A high-precision grinding error compensation system and control method based on rigid-flexible coupling

Abstract

This invention proposes a high-precision grinding error compensation system and control method based on rigid-flexible coupling, comprising: a first piezoelectric stack, a second piezoelectric stack, a first piezoelectric adjusting screw, a second piezoelectric adjusting screw, a signal measurement unit, and a control system; the first and second piezoelectric stacks are symmetrically mounted relative to the tool holder and in contact with a plane on the tool holder; the first piezoelectric adjusting screw is used to adjust the initial contact force between the first piezoelectric stack and the tool holder, and the second piezoelectric adjusting screw is used to adjust the initial contact force between the second piezoelectric stack and the tool holder; after adjusting the initial contact force, the signal measurement unit collects different excitation signals generated by the combined use of the first and second piezoelectric stacks and transmits them to the control system; the control system controls the working state of the first and second piezoelectric stacks to suppress vibration.

Description

Technical Field

[0001] This invention belongs to the field of ultra-precision machining technology, and in particular relates to a high-precision grinding error compensation system and control method based on rigid-flexible coupling. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] According to the ultra-precision grinding and polishing requirements of large thin-walled rotating parts, the grinding machine suffers from poor surface accuracy due to factors such as mechanical vibration and fixture clearance during the grinding process, which makes it difficult to meet the accuracy requirements of ultra-precision grinding. At the same time, there are also many common tool wear issues, which lead to large machine tool feed errors and also greatly affect the machining accuracy of the workpiece surface. This makes it difficult for the machine tool to effectively control the actual grinding force and grinding feed.

[0004] Currently, existing grinding systems have low processing efficiency. During the rotation of the grinding wheel, factors such as vibration and heat cause uneven force between the grinding wheel and the workpiece. Over time, this uneven force can easily affect the surface accuracy of the workpiece. Current technological improvements involve error compensation in the machine tool control system. However, due to the randomness of vibration information generated during the processing of parts, the machine tool control compensation system is unable to compensate for the effects of nonlinear factors, making it difficult to improve processing accuracy. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a high-precision grinding error compensation system based on rigid-flexible coupling. The system has a reasonable structural design, good operation quality, and reliable operation, meeting the requirements of high-precision grinding error compensation system and control system.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0007] In the first aspect, a high-precision grinding error compensation system based on rigid-flexible coupling is disclosed, comprising:

[0008] The system comprises a first piezoelectric stack, a second piezoelectric stack, a first piezoelectric adjusting screw, a second piezoelectric adjusting screw, a signal measurement unit, and a control system.

[0009] The first piezoelectric stack and the second piezoelectric stack are symmetrically mounted relative to the tool holder and are in contact with the plane on the tool holder;

[0010] The first piezoelectric adjusting screw is used to adjust the initial contact force between the first piezoelectric stack and the tool holder, and the second piezoelectric adjusting screw is used to adjust the initial contact force between the second piezoelectric stack and the tool holder;

[0011] After adjusting the initial contact force, the signal measurement unit collects different excitation signals generated during the combined use of the first piezoelectric stack and the second piezoelectric stack and transmits them to the control system. The control system controls the working state of the first piezoelectric stack and the second piezoelectric stack to suppress vibration.

[0012] As a further technical solution, a bushing is also included, which is fixed on the tool holder and aligned with the shoulder of the tool holder.

[0013] As a further technical solution, the first piezoelectric stack is installed in one of the mounting holes of the bushing through a piezoelectric end cap; the position of the first piezoelectric adjusting screw is fixed by a first adjusting nut.

[0014] As a further technical solution, the second piezoelectric stack is installed in one of the mounting holes of the bushing through a piezoelectric end cap, and the position of the second piezoelectric adjusting screw is fixed by a second adjusting nut.

[0015] As a further technical solution, a sensor clip is also included. The signal measurement unit is an accelerometer. The sensor clip mounts the accelerometer on the tool holder and aligns it with the end of the bushing. A sensor protective pad is installed inside the sensor clip to restrict the degrees of freedom of the accelerometer in various directions for collecting acceleration data.

[0016] As a further technical solution, it also includes a grinding wheel assembly structure, which includes a clamping structure and a combined grinding wheel module. The clamping structure consists of an inner grinding wheel ring and an outer grinding wheel ring. The combined grinding wheel module is circumferentially distributed in the clamping structure and cooperates with the limiting pin in the outer grinding wheel ring.

[0017] As a further technical solution, the grinding wheel assembly structure also includes an internal buffer pad and an external buffer pad;

[0018] The internal and external buffer pads are installed in the inner and outer rings of the grinding wheel on both sides of the combined grinding wheel module.

[0019] As a further technical solution, the grinding wheel assembly structure also includes multiple sets of spring positioning pins and pressure compensation springs, with the multiple sets of spring positioning pins evenly installed at the position of the outer ring spindle of the grinding wheel.

[0020] One end of the pressure compensation spring is evenly installed on the spring positioning pin, and the other end is aligned with the positioning hole inside the combined grinding wheel module, so that the combined grinding wheel module can be adjusted up and down according to the magnitude of the grinding force.

[0021] As a further technical solution, a fixing mechanism is also included, which includes fastening bolts and anti-loosening washers. The fastening bolts and anti-loosening washers are used together to fix the grinding wheel assembly structure at the front end of the tool holder, ensuring that the grinding wheel assembly structure can be tightly fitted together with the tool holder and ensuring the stability of the grinding wheel structure.

[0022] Secondly, a high-precision grinding error compensation method based on rigid-flexible coupling is disclosed, including:

[0023] Adjust the initial contact force between the first piezoelectric stack and the tool holder, and adjust the initial contact force between the second piezoelectric stack and the tool holder;

[0024] After adjusting the initial contact force, the signal measurement unit collects different excitation signals generated by the combined use of the first piezoelectric stack and the second piezoelectric stack and transmits them to the control system. The control system controls the working state of the first piezoelectric stack and the second piezoelectric stack to suppress vibration.

[0025] The above one or more technical solutions have the following beneficial effects:

[0026] This invention addresses the lack of corresponding vibration suppression and rigid-flexible coupled grinding wheel structure combinations in existing technologies. It not only achieves vibration suppression but also automatically utilizes the rigid-flexible coupling structure to compensate for grinding errors, thereby improving grinding accuracy and production efficiency. It achieves high-precision grinding error compensation in the ultra-precision grinding process of large, thin-walled rotating parts.

[0027] The present invention has a reasonable structural design, good operation quality, reliable operation, and high degree of versatility, which fully meets the requirements of high-precision grinding error compensation system and control method for the ultra-precision grinding process of large thin-walled rotating parts.

[0028] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a sectional view of the mechanical assembly system of the present invention;

[0031] Figure 2 This is a diagram of the variable friction grinding wheel mechanism based on the rigid-flexible coupling compensation principle of this invention;

[0032] The labels in the diagram are as follows: 1-Tool holder, 2-Sleeve, 3-Anti-loosening nut I, 4-Positioning set screw, 5-Piezoelectric end cap I, 6-Piezoelectric adjusting screw I, 7-Adjusting nut I, 8-Piezoelectric stack I, 9-Acceleration sensor, 10-Sensor clip, 11-Sensor protective pad, 12-Piezoelectric end cap II, 13-Adjusting nut II, 14-Piezoelectric adjusting screw II, 15-Piezoelectric stack II, 16-Fasting bolt, 17-Grinding wheel inner ring, 18-Combined grinding wheel module, 19-Internal buffer pad, 20-External buffer pad, 21-Pressure compensation spring, 22-Spring positioning pin, 23-Anti-loosening washer, 24-Grinding wheel outer ring, 25-Limit pin. Detailed Implementation

[0033] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0035] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0036] Example 1

[0037] like Figure 1 and Figure 2 As shown, this embodiment discloses a high-precision grinding error compensation system based on rigid-flexible coupling, including a tool holder 1, a bushing 2, an anti-loosening nut I3, a positioning set screw 4, a piezoelectric end cap I5, a piezoelectric adjusting screw I6, an adjusting nut I7, a piezoelectric stack I8, an acceleration sensor 9, a sensor clip 10, a sensor protective pad 11, a piezoelectric end cap II12, an adjusting nut II13, a piezoelectric adjusting screw II14, a piezoelectric stack II15, a fastening bolt 16, an inner ring of a grinding wheel 17, a combined grinding wheel module 18, an internal buffer pad 19, an external buffer pad 20, a pressure compensation spring 21, a spring positioning pin 22, an anti-loosening washer 23, an outer ring of a grinding wheel 24, and a limit pin 25.

[0038] This embodiment of the sub-technical solution addresses the different vibration signals randomly generated during workpiece processing. This application generates different vibration signals that cancel each other out with the vibration frequency of the workpiece, thereby achieving vibration suppression.

[0039] In this embodiment, the bushing 2 is fixed to the tool holder 1 by the anti-loosening nut I3 and the positioning set screw 4, and the bushing 2 is aligned with the shoulder of the tool holder 1 to ensure the accuracy of the installation position and coaxiality.

[0040] The aforementioned piezoelectric stack I8 is installed in one of the mounting holes of the bushing 2 via the piezoelectric end cap I5, ensuring that the piezoelectric stack I8 is in contact with the plane on the tool holder 1. Simultaneously, the contact force between the piezoelectric stack I8 and the tool holder is adjusted via the piezoelectric adjusting screw I6, and the position of the piezoelectric adjusting screw I6 is fixed using the adjusting nut I7. Adjusting the initial preload ensures that the piezoelectric stack I8 can achieve accurate output force and displacement.

[0041] The piezoelectric stack II15 is installed in one of the mounting holes of the bushing 2 through the piezoelectric end cap II12. It is necessary to ensure that the piezoelectric stack II15 and the piezoelectric stack I8 are installed symmetrically to facilitate symmetrical output force or displacement, which is beneficial to the construction of the control system. It is in contact with the plane on the tool holder 1. The contact force between the piezoelectric stack II15 and the tool holder is adjusted by the piezoelectric adjusting screw II14, and the position of the piezoelectric adjusting screw II14 is fixed by the adjusting nut II13.

[0042] The sensor clip 10 mounts the accelerometer 9 onto the tool holder 1 and aligns it with the end of the bushing 2 to ensure accurate mounting. Additionally, to prevent damage to the accelerometer 9, a sensor protective pad 11 is installed inside the sensor clip 10 to restrict the accelerometer 9's degrees of freedom in all directions, thereby enabling accurate acquisition of the workpiece's vibration (acceleration) signals during machining.

[0043] Specifically, the four sets of combined grinding wheel modules 18 are circumferentially distributed in the clamping structure formed by the inner ring 17 and the outer ring 24 of the grinding wheel, and the limiting pins 25 in the outer ring 24 of the grinding wheel are engaged together. The internal buffer pads 19 and external buffer pads 20 are installed in the inner ring 17 and the outer ring 24 of the grinding wheel on both sides of the four sets of combined grinding wheel modules 18 to seal the gaps in the grinding wheel and prevent grinding dust from affecting the reliability of the structure.

[0044] The aforementioned combined grinding wheel module 18 enables the grinding wheel to compensate for minute errors in the grinding process for different surface roughnesses of the workpiece, and has an automatic compensation function.

[0045] Twelve sets of spring locating pins 22 are evenly installed at the spindle position of the outer ring 24 of the grinding wheel; one end of each set of twelve pressure compensation springs 21 is evenly installed on the spring locating pins 22, and the other end is aligned with the locating holes inside the combined grinding wheel module 18, which allows the combined grinding wheel module 18 to be adjusted up and down according to the magnitude of the grinding force. Among them, the pressure compensation springs 21 maintain the contact force between the combined grinding wheel module 18 and the workpiece surface according to the radial force it receives.

[0046] The fastening bolt 16 and the anti-loosening washer 23 are used together to fix the grinding wheel assembly structure at the front end of the tool holder 1, ensuring that the grinding wheel structure can be tightly fitted together with the tool holder 1 and ensuring the stability of the grinding wheel structure.

[0047] Piezoelectric stacks I8 and II15 are used together, and both are controlled to generate high-frequency vibration. Specifically, the input voltage signal of the piezoelectric stacks is controlled to achieve high-frequency control. By generating different excitation signals, the vibration generated by the tool holder 1 during the machining process is suppressed. During the installation of piezoelectric stacks I8 and II15, the appropriate initial pressure needs to be adjusted using piezoelectric adjusting screws I6 and II14, and the corresponding voltage signal needs to be input to them to ensure that the two piezoelectric stacks can be accurately controlled. The initial pressure can be adjusted using a torque wrench.

[0048] Accelerometer 9 is a highly sensitive information acquisition device. It collects vibration signals and transmits them to the control system. The control system combines the signal information from accelerometer 9 with the piezoelectric stacks I8 and II15 to achieve stable vibration suppression. Specifically, the control system needs to determine the vibration information and output a voltage signal to control the piezoelectric stacks to generate a vibration frequency, thereby reducing the vibration of the workpiece.

[0049] The sensor clip 10 can adjust the installation position of the acceleration sensor 9 according to the structural parameters of the workpiece and the tool holder 1, and fix its structure stably on the tool holder 1 through the sensor protective pad 11. At the same time, it can correct the signal parameters of the acceleration sensor 9 according to the collected acceleration signal.

[0050] The inner ring 17 and outer ring 24 of the grinding wheel clamp the four sets of combined grinding wheel modules 18, which can realize the movement space of the combined grinding wheel modules 18 in the radial direction of -1.52 to +1.52 mm, and realize the error compensation function of the four sets of combined grinding wheel modules 18.

[0051] The spring force of the pressure compensation spring 21 ensures that the combined grinding wheel module 18 is in flexible contact with the workpiece surface, without achieving position compensation due to irregular surface roughness.

[0052] Each combined grinding wheel module 18 has three tapered holes inside, which are fitted with three pressure compensation springs 21 for installation. The resulting rigid-flexible coupling structure ensures that the combined grinding wheel module 18 can change its structural displacement according to the grinding force it receives, thereby compensating for grinding errors during the machining process. This achieves error compensation for all four sets of combined grinding wheel modules 18. The piezoelectric stack itself linearly outputs the corresponding displacement based on the input voltage.

[0053] The internal buffer pad 19 and the external buffer pad 20 not only provide dust protection and cushioning, but also have good high-temperature resistance. This effectively protects the working reliability of the grinding wheel structure.

[0054] This invention addresses the shortcomings of existing technologies. The lack of a suitable rigid-flexible coupled grinding wheel structure and vibration suppression control methods leads to low surface accuracy in the machining of large, thin-walled rotating parts. Furthermore, current machining systems only solve some basic chatter problems, failing to consider machining errors caused by workpiece-fixture clearance errors under different grinding conditions, and uneven force distribution during workpiece contact due to the long tool holder. This new system features a rational structural design, high-quality operation, and reliable performance, meeting the design requirements for high-precision grinding error compensation and control systems.

[0055] The grinding wheel structure itself is a flexible error compensation mechanism. The machining errors under different conditions are compensated by integrating the algorithms into the control system through the accumulation of previous technologies.

[0056] Since grinding force has processing errors, it is a variable. The flexible structure of the grinding wheel can compensate for these errors. Traditional solid grinding wheels do not have this compensation function. This invention collects chatter signals, and the corresponding vibration signal output by the piezoelectric stack cancels out the vibration frequency of the workpiece itself. By replacing the traditional rigid grinding wheel structure with a flexible, automatically compensating grinding wheel, flexible grinding is achieved, avoiding the problem of uneven force.

[0057] Example 2

[0058] The purpose of this embodiment is to provide a control method for a high-precision grinding error compensation system based on rigid-flexible coupling, which is particularly suitable for ultra-precision grinding and polishing of large, thin-walled rotating parts, including:

[0059] Adjust piezoelectric stacks I and II to have the same contact force with the tool holder;

[0060] Accurately collect vibration information of the tool holder using an accelerometer;

[0061] Vibration information is fed back to the control system in a timely manner, and vibration suppression signals are output to piezoelectric stack I and piezoelectric stack II.

[0062] Four sets of combined grinding wheel modules and 12 sets of spring locating pins are evenly installed on the outer ring mandrel of the grinding wheel. This allows the combined grinding wheel modules to be adjusted up and down according to the magnitude of the grinding force, ensuring that the combined grinding wheel modules can make good contact with the workpiece and thus improving the grinding quality.

[0063] The technical solution of the embodiments of the present invention solves the problem of rigid-flexible coupled grinding wheel structure combination in the prior art due to the lack of corresponding vibration suppression. It can not only achieve vibration suppression, but also automatically use rigid-flexible coupled structure to complete grinding error compensation, improve grinding accuracy and production efficiency, and fully meet the requirements of high-precision grinding error compensation system and control method for ultra-precision grinding of large thin-walled rotating parts.

[0064] The working process of the device of the present invention is as follows:

[0065] During the operation of this device, when performing ultra-precision grinding on large thin-walled rotating parts, it is first necessary to select a suitable tool holder 1 according to the structural parameters and dimensions of the parts, adjust and determine the installation position of the bushing 2, fix the bushing 2 with the anti-loosening nut I3 and the positioning set screw 4, and at the same time adjust the preload between the piezoelectric stack I8 and the piezoelectric stack II15 and the tool holder 1.

[0066] Adjust the sensor clip 10 to determine the installation position of the accelerometer 9, which is used to collect vibration signals generated during workpiece processing;

[0067] Next, the work begins. The tool holder 1 and the workpiece start to rotate together, and the rigid-flexible coupling high-precision grinding error compensation system of the present invention is moved to the designated grinding position. The combined grinding wheel module 18 contacts the workpiece surface and grinding begins. At this time, if the workpiece or the tool holder 1 vibrates significantly, the vibration signal of the tool holder 1 is collected by the acceleration sensor 9, and the piezoelectric stack I8 and piezoelectric stack II15 are controlled by the control system to start working and suppress the vibration of the tool holder 1.

[0068] Meanwhile, since the grinding wheel structure designed in this invention is a combination of spring structure and rigid structural component, it is a rigid-flexible coupling structure. The pressure compensation spring 21 automatically adjusts the contact force between the combined grinding wheel module 18 and the workpiece. When the force is large, the pressure compensation spring 21 is compressed. When the force is small, the pressure compensation spring 21 pushes the combined grinding wheel module 18 to maintain contact with the workpiece surface for grinding.

[0069] Meanwhile, the internal buffer pad 19 and the external buffer pad 20 can prevent grinding dust from affecting the movement clearance of the combined grinding wheel module 18, avoid structural failure, and ensure that the high-precision grinding error compensation system and control method based on rigid-flexible coupling in this invention can better improve the processing quality.

[0070] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A high-precision grinding error compensation system based on rigid-flexible coupling, characterized in that, include: The system comprises a first piezoelectric stack, a second piezoelectric stack, a first piezoelectric adjusting screw, a second piezoelectric adjusting screw, a signal measurement unit, and a control system. The first piezoelectric stack and the second piezoelectric stack are symmetrically mounted relative to the tool holder and are in contact with the plane on the tool holder; The first piezoelectric adjusting screw is used to adjust the initial contact force between the first piezoelectric stack and the tool holder, and the second piezoelectric adjusting screw is used to adjust the initial contact force between the second piezoelectric stack and the tool holder; After adjusting the initial contact force, the signal measurement unit collects different excitation signals generated by the combined use of the first piezoelectric stack and the second piezoelectric stack and transmits them to the control system. The control system controls the working state of the first piezoelectric stack and the second piezoelectric stack to suppress vibration. It also includes a grinding wheel assembly structure, which includes a clamping structure and a combined grinding wheel module. The clamping structure consists of an inner grinding wheel ring and an outer grinding wheel ring. The combined grinding wheel module is circumferentially distributed in the clamping structure and is engaged with a limiting pin in the outer grinding wheel ring. The grinding wheel assembly structure also includes an internal buffer pad and an external buffer pad; The internal and external buffer pads are installed in the inner and outer rings of the grinding wheel on both sides of the combined grinding wheel module. The grinding wheel assembly structure also includes multiple sets of spring positioning pins and pressure compensation springs, with the multiple sets of spring positioning pins evenly installed at the position of the outer ring spindle of the grinding wheel. One end of the pressure compensation spring is fixedly and evenly installed on the spring positioning pin, and the other end is aligned with the positioning hole inside the combined grinding wheel module, so that the combined grinding wheel module can be adjusted up and down according to the magnitude of the grinding force.

2. The high-precision grinding error compensation system based on rigid-flexible coupling as described in claim 1, characterized in that, It also includes a bushing, which is fixed on the tool holder and aligned with the shoulder of the tool holder.

3. The high-precision grinding error compensation system based on rigid-flexible coupling as described in claim 1, characterized in that, The first piezoelectric stack is mounted in one of the mounting holes of the bushing via a piezoelectric end cap; the first adjusting nut is used to fix the position of the first piezoelectric adjusting screw.

4. The high-precision grinding error compensation system based on rigid-flexible coupling as described in claim 1, characterized in that, The second piezoelectric stack is installed in one of the mounting holes of the bushing through a piezoelectric end cap, and the position of the second piezoelectric adjusting screw is fixed by a second adjusting nut.

5. The high-precision grinding error compensation system based on rigid-flexible coupling as described in claim 1, characterized in that, It also includes a sensor clip, the signal measurement unit is an accelerometer, the sensor clip mounts the accelerometer on the tool holder and aligns it with the end of the bushing, and a sensor protective pad is installed inside the sensor clip to restrict the degrees of freedom of the accelerometer in all directions for collecting acceleration.

6. The high-precision grinding error compensation system based on rigid-flexible coupling as described in claim 1, characterized in that, It also includes a fixing mechanism, which includes fastening bolts and anti-loosening washers. The fastening bolts and anti-loosening washers are used together to fix the grinding wheel assembly structure at the front end of the tool holder, ensuring that the grinding wheel assembly structure can be tightly fitted together with the tool holder and ensuring the stability of the grinding wheel structure.

7. The method for a high-precision grinding error compensation system based on rigid-flexible coupling as described in claim 1, characterized in that, include: Adjust the initial contact force between the first piezoelectric stack and the tool holder, and adjust the initial contact force between the second piezoelectric stack and the tool holder; After adjusting the initial contact force, the signal measurement unit collects different excitation signals generated by the combined use of the first piezoelectric stack and the second piezoelectric stack and transmits them to the control system. The control system controls the working state of the first piezoelectric stack and the second piezoelectric stack to suppress vibration.

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