JPH08164548A - Mold clamping device - Google Patents

Abstract

PURPOSE: To prevent the leakage of oil from a mold clamping cylinder by constituting a mold clamping device of the die plate on an injection side holding a mold on an injection side between a fixed plate and a movable die plate and the clamping cylinder allowing the die plate to slightly advance and retreat with respect to the fixed plate. CONSTITUTION: In such a state that the mold of a mold clamping device is opened, a movable die plate 10 is present at a two-dot broken line position and a die plate 6 on an injection side is present at a solid line position. When the plate 10 is pulled by a mold opening and closing cylinder 14, the plate 10 is moved toward the plate 6 while guided by a guide rail 5 and the leading end of a tie bar 3 passes through the through-hole 10a of the plate 10 to protrude to the rear side of the plate 10 and a movable mold 13 comes into contact with a fixed mold 9 and becomes a mold clamping state to stop. Herein, a half nut 12 is closed to be connected to the tie bar 3 to restrict the movement of the plate 10. The nut 12 and the tie bar 3 are adjusted in screw phase so as to be engaged by a meshing adjusting mechanism. Next, pressure oil is sent to the oil chamber 15a of a hydraulic cylinder 15 to press the plate 6 to the plate 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device for an injection molding machine.

[0002]

2. Description of the Related Art A conventional mold clamping device will be described with reference to FIGS. 3 to 7. In FIG. 3, reference numeral 150 denotes a base on which the mold clamping device is mounted and fixed.
The fixed die plate 154 for mounting 52 is fixed. Reference numeral 158 denotes a movable die plate, a movable die 156 is attached to the fixed die plate 154 side, and a slide shoe 159 is integrally attached to a leg portion of the movable die 154, and a guide rail 151 provided on the base 150. It is mounted so that it can move forward and backward. The guide portion of the movable die plate 158 may be a sliding slide, a rolling guide, or may be floated by air or magnetic force.

Hydraulic cylinders 160 are formed at four corners of the fixed die plate 154 to generate a mold clamping force after the mold is closed. The hydraulic cylinder 160 has oil chambers 161A and 161B inside with a ram 162 sandwiched therebetween, as will be described later. Have As shown in an enlarged view in FIG. 4, the ram 162 has a multi-stepped outer circumference with large, medium, and small diameters, and the insertion hole 1 of the tie bar 164 is formed at the axial center.
74 is formed penetratingly, and when the mold clamping pressure is increased, pressure oil is sent to the one oil chamber 161A to move to the right in FIG. 4, and the tip end portion 163 thereof is brought into contact with the half nut 180, and With the half nut 180 engaged with the tie bar 164, the half nut 180 is further pushed rightward to generate a mold clamping force. A stopper pin 193 is fixed to the half nut 180 side of the ram 162.
Reference numeral 3 penetrates through the shaft center portion 191 of the sprocket 190, and a double nut 192 is attached to the tip thereof so that the dimension L between the stopper pin 193 attachment surface of the ram 162 and the double nut 192 can be finely adjusted. That is, by setting the dimension L, the moving width (cylinder stroke) of the ram is determined.

One end of the tie bar 164 is fixed to the movable die plate 158 by a nut 165, and a threaded portion 172 is formed at a tip of the tie bar 164 over a predetermined length. The threaded portion 172 is a fixed die plate during mold clamping. It meshes with a half nut 180 provided on the back side of 154.
Reference numeral 166 denotes a die opening / closing cylinder attached to the fixed die plate 154 or the moving die plate 158, which moves the moving die plate 158 forward and backward. Therefore, the tip of the rod 170 of the mold opening / closing cylinder 166 is attached to the moving die plate 1
58 or fixed die plate 154.

175 and 176 are fixed die plates 154.
A packing presser fixed to the front and rear of the portion forming the mold clamping cylinder, and a guide bar 177 for supporting the half nut 180 so that it can move forward and backward is fixed to the packing presser 176 on the back side of the fixed die plate 154. At the same time, a screw hole 182 is provided near the inner peripheral portion thereof. On the guide bar 177 fixed to the packing retainer 176, as shown in FIG. 5, a half nut 180, which is a nut divided into two and is opposed, is slidably supported via a bracket 178, and the half nut 180 is a spring. It is always urged by 179 so as to be pressed against the tip portion 163 of the ram 162. The half nut 180 can be opened and closed to the left and right by an opening and closing mechanism (not shown) along a guide bar 181 fixed to the bracket 178, and is closed during mold clamping to mesh with the threaded portion 172 of the tie bar 164.
Reference numeral 190 denotes a sprocket having a thread cut on the outer peripheral portion of the boss, and the sprocket 190 is screwed into the screw hole 182 provided near the inner circumference of the packing retainer 176. The sprocket 190 is moved back and forth in a direction indicated by an arrow in FIG. 4 via a chain 195 by a chain driving device such as a stepping motor (not shown).

Next, the operation of the mold clamping device having the above structure will be described. One oil chamber 168A of the mold opening / closing cylinder 166
When the pressure oil is sent to the fixed die plate 158, the movable die plate 158 is guided by the guide rail 151 and advances toward the fixed die plate 154 side, and the tip end of the diver 164 penetrates the tie bar insertion hole 174 of the fixed die plate 154, and the fixed die 152 and When the movable mold 156 is fitted, it stops as shown in FIG. FIG. 7 is a view on arrow C in FIG.

The sprocket 190, which is screwed to the packing holder 176, drives the chain 195 in advance to position it, and applies hydraulic pressure to the other oil chamber 161B of the hydraulic cylinder 160 to apply the hydraulic pressure to the end face of the sprocket 190 and the double nut as shown in FIG. The ram 162 is stopped moving to the left in the figure until 192 contacts the surface. Half nut 1 at this time
The spring 80 is also pushed by the spring 179 and moved by the amount of the movement of the ram 162, and is stopped in a state where the ram tip portion 163 and the half nut end surface are in pressure contact with each other. At the half nut stop position, the tie bar 164 is fixed to the fixed die plate 1 as described above.
The position is preliminarily indexed and determined by the control device so that the screw portion 172 of the tie bar 164 and the phase of the screw substantially coincide with each other at the time of stopping after penetrating 54. The hydraulic cylinder 160 is provided corresponding to each of the four tie bars 164. Threaded portion 172 of the four tie bars 164.
Does not always match all the phases, so the phase shift of the screw portion 172 at the end of mold closing is finely adjusted by the double nut 192 as necessary.

When the mold closing is completed, the half nut 1
80 is closed by a half nut opening / closing device (not shown),
Next, hydraulic pressure is applied to the oil chamber 161A side of the hydraulic cylinder 160. Tie bar 164 screw 172 and half nut 18
Since the 0 screw is already meshed at this time, the half nut 180 is pushed to the right by the ram tip portion 163, whereby the tie bar 164 is pulled and a mold clamping force is generated. When the mold is finished and the mold is opened, first the hydraulic cylinder 16
0, the oil pressure in the oil chamber 161A is reduced, and then the half nut 180 is opened by a half nut opening / closing device (not shown) to release the meshing with the tie bar 164, and then the pressure oil is supplied to the oil chamber 168B in the die opening / closing cylinder 166. If sent, the moving die plate 158 moves to the left and the mold opens.

[0009]

However, the conventional mold clamping device has the following problems. (1) When the packing on the front side of the mold clamping hydraulic cylinder 160 is worn, the hydraulic oil leaks from the front packing retainer 175 and flows out to the mold mounting surface, which stains the mold mounting surface and the mold.
For this reason, it is necessary to manually wipe off the leaked oil or provide a drain pipe for collecting and discarding the oil. (2) Since there are four mold clamping hydraulic cylinders, the oil piping becomes complicated, and it is necessary to pressurize evenly at four more positions. In addition, the mold clamping force is applied at a position away from the mold, so the fixed die plate The bending moment applied to is large and it is necessary to increase the rigidity of the fixed die plate. Therefore, the present invention provides an injection-side die plate for holding a fixed die between a fixed die plate and a moving die plate, and uses one large-diameter and small-stroke die clamping cylinder provided on the fixed die plate during die clamping. An object of the present invention is to solve the above-mentioned conventional problems by moving the injection side die plate so that the mold can be clamped.

[0010]

Therefore, the present invention is directed to a fixed plate fixed to a base, a tie bar fixed to the fixed plate, a movable die plate for holding a movable die, and the movable die. A mold opening / closing cylinder that moves the plate forward and backward with respect to the fixed plate, a means for engaging and disengaging the tie bar and the moving die plate, and an injection side die plate that holds the injection side mold between the fixed plate and the moving die plate. And a clamping cylinder for slightly moving the injection-side die plate forward and backward with respect to the fixed plate, which serves as means for solving the problem.

[0011]

As described above, according to the present invention, between the fixed die plate and the movable die plate, the movable die plate is slidably mounted near the fixed die plate on the same guide rail on which the movable die plate is mounted. At the same time, an injection side (moving) die plate that can move a small distance with respect to the fixed die plate is arranged, and a fixed mold is attached to this injection side die plate. Furthermore, a mold is attached to the fixed die plate. The diver is fixed to the fixed plate like a cantilever, and the movable die plate is provided with a tie bar insertion hole and a half nut. The fixed plate is integrally provided with one large-diameter, small-stroke hydraulic cylinder for mold clamping, and connects the tip of the piston rod to the injection-side die plate. In this case, the piston rod and the die plate on the injection side may be integrated. The hydraulic cylinder for mold clamping is composed of an annular cylinder formed on a fixed plate, an annular piston fitted in the cylinder, and a cylindrical piston rod connecting the piston and the injection side die plate. A passage hole through which the resin injection cylinder passes is formed in the central portion of the fixed plate, the hydraulic cylinder, and the injection side die plate.

In order to perform mold clamping, first, the injection side die plate is set at a predetermined position, the moving die plate is moved toward the injection side die plate at a relatively fast speed by the die opening / closing cylinder, and the two dies are pressed. Make contact (mold closing) and stop. Now close the half nuts and connect with the tie bars. The half nut and tie bar screws should be in phase with each other by an appropriate meshing adjustment mechanism. Next, pressure oil is sent to the mold clamping hydraulic cylinder to push the injection side die plate toward the moving die plate side. The die plate on the injection side moves by an amount of play existing in each part between the die plate and the half nut which is engaged with the tie bar and is fastened to strongly clamp both dies. Resin is injected and molded in this mold clamped state. After completion of molding, loosen the hydraulic cylinder for mold clamping and return it to the original position, open the half nut at the same time to release the engagement with the tie bar, and return the moving die plate to the original position with the mold opening / closing cylinder. The molding process is completed. There is no risk of oil leaking from the mold clamping hydraulic cylinder flowing out to the mold mounting surface of the injection side die plate to which the injection mold is attached, and there is only one mold clamping hydraulic cylinder. The piping is simple and the mounting surface can be machined. Further, since the mold clamping force is applied to an area substantially equal to the die mounting area of the injection side die plate, a bending moment that deforms the injection side die plate is not generated. Therefore, the injection-side die plate can be thinner than a normal fixed die plate. Even if the tie bar is fixed to the movable die plate and a means for engaging and disengaging the tie bar and the fixed plate is provided on the fixed plate side, the same effect as described above can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a main part of the mold clamping device in section, and FIG.
FIG. 3 is a sectional view taken along line DD in FIG. 1. In these figures (mainly FIG. 1), 30 is a resin injection cylinder of an injection machine that constitutes an injection molding machine together with this mold clamping device, 1 is a base, 2 is a fixed plate fixed to one end of the base 1, and 3 is a fixed plate. Four tie bars 5 supported in a cantilever shape having a threaded portion 3a at one end and the other end fixed to the four corners of the fixing plate 2 by nuts 4 are fixed on the base 1. The guide rails 6, 6 are located near the fixed plate 2, and support the weight by the rail 5 via the slide shoe 7 attached to the lower part, and are guided by the tie bar 3 via the bush 8 for a short distance. With respect to the injection side (moving) die plate, 9 is a fixed mold attached to the injection side die plate 6, and 10 is a position facing the fixed plate 2 with the injection side die plate 6 in between, and four corners. To A movable die plate which has an insertion hole 10a through which the bar 3 is inserted and which slides on the rail 5 through a slide shoe 11 to move back and forth. Reference numeral 12 denotes a half nut attached to the movable die plate 10 and its opening / closing mechanism. , 13 is a moving die attached to the moving die plate 10, 14 is the body part on the fixed plate 2, and the tip of the rod is the moving die plate 1.
It is a small-diameter long-stroke mold opening / closing cylinder attached to 0. The mold opening / closing cylinder 14 in FIG. 1 is shown in a position (FIG. 2) lifted by rotating 90 °.

The fixed die plate 2 is formed with a mold clamping cylinder 15 having a large diameter and a small stroke which requires mold clamping. The mold clamping cylinder 15 includes an annular cylinder 2a integrally formed on the fixed plate 2. The cylinder 2a includes an annular piston 16 fitted in the cylinder 2a, and a cylindrical piston rod 17 having one end fixed to the piston 16 and the other end having an end wall 17a.
b and 15c are formed. 18 and 19 are outer and inner packing retainers, and 20 and 21, respectively.
Are the outer packing and the inner packing, respectively, and the end wall 17a of the cylindrical piston rod 17 is the injection side die plate 6
The end wall 17a, the injection-side die plate 6, and the fixed plate 2 are provided with holes through which the screw cylinders 30 pass.

Next, the operation of the mold clamping device having the above configuration will be described. In the state where the mold is opened, the movable die plate 10 is at the position shown by the chain double-dashed line in FIG. 1, and the injection side die plate 6 is at the predetermined position shown by the solid line. When the movable die plate 10 is pulled by the mold opening / closing cylinder 14, the movable die plate 1
0 is guided by the guide rail 5 and is on the injection side die plate 6
, The tip of the tie bar 3 penetrates through the insertion hole 10a of the movable die plate 10 and protrudes to the back side, and the movable mold 13 abuts the fixed mold 9 and is in the mold closed state (state shown by the solid line in FIG. 1). ) And stop. Here, the half nut 12 is closed and coupled with the tie bar 3 to restrain the movement of the movable die plate 10. The phases of the screws of the half nut 12 and the tie bar 3 are adjusted so as to be engaged by a meshing adjustment mechanism (not shown). Next, pressure oil is sent to the oil chamber 15a of the hydraulic cylinder 15 to push the injection side die plate 6 toward the moving die plate 10. The injection-side die plate 6 moves by filling the play existing in each portion between the injection-side die plate 6 and the half nut, and strongly clamps the fixed mold 9 and the movable mold 13. In this mold clamped state, the resin is injected by the screw cylinder 30.

After the completion of molding, the oil chamber 1 of the hydraulic cylinder 15
5a is stepped down, pressure oil is sent to the oil chambers 15b and 15c to return the injection side die plate 6 to the original position, and the half nut 1
2 is opened and the die opening / closing cylinder 14 moves the die plate 10
Is returned to the original position, and one molding process is completed. The above-mentioned operation is usually performed automatically by various sensors and control devices (not shown). In this embodiment, the tie bar 3
Is fixed to the fixed plate 2, and the tie bar 3 and the moving plate 10 are engaged and disengaged by the half nut 12 provided on the moving plate 10. The tie bar 3 is fixed to the moving plate 10 and fixed to the tie bar 3. Disengagement of plate 2
It goes without saying that the half nut 12 provided on the fixed plate 2 may be used.

[0017]

As described above in detail, according to the present invention, the die plate on the injection side has no sliding hole for the piston rod of the mold clamping cylinder. Therefore, even if the packing of the piston rod fails. However, there is no risk of oil leaks contaminating the die mounting surface or the die. Further, it is possible to easily take measures against the leaked oil. Since there is only one mold clamping cylinder, oil piping is simple. Further, it is not necessary to evenly distribute the oil to the plurality of cylinders, and the molds can be easily aligned. The mold clamping force of the mold clamping cylinder is applied to the area of the injection side die plate that is almost equal to the area where the mold is attached, and no bending moment that deforms the injection side die plate is generated, so the injection side die plate can be made thinner. It is possible to obtain excellent effects such as reduction of

[Brief description of drawings]

FIG. 1 is a partially sectional front view showing an embodiment of a mold clamping device of the present invention.

FIG. 2 is a sectional view taken along the line DD in FIG.

FIG. 3 is a partial sectional front view showing a mold opening state of a conventional mold clamping device.

FIG. 4 is an enlarged view of part A of FIG.

5 is a view on arrow B of the half nut portion in FIG. 4. FIG.

FIG. 6 is a partially sectional front view showing a mold closing state of a conventional mold clamping device.

7 is a view on arrow C of the half nut portion in FIG.

[Explanation of symbols]

1 Base 2 Fixed Plate 2a Annular Cylinder 3 Tie Bar 6 Injection Side Die Plate 9 Fixed Die 10 Moving Die Plate 12 Half Nut (Means to Combine Tie Bar and Moving Die Plate) 13 Moving Die 14 Die Cylinder 15 Die Clamp Cylinder 16 piston 17 piston rod

Claims (2)

[Claims] 1. A fixed plate fixed to a base, a tie bar fixed to the fixed plate, a movable die plate for holding a movable die, and a movable die plate which moves back and forth with respect to the fixed plate. A mold opening / closing cylinder, means for engaging and disengaging the tie bar and the moving die plate, an injection side die plate for holding an injection side mold between the fixed plate and the moving die plate, and the injection side die plate for fixing the same. A mold clamping device comprising a clamping cylinder that is slightly moved back and forth with respect to a plate. 2. A fixed plate fixed to the base, a moving die plate for holding a moving die, a tie bar fixed to the moving die plate, and the moving die plate with respect to the fixed plate. A mold opening / closing cylinder for moving, means for engaging and disengaging the tie bar and the fixed die plate, an injection side die plate for holding an injection side die between the fixed plate and the moving die plate, and the injection side die plate A mold clamping device comprising a clamping cylinder that is slightly moved back and forth with respect to a fixed plate.