JPH0422683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric mold clamping device for an injection molding machine for synthetic resin using a servo motor as a drive source.

[Prior art] In an electric injection molding machine that uses a servo motor as a drive source, even though the servo motor's rotational force can be used to open and close the mold and clamp the mold, the rotational force is not used to maintain the mold clamping force. It is technically extremely difficult to use it.

Therefore, in the electric injection molding machine already known from Japanese Patent Application Laid-Open No. 58-62030, the transmission shaft on the mold clamping side is fixed by a brake at the connection part with the transmission shaft on the injection side, and the mold clamping force is I am trying to maintain this.

[Problems to be Solved by the Invention] When holding the mold clamping force through such a transmission shaft, there is a distance between the fixing point of the transmission shaft and the rotary disk of the screw shaft, so the transmission shaft may be twisted after being fixed. may occur, and the mold clamping force may decrease accordingly.

This twisting of the transmission shaft can be prevented by increasing the diameter of the shaft, but this increases the weight and therefore the inertia, causing problems such as braking by the brake and start-up of rotation after release of fixation.

In addition, when fixing with an electromagnetic brake, since the electromagnetic brake is fitted onto the transmission shaft, a large diameter electromagnetic brake is also required, and due to its large size, commercially available ones cannot be used. , problems such as high costs also arise.

This invention was devised in order to solve such conventional problems, and its purpose is to be able to maintain the mold clamping force by an electromagnetic brake regardless of the transmission shaft, and to make it possible to maintain the mold clamping force by using an electromagnetic brake regardless of the transmission shaft, and to An object of the present invention is to provide an electric mold clamping device for an injection molding machine, which is equipped with a mold clamping force retaining device of a new configuration that can reliably retain mold clamping force with a small force.

[Means for Solving the Problems] This invention according to the above object includes a pair of fixed plates provided on a machine base, and a tie bar provided across both fixed plates, which are arranged so as to be movable forward and backward relative to one of the fixed plates as guide members. a movable platen, a screw shaft for mold clamping coupled to the back surface of the movable platen and having a thread groove around the periphery; the screw shaft is internally threadedly engaged with the screw shaft, and the screw shaft is moved in the axial direction. Connect the rotating member installed on the other fixed plate behind the movable plate and one end to the servo motor,
A transmission shaft having a transmission gear meshing with the gear of the rotating member at the other end, constitutes a mold clamping device, and a bearing portion attached to the other fixed plate of the mold clamping device is provided. A mold clamping force consisting of a brake gear that is integral with the rotating shaft supported by the bearing and the fixed plate and meshed with the transmission gear, and an electromagnetic brake device that is fixed to the bearing and acts on the rotating shaft. It is characterized by being provided with a holding device.

[Operation] In the above configuration, when the brake gear is fixed together with the rotating shaft by the electromagnetic brake device after mold clamping is completed, the rotating member is also fixed via the transmission gear that meshes with the brake gear, and a predetermined mold clamping force is applied. keep it. Further, when the brake gear is released from being fixed by the electromagnetic brake device while applying a rotational force opposite to that during mold clamping to the transmission shaft, the rotating member together with the transmission gear immediately rotates in the opposite direction, causing the mold to open.

[Example] In the figure, 1 is a mold clamping device, and 2 is an injection device.

The mold clamping device 1 includes a pair of fixed plates 10 and 11 installed oppositely on a machine stand 3, and a required number of tie bars 12 and 12 temporarily installed across both fixed plates 10 and 11.
and a movable platen 13 movably attached to the tie bars 12, 12.

Molds 14, 14 are attached to the opposing surfaces of the one fixed platen 11 and the movable platen 13, respectively.
Further, a large diameter screw shaft 15 having a ball screw groove on the circumferential surface is connected to the back surface of the movable platen 13.

As shown in FIG. 2, this screw shaft 15 is connected to the inner end of a rotating member 16, which is a cylindrical body rotatably mounted on the other fixed platen 10 on the back of the movable plate, which serves as a fixed member, using a ball bearing or the like. A gear 17 is attached to the outer end of the rotating member 16, which is screwed into a screw receiving member 16a having a ball 16b, and this gear 17 meshes with a transmission gear 19 at the end of a transmission shaft 18.

The transmission shaft 18 is rotatably supported under the stationary plates 10 and 11, and has a transmission gear 19 at its outer end that is close to the stationary plate 10 and meshes with the gear 17, and at its inner end 20. It has splines.

A transmission shaft 22 disposed in the lower part of the housing 21 of the injection device 2 is connected to the transmission shaft 18 . Further, a joint 24 is connected to the inner end of the transmission shaft 22 via an electromagnetically actuated clutch mechanism 23 so as to be movable toward and away from the shaft. The joint 24 includes a shaft portion rotatably and slidably supported by the housing 21, and a cylinder integrally formed on the outer end of the shaft portion with a spline inside for receiving the inner end portion 20 of the transmission shaft 18. Consisting of

Further, the outer end of the transmission shaft 22 is provided with the housing 2
A servo motor 25 attached to the bottom surface of 1 is connected. This connection is made by placing a drive belt 28 over belt pulleys 26 and 27 provided at the ends of the respective shafts, so that the drive shafts 22 and 18 can be rotated.

The injection device 2 is operated by the servo motor 25 through a plurality of gears attached to the transmission shaft 22 together with a clutch mechanism, and the mold clamping device 1 is operated by the transmission gear 19 attached to the transmission shaft 18. and the gear 17 of the rotating member 16. That is, when the rotating member 6 is rotated clockwise by the gear 17, the upper screw shaft 15 is rotated by the ball 1 on the rotating member side.
6b and the thread groove on the peripheral side of the screw shaft, the movable platen 13 is moved in the mold clamping direction.

In mold clamping using such mechanical means, the rotational force of the servo motor 25 cannot be directly used to maintain the mold clamping force, and an additional mold clamping force retaining device is required.

As shown in FIGS. 2 and 3, the mold clamping force retaining device 30 is formed integrally with a housing 33 attached to the outside of the fixed platen 10, and is connected to a bearing portion 42 provided outside the transmission gear 19. , a brake gear 31 that is integrated with the rotating shaft 34 supported by the bearing part 42 and the fixed platen 10 and meshed with the transmission gear 19, and an inner driver 35 in the field core 38,
The electromagnetic brake device 32 of the brake gear 31 is connected to the outer end of the rotating shaft 34 protruding from the bearing 42 using a key so as to be movable in the axial direction, and is fixed to the bearing 42 with a mounting plate 36. It is composed of.

FIG. 4 shows the structure of the electromagnetic brake device 32, which is usually referred to as negative operation (non-excitation operation), and includes a donut-shaped mounting plate 36 and a field core 38 connected by bolts and nuts. In between, a brake disc 43 and an armature 37 are inserted in an overlapping manner with the armature 37 facing the field core side. Further, a coil spring 40 equipped with an excitation coil 41 and a torque adjustment bolt 39 is disposed inside the field core 38, and the spring pressure of the coil spring 40 causes the armature 37 to
The brake disc 43 is always attached to the mounting plate 36.
is being pressed.

The brake disc 43 is fitted and attached around the inner driver 35 located at the center of the mounting plate 36 and the field core 37 so as to be movable in the axial direction, and rotates together with the inner driver 35. ing.

Excitation coil 41 of such electromagnetic brake 32
When energized, the armature 37 that was pressing the brake disc 43 compresses the coil spring 40 and is attracted to the field core 37, so the brake disc 43 becomes free and the brake on the inner driver 35 is released. .

Therefore, in the mold clamping device 1 of this embodiment, when the electromagnetic brake device 32 is in an excited state, the mold opening/closing and mold clamping can be performed using the rotational force of the servo motor 25. Further, when the molds 14, 14 are completely closed due to the movement of the movable platen 13 and the mold is in a clamped state, when the excitation of the electromagnetic brake device 32 is stopped,
Immediately, the coil spring 40 causes a braking operation, and the brake gear 31 is fixed together with the rotary shaft 34, whereby the rolling gear 19 is also fixed, and the mold clamping force is maintained. Even if the rotational force on the transmission shaft 18 is subsequently released by the operation of the clutch mechanism 23, since the rotating member 16 remains in a fixed state, the mold clamping force against the injection pressure is sufficiently maintained. .

[Effects of the Invention] As described above, the present invention includes a pair of fixed plates 10 and 11 provided on the machine base 3, and a tie bar 12 provided over both fixed plates 10 and 11 as guide members for one fixed plate 11. A movable platen 13 is disposed to move forward and backward, a screw shaft 15 for mold clamping is connected to the back surface of the movable platen 13 and has a threaded groove around its periphery, and is internally screwed together with the screw shaft 15. The other fixed platen 10 at the back of the movable platen moves the screw shaft 15 in the axial direction.
a transmission shaft 18 having one end connected to a servo motor 25 and a transmission gear 19 meshing with the gear 17 of the rotation member 16 at the other end;
A mold clamping device 1 is constructed from the above, and the other fixed platen 10 of the mold clamping device 1 includes a bearing part 42 attached to the fixed platen 10, and a rotating part supported by the bearing part 42 and the fixed platen 10. Integrally with the shaft 34, the transmission gear 1
9 and the brake gear 31 meshed with the bearing part 4.
A mold clamping force retaining device 30 consisting of an electromagnetic brake device 32 fixed to the rotary shaft 24 and acting on the rotating shaft 24 is provided. Since the force can be maintained, there is no change in the mold clamping force even if the rotational force of the servo motor is removed, and during that time the rotational force of the servomotor can be used as a drive source for the injection device.

In addition, the rotating shaft of the brake gear is fixed by an electromagnetic brake device, and the gears are fixed to each other to maintain mold clamping force, which solves the problem that occurs when directly fixing the transmission shaft, and even with a small braking force. Sufficient mold clamping force can be maintained. Furthermore, by adopting a negative actuation brake device, not only responsiveness but also safety can be improved, and since a commercially available electromagnetic brake device can be used, there is no need for high costs.

[Brief explanation of drawings]

The drawings show an embodiment of an electric mold clamping device for an injection molding machine according to the present invention. FIG. 1 is a partially vertical side view of the molding machine, FIG. Figure 3 is an end view of the mold clamping device with a part cut out.
FIG. 4 is a longitudinal sectional side view of the electromagnetic brake device. 1... Mold clamping device, 2... Injection device, 3... Machine stand, 10, 11... Fixed platen, 13... Movable platen, 1
5...Screw shaft, 16...Rotating member, 16a...Screw receiving member, 17...Gear, 18...Transmission shaft, 19
... Transmission gear, 25 ... Servo motor, 30 ...
Mold clamping force holding device, 31...brake gear, 32...
...Electromagnetic brake device, 34...Rotation shaft, 42...
Bearing part, 43...Brake disc.

Claims (1)

[Claims] 1. A pair of fixed plates provided on the machine base, a movable platen that is arranged to move forward and backward with respect to one of the fixed plates using a tie bar installed across both fixed plates as a guide member, and a pair of fixed plates coupled to the back side of the movable platen, and a mold clamping screw shaft with a threaded groove around its periphery; a rotating member provided on the other stationary plate at the back of the movable plate that is internally threaded with the screw shaft and moves the screw shaft in the axial direction; A mold clamping device is constituted by a transmission shaft having one end connected to a servo motor and the other end having a transmission gear that meshes with the gear of the rotating member, and the other fixed plate of the mold clamping device,
a bearing part attached to the fixed plate; a brake gear integral with the rotating shaft supported by the bearing part and the fixed plate; and a brake gear meshing with the transmission gear; and a brake gear fixed to the bearing part and acting on the rotating shaft. An electric mold clamping device for an injection molding machine, comprising a mold clamping force holding device comprising an electromagnetic brake device.