Microsphere four-axis grinding device and grinding method thereof

Abstract

The invention discloses a microsphere four-axis grinding device and a grinding method thereof. The grinding device comprises a lathe bed assembly. The lathe bed assembly is provided with a four-axis grinding and polishing assembly and a feeding and discharging device. The four-axis grinding and polishing assembly comprises four grinding and polishing main shaft modules which are symmetrically arranged in a three-dimensional space, and the axes of the four grinding and polishing main shaft modules intersect at one point. The feeding and discharging device can convey the microsphere workpiece to a machining position before grinding and take down the microsphere workpiece after grinding. According to the microsphere four-axis grinding device, the specific structural design is adopted, the motorized spindle is used for driving the grinding tool, the motorized spindle and the grinding tool are connected through the elastic follow-up device, and when the device works, the grinding tool can slightly deflect, so that the grinding tool is always attached to the spherical surface of a microsphere workpiece, and the machining precision is effectively improved. The invention further provides a microsphere four-axis grinding method, according to the method, the grinding tool is controlled to switch the rotating direction according to the set time sequence, the microsphere workpiece is ground, and the grinding uniformity can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of sphere precision machining, and in particular to a microsphere four-axis grinding device and a grinding method realized by using the device. Background Art

[0002] High-quality surface microspheres play an irreplaceable role in the field of high technology and are important components of high-precision equipment. Their shape accuracy, surface quality and dimensional consistency directly affect the performance and life of mechanical parts. Precision spheres are often used for the calibration of various measuring equipment, such as optical measuring instruments, coordinate measuring machines, etc. By utilizing their geometric shape and dimensional accuracy, the accuracy of measuring equipment can be effectively corrected and verified. In addition, precision spheres can be used as references for reflective surfaces or focusing lenses, and are used in the calibration of laser systems and the testing of optical components to ensure the accuracy and uniformity of the beam. The precision processing technology of microspheres occupies an important position in many scientific research and industrial fields.

[0003] In recent years, micro-ball grinding technology has gradually become a research hotspot. The current micro-ball processing methods include single-disc and double-disc drive processing, three-disc and double-disc eccentric processing, variable curvature grooves and non-traditional magnetic fluid processing, non-magnetic fluid processing, etc. These methods perform well in improving the processing accuracy and surface quality of the sphere.

[0004] Although the ball grinding technology is relatively mature, there is still little research on the processing of balls with a diameter less than 5 mm. At the same time, the existing ball grinders have a single movement mode, which makes it difficult to form a continuous and uniform force on the precision ball. The existing equipment has low processing efficiency and it is difficult to control the movement trajectory of the precision ball during the grinding process, making it difficult to meet the requirements of efficient, precise and stable grinding.

[0005] The four-axis sphere grinding technology uses four grinding axes that are symmetrically arranged in space (the angle between any two axes is 109.4712°) to grind the sphere. The four grinding axes form a regular tetrahedron in space. The intersection of all axes is the position of the center of the ball blank to be processed. The rotation speed and pressure of the four grinding tools are controlled to be equal, and two grinding tools rotate forward and two grinding tools rotate reversely to drive the spherical workpiece to rotate. In theory, the spherical surface of the sphere can be formed and evenly ground. However, the four-axis grinding technology is still immature and is still in the laboratory stage. It cannot be used in the industry. One of the important factors is that errors cannot be avoided during the manufacturing and assembly of parts, which makes the four grinding axes unable to reach the theoretical state. During the grinding process, the sphere is in a floating state, so the grinding tool cannot completely fit the spherical surface, affecting the processing accuracy. This problem is particularly prominent on microspheres. Summary of the invention

[0006] In order to overcome the deficiencies in the prior art, the present invention provides a microsphere four-axis grinding device. The microsphere four-axis grinding device of the present invention adopts a specific structural design, uses an electric spindle to drive the grinding tool, and the electric spindle and the grinding tool are connected by an elastic follower. During operation, the grinding tool can be slightly deflected, so that it always keeps in contact with the spherical surface of the microsphere workpiece, effectively improving the processing accuracy. Correspondingly, the present invention also provides a microsphere four-axis grinding method. The method of the present invention realizes the grinding of the microsphere workpiece by controlling the grinding tool to switch the rotation direction according to a set timing, which is conducive to improving the uniformity of grinding.

[0007] For the grinding device, the technical solution of the present invention is as follows:

[0008] A microsphere four-axis grinding device comprises a frame; a bed assembly is arranged on the frame, and a four-axis grinding and polishing assembly and a loading and unloading device are arranged on the bed assembly; the four-axis grinding and polishing assembly comprises four grinding and polishing spindle modules which are arranged symmetrically in three-dimensional space, and the axes of the four grinding and polishing spindle modules converge at one point; one grinding and polishing spindle module in the four-axis grinding and polishing assembly is vertically arranged, which is axis I, and the other three grinding and polishing spindle modules are axis II, axis III and axis IV respectively; the grinding and polishing spindle module comprises a cup-shaped grinding tool, an elastic follower, an electric spindle, a clamp, a push plate, a pressure sensor, an electric push rod, and a linear module; the electric push rod and the linear module are fixed on the bed assembly, and the push plate is arranged on the linear module. The electric push rod can push the push plate to perform linear motion on the linear module; the electric spindle is fixed to the push plate by a clamp, and the front end of the electric spindle is connected to the elastic follower, which can drive the elastic follower to perform rotational motion; the cup-shaped grinder is connected to the elastic follower and can rotate with the elastic follower, and the front end face of the cup-shaped grinder can fit the spherical surface of the micro-sphere workpiece; the elastic follower allows the cup-shaped grinder to deflect slightly after the cup-shaped grinder presses the micro-sphere workpiece; the pressure sensor is connected to the output shaft of the electric push rod, and can detect the pressure changes when the cup-shaped grinder contacts the micro-sphere workpiece in real time, and feed back the pressure data to the control system to control the output pressure of the electric push rod.

[0009] Compared with the prior art, the microsphere four-axis grinding device of the present invention can improve grinding accuracy and realize automated grinding, and has made significant progress, as follows:

[0010] 1) In the four-axis grinding device of the present invention, the grinding tool is connected to the electric spindle through an elastic follower device, and the elastic follower device allows the grinding tool to deflect slightly to ensure that it can fit with the surface of the microsphere workpiece, thereby ensuring the processing effect and improving the grinding accuracy.

[0011] 2) In the grinding device of the present invention, an electric push rod is used to realize the feeding of the grinding shaft. A spring device and a pressure sensor are provided between the spring device and the electric spindle. When working, the pressure acting on the surface of the microsphere workpiece can be kept constant.

[0012] Furthermore, in the aforementioned microsphere four-axis grinding device, the loading and unloading device includes a loading mounting frame and a loading rod; the loading mounting frame is provided with a micro electric cylinder, and the micro electric cylinder can control the lifting and lowering of the loading rod; the top of the loading rod is provided with a ball pit for placing the microsphere workpiece, and the side of the ball pit is provided with a grinding tool clearance groove, and the cup-shaped grinding tool can pass through the grinding tool clearance groove to press the microsphere workpiece. The loading and unloading device adopts this design, which has high reliability, can realize automatic loading and unloading, improve work efficiency, and is easy to implement.

[0013] Furthermore, in order to further improve reliability, in the aforementioned microsphere four-axis grinding device, the loading rod is connected to the micro electric cylinder through a floating joint.

[0014] Furthermore, in the aforementioned microsphere four-axis grinding device, a polishing liquid collecting tank is sleeved on the feeding rod, so that during processing, the polishing liquid falling from the processing area can be collected by the polishing liquid collecting tank for recycling.

[0015] Furthermore, in the aforementioned microsphere four-axis grinding device, the upper portion of the loading mounting frame is provided with a dust cover, and the dust cover is fixedly connected to the bed assembly.

[0016] Furthermore, in the aforementioned microsphere four-axis grinding device, a spring device is provided between the push plate and the pressure sensor, and the spring device includes a buffer spring and a limit pin arranged in a group, one end of the limit pin is fixedly connected to the pressure sensor, and the other end passes through the guide hole on the push plate and is slidably connected to the push plate; a limit portion is provided at the end of the limit pin, and the limit pin forms a limit on the push plate through the limit portion; a notch for spring positioning is respectively provided on the pressure sensor and the push plate, and the two ends of the buffer spring are respectively assembled in the notches on the pressure sensor and the push plate. The setting of the spring device can eliminate the non-parallelism problem caused by the installation error, and provide an effective buffering function, reduce the impact load during the grinding process, and improve the stability and control accuracy of the device.

[0017] Furthermore, in the aforementioned microsphere four-axis grinding device, the bed assembly is provided with a drag chain used in conjunction with the electric spindle, the movable end of the drag chain is fixedly connected to the push plate, and the wires of the electric spindle are arranged in the drag chain. This prevents the wires of the electric spindle from being worn, pulled off or scattered during movement, protects the wires, improves safety, optimizes line management, and improves the neatness of the equipment.

[0018] Furthermore, in the aforementioned micro-sphere four-axis grinding device, the linear module includes a base, a cross roller guide, and a sliding block; the base is fixedly connected to the bed assembly, and the cross roller guide is arranged on the base; the sliding block is slidably connected to the cross roller guide, and the push plate is fixedly connected to the sliding block. The cross roller guide has high precision and high stability, transmits pressure more smoothly and accurately, and improves grinding accuracy.

[0019] Furthermore, in the aforementioned microsphere four-axis grinding device, the elastic follower device includes a shell, a bushing is provided at the front end of the shell, the shell has axial and radial limits on the bushing, and the cup-shaped grinder extends out of the shell through the bushing; the cup-shaped grinder is in clearance with the bushing, and the step surface at its rear end is used to abut against the bushing to form an axial limit; the rear end of the shell is provided with a base, and the base is fixedly connected to the shell; a pressure spring and a sliding rod are provided between the base and the cup-shaped grinder, and the sliding rod is in the shape of a stepped shaft, the large end is movably connected to the cup-shaped grinder and can slide along the axial direction, and the small end is movably connected to the base and forms an axial limit through the stepped surface; the axis of the base and the cup-shaped grinder is respectively provided with a notch for spring positioning, and the two ends of the pressure spring are respectively assembled in the notches on the base and the cup-shaped grinder; the axis of the base is provided with a driving rod, and the driving rod is connected to the electric spindle in a transmission manner. The elastic follower device adopts the above-mentioned structural design, which can meet the functional requirements of micro-deflection, is easy to implement, and has high reliability.

[0020] Furthermore, in the aforementioned microsphere four-axis grinding device, a shock-absorbing pad is provided at the connection between the bed assembly and the frame. The provision of the shock-absorbing pad can further reduce the influence of equipment vibration on the grinding of the microsphere workpiece, thereby ensuring the grinding effect.

[0021] For the grinding method, the technical scheme of the present invention is as follows:

[0022] A microsphere four-axis grinding method, which utilizes the above-mentioned microsphere four-axis grinding device to grind a microsphere workpiece, comprises the following steps:

[0023] S1: Place the microsphere workpiece in the ball pit of the loading rod, and the micro-electric cylinder pushes the loading rod up to load the microsphere workpiece to the specified position and stop;

[0024] S2: The cup-shaped lapping tool of axis I is driven downward by the electric push rod, and presses against the microsphere workpiece with a pressure of 0.1-1N; then, the cup-shaped lapping tools of the other three axes are driven by the electric push rod to move in the direction of the microsphere workpiece, and press against the microsphere workpiece with the same pressure as axis I, and then the loading rod descends back to its original position;

[0025] S3: Start the electric spindle, and the four cup-shaped grinders start to rotate and switch the rotation direction according to the set timing; the pressure exerted by the cup-shaped grinders on the microsphere workpiece causes friction between the cup-shaped grinders and the microsphere workpiece, thereby driving the microsphere workpiece to perform a compound motion. Under the action of friction, the high points on the surface of the microsphere workpiece are removed, making the radius of the sphere tend to be consistent;

[0026] S4: After the processing reaches the set time, the cup-shaped grinder stops rotating, the micro-electric cylinder pushes the loading rod to rise, the cup-shaped grinder withdraws, and the microsphere workpiece falls back into the ball pit of the loading rod. Then, the loading rod descends to its original position and takes out the microsphere workpiece.

[0027] Compared with the prior art, the microsphere four-axis grinding method of the present invention adopts the above-mentioned microsphere four-axis grinding device to grind the microspheres. The method of the present invention realizes the grinding of the microsphere workpiece by controlling the grinding tool to switch the rotation direction according to the set timing, which is beneficial to improving the uniformity of grinding; during the processing, the angle of the cup-shaped grinding tool can be slightly adjusted so that the axis center of the cup-shaped grinding tool always coincides with the center of the microsphere workpiece, thereby ensuring the processing effect and improving the grinding accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the microsphere four-axis grinding device of the present invention;

[0029] Figure 2 It is a structural schematic diagram of the grinding and polishing spindle module in the microsphere four-axis grinding device of the present invention;

[0030] Figure 3 1. It is a schematic diagram of the structure of the loading and unloading device in the microsphere four-axis grinding device of the present invention (in the figure, the dust cover is hidden to clearly express the internal structure);

[0031] Figure 4 It is a schematic diagram of the structure of a cup-shaped grinding tool in a microsphere four-axis grinding device of the present invention;

[0032] Figure 5 : is a schematic diagram of the structure of the spring device in the microsphere four-axis grinding device of the present invention (in order to clearly express the structure of the spring device, the push plate and the pressure sensor are retained in the figure);

[0033] Figure 6 It is a schematic diagram of the structure of the elastic follower device and the cup-shaped grinding tool in the microsphere four-axis grinding device of the present invention;

[0034] Figure 7 Schematic diagram of the internal structure of the elastic follower and the cup-shaped grinding tool in the microsphere four-axis grinding device of the present invention (the outer shell of the elastic follower is hidden in the figure);

[0035] Figure 8 It is a schematic diagram of the structure of the linear module in the microsphere four-axis grinding device of the present invention;

[0036] Fig. 9 It is a process timing diagram of the forward and reverse rotation of the cup-shaped grinding tool in the microsphere four-axis grinding method of the present invention;

[0037] Fig.10 The roundness test diagram of the workpiece surface after being ground by the microsphere four-axis grinding device of the present invention is measured by a roundness measuring instrument;

[0038] Fig.11 The white light interferometer is used to measure the white light interference pattern of the workpiece surface after being ground by the microsphere four-axis grinding device of the present invention;

[0039] Fig.12 It is a schematic diagram of the cup-shaped grinding tool in the microsphere four-axis grinding device of the present invention adjusting its processing angle as the position of the microsphere workpiece changes.

[0040] The accompanying drawings are marked as follows: 1-frame; 2-bed assembly; 3-micro-sphere workpiece; 4-cup-shaped grinding tool; 5-elastic follower; 501-shell; 502-bushing; 503-base; 504-pressure spring; 505-sliding rod; 506-driving rod; 6-electric spindle; 7-clamp; 8-push plate; 9-pressure sensor; 10-electric push rod; 11-linear module; 1101-base; 1102-cross roller guide; 1103-slider; 12-feeding mounting frame; 13-feeding rod; 1301-ball pit; 1302-grinding tool clearance groove; 14-micro electric cylinder; 15-dust cover; 16-spring device; 1601-buffer spring; 1602-limit pin; 17-drag chain; 18-floating joint; 19-polishing liquid collection tank; 20-shock-absorbing pad. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to serve as the basis of the present invention.

[0042] Example (see Figure 1-12 ):

[0043] A microsphere four-axis grinding device comprises a frame 1; a bed assembly 2 is provided on the frame 1, and a four-axis grinding and polishing assembly and a loading and unloading device are provided on the bed assembly 2; the four-axis grinding and polishing assembly comprises four grinding and polishing spindle modules which are arranged symmetrically in three-dimensional space, and the axes of the four grinding and polishing spindle modules converge at one point; one grinding and polishing spindle module in the four-axis grinding and polishing assembly is vertically arranged, which is axis I, and the other three grinding and polishing spindle modules are axis II, axis III and axis IV respectively in counterclockwise direction; the grinding and polishing spindle module can act on the outer surface of a microsphere workpiece 3 to realize polishing of the surface of the microsphere workpiece 3; the loading and unloading device can transport the microsphere workpiece 3 to the processing position before grinding, and remove the microsphere workpiece 3 after grinding is completed.

[0044] In the embodiment, the grinding and polishing spindle module includes a cup-shaped grinding tool 4, an elastic follower 5, an electric spindle 6, a clamp 7, a push plate 8, a pressure sensor 9, an electric push rod 10, and a linear module 11; the electric push rod 10 and the linear module 11 are fixed to the bed assembly 2, the push plate 8 is arranged on the linear module 11, and the electric push rod 10 can push the push plate 8 to perform linear motion on the linear module 11; the electric spindle 6 is fixed to the push plate 8 by the clamp 7, and the front end of the electric spindle 6 is connected to the elastic follower 5, which can drive the elastic follower 5 to perform rotational motion; the The cup-shaped grinder 4 is connected to the elastic follower 5 and can rotate with the elastic follower 5. The front end face of the cup-shaped grinder 4 can fit with the spherical surface of the microsphere workpiece 3. After the cup-shaped grinder 4 presses the microsphere workpiece 3, the elastic follower 5 allows the cup-shaped grinder 4 to deflect slightly, so that the cup-shaped grinder 4 always fits with the spherical surface of the microsphere workpiece 3. The pressure sensor 9 is connected to the output shaft of the electric push rod 10, and can detect the pressure changes when the cup-shaped grinder 4 contacts the microsphere workpiece 3 in real time, and feed back the pressure data to the control system to control the output pressure of the electric push rod 10.

[0045] In the embodiment, the loading and unloading device includes a loading mounting frame 12 and a loading rod 13; a micro electric cylinder 14 is provided in the loading mounting frame 12, and the micro electric cylinder 14 can control the lifting and lowering of the loading rod 13; a ball pit 1301 for placing the microsphere workpiece 3 is provided at the top of the loading rod 13, and a grinding tool clearance groove 1302 is provided on the side of the ball pit 1301, and the cup-shaped grinding tool 4 can pass through the grinding tool clearance groove 1302 to press the microsphere workpiece 3.

[0046] In the embodiment, the feeding rod 13 is connected to the micro-electric cylinder 14 via a floating joint 18. The floating joint 18 can finely adjust the position of the feeding rod 13 in the vertical direction, further improving the feeding accuracy.

[0047] In the embodiment, a polishing liquid collecting tank 19 is sleeved on the feeding rod 13. Therefore, during processing, the polishing liquid collecting tank 19 can be used to collect the polishing liquid falling from the processing area to achieve recycling and reuse.

[0048] In the embodiment, a dust cover 15 is provided on the upper portion of the loading mounting frame 11 , and the dust cover 15 is fixedly connected to the bed assembly 2 .

[0049] In the embodiment, a spring device 16 is provided between the push plate 8 and the pressure sensor 9, and the spring device 16 includes a buffer spring 1601 and a limit pin 1602 arranged in a group, one end of the limit pin 1602 is fixedly connected to the pressure sensor 9, and the other end passes through the guide hole on the push plate 8 and is slidably connected to the push plate 8; a limit portion is provided at the end of the limit pin 1602, and the limit pin 1602 limits the push plate 8 through the limit portion; a notch for spring positioning is provided on the pressure sensor 9 and the push plate 8, respectively, and the two ends of the buffer spring 1601 are respectively assembled in the notches on the pressure sensor 9 and the push plate 8. The setting of the spring device 16 can eliminate the non-parallel problem caused by the installation error, and provide an effective buffering function, reduce the impact load during the grinding process, and improve the stability and control accuracy of the device.

[0050] In the embodiment, the bed assembly 2 is provided with a drag chain 17 used in conjunction with the electric spindle 6, the movable end of the drag chain 17 is fixedly connected to the push plate 8, and the wires of the electric spindle 6 are arranged in the drag chain 17. The wires of the electric spindle 6 are prevented from being worn, pulled off, and scattered during movement, which can protect the wires, improve safety, optimize line management, and improve the neatness of the equipment.

[0051] In the embodiment, the linear module 11 includes a base 1101, a cross roller guide 1102, and a sliding block 1103; the base 1101 is fixedly connected to the bed assembly 2, the cross roller guide 1102 is arranged on the base 1101; the sliding block 1103 is slidably connected to the cross roller guide 1102, and the push plate 8 is fixedly connected to the sliding block 1103. The cross roller guide 1102 has high precision and high stability, can transmit pressure more smoothly and accurately, and improves grinding accuracy.

[0052] In the embodiment, the elastic follower 5 includes a shell 501, a bushing 502 is provided at the front end of the shell 501, the shell 501 has axial and radial limits on the bushing 502 (interference fit in the embodiment), the cup-shaped grinder 4 passes through the bushing 502 and extends to the outside of the shell 501; the cup-shaped grinder 4 is in clearance fit with the bushing, and the step surface at its rear end is against the bushing 502 to form an axial limit; the rear end of the shell 501 is provided with a base 503, and the base 503 is fixedly connected to the shell 501; a pressure spring 504 and a sliding rod 505 are provided between the base 503 and the cup-shaped grinder 4, The sliding rod 505 is in the shape of a stepped shaft, with the large end movably connected to the cup-shaped grinder 4 and can slide axially, and the small end movably connected to the base 503 and forming an axial limit through the stepped surface (the small end of the sliding rod 505 is inserted into the through hole of the base 503, and at the same time, its step surface is against the base 503 to form an axial limit); the axis of the base 503 and the cup-shaped grinder 4 are respectively provided with a notch for spring positioning, and the two ends of the pressure spring 504 are respectively assembled in the notches on the base 503 and the cup-shaped grinder 4; the axis of the base 503 is provided with a driving rod 504, and the driving rod 504 is connected to the electric spindle 6 in transmission. The elastic follower 5 adopts the above-mentioned structural design, which can meet the functional requirements of micro-deflection, is easy to implement, and has high reliability. Fig.12 It is shown that during the grinding process, the pressure spring 504 can adapt to the position change of the microsphere workpiece 3 through elastic deformation, so that the cup-shaped grinder 4 can adjust its processing angle, thereby maintaining stable contact between the cup-shaped grinder 4 and the microsphere workpiece 3 (during processing, the cup-shaped grinder 4 applies pressure to the surface of the microsphere workpiece 3, compressing the pressure spring 504, separating the step surface of the cup-shaped grinder 4 from the bushing 502, and because the cup-shaped grinder 4 and the bushing have a clearance fit, the cup-shaped grinder 4 can change its processing angle).

[0053] In the embodiment, a shock-absorbing pad 20 is provided at the connection between the bed assembly 2 and the frame 1. The provision of the shock-absorbing pad 20 can further reduce the influence of equipment vibration on the grinding of the microsphere workpiece 3, thereby ensuring the grinding effect.

[0054] In the embodiment, the microsphere four-axis grinding method comprises the following steps:

[0055] S1: Place the microsphere workpiece 3 in the ball pit 1301 of the loading rod 13, and the micro-electric cylinder 14 pushes the loading rod 13 upward to load the microsphere workpiece 3 to the specified position and stop;

[0056] S2: The cup-shaped grinding tool 4 of the I axis is pressed down by the electric push rod 10, and the microsphere workpiece 3 is supported by a pressure of 0.1-1N; then, the cup-shaped grinding tools 4 of the other three axes are driven by the electric push rod 10 to move along the direction of the microsphere workpiece 3, and the microsphere workpiece 3 is supported by the same pressure as the I axis, and then the loading rod 13 is lowered back to the original position;

[0057] S3: Start the electric spindle 6, the four cup-shaped grinders 4 start to rotate, and switch the rotation direction according to the set timing; the pressure applied by the cup-shaped grinder 4 on the microsphere workpiece 3 generates friction between the cup-shaped grinder 4 and the microsphere workpiece 3, thereby driving the microsphere workpiece 3 to perform a compound motion. Under the action of friction, the high points on the surface of the microsphere workpiece 3 are removed, so that the radius of the sphere tends to be consistent; the rotation speed of the four cup-shaped grinders 4 is adjustable within the range of 100-3000r / min; in the early stage (10-15min), the cup-shaped grinder 4 uses a high speed to roughly grind the microsphere workpiece 3; in the later stage (5-10min), the cup-shaped grinder 4 uses a low speed to finely grind the microsphere workpiece 3; in this way, the grinding efficiency can be improved while ensuring the grinding accuracy;

[0058] S4: After the processing reaches the set time, the cup-shaped grinding tool 4 stops rotating, the micro-electric cylinder 14 pushes the loading rod 13 to rise, the cup-shaped grinding tool 4 withdraws, and the microsphere workpiece 3 falls back into the ball pit 1301 of the loading rod 13. Then, the loading rod 13 descends to its original position and takes out the microsphere workpiece 3.

[0059] The present invention is further described below in conjunction with a processing experiment carried out in accordance with the implementation of the present invention.

[0060] In the processing experiment, the setting sequence of the four cup-shaped grinding tools 4 is as follows Fig. 9 As shown, specifically: ① The cup-shaped grinder 4 of axis Ⅰ and axis Ⅲ rotates reversely, and the cup-shaped grinder 4 of axis Ⅱ and axis Ⅳ rotates forwardly; ② The cup-shaped grinder 4 of axis Ⅰ and axis Ⅱ rotates forwardly, and the cup-shaped grinder 4 of axis Ⅲ and axis Ⅳ rotates reversely; ③ The cup-shaped grinder 4 of axis Ⅰ and axis Ⅳ rotates reversely, and the cup-shaped grinder 4 of axis Ⅱ and axis Ⅲ rotates forwardly; ④ The cup-shaped grinder 4 of axis Ⅰ and axis Ⅲ rotates forwardly, and the cup-shaped grinder 4 of axis Ⅱ and axis Ⅳ rotates reversely; ⑤ The cup-shaped grinder 4 of axis Ⅰ and axis Ⅱ rotates reversely, and the cup-shaped grinder 4 of axis Ⅲ and axis Ⅳ rotates forwardly; ⑥ The cup-shaped grinder 4 of axis Ⅰ and axis Ⅳ rotates forwardly, and the cup-shaped grinder 4 of axis Ⅱ and axis Ⅲ rotates reversely.

[0061] In the processing experiment, a silicon ball with diamond deposited on the surface was selected as the processing workpiece, and it was polished using the above-mentioned grinding method, wherein the polishing liquid selected was a 3% diamond polishing liquid, and the cup-shaped grinding tool 4 was made of cast iron; during polishing, the pressure of the cup-shaped grinding tool 4 on the workpiece surface was 0.5N; in the early stage (10min), the rotation speed of the cup-shaped grinding tool 4 was 2000r / min, and the workpiece surface was roughly polished, and in the later stage (5min), the rotation speed of the cup-shaped grinding tool 4 was adjusted to 600r / min, and the workpiece surface was finely polished; Fig. 9 , the four cup-shaped grinding tools 4 are replaced with a steering combination every 15s; Fig.10 , 11As shown, after processing, the roundness deviation of the workpiece was measured by a roundness measuring instrument to be 0.03677um, and the surface roughness of the workpiece was measured by a white light interferometer to be 53.54nm.

[0062] The above general description of the invention involved in this application and the description of its specific implementation methods should not be understood as limiting the technical solutions of the invention. Based on the disclosure of this application, those skilled in the art can, without violating the constituent elements of the invention involved, add, reduce or combine the disclosed technical features in the above general description or / and specific implementation methods (including examples) to form other technical solutions within the scope of protection of this application.

Claims

1. A microsphere four-axis grinding device, comprising a frame (1); a bed assembly (2) is provided on the frame (1), and a four-axis grinding and polishing assembly and a loading and unloading device are provided on the bed assembly (2); the four-axis grinding and polishing assembly comprises four grinding and polishing spindle modules which are arranged symmetrically in three-dimensional space, and the axes of the four grinding and polishing spindle modules converge at a point; one grinding and polishing spindle module in the four-axis grinding and polishing assembly is vertically arranged, which is axis I, and the other three grinding and polishing spindle modules are axis II, axis III and axis IV respectively; Features: The grinding and polishing spindle module comprises a cup-shaped grinding tool (4), an elastic follower (5), an electric spindle (6), a clamp (7), a push plate (8), a pressure sensor (9), an electric push rod (10), and a linear module (11); the electric push rod (10) and the linear module (11) are fixed on the bed assembly (2), the push plate (8) is arranged on the linear module (11), and the electric push rod (10) can push the push plate (8) to perform linear motion on the linear module (11); the electric spindle (6) is fixed on the push plate (8) by the clamp (7), and the front end of the electric spindle (6) is connected to the elastic follower (5) and can drive the elastic follower (5) to move linearly. The elastic follower (5) rotates; the cup-shaped grinder (4) is connected to the elastic follower (5) and can rotate with the elastic follower (5); the front end surface of the cup-shaped grinder (4) can fit the spherical surface of the microsphere workpiece (3); after the cup-shaped grinder (4) presses the microsphere workpiece (3), the elastic follower (5) allows the cup-shaped grinder (4) to deflect slightly; the pressure sensor (9) is connected to the output shaft of the electric push rod (10) and can detect the pressure change when the cup-shaped grinder (4) contacts the microsphere workpiece (3) in real time, and feeds back the pressure data to the control system to control the output pressure of the electric push rod (10).

2. The microsphere four-axis grinding device according to claim 1, characterized in that: The loading and unloading device comprises a loading mounting frame (12) and a loading rod (13); a micro electric cylinder (14) is arranged in the loading mounting frame (12), and the micro electric cylinder (14) can control the lifting and lowering of the loading rod (13); a ball pit (1301) for placing a microsphere workpiece (3) is arranged at the top end of the loading rod (13), and a grinding tool clearance groove (1302) is arranged around the ball pit (1301), and the cup-shaped grinding tool (4) can pass through the grinding tool clearance groove (1302) to press the microsphere workpiece (3).

3. The microsphere four-axis grinding device according to claim 2, characterized in that: The loading rod (13) is provided with a polishing liquid collecting tank (19).

4. The microsphere four-axis grinding device according to claim 2, characterized in that: The upper part of the loading mounting frame (11) is provided with a dust cover (15), and the dust cover (15) is fixedly connected to the bed assembly (2).

5. The microsphere four-axis grinding device according to claim 1, characterized in that: A spring device (16) is provided between the push plate (8) and the pressure sensor (9), the spring device (16) comprising a buffer spring (1601) and a limit pin (1602) arranged in a group, one end of the limit pin (1602) being fixedly connected to the pressure sensor (9), and the other end of the limit pin (1602) passing through a guide hole on the push plate (8) and being slidably connected to the push plate (8); a limit portion is provided at the end of the limit pin (1602), and the limit pin (1602) limits the push plate (8) through the limit portion; a notch for spring positioning is respectively provided on the pressure sensor (9) and the push plate (8), and two ends of the buffer spring (1601) are respectively assembled in the notches on the pressure sensor (9) and the push plate (8).

6. The microsphere four-axis grinding device according to claim 1, characterized in that: The bed assembly (2) is provided with a drag chain (17) for use with the electric spindle (6); the movable end of the drag chain (17) is fixedly connected to the push plate (8); and the electric wires of the electric spindle (6) are arranged in the drag chain (17).

7. The microsphere four-axis grinding device according to claim 1, characterized in that: The linear module (11) comprises a base (1101), a cross roller guide rail (1102), and a sliding block (1103); the base (1101) is fixedly connected to the bed assembly (2), and the cross roller guide rail (1102) is arranged on the base (1101); the sliding block (1103) is slidably connected to the cross roller guide rail (1102), and the push plate (8) is fixedly connected to the sliding block (1103).

8. The microsphere four-axis grinding device according to claim 1, characterized in that: The elastic follower device (5) comprises a shell (501), a bushing (502) is provided at the front end of the shell (501), the shell (501) has axial and radial limiting functions for the bushing (502), the cup-shaped grinding tool (4) passes through the bushing (502) and extends to the outside of the shell (501); the cup-shaped grinding tool (4) is in clearance fit with the bushing, and the step surface at the rear end thereof abuts against the bushing (502) to form an axial limiting function; the rear end of the shell (501) is provided with a base (503), and the base (503) is fixedly connected to the shell (501); the base (503) and the cup-shaped grinding tool (4) are connected to each other. A pressure spring (504) and a sliding rod (505) are provided between the base (503) and the cup-shaped grinder (4); the sliding rod (505) is in the shape of a stepped shaft, the large end of which is movably connected to the cup-shaped grinder (4) and can slide axially, and the small end of which is movably connected to the base (503) and forms an axial limit through a stepped surface; the axes of the base (503) and the cup-shaped grinder (4) are respectively provided with a notch for spring positioning, and the two ends of the pressure spring (504) are respectively assembled in the notches on the base (503) and the cup-shaped grinder (4); the axis of the base (503) is provided with a driving rod (504), and the driving rod (504) is transmission-connected to the electric spindle (6).

9. The microsphere four-axis grinding device according to claim 1, characterized in that: A shock-absorbing pad (20) is provided at the connection between the bed assembly (2) and the frame (1).

10. Microsphere four-axis grinding method, characterized in that: The method uses the microsphere four-axis grinding device of claim 1 to grind the microsphere workpiece (3), comprising the following steps: S1: placing the microsphere workpiece (3) in the ball pit (1301) of the loading rod (13), and the micro electric cylinder (14) pushes the loading rod (13) upward, loading the microsphere workpiece (3) to a designated position and stopping; S2: The cup-shaped grinding tool (4) of the I axis is pressed downward by the electric push rod (10) to press against the microsphere workpiece (3) with a pressure of 0.1-1N; then, the cup-shaped grinding tools (4) of the other three axes are moved along the direction of the microsphere workpiece (3) by the electric push rod (10) to press against the microsphere workpiece (3) with the same pressure as that of the I axis, and then, the loading rod (13) is lowered back to its original position; S3: starting the electric spindle (6), and the four cup-shaped grinding tools (4) start to rotate, and the rotation direction is switched according to the set timing; the pressure exerted by the cup-shaped grinding tools (4) on the microsphere workpiece (3) causes friction between the cup-shaped grinding tools (4) and the microsphere workpiece (3), thereby driving the microsphere workpiece (3) to perform a compound motion. Under the action of friction, the high points on the surface of the microsphere workpiece (3) are removed, so that the radius of the sphere tends to be consistent; S4: After the processing reaches the set time, the cup-shaped grinding tool (4) stops rotating, the micro-electric cylinder (14) pushes the loading rod (13) to rise, the cup-shaped grinding tool (4) is withdrawn, and the microsphere workpiece (3) falls back into the ball pit (1301) of the loading rod (13), and then the loading rod (13) descends to its original position to take out the microsphere workpiece (3).

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