JP2999332B2 - Hydraulic circuit of mold attaching / detaching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit of a mold attaching / detaching apparatus for attaching / detaching a mold to / from an injection molding machine or the like.

[0002]

2. Description of the Related Art In an injection molding machine, for example, a mold attaching / detaching device S is provided at a mold attaching portion R of a movable plate P and a fixed plate Q as shown in FIG. Mold M
Has been removed.

[0003] Conventionally, there is an apparatus shown in FIG. The mold attaching / detaching device 40 includes a main body 42 fixed to the mold attaching portion R of the movable plate and the fixed plate,
It comprises a clamp member 44 housed in the main body 42 so as to be able to move back and forth, and a hydraulic cylinder device 50 for moving the clamp member 44 back and forth. The clamp member 4
4 The front side of the front part, that is, the mold mounting part R side is a mold engaging part 46 having a tapered surface.

In the hydraulic cylinder device 50, a piston front piping port 54 is formed near the piston 52 at the most advanced position, and a piston rear piping port 56 is formed near the piston retreating position, and hydraulic circuits are provided at the piping ports 54, 56. Are linked.

A conventional hydraulic circuit has a configuration shown in FIGS. 5 and 6. The hydraulic circuit 60 includes a forward path 66 for supplying pressurized oil sent from the hydraulic pump to the hydraulic cylinder device 50 after passing through the pressure reducing valve 62 and the check valve 64, and an oil from the hydraulic cylinder device 50 to the tank. And a return path 68 for returning.
The forward path 66 and the return path 68 are connected to the hydraulic cylinder device 50 via a switching valve 70.

The hydraulic circuit 60 controls the pressurized oil sent from the hydraulic pump to the outward path 66 as shown in FIG. The pressure is then reduced by the switching valve 70 and supplied into the hydraulic cylinder device 50 through the piping ports 54 and 56 on both sides of the piston 52.

The pressurized oil supplied into the hydraulic cylinder device 50 from the piping port 54 on the front side of the piston is
And the pressurized oil supplied into the hydraulic cylinder device 50 from the piping port 56 on the rear side of the piston presses the rear surface 53 of the piston forward.

At this time, comparing the pressure receiving area of the piston front face 51 and the pressure receiving area of the piston rear face 53, the pressure receiving area of the piston rear face 53 is larger by the integral of the cross section of the piston rod 58. Therefore, the pressure applied to the piston rear surface 53 increases due to the pressure receiving area difference between the front and rear surfaces of the piston, and the piston 52 and the piston rod 58 integrated with the piston are pushed forward and moved forward. As a result, the clamp member 44 advances, and the mold substrate N is sandwiched between the mold engaging portion 46 formed of a tapered surface at the front of the clamp member and the mold mounting portion R. At this time, since the mold engaging portion 46 has a tapered surface, the front end of the clamp member 44 smoothly slides on the surface of the mold substrate N without hitting the end of the mold substrate N.

On the other hand, when the mold attaching / detaching device is unclamped, that is, when the mold is removed, the hydraulic circuit 60 has a switching valve 70 operated as shown in FIG. The return path 68 which is connected only to the port 54 and communicates with the tank 72 is connected to the pipe port 56 on the rear side of the piston 52. As a result, the piston 52 in the cylinder device 50 is pushed backward from the piston front surface 51 side by the pressurized oil depressurized by the primary pressure reducing valve 62, and accordingly, the oil on the piston rear surface 53 side is switched via the switching valve 70. It is returned to the tank 72 through the return route 68.

Incidentally, the clamp member 44 has a tapered surface at the front end of the mold engaging portion 46, so that the mold member N is repeatedly vibrated due to repeated opening and closing of the mold, or is pressed against the mold substrate N for a long time. In some cases, the clamp member 44 advances more than when the mold is attached, and the mold engaging portion 46 cuts into the surface of the mold substrate N more than when the mold is attached. For this reason, the mold may not be able to be removed unless a larger pressure is applied to the clamp member during unclamping than during clamping.

However, in the hydraulic circuit, the pressurized oil supplied to the cylinder device during clamping and unclamping is reduced to the same pressure by the pressure reducing valve. In addition, the pressure receiving area of the piston during clamping (corresponding to the cross-sectional area of the piston rod) and the pressure receiving area of the piston during unclamping (corresponding to the area of the front surface of the piston on the outer periphery of the piston rod) are generally approximated. Therefore, the pressure applied to both sides of the piston is substantially equal between the time of clamping and the time of unclamping, and unclamping may become difficult when the clamp member bites into the surface of the mold substrate N.

It is conceivable to provide another hydraulic circuit for unclamping, but there is a problem that the circuit becomes complicated and the cost increases.

[0013]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a hydraulic circuit of a mold attaching / detaching apparatus capable of making the unclamping force larger than the clamping force.

[0014]

According to the present invention, there is provided a mold attaching / detaching device for moving a clamp member back and forth by a hydraulic cylinder device, and pressurized oil is supplied to the hydraulic cylinder device during clamping by a switching valve. In the hydraulic circuit of the mold attaching / detaching device that supplies pressurized oil only to the front side of the piston in the hydraulic cylinder device and discharges oil behind the piston from the hydraulic cylinder device during unclamping, A primary pressure reducing valve is provided on the side of the hydraulic cylinder device, and a secondary pressure reducing valve is set on the hydraulic cylinder device side at a pressure lower than that of the primary pressure reducing valve. The switching valve is provided between the valves so that the oil behind the piston is discharged from the hydraulic cylinder device during unclamping and the pilot circuit of the secondary pressure reducing valve is provided. According to the hydraulic circuit of the mold attachment apparatus is characterized in that so as to communicate with the air.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention when clamping, and FIG. 2 is a hydraulic circuit diagram showing when unclamping.

The hydraulic circuit 10 includes a forward path 12 and a return path 14.
Between the forward path 12 and the return path 14 through the switching valve 16 through the piston front piping port 54 of the hydraulic cylinder device 50.
And a piston front flow path 18 and a piston rear flow path 20 connected to the piston rear piping port 56.

The forward path 12 is for supplying pressurized oil sent from the hydraulic pump to the hydraulic circuit 10, and has one end connected to the hydraulic pump and the other end connected to the switching valve 16.
In this forward path 12, a primary pressure reducing valve 22 is provided in series on the hydraulic pump side, and a secondary pressure reducing valve 24 is provided in series on the switching valve 16 side. A check valve 26 is provided between the primary pressure reducing valve 22 and the secondary pressure reducing valve 24.

The primary pressure reducing valve 22 and the secondary pressure reducing valve 24 are for adjusting the pressurized oil sent from the hydraulic pump to a predetermined pressure and then supplying it to the hydraulic cylinder device 50. The pressure is set lower than the primary pressure reducing valve 22. Commercially available pressure reducing valves 22 and 24 are used. In this embodiment, MG-02A-1-50 manufactured by Daikin is used. 23 and 25 indicated by broken lines are pilot circuits for adjusting the pressure of the pressure reducing valve.

The check valve 26 allows pressurized oil to flow from the hydraulic pump to the switching valve 16 and not to flow in the opposite direction.

The switching valve 16 comprises a four-port two-position switching valve. One side is connected to the outward path 12 and the backward path 14, and the other side is connected to the piston front flow path 18 and the piston rear flow path 20. The switching valve 16 connects both the piston front flow path 18 and the piston rear flow path 20 to the outward path 12 at the time of clamping as described later, while only the piston front flow path 18 is connected to the outward path 12 at the time of unclamping. Then, the other piston rear flow path 20 and the pilot circuit 25 of the secondary pressure reducing valve 24 are connected to the return path 14.

The return path 14 connects the switching valve 16 and the tank 28 to collect oil in the tank 28 at the time of unclamping and to provide a pilot circuit 25 for the secondary pressure reducing valve 24.
Is connected to the atmosphere, one end of which is connected to the tank 28 in the atmosphere, and the other end is connected to the switching valve 16.

The hydraulic cylinder device 50 forms a part of the mold attaching / detaching device, and the mold attaching / detaching device 40 shown in FIG.
It has the same configuration as. Further, the clamp member 44 and the like disposed at the front end of the piston rod 58 of the hydraulic cylinder device 50 also have the same configuration as that of the mold attaching / detaching device 40 described above.

Next, the operation of the hydraulic circuit 10 during clamping and unclamping will be described. In this embodiment, the primary pressure reducing valve 22 is 140 kg / cm ² and the secondary pressure reducing valve 24 is 7 kg / cm ² .
0 kg / cm ² and the diameter of the piston 52 is 50 m
m, the diameter of the piston rod 58 was 35.5 mm. The pressure receiving area of the piston at the time of clamping calculated from the diameters of the piston 52 and the piston rod 58 (corresponding to the cross-sectional area of the piston rod 58) is 9.9 cm ² , and the pressure receiving area at the time of unclamping (the piston at the outer periphery of the piston rod 58) 52 is 9.7 cm ² .

First, the clamp time shown in FIG. 1 will be described. At the time of clamping, in the hydraulic circuit, both the piston front flow path 18 and the piston rear flow path 20 are connected to the outward path 12 by the switching valve 16. The pressurized oil sent from the hydraulic pump to the outward path 12 becomes 140 kg / cm ² when passing through the primary pressure reducing valve 22, and becomes 7 kg when passing through the secondary pressure reducing valve 24.
After the pressure is reduced to 0 kg / cm ² , the flow is divided by the switching valve 16 and flows into both the piston front flow path 18 and the piston rear flow path 20.

70 kg / cm that has flowed into the piston front passage 18
² pressurized oil flows into the front side of the piston 52 from the piston front piping port 54 of the hydraulic cylinder device 50, while 70 kg / cm ² pressurized oil flowing into the piston rear flow path 20 is supplied to the piston of the hydraulic cylinder device 50. Piston 5 from rear piping port 56
2 Flow into the rear side. Then, the pressure receiving area of the piston at the time of clamping calculated above is 9.9 cm ² and the pressure of the pressurized oil is 70 kg /.
by the pressing force 693kg consisting product of cm ^2, and the piston 5
2 is pushed forward and moves forward. As a result, the clamp member 44 advances through the piston rod 58, and the mold engaging portion 46 formed of a tapered surface at the front end of the clamp member moves the mold substrate N
Attach to the surface.

On the other hand, at the time of unclamping, as shown in FIG.
8 is connected to the forward path 12, and the piston rear flow path 20 and the pilot circuit 25 of the secondary pressure reducing valve 24 having one end in the piston rear flow path 20 are connected to the return path 14.

The pressurized oil sent from the hydraulic pump to the outward path 12 is made 140 kg / cm ² when passing through the primary pressure reducing valve 22, and then flows through the secondary pressure reducing valve 24 into the piston front flow path 18. At this time, the pilot circuit 25 of the secondary pressure reducing valve 24 is connected to the atmospheric pressure tank 28 via the return path 14 so that the pilot pressure becomes the atmospheric pressure. Therefore, the pilot does not operate and the secondary pressure reducing valve 24 reduces the pressure. No longer. As a result, the pressurized oil flows into the piston front side from the piston front side piping port 54 of the hydraulic cylinder device 50 with the pressure at the time of passing through the primary pressure reducing valve 22 at 140 kg / cm ² .

The piston 52 is pushed backward by a pressing force of 1358 kg, which is the product of the pressure receiving area of the piston at the time of unclamping of 9.7 cm ² and the pressure of the pressurized oil of 140 kg / cm ² . As a result, the clamp member 44 is pushed backward by almost twice the force of the clamp, and retreats.
4 The tapered mold engaging portion 46 at the front end is securely separated from the mold substrate N. The oil located at the rear of the piston 52 in the hydraulic cylinder device 50 returns from the piston rear flow path 20 to the tank 28 through the return path 14.

[0029]

As shown and described above, according to the present invention, during clamping, pressurized oil decompressed in two stages by the two pressure reducing valves, the primary pressure reducing valve and the secondary pressure reducing valve, is supplied to the hydraulic cylinder device. On the other hand, at the time of unclamping, the pressurized oil depressurized only by the primary pressure reducing valve is supplied to the hydraulic cylinder device, so that the unclamping force of the mold attaching / detaching device can be made larger than the clamping force. Therefore, even when the clamp member having the tapered mold engaging portion bites into the surface of the mold substrate than when the mold is attached, the mold can be reliably removed. Moreover, only one hydraulic circuit is required as in the past,
Since there is no need to provide a separate circuit for unclamping,
There are no problems such as complicated circuits.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a clamp state according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing an unclamping state in the embodiment.

FIG. 3 is a sectional view of a mold attaching / detaching device.

FIG. 4 is a side view of the injection molding machine.

FIG. 5 is a hydraulic circuit diagram showing a conventional example at the time of clamping.

FIG. 6 is a hydraulic circuit diagram showing a conventional example at the time of unclamping.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Outgoing path 14 Return path 16 Switching valve 18 Piston front flow path 20 Piston rear flow path 22 Primary pressure reducing valve 24 Secondary pressure reducing valve 25 Pilot circuit of secondary pressure reducing valve 26 Check valve 44 Clamp member 50 Hydraulic cylinder device 52 Piston

Claims (1)

(57) [Claims] 1. A hydraulic cylinder device is connected to the hydraulic cylinder device of a mold attaching / detaching device for moving a clamp member back and forth, and a switching valve supplies pressurized oil to both sides of a piston in the hydraulic cylinder device during clamping by a switching valve. At the time of unclamping, in the hydraulic circuit of the mold attaching / detaching device for supplying pressurized oil only to the front side of the piston in the hydraulic cylinder device and discharging the oil behind the piston from the hydraulic cylinder device, the hydraulic pump side is a primary pressure reducing valve, The cylinder device side is a secondary pressure reducing valve set to a lower pressure than the primary pressure reducing valve. Two pressure reducing valves are provided in series on the outward path of the pressurized oil, and the switching valve is provided between the hydraulic cylinder device and the secondary pressure reducing valve. Oil at the rear of the piston from the hydraulic cylinder device during unclamping, and the pilot circuit of the secondary pressure reducing valve communicates with the atmosphere. Hydraulic circuit of the die detachment apparatus according to claim.