JPH01192519A - Mold clamping device of injection molding machine - Google Patents

Abstract

PURPOSE:To reduce a mounting apace of an injection molding machine by miniaturizing a mold clamping device, by generating mold clamping force by a mechanism performing frictional joining to a tie bar through a wedgy action. CONSTITUTION:When mold clamping is completed by actuating a mold breaking and clamping cylinder 16, hydraulic oil is fed to oil chambers 48, 54 and discharges hydraulic oil of oil chambers 50, 52. With this construction, force of a direction where both a large diameter piston 30 and small-diameter piston 32 approach close to each-other is applied to both of them, a tapered axial part 40 and tapered hole part 42 are stuck close to each other, wedgy action is generated between both of them and the tapered axial part 40 receives force of a direction where the tapered axial part 40 contracts toward an inner diameter side. Therefore, a lining 44 is clamped down strongly to the outer circumference of a tie bar 14. When hydraulic pressure of the oil chamber 48 is raised, as a sleeve 38 and the tie bar 14 are joined to each other frictionally, mold clamping force is generated on the tie bar.

Description

[Detailed description of the invention] (b) Industrial application field The present invention relates to a mold clamping device for an injection molding machine.

(b) Conventional technology As a conventional mold clamping device for an injection molding machine, for example,
There are two types of mold clamping devices: a toggle type mold clamping device as shown in Japanese Utility Model Publication No. 0-157054, and a direct pressure type mold clamping device shown in Japanese Utility Model Application No. 111830/1983. A toggle type mold clamping device uses a toggle mechanism to double the pushing force of a relatively small-diameter hydraulic cylinder to press a movable platen. Further, a direct pressure type mold clamping device is one in which a large diameter hydraulic cylinder directly presses a movable platen.

(c) Problems to be solved by the invention However, the mold clamping device of the conventional injection molding machine as described above requires a large-diameter hydraulic cylinder or a toggle mechanism, resulting in a large structure and a large installation space. There is a problem with this. The present invention aims to solve such problems.

(d) Means for Solving the Problems The present invention solves the above problems by generating mold clamping force using a mechanism that frictionally engages the tie bars through a wedge action. That is, the mold clamping device of the injection molding machine according to the present invention includes a movable platen (12) on the side opposite to the side facing the fixed platen (10) so as to coaxially surround each tie bar (14). A cylinder (20) is provided, and a first piston (30) and a second piston (32) are provided in the cylinder, and the first piston and the second piston move independently by the hydraulic pressure applied thereto. The first piston and the second piston each have a tapered hole (42) and a tapered shaft (40) that can contact each other, and the tapered shaft that is fitted onto the outer periphery of the tie bar is connected to the tapered hole. When pressed against the tie bar, the tie bar is configured to contract inward and be coupled to the tie bar by frictional force.

(E) Action: For example, hydraulic pressure is applied to the first piston and the second piston in a direction that causes them to approach each other. As a result, the tapered hole portion and the tapered shaft portion are pressed in a direction in which they come into close contact with each other.

As a result, the hollow tapered shaft portion side tends to deform in a direction that reduces the inner diameter. Since the tie bar fits into the inner diameter of the tapered shaft, the inner diameter of the tapered shaft tightens the outer diameter of the tie bar. This brings the tie bar and the tapered shaft portion into a state where they are coupled by frictional force. In this state, if a difference is given between the hydraulic pressure acting on the first piston and the hydraulic pressure acting on the second piston, a tensile force will be applied to the tie bar by this difference. This force causes a clamping force to act on the mold.

(F) Embodiment FIG. 3 shows the overall structure of a mold clamping device for an injection molding machine according to the present invention. A movable platen 12 is provided so as to face a fixed platen 10 fixed to a stationary part, and both are connected by tie bars 14. The movable platen 12 is guided by tie bars 14 and is movable toward and away from the fixed platen 10. Fixed platen 10 and movable platen 12
A mold opening/closing cylinder 16 serving as a mold opening/closing mechanism is provided between the movable platen 12 and the movable platen 12 as described above. A mold clamping force generating mechanism 18 is provided on the surface of the movable platen 12 opposite to the side facing the fixed platen 10. A mold clamping force generating mechanism 18 is provided corresponding to each tie bar 14.

This mold clamping force generating mechanism 18 is shown in an enlarged scale in FIG. A cylinder 20 is attached to the movable platen 12 with bolts 22. The cylinder 20 is composed of a large-diameter cylinder member 24, a small-diameter cylinder member 26, and a flange member 28, which are overlapped and fastened to the movable platen 12 with bolts 22. The flange member 28 partitions the large-diameter cylinder member 24 side and the small-diameter cylinder member 26 side, and a large-diameter piston 30 is fitted into the inner diameter part of the large-diameter cylinder member 24 side, and a small-diameter piston 32 is fitted on the small-diameter cylinder member 26 side. Fit together. Large diameter piston 30
A spring 34 is provided between the small diameter piston 32 and the flange member 28, and a spring 36 is provided between the small diameter piston 32 and the flange member 28. A sleeve 38 is integrally formed with the small diameter piston 32. Small diameter piston 3
2 and sleeve 38 are hollow, the inner diameter of which typically fits loosely into the outer diameter of tie bar 14. A tapered shaft portion 40 is provided at the distal end of the sleeve 38, and the diameter thereof decreases toward the distal end, and a tapered hole portion 42 is provided at the inner diameter portion of the large diameter piston 30 corresponding to this. .

A lining 4 with a high friction coefficient is provided on the inner diameter portion of the tapered shaft portion 40.
4 is provided. Further, a slit 46 is provided on the distal end side of the sleeve 38 to facilitate deformation in the radial direction. By arranging the large diameter piston 30 and the small diameter piston 32 in this manner, oil chambers 48 and 50 are formed on both sides of the large diameter piston 30, respectively, and an oil chamber 52 and an oil chamber 54 are formed on both sides of the small diameter piston 32, respectively. be done. Note that seal members are provided at each location necessary for hydraulic sealing. Hydraulic pressure can be supplied to the oil chamber 48 and the oil chamber 50 from oil pressure supply ports 56 and 58, respectively, and the oil chamber 52 and the oil chamber 54 each have a hydraulic pressure supply port 6.
Oil pressure can be supplied from 0 and 62.

Next, the operation of this embodiment will be explained. When the mold clamping operation is not performed, the mold clamping force generating mechanism 18 is in the state shown in FIG. 2. That is, hydraulic pressure is supplied to the oil chamber 50,
No oil pressure is acting on the oil chamber 48. Therefore, the large diameter piston 30 is pushed rightward in the figure by the oil pressure in the oil chamber 50 and the force of the spring 34. Further, oil pressure is supplied to the oil chamber 52, but no oil pressure is applied to the oil chamber 54.

Therefore, the small diameter piston 32 is pushed leftward in the figure by the hydraulic pressure of the oil chamber 52 and the force of the spring 36.

Therefore, the tapered shaft portion 40 and the tapered hole portion 42 are separated from each other, and no force is applied to the tapered shaft portion 40 from the outer circumferential side. Therefore, the sleeve 38 is movable in the ring direction relative to the tie bar 14. By operating the mold opening/closing cylinder 16 in this state, the movable platen 12 can freely move along the tie bars 14, and the mold opening/closing operation can be performed.

When applying mold clamping force, first the mold opening/closing cylinder 16 is operated to close the mold. When the mold closing is completed, the oil chamber 4
8 and discharges the oil pressure in the oil chamber 50. Also,
Hydraulic pressure is supplied to the oil chamber 54, and hydraulic pressure in the oil chamber 52 is discharged.

As a result, a force is applied to the large-diameter piston 30 and the small-diameter piston 32 in a direction in which they approach each other. As a result, the tapered shaft portion 40 and the tapered hole portion 42 come into close contact with each other.
A wedge effect occurs between the two, and the tapered shaft portion 40 receives a force that causes it to contract inward.

Therefore, the lining 44 is strongly tightened around the outer periphery of the tie bar 14. Since the lining 44 is made of a material with a large coefficient of friction, a large frictional force is generated, and the sleeve 38 is coupled to the tie bar 14 by the frictional force. When the hydraulic pressure in the oil chamber 48 is increased in this state, a force directed to the left in the figure, that is, a mold clamping force, is generated on the tie bar 14 because the sleeve 38 and the tie bar 14 are frictionally connected as described above. Become. 1 tie bar each
It is possible to generate the necessary mold clamping force as a whole until the same effect is obtained in the mold clamping force generating mechanism 18 provided at 4.

When releasing the mold clamping force, by switching the hydraulic pressure supply state in the same way as the above-mentioned mold clamping force non-action state, the close contact between the tapered shaft portion 40 and the tapered hole portion 42 is released, and the tie bar 14 is released.
and the sleeve 38 can be moved relative to each other.

In this embodiment, the tapered shaft portion 40 is provided on the sleeve 38 side that is integrated with the small diameter piston 32, and the tapered hole portion 42 is provided on the large diameter piston 30 side, but this may be reversed. Further, although the large diameter piston 30 is made larger than the small diameter piston 32, the pistons may have the same diameter.In this case, the oil pressure in the oil chamber 48 can be made higher than the oil pressure in the oil chamber 54. It is possible to obtain a strong mold clamping force.

(g) As described in detail, according to the present invention, the piston of the mold clamping force generating mechanism can be attached to the tie bar by a wedge action, and the mold clamping force generating mechanism is arranged for each tie bar. Compared to the case of using a conventional direct pressure cylinder or toggle mechanism, a large installation space behind the movable platen is not required, and the mold clamping device can be made smaller. This allows the installation space of the injection molding machine to be reduced.

[Brief explanation of the drawing]

Fig. 1 is an enlarged view of the mold clamping force generation mechanism of the present invention (a diagram showing a mold clamping force generation state), and Fig. 2 is a view of the mold clamping force generation mechanism shown in Fig. 1 in a state in which the mold clamping force is not generated. FIG. 3 is a diagram showing the overall structure of a mold clamping device of an injection molding machine. 10... Fixed plate, 12... Movable plate, 14... Tie bar, 16... Mold opening/closing cylinder, 18... Mold clamping force generation mechanism, 20... Cylinder, 30... Large diameter Piston, 32... Small diameter piston, 38... Sleeve, 40
...Tapered shaft part, 42...Tapered hole part, 44...
lining. Patent applicant: Japan Steel Works, Ltd.

Claims (1)

[Scope of Claims] A fixed platen, a movable platen arranged to face the fixed platen and movable in a direction toward or away from the fixed platen, and a movable platen that guides the movable platen and moves between the fixed platen and the movable platen. a tie bar that supports the mold clamping reaction force; a mold opening/closing mechanism that drives the movable platen in a direction toward or away from the fixed plate;
In a mold clamping device for an injection molding machine having a movable platen, a cylinder is provided on the opposite side of the movable platen from the side facing the fixed platen so as to coaxially surround each tie bar, and a cylinder is provided in the cylinder so as to coaxially surround each tie bar. A first piston and a second piston are provided, and the first piston and the second piston are movable independently by hydraulic pressure applied thereto.
The piston and the second piston each have a tapered hole and a tapered shaft that can come into contact with each other, and the tapered shaft that fits onto the outer periphery of the tie bar shrinks inward when pressed against the tapered hole, thereby forming the tie bar. A mold clamping device for an injection molding machine, characterized in that the mold clamping device is configured to be coupled by frictional force to the mold clamping device.