JPS6234670Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a rotary table for a precision lapping machine.

<Purpose of the invention> The purpose of the invention is to obtain a rotary table that exhibits extremely little change in attitude due to unbalanced loads acting on the rotary table and that has high rotation accuracy in a horizontal plane.

Another object of the present invention is to prevent a decrease in rigidity due to a change in bearing clearance due to deformation of a bearing metal of a hydrostatic thrust bearing that supports a rotary table.

<Prior Art> Conventionally, it is known that a rotary table is supported by a hydrostatic thrust bearing, but in many cases, a hydrostatic thrust bearing pocket is formed only on the support surface that slides into contact with the lower surface of the rotary table. In such a device, when an unbalanced load acts on the table, a floating phenomenon occurs at a point symmetrical to the point of application of the load, and there is almost no restraining force against this. In order to prevent the generation of a restraining force against this floating phenomenon, it is conceivable to provide a flange on the circumference of the rotary table and to sandwich the upper and lower surfaces of this flange portion with hydrostatic thrust bearings. The problem in this case is that the hydrostatic thrust bearing protrudes outward from the outer periphery of the rotary table, making it difficult to adopt when there are space constraints around the rotary table, and when the pressure fluid is air. Apart from this, in the case of a liquid, there is a problem in that the cutting fluid or the like supplied onto the rotary table enters the bearing part and mixes with the liquid, and it is relatively difficult to create a seal to prevent this.

Furthermore, in the configuration in which thrust bearing metals are arranged on the upper and lower surfaces of the flange, the point of application of static pressure is shifted radially inward with respect to the support point of the bearing metal, which tends to cause deformation of the bearing metal and reduce the bearing gap. There is concern that this may lead to an increase in

<Structure of the invention> The present invention provides a rotary table that solves the above-mentioned problems.The upper bearing metal, which supports the rotary shaft with static pressure in the radial direction, is sandwiched between a thrust plate integrated with the rotary shaft and a flange piston. a hydrostatic thrust bearing pocket is formed on the upper end surface of the upper bearing metal facing the lower surface of the thrust plate;
Further, a cylinder into which the piston flange is slidably fitted is bored in the lower end surface of the upper bearing metal, pressure fluid is supplied to the hydrostatic thrust bearing pocket through a restriction, and constant pressure fluid is supplied to the cylinder. It was designed to do so.

<Example> Examples thereof will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a table support body fixed to the machine base, and is provided with a shaft hole 2, a hydraulic pressure supply passage 3, and a hydraulic pressure discharge passage 4 in the vertical axis direction. A pair of bearing metals 6a and 6b, each having a plurality of hydrostatic bearing pockets 7a and 7b formed in the circumferential direction, are installed on the inner circumferential surface of the shaft hole 2, spaced apart from each other in the vertical direction, and a pulley is connected to the bearing metals by a motor (not shown). A rotary shaft 5 that is rotatably driven via a shaft 27 is supported. Further, the hydrostatic bearing pockets 7a, 7b communicate with annular grooves 8a, 8b provided on the outer peripheral surfaces of the bearing metals 6a, 6b via throttles 9a, 9b, and the annular grooves 8a, 8b are connected to hydraulic pressure supply channels. It communicates with 3. 19 is a hydraulic discharge groove.

Reference numeral 10 designates a rotary table, on the top of which a wrapping surface plate 20, for example, is placed, and the workpiece is wrapped. The bottom surface of this rotary table 10 is
It is fixed to the upper surface of a thrust plate 11 having a diameter smaller than the outer diameter of a rotary table 10 integrally formed on the upper part of the rotary shaft 5. Further, a piston flange 31 is provided at the center of the rotating shaft 5 so as to sandwich the bearing metal 6a between the slide plate 11 and the bearing metal 6a.

The upper bearing metal 6a has a bearing surface 26a (see FIG. 2) formed on its upper end surface that slides into contact with the lower surface of the thrust plate 11. A plurality of hydrostatic thrust bearing pockets 16a are formed in the circumferential direction,
The annular groove 15 communicates with each other via the aperture 17.

A cylinder inner hole 30 is concentrically formed in the lower end surface of the upper bearing metal 6a, and a piston flange 31 protruding from the center of the rotating shaft 5 is fitted into the cylinder 30. A constant pressure fluid is supplied to press the piston flange 31 downward. 18 is a hydraulic pressure discharge hole, and 24 is a hydraulic pressure discharge groove. Reference numeral 21 indicates a cutting fluid discharge hole provided near the outer periphery of the rotary table 10, and 22 indicates an outlet pipe for the cutting fluid that falls from the discharge hole 21.

Since the present invention has the above-described structure, the rotating shaft 5 is rotatably supported in the radial direction by the hydraulic pressure supplied to the hydrostatic bearing pockets 7a and 7b of the pair of upper and lower bearings 6a and 6b. do. The rotary table 10 rotated by the rotary shaft 5 also has a thrust bearing surface 26 formed on the upper bearing metal 6a that supports the lower surface of the thrust plate 11 on the lower surface thereof.
The thrust bearing is statically supported in the thrust direction by the hydraulic pressure generated in the hydrostatic thrust bearing pocket 16 formed in the thrust bearing pocket 16 . The constant pressure fluid supplied to the cylinder 30 presses the piston flange 31 downward, reducing the bearing clearance between the thrust plate 11 and the bearing surface 26, increasing bearing rigidity and reducing uneven load on the rotary table. Even in the event of an action, it becomes possible to restrain the floating phenomenon of the rotary table at a point symmetrical to the point of action.

<Effects of the Invention> According to the configuration of the present invention, a hydrostatic thrust bearing pocket is formed on the upper surface of the upper bearing metal, facing the thrust plate provided at the upper part of the rotating shaft, and a hydrostatic thrust bearing pocket is formed on the lower surface at the middle part of the rotating shaft. Since a cylinder is formed into which the piston flange is slidably fitted, the configuration of the thrust bearing can be simplified, and the static pressure acting on the bearing metal is absorbed by the table support below the static pressure support point. deformation of the bearing metal is prevented. In addition, the bearing gap is pinched by a constant downward load acting on the piston flange provided at the middle of the rotating shaft, increasing the thrust bearing rigidity and preventing posture changes due to uneven loads, resulting in a rotary table with high rotation accuracy. .

[Brief explanation of the drawing]

The drawing shows a rotary table according to the present invention, and the first
The figure is a vertical cross-sectional view taken along the line -- in FIG. 2, and FIG. 2 is a view taken along the line shown in FIG. 1. DESCRIPTION OF SYMBOLS 1... Table support, 2... Shaft hole, 3... Hydraulic pressure supply passage, 4... Hydraulic pressure discharge passage, 5... Rotating shaft, 6a... Upper bearing metal, 6b... Lower bearing metal,
7a, 7b...Static pressure pocket, 10...Rotary table, 11...Thrust plate, 16...Static pressure thrust bearing pocket, 26...Bearing surface, 30...Cylinder, 31...Piston flange.

Claims (1)

[Scope of utility model registration request] Equipped with a rotating shaft integrally formed with a thrust plate with a diameter smaller than the outer diameter of the rotating table, which is fixed to the bottom surface of the rotating table, and a plurality of hydrostatic bearing pockets in the circumferential direction on the inner peripheral surface of the shaft hole that fits into this rotating shaft. The formed pair of bearing metals are vertically spaced apart and installed on a table support, and a plurality of hydrostatic thrust bearing pockets are formed in the circumferential direction on the upper end surface of the upper bearing metal that faces the lower surface of the thrust plate. , a piston flange for sandwiching the upper bearing metal between the thrust plates is provided in the middle of the rotating shaft, and a cylinder is bored in the lower end surface of the upper bearing metal for slidably fitting the piston flange. The hydrostatic bearing pocket and the hydrostatic thrust bearing pocket are each provided with pressure fluid supply means through a throttle, and the cylinder is provided with a pressure fluid supply means for supplying a constant pressure fluid without going through a throttle. A rotary table characterized by: