Modular Asymmetric Backlash Elimination C Axis and Its Installation and Positioning Method

Abstract

The present invention relates to a modular asymmetric backlash elimination C-axis, which includes a main drive turning module and a C-axis module. The main drive turning module is provided in the spindle box body and is composed of a spindle module and a transmission sub-module. The spindle module is composed of a spindle and parts such as a large gear that are coaxially matched. The C-axis module is provided in the cover and is composed of a C-axis shifting device and a C-axis transmission device. A small gear is arranged on the C-axis transmission device, and a sliding seat is arranged on the C-axis shifting device. The sliding seat is connected to the C-axis transmission device and drives the small gear to mesh with or disengage from the large gear. This modular asymmetric backlash elimination C-axis adopts a structure in which the C-axis module is installed in the cover, realizing all the functions of a traditional C-axis spindle box. At the same time, the concept of modular design is applied, greatly reducing the manufacturing difficulty and cost, shortening the manufacturing cycle, and improving the convenience of production organization.

Description

Technical Field

[0001] The present invention relates to a modular asymmetric backlash elimination C-axis and its installation and positioning method, belonging to the technical field of machining axes of turning-milling composite machine tools. Background Art

[0002] Large / heavy lathes achieve turning functions through the rotation of a high-torque main shaft driven by multiple-stage gears in cooperation with the movement of other linear axes, and achieve special trajectory machining of complex parts through the indexing and positioning functions of the C-axis (the same rotating shaft as the main shaft, but with different control methods) in cooperation with other moving axes. The accuracy of the main shaft and the C-axis directly affects the machining accuracy of parts. Therefore, the C-axis is one of the most core functional components of turning-milling products and is the key to whether the machine tool can perform multi-process and complex surface machining. There are two types of indexing main shafts for traditional turning centers / turning-milling centers:

[0003] One type is the traditional mechanical C-axis; based on the main spindle box of the lathe product, the mechanical C-axis function is added, and at the same time, the C-axis clamping function is added. The C-axis indexing generally uses a single-gear mechanical backlash elimination structure to ensure indexing accuracy. The switching between the C-axis and the main shaft functions must be realized by controlling the engagement and disengagement of the gears through hydraulic components. At the same time, a dedicated C-axis hydraulic clamping or low-pressure damping function is also required to avoid workpiece swing caused by the side clearance of the gears, thereby affecting the milling rigidity. The problems of this structure are that the transmission structure is complex, the mechanical manufacturing cost is high, the adjustment is difficult, the failure rate is high, the accuracy is low, and the accuracy retention is poor.

[0004] The other type is the symmetric dual-drive C-axis; by using two completely symmetrically arranged gear drive chains acting on the large gear installed on the main shaft, the electrical backlash elimination of the C-axis is realized through the combined action of the system controlling the two drive chains. The C-axis of this structure has high accuracy, but two completely symmetric drive chains need to be designed. For large and heavy lathes, the main shaft requires high torque and a wide constant power speed range. Therefore, multiple-stage gear transmission and multiple-speed shifting are required. Two completely symmetric drive chains will greatly increase the cost of the machine tool and make the size of the main spindle box extremely large.

[0005] The above are the main problems of these two types of existing technologies, but there is also a common problem of these two types of technologies: the C-axis main spindle box and the turning main spindle box are completely non-universal. In order to realize the C-axis indexing interpolation function of the turning-milling main spindle box, an independent C-axis turning-milling main spindle box must be designed and developed, and in order to cooperate with the realization of the indexing and positioning function, additional auxiliary functions such as hydraulic or pneumatic must be added. This makes the main spindle box of large turning-milling products have to be produced separately, increasing the manufacturing difficulty, manufacturing cycle and manufacturing cost. Due to such factors, the delivery period of products such as large turning centers / turning-milling centers is long and the price is expensive. This makes it difficult to popularize and apply large turning centers / turning-milling centers. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a modular asymmetric anti-backlash C-axis. This modular asymmetric anti-backlash C-axis utilizes a structure in which the C-axis module is installed within a housing cover, achieving all the functions of a traditional C-axis spindle box. Simultaneously, the modular design concept is applied, significantly reducing manufacturing difficulty and cost, shortening the manufacturing cycle, and improving the convenience of production organization. The modular asymmetric anti-backlash C-axis installation and positioning method is used to improve the C-axis transmission accuracy.

[0007] To solve the above problems, the specific technical solutions created by the present invention are as follows: a modular asymmetric anti-backlash C-axis, including a main transmission turning module and a C-axis module. The main transmission turning module is provided in the spindle box body, and the main transmission turning module is composed of a spindle module and a transmission sub-module. The spindle module is composed of a spindle and a coaxial large gear and other parts; a C-axis module is provided in the box cover, and the C-axis module is composed of a C-axis shifting device and a C-axis transmission device. A small gear is provided on the C-axis transmission device, and a slide is provided on the C-axis shifting device. The slide is connected to the C-axis transmission device and drives the small gear to engage or disengage with the large gear.

[0008] The C-axis shifting device structure includes two parallel linear guide rails provided on the inner surface of the box cover, and the slide seat slides with the linear guide rails through the slider; a shifting servo motor is provided on the outer surface of the box cover, and the output shaft of the shifting servo motor is connected to the lead screw through a coupling, one end of the lead screw and the coupling is supported on the box cover through a bearing, and the other end is connected to the slide seat.

[0009] The C-axis transmission device structure includes: one end of the pinion is connected to the slide through a bearing, the other end of the pinion is connected to the transmission servo motor through a reduction mechanism, and the transmission servo motor is connected to the box cover.

[0010] The slide is connected with a detection rod, the end of which extends out of the box cover to connect with a contact, and a contactless switch is connected to the outer surface of the box cover, and the position of the contactless switch corresponds to the position of the contact.

[0011] The transmission submodule consists of a main shaft submodule, a first-axis submodule, a second-axis submodule and a third-axis submodule. The transmission gears on the main shaft submodule, the first-axis submodule, the second-axis submodule and the third-axis submodule are driven according to the transmission ratio required by the design, and each submodule is supported in the box shell by a flange; the main motor connected to the outside of the main shaft box body is connected to one of the submodules in the transmission submodule through a pulley transmission submodule to transmit power to the main shaft submodule.

[0012] During the design process, the setting of the reduction ratio i1 of the reduction mechanism in the C-axis transmission device should follow T1×i1≈T2×i2; where T1 is the rated torque of the drive servo motor in the C-axis transmission device, T2 is the torque of the main motor connected to the spindle, and i2 is the reduction ratio of the low-speed gear in the transmission sub-module, and the numerical deviation between the left and right sides of the equation T1×i1≈T2×i2 is not greater than 5%.

[0013] The above-mentioned installation and positioning method of the modular asymmetric backlash-eliminating C-axis includes the following steps:

[0014] Determine the center distance between the pinion and the big gear according to the design requirements: When the C-axis housing cover is buckled on the spindle housing, a certain vertical surface during buckling is defined as the positioning vertical surface A, and the parallelism between the positioning vertical surface A and the spindle axis is ≤0.01mm; the parallelism requirement between the linear guide rail in the C-axis housing cover and the positioning vertical surface A is ≤0.01mm;

[0015] Ensure the dimension L1 from the center hole of the big gear in the main drive cutting module to the installation vertical surface and the dimension L2 to the upper surface of the spindle housing through machining; ensure the dimension L3 from the center of the pinion to the lower joint surface of the housing cover and the dimension L4 from the center of the pinion to the housing cover to the positioning vertical surface A; ensure that after the C-axis module and the main drive cutting module are installed, the center distance L between the gear and the big gear meets the dimension requirements by controlling the dimensions L1, L2, L3, and L4;

[0016] When machining the dimensions L3 and L4, it needs to be achieved through fixture to fix the housing cover, linear guide rail, slider and slide block together and then perform component combination machining;

[0017] When assembling the big gear and the pinion of the spindle, adjust the spindle to the neutral position, rotate the spindle to detect the contact ratio between the big gear and the pinion of the spindle, which should not be lower than 85% in the length direction;

[0018] During assembly, it is necessary to verify the tooth side clearance. At this time, a 0.03mm feeler gauge and a 0.02mm feeler gauge should be padded on both sides of the meshing teeth once respectively to keep the total tooth side clearance greater than 0.04mm and less than 0.06mm during operation.

[0019] The modular asymmetric backlash-eliminating C-axis of the present application has the following advantages:

[0020] 1) Based on the C-axis indexing concept of double-motor backlash elimination, but breaking through the idea that the two drive chains must be consistent in the traditional double-motor backlash elimination indexing. Adding an independent C-axis module outside the main turning drive chain can realize all the functions of the traditional complex C-axis structure, greatly simplifying the C-axis structure;

[0021] 2) The C-axis motor is responsible for precise positioning in the angular direction, and the turning main motor follows the speed. Because the C-axis speed is relatively low, through certain parameter settings, even if the C-axis drive chain and the main turning drive chain are inconsistent, good synchronization can still be achieved;

[0022] 3) When drilling and milling workpieces in a fixed position, the C-axis must be sufficiently rigid and prevent swinging. The turning motor torque is adjusted by a torque controller, which controls the transmission gear tooth side to provide reverse tension to the C-axis gear to eliminate C-axis backlash, thereby fixing the C-axis in position while eliminating backlash.

[0023] 4) The machine tool's main drive turning module and C-axis module adopt a fully modular design. The turning and C-axis functions are achieved by superimposing various functional modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a three-dimensional view of the open cover of the modular asymmetric anti-backlash C-axis.

[0025] Figure 2 This is a cross-sectional view of the gear meshing state when the C-axis is working.

[0026] Figure 3 This is the transmission distribution diagram after removing the spindle box.

[0027] Figure 4 This is a schematic diagram of the C-axis shift device structure.

[0028] Figure 5 It is a schematic diagram of the C-axis transmission structure.

[0029] Figure 6 Schematic diagram of the decomposition of each module in the main transmission cutting module.

[0030] Figure 7 This is a schematic diagram of the box cover assembly processing. DETAILED DESCRIPTION

[0031] like Figures 1 to 3 As shown, a modular asymmetric anti-backlash C-axis includes a main transmission turning module 100 and a C-axis module 200. The main transmission turning module 100 is provided in the spindle box body 34. The main transmission turning module 100 is composed of a spindle module 101 and a transmission sub-module. The spindle module 101 is composed of a spindle 35 and a coaxial large gear 32 and other parts; a C-axis module 200 is provided in the box cover 9. The C-axis module 200 is composed of a C-axis shifting device and a C-axis transmission device. A small gear 22 is provided on the C-axis transmission device, and a slide 6 is provided on the C-axis shifting device. The slide 6 is connected to the C-axis transmission device and drives the small gear 22 to engage or disengage with the large gear 32.

[0032] The described C-axis shifting device structure includes that two parallel linear guides 8 are provided on the inner surface of the housing cover 9, and the sliding seat 6 is slidably engaged with the linear guide 8 through the slider 7; a shifting servo motor 1 is provided on the outer surface of the housing cover 9, the output shaft of the shifting servo motor 1 is connected to the lead screw 4 through the coupling 2, one end of the lead screw 4 and the coupling 2 are supported on the housing cover 9 through bearings, and the other end is connected to the sliding seat 6.

[0033] The described C-axis transmission device structure includes that one end of the pinion gear 22 is connected to the sliding seat 6 through a bearing, and the other end of the pinion gear 22 is connected to the transmission servo motor 20 through the reduction mechanism 21, and the transmission servo motor 20 is connected to the housing cover 9.

[0034] A detection rod 24 is connected to the sliding seat 6, the end of the detection rod 24 extends out of the housing cover 9 and is connected to the contact 25, and a non-contact switch 26 is connected to the outer surface of the housing cover 9, and the position of the non-contact switch 26 corresponds to the position of the contact 25.

[0035] The described transmission sub-module is composed of a main shaft sub-module 101, a first shaft sub-module 102, a second shaft sub-module 103 and a third shaft sub-module 104. The transmission gears on the main shaft sub-module 101, the first shaft sub-module 102, the second shaft sub-module 103 and the third shaft sub-module 104 are transmitted according to the designed transmission ratio, and each sub-module is supported in the housing shell 34 through a flange; the main motor 3 connected to the outside of the main shaft housing 34 is transmitted to one of the sub-modules in the transmission sub-module through the belt pulley transmission sub-module 105 to transmit power to the main shaft sub-module 11.

[0036] Different from the symmetric C-axis, in order to achieve good C-axis dynamic response, ensure that both the C-axis module and the main transmission module have good dynamic response during asymmetric backlash elimination transmission, and achieve better backlash elimination positioning accuracy, the power source of the C-axis is the transmission servo motor 20, the power source of the main shaft is the main motor 3, and both the C-axis module and the main transmission module participate in the work during the C-axis movement backlash elimination process. During the design process, the setting of the reduction ratio i1 of the reduction mechanism 21 in the C-axis transmission device should follow T1×i1≈T2×i2; where, T1 is the rated torque of the transmission servo motor 20 in the C-axis transmission device, T2 is the torque of the main motor connected to the main shaft 35, i2 is the reduction ratio of the low-speed gear in the transmission sub-module, and the numerical deviation between the left and right sides of the equation T1×i1≈T2×i2 is not more than 5%.

[0037] The above installation and positioning method of the modular asymmetric backlash elimination C-axis includes the following steps:

[0038] Determine the center distance between the pinion 22 and the gear 32 according to the design requirements: When the C-axis housing cover 9 is fastened to the main spindle housing 34, a certain vertical plane during fastening is defined as the positioning vertical plane A, and the parallelism between the positioning vertical plane A and the main spindle axis is ≤ 0.01 mm; the parallelism requirement between the linear guide 8 in the C-axis housing cover 9 and the positioning vertical plane A is ≤ 0.01 mm;

[0039] Ensure the dimension L1 from the center hole of the gear 32 in the main drive cutting module to the installation vertical plane and the dimension L2 to the upper surface of the main spindle housing through machining; ensure the dimension L3 from the center of the pinion 22 to the lower joint surface of the housing cover 9 and the dimension L4 from the center of the pinion 22 to the positioning vertical plane A of the housing cover 9; by controlling the dimensions L1, L2, L3, and L4, ensure that after the C-axis module 200 and the main drive cutting module 100 are installed, the center distance L between the gear 22 and the gear 32 meets the dimensional requirements;

[0040] Since the pinion 22 is installed on the lead screw sliding mechanism, when machining the dimensions L3 and L4 in step 2, it needs to be achieved through fixture to fix the housing cover 9, the linear guide 8, the slider 7, and the slide base 6 together and then perform component combination machining;

[0041] During assembly, in order to ensure the parallelism between the gear 32 and the pinion 22 of the main spindle 35, the main spindle 35 needs to be adjusted to the neutral position, and the main spindle is rotated to detect the contact ratio between the main spindle gear 32 and the pinion 22, which should not be lower than 85% in the length direction;

[0042] In order to ensure a stable clearance between the pinion 22 and the gear 32, a good clearance can ensure better precision for the C-axis drive. During assembly, the tooth side clearance needs to be verified. At this time, a 0.03 mm feeler gauge and a 0.02 mm feeler gauge should be inserted on both sides of the meshing teeth once respectively to keep the total tooth side clearance greater than 0.04 mm and less than 0.06 mm during operation.

[0043] Regarding the system commissioning after installation: When enabling the C-axis mode, the C-axis motor is set as the main motor, and the turning main motor is set as the slave motor. The system performs position loop control on the C-axis motor and speed loop control on the slave motor. The C-axis motor is responsible for precise feeding in the angular direction, and the turning main motor follows the speed. Since the C-axis speed is relatively low, through certain parameter settings, even if the C-axis drive chain and the main turning drive chain are inconsistent, good synchronization can still be achieved. This is the feeding mode of the C-axis. Taking the Siemens 840D system as an example, the torque percentage needs to be set through the parameter MD37268 $MA_MS_TORQUE_WEIGHT_SLAVE. The conventional symmetric dual-motor torque distribution is generally set as 50% and 50% for the main and slave motors respectively. Since the present invention adopts an asymmetric dual-motor backlash elimination drive, the rated torques T of the main and slave motors need to be considered according to 1，Re - distribute the torques of T2 and different transmission ratios i1, i2 of the master - slave transmission chains. The distribution ratio standard is that after the distribution, the torques output to the C - axis by the two transmission chains at the rated torque are basically the same. To avoid excessive heat generation caused by the high proportion of the torque distribution of the C - axis main motor, when designing the C - axis module, it is necessary to try to satisfy T1×i1≈T2×i2, and generally the deviation is controlled within 5%.

[0044] When fixed - position drilling and milling of workpieces are required, it is necessary to ensure that the C - axis has sufficient rigidity and cannot swing. It is necessary to accurately position and fix the C - axis. At this time, first, the C - axis motor is used to position the C - axis, and the turning motor is used as a backlash - eliminating motor. The system adjusts the torque of the turning motor through the torque controller to control the reverse tension provided by the side of the transmission gear to the large gear of the C - axis to eliminate the C - axis backlash, and fix and position the C - axis while eliminating the backlash. Set the tension between the master and slave through the parameter MDN37264 $MA_MS_TENSION_TORQUE. MD37264 is a percentage of the reference torque p2003 Reference torque. The tension torque eliminates the backlash on the one hand and can improve the mechanical rigidity on the other hand. The backlash - eliminating torque is generally set with a ratio within 10% of the main driving torque of the C - axis. The specific ratio still needs to be accurately debugged and determined according to the on - site situation.

Claims

1. A modular asymmetric anti-backlash C-axis, characterized by: The invention comprises a main transmission turning module (100) and a C-axis module (200), wherein the main transmission turning module (100) is arranged in a main spindle box (34), the main transmission turning module (100) is composed of a main spindle module (101) and a transmission submodule, the main spindle module (101) comprises a main spindle (35) and a coaxial large gear (32); a C-axis module (200) is arranged in a box cover (9), the C-axis module (200) is composed of a C-axis shifting device and a C-axis transmission device, a small gear (22) is arranged on the C-axis transmission device, a slide seat (6) is arranged on the C-axis shifting device, and the slide seat (6) is connected to the C-axis transmission device, and Drive the small gear (22) to engage or disengage with the large gear (32); in the design process, the setting of the reduction ratio i1 of the reduction mechanism (21) in the C-axis transmission device should follow T1×i1≈T2×i2; wherein T1 is the rated torque of the transmission servo motor (20) in the C-axis transmission device, T2 is the main motor torque connected to the main shaft (35), i2 is the reduction ratio of the low-speed gear in the transmission submodule, and the numerical deviation of the equation T1×i1≈T2×i2 is not more than 5%; the C-axis shifting device structure includes two parallel linear guide rails (8) provided on the inner surface of the box cover (9), the slide seat (6 ) is slidably matched with the linear guide rail (8) through the slider (7); a shift servo motor (1) is provided on the outer surface of the box cover (9), and the output shaft of the shift servo motor (1) is connected to the lead screw (4) through the coupling (2), and one end of the lead screw (4) and the coupling (2) are supported on the box cover (9) through a bearing, and the other end is connected to the slide (6); the C-axis transmission device structure includes: one end of the pinion (22) is connected to the slide (6) through a bearing, and the other end of the pinion (22) is connected to the transmission servo motor (20) through a speed reduction mechanism (21), and the transmission servo motor (20) is connected to the box cover (9); the The transmission submodule is composed of a main shaft submodule (101), a first-axis submodule (102), a second-axis submodule (103) and a third-axis submodule (104). The transmission gears on the main shaft submodule (101), the first-axis submodule (102), the second-axis submodule (103) and the third-axis submodule (104) are driven according to the transmission ratio required by the design, and each submodule is supported in the housing (34) through a flange. The main motor (3) connected to the outside of the main shaft housing (34) is connected to one of the submodules in the transmission submodule through a pulley transmission submodule (105), thereby transmitting power to the main shaft submodule (11).

2. The modular asymmetric anti-backlash C-axis according to claim 1, characterized in that: The slide (6) is connected to a detection rod (24), the end of the detection rod (24) extends out of the box cover (9) to connect to the contact (25), and a contactless switch (26) is connected to the outer surface of the box cover (9), and the position of the contactless switch (26) corresponds to the position of the contact (25).

3. The method for installing and positioning a modular asymmetric anti-backlash C-axis according to claim 1, characterized in that The following steps are involved: 1) Determine the center distance between the small gear (22) and the large gear (32) according to the design requirements: When the C-axis box cover (9) is fastened to the spindle box body (34), a vertical surface of the fastening is defined as the positioning vertical surface A, and the parallelism between the positioning vertical surface A and the spindle axis is ≤0.01mm; the parallelism between the linear guide (8) in the C-axis box cover (9) and the positioning vertical surface A is required to be ≤0.01mm; 2) Ensure that the axis hole of the large gear (32) in the main transmission cutting module is from the installation vertical dimension L1 to the upper surface of the spindle box body L2 through machining; ensure that the axis of the small gear (22) is from the lower joint surface dimension L3 to the box cover (9), and the axis of the small gear (22) is from the box cover (9) to the positioning vertical dimension A dimension L4; by controlling the dimensions of L1, L2, L3, and L4, ensure that after the C-axis module (200) and the main transmission cutting module (100) are installed, the center distance L between the gear (22) and the large gear (32) meets the dimension requirements; 3) When processing the L3 and L4 sizes, it is necessary to fix the box cover (9), linear guide rail (8), slider (7) and slide seat (6) together through the tooling and then perform the component assembly processing; When assembling the large gear (32) and the small gear (22) of the main shaft (35), adjust the main shaft (35) to the neutral position, rotate the main shaft to detect the contact rate between the large gear (32) and the small gear (22), and the contact rate in the length direction shall not be less than 85%; 4) The tooth side clearance needs to be verified during assembly. At this time, a 0.03mm feeler gauge and a 0.02mm feeler gauge should be placed on both sides of the meshing teeth to keep the total tooth side clearance greater than 0.04mm and less than 0.06mm during operation.

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