Grinding method for large eccentric cross shaft

Abstract

The invention discloses a grinding method for a large eccentric cross shaft, and relates to the technical field of grinding processes. An axial extension structure is reserved at the end of any shaft neck of the cross shaft to serve as a clamping part, the cross shaft is clamped in a three-jaw chuck of a turning and milling combined machining center, all grinding is completed through one-time clamping, and accumulative errors caused by multiple times of positioning are avoided; a first motor on the tool turret is used for driving a first grinding wheel to continuously grind the outer circle and the transition R angle of the first shaft neck and the second shaft neck on the same straight line in the X direction, and the three-jaw chuck rotates at a low speed to be matched with enveloping motion; the posture of the workpiece is adjusted, a third journal and a fourth journal are parallel to a rotating shaft of a second motor, the second grinding wheel is driven by a tool turret to revolve around the third journal while rotating at a high speed, and precise forming grinding is achieved; the three-jaw chuck drives the workpiece to rotate by 180 degrees, and the fourth journal is ground in the same mode; and after the four journals are all machined, a machine tool automatically cuts off the clamping parts, and a complete cross shaft structure is obtained.

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 the first and second shaft necks are ground, the third and fourth shaft necks are adjusted to be parallel to the rotating shaft of the second motor, the second motor on the second grinding wheel is driven to rotate, and the knife tower drives the second grinding wheel to revolve around the third shaft neck to polish the third shaft neck;

[0010] After the third shaft neck is polished, the cross shaft is rotated by 180° through the three-jaw chuck, and the fourth shaft neck is polished in the same way;

[0011] After the four shaft necks of the cross shaft are all ground, the clamping part on the cross shaft is cut by the turning and milling combined machining center to obtain the ground cross shaft structure.

[0012] In some embodiments, the first and second shaft necks are coaxial with the axis of the clamping part.

[0013] In some embodiments, the third and fourth shaft necks are spatially perpendicular to the axis of the clamping part.

[0014] In some embodiments, when the first grinding wheel polishes the first and second shaft necks, the rotating speed of the first motor is 20000-30000 RPM, and the rotating speed of the three-jaw chuck is 10-300 RPM.

[0015] In some embodiments, when the second grinding wheel polishes the third and fourth shaft necks, the rotating speed of the second motor is 20000-30000 RPM, and the revolving angular velocity of the second motor is 0.5°-5° / s.

[0016] In some embodiments, the roughness of the first, second, third and fourth shaft necks is 0.4 microns.

[0017] In some embodiments, the grinding allowance of the first, second, third and fourth shaft necks is 0.1mm to 0.15mm on one side.

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

[0019] The application also provides a workpiece for grinding a large eccentric cross shaft, which comprises a cross shaft body, and a clamping part arranged at an arbitrary shaft neck end of the cross shaft body.

[0020] The application also provides a grinding device for a large eccentric cross shaft, which comprises:

[0021] A three-jaw chuck of a turning and milling combined machining center, used to clamp the clamping part on the cross shaft body.

[0022] A base is installed on a tool turret of a turning-milling combined machining center, and the tool turret is used to drive the base to move;

[0023] A first motor is installed on the base, a first grinding wheel is installed on an output shaft of the first motor, and a rotating shaft of the first motor is parallel to a rotating shaft of the clamping part;

[0024] A second motor is installed on the base, a second grinding wheel is installed on an output shaft of the second motor, and a rotating shaft of the second motor is perpendicular to the rotating shaft of the clamping part.

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

[0026] The grinding method provided by the present application avoids the reduction of grinding precision caused by the replacement of the clamping position, and the grinding of all the four shaft necks of the cross shaft is completed through one-time clamping of the cross shaft, thereby improving the grinding precision of the cross shaft. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application.

[0028] Figure 1 The structure schematic diagram of the workpiece provided by the present application is shown in the figure;

[0029] Figure 2 The structure schematic diagram of the grinding device provided by the present application is shown in the figure.

[0030] In the figure, 10 is a cross shaft body, 11 is a first shaft neck, 12 is a second shaft neck, 13 is a third shaft neck, 14 is a fourth shaft neck, 15 is a clamping part, 21 is a three-jaw chuck, 22 is a base, 23 is a first motor, 24 is a first grinding wheel, 25 is a second motor, and 26 is a second grinding wheel. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] It should be noted that all directionality indications (such as up, down, left, right, front, back, and the like) in the embodiments of the present application are only used to explain the relative position relationship, movement condition and the like between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directionality indications also change accordingly.

[0033] In addition, the description involving "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0034] The technical scheme in the embodiments of the present application solves the technical problem that the cross shaft in the prior art cannot realize all grinding work through one clamping, resulting in poor grinding precision.

[0035] The technical scheme in the embodiments of the present application solves the technical problem that the cross shaft in the prior art cannot realize all grinding work through one clamping, resulting in poor grinding precision.

[0036] The technical scheme in the embodiments of the present application solves the technical problem that the cross shaft in the prior art cannot realize all grinding work through one clamping, resulting in poor grinding precision.

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

[0038] The clamping part 15 is clamped in a three-jaw chuck 21 of a turning-milling combined machining center, so that the geometric center of the cross shaft is fixed and serves as a unified machining reference;

[0039] A first motor 23 installed on a tool turret drives a first grinding wheel 24 to rotate along the X direction to continuously grind the outside circle and transition R angle of the first journal 11 and the second journal 12 on the same straight line, wherein the first grinding wheel 24 and the three-jaw chuck 21 both rotate;

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

[0041] The first journal 11, the second journal 12, the third journal 13 and the fourth journal 14 are distributed in space in an orthogonal manner, the eccentricity is 9mm-12mm, and the proportion of the eccentricity to the total height is more than 50%, which is a large eccentricity and small size structure.

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

[0043] After the four journals of the cross axle are all polished, the clamping portion 15 on the cross axle is cut off by the turning-milling combined machining center to obtain the polished cross axle structure.

[0044] The replacement of the clamping position is avoided, the four journals are all polished by clamping the cross axle once, and thus the polishing precision of the cross axle is improved.

[0045] In order to better understand the above technical solutions, the above technical solutions will be described in detail in combination with the drawings of the specification and specific embodiments.

[0046] Example one: grinding of a standard large eccentric cross axle

[0047] In this embodiment, the cross axle workpiece is a forge piece, the length of the cross axle ranges from 25 mm to 40 mm, the diameters of the first journal 11, the second journal 12, the third journal 13 and the fourth journal 14 range from 5 mm to 12 mm, and the length of the clamping portion 15 ranges from 8 mm to 20 mm. In this embodiment, the distance from the end face of the first journal 11 to the end face of the second journal 12 is 30 mm, and the eccentricity is 10 mm; the rough machining diameters of the four journals are 6.2 mm, and the reserved single-side polishing allowance is 0.15 mm; the clamping portion 15 is coaxial with the first journal 11 and the second journal 12, the length of the clamping portion 15 is 12 mm, and the third journal 13 and the fourth journal 14 are perpendicular to the axis of the clamping portion 15 in space.

[0048] The grinding device includes a turning-milling combined machining center, an integrated base 22 is installed on the tool turret, the first motor 23 and the second motor 25 are installed on the base 22 at the same time. The first motor 23 drives the first grinding wheel 24, which is used for grinding the coaxial first journal 11 and the second journal 12; the second motor 25 drives the second grinding wheel 26, which is used for grinding the third journal 13 and the fourth journal 14.

[0049] The machining steps are as follows:

[0050] Clamping: firmly clamp the clamping portion 15 of the cross axle workpiece in the three-jaw chuck 21, and find 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 rotation speed of the first motor 23 is set to 20000-30000 RPM, in this embodiment, the rotation speed of the first motor 23 is set to 25000 RPM, the rotation speed of the three-jaw chuck 21 is set to 10-300 RPM, in this embodiment, the rotation speed of the three-jaw chuck 21 is set to 50 RPM. Control the tool turret to feed along the X axis, that is, the direction perpendicular to the rotation axis of the clamping part 15, so that the first grinding wheel 24 continuously grinds the first journal 11 and the second journal 12 in rotation until the size reaches φ6.00mm, and the surface roughness Ra≤0.4μm.

[0052] Grinding the third journal 13: stop the rotation of the chuck and rotate it accurately by 90°, so that the axis of the third journal 13 is parallel to the axis of the second grinding wheel 26; start the second motor 25, the rotation speed of the second motor 25 is set to 20000-30000 RPM, in this embodiment, the rotation speed of the second motor 25 is set to 25000 RPM, and the tool turret is programmed to drive the second grinding wheel 26 to revolve around the axis of the third journal 13, the revolution angular velocity of the second motor 25 is set to 0.5°-5° / s, in this embodiment, the revolution angular velocity of the second motor 25 is 2° / s, until the grinding is completed.

[0053] Grinding the fourth journal 14: after the third journal 13 is ground, rotate the three-jaw chuck 21 by 180°, so that the fourth journal 14 reaches 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 0.1mm to 0.15mm on one side.

[0055] Cutting the clamping part 15: use the turning tool on the machining center to cut and finish the end face of the clamping part 15.

[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 in precision than the traditional method.

[0057] Example two: grinding of small-size high-precision cross shaft

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

[0059] The machining process is the same as in Example 1, but the process parameters are more precise:

[0060] When grinding the first journal 11 and the second journal 12: set the rotation speed of the first motor 23 to 30000 RPM, and the rotation 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 rotate at 30000 RPM, and the angular velocity of revolution to be 0.5° / s.

[0062] The final product journal diameter tolerance is controlled within ±0.0015mm, and the surface roughness Ra reaches 0.2μm.

[0063] Example three: modification 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 up and down along the Z-axis direction of the tool turret, rather than the parallel arrangement shown in the figure. As long as the first grinding wheel 24 and the second grinding wheel 26 can reach the respective grinding stations through the movement of the tool turret, the purpose of the present application can be achieved, and such a layout makes the structure more compact and adapts to different equipment spaces.

[0065] Alternatively, in other specific embodiments, the first motor 23 and the second motor 25 can also be arranged at a 90° angle on the base 22. When grinding the first and second journals 12 is required, the control system drives the base 22 to rotate, so that the first motor 23 drives the first grinding wheel 24 to enter the horizontal grinding station; after grinding is completed, the rotary table is rotated by 90°, and the second motor 25 and the second grinding wheel 26 are precisely switched to the vertical grinding position.

[0066] Of course, a better solution is to arrange the first motor 23 and the second motor 25 at a 180° angle on the base 22. After grinding is completed, the rotary table is rotated by 180°, which can achieve the switching of the grinding position, so that the center of gravity of the base 22 is more stable, and the mutual interference between the first grinding wheel 24 and the second grinding wheel 26 is avoided.

[0067] Arranging the first motor 23 and the second motor 25 horizontally on the end face of the base 22 solves the problem of spatial interference between the two grinding wheels through one degree of freedom movement, which is especially suitable for scenarios where the size of the grinding wheel is large or the working space is small, and improves 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 also be arranged as independent modules. The first motor 23 and the second motor 25 can be quickly installed on or detached from the base 22 through a standard interface. Users can quickly replace grinding wheel motor modules of different specifications according to the size of different types of cross shafts and grinding process requirements, so that one device can adapt to the flexible production needs of multiple varieties and small batches, greatly improving the utilization rate of the device.

[0069] Alternatively, in other embodiments, only one driving motor can also be provided, which is installed on the base 22 and transmits power to the first grinding wheel 24 shaft and the second grinding wheel 26 shaft through a transmission system. The transmission system can be a clutch or an electrically controlled switching device to selectively connect power to the first grinding wheel 24 shaft or the second grinding wheel 26 shaft, thereby reducing one motor and reducing manufacturing cost and overall weight. The transmission system is a commonly used mechanism in the art, and its working principle and application belong to the conventional technology in the art, and therefore, the specific settings and the connection relationship between the structures will not be described here.

[0070] As shown in Figure 1 The application also provides a workpiece for grinding a large eccentric cross shaft, which comprises a cross shaft body 10, and a clamping portion 15 is provided at any one of the journal ends of the cross shaft body 10 in an extended manner, so as to realize reliable clamping and unified reference positioning on a turning-milling combined machining center. The clamping portion 15 serves as a temporary process structure, so that the workpiece can complete continuous grinding of the four journal ends under one-time clamping, thereby effectively avoiding cumulative errors caused by repeated disassembly and repositioning in traditional multi-process machining, and significantly improving the geometric precision such as position degree, perpendicularity and symmetry between the journal ends. Meanwhile, the design solves the problem that the large eccentric structure is prone to vibration or “throwing out” during high-speed rotation due to uneven mass distribution, thereby ensuring the stability of the grinding process. The clamping portion 15 can be conveniently cut off after all grinding is completed, without affecting the structural integrity and functional performance of the final part. The workpiece structure is particularly suitable for manufacturing cross shafts for robot joints with small size and high precision, and provides a basic guarantee for realizing high consistency and high efficiency of precision grinding.

[0071] As shown in Figure 2 The application also provides a grinding device for a large eccentric cross shaft, which comprises:

[0072] A three-jaw chuck 21 of the turning-milling combined machining center, which is used to clamp the clamping portion 15 on the cross shaft body 10;

[0073] A base 22, which is installed on a tool turret of the turning-milling combined machining center, and the tool turret is used to drive the base 22 to move. The turning-milling combined machining center is a product in the prior art, and the tool turret used to control the three-dimensional space movement of the base 22 also belongs to the prior art, and therefore, the description will not be repeated here.

[0074] A first motor 23, which is installed on the base 22, and a first grinding wheel 24 is installed on the output shaft of the first motor 23, and the rotating shaft of the first motor 23 is parallel to the rotating shaft of the clamping portion 15;

[0075] A second motor 25 is mounted on the base 22, and a second grinding wheel 26 is mounted on an output shaft of the second motor 25, and a rotating shaft of the second motor 25 is perpendicular to a rotating shaft of the clamping part 15.

[0076] The device can complete the grinding of all journal by one clamping, avoid the cumulative error caused by multiple dismounting and repositioning, significantly improve the geometric precision and surface quality consistency between the journal, such as perpendicularity, symmetry, position, and reduce the frequency of grinding wheel replacement and the number of dressing, improve the utilization and processing efficiency of the equipment.

[0077] Although preferred embodiments of the application have been described herein, changes and modifications can be suggested to one skilled in the art, and it is intended that the application encompass such changes and modifications as fall within the scope of the appended claims.

[0078] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A method of grinding a large-eccentricity cross axle, characterized by, The method comprises: Reserve an axial extension structure as a clamping part at any one of the journal end of the cross shaft; Clamp the clamping part in the three-jaw chuck of the turning-milling combined machining center to fix the geometric center of the cross shaft and serve as a unified machining reference; Use the first motor installed on the tool turret to drive the first grinding wheel to continuously grind the first journal and the second journal on the same straight line in the X direction, wherein the first grinding wheel and the three-jaw chuck both rotate; After the first journal and the second journal are ground, adjust the third journal and the fourth journal to be parallel to the rotating shaft of the second motor, drive the second grinding wheel on the second motor to rotate, and drive the second grinding wheel on the tool turret to revolve around the third journal to polish the third journal; After the third journal is polished, rotate the cross shaft by 180° through the three-jaw chuck, and polish the fourth journal in the same way; After the four journals of the cross shaft are all ground, the turning-milling combined machining center cuts off the clamping part on the cross shaft to obtain the ground cross shaft structure.

2. The method of claim 1, wherein the large eccentric cross shaft is formed by a process comprising: The first journal and the second journal are coaxial with the axis of the clamping part.

3. The method of claim 1, wherein the large eccentric cross shaft is formed by a process comprising: The third journal and the fourth journal are spatially perpendicular to the axis of the clamping part.

4. The method of claim 1, wherein the large eccentric cross shaft is formed by a process comprising: When the first grinding wheel polishes the first journal and the second journal, the rotating speed of the first motor is 20,000-30,000 RPM, and the rotating speed of the three-jaw chuck is 10-300 RPM.

5. The method of claim 1 wherein, When the second grinding wheel polishes the third journal and the fourth journal, the rotating speed of the second motor is 20,000-30,000 RPM, and the revolving angular velocity of the second motor is 0.5°-5° / s.

6. The method of claim 1 wherein, The roughness of the first journal, the second journal, the third journal, and the fourth journal is 0.4 microns.

7. The method of claim 1 wherein, The grinding allowance of the first journal, the second journal, the third journal, and the fourth journal is 0.1-0.15 mm on one side.

8. The method of claim 1 wherein, The length of the cross shaft ranges from 25 mm to 40 mm, the diameter of the first journal, the second journal, the third journal, and the fourth journal ranges from 5 mm to 12 mm, and the length of the clamping part ranges from 8 mm to 20 mm.

9. The method of claim 1 wherein, The workpiece ground in the method comprises a cross shaft body, and a clamping part is provided at any one of the journal end of the cross shaft body.

10. The method of claim 1 wherein, The grinding device ground in the method comprises: A three-jaw chuck of a turning-milling combined machining center, used to clamp the clamping part on the cross shaft body; A base installed on a tool turret of the turning-milling combined machining center, the tool turret being used to drive the base to move; A first motor installed on the base, a first grinding wheel being installed on the output shaft of the first motor, and the rotating shaft of the first motor being parallel to the rotating shaft of the clamping part; A second motor installed on the base, a second grinding wheel being installed on the output shaft of the second motor, and the rotating shaft of the second motor being perpendicular to the rotating shaft of the clamping part.

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