JPH0228248Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic system used in a processing machine for high-temperature work, and aims to improve the durability, safety, and economic efficiency of the hydraulic system.

In hydraulic systems used in high-temperature processing machines such as hot forging presses, die-casting machines, and injection molding machines, an abnormal rise in oil pressure due to a rise in oil temperature after the start of operation is unavoidable.

In the conventional device, pressure oil leaked from the directional control valve, so there was no need to specifically relieve the increase in oil pressure.Instead, in order to prevent the oil pressure from decreasing,
Hydraulic pumps had to be operated frequently to supply pressurized oil.

In this case, there are drawbacks such as shortening the life of the hydraulic pump, degrading the hydraulic oil, and requiring an oil cooler.

In order to solve the above problem, the present invention provides a directional valve that can seal the hydraulic oil passage between the hydraulic actuator and the directional valve attached to the processing machine used for high-temperature work, and also By connecting a direct-acting relief valve with a small cross-sectional area and a long full-length throttle passage, it is possible to provide reliable relief in the event of an abnormal rise in oil pressure due to a rise in the temperature of the pressure oil in the hydraulic oil passage, and also to prevent large shocks on the processing machine side. This prevents relief from occurring at the peak pressure caused by the pressure, and allows the hydraulic pump to be stopped while maintaining the hydraulic pressure at the set pressure.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 schematically shows a press machine used for high-temperature work, and is configured to fix a lower mold 3 and an upper mold 4 to a lower base 1 and an upper base 2, respectively, using hydraulic clamp mechanisms 5 and 6, respectively. At the same time, a hydraulic lift mechanism 7 for carrying in and out the lower mold 3 is attached to the lower base 1.

FIG. 2 shows a hydraulic clamp mechanism 5 for fixing the lower mold, and this hydraulic clamp mechanism 5 hydraulically presses a clamp body 8, a clamp lever 10 pivotally supported to the clamp body 8 via a pin 9, and a clamp lever 10. A single-acting actuator 5a consisting of a piston 11 and a cylinder 12 for guiding the piston 11, a spring 13 for double return of the clamp lever 10, etc., supplies pressurized oil to an oil chamber 12a formed in the lower part of the cylinder 12. As a result, the piston 11 rises and pushes up one end of the clamp lever 10, causing the clamp lever 10 to swing around the pivot pin 9, and the lower mold 3 is moved between the other end 10a of the clamp lever 10 and the lower base. It is designed to be clamped and fixed. Then, attach the clamp body 8 to the lower base 1.
The lower mold 3 of any size can be fixed by changing the position along the guide groove 1a formed in the lower mold 3. Note that the clamp mechanism 6 of the upper base 2 is constructed in the same manner.

As shown in FIG. 3, the hydraulic lift mechanism 7 includes a lifter body 15 equipped with rollers 14, a hydraulic cylinder 17 for lifting the lifter body hydraulically, a hydraulic piston 16 that moves in and out relative to the hydraulic cylinder 17, and a plurality of lifter bodies 15. The hydraulic cylinder 17 is pushed up by supplying pressure oil from an oil passage formed in the lifter body 15 to an oil chamber 17a formed in the upper part of the cylinder 17. As a result, the lifter main body 15 is lifted and protrudes above the lower base 1, and as the pressure oil is discharged from the oil chamber 17a, the cylinder 17 is lowered by the elastic force of the compound spring 18, and the lifter main body 15 is lowered. is configured to be stored within the lower base 1.

The hydraulic device H includes a single-acting hydraulic actuator 5 of a hydraulic clamp mechanism 5 and a hydraulic lift mechanism 7.
a and 7a, a directional control valve V with a pressure switch, a direct acting relief valve 59 connected to the hydraulic oil passage 58 from this directional control valve V to the hydraulic oil chamber 12a of the hydraulic actuator 5a, and a directional control valve V connected to the above-mentioned directional control valve V. It consists of a hydraulic pump 21, an oil tank 22, etc.

5 to 7 show details of the directional control valve V, which includes two unit directional control valves 1.
9 and 20 are a pair of left and right side plates 26 and 27
The input port 2 of each directional control valve 19, 20 is clamped and fixed with bolts 26a, 27a between them.
8 and 29 and return ports 30 and 31 are communicated with each other and connected to a pressure oil introduction port 32 and a return oil discharge port 33 formed in one side plate 27, respectively. In addition, each direction switching valve 19,
Output ports 34 and 35 to the respective hydraulic actuators 5a and 7a are formed in the front surfaces of the valve boxes 19a and 20a, and an oil supply passage 36, which communicates the output ports 34 and 35 with the input ports 28 and 29, is provided in the 20. 3
Check valves 38, 39 on the input ports 28, 29 side of 7
, the feed stop valves 40, 41 are installed on the output port side.
The check valves 3 and 3 are interposed in a state where they are biased in the direction of separation by valve closing bias springs 38b and 39b, respectively, and the check valve 3
When the valve elements 38a and 39a of 8 and 39 come into elastic contact with the valve seat part by the urging force of the valve closing urging springs 38b and 39b, the pressure oil flows back from each output port 34 and 35 to the input port 28 and 29. is blocked.

In addition, a discharge stop valve 44, 45 is closed on the return port 30, 31 side of the discharge oil passage 42, 43, which communicates each output port 34, 35 with each return port 30, 31. The valves are inserted in a state where the valves are biased to close by biasing springs.

The feed stop valve 40 and the discharge stop valve 44 of the directional control valve 19 and the feed stop valve 41 and the discharge stop valve 45 of the directional control valve 20 are opened and closed by opening and closing devices, and the feed stop valve 40 ,41
is opened and the discharge stop valves 44, 45 are closed, and a discharge position where the supply stop valves 40, 41 are closed and the discharge stop valves 44, 45 are open. There is.

The opening/closing device includes operating rods 46, 47 that operate valves 40a, 41a of feed stop valves 40, 41.
and valves 44a of discharge stop valves 44, 45,
45a, operating shafts 50, 51 that receive the ends of each operating rod 46, 48 and 47, 49, and operating levers 52, 53 of each operating shaft 50, 51. Axis 50,5
1 are pivotally supported at the lower portions of valve boxes 19a and 20a, respectively.

Each operating shaft 50 and 51 has respective operating rods 46, 49 and 4, as shown in FIGS. 8 and 9.
Cam surfaces 46a, 49a and 4 opposite to 8, 47
8a, 49a are formed by cutting, and both operating shafts 5
0 and 51 are arranged so that rods 46-48 and 49-47 are operated inversely to each other.

Here, in order to prevent mutual interference between the clamp mechanism 5 controlled by the directional switching valve 19 and the lift mechanism 7 controlled by the directional switching valve 20, the operating shaft 50 is
The two-way switching valves 19 and 20 are formed to have the mechanism shown in FIG. 10 by the pin 55 implanted in the pin 55 and the cam surface formed on the operating shaft 51.

When driving the clamp mechanism 5, the operating lever 53
When the directional control valve 20 is held in the discharge position, the valve element 45a of the discharge stop valve 45 is pushed up by the operating rod 49, and the output port 35 of the directional control valve 20 and the discharge oil passage 43 are opened. At the same time, the feed stop valve 41 is equipped with an operating rod 47.
does not act, the feed stop valve 41 and the check valve 39 are in the closed position, and the output port 35 is closed.
The pressure oil from the return port 3 passes through the discharge oil passage 43.
1, the lift mechanism 7 is stored within the lower base 1. Next, when the operating lever 52 is pulled up and the directional control valve 19 is switched to the non-return and feeding position, the valve element 40a of the feeding stop valve 40 is pushed up by the operating rod 46, and the feeding stop valve 40 is opened. While being held in the open position, the discharge stop valve 44
is kept in the closed position. Then, input port 28
The pressure oil pushes open the check valve 38 with its hydraulic pressure, enters the output port 34 through the oil supply path 36, and the clamp mechanism 5 is driven.

On the contrary, in order to replace the lower mold 3 and upper mold 4,
When driving the lift mechanism 7, the operating lever 52
is lowered and the directional control valve 19 is placed in the discharge position.
The feed stop valve 40 is closed by the combined force of the elastic force of the valve-closing spring 38b and the hydraulic pressure from the input port 28, and the discharge stop valve 44 is pushed open by the operating rod 48 to connect to the output port 34. The discharge oil path 42 is communicated with the output port 34, pressure oil is discharged from the output port 34 to the return port 30, and the clamp mechanism becomes unclamped. Next, when the operating lever 53 is lowered to switch the directional control valve 20 to the non-return/feeding position, the feed stop valve 41 of the directional control valve 20 becomes open and the discharge stop valve 45 becomes closed. The check valve is pushed open by the oil pressure from the port 29, and the input port 29 and the oil supply passage 37 are brought into conduction. Pressure oil enters the output port 35 from the oil supply passage 37, the lift mechanism 7 is driven, and the lift mechanism 7 rollers 14 float above the lower base 1.

The operating levers 52 and 53 are configured to be locked in respective operating positions by locking pins 52a and 53a, respectively.

Next, the direct acting relief valve 59 attached to the hydraulic oil passage 58 from the output port 34 of the directional control valve 19 to the hydraulic actuator 5a of the clamp mechanism 5 will be described.

This relief valve 59 is used to increase the oil temperature of the pressure oil in the hydraulic oil passage 58 when performing high-temperature work in a press machine while holding the directional control valve 19 in the non-return and feeding position and clamping it with the clamp mechanism 5. As a result, volumetric expansion of the hydraulic oil occurs, leading to an abnormal increase in oil pressure.However, although this gradual substantial increase in oil pressure can be reliably relieved, the impact of the press operation causes the hydraulic oil passage 5 to
This is a temperature-guaranteed direct-acting relief valve that does not provide relief under the peak pressure that appears in the pressure oil.

As shown in FIGS. 11 and 12, the direct acting relief valve 59 is connected to the output port 34 of the directional control valve 19.
The pressure oil introduction hole 60 of the relief valve 59 is connected to the hydraulic oil passage 58 via a T-joint on the outside of the valve, and the pressure relief hole 61 of the relief valve 59 is connected to the directional switching valve via a pressure relief oil passage 61a transparently provided in the side plate 26. 19 return port 3
It is connected to 0.

A valve body 63 is installed inside a cylindrical hole-shaped valve chamber 62 formed in a valve box 59a of the relief valve 59, and
A pressure oil introduction hole 60 is formed in a boss portion protruding from the lower side of the valve box 59a. The peripheral wall at the terminal end of the pressure oil introduction hole 60 is made to protrude into the valve chamber 62 to form the valve seat 60a.
A valve surface 63a on the bottom surface of the valve body 63 is pressed against the valve seat 60a by a spring 64 to open the valve.

A synthetic resin sealing member (not shown) may also be embedded in the valve surface 63a to improve sealing performance.

A pressure oil relief hole 61 is formed in the front surface of the valve box 59a so as to communicate with the lower part of the valve chamber 62.

In addition, a female thread groove 60b is provided on the inner periphery of the pressure oil introduction hole 60.
Two male screws 60c are screw-fitted into the female screw groove 60b, and screwed into each other in a pressing manner to form a rotation prevention mechanism.

A throttle passage is formed in the screw fitting gap between the female screw groove 60b and the male screw 60c, but the cross-sectional area of this throttle passage is extremely small and the total length of the passage is extremely long. The flow resistance of the passage becomes extremely large.

Therefore, when the oil pressure substantially increases due to a rise in oil temperature, the oil leaks from the throttle passage, opens the valve, and is relieved into the pressure oil relief hole 61.

However, when instantaneous peak pressure is generated due to the impact of the press machine, this peak pressure is absorbed in the throttle passage with large flow resistance and appears in the pressure oil introduction hole 60 above the male thread 60c. There isn't.

However, the total passage length and passage cross-sectional area of the above-mentioned throttle passage are determined by the physical properties of the hydraulic fluid (especially volumetric expansion coefficient and viscosity),
It is desirable to set it appropriately according to factors such as the temperature increase, the rate of temperature increase, and the volume of the hydraulic oil that is accompanied by the temperature increase.

The symbol F in the figure is a filter, and the relief valve 5
In order to prevent the relief valve from malfunctioning due to minute foreign matter in the hydraulic oil flowing into the valve 9, the inlet of the pressure oil introduction hole 60 of the relief valve 59 and the operation inside the directional control valves 19 and 20 are Minute foreign matter in the oil flows into the check valves 38, 39 and the discharge stop valve 44,
45, the pressure oil introduction port 32 of the side plate 27 and the output ports 34, 3 of each directional control valve 19, 20
It will be installed in 5th class.

This filter F, as shown in FIG.
It is formed by sandwiching a fine mesh wire mesh 66 between two synthetic resin perforated plates 65, and each port 3
2, 34, 35 connectors 32a, 34a, 35a
It is attached by holding it down with the inner edge of the back end.

The structure of the filter F is not limited to the above, and may be one in which wire mesh is laminated, or may consist only of various perforated plates. Further, the number of filters F is not limited to one, but a plurality of filters can also be installed.

In addition to the above, the directional switching valves 19 and 20 may be valves that are operated by a pneumatically operated or solenoid type opening/closing device.

Note that the two directional control valves 19 and 20 are not limited to being arranged side by side as described above, but a plurality of directional control valves may be arranged side by side and sandwiched between the left and right side plates 26 and 27. It is also conceivable to directly fix a pressure switch that detects the pressure in the output port of each directional valve to the valve box.

Furthermore, a direct acting relief valve connected to the hydraulic oil passage 58 may be used.

Since the present invention is configured as described above, it has the following effects.

(1) A check valve and a feed stop valve are installed between the input port and the output port of the directional control valve, biased to close in the direction away from each other, and a check valve and a feed stop valve are installed between the output port and the return port. The discharge stop valve is biased closed and installed, and the closing action of this check valve and discharge stop valve opens the hydraulic oil path between the hydraulic actuator of the processing machine for high-temperature work and the output port of the directional control valve. A direct-acting relief valve is installed in this hydraulic oil passage, so when the directional control valve is in the non-return and feed position, it prevents pressure oil from leaking from the output port to the input port. Since it is shut off by the action of the check valve, the hydraulic pump can be stopped while maintaining the hydraulic pressure at the set pressure.

Therefore, the durability of the hydraulic pump is improved, the hydraulic oil is less likely to deteriorate, an oil cooler is not required, and power consumption can also be reduced.

In addition, when the oil pressure increases due to a rise in oil temperature, the direct-acting relief valve reliably provides relief, preventing the oil line hose from bursting or the directional control valve not being able to switch.
Accidents such as damage to hydraulic actuators are eliminated.

(2) In particular, in the pressure oil introduction hole of a direct-acting relief valve, a throttle passage consisting of a threaded fit between a male thread and a female thread groove, with a small passage cross-sectional area and a long passage overall length, is formed. When the oil pressure increases due to a rise in temperature, the oil will definitely be relieved, but it will not be relieved when the large peak pressure propagates to the pressure oil due to the large impact of the processing machine.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic configuration diagram of a press machine, Fig. 2 is a longitudinal sectional front view of the hydraulic clamp mechanism, Fig. 3 is a longitudinal sectional front view of the hydraulic lift mechanism, and Fig. 4 is a hydraulic Circuit diagram, FIG. 5 is a longitudinal sectional front view of the directional control valve, FIG. 6 is a partially cutaway side view of the directional control valve, FIG. 7 is a partially cutaway front view showing a part of the directional control valve, and FIG. The figure is a sectional view taken along the line a-a in FIG. 5, FIG. 9 is a sectional view taken along the line bb-b in FIG. 5, FIG.
The figure is a front view of the directional control valve, FIG. 12 is a longitudinal sectional side view of the direct acting relief valve, FIGS. 13 and 14 are partial longitudinal sectional views of the pressure oil port and the output port, respectively.
FIG. 15 is a partial vertical sectional view of the filter. 5a...Hydraulic actuator, 12a...5a
Hydraulic oil chamber, 19... Directional switching valve, 19a...1
9 valve box, 21...hydraulic pump, 22...oil tank, 28...input port, 30...return port,
34... Output port, 36... Oil supply path, 38...
... Check valve, 38a ... Valve element 38, 38b ... Valve seat, 40 ... Stop valve for feeding, 42 ... Discharge oil passage, 44 ... Stop valve for discharge, 52 ... Opening/closing operation tool, 58... Hydraulic oil passage, 59... Direct acting relief valve, 59a... Valve box of 59, 60... Pressure oil introduction hole, 60a... Valve seat, 60b... Female thread groove, 60
c...Male thread, 61...Pressure oil relief hole, 62...Valve chamber, 63...Valve body, 64...Spring.

Claims (1)

[Scope of utility model registration request] A directional switching valve 19 is connected to an oil path extending from the hydraulic pump 21 to a hydraulic actuator 5a attached to a processing machine used for high-temperature work.
The input port 28 and the output port 34 formed in the valve box 19a are connected through an oil supply passage 36, and the output port 34 and the return port 30 are connected through a discharge oil passage 42. A check valve 38 and a feed stop valve 40 are assembled in the holder, and a spring 38b is interposed between the valve element 38a of the check valve 38 and the valve element 40a of the feed stop valve 40, so that both valve elements can be closed. 38a and 40a in the direction away from each other, the check valve 38 and the feed stop valve 40 are urged to close, and the discharge stop valve 44 in the discharge oil path 42 is urged to close. By configuring both stop valves 40, 44 to be openable by the opening/closing operation tool 52, the directional control valve 19 can be configured to have a reverse configuration in which the feed stop valve 40 opens and the discharge stop valve 44 closes. It is configured to be able to be selectively switched between a stop and feed position and a discharge position where the feed stop valve 40 is closed and the discharge stop valve 44 is opened, and the directional control valve 19 serves as a check and feed position. In the position, the output port 34
A check valve 38 prevents the backflow of pressure oil from the input port 28 to the input port 28.
The valve element 38a is securely brought into contact with the valve seat 38b on the input port 28 side by the combined force of the spring pressure and the backflow hydraulic pressure.
The hydraulic oil passage 58 formed between the hydraulic oil chambers 12a and 12a is completely sealed, a direct acting relief valve 59 is attached to the hydraulic oil passage 58, and the valve box of the direct acting relief valve 59 is A valve chamber 62 is formed in 59a,
A valve body 63 is installed inside the valve chamber 62 and communicates with a pressure oil introduction hole 60 in a part of the valve chamber 62 and a pressure oil relief hole 61 in the other part.
is pressed against the valve seat 60a on the peripheral wall at the end of the pressure oil introduction hole 60 with a spring 64 to close the valve, a female thread groove 60b is formed in the pressure oil introduction hole 60, and a male screw 60c is screwed into this female thread groove 60b. and fix it with this screw fitting〓
A hydraulic system for use in a processing machine for high-temperature work, characterized in that a throttle passage is formed between the passages, the passage cross-sectional area is small, and the passage length is long, and the starting end of the pressure oil introduction hole 60 is connected to the hydraulic oil passage 58. .