JP3729075B2 - Screw fixing device in electric vertical injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw fixing device in a vertical injection device using an electric motor such as an electric servomotor as a drive source.
[0002]
[Problems to be solved by the invention]
An electric motor such as an electric servo motor is used as a driving source for metering and injection of the material resin, and the rotational movement by the electric motor is converted into a linear movement by a screw shaft and a nut member screwed into the screw shaft for injection. Among the electric injection molding machines that move the screw forward, in the horizontal injection molding machine in which the entire injection device is installed horizontally on the machine base, the moving direction of the drive unit and the screw is horizontal, so the screw is under its own weight. An injection plate that does not move but supports the injection device on the support shaft on the movable plate so that it can be raised and lowered, and is installed vertically on the machine base to hold the screw so that it can rotate and retreat. However, since the screw shaft is only supported by the upper plate by screwing the screw shaft and the nut member, the screw shaft self-rotates due to the load on the injection plate side, and the injection plate There is a tendency to move downward along with the Interview.
[0003]
Therefore, the present inventors have made an invention (refer to Japanese Patent No. 3090885) in which the injection plate is prevented from moving by providing a brake in the injection electric motor first. However, the electric motor with a brake is a horizontal molding. Compared to the non-brake electric motor used in the machine, the structure is complicated and the necessity is limited to the saddle type, so it is not possible to reduce the cost by mass production. The vertical molding machine using the attached electric motor had to be expensive compared to the horizontal type.
[0004]
The present invention has been conceived in order to solve the above-mentioned problems, and its purpose is to move the injection plate up and down across the upper plate and the injection plate without braking the rotation of the screw shaft by the brake of the electric motor. A fixing device that can be constrained by a brake is arranged, so that a screw fixing device in a new electric vertical injection device that can fix a screw in a predetermined position together with an injection plate even if an electric motor of a normal structure is adopted for injection It is to provide.
[0005]
[Means for Solving the Problems]
The present invention according to the above object comprises a plurality of support shafts erected on a movable plate, a lower plate having a heating cylinder with an injection screw installed downward, and an upper plate provided with an electric motor for injection. A screw shaft that is connected to a connecting rod inserted through an injection plate so as to be movable up and down, converts the rotation of the electric motor into a linear motion between the injection plate and the upper plate, and moves the injection plate together with the screw. In an electric vertical injection device provided with an injection drive device using a nut and a nut member, a ball screw shaft is rotatably provided on one of the upper plate and the injection plate, and the ball screw shaft is fixed to the other plate. It is screwed into the ball nut member provided and rotated by the movement of the injection plate. It is those that formed by providing a device and the brake device consists of exciting actuating the braking device or non-excitation braking device, is that.
[0006]
In the above configuration, the screw fixing device arranged between the upper plate and the injection plate prevents the downward movement at the completion of weighing due to its own weight on the injection plate side and upon completion of injection filling. As the injection screw stops reliably, the weighing accuracy is improved, and in push-cut molding, movement beyond the end of the injection stroke due to its own weight is prevented, and problems such as injection accuracy due to overpacking are also improved. The electric motor having the normal structure used in the above can be directly adopted as the injection drive source, and the manufacturing cost of the vertical injection device can be reduced.
[0007]
In addition, when a non-excitation brake device is used as the screw fixing device, the brake is operated by stopping energization, so even when the injection and metering electric motor is stopped due to a power failure, the screw is immediately operated and the screw is Since it is fixed in position and prevents the injection plate and screw from moving downward due to gravity, it also functions as a safety device.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the figure, reference numeral 1 denotes a movable plate located above the machine base (not shown), and four support shafts 2 and 2 on the upper surface are erected. On both sides of the upper end plate 3 of the support shafts 2 and 2, nozzle touch screw shafts 5 that are rotated by the electric motor 4 are provided vertically.
[0009]
Further, an upper plate 6 and a lower plate 7 are inserted into the support shafts 2 and 2 through a connecting rod 9 in which an injection plate 8 is movably fitted, and both sides of the upper plate 6 are connected to the nozzles. The screw shaft 5 is engaged with the touch screw shaft 5 and moved up and down together with the lower plate 7 and the injection plate 8 using the support shafts 2 and 2 as a guide.
[0010]
A central portion of the upper plate 6 is integrally formed with a bearing portion 11 of an injection ball screw shaft 10 that protrudes long downward, and an injection electric servo motor 12 is mounted upward on a side portion of the bearing portion 11. . Further, the shaft portion of the ball screw shaft 10 is rotatably passed through the bearing portion 11, and a pulley 13 is attached to a shaft end protruding on the bearing portion. A driving belt 14 is wound around the pulley 13 over a pulley 15 at the driving shaft end of the electric servo motor 12.
[0011]
A heating cylinder 16 having a nozzle at the lower end is attached downward in the center of the lower surface of the lower plate 7, and an injection screw 17 whose rear end is rotatably connected to the injection plate 8 is advanced and retracted in the heating cylinder. Inserted freely.
[0012]
A cylindrical ball nut member 18 screwed with the threaded portion of the ball screw shaft 10 is attached to the center of the upper surface of the injection plate 8. Further, the rear end of the screw 17 penetrating the lower plate 7 is rotatably attached at the center of the lower surface, and an injection plate is connected to a pulley 17a provided at the rear end of the screw between the lower plate 7 and the injection plate 8. A driving belt 20 from a measuring servo motor 19 attached to the side portion 8 is attached.
[0013]
In the above configuration, since the ball screw shaft 10 side to be screwed together is fixed and the ball nut member 18 side is movable, the rotational motion of the ball screw shaft 10 by the electric servo motor 12 is changed to linear motion by the ball nut member 18. As a result, the injection plate 5 moves downward (upward depending on the rotation direction) between the upper and lower play portions with the connecting rod 9 as a guide, and thus the screw 17 in the heating cylinder supported by the injection plate 8 also moves downward. And a drive device for injecting the measured resin.
[0014]
Further, when the screw 17 is rotated by the measuring servo motor 19 and the material resin is supplied and plasticized in the heating cylinder 16 as usual, the resin pressure by the plasticization is injected through the screw 17 into the injection plate. 8 acts as a pressing force. In order to obtain an appropriate back pressure at the time of measurement, an appropriate rotational braking force is applied to the ball screw shaft 10 by the electric servomotor 12 for injection, but the ball screw shaft 10 is pressed by the pressing force exceeding the rotational braking force. The injection plate 8 rotates reversely to the time of injection, and the injection plate 8 moves backward together with the screw 17 to the measurement stop position.
[0015]
When the backward movement reaches the measurement stop position, the measurement electric servo motor 19 is stopped as measurement completion. Further, it is necessary to fix the screw position with respect to the ball screw shaft 10 so that the ball screw shaft 10 is self-rotated by the load on the injection plate side and the injection plate side does not move downward.
[0016]
A screw fixing device 21 is fitted to the ball screw shaft 22 and the bearing member 23, a ball nut member 24 screwed to the ball screw shaft 22, and a shaft end 22 a of the ball screw shaft 22, and is fixed to the bearing member 23. Brake device 25. As this brake device 25, a commercially available excitation actuation brake device or non-excitation actuation brake device having a normal structure can be adopted.
[0017]
The screw fixing device 21 is configured such that a ball screw shaft 22 and a ball nut member 24 are respectively attached to support members 26 and 27 attached to the side portions of the upper plate 6 and the injection plate 8 in the same position. It is arranged over the injection plate 8.
[0018]
In the figure, the bearing member 23 of the ball screw shaft 22 is attached to the support member 26 and provided on the upper plate 6 side, and the ball nut member 24 is fixed on the support member 27 and provided on the injection plate 8 side. In some cases, the reverse may be possible. In short, it is only necessary that the ball screw shaft 22 is disposed on both sides of the upper plate 6 and the injection plate 8 so that the ball screw shaft 22 rotates as the injection plate 8 moves up and down.
[0019]
In such a screw fixing device 21, the upper plate 6 and the injection plate 8 are connected by screwing the ball screw shaft 22 and the ball nut member 24, but the ball screw shaft 22 is connected to the injection plate 8. Since it is rotatably attached to the upper plate 6, when the injection plate 8 moves in the vertical direction together with the ball nut member 24 by the rotation of the ball screw shaft 10 on the injection driving side or the metering resin pressure, the injection plate 8 Moves in the vertical direction while rotating the ball screw shaft 22 by the ball nut member 24.
[0020]
Therefore, the injection plate 8 moves up and down together with the screw 17 within a range equal to the length of the screw portion without being restrained by the ball screw shaft 22.
When the brake device 25 is operated and the rotation of the ball screw shaft 22 is braked and fixed at the shaft end portion 22a, the ball screw shaft 22 cannot be rotated. Therefore, the injection plate 8 is restrained by the ball screw shaft 22 and cannot move. Then, the brake position is fixed.
[0021]
This braking operation is mainly performed by the injection electric servomotor 12 or the measurement electric servomotor 19 at the injection completion position (see FIG. 4A) and the measurement completion position (see FIG. 4B). Although it is set to synchronize with the stop, it is not specified to those positions, and when a non-excitation actuating brake device is adopted as the brake device 25, the open state is maintained by energization by energization, and the energization is stopped. Unlike the case where a magnetically operated brake device that performs a braking operation by energization is adopted, the braking operation is immediately performed even when the electric servo motors 12 and 19 are stopped due to a power failure. The screw 17 is fixed at that position, and the downward movement of the injection plate 8 and the screw 17 due to gravity is prevented.
[0022]
For this reason, the electric motor with a brake used in the conventional electric vertical injection device is no longer necessary, and the electric motor used in the horizontal injection device can be used as it is for injection. Even if it is provided separately, the cost of the electric vertical injection device can be reduced more than ever.
[Brief description of the drawings]
FIG. 1 is a side view of an electric soot injection device provided with a screw fixing device according to the present invention.
FIG. 2 is a front view of the same.
FIG. 3 is also a plan view.
FIG. 4 is a vertical side view of the screw fixing device at a measurement completion position (A) and an injection completion position (B).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Movable board 2 Support shaft 3 Upper end plate 4 Electric motor for nozzle touch 5 Nozzle touch screw shaft 6 Upper plate 7 Lower plate 8 Injection plate 9 Connecting rod 10 Ball screw shaft for injection
12 Electric servo motor for injection 16 Heating cylinder 17 Screw for injection 18 Ball nut member 19 for injection Electric servo motor for measurement 21 Screw fixing device 22 Ball screw shaft 22a Shaft end 23 Bearing member 24 Ball for screw fixing Nut member 25 Brake device 26, 27 Support member

Claims (2)

A connecting rod in which a plurality of support shafts erected on a movable plate are provided with a lower plate having a heating cylinder with an injection screw facing downward and an upper plate having an electric motor for injection inserted through the injection plate. The screw is driven by a screw shaft and a nut member that move the injection plate together with the screw by converting the rotation of the electric motor into a linear motion between the injection plate and the upper plate. In the electric vertical injection device provided with the device,
A ball screw shaft is rotatably provided on one of the upper plate and the injection plate, and the ball screw shaft is screwed into a ball nut member fixed to the other plate so as to rotate by movement of the injection plate. A screw fixing device in an electric vertical injection device, wherein a ball screw shaft is provided with a brake device for screw fixing. 2. The screw fixing device for an electric vertical injection device according to claim 1, wherein the brake device comprises an excitation operation brake device or a non-excitation operation brake device.

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