JP2007008105A - Mold closing device for electric injection molding machine and method of controlling its clamping force - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold closing device for electric injection molding machines which is low-cost, has high reliability and can keep the clamping force constant in a long-period continuous operation and give consistent moldings. <P>SOLUTION: A device for controlling the clamping force is employed in electric injection molding machines in which a clamping housing is connected with a movable platen through a linkage, with the linkage connected through a cross-head, so that moving the movable platen with moving cross-head causes a fixed platen and the movable platen to clamp the mold. In the device for controlling the clamping force, a clamping force set before starting of continuous operation is stored as a position of the clamping housing, and changes of the clamping force during mold clamping in continuous operation are detected as changes in the position of the clamping housing. When there occurs a change in the position of the clamping housing, the stopping position of the cross-head during clamping is corrected so that the clamping force reaches the value set before starting of the operation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold clamping device of an electric injection molding machine that automatically corrects the mold clamping force during continuous production to be always constant in the electric injection molding machine and a mold clamping force control method thereof.

In an injection molding machine having a mold clamping device using a toggle mechanism, the mold clamping force is adjusted at the time of mold installation, and continuous production is performed. However, when the mold expands due to temperature rise, the mold clamping force fluctuates. There was a possibility. Conventionally, in order to avoid this problem, a strain sensor is attached to a component of the mold clamping, and the mold clamping force is adjusted so that the detected value of the strain sensor becomes the set mold clamping force (see Patent Document 1) A method is known in which the amount of movement of the base and the mold clamping housing during mold clamping is measured, and thereby the mold clamping housing is moved to adjust the mold clamping force (see, for example, Patent Document 2).
JP-A-9-187853 JP 2001-277248 A

  However, in the technique shown in Patent Document 1, it is necessary to provide a strain sensor, which may increase the cost. In addition, when the accuracy of the mold clamping device is slightly deviated due to wear of components, accurate mold clamping force cannot be detected.

  Moreover, in the technique shown in Patent Document 2, since the mold clamping housing is moved during automatic operation, there is a possibility that the cycle becomes long and molding is not stable. In addition, there is a possibility that the mold clamping force may vary depending on the direction in which the mold clamping housing is moved during adjustment due to the clearance due to the tolerance between the screw portions of the tie bar and the nut. Moreover, there is a possibility that the adjustment must be repeated many times.

  The present invention has been made to solve the above-described conventional problems, and detects a change in the mold clamping force by detecting a change in the position of the mold clamping housing, and compensates for the fluctuation amount. By correcting the position of the motor, it is possible to maintain a constant mold clamping force in a long-term continuous operation at a low cost and with high reliability, and to obtain a stable molded product. An object of the present invention is to provide a mold clamping device of an injection molding machine and a mold clamping force control method thereof.

  In order to solve the above-described problems, the present invention connects a mold clamping housing to a movable platen using a link mechanism, and connects the link mechanism by a crosshead, and moves the movable platen as the crosshead moves. In the mold clamping device of the electric injection molding machine configured to perform mold clamping, the mold clamping housing position detecting means for detecting the position of the mold clamping housing at the time of mold clamping, and detection by the mold clamping housing position detecting means Crosshead movement position correcting means for calculating the amount of change from the position of the mold clamping housing and correcting the movement stop position of the crosshead during mold clamping based on the amount of change. To do.

  Further, in the mold clamping device of the electric injection molding machine according to the present invention, the mold clamping housing position detecting means includes a first position sensor for detecting a position of the mold clamping housing with respect to a base, and the crosshead moving position correcting means. Is a mold clamping device for an electric injection molding machine, wherein a change amount of a mold clamping force is detected based on a change in a detection value of the first position sensor.

  Further, in the mold clamping device of the electric injection molding machine according to the present invention, a second position sensor for detecting a position of the mold clamping housing relative to the stationary platen is provided as the mold clamping housing position detecting means, and the crosshead movement position correction is performed. The means detects the amount of change in the clamping force based on the change in the detection value of the second position sensor.

  Further, in the mold clamping device of the electric injection molding machine of the present invention, a third position sensor for detecting the position of the movable plate relative to the fixed platen is provided as the mold clamping housing position detecting unit, and the crosshead moving position correcting unit is provided. Is characterized in that the amount of change in mold clamping force is detected based on the change in the detection value of the third position sensor.

  Further, in the mold clamping device of the electric injection molding machine according to the present invention, the cross head movement position correcting means includes a cross head position sensor for detecting a position of the cross head with respect to a position of the mold clamping housing, and the cross head position sensor. And a control device that determines the stop position of the crosshead during mold clamping based on the detected value.

  Further, the present invention connects the mold clamping housing to the movable platen using the link mechanism, and connects the link mechanism with the crosshead, and moves the movable platen along with the movement of the crosshead, thereby fixing the fixed platen. In the mold clamping force control method of the electric injection molding machine in which mold clamping is performed with the movable platen, the mold clamping force set before the start of continuous operation is stored as the position of the mold clamping housing, and during the continuous operation Change in mold clamping force at the time of mold clamping is detected as a change in the position of the mold clamping housing, and if there is a change in the position of the mold clamping housing, the mold clamping force set before the start of continuous operation will be used. The crosshead movement stop position at the time of mold clamping is corrected.

  According to the present invention, the mold clamping force is detected by detecting the position of the mold clamping housing at the time of mold clamping, so that the mold clamping force can be accurately monitored, and the mold clamping force is corrected by the position of the crosshead. Since the adjustment is performed by adjusting the angle, it can be easily changed in a short time, and there is an effect that a stable mold clamping force can be obtained at low cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
1 is a side sectional view of a mold clamping device of an electric injection molding machine according to Embodiment 1 of the present invention.
The fixed platen 1 is fixed on a base 18, and a fixed mold 4 is attached to the fixed platen 1.
The movable platen 2 is movably installed on a base 18 in a form guided by four tie bars 6, and the movable mold 5 is mounted on the movable platen 2.

  The mold clamping housing 3 is connected to the fixed platen 1 and the tie bar 6 and is movable to the left and right on the base 18 by a moving device (not shown). The link mechanism 7 is connected to the movable platen 2. The link mechanism 7 is connected to the cross head 8, and when the cross head 8 moves left and right on the paper surface, the movable platen 2 similarly moves left and right, and the mold is opened and closed.

  A ball nut 19 is fixed to the cross head 8, and the ball screw 12 is rotated to move in the left-right direction. The rotation of the servo motor 15 is transmitted to the ball screw 12 through the small pulley 11, the timing belt 10, and the large pulley 9.

  The first position sensor 14 constituting the mold clamping housing position detecting means of the present invention is fixed to the base 18 and the mold clamping housing 3 and detects the position of the mold clamping housing with respect to the base.

  Further, the crosshead position sensor 13 constituting the crosshead movement position correcting means of the present invention is fixed to the crosshead 8 and the mold clamping housing 3, and the control device 16 crosses the crosshead position sensor 13 based on the detection position of the crosshead position sensor 13. The movement amount of the head is detected, and the movement stop position of the cross head is determined based on the detection value of the first position sensor 14.

  Note that the control device 16 can control the entire mold clamping device and can control the operation of the servo motor 15 via the servo amplifier 17.

  The operation of the first embodiment configured as described above will be described with reference to FIG.

  At the start of molding, the movable platen 2 and the movable mold 5 are moved to the left side of the page, and the mold is open. Next, the servo motor 15 is rotated, and the ball screw 12 is rotated through the small pulley 11, the timing belt 10, and the large pulley 9. The ball nut 19 moves integrally with the cross head 8 to the right side of the drawing.

  The movable platen 2 and the movable mold 5 are moved in the direction guided by the tie bar 6 in the direction of the fixed platen 1 and the fixed mold 4 via the link mechanism 7. The fixed mold 4 and the movable mold 5 are in contact with each other, and the crosshead 8 is further moved to the right side of the drawing, and the movable mold 5 is pressed toward the fixed mold 4 to generate a predetermined clamping force.

  When the mold clamping of the molding start shot is completed (S1), the position of the mold clamping housing 3 is detected (measured) by the first position sensor 14, and the numerical value is stored as a reference value (S2).

  Next, material is injected into the mold from an injection device (not shown), and after a predetermined cooling time has passed, the movable mold 5 is rotated together with the movable platen 2 from the fixed platen 1 by the rotation of the servo motor 15 in the opposite direction. It moves away, opens the mold, takes out the molded product with a device not shown, and completes one cycle.

  Usually, the temperature of the fixed mold 4 and the movable mold 5 gradually increases because molten resin is injected after the start of continuous molding. As the mold expands, there is a possibility that the position of the mold clamping housing at the time of completion of mold clamping is shifted from shot to shot. Therefore, after the start of continuous molding, the control device 16 measures the position of the mold clamping housing 3 with the first position sensor 14 every time mold clamping is completed (S4), and compares it with the stored reference value to calculate the deviation amount. (S6).

  When the deviation is outside the allowable range (S7), the control device 16 corrects the movement amount of the movable platen 2 so that the position of the mold clamping housing 3 is the same as that at the start of molding. 8 is stopped (S8). This correction amount is determined as the amount of change in the detected value of the crosshead position sensor 13 determined in accordance with the amount of change in the position of the mold clamping housing 3, and the control device 16 drives the servo motor 15 to detect the position of the crosshead. Correct.

  If the amount of deviation is within the allowable range (S9), the continuous operation is performed without correcting the position of the crosshead 8 (S10).

Embodiment 2. FIG.
FIG. 3 is a side sectional view of the mold clamping device of the electric injection molding apparatus showing the second embodiment.
In the first embodiment, the mold clamping housing position detection means is configured by the first position sensor 14 that detects the position of the mold clamping housing with respect to the base. However, as shown in FIG. You may make it comprise by the 2nd position sensor 14A which detects the position with respect to the stationary platen 1 of the mold clamping housing 3. FIG.

  In this case, the control device 16A detects the amount of change in the position of the mold clamping housing 3 (the amount of change in the mold clamping force) based on the change in the detection value of the second position sensor 14A, and hereinafter the same as in the first embodiment. The operation can be performed, and the same effect as in the first embodiment can be obtained.

Embodiment 3 FIG.
FIG. 4 is a side cross-sectional view of the mold clamping device of the electric injection molding apparatus showing the third embodiment.
In the third embodiment, the mold clamping housing position detecting means may be configured by a third position sensor 14B that detects the position of the movable platen 2 with respect to the fixed platen 1.

  In this case, the control device 16B detects the amount of change in the position of the mold clamping housing 3 (the amount of change in the mold clamping force) based on the change in the detection value of the third position sensor 14B, and hereinafter the same as in the first embodiment. The operation can be performed, and the same effect as in the first embodiment can be obtained.

  In the above-described embodiment, the crosshead movement position correcting means is configured by the crosshead position sensor 13 that detects the position of the crosshead 8 relative to the position of the mold clamping housing 3 and the control device 16. Instead of the cross head position sensor 13, the position of the cross head 8 may be corrected by an encoder mounted on the servo motor 15.

  As described above, according to the embodiment of the present invention, the mold clamping force is detected by the position sensor, so that stable detection can be performed for a long time, and the mold clamping force is corrected at the stop position of the crosshead. Since the control is performed, the correction can be performed in a short time, and there is an effect that the stable molding of the product can be continuously performed without affecting the cycle during the automatic operation.

It is a sectional side view of the mold clamping apparatus of the electric injection molding machine of Embodiment 1 of this invention. It is a flowchart which shows the operation | movement of Embodiment 1 of this invention. FIG. 5 is a side sectional view of a mold clamping device of an electric injection molding apparatus showing a second embodiment. FIG. 5 is a side sectional view of a mold clamping device of an electric injection molding apparatus showing a third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fixed board, 2 Movable board, 3 Clamping housing, 4 Fixed metal mold, 5 Movable metal mold, 6 Tie bar, 7 Link mechanism, 8 Cross head, 9 Large pulley, 10 Timing belt, 11 Small pulley, 12 Ball screw, 13 Crosshead position sensor, 14 1st position sensor, 14A 2nd position sensor, 14B 3rd position sensor, 15 servo motor, 16, 16A, 16B control device, 17 servo amplifier, 18 base, 19 ball nut.

Claims (6)

Electric injection in which the mold clamping housing is connected to the movable platen using a link mechanism, the link mechanism is connected by a crosshead, and the movable platen is moved along with the movement of the crosshead to perform mold clamping. In the mold clamping device of the molding machine,
Mold clamping housing position detecting means for detecting the position of the mold clamping housing at the time of mold clamping;
A crosshead movement position correction for calculating the amount of change from the position of the mold clamping housing detected by the mold clamping housing position detecting means and correcting the movement stop position of the crosshead during mold clamping based on the amount of change. And a mold clamping device for an electric injection molding machine. The mold clamping device of the electric injection molding machine according to claim 1,
As the mold clamping housing position detecting means, a first position sensor for detecting a position of the mold clamping housing with respect to a base is provided,
The mold clamping device for an electric injection molding machine, wherein the crosshead movement position correcting means detects a change amount of a mold clamping force based on a change in a detection value of the first position sensor. The mold clamping device of the electric injection molding machine according to claim 1,
As the mold clamping housing position detecting means, a second position sensor for detecting the position of the mold clamping housing with respect to the fixed platen is provided, and the crosshead moving position correcting means is based on a change in a detection value of the second position sensor. A mold clamping device for an electric injection molding machine, wherein the amount of change in mold clamping force is detected. The mold clamping device of the electric injection molding machine according to claim 1,
A third position sensor for detecting the position of the movable platen with respect to the fixed platen is provided as the mold clamping housing position detecting unit, and the crosshead moving position correcting unit is based on a change in a detection value of the third position sensor. A mold clamping device for an electric injection molding machine, wherein a change amount of a mold clamping force is detected. The mold clamping apparatus of the electric injection molding machine according to any one of claims 1 to 4,
The crosshead moving position correcting means is
A crosshead position sensor for detecting the position of the crosshead relative to the position of the mold clamping housing;
A mold clamping device for an electric injection molding machine, comprising: a control device that determines a stop position of the cross head during mold clamping based on a detection value of the cross head position sensor. The mold clamping housing is connected to the movable platen using a link mechanism, the link mechanism is connected by a crosshead, and the movable platen is moved along with the movement of the crosshead. In the mold clamping force control method of the electric injection molding machine adapted to perform clamping,
The mold clamping force set before the start of continuous operation is stored as the position of the mold clamping housing, and a change in the mold clamping force during mold clamping during continuous operation is detected as a change in the position of the mold clamping housing. The electric injection is characterized in that when the position of the clamping housing changes, the crosshead movement stop position at the time of mold clamping is corrected so that the mold clamping force set before the start of continuous operation is obtained. Mold clamping force control method of molding machine.

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