JPH08216213A - Die clamping device of injection molding machine - Google Patents

Abstract

PURPOSE: To obtain a high parting power with interfering with a finished product delivery operation by arranging large dia. short-stroke hydraulic cylinders for pressure boosting in series on the front end of a die closing cylinder, and connecting the rod of a large dia. piston to an additionally installed piston on the die closing cylinder. CONSTITUTION: A small dia. long-stroke hydraulic cylinder 302 and a large dia. short-stroke hydraulic cylinder 303 are arranged on a die closing cylinder 301 so that these cylinders are connected serially in an axial direction, and a second piston 306 is engaged with a head side. The hydraulic cylinder 303 is a pressure-boosting cylinder for parting a die, and the rear end of a rod 308 which connects with a piston 307 is connected to the front end of the second piston of the small dia. cylinder 302. If a hydraulic oil is supplied to the oil chamber 303B of the pressure-boosting cylinder 303, the piston 307 generates a required high power for parting the die, and thereby boosts the oil pressure of the oil chamber 302 blocked from the piston 306 to push the piston. Thus a movable die 156 is separated from a fixed die 152 through a rod 305.

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 of an injection molding machine for opening and closing a mold and clamping the mold.

[0002]

2. Description of the Related Art Conventionally, a mold clamping device of an injection molding machine has a structure as shown in FIG. 4 which is a side view of FIG. 3 and an enlarged view of an IV portion thereof. That is, in the figure,
Reference numeral 150 denotes a base on which the mold clamping device is mounted and fixed, and a fixed mold plate 154 to which a fixed mold 152 is attached is fixed to the front end of the base 150. 158 is a movable die platen, and a movable die 156 is attached to the movable die platen 158,
A slide shoe 159 is integrally attached to the leg portion, and a guide rail 151 provided on the base 150.
It is mounted so that it can move forward and backward along. Fixed mold board 15
Hydraulic cylinders in the front-rear direction (hereinafter referred to as mold clamping cylinders) that generate the mold clamping force after the mold is closed at the four corners of the upper, lower, left and right sides of 4.
160 are respectively formed in the mold clamping cylinder 160, and the rear oil chamber 16 is provided in front of and behind the ram 162, as will be described later.
1A and a front oil chamber 161B are formed. Ram 162
As shown in an enlarged view in FIG. 4, the outer circumference is formed in three stages of large, medium and small diameters, and the insertion hole 17 for the tie bar 164 is formed in the axial center.
4 is formed so as to penetrate the rear oil chamber 1 when the mold clamping pressure is increased.
By sending pressure oil to 61A, it moves to the front of the drawing, its tip portion 163 is brought into contact with the half nut 180, and the half nut 180 meshes with the tie bar 164 in a manner to be described later. Generate the mold clamping force. Here, the tie bar 164 is the nut 16
5, the rear end is fixed to the movable die plate 158, and a threaded portion 172 is formed on the front end over a predetermined length. The threaded portion 172 is a half nut 180 provided on the front side of the fixed die plate 154 during mold clamping. It is supposed to mesh with. 16
Reference numeral 6 denotes a die opening / closing cylinder attached to the fixed die plate 154, which moves the movable die plate 158 forward and backward. Therefore, the rear end of the rod 170 of the mold opening / closing cylinder 166 is fixed to the movable mold board 158. 175 and 176 are fixed mold plates 1
54 is a rear packing presser and a front packing presser that are fixed to the front and rear of the portion of the mold clamping cylinder that constitutes the mold clamping cylinder. A guide bar 177 in the front-rear direction is fixed to the front packing presser 176 on the front side of the fixed mold board 154. A half nut 180, which is a pair of left and right divided nuts and is opposed to the guide bar 177, is slidably supported via a bracket 178.
It is always urged by 79 so as to be pressed against the front end 163 of the ram 162, and the half nut 180 can be opened and closed right and left by an opening and closing mechanism (not shown) along the guide bar 181 fixed to the bracket 178. When the mold is clamped, it is closed and screwed with the threaded portion 172 of the tie bar 164. Further, a sprocket 190 having an internal thread cut on the inner surface is screwed onto a screw rod 191 protruding forward from the front packing holder 176. The sprocket 190 is driven by a chain drive device such as a stepping motor (not shown). As shown by the arrow in FIG. 4, it is possible to move forward and backward through the chain 195. In the mold clamping device having such a structure, in the rear oil chamber 1 of the mold opening / closing cylinder 166.
When the pressure oil is sent to 68A, the movable die plate 158 is guided by the guide rail 151 and moves toward the fixed die plate 154,
The tip of the tie bar 164 passes through the tie bar insertion hole 174 of the fixed mold board 154 and passes through the fixed mold 152 and the movable mold 156.
Will stop at the point of contact. Where sprocket 1
90 is previously driven by the chain 195 to be positioned as described later, and hydraulic pressure is applied to the front oil chamber 161B of the hydraulic cylinder 160 until the end surface 190a of the sprocket 190 and the end surface 163a of the ram 162 come into contact with each other. The ram 162 is moved rearward in the figure and stopped. At this time, the half nut 180 is also pushed by the spring 179 and moves by an amount corresponding to the movement of the ram 162, and the tip 163 of the ram is moved.
And the rear end of the half nut is pressed and stopped. The stop position of this half nut is determined in advance by the control device so that the phase of the screw portion 172 of the tie bar 164 and the screw phase substantially match when the tie bar 164 penetrates the stationary die plate 154 and is stopped. Keep it. When the mold closing is completed, the half nut 180 is closed by a half nut opening / closing device (not shown), and then hydraulic pressure is applied to the front oil chamber 161A side of the mold clamping cylinder 160. Since the screw portion 172 of the tie bar 164 and the screw of the half nut 180 are already screwed together at this time, the front end 163 of the ram.
Is pushed in front of the half nut 180, and thereby the tie bar 164 is pulled to generate a mold clamping force. In this state, the resin is injected and molded. When the molding is completed and the mold is opened, the hydraulic pressure in the front oil chamber 161A of the mold clamping cylinder 160 is first lowered, and then the half nut 180 is opened by a half nut opening / closing device (not shown) to be screwed with the tie bar 164. When the mold is released and then pressure oil is sent to the rear oil chamber 168B of the mold opening / closing cylinder 166, the movable mold plate 158 moves rearward to open the mold.

[0003]

However, as described above, in this mold clamping device, the ram type mold clamping cylinder 16 having a large diameter and a short stroke is used only for the mold clamping which requires a large force.
The mold opening / closing cylinder 166 having a small diameter and a long stroke is used to close both the molds 152 and 156 and to open them apart after molding. Therefore, if the mold is complicated and the contact area is large, or if the adhesive force of the resin is large and the force required for the mold release is large, the mold opening / closing cylinder 166 having a small diameter has insufficient power and the mold release becomes difficult. There is. Further, if the diameter of the mold opening / closing cylinder 166 is increased in order to increase the mold release force with the same pump discharge amount, the mold opening / closing speed becomes slower, so there is a limit to the enlargement of the cylinder diameter. That is, if an attempt is made to maintain an appropriate mold opening / closing speed, the releasing force will be restricted. Therefore, in order to solve these problems, the structures shown in FIGS. 5 to 8 are conventionally known. That is, the structure of this mold clamping device is substantially the same as the structure shown in FIGS. 3 to 4, but the structure of the mold opening and closing cylinder is slightly different as shown in FIG. That is,
In FIG. 5, the mold opening / closing cylinder 201 has a large-diameter hydraulic cylinder 202 and a small-diameter hydraulic cylinder 203 arranged axially in series so that the same piston rod 204 can be operated simultaneously. The operation of the mold clamping device including the mold opening / closing cylinder 201 will be described. In the case of foam molding in which the mold clamping force may be relatively small at the time of molding, the mold opening / closing cylinder 201 is configured as shown in FIG. By simultaneously driving the large-diameter hydraulic cylinder 202 and the small-diameter hydraulic cylinder 203 which are operated by an appropriate hydraulic circuit, it is possible to obtain a mold clamping force necessary and sufficient for foam molding. Moreover, FIG.
As shown in FIG. 5, a sufficient releasing force can be obtained by simultaneously using the large diameter hydraulic cylinder 202 and the small diameter hydraulic cylinder 203 by an appropriate hydraulic circuit even at the time of releasing the mold. As a result, when the mold clamping force is relatively small, it is not necessary to use the ram type hydraulic cylinder 160,
The injection molding cycle time can be significantly reduced. When a large mold clamping force is required, as shown in FIG. 7, a ram type mold clamping cylinder 160 is used as shown in FIG. 3 to FIG. Mold opening / closing cylinder 2
Since the large-diameter hydraulic cylinder 202 and the small-diameter hydraulic cylinder 203 constituting 01 are used at the same time, it is possible to obtain a sufficient releasing force necessary for releasing. However,
With this structure, the mold opening and closing cylinder becomes long,
There is another problem that it interferes with the product removal work when the mold is opened, or it protrudes to the rear of the fixed mold board to increase the installation area of the device.

The present invention has been proposed in view of the above circumstances. When the mold is clamped, the conventional large mold clamping force is exerted, and when the mold is opened, it does not interfere with the product take-out work, and the entire apparatus is provided. Without increasing the installation area of
Moreover, it is an object of the present invention to provide an economical mold clamping device for an injection molding machine, which can exert a large releasing force.

[0005]

To this end, the present invention is directed to a front fixed mold plate for holding a fixed mold, a rear movable mold plate for holding a movable mold, and before and after reciprocating the rear movable mold plate. Direction opening / closing cylinder, a tie bar in the front-rear direction that is attached to the rear moving mold plate and is locked to the front fixed mold plate after mold closing, and means for locking the tie bar to the front fixed mold plate. A mold clamping device configured to apply a tension to the tie bar to perform mold clamping, wherein a large-diameter short-stroke hydraulic cylinder for increasing pressure is arranged in series in the axial direction at the front end of the mold opening / closing cylinder. And integrally formed, and the rear end of the rod of the large-diameter piston of the large-diameter short-stroke hydraulic cylinder for increasing pressure is connected to the piston added to the front part in the mold opening / closing cylinder via the piston rod. Is characterized by.

[0006]

According to such a structure, the operations of the mold clamping apparatus including the mold opening / closing cylinder with the pressure boosting cylinder described above, from the mold closing to the mold clamping to the injection molding, are the same as those of the structures shown in FIGS. It is the same. By the way, when opening the mold after injection molding, first, a large mold release force is generated by the pressure boosting cylinder, and this force is transferred from the piston connected to the tip of the rod of the pressure boosting cylinder through blocked pressure oil to the mold opening / closing cylinder. Tell the piston and talk about the mold. Since a large force is not required once the mold is separated, the stroke of the pressure boosting cylinder required for mold release is small, and thereafter, the mold opening / closing cylinder alone is used to perform mold opening as in the conventional case.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a horizontal sectional view showing a mold closing state of the mold clamping device and corresponds to FIG. 6 of a conventional example. Since the structure of the mold clamping device of the embodiment of the present invention is almost the same as the structure of the two conventional devices shown in FIGS. 3 to 4 and 5 to 8, the same parts are designated by the same reference numerals and the description thereof will be omitted. Only the two mold opening / closing cylinders different from the conventional structure will be described. FIG. 2 is an explanatory view showing an operating procedure of the mold clamping device of FIG.

First, in FIG. 1, 301 is a mold opening / closing cylinder according to the present invention, and the cylinder body is a fixed mold plate 15.
4, the piston end is connected to the movable die plate 158, and the small diameter long stroke hydraulic cylinder 302 and the large diameter short stroke hydraulic cylinder 303 having different diameters are arranged and connected in series in the axial direction. There is. A small-diameter long-stroke hydraulic cylinder 302 (hereinafter referred to as a small-diameter cylinder) is a hydraulic cylinder corresponding to the mold opening / closing cylinder 166 of Conventional Example 1, and as shown in FIG. Is connected to the movable mold board 158. A second piston 306 is fitted on the head side of the cylinder, and a rear oil chamber 302A between the rod cover and the piston 304 and a central oil chamber between the piston 304 and the piston 306 are installed inside the cylinder. 302B and a front oil chamber 302C between the piston 306 and the head cover
It is divided into three chambers, and there are three ports leading to each oil chamber. A large diameter end stroke hydraulic cylinder 303 (hereinafter referred to as a pressure boosting cylinder) is a pressure boosting cylinder for mold release, and a rod 308 that is coupled to the piston 307.
The rear end of the hydraulic cylinder 30 is connected to the front end of the second piston 306 of the small diameter cylinder 302, and has a large diameter end stroke.
No. 3 rod side oil chamber 303A and head side oil chamber 303B
And, it has a port leading to each. Reference numeral 309 (FIG. 1) is a hydraulic device that supplies pressure oil to the cylinder 301.

Next, the operation of the mold clamping device having such a structure will be described with reference to the operation explanatory diagrams of FIGS. 2 (A) to 2 (E).
First, as shown in FIG. 2A, the piston 307 of the pressure boosting cylinder 303 is placed at the front end position of its stroke,
When the ports of the oil chamber 303A and the oil chamber 303B are closed,
The piston 306 is fixed and becomes similar to the case of FIG. 5 without the pressure boosting cylinder 303. Therefore, as in the conventional example until the injection molding operation, as shown in FIG. 2 (B), pressure oil is supplied to the oil chamber 302A of the small diameter cylinder 302 to close the mold, close the half nut 180, and close the ram. Hydraulic cylinder 1
The mold is clamped by 60, resin molding is performed, and after cooling, the hydraulic cylinder 160 is loosened and the half nut 180 is opened.
Next, when a particularly large releasing force is not required, pressure oil is supplied to the oil chamber 302B of the small diameter cylinder 302 to open the mold (not shown) as in the conventional example. When a large releasing force is required, as shown in FIG.
With B blocked and other oil chambers open, pressure oil is supplied to the oil chamber 303B of the pressure boosting cylinder 303. Then, the piston 307 generates a large force necessary for mold release, pressurizes the piston 304 by increasing the hydraulic pressure of the oil chamber 302B blocked from the piston 306, and moves the movable mold 156 via the rod 305 to the fixed mold 152. Away from, piston 307 travels the entire stroke and stops. here,
As shown in FIG. 2D, pressure oil is supplied to the oil chamber 302B to open the mold. When the mold is closed next time, as shown in FIG. 2 (E), the pressure oil is supplied to the oil chamber 303A to cause the piston 306 to move.
Return to the position on the head side.

[0009]

According to such a mold clamping device, a large-diameter short-stroke booster cylinder for releasing the mold is arranged in series at the rear part of the mold opening / closing cylinder, so that a sufficient pressing force necessary for the releasing system is provided. On the other hand, the length in the axial direction is short, and the hydraulic cylinder does not project to the work area (daylight part) when the mold is opened or the outside of the device. Does not interfere with work or increase the installation area.

In short, according to the present invention, the front fixed mold plate holding the fixed mold, the rear movable mold plate holding the movable mold, and the mold opening / closing cylinder in the front-rear direction for reciprocating the rear movable mold plate. A tie bar in the front-rear direction that is attached to the rear movable mold plate and is locked to the front fixed mold plate after closing the mold; a means for locking the tie bar to the front fixed mold plate; and a tension on the tie bar. And a mold clamping unit configured to perform mold clamping by applying a hydraulic pressure increasing cylinder having a large diameter and a short stroke to the front end of the mold opening / closing cylinder so as to be arranged in series in the axial direction and connected integrally. And the rear end of the rod of the large-diameter piston of the large-diameter short-stroke hydraulic cylinder for increasing pressure is connected to the piston added to the front part in the mold opening / closing cylinder through the piston rod, , Big as before Economical mold clamping device for injection molding machine that generates clamping force, does not interfere with product removal work when the mold is opened, and can exhibit a large mold releasing force without increasing the installation area of the entire device. Therefore, the present invention is extremely useful industrially.

[Brief description of drawings]

FIG. 1 is an overall horizontal sectional view showing a mold clamping device according to an embodiment of the present invention.

2 is an operation explanatory view showing an operating procedure of the mold clamping device of FIG. 1. FIG.

FIG. 3 is a partial cross-sectional side view showing an example of a conventional mold clamping device.

FIG. 4 is an enlarged sectional view of an essential part showing an IV part in FIG.

5 is a vertical cross-sectional view showing a modification of FIGS. 3 to 4. FIG.

6 is an operation explanatory view showing a first mold clamping operation state of the mold clamping device of FIG. 5. FIG.

7 is an operation explanatory view showing a second mold clamping operation state of the mold clamping device of FIG. 5. FIG.

FIG. 8 is an operation explanatory view showing a mold releasing operation state of the mold clamping device in FIG. 5;

[Explanation of symbols]

 152 Fixed mold 154 Fixed mold plate 156 Moving mold 158 Moving mold plate 160 Clamping cylinder 163 Front end of ram 164 Tie bar 166 Conventional mold opening / closing cylinder 180 Half nut 301 Mold opening / closing cylinder 302 Small diameter long stroke hydraulic cylinder 302A Rear oil chamber 302B Central oil chamber 302C Front oil chamber 303 Hydraulic cylinder for increasing pressure 303A Rod-side oil chamber 303B Head-side oil chamber 306 Expanded piston 307 Expanded large-diameter piston 308 Pressure-increasing cylinder rod 309 Hydraulic system

Claims (1)

[Claims] 1. A front fixed mold plate holding a fixed mold, a rear movable mold plate holding a movable mold, a front-back mold opening / closing cylinder for reciprocating the rear movable mold plate, and the rear movement. A front and rear tie bar attached to the mold plate and locked to the front fixed mold plate after the mold is closed, a means for locking the tie bar to the front fixed mold plate, and a mold clamping by applying tension to the tie bar. In the mold clamping device, the hydraulic cylinder for increasing pressure having a large diameter and a short stroke is axially arranged in series at the front end of the mold opening / closing cylinder to be integrally formed. The mold clamping of the injection molding machine, characterized in that the rear end of the rod of the large-diameter piston of the large-diameter short-stroke hydraulic cylinder for pressure is connected to the piston added to the front part inside the mold opening / closing cylinder via the piston rod. apparatus.