Omnidirectional powerful numerical control rolling machine tool for strengthening axle

Abstract

The invention belongs to the technical field of metal material cold machining strengthening, and particularly relates to an omni-directional powerful numerical control rolling machine tool for axle strengthening, which comprises a machine tool body, and a spindle box, a radial feeding mechanism and a tailstock which are sequentially arranged on the machine tool body, opposite rotary tables are arranged above the radial feeding mechanism, and rolling devices are arranged on the rotary tables; the rolling device is internally provided with two rolling heads arranged back to back, and the rolling heads are switched through a rotary table. The invention further discloses an axle strengthening machining method which comprises six steps that three-dimensional space accurate positioning is achieved through the axial and radial numerical control seven-axis linkage interpolation technology, and the rolling device is pushed through the hydraulic driving system to apply high-strength acting force; the rotary table is adopted to drive the rolling heads to quickly switch the rolling heads for different shaft sections, so that the efficiency is improved; the device has the advantages of high automation, large rolling force, high reliability and the like, the roughness of the workpiece surface is remarkably reduced, the surface hardness is improved, the axle surface layer is strengthened, the wear resistance is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of cold working and strengthening of metal materials, and specifically relates to an omnidirectional high-power CNC rolling machine for axle strengthening, which can perform surface strengthening on arc segments and straight segments of axle bodies of various axle types of rail vehicles. Background Art

[0002] Rail vehicle axles are key load-bearing components of the bogie system, and their surface integrity parameters directly impact the train's dynamic performance and service safety. Under complex operating conditions, axles are subjected to periodic impact loads caused by track joints and alternating stresses resulting from operational jolts. Long-term exposure to high loads coupled with sliding friction can easily induce surface fatigue cracks. The progressive expansion of cracks ultimately leads to component fatigue failure. To address this failure mode, improving the wear resistance and fatigue resistance of axle materials through advanced surface engineering technologies has become a key area of ​​research in rail transit equipment reliability, with significant engineering application value.

[0003] Surface strengthening treatment is the most effective way to increase the life of axles. Currently, in the field of rail vehicle axle manufacturing, there are two main technical routes for surface rolling strengthening processes: one is to use a CNC lathe equipped with a low-load rolling device to carry out the operation. Due to the rigidity of the equipment structure, it can only achieve a slight plastic deformation at the surface polishing level, and cannot form a deep compressive stress field. The material strengthening effect is difficult to meet engineering standards; the second is to use an experience-oriented process. The operator relies on an ordinary lathe platform and manually adjusts the tool holder to position and clamp the small curvature radius rolling tool to perform the operation. This model has significant technical defects - the lack of an open force control system makes it impossible to accurately quantify the rolling force value, and the motion trajectory relies on manual operation, resulting in poor processing consistency. In addition, the overall process automation level lags behind the technical requirements of the intelligent manufacturing era for process controllability, repeatability and digital management.

[0004] Currently, rail vehicle axle manufacturers primarily use CNC lathes or manual labor based on experience to perform surface hardening of arc and straight sections of axles using small arc rolling tools clamped in the tool holder of a conventional lathe. This results in low rolling forces and insignificant strengthening effects, making it difficult to meet the demands of modern axle hardening. Furthermore, the machine must adjust the angle and position of the rolling tools for different shaft types and segments, which is complex and labor-intensive. This discrete, experience-driven process model fails to meet the requirements of intelligent manufacturing systems for closed-loop control of process data, becoming a key bottleneck hindering the improvement of axle fatigue life and the development of smart factories. Consequently, traditional manual operations rely on accumulated experience, resulting in insufficient process stability. CNC low-energy rolling, however, is limited by the dynamic characteristics of the equipment, resulting in low rolling forces and difficulty in achieving high-intensity rolling. Common flaws of both methods include insufficient microstructural gradient development and unstable residual stress distribution, resulting in generational differences in the fatigue performance of the hardened layer compared to the designed specifications. Summary of the Invention

[0005] In order to address the shortcomings of the existing technology, an omnidirectional high-power CNC rolling machine for axle strengthening is provided. The rotary rolling head is used to efficiently meet the high-power rolling requirements of arc segments and straight segments of different shaft shapes. The present invention is achieved through the following technical solutions: The present invention provides an omnidirectional high-power CNC rolling machine for axle strengthening, which includes a bed, a slide, a spindle box, a dial, a tailstock, a shaft support device, a radial feed mechanism, a turntable, a rolling device, and a measuring device, a CNC system and a hydraulic system required for the normal operation of the CNC rolling machine.

[0006] Furthermore, the spindle box is installed on the left side of the bed by screws, and the spindle is driven to rotate by the second motor, and a dial is installed on the spindle; the tailstock is installed on the slide block on the bed, and the axial movement of the tailstock is controlled by the trapezoidal screw. The tailstock is provided with a top, and the oil cylinder controls the left and right movement of the top; Furthermore, the slide is installed on the slider of the slide rail, and the axial movement of the slide is controlled by a ball screw; a support shaft device is installed on the slide, and the lifting and lowering of the support shaft device is controlled by a cylinder; the radial feed mechanism is symmetrically installed on the slide, and the ball screw is driven by the sixth motor to drive the radial feed mechanism for radial feeding.

[0007] Furthermore, the turntable is installed on the radial feed mechanism, a turbine is provided at the bottom of the turntable, the turbine is engaged with the worm, the worm is connected to the output shaft of the fourth motor, and the worm is driven by the fourth motor to realize the rotation function; a rolling device is installed on the turntable, a rotating shaft and an oil distribution joint are installed on the rolling device, and a measuring device is installed on the side of the radial feed mechanism.

[0008] Furthermore, the CNC rolling machine comprises seven axes, namely Z1, Z2, X1, X2, C1, C2 and C3, wherein the Z1 axis drives the rolling device (20) to feed along the axial direction of the axle, the X1 and X2 axes control the radial feed of the rolling device, the Z1 axis is linked with the X1 axis and the X2 axis to complete the rolling processing of the axle surface, the Z2 axis is used to move the tailstock, the C1 axis is used as the main spindle servo drive axis to realize the rotation of the axle; and C2 and C3 are the rotation axes of the turntable.

[0009] Furthermore, the axle strengthening processing method of the omnidirectional strong CNC rolling machine includes the following steps: Fixed clamping of S1 axle; S2 sets the feed rate for rolling process; S3 cleans the surface of the axle to be rolled; S4 moves the rolling head to the rolling area and adjusts the rolling force; S5 performs rolling processing on the axle; S6 performs precision inspection on axles.

[0010] Compared with the existing technology, the present invention provides an omnidirectional high-power CNC rolling machine for axle strengthening, which has the following significant advantages: the rotating rolling head base structure under the turntable can achieve dynamic stability under complex shaft-shaped and shaft-surface working conditions, and is conducive to rapid disassembly and cleaning; the axial and radial CNC seven-axis linkage interpolation technology is used to achieve precise positioning in three-dimensional space, and the hydraulic drive system is used to propel the rolling device to apply high-strength force; the support shaft device is used to increase the loading and unloading speed to achieve efficient production adaptation, and through systematic technical improvements, a coordinated breakthrough in processing accuracy, equipment reliability and production efficiency is achieved.

[0011] The present invention effectively ensures the stability and reliability during the axle rolling process, improves the rolling strengthening quality of the axle, increases the fatigue resistance of the axle surface by an order of magnitude, and increases the service life of the axle. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be further described below with reference to the accompanying drawings and examples.

[0013] Figure 1 It is a top view of an omnidirectional high-power CNC rolling machine for axle strengthening according to the present invention; Figure 2 This is a front view of an omnidirectional high-power CNC rolling machine for axle strengthening according to the present invention; Figure 3 It is a schematic diagram of the layout of the moving parts of the machine tool of the present invention; Figure 4 It is a three-dimensional diagram of an omnidirectional high-power CNC rolling machine for axle strengthening according to the present invention; Figure 5 It is a structural relationship diagram of the turntable and the rolling device of the present invention.

[0014] Among them: 1. Spindle box; 2. First motor; 3. Dial; 4. Radial feed mechanism; 5. Second motor; 6. Third motor; 7. Tailstock; 8. Bed; 9. Slide; 10. Ball screw; 11. Shaft support device; 12. Linear rail; 13. Linear guide; 14. Screw; 15. Trapezoidal screw; 16. Fourth motor; 17. Fifth motor; 18. Measuring device; 19. Turntable; 20. Rolling device; 21. Oil distribution joint; 22. Rotating shaft; 23. Worm gear. DETAILED DESCRIPTION

[0015] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0016] Reference Figures 1 to 4 As shown, the present invention provides an omnidirectional high-power CNC rolling machine for axle strengthening, comprising a bed 8, a spindle box 1, a radial feed mechanism 4, and a tailstock 7 sequentially arranged on the bed 8. Above the radial feed mechanism 4, an opposing turntable 19 is disposed. A rolling device 20 is mounted on the turntable 19. The rolling device 20 houses two rolling heads arranged back to back, which are switched by the turntable 19. The rolling heads come in two sizes, one for machining cylindrical segments and the other for machining circular segments.

[0017] In order to replaceably complete the fixing and rolling processing of the axle, it also includes a second motor 2, a dial 3, a third motor 5, a fourth motor 6, a slide 9, a ball screw 10, a shaft support device 11, a linear rail 12, a linear guide 13, a screw 14, a trapezoidal screw 15, a fifth motor 16, a sixth motor 17, a measuring device 18, a turntable 19, a rolling device 20, an oil distribution joint 21, a rotating shaft 22, and a worm gear 23.

[0018] Preferably, the bed 8 is equipped with a linear guide 13, a screw 14 and a trapezoidal screw 15; the spindle box 1 is installed on the left side of the bed 8 by screws, and the second motor 2 drives the transmission belt to drive the spindle to rotate. The dial 3 is installed on the spindle box 1 to play the role of retracting the shaft; the tailstock 7 is installed on the linear guide 13, and the trapezoidal screw 15 is driven by the fifth motor 16 to control the axial movement of the tailstock 7. The tailstock 7 is provided with a top, and the top movement is controlled by the oil cylinder to achieve the tightening of the axle; both ends of the axle adopt the clamping method of top tightening, which has high positioning accuracy, is easy to meet the axle coaxiality requirements, and can ensure the accuracy during multiple clamping. Therefore, it is mostly used for long-axis workpieces or processing scenarios that require multiple clamping. However, it should be noted that the top tightening force must be controlled within a reasonable range to avoid excessive bending of the axle and reducing the rigidity of the axle.

[0019] Preferably, the slide 9 is installed on a linear guide rail 13, and the sixth motor 17 drives the screw 14 to control the axial movement of the slide 9; the shaft support device 11 is installed on the slide 9, and the lifting and lowering of the shaft support device 11 is controlled by the cylinder to realize the loading and unloading of the axle; the radial feed mechanism 4 is symmetrically installed on the linear rail 12 of the slide 9, and the ball screw 10 is driven by the third motor 5 to drive the radial movement of the radial feed mechanism 4; the measuring device 18 is installed on the side of the radial feed mechanism 4 for high-precision measurement of the shaft surface after processing is completed.

[0020] Preferably, the turntable 19 is installed on the radial feed mechanism 4 and is arranged in an opposing manner. A worm gear 23 is provided at the bottom of the turntable 19, and the worm gear 23 is engaged with the worm. The worm is connected to the output shaft of the fourth motor 6, and the worm is driven by the fourth motor 6 to drive the worm gear 23 to realize the rotation function; a rolling device 20 is installed on the turntable 19, and the rolling device 20 is equipped with two rolling heads arranged back to back. The extension and retraction of the rolling heads are controlled by a hydraulic cylinder, and the rapid switching of the rolling heads is realized through the turntable 19; a rotating shaft 22 and an oil distribution joint 21 are installed above the rolling device 20 to provide hydraulic oil and lubricating oil to the transmission components.

[0021] like Figure 3 As shown, the CNC rolling machine includes seven axes: Z1, Z2, X1, X2, C1, C2, and C3. The Z1 axis drives the rolling device 20 along the axial feed of the axle, while the X1 and X2 axes control the radial feed of the rolling device 20. The Z1 axis works in conjunction with the X1 and X2 axes to complete the rolling process on the axle surface. Furthermore, the Z2 axis is used to move the tailstock 7, and the C1 axis serves as the spindle servo drive axis to achieve axle rotation. The C2 and C3 axes are the rotation axes of two opposing turntables 19, used for rapid switching of the rolling heads. They utilize axial and radial CNC five-axis linkage interpolation technology to achieve precise three-dimensional positioning. A hydraulic drive system is used to propel the rolling device to apply high-intensity forces.

[0022] The specific steps of CNC rolling machine are as follows: (1) Fixing and clamping the axle: First, hoist the axle onto the bed of the machine tool and clamp it with the centers at both ends tightly pressed together to ensure that the two centers are accurately positioned and meet the axle coaxiality requirements, thereby ensuring the accuracy of multiple clamping. During clamping, a micrometer is required to measure and adjust the radial runout of the axle to control the error within the preset range. At the same time, check the contact area between the center center and the axle center hole to avoid loosening or eccentricity during clamping. After clamping, the stability of the axle needs to be confirmed again to prevent displacement during processing.

[0023] (2) Set the feed rate for rolling: In the machine tool control system, find the feed rate parameter setting interface and set the feed rate of the Z1 axis to the parameters required for processing. After the setting is completed, perform a dry run test to observe whether the motion trajectory and speed of the rolling device meet the set requirements. If there is any deviation, it is necessary to recheck the parameter settings and transmission system to ensure that the feed rate is accurate.

[0024] (3) Clean the surface of the axle to be rolled and apply oil after cleaning: Use a dust-free cloth with a cleaning agent such as acetone or alcohol to wipe the surface of the axle to be rolled to remove oil, iron filings, oxide scale and other impurities on the surface. When cleaning, wipe along the axial direction of the axle to avoid residual detergent or impurities. During the processing, lubricating oil is sprayed from the oil pipe onto the rolling head and the axle processing surface to ensure good lubrication of the roller and the axle surface, reducing friction and wear.

[0025] (4) Move the rolling head to the rolling area and adjust the rolling force to the predetermined pressure: Slowly move the rolling head to the rolling starting position of the axle by linking the X1, X2 and Z1 axes of the machine tool. During the movement, observe the distance between the rolling head and the axle surface in real time to avoid collision. After reaching the predetermined position, gradually increase the rolling force to the appropriate value. During the adjustment process, pay close attention to the changes in the pressure value. When the pressure approaches the set value, gradually adjust it in smaller pressure increments to ensure that the pressure is stable within a certain range.

[0026] (5) Rolling the axle: After confirming that the parameters such as clamping, feed rate, and rolling force meet the requirements, start the rolling program of the machine tool. The rolling head has two specifications, which are used for processing cylindrical segments and arc segments respectively. During the rolling process, the operating status of the rolling head, the vibration of the axle, and the operating parameters of the machine tool are monitored in real time. If abnormal vibration, noise, or parameter fluctuations are found, the rolling process should be stopped immediately, the equipment and process parameters should be checked, and the processing can be continued only after the fault is eliminated.

[0027] (6) Accuracy testing of the axle: After rolling, use a measuring device to test the dimensional accuracy of the axle, such as diameter, roundness, cylindricity, shape accuracy, and surface roughness. At the same time, use a hardness tester to measure the hardness value of the axle surface and check the distribution of residual compressive stress. Compare the test results with the process requirements. If there is any deviation, analyze the cause and adjust the rolling process parameters. If necessary, rework the axle.

[0028] During operation, the axle is placed between two rolling heads, each of which has a certain degree of hardness. When the rolling heads apply a compressive force to the axle surface, the surface material undergoes plastic deformation under the influence of the rolling force. This process creates residual compressive stress on the axle surface, which in turn increases the surface hardness. Furthermore, surface rolling strengthens the axle significantly, significantly enhancing its wear resistance. After rolling, the residual compressive stress generated significantly increases the material's wear resistance. Furthermore, the surface roughness is reduced by 2-3 levels, and the surface hardness is increased by 0.5 times. These multiple factors contribute significantly to the axle's wear resistance, effectively increasing its fatigue strength and service life.

[0029] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An omnidirectional high-power CNC rolling machine for axle strengthening, characterized by: The invention comprises a bed (8), a main spindle box (1), a radial feed mechanism (4), and a tailstock (7) which are sequentially arranged on the bed (8); a turntable (19) is arranged opposite to each other above the radial feed mechanism (4); a rolling device (20) is arranged on the turntable (19); the rolling device (20) has two rolling heads arranged back to back, and the rolling heads are switched through the turntable (19).

2. The omnidirectional high-power CNC rolling machine for axle strengthening according to claim 1, characterized in that: The bed (8) is provided with a linear guide rail (13), a screw rod (14) and a trapezoidal screw rod (15); the spindle box (1) is installed on the left side of the bed (8) by screws, and the second motor (2) is driven to drive the transmission belt and then drive the spindle to rotate, and the spindle box (1) is installed with a dial (3); the tailstock (7) is installed on the linear guide rail (13), and the trapezoidal screw rod (15) is driven by the fifth motor (16) to control the axial movement of the tailstock (7), and the tailstock (7) is provided with a top, and the top movement is controlled by the oil cylinder.

3. The omnidirectional high-power CNC rolling machine for axle strengthening according to claim 1, characterized in that: The invention also includes a slide (9), which is installed on a linear guide rail (13), and the sixth motor (17) drives a screw rod (14) to control the axial movement of the slide (9); a shaft support device (11) is installed on the slide (9), and the lifting and lowering of the shaft support device (11) is controlled by an oil cylinder; a radial feed mechanism (4) is symmetrically installed on the linear rail (12) of the slide (9), and the third motor (5) drives the ball screw rod (10) to drive the radial feed mechanism (4) to move radially.

4. The omnidirectional high-power CNC rolling machine for axle strengthening according to claim 1, characterized in that: The turntable (19) is mounted on the radial feed mechanism (4). A worm gear (23) is provided at the bottom of the turntable (19). The worm gear (23) is engaged with a worm, and the worm is connected to the output shaft of the fourth motor (6). A rolling device (20) is mounted on the turntable (19). The rolling device (20) is equipped with two rolling heads arranged back to back. The extension and contraction of the rolling heads are controlled by a hydraulic cylinder. A rotating shaft (22) and an oil distribution joint (21) are mounted above the rolling device (20).

5. The omnidirectional high-power CNC rolling machine for axle strengthening according to claim 1, characterized in that: The CNC rolling machine comprises seven axes, namely Z1, Z2, X1, X2, C1, C2 and C3, wherein the Z1 axis drives the rolling device (20) to feed along the axial direction of the axle, the X1 and X2 axes control the radial feeding of the rolling device (20), the Z1 axis is linked with the X1 axis and the X2 axis to complete the rolling processing of the axle surface, the Z2 axis is used to move the tailstock (7), the C1 axis serves as the main spindle servo drive axis to realize the rotation of the axle; and C2 and C3 are the rotation axes of the turntable (19).

6. A method for strengthening an axle using the omnidirectional high-power CNC rolling machine according to any one of claims 1 to 5, characterized in that The following steps are involved: Fixed clamping of S1 axle; S2 sets the feed rate for rolling process; S3 cleans the surface of the axle to be rolled; S4 moves the rolling head to the rolling area and adjusts the rolling force; S5 performs rolling processing on the axle; S6 performs precision inspection on axles.

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