JP2804191B2 - Injection pressure control device - 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 pressure control device.

[0002]

2. Description of the Related Art Conventionally, a resin heated and fluidized in a heating cylinder is injected into a mold at a high pressure and cooled therein.
In an injection molding machine that solidifies or hardens, and then opens a mold to take out a molded product, a screw is supported rotatably and advancing and retracting in a heating cylinder, and injection is performed by advancing the screw. Weighing can be performed by rotating the screw and moving it back.

FIG. 2 is a schematic view of an injection device of a conventional injection molding machine. In the drawing, 1 is a heating cylinder, 2 is a screw disposed rotatably and advancing and retreating in the heating cylinder 1, 3 is a nozzle portion formed at the tip of the heating cylinder 1, and 4 is a screw which is retracted This is a hopper for supplying pellet-shaped resin 5 into the heating cylinder 1 when performing the heating. The resin 5 is heated by the heating cylinder 1 while advancing along the groove of the screw 2, melted, and stored at the tip of the nozzle portion 3.

[0004] Further, reference numeral 11 denotes a front injection support to which the heating cylinder 1 is mounted, 17 denotes a rear injection support arranged at a predetermined distance from the front injection support 11, and 18 denotes a rear end of the screw 2. Drive shaft connected to the drive shaft. The front injection support 11 and the rear injection support 17 are fixed to slide bases (not shown) via bolts, respectively, and a guide bar 21 is installed between the two in a horizontal direction.

A pressure plate 30 is provided between the front injection support 11 and the rear injection support 17 so as to be able to advance and retreat along the guide bar 21, and the drive shaft 18 is mounted on the pressure plate 30 via a bearing 31. Supported rotatably. Reference numeral 32 denotes a screw rotation pulley, which is connected to the screw rotation motor 33 and is driven at the time of measurement to retract the screw 2.

Reference numeral 34 denotes a ball screw rotatably supported by the rear injection support 17 via a bearing 35. The ball screw 34 has a ball nut 3 at the front end.
7 is screwed. The ball nut 37 is fixed to a slide plate 38 slidably disposed along the guide bar 21. The above pressure plate 3
A load cell 39 is arranged between the slide plate 38 and the pressure plate 30, and the pressure plate 30 can be moved back and forth by rotating the ball screw 34.

For this reason, an injection pulley 40 is attached to the rear end of the ball screw 34, and the timing belt 4
1, connected to an injection motor 43 via a pulley 42, and the driving force of the injection motor 43
4. By the way, in the injection device of the injection molding machine having the above configuration, the injection motor 43 is driven to rotate the injection pulley 40, and the screw 2 is advanced through the pressure plate 30 to perform injection. By finding the firing power that occurs,
An injection step and a pressure-holding step with high precision and reproducibility can be realized.

For this purpose, a load cell 39 is provided between the pressure plate 30 and the ball nut 37. The ball nut 34 is rotated to rotate the ball nut 37.
Is moved, the pressure plate 30 and the screw 2 advance, and a reaction force is generated by the resin in the heating cylinder 1 so that the load cell 39 is pressed.
At this time, the distortion of the load cell 39 is converted into an electric signal, and a radiation output can be obtained from the electric signal. As the load cell 39, a load cell having low rigidity is used in order to increase detection accuracy.

When the ball screw 34 rotates by receiving the driving force from the injection motor 43, the ball nut 37 receives torque from the ball screw 34. The load cell 39 is for detecting a strain when a load is applied in the axial direction, and obtains a radiation output by an electric signal corresponding to the strain. Therefore, when the torque is applied in a direction other than the axial direction, in the case of the load cell 39 having a low rigidity, a distortion is generated in a direction other than the axial direction, so that it is not possible to obtain an accurate radiation output.

Therefore, the slide plate 38 is slid along the guide bar 21, and a ball nut 37 is attached to the slide plate 38, and the torque transmitted through the ball nut 37 is applied to the guide bar 21. I am trying to receive it.

[0011]

However, in the injection device of the conventional injection molding machine described above, the ball nut 3
7, the torque transmitted to the slide plate 38 through the guide bar 21 is received by the guide bar 21, so that a frictional force is generated between the slide plate 38 and the guide bar 21 to reduce the efficiency of the drive system and reduce the number of parts. Also increase. When the slide plate 38 is removed, an output proportional to the applied torque is generated in the load cell 39, and this output does not make it possible to increase the detection accuracy of the output power.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injection pressure control device capable of solving the above-described problems of the injection device of the conventional injection molding machine and improving the accuracy of detecting the injection output by the load cell.

[0013]

For this purpose, in the injection pressure control device of the present invention, a heating cylinder for supporting a screw rotatably and advancing and retreating, a front injection support for fixing the heating cylinder, and a front injection support are provided. A rear injection support is provided to face the support, and a guide bar is provided between the front injection support and the rear injection support.

A pressure plate is movably arranged along the guide bar between the front injection support and the rear injection support, and rotatably supports the rear end of the screw. A feed screw is provided between the pressure plate and the rear injection support, rotated by an injection motor, and screwed with a nut fixed to the pressure plate.

[0015] A load cell is arranged between the nut and the pressure plate, and outputs an electric signal corresponding to a distortion generated when the screw is advanced by rotating the feed screw. Correct the output of the load cell,
The output when only the torque is applied to the load cell is eliminated.

[0016]

According to the present invention, as described above, the heating cylinder for supporting the screw rotatably and advancing and retracting, the front injection support for fixing the heating cylinder, and the front injection support are provided to face the front injection support. It has a rear injection support, and a guide bar is provided between the front injection support and the rear injection support.

A pressure plate is movably disposed along the guide bar between the front injection support and the rear injection support, and rotatably supports the rear end of the screw. A feed screw is provided between the pressure plate and the rear injection support, rotated by an injection motor, and screwed with a nut fixed to the pressure plate.

When the injection motor is driven, the feed screw rotates, and the screw is moved forward and backward through the nut and the pressure plate. A load cell is arranged between the nut and the pressure plate, and outputs an electric signal corresponding to a distortion generated when the screw is advanced by rotating the feed screw. The output of the load cell includes, in addition to the axial load applied to the nut, distortion due to torque applied to the nut due to rotation of the feed screw.

Therefore, the output of the load cell is corrected,
By removing the output when only the torque is applied to the load cell, the detection accuracy of the radiation output can be increased.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view of an injection device of an injection molding machine employing an injection pressure control device of the present invention.
In the figure, 1 is a heating cylinder, 2 is the heating cylinder 1
A screw 3 is provided at the tip of the heating cylinder 1 so as to be rotatable and advanceable and retractable. A nozzle 4 is formed at the tip of the heating cylinder 1. It is a hopper for supplying. Resin 5
Is the heating cylinder 1 while moving forward along the groove of the screw 2.
, And is melted and stored at the tip of the nozzle portion 3.

Reference numeral 11 denotes a front injection support to which the heating cylinder 1 is mounted, 17 denotes a rear injection support arranged at a predetermined distance from the front injection support 11, and 18 denotes a rear end of the screw 2. Drive shaft connected to the drive shaft. The front injection support 11 and the rear injection support 17 are fixed to slide bases (not shown) via bolts, respectively, and a guide bar 21 is installed between the two in a horizontal direction.

A pressure plate 30 is disposed between the front injection support 11 and the rear injection support 17 so as to be able to advance and retreat along the guide bar 21, and the drive shaft 18 is mounted on the pressure plate 30 via a bearing 31. Supported rotatably. Reference numeral 32 denotes a screw rotation pulley, which is connected to the screw rotation motor 33 and is driven at the time of measurement to retract the screw 2.

Reference numeral 34 denotes a ball screw (feed screw) rotatably supported by the rear injection support 17 via a bearing 35. The ball screw 34 is screwed to a ball nut 37 at a front end. The ball nut 37
Is the pressure plate 30 through the load cell 39
The pressure plate 30 can be moved back and forth by rotating the ball screw 34.

Therefore, an injection pulley 40 is attached to the rear end of the ball screw 34, and the timing belt 4
1, connected to an injection motor 43 via a pulley 42, and the driving force of the injection motor 43
4. By the way, in the injection device of the injection molding machine having the above configuration, the injection motor 43 is driven to rotate the injection pulley 40, and the screw 2 is advanced through the pressure plate 30 to perform injection. By finding the firing power that occurs,
An injection step and a pressure-holding step with high precision and reproducibility can be realized.

Therefore, a load cell 39 is provided between the pressure plate 30 and the ball nut 37. The ball nut 34 is rotated to rotate the ball nut 37.
Is moved, the pressure plate 30 and the screw 2 advance, and a reaction force is generated by the resin in the heating cylinder 1 so that the load cell 39 is pressed.
At this time, the distortion of the load cell 39 is converted into an electric signal, and a radiation output can be obtained from the electric signal. As the load cell 39, a load cell having low rigidity is used in order to increase detection accuracy.

When the screw 2 is advanced by rotating the ball screw 34, an axial strain is generated in the load cell 39. At this time, a torque is applied to the load cell 39 via the ball nut 37. This torque affects the axial strain of the load cell 39, and cannot improve the detection accuracy of the radiation output. Therefore, the distortion of the load cell 39 other than the axial direction can be removed.

Reference numeral 51 denotes a load cell output compensator; 52, an injection molding machine control device; 53, an injection output setting device; and 54, an injection servo amplifier. The load cell output compensator 51 includes:
This is for correcting the output of the load cell 39 and removing the output generated by the torque applied to the load cell 39 via the ball nut 37, so that the corrected output is sent to the injection molding machine controller 52. Has become. The injection molding machine control device 52 receives the value set by the injection power setting device 53 and the output from the load cell output compensator 51, activates the injection servo amplifier 54, and drives the injection motor 43.

In order to perform the calculation in the load cell output compensator 51, the output when only the torque acts on the load cell 39 is measured in advance. FIG. 3 is a diagram showing a load cell output measuring device for performing injection pressure control. 3A shows a side surface of the load cell output measuring device, and FIG. 3B shows a front surface of the load cell output measuring device.

In the figure, 39 is a load cell, 56 is a base of the load cell output measuring device, 57 is a fixed wall for fixing one end of the load cell 39, and 58 is a verification shaft fixed to the other end of the load cell 39. is there. A wing portion 60 extending left and right is provided at the tip of the verification shaft 58, and a constant load is applied to the tip of the wing portion 60, and the output of the load cell 39 at this time is taken out.

When the load cell 39 is fixed alone and the output is measured by applying only torque, F _T = aT _M F _T : the output of the load cell 39 due to the torque alone T _M : torque acting on the load cell 39 a: It becomes the proportionality constant. That is, the output is uniquely determined with respect to the torque.

Further, incorporation of the load cell 39 to the injection device, by the action of torque on the injection pulley 40, when measuring the output of the load cell 39 by fixing the axial movement of the pressure plate 30, F _L = bT _M b : Proportional constant In this case, the if the actual injection force and _{F i F i = F L -F} T = F L (1-a / b). In the load cell output compensator 51, perform the above calculation, it is possible to obtain an output of an injection molding machine controller 52 based on the injection force F _i obtained with the value set by the injection force setting device 53 by calculation.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0033]

As described above in detail, according to the present invention, the pressure plate is movably disposed along the guide bar between the front injection support and the rear injection support, and the rear end of the screw is rotated. Support freely. A feed screw is provided between the pressure plate and the rear injection support, rotated by an injection motor, and screwed with a nut fixed to the pressure plate.

A load cell is disposed between the nut and the pressure plate, and outputs an electric signal corresponding to a distortion generated when the screw is advanced by rotating the feed screw. At this time, the output of the load cell is corrected, and the output when only the torque is applied to the load cell is removed. Therefore, an output corresponding to the strain of only the load applied to the load cell in the axial direction can be obtained, so that the detection accuracy of the radiation output can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic view of an injection device of an injection molding machine employing an injection pressure control device of the present invention.

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

FIG. 3 is a diagram showing a load cell output measuring device for performing injection pressure control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating cylinder 2 Screw 11 Front injection support 17 Rear injection support 21 Guide bar 30 Pressure plate 34 Ball screw (feed screw) 37 Ball nut (nut) 39 Load cell 43 Injection motor

Continued on the front page (56) References JP-A-2-16023 (JP, A) JP-A-4-129719 (JP, A) JP-A-4-77225 (JP, A) JP-A-4-270625 (JP) JP-A-3-36013 (JP, A) JP-A-61-266219 (JP, A) JP-A-61-154820 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) B29C 45/00-45/84

Claims (1)

(57) [Claims] 1. A heating cylinder for supporting a screw rotatably and advancing and retreating, (b) a front injection support for fixing the heating cylinder, and (c) being disposed opposite to the front injection support. A rear injection support, (d) a guide bar provided between the front injection support and the rear injection support, and (e) a movable bar along the guide bar between the front injection support and the rear injection support. A pressure plate for rotatably supporting the rear end of the screw, (f) a feed screw disposed between the pressure plate and the rear injection support and rotated by an injection motor, and (g) a feed screw. A nut screwed and fixed to the pressure plate; and (h) the feed screw is disposed between the nut and the pressure plate and rotated. A load cell for outputting an electric signal corresponding to the distortion at the time, and (i) means for correcting the output of the load cell and removing only the output when only the torque is applied to the load cell. Injection pressure control device.