JP2000117789A - Injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly detect a thrust by connecting a rotary member to a propulsion member under a restraining force to be applied to only a relative movement in the rotating direction and thereby, detecting a load to be generated on the propulsion member through a rotation transmission member which transmits rotation to the propulsion member. SOLUTION: In a heating cylinder 12, a screw 22 is arranged as a propulsion member and an injection member. A through hole 36a is formed almost in the center of a movable plate 36 and a transmission shaft 75 is supported as a rotating member by allowing the shaft 75 to pass almost through the hole 36a. In addition, a bearing box 72 as a bearing retaining member is attached to the front end face of the movable plate 36 through a load cell 71 as an annular load detection means. At the same time, a screw support shaft 38 is supported as a rotation transmission member by the bearing box to transmit the rotation transmitted from the transmission shaft 75 to the screw 22. Further the back end of the screw support shaft 38 is connected to the front end of the transmission shaft 75 in a splined connection fashion in the through hole 36a. The rotation transmission is achieved by the connection between both screw support shaft 38 and transmission shaft 75 in such a way that only their relative movement in the rotating direction is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is injected at a high pressure to fill a cavity space of a mold apparatus.
A molded product can be obtained by cooling and solidifying in the cavity space.

For this purpose, the injection molding machine has a mold clamping device and an injection device. The mold clamping device has a fixed platen and a movable platen, and a mold clamping cylinder advances and retreats the movable platen to form a mold device. Close, close and open the mold. On the other hand, the injection device includes a heating cylinder that heats and melts the resin supplied from the hopper, and an injection nozzle that injects the melted resin, and a screw as a propulsion member is rotatably provided in the heating cylinder. , And are arranged to be able to move forward and backward. Then, the resin is injected from the injection nozzle by moving the screw forward by a driving unit connected to the rear end, and the resin is measured by moving the screw backward by the driving unit.

FIG. 2 is a diagram showing a driving section of a conventional injection device. In the figure, 12 is a heating cylinder, 22 is a screw, and 35 is a fixed plate fixed to a slide table (not shown), and the rear end (right end in the figure) of the heating cylinder 12 is fixed to the fixed plate 35.
A movable plate 36 is provided movably with respect to the fixed plate 35.

The through hole 3 is formed substantially at the center of the movable plate 36.
6a is formed, a bearing box 72 is attached to a front end surface S1 of the movable plate 36 via an annular load cell 71, and a screw support shaft 38 is provided with a bearing 73 disposed in the through hole 36a, Bearing 4 arranged in box 72
1 and 42 are rotatably supported. The screw support shaft 38 extends rearward (to the right in the drawing) through the through hole 36a, a rear end of the screw 22 is fixed to a front end (the left end in the drawing), and a driven pulley is provided at the rear end. 43 is fixed.

A weighing motor (not shown) is attached to a predetermined portion of the movable plate 36, and a drive pulley (not shown) is attached to an output shaft of the weighing motor. A timing belt (not shown) is stretched between them. An injection motor (not shown) is attached to a predetermined portion of the movable plate 36.

In the weighing step, when the weighing motor is driven to retract (move to the right in the drawing) while rotating the screw 22, the resin in the hopper (not shown) falls and falls into the heating cylinder 12. Into
Advances inside the heating cylinder 12 (moves to the left in the figure)
Let me do. A heater (not shown) is provided around the heating cylinder 12 so that the heating cylinder 12 can be heated by the heater and the resin in the heating cylinder 12 can be melted. Therefore,
When the screw 22 is rotated backward by a predetermined distance while rotating, one shot of the melted resin is stored in front of a screw head (not shown).

Next, in the injection step, when the injection motor is driven to advance without rotating the screw 22, the resin stored in front of the screw head is attached to the front end of the heating cylinder 12. It is injected from an injection nozzle (not shown) and filled into a cavity space of a mold device (not shown). The rotation generated by driving the injection motor is transmitted to a ball screw via a pulley, a timing belt, and the like (not shown) to move the movable plate 36 and the screw 22 forward.

As the screw 22 is advanced, a reaction force is generated by the resin in the heating cylinder 12, and the reaction force is generated by the screw 22 and the screw support shaft 38.
Is applied to the load cell 71 as a load. Therefore, the thrust of the screw 22 in the injection process is detected by detecting the load applied to the load cell 71.

[0010]

However, in the conventional injection device, since a timing belt is stretched between the driving pulley and the driven pulley 43, the timing belt is attached to the screw support shaft 38 by the timing belt. A moment is generated in a direction in which the driven pulley 43 is pulled toward the driving pulley, and an eccentric load is applied to the load cell 71.

For example, when the weighing motor is disposed on the top surface of the movable plate 36, the driven pulley 43 is pulled upward by the timing belt, and the counterclockwise moment in FIG. Is generated, and a compressive load is applied to the lower end of the load cell 71.
Therefore, the load applied to the load cell 71 cannot be accurately detected, and the thrust of the screw 22 in the measuring step and the injection step cannot be accurately detected.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional injection device and to provide an injection device capable of accurately detecting the thrust of a propulsion member.

[0013]

For this purpose, in the injection device of the present invention, a rotatable member rotatably disposed;
A transmission means for transmitting the rotation generated by driving the driving means to the rotating member, a propulsion member rotatably and reciprocally disposed, and a relative rotation member and a rotating member. It has a rotation transmitting member connected to restrict only movement and transmitting rotation to the propulsion member, and a load detecting means for detecting a load generated on the propulsion member via the rotation transmission member.

In another injection device of the present invention, the injection device further includes a movable member arranged to be able to advance and retreat, and a bearing holding member attached to the rotation transmitting member via a bearing. The load detecting means is provided between the movable member and the bearing holding member. In still another injection device of the present invention, the rotation member and the rotation transmitting member transmit rotation and are connected by a bendable engagement means.

In still another injection device of the present invention, the load detecting means further comprises an inner ring portion, an outer ring portion, and an intermediate strain (dwarf) portion, and the position of the inner ring portion and the outer ring portion. The load is detected based on the deviation. In still another injection device of the present invention, the load detecting means further regulates a sensor output when detecting a load in a circumferential direction.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a driving unit of the injection device according to the embodiment of the present invention, and FIG. 3 is a sectional view of a main part of the injection device according to the embodiment of the present invention. In FIG. 3, reference numeral 12 denotes a heating cylinder as a cylinder portion, and the heating cylinder 12 has an injection nozzle 12a at a front end (left end in the figure). In the heating cylinder 12, a screw 22 as a propulsion member and an injection member is rotatably arranged and movable back and forth.

The screw 22 has a screw head 22a at the front end, extends rearward (to the right in the drawing) in the heating cylinder 12, and is connected at the rear end (to the right end in the drawing) to a drive unit to be described later. Is done. A spiral flight 23 is formed around the screw 22, and a groove 26 is formed by the flight 23.

A resin supply port 29 is formed at a predetermined position of the heating cylinder 12, and a hopper 30 is fixed to the resin supply port 29. Therefore, the resin 33 stored in the hopper 30 can be supplied to the heating cylinder 12 through the resin supply port 29. The resin supply port 29
In a state where the screw 22 is located at the most forward position (left side in the figure) in the heating cylinder 12,
The groove 26 is formed at a position corresponding to the rear end (the right end in the figure).

Next, the driving section will be described. FIG.
, 12 is a heating cylinder, 22 is a screw, 3
Reference numeral 1 denotes a slide table provided to be able to advance and retreat with respect to a frame (not shown). Reference numeral 34 denotes a fixing plate as a fixing member fixed to the slide table 31. The fixing plate 34 is attached to the rear end of the heating cylinder 12 ( (Right end in the figure) is fixed. Further, the fixing plate 34
Movable plate 36 as a movable member movably with respect to
Is arranged.

The through hole 3 is formed substantially at the center of the movable plate 36.
A transmission shaft 75 as a rotating member is rotatably supported by a pair of bearings 76 as a first bearing. A bearing box 72 as a bearing holding member is attached to a front end surface S1 of the movable plate 36 via a load cell 71 as an annular load detecting means, and a screw support shaft 38 as a rotation transmitting member is provided.
The bearings 41 and 42 as second bearings disposed in the bearing box 72 are rotatably supported and transmit the rotation transmitted from the transmission shaft 75 to the screw 22. The bearing 42 is constituted by a thrust bearing so that it can receive a radiation output applied to the screw 22 at the time of injection.

The screw support shaft 38 extends rearward (to the right in the drawing) through the load cell 71, and the rear end of the screw support shaft 38 and the front end of the transmission shaft 75 are splined in the through hole 36a. Engaged. Therefore, the screw support shaft 38 and the transmission shaft 75 are connected only by restricting relative movement in the rotation direction, and rotation is transmitted between the screw support shaft 38 and the transmission shaft 75, and the screw support shaft 38 and the transmission shaft 75 are transmitted. Axis 75
Is connected to the connection part so that it can bend somewhat. To this end, an engagement hole 75a is formed at the front end (left end in the figure) of the transmission shaft 75, a spline groove is formed on the inner peripheral surface of the engagement hole 75a, and the screw support shaft 3 is formed.
8, spline teeth are formed on the outer peripheral surface at the rear end. Also,
The driven pulley 43 is fixed at the rear end of the transmission shaft 75.
The engagement means is constituted by the spline grooves and the spline teeth.

Further, the rear end of the screw 22 and the front end of the screw support shaft 38 are spline-engaged. Therefore, rotation is transmitted between the screw 22 and the screw support shaft 38. For this purpose, an engaging hole 38a is formed at the front end of the screw support shaft 38, a spline groove is formed on the inner peripheral surface of the engaging hole 38a, and a spline tooth is formed on the outer peripheral surface of the rear end of the screw 22. It is formed.

Further, a predetermined portion of the movable plate 36,
For example, a weighing motor (not shown) as driving means is mounted on the top surface S2, a driving pulley is mounted on an output shaft of the weighing motor, and a timing belt is provided between the driving pulley and the driven pulley 43. It is stretched. In addition, a servomotor can be used as the weighing motor. In addition, the weighing motor, the driving pulley, the timing belt, and the driven pulley 43 make the first
Transmission means is constituted.

The ball screw shafts 45 are supported by bearings 46 at a plurality of positions on the periphery of the movable plate 36, for example, at two positions, in parallel with each other and rotatably. The ball screw shaft 45 includes a screw portion 48,
And a shaft 49 formed at the rear end (right end in the figure).
The shaft portion 49 extends rearward through a hole 36b formed in the movable plate 36, and is driven by the driven pulley 5 at the rear end.
1 is attached. On the other hand, the screw portion 48 extends forward (to the left in the drawing) through a hole 34 a formed in the fixed plate 34, and is screwed with a ball nut 52 attached to the fixed plate 34. The ball nut 5
2 is provided with a flange 53 at the front end.
The ball nut 52 is fixed to the fixing plate 34 by a bolt (not shown) that penetrates the ball nut 52. The ball screw shaft 45 and the ball nut 52 constitute conversion means for converting the rotational force transmitted to the ball screw shaft 45 into a thrust. Reference numeral 55 denotes a holding plate for holding the bearing 46.

Further, an injection motor (not shown) as driving means is attached to a predetermined portion of the movable plate 36, and a drive pulley (not shown) is attached to an output shaft of the injection motor. A timing belt (not shown) is stretched between the pulley 51 and the pulley 51. Note that a servomotor can be used as the injection motor. The injection motor, the driving pulley, the timing belt and the driven pulley 51 constitute a second transmission means.

In the present embodiment, the ball screw shaft 45 is rotatably provided on the movable plate 36 and the ball nut 52 is fixed on the fixed plate 34. The ball nut may be fixed and the ball screw shaft may be rotatably provided on the fixing plate 34. In that case, the injection motor is attached to a predetermined portion of the fixed plate 34.

In the weighing step, when the weighing motor is driven, the rotation generated by the weighing motor is transmitted to the transmission shaft 75 via the driving pulley, the timing belt and the driven pulley 43. The power is transmitted to the screw 22 via the screw support shaft 38. When the screw 22 is rotated backward (moved to the right in the figure) while rotating, the resin 33 in the hopper 30 (FIG. 3) falls and enters the heating cylinder 12, It is moved forward (moved to the left in the figure).

A heater (not shown) is provided around the heating cylinder 12, and heats the heating cylinder 12 by the heater.
Can be melted. Therefore, when the screw 22 is rotated backward by a predetermined distance while rotating, one shot of the melted resin 33 is stored in front of the screw head 22a.

Next, in the injection step, when the injection motor is driven, the rotation generated by the injection motor is transmitted to the ball screw shaft 45 via the drive pulley, the timing belt and the driven pulley 51. Is done. Then, with the rotation of the ball screw shaft 45, the movable plate 36 is advanced. At this time, since the weighing motor is not driven, the screw 22 can be advanced without rotating, and the screw head 2 can be moved forward.
The resin 33 stored in front of the injection nozzle 1a
It is injected from 2a and is filled in a cavity space of a mold device (not shown).

As the screw 22 advances, a reaction force is generated by the resin 33 in the heating cylinder 12, and the reaction force is applied as a load to the load cell 71 via the screw 22 and the screw support shaft 38. .
Therefore, the thrust of the screw 22 in the injection process is detected by detecting the load applied to the load cell 71.

The load cell 71 has a thick inner ring portion 8.
1. Thick outer ring 82, inner ring 81 and outer ring 8
2 and a thin intermediate strain member 83 which is integrally formed of an elastic material.
3 are provided with a plurality of strain gauges (not shown). The inner ring portion 81 has a smaller diameter than the outer ring portion 82, the rear end of the bearing box 72 and the front end of the inner ring portion 81 are fixed to each other, and the rear end of the outer ring portion 82 and the movable plate 36 The front ends are fixed to each other.

Here, when a load is applied to the load cell 71, the load cell 71 is deformed according to the magnitude of the load, and a positional deviation occurs between the inner ring portion 81 and the outer ring portion 82. At this time, a sensor output is generated by the strain gauge, and the sensor output is sent to a control device (not shown) as a detection signal. In addition, when the screw support shaft 38 is rotated together with the screw 22 in a measuring process or the like, a load in the circumferential direction is applied to the load cell 71. The load cell 71 outputs a sensor output when detecting the load in the circumferential direction. Because of the regulation, no sensor output is generated.

Since a timing belt is stretched between the driving pulley and the driven pulley 43, a moment is applied to the transmission shaft 75 in a direction in which the driven pulley 43 is pulled toward the driving pulley by the timing belt. appear. In the present embodiment, since the weighing motor is disposed on the top surface S2, the driven pulley 43 is pulled upward by the timing belt, and the transmission shaft 75 has A surrounding moment is generated.

However, the rear end of the screw support shaft 38 and the front end of the transmission shaft 75 are spline-engaged in the through hole 36a, and a clearance is formed between the spline teeth and the spline groove. The axis of the shaft 38 and the axis of the transmission shaft 75 are relatively slightly inclined. Therefore, the moment generated on the transmission shaft 75 is absorbed by the spline engagement and is not transmitted to the screw support shaft 38.

As a result, since an unbalanced load is not applied to the load cell 71, the load applied to the load cell 71 can be accurately detected, and the thrust of the screw 22 in the injection process can be accurately detected. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention.
They are not excluded from the scope of the invention.

[0036]

As described in detail above, according to the present invention, in the injection device, the rotation member rotatably disposed and the rotation generated by driving the driving means are rotated by the rotation. A transmission means for transmitting to the member, a propulsion member rotatably and freely reciprocally disposed, and coupled only by restricting relative movement in the rotational direction with the rotation member, to rotate the propulsion member. A rotation transmitting member for transmitting the load; and load detecting means for detecting a load generated on the propulsion member via the rotation transmitting member.

In this case, the rotation generated by driving the driving means is transmitted to the rotating member by the transmission means. Then, a load generated as the propulsion member advances is detected by the load detecting means. A moment is generated in the rotating member by the transmission means,
Since only the relative movement of the rotation member and the rotation transmission member in the rotation direction is restricted, the moment is absorbed and is not transmitted to the rotation transmission member.

Therefore, since an unbalanced load is not applied to the load detecting means, the load can be accurately detected, and the thrust of the propulsion member in the injection process can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a driving unit of an injection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a driving unit of a conventional injection device.

FIG. 3 is a sectional view of a main part of the injection device according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 22 screw 36 movable plate 38 screw support shaft 41, 42 bearing 43 driven pulley 71 load cell 72 bearing box 75 transmission shaft 75a engagement hole 81 inner ring part 82 outer ring part 83 intermediate strain part

Claims (5)

[Claims] (A) a rotating member rotatably disposed; (b) a transmission means for transmitting rotation generated by driving a driving means to the rotating member; and (c).
A propulsion member rotatably and freely movable forward and backward,
(D) a rotation transmitting member which is coupled to the rotating member by restricting only relative movement in a rotational direction and transmits rotation to the propulsion member; and (e) a rotation transmission member for transmitting a load generated on the propulsion member. And a load detecting means for detecting the load via the injection device. And (b) a bearing holding member attached to the rotation transmitting member via a bearing, and (c) the load detecting means. The injection device according to claim 1, wherein the injection device is provided between the movable member and the bearing holding member. 3. The injection device according to claim 1, wherein the rotation member and the rotation transmitting member transmit rotation and are connected by a bendable engagement means. 4. The load detecting device according to claim 1, wherein the load detecting means includes an inner ring portion, an outer ring portion, and an intermediate strain portion, and detects a load based on a positional deviation between the inner ring portion and the outer ring portion. Injection device. 5. The injection device according to claim 1, wherein the load detecting means regulates a sensor output when detecting a load in a circumferential direction.