A high-precision pneumatic chuck structure

Abstract

The present invention relates to a high-precision pneumatic chuck structure, which is installed on a flange of a machine tool, and includes a rotating shaft fixedly connected to the flange, a pneumatic assembly arranged at the front of the rotating shaft, a chuck assembly arranged on the pneumatic assembly, and a vent bearing arranged at the rear of the rotating shaft. The vent bearing adopts an air static pressure bearing, and a vent groove is arranged in the rotating shaft, and the vent groove connects the pneumatic assembly and the air static pressure bearing; a part of the air introduced into the air static pressure bearing forms an air film in the air static pressure bearing, and the other part enters the pneumatic assembly through the vent groove to drive the chuck assembly. Due to the homogenization effect of the gas film, the rotation accuracy can be further improved, and the influence of the shape error of the mechanical bearing on the rotation accuracy and rotation stability of the chuck is greatly reduced; at the same time, in the air static pressure bearing, since the air film is used to separate the rotating part of the chuck from the stationary part, direct contact of mechanical parts is avoided, and the friction during operation is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of machine tool chuck production and manufacturing, and in particular to a high-precision pneumatic chuck structure. Background Art

[0002] Pneumatic chuck is a mechanical device that uses the radial movement of movable jaws evenly distributed on the chuck to clamp the workpiece. It is often installed on lathes, internal and external cylindrical grinders. With the development of ultra-precision machining and manufacturing technology, many high-tech products have higher and higher requirements for the machining accuracy of ultra-precision machining machine tools. Pneumatic chucks are widely used in high-precision turning and grinding due to their high clamping efficiency, high clamping accuracy, and simple chuck structure.

[0003] The rotation of the chuck is driven by the flange connecting the workpiece spindle. The external compressed air source enters the air chamber of the chuck through the airway connector part. The airway connector is the static part. The airway connector reduces the friction between the rotating part and the static part of the chuck by using bearing technology. As a chuck directly connected to the spindle, its rotation accuracy largely determines the rotation error of the workpiece end at high speed. In addition to the machining accuracy of the chuck itself, the bearing technology used in the airway connector part also largely determines the rotation accuracy of the chuck.

[0004] Traditional contact rolling bearings are widely used in pneumatic chucks to reduce the friction between the stationary and rotating parts. Due to their own structure, it is difficult for traditional contact bearings to achieve extremely high processing accuracy, which will cause vibration during the rotation process and reduce the rotation accuracy of the chuck. Creeping will occur during low-speed operation, and during long-term high-speed rotation, the frictional heat generated by the bearing will cause thermal deformation of the chuck part, which will also reduce the rotation accuracy of the workpiece end. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a high-precision pneumatic chuck structure, which realizes high-precision rotation of the chuck with small vibration, does not cause creeping at low speed, and does not generate frictional heat at high speed.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a high-precision pneumatic chuck structure, installed on the flange of the machine tool, including a rotating shaft fixedly connected to the flange, a pneumatic component arranged at the front of the rotating shaft, a chuck component arranged on the pneumatic component and a vent bearing arranged at the rear of the rotating shaft, the vent bearing adopts an air static pressure bearing, a vent groove is arranged in the rotating shaft, the vent groove connects the pneumatic component and the air static pressure bearing; a part of the air introduced into the air static pressure bearing forms an air film in the air static pressure bearing, and the other part enters the pneumatic component through the vent groove to drive the chuck assembly.

[0007] More specifically, the air static pressure bearing comprises an air floating guide rail and an air floating bearing coaxially arranged with the air floating guide rail, and a plurality of throttle holes for axial thrust and radial support are arranged on the air floating bearing.

[0008] More specifically, the pneumatic assembly includes a pneumatic housing centered on a rotating shaft, a pneumatic piston arranged in the pneumatic housing and sleeved on the rotating shaft, a front cover arranged on the pneumatic housing, and a return spring arranged between the front cover and the pneumatic piston. An air chamber is formed between the pneumatic housing and the pneumatic piston, and the ventilation groove connects the air chamber.

[0009] More specifically, the throttling holes include a plurality of radially arranged radial throttling holes, an axial throttling hole connecting the plurality of radial throttling holes, and an annular air supply groove connecting the plurality of radial throttling holes, and an air inlet hole is arranged on the annular air supply groove.

[0010] More specifically, the annular air supply groove is an annular groove arranged on the cylindrical surface of the air bearing, and a sealing ring is arranged on the annular groove.

[0011] More specifically, a groove is provided on the inner side of the front cover, and the return spring is located in the groove.

[0012] More specifically, the rotating shaft, the air-floating guide rail and the pneumatic housing are integrally formed.

[0013] More specifically, the chuck assembly includes a slidable power wedge disposed on the front cover, a clamping claw disposed on the power wedge, and a convex wedge disposed on the pneumatic piston and cooperating with the power wedge, wherein the convex wedge extends obliquely in a direction away from the rotating shaft.

[0014] The beneficial effects of the present invention are as follows: after adopting the above structure, due to the homogenization effect of the gas film, the present invention can not only further improve the rotation accuracy compared with the pneumatic chuck using the traditional mechanical contact bearing, but also greatly reduce the influence of the shape error of the ball or roller in the mechanical bearing on the rotation accuracy and rotation stability of the chuck; at the same time, in the air static pressure bearing, since the rotating part of the chuck is separated from the stationary part by the air film, the direct contact of the mechanical parts is avoided, the friction during operation is effectively reduced, and the creeping phenomenon will not occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a cross-sectional structural schematic diagram of the present invention;

[0016] Figure 2 yes Figure 1 Schematic diagram of the enlarged structure of part A.

[0017] In the figure: 1. flange; 2. rotating shaft; 3. ventilation groove; 4. air-floating guide rail; 5. air-floating bearing; 6. pneumatic housing; 7. pneumatic piston; 8. front cover; 9. return spring; 10. air chamber; 11. power wedge; 12. claw; 13. convex wedge; 51. radial throttle hole; 52. axial throttle hole; 53. annular air supply groove; 54. air inlet hole. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with the accompanying drawings.

[0019] like Figure 1 A high-precision pneumatic chuck structure is shown, which is installed on a flange 1 of a machine tool, and includes a rotating shaft 2 fixedly connected to the flange 1, a pneumatic component arranged in the front of the rotating shaft 2, a chuck component arranged on the pneumatic component, and a vent bearing arranged in the rear of the rotating shaft 2. The vent bearing adopts an air static pressure bearing, and a vent groove 3 is arranged in the rotating shaft 2. The vent groove 3 connects the pneumatic component and the air static pressure bearing; a part of the air introduced into the air static pressure bearing forms an air film in the air static pressure bearing, and the other part enters the pneumatic component through the vent groove 3 to drive the chuck assembly; by ventilating the air static pressure bearing, the chuck assembly is adjusted and the air film is formed, thereby improving the rotation accuracy.

[0020] like Figure 2As shown, the air static pressure bearing includes an air floating guide rail 4 and an air floating bearing 5 coaxially arranged with the air floating guide rail 4. The air floating guide rail 4 is fixed on the flange 1 and rotates with the flange 1. A plurality of throttling holes for axial thrust and radial support are arranged on the air floating bearing 5. A plurality of axial throttling holes 52 are evenly opened around the axis of the air floating bearing 5 in the axial direction. In this case, the axial throttling holes 52 are arranged in 8 groups, each with 1 hole. The axial throttling holes 52 are through holes, and the openings on both sides thereof correspond to the flange 1 and the pneumatic component positions respectively. A plurality of radial throttling holes 51 are arranged in the radial direction of the air floating bearing 5. In this case, 8 groups are arranged, each with 3 holes, and they are evenly distributed. In the same radial plane, the radial throttling holes 51 are connected with the axial throttling holes 52. At the same time, in order to ensure that all radial throttling holes 51 are connected with the axial throttling holes 52, the radial throttling holes 51 are connected with the axial throttling holes 52. The holes 52 are connected, and an annular air supply groove 53 is opened on the air-floating bearing 5. The annular air supply groove 53 connects a radial throttling hole 51 in each radial plane, and at least one air inlet hole 54 is opened on the annular air supply groove 53 to realize air intake; and for the convenience of processing, the annular air supply groove 53 is arranged on the cylindrical surface of the air-floating bearing 5 to form an annular groove, and a sealing ring is installed on the annular groove to realize the function of the annular air supply groove 53; the radial throttling hole 51 is processed into a through hole, which is located on one side of the cylindrical surface of the air-floating bearing 5 and can be sealed, which is also convenient for cleaning; the gas entering from the air inlet hole 54 passes through the radial throttling hole 51 and forms an air film between the air-floating bearing 5 and the air-floating guide rail 4, and the gas passed through the axial throttling hole 52 forms an air film between the air-floating bearing 5 and the flange 1, and between the air-floating bearing 5 and the pneumatic component.

[0021] The pneumatic assembly includes a pneumatic housing 6 centered on the rotating shaft 2, a pneumatic piston 7 arranged in the pneumatic housing 6 and sleeved on the rotating shaft 2, a front cover 8 arranged on the pneumatic housing 6, and a return spring 9 arranged between the front cover 8 and the pneumatic piston 7. An air chamber 10 is formed between the pneumatic housing 6 and the pneumatic piston 7. The vent groove 3 is connected to the air chamber 10. The air chamber 10 is arranged on a side close to the flange 1. The air chamber 10 is an annular space. The vent groove 3 is provided with three vent grooves all connected to the air chamber 10. In order to facilitate the positioning of the return spring 9, the front cover 8 is provided with a return spring 9. Three grooves are arranged on the upper surface, and three reset springs 9 are fixed in the grooves one by one; when working, the air static pressure bearing is ventilated, and the gas enters the ventilation groove 3 along the throttle hole, and the ventilation groove 3 passes the gas into the air chamber 10. The air pressure in the air chamber 10 increases, so that the pneumatic piston 7 moves to the side away from the flange 1 and compresses the reset spring 9. At this time, the clamping operation of the chuck assembly is realized; when not working, the ventilation is stopped, the air pressure in the air chamber 10 is reduced, and the reset spring 9 makes the pneumatic piston 7 return to the initial position, and the loosening operation of the chuck assembly is realized.

[0022] The chuck assembly includes a slidable power wedge 11 arranged on the front cover 8, a claw 12 arranged on the power wedge 11, and a convex wedge 13 arranged on the pneumatic piston 7 and cooperating with the power wedge 11, wherein the convex wedge 13 extends obliquely in a direction away from the rotating shaft 2; the chuck assembly is arranged in three groups and is evenly distributed on the front cover 8 around the rotating shaft; when the pneumatic piston 7 drives the convex wedge 13 to approach the power wedge 11, the convex wedge 13 makes the power wedge 11 move toward the center of the rotating shaft 2, and the power wedge 11 drives the claw 12 to move toward the center of the rotating shaft 2, thereby clamping the workpiece; when the pneumatic piston 7 drives the convex wedge 13 away from the power wedge 11, the convex wedge 13 makes the power wedge 11 and the claw 12 move away from the center of the rotating shaft 2, thereby releasing the workpiece.

[0023] Based on the above structure, in order to facilitate installation, the rotating shaft 2, the air floating guide rail 4 and the pneumatic housing 6 are integrally formed. During installation, only the corresponding components need to be installed, thereby improving installation efficiency.

[0024] To sum up, for the existing pneumatic chuck, this case uses air static pressure bearings to replace the existing mechanical contact bearings. Due to the homogenization error effect of the air film, it has less vibration and higher rotation accuracy than traditional mechanical contact bearings. Under low-speed conditions, there will be no creeping phenomenon, and under high-speed conditions, there will be no frictional heat generation, which greatly increases the rotation accuracy and improves the processing accuracy.

[0025] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high-precision pneumatic chuck structure, mounted on a flange (1) of a machine tool, comprising a rotating shaft (2) fixedly connected to the flange (1), a pneumatic assembly arranged in front of the rotating shaft (2), a chuck assembly arranged on the pneumatic assembly, and a vented bearing arranged at the rear of the rotating shaft (2), characterized in that: The vented bearing adopts an air static pressure bearing, and a vent groove (3) is arranged in the rotating shaft (2), and the vent groove (3) connects the pneumatic component and the air static pressure bearing; part of the air introduced into the air static pressure bearing forms an air film in the air static pressure bearing, and the other part enters the pneumatic component through the vent groove (3) to realize the driving of the chuck component; The pneumatic assembly comprises a pneumatic housing (6) with the rotating shaft (2) as the center, a pneumatic piston (7) arranged in the pneumatic housing (6) and sleeved on the rotating shaft (2), a front cover (8) arranged on the pneumatic housing (6), and a return spring (9) arranged between the front cover (8) and the pneumatic piston (7); an air chamber (10) is formed between the pneumatic housing (6) and the pneumatic piston (7), and the vent groove (3) is connected to the air chamber (10); a groove is arranged on the inner side of the front cover (8), and the return spring (9) is located in the groove; The chuck assembly comprises a slidable power wedge (11) arranged on the front cover (8), a claw (12) arranged on the power wedge (11), and a convex wedge (13) arranged on the pneumatic piston (7) and cooperating with the power wedge (11), wherein the convex wedge (13) extends obliquely in a direction away from the rotating shaft (2).

2. The high-precision pneumatic chuck structure according to claim 1, characterized in that: The air static pressure bearing comprises an air floating guide rail (4) and an air floating bearing (5) coaxially arranged with the air floating guide rail (4), and a plurality of throttle holes for axial thrust and radial support are arranged on the air floating bearing (5).

3. The high-precision pneumatic chuck structure according to claim 1, characterized in that: The air static pressure bearing comprises an air floating guide rail (4) and an air floating bearing (5) coaxially arranged with the air floating guide rail (4), and a plurality of throttle holes for axial thrust and radial support are arranged on the air floating bearing (5).

4. The high-precision pneumatic chuck structure according to claim 2 or 3, characterized in that: The throttle holes include a plurality of radial throttle holes (51) arranged radially, an axial throttle hole (52) connected to the plurality of radial throttle holes (51), and an annular air supply groove (53) connected to the plurality of radial throttle holes (51), and an air inlet hole (54) is arranged on the annular air supply groove (53).

5. The high-precision pneumatic chuck structure according to claim 4, characterized in that: The annular air supply groove (53) is an annular groove arranged on the cylindrical surface of the air bearing (5), and a sealing ring is arranged on the annular groove.

6. The high-precision pneumatic chuck structure according to claim 4, characterized in that: The rotating shaft (2), the air-floating guide rail (4) and the pneumatic housing (6) are integrally formed.

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