oil chamber A is increased to the initial set pressure, and both molds 25, The initial mold clamping force acts between 27. In this state, the main solenoid valve 14
Is returned to the neutral position shown in the drawing, and the pilot check valve driving solenoid valve 20 is switched to the symbol position on the right side in the drawing. As a result, the pilot check valve 16 is closed, and the fluid pressure in the mold clamping side pipe 32 and the mold clamping side oil chamber A is maintained at the initial set pressure. Injection is performed in this state, a force greater than the initial mold clamping force is generated by the resin pressure in the molds 25 and 27, and the tie bar 30 is stretched by a small amount, so that both molds 25 and 27 are opened to some extent.
Along with this, the fluid pressure in the mold clamping side pipe 32 and the mold clamping side oil chamber A rises slightly above the initial set pressure. When the injection is completed and the pressure control valve 18 is changed to the maximum set pressure, and the main solenoid valve 14 is switched to the symbol position on the left side in the drawing again, the toggle mechanism 28 is fully extended and the piston 12b of the mold clamping cylinder 12 is extended. Moves to the forward limit, and the final mold clamping force is applied to both molds 25 and 27. By maintaining this state even during the holding pressure and cooling, a predetermined injection compression molded product can be molded.
After the cooling is completed, the pilot check valve driving solenoid valve 20 is switched to the symbol position shown in the drawing, and the main solenoid valve 1
4 is switched to the symbol position on the right side in the figure. As a result, the pilot check valve 16 is opened, and the fluid pressure in the mold clamping side oil chamber A and the mold clamping side pipe 32 passes through the pilot check valve 16, the connection pipe 36, the main solenoid valve 14, and the pipe 46. While being opened to the tank 48 and the mold clamping force is reduced to 0, it is supplied to the mold opening side oil chamber B from the main circuit 44 through the pipe 40, the main solenoid valve 14, and the mold opening side pipe 42, and the piston 12b is moved in the mold opening (backward) direction. As a result, the mold is opened and the injection compression molded product can be taken out. In the first embodiment, the pressure control valve 18 is arranged upstream of the pilot check valve 16 (on the side of the main circuit 44). However, in this configuration, as described above, the pilot is not operated during injection. The fluid pressure inside the mold clamping side pipe 32 and the mold clamping side oil chamber A of the mold clamping cylinder 12 on the downstream side of the check valve 16 becomes higher than the initial mold clamping pressure, and the resin pressure in the mold also rises. .

(Second Embodiment) When it is not preferable that the resin pressure in the mold rises during injection as in the case of the first embodiment, the branch pipe 38 shown by the solid line in FIG. 1 is used. Instead of providing the pressure control valve 18, a branch pipe 39 is provided in the mold clamping side pipe 32 on the downstream side of the pilot check valve 16, and the pressure control valve 19 is provided therein, as shown by a virtual line in the figure. You can also This makes it possible to prevent the initial mold clamping pressure from rising above a predetermined level from injection to the start of compression. That is, it is possible to prevent the resin pressure in the mold from rising above the set value during injection.

[0011]

As described above, according to the present invention, even when the toggle type mold clamping device is used for injection compression molding, the setting work of the initial mold clamping force is extremely simple as compared with the conventional case. Therefore, the cost required to set the initial mold clamping force can be reduced, and injection compression molding can be performed with a device having a simple structure that does not require complicated control.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a mold clamping cylinder showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an output of a mold clamping cylinder and a mold clamping force in a toggle type mold clamping device.

[Explanation of symbols]

 10 Toggle type mold clamping device 12 Mold clamping cylinder 14 Main solenoid valve (main switching valve) 16 Pilot check valve 18, 19 Pressure control valve 20 Pilot check valve drive solenoid valve 32 Mold clamping side pipe 36 Connection pipe 38, 39 Branch pipe 40, 46 Piping 42 Mold opening side piping 34 Pilot piping A Mold clamping side oil chamber B Model opening side oil chamber

Claims (3)

[Claims] 1. A method of controlling a mold clamping force of a toggle type mold clamping device used in an injection compression device, wherein the mold clamping cylinder output and the mold clamping force are limited to a range in which the mold clamping force and the mold clamping force have a substantially proportional relationship. A mold clamping force is set, and injection is started with the fluid pressure proportional to this initial mold clamping force being supplied to the mold clamping side oil chamber of the mold clamping cylinder. Is supplied to the mold clamping side oil chamber of the mold clamping cylinder, and a mold clamping force control method for a toggle type mold clamping device. 2. A device for controlling the mold clamping force of a toggle type mold clamping device (10) used in an injection compression device, wherein the mold clamping side oil chamber (A) and one end of the mold clamping cylinder (12) are provided. The mold clamping side pipe (32) connected, and the mold opening side oil chamber (B) of the mold clamping cylinder (12) and the mold opening side pipe (42) whose one end is connected.
And a main switching valve (14) for switching the supply of fluid to both pipes (32, 42), the mold clamping force control device for a toggle type mold clamping device, wherein the other end of the mold opening side pipe (42) The main switching valve (1
4) Pilot check valve (16) that is connected to one of the supply ports (b) and is connected to the other end of the mold clamping side pipe (32) and opens toward the mold clamping side pipe (32). ), A connection pipe (36) for connecting the upstream side port thereof to the other supply port (a) of the main switching valve (14), a branch pipe (38) branched from the connection pipe (36), The pressure control valve (18) provided in the pipe (38) and the pilot pipe (3) of the pilot check valve (16)
4) and a pilot check valve driving solenoid valve (20) provided in the pilot pipe (34), and a mold clamping force control device for a toggle type mold clamping device. 3. A branch pipe (39) branched from the mold clamping side pipe (32) instead of providing the branch pipe (38) and the pressure control valve (18).
A pressure control valve (19) provided in the branch pipe (39),
The mold clamping force control device for a toggle type mold clamping device according to claim 2, further comprising: