JPH0214909Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a hydraulic clamp device with a pressure intensifier.

<Prior art and problems to be solved by the invention> Conventionally, as described in, for example, Japanese Utility Model Publication No. 55-20427, a pressure intensifier was attached to the clamp body of a hydraulic clamp, and the pressure in the input oil chamber of the pressure intensifier was increased. The output oil chamber is connected to the oil supply/discharge port, and the output oil chamber is connected to the clamp oil chamber of the clamp cylinder. Pressure oil is supplied from the pressure oil supply/discharge port to the input oil chamber to operate the pressure intensifier, and the hydraulic oil in the output oil chamber is A system in which the pressure is increased and supplied to the clamp oil chamber to drive the clamp cylinder with boosted clamping power has been put into practical use.

However, in this structure, the no-load stroke movement from the unclamping position of the clamp cylinder to the clamping start position where it contacts the object to be fixed is also performed by the operation of the pressure intensifier. As a result, the drive stroke of the pressure intensifier required to move the clamp cylinder through a no-load stroke becomes long in proportion to the pressure increase rate.

For this reason, a large pressure intensifier with a long stroke is required, and a large amount of pressure oil is required for no-load stroke movement, resulting in large energy consumption.
The moving speed of the no-load stroke is reduced by the reciprocal of the pressure increase rate of the pressure intensifier, and clamping takes time.
There are problems such as.

Therefore, in Japanese Patent Application Laid-open No. 49-73776, a check valve is interposed in the oil passage to the clamp oil chamber of the clamp cylinder, and a pressure increase valve and a pressure increase valve are installed in the oil passage that bypasses the check valve of the oil passage. A pressure intensifier is provided to pressurize the oil in the clamp oil chamber by receiving hydraulic pressure from the input oil chamber through the
An automatic pressure increase device has been proposed that is configured to introduce hydraulic pressure into a return motion oil chamber of a clamp cylinder to a pressure increase valve to hold the pressure increase valve in an open position during return motion of the clamp cylinder.

In this automatic pressure booster, the pressure booster is installed separately from the clamp cylinder, so it is difficult to downsize the hydraulic clamp device.Moreover, the pressure booster valve has a special and complicated structure, so its manufacturing cost is high. The problem is that it is expensive.

The purpose of this invention is to provide a hydraulic clamp device with a pressure intensifier that can reduce the overall structure of the clamp cylinder and pressure intensifier in size and weight, and that can construct a hydraulic circuit using ordinary valves without using special valves. The goal is to provide the following.

<Means for solving the problem> The hydraulic clamp device with a pressure intensifier according to the present invention has the following features:
A hydraulic clamp device that clamps an article to be clamped includes a clamp cylinder having a piston and a clamp oil chamber, a pressure increase piston including an output plunger, and an input oil formed on the opposite side of the output plunger with respect to the pressure increase piston. A return spring that urges the pressure booster piston toward the input oil chamber, and an output oil chamber that communicates with the clamp oil chamber and pressurizes oil with the output plunger of the pressure booster piston, and is common to the cylinder body of the clamp cylinder. A hydraulic circuit interposed between a pressure intensifier incorporated in the housing member, a clamp oil chamber, an input oil chamber, and a hydraulic pressure supply source, the directional control valve being switchable between a supply device and a discharge position. and a first oil passage that connects the input oil chamber to the discharge port of the directional control valve; a sequence valve to be switched, a first check valve that is interposed in the first oil passage in parallel with the sequence valve and allows hydraulic pressure to flow out from the input oil chamber, and a first check valve that connects the clamp oil chamber to the discharge port of the directional control valve. 2 oil roads and
A second check valve that is interposed in the second oil passage and prevents oil pressure from flowing out from the clamp oil chamber;
A second oil passage branched from a second oil passage portion between the check valves, connected to a port of the directional valve that connects to the tank when the directional valve is in the discharge position, and is sealed when the directional valve is in the supply position. A hydraulic circuit with three oil passages is provided.

<Function> In the hydraulic clamp device with a pressure intensifier according to the present invention, when the directional control valve is switched to the supply position for clamp operation, the sequence valve initially maintains the closed position, and the hydraulic pressure is supplied to the second oil path and the second reverse The hydraulic pressure is supplied to the clamp oil chamber of the clamp cylinder and the output oil chamber of the pressure intensifier through the stop valve, so when the clamp device is no-load, hydraulic pressure is supplied to the clamp oil chamber without going through the pressure intensifier, and the piston of the clamp cylinder is activated. Operates at high speed. Next, when the load starts to act on the clamp device, the primary pressure in the first oil path becomes higher than the set pressure, the sequence valve is switched to the open position, and the oil pressure is transferred from the first oil path to the input oil chamber of the pressure booster. is supplied, the output plunger of the pressure intensifier piston pressurizes the output oil chamber and the clamp oil chamber, and the clamp device generates a strong clamping force. However, at this time, the hydraulic pressure in the clamp oil chamber is checked by the second check valve of the second oil passage, and the directional control valve is in the supply position and the port connected to the third oil passage is sealed, so the clamp oil chamber The second hydraulic pressure is
There will be no leakage from the oil channel.

On the other hand, when the directional control valve is switched to the discharge position to release the clamp, the port of the directional control valve to which the third oil passage is connected is connected to the tank, and the sequence valve of the first oil passage is switched to the closed position. The oil pressure in the clamp oil chamber quickly flows out to the tank through the second oil passage and the third oil passage, and the oil pressure in the input oil chamber flows through the first oil passage.
The oil passage, the first check valve, the second oil passage, the second check valve, and the third
It is discharged through the oil passage.

<Effects of the invention> According to the hydraulic clamping device with a pressure intensifier according to the invention, the pressure intensifier is incorporated into a common housing member with the clamp body of the clamp cylinder, thereby realizing a compact hydraulic clamping device with a pressure intensifier. At the same time, the hydraulic circuit can be constructed using ordinary and simple valves (directional switching valve, sequence valve, first and second check valves) rather than special and complicated valves.

By supplying and discharging hydraulic pressure from the hydraulic supply source to the clamp cylinder and the pressure intensifier through the hydraulic circuit, the clamp cylinder is quickly driven through the no-load stroke from the unclamping position to the clamping start position. The pressure intensifier eliminates the need to move the clamp cylinder through a no-load stroke, and allows the pressure intensifier to have a short stroke necessary to move the clamp cylinder through a no-load stroke.

Therefore, the pressure intensifier can be made compact with a short stroke, reducing the amount of hydraulic pressure required for no-load stroke movement, saving energy consumption, and increasing the movement speed of no-load stroke, making clamping more efficient. It can be done.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

A longitudinal sectional front view of the hydraulic clamp device with a pressure intensifier is shown, and FIG. 2 is a longitudinal sectional front view of the hydraulic clamp device in an operating state.

In the figure, reference numeral 1 indicates a hydraulic clamp device, and this hydraulic clamp device 1 includes a clamp cylinder 4 that fixes a mold 3 on a table 2 of a machine tool (not shown), and a pressure oil supplied to the clamp cylinder 4. It consists of a hydraulic pressure supply device 6 to control.

The clamp cylinder 4 slidably accommodates a clamp piston 7 and a pressure increase piston 8 in a cylindrical cylinder body 5, and has a lower surface 7a of the clamp piston 7.
A clamp oil chamber 9 is formed between the cylinder body 5 and the cylinder body 5, and an input oil chamber 10 is formed between the upper surface 8a of the pressure boosting piston 8 and the cylinder body 5.

The output shaft 11 of the clamp piston 7 protrudes downward from the cylinder body 5, and the nut 12 attached to the lower end is engaged with the T groove 13 of the table 2, and the mold 3 is placed on the table 2 by the lower surface 5a of the cylinder body 5. It is designed to be pressed and fixed.

The output plunger 14 of the pressure booster piston 8 has an output oil chamber hole 15 recessed in the upper end of the clamp piston 7.
It is inserted into A so that it can move forward and backward, and the output oil chamber hole 15
An output oil chamber 15 is formed in the lower part of the output plunger 14 in A, and the pressure increase piston 8 is pressed upward by a return spring 16 provided between the pressure increase piston and the clamp piston 7. .

The output oil chamber 15 connects the clamp oil chamber 9 to the pressure oil supply path 1.
The input oil chamber 10, the pressure increase piston 8, the return spring 16, and the output oil chamber 15 form a pressure intensifier 17.

Input oil chamber 10 and clamp oil chamber 9 of pressure booster 17
The hydraulic supply device 6 supplies pressure oil to the oil tank 1.
The hydraulic oil stored in the hydraulic pump 20 is pumped to the three-position directional control valve 21, and the hydraulic oil is transferred from the discharge port 22 of the directional control valve 21 to the pressure oil supply/discharge port 23 of the input oil chamber 10 of the pressure intensifier 17 and the clamp oil chamber 9. The hydraulic pressure is supplied to the hydraulic pressure supply/discharge port 24 of the hydraulic pressure supply/discharge port 24, respectively.

In the middle of the hydraulic pressure supply path 25 that communicates the discharge port 22 of the directional control valve 21 and the input oil chamber 10, a pilot circuit 26 is provided when the primary pressure supplied from the directional control valve 21 exceeds a set pressure. A sequence valve 27 is provided which opens accordingly, and
A bypass 29 provided with a check valve 28 that allows hydraulic pressure to flow out from the input oil chamber 10 is connected to the hydraulic pressure supply path 25 in parallel with the sequence valve 27 .

A hydraulic pressure supply path 30 that communicates between the discharge port 22 of the directional control valve 21 and the clamp oil chamber 9 is provided with a check valve 31 that prevents hydraulic pressure from flowing out from the clamp oil chamber 9. A hydraulic pressure return path 32 is provided which connects the hydraulic pressure supply path 30 on the side of the clamp oil chamber 9 and the directional switching valve 21.
is a port that is sealed when the directional control valve 21 is in the supply position 33, and is connected to a port that communicates with the tank 19 when the directional control valve 21 is in the discharge position 35.

The operation of the hydraulic clamp device configured as described above will be explained next.

When fixing the mold 3 to the table 2, the hydraulic directional control valve 21 is operated to the supply position 33 with the mold 3 inserted between the top surface of the table 2 and the clamp body 5 as shown in FIG. Then, hydraulic pump 2
The pressure oil fed under pressure from the directional control valve 21 is supplied to the hydraulic pressure supply paths 25 and 30.

When pressure oil is supplied to the hydraulic supply paths 25 and 30,
The check valve 31 of the hydraulic pressure supply path 30 leading to the clamp oil chamber 9 is pushed open, pressure oil is supplied to the clamp oil chamber 9, and the lower surface 5a of the cylinder body 5 is brought into contact with the upper surface 3 of the mold 3.
The cylinder body 5 is quickly lowered until it reaches the state shown in FIG. 2 where it comes into contact with point a. Thereafter, when hydraulic pressure is further supplied from the hydraulic pump 20, the pressure in the clamp oil chamber 9 and the hydraulic pressure supply paths 25, 30 becomes higher than the set pressure, and the pressure in the directional control valve 21 and the input oil chamber 10 of the pressure intensifier 17 increases. The sequence valve 27 of the hydraulic pressure supply path 25 communicating with the input oil pressure is opened by the pilot circuit 26, and pressurized oil is supplied to the input oil chamber 10.

In this way, when pressure oil is supplied to the input oil chamber 10, the pressure booster piston 8 descends, pressurizes the hydraulic oil in the output oil chamber 15 with the output plunger 14 of the pressure booster piston 8, and clamps it from the pressure oil supply path 18. The output shaft 1 of the clamp piston 7 is supplied with a large force to the oil chamber 9.
1 to firmly fix the mold 3.

Next, when releasing the clamp, the hydraulic directional control valve 21 is operated to the discharge position 34. Then, the clamp oil chamber 9 connects the hydraulic pressure supply path 30 and the hydraulic pressure return path 32.
The hydraulic oil in the clamp oil chamber 9 passes through the hydraulic pressure supply path 30, the hydraulic pressure return path 32, the directional control valve 21, and the drain oil path 38 in order, and is then connected to the hydraulic tank. 19, and the cylinder body 5 is pushed upward by the return spring 16 provided between the clamp piston 7 and the pressure increase piston 8 via the pressure increase piston 8.

After the pressure of the hydraulic oil in the clamp oil chamber 9 becomes low, the hydraulic oil in the input oil chamber 10 is connected to a check valve 28 provided in parallel with the sequence valve 27 in the hydraulic pressure supply path 25 communicating with the input oil chamber 10. , the check valve 31 provided in the hydraulic pressure supply path 30 communicating with the clamp oil chamber 9 is pushed open in order, and the directional control valve is opened through the hydraulic pressure supply path 25, the bypass path 29, the hydraulic pressure supply path 30, and the hydraulic pressure return path 32. 21 and is returned to the oil tank 19, the pressure in the output oil chamber 10 decreases, and the pressure increasing piston 8 is raised toward the unclamping side by the return spring 16.

In this way, the cylinder body 5 is raised by the return spring 16, and the lower surface 7a of the clamp piston 7 comes into contact with the bottom surface 9a of the clamp oil chamber 9.

Furthermore, when placing the mold 3 on the table 2 and aligning it, when the directional control valve 21 is operated to the auxiliary supply position 35, the pressure oil from the hydraulic pump 20 flows into the clamp oil chamber 9 through the hydraulic return path 32. The mold 3 can be temporarily fixed on the table 2 with this hydraulic pressure.

3 to 4 show different embodiments, and the one shown in FIG. 3 has an input oil chamber 10 formed laterally outward of the clamp oil chamber 9, and is arranged in the direction of operation of the hydraulic piston 8. The operating direction of the output shaft 11 of the clamp piston is perpendicular to the operating direction. With such a device, the height of the clamp device 1 can be reduced.

The one shown in FIG. 4 is a lever-type clamp in which the present invention is applied, and the force point 36 at one end of the clamp arm 35 is pressed by the output shaft 11 of the clamp oil chamber 9 communicating with the output oil chamber 15. The workpiece is clamped at the point of action 37 at the other end.
Note that the oil chamber supply/discharge port 24 may be communicated with the clamp oil chamber 9 via the output oil chamber 15.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a longitudinal sectional front view of a hydraulic clamp device with a pressure intensifier, Fig. 2 is a longitudinal sectional front view showing the operating state of the clamp cylinder, and Figs. FIG. 3 is a cross-sectional plan view of the main part, and FIG. 5 is a view corresponding to FIG. 1. 4... Clamp cylinder, 6... Hydraulic pressure supply device, 7... Piston, 8... Pressure increase piston, 9...
... Clamp oil chamber, 10 ... Input oil chamber, 14 ... Output plunger, 15 ... Output oil chamber, 16 ... Return spring, 17 ... Pressure booster, 19 ... Oil tank, 20
... Hydraulic pump, 21 ... Directional switching valve, 22 ...
Discharge port, 25...Pressure oil supply path, 27...Sequence valve, 28...Check valve, 30...Hydraulic pressure supply path, 31...Check valve, 32...Pressure oil return path, 33
...supply position, 34...discharge position.

Claims (1)

[Scope of Claim for Utility Model Registration] A hydraulic clamp device for clamping an article to be clamped, comprising: a clamp cylinder having a piston and a clamp oil chamber; a pressure increasing piston including an output plunger; and an output plunger and an output plunger for the pressure increasing piston. It includes an input oil chamber formed on the opposite side, a return spring that urges the pressure booster piston toward the input oil chamber, and an output oil chamber that communicates with the clamp oil chamber and pressurizes oil with the output plunger of the pressure booster piston. , a pressure intensifier incorporated in a housing member common to the cylinder body of the clamp cylinder, and a hydraulic circuit interposed between the clamp oil chamber, the input oil chamber, and the hydraulic pressure supply source, the hydraulic circuit having a supply position and a discharge position. a directional control valve that can be switched between the two, a first oil passage that connects the input oil chamber to the discharge port of the directional valve, and a primary pressure that is interposed in the first oil passage and is supplied from the directional valve at a set value. A sequence valve that is switched to the open position only in the above cases, a first check valve that is installed in the first oil passage in parallel with the sequence valve and allows oil pressure to flow out from the input oil chamber, and a clamp oil chamber that changes direction. A second oil passage connected to the discharge port of the valve, a second check valve that is interposed in the second oil passage and prevents oil pressure from flowing out from the clamp oil chamber, and between the clamp oil chamber and the second check valve. a third oil passage branching from the second oil passage portion and connected to a port of the directional control valve that is connected to the tank when the directional control valve is in the discharge position and sealed when the directional control valve is in the supply position; A hydraulic clamp device with a pressure intensifier, characterized in that it is equipped with a hydraulic circuit.