JPS6142121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure increase device used as a fluid pressure source for a workpiece clamping device used in a machine tool, for example.

[Conventional technology]

Conventionally, this type of pressure intensifier was
There is one shown in Publication No. 51420.

This pressure booster has a pneumatic cylinder and a hydraulic cylinder arranged in series, and connects the large-diameter piston of the pneumatic cylinder and the small-diameter piston of the hydraulic cylinder by a rod penetrating the large-diameter piston in an oil-tight manner. The pneumatic cylinder chambers on both sides of the piston are connected to an air source via a solenoid valve and a pressure reducing valve, and the low oil pressure chamber and high oil pressure chamber on both sides of the small diameter piston are connected to a refueling tank and a clamping device through check valves. The pressure in the low hydraulic pressure chamber is set by a combination of a pneumatic piston and a pressure reducing valve for setting low pressure, or by a relief valve. Switching from low pressure to high pressure is performed by detecting the movement of the large diameter piston using two limit switches and switching the electromagnetic valve.

In this pressure booster, when pressurized air is supplied from an air source to the bottom side chamber of the pneumatic cylinder via a pressure reducing valve and a solenoid valve, the large diameter piston of the pneumatic cylinder and the small diameter piston of the hydraulic cylinder move forward as one. However, low-pressure, high-flow pressure oil determined by the ratio of the pressure-receiving area of the large-diameter piston to the pressure-receiving area of the small-diameter piston is supplied from the low oil pressure chamber to the clamp device through the check valve. Then, when the movement of the large diameter piston is detected by the limit switch and the solenoid valve is switched to supply pressurized air to the rod side chamber of the pneumatic cylinder, the large diameter piston and the small diameter piston move back together. , high pressure and small flow rate pressure oil determined by the ratio of the rod side pressure receiving area of the large diameter piston to the rod side pressure receiving area of the small diameter piston is supplied from the high hydraulic pressure chamber to the clamp device through the check valve. It's summery. Note that since the pressure in the low hydraulic pressure chamber is set by a combination of a pneumatic piston and a low pressure setting reducing valve, or by a relief valve, the pressure in the clamp device is maintained at a constant value.

[Problems to be solved by the invention] In the above conventional device, the clamping device (for example,
If the capacity of the clamp cylinder (clamp cylinder) is small, low pressure,
The pressure of the clamp device reaches the set pressure while switching from large flow rate to high pressure and small flow rate. In this case, in order to switch from low pressure to high pressure, the large-diameter piston is stroked extra until it kicks the limit switch, but most of the pressure oil in the low oil pressure chamber escapes from the relief valve etc. to the tank, causing energy loss. There was a problem.

The cause of this problem is that a limit switch detects the movement of the piston and switches from low pressure and high flow rate to high pressure and low flow rate.

[Means for solving problems]

Therefore, the present invention has been developed to change the pressure from low pressure and large flow rate to high pressure depending on the load pressure of the driven device (clamp device).
The technical challenge is to switch to a small flow rate.

The technical means to achieve this goal is to use a pneumatic cylinder section that operates by supplying and discharging pressurized air,
and a hydraulic pressure generating section disposed at a position that receives the driving force of the pneumatic cylinder section, and a hydraulic pressure generating section that generates a low pressure and large flow of hydraulic pressure in the hydraulic pressure generating section by the pressing force of the pneumatic cylinder section. In the pressure booster, the pressure increasing device includes a first hydraulic pressure generating device and a second hydraulic pressure generating device that generates high pressure and small flow rate hydraulic pressure, and an output port connected to a driven device. Between the hydraulic pressure generating device and the output port, a first connecting the pressure fluid of the first hydraulic pressure generating device to the output port of the hydraulic pressure generating section until the hydraulic pressure acting on the output port reaches a certain value. A switching valve section is provided that has a switching position and a second switching position that puts no load on the first hydraulic pressure generating device when the hydraulic pressure reaches a certain value.

[Effect]

According to this means, when the hydraulic pressure to the driven device reaches a certain value, the switching valve section unloads the first hydraulic pressure generating device that generates a low-pressure, large-flow hydraulic pressure, and the high-pressure, small-flow Since only the second hydraulic pressure generating device that generates the hydraulic pressure is connected to the output port, it is possible to switch from low pressure and large flow rate to high pressure and small flow rate regardless of the capacity of the driven device.

〔Example〕

1 and 2 showing one embodiment of the present invention will be described below.

The pneumatic cylinder section 1 is a driving force section of a hydraulic pressure generating section 2 to be described later, and includes a cylinder tube 5 having an inner hole 4 into which a piston 3 is slidably inserted, and a bolt 6 at the end of the cylinder tube 5. Rod side lid 8 that is fixed and has a supply/discharge port 7 connected to a source of pressurized air.
The bolt 6 includes a rod 9 fixed to the piston 3 and having one end extending to the hydraulic pressure generating section 2, and an opening 10 through which the rod 9 passes and opens to the atmosphere.
and an intermediate body 11 fixed to the cylinder tube 5. The piston 3 divides the inner bore 4 of the cylinder tube 5 into an air chamber 12 and an atmospheric chamber 13. The air pressure chamber 12 has an open supply/discharge port 7 and is connected to a pressure air source or the atmosphere via a switching valve (not shown). Moreover, the atmospheric chamber 13 is located at the opening 10 of the intermediate body 11.
is open and connected to the atmosphere at all times. When pressurized air flows into the pneumatic chamber 12, the piston 3 generates a downward pressing force to drive the hydraulic pressure generating section 2. Pneumatic chamber 1
2 opens to the atmosphere, the piston 3
It moves in the opposite direction to the above-mentioned direction by the pressing force of the spring 14 provided at 3.

The hydraulic pressure generating section 2 includes a liquid tank 16, a first hydraulic pressure generating device 17 that generates a low-pressure, large-flow hydraulic pressure, and a second hydraulic pressure generating device 1 that generates a high-pressure, small-flow hydraulic pressure.
8 and more. The liquid tank 16 is the intermediate body 11
A cylinder tube 21 having an inner hole 21a is fixed with a bolt 6 between the cylinder tube 21 and the end cover 20 in which the output port 19 connected to the driven device opens, and a liquid is stored in the inner hole 21a. . The first hydraulic pressure generating device 17 is fixed together with the cylinder tube 21 between the intermediate body 11 and the end cap 20, and a large diameter plunger 22 that penetrates the intermediate body 11 and is connected to the rod 9 of the piston 3. It is formed from an intermediate sleeve 24 having an inner hole 23 into which the plunger 22 is slidably inserted. The intermediate sleeve 24 defines within its bore 23 a pressure chamber 26 which is connected via a passage 27 in the end cap 20 to the switching valve 15, which is shown in detail in FIG. This pressure chamber 26 is connected to the inner bore 21 of the cylinder tube 21 of the liquid tank 16 through the mouth 25 of the intermediate sleeve 24 when the piston 3 is at its uppermost position.
The liquid stored in a is designed to flow in.
The second hydraulic pressure generating device 18 includes a small-diameter plunger 31 attached to an annular foot 28 provided at the lower end of the large-diameter plunger 22 with a pin 29 with a gap 30 in between.
An end portion 34 having an inner hole 33 of a small diameter plunger 31 is slidably fitted into an inner hole 32 formed in the end cover 20 and in which the output port 19 opens. Pressure chamber 35
is connected to the output port 19 and, when the piston 3 is at the upper end position, to the pressure chamber 26 via the port 36 and the inner hole 33, and the passage 27 is also connected to the switching valve 1.
5. The opening 25 of the intermediate sleeve 24 and the opening 36 of the small diameter plunger have a positional relationship such that they open and close almost simultaneously.

Next, the switching valve 15 is connected to the second
Let's talk about the diagram.

The switching valve 15 includes a valve body 39 having an inner hole 38 into which a spool valve 37 is slidably inserted, and a pilot piston 40 that presses the spool valve 37 when the pilot piston 40 slides under the action of hydraulic pressure within the pressure chamber 35. A pilot valve body 42 having an inner hole 41 that is movably inserted is fixed to the valve body 39 with a plurality of bolts 43. The inner hole 38 into which the spool valve 37 is slidably fitted includes a passage 45 communicating with the liquid tank 16 via a passage 44 of the end cover 20, a passage 46 connected to the passage 27, and a passage 48 of the end cover 20. The passages 47 communicating with the pressure chambers 35 are respectively opened. The spool valve 37 is
Land portions 49 and 5 slidably fit into the inner hole 38
0, and an annular groove 51 formed between the land portions 49 and 50. And this spool valve 37
connects passages 46 and 47 when in the position shown, and connects passages 46 and 45 when moved to the right from the position shown. A spring chamber 52 is formed at the right end of the spool valve 37.
A pilot piston 40 is in contact with a spring 53 that can be adjusted by a pressure regulating screw 54 provided at the right end of the piston 40 , and a pilot piston 40 that communicates with the passage 48 via a passage 55 and constantly receives the hydraulic pressure in the pressure chamber 35 is in contact with the spring 53 . are in contact with each other. The screw 56 presses the pilot piston 40 and the spool valve 37 through the intermediate block 56a inserted into the inner hole 41, thereby opening the passage 46,
This is a screw that adjusts the amount of aperture between 47 and 47. A passage 58 provided in the center of the spool valve 37 opens to the abutting surface of the pilot piston 40 and the spool valve 37 and also opens to the spring chamber 52. This spring chamber 52 opens to the passage 45 via a passage 59. The spool valve 37 is pressed by a spring 53 and the pilot piston 40 at both ends thereof, and when the pressing force of the pilot piston 40 exceeds the pressing force of the spring 53, it moves to the right. That is, when the spool valve 37 is in the illustrated position, it is in the first switching position where the hydraulic pressure in the pressure chamber 26 flows into the discharge port 19, and the hydraulic pressure in the discharge port 19 flows into the pilot piston 40.
When the spool valve 37 moves to the right, it becomes the second switching position where the pressure liquid in the pressure chamber 26 flows into the liquid tank 16. The check valve 57 is connected to the passage 46
The annular groove 51 is provided between the passage 45 and the annular groove 51 communicating with the passage 45 to prevent cavitation of the first hydraulic pressure generating device 17 from occurring. Also, spool valve 3
The land portion 49 of No. 7 adjusts the amount of restriction between the passages 46 and 47 by adjusting the screw 56. By changing this throttle amount, the driving speed of the driven device connected to the output port 19 is adjusted.

The operation of this embodiment will be described below.

In the state shown in Fig. 1 with the supply/discharge port 7 open to the atmosphere,
The switching valve 15 is also in the state shown in FIG. When pressurized air is supplied to the supply/discharge port 7, the piston 3
It receives air pressure on its upper surface and begins to move downward against the pressing force of the spring 14. Due to the downward movement of piston 3,
Both the large-diameter plunger 22 and the small-diameter plunger 31 begin to move downward, and the ports 25 and 36 are connected to the hydraulic tank 1.
6 and the pressure chambers 26, 35 are cut off almost simultaneously. As the piston 3 moves downward, the pressure chamber 2
The liquid in 6 and 35 is transferred to the large diameter plunger 2, respectively.
2. Receives the pressing force of the small diameter plunger 31. The liquid in the pressure chamber 26 is discharged from the discharge port 19 via the pressure chamber 35 via the passages 27 and 46, the annular groove 51 of the spool valve 37, and the passages 47 and 48. At the same time, the liquid in the pressure chamber 35 is also discharged from the discharge port 19 under the pressure of the small-diameter plunger 31 . Discharge port 19
The hydraulic pressure increases according to the load of the driven device.
This hydraulic pressure acts on the pilot piston 40 through the passage 55 and pushes the spool valve 37 to the right. When the pressing force of the pilot piston 40 exceeds the pressing force of the spring 53, the spool valve 37 moves to the right to connect the passages 46 and 45, and the passage 4
Cut between 6 and 47. For this reason, pressure chamber 2
6 is connected to the liquid tank 1 via the passage 27 and the passage 44.
6 and enters a no-load state. In other words, the first hydraulic pressure generating device 17 is in a no-load operation. Therefore, the pressing force of the piston 3 acts only on the plunger 31, and the pressure chamber 35 supplies high pressure liquid to the discharge port 19.

Next, when the supply/discharge port 7 is released to the atmosphere, the piston 3
is moved upward by the pressing force of the spring 14. At this time, the load acting on the discharge port 19 is close to no load, so the spool valve 37 is moved by the spring 53.
The liquid of the driven device, which flows into the pressure chamber 35 through the discharge port 19, flows into the pressure chamber 26 through the passages 48, 46, and 27. If the liquid in the driven device runs out by the time the piston 3 reaches the position shown in FIG.
7. Flows into the pressure chamber 26 via the passage 27. Therefore, even if the liquid decreases due to liquid leakage when the driven device is driven, the liquid is replenished from the liquid tank 16, so cavitation does not occur in the pressure chamber 26. When the piston 3 returns to the illustrated position, the liquid tank 16 and the pressure chambers 26, 35 are connected via the ports 25, 36. In the above operation, by adjusting the screw 56, the passages 46 and 47 are
If the amount of throttle between the two is increased, the drive speed of the driven device becomes low, and if the amount of throttle is decreased, the drive speed of the driven device becomes high.

[Effects of the Invention] According to this invention having the above-mentioned structural effects,
Since the low-pressure side hydraulic pressure generator is set to no load according to the load pressure of the driven device, it is possible to switch from low pressure and large flow rate to high pressure and small flow rate regardless of the capacity of the driven device. Therefore, there is no energy loss caused by the capacity of the clamping device that clamps the workpiece of the machine tool, and no time lag occurs in the clamping time of the workpiece.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment according to the present invention;
FIG. 2 is a sectional view taken along the line AA in FIG. 1. 1...Pneumatic cylinder section, 2...Liquid pressure generation section, 3
... Piston, 7 ... Supply and discharge port, 10 ... Port, 11
...Intermediate, 15...Switching valve, 16...Liquid tank, 17...First hydraulic pressure generator, 18...Second hydraulic pressure generator, 22...Large diameter plunger, 24...
...Intermediate sleeve, 26, 35...Pressure chamber, 31...
...Small diameter plunger, 37...Spool valve.

Claims (1)

[Claims] 1 Consists of a pneumatic cylinder section that operates by supplying and discharging pressurized air, and a hydraulic pressure generating section disposed at a position that receives the driving force of this pneumatic cylinder section, and a pneumatic cylinder is attached to the hydraulic pressure generating section. A first hydraulic pressure generating device that generates a low-pressure, large-flow hydraulic pressure by the pressing force of the part, and a second hydraulic pressure generating device that generates a high-pressure, small-flow hydraulic pressure, and an output port connected to a driven device. In the pressure booster, the first hydraulic pressure generator is connected between the first hydraulic pressure generating device and the output port of the hydraulic pressure generating section until the hydraulic pressure acting on the output port reaches a certain value. A first connecting the pressure fluid of the device to the output port of the fluid pressure generating section.
A pressure booster comprising a switching valve portion having a switching position and a second switching position that places no load on the first hydraulic pressure generating device when the hydraulic pressure reaches a certain value.