JPH01314128A - Motor driven mold clamping device of injection molding machine and its driving control method - Google Patents

Abstract

PURPOSE:To perform mold clamping of high-thrust force equal to that not exceeding a lead angle, by a method wherein turning power of exclusive servomotor is transferred individually to nut members of tie bars screwed into the nut members mounted turnably on both of a stationary side die plate and movable side die plate. CONSTITUTION:Since a screw shaft is of a tie-bar, a movable side die plate 2 performs a breaking or clamping movement by a screw movement with a screw shaft 3 in either case where either nut member 4 of a stationary side die plate 1 or a movable side die plate 2 is turned by a servomotor 9 or nut member 4' is turned similarly by a servomotor 9'. When only nut member 4 or 4' on one side is turned the movement is of a half speed movement (half speed movement of an undermentioned double speed movement) and when both the nut members 4, 4' are turned at a time in the directions opposing to each other, the movement becomes a doubled speed one. When the two nut members 4, 4' are turned at a little speed difference in the same direction, a movement of the movable side die plate 2 becomes the speed difference, which becomes substantially the movement not exceeding a screw lead angle and mold clamping of high-thrust force can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to injection molding machines and injection press molding machines used for secondary molding of synthetic resins (injection molding machines and injection press molding machines that inject molten resin into the mold immediately before mold clamping and Molding machines that include filling, then high-thrust mold clamping, and pressing.However, the following is representative of injection molding machines), and more specifically, it is a molding machine that uses an electric motor as a power source to open and close the mold and clamp the mold. The present invention relates to an electric mold clamping device and its drive control method.

Conventional technology Electric mold clamping devices using electric motors (including servo motors) as a power source are already known in various ways (for example, Japanese Patent Laid-Open No. 58
-62030, JP-A-58-179630, JP-A-61-246032, etc.).

■ JP-A-58-62030 and JP-A-58-179
No. 630 discloses that a clutch is installed in the middle of a rotating shaft rotated by a servo motor, a nut member installed on a fixed plate and the rotating shaft are connected by a gear train with a speed increasing ratio, and the clutch is screwed into the nut member. An electric mold clamping device is described in which a movable die plate is attached to the tip of a screw shaft, and the mold clamping device is driven by a single electric motor that also serves as a drive for an injection device.

■ Japanese Patent Application Laid-Open No. 61-246032 discloses that a pole nut member is installed on a stationary plate so that it can only rotate freely, and the tip of the pole screw shaft screwed into this nut member applies an axial thrust to the moving die plate. It is configured such that the ball nut member and the pole screw shaft can be driven individually by two dedicated servo motors, or both can be rotationally driven in common by one servo motor. An electric mold clamping device is described.

Problem to be solved by the present invention (I) Regarding the mold clamping device of an injection molding machine, high thrust mold clamping is required to prevent a pair of molds from opening due to the pressure of the injection resin during injection of molten resin. . However,
When opening and closing the mold to take out the molded product, it is required to move as fast as possible to improve productivity. However, as for the rotational speed-torque characteristics of an electric motor, increasing the speed and increasing the thrust are contradictory. For this reason, JP-A-58-6203
In the case of a system driven by a single electric motor, such as the electric mold clamping device described in No. 0 and Japanese Patent Application Laid-Open No. 58-179630, it rotates at high speed and outputs high torque for mold clamping. Therefore, a large-sized, high-output servo motor must be selectively used as the motor, making it very expensive.

For these reasons, the mold clamping device is not used in large injection molding machines, but is actually used mostly in small machines.

(■) The electric mold clamping device described in JP-A-61-246032 solves this problem by switching the motor and transmission mechanism for high-speed mold opening/closing and high-thrust mold clamping. ing. However, two systems of gear type reduction mechanisms with different reduction ratios are required, which makes assembly difficult and increases production costs.On the other hand, the pole screw mechanism has a limit of its high speed rotation It is a well-known fact that there is a certain number (also called speed limit or permissible rotation speed limit), and therefore there is a limit to increasing the opening/closing speed of the mold clamping device.For example, there is a limit of 2.
It is simply impossible to double the opening and closing speed, and this is an issue that must be resolved.

(■) Therefore, the purpose of the present invention is to eliminate the need for reducing speed reduction mechanisms and long rotating shafts (transmission shafts), and for example, to open and close at double the speed (double speed movement) without exceeding the limit rotation speed of a pole screw. It is an object of the present invention to provide an electric mold clamping device and a drive control method thereof, which are operable and have an improved structure capable of performing mold clamping with a high thrust equal to or less than the actual lead angle of a 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 for an injection molding machine according to the present invention is provided as an example shown in the drawings.

An electric type in which a nut member is installed on a fixed platen or die plate so that it can only rotate, and this nut member is rotated by an electric motor to open and close the mold and perform high-thrust mold clamping via a screw shaft screwed into the nut member. In the mold clamping device, nut members 4.4' are installed on both the stationary die plate l and the movable die plate 2 so as to be rotatable, and the screw shaft 3 is commonly screwed into both nut members 4.4'. This was used as a tie bar, and a dedicated servo motor 9.9' was directly connected to each nut member 4.4' by, for example, a belt transmission mechanism to enable transmission of rotational power. and,
The structure is such that the mold is opened and closed or the mold is clamped with high thrust by operating these two servo motors 9 and 9' individually or in combination.

Since the working screw shaft 3 is a tie bar, when either the nut member 4 or 4' of the stationary die plate 1 or the movable die plate 2 is rotated, the screw movement with the screw shaft 3 will cause the movement. The side die plate 2 moves to open and close. When only one nut member 4 or 4' is rotated, half-speed movement (means % speed movement of double-speed movement described later, the same applies hereinafter)
Therefore, when both nut members 4,4' are rotated simultaneously in opposite directions, the movement becomes double speed. Even during this double speed movement, the rotational speed of the nut member 4.4' can be kept below the limit rotational speed of the pole screw. In addition, two nut members 4
．． 4' are rotated in the same direction with a slight speed difference, the amount of movement of the movable die plate 2 is equal to the speed difference, and the amount of movement is substantially less than the screw lead angle, so that mold clamping can be performed with a high thrust.

(Second and Third Inventions) As a means for solving the same problems of the prior art, a drive control method for an electric mold clamping device for an injection molding machine according to the present invention is a method for controlling the drive of an electric mold clamping device according to the first invention. This is a drive control method carried out during the mold opening/closing movement and mold clamping process of a type mold clamping device, that is, the nut members 4 and 4' are installed on both the stationary die plate 1 and the movable die plate 2 so that they can only rotate. The screw shaft 3 commonly screwed into both of these nut members 4 and 4' serves as a tie bar, and the nut members 4 and 4 of each of the stationary die plate 1 and the movable die plate 2 are connected to each other.
A dedicated servo motor 9.9' is directly connected to 4', for example, by a belt transmission mechanism, so that rotational power can be transmitted.
In an electric mold clamping device in which the nut members 4 and 4' are rotated by servo motors 9 and 9' to open and close the mold and clamp the mold with high thrust via the screw shaft 3, the mold opening and closing process is performed on one side (e.g. The servo motor 9 on the fixed side is driven in the forward direction, and the other servo motor 9' on the moving side is driven in the reverse direction to perform double-speed movement. Immediately before mold closing, the servo motor 9 on the one side (the fixed side) is stopped. Then, close the mold with low thrust by moving at half speed. In the mold clamping process, high thrust mold clamping is performed by driving both servo motors 9.9' in the same direction with a slight speed difference, or just before mold clamping, both servo motors 9.9' are driven slightly in the same direction. This special feature is characterized in that it closes the mold with high thrust and clamps the mold by driving in the same direction with a speed difference of In contrast, the screw shaft 3 moves straight in the direction of arrow A, for example. When the other (moving side) servo motor 9' is reversed, the moving side die plate 2
moves in the same direction as the linear movement of the screw shaft 3. Therefore, if these two operations are performed simultaneously, the actual moving speed of the moving die plate 2 will be doubled (double speed movement).
The mold opens and closes at double speed.

When one (fixed side) servo motor 9 is stopped immediately before the mold closes, the movable die plate 2 moves at a speed based on the rotation of the other remaining servo motor 9' (the speed of expansion compared to the double speed movement, hereinafter referred to as half this). (referred to as high-speed movement), the mold is closed with low thrust.

When both servo motors 9 and 9' are reversely driven in the same direction with a slight speed difference immediately before mold closing or during mold clamping, the movable die plate 2 moves an amount corresponding to the speed difference (
Strictly speaking, the movement is greater than 0 and less than the lead angle of the screw shaft 3), and a high thrust is generated inversely proportionally, resulting in high thrust mold clamping.

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

In the figure, 1 is a stationary die plate, and 2 is a movable die plate, both of which are placed facing each other on the molding machine base 12. The movable die plate 2 rides on a sliding guide 11 installed on the upper surface of the molding machine base 12 (Fig. 2), and moves in parallel toward or away from the fixed die plate 1. There is. Illustration of the mold was omitted.

The tie bars of the stationary die plate l and the movable die plate 2 are mounted in such a position that the rotary cylinder 6, 6' can only be rotated freely by the ball bearing 13 which also serves as thrust, that is, even when receiving a thrust equal to the mold clamping force. It is installed so that it never moves in the axial direction. A pole nut member 4.4' is attached to the outer end of the one-rotation tube 6.6 by bolting or the like so that it rotates integrally therewith. A screw shaft 3 formed as a pawl screw is commonly screwed into both nut members 4,4' through a pawl 14, and is configured to function as a tie bar. At the end of each screw shaft 3 on the movable die plate 2 side, a fixed plate 10 in the form of a grid is attached with a nut as shown in FIG. ing.

A belt pulley 5.degree. 5' is attached to the outer periphery of each nut member 4, 4' so as to rotate integrally therewith. In particular, as shown in Fig. 2, each belt pulley 5' on the moving side die plate 2 side...
A series of belts (including timing belt) wrapped around 8
' is also commonly wrapped around the drive belt pulley 7' of the servo motor 9' which is fixedly attached to the lower part of the moving die plate 2.
Therefore, the servo motor 9' directly drives each nut member 4.
' are configured to rotate in the same direction at the same speed.

In this way, when the servo motor 9' rotates forward and the nut member 4' rotates forward, the right end of the screw shaft 3 is fixed so that it does not move in the axial direction toward the fixed side guide 1 by the nut member 4.
Due to the screw movement between the die plate 2 and the movable die plate 2, the movable die plate 2 relatively moves in the direction of arrow B' in FIG. Conversely, when the servo motor 9' is reversed, the moving die plate 2
moves in the direction of arrow A' to close the mold.

On the other hand, a belt (including a timing belt) 8, which is wound in series around a belt pulley 5 attached to a nut member 4 on the fixed die plate L side, is a driving force of a servo motor 9 installed on a molding machine base 12. It is also commonly wound around the belt pulley 7, and the servo motor 9 directly connects each nut member 4...
・It is configured to rotate in the same direction at the same speed. That is, when the servo motor 9 rotates normally and the nut member 4 rotates normally, the screw shaft 3 moves straight in the direction of arrow A in FIG. 1 due to the screw movement with the screw shaft 3. Therefore, when the nut member 4' of the movable die plate 2 is stopped, the movable die plate 2 moves to close the mold due to the linear movement of the screw shaft 3. Conversely, when the servo motor 9 is reversed, the screw shaft 3 moves straight in the direction of arrow B, and the movable die plate 2 moves to open the mold. Therefore, in summary, the following operations and combinations are established.

According to the case of ■ or ■ above, the servo motor 9 or 9
When ' is operated alone, the movable die plate 2 moves at half speed to close or open the mold within the limit rotational speed of the pole screw.

According to the case of ■ or ■ above, the servo motor 9 or 9
When the nut member 4 or 4' is rotated at the limit rotation speed of the pole screw, the movable die plate 2 moves at twice the speed to close or open the mold as a result of the combination of both screw movements. It turns out.

According to the above case (■) or (■), if the rotation speeds of the servo motors 9 and 9' are the same, the relative speed of the moving die plate 2 will be 0 as a result of the combination of both screw movements, and there will be no actual movement. do not.

However, if a slight speed difference is set between the servo motors 9 and 9', the servo motors 9 and 9' will move at a very small speed in the direction where the absolute value of the speed is large. In the case of , when the moving speed of arrow A' is slightly increased, the moving die plate 2 moves in the mold closing direction by that speed difference, and a high thrust is generated in the range of the lead angle of the screw shaft 3 from O to the lead angle. Mold clamping is performed.

Therefore, in the opening/closing process of the mold, for example, one servo motor 9 is driven in the forward direction and the other servo motor 9' is driven in the reverse direction (or in the opposite direction). Immediately before mold closing, one servo motor 9 (or 9') is stopped and the mold is closed with low thrust at half speed, as in case ① or ① above, and the mold closing process is performed by moving at double speed. In this case, mold clamping with a high thrust can be performed by driving both servo motors 9 and 9' in forward and reverse directions with a slight speed difference, as in case 1 or 2 above.

Alternatively, just before mold clamping, both servo motors 9 and 9' can be driven in forward and reverse directions with a slight speed difference, as in case ① or ■ above, to perform mold closing and clamping with high thrust. .

It should be noted that the belt 8.8' and the belt pulleys 7.7' and 5.5' in the configuration of the above embodiment can be replaced with, for example, a chain 7 and a sprocket.

As described in detail in conjunction with the embodiments, the effects of the present invention are as follows.According to the electric mold clamping device for an injection molding machine and its drive control method according to the present invention, firstly, the transmission gear, etc. The mold opening/closing speed can be freely selected from high to low without using a reduction gear, and the mold can be clamped with high thrust. In particular, the movable die plate 2 can be moved at double speed within the limit rotation speed specific to the pole screw to increase the speed.

Second, regardless of the lead angle of the pole screw,
It is possible to generate high thrust with content less than the lead angle,
The size and cost of the servo motor 9,9' can be reduced.

In this way, by reducing the manufacturing cost of the mold clamping device and increasing the mold opening/closing speed, it is possible to obtain effects that further contribute to improved productivity.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of an injection molding machine according to the present invention, and FIGS. 2 and 3 are left and right side views of the same. l... Fixed side die plate 2... Moving side die plate 3... Screw shaft 4
, 4'...Stone 8B Material 9.9
'...Servo motor 7.5...Belt wheel 8...
・Belt Figure 2 Figure 3

Claims (1)

[Scope of Claims] [1] A nut member is installed on a fixed platen or a die plate so that it can only rotate, and this nut member is rotated by an electric motor to open and close the mold via a screw shaft screwed into the nut member. In an electric mold clamping device that performs high-thrust mold clamping, nut members are installed on both the stationary die plate and the movable die plate so that they can only rotate, and a screw shaft is screwed into both nut members in common. A dedicated servo motor is directly connected to the tie bar and each nut member to enable the transmission of rotational power, and these two servo motors can be operated independently or jointly to open and close the mold or to generate high thrust. An electric mold clamping device for an injection molding machine that performs mold clamping. [2] Nut members are installed on both the fixed die plate and the moving die plate so that they can only rotate, and the threaded shafts commonly screwed into both nut members are used as tie bars, and the fixed die plate and the moving side A dedicated servo motor is directly connected to each nut member of the die plate to enable transmission of rotational power, and the nut member is rotated by the servo motor, opening and closing the mold and clamping the mold with high thrust through the screw shaft. In an electric mold clamping device, the mold opening/closing process is performed at double speed by driving one servo motor in the forward direction and driving the other servo motor in the reverse direction. Immediately before mold clamping, one servo motor is Injection molding that is characterized by stopping and moving at half speed to close the mold with low thrust, and in the mold clamping process, closing the mold with high thrust by driving both servo motors in the same direction with a slight speed difference. A method for controlling the drive of the electric mold clamping device of the machine. [3] Nut members are installed on both the stationary die plate and the movable die plate so that they can only rotate, and the threaded shaft commonly screwed into both nut members is used as a tie bar, and the fixed die plate and the movable side A dedicated servo motor is directly connected to each nut member of the die plate to enable transmission of rotational power, and the nut member is rotated by the servo motor, opening and closing the mold and clamping the mold with high thrust through the screw shaft. In an electric mold clamping device, the mold opening/closing process is performed at double speed by driving one servo motor in the forward direction and driving the other servo motor in the reverse direction. 1. A drive control method for an electric mold clamping device for an injection molding machine, which performs high-thrust mold clamping by driving in the same direction with a speed difference of .