JPS60157513A - Hydraulic bearing device - Google Patents

Abstract

PURPOSE:To enable to perform stabilized bearing control, by providing a magnetic field generating device in a bearing gap by mixing a magnetized fluid with a pressurizing working fluid, in a device supporting a movable body by supplying the pressurizing working fluid in the bearing gap supporting the movable body. CONSTITUTION:A cylinder component 2 forming a bearing gap in opposition to a spindle 1 is provided with a plurality of pieces of nozzles 3a-3c and time-division change-over supply of a working fluid in a tank 7 is performed to each of the nozzles 3a-3c by a pump 6 through a change-over valve 4. A magnetized fluid is made to mix with the working fluid in the tank 7 while its fluidity, viscosity and pressure resistance are made controllable through action of the magnetic field. Magnetic field forming coils 8a-8c are provided in a corresponding state to each of the nozzles 3a-3c, and the formed magnetized field is made to act upon the bearing gap. Then each of the coils 8a-8c are controlled by a controller 10 based on a detecting signal of a detector 9 detecting a position and an inclination of the spindle 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid bearing device for movably and accurately supporting a movable body such as a spindle of a machine tool.

Conventional fluid bearings use oil or the like as a working fluid, which is supplied under pressure to a gap that movably supports a movable body, and is controlled by the supplied pressure. There is a limit to the responsiveness of this hydraulic fluid pressure control method, and a highly pressurized, V*4P, 1lf5, wide and expensive body control device is required.

The present invention was proposed to improve these points,
The present invention is characterized in that a magnetic field generator is provided which uses a mixture of hydraulic fluid and a magnetic fluid and applies a magnetic field to a bearing gap to which the mixed hydraulic fluid is supplied.

The present invention will be explained below with reference to the drawings of one embodiment.

1 is a spindle of a mechanical device that moves left and right in the figure, 2
3a, 3b, and 3C are cylinder members that face the spindle 1 and form a gap that acts as a fluid bearing, and 3a, 3b, and 3C are hydraulic fluid jet supply nozzles distributed in the length direction of the gap, and the hydraulic fluid is supplied by the switching pulp 4. Provides time-division switching supply. Reference numeral 5 represents a rotary motor that selectively operates the switching valve 4 over time, and 6 represents a hydraulic fluid supply pump that circulates and supplies the fluid stored in the tank 7.

A magnetic fluid is mixed in the hydraulic fluid in the tank, and due to the action of the magnetic field, a field due to fluidity, viscosity, pressure resistance, etc. acts on the bearing gap at each nozzle position.

9 is a detector for detecting the position, inclination, etc. of the spindle 1; 10;
The magnetic field coil 8a18b1 is activated by the detection signal of the detector 9.
8c, and also controls the pump 6 and motor 5.

The magnetic fluid to be mixed with the working fluid supplied into the tank 7 has a volume ratio of about 0.1 to 30%. This working fluid is supplied under pressure from the pump 6 and diverted to the bearing gap by the switching valve 4.

The switching speed is controlled by the motor 5 so that the spindle 1 is balanced and moves smoothly. each nozzle 3a by switching the switching valve 4.

The flow rates divided into 3b13c can be made equal to each other or can be changed by controlling the valve switching time.
Controlling only the jetting supply of the hydraulic fluid has poor responsiveness. However, since the hydraulic fluid contains a magnetic fluid, the viscosity and pressure resistance can be easily controlled by the action of a magnetic field. Each magnetic field forming coil 8 is sent from the control device 10 by the detection by the detector 9.
Controls a, 8b, and 8c. For example, by increasing the excitation of the coil 8a, it is possible to increase the liquid pressure in the bearing gap part ejected from the nozzle 3a, and by controlling the excitation of the other coil 8C to be weak, the liquid pressure in the nozzle 3C part can be weakened. Normally, the working magnetic field is controlled by a coil, for example, by mixing 11% magnetic fluid with silicone working fluid and applying 10G.
It can change up to ~800G, and the response can be increased to about four times that of the conventional one.

Also, by always applying at least the lowest level of magnetic field using the coil, leakage of hydraulic oil can be halved compared to when no magnetic field is applied. Each coil 8a,
The magnetic fields 8b and 8c are controlled so that the spindle 1 is balanced and constant in the axial direction by detection by the detector 9. When it becomes constant, the pump 6 can also be stopped.

As described above, the present invention mixes a magnetic fluid into the working fluid that is jetted into the bearing gap, and controls the bearing gap by applying a magnetic field, which improves the response speed and provides stable control. can do. Furthermore, solid contact in the bearing gap can be prevented by the magnetic field solidification and pressure increasing effect of the magnetic fluid, and the coefficient of friction can be significantly reduced, reducing stick-skip and allowing smooth movement.

Further, the quadruple load can be increased by the pressure increasing effect due to the magnetization of the magnetic fluid, the range of variation can be expanded, and the working fluid control device can be configured in a compact size.

Furthermore, leakage and consumption of the working fluid can be reduced by the magnetic field action.

Due to such improved characteristics, the present invention is particularly effective when used as a discharge gap control device for an electric discharge machine, and stable servo control can be performed. For example, under the conditions of electrical discharge machining of SKD material with a CU electrode to a machined surface roughness of 5μRmax, 11% magnetic fluid is mixed with silicone hydraulic oil, and the working magnetic field is increased to 10%.
When the servo device was operated under control within a variation range of ~800G, the servo became stable and machining was extremely stable, with a machining speed of approximately 0.011 gr/min. For comparison, the machining speed is 0,0032 when the working magnetic field is turned off.
gr/man, confirming the effectiveness of the stability control.

In addition, ttII can be used in various mechanical devices other than electrical discharge machines.
III17 One bottle on the shelf.

[Brief explanation of the drawing]

The drawing is a cross-sectional configuration diagram of an apparatus according to an embodiment of the present invention. 1... Spindle 2... Cylinder members 3a, 3b13c... Nozzle 4...
......Switching valve 6...Pump 8a, 8b, 8c...Magnetic field coil 9
......Detector 10...Control device patent applicant

Claims (1)

[Claims] In a fluid bearing that supports a movable body by supplying a pressurized hydraulic fluid to a bearing gap that movably supports a movable body, a magnetic field that mixes a magnetic fluid with the hydraulic fluid and applies a magnetic field to the gap that supplies the hydraulic fluid. A fluid bearing device characterized by being provided with a generator.