JP3140996B2 - Injection device of electric injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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, filled into a cavity space of a mold, and cooled in the cavity space. After solidification, the mold is opened and the molded product is taken out.

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 moves the movable platen forward and backward to move the mold. It has become. on the other hand,
The injection device includes a heating cylinder for heating and melting the resin supplied from the hopper, and an injection nozzle for injecting the melted resin, and a screw is disposed in the heating cylinder so as to be able to move forward and backward. And the screw,
By moving the resin forward, the resin can be injected, and by moving the resin backward, measurement can be performed.

Meanwhile, there has been provided an electric injection molding machine using an electric motor for moving the injection device forward and backward and for moving the screw forward and backward. FIG. 2 is a schematic view of an injection device in a conventional electric injection molding machine. In the figure, reference numeral 2 denotes an injection device, and 4 denotes an injection device frame. A heating cylinder 21 is fixed in front of the injection device frame 4 (to the left in the figure), and an injection nozzle 21a is arranged at the tip of the heating cylinder 21. Is established. A hopper 21b is provided in the heating cylinder 21, and a screw 20 is provided in the heating cylinder 21 so as to be able to advance and retreat and rotate freely, and the rear end of the screw 20 is rotatable by the support member 5. Supported by

[0005] A first servomotor 6 is attached to the support member 5, and the rotation of the first servomotor 6 is transmitted to the screw 20 via a timing belt 7a. In addition, the injection device frame 4 includes:
A screw shaft 8 is rotatably supported in parallel with the screw 20, and a rear end of the screw shaft 8 is a timing belt 7b.
Is connected to a second servomotor 9 so that the screw shaft 8 can be rotated by the second servomotor 9. The front end of the screw shaft 8 is screwed with a nut 5a fixed to the support member 5.
Therefore, the nut 5a can be moved in the axial direction by driving the second servomotor 9 and rotating the screw shaft 8 via the timing belt 7b.

Next, the operation of the injection device 2 having the above configuration will be described. First, in the measuring step, the first servomotor 6 is driven, the screw 20 is rotated via the timing belt 7a, and the screw 20 is retracted by a predetermined amount. At this time, the resin supplied from the hopper 21b is heated and melted in the heating cylinder 21, and is stored (stored) in front of the screw 20 (left side in the figure) as the screw 20 retreats.

Next, in the injection step, the injection nozzle 21a is pressed against a mold (not shown), the second servomotor 9 is driven, and the screw shaft 8 is driven via the timing belt 7b.
To rotate. At this time, the support member 5 is moved with the rotation of the screw shaft 8 and advances the screw 20, so that the resin stored in front of the screw 20 is injected from the injection nozzle 21a.

FIG. 3 is a schematic view of another injection device in a conventional electric injection molding machine. In the figure, 2 is an injection device,
Reference numeral 4 denotes an injection device frame. A heating cylinder 21 is fixed in front of the injection device frame 4 (to the left in the drawing), and an injection nozzle (not shown) is provided at a tip of the heating cylinder 21. A screw 20 is provided in the heating cylinder 21 so as to be able to advance and retreat and rotate freely. A ball screw 31 is formed at the rear end of the screw 20, and a spline 32 is formed at the rear end of the ball screw 31. You.

The injection unit frame 4 is provided with an injection through-type motor 34 corresponding to the ball screw 31. A ball screw nut 37 and the injection through-type motor 34 are fixed, and the spline A metering penetrating motor 35 is provided corresponding to 32, and the spline nut 38 and the metering penetrating motor 35 are fixed. An NC controller 39 is connected to the injection penetrating motor 34 and the metering penetrating motor 35, and the NC controller 39 selectively rotates the injection penetrating motor 34 and the metering penetrating motor 35. By doing so, injection and metering can be performed. That is, in the measuring process, the spline 32, the ball screw 31, and the screw 20 rotate to perform the measurement by rotating the penetrating motor 35 for measurement and simultaneously rotating the penetrating motor 34 for injection at the same rotational speed. Will be At this time, the supply of electric power to the injection penetrating motor 34 is adjusted, and the screw 20 is retracted by providing a rotational speed difference between the ball screw nut 37 and the spline nut 38, thereby controlling the back pressure during measurement. It can be performed.

Further, in the injection step, when the injection penetrating motor 34 is rotated to prevent the metering penetrating motor 35 from rotating, the ball screw 31 is advanced by the rotation of the ball screw nut 37. As a result, screw 2
Zero is also advanced and injection is performed.

[0011]

However, in the injection device of the conventional electric injection molding machine, the timing belts 7a and 7b are used in the case of the injection device shown in FIG. Not only occurs, but also because the first servomotor 6 and the second servomotor 9 are not arranged on the same axis as the screw 20, the injection device becomes large. And the timing belt 7
a and 7b are worn, so that the maintenance and management of the injection device is troublesome.
The control accuracy of the position and the like is reduced. Further, the first
Since the servo motor 6 moves back and forth with the screw 20,
The reliability of the motor wiring and the like will be reduced.

In the case of the injection device shown in FIG. 3, the ball screw 31 and the spline 32 are integrated, and the ball screw nut 37 screwed with the ball screw 31 is rotated by the injection penetrating motor 34 to generate the spline. A spline nut 38 connected to the spline 32 by a spline is rotated by a penetrating motor 35 for measurement. Then, for example, when performing weighing, the injection penetrating motor 34
The back pressure is applied to the screw 20 by increasing the rotation speed of the screw 20 and decreasing the rotation speed of the penetrating motor 35 for measurement. For this purpose, it is necessary to operate the penetrating motor 35 for measurement and the penetrating motor 34 for injection in synchronization, and it is difficult to control the penetrating motor 35 for measurement and the penetrating motor 34 for injection, and it is difficult to control the back pressure. Will decrease.

When the injection is performed, the ball screw nut 37 is rotated, so that the rotational inertia of the drive unit becomes large, and the controllability such as speed rise is poor. Further, at this time, since the measuring penetrating motor 35 restricts the rotational movement of the screw 20, a force equivalent to the rotational force at the time of injection is generated to maintain the position of the screw 20. Therefore, the capacity of the penetrating motor 35 for measurement increases.

The present invention solves the above-mentioned problems of the injection device of the conventional electric injection molding machine, facilitates maintenance and management, and can improve control accuracy of speed, position, back pressure, and the like.
An object of the present invention is to provide an injection device of an electric injection molding machine that can easily control a motor.

[0015]

For this purpose, in the injection apparatus of the electric injection molding machine according to the present invention, a drive unit case,
An injection motor disposed on the same axis as the screw in the drive unit case, and a movement coupled between the injection motor and the screw for converting a rotational motion into a linear motion and for moving the screw forward and backward. Direction changing means, a weighing motor disposed in the drive unit case, and connected between the weighing motor and the screw to restrain relative movement in the rotational direction and to perform relative movement in the axial direction. A first driving force transmitting means for permitting a movement, and a second driving force transmission means connected between the driving unit case and the screw for restraining relative movement in a rotational direction and permitting relative movement in an axial direction. A third driving force transmitting means connected between the driving force transmitting means and the movement direction converting means and the screw, for restraining relative movement in the axial direction and allowing relative movement in the rotating direction; With the door.

[0016]

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram of a drive unit of an electric injection molding machine according to an embodiment of the present invention,
FIG. 4 is a schematic diagram of a heating cylinder of the electric injection molding machine according to the embodiment of the present invention. In FIG. 4, reference numeral 12 denotes a heating cylinder, and the heating cylinder 12 has an injection nozzle 12a at a tip (left side in the figure). A screw 22 is provided in the heating cylinder 12 so as to be able to advance and retreat and rotate freely.

The screw 22 has a screw head 22a at the tip, extends rearward (to the right in the drawing) in the heating cylinder 12, and is connected at the rear end to a drive unit described later. A spiral flight 23 is formed around the screw 22, and a groove 26 is formed between the flights 23. A resin supply port 29 is formed at a set location of the heating cylinder 12, and a hopper 30 is fixed to the resin supply port 29. The resin supply port 29 connects the screw 22 to the heating cylinder 12.
In the state of being located at the forefront (left side in the figure) of the inside, it is formed at a position corresponding to the rear end of the groove 26.

Therefore, in the measuring step, when the driving section is driven to retract the screw 22 while rotating, the pellet-shaped resin 33 in the hopper 30 falls and enters the heating cylinder 12, The groove 26 is advanced. A heater (not shown) is provided around the heating cylinder 12 so that the heating cylinder 12 can be heated by the heater to melt the resin 33 in the groove 26. Therefore, when the screw 22 is rotated backward by a predetermined amount, one shot of the melted resin 33 is stored in front of the screw head 22a.

Next, in the injection step, when the driving unit is driven to advance without rotating the screw 22, the resin 33 stored in front of the screw head 22a is injected from the injection nozzle 12a. It is filled in a cavity space of a mold (not shown). Next, the driving unit will be described.

In FIG. 1, reference numeral 11 denotes a drive unit case surrounding the drive unit. The drive unit case 11 is fixed to the rear of the heating cylinder 12 (to the right in the figure). The drive unit case 11 includes a front cover 13, a front support 14, a center support 15, a rear support 16, a rear cover 17, a front frame 41 connecting the front support 14 and the center support 15, and the center support 15 and a rear support. And a rear frame 42 connecting the front frame 16 and the rear frame 16. And the front cover 1
3 and the front support 14 are fixed by bolts 18, and the rear support 16 and the rear cover 17 are fixed by bolts 19, respectively.

A metering motor 44 is provided on the front part of the drive unit case 11 and an injection motor 45 is provided on the rear part thereof on the same axis. The metering motor 44 includes a stator 46 fixed to the front frame 41, and a rotor 47 disposed on the inner peripheral side of the stator 46, and an injection motor 45 includes a stator 48 fixed to the rear frame 42. , And a rotor 49 disposed on the inner peripheral side of the stator 48.

The rotor 47 is rotatably supported by the drive case 11. For this purpose, a hollow first rotor shaft 56 is fitted and fixed to the rotor 47, and the front end of the first rotor shaft 56 is attached to the front support 14 by the bearing 51, and the rear end is attached to the center support 15 by the bearing 52. Supported by On the other hand, the rotor 49 is also rotatably supported by the drive unit case 11. Therefore, a hollow second
The rotor shaft 57 is fitted and fixed. The front end of the second rotor shaft 57 is supported by the center support 15 by the bearing 53, and the rear end of the second rotor shaft 57 is supported by the rear support 16 by the bearing 54.

By supplying a current of a predetermined frequency to the stator 46 of the metering motor 44, the screw 22 (FIG. 4) can be moved backward while rotating. To this end, a first spline nut 62 is fixed to the inner periphery of the front end of the first rotor shaft 56, the first spline nut 62 and the first spline shaft 63 are spline-connected, and the front end of the first spline shaft 63 is , The screw 22 is fixed. In this case, the first spline nut 62 and the first spline shaft 63 constitute a first driving force transmitting means, and the relative movement in the rotational direction is restricted, and the relative movement in the axial direction is allowed. You. The first spline shaft 63 has a length corresponding to the stroke of the screw 22.

Therefore, when the metering motor 44 is driven to rotate the rotor 47, the rotation of the rotor 47 is transmitted to the screw 22 via the first rotor shaft 56, the first spline nut 62 and the first spline shaft 63. Then, the screw 22 is rotated. And the groove 2
6, the resin 33 moves forward while being melted.
The screw 22 is caused to retreat by a back pressure generated with the advance of the screw 22.

At this time, since the first spline nut 62 and the first spline shaft 63 are spline-connected, the first spline shaft 63 is retracted relatively to the first spline nut 62. On the other hand, in the injection motor 45, the screw 22 can be advanced by supplying a current of a predetermined frequency to the stator 48. For this purpose, an annular bearing retainer 64 is fixed to the rear end of the second rotor shaft 57, and a ball screw shaft 6 is mounted on the inner periphery of the bearing retainer 64.
5 is fitted and fixed. And the ball screw shaft 6
5 is rotatably supported by the drive unit case 11.
That is, the ball screw shaft 65 is connected to the bearing retainer 6.
4, and is supported by the rear cover 17 by a bearing 66 disposed rearward (to the right in the drawing) of the bearing 66.

A ball nut 69 is provided in the second rotor shaft 57 so as to be able to move forward and backward. The ball nut 69 and the ball screw shaft 65 are screwed together to constitute a movement direction changing means. Therefore, the rotor 4
The rotation of No. 9 is transmitted to the ball screw shaft 65 via the second rotor shaft 57 and the bearing retainer 64, and the rotational motion is converted into a linear motion to move the ball nut 69 forward and backward. At this time, the ball nut 69 is
So that it does not rotate with the ball nut 6
9, a second spline shaft 71 is fixed to the front end, and a second spline nut 76 fixed to the center support 15 is provided.
And the second spline shaft 71 are spline-connected. In this case, the second spline nut 76 and the second spline shaft 71 constitute a second driving force transmission unit, and the relative movement in the rotation direction is restricted, and the relative movement in the axial direction is allowed. The second spline shaft 71 has a length corresponding to the stroke of the screw 22.

A bearing box 72 as a third driving force transmitting means is fixed to the front end of the second spline shaft 71, and a thrust bearing 73 is provided in the bearing box 72 at the front and a bearing 74 at the rear. Is established. In this case, the bearing box 72 restricts the relative movement in the axial direction, and allows the relative movement in the rotation direction. Therefore, the first spline shaft 63 includes the thrust bearing 73 and the bearing 7.
4, the second spline shaft 71 and the ball nut 6
9 and is supported so as to be rotatable relative to 9. Reference numeral 85 denotes an absolute value pulse encoder for detecting the position of the screw 22, and reference numeral 86 denotes a bracket that supports the absolute value pulse encoder 85.

Next, the operation of the driving section having the above configuration will be described. First, in the injection step, when a current is supplied to the stator 48 of the injection motor 45, the rotor 49 is rotated, and the rotation of the rotor 49 is controlled by the second rotor shaft 57.
And a ball screw shaft 65 via a bearing retainer 64.
And the ball screw shaft 65 is rotated. At this time, since the second spline nut 76 fixed to the center support 15 and the second spline shaft 71 are spline-connected, the ball nut 69 does not rotate. Therefore, a thrust is generated in the ball nut 69, and the ball nut 69 is advanced.

During this time, the weighing motor 44 is not driven, and the rotor 47 is stopped. Therefore, the first spline shaft 63 disposed in front of the ball nut 69
Is advanced without rotating, the screw 2
Advance 2 In this manner, the rotational motion generated by the injection motor 45 is converted into a linear motion by the ball screw shaft 65 and the ball nut 69. As a result, the resin 3 accumulated in front of the screw 22
3 can be injected from the injection nozzle 12a.

Next, in the measuring step, the measuring motor 4
When the current is supplied to the stator 46 of the fourth spline, the rotor 47 is rotated, and the rotation of the rotor 47 is transmitted to the first spline shaft 63 via the first rotor shaft 56 and the first spline nut 62, and the first spline The shaft 63 is rotated. Then, the rotation of the first spline shaft 63 is transmitted to the screw 22, and the screw 22 is rotated. Along with this, the resin 33 advances in the groove 26 while being melted, and the screw 22 is moved backward by the back pressure generated as the resin 33 advances.

At this time, since the first spline nut 62 and the first spline shaft 63 are spline-connected, the first spline shaft 63 is relatively retracted with respect to the first spline nut 62. The injection motor 45 is driven while controlling the back pressure of the resin 33 to be measured, and the rotor 49 is rotated in a direction to retract the screw 22. The back pressure is based on, for example, a load applied in the axial direction of the screw 22 or the like detected by a load meter (not shown) or a pressure of the resin 33 in the heating cylinder 12 detected by a pressure sensor (not shown). You can ask.

As described above, in order to move the screw 22 forward and backward or rotate it, the timing belts 7a and 7
Since there is no need to use b (see FIG. 2), no noise is generated at the time of driving, maintenance and management of the injection device are easy, and control accuracy such as speed and position can be improved. Further, since the ball screw shaft 65 can be rotated at the time of injection, the rotational inertia can be reduced as compared with the case where the ball nut 69 is rotated, and controllability such as speed rise can be improved. be able to.

Since the first spline shaft 63 and the ball nut 69 can be rotated relative to each other by the thrust bearing 73 and the bearing 74, the measuring motor 44 and the injection motor 45 are synchronized. It is not necessary to drive the motor for measurement, the metering motor 44 and the injection motor 45 can be easily controlled, and the control accuracy of the back pressure can be improved. Further, since the rotation force of the injection motor 45 is held by the second spline nut 76, the measurement motor 44 does not receive the rotation force. Therefore, the capacity of the weighing motor 44 can be reduced.

In all the steps, the measuring motor 44
In addition, since both the injection motor 45 and the injection motor 45 can be fixed, the reliability of the motor wiring and the like can be improved. It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0036]

As described above in detail, according to the present invention, in the injection device of the electric injection molding machine, the drive unit case and the screw are disposed in the drive unit case on the same axis as the screw. Injection motor, movement direction conversion means connected between the injection motor and the screw, for converting rotational movement into linear movement, and for moving the screw forward and backward,
A weighing motor disposed in the drive unit case, a second motor connected between the weighing motor and the screw, for restraining relative movement in the rotational direction and allowing relative movement in the axial direction; A second driving force transmitting means, which is connected between the driving part case and the screw, restricts relative movement in the rotational direction, and permits relative movement in the axial direction; A third driving force transmitting means connected between the movement direction changing means and the screw, for restraining relative movement in the axial direction and allowing relative movement in the rotation direction.

In this case, in the injection step, when the injection motor is driven, the rotation generated by the injection motor is transmitted to the movement direction conversion means, and the rotation movement is converted into a linear movement by the movement direction conversion means. Is converted. Therefore, since the screw is advanced without rotating, the resin stored in front of the screw can be injected from the injection nozzle.

Next, in the measuring step, when the rotation is transmitted to the screw via the second driving force transmitting means, the screw can be moved backward while rotating. As a result, there is no need to use a timing belt to advance or retreat or rotate the screw, so that noise is not generated at the time of driving, maintenance and management of the injection device are easy, and speed, position, etc. Control accuracy can be improved.

The third driving force transmitting means transmits the linear motion from the motion direction converting means to the screw, but allows the relative motion in the rotating direction.
There is no need to synchronize the rotation for weighing and the rotation for injection. Therefore, the injection motor can be easily controlled, and the control accuracy of the back pressure can be improved.

[0040]

[0041]

[0042]

[0043]

[Brief description of the drawings]

FIG. 1 is a schematic view of a drive unit of an electric injection molding machine according to an embodiment of the present invention.

FIG. 2 is a schematic view of an injection device in a conventional electric injection molding machine.

FIG. 3 is a schematic view of another injection device in a conventional electric injection molding machine.

FIG. 4 is a schematic view of a heating cylinder of the electric injection molding machine according to the embodiment of the present invention.

[Explanation of symbols]

 11 Drive part case 22 Screw 45 Injection motor 46, 48 Stator 47, 49 Rotor 56 First rotor shaft 57 Second rotor shaft 62 First spline nut 63 First spline shaft 65 Ball screw shaft 69 Ball nut 71 Second spline shaft 72 Bearing box 76 Second spline nut

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/17 B29C 45/46-45/52 B29C 45/57-45/58

Claims (1)

(57) [Claims] (A) a driving unit case; (b) an injection motor disposed on the same axis as the screw in the driving unit case; and (c) a position between the injection motor and the screw. And (d) a measuring motor disposed in the drive unit case, and (e) the measuring motor and the measuring motor . is connected between the screw, between the constraining relative movement in the rotational direction, the first driving force transmitting means for allowing relative movement in the axial direction, and (f) the drive unit case and the screw (G) connected between the movement direction converting means and the screw, the second driving force transmitting means being constrained to the relative movement in the rotational direction and allowing the relative movement in the axial direction. , Axial relative An injection device for an electric injection molding machine, comprising: a third driving force transmitting means for restricting a dynamic movement and allowing a relative movement in a rotational direction.