JP2000280310A - Mold clamping device for injection-molding machine, injection device and method for controlling this device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily measure and control a mold clamping force or an injection pressure by interposing an annular element for measuring the mold clamping force between a fixed platen and a tie-bar nut. SOLUTION: A movable platen 2 is arranged opposite to a fixed platen 1, and a mold clamping housing 3 is arranged on the left of the movable platen 2 and at the same time, a half mold 4 is mounted on the fixed platen 1 and the movable platen 2 respectively. In addition, four tie-bars 5 are arranged penetrating through the fixed platen 1, the movable platen 2 and the mold clamping housing 3, and the position of the mold clamping housing 3 is set to the fixed platen 1 by tie-bar nuts 6 screwed into both ends of the tie-bars 5. Further, an annular element 11 for measuring a mold clamping force is structurally held between the fixed platen 1 and the tie-bar nut 6 so that the amount of deformation of the annular element 11 can be measured using a strain gauge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device and an injection device for an injection molding machine having a measuring device for measuring a mold clamping force or an injection pressure, and a control method therefor.

[0002]

2. Description of the Related Art In a conventional mold clamping device of an injection molding machine, a position of a cross head fastened to a mold clamping hydraulic cylinder or a ball screw is detected by a position detecting encoder, and the position of a mold clamping force is controlled. Had been In addition, in a conventional electric injection device of an injection molding machine, as shown in FIG.
The injection pressure is measured and controlled by arranging between the thrust ball bearing 45 and the angular ball bearing 46 in the intermediate plate 44 in which the output shaft 43 to which the 2 is screwed is rotatably mounted. Was. Further, a tie bar sensor is attached to the outer periphery of the tie bar to measure and control the mold clamping force.

[0003]

In the conventional method for detecting the position of the crosshead, depending on the temperature adjustment of the mold,
The heat applied to the mold is transmitted to the tie bar via the fixed platen and the movable platen, and the thermal expansion of the tie bar causes variations in the mold clamping force. Further, since the mold clamping force is controlled only by the position of the crosshead, it is not possible to cope with disturbance due to a temperature change.

In the method of disposing an annular body, the shaft of the ball screw becomes thicker as the model becomes larger, and the annular body must be enlarged to prevent interference with the shaft of the ball screw. For this reason, the annular body is special and expensive. Further, since the annular body is provided in the intermediate plate, replacement and maintenance of the annular body are troublesome, and wiring of the annular body cannot be easily performed.

[0005] In the method of attaching the tie bar sensor to the outer periphery of the tie bar, it is necessary to secure a space around the tie bar when the tie bar is fixed. Further, since the tie bar sensor is expensive, there is a case where a system is constructed by reducing the cost by substituting two or one of the four tie bars, but there is a problem in reliability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a mold clamping apparatus and an injection apparatus for an injection molding machine capable of easily measuring and controlling a mold clamping force or an injection pressure, and an apparatus therefor. It is an object to provide a control method.

[0007]

A mold clamping apparatus for an injection molding machine according to the present invention has an annular body for measuring a mold clamping force interposed between a fixed platen and a tie bar nut.

The injection device of the injection molding machine according to the present invention comprises a fixed plate on which an injection cylinder is fixed or a rear plate rotatably supporting a ball screw for moving a screw back and forth, and a screw at both ends of a guide bar. An annular body for measuring the injection pressure is interposed between the combined nuts.

[0009] The actual clamping force and the actual injection pressure during molding can be measured by the annular body. Further, closed control can be performed based on the measured value.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings.

FIG. 1 is an overall configuration diagram of a mold clamping device of an injection molding machine according to a first embodiment of the present invention. As shown in FIG. 1, a movable platen 2 is disposed opposite to a fixed platen 1,
The mold clamping housing 3 is arranged on the left side in FIG. Half molds 4 are attached to the fixed platen 1 and the movable platen 2, respectively.

Four tie bars 5 are disposed through the fixed board 1, the movable board 2, and the mold clamping housing 3, and
The positions of the mold clamping housing 3 with respect to the fixed platen 1 are determined by the tie bar nuts 6 screwed to both ends of the mold. A toggle device 12 connected to the crosshead 7 to move the movable platen 2 back and forth is provided in the mold clamping housing 3 and the movable platen 2.
Are connected.

The crosshead 7 has a ball nut 8
Is fixed, and a ball screw 9 screwed into the ball nut 8 is rotatably supported by the mold clamping housing 3 and is rotated by a mold opening / closing motor (not shown). The crosshead 7 may be moved back and forth by a mold clamping hydraulic cylinder. The crosshead 7 has a crosshead 7
Is mounted.

In the present invention, an annular body 11 for measuring a mold clamping force is sandwiched between the fixed platen 1 and the tie bar nut 6. The annular body 11 is configured so that the deformation amount can be measured by a strain gauge. The annular body 11 is provided with all the tie bars 5 according to the mold clamping device to be applied.
May be provided, or only one tie bar 5 may be provided. Since this annular body 11 is provided on the tie bar 5, it does not become a large and special one.

Next, the operation of the mold clamping device will be described.

The crosshead 7 is driven by the thrust of the ball screw 9.
Move forward, the movable platen 2 moves along the tie bar 5, and after the touch of the mold, a mold clamping step is performed. At this time, the tie bar 5 receives the reaction force of the mold clamping, and the fixed platen 1 fixed to the tie bar 5 by the tie bar nut 6 is slightly displaced. The annular body 11 sandwiched between the fixed platen 1 and the tie bar nut 6 electrically measures this displacement and measures the mold clamping force. The initial compression force acts when the annular body 11 is sandwiched between the tie bar nuts 6, but this can be solved by providing an electrical offset.

During continuous operation molding, the mold clamping device is always subjected to a temperature disturbance due to the influence of a mold temperature controller and a change in outside air temperature. Since the tie bar 5 is metallic, mechanical characteristics such as elongation change due to a temperature disturbance, and finally, the mold clamping force also changes according to the temperature change. In the present invention, the amount of strain of the tie bar 5 is electrically detected by the annular body 11 and the mold clamping force including the variation due to the disturbance is closed-controlled, so that the mold clamping can be performed accurately and accurately even in an environment where temperature disturbance occurs. Can generate force.

Hereinafter, a method of controlling the mold clamping force by changing the position of the crosshead conventionally used each time according to the amount of disturbance change detected by the annular body 11 will be described.

FIG. 2 shows a state in which the tie bar elongation amount (= clamping force) has an error from normal due to thermal disturbance or the like.

FIG. 3 is a mold clamping force table showing the relative relationship between the mold clamping force and the crosshead position. Conventionally, the mold clamping force was controlled by the position only using this table.

FIG. 4 is a flowchart showing a mold clamping control method.

As shown in FIG. 4, the mold clamping force is measured by an annular body 11 which is a load cell, and when an error as shown in FIG. 2 occurs, the actual mold clamping force becomes a normal mold clamping force. And the process moves to the next cycle. The sampling of the mold clamping force can be set according to the purpose, such as every shot, once every 10 shots. In this way, by performing closed control of the mold clamping force, a stable mold clamping force can always be generated.

FIG. 5 is an overall configuration diagram of an injection device of an injection molding machine according to a second embodiment of the present invention.

As shown in the figure, an intermediate plate 22 is disposed behind the fixed plate 21 (right side in the figure), and behind the intermediate plate 22 (right side in the figure), a rear plate 23 is provided.
Is arranged. An injection cylinder 24 is fixed to the fixed plate 21.
Is supported so that it can move back and forth and rotate. Intermediate plate 2
An output shaft 27 to which a screw rotation pulley 26 is attached is rotatably attached via an angular ball bearing 28 to a front portion of the device 2, and a ball nut 29 is attached to a rear portion of the output shaft 27. A ball screw 30 screwed with the ball nut 29 is rotatably supported on the rear plate 23, and an injection pulley 31 is attached to an end of the ball screw 30.

The fixed plate 21 and the intermediate plate 22
A guide bar 32 is disposed through the rear plate 23 and the fixed plate 21 and the rear plate 23 are connected by nuts 33 screwed to both ends of the guide bar 32, respectively.

In the present invention, an annular body 34 for measuring the injection pressure is interposed between the fixed plate 21 or the rear plate 23 and the nut 33. This annular body 34
Is configured such that the deformation amount can be measured by a strain gauge. The annular body 34 may be provided on all of the guide bars 32 or may be provided on only one guide bar 32, depending on the injection device to be applied. Since the annular body 34 is provided on the guide bar 32, it is not a large and special one.

Next, the operation of the injection device will be described.

When the injection pulley 31 is driven and rotated by an injection servomotor (not shown), the ball screw 30 rotates and the ball nut 29 screwed thereto moves, and the intermediate plate 22 is pressed and pulled back. 22
Moves along the guide bar 32, and at the same time, the screw 2 is rotated by the output shaft 27 mounted via the angular ball bearing 28.
5 moves forward and backward, and the injection stroke is performed. At this time, the guide bar 32 receives the reaction force of the injection, and the fixing plate 21 fixed to the guide bar 32 by the nut 33 is slightly displaced. The annular body 34 sandwiched between the fixed plate 21 and the nut 33 electrically measures this displacement and measures the injection pressure. Note that the initial compression force acts when the annular body 34 is sandwiched between the nuts 33, but this can be solved by having an electrical offset.

In the present embodiment, similarly to the first embodiment, the injection pressure is detected by the annular body 34 as a load cell, and the injection pressure is closed-controlled, so that a stable injection pressure can always be generated. .

[0030]

According to the annular body for measuring the mold clamping force and the injection pressure according to the present invention, (a) the actual mold clamping force and the actual injection pressure can be monitored. (B) The mold clamping force and the injection pressure can be controlled stably and accurately with respect to disturbance due to a temperature change of the mold clamping device and the injection device. (C) Since the ring-shaped load cell is inexpensive as compared with a commercially available tie bar sensor, incorporating it into all four tie bars improves the reliability of the system. (D) Variations in the weight of the molded product due to changes in the mold clamping force and the injection pressure can be suppressed, and an improvement in productivity due to a reduced product defect rate can be expected. (E) Since the annular body is fitted to the tie bar and the guide bar and fastened with a nut to a fixed plate or the like, the annular body can be designed compactly, and its mounting method is versatile.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a mold clamping device of an injection molding machine according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a tie bar elongation amount has an error from normal due to a thermal disturbance or the like.

FIG. 3 is a mold clamping force table showing a relative relationship between a mold clamping force and a crosshead position.

FIG. 4 is a flowchart illustrating a mold clamping control method.

FIG. 5 is an overall configuration diagram of an injection device of an injection molding machine according to a second embodiment of the present invention.

FIG. 6 is an overall configuration diagram of an injection device of a conventional injection molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed board 2 Movable board 3 Mold clamping housing 4 Die 5 Tie bar 6 Tie bar nut 7 Cross head 8 Ball nut 9 Ball screw 10 Encoder 11 Annular body 12 Toggle device 21 Fixing plate 22 Intermediate plate 23 Back plate 24 Injection cylinder 25 Screw 26 Screw Rotary pulley 27 Output shaft 28 Angular contact ball bearing 29 Ball nut 30 Ball screw 31 Injection pulley 32 Guide bar 33 Nut 34 Ring

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F202 AP02 AQ03 AR02 CA11 CB01 CL39 CL44 4F206 AP022 AP027 AQ03 AR024 JA07 JP11 JP17 JT01 JT05 JT38

Claims (4)

[Claims] A tie bar (5) is disposed through a fixed plate (1), a movable plate (2) and a mold clamping housing (3), and a tie bar nut screwed to both ends of the tie bar (5). In the mold clamping device of the injection molding machine in which the fixed plate (1) and the mold clamping housing (3) are connected by (6), the mold clamping force is measured between the fixed plate (1) and the tie bar nut (6). A mold clamping device for an injection molding machine, wherein an annular body (11) is interposed. 2. A fixed plate (21) to which an injection cylinder (24) is fixed, and an intermediate plate to which an output shaft (27) is rotatably mounted at a front portion and a ball nut (29) is mounted at a rear portion. (22) and a back plate (23) rotatably supporting a ball screw (30) screwed with the ball nut (29), a guide bar (32) is arranged, and the guide bar (32) is arranged. In an injection device in which the fixed plate (21) and the rear plate (23) are connected by nuts (33) screwed to both ends of the fixed plate (21) or the rear plate (23) and the nut (33). An injection device for an injection molding machine, characterized in that an annular body (34) for measuring an injection pressure is interposed between the injection members. 3. A tie bar (5) is disposed through the fixed plate (1), the movable plate (2) and the clamping housing (3), and a tie bar nut screwed to both ends of the tie bar (5). In the control method of the mold clamping device of the injection molding machine in which the fixed plate (1) and the mold clamping housing (3) are connected by (6), the fixed plate (1) and the tie bar nut (6) are interposed. By the annular body (11) for measuring the mold clamping force,
A method for controlling a mold clamping device of an injection molding machine, wherein a strain amount of a tie bar (5) is electrically detected, and a mold clamping force is closed-controlled based on the detected value. 4. A fixed plate (21) to which an injection cylinder (24) is fixed, and an intermediate plate having an output shaft (27) rotatably mounted at a front portion and a ball nut (29) mounted at a rear portion. (22) and a back plate (23) rotatably supporting a ball screw (30) screwed with the ball nut (29), a guide bar (32) is arranged, and the guide bar (32) is arranged. 32) In a control method of an injection device in which the fixed plate (21) and the rear plate (23) are connected by nuts (33) screwed to both ends of the injection plate, the fixed plate (21) or the rear plate (23) is connected. The annular body (34) for measuring the injection pressure interposed between the nuts (33) electrically detects the amount of distortion of the guide bar (32), and closes the mold clamping force based on the detected value. A method for controlling an injection device of an injection molding machine, comprising: