JPH0651333B2 - Electric mold clamping device of injection molding machine and drive control method thereof - Google Patents

Description

Description: INDUSTRIAL APPLICABILITY The present invention relates to an injection molding machine and an injection press molding machine used for secondary molding of synthetic resin (a molten resin is injected into a mold immediately before mold clamping and quantitative determination is performed). A molding machine that includes a step of pressing after performing filling with a high thrust mold (However, the following is typified by an injection molding machine.) And a drive control method thereof.

2. Description of the Related Art Electric mold clamping devices that use an electric motor (including a servomotor) as a power source are already known in the art (for example, JP-A-58).
-62030, JP-A-58-179630, JP-A-61-246032, etc.).

JP-A-58-62030 and JP-A-58-1796
In Japanese Patent Publication No. 30, a clutch is installed at an intermediate position of a rotary shaft rotated by a servo motor, and a nut member installed on a fixed platen and the rotary shaft are connected by a gear train having a speed increasing ratio and screwed into the nut member. There is described an electric mold clamping device in which a moving side die plate is attached to the tip of the screw shaft and driven by a single electric motor which also drives the injection device.

In Japanese Patent Laid-Open No. 61-246032, a ball nut member is rotatably installed on a fixed platen, and the tip of a ball screw shaft screwed into the nut member has a thrust force in the axial direction with respect to a moving die plate. The ball nut member and the ball screw shaft are individually driven by two dedicated servo motors, respectively.
Alternatively, an electric mold clamping device configured to drive both of them in common by a single servo motor is described.

Problems to be Solved by the Invention (I) Regarding a mold clamping device of an injection molding machine, a high thrust mold clamping is required to prevent a pair of molds from opening due to injection resin pressure during injection of molten resin. . However, when opening and closing the mold for taking out the molded product, it is required to move the mold as fast as possible in order to improve productivity. However, as the rotation speed-torque characteristic of the electric motor, a high speed and a high thrust are in opposition. For this reason, JP-A-58-62030
In the case of the system driven by a single electric motor like the electric mold clamping device described in Japanese Patent Publication No. 58-179630 and Japanese Patent Application Laid-Open No. 58-179630, high-speed rotation is performed and a high torque for mold clamping is output. There is no choice but to use an electric motor (servo motor). Therefore, a large-sized and large-output servomotor has to be selectively used for the electric motor, which is very expensive. For this reason, the mold clamping device is not used in a large-sized injection molding machine, but is actually used in a small-sized machine.

(II) In this regard, the electric mold clamping device disclosed in Japanese Patent Laid-Open No. 61-246032 is solved by switching between the motor and the transmission mechanism for high-speed mold opening / closing and high-thrust mold clamping. ing. However, two types of gear type speed reduction mechanisms having different reduction ratios are required, and the assembly is troublesome and the manufacturing cost is high. On the other hand, it is a well known fact that the ball screw mechanism has a limit of its high speed rotation, that is, a limit number of revolutions (also referred to as a speed limit or an allowable limit number of revolutions). There is also a limit to the speedup. For example, it is almost impossible to achieve an opening / closing speed that is twice the rotational speed limit of the ball screw, and this is a problem to be solved.

(III) Therefore, the object of the present invention is to use a reduction mechanism and a long rotary shaft (transmission shaft) at all, and realize, for example, a double opening / closing speed (double speed movement) without exceeding the limit rotational speed of the ball screw. An object of the present invention is to provide an improved electric mold clamping device and a drive control method therefor capable of performing mold clamping with a high thrust comparable to or less than the actual lead angle of the screw shaft.

Means for Solving the Problems (First Invention) As a means for solving the problems of the above-mentioned prior art, an electric mold clamping device of an injection molding machine according to the present invention is An electric type that installs a nut member on a fixed plate or a die plate so that it can only rotate, and rotates this nut member with an electric motor to open and close the mold and clamp the mold with a high thrust through a screw shaft screwed into the nut member. In the mold clamping device, nut members 4 and 4'are rotatably installed on both the fixed side die plate 1 and the moving side die plate 2, and the screw shaft 3 is commonly screwed into both nut members 4 and 4 '. This is used as a tie bar, and dedicated servo motors 9 and 9'are directly connected to the respective nut members 4 and 4'to enable transmission of rotational power, for example, by a belt transmission mechanism. And
The two servomotors 9 and 9'are operated individually or jointly to open and close the mold or clamp the mold with high thrust.

Action Since the screw shaft 3 is a tie bar, no matter which nut member 4 or 4'of the fixed side die plate 1 or the moving side die plate 2 is rotated, the moving side is moved by the screw movement with the screw shaft 3. The die plate 2 is opened and closed. When only one of the nut members 4 or 4'is rotated, it is a half-speed movement (meaning half-speed movement of the double-speed movement described later, the same applies below), and both nut members 4 and 4'are in the opposite directions at the same time. When it turns to, it will move at double speed. Even during this double speed movement, the rotational speed of the nut members 4 and 4'can be kept below the limit rotational speed of the ball screw. Further, when the two nut members 4 and 4'are rotated in the same direction with a slight speed difference, the moving amount of the moving die plate 2 becomes the speed difference, and the moving amount is substantially less than the screw lead angle. The mold can be clamped.

(Second and Third Inventions) Similarly, as a means for solving the problems of the prior art, the drive control method of the electric mold clamping device for the injection molding machine according to the present invention is the electric drive method according to the first invention. This is a drive control method executed as a mold opening / closing movement of the mold clamping device and a mold clamping process. That is, nut members 4 and 4'are installed on both the fixed side die plate 1 and the movable side die plate 2 so as to be rotatable only. , The screw shaft 3 screwed in common to both of these nut members 4 and 4'is used as a tie bar, and the fixed-side die plate 1 and the moving-side die plate 2 respectively have dedicated servos individually for the nut members 4 and 4 '. The motors 9 and 9'are capable of transmitting rotational power directly by, for example, a belt transmission mechanism, and the nut members 4 and 4'are rotated by the servomotors 9 and 9'to open and close the mold and to increase the thrust force through the screw shaft 3. The mold clamping In the electric mold clamping device, in the mold opening / closing process, the servo motor 9 on one side (for example, the fixed side) is normally driven and the servo motor 9'on the other side (moving side) is reversely driven to move at a double speed. To do. Immediately before the mold clamping, one (fixed side) servo motor 9 is stopped and the mold is closed at a half speed with low thrust. In the mold clamping process, both servo motors 9 and 9'are driven in the same direction with a slight speed difference to perform mold clamping with high thrust, or both servo motors 9 and 9'are slightly clamped immediately before mold clamping. It is characterized in that the mold is closed with a high thrust as it is by driving in the same direction with the speed difference.

Action When one (fixed side) servo motor 9 is rotated in the normal direction, the screw shaft 3 moves straight in the direction of arrow A with respect to the fixed side die plate 1. When the other (moving side) servo motor 9'is rotated in the reverse direction, the moving side die plate 2 is moved with respect to the screw shaft 3.
Moves in the same direction as the straight movement of the screw shaft 3. Therefore, if these two operations are performed at the same time, the actual moving speed of the moving die plate 2 is doubled (double speed movement),
Double speed mold opening and closing is performed.

If one (fixed side) servo motor 9 is stopped immediately before the mold is closed, the moving side die plate 2 has a speed based on the rotation of the other servo motor 9 '(half the speed of the double speed movement, hereinafter Is called a half-speed movement) and low-thrust mold closing is performed.

Immediately before the mold is closed or when the molds are clamped, when both servo motors 9 and 9'are reversely driven in the same direction with a slight speed difference, the moving side die plate 2 is moved by an amount corresponding to the speed difference (strictly, 0). As a result, the screw shaft 3 is moved at a lead angle of the screw shaft 3 or less), and a high thrust is generated in inverse proportion to the mold clamping with a high thrust.

EXAMPLE Next, an example of the present invention shown in FIGS. 1 to 3 will be described.

In the figure, 1 is a fixed-side die plate, 2 is a movable-side die plate, and both are installed on the molding machine base 12 so as to face each other. The movable die plate 2 is supposed to ride on the sliding guide 11 installed on the upper surface of the molding machine base 12 (FIG. 2) and move in parallel toward or away from the fixed die plate 1. There is. Illustration of the mold is omitted.

At the tie bar mounting positions of the fixed side die plate 1 and the moving side die plate 2, the rotating barrels 6 and 6'can only be rotated by the ball bearings 13 that also serve as thrusts, that is, even if a thrust force of about the mold clamping force is applied. It is installed so that it never moves in the direction. Ball nut members 4 and 4'are attached to the outer ends of the rotary cylinders 6 and 6 so as to rotate integrally by a method such as bolting. A screw shaft 3 formed as a ball screw is commonly screwed into both nut members 4 and 4'through a ball 14 so as to function as a tie bar. At the end of each screw shaft 3 on the side of the moving die plate 2 is attached a fixing plate 10 in the shape of a cross girder as shown in FIG. 2 by a nut fixing method, so that the screw shaft 3 is fixed so as not to rotate. There is.

Belt wheels 5 and 5'are attached to the outer circumferences of the nut members 4 and 4'for integral rotation. Particularly, as shown in FIG. 2, a belt (including a timing belt) 8'wound around each belt wheel 5 '... on the moving die plate 2 side in series.
Is also commonly wound around a driving belt wheel 7'of a servo motor 9'mounted and fixed to the lower part of the moving die plate 2, so that each nut member 4'is directly attached by the servo motor 9 '.
Are driven to rotate in the same direction at the same speed.

In this way, when the servomotor 9'is normally rotated and the nut member 4'is normally rotated, the right end portion of the screw shaft 3 is fixed to the fixed die plate 1 by the nut member 4 so as not to move in the axial direction.
The moving die plate 2 relatively moves in the direction of arrow B'in FIG. Conversely, when the servomotor 9'is rotated in the reverse direction, the moving die plate 2
Moves in the direction of arrow A '.

On the other hand, a belt (including a timing belt) 8 wound in series around a belt wheel 5 attached to the nut member 4 on the fixed die plate 1 side is a driving belt wheel of a servo motor 9 installed on a molding machine base 12. 7 is also wound in common, so that the servo motors 9 directly drive the nut members 4 ... In the same direction at the same speed. That is, when the servomotor 9 rotates in the normal direction and the nut member 4 rotates in the normal direction, the screw shaft 3 moves linearly in the direction of arrow A in FIG. Therefore, when the nut member 4'of the moving side die plate 2 is stopped, the moving side die plate 2 is moved to close the mold by the linear movement of the screw shaft 3. Conversely, when the servomotor 9 is rotated in the reverse direction, the screw shaft 3 moves straight in the direction of arrow B, and the moving die plate 2 moves to open the mold. Therefore,
In summary, the following operations and combinations are established.

According to the above case, when the servomotor 9 or 9'is operated independently, the moving die plate 2 moves at a half speed of the mold closing or mold opening movement within the limit rotation speed of the ball screw. .

According to the above case, when the servomotor 9 or 9'rotates the nut member 4 or 4'at the limit rotational speed of the ball screw, the moving side die plate 2 becomes 2 as a result of combining both screw motions. The mold will be closed or opened at a double speed.

According to the above case, if the rotation speeds of the servomotors 9 and 9'are the same, the moving side die plate 2 has a relative speed of 0 as a result of the combination of both screw movements, and does not move substantially. However, the servomotors 9 and 9 '
If a slight speed difference is set in, the speed will move at a small speed in the direction in which the absolute value of the speed is large. For example, in the above case, the moving speed in the arrow A direction is slightly increased, and in the above case, the moving speed in the arrow A ′ is slightly increased, the moving side die plate 2 moves in the mold closing direction by the speed difference, and the screw shaft When the lead angle of 3 is in the range of 0 to the lead angle, a high thrust is generated and the mold is clamped.

Therefore, in the mold opening / closing step, as shown in the above or case, for example, one servomotor 9 is driven in the forward direction and the other servomotor 9'is driven in the reverse direction (or the opposite thereof). Just before the mold clamping, one servomotor 9 (or 9 ') is stopped to move the mold at a low thrust at a half speed to perform the mold closing step. As in the case, by driving both servo motors 9 and 9'forward / reversely with a slight speed difference, it is possible to perform mold clamping with high thrust.

Alternatively, immediately before the mold clamping, both servo motors 9 and 9'may be driven in the forward and reverse directions with a slight speed difference, as in the above case, to perform the mold closing and mold clamping with high thrust.

The belts 8 and 8'and the belt wheels 7, 7'and 5, 5'in the configuration of the above-described embodiment may be replaced with configurations such as chains and sprockets, and the same operation can be performed.

Advantageous Effects of the Present Invention As described above in detail with reference to the embodiments, according to the electric mold clamping device of the injection molding machine and the drive control method thereof according to the present invention, firstly, a transmission gear, etc. The mold opening / closing can be freely selected from high speed to low speed without using a speed reducer, and the mold can be clamped with high thrust. In particular, the moving-side die plate 2 can be moved at a double speed within the range of the rotational speed limit specific to the ball screw to increase the speed.

Second, without being influenced by the lead angle of the ball screw,
High thrust can be generated with the contents below the lead angle.
The servo motors 9 and 9'can be downsized and cost can be reduced.

By thus reducing the manufacturing cost of the mold clamping device and increasing the mold opening / closing speed, it is possible to obtain the effect of further improving the productivity.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of an essential part of an injection molding machine according to the present invention, and FIGS. 2 and 3 are left and right side views of the same. 1 ... Fixed side die plate 2 ... Moving side die plate, 3 ... Screw shaft 4,4 '... Nut member 9,9' ... Servo motor, 7, 5 ... Belt wheel 8 ... Belt

Claims (3)

[Claims] 1. A nut member is rotatably installed on a stationary plate or a die plate, the nut member is rotated by an electric motor, and the mold is opened and closed and a high thrust mold is inserted through a screw shaft screwed into the nut member. In an electric mold clamping device that performs tightening, a nut member is rotatably installed on both the fixed die plate and the moving die plate, and a screw shaft is commonly screwed into both nut members to form a tie bar. A dedicated servo motor is directly connected to each nut member so that rotational power can be transmitted, and the mold is opened or closed or the mold is clamped with high thrust by operating these two servo motors individually or jointly. An electric mold clamping device for an injection molding machine, which is characterized in that 2. A fixed-side die plate and a movable-side die plate are provided with nut members rotatably only, and a screw shaft commonly screwed into both of these nut members serves as a tie bar. A dedicated servo motor is directly connected to each nut member of the moving die plate so that rotational power can be transmitted, and the nut member is rotated by the servo motor to open / close the mold and increase the thrust force through the screw shaft. In the electric mold clamping device that performs mold clamping, the mold opening and closing process is performed at double speed by driving one servomotor in the forward direction and the other servomotor in the reverse direction. The motor is stopped and the mold is closed at a half speed with low thrust, and the mold clamping process is performed by driving both servo motors in the same direction with a slight speed difference to achieve mold clamping with high thrust. A drive control method for an electric mold clamping device of an injection molding machine, the method comprising: 3. A fixed-side die plate and a movable-side die plate are provided with a nut member rotatably only, and a screw shaft commonly screwed into these both nut members serves as a tie bar. A dedicated servo motor is directly connected to each nut member of the moving die plate so that rotational power can be transmitted, and the nut member is rotated by the servo motor to open / close the mold and increase the thrust force through the screw shaft. In an electric mold clamping device that performs mold clamping, the mold opening and closing process is performed at double speed by driving one servomotor in the forward direction and the other servomotor in the reverse direction. Is controlled in the same direction with a slight speed difference to perform mold clamping with high thrust, and a drive control method for an electric mold clamping device of an injection molding machine.