JPS6124423A - Motorized injection device of injection molding machine - Google Patents

Abstract

PURPOSE:To enable to motorize both the plasticization and the injection of resin by a structure wherein means to indicate the pressure of resin and plasticizing torque based upon the electric powers supplied to the respective prime movers are provided. CONSTITUTION:An intermediate shaft 22 is connected to the rear part of an injection molding screw 12 by means of spline. The rear portion of the intermediate shaft 22 has a large diameter and is hollow. In addition, a nut 54 is installed at the rear end of the shaft 22. The screw 12 is axially shifted by rotating a male screw 50, which engages with the threads of the nut 54, by means of a first motor 70. On the other hand, the screw 12 is rotated by means of a second motor 71 by rotatingly driving a shaft 14, onto which a flanged gear 83 brought into mesh with a gear 82 fixed onto the large diametral part of the intermediate shaft 22 is connected through a sliding key 85. The pressure of resin in a cylinder 10 is calculated by detecting the voltage and current of the first motor 70 and the plasticizing torque of the screw 12 is calculated by detecting the voltage and current of the second motor 71. The values of the calculated pressure and torque are indicated on respective indicators.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an electric injection device for an injection molding machine.

(B) Prior Art The injection device of a conventional injection molding machine includes a fully hydraulic type and a hydraulic Φ-electric type. In a fully hydraulic injection device, a hydraulic motor rotates a screw for plasticizing the resin material, and a hydraulic cylinder moves the screw for injecting molten resin.

Further, in a hydraulic/electric injection device, a screw for plasticizing is rotated by an electric motor, and a screw for injection is moved by hydraulic pressure.

(c) Problems to be solved by the invention In any case, the injection device of the conventional injection molding machine as described above uses a hydraulic cylinder, and the packing, sealing member, etc. for electrically sealing high-pressure oil, etc. There are problems in that there are many factors that reduce productivity, such as the need for periodic replacement as they are prone to wear and tear, and operations may have to be stopped due to oil leaking accidents. Ta. Furthermore, since hydraulic equipment is used, there is a limit to the stability of the dimensions and weight of the molded product due to changes in oil temperature, outside temperature, etc. The present invention solves the above-mentioned problems and provides an electric injection molding machine for injection molding machines that eliminates the need for periodic replacement of gaskets, etc., eliminates oil leakage accidents, and allows stable molding. The purpose is to obtain a device and to be able to display resin pressure and plasticizing torque when it is motorized.

B.) Means for Solving the Problems The present invention achieves the above object by electrifying both plasticization and injection and providing a display device that displays resin pressure and plasticization torque based on the power supplied to the electric motor. Achieve. That is, the electric injection device for an injection molding machine according to the present invention includes a first electric motor that can drive a screw in the injection molding machine cylinder in the axial direction via a ball screw mechanism, a second electric motor that can rotationally drive the screw, a first current detection device and a first voltage detection device that respectively detect the current wave υ voltage of the first motor; a second current detection device and a second voltage detection device that respectively detect the current and voltage of the second motor; A first calculation device that calculates the resin pressure in the cylinder based on signals from the first current detection device and the first voltage detection device, a resin pressure display device that displays the calculated resin pressure, and a second current detection device. and a second calculation device that calculates the torque of the screw based on the signal from the second voltage detection device, and a plasticizing torque display device that displays the calculated torque.

(E) Function With the above-described configuration, when the first electric motor is rotated and the second electric motor is stopped, the screw moves forward by the ball screw mechanism and injection can be performed. Also, put the first electric motor in a free rotation state (
When the second electric motor is rotated with the second electric motor (or a small driving force generation state), the screw is rotationally driven, the resin material is plasticized within the cylinder, and the screw is retracted by the resin pressure. Since the resin pressure (during injection and screw retraction) corresponds to the driving torque of the first electric motor, the resin pressure is calculated according to the current and voltage of the first electric motor, and this is displayed on the resin pressure display device. . Moreover, since the plasticizing torque of the screw corresponds to the driving torque of the second electric motor, the plasticizing torque is calculated in correspondence with the current and voltage of the second electric motor, and this is displayed on the plasticizing torque display device.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 and 2 of the accompanying drawings.

A screw 12 is inserted into a cylinder lO of an injection molding machine. A casing 14 is attached to the rear end side (upstream side in the resin flow direction) of the cylinder IO. The casing 14 includes a housing 16 and a cover 18, which define a chamber 20. A rotatable and axially movable intermediate shaft 22 is provided within this chamber 20 . The intermediate shaft 22 has a small diameter shaft portion 24 and a large diameter shaft portion 26 . The tip of the small diameter shaft portion 24 is connected to the screw 12 by a spline. Small diameter shaft part 2
4 is rotatably and axially movably supported by sliding bearings 36 and 38 attached to the housing 16. A nut member 54 having a female thread that constitutes a ball screw mechanism 52 together with a male thread 50 provided on the shaft 48 is fixed to the large diameter shaft portion 26 side of the intermediate shaft 22 . A shaft 48 provided with a male thread 50 is rotatably supported with respect to the cover 18 by a thrust bearing 56 and a bearing 58. The shaft 48 is connected to a first electric motor 70 outside the casing 14 . The first electric motor 70 includes
A first pulse generator 72 is provided. The end of shaft 48 inside housing 14 is supported against the inside diameter of intermediate shaft 22 by a linear 1M motion bearing 75 . The dimension between the bottom of the inner diameter of the intermediate shaft 22 and the tip of the shaft 48 when the intermediate shaft 22 is moved to the leftmost position in FIG. 1 is L as shown. That is, the intermediate shaft 22 can be moved in the axial direction by the maximum dimension. Large diameter shaft of intermediate shaft 22! A driven tooth bundle 82 is attached to the outer periphery of the shaft 2B by a key 81 so as to rotate together with the intermediate shaft 22. Driven gear 82
It meshes with the drive gear 83 with a collar 83a,
This drive gear 83 is connected to a shaft 84 by a sliding key 85. The sliding key 85 has a length that is equal to or larger than the L dimension. The shaft 84 is connected to the housing 16 and the cover 18.
is rotatably supported by bearings 86 and 87. A portion of the shaft 84 that protrudes to the outside of the casing 14 is connected to the second electric motor 71 . The second electric motor 71 is provided with a second pulse generator 73 . Signals from the first pulse generator 72 and second pulse generator 73 described above are input to the control device 100. In addition, the first electric motor 7
The operation of the zero and second electric motors 71 is controlled by electric power from the control device lOO. That is, as shown in Figure 2,
Predetermined electric power is supplied from the drive circuits 102 and 104 of the control device 100 to the first electric motor @70 and the second electric motor 71, respectively. The current and voltage supplied to the first electric motor 70 are determined by the first voltage detection device 106 and the first voltage detection device 108.
are detected by the first current detection device 1.
06 and the first voltage detection device lO8 are input to the il calculation device 110. The signal from the first calculation device 110 is output to the resin pressure display device 112, thereby displaying the resin pressure as described later. The current and voltage to the second electric motor 71 are detected by a second current detection device 114 and a second voltage detection device 116, respectively, and signals from these are input to a second calculation device 118. Second arithmetic device 11
The signal No. 8 is output to the plasticizing torque display device 120, thereby displaying the plasticizing torque as described later.

Next, the operation of this embodiment will be explained. FIG. 1 shows the injection completed state. When the injection is completed, the first electric motor 70 is put into a free rotation state by the control device 100,
Further, the second electric motor 71 is started to rotate. Second
When the shaft 84 is rotated by the electric motor 71, the drive gear 83
The intermediate shaft 22 rotates via the driven gear 82. When the intermediate shaft 22 rotates, the screw 12 connected to it through a spline rotates within the cylinder 10, melting and plasticizing the resin material supplied from the material supply port 10a to the inner diameter of the cylinder 10, (left side in Figure 1). As the molten resin transferred to the front of the cylinder 10 increases, the screw 12 moves backward while rotating (moves to the right in FIG. 1). Therefore, the intermediate shaft 22 also moves to the right in FIG. move in the direction.

Since the shaft 48 is connected to the intermediate shaft 22 by a ball screw mechanism 52, it rotates at a rotational speed that corresponds to the rotation of the intermediate shaft 22, but it cannot rotate at a rotational speed higher than the rotational speed of the intermediate shaft 22. do not have.

Therefore, the nut member 54 rotates relative to the external thread 50 and moves to the right in FIG. In addition, intermediate shaft 2
2, the drive gear 83 moves along the sliding key 85 to follow the intermediate shaft 22 while being engaged with the driven gear 82 due to the action of the collar 83a. In this way, the intermediate shaft 22
When the screw 12 moves by the stroke S, the first electric motor 70 and the second electric motor 71 are activated by the control device 100.
rotation is stopped and the plasticizing stroke is completed.

When the first electric motor 70 and the second electric motor 71 are stopped as described above and the plasticizing stroke is completed, the injection stroke is performed next. That is, the first electric motor [70 is rotated while the second electric motor 71 is stopped. intermediate shaft 22
The nut member 54 integrated therewith is connected to the second electric motor 71 via the driven gear 82, the drive gear 83, and the shaft 84, and therefore cannot rotate. Therefore, when the male thread 50 of the shaft 48 is rotated by the first electric motor 70, the nut member 54 is rotated by the action of the ball screw mechanism 52.
moves to the left in FIG. Therefore, the nut member 54, the intermediate shaft 22, and the screw 12 connected thereto move to the left in FIG. This allows cylinder 1
The resin that has been rotated and melted in the 0 is injected. In addition,
In this case as well, the driving gear 83 moves together with the driven gear 82 following the intermediate shaft 22. In this way, the state shown in FIG. fiS1 is reached again, and the injection stroke is completed. One cycle is completed with the above steps, and the same operation is repeated thereafter. In the end, the first
The screw 12 for injection is driven by the driving force of the electric motor 70.
The second electric motor 71, which rotationally drives the shaft 84, rotates the screw 12 for plasticizing. That is, both the injection operation and the plasticizing operation are motorized and do not require hydraulic drive.

During the above operation, resin pressure and plasticizing torque are displayed as follows. During injection, the first electric motor 70 is activated as described above.
operates, but the current and voltage supplied to the first electric motor 70 are detected by the first current detection device 106 and the first voltage detection device 108, respectively. First computing device 11
0, a signal proportional to the resin pressure on the tip side of the screw 12 is calculated based on the signals from the first current detection device 106 and the voltage detection device 108. The resin pressure exerts a pushing force on the screw 12, and this force corresponds to the torque of the shaft 48 (that is, the driving torque of the first electric motor 70) via the intermediate shaft 22 and the ball screw mechanism 52. Therefore, the first arithmetic unit 110 calculates the driving torque of the first electric motor 70 from the current signal and the voltage signal,
By adding a predetermined calculation to this, a signal corresponding to the resin pressure can be obtained. In this way the first
The signal calculated by the calculation device 110 is sent to the resin pressure display device 112 and displayed. In the above description of the operation, the first electric motor 70 was set in a free rotation state during plasticization, but a relatively small amount of electric power is supplied to the first electric motor 70 during plasticization to generate a plasticization back pressure and stabilize the first electric motor 70. It is also possible to make plasticization possible. In this case, the resin pressure display device 11
The resin pressure indicated by 2 indicates the plasticizing back pressure.

Similarly, the current and voltage of the second electric motor 71 are determined by the second current detection device 114 and the second voltage detection device 11, respectively.
These signals are input to a second calculation unit 118, and a signal corresponding to the plasticizing torque of the screw 12 is calculated in the second calculation unit m118. Since the driving torque of the second electric motor 71 is transmitted to the screw 12 via the shaft 84, the driving gear 83, the driven gear 82, and the intermediate shaft 22, the second electric motor #! A signal corresponding to the torque of the screw 12 can be obtained by calculating the drive torque from the current and voltage of the screw 71 and performing a predetermined calculation on the drive torque. Due to this.

The plasticizing torque is displayed on the plasticizing torque display device 120.

(G) As described in detail, according to the present invention, both the rotation of the screw for plasticizing and the stroke of the screw for injection are motorized, and the resin pressure and plasticizing torque are controlled by the electric current of the electric motor. Since the display is calculated from the pressure and voltage, hydraulic equipment is no longer required, improving the productivity of the injection molding machine.In addition, the resin pressure and plasticizing torque are displayed to the operator, ensuring reliable Operation becomes possible and molding work is facilitated.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an electric injection device of an injection molding machine according to the present invention, and FIG. 2 is a diagram showing a detection device, a calculation device, a display device, etc. 10...Cylinder, 12・Φ・Screw, 22φ・・
Intermediate shaft, 52...ball screw mechanism, 70...φ first electric motor, 71-φ second electric motor, 100φ conflict control device,
106, Φ, first current detection device, 108, first voltage detection device, 110, ff1l calculation device, 112, .
・Resin pressure display device, 114...Φ second current detection device,
116...Second voltage detection device, 118.ψ.Second calculation device, 120.Plasticizing torque display device.

Claims (1)

[Claims] A first electric motor capable of driving a screw in an injection molding machine cylinder in the axial direction via a ball screw mechanism, a second electric motor capable of rotationally driving the screw, and a first electric current that detects the current and voltage of the first electric motor, respectively. A detection device and a first voltage detection device, a second current detection device and a second voltage detection device that respectively detect the current and voltage of the second motor, and based on signals from the first current detection device and the first voltage detection device. a first calculation device that calculates the resin pressure in the cylinder; a resin pressure display device that displays the calculated resin pressure; and a screw torque control device that calculates the screw torque based on signals from the second current detection device and the second voltage detection device. An electric injection device for an injection molding machine including a second calculation device that performs calculations and a plasticizing torque display device that displays the calculated torque.