Complex curved surface force-controlled grinding and polishing device for multi-axis numerical control machine tool

Abstract

The present invention relates to the technical field of machine tool grinding and polishing. Disclosed is a complex curved surface force-controlled grinding and polishing device for a multi-axis numerical control machine tool. The device consists of five parts, i.e., a mounting component, a rotational motion transmission component, an active force control component, a force sensor, and a metal housing. The present invention is mounted at the front end of a spindle of a numerical control machine tool, and while the rotational motion transmission component transmits the torque and rotational motion of the spindle of the machine tool to a grinding and polishing tool, the active force control component comprising a voice coil motor and the force sensor accurately and actively controls a grinding and polishing contact force during grinding and polishing machining, thereby ensuring the consistency and uniformity of the surface quality in the multi-axis numerical control grinding and polishing process for complex curved surfaces.

Description

A force-controlled grinding and polishing device for complex curved surfaces used in multi-axis CNC machine tools Technical Field

[0001] The invention belongs to the technical field of machine tool grinding and polishing, and relates to a force-controlled grinding and polishing device for complex curved surfaces of multi-axis CNC machine tools. Background Art

[0002] Complex curved surface parts have been widely used in aerospace, automobile, shipbuilding, energy and other fields, and grinding and polishing is an important finishing process that affects whether complex curved surface parts can work properly. At present, the grinding and polishing methods for complex curved surfaces mostly use multi-axis machine tools for CNC grinding and polishing. Multi-axis CNC machine tools have the characteristics of strong processing posture adjustment capabilities and high processing efficiency. They can complete the entire process from milling to grinding and polishing of complex curved surface parts in one clamping. Since the curvature radius of complex curved surfaces will change, it is difficult for grinding and polishing tools to match the complex curved surface profile. Grinding and polishing tools not only have sufficiently high rigidity and hardness to ensure the material removal rate, but also need to have a certain degree of flexibility to ensure that their surface errors are not copied to the workpiece surface. The most important process parameter that affects the surface quality error caused by the surface error of the grinding and polishing tool is the contact force between the grinding and polishing tool and the workpiece surface during the grinding and polishing process.

[0003] Currently, most grinding and polishing devices used for multi-axis CNC machine tools utilize flexible tools or toolholders for passive force-controlled grinding and polishing. For example, the patent "A Flexible Chuck for Automatic Polishing Machines, CN219504504U" proposes a flexible chuck that uses a spring as an axial floating mechanism. The spring's rebound force provides relatively stable pressure, allowing the wool felt grinding head to adaptively press down to the processing position. The patent "A Multi-Directional Floating Grinding Method and Device, CN 115431139 A" utilizes a spring and belt drive to achieve multi-directional floating of the polishing wheel. The grinding contact force is adjusted by adjusting the force of the floating element. It should be noted that the passive force control achieved by this flexible structure makes it difficult to achieve precise contact force control during machining. The surface errors of the grinding and polishing tool, combined with the influence of the coordinated motion errors of the multi-axis CNC machine tool, can easily lead to over- or under-polishing of localized areas, thus affecting the surface quality of the part. In summary, there is still a need for the development of devices for multi-axis CNC machine tools that can achieve active and precise contact force control. Technical Solutions

[0004] In response to the above-mentioned problems, the present invention proposes a force-controlled grinding and polishing device for complex curved surfaces of a multi-axis CNC machine tool.

[0005] The technical solution of the present invention:

[0006] A complex curved surface force-controlled grinding and polishing device for multi-axis CNC machine tools mainly consists of four parts: a mounting assembly 1, a metal shell 2, a rotary motion transmission assembly 3, and an active force control assembly 4;

[0007] The mounting assembly 1 is installed in conjunction with the outer flange of the machine tool spindle, and is used to connect the complex surface force-controlled grinding and polishing device to the machine tool spindle, thereby realizing rapid installation and disassembly of the device; the metal shell 2 protects the active force control assembly and the rotary motion assembly from liquid and electromagnetic interference, and does not have other features that may cause interference with the workpiece during the grinding and polishing process; the upper end of the rotary motion transmission assembly 3 is connected to the machine tool spindle through the tool holder 5, and the lower end realizes grinding and polishing through the grinding and polishing tool 9; the upper end of the active force control assembly 4 is connected to the mounting assembly 1, and the rotary ball spline 7 in the rotary motion transmission assembly 3 at the lower end is used to control the contact force between the grinding and polishing tool 9 at the end of the device and the workpiece.

[0008] The rotary motion transmission assembly 3 includes a tool handle 5, a transmission shaft 6, a rotary ball spline 7, a connecting flange 8, and a grinding and polishing tool 9; the central spline shaft of the rotary ball spline 7 is connected to the transmission shaft 6, and the lower end of the inner ring of the rotary ball spline 7 is connected to the grinding and polishing tool 9 through the connecting flange 8. As a structure for transmitting rotary motion, the upper end of the outer ring of the rotary ball spline 7 is connected to the active force control assembly 4, and then the coupling of the axial motion of the outer ring and the rotational motion of the inner ring on the grinding and polishing tool 9 is realized through the rotary ball spline 7; the grinding and polishing tool 9 is made of flexible material, and the active force control effect of the contact force is more stable by realizing flexible contact between the device and the workpiece. The grinding and polishing tool 9 is mounted on the lower end of the connecting flange 8 through a thread, which makes it easy to replace grinding and polishing consumables.

[0009] The active force control component 4 includes a stator flange 10, a linear bearing 11, a voice coil motor 12, a spring 13, a linear encoder 14, a mover flange 15, a force sensor 16 and a spline sleeve 17; the voice coil motor 12 is installed between the stator flange 10 and the mover flange 15 along the axial direction of the transmission shaft 6, and the voice coil motor 12 applies thrust along the axial direction of the transmission shaft 6 and generates motion; the linear bearing 11, the spring 13 and the linear encoder 14 are installed between the stator flange 10 and the mover flange 15 along the axial direction of the transmission shaft 6; the linear bearing 11 limits the radial displacement of the active force control component 4 to realize the axial guiding function; the spring 13 is used to balance the gravity at the lower end of the active force control component 4, and the linear encoder 14 is used to collect the axial displacement generated by the voice coil motor 12; the force sensor 16 is installed at the lower end of the mover flange 15 and is connected to the rotary motion transmission component 3 through the spline sleeve 17, which is used to measure the axial force value generated by the voice coil motor 12.

[0010] The mounting assembly 1 can integrate the power supply and signal circuit quick connection plugs required by the complex surface force-controlled grinding and polishing device.

[0011] The tool handle 5 uses a standard tool handle structure, and the tool handle 5 can be replaced to make the device adaptable to machine tools with different spindle structures.

[0012] The voice coil motor 12 adopts a hollow structure, so that the transmission shaft 6 passes through the axis of the voice coil motor 12, thereby making the axial force distribution more uniform.

[0013] The linear bearings 11 and springs 13 are arranged in parallel and evenly distributed in multiple groups, so that the structure of the active force control assembly 4 is more stable.

[0014] The force sensor 16 is a ring-shaped force sensor or a plurality of force sensors evenly distributed, so that the axial force measurement is more accurate.

[0015] The inclination information of the machine tool or the inclination sensor is collected, and gravity compensation is performed on the force value measured by the force sensor 16 in a working posture with an inclination.

[0016] The spring 13 can be a thrust spring to assist the voice coil motor 12 in applying thrust to meet a greater grinding and polishing contact force requirement.

[0017] The grinding and polishing tool 9 can be made of different materials such as sponge disk, wool disk, rubber disk, etc. to meet different process requirements. Beneficial effects

[0018] (1) The complex curved surface force-controlled grinding and polishing device of the present invention realizes the active control of contact force during the complex curved surface grinding and polishing process of a multi-axis CNC machine tool, and optimizes the consistency and uniformity of the surface quality of the complex curved surface grinding and polishing process.

[0019] (2) The complex curved surface force-controlled grinding and polishing device of the present invention can be easily installed on multi-axis CNC machine tools with different structures and is convenient and versatile for various working scenarios.

[0020] (3) The complex curved surface force-controlled grinding and polishing device of the present invention can easily realize variable contact force control according to different grinding and polishing contact force requirements, and is easy to replace grinding and polishing tools and consumables, and is universally applicable to different grinding and polishing process requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic structural diagram of an embodiment of the present invention.

[0022] FIG2 is a schematic cross-sectional view of the structure of an embodiment of the present invention.

[0023] FIG3 is a schematic structural diagram of a rotary motion transmission assembly in one embodiment of the present invention.

[0024] FIG4 is a schematic structural diagram of an active power control assembly in one embodiment of the present invention.

[0025] In the figure: 1-mounting assembly; 2-metal housing; 3-rotational motion transmission assembly; 4-active force control assembly; 5-tool handle; 6-drive shaft; 7-rotary ball spline; 8-connecting flange; 9-grinding and polishing tool; 10-stator flange; 11-linear bearing; 12-voice coil motor; 13-spring; 14-linear encoder; 15-motor flange; 16-force sensor; 17-spline sleeve. Modes for Carrying Out the Invention

[0026] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0027] Referring to Figures 1-4, a force-controlled grinding and polishing device for complex curved surfaces used in multi-axis CNC machine tools consists primarily of a mounting assembly 1, a metal housing 2, a rotary motion transmission assembly 3, and an active force control assembly 4. The rotary motion transmission assembly 3 includes a tool holder 5, a drive shaft 6, a rotary ball spline 7, a connecting flange 8, and a grinding and polishing tool 9. The active force control assembly 4 comprises a stator flange 10, a linear bearing 11, a voice coil motor 12, a spring 13, a linear encoder 14, a mover flange 15, a force sensor 16, and a spline sleeve 17.

[0028] In this example, the mounting assembly 1 uses a sleeve structure to connect to the outer flange of the machine tool spindle, and the stator flange is installed at the lower end of the mounting assembly 1. The voice coil motor 12 is installed between the stator flange 10 and the rotor flange 15 to apply axial thrust and displacement. Three linear bearings 11 and a spring 13 of the same specifications are installed at their upper ends on the stator flange 10 and their lower ends on the rotor flange 15. The linear bearings 11 provide support and guidance, and the springs 13 assist the axial movement of the voice coil motor 12. A linear encoder 14 is installed between the stator flange 10 and the rotor flange 15 to measure and provide feedback on the real-time axial position of the voice coil motor 12. The force sensor 16 uses three evenly distributed unidirectional force sensors installed between the rotor flange 15 and the spline sleeve 17. It calculates the axial resultant force through analog circuit summation to measure and provide feedback on the real-time axial thrust of the voice coil motor 12. A spline sleeve 17 is installed at the lower end of the force sensor to connect the active force control assembly 4 to the rotary ball spline 7 in the rotary motion transmission assembly 3.

[0029] In this example, the tool holder 5 is installed on the machine tool spindle using a BT40 tool holder. The upper end of the transmission shaft 6 is connected to the tool holder 5, and the lower end is connected to the rotary ball spline 7. It passes through the center hole of the voice coil motor 12 and is used to transmit the rotational motion power of the machine tool spindle received by the tool holder 5 at the upper end of the device to the rotary ball spline at the lower end; the center spline shaft of the rotary ball spline 7 is connected to the transmission shaft 6 for receiving the rotational motion power, the outer ring is connected to the spline sleeve 17 for receiving the axial thrust generated by the active force control component 4, and the lower end is connected to the flange 8 for coupling the axial thrust and rotational motion power and transmitting them to the grinding and polishing tool 9; the grinding and polishing tool 9 is installed at the lowest end of the device and adopts a flexible sponge disc structure to achieve flexible contact during the grinding and polishing process, reduce vibration during the grinding and polishing process, and enable the device to achieve better force control effect.

[0030] In this example, the rotary motion transmission assembly 3 is used to transmit the rotary power of the machine tool spindle to the end of the device. The upper end tool holder 5 is connected to the machine tool spindle, and the rotary motion and torque generated by the spindle are transmitted to the grinding and polishing tool 9 at the end of the device through the transmission shaft 6, the rotary ball spline 7, and the connecting flange 8 in sequence, and act on the workpiece; the upper end of the active force control assembly is connected to the mounting assembly 1, and the axial thrust and displacement are generated by the voice coil motor 12, and are transmitted to the rotary ball spline 7 through the mover flange 15, the force sensor 16, and the spline sleeve 17 in sequence, and then the axial thrust and displacement are applied to the grinding and polishing tool 9 through the connecting flange 8; the rotary ball spline 7 serves as the connecting structure between the active force control assembly 4 and the rotary motion transmission assembly 3, completing the coupling between rotary motion and axial movement, as well as the coupling between torque and thrust; by performing gravity compensation calculation on the axial force value collected by the force sensor 16, the closed-loop control of the voice coil motor 12 is completed, thereby realizing the grinding and polishing processing of the grinding and polishing tool 9 and the active control of the contact force during the processing.

[0031] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A complex curved surface force-controlled grinding and polishing device for a multi-axis CNC machine tool, characterized in that: The complex curved surface force-controlled grinding and polishing device mainly consists of four parts: a mounting component (1), a metal shell (2), a rotary motion transmission component (3), and an active force control component (4); The mounting assembly (1) is mounted in cooperation with the outer flange of the machine tool spindle, and is used to connect the complex curved surface force-controlled grinding and polishing device to the machine tool spindle, so as to realize rapid installation and removal of the device; the metal housing 2 protects the active force control assembly and the rotary motion assembly from liquid and electromagnetic interference, and does not have other features that may cause interference with the workpiece during the grinding and polishing process; the upper end of the rotary motion transmission assembly (3) is connected to the machine tool spindle through the tool handle (5), and the lower end is used to realize grinding and polishing through the grinding and polishing tool (9); the upper end of the active force control assembly (4) is connected to the mounting assembly (1), and the rotary ball spline (7) in the rotary motion transmission assembly (3) at the lower end is used to control the contact force between the grinding and polishing tool (9) at the end of the device and the workpiece; The rotary motion transmission component (3) comprises a tool handle (5), a transmission shaft (6), a rotary ball spline (7), a connecting flange (8) and a grinding and polishing tool (9); the central spline shaft of the rotary ball spline (7) is connected to the transmission shaft (6), the lower end of the inner ring of the rotary ball spline (7) is connected to the grinding and polishing tool (9) via the connecting flange (8), and as a structure for transmitting rotary motion, the upper end of the outer ring of the rotary ball spline (7) is connected to the active force control component (4), and the coupling of the axial motion of the outer ring and the rotary motion of the inner ring on the grinding and polishing tool (9) is achieved through the rotary ball spline (7); the grinding and polishing tool (9) is made of flexible material, and the active force control effect of the contact force is more stable by achieving flexible contact between the device and the workpiece; the grinding and polishing tool (9) is threadedly mounted to the lower end of the connecting flange (8), and it is easy to replace grinding and polishing consumables; The active force control component (4) comprises a stator flange (10), a linear bearing (11), a voice coil motor (12), a spring (13), a linear encoder (14), a mover flange (15), a force sensor (16) and a spline sleeve (17); the voice coil motor (12) is installed between the stator flange (10) and the mover flange (15) along the axial direction of the transmission shaft (6); the voice coil motor (12) applies thrust along the axial direction of the transmission shaft (6) and generates motion; the linear bearing (11), the spring (13) and the linear encoder (14) are installed along the axial direction of the transmission shaft (6) ) is installed between the stator flange (10) and the mover flange (15); the linear bearing (11) limits the radial displacement of the active force control component (4) to achieve an axial guiding function; the spring (13) is used to balance the gravity at the lower end of the active force control component (4), and the linear encoder (14) is used to collect the axial displacement generated by the voice coil motor (12); the force sensor (16) is installed at the lower end of the mover flange (15) and is connected to the rotary motion transmission component (3) through a spline sleeve (17) to measure the axial force value generated by the voice coil motor (12).

2. The complex curved surface force-controlled grinding and polishing device according to claim 1, characterized in that: The mounting assembly (1) integrates the power supply and signal circuit quick connection plugs required by the complex curved surface force-controlled grinding and polishing device.

3. The complex curved surface force-controlled grinding and polishing device according to claim 1, characterized in that: The voice coil motor (12) adopts a hollow structure, so that the transmission shaft (6) passes through the axis position of the voice coil motor (12), thereby making the axial force distribution more uniform.

4. The complex curved surface force-controlled grinding and polishing device according to claim 1, characterized in that: The linear bearing (11) and the spring (13) adopt a multi-group parallel evenly distributed structure, so that the structure of the active force control component (4) is more stable.

5. The complex curved surface force-controlled grinding and polishing device according to claim 1, characterized in that: The force sensor (16) is a ring-shaped force sensor or a plurality of force sensors evenly distributed.

6. The complex curved surface force-controlled grinding and polishing device according to claim 1, characterized in that: The spring (13) is a thrust spring.

7. The complex curved surface force-controlled grinding and polishing device according to claim 1, characterized in that: The material of the grinding and polishing tool (9) is a sponge disk, a wool disk or a rubber disk.

Images