JPH04224910A - Mold clamping device - Google Patents

Abstract

PURPOSE:To simplify a mold clamping device for an injection molding machine and enhance controllability of opening and clamping molds. CONSTITUTION:Cylinders 24 are provided unitarily with one surface of a movable die plate 12 on its portions where tie rods 20 penetrate through the die plate, thereby causing the tie rods to penetrate through the cylinders, and the tie rods are provided with a piston part 26, respectively. A working fluid is fed into and discharged from fluid pressure chambers 28, 30, each being divided into two sections by the piston part, so that the movable cylinders 24 are driven to enable molds to be clamped. By giving a difference in pressure receiving areas to the fluid pressure chambers, the die plate can be regulated so as to be moved at a high speed.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a mold clamping device, and more particularly to a direct pressure type mold clamping device in which a moving die plate is directly actuated by a hydraulic cylinder mechanism, and the present invention is a mold clamping device suitable for application to an injection molding machine. Regarding equipment.

0002

2. Description of the Related Art In an injection molding machine, a mold is attached to a die plate called a platen, and the die plates are moved close to each other to perform mold clamping. Usually, a die plate consists of a fixed side and a moving side.
The mold is clamped by moving the movable die plate by pressing it with a hydraulic cylinder mechanism. In addition, the hydraulic cylinder and stationary die plate are connected by tie rods to maintain pressure force during mold clamping and to accurately align the molds.
The movable die plate is configured to move while being guided by tie rods.

By the way, in a direct pressure type mold clamping device for an injection molding machine, a movable die plate is directly connected to a ram in a mold clamping cylinder located at the center of pressure, and the mold is directly clamped by hydraulic pressure. That's what I do. In this case, the diameter of the ram cinder is increased in order to increase the mold clamping force, but there is a problem in that a large capacity hydraulic pump is required to move the ram cinder at high speed to the mold matching position. For this reason, mold clamping devices have conventionally been used that are provided with auxiliary drive means for performing high-speed movement for opening and closing the mold.

Conventional mold clamping devices of this type include a booster ram type, an auxiliary cylinder type, a pressure increasing cylinder type, and the like. Booster type equipment has a booster ram built into the mold clamping ram, and the small diameter booster ram moves the mold to the mold matching position at high speed, and mold clamping is performed by supplying pressure oil to the large diameter mold clamping ram. . The auxiliary cylinder type has a structure in which an auxiliary cylinder with a small diameter cross section is attached to the side of the ram cylinder, and high-speed movement is possible due to the action of the auxiliary cylinder. Furthermore,
In the pressure increasing cylinder type, a pressure increasing cylinder mechanism is attached to the rear end of the ram, and the ram is pushed out under pressure by the action of the pressure increasing cylinder.

In any case, the conventional mold clamping device is provided with a ram cylinder that generates mold clamping force during injection and a separate auxiliary drive means for moving the mold. With this configuration, the mold clamping operation is performed in the order of low speed start, high speed advance, low speed low pressure mold clamping, and pressure increase, and mold opening is performed in the order of low speed high pressure mold opening, high speed retraction, low speed retraction, and product extrusion. It has become.

[0006]

However, in the conventional mold clamping device described above, it is necessary to incorporate an auxiliary drive mechanism inside, on the side, or at the rear end of the mold clamping ram, and when it is installed inside the ram, the structure is This is very complicated, and even when it is attached to the side or rear end, there are drawbacks such as an increase in the size of the equipment. Furthermore, high-speed mold opening and closing is difficult to control, requiring complicated position control and pressure control.

An object of the present invention is to be able to perform mold closing and mold opening operations at high speed with an extremely simple mechanism without separately providing a mold clamping cylinder and an auxiliary drive mechanism, and at the same time with a simple operation circuit. To provide a mold clamping device capable of performing mold closing and mold opening operations at high speed.

[0008]

[Means for Solving the Problems] In order to achieve the above object, a mold clamping device according to the present invention includes an even number of tie rods installed around a fixed die plate symmetrically with respect to the mold clamping center, and guided by the tie rods. In a mold clamping device in which a movable die plate is directly driven by a mold clamping cylinder mechanism to perform mold clamping, a mold clamping cylinder is integrally provided in a tie rod penetrating portion of the movable die plate, and the tie rod is provided with the mold clamping cylinder mechanism. A mold clamping cylinder mechanism is formed by providing a piston part that slides in contact with the cylinder, and a pressure receiving area difference is given to the hydraulic pressure chamber partitioned by the piston part of the tie rod, and a pair of piston parts formed on diagonally located tie rod parts are provided. The mold clamping cylinder mechanism is constructed by combining a pair with a larger pressure receiving area on the movable die plate side and a pair with a larger pressure receiving area on the opposite side.

[0009]

[Operation] According to the above structure, the mold clamping cylinder mechanism that drives the movable die plate is formed in the cylinder of the movable die plate and the piston portion provided on the tie rod, so that by supplying and discharging working fluid to the cylinder, the mold clamping cylinder mechanism drives the movable die plate. The cylinder moves, and the movable die plate, which is integrated with the cylinder, is driven toward or away from the fixed die plate. Since four tie rods are normally provided, they can be provided at the four corners around the die plate, and mold clamping pressure can be increased by simultaneous driving of four cylinders. Therefore, the increased pressure for mold clamping can be adequately dealt with by ensuring the total pressure receiving area of each cylinder. In addition, since the pressure-receiving area of each cylinder can be reduced, movement for mold closing and mold opening can be performed using some of the multiple cylinders, which allows a small-capacity pump to move the mold. High-speed movement of the mold is realized. At this time, a pressure receiving area difference was given to the piston part of the tie rod before and after in the sliding direction, and a pair of tie rods located diagonally were used as a pair, and one pair had a larger pressure receiving area on the movable die plate side, and the other had a larger pressure receiving area on the opposite side. By configuring a combination of pairs, high-speed movement in the mold-closing direction and high-speed movement in the mold-opening direction can be shared, and higher speeds can be realized.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments in which a mold clamping device according to the present invention is applied to an injection molding machine will be described in detail below with reference to the drawings.

FIGS. 1 and 2 show a mold clamping device for an injection molding machine according to an embodiment. This mold clamping device joins the molds together and performs mold clamping by moving a movable die plate 12 to which the other mold is attached to a fixed die plate 10 to which one of the molds is attached. . Therefore, in the mold clamping device, a fixed die plate 10 is fixedly installed on a machine base 14, and a movable die plate 12 is attached so as to be slidable via a rail 16 of the machine base 14. Further, a rear plate 18 is erected and fixed on the machine base 14 so that the movable die plate 12 is located in the middle, and both die plates 10, 1
The movable die plate 12 is installed so that it can reciprocate between the fixed die plate 10 and the rear plate 18 at both ends, so that the die plate 2 and the rear plate 18 are parallel to each other.

Each of the mold clamping components has a rectangular planar shape, and tie rods 20 are located at their four corners, particularly at equidistant positions on the circumference from the mold clamping center.
is penetrated. This tie rod 20 is arranged point-symmetrically with respect to the mold clamping center, and both ends of the tie rod 20 are fixedly connected to the fixed die plate 10 and the rear plate 18 to provide support during mold clamping. There is. Furthermore, the tie rod 20 is slidable on the intermediate movable die plate 12, and has a guide function when the die plate is moved to close or open the mold.

In the above configuration, the movable die plate 12
A mold clamping cylinder mechanism 22 is provided to drive the mold clamping, and this is formed at four locations of the tie rod penetrating portion of the movable die plate 12. That is, each tie rod 20 is provided on the back side of the movable die plate 12.
Four cylinders 24 are integrally attached to the movable die plate 12 so as to contain the movable die plate 12.
It is designed to be moved along with the A piston portion 26 having a diameter larger than the rod diameter is formed in the tie rod 20 inside each cylinder 24.
6 is slidably attached to the cylinder 24, and the piston part 26
The piston portion 26 is configured to be moved within the cylinder 24 by supplying and discharging working fluid into the left and right hydraulic pressure chambers partitioned by. Therefore, when supplying and discharging working fluid to and from such a mold clamping cylinder mechanism 22, since both ends of the tie rod 20 are fixed, the cylinder 24 is relatively driven, and the cylinder 24 is relatively driven. The movable die plate 12 is moved along the axial direction of the tie rods 20 to perform a mold clamping operation.

By the way, in this embodiment, the mold clamping cylinder mechanisms 22 are provided at four locations so as to pass through the tie rods 20, so they are arranged on the circumference at equal distances from the mold clamping center. A pair of mold clamping cylinder mechanisms 22A, 22A and 22B, 22B located diagonally are arranged in pairs and used for driving when the mold is closed and for driving when the mold is opened. Therefore, in one pair cylinder mechanism 22A, 22A, the piston portion 26
The pressure receiving area of the hydraulic pressure chamber 28R on the movable die plate 12 side, which is partitioned by , is made larger than that of the other hydraulic pressure chamber 28L. This is achieved by making the diameter d1 of the tie rod 20 extending from the piston portion 26 toward the rear plate 18 larger than the diameter d on the die plates 10 and 12 side. Further, in the other paired cylinder mechanism, the pressure receiving area of the hydraulic pressure chamber 30R on the movable die plate 12 side is made smaller than that of the other hydraulic pressure chamber 30L. This means that the diameter d2 of the tie rod 20 extending from the piston portion 26 to the rear plate 18 side is
, by making the diameter d smaller than that of the 12 side. The paired cylinder mechanisms 22A, 22A and 22B, 22B, whose pressure receiving areas are adjusted in this way, are used for high-speed movement for mold closing and mold opening, respectively, and are set so that both pairs are driven together when mold clamping pressure is increased. ing.

A hydraulic circuit for driving the mold clamping cylinder mechanism 22 is shown schematically in FIG. As shown in the figure, a pump 32 for supplying working fluid to each mold clamping cylinder mechanism 22 is provided, and a supply pipe 3 is provided at the discharge port of this pump 32.
4 is connected, and a flow rate control valve 36 is interposed therebetween to supply working fluid while controlling the amount of oil. The supply pipe line 34 includes a pipe line 37 that communicates with each mold clamping cylinder mechanism 22.
This branch pipe line 37 is connected to the hydraulic pressure chambers 28R, 28L, 30R, and 30L of each mold clamping cylinder mechanism 22 via a check valve 38 and a switching solenoid valve 40 in the middle. The switching solenoid valve 40 is a 4-port 3-position switching valve, and the pump 32 is connected to the left and right hydraulic pressure chambers 28R, 28L (30
Movable pressurized supply port position (R, 30L) connected simultaneously to
a Solenoid activation), both hydraulic chambers 28R, 28L (30R
, 30L) to the tank 42, and the hydraulic chamber 28R (30L) on the side that pressurizes the movable die plate 12.
R) and the other hydraulic pressure chamber 28L (30L).
It can be switched to three positions, including a boost supply port position (b solenoid activation) that opens the air to the tank 42. In this case, at the movable pressurized supply port position, the working fluid is simultaneously supplied to the hydraulic pressure chambers on both sides of the piston, forming a runaround circuit driven by the difference in pressure receiving area.

Note that in FIG. 3, 44 is a relief valve.

The operation of the mold clamping device constructed as described above is as follows. The mold clamping device basically performs the mold closing process of moving the movable die plate 12 from the standby position to the mold clamping position at high speed relative to the fixed die plate 10, the process of increasing the pressure for mold clamping, and the process of demolding the product after injection is completed. In order to do this, a mold opening process is required in which the movable die plate 12 is moved at high speed to a standby position.

First, in the mold closing process, one set of cylinder mechanisms 22A and 22A, which have a large pressure receiving area in the hydraulic chamber on the movable die plate 12 side, is used among the four mold clamping cylinder mechanisms 22. That is, the working fluid supply path to the pair of cylinder mechanisms 22A, 22A located diagonally is opened. This is done by activating the a solenoid of the switching solenoid valve 40 that communicates with the cylinder mechanism 22A, and the working fluid is simultaneously supplied to both hydraulic chambers 28R and 28L. A difference in pressure receiving area is provided between the hydraulic pressure chambers 28R and 28L, and as shown in FIG. 4(1), the cylinder 2
When the inner diameter of No. 4 is D, the mold closing speed is given by the following equation.

VC=Q/π/4・(d12−d2)・2

[0020] Therefore, the mold closing speed can be determined according to the magnitude of the pressure receiving area difference, and the mold can be operated at high speed and with low force.

Mold clamping is performed after mold closing is completed, and this is achieved by simultaneously driving the four cylinder mechanisms 22A, 22A, 22B, and 22B, and activating the b solenoid of the switching solenoid valve 40 that communicates with each cylinder 24. It is done by doing. As a result, the working fluid is introduced only into the hydraulic pressure chambers 28R, 30R on the movable die plate 12 side, and the other hydraulic pressure chambers 28L, 30L are opened. As a result, Figure 4 (
As shown in 2), a high pressing force is generated in the mold clamping cylinder mechanism, and a mold clamping force is generated between both die plates 10 and 12. The mold clamping force F at this time is expressed by the following formula.

F=π/4・(D2−d2)・4・p

0
[023] In addition, the mold opening for taking out the product is performed using the cylinder mechanisms 22B and 22B, which have a smaller pressure receiving area of the hydraulic chamber on the movable die plate 12 side, among the four mold clamping cylinder mechanisms 22.
One set is used. That is, the working fluid supply path to the pair of diagonally located cylinder mechanisms 22B, 22B is opened. This is done by activating the a solenoid of the switching solenoid valve 40 that communicates with the cylinder mechanism 22B, so that the working fluid is simultaneously supplied to both hydraulic chambers 30.
R, 30L. A difference in pressure receiving area is given between the hydraulic pressure chambers 30R and 30L, and as shown in FIG. 4(3), when the inner diameter of the cylinder 24 is D, the mold closing speed is given by the following equation.

VO=Q/π/4・(d2−d22)・2

[0025] Therefore, the mold opening speed can be determined depending on the magnitude of the pressure receiving area difference, and the mold opening speed can be operated at high speed and with low force.

As described above, according to this embodiment, both the mold closing and mold opening operations can be performed by a simple operating circuit using hydraulic pressure, so that the movable die plate 12 for mold closing and mold opening can be moved at high speed. can be done. Further, there is no need to provide an auxiliary cylinder or other actuator separately from the mold clamping cylinder for high-speed movement of the die plate. Therefore, space can be used effectively, and the device configuration can be simplified and simplified. Furthermore, the speed of the movable die plate and the mold opening/closing force can be arbitrarily changed by simply changing the tie rod diameter on the rear plate 18 side, resulting in a highly versatile structure.

[0027]

Effects of the Invention As explained above, according to the mold clamping device of the present invention, mold closing and mold opening operations can be performed at high speed by an extremely simple mechanism without separately providing a mold clamping cylinder and an auxiliary drive mechanism. At the same time, an excellent effect can be obtained in that the mold closing and mold opening operations can be performed at high speed with a simple operation circuit.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a mold clamping device according to an embodiment.

FIG. 2 is a cross-sectional view of the device.

FIG. 3 is a hydraulic circuit diagram of the device.

FIG. 4 is an explanatory diagram of a mold clamping method.

[Explanation of symbols]

10 Fixed die plate 12 Moving die plate 18 Rear plate 20 Tie rod

Claims (1)

[Claims] Claim 1: A mold clamping method in which an even number of tie rods are installed around a fixed die plate symmetrically with respect to the mold clamping center, and a movable die plate guided by the tie rods is directly driven by a mold clamping cylinder mechanism to perform mold clamping. In the apparatus, a mold clamping cylinder is integrally provided in a tie rod penetrating portion of the movable die plate, and a piston part that slides in contact with the mold clamp cylinder is provided on the tie rod to form a mold clamping cylinder mechanism, and the tie rod A pair of mold clamping cylinder mechanisms formed on diagonally located tie rods is used to provide a pressure receiving area difference to the hydraulic pressure chamber divided by the piston part, and the pressure receiving area on the movable die plate side is increased. A mold clamping device characterized in that it is constructed by a combination of pairs with larger opposite sides.