JPS5922321Y2 - Pressure booster - Google Patents

Description

[Detailed description of the invention] The present invention relates to a pressure increase device for a hydraulic clamp device, etc., and in particular, when the pressure of the operated clamp is released, such as when unclamping, the oil in the operated cylinder is actively discharged. The present invention relates to a pressure increasing device.

For example, in large machine tools, hydraulic clamping devices are used to fix the table to the bed and the spindle head and cross rail to the column during machining.

This hydraulic clamp device has a large clamping force and requires a pressure higher than that of other devices in the machine, so a pressure increase device is used.

This type of pressure booster uses a pressure booster piston that integrates large and small pistons, and uses pressure oil alone or a combination of pressure oil and a spring to apply pressure force to the large piston's longitudinal movement and to the small piston side. high pressure is generated in the cylinder chamber formed at the tip of the small piston (hereinafter referred to as the high pressure cylinder chamber), and this high pressure cylinder chamber is communicated with a cylinder chamber to be operated such as a hydraulic clamp device. High pressure is applied to the operated cylinder chamber, and the operated piston engaged with the operated cylinder is moved by the forward and backward movement of the pressure increasing piston, that is, the small piston.

In addition, this type of pressure booster connects the high pressure cylinder chamber and the operated cylinder chamber to a tank via a check valve, and when the oil in the high pressure cylinder chamber and the operated cylinder chamber decreases due to oil leakage, Generally, it is constructed so that it can be replenished from a tank.

However, in this replenishment circuit, when the pressure booster piston is retracted, the oil in the operated cylinder chamber preferentially flows into the high pressure cylinder chamber, and even after the operated piston in the operated cylinder reaches its retraction limit, When it is necessary to replenish oil to the high pressure cylinder chamber, it is necessary to act to replenish oil from the tank to the high pressure cylinder chamber through the check valve.
For this reason, the cracking pressure of the check valve is determined so that the pressure drop due to flow resistance etc. from the operated cylinder chamber to the high pressure cylinder chamber is smaller than that from the tank to the high pressure cylinder chamber, and furthermore, the cracking pressure of the check valve is determined so that the pressure drop due to flow resistance etc. from the operated cylinder chamber to the high pressure cylinder chamber is smaller than that from the tank to the high pressure cylinder chamber. However, depending on usage conditions such as temperature changes and the retraction speed of the pressure booster piston, the rate of pressure drop between the two changes, and the Oil may flow into the high pressure cylinder chamber from the tank.

If this is repeated, the amount of oil present in the high-pressure cylinder chamber and the operated cylinder chamber whose outflow is prevented by the check valve gradually increases, and the amount of advance of the pressure booster piston when high pressure is generated gradually decreases. Eventually, the amount of advance becomes zero, and when detecting clamping or unclamping with a limit switch, etc., using the forward movement or compound eye of the pressure intensifier piston, it becomes impossible to detect it, and when the pressure is released, the pressure intensifier piston is almost Since the cylinder does not move backward, there is a problem that the pressure inside the operated cylinder cannot be lowered.

The present invention solves the above-mentioned problems, and even if oil flows into the high-pressure cylinder chamber from the tank during the retraction of the operated piston, the high-pressure cylinder chamber is connected to the tank near the retraction limit of the pressure booster piston. Further, the oil in the operated cylinder is discharged by the action of a return spring provided for the operated piston, so that the operated piston does not stop near the forward limit when pressure is released, and is reliably maintained over a long period of time. In addition to being easy to operate, design and manufacture are easy by eliminating design constraints caused by problems such as underpressure in the circuits connecting the operated cylinder and tank with the high-pressure cylinder chamber. Another object of the present invention is to provide a pressure booster that can achieve the above object with a simple and compact structure.

Below, a diagram showing an embodiment in which the present invention is applied to a clamp device will be described.

Reference numeral 1 denotes a pressure increasing cylinder, which has cylinder holes 2 and 3 of different sizes coaxially provided.

This pressure increase cylinder 1 has the above-mentioned large and small cylinder holes 2 and 3.
A pressure increasing piston 4 is fitted into the pressure increasing piston 4, which is integrally formed with large and small pistons 5 and 6 that are slidably engaged with each other.

In the figure, the pressure booster cylinder 1 has an open right end, and a spring receiver 7 is attached to the open end with a bolt 8, and a spring receiver 7 is formed at the tip of the small piston 6 between the spring receiver 7 and the pressure booster piston 4. A spring 9 is provided to generate an increased pressure in the high pressure cylinder chamber 15.

At the center of the right end of the pressure booster piston 4 in the figure, a rod 10 is provided concentrically with the piston, and a stepped portion 11 is provided at the tip of the rod 10.
．． 12 are provided, and detection elements 13, 14 such as limit switches for detecting pressure release and abnormal pressure conditions are provided corresponding to these stepped portions 11, 12.

The front cylinder chamber of the large piston 5, that is, the cylinder chamber on the side from which the small piston 6 protrudes (hereinafter referred to as a low pressure cylinder chamber) 16 can be selectively connected to a hydraulic power source 18 and a tank 19 via a switching valve 17. It looks like this.

The high pressure cylinder chamber 15 is connected to an operated cylinder 22 of a clamp device 21 via an oil passage 20.

Reference numeral 23 denotes an operated piston engaged with the operated cylinder 22, and an operated cylinder chamber 24 communicating with the oil passage 20 is formed between the piston 23 and the cylinder 22.

The operated cylinder 22 is attached to a bed 26 that slidably supports a table 25, while the operated piston 23
A clamp piece 28 is attached to the rod 27 for pressing and fixing the table 25 to the bed 26 by moving the rod 27 to the right in the figure (hereinafter referred to as forward movement).

Furthermore, two return springs are provided for the operated piston 23 to press it in the backward direction.

The oil passage 20 is connected to a tank 19 via a check valve 30 and a throttle 31 for increasing flow resistance, and can be refilled with oil from the tank 19 when the oil passage 20 becomes negative pressure. ing.

The inner surface of the small cylinder hole 3 of the pressure boosting cylinder 1 is closed by the small piston 6 when the pressure boosting piston 4 is near the forward position, and the pressure boosting piston 4 is at the backward limit (rightward limit in the figure). When located near the small piston 6, an oil passage 32 that separates from the tip of the small piston 6 and connects the high pressure cylinder chamber 15 to the tank 19 is opened.

In the figure, 33.34° 35 is a seal.

Next, the operation of this device will be explained.

The illustrated state shows a clamped state, and the switching valve 17 is de-energized and the low pressure cylinder chamber 16 is connected to the tank 19 as shown in the figure.
It is open to

Therefore, the pressure boosting piston 4 is pushed to the left by the spring 9,
High pressure is generated in a high pressure cylinder chamber 15 at the tip of the small piston 6.

The pressure in the high pressure cylinder chamber 15 is led to the operated cylinder chamber 24 via the oil passage 20, moves the operated piston 23 forward against the return spring 29, presses the clamp piece 28 against the tenible 25, and presses the clamp piece 28 against the table 25 is clamped to the bed 26.

At this time, the check valve 30 connected to the oil passage 20 is closed to prevent pressure oil from flowing out from the oil passage 20, and at the same time, the oil passage 32 opened on the inner surface of the small cylinder hole 3 is closed. It is closed by the small piston 6, and the high pressure cylinder chamber 15 is connected to the oil passage 32.
It is kept at high pressure because it is cut off from the air.

Next, when the switching valve 17 is energized to unclamp and the switching valve 17 is switched to the left position in the figure, pressure oil from the hydraulic source 18 is supplied to the low pressure cylinder chamber 16, and the pressure booster piston 4 is It is moved backward against the spring 9.

At this time, the pressure necessary to retreat the pressure booster piston 4 is such that the cross-sectional area of the low pressure cylinder chamber 16 is
It goes without saying that if the pressure is set to, for example, three times that of the spring 9, the pressure in the high-pressure cylinder chamber 15 generated by the spring 9 can be approximately one third.

As the pressure boosting piston 4 retreats, the small piston 6 integrated therewith retreats within the cylinder hole 3, and the pressure within the high pressure cylinder chamber 15 decreases.

With this pressure drop, the oil in the operated cylinder chamber 24 is sucked into the high-pressure cylinder chamber 15 with the help of the return spring 29, causing the operated screw 1 hen 23 to retreat, that is, to move to the left in the figure, and the clamp piece 28 Open it to unclamp it.

In this way, when the operated piston 23 reaches the retraction limit, if the pressure booster piston 4 is still in the process of retreating, the interior of the high pressure cylinder chamber 15 becomes negative pressure due to the subsequent retreat of the pressure booster piston 4. A check valve 30 connected to the oil passage 20
is opened by the negative pressure, and the tank 24 is opened through the throttle 31.
Oil is supplied to the high pressure cylinder chamber 15 from there.

In this way, normally, due to the flow path resistance caused by the cracking pressure of the check valve 30 and the throttling action of the throttle 31, the oil in the operated cylinder chamber 24 first flows into the high pressure cylinder chamber 15, and then the insufficient amount is absorbed by the Throttle 31 and check valve 30
This is due to the difference in flow path resistance between the operated cylinder chamber 24 and the high pressure cylinder chamber 15 and between the tank 24 and the high pressure cylinder chamber 15. Even if the resistance of both flow paths is set so that the latter is larger than the former by providing a throttle 31, etc., the flow path resistance will vary depending on various usage conditions such as temperature changes and the retraction speed of the pressure booster piston 4. Since the piston 23 is easily variable and unstable due to changes in 31., the piston 31. Replenishment from the tank 19 may occur via the check valve 30.

If such unnecessary replenishment is performed, the amount of oil in the high-pressure cylinder chamber 15, oil passage 20, and operated cylinder chamber 24 will increase, and even if the pressure booster piston 4 reaches its retraction limit, the operated piston 23 will not move. The retraction limit is not reached and the piston stops midway, and the amount of advance of the pressure intensifying piston 4 during re-clamping gradually decreases.

However, in this device, when the pressure booster piston 4 approaches the retraction limit position, the tip of the small piston 6 comes off the oil passage 32, opening the oil passage 32 into the high pressure cylinder chamber 15, and opening the high pressure cylinder chamber 15 with oil. It opens into tank 19 via channel 32 .

Therefore, the oil in the operated cylinder chamber 24 is removed from the oil passage 20.
, tank 1 via high pressure cylinder chamber 15 and oil passage 32
At this time, if the operated piston 23 is still in the middle of retraction, the oil in the operated cylinder chamber 24 is discharged to the tank 19 with the help of the return spring 36, and the operated piston 23 is discharged to the tank 19. reaches the retreat limit.

Therefore, even if unnecessary oil is replenished as described above, it will not accumulate, and the pressure booster piston 4 and operated screws 1 to 23 will remain in their initial state even after long-term use. It maintains the stroke and operates reliably.

For this reason, when the pressure booster piston 4 reaches its retraction limit and the stepped portion 11 of the rod 10 turns on the detection element 13, the clamp piece 28 is reliably opened, and the detection element 13 can accurately detect unclamping. It is done.

FIG. 2 shows another embodiment of the present invention, in which one end is always connected to the high pressure cylinder chamber in the small piston 6 of the pressure booster piston 4.
The small piston 6 is opened at the tip of the small piston 6 to communicate with the small cylinder hole 3, and the other end is connected to the oil passage 32 that is opened on the inner surface of the small cylinder hole 3 when the pressure booster piston 4 is located near the retraction limit.
An oil passage 36 opened on the outer peripheral surface of the oil passage 32 and 36 is provided.
The high pressure cylinder chamber 15 is opened and closed with respect to the tank 19 between the high pressure cylinder chamber 15 and the tank 19.

As described above, the specific means for opening and closing the oil passage 32 with respect to the high pressure cylinder chamber 15 in accordance with the movement of the pressure boosting piston 4 can be changed to type 4.

In the embodiment described above, the spring 9 is used as a means to press the pressure increase piston 4 forward to generate pressure increase, and the hydraulic pressure is used to retreat the pressure increase piston 4 to release the pressure increase. We have shown an example in which clamping is performed when hydraulic pressure is not applied, making it suitable for long-term clamping and allowing safe clamping even if hydraulic pressure is lost due to an unexpected accident. It goes without saying that various modifications can be made, such as moving the piston 4 forward using hydraulic pressure, moving backward using a spring, or moving forward and backward using hydraulic pressure.

As described above, according to the present invention, even if unnecessary oil is replenished from the tank to the high-pressure cylinder chamber while the operated screw is returning, the high-pressure cylinder chamber will be refilled at the retraction limit of the pressure booster piston. The oil in the operated cylinder chamber can be drained by communicating with the tank, and the oil is discharged by the return spring to almost completely return the operated piston, so the unnecessary oil replenishment accumulates and increases the pressure. There is no inconvenience such as the operated piston stopping near the forward limit when releasing, or the pressure increasing piston stopping near the backward limit when increasing the pressure, and can be operated reliably over a long period of time.

Furthermore, it is not necessary to strictly determine the relationship between the flow path resistances between the operated cylinder chamber and the tank and the high-pressure cylinder chamber, and there is an advantage that the circuit and device can be designed and manufactured easily.

Further, the device is extremely simple, does not differ much from conventional devices, can be manufactured at low cost, and has the advantage of being easily applicable to existing conventional devices.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of a pressure increasing device according to the present invention, and FIG. 2 is an explanatory diagram showing another embodiment of the present invention. 1... Pressure increase cylinder, 2... Large cylinder hole, 3... Small cylinder hole, 4... Pressure increase piston, 5...・Large piston, 6...
・Small piston, 9... Spring, 15...
High pressure cylinder chamber, 16...Low pressure cylinder chamber, 1
7...Switching valve, 18...Hydraulic power source, 19
... Tank, 21 ... Clamp device,
22...Operated cylinder, 23...Operated piston, 24...Operated cylinder chamber, 2
8... Clamp piece, 29... Return spring, 30... Check valve, 3... Throttle, 32
...Oil road.

Claims (1)

[Scope of utility model registration request] A pressure increasing cylinder having large and small cylinder holes on the same axis, a pressure increasing piston integrally formed with large and small pistons that are slidably engaged with the large and small cylinder holes, respectively, and a pressure increasing piston formed at the tip of the small piston. Pressure oil is supplied and discharged to and from an operated cylinder connected to a high-pressure cylinder chamber connected to a high-pressure cylinder chamber and a low-pressure cylinder chamber formed in at least one of the large piston. /
Or, in a pressure increasing device comprising a pressure increasing piston actuating means that presses forward or backward with the pressure oil, the small piston of the pressure increasing piston opens and closes the inner surface of the small cylinder hole of the pressure increasing cylinder in which the small piston slides. is enabled and is opened when the pressure boosting piston is located near the retraction limit to open an oil passage that communicates the high pressure cylinder chamber with the tank, and to return the operated piston engaged with the operated cylinder. A pressure increase device characterized by being provided with a return spring.