A high-precision numerically controlled vertical grinding machine

Abstract

The present invention relates to the technical field of metal cutting, and particularly to a high-precision numerically controlled vertical grinding machine, which includes a column module, a bed module, and a grinding head module. The column module is connected to the bed module. A turntable is arranged on the bed, and a spindle box is slidably arranged on the column. A main shaft is arranged in the spindle box, and the main shaft is connected to the grinding head module. A topology repair module is also arranged in the spindle box; through the linkage design of the centering unit by the fixed seat, the centering plate, the pushing sub-unit, and the centering rod, it directly acts on the outer periphery of the main shaft to compensate the center deviation of the main shaft in real time; the pushing sub-unit is controlled by the control unit and can adjust the displacement of the centering plate according to the instruction output by the error repair model, so as to correct the radial offset of the main shaft caused by insufficient rigidity or assembly error; it solves the problems of large surface roughness and cumulative roundness error of the processed surface caused by vibration and center offset of the traditional grinding machine, and realizes high-precision deep hole processing.

Description

Technical Field

[0001] The present invention relates to the technical field of metal cutting, and particularly relates to a high-precision numerically controlled vertical grinding machine. Background Art

[0002] Vertical grinding machines are used for grinding machined parts after quenching, mainly for grinding the inner holes, outer circles, and end faces of parts.

[0003] Most existing vertical grinding machines use mechanical turntables, which have poor rigidity and rotational accuracy, the support bearings are prone to wear, and the roundness accuracy of the machine tool during processing is not high. In addition, the grinding head spindle of the existing vertical grinding machine is directly connected to the grinding wheel rod. Especially when processing deep holes, the grinding wheel rod is long and has poor rigidity. When the grinding wheel rotates at high speed, there is large vibration and poor rotational accuracy, and high-precision processing cannot be achieved. Summary of the Invention

[0004] The main purpose of the present invention is to provide a high-precision numerically controlled vertical grinding machine, aiming to solve the problem of low processing accuracy caused by large vibration of the grinding wheel during deep hole processing in the prior art.

[0005] To achieve the above object, the present invention provides a high-precision numerically controlled vertical grinding machine, including a column module, a bed module, and a grinding head module. The column module is connected to the bed module. A turntable is provided on the bed, and a shaft housing is slidably provided on the column. A main shaft is provided inside the shaft housing, and the main shaft is connected to the grinding head module. A topology repair module is also provided inside the shaft housing.

[0006] The topology repair module includes a control unit on which an error repair model is loaded. The topology repair module also includes a centering unit and a vibration damping unit provided inside the shaft housing. The centering unit is also connected to the outer periphery of the main shaft and is used to compensate for the central error of the main shaft. The vibration damping unit is also connected to the outer periphery of the main shaft and is used to reduce the rotational vibration of the main shaft.

[0007] Optionally, the centering unit includes a fixed seat fixedly connected to the shaft housing. A centering plate is rotatably provided on the fixed seat. The centering plate is sleeved on the main shaft. The fixed seat is also provided with a plurality of pushing sub-units. The end of the pushing sub-unit is hinged with a centering rod, and the free end of the centering rod is hinged with the centering plate. The pushing sub-unit is in communication connection with the control unit.

[0008] Optionally, the centering unit further includes a compensation sub-unit. The compensation sub-unit includes a cylinder provided on the fixed seat. The output end of the cylinder is connected with a compensation rod, and the compensation rod is sleeved on the main shaft.

[0009] Optionally, the vibration damping unit includes a plurality of vibration damping rods fixedly connected to the upper end surface of the axle box. The free end of the vibration damping rod is connected with a vibration damping plate, and the vibration damping plate is sleeved on the main shaft.

[0010] Optionally, the compensation rod, the centering plate and the vibration damping plate are all sleeved on the main shaft through bearings.

[0011] Optionally, the vibration damping rods are arranged in pairs.

[0012] Optionally, the error repair model is divided into topological branches, and the topological branches include a bed workpiece branch, a bed grinding head branch and a column main shaft branch.

[0013] Optionally, the error repair model includes a spatial error model and an error compensation model. The spatial error model is established through the following process: a local coordinate system is established for each topological branch, and the ideal motion relationship and actual error relationship of the topological branch are described by a homogeneous transformation matrix. Then, after establishing a spatial constraint equation and combining it with the homogeneous transformation matrix, a simultaneous solution is obtained to get the spatial error model.

[0014] Optionally, the error compensation model is established through the following process: partial derivatives are taken of the error parameters in the spatial error model, the sensitivity of the error parameters to the machining error is calculated, and the key error terms are determined through sensitivity coefficient normalization. Finally, the control unit repairs the key error terms according to the deviation value ratio of the key error terms.

[0015] Optionally, the process of repairing the key error terms of the main shaft by the compensation rod is as follows: the angle and displacement of the key error terms are extracted, and the cylinder is adjusted through the control unit to make the compensation rod output the same displacement at the reverse angle of the key error terms.

[0016] The process of repairing the key error terms of the main shaft by the centering plate is as follows: the angle and displacement of the key error terms are extracted, and the pushing subunit is adjusted through the control unit to make the centering plate output the displacement ratio at the reverse angle of the key error terms.

[0017] The synergistic effect of the mechanical structure and the intelligent control model proposed in the embodiment of the present invention realizes dynamic error compensation and vibration suppression. Among them, the centering unit directly acts on the outer periphery of the main shaft through the linkage design of the fixed seat, the centering plate, the pushing subunit and the centering rod to compensate the center deviation of the main shaft in real time; the pushing subunit is controlled by the control unit and can adjust the displacement of the centering plate according to the instruction output by the error repair model, so as to correct the radial offset of the main shaft caused by insufficient rigidity or assembly error; at the same time, the vibration damping unit forms a symmetric damping structure through the paired vibration damping rods and the vibration damping plate, disperses and absorbs the vibration energy of the main shaft, suppresses the vibration transmission during high-speed rotation, and significantly reduces the rotation vibration amplitude of the main shaft; solves the problems of large machining surface roughness and roundness error accumulation caused by vibration and center offset of traditional grinding machines, and realizes high-precision deep hole machining. Brief Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of the grinding machine of the present invention;

[0019] Figure 2 It is a schematic structural diagram of the axle box of the present invention;

[0020] Figure 3 It is a schematic cross-sectional structural diagram of the axle box of the present invention;

[0021] Figure 4 It is a schematic structural diagram of the centering unit and the vibration damping unit of the present invention;

[0022] Figure 5 It is a schematic structural diagram of the centering unit of the present invention.

[0023] Reference Signs:

[0024] 1 - Column Module, 2 - Bed Module, 3 - Grinding Head Module, 4 - Axle Box, 5 - Spindle, 6 - Turntable;

[0025] 41 - Centering Unit, 42 - Vibration Damping Unit;

[0026] 411 - Fixed Seat, 412 - Centering Plate, 413 - Pushing Sub - unit, 414 - Centering Rod, 415 - Cylinder, 416 - Compensation Rod;

[0027] 421 - Vibration Damping Rod, 422 - Vibration Damping Plate.

[0028] The realization of the purpose, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0031] In the present invention, unless otherwise clearly specified and defined, terms such as "connection" and "fixation" shall be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, such descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes Scenario A, or Scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] Embodiment 1:

[0034] Please refer to the attached Figures 1 to 5 , this embodiment provides a high-precision CNC vertical grinding machine, including a column module 1, a bed module 2, and a grinding head module 3. The column module 1 is connected to the bed module 2. A turntable 6 is arranged on the bed. A shaft housing 4 is slidably arranged on the column. A main shaft 5 is arranged inside the shaft housing 4, and the main shaft 5 is connected to the grinding head module 3. A topology repair module is also arranged inside the shaft housing 4;

[0035] The topology repair module includes a control unit on which an error repair model is carried. The topology repair module also includes a centering unit 41 and a vibration damping unit 42 arranged inside the shaft housing 4. The centering unit 41 is also connected to the outer periphery of the main shaft 5 and is used to compensate for the center error of the main shaft 5. The vibration damping unit 42 is also connected to the outer periphery of the main shaft 5 and is used to reduce the rotational vibration of the main shaft 5.

[0036] It should be noted that the grinding head spindle 5 of the existing vertical grinder is directly connected to the grinding wheel rod. Especially when processing deep holes, the grinding wheel rod is long and has poor rigidity. When the grinding wheel rotates at high speed, it vibrates greatly and has poor rotation accuracy, and high-precision processing cannot be achieved. Based on the above problems, this embodiment proposes to introduce a topology repair module and its internal structure into the grinder, which effectively solves the problems of large vibration, low rotation accuracy and poor processing roundness caused by insufficient rigidity of the grinding wheel rod in deep hole processing of the existing vertical grinder.

[0037] Specifically, the topology repair module is composed of a control unit, a centering unit 41 and a vibration reduction unit 42, and realizes dynamic error compensation and vibration suppression through the synergy of the mechanical structure and the intelligent control model. Among them, the centering unit 41 directly acts on the periphery of the main shaft 5 through the linkage design of the fixed seat 411, the centering plate 412, the pusher unit 413 and the centering rod 414, and compensates the center deviation of the main shaft 5 in real time.

[0038] The pusher unit 413 is controlled by the control unit, and can adjust the displacement of the centering plate 412 according to the instructions output by the error repair model, thereby correcting the radial offset of the main shaft 5 caused by insufficient rigidity or assembly error. At the same time, the vibration reduction unit 42 forms a symmetrical damping structure through the vibration reduction rod 421 and the vibration reduction plate 422 arranged in pairs, which disperses and absorbs the vibration energy of the main shaft 5, suppresses the vibration transmission during high-speed rotation, and significantly reduces the rotation vibration amplitude of the main shaft 5.

[0039] The synergistic effect of the above units improves the positioning accuracy and movement smoothness of the spindle 5 from the two dimensions of geometric accuracy and dynamic stability, solves the problems of large machining surface roughness and accumulated roundness errors caused by vibration and center offset of traditional grinders, and realizes high-precision deep hole processing.

[0040] In some embodiments, intelligent error compensation is achieved through an integrated error repair model, which further enhances the technical effect. The error repair model divides the machine tool system into three topological branches: a bed workpiece branch, a bed grinding head branch, and a column spindle 5 branch. A spatial error model is established based on a homogeneous transformation matrix. The relationship between the ideal motion and the actual error of each branch is described through a local coordinate system, and the global error distribution is obtained by jointly solving the spatial constraint equations.

[0041] In some embodiments, the control unit performs a sensitivity analysis on the error parameters based on the error compensation model, screens out the key error terms, and drives the compensation rod 416 of the centering unit 41 and adjusts the displacement of the centering plate 412 through the pushing sub-unit 413 to output the compensation amount in an inverse proportion. Specifically, according to the angle and displacement data of the key error terms, the compensation rod 416 is driven by the cylinder 415 to apply an equal displacement in the reverse angle direction to offset the geometric deviation of the main shaft 5; the centering plate 412 outputs a displacement in proportion in the reverse angle direction through the precise adjustment of the pushing sub-unit 413 to further correct the remaining errors.

[0042] In some embodiments, the proportion range of the displacement output by the centering plate 412 in proportion in the reverse angle direction is 0.6 to 0.8.

[0043] It can be understood that the above hierarchical compensation mechanism not only realizes the dynamic correction of the static error of the main shaft 5, but also suppresses the dynamic disturbance during the machining process through the continuous action of the vibration damping unit 42. Finally, while improving the machining accuracy, this structure significantly enhances the rigidity and vibration resistance of the machine tool, and is especially suitable for the machining of complex workpieces such as deep holes and high-precision curved surfaces, achieving a double breakthrough in machining efficiency and quality.

[0044] In some embodiments, the axle box 4 is connected to the column module 1 through a guide rail to realize the movement of the axle box 4 in the Z-axis direction. Among them, the guide rail is preferably a roller guide rail and is equipped with a corresponding grating scale, and the grating scale is communicatively connected to the control module to realize the acquisition of the corresponding error parameters.

[0045] In some embodiments, the grinding head module 3 is a deep hole grinding head. The deep hole grinding head has the characteristics of good support rigidity, small axial and radial runout, and high rotational accuracy. Especially when machining deep holes, the grinding wheel rod can be made very short and connected to the main shaft 5 of the deep hole grinding head, and the rigidity and accuracy of the grinding process can be effectively improved, and the accuracy of the roundness, taper, and coaxiality of the hole after the part is ground can be effectively improved.

[0046] In some embodiments, the turntable 6 is preferably a hydrostatic turntable 6. An oil film is formed between its working surfaces. The oil film has the characteristics of high rigidity, strong load-bearing capacity, and good vibration absorption. It can make there be no friction and wear between the working surfaces, good low-speed crawling, good accuracy stability, and long service life. The application of the high-precision hydrostatic turntable 6 improves the accuracy of the machine tool itself and the machining accuracy, and can realize ultra-precision grinding.

[0047] Embodiment 2:

[0048] In this embodiment, the centering unit 41 includes a fixed seat 411 fixedly connected to the axle box 4. A centering plate 412 is rotatably arranged on the fixed seat 411. The centering plate 412 is sleeved on the main shaft 5. The fixed seat 411 is further provided with a plurality of pushing sub-units 413. The end of the pushing sub-unit 413 is hingedly provided with a centering rod 414. The free end of the centering rod 414 is hinged to the centering plate 412. The pushing sub-unit 413 is communicatively connected to the control unit.

[0049] Based on Embodiment 1, this embodiment refines the mechanical linkage structure of the centering unit 41, solves the core problem of insufficient machining accuracy caused by the accumulation of radial deviations of the main shaft 5 in existing vertical grinding machines, and realizes high-response and high-precision dynamic error compensation.

[0050] Specifically, the centering unit 41 is composed of a fixed seat 411, a centering plate 412, a pushing sub-unit 413 and a centering rod 414. Among them, the fixed seat 411 is rigidly connected to the axle box 4. The centering plate 412 is sleeved on the outer periphery of the main shaft 5 through a bearing. The pushing sub-unit 413 and the centering plate 412 form a multi-degree-of-freedom linkage mechanism through the hinged centering rod 414. When

[0051] the main shaft 5 generates a radial offset due to insufficient rigidity or load change, the control unit drives the pushing sub-unit 413 to adjust the telescopic amount of the centering rod 414 according to the compensation instruction output by the error repair model, forcing the centering plate 412 to rotate or translate slightly around the axis of the main shaft 5. For example, if the main shaft 5 deflects to the left during the machining process due to uneven force, the pushing sub-unit 413 applies a reverse thrust to the centering plate 412 through the hinge point of the centering rod 414, causing the centering plate 412 to drive the main shaft 5 to return to the right, thereby correcting the center error in real time.

[0052] It can be understood that the above mechanical linkage design can not only directly act on the outer periphery of the main shaft 5 to achieve precise displacement compensation under force closed-loop control, but also reduce the rigid impact of the mechanical structure through the flexible connection of multiple hinge points, avoiding the jamming or wear problems caused by overconstraint in traditional rigid compensation mechanisms. Compared with the passive compensation methods of traditional grinding machines that rely on manual adjustment or single sensors, this structure improves the compensation accuracy of the center error of the main shaft 5 to the micron level through a dynamic closed-loop feedback mechanism, significantly improving the roundness error and coaxiality deviation in deep hole machining.

[0053] It can also be understood that the communication connection between the pushing sub-unit 413 and the control unit enables the adjustment process of the centering plate 412 to be linked with the error repair model in real time. Specifically, when the error model detects that the geometric error of the bed workpiece branch causes the center offset of the main shaft 5, the control unit can synchronously retrieve the compensation parameters of the centering unit 41 and realize multi-axis collaborative compensation through the precise displacement output of the pushing sub-unit 413.

[0054] The above intelligent linkage mechanism not only solves the local correction problem of a single error source, but also can cope with the multi-error coupling effect under complex working conditions. When machining deep holes, the increase in the overhanging length of the grinding wheel rod will amplify the flexural deformation of the main shaft 5, and the centering unit 41 of this embodiment can apply differential compensation forces at different rotation angles of the main shaft 5 by adjusting the displacement of the centering plate 412 in real time, so as to offset the non-linear error caused by flexure.

[0055] At the same time, the design of the articulated centering rod 414 allows the centering plate 412 to be freely adjusted in multiple directions, which not only ensures the flexibility of the compensation action, but also avoids the secondary offset caused by thermal expansion or assembly error of traditional rigid connections. The active compensation of the centering unit 41 further suppresses the interference of vibration on the positioning accuracy of the main shaft 5, forming a dual optimization mechanism of "static error dynamic trimming and dynamic vibration active suppression". Finally, the structure in this embodiment not only reduces the radial runout error of the main shaft 5 by more than 50%, but also improves the machining stability of the machine tool under high-speed and heavy-load working conditions by 30%. It is especially suitable for ultra-precision machining of complex parts such as high-precision turbine disks and hydraulic valve bodies in the aerospace field.

[0056] In some embodiments, the pushing subunit 413 is preferably a servo motor, a hydraulic actuator, a pneumatic actuator, etc.

[0057] In some embodiments, the communication connection between the pushing subunit 413 and the control unit is through a bus protocol or a digital signal interface.

[0058] In some embodiments, the centering plate 412 is a triangular plate, and the centering rods 414 are respectively hinged to the three corners of the centering plate 412.

[0059] Embodiment 3:

[0060] This embodiment only describes the parts different from Embodiment 2. Specifically, in this embodiment, the centering unit 41 further includes a compensation subunit, and the compensation subunit includes a cylinder 415 arranged on the fixed seat 411. The output end of the cylinder 415 is connected with a compensation rod 416, and the compensation rod 416 is sleeved on the main shaft 5.

[0061] It should be noted that the compensation rod 416 is sleeved on the outer periphery of the main shaft 5 through a bearing, forming a mechanical connection coaxial with the main shaft 5 but capable of independent movement. When the main shaft 5 generates axial or radial offset due to thermal expansion or load change, the control unit drives the cylinder 415 to push the compensation rod 416 to perform fine adjustment along the axial direction or the radial direction of the main shaft 5 according to the key error items output by the error repair model.

[0062] It should also be noted that during deep hole machining, the overhang of the grinding wheel rod will cause the front end of the main shaft 5 to deflect due to insufficient rigidity. At this time, the error repair model analyzes the geometric errors of the column main shaft 5 branch, extracts the displacement and direction of the key error items, and the control unit instructs the cylinder 415 to output an accurate linear displacement accordingly, driving the compensation rod 416 to apply a reverse thrust to the main shaft 5, directly offsetting the axis offset caused by the deflection deformation. The compensation rod 416 of this embodiment can act more directly on the force application point of the main shaft 5 through axial rigid connection, avoiding energy loss during force transmission and significantly improving the compensation efficiency. In addition, the linear drive characteristic of the cylinder 415 enables the compensation action to have a higher response speed, capable of real-time tracking of the dynamic error changes of the main shaft 5 under high-speed rotation or variable load conditions, thus solving the problem of insufficient compensation accuracy caused by inertial lag of traditional mechanical compensation mechanisms.

[0063] It should also be noted that the centering plate 412 initially corrects the center error of the main shaft 5 through the flexible adjustment of the hinge rod, while the compensation rod 416 performs secondary refined compensation on the residual error through the linear drive of the cylinder 415. When the main shaft 5 has both radial offset and axial offset, the centering unit 41 adjusts the radial position of the centering plate 412 through the pushing subunit 413 to correct the center deviation, while the cylinder 415 of the compensation subunit drives the compensation rod 416 to retract axially to offset the axial runout.

[0064] In some embodiments, the key error items include, for example, angle deviation and displacement deviation.

[0065] In this embodiment, the damping unit 42 includes a plurality of damping rods 421 fixedly connected to the upper end face of the axle box 4. The free ends of the damping rods 421 are connected with a damping plate 422, and the damping plate 422 is sleeved on the main shaft 5. Through the elastic deformation of the damping rods 421 and the damping effect of the damping plate 422, the radial vibration energy of the main shaft 5 is dispersed and absorbed. Specifically, when the grinding wheel rotates at high speed, the vibration of the main shaft 5 is transmitted to the damping rods 421 through the damping plate 422. The damping rods 421, as elastic support members, convert the vibration energy into heat energy dissipation through their own bending deformation. At the same time, the connection between the damping plate 422 and the bearing of the main shaft 5 avoids the vibration amplification effect caused by rigid contact.

[0066] In this embodiment, the compensation rod 416, the centering plate 412, and the damping plate 422 are all sleeved on the main shaft 5 through bearings.

[0067] It can be understood that the bearing connection enables components such as the compensation rod 416 and the centering plate 412 to apply a compensation force without affecting the free rotation of the main shaft 5. When the centering plate 412 is sleeved on the main shaft 5 through a bearing, its adjustment action only acts on the correction of the radial offset of the main shaft 5, and will not generate additional frictional resistance or heat accumulation due to the high-speed rotation of the main shaft 5.

[0068] In addition, the precise guiding characteristics of the bearing ensure that the acting direction of the compensation force is strictly aligned with the error direction of the main shaft 5, avoiding the compensation lag or accuracy loss caused by the clearance in the traditional sliding fit. In the structure where the compensation rod 416 is sleeved on the main shaft 5 through the bearing, the compensation rod 416 driven by the cylinder 415 can move precisely along the axial or radial direction of the main shaft 5, and its displacement resolution can reach 0.1 μm, capable of real-time correcting the micron-level errors caused by thermal deformation.

[0069] In this embodiment, the damping rods 421 are arranged in pairs. Based on the above structure, a symmetrically distributed damping structure is formed, enabling the vibration energy to be evenly absorbed in the circumferential direction of the main shaft 5, effectively suppressing the eccentric rotation problem caused by asymmetric vibration. When the main shaft 5 generates periodic vibration due to the imbalance of the grinding wheel, the paired damping rods 421 deform synchronously in the directions with opposite vibration phases, significantly reducing the overall amplitude of the main shaft 5 through the mutual cancellation effect. Experiments show that this structure can reduce the amplitude of the rotational vibration of the main shaft 5 by more than 40%. Especially in the scenario of high-frequency vibration (such as when the linear speed of the grinding wheel exceeds 80 m / s), the surface roughness Ra value of the machined surface is reduced from 0.8 μm to below 0.2 μm.

[0070] Embodiment 4:

[0071] In this embodiment, the error repair model is divided into topological branches, and the topological branches include the bed workpiece branch, the bed grinding head branch, and the column main shaft 5 branch.

[0072] In this embodiment, the error compensation model is established through the following process: taking the partial derivative of the error parameters in the spatial error model, calculating the sensitivity of the error parameters to the machining error, determining the key error terms through the normalization of the sensitivity coefficient, and finally repairing the key error terms through the control unit according to the deviation value ratio of the key error terms.

[0073] In this embodiment, the process of the compensation rod 416 repairing the key error terms of the main shaft 5 is as follows: extracting the angle and displacement of the key error terms, and adjusting the cylinder 415 through the control unit to make the compensation rod 416 output the same displacement at the reverse angle of the key error term angle;

[0074] The process of the centering plate 412 repairing the key error terms of the main shaft 5 is as follows: extracting the angle and displacement of the key error terms, and adjusting the pushing subunit 413 through the control unit to make the centering plate 412 output the displacement ratio at the reverse angle of the key error term angle.

[0075] It can be understood that the bed workpiece branch focuses on the relative position error between the turntable 6 and the workpiece, the bed grinding head branch analyzes the dynamic offset between the grinding head module 3 and the bed, and the column spindle 5 branch quantifies the rotation vibration and geometric deviation of the spindle 5 in the axle box 4. Each branch establishes an independent error parameter set through a local coordinate system.

[0076] For the bed-workpiece branch, the bed is the basic supporting structure of the machine tool, and its deformation error and assembly error will be transmitted to the workpiece through the turntable 6, causing positioning deviation or roundness error of the workpiece; a motion chain model of the bed-turntable 6-workpiece is established through the local coordinate system, and the mapping relationship of the bed geometric error in the workpiece coordinate system is quantified using the homogeneous transformation matrix, so as to identify the systematic error source caused by insufficient bed stiffness or poor thermal stability.

[0077] For the bed grinding head branch, the ideal motion trajectory of the grinding head module 3 relative to the bed is described by the local coordinate system, and the error parameters in the actual motion are compared through the homogeneous transformation matrix to establish the correlation model between the grinding head position error and the surface waviness of the workpiece.

[0078] For the column spindle 5 branch, the corresponding integrated motion chain is the column module 1, the axle box 4, the spindle 5 and its affiliated compensation mechanism (centering unit 41, vibration reduction unit 42). The deviation between the ideal rotation axis of the spindle 5 and the actual motion trajectory is decomposed into various error parameters by aligning the transformation matrix of the local coordinate system, and the error transmission law in the column-axle box 4-spindle 5 chain is analyzed based on the spatial constraint equation. When machining deep holes, the flexural deformation of the spindle 5 will cause the end of the grinding wheel rod to deviate. The model dynamically corrects the real-time posture error of the spindle 5 by combining the column stiffness parameters, the displacement output of the compensation mechanism and the damping coefficient of the vibration reduction unit 42.

[0079] In some embodiments, the ideal motion trajectory includes linear feed and circular interpolation.

[0080] In some embodiments, the error parameters include a pitch error and a yaw error of the guide rail;

[0081] In some embodiments, the geometric error includes, for example, a translation error and an angular error.

[0082] In some embodiments, the error parameter set includes translation error, angular deviation, deformation coefficient, etc.

[0083] In this embodiment, the error repair model includes a spatial error model and an error compensation model. The spatial error model is established through the following process: a local coordinate system is established for each topological branch, and the ideal motion relationship and the actual error relationship of the topological branch are described by a homogeneous transformation matrix. After establishing the spatial constraint equation, the spatial error model is obtained by combining the homogeneous transformation matrix to solve it.

[0084] For the mathematical modeling process of the column spindle 5 branch in this embodiment, the topological structure of the column spindle 5 branch is decomposed into:

[0085] Column axle box 4 sliding pair: The main spindle 5 slides along the guide rail of the column through the axle box, and its geometric errors include the straightness error of the guide rail, the assembly clearance between the axle box 4 and the column (denoted as , , ), and the pitch angle error and yaw angle error during the sliding process.

[0086] Main spindle rotation system: The radial runout error , axial runout and angular yaw of the main spindle 5.

[0087] Dynamic vibration transmission path: When the grinding wheel rotates at high speed, the centrifugal force and cutting reaction force are transmitted to the axle box through the main spindle 5, forming a vibration displacement , which needs to be absorbed by the vibration damping unit 42.

[0088] Function of the compensation mechanism: The centering unit 41 drives the centering plate 412 to correct the center deviation of the main spindle 5 by pushing the sub-unit 413 , and the cylinder of the compensation sub-unit drives the compensation rod to offset the deformation error .

[0089] For the local coordinate system and homogeneous transformation matrix modeling:

[0090] The error transfer of the column spindle branch is quantified through the local coordinate system and homogeneous transformation matrix to obtain the ideal motion model and the actual motion error model:

[0091] Ideal motion model:

[0092] ;

[0093] Among them, is the ideal rotation matrix;

[0094] is the ideal position of the end point of the main spindle 5;

[0095] are the coordinates of the end point of the main spindle 5.

[0096] Actual motion error model:

[0097] The actual motion is affected by multi-source errors and can be decomposed into:

[0098] Column axle box sliding error:

[0099] The translational error of the sliding pair With angular error , its secondary transformation matrix is:

[0100] .

[0101] Spindle rotational error:

[0102] The radial runout of spindle 5 and axial runout can be expressed as a displacement error matrix:

[0103] ;

[0104] wherein, is the rotational angle, is the angular yaw.

[0105] Dynamic vibration error:

[0106] Vibration displacement is modeled as a time-varying disturbance term:

[0107] .

[0108] For the spatial error model:

[0109] is expressed as the accumulation of each error term:

[0110] .

[0111] Taking the error compensation model of the centering unit 41 as an example, the centering unit 41 adjusts the displacement of the centering plate 412 by pushing the sub-unit 413 to correct the spindle center deviation , assuming the compensation displacement of the centering plate is , its force model is:

[0112] .

[0113] wherein, is the transmission coefficient of the centering rod 414, and the control unit calculates the to be compensated according to the output by the error model:

[0114] .

[0115] The column spindle branch is modeled by the HTM of the local coordinate system and compensated by multi-mechanism collaboration. The spindle error is decomposed into quantifiable parameters, and precise correction is achieved based on sensitivity analysis. Its mathematical framework not only supports the global solution of the error model but also provides a theoretical basis for real-time control, ultimately enabling the machine tool to achieve high-precision performance in high-speed, heavy-load, and high-precision scenarios.

[0116] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A high-precision numerically controlled vertical grinding machine, characterized in that, It includes a column module, a bed module, and a grinding head module. The column module is connected to the bed module. A turntable is provided on the bed. A spindle box is slidably provided on the column. A main shaft is provided in the spindle box, and the main shaft is connected to the grinding head module. A topology repair module is also provided in the spindle box; The topology repair module includes a control unit on which an error repair model is carried. The topology repair module also includes a centering unit and a vibration damping unit provided inside the spindle box. The centering unit is also connected to the outer periphery of the main shaft and is used to compensate for the center error of the main shaft. The vibration damping unit is also connected to the outer periphery of the main shaft and is used to reduce the rotational vibration of the main shaft; The centering unit includes a fixed seat fixedly connected to the spindle box. A centering plate is rotatably provided on the fixed seat. The centering plate is sleeved on the main shaft. The fixed seat is also provided with a plurality of pushing sub-units. A centering rod is hingedly provided at the end of the pushing sub-unit. The free end of the centering rod is hinged to the centering plate. The pushing sub-unit is in communication connection with the control unit; The centering unit also includes a compensation sub-unit. The compensation sub-unit includes a cylinder provided on the fixed seat. The output end of the cylinder is connected with a compensation rod. The compensation rod is sleeved on the main shaft; The vibration damping unit includes a plurality of vibration damping rods fixedly connected to the upper end surface of the spindle box. The free ends of the vibration damping rods are connected with a vibration damping plate. The vibration damping plate is sleeved on the main shaft.

2. The high-precision numerically controlled vertical grinding machine according to claim 1, wherein The compensation rod, the centering plate, and the vibration damping plate are all sleeved on the main shaft through bearings.

3. The high-precision numerically controlled vertical grinding machine according to claim 1, characterized in that The vibration damping rods are arranged in pairs.

4. A high-precision numerically controlled vertical grinding machine according to claim 2, characterized in that, The error repair model is divided into topology branches. The topology branches include a bed workpiece branch, a bed grinding head branch, and a column main shaft branch.

5. The high-precision numerically controlled vertical grinding machine according to claim 4, wherein, The error repair model includes a spatial error model and an error compensation model. The spatial error model is established through the following process: A local coordinate system is established for each topology branch, and the ideal motion relationship and actual error relationship of the topology branch are described by a homogeneous transformation matrix. Then, after establishing a spatial constraint equation and combining it with the homogeneous transformation matrix, a simultaneous solution is obtained to get the spatial error model.

6. The high-precision numerically controlled vertical grinding machine according to claim 5, wherein The error compensation model is established through the following process: The partial derivatives of the error parameters in the spatial error model are calculated to calculate the sensitivity of the error parameters to the machining error, and the key error terms are determined through sensitivity coefficient normalization. Finally, the control unit repairs the key error terms according to the deviation value ratio of the key error terms.

7. The high-precision numerically controlled vertical grinding machine according to claim 6, characterized in that, The process of the compensation rod repairing the key error terms of the main shaft is: Extract the angle and displacement of the key error terms, and adjust the cylinder through the control unit to make the compensation rod output the same displacement at the reverse angle of the key error term angle; The process of the centering plate repairing the key error terms of the main shaft is: Extract the angle and displacement of the key error terms, and adjust the pushing sub-unit through the control unit to make the centering plate output the displacement ratio at the reverse angle of the key error term angle.

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