JPH0751301Y2 - Resin pressure detection mechanism of electric 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 resin pressure detecting mechanism during molding of an electric injection molding machine.

[0002]

2. Description of the Related Art A conventional electric injection molding machine having a resin pressure detecting mechanism has a cylinder 1 as shown in FIG.
A screw 3 is rotatably supported only on the cylinder center on a holding plate 2 which is movably provided on a fixed base 10 on which the injection screw holding plate 2 is mounted. Is rotated. The injection screw pressing plate 2 is provided with a ball nut 7 through a load cell 6 on the same axis as the screw 3 at the rear.
Is mounted, and a ball screw 8 that is screwed onto this is rotated by a motor 9 on a fixed base, and the rotation of the motors 4, 9 advances the screw 3 to perform injection molding. The resin pressure applied to the screw 3 at that time is applied to the load cell 6
Is to be detected by.

[0003]

Since the load cell is arranged on the same axial rear side of the screw rotating shaft 3 as described above, all the resin pressure is applied to the load cell, and a large load cell having a wide detection range is required. Therefore, the cost becomes high. Further, the thickness of the load cell is increased, and a cylinder pressing plate that projects further to the rear by the thickness and expands the space to the rear is required, and the size of the machine becomes large. Further, since the load cell is provided immediately after the screw rotation shaft, the heat generated in the cylinder portion is transmitted to the screw rotation shaft and adversely affects the load cell, resulting in an error in pressure detection. Further, since the load cell is attached in front of the ball nut, there is a problem that the rotational inertial force generated in the nut portion is transmitted to the load cell as a load and an error from the actual resin pressure occurs. The present invention has been made in view of the above problems of the conventional technology. The purpose of the present invention is to improve the reliability of the load cell detection value and to use a small one without increasing the size of the machine. The present invention intends to provide a resin pressure detecting mechanism.

[0004]

In order to achieve the above-mentioned object, the present invention provides an electric injection molding machine in which injection molding is performed by a screw axially moved by a ball screw rotated about a cylinder. Are arranged in parallel to the screw, a load cell is interposed between the thrust receiving member of the screw and one thrust bearing of the ball screw, and the number of the ball screw is provided at the output of the load cell. The value obtained by multiplying the coefficient based on is the resin pressure.

[0005]

Function: The resin is injected by the screw advanced by the rotation of the ball screw. The resin pressure at this time is received by the plurality of ball screws through the screw and the injection screw pressing plate. The load cell installed in the bearing portion of one ball screw detects the pressure of a fraction of the number of screws, and the total pressure can be known by multiplying the detected value by the number of screws.

[0006]

Embodiment This embodiment will be described below with reference to FIG. The figure shows a drive unit of a vertical electric injection molding machine, and a cylinder fixing plate 12 to which a cylinder 11 to which a molten resin is supplied is fixed is provided through a nut for screwing a plurality of screws established on a table (not shown). The nut is rotated by a motor (not shown) so as to be connected to and separated from a mold (not shown). A plurality of ball nuts 13 are fixed to the cylinder 11 at symmetrical positions in parallel with the axis of the cylinder 11. A screw 14 is rotatably and axially movable in the center of the cylinder 11, and the injection screw pressing plate 1 is movably provided.
5 is rotatably supported by a radial bearing 16 and a thrust bearing 17 and is integrally connected to a screw rotating shaft 19 having a pulley 18 attached to its rear end.

A ball screw 20 screwed to each ball nut 13 is rotatably supported by a radial bearing 21 and a thrust bearing 22 on the injection screw pressing plate 15. The outer ring of the thrust bearing 22 that supports one of the ball screws 20 and the hole 1 of the injection screw pressing plate 15
A load cell 23 is interposed between the step portion 5a and the step portion. A pulley 24 is keyed to the rear end of each ball screw 20, a single timing belt (not shown) is hung on it, and is synchronously rotated in the same direction by a motor provided on the injection screw pressing plate 15. Further, the pulley 18 of the screw rotating shaft 19 is connected to a motor (not shown) on the injection screw pressing plate 15 by a timing belt. Reference numeral 25 is an outer ring holding plate of the radial bearing 16, 26 is an inner ring of the radial bearing, and 27 is a holding plate of the outer ring.

The operation of the present invention having such a configuration will be described. The cylinder fixing plate 12 is moved so that the tip of the cylinder 11 is pressed against the casting port of a mold (not shown). The molten resin supplied into the cylinder 11 rotates the pulley 18 and is sent to the tip by the screw 14. The pulley 24 is rotated to synchronously rotate the plurality of ball screws 20, and the injection screw pressing plate 15 is lowered. By this descending, the screw 14 is descended to inject the resin into the mold from the tip of the cylinder 11. The internal pressure of the resin is transmitted to the screw 14,
The screw rotating shaft 19, the thrust bearing 17, and the hole 15a of the injection screw pressing plate 15 act on the load cell 23 from the stepped portion, and are received by the ball screw 20 of the thrust bearing 22. The plurality of ball screws 20 receive the same amount of force. The load cell 23 detects a pressure that is a fraction of the total number of ball screws. Therefore, it is possible to know the total pressure of the resin by multiplying this detected value by the number of Volvo screws.

[0009]

As described above, the present invention has the following effects. Since a part of the total resin pressure is detected and the total resin pressure is calculated from the value, it is economical because a small load cell having a narrower range than the conventional load cell for detecting the total resin pressure can be used for detection. A bolus screw nut mechanism that moves the injection screw pressing plate is placed at a position off the same axis as the screw rotation axis, and the load cell can be installed at a position off the same axis as the screw rotation axis, so heat transfer is difficult, It is possible to suppress the occurrence of an error due to the heat of the load cell, and to obtain stable detection accuracy. In addition, since the front-rear positional relationship can be shifted, the injection screw pressing plate becomes thin and the space can be reduced, which contributes to downsizing of the machine. Further, since the thrust generated by the ball screw nut mechanism is transmitted to the load cell through the bearing, the load cell can accurately detect the resin pressure without being affected by the inertial force due to the rotation.

[Brief description of drawings]

FIG. 1 is a sectional view showing a screw and a ball screw driving portion of a vertical injection molding machine of the present invention.

FIG. 2 is an explanatory cross-sectional view of a drive unit of a conventional molding machine of the same type.

[Explanation of symbols]

11 Cylinder 12 Cylinder Fixing Plate 13 Ball Nut 14 Screw 15 Injection Screw Holding Plate 17,22 Thrust Bearing 18,24 Pulley 23 Load Cell

Claims (1)

[Scope of utility model registration request] 1. In an electric injection molding machine injection-molded by a screw which is rotated around a cylinder and axially moved by a ball screw, a plurality of the ball screws are arranged in a position parallel to the screw, A load cell is interposed between a thrust receiving member and one thrust bearing of the ball screw, and a value obtained by multiplying an output of the load cell by a coefficient based on the number of the ball screws is used as a resin pressure. Resin pressure detection mechanism of electric injection molding machine.