JPH0618751Y2 - Machine sliding surface load compensator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a load acting on a moving body in a machine having a sliding surface for slidably supporting the moving body, such as a machine tool or various measuring machines. Regardless, the present invention relates to a sliding surface load compensating device that constantly compensates a load applied to a sliding surface.

[Background technology and its problems]

A so-called static pressure sliding method and a dynamic pressure sliding method are known as methods for smoothly moving a moving body such as a table with respect to a machine base or the like.

The former hydrostatic sliding method is a method in which a fluid, for example, pressure air is supplied between the sliding surfaces of the base and the moving body to support the moving body and the total load acting on the moving body by the pressure air. Since it is a system that slides in a state that it is completely levitated from the sliding surface of the base, it can significantly reduce sliding resistance, but has the drawback of extremely low rigidity when a moving body is impacted. There is.

The latter dynamic pressure sliding method is a method of sliding while directly contacting the sliding surfaces of the base and the moving body via the lubricating oil, so that the sliding surface has the advantage of high rigidity, There is a drawback that sliding resistance increases due to an increase in the load acting on the moving body.

Therefore, as a solution to the above-mentioned drawbacks of both types,
Japanese Patent Publication No. 61-16575 and Japanese Patent Publication No. 61-3252
No. 5 publication is proposed. This is to supply pressure air between the sliding surfaces of the base and the moving body, to support the weight of the moving body and a part of the load acting on the moving body by the levitation force of the pressure air, while the rest is the base. And the moving body are supported by direct contact with each other, and the pneumatic pressure supplied to the sliding surface is adjusted by an automatic pressure control valve according to the back pressure on the sliding surface, so that the moving body responds to load fluctuations acting on the moving body. The sliding resistance of is kept constant.

However, the automatic pressure regulating valve used in this method balances the diaphragm to the neutral position by the back pressure and the compression spring or the regulated air pressure, and the displacement of the diaphragm accompanying the increase or decrease of the back pressure causes the pneumatic pressure to be supplied to the sliding surface. Since it is configured so as to squeeze, the response sensitivity to a minute back pressure change is poor. Therefore, there is a drawback that the effect is small when the load acting on the moving body is large, but the effect is small when the load is light.

[Purpose of device]

Here, the object of the present invention is to eliminate such drawbacks, to keep the rigidity constant regardless of the applied load, to constantly compensate the load applied to the sliding surface, and to keep the sliding resistance constant. An object is to provide a sliding surface load compensating device for a machine.

[Means for solving problems]

Therefore, according to the configuration of the present invention, the movable body is movably provided on the sliding surface of the machine, and the compressed air is supplied between the sliding surface of the sliding surface and the sliding surface of the moving body, and the weight and movement of the moving body are increased. A sliding surface load compensating device for a machine, wherein a part of a load acting on a body is supported by the pressure air and the rest is supported by direct contact between a sliding surface and a moving body. The back pressure detection groove and the pressure air supply groove provided on one of the sliding surfaces of the surface and the moving body, the pressure air supply source, and the force for floating the moving body by the pressure air are smaller than the weight of the moving body. A back pressure detecting air supply means for supplying the back pressure detection groove with a back pressure detection groove, and a back pressure sensor for detecting the back pressure of the back pressure detection groove as an electric signal. Pressure detection means,
The signal detected by the back pressure detecting means is used as a command signal, and the pressure air pressure adjusting means for adjusting the pressure air pressure supplied from the pressure air supply source to the pressure air supply groove according to the increase or decrease of the command signal, The pressure-air pressure adjusting means includes a base body, a supply port and an exhaust port which are opened in the base body and communicate with each other through a valve seat, a back pressure chamber communicating with the supply port, and the atmosphere. A diaphragm that separates the atmosphere communication chamber from each other, a valve that opens and closes the valve seat in conjunction with the displacement of the diaphragm, a nozzle that discharges the pressure air in the back pressure chamber to the atmosphere, and a direction that opens and closes the nozzle. A flapper provided displaceably, a pressure sensor for converting pressure air pressure from the exhaust port into an electric signal, a detection signal from this pressure sensor and a command signal from the back pressure detecting means are compared, and the pressure Sky Pressure air pressure supplied to the supply groove and a controller for displacing the flapper to meet the command signal, characterized in that.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment applied to a sliding portion between a bed and a table of a machine tool. In the figure, the table 12 sliding on the sliding surface of the bed 11 has a plurality of aa pads 13 so as to be in contact with the sliding surface of the bed 11.
A and 13B are buried. Each air pad 13A,
A compressed air supply groove 14 and a back pressure detection groove 15 are provided in 13B, respectively.

Pressure air from a pressure air supply source 21 is supplied to each back pressure detection groove 15 via a pipe 22 and a distributor 23. A throttle valve 24 and a pressure gauge 25 are attached in the middle of the pipe 22, and the pressure air pressure supplied to the back pressure detection groove 15 is adjusted by the throttle valve 24. Here, the pipe 2
2, the distributor 23, the throttle valve 24 and the pressure gauge 25,
The back pressure detection air supply means 26 is configured.

The back pressure of each back pressure detection groove 15 is detected by the pressure sensor 31 as an electric signal and then applied to the pressure / voltage converter 32. Here, the pressure sensor 31 and the pressure / voltage converter 32 constitute a back pressure detecting means 35. As shown in FIG. 2, the pressure / voltage converter 32 includes a sensor amplifier 33 that amplifies a signal from the pressure sensor 31, and a voltage / pressure conversion function of the output signal from the sensor amplifier 33 as pressure air pressure adjusting means. Output amplifier 34 for outputting to the device 41
It consists of and. Note that 34A is a zero adjustment knob and 34B is a span adjustment knob.

As shown in FIG. 3, the voltage / pressure converter 41 includes a base body 42 having a valve mechanism inside. The base 42 has a valve seat 4
3, an air supply port 44 and an exhaust port 45 which communicate with each other via an opening 3, respectively, and a back pressure chamber 47 and a passage 4 which communicate with the air supply port 44 via a passage 46 above them.
Two diaphragms 50, 51 partitioning an atmosphere communication chamber 49 communicating with the atmosphere via 8 from each other are displaceably supported. The air supply port 44 is connected to the compressed air supply source 21,
The exhaust port 45 is connected to each pressurized air supply groove 14. A valve rod 52 is integrally attached to the centers of the diaphragms 50 and 51. When the valve rod 52 is displaced downward in the drawing, the valve valve 43 for opening and closing the valve seat 43 is displaced downward against the compression spring 53, so that the valve seat 43 is opened.

Further, the back pressure chamber 47 is provided with a nozzle 55 that discharges the pressure air introduced into the back pressure chamber 47 from the air supply port 44 through the passage 46 to the atmosphere. One end is fixed to the nozzle 55, and the other end of the flapper 56 made of a piezoelectric element that is displaced in a direction of opening and closing the nozzle 55 by a signal from the controller 59 is exposed.

On the exhaust port 45 side, the pressure sensor 5 is connected via a pipe 57.
8 are provided. The pressure sensor 58 detects the output pressure of the exhaust port 45 as an electric signal, and the controller 5
Give to 9. The controller 59 compares the detection signal from the pressure sensor 58 with the command signal from the pressure / voltage converter 32, and adjusts the flapper so that the pressure air pressure supplied to the pressure air supply groove 14 matches the command signal. 56
To displace.

FIG. 4 shows the circuit configuration of the controller 59. The circuit 59 includes a sensor amplifier 62 for amplifying the signal from the pressure sensor 58, an adder 63 for obtaining a difference between the signal from the sensor amplifier 62 and the command signal from the pressure / voltage converter 32, and A characteristic compensation amplifier 64 and a preamplifier 65 connected in parallel to each other at the output terminal of the adder 63.
And an adder 66 for obtaining the difference between the outputs from these amplifiers 64 and 65, and the output of this adder 66 to the flapper 56.
And an output amplifier 67 for feeding In addition,
Reference numeral 68 is a zero adjustment knob, and 69 is a span adjustment knob.

Next, the operation of this embodiment will be described.

First, the pressure air supplied between the sliding surfaces of the bed 11 and the table 12 causes the force for floating the table 12 to be smaller than the weight of the table 12, for example, 60 to 80% of the weight of the table 12. Is supplied to the back pressure detection groove 15. When the air pressure at this time, that is, the initial air pressure is P, the air pressure P is detected as an electric signal by the pressure sensor 31, subsequently amplified by the pressure / voltage converter 32, and then given to the voltage / pressure converter 41. To be This allows the voltage /
The pressure converter 41 supplies the pressure air corresponding to the voltage from the pressure / voltage converter 32 to the pressure air supply groove 14.

Therefore, since 60 to 80% of the weight of the table 12 is supported by the compressed air and the rest is directly supported by the bed 11, the rigidity can be maintained and the sliding resistance can be reduced.

By the way, when a load is applied to the table 12, the clearance between the bed 11 and the table 12 is reduced, so that the back pressure in the back pressure detection groove 15 is equal to the surface pressure Δ corresponding to the load.
P rises. This increase ΔP is added to the initial air pressure P, converted into a voltage through the sensor 31 and the pressure / voltage converter 32, and then given to the controller 59 of the voltage / pressure converter 41 as a command signal.

Now, when the command signal to the controller 59 increases, the output of the adder 63 decreases. Then, as a result of the flapper 56 bending in the direction of closing the nozzle 55, the pressure in the back pressure chamber 47 increases. This pressure acts on the upper surface of the diaphragm 50 and pushes down the valve rod 52. Then, the valve 54 interlocked with this is pushed downward against the compression spring 53, so that the valve seat 43 is opened. As a result, the pressure of the exhaust port 45 increases. This output pressure is converted into an electric signal by the pressure sensor 58 and then fed back to the controller 59. The controller 59 compares this with a command signal and performs a correction operation until an output pressure commensurate with the command signal is obtained.

Therefore, a specific example of the actual test will be described. Here, the pressure / voltage converter 32 and the voltage / pressure converter 41 having the following specifications were used.

The pressure / voltage converter 32 (including the pressure sensor 31) input air pressure; 0~10kgf / cm ^2, the output voltage; 0 to 5VDC, the voltage / pressure transducer 41 input voltage; 0 to 5VDC, output air pressure; 0～5Kgf / cm ² , output voltage of the sensor amplifier 62; DC 5 to 6.2 V Further, the weight of the table 12 is 2500 kg.

Under these conditions, the back pressure detection groove 15 has a pressure of 1 kgf / cm ²
An output voltage of 0.5 V was obtained from the pressure / voltage converter 32 when the air pressure was supplied. At this time, the output air pressure of 1.3 kgf / cm ² was supplied from the voltage / pressure converter 41 to the pressure air supply groove 14, and a balanced state was obtained. This is the effective pressure receiving area A of the pressure air supply groove 14 is 1500 cm.
^{If 2} is set, 78% of the weight of the table 12 is supported by the levitation force of the air pressure supplied to the pressure air supply groove 14,
Is a state of being supported by direct contact between the bed 11 and the remaining ^{(1500cm 2 × 1.3kgf / cm 2} = 2500kgf
X 78%). Incidentally, the output voltage of the sensor amplifier 62 at this time is 5.3V, and the output voltage of the adder 63 is 4.8V.
(= 5.3-0.5).

In this state, when a load of 3000 kgf is placed on the table 12, the output voltage of the pressure / voltage converter 32 is 1.
Increased to 8V. By the way, since the gain of the pressure / voltage converter 32 is (change in output voltage / change in load),
It is about 0.43. As a result, the output voltage from the sensor amplifier 62 increases to 5.5V, and the voltage / pressure converter 41
To 3.3 kgf / cm ² of output air pressure from the pressure air supply groove 14
An equilibrium state was obtained when it was supplied to. That is, the load variation (3000 kgf) is the pressure increase of the air pressure supplied to the pressure air supply groove 14 (3.3 kgf / cm ² -1.3 k).
gf / cm ² = 2 kgf / cm ² ) and effective pressure receiving area A (150
It is compensated by the static pressure based on 0 cm ² × 2 kgf / cm ² = 3000 kgf), and the supporting load due to direct contact with the bed 11 is maintained constant.

This is because the command signal to the controller 59 is increased (0.5
V → 1.8 V) decreases the output voltage of the adder 63, and the flapper 56 bends in the direction of closing the nozzle 55.
This is because the pressure of the exhaust port 45 has increased. At this time, the output voltage of the adder 63 was 3.9V. This is because the back pressure in the back pressure detection groove 15 also decreases due to the increase in the pressure of the exhaust port 45, and the command signal finally becomes 1.6 V in the equilibrium state, and the output voltage of the adder 63 becomes 5.5 V-1. 6V = 3.
It is thought that it became 9V. Therefore, the back pressure detection groove 1
5, the output voltage of the adder 63 decreases (4.8V → 3.9V) in response to the increase of the back pressure detected, that is, the increase of the command signal (0.5V → 1.6V), and the pressure air Supply groove 1
The pressure and air pressure supplied to 5 increases (1.3 kgf / cm ² →
3.3kgf / cm ² ). In this way, the correction operation is performed so that the output pressure corresponds to the command signal.

Therefore, according to the present embodiment, even if the applied load changes, the load applied to the slip surface of the base 11 can be constantly compensated, so that the sliding resistance can always be kept constant. Moreover, the back pressure is detected as an electric signal, and the voltage /
Output pressure from the pressure converter 41, that is, pressure air supply groove 1
The air pressure supplied to 4 is converted into an electric signal by the pressure sensor 58, and the air pressure supplied to the pressure air supply groove 14 is adjusted by comparing these two signals, so that the response sensitivity is excellent and the sliding surface of the base 11 even under a light load. It is possible to always compensate for the load applied to.

Further, since 60 to 80% of the weight of the table 12 is supported by the compressed air and the rest is directly supported by the bed 11, the rigidity can be maintained and the sliding resistance can be reduced. Therefore, improvement in positioning accuracy and contour processing accuracy can be expected.

In the above embodiment, the pressure air supply groove 14 is provided on the table 12 side of the slip surfaces of the bed 11 and the table 12.
Further, although the back pressure detection groove 15 is provided, conversely, these grooves may be provided on the bed 11 side.

Further, the present invention is not limited to the machine tools described in the above embodiments, but can be applied to general machines having a sliding surface that slidably supports a moving body.

[Effect of device]

As described above, according to the present invention, regardless of the applied load,
It is possible to provide a sliding surface load compensating device for a machine, which is capable of constantly compensating a load applied to a sliding surface while maintaining rigidity and constantly maintaining a constant sliding resistance.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a diagram showing the entire structure, FIG. 2 is a circuit diagram showing a pressure / voltage converter, and FIG. 3 is a diagram showing a voltage / pressure converter. FIG. 4 is a circuit diagram showing the controller. 11 ... Bed, 12 ... Table, 14 ... Pressure air supply groove, 15 ... Back pressure detection groove, 21 ... Pressure air supply source, 26 ... Back pressure detection air supply means, 31 ... Pressure sensor , 35 ... Back pressure detecting means, 41 ... Voltage / pressure converter, 42 ... Base body, 43 ... Valve seat, 44 ... Air supply port, 4
5 ... Exhaust port, 47 ... Back pressure chamber, 49 ... Atmosphere communication chamber,
50, 51 ... Diaphragm, 54 ... Valve, 56 ...
… Flapper, 58 …… Pressure sensor, 59 …… Controller.

Claims (1)

[Scope of utility model registration request] 1. A movable body is provided movably with respect to a sliding surface of a machine, and compressed air is supplied between a sliding surface of the sliding surface and the sliding surface of the moving body to act on the weight of the moving body and the movable body. In a sliding surface load compensating device for a machine, a part of the load to be supported is supported by the pressure air, and the rest is supported by direct contact between the sliding surface and the moving body. The back pressure detection groove and the pressure air supply groove provided on one of the sliding surfaces of the body, the pressure air supply source, and the force for levitating the moving body by the pressure air are smaller than the weight of the moving body. Back pressure detection air supply means for supplying such pressure air pressure from the pressure air supply source to the back pressure detection groove, and back pressure detection means including a pressure sensor for detecting the back pressure of the back pressure detection groove as an electric signal. And this back pressure detection means As a command signal, and a pressure air pressure adjusting means for adjusting the pressure air pressure supplied from the pressure air supply source to the pressure air supply groove according to the increase or decrease of the command signal. Divides the base body, the air supply port and the air exhaust port which are opened in the base body and communicate with each other through the valve seat, the back pressure chamber which communicates with the air supply port, and the atmosphere communication chamber which communicates with the atmosphere. A diaphragm and a valve that opens and closes the valve seat in conjunction with the displacement of the diaphragm,
A nozzle that discharges pressure air in the back pressure chamber to the atmosphere, a flapper that is displaceable in a direction that opens and closes the nozzle, a pressure sensor that converts pressure air pressure from the exhaust port into an electric signal, and this pressure. A controller that compares the detection signal from the sensor and the command signal from the back pressure detection means, and that displaces the flapper so that the pressure air pressure supplied to the pressure air supply groove matches the command signal. A sliding surface load compensator for a machine, which is characterized by