JPH0227965Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is for pressure molding, in which both fixed and movable molds are clamped under pressure in order to inject molten metal or plastic into a mold and perform pressure molding. This relates to a mold clamping device.

[Conventional technology]

As a type of injection molding equipment such as die casting machines and plastic injection molding machines, there is a mold opening/closing cylinder that opens and closes a movable mold relative to a fixed mold, and this mold opening/closing cylinder applies a large mold clamping force to both molds that are matched. There is a known type that is equipped with separate mold clamping cylinders for adding .

Figure 6 is a partially cutaway plan view of this type of die casting machine disclosed in Japanese Patent Publication No. 51-29865. A mold clamping cylinder 2 is integrally provided at the four corners of the fixed platen 1 fixed above, and the other end of the tie rod 3 as a piston rod is attached to a machine base so as to be able to move forward and backward with respect to the fixed platen 1. A support plate 4 supported by is fixed with nuts 5. Further, a movable platen 6 is slidably supported on the tie rod 3, and a fixed mold 7 and a movable mold 8 are fixed to the fixed platen 1 and the movable platen 6, respectively, facing each other. 9 is a movable platen 6
It is a half-shaped nut supported on the side, and 10
is a screw cut into the tie rod 3, and the nut 9 is inserted into the screw 10 by advancing and retracting it in the direction of the arrow in the figure.
An engagement mechanism (not shown) that engages and disengages the movable platen 6 is supported and attached to the movable platen 6 side, and by closing the nut 9, the movable platen 7 and tie rod 3 are integrated and engaged. By uncoupling the movable platen 6, the movable platen 6 is configured to be able to slide freely relative to the tie rod 3.
The tie rod 3 has a plurality of grooves 1 arranged in parallel in the axial direction.
1 is provided, and a separate half-shaped stop ring 12 is provided which selects and engages any one of these grooves 11. 13 is a mold opening/closing cylinder fixed to the mold clamping cylinder 2 side, and the working end of the piston rod 14 is fixed to the movable platen 6.

With this configuration, the pressure oil in the mold clamping cylinder 2 can be removed from the illustrated state, and the nut 5 can be removed.
When it is opened and oil is sent to the head end side of the mold opening/closing cylinder 13, the movable platen 6 moves and the mold 7,
8 is separated and the mold is opened. Therefore, mold 7,
After selecting one of the grooves 11 according to the dimensions of 8 and engaging the stop ring 12, tighten the nut 5.
When oil is supplied to the rod end side of the open/close cylinder 13 while the cylinder is open, the movable platen 6 moves toward the fixed platen 1 at high speed. The movable platen 6 is switched to low speed just before it comes into contact with the stop ring 12, and stops when it comes into contact with the stop ring 12, and at the same time, the nut 5 is closed to integrate the movable platen 6 and the tie rod 3. At this time, the molds 7 and 8 are lightly contacted and matched, so
When oil is sent to the rod end side of mold clamping cylinder 2,
The tie rod 3 serving as the piston rod moves, and the movable platen 6 integrated therewith moves, applying a strong mold clamping force to both molds 7 and 8.

In addition, in the above example, the groove 11 and the stop ring 12 are used as a so-called die height adjustment device that regulates the die alignment stop position according to the dimensions of the molds 7 and 8.
However, as a die height adjustment device,
In addition, the tie rod 14 is threaded and fitted with a split nut that can be opened and closed freely.

In addition, the mold clamping cylinder 2, which operates from the mold alignment position to the mold clamping force generation position, is generally equipped with a pressure switch that detects the hydraulic pressure on the rod end side of the cylinder and stops oil supply. It is configured to issue a signal to start injection after confirming completion.

[Problem that the invention attempts to solve]

However, in the conventional mold clamping device for pressure molding configured in this way, if the die height adjustment that should be made in accordance with the dimensions of the molds 7 and 8 is incorrectly set, the molds 7 and 8 may When the tie rod 3 as a piston of the mold clamping cylinder 2 reaches the stroke end in a state where the molds are not aligned and the mold is not clamped, the rod end side of the mold clamping cylinder 2 reaches a predetermined pressure and the pressure switch issues a signal. , injection was started.

Conventionally, the tie rod 3 is provided with a rod that passes through the head cover of the mold clamping cylinder 2 and protrudes out of the cylinder, and when the tie rod 3 overstrokes just before contacting the head cover, the protruding end of this rod operates a limit switch. The mold clamping cylinder was stopped.

However, when releasing the mold, a large amount of pressure oil must flow into the head end of the mold clamping cylinder 2, and the pressure at the rod end must be reduced, so the hydraulic circuit and control device for this must be complicated. It was hot.

[Means for solving problems]

In order to solve these problems, the present invention uses a cylindrical part with a cover, which is part of the fixed platen, as the cylinder, and a mold clamping system in which the piston is a tie rod with one end of the head slidably fitted into the cylindrical part. The head end side of the cylinder and the rod end side are connected by a differential circuit, and there is also a flow path that communicates the head end side and the rod end side of the head, and a spool located in this flow path that protrudes from the end surface of the head end side of the head. A check valve is provided, the protruding end of which contacts the inner surface of the cylinder cover and is pushed to communicate the flow path.

[Effect]

With this configuration, if the tie rod as the piston of the mold clamping cylinder reaches just before the stroke end due to incorrect die height adjustment, the spool of the check valve will come into contact with the inner surface of the cover. The pressure oil on the rod end side flows back through the flow path to the head end side and then returns to the tank via the differential circuit switching valve, so the pressure switch does not operate and the injection operation is not performed. Not possible.

〔Example〕

Figures 1 to 5 show an example in which the mold clamping device for pressure forming according to the present invention is implemented in a horizontal mold clamping and horizontal casting type die casting machine, and Figure 1 is a schematic cross-sectional view of the die casting machine in which this device is implemented. Figure 2 is a partially cutaway side view, Figure 3 is a cross-sectional view along AA of Figure 2,
FIG. 4 is a sectional view and hydraulic circuit diagram of the vicinity of the mold clamping cylinder, and FIG. 5 is an enlarged sectional view of the main part of FIG. 4. In these figures, a die casting machine 20 is equipped with a machine base 22 fixed on a foundation 21 on the floor, and on one end of this machine base 22,
A fixed platen 23 serving as a fixed platen is fixed. A fixed mold 24 is attached to the fixed platen 23, and an injection cylinder (not shown) for injecting molten metal into the cavity of the fixed mold 24 is fixed corresponding to an injection hole. Furthermore, bottomed cylindrical cylinders 23b are integrally formed at the four corners of the top, bottom, left and right of the fixed platen 23, and the openings thereof are closed by covers 23d having ports 23c for introducing pressure oil. Also, the cylinder 23b
A rod hole 23a is bored in the bottom plate.
Reference numeral 25 denotes a tie rod which constitutes the mold clamping cylinder 26 together with the cylinder 23b as a piston that moves forward and backward by pressure oil introduced into the cylinder 23b, and one end of which is slidably inserted into the cylinder 23b. The tie rods 25 extend horizontally in parallel with each other. A thread 25a is cut into the free end of each tie rod 25, and a nut 27 is screwed into each thread 25a. Reference numeral 28 denotes two sprockets fixed to each nut 27. A chain 29, which is driven by a motor (not shown), is stretched between these four sprockets 28, and the four nuts are driven by the motor. 27 is configured to rotate at any time and move back and forth on the screw 25a. 30
is a safety cover that covers the sprocket 28 and chain 29. Also, what is designated as a whole by the reference numeral 31 is a support plate serving as a connecting member that connects the free ends of the four tie rods 25, and includes four boss portions 31a and a plate that rotatably support the nut 27. It is integrally formed with a connecting plate 31b having a shape of 2
The lower boss portion 31a is slidably supported by the machine base 22. Further, 31 is a sleeve slidably fitted to the tie rod 25, and one end of the sleeve is connected to the boss portion 31a of the support plate 31.
The movable platen 3 serving as a movable platen is inserted at the other end and is restricted from moving in the axial direction by a cover body 33.
4 is slidably supported. Then, by putting the attaching/detaching device 36 (to be described later) into the attached state and rotating the nut 27, the movable platen 34 and the sleeve 3 are attached.
2 are configured to move forward and backward on the tie rod 25 in unison. The movable platen 34 includes
A movable mold 35 that moves forward and backward with respect to the fixed mold 24 by its movement is attached, and four sets of attachment/detachment devices, generally designated by reference numeral 36, are attached to each sleeve 35 on the side opposite to the mold of the movable platen 34. The screw 32a is provided on a part of the outer periphery of the screw 32a. This attachment/detachment device 36 is attached to the movable platen 34.
A nut box 38 is formed in a U-shape and is connected to the boss portion 34a with four bolts 37 to form a box shape together with the boss portion 34a. Inside the nut box 38, there is provided a half-shaped split nut 39, which is supported by the bolt 37 and has a female thread cut on its inner circumferential surface to be engaged with the screw 32a. The split nut 39 has an elongated hole for fitting the bolt 37, so that the split nut 39 can move freely in the left-right direction in FIG. 3 along the nut box 38. Reference numeral 40 denotes a removable cylinder attached to the nut box 38, and a lever 41 is fixed to the piston thereof so as to be movable in the vertical direction.A pair of long and short links 42 and 43 are provided at both upper and lower ends of the lever 41. Each is pivoted. The long link 42 is connected at one end with a connecting link 44 and at the other end with a split nut 3.
The other end of the short link 43 is pivotally connected to the other nut piece 39b of the split nut 39. With this configuration, when the piston of the removable cylinder 40 moves back and forth using fluid pressure, the nut pieces 39a and 39b move in opposite directions via the lever 41 and the links 42 and 43, and the split nut 39 is screwed. 32a
The movable platen 34 and the sleeve 32 may be fixed by engaging with each other, or the movable platen 34 may be disengaged from the sleeve 32 to fix the movable platen 34 and the sleeve 32.
and the sleeve 32 become slidable. Note that the four detachable cylinders 40 are activated at predetermined timings according to commands from the control device.

On the other hand, a mold opening/closing cylinder 46 is pivotally supported on brackets 45 integrally formed on both sides of the fixed platen 23, and its piston rod 47 is pivotally supported on brackets 48 integrally formed on both sides of the movable platen 34. has been done. Then, by opening the split nut 39 using the detachable cylinder 40 and moving the piston rod 47 of the mold opening/closing cylinder 46 forward and backward using hydraulic pressure, the movable platen 34 is moved forward and backward on the sleeve 32 accompanied by the detachable device 36, and the movable mold 35 is configured to be opened and closed with respect to the fixed mold 24.

Further, a pair of die height adjustment cylinders 49 are pivotally attached to the connecting plate 31b of the support plate 31 via a bracket 50, and the working end of the piston rod 51 is fixed to the movable platen 34 via a bearing 51a. . By doing this, when the split nut 39 of the attaching/detaching device 36 is opened and the nut 27 is rotated as described above, the piston rod 51 fixed to the movable platen 34 is fixed to the connecting plate 31b while remaining stationary. Since only the cylinder 49 moves forward and backward, the movable platen 34
The relative position between the die and the support plate 31 changes, and so-called die height adjustment corresponding to the thickness of the molds 24 and 35 is performed.

2 are a pair of extrusion cylinders fixed on both sides of the movable platen 34, and the extrusion plate 54 fixed to the working end of the piston rod 53 has the movable platen 34 and the movable metal plate 54 fixed to the working end of the piston rod 53. A plurality of extrusion pins (not shown) are implanted to penetrate through the mold 35, and when the mold is opened, the extrusion cylinder 5
By retracting the second piston rod 53, the extrusion pin protrudes into the cavity of the movable mold 35, and the product in the cavity is extruded.

The mold clamping device of the die casting machine configured as described above is provided with a safety device in case of incorrect die height adjustment. That is, Figures 4 and 5
In the figure, cylinder 2 of the mold clamping cylinder 26
The open end of 3b is connected to the cover 2 having a port 23c.
3d, and inside the cylinder 23b,
Tie rod 2 which is the piston of the mold clamping cylinder 26
The head 25b of No. 5 is slidably fitted.
In addition, on the rod end side of the mold clamping cylinder 26,
A port 23e is provided, and this port 23e
e and the port 23c on the head end side are:
They are connected by a differential circuit 55. A switching valve 58 connected to a pump 56 and a tank 57 is provided in the differential circuit 55, and a pressure switch 60 and a pressure gauge 61 are connected to a pipe 59 connecting the port 23e and the switching valve 58. A pipe 62 having a branched pipe 62 is branched. The head end side and the rod end side of the head 25b are communicated through a flow path 63, and within this flow path 63, a conventionally well-known check valve 64 is provided. This check valve 64 is equipped with a spool 64b that is biased in the closing direction by a compression coil spring 64a, and normally closes the flow path, but if the head end side becomes high pressure or the spool 64b is pushed by an external force. By doing so, the flow path 63 is opened. In this device, the spool 64b is attached to the head 25b.
The spool 64b protrudes from the end face of the head end side as shown by the symbol t in the figure, and as a result of the head 25b being moved by the hydraulic pressure on the rod end side, the spool 64b moves toward the cover 2.
3d, the check valve 64 opens and the rod end side and head end side of the flow path 63 communicate with each other. In FIG. 4, the molds 24 and 35 are
The figure shows the mold alignment state before mold clamping, and the symbol t ₁ in the figure
It has a mold clamping allowance shown as . Further, in FIG. 5, the head 25b shows the mold clamping start position, and a gap t is formed on the rod end side thereof, which is the same as the protrusion dimension of the spool 64b. From this state, the head 25b moves forward and mold clamping is performed, but if the die height adjustment is performed normally, when the spool 64b comes into contact with the inner surface of the cover 23d, that is, when the head 25b and the cover 23
It is set so that mold clamping is completed when a gap t is left between b and the inner surface. And head 2
When the rod 5b moves further forward, the spool 64b is pushed and the flow path 63 is opened, and the pressure oil on the rod end side is returned to the head end side through the flow path 63.
It is configured to be returned to the tank 57 from the port 23c via the switching valve 58. And this is
This occurs when the die height adjustment is incorrect and the molds are not matched, and the dimension indicated by the symbol _t1 in FIG. 4 is larger than this.

The mold clamping and casting operations performed by the die casting machine configured as described above will be explained. When the molds 24, 35 are installed, the piston rod 47 of the mold opening/closing cylinder 46 is moving forward to open the mold, and the piston rod 51 of the die height adjusting cylinder 49 is retracting. Further, the split nut 39 of the attachment/detachment device 36 is open. Therefore, when the chain 29 is run by a motor and the four sprockets 28 are rotated synchronously, the nut 27, which is integrated with the chain 29, rotates within the nut box 31a, and the nut 27 is attached to the sleeve 32 by being engaged with the screw 25a. and move on the tie rod 25. At this time, the movable platen 34 and the piston rod 51 integrated therewith are stationary, and the cylinder 49 integrated with the support plate 31 moves, so the die height is adjusted in accordance with the thickness of the molds 24 and 35, and the cylinder 4
The relative axial position between piston rod 9 and piston rod 51 changes.

Therefore, when the piston rod 47 of the mold opening/closing cylinder 46 is moved backward, the movable platen 34 moves on the sleeve 32 at high speed, the movable mold 35 approaches the fixed mold 24, and the piston rod 51
moves toward the rod end inside the stationary cylinder 49. As shown in FIG. 4, just before the molds 24 and 35 are brought together, pressure oil is introduced to the rod end side of the mold opening/closing cylinder 46, its motion is switched from high speed to low speed, and the piston rod 51 moves further. The movement of the movable platen 3 is restricted by the tip of the cylinder 49.
4 moves along with the sleeve 32 via the support platen 31, and the mold matching is completed. During this mold matching, as mentioned above, the intermediate draft shown in Figures 4 and 5 is
t ₁ , t are formed. At the same time as the mold matching during this movement, the attachment/detachment cylinder 40 operates, and the rod 4
1. The split nut 39 is closed to the state shown in the figure via the links 42 and 43, and the mold clamping cylinder 2 is closed.
Since the oil is sent to the rod end side of the mold 6, the tie rod 25 and the movable platen 34 move forward as one, and the mold is clamped. During mold clamping, the check valve 64 is closed because the pressure on the rod end side is higher than on the head end side. When the head 25b moves forward and the protruding end of the spool 64b comes into contact with the inner surface of the cover 23d, mold clamping is completed and the pressure switch 60 is activated to stop oil supply to the rod end side. A large mold clamping force is applied.

After the mold is clamped, the injection cylinder injects the molten metal into the cavities of the molds 24 and 35 in response to a signal from the control device, and waits for the molten metal to solidify and cool before opening the mold.
For this purpose, if the switching valve 58 of the differential circuit is switched,
Pressure oil from the rod end side of the mold clamping cylinder 26 is removed and the oil is sent to the head end side, so that the tie rod 25 moves in the mold clamping force release direction. Then, when the split nut 39 is opened and the piston rod 47 of the mold opening/closing cylinder 46 is advanced, the movable platen 34
moves on the sleeve 32, and the solidified product moves toward the movable mold 35. The mold opening ends when the piston rod 51 comes into contact with the other end of the cylinder 49, so by retracting the piston rod 53 of the extrusion cylinder 52, the extrusion pin is projected into the cavity of the movable mold 35 via the extrusion plate 14. to extrude the product.

The above explanation is based on the case where the die height adjustment is performed normally.
If the die height adjustment is made by misjudged the dimension 5 to be larger than the actual dimension, when the mold matching is completed, the mold matching gap shown by the symbol _t1 in Fig. 4 will be larger than this, and the two metal parts will be separated. The molds 24 and 35 are separated by a large distance. From this state, mold clamping is performed as described above, but even if the spool 64b contacts the inner surface of the cover 23d, the predetermined mold clamping force is still not achieved, so the pressure switch 60 does not operate and the head 25b moves forward. Continue. Therefore, the spool 64b is pushed by the inner surface of the cover 23d against the elastic force of the compression coil spring 64a, the check valve 64 is opened, and the flow path 63 is communicated, so that the pressure oil on the rod end side flows through the flow path 63. The water is returned to the head end through the switching valve 58 and then returned to the tank 57. Therefore, since the pressure switch 60 does not detect the pressure increase and does not issue a signal, injection is not started without the mold being clamped.

Although this embodiment shows an example in which the present invention is applied to a die-casting machine with a horizontal clamping mold, it can be applied to a die-casting machine with a vertical clamping mold as well. The same can be applied to plastic injection molding machines with closed molds.

[Effect of idea]

As is clear from the above explanation, according to the present invention, in a mold clamping device for pressure molding, a cylindrical part with a cover, which is a part of a fixed platen, is used as a cylinder, and one end of the head is slidably fitted into this cylindrical part. A differential circuit connects the head end side of the clamping cylinder and the rod end side of the mold clamping cylinder, which uses the tied rod as a piston. The protruding end of the spool that protrudes from the head end side end face of the die is provided with a check valve that communicates the flow path when the protruding end of the spool comes into contact with the inner surface of the cylinder cover and is pushed. By configuring the rod end side pressure oil to be returned to the tank via the flow path and differential circuit, there is no risk of injection being performed with insufficient mold clamping, which improves safety and improves machine safety. There is no need to reduce the pressure on the rod end side physically or electrically, simplifying the hydraulic circuit and control circuit.

[Brief explanation of drawings]

1 to 5 show an embodiment of the pressure molding mold clamping device according to the present invention, and FIG. The figure is also a partially cutaway side view, Figure 3 is a sectional view along AA of Figure 2, Figure 4 is a sectional view and hydraulic circuit diagram near the mold clamping cylinder, and Figure 5 is an enlarged sectional view of the main part of Figure 4. , FIG. 6 is a schematic plan view of a die casting machine incorporating a conventional pressure molding mold clamping device. 23...Fixed platen, 23b...Cylinder,
23c, 23e...port, 23d...cover,
25...Tie rod, 25b...Head, 26...
...Mold clamping cylinder, 55...Differential circuit, 58...Switching valve, 60...Pressure switch, 63...Flow path, 6
4...Check valve, 64a...Spool.

Claims (1)

[Scope of utility model registration request] In a mold clamping device for pressure molding, the mold clamping device has a mold clamping cylinder in which the cylinder is a cylindrical part with a cover formed on a part of the fixed platen, and the piston is a tie rod with one end of the head slidably fitted into the cylindrical part. The head end side and the rod end side of the mold clamping cylinder are connected by a differential circuit, and a flow passage passing through the head end side and the rod end side of the head, and a spool disposed within this flow passage, the tip of the spool is connected to the head end side of the head. A mold clamping device for pressure molding, characterized in that it is provided with a check valve which projects from a side end face and connects the flow path when the projecting end comes into contact with the inner surface of the cover and is pressed.