JPH08150527A - Hydraulic cylinder device for static pressure bearing - Google Patents

Abstract

PURPOSE: To drive a movable table without scoring any feed mark on a processed mirror finishing surface. CONSTITUTION: A piston rod 4 of a hydraulic cylinder 1 is coupled to a movable table 6 movably laid on a saddle 5 through the intermediary of a static pressure coupling, and static pressure pockets 9a, 9b, 10a, 10b are formed in the inner surface of a rod cover part 8 for supporting the piston rod 4, and is fed with hydraulic pressure through opposed type constant-proportional valves 7, 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic bearing hydraulic cylinder device for driving a moving table or the like in an ultra-precision machine tool.

[0002]

2. Description of the Related Art Generally, an electric servo feed device or a ball screw is used as a drive device for a moving table in a machine tool. In the field of ultra-precision machining, mirror surface machining is used. In the case of carrying out, there is a problem that the feed mark according to the command value is transferred to the machined surface, and the surface of the mirror surface machining becomes remarkably low in evaluation.

In view of the above points, the present invention has an object to provide a hydrostatic bearing hydraulic cylinder device capable of driving a moving table so that a mirror-finished surface does not have a jagged feed mark.

[0004]

According to the present invention, a piston rod of a hydraulic cylinder is connected to a movable table movably arranged in a saddle shape via a static pressure coupling, and the piston rod is supported. The present invention is characterized in that a static pressure pocket is formed on the inner surface of the rod cover supporting portion, and the pressure oil is supplied to the static pressure pocket through an opposed constant ratio valve, a fixed throttle, or a flow control valve.

Further, the present invention is characterized in that the oil tank is provided with an oil temperature control device for controlling the temperature of the pressure oil.

[0006]

The piston rod of the hydraulic cylinder is supported and held by the hydraulic pressure supplied to the static pressure pocket formed on the inner surface of the rod cover supporting portion. Therefore, the rigidity of the rod portion is increased, fluctuation does not occur during the feeding operation, and the influence of hydraulic pressure pulsation is prevented by the static pressure coupling.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is a hydraulic cylinder installed on a base 2, and a piston rod 4 integrally connected to a piston 3 slidably provided in the hydraulic cylinder 1 is provided. , Projects from the end of the hydraulic cylinder 1. The tip of the piston rod 4 is connected to a movable table 6 movably mounted on the fixed saddle 5 via a static pressure coupling 7.

By the way, a rod cover support portion 8 through which the piston rod 4 penetrates is provided on the inner peripheral surface of one end of the hydraulic cylinder 1, and a plurality of pairs of rod cover support portions 8 facing each other are provided on the inner surface thereof. Static pressure pockets 9a, 9
b, 10a, 10b are formed, and each static pressure pocket 9a,
Pressure oil of a predetermined pressure is supplied to 9b, 10a, 10b.

On the inner peripheral surface of the rod cover supporting portion 8,
Oil discharge holes 11a and 11b extending in the circumferential direction are formed on the left and right sides of the static pressure pockets 9a in the axial direction, and the oil discharge holes 11a and 11b are connected to a recovery line 13 having a recovery pump 12. In addition, the oil drain hole 11 on the outer end side
An air seal supply groove 14 extending in the circumferential direction is provided on the outer side of b.
Is provided to prevent the oil from leaking outside from the annular gap between the cylinder rod 4 and the rod cover support member 8.

FIG. 2 is a diagram showing a pressure oil supply system for the hydraulic cylinder 1 and the static pressure bearing portion. The pressure oil pumped up and pressurized by the pump 15 is shown in FIG. It is supplied to the hydraulic cylinder 1 and the piston 3 thereof is driven. A part of the pressure oil pressurized by the pump 15 is passed through the opposed constant-ratio valve 17 to the upper and lower static pressure pockets 9.
a, 9b, and is also supplied to the left and right static pressure pockets 10a, 10b via another opposed constant ratio valve 18.

Further, in the oil tank 19 for storing the oil supplied to the hydraulic cylinder 1 and the like, a heat exchanger 2 for controlling the oil temperature is provided.
0 is provided, and a cooling fluid is supplied from the cooler 21 to the oil temperature control heat exchanger 20 so that the oil temperature in the oil tank 19 becomes constant and the viscosity of the oil becomes constant. I am doing it. In the figure, reference numeral 22 is a relief valve.

Therefore, when the work W placed on the moving table 6 is processed, the pressure oil pressurized by the pump 15 is supplied to the hydraulic cylinder 1 by the switching of the switching valve 16, and the piston 3 is moved. It is moved in a predetermined direction, and the moving table 6 is moved in the left-right direction in FIG. 1 at a predetermined speed via the piston rod 4 and the static pressure coupling 7.
On the other hand, pressure oil passes through the opposed constant ratio valves 17 and 18, and the upper and lower static pressure pockets 9a and 9b and the left and right static pressure pockets 10a,
Since it is supplied to 10b, the static pressure thereof fixes and holds the intermediate portion of the piston rod 4 so that it is always on the same axis, and the rigidity of the piston rod portion is increased.

Therefore, the piston rod 4 does not sway when the piston rod 4 moves, and the pulsation of the pressure oil by the pump is eliminated by the static pressure coupling 7, and the moving table by the hydraulic feed device is removed. The desired surface can be processed with respect to the work W by the feeding of, and a mirror surface close to an ideal one can be obtained. Further, at this time, since the oil temperature in the oil tank 19 is controlled by the oil temperature control heat exchanger 20, the viscosity of the oil is kept constant, and uneven feeding due to temperature change may occur. Is reliably prevented.

Further, oil drain holes 1 are provided on both sides of the static pressure pocket.
1a and 11b are provided, the oil leaking along the piston rod 4 from the static pressure pockets 9a, 9b, 10a and 10b is captured by the oil drain holes 11a and 11b, and passes through the recovery line 13. By collecting the sealing air into the air seal supply groove 14, the oil is reliably prevented from flowing out.

Although the opposed low ratio valve is provided in the above embodiment, a fixed throttle or a flow rate adjusting valve may be provided instead.

[0017]

As described above, according to the present invention, the piston rod of the hydraulic cylinder is connected to the moving table movably arranged on the saddle via the static pressure coupling, and the rod supporting the piston rod is connected. A static pressure pocket is formed on the inner surface of the cover support, and pressure oil is supplied to the static pressure pocket via an opposed low ratio valve, a fixed throttle or a flow control valve, preventing piston rod wobbling. In addition, the effect of hydraulic pressure pulsation can be prevented, and a mirror-finished surface without a jagged feed mark on the machined surface can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a hydrostatic bearing hydraulic cylinder device of the present invention.

FIG. 2 is a pressure oil supply system diagram of the hydrostatic bearing hydraulic cylinder.

[Explanation of symbols]

 1 Hydraulic Cylinder 3 Piston 4 Piston Rod 5 Saddle 6 Moving Table 7 Static Pressure Coupling 8 Rod Cover Support 9a, 9b, 10a, 10b Static Pressure Pocket 11a, 11b Oil Drain Hole 14 Air Seal Supply Groove 16 Switching Valve 17, 18 Opposed constant ratio valve 19 Oil tank 20 Heat exchanger for oil temperature control

Claims (4)

[Claims] A piston rod of a hydraulic cylinder is connected to a moving table movably arranged on a saddle via a static pressure coupling, and a static pressure is applied to an inner surface of a rod cover supporting portion which supports the piston rod. A hydrostatic bearing hydraulic cylinder device characterized in that a pocket is formed and pressure oil is supplied to the hydrostatic pocket through an opposed type constant ratio valve. 2. The hydrostatic bearing hydraulic cylinder device according to claim 1, wherein a fixed throttle or a flow control valve is provided in the pressure oil supply line instead of the opposed constant ratio valve. 3. The hydrostatic bearing hydraulic cylinder device according to claim 1, wherein at least one oil drain hole is provided on the left and right of the hydrostatic pocket. 4. The static pressure according to claim 1, wherein the oil tank for supplying the pressure oil to the static pressure pocket is provided with an oil temperature control device for controlling the temperature of the pressure oil. Bearing hydraulic cylinder device.