A grinding method for a large eccentric cross shaft

Abstract

This invention discloses a grinding method for a large eccentric cross shaft, relating to the field of grinding technology. By reserving an axial extension structure at the end of any journal of the cross shaft as a clamping part, it is clamped in a three-jaw chuck of a milling-turning machining center, enabling all grinding to be completed in a single clamping, avoiding cumulative errors caused by multiple positioning. A first motor on the turret drives a first grinding wheel to continuously grind the outer diameter and transition radius of the first and second journals along the X-direction, while the three-jaw chuck rotates at low speed in conjunction with an envelope motion. The workpiece posture is adjusted so that the third and fourth journals are parallel to the second motor shaft. The second grinding wheel rotates at high speed while being driven by the turret to revolve around the third journal, achieving precision forming grinding. The three-jaw chuck rotates the workpiece 180°, grinding the fourth journal in the same manner. After all four journals are machined, the machine tool automatically removes the clamping part, obtaining a complete cross shaft structure.

Description

Technical Field

[0001] This invention relates to the field of grinding technology, and in particular to a grinding method for a large eccentric cross shaft. Background Technology

[0002] Cross shafts are key core components in various precision transmission devices and heavy machinery systems, widely used in high-precision universal couplings, aerospace actuators, robot joints, precision testing equipment, and heavy equipment in metallurgy, mining, and other fields. Among them, the large eccentric cross shaft refers to a special structural form in which the four journals have a significant eccentricity relative to the central body. This design is typically used to meet specific spatial layout, motion transmission, or mechanical performance requirements. Due to its highly asymmetrical geometry, extremely uneven mass distribution, and complex spatial orientation of each journal, this type of part is a typical example of extremely difficult to manufacture in the field of precision manufacturing.

[0003] In existing machining processes, the external cylindrical grinding of large eccentric cross shafts faces numerous technical bottlenecks. Because the four journals are spatially orthogonal and have a large eccentricity, their axes are not in the same plane, making it impossible to complete the machining of all surfaces in a single setup on a conventional grinding machine. Traditional methods require repeated disassembly and repositioning of the workpiece between multiple operations, and different shapes and sizes of grinding wheels must be changed for each functional area of ​​a journal. However, under current processes, the complete grinding of all four journals often requires up to twelve repeated setups. Each setup inevitably introduces positioning errors, clamping deformation, and datum offsets, leading to significant cumulative errors and making it difficult to guarantee the geometric accuracy and assembly interchangeability of the final product. Summary of the Invention

[0004] This application provides a grinding method for a large eccentric cross shaft, which solves the technical problem in the prior art that the cross shaft cannot complete all grinding work in one clamping, resulting in poor grinding accuracy.

[0005] This application provides a grinding method for a large eccentric cross shaft, the method comprising:

[0006] An axially extended structure is reserved at one end of any journal of the cross shaft as a clamping part;

[0007] The clamping part is clamped in the three-jaw chuck of the milling and turning machining center to fix the geometric center of the cross shaft and use it as a unified machining reference.

[0008] The first motor mounted on the turret drives the first grinding wheel to continuously grind the outer diameter and transition R angle of the first and second journals on the same straight line along the X direction, wherein the first grinding wheel and the three-jaw chuck both rotate.

[0009] After grinding the first and second journals, the third and fourth journals are adjusted to be parallel to the shaft of the second motor, driving the second grinding wheel on the second motor to rotate, and the turret drives the second grinding wheel to revolve around the third journal to grind the third journal;

[0010] After the third journal is polished, rotate the cross shaft 180° using a three-jaw chuck and polish the fourth journal in the same way.

[0011] After all four journals of the cross shaft are ground, the milling and turning machining center removes the clamping part on the cross shaft to obtain the ground cross shaft structure.

[0012] In some embodiments, the first journal and the second journal are coaxial with the axis of the clamping portion.

[0013] In some embodiments, the third journal and the fourth journal are spatially perpendicular to the axis of the clamping portion.

[0014] In some embodiments, when the first grinding wheel grinds the first journal and the second journal, the speed of the first motor is 20,000-30,000 RPM, and the speed of the three-jaw chuck is 10-300 RPM.

[0015] In some embodiments, when the second grinding wheel grinds the third and fourth journals, the rotation speed of the second motor is 20,000-30,000 RPM, and the revolution angular velocity of the second motor is 0.5°-5° / second.

[0016] In some embodiments, the roughness of the first journal, the second journal, the third journal, and the fourth journal is 0.4 micrometers.

[0017] In some embodiments, the grinding allowance of the first journal, the second journal, the third journal, and the fourth journal is 0.1 mm to 0.15 mm per side.

[0018] In some embodiments, the length of the cross shaft ranges from 25mm to 40mm, the diameter of the first journal, the second journal, the third journal, and the fourth journal ranges from 5mm to 12mm, and the length of the clamping part ranges from 8mm to 20mm.

[0019] This application also provides a workpiece for grinding with a large eccentric cross shaft, the workpiece including a cross shaft body, and a clamping portion extended from any one journal end of the cross shaft body.

[0020] This application also provides a large eccentric cross-shaft grinding device, the grinding device comprising:

[0021] The three-jaw chuck of the milling and turning machining center is used to clamp the clamping part on the cross shaft body;

[0022] A base is mounted on a turret of a milling and turning machining center, and the turret is used to drive the base to move.

[0023] A first motor is mounted on the base, and a first grinding wheel is mounted on the output shaft of the first motor. The rotating shaft of the first motor is parallel to the rotating shaft of the clamping part.

[0024] A second motor is mounted on the base, and a second grinding wheel is mounted on the output shaft of the second motor. The rotation shaft of the second motor is perpendicular to the rotation shaft of the clamping part.

[0025] The beneficial effects of this application are as follows:

[0026] The grinding method provided by this invention avoids the reduction in grinding accuracy caused by changing the clamping position. By clamping the cross shaft once, all four journals can be ground, thereby improving the grinding accuracy of the cross shaft. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention.

[0028] Figure 1 A schematic diagram of the workpiece structure for grinding provided in this application;

[0029] Figure 2 A schematic diagram of the grinding apparatus provided in this application.

[0030] Among them, 10 is the cross shaft body; 11 is the first journal; 12 is the second journal; 13 is the third journal; 14 is the fourth journal; 15 is the clamping part; 21 is the three-jaw chuck; 22 is the base; 23 is the first motor; 24 is the first grinding wheel; 25 is the second motor; and 26 is the second grinding wheel. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0033] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0034] This application provides a grinding method for a large eccentric cross shaft, which solves the technical problem in the prior art that the cross shaft cannot complete all grinding work in one clamping, resulting in poor grinding accuracy.

[0035] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0036] The grinding method for a large eccentric cross shaft provided in this application includes:

[0037] An axially extended structure is reserved at one end of any journal of the cross shaft as a clamping part 15;

[0038] The clamping part 15 is clamped in the three-jaw chuck 21 of the milling and turning machining center to fix the geometric center of the cross shaft and use it as a unified machining reference.

[0039] The first motor 23 mounted on the turret drives the first grinding wheel 24 to continuously grind the outer diameter and transition R angle of the first journal 11 and the second journal 12 on the same straight line along the X direction, wherein the first grinding wheel 24 and the three-jaw chuck 21 both rotate.

[0040] After grinding the first journal 11 and the second journal 12, the third journal 13 and the fourth journal 14 are adjusted to be parallel to the rotating shaft of the second motor 25, and the second grinding wheel 26 on the second motor 25 is driven to rotate. The turret drives the second grinding wheel 26 to revolve around the third journal 13 to grind the third journal 13.

[0041] The first journal 11, the second journal 12, the third journal 13, and the fourth journal 14 are spatially orthogonal, with an eccentricity of 9mm-12mm, accounting for more than 50% of the total height, which is a large eccentricity small size structure.

[0042] After the third journal 13 is polished, the cross shaft is rotated 180° by the three-jaw chuck 21, and the fourth journal 14 is polished in the same way.

[0043] After all four journals of the cross shaft are ground, the milling and turning machining center removes the clamping part 15 on the cross shaft to obtain the ground cross shaft structure.

[0044] This avoids the reduction in grinding accuracy caused by changing the clamping position. By clamping the cross shaft once, all four journals can be ground, thereby improving the grinding accuracy of the cross shaft.

[0045] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0046] Example 1: Grinding of a standard large eccentric cross shaft

[0047] In this embodiment, the cross shaft workpiece is a forging, and the length of the cross shaft ranges from 25mm to 40mm. The diameters of the first journal 11, the second journal 12, the third journal 13, and the fourth journal 14 range from 5mm to 12mm, and the length of the clamping part 15 ranges from 8mm to 20mm. In this embodiment, the distance from the end face of the first journal 11 to the end face of the second journal 12 is 30mm, and the eccentricity is 10mm. The rough machining diameter of the four journals is 6.2mm, with a 0.15mm allowance for single-sided grinding. The clamping part 15 is coaxial with the first journal 11 and the second journal 12, and the length of the clamping part 15 is 12mm. The third journal 13 and the fourth journal 14 are spatially perpendicular to the axis of the clamping part 15.

[0048] The grinding apparatus includes a milling and turning machining center with an integrated base 22 mounted on the turret. A first motor 23 and a second motor 25 are also mounted on the base 22. The first motor 23 drives a first grinding wheel 24 for grinding a coaxial first journal 11 and a second journal 12; the second motor 25 drives a second grinding wheel 26 for grinding a third journal 13 and a fourth journal 14.

[0049] The processing steps are as follows:

[0050] Clamping: Securely clamp the clamping part 15 of the cross shaft workpiece in the three-jaw chuck 21 and align the geometric center.

[0051] Grinding the first journal 11 and the second journal 12: Start the first motor 23 and the three-jaw chuck 21. The speed setting range of the first motor 23 is 20000-30000 RPM. In this embodiment, the speed of the first motor 23 is set to 25000 RPM. The speed setting range of the three-jaw chuck 21 is 10-300 RPM. In this embodiment, the speed of the three-jaw chuck 21 is set to 50 RPM. Control the turret to feed along the X-axis, that is, in the direction perpendicular to the rotation axis of the clamping part 15, so that the first grinding wheel 24 continuously grinds the rotating first journal 11 and the second journal 12 until the size reaches φ6.00mm and the surface roughness Ra≤0.4μm.

[0052] Grinding the third journal 13: The chuck stops rotating and rotates precisely 90° to make the axis of the third journal 13 parallel to the axis of the second grinding wheel 26; the second motor 25 is started, and the rotation speed of the second motor 25 is set in the range of 20000-30000 RPM. In this embodiment, the rotation speed of the second motor 25 is set to 25000 RPM, and the turret is programmed to drive the second grinding wheel 26 to revolve around the axis of the third journal 13. The angular velocity of the second motor 25 is set in the range of 0.5°-5° / second. In this embodiment, the angular velocity of the second motor 25 is 2° / second, until the grinding is completed.

[0053] Grinding the fourth journal 14: After the third journal 13 has been ground, rotate the three-jaw chuck 21 180° to bring the fourth journal 14 to the machining position, and repeat the operation of the previous step.

[0054] The grinding allowance of the first journal 11, the second journal 12, the third journal 13 and the fourth journal 14 is 0.1 mm to 0.15 mm on each side.

[0055] Cut off the clamping part 15: Use a cutting tool on a machining center to cut off the clamping part 15 and finish machine the end face.

[0056] The coaxiality of the two pairs of journals of the finished cross shaft is less than 0.005mm, and the perpendicularity of the two pairs of journals is less than 0.008mm, which is much higher than that of traditional methods.

[0057] Example 2: Grinding of small-sized, high-precision cross shafts

[0058] In this embodiment, the total height of the cross shaft is 26mm, the journal diameter is 5.2mm, the eccentricity is 9mm, the clamping part 15 is 8mm long, and the single-sided allowance is 0.1mm.

[0059] The processing procedure is the same as in Example 1, but the process parameters are more refined:

[0060] When grinding the first journal 11 and the second journal 12: set the speed of the first motor 23 to 30000 RPM and the speed of the chuck to 10 RPM.

[0061] When grinding the third journal 13 and the fourth journal 14: set the second motor 25 to a speed of 30000 RPM and a revolution angular velocity of 0.5° / second.

[0062] The final product has a journal diameter tolerance controlled within ±0.0015mm and a surface roughness Ra of 0.2μm.

[0063] Example 3: Variation of the grinding device

[0064] In this embodiment, the first motor 23 and the second motor 25 on the base 22 can also be arranged vertically along the Z-axis of the turret, instead of being arranged side by side as shown in the figure. As long as the movement of the turret enables the first grinding wheel 24 and the second grinding wheel 26 to reach their respective grinding stations, the purpose of this invention can be achieved. This layout makes the structure more compact and adaptable to different equipment spaces.

[0065] Alternatively, in other specific embodiments, the first motor 23 and the second motor 25 can be arranged at a 90° angle on the base 22. When the first and second journals 12 need to be ground, the control system drives the base 22 to rotate, so that the first motor 23 drives the first grinding wheel 24 into the horizontal grinding position. After the grinding is completed, the turntable rotates 90° to precisely switch the second motor 25 and the second grinding wheel 26 to the vertical grinding position.

[0066] A better solution would be to arrange the first motor 23 and the second motor 25 at a 180° angle on the base 22. After grinding is completed, the turntable can be rotated 180° to switch the grinding position, making the center of gravity of the base 22 more stable and avoiding interference between the first grinding wheel 24 and the second grinding wheel 26.

[0067] The first motor 23 and the second motor 25 are arranged horizontally on the end face of the base 22. Through a movement of one degree of freedom, the spatial interference problem between the two grinding wheels is solved. This is especially suitable for scenarios where the grinding wheel size is large or the working space is small, thus improving the safety and reliability of the equipment movement.

[0068] Of course, as an alternative, in other specific embodiments, the first motor 23 and the second motor 25 can be used as independent modules. Both the first motor 23 and the second motor 25 can be quickly installed onto or removed from the base 22 via a standard interface. Users can quickly replace the grinding wheel motor modules of different specifications according to the size of different models of cross shafts and grinding process requirements, enabling a single machine to adapt to the flexible production needs of multiple varieties and small batches, greatly improving the utilization rate of the equipment.

[0069] Alternatively, in other specific embodiments, only one drive motor can be provided. This drive motor is mounted on the base 22 and transmits power to the first grinding wheel 24 axis and the second grinding wheel 26 axis respectively through a transmission system. The transmission system can be a clutch or an electronically controlled switching device to selectively connect power to the first grinding wheel 24 axis or the second grinding wheel 26 axis, reducing one motor and lowering manufacturing costs and overall weight. The transmission system is a commonly used mechanism in the art, and its working principle and application are conventional technologies in the field. Its specific settings and structural connections will not be described in detail here.

[0070] like Figure 1 As shown, this application also provides a workpiece for grinding a large eccentric cross shaft. The workpiece includes a cross shaft body 10, and a clamping part 15 is extended from any one of the journal ends of the cross shaft body 10, realizing reliable clamping and unified reference positioning on a milling and turning machining center. This clamping part 15 serves as a temporary process structure, allowing the workpiece to complete continuous grinding of four journals in a single clamping operation. This effectively avoids the cumulative errors caused by repeated disassembly and repositioning in traditional multi-process machining, significantly improving the geometric accuracy such as positional accuracy, perpendicularity, and symmetry between the journals. Simultaneously, this design solves the problem of vibration or "throwing out" during high-speed rotation due to uneven mass distribution in large eccentric structures, ensuring the stability of the grinding process. The clamping part 15 can be easily removed after all grinding is completed without affecting the structural integrity and functional performance of the final part. This workpiece structure is particularly suitable for manufacturing small-sized, high-precision robot joint cross shafts, providing a fundamental guarantee for achieving high consistency and high efficiency precision grinding.

[0071] like Figure 2 As shown, this application also provides a large eccentric cross-spindle grinding apparatus, the grinding apparatus comprising:

[0072] The three-jaw chuck 21 of the milling and turning machining center is used to clamp the clamping part 15 on the cross shaft body 10.

[0073] The base 22 is mounted on the turret of the mill-turn machining center. The turret is used to drive the base 22 to move. The mill-turn machining center is an existing product, and the turret on it used to control the three-dimensional spatial movement of the base 22 is also existing technology, which will not be described in detail here.

[0074] A first motor 23 is mounted on the base 22. A first grinding wheel 24 is mounted on the output shaft of the first motor 23. The rotation shaft of the first motor 23 is parallel to the rotation shaft of the clamping part 15.

[0075] The second motor 25 is mounted on the base 22. A second grinding wheel 26 is mounted on the output shaft of the second motor 25. The rotation shaft of the second motor 25 is perpendicular to the rotation shaft of the clamping part 15.

[0076] This device completes the grinding of all journals in one clamping, avoiding the cumulative errors caused by multiple disassembly and repositioning. It significantly improves the geometric accuracy and surface quality consistency between journals, such as perpendicularity, symmetry, and positional accuracy. At the same time, it reduces the frequency of grinding wheel replacement and dressing, thereby improving equipment utilization and processing efficiency.

[0077] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0078] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A grinding method for a large eccentric cross shaft, characterized in that, The method includes: An axially extended structure is reserved at one end of any journal of the cross shaft as a clamping part; The clamping part is clamped in the three-jaw chuck of the milling and turning machining center to fix the geometric center of the cross shaft and use it as a unified machining reference. The first motor mounted on the turret drives the first grinding wheel to continuously grind the outer diameter and transition R angle of the first and second journals on the same straight line along the X direction, wherein the first grinding wheel and the three-jaw chuck both rotate. After grinding the first and second journals, the third and fourth journals are adjusted to be parallel to the shaft of the second motor, driving the second grinding wheel on the second motor to rotate, and the turret drives the second grinding wheel to revolve around the third journal to grind the third journal; After the third journal is polished, rotate the cross shaft 180° using a three-jaw chuck and polish the fourth journal in the same way. After all four journals of the cross shaft are ground, the milling and turning machining center removes the clamping part on the cross shaft to obtain the ground cross shaft structure.

2. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, The first journal and the second journal are coaxial with the axis of the clamping part.

3. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, The third and fourth journals are spatially perpendicular to the axis of the clamping part.

4. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, When the first grinding wheel grinds the first journal and the second journal, the speed of the first motor is 20,000-30,000 RPM, and the speed of the three-jaw chuck is 10-300 RPM.

5. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, When the second grinding wheel grinds the third and fourth journals, the rotation speed of the second motor is 20,000-30,000 RPM, and the revolution angular velocity of the second motor is 0.5°-5° / second.

6. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, The roughness of the first journal, the second journal, the third journal, and the fourth journal is 0.4 micrometers.

7. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, The grinding allowance for the first journal, the second journal, the third journal, and the fourth journal is 0.1 mm to 0.15 mm on each side.

8. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, The cross shaft has a length range of 25mm-40mm, the diameters of the first journal, second journal, third journal, and fourth journal range of 5mm-12mm, and the clamping part has a length range of 8mm-20mm.

9. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, The workpiece being ground in the method includes a cross shaft body, and a clamping part is provided at any one end of the journal of the cross shaft body.

10. The grinding method for a large eccentric cross shaft as described in claim 1, characterized in that, The grinding apparatus in the method includes: The three-jaw chuck of the milling and turning machining center is used to clamp the clamping part on the cross shaft body; A base is mounted on a turret of a milling and turning machining center, and the turret is used to drive the base to move. A first motor is mounted on the base, and a first grinding wheel is mounted on the output shaft of the first motor. The rotation shaft of the first motor is parallel to the rotation shaft of the clamping part. A second motor is mounted on the base, and a second grinding wheel is mounted on the output shaft of the second motor. The rotation shaft of the second motor is perpendicular to the rotation shaft of the clamping part.

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