JPH0248912A - Motor-driven injection device - Google Patents

Abstract

PURPOSE:To contrive universal adjustment control of an advance motion speed of a screw of an injection molding machine, by a method wherein turning force of a servomotor is converted into a linear motion by a specific mechanism of a screw shaft and screw holding member. CONSTITUTION:A servomotor is turned, a clutch mechanism 41 is actuated through a driving belt 43 and a transmission gear 39 is turned along with a transmission shaft. With this construction, a screw shaft 30 is turned along with a gear 29 and a screw holding member 25 is moved forward with a lead of a screw. Since the screw holding member 25 is born by an extended shaft 27 of a rear end of the screw, also that screw 20 is moved forward along with the extended shaft 27 and performs injection. Since the title device is constituted so that forward movement of the screw 20 is performed by converting turning force of the servomotor into linear motion by a mechanism consisting of a screw supporting member 28 and screw shaft 30, torque control and speed control covering a wide area become possible.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to an electric injection device.

[Prior Art] As an electric injection device, the one described in Japanese Utility Model Publication No. 39-10424 is known.

This injection device rotatably connects a screw shaft to a holding member at the rear end of the plunger, and a commonly used electric motor rotates a screw receiving member screwed into the screw shaft at a fixed position to hold the holding member together with the screw shaft. It consists of a structure that moves forward and backward.

[Problem to be solved by the invention] A normal electric motor used in such a conventional device is
It is unsuitable for starting, stopping, and rapid acceleration/deceleration control of electric motors, and is difficult to use for injection devices that require high-speed response.

In addition, torque control is difficult, and practical application has been considered extremely difficult due to the inability to perform high-precision speed control over a wide range from low speed to rated speed.

This invention was devised to solve the above-mentioned problems with electric injection devices, and its purpose is to achieve high speed response, high precision speed control, torque control, etc. while using an electric motor as an injection drive source. Our objective is to provide an excellent electric injection device.

[Means for Solving the Problems] The features of this invention according to the above-mentioned objects include a screw of an injection heating cylinder having an extension shaft at the rear end, a screw that is rotatably held via the extension shaft, and a screw that moves forward and backward together with the screw. The moving holding member and the screw receiving member provided on the screw holding member are screwed together via balls, and the rotational force from the injection drive source is converted into linear interlocking for advancing the screw with the screw receiving member. The injection drive source is a servo motor.

[Function] In the above configuration, the rotational force of the servo motor is transmitted to the screw shaft, and when the screw shaft rotates, the screw receiving member side moves forward together with the screw holding member.

As a result, the screw of the injection heating cylinder also moves forward, and the molten resin is injected.

The present invention will be explained in detail below with reference to embodiments shown in the drawings.

[Example] In the figure, 1 indicates a mold clamping device, and 2 indicates an injection device. The mold clamping device 1 includes a tie bar 12 installed on a pair of fixed plates 10 and 11 on a machine stand 3, and a movable plate 13 movably attached to the tie bar 12. Molds 14 and 14 are provided on the opposing surfaces of the one fixed platen 11 and the movable platen 13, respectively.
Further, a screw shaft 15 is provided protruding from the opposite side of the movable platen 13. This screw shaft 15 is screwed through a ball into a rotary disk 16 rotatably attached to the other fixed plate 10, and a gear 17 is attached to the rotary disk 16.
When the rotary plate 16 rotates at the same time, the screw shaft 15 moves together with the movable plate 13 by the screw lead.

The injection device 2 includes an injection heating cylinder 21 containing a screw 20.
and a housing 22 on the machine base that also serves to hold the injection heating cylinder 21. Inside the housing 22, there is a rear end of the screw 20 and a pair of support shafts 24.24 installed on both sides in parallel with the screw. It is slidably mounted.

Further, an extension shaft 27 having a gear 26 is connected to the rear end of the screw 20, and the end of the extension shaft 27 is rotatably connected to the screw holding member 25.

Furthermore, the screw receiving member 28 provided at the rear of the screw retaining portion 25 has a screw shaft 3 which is rotatably held on the housing wall 22a and is integral with a shaft portion 30a having a gear 29.
0 is screwed in via a ball, and the outer end of the shaft portion 30a is connected to a brake device 31 fixed to the housing wall portion 22a. This brake device 31 is equipped with a hysteresis brake inside.

This hysteresis brake consists of three parts: a field, a rotor, and a cup. When the field containing the excitation coil is magnetized by energization and a magnetic field is generated between the outer and outer magnetic poles of the rotor, the cup placed in the magnetic field also It is magnetized and has a structure in which the cup and the cup are connected magnetically, and is commonly commercially available. 32 is a transmission shaft on the mold clamping device side, 33 is a transmission shaft on the injection device side, and as shown in FIG. A transmission gear 35 is provided close to the stationary platen 10 and meshed with the gear 17. Further, the transmission shaft 32 is connected to a transmission shaft 36 via a joint 36a having a spline, and the transmission shaft 36 is connected to the transmission shaft 36 through a joint 36a having a spline.
3 and are connected to each other via an electromagnetically actuated clutch mechanism 34 so as to be able to freely approach and separate.

Further, the transmission shaft 33 is rotatably supported in the lower part of the housing 22 together with another transmission shaft 37, and the transmission shaft 33.
Transmission gears 38 and 39 that mesh with the gears 26 and 29, respectively, and a plurality of electromagnetically actuated clutch mechanisms 40 and 41 that rotate and stop the gears are provided on the transmission @ 37. A servo motor 42 is connected to the drive belt 43 via a drive belt 43.

Note that 44.45 is a driving gear provided on the transmission shaft 33.37, 46 is a screw shaft for nozzle touch, and 47 is a screw shaft 46.
It is a clutch.

In the example shown in FIG. 5, the support shafts 24 and 24 are rotatably installed, and the insides thereof are screw shafts 24a, 24a, and screw receiving members 28 are provided at both ends of the screw holding member 25.
．． 28 is provided and screwed into the screw shafts 24a, 24a through balls, respectively, and the support shafts 24.24
is further provided with gears 29a, 29a that mesh with the gear 29, the rotation of the gear 29 is transmitted to the support shaft 24, 24 via the gears 29a, 29a, and the screw holding member 25 is moved forward and backward together with the screw 20 by the screw lead. It consists of a structure that

Next, the injection molding process will be explained.

With the clutch mechanism 34 connecting the transmission shafts 32 and 33, the servo motor 42 is rotated forward. At this time, on the injection device 2 side, the transmission gears 38 and 39 are set in a free state by the operation of the clutch mechanisms 40 and 41.

The rotary disk 16 is rotated by the transmission shaft 32, the transmission gear 35, and the gear 17, and the screw shaft 15 is sent out. As a result, the movable platen 13 moves forward, the molds 14 and 14 are closed, and even stronger mold clamping is performed. When the mold clamping pressure reaches a predetermined pressure, the brake 48 is activated to fix the transmission shaft 32, and the clutch mechanism 34 is further activated to disconnect the transmission shaft 33.

Further, on the injection device side, the clutch mechanism 41 is activated by the command, and the three transmission gears are rotated together with the transmission shaft 33. As a result, the screw shaft 30 is rotated together with the gear 29, and the screw holding member 25 is advanced by the screw lead. This screw holding member 25 includes an extension shaft 27 at the rear end of the screw.
Since this is a bearing, the screw 20 also moves forward together to perform injection.

When the injection is completed, the servo motor 42 is stopped by the command, and at the same time, the clutch mechanism 41 is operated to disconnect the gear 39. Next, the clutch machine M440 is operated to cause the transmission gear 38 to rotate together with the transmission shaft 37. Then, when the servo motor 42 rotates in the reverse direction again, the screw 20 rotates and the material is transferred. The backward force generated in the screw 20 due to the transfer of the material generates a rotational force in the screw shaft 30 through the screw holding member 25 in a direction opposite to that when the screw advances.

At the same time, the brake device 31 is actuated to apply a brake force to the screw shaft 30, so that the material is measured while generating so-called screw back pressure.

When the weighing is completed, on the mold clamping mechanism side, the electromagnetic brake 48 is released and the clutch mechanism 34 is activated to connect the transmission shaft 32 to the transmission shaft 33 again. Further, by rotating the servo motor 42 in the reverse direction, the screw shaft 15 rotates in the reverse direction to open the mold, completing one cycle of injection molding.

[Effects of the Invention] As described above, the present invention uses a servo motor as an injection drive source, and uses the rotational force of the servo motor to generate a straight line by connecting a movable screw receiving member screwed together via a ball and a screw shaft in a fixed position. Since the screw can be moved forward by being converted to interlocking, there are no inconveniences that occur when a normal electric motor is used as the injection drive source, and it is durable against high loads, which is essential as a drive source for injection equipment. It is possible to meet the demands of high performance and adjustment characteristics with 1 precision, and while the electric motor is used as the injection drive source, the ball screw has good transmission efficiency, torque control is easy, and speed control over a wide range can be performed with high precision. It has the following advantages.

[Brief explanation of the drawing]

The drawings show one embodiment of the electric injection device according to the present invention, and FIG. 1 is a side view of the injection molding machine, FIG. 2 is a cross-sectional plan view of the injection device, and FIG. 3 is a longitudinal cross-section of the housing portion. 4 is a cross-sectional plan view of the lower portion of the housing, FIG. 5 is a cross-sectional plan view of another embodiment of the injection device, and FIG. 6 is a vertical cross-sectional view of the housing portion of FIG. 5. 1... Mold clamping device 2... Injection device 20... Screw 21... Injection heating direction 24... Support shaft 25... Screw holding member 27... Extension shaft 28...Screw receiving member 29...Gear 3o...Screw shaft 42...Servo motor

Claims (1)

[Claims] A screw of an injection heating cylinder having an extension shaft at the rear end, a holding member that rotatably holds the screw via the extension shaft and moves forward and backward together with the screw, and a screw receiving member provided on the screw holding member. Screw together through the ball,
An electric injection device comprising a fixed-position screw shaft that converts rotational force from an injection drive source into linear interlocking for advancing the screw using the screw receiving member, and the injection drive source is a servo motor. .