JPH0263713A - Injection molding machine - Google Patents

Abstract

PURPOSE:To prevent initial strain from occurring by disposing a strain generator between the rear end of a metering bearing housing fixed on a pusher plate and the ball-nut screwed to an injection ball-screw, and by fixing the metering bearing housing and the strain generator, and the ball-nut and the strain generator individually and besides attracting the strain generator. CONSTITUTION:A strain generator 12 is fixed on the front surface of an outer ring 18 and the rear surface of an inner ring 19 individually with a metering bearing housing 6 by means of bolts 23 and an injection ball-nut 11 by means of bolts 24. Each fixation is of a state that the strain generator 12 is attracted to each side of the metering bearing housing 6 and the injection ball-nut 11 in every parts. And, as an injection pulley 17 is driven in the injection process, an injection ball-screw 15 rotates, and thus, the injection ball-nut 11 moves forward. In this fashion, the entire of a pusher plate moves forward via the strain generator 12 so as to push out a metering screw 13, and an injection is carried out. The movement of the metering screw 13 is continued until the injection pressure becomes a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application: This invention relates to a structure for mounting a load cell for measuring injection pressure and the like in an injection molding machine.

In order to measure injection pressure, etc., the electric injection unit in the conventional injection molding machine uses a load cell for pressure detection, which has a strain gauge or the like attached to an annular strain body (a), as shown in Fig. 4. (b) is used, but this is the total ffi'
The thrust ball bearing (d) is arranged between the thrust ball bearing (d) and the locking step (e) inside the LD receiver housing (C).
) and the angular bearing (i)? :I and is in a preloaded state. Therefore, the strain body (a) always has an initial strain, and in order to accurately measure the injection pressure, it was necessary to adjust the zero point of the load cell (b) using an adjustment circuit to correct the injection pressure, etc. . In addition, a strain body (a
) is located inside the bearing housing (C), so replacing and maintaining the strain element (a) is troublesome, and wiring to the load cell (b) cannot be done easily. .

Furthermore, Fig. 4 shows the pusher plate part of the injection unit, in which a screw sleeve (f) is rotatably attached to the front part of the metering bearing housing (C), and an injection ball nut (g) is attached to the rear part. Fixed. The symbol (h) is an injection pole screw.

To deal with the above situation, the pressure detection load cell (b) is fixed to the pusher plate using a metering bearing housing (
An attempt has been made to construct a structure in which the metering bearing housing (C) side and the ball nut (l side) are individually fixed with bolts, with the rear end of the ball nut (g) being placed between the injection ball nuts (g). No. 62-183449).

According to this, the problem of applying preload due to clamping is solved,
In addition, inspection and replacement of the flexure element (a) becomes easier, but the bolts that fix the flexure element (a) are screwed directly from the flexure element (a) side toward the metering bearing housing (C). , since it is tightened, compressive strain occurs at this location, and the initial strain of the flexure element (a) is not completely eliminated.

Problems to be Solved by the Invention An object of the present invention is to provide an injection molding machine in which a pressure detection load cell is attached without causing initial strain to the strain body.

Means for Solving the Problem In the injection unit, the strain element of the pressure detection load cell is interposed between the rear end of the metering bearing housing fixed to the pusher plate and the ball nut screwed onto the injection pole screw. Fix it.

The above-mentioned fixing involves fixing the metering bearing housing and the strain-generating body, and the ball nut and the strain-generating body individually, and by attracting the strain-generating body at each location.

The configuration in which the actuating strain body is mounted between the metering bearing housing and the injection ball nut simplifies the replacement and maintenance of the load cell.

The configuration in which the strain-generating body is attracted and fixed to both the metering bearing housing and the injection ball nut makes it possible to fix the strain-generating body with almost no initial distortion.

Embodiment FIG. 1 shows an injection unit 1, in which a front plate 2 and a rear plate 3 are connected in parallel by a tie rod 4, and a pusher plate 5 is mounted between the plates 2 and 3 so as to be movable back and forth. .

The pusher plate 5 has a metering bearing housing 6 in the center.
is inserted into the housing 6 and fixed with a bolt 7. Furthermore, a screw sleeve 8 is rotatably supported on the front part of the housing 6 by a thrust ball bearing 9, a radial ball bearing 10, etc. An injection ball nut 11 is attached via a strain body 12. The base of an 81st screw 13 is attached to the front surface of the screw sleeve 8, and this screw 13 is fitted into an injection cylinder 14 attached to the front surface of the front plate 2. An injection pole screw 15 is pivotally supported on the rear braun 3, and the injection ball nut 11 is screwed onto this pole screw 15.

The reference numeral 16 is a measuring shaft pulley, and the reference numeral 17 is an injection pulley, which are connected to a servo motor for measuring and an injection, respectively.

As shown in FIG. 3, the strain body 12 has an outer ring 18 and an inner ring 19.
is an annular body which is arranged with a step difference in the axial direction and has a connecting portion 20 between the two wheels 18 and 19, and a strain gauge is attached to the connecting portion 20 to constitute a load cell. Outer ring 18
A plurality of tap holes 21 and 22 are provided on the front surface of the inner ring 19 and the rear surface of the inner ring 19.
are formed without penetrating from the front side and the tangential side, respectively.

As shown in FIG. 1, the strain body 12 is fixed individually to the metering bearing shaft housing 6 by bolts 23, to the injection ball nut 11 by bolts 24, and to the front surface of the outer ring 18 and the rear surface of the inner ring 19. has been done. These are fixed in such a manner that the strain-generating body 12 is drawn toward the metering bearing housing 6 or the injection ball nut 11 side by bolts at all locations.

In this embodiment, if the bolt 23 cannot be installed from the metering bearing housing 6 side, screw a headless bolt into the tapped hole of the flexure element 12 in advance, and then attach it to the metering bearing housing 6, so that its protrusion can be removed. Screw the nut into place to secure.

When the injection pulley 17 is driven in the injection process, the injection pole screw 15 rotates and the injection ball nut 11 moves forward. As a result, the entire pusher plate 5 moves forward via the flexure element 12 and pushes out the metering screw 13, thereby performing injection. The metering screw 13 is moved until the injection pressure reaches the set value, and then the pressure holding step is started.

The strain body 12 in the load cell is distorted by the pressing force of the injection ball nut 11, which causes the connecting portion 20
This is detected as a change in the resistance value of a strain gauge attached to the strain gauge, and is used for various controls related to injection pressure or holding pressure. It is also used to manage back pressure during removal of culms.

At this time, since there is no initial distortion when mounting the flexure element 12,
When measuring injection pressure, etc., there is no need for significant adjustment regarding the zero point, and the load cell can be used within the most suitable range of its usage characteristics.

FIG. 2 shows a second embodiment. In the first embodiment, the strain body 12 is attached to an annular adapter 23 with bolts 24, and is fixed to a total of one bearing housing 6 via the adapter 23. This is done by bolt 7. bolt 7
is for fixing the metering wheel holder housing 6 to the pusher plate 5 and is commonly used.

The second embodiment has the advantage that machining of the metering bearing housing 6 and its subsequent parts is simple, and the strain-generating body 12 can be easily attached.

Effect of the invention Load cells can be easily replaced and maintained.

The zero point adjustment range of the load cell is small, ensuring accurate measurement results at all times.

[Brief explanation of the drawing]

Fig. 1 is a front view partially shown in cross section, Fig. 2 is a front view of main parts shown in cross section, Fig. 3 is a front view shown in cross section, and Fig. 4 is a front view partially shown in cross section.
The figure is a front view showing a main part of a conventional example in cross section. 1... Injection unit, 5... Pusher plate,
6... Metering bearing housing, 9... Thrust ball bearing, 11... Ball nut for injection, 12... Strain body,
15... Injection pole screw 23... Adapter. Cause

Claims (1)

[Claims] A ball nut screwed onto an injection pole screw is fixed to the rear end of the metering bearing housing fixed to the pusher plate of the injection unit, with the strain body of the pressure detection load cell interposed therebetween, and the fixing is performed by the metering bearing housing. An injection molding machine characterized in that the bearing housing and the strain body, and the ball nut and the strain body are individually fixed by attracting the strain body at each location.