JP2000233300A - Overload preventing device for mechanical press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily change the set compensation pressure of a pressure compensating means according to changes of the set charging pressure of an oil pressure chamber for absorbing an overload. SOLUTION: A hydraulic pump 5, an overload preventing valve 10 and a pressure compensating means 14 are connected in parallel to an oil pressure chamber 3 for absorbing an overload in the slide 2 of a mechanical press 1, and a check valve 9 stopping a flow to the hydraulic pump 5 is provided. The pressure compensating means 14 is constituted by a choke path 26 and a relief valve 27 connected in series so that a relief operation is obtained when the pressure of the oil pressure chamber 3 rises at a very slow speed. The relief valve 27 is pressed to a closing position X by the resultant force of a valve closing force based on the pressure of the inlet side 9a of the check valve 9 and the valve closing force of a compression spring 29 for keeping a residual pressure, and it is also pressed to an opening position Y by a valve opening force based on the pressure of the outlet side 31 of the choke path 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing a mechanical press from being overloaded.

[0002]

2. Description of the Related Art An overload prevention device of this type has been disclosed in Japanese Patent Publication No. Hei. 5-20629 previously proposed by the present inventor. In the conventional device, an overload prevention valve is connected to an overload absorption hydraulic chamber formed in a slide of a mechanical press, and a relief member and a valve closing spring of pressure compensation means are provided inside the overload prevention valve, The relief member is closed by the urging force of the valve closing spring.

[0003]

By the way, the above-mentioned pressure compensating means releases only the pressure increase when the pressure oil in the hydraulic chamber rises at a very low speed from the set filling pressure during the press work. belongs to. Therefore, the relief pressure of the pressure compensating valve (hereinafter referred to as the set compensation pressure) is
It is necessary to set a value slightly higher than the above set filling pressure. Therefore, when increasing the set filling pressure according to the capacity and use of the mechanical press, it is necessary to increase the set compensation pressure accordingly, and similarly, when decreasing the set filling pressure as described above. It was necessary to lower the above set compensation pressure.

The above prior art is excellent in that the pressure compensating means is built in the overload prevention valve, so that the apparatus can be made compact. However, when the above set compensation pressure is changed, it is arranged inside the overload prevention valve. It is necessary to change the biasing force of the closed valve spring. Therefore, the change of the biasing force of the valve-closing spring and the confirmation test after the change require time and effort. An object of the present invention is to make it possible to easily change the set compensation pressure of the pressure compensating means according to the change of the set filling pressure of the overload absorbing hydraulic chamber.

[0005]

In order to achieve the above object, the invention of claim 1 is, for example, shown in FIG. 1 and FIG. 2 or FIG.
-As shown in Figs. 4 and 5, the overload prevention device for the mechanical press was configured as follows. A hydraulic pump 5 for supplying pressurized oil to the overload absorbing hydraulic chamber 3 in the slide 2 of the mechanical press 1 at a set filling pressure, and a check valve for preventing a flow from the hydraulic chamber 3 to the hydraulic pump 5 9, an overload prevention valve 10 which operates when the pressure in the hydraulic chamber 3 exceeds a set overload pressure, and a throttle path 26 and a relief valve 27 connected in series. And a pressure compensating means 14 which performs a relief operation when the pressure rises at a very low speed and exceeds a set compensating pressure. Is pressed to the closing position X by the combined force of the valve closing force based on the pressure and the valve closing force of the elastic means 29 for maintaining the residual pressure, and the opening position is controlled by the valve opening force based on the pressure on the outlet side 31 of the throttle path 26. So that it can be pressed to Y One in which the.

The first aspect of the present invention has the following operational effects. In order to increase the set filling pressure of the overload absorbing hydraulic chamber, the discharge pressure of the hydraulic pump may be increased. Then, at the same time, the hydraulic pressure on the inlet side of the check valve also increases, and the closing force of the relief valve also increases, so that the compensation pressure set by the pressure compensating means increases. Similarly, when decreasing the set filling pressure of the hydraulic chamber, the discharge pressure of the hydraulic pump may be reduced. Then, at the same time, the hydraulic pressure on the inlet side of the check valve also decreases, and the valve closing force of the relief valve also decreases.
The set compensation pressure of the pressure compensation valve decreases. Therefore, it is possible to automatically change the set compensation pressure of the pressure compensating means according to the change of the set filling pressure of the overload absorbing hydraulic chamber, and the change is easy and reliable.

Further, even if the pressure on the inlet side of the check valve disappears for some reason, the relief valve can be closed by the closing force of the elastic means.
Pressure oil of a predetermined pressure can be left in the overload absorbing hydraulic chamber. For this reason, the refilling of the hydraulic chamber with the pressure oil can be performed smoothly and promptly.

The relief valve 27 includes a valve closing piston 47 for pressing a relief member 48 in a valve closing direction, the valve closing piston 47 facing the valve closing piston 47, and the check valve. A valve closing operation chamber 49 connected to the inlet side 9a of the valve 9; and when the relief member 48 is urged in the valve closing direction by the elastic means 29, the relief valve of the pressure compensating means is opened. Simple to build.

Further, the relief member 48 and the valve closing piston 47 are integrally formed, and the elastic means 29 is constituted by a compression spring. When one end of the elastic means 29 is connected to the end wall of the valve closing working chamber 49 and the other end of the elastic means 29 is connected to the valve closing piston 47, the pressure compensating means is reduced in size. The device can be made compact.

Further, as shown in the fourth aspect of the present invention, the pressing force for closing the overload prevention valve 10 is reduced by a valve closing spring 10a.
In the case of the urging force, since the closing pressure of the overload prevention valve can be kept at the initial value even if the discharge pressure of the hydraulic pump is changed, the set overload pressure of the overload prevention valve is reduced. It can be prevented from being changed by mistake.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. First, the outline of the overload prevention device will be described with reference to the overall system diagram of FIG.

An overload absorbing hydraulic chamber 3 is formed in a slide 2 of a crank type mechanical press 1. The hydraulic chamber 3
Is connected to a hydraulic pump 5 via a connection path 4, and the hydraulic pump 5 supplies the above-described hydraulic chamber 3 with pressurized oil at a set filling pressure. The pressing force transmitted from the connecting rod 6 of the mechanical press 1 to the piston 7 is applied to a work material (not shown) via the pressure oil in the hydraulic chamber 3. A check valve 9 for preventing the flow from the hydraulic chamber 3 to the hydraulic pump 5 is disposed in the middle of the connection path 4.

When the slide 2 is overloaded for some reason and the pressure in the hydraulic chamber 3 exceeds the set overload pressure, the overload prevention valve 10 is operated to relieve, and the pressure in the hydraulic chamber 3 is reduced. If the pressure oil is above the overload prevention valve 10
Then, the oil is discharged to the oil tank 12 through the discharge passage 11 in sequence. As a result, the downward force acting on the piston 7 is absorbed by the compression operation of the hydraulic chamber 3 and is not transmitted to the slide 2, and as a result, overload is prevented. The pressing force for closing the overload prevention valve 10 is constituted by the biasing force of the valve closing spring 10a.

Further, the pressure oil in the hydraulic chamber 3 receives a pressing force during the pressing operation and rises in temperature, so that the pressure rises at a very low speed due to volume expansion. Then, when the slow speed rising pressure exceeds the set compensation pressure, the pressure compensating means 14 performs a relief operation and discharges only the slow speed rising pressure to the oil tank 12 through the discharge path 11. Thus, the overload prevention valve 10 can be prevented from being erroneously overloaded, and the hydraulic chamber 3 can be prevented from operating.
The pressure inside can be kept within a predetermined range.

The values of the set filling pressure of the hydraulic pump 5, the set compensation pressure of the pressure compensating means 14, and the set overload pressure of the overload prevention valve 10 are determined by the capacity and use of the mechanical press 1. varies depending on, for example, respectively, is set to a value of about 100 kgf / cm ² (about 10 MPa) and about 120 kgf / cm ² (about 12 MPa) and about 230 kgf / cm ² (about 23 MPa).

Next, a specific structure of the above-described overload prevention device will be described. In the first embodiment, the hydraulic pump 5 is constituted by a pneumatic hydraulic booster pump. More specifically, a hydraulic piston is connected to a pneumatic piston that is reciprocated by compressed air from a pneumatic source 16.
The pressure in the oil in the oil tank 12 is increased according to the cross-sectional area ratio between the two pistons (not shown), and the oil is discharged. Reference numeral 18 denotes a suction valve of the hydraulic pump 5 described above. The discharge valve of the hydraulic pump 5 is constituted by the check valve 9 described above.

Then, pressure oil discharged from a pump chamber (not shown) of the pump body 5a of the hydraulic pump 5 passes through the check valve 9, a branch chamber 23 described later, and the connection path 4 to each other. The overload absorbing hydraulic chamber 3 is filled sequentially. The discharge pressure of the booster type hydraulic pump 5 is adjusted by adjusting the air pressure by a pressure reducing valve 21 provided in the compressed air supply path 20.

The pressure compensating means 14 has a throttle path 26 and a relief valve 27 connected in series. The relief valve 27 is pressed to the closed position X by the combined force of the valve closing force based on the pressure on the inlet side 9a of the check valve 9 and the valve closing force of the compression spring (elastic means) 29 for holding the residual pressure. Along with
It is configured to be pressed to the opening position Y by a valve opening force based on the pressure on the outlet side 31 of the throttle path 26.

More specifically, as shown in FIG. 2, the pressure compensating means 14 is configured as follows. The pump case 35 of the hydraulic pump 5 and the housing 36 of the overload prevention valve 10 are shared by a common block 37.
Are formed integrally. The branch chamber 23 is formed in the common block 37, and a sleeve 38 and a cover bolt 39 are mounted in a space above the branch chamber 23 in a sealed manner in order from the inside. A throttle member 42 is fitted into the cylindrical hole 41 of the sleeve 38. Due to the fitting gap between the outer peripheral surface of the aperture member 42 and the cylindrical hole 41, the aperture path 26
Is configured. Note that a filter 43 is attached to a lower portion of the sleeve hole 41 of the sleeve 38.

The relief valve 27 is provided with the cover bolt 3
9 and a cylinder hole 46 formed in the cylinder hole 46.
A valve-closing piston 47 which is inserted in a sealing manner, a relief member 48 integrally formed with a lower portion of the valve-closing piston 47,
The valve closing working chamber 4 formed above the valve closing piston 47
9 and the compression spring (elastic means) 29 for urging the relief member 48 in the valve closing direction.

The above-mentioned valve closing operation chamber 49 is communicated with the inlet side 9a of the check valve 9 through the communication passage 51 (see FIG. 1). The communication passage 51 is provided with a vertical passage 5 provided in a threaded portion of the cover bolt 39 and the horizontal passage 52 in the cover bolt 39.
3 and an oblique passage 54 provided in the pump case 35. Here, the diagonal passage 54 is communicated with the inlet side 9a of the check valve 9 via a pump chamber (not shown) of the hydraulic pump 5.

One end of the compression spring 29 is connected to the cover bolt 39 which is an end wall of the valve closing operation chamber 49, and the other end of the compression spring 29 is connected to the valve closing piston 47. Are linked. A protruding valve surface 57 provided at a lower end of the relief member 48 is in contact with a valve seat 58 provided at an upper portion of the sleeve 38. The above-mentioned projecting valve surface 57
The hydraulic pressure of the branch chamber 23 acts upward on the cross-sectional area corresponding to the sealing diameter A inside the inside. On the other hand, the resultant force of the hydraulic pressure acting on the cross-sectional area corresponding to the sealing diameter D of the cylinder hole 46 and the urging force of the compression spring 29 acts on the valve closing piston 47 downward. .

The pressure compensating means 14 operates as follows. When the pressure in the overload absorbing hydraulic chamber 3 (and the branch chamber 23) is equal to or lower than the set compensation pressure, the pressure on the inlet side 9a of the check valve 9 (here, the discharge pressure of the hydraulic pump 5) ) Presses the valve-closing piston 47 downward, and the valve-closing force, which is the resultant of the pressing force and the urging force of the compression spring 29, overcomes the hydraulic pressure acting on the valve surface 57, The valve surface 57 is brought into close contact with the valve seat 58.

On the other hand, when the pressure in the hydraulic chamber 3 rises at a very low speed and exceeds the set compensation pressure, the hydraulic pressure acting on the valve face 57 becomes larger than the valve closing force. Thus, the valve face 57 is slightly separated from the valve seat 58.
Thereby, the pressure oil in the hydraulic chamber 3 is supplied to the connection path 4.
And the branch chamber 23, the filter 43, the throttle path 26, the opening gap of the relief valve 27, the outlet path 60, and the discharge path 11, and are discharged to the oil tank 12. . Thereby, the pressure of the hydraulic chamber 3 can be maintained between the set filling pressure and the set compensation pressure.

In order to increase the filling pressure of the hydraulic oil into the hydraulic chamber 3, the pressure reducing valve 21 provided in the compressed air supply path 20 is adjusted to supply the pressure to the booster type hydraulic pump 5. What is necessary is just to raise air pressure. Then, at the same time, the discharge pressure of the hydraulic pump 5 increases, the hydraulic pressure supplied to the valve closing operation chamber 49 increases, and the valve closing pressure of the relief valve 27 also increases. The set compensation pressure of the pressure compensation means 14 increases. Similarly, when lowering the pressure of the pressurized oil into the hydraulic chamber 3 when the air pressure is reduced, the oil pressure supplied to the valve closing operation chamber 49 is also reduced. Therefore, the set compensation pressure of the pressure compensation means 14 becomes low. Therefore,
The setting compensation pressure of the pressure compensating means 14 can be automatically changed according to the change of the filling pressure set in the overload prevention hydraulic chamber 3.

If the pressure on the inlet side 9a of the check valve 9 disappears for some reason, the pressure in the valve closing operation chamber 49 of the pressure compensating means 14 also disappears.
However, the relief member 48 is closed and brought into contact with the valve seat 58 by the urging force of the compression spring 29, so that a predetermined pressure oil remains in the branch chamber 23 and the hydraulic chamber 3. It is. Therefore, the refilling of the hydraulic chamber 3 with the pressure oil can be performed smoothly and promptly.

FIGS. 3 to 5 show the second to fourth embodiments, respectively. In these other embodiments, the same components as those in the first embodiment will be described in principle with the same reference numerals.

FIG. 3 shows a second embodiment, and FIG.
FIG. The embodiment of FIG. 3 differs from the above-described embodiment of FIG. 2 in the following points. Said cover bolt 39
The upper part of the aperture member 42 is inserted into the lower part of the upper part so as to be able to move in a vertical direction. The protruding valve surface 57 of the relief member 48 contacts the valve seat 58 on the upper end surface of the throttle member 42. The lower portion of the throttle member 42 is fitted in the through hole 65 of the common block 37, and the fitting path forms the throttle path 26.

The aperture member 42 operates as follows. When refilling the overload absorbing hydraulic chamber (not shown here) with the pressure oil, the pressure oil supplied to the valve closing operation chamber 49 lowers the valve closing piston 47, and Since the member 48 lowers the throttle member 42, the foreign matter clogged in the throttle path 26 is taken out to the branch chamber 23.

Further, when the above-described overload prevention valve (not shown here) is overloaded, the overload prevention valve opens rapidly, so that the pressure in the branch chamber 23 drops rapidly. Therefore, the valve-closing piston 47 strongly lowers the throttle member 42 via the relief member 48, and smoothly brings the foreign matter clogged in the throttle path 26 into the branch chamber 23. For this reason, the clogging of the throttle path 26 can be automatically prevented. As described above, in the embodiment of FIG. 3, the filter 43 shown in FIG. 2 can be omitted, and the maintenance is not required.

FIG. 4 shows a third embodiment, and FIG.
FIG. The embodiment of FIG. 4 differs from the above-described embodiment of FIG. 1 in the following points. Another check valve 68 is provided between the pump body 5 a of the booster type hydraulic pump 5 and the check valve 9, and a throttle valve 69 is provided in the communication passage 51. By providing the above-mentioned another check valve 68, the pressure pulsation on the inlet side 9a of the above-mentioned check valve 9 is reduced, and the height difference between the valve closing operation chamber 49 of the relief valve 27 of the pressure compensating means 14 and A large pulse pressure can be prevented from acting. Therefore, it is possible to improve the operation accuracy of the relief valve 27 and to prevent chattering of the relief valve 27.

By providing the throttle valve 69, it is possible to reliably prevent a pulse pressure having a large difference in height from acting on the valve closing operation chamber 49 of the relief valve 27. For this reason, the above-mentioned effect is further enhanced. It is also possible to omit one of the other check valve 68 and the throttle valve 69.

FIG. 5 shows a fourth embodiment, and FIG.
FIG. The embodiment of FIG. 5 differs from the embodiment of FIG. The hydraulic pump 5 is configured by a motor pump instead of the booster pump described above. That is, the pump main body 5a including a plunger pump or a gear pump is driven by the electric motor M.
The discharge side of the hydraulic pump 5 is communicated with the oil tank 12 via the pump relief valve 72, so that a constant discharge pressure always acts on the inlet side 9a of the check valve 9. ing.

Each of the above embodiments can be further modified as follows. The common block 37 in FIGS.
Instead of mounting the three devices of the hydraulic pump 5, the overload prevention valve 10, and the pressure compensating means 14, the overload preventing valve 10 and the pressure compensating means 14 Two devices may be attached, and the hydraulic pump 5 and the pressure compensating means 1
4 may be attached. Further, the above three devices 5, 10, and 14 can be manufactured as independent parts and connected by piping.

The relief member 48 of the pressure compensating means 14 can be formed separately from the valve closing piston 47 instead of being formed integrally with the valve closing piston 47. In this case, the compression spring 29, which is an elastic means, can be mounted between the above-described separate relief member 48 and the valve closing piston 47. The above elastic means may be a tension spring instead of the illustrated compression spring 29, and it is also possible to use rubber or the like. The throttle path 26 of the above-described pressure compensating means 14 can be constituted by a needle valve or the like instead of the illustrated fitting gap. The closing pressure of the overload prevention valve 10 may use the pressure of the compressed air instead of using the biasing force of the illustrated valve closing spring 10a.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention and is an overall system diagram of an overload prevention device.

FIG. 2 is a sectional view showing a pressure compensating means of the overload prevention device.

FIG. 3 is a view showing a second embodiment of the present invention and corresponding to FIG. 2 described above.

FIG. 4 shows a third embodiment of the present invention and is a view corresponding to FIG. 1 described above.

FIG. 5 shows a fourth embodiment of the present invention and is a view corresponding to FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mechanical press, 2 ... Slide, 3 ... Hydraulic chamber for overload absorption, 5 ... Hydraulic pump, 9 ... Check valve, 9a ... Inlet side, 10
... overload prevention valve, 10a ... valve closing spring, 14 ... pressure compensating means, 26 ... throttle path, 27 ... relief valve, 29 ... elastic means
(Compression spring), 31 ... Exit side of throttle path 26, 47 ... Valve closing piston, 48 ... Relief member, 49 ... Valve closing working chamber, X ...
Close position, Y ... Open position.

Claims (4)

[Claims] 1. A hydraulic pump (5) for supplying pressurized oil at a set filling pressure to an overload absorbing hydraulic chamber (3) in a slide (2) of a mechanical press (1), and the hydraulic chamber (3) A check valve (9) for preventing flow from the hydraulic pump (5) to the hydraulic pump (5);
The hydraulic chamber (3) is composed of an overload prevention valve (10) that operates when the pressure of (3) exceeds a set overload pressure, a throttle path (26) and a relief valve (27) connected in series. ) Comprising a pressure compensating means (14) for performing a relief operation when the pressure of the pressure compensating means (14) rises at a very low speed and exceeds the set compensation pressure. The relief valve (27) of the pressure compensating means (14) The valve is pressed to the closing position (X) by the combined force of the valve closing force based on the pressure on the inlet side (9a) of the stop valve (9) and the valve closing force of the elastic means (29) for maintaining the residual pressure. Restriction path (26)
Opening position by the valve opening force based on the pressure on the outlet side (31)
An overload prevention device for a mechanical press, wherein the device is configured to be pressed to (Y). 2. An overload preventing device for a mechanical press according to claim 1, wherein said relief valve (27) includes a valve-closing piston (47) for pressing a relief member (48) in a valve-closing direction, and said valve-closing piston (47). Valve piston
(47) and the inlet side (9) of the check valve (9).
a) a valve closing working chamber (49) communicated with a), wherein the relief member (48) is urged in the valve closing direction by the elastic means (29). Load protection device. 3. The overload prevention device for a mechanical press according to claim 2, wherein said relief member (48) and said valve closing piston (47) are integrally formed and said elastic means (29). Is constituted by a compression spring, and the elastic means comprising the compression spring
(29) is connected at one end to the end wall of the valve closing working chamber (49), and the other end of the elastic means (29) is connected to the valve closing piston (47). Overload prevention device for mechanical press. 4. The overload prevention device for a mechanical press according to claim 1, wherein the overload prevention valve (10) has a closing pressure of a valve closing spring.
(10a) An overload prevention device for a mechanical press, which is an urging force of (10a).