CN113606253A

CN113606253A - Conical dynamic pressure bearing of grinding wheel spindle of asymmetric high-speed grinding machine

Info

Publication number: CN113606253A
Application number: CN202110860105.4A
Authority: CN
Inventors: 王国良
Original assignee: Shanghai Dingjiu Machine Tool Co ltd
Current assignee: Shanghai Dingjiu Machine Tool Co ltd
Priority date: 2021-07-28
Filing date: 2021-07-28
Publication date: 2021-11-05

Abstract

The invention belongs to the technical field of machinery, and particularly relates to a conical dynamic pressure bearing of a grinding wheel spindle of an asymmetric high-speed grinding machine. The invention relates to a conical dynamic pressure bearing, which comprises a front bearing, a rear bearing, an end cover and a shell; the inner walls of the front bearing and the rear bearing are both cone frustum bodies, and the front bearing and the rear bearing are asymmetric in structure, namely the two bearings have different tapers; the taper of the rear bearing is slightly larger than that of the front bearing; the inner walls of the front bearing and the rear bearing are respectively provided with 3 strip-shaped same arc-shaped oil grooves which are distributed at equal intervals; the front section and the rear section of the grinding wheel spindle of the grinding machine matched with the front bearing and the rear bearing are also asymmetric frustum bodies, and the conicity of the grinding wheel spindle is respectively consistent with that of the front bearing and the rear bearing. The conical dynamic pressure bearing designed by the invention has the advantages of large bearable load, increased rotating speed of the main shaft and increased oil wedge dynamic pressure effect, thereby increasing the bearable load.

Description

Conical dynamic pressure bearing of grinding wheel spindle of asymmetric high-speed grinding machine

Technical Field

The invention belongs to the technical field of machinery, and particularly relates to a conical dynamic pressure bearing of a grinding wheel spindle of an asymmetric high-speed grinding machine.

Background

The main shaft bearing of the grinding wheel of the grinding machine generally comprises a rolling bearing and a sliding bearing; the sliding bearings are divided into hydrostatic bearings and hydrodynamic bearings. The present invention relates only to dynamic pressure bearings. A dynamic pressure bearing for the main shaft of grinding wheel in asymmetric high-speed grinder is disclosed. High speed grinding is used herein to refer to grinding of workpieces, typically with high power and efficiency, in addition to grinding of superhard materials. The dynamic pressure sliding bearing of the grinding machine spindle is one of the earliest machine tool spindle bearings, and the dynamic pressure bearing of a movable support tilting pad invented in nine 0 five years is generally used at present, and the working principle is as follows: the lubricating liquid is brought into the movable supporting shoe block by utilizing the self rotation of the main shaft, so that the shoe block rotates on the original eccentric movable supporting point by a micro radian to form an included angle with the surface of the main shaft, an oil wedge is generated to realize a dynamic pressure working effect, and only two micro supporting loads of the main shaft on a Y axis and a Z axis are generated, namely only a radial load is generated, and no bearing force exists in the axial direction. The bearing is an incomplete main shaft bearing, the dynamic pressure effect of the structure is obvious, the working principle is simple, and the influence of the outside is small. However, the bearing needs to be additionally provided with one-dimensional constraint in the axial direction, and therefore interference which easily influences the operation of the whole bearing system is brought.

Herein, let X be the bearing axial direction, y be the bearing vertical radial direction, and Z be the bearing horizontal radial direction.

Disclosure of Invention

The invention aims to provide a conical dynamic pressure bearing of a grinding wheel spindle of an asymmetric high-speed grinding machine, which does not need axial constraint and has stable system work.

The structure of the conical dynamic pressure bearing for the grinding wheel spindle of the asymmetric high-speed grinding machine, which is provided by the invention, is shown in figures 1 and 2, and comprises the following components: the bearing comprises a front bearing 2, a rear bearing 5, an end cover 1 and a shell 3; the diameter of the bearing hole is matched with the diameter of a grinding wheel spindle of the grinding machine; the inner walls of the front bearing 2 and the rear bearing 5 are frustum bodies, and the front bearing 2 and the rear bearing 5 are asymmetric in structure, namely the two have different tapers; let the taper of the inner wall of the front bearing 2 be k1, the taper of the inner wall of the rear bearing 5 be k2, k1 be 1: 7-1: 10), k2 be 1: 5- -1: 7, i.e. k2 is slightly larger than k 1;

the taper is defined as follows: and k = (R-R) L, wherein R is the radius of the lower bottom of the frustum, R is the radius of the upper bottom of the frustum, and L is the length of a generatrix of the frustum.

In the invention, the inner walls of the front bearing 2 and the rear bearing 5 are respectively provided with 3 strip-shaped same arc-shaped oil grooves 7 which are distributed at equal intervals; namely, the inner wall of the bearing is divided into three identical circular arcs (viewed from the cross section of the shaft); moreover, the central angle corresponding to each section of inner wall arc is equal to or approximately equal to the central angle corresponding to the arc-shaped oil groove; and the generatrix of the arc-shaped oil groove is parallel to the generatrix of the frustum.

In the invention, the maximum depth of the circular arc-shaped oil groove 7 is 10-15 mm.

The front section and the rear section of the grinding wheel spindle 4 of the grinding machine matched with the front bearing 2 and the rear bearing 5 designed by the invention are also asymmetric frustum bodies, and the conicity of the grinding wheel spindle is respectively consistent with that of the front bearing 2 and the rear bearing 5;

during assembly, the front bearing 2 and the rear bearing 5 are respectively assembled to the front section and the rear section of the grinding wheel spindle, and the gap between the front section and the rear section of the spindle on the inner walls of the front bearing and the rear bearing is 50-60 mu (wire); the front bearing and the rear bearing are respectively in interference fit with the shell through the bearings and are fixed; then, end covers are respectively added at two ends of the front bearing and the rear bearing; and the grinding wheel is arranged on the main shaft at the end of the rear bearing 5.

The bearing oil cavity bearing mechanism of the conical dynamic pressure bearing of the grinding wheel spindle of the asymmetric high-speed grinding machine designed by the invention is shown in figure 3.

Before the bearing works, oil fills three oil grooves and corresponding oil chambers 8, namely the quadrangle abcd (gaps are not considered at all), and when the main shaft (in the direction of n shown in the figure) turns and starts, the oil in the oil chambers abcd is brought to the befc oil sealing surface by the main shaft. Here, the bc side in the quadrangle abcd is the boundary line of the bearing radial oil seal surface 9, the ab side is the upper arc of the oil chamber, the cd side is the lower arc of the oil chamber, and the ad side is the boundary line of the oil chamber and the oil chamber. The oil chamber is through, i.e. the bearing oil chamber has no axial oil seal surface. The rotation process of the main shaft produces the following results: namely, a step dynamic pressure oil wedge is formed, the generated dynamic pressure area 10 can bear load, the rotating speed of the main shaft is increased, the dynamic pressure effect of the oil wedge is increased, and the bearing load is increased. Here too, the oil viscosity is proportional to the load.

The working principle of the conical dynamic pressure bearing of the grinding wheel spindle of the asymmetric high-speed grinding machine designed by the invention is shown in figure 4.

When the main shaft rotates (as shown in the figure n), the oil is extruded from the oil cavity abcd surface to the oil sealing surface befc through the Y vertical radial oil sealing surface boundary line bc, wherein the be side is an upper circular arc of the oil cavity, the ef side is a boundary line of the oil groove and the oil cavity, and the fc side is a lower circular arc of the oil cavity, so that the bearing force is generated in the whole X axial width. Due to the cone, the load is decomposed into a radial component and an axial component of the bearing. The radial component is divided into a vertical component (bearing the gravity of the spindle system) and a horizontal component (bearing the cutting force of the spindle). And the axial component force is the axial stiffness of the bearing. With the axial rigidity, the bearing system can independently finish grinding the workpiece without adding X axial restraint in the axial direction, and the X axial load is changed by selecting the conical body K values of different front and rear bearings, so that the end face of the workpiece can be effectively ground, which is the fundamental difference between a conical bearing and a non-conical bearing.

The bearing system designed by the invention is a self-locking conical friction pair, and as shown in figure 1, a proper bearing X is selected for axial positioning to enable the bearing to become a non-self-locking conical bearing. In general, the X-axis component forces of the front bearing and the rear bearing are balanced with each other, and because the two ends of the dynamic pressure oil cavity are penetrated without an axial oil sealing surface, the grinding wheel spindle can rotate at a high speed, otherwise, high temperature is easily generated to influence the grinding of a workpiece. Meanwhile, the bearing is also a unidirectional rotation bearing like a movable support tilting pad.

The conical dynamic pressure bearing for the grinding wheel spindle of the asymmetric high-speed grinding machine, which is designed by the invention, has the following advantages:

(1) in 1905, the dynamic pressure sliding bearing (called three-piece bearing) of a movable supporting tilting pad is firstly appeared in the world to be excellent support for a mechanical rotating shaft at that time; such pad bearings have been used to date; because the pad only restricts the radial movement of the rotating shaft, and the axial direction needs to be additionally provided with restriction, the complexity of the mechanism is increased; the conical dynamic pressure bearing designed by the invention properly solves the problem that the axial component force generated by paired conical bearings restricts the axial movement of the main shaft without additional restriction;

(2) because the conical dynamic pressure bearing designed by the invention is of an integral structure, compared with a static pressure bearing which is of an integral structure, the contact surface between a shaft and the bearing is greatly reduced, and the high-speed rotation of the main shaft is facilitated, and the temperature is not increased much; the high-speed rotation of the main shaft brings two advantages: (1) the linear velocity of the grinding wheel is high, which is beneficial to grinding; (2) the high-speed rotation of the main shaft enhances dynamic stiffness and is also beneficial to grinding;

(3) because the dynamic pressure bearing does not need a bearing oil supply system, an oil supply system which is expensive and a cooling system for supplied oil are omitted; and the process is simple, and the equipment cost is favorably reduced.

Drawings

FIG. 1 is a schematic view of a conical dynamic pressure bearing structure of a grinding wheel spindle of an asymmetric high-speed grinding machine.

FIG. 2 is a cross-sectional view of the bearing of the present invention in YZ direction.

FIG. 3 is a cross-sectional view of the bearing of the present invention in the YZ direction showing the bearing oil cavity bearing mechanism.

Fig. 4 is a cross-sectional view of the bearing of the present invention in the YX direction, showing the working principle of the bearing.

Reference numbers in the figures: the device comprises an end cover 1, a front bearing 2, a shell 3, a grinding wheel spindle of a grinding machine 4, a rear bearing 5, a belt pulley 6, an oil groove 7, an oil cavity 8, an oil sealing surface 9 and a dynamic pressure area 10.

Detailed Description

The invention will now be further described by way of specific examples.

The structure of a conical dynamic pressure bearing of a grinding wheel spindle of a high-speed grinding machine of a certain type is shown in figures 1 and 2, and comprises: the bearing comprises a front bearing 2, a rear bearing 5, an end cover 1 and a shell 3; the front bearing 2 and the rear bearing 5 are packaged in the shell 3. Wherein, the radius of the upper bottom of the cone frustum of the front bearing 2 is 100 mm, the radius of the lower bottom is 112 mm, the length of the generatrix is 120 mm, and the taper is as follows: 1: 10. the radius of the upper bottom of the cone frustum of the rear bearing 2 is 100 mm, the radius of the lower bottom is 110 mm, the length of the generatrix is 70 mm, and the taper is as follows: 1: 7.

the bearing inner wall can have 3 equidistant distributed circular arc oil grooves 6 of the same shape, the central angle that the radian section that every oil groove is located corresponds is 60 degrees, and the central angle that all the other 3 sections of radian sections of bearing inner wall correspond is 60 degrees. The maximum depth of the circular arc-shaped oil groove 6 is 12 mm.

The middle of the grinding wheel spindle 4 of the grinding machine is a cylinder, the front side and the rear side are two cones, and the conicity of the two cones is consistent with that of the front bearing 2 and the rear bearing 5 respectively; the length of the middle cylinder is 200-250 mm; the diameter is slightly larger than the diameter of the lower bottoms of the two cones at the two sides.

The assembly is carried out according to the figure 1, and the clearance between the front bearing 2 and the rear bearing 5 and the front cone and the rear cone of the grinding wheel spindle 4 of the grinding machine is controlled to be 50-60 mu (wire). The bearing is fixed with the shell in an interference fit manner, and the two ends are treated in the same way; then, the upper end caps are installed at both ends.

The dynamic pressure bearing designed above can be assembled with the grinding wheel spindle of the grinding machine to work. The linear speed V working range of the grinding wheel of the grinding machine is as follows:

60 ^m/s ≤V ≤100 ^m/s ；

when:

V ≤80 ^m(s) working with a belt wheel;

V >80 ^mand/s, working by adopting an electric spindle.

Claims

1. The utility model provides an asymmetric high-speed grinding machine emery wheel main shaft circular cone dynamic pressure bearing which characterized in that includes: the bearing comprises a front bearing (2), a rear bearing (5), an end cover (1) and a shell (3); the diameter of the bearing hole is matched with the diameter of a grinding wheel spindle of the grinding machine; the inner walls of the front bearing (2) and the rear bearing (5) are both conical frustum bodies, and the front bearing (2) and the rear bearing (5) are asymmetric in structure, namely the conical degrees of the front bearing (2) and the rear bearing (5) are different; setting the taper of the inner wall of the front bearing (2) as k1, the taper of the inner wall of the rear bearing (5) as k2, k1 between 1:7 and-1: 10, k2 between 1: 5- -1: 7, i.e. k2 is slightly larger than k 1;

wherein the taper is defined as follows: and k = (R-R) L, wherein R is the radius of the lower bottom of the frustum, R is the radius of the upper bottom of the frustum, and L is the length of a generatrix of the frustum.

2. The conical hydrodynamic bearing as claimed in claim 1, wherein the inner walls of the front bearing (2) and the rear bearing (5) are respectively provided with 3 strip-shaped oil grooves (7) with the same circular arc shape and are distributed at equal intervals; namely, the inner wall of the bearing is divided into three identical arcs when viewed from the cross section of the shaft; moreover, the central angle corresponding to each section of inner wall arc is equal to or approximately equal to the central angle corresponding to the arc-shaped oil groove; and the generatrix of the arc-shaped oil groove is parallel to the generatrix of the frustum.

3. A conical hydrodynamic bearing according to claim 3, characterized in that the circular arc-shaped oil grooves (7) have a maximum depth of 10-15 mm.

4. A conical hydrodynamic bearing according to claim 2, characterized in that the grinding wheel spindle (4) matching the front bearing (2) and the rear bearing (5) is also provided with asymmetrical frustums in the front and rear sections and with a conicity corresponding to the conicity of the front bearing (2) and the rear bearing (5), respectively.

5. The conical dynamic pressure bearing according to claim 4, characterized in that, during assembly, the front bearing (2) and the rear bearing (5) are respectively assembled to the front and rear sections of the grinding wheel spindle (4), and the clearance between the inner walls of the front and rear bearings and the two frustum bodies of the front and rear sections of the grinding wheel spindle (4) is 50-60 μ; the front bearing and the rear bearing are respectively in interference fit with the shell through the bearings and are fixed; then, end covers are respectively added at the two ends of the front bearing and the rear bearing.