JPH078185Y2 - Pressure detector for injection molding machine - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detecting device for detecting injection pressure or the like in an injection molding machine.

[0002]

2. Description of the Related Art In an electric injection molding machine, a load cell is installed as a load converter at the rear end of an injection screw in order to perform feedback control of injection pressure when injecting resin into a mold and back pressure during measurement. To detect the pressure (Japanese Patent Laid-Open No. 64-64-
No. 27921).

[0003]

The load cell is usually installed at the rear end of the injection screw through a bearing, but that portion is the heat of the heating cylinder and frictional heat associated with the rotation of the injection screw. For example, the temperature tends to be higher than room temperature. Further, the ball screw may also generate heat due to friction between the ball and the raceway surface during high load continuous operation. When the temperature of the load cell changes, both the zero point and the output change. The rate of change depends on the manufacturer and type of load cell, but for a temperature change of 10 ° C, the temperature effect of the zero point is approximately 0.03 to 0.05%, and the temperature effect of the output is approximately 0%. It is 0.03 to 0.1%.

Therefore, for example, the injection pressure is 2000 kg.
/ Cm For ² (MAX), when the temperature 40 ° C. changes, the zero 2.4～4Kg / cm ^2, the output becomes possible to vary 2.4～8Kg / cm ^2, adverse effect on the stability of the molding There are things that cannot be ignored.

An object of the present invention is to provide a pressure detection device for an injection molding machine, which can detect pressure accurately and improve molding stability without being affected by heat of a heating cylinder or the like. And

[0006]

To achieve the above object, the present invention provides a pressure detecting device for an injection molding machine, wherein a load converter is provided between a pressing member and a pressure receiving member. A heat insulating material is interposed between at least one of the load converter and the pressure receiving member and between the load converter and the pressure receiving member.

[0007]

The heat insulating material interposed between at least one of the load converter and the pressing member and between the load converter and the pressure receiving member blocks the conduction heat of the heating cylinder and the injection screw. Therefore, the load converter does not raise the temperature due to the influence of the heating cylinder, the injection screw, and the like, and maintains the room temperature to accurately detect the pressure.

[0008]

1 shows an embodiment of the present invention. In the figure, reference numeral 1 is a front plate. Front plate 1
The heating cylinder 2 is fixed to the. A rear plate 3 is provided behind the front plate 1 (on the right side in FIG. 1) in parallel with the front plate 1, and a pair of identical ball screw shafts 4 and 4 are mounted between the plates 1 and 3. 1a, 3a
It is rotatably supported and provided on the. Pulleys 5 having the same diameter are attached to the ends of the ball screw shafts 4, respectively.

An electric servomotor 6 is fixed to the rear plate 3, and an endless timing belt 9 is wound between a drive pulley 8 and a pulley 5, 5 provided on an output shaft 7 of the motor 6. ing. The electric servomotor 6 rotates the ball screw shafts 4 and 4 in the circumferential direction in synchronization with each other via the drive pulley 8, the timing belt 9, and the pulleys 5 and 5.

A ball nut 1 is attached to each of the ball screw shafts 4 and 4.
1 are screwed together, and the pair of ball nuts 1
A pressure plate 12 is installed between 1 and 11. The pressure plate 12 has each ball screw shaft 4, 4
When is rotated, it moves in the front-back direction (left-right direction in FIG. 1) together with the ball nuts 11, 11.

A bearing housing 13 is attached to the front surface of the pressure plate 12 on the heating cylinder 2 side via heat insulating materials 14 and 15 and a load converter 16 such as a load cell. The heat insulating materials 14 and 15 are made of asbestos, ceramics or the like, and sandwich the load converter 16 in the front and rear.

A bearing 17 is provided in the bearing housing 13, and a rotary shaft 18 is rotatably supported by the bearing 17. A pulley 19 is attached to the front end of the rotary shaft 18, and a spline bush 20 is attached to the front surface of the pulley 19.
The injection screw 21 is attached via. The injection screw 21 is inserted in the heating cylinder 2. The central axes of the heating cylinder 2, the rotary shaft 18, the pulley 19 and the injection screw 21 coincide with each other and are parallel to the ball screw shafts 4 and 4.

Passages 12a and 13a for a cooling medium such as water are provided in the heat insulating materials 13 and 14 of the pressure plate 12 and the bearing housing 13, and a cooler (not shown)
Have been contacted.

Next, the operation of the pressure detecting device of the injection molding machine according to the present invention constructed as described above will be described. The injection screw 21 is rotated in the circumferential direction via a pulley 19 by an electric motor (not shown) supported by the pressure plate 12, and is retreated by the resin pressure to plasticize the resin and measure it in front of the screw head 21a. To do. The injection screw 21 is advanced by the rotation of the ball screw shafts 4 and 4 by the electric servomotor 6, and the resin measured above is injected from the nozzle 2a to the mold.

In the above operation, the load converter 16 is
When measuring the resin, the bearing housing (pressing member) 13 presses it against the pressure plate (pressure receiving member) 12, and the pressure (back pressure) at that time is detected. Further, the load converter 16 is pressed against the bearing housing (pressure receiving member) 13 by the pressure plate (pressing member) 12 for resin injection, and detects the pressure (injection pressure) at that time.

The heat of the heating cylinder 2 and the heat generated by the rotation of the injection screw 21 and the like are transmitted to a low temperature portion to raise the temperature. At this time, the heat insulating materials 14 and 15 block the above heat conduction. , The pressure plate 12 and the bearing housing 1
The cooling medium passed through the third passages 12a and 13a cools the portion. Therefore, the load converter 16 is not heated by the heat of the heating cylinder 2 or the like, and keeps the temperature constant and accurately detects the pressure.

FIG. 2 shows another embodiment of the present invention.
A bearing portion 12b is formed on the pressure plate 12, and a rotating shaft 18 is supported by bearings 17, 17 of the bearing portion 12b. A load converter 16 is provided between the bearing portion 12b and the bearing 17 via heat insulating materials 14, 15, 22 arranged in front of and behind it.

Also in this embodiment, each heat insulating material 14, 1
Reference numerals 5 and 22 prevent heat conduction to the load converter 16, and the cooling medium flowing in the passage 12a cools the bearing portion 12b to keep the load converter 16 at a low temperature. Bearing 17 for weighing
Serves as a pressing member and the bearing portion 12b serves as a pressure receiving member, and the above is reversed at the time of injection. The same members and the like as those in FIG. 1 of FIG. 2 are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 3 shows another embodiment of the present invention. The load converter 16 is provided between the front plate 1 and the flange 23 fixed to the heating cylinder 2 via heat insulating materials 14, 15, and 22. Even in this case, each heat insulating material 1
4, 15 and 22 prevent heat conduction to the load converter 16,
In addition, the cooling medium flown in the passage 1b is the front plate 1
To keep the load transducer 16 cool. The front plate 1 serves as a pressing member and the flange 23 serves as a pressure receiving member at the time of weighing, and the above is reversed at the time of injection. The front plate 1 may be a mounting plate of a hopper.

Although the above-mentioned three embodiments are examples in which the present invention is applied to the injection unit, they can also be applied to the mold clamping unit.

[0021]

As described above, the pressure detecting device for an injection molding machine according to the present invention is the pressure detecting device for an injection molding machine in which a load converter is provided between the pressing member and the pressure receiving member. Since the heat insulating material is interposed between at least one of the load converter and the pressing member and between the load converter and the pressure receiving member, the load converter is affected by the heat of the heating cylinder or the like. Keeping the predetermined temperature without. Therefore, the pressure can be accurately detected to improve the molding stability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a pressure detecting device for an injection molding machine according to the present invention.

FIG. 2 is a sectional view of another embodiment of the present invention.

FIG. 3 is a sectional view of another embodiment of the present invention.

[Explanation of symbols]

 1 Front Plate 3 Rear Plate 4 Ball Screw Shaft 11 Vault Nut 12 Pressure Plate 13 Bearing Housing 14, 15 Heat Insulation Material 16 Load Converter

Claims (1)

[Scope of utility model registration request] 1. A pressure detecting device for an injection molding machine, wherein a load converter is provided between a pressing member and a pressure receiving member, and between the load converter and the pressing member and between the load converter and the pressure receiving member. A pressure detecting device for an injection molding machine, wherein a heat insulating material is interposed in at least one of the above.