JPS63209818A - Mold clamping device for injection molding machine - Google Patents

Abstract

PURPOSE:To eliminate the need for an end housing and a tie bar, and to miniaturize the whole mold clamping device by mounting a specific link mechanism between a fixed plate and a movable plate. CONSTITUTION:When a hydraulic cylinder 40 is operated and a crosshead 38 is moved forward in the right direction in the fugure, a third link 22 connected to the crosshead 38 through a driving link 24 is turned in the counterclockwise direction. Consequently, a first link 18, a second link 20 and the third link 22 are displaced in the folding direction, and a movable plate 12 is brought near to the fixed plate 10 side, and a movable mold 16 may be brought into contact with a fixing mold 14. The crosshead 38 is further pushed out from that state, they a pin 26, a pin 32, a pin 30 and a pin 28 are positioned on approximately a straight line. A large tensile force works between a fixed plate 10 and the movable plate 12 under that state, thus clamping force is to the fixing mold 14 and the movable mold 16.

Description

[Detailed description of the invention] (b) Industrial application fields 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 is a toggle type mold clamping device as shown in Japanese Patent No. 0-157054. The mold clamping device shown here has three plates: a fixed plate, a movable plate, and an end housing, and a plurality of tie bars connecting these plates, and the force of the hydraulic cylinder installed in the end housing is transferred to the end housing. The movable platen is configured to be pressed against the fixed platen by a toggle mechanism provided between the movable platen and the movable platen.

(c) Problems to be solved by the invention However, in the mold clamping device of the conventional injection molding machine as described above, the emergency stop mechanism for pressing the movable platen against the fixed platen is large and has a large size compared to the total length of the injection molding machine. It requires about 30% of the length. Furthermore, as mentioned above, three boards and a tie bar to connect them are required. For this reason, the overall size of the device becomes very large, and the installation space for the device also becomes large. The present invention aims to solve these problems.

(d) Means for solving the problems The present invention solves the above problems by providing a link mechanism between the fixed platen and the movable platen. That is, the mold clamping device for an injection molding machine according to the present invention includes a stationary first plate (fixed plate 10) with a mold attached to opposing sides thereof, and a second plate movable in a direction toward the mold or a direction away from the mold. A board (movable board 12) and a first link (18) hinged to the first board.
), a second link (20) that is hinged to the second board, and a mold (14) for the first board and a mold (16) for the second board that are hinged to the first link and the second link, respectively. The third link (22) forms an acute angle with the first link and the second link when the 32) and a drive device (hydraulic cylinder 40) that can apply a force to relatively rotate the parts. Note that the symbols in parentheses indicate corresponding members in the embodiments described later.

(E) Effect When the drive device is operated with the mold of the first plate and the mold of the second plate in contact and the third link is rotated in a direction that reduces the acute angle formed by the link, the third link The displacement in the rotational direction is converted into a minute linear movement in the longitudinal direction of the first link and the second link. Therefore, the rotational force applied to the third link is greatly boosted and transmitted to the first and second links, and the first and second links apply force in the direction of bringing the first and second plates closer together. . As a result, a large force can be applied between the molds, and a function as a mold clamping device can be obtained.

(F) Example (First Example) FIG. 1 shows a first example of the present invention. A fixed platen 10 and a movable platen 12 are provided so as to face each other, and the movable platen 12 is movable toward or away from the fixed platen 10. A fixed die 14 is attached to the fixed platen 10, and a movable die 16 is attached to the movable platen 12. The fixed platen 10 and the movable platen 12 have a first link 18 and a second link.
They are connected by a link mechanism consisting of a link 20, a third link 22, and a drive link 24. The link mechanisms are symmetrically arranged above and below the sides of the fixed platen 10 and the movable platen 12, and the sides of the fixed platen 10 and the movable platen 12 shown in FIG. 1 are different from each other. Similarly, two sets of link mechanisms are provided on the opposite side, for a total of 4
A pair of linkages are provided. The first link 18 is hinged at one end to the stationary platen 10 by a pin 26. Further, the second link 20 is hinged to the movable platen 12 at one end via a pin 28. 1st link 18
The other end is hinged to one end of the third link 22 by a pin 30, and the other end of the second link 20 is connected to a position near the other end of the third link 22 by a pin 32. There is. The other end of the third link 22 is hinged to one end of the drive link 24 by a pin 34 . The other end of the drive link 24 is hinged to a crosshead 38 by a pin 36. The crosshead 38 is attached to the tip of a piston rod 40a of a hydraulic cylinder 40 attached to a movable platen. Note that the drive link 24 of the upper and lower link mechanisms is connected to a crosshead 38 driven by one hydraulic cylinder 4o. That is, the two link mechanisms are driven by one hydraulic cylinder. Note that the two link mechanisms not shown in FIG. 1 are also configured to be driven by a single hydraulic cylinder. That is, the mold clamping device of this injection molding machine is configured to operate four link mechanisms using two hydraulic cylinders 40.

Next, the operation of this embodiment will be explained. The state shown in FIG. 1 is the mold opening state, but when the hydraulic cylinder 40 is operated from this state and the crosshead 38 is moved forward in the right direction in FIG. The connected third link 22 rotates counterclockwise (for the upper link mechanism). As a result, the first link 18, the second link 20, and the third link 22 are displaced in the folding direction, and the movable platen 12 is brought closer to the fixed platen 10 side. This allows the movable mold 16 to come into contact with the fixed mold 14. From this state, cross head 3
By pushing out 8, the bins 26, 32, 3
0 and the bin 28 can be positioned almost in a straight line, and in this state, a large tensile force acts between the fixed platen 10 and the movable platen 12, and a mold clamping force is applied to the fixed mold 14 and the movable mold 16. can be done. To open the mold, the hydraulic cylinder 40 is operated in the opposite direction to move the crosshead 38 back to the left in FIG. In addition, since the two hydraulic cylinders 40 provided on both sides of the fixed platen 10 and the movable platen 12 are operated synchronously, the movable platen 12 operates smoothly.

The fact that a large mold clamping force can be obtained by the link mechanism as described above will be explained based on a drawing for explaining the principle shown in FIG. 2. The second link 20 and the third link 22 intersect with each other at an acute angle θ. In this state, by applying a rotational force to the third link 22 in the direction of decreasing θ, the bottle 3
When a force F is applied to the second link 20, a tensile force F is applied to the second link 20.
2 is generated, and a compressive force F3 is also generated in the third link 22. The following relationship exists between the stiffening forces Fl, F2, and F3.

F, /Sinθ =F2757 mouth 90" = F 3 / Sin (90' - 0) Therefore, F2=(Sin 90°/Sinθ)XF.

Fa −(Sin (90°−θ)/Sinθ)xF
.

Therefore, the smaller θ is, the more F2 and F3 become F.
It becomes a large value for . Since the force F2 becomes a tensile force that acts in the direction of moving the movable platen 12 closer to the fixed platen 10, a large mold clamping force can be obtained as described above.

In this embodiment, two hydraulic cylinders 40 are used to operate the four link mechanisms, but one hydraulic cylinder is provided for each link mechanism, and the four hydraulic cylinders are operated in synchronization. You can do it like this. Further, as long as the crosshead 38 can be moved forward and backward, a combination of an electric motor and a ball screw mechanism, for example, may be used instead of the hydraulic cylinder. Further, in this embodiment, the bin 34 is provided on a straight line connecting the bins 30 and 32, but it may be provided at a position other than this straight line. Also,
Although the first link 18, the second link 20°, the third link 22, and the drive link 24 are each made up of one member, all or part of these may be made up of two parallel members.

(Second Embodiment) FIGS. 3 and 4 show a second embodiment of the present invention. FIG. 3 shows only the upper half of the mold clamping device of the injection molding machine. The fixed platen 10 and the movable platen 12 are connected by a first link 18, a second link 20, and a third link 22. A sprocket 52 provided to rotate together with the rotating shaft of an electric motor (or hydraulic motor) 50 attached to the movable platen 12 and a sprocket 56 rotatably supported by a bearing 54 on the bin 28 are connected to the chain 58. They are connected together. The sprocket 56 has two teeth 56a and 56b as shown in FIG. 4, and the chain 58 is wound around the teeth 56a. Third link 22
A sprocket 64 is provided to the bin 32, which is connected to the bin 32 so as to rotate together with the key 6o. A chain 66 is wound around this sprocket 64 and the teeth 56b of the sprocket 56 described above. Note that the second link 20 is the bin 28
and bin 32 by bearings 68 and 70, respectively. Even in the second embodiment with such a configuration, when the electric motor 50 is operated to generate rotational force, this is transmitted to the third gear via the sprocket 52, the chain 58, the teeth 56a1 of the sprocket 56, the teeth 56b1 of the sprocket 56, the chain 66, the sprocket 64, and the pin 32. is transmitted to link 22. As a result, the first link 18 and the second link 20
If the third link 22 is operated in a direction in which the acute angle formed by these links becomes smaller, a large mold clamping force can be generated as in the first embodiment described above. Moreover, by rotating the electric motor 50 in the reverse direction, the mold can be opened. In addition, the electric motor 50
As a mechanism for transmitting the rotational force to the third link 22, it is also possible to use a worm, a worm wheel, a rack, a binion, or the like.

In addition to the two embodiments described above, the fixed platen 10 and the movable platen 12 may be replaced, the link mechanisms may be provided on the upper and lower parts of the fixed platen 10 and the movable platen 12 instead of on the sides, and the fixed platen 10 and the movable platen 12 may be It is also possible to arrange the movable platen 2 in the vertical direction to form a vertical device.

(G) As described in detail, according to the present invention, since the link mechanism is disposed between the fixed platen and the movable platen, the overall length is reduced compared to the mold clamping device of a conventional injection molding machine. Can be shortened. Furthermore, the end housing and tie bar that were conventionally required are no longer necessary.

Since tie bars are not required, the outer circumferences of the fixed platen and movable platen can also be made smaller. In this way, the number of large parts is reduced, the mold clamping device as a whole can be downsized, the installation space can be reduced by about 30% compared to the conventional method, and the price can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the invention, FIG. 2 is a diagram for explaining the invention in detail, FIG. 3 is a diagram showing a second embodiment of the invention, and FIG. 4 is a diagram showing a second embodiment of the invention. FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG. 3; DESCRIPTION OF SYMBOLS 10... Fixed plate, 12... Movable plate, 14... Fixed type, 16... Movable type, 18... First link, 20...
...Second link, 22...Third link, 26, 28,
30, 32, 34° 36...Bin, 40...Hydraulic cylinder.

Claims (1)

[Scope of Claims] 1. A first plate and a second plate, each having a mold attached to their opposing sides and one of which is movable relative to the other in a direction toward the mold or a direction away from the mold; A first link that is hinged to the second plate, a second link that is hinged to the second plate, and a mold that is hinged to the first link and the second link and contacts the mold of the first plate and the mold of the second plate. In this state, the third link forms an acute angle with the first link and the second link, and a force can be applied to the third link to rotate one hinge connection point of the third link relative to the other hinge connection point. A mold clamping device for an injection molding machine consisting of a driving device and a drive device. 2. The mold clamping device for an injection molding machine according to claim 1, wherein a plurality of sets of the same structure are provided, each of which is a combination of a first link, a second link, and a third link.