Numerically-controlled machine tool rotary table of double-track supporting structure

Abstract

The utility model discloses a numerical control machine tool rotary table with a double-track supporting structure, which relates to the technical field of machine tool rotary tables and comprises a base, a rotary table body is rotatably mounted at the top of the base and fixedly provided with a driving gear ring, and the driving gear ring is in transmission connection with an even number of driving gears. Each driving gear is in transmission connection with a motor through a speed reducing mechanism; the rotary table body is fixedly provided with a feedback shaft, and the base is provided with an encoder matched with the feedback shaft; a hydrostatic guideway and a rolling bearing are respectively arranged between the rotary table body and the base, the hydrostatic guideway is arranged between a pair of upper and lower surfaces of the rotary table body and the base, is positioned outside and is close to the driving gear, and the rolling bearing is arranged between a pair of inner and outer peripheral surfaces of the rotary table body and the base, is positioned inside and is close to the feedback shaft. Therefore, the mounting steps are simplified, the machining precision is kept, and the heavy load requirement is particularly met.

Description

Technical Field

[0001] This utility model relates to the field of machine tool rotary table technology, specifically to a CNC machine tool rotary table with a double track support structure. Background Technology

[0002] To adapt to the development of large-scale mechanical equipment, the development trend of CNC machine tools and machine tool rotary tables is also towards large and heavy-duty models. In order to ensure machining accuracy, the larger the machine tool rotary table is, the higher the requirements for installation accessories are.

[0003] During operation, machine tool rotary tables are subjected to both axial and radial forces. To meet machining requirements, traditional CNC rotary tables typically employ a structure where cylindrical roller bearings and thrust ball bearings are mounted on the spindle to bear the radial force, while hydrostatic guideways bear the axial force, achieving high-precision rotation. While the load-bearing range of the hydrostatic guideways can be adjusted based on hydraulic pressure variations due to their inherent characteristics, some fluctuation error exists. Although some manufacturers use a single crossed roller bearing instead of the aforementioned multiple bearings to reduce error, small crossed roller bearings are unsuitable for ultra-large rotary tables with diameters exceeding 4 meters. Furthermore, bearings meeting the required precision must be custom-made or imported, resulting in extremely high procurement costs and hindering mass production.

[0004] To meet the demands of ultra-large rotary tables, some manufacturers employ a combination of hydrostatic guideways and cylindrical roller bearings, utilizing a hydraulic system to achieve heavy loads and adjusting the oil supply pressure according to the weight of the workpiece. Refer to patent publication number CN110091186B, entitled "An Embedded Direct-Drive Rotary Table Using Hydrostatic Guideways," which provides a more detailed description. Hydrostatic guideways are a mature existing technology; their oil film significantly reduces friction. However, due to the inherent characteristics of hydrostatic guideways, the oil film thickness varies by approximately 0.05-0.1 mm. Consequently, the distance between the machine tool rotary table surface and the spindle end face also varies by approximately 0.05-0.1 mm, easily causing an error of approximately 0.05-0.1 mm in the height of the workpiece being cut. This cannot meet the requirements of high-precision CNC machine tools, especially not for fully automated CNC machine tools where no operator is needed throughout the machining process. Utility Model Content

[0005] To overcome the above-mentioned defects, the purpose of this utility model is to provide a CNC machine tool rotary table with a double track support structure, which simplifies the installation steps, maintains machining accuracy, and is especially suitable for meeting heavy-duty requirements.

[0006] To achieve the above objectives, this utility model provides a CNC machine tool rotary table with a dual-track support structure, characterized in that it includes:

[0007] The base has a rotary table body rotatably mounted on its top. The rotary table body is fixedly provided with a drive gear ring, which is driven by an even number of drive gears. Each drive gear is driven by a motor through a reduction mechanism. The rotary table body is fixedly provided with a feedback shaft, and the base is provided with an encoder that matches the feedback shaft.

[0008] A hydrostatic guide rail and a rolling bearing are respectively provided between the rotary table body and the base. The hydrostatic guide rail is located between a pair of upper and lower surfaces of the rotary table body and the base, on the outside and close to the drive gear. The rolling bearing is located between a pair of inner and outer circumferential surfaces of the rotary table body and the base, on the inside and close to the feedback shaft.

[0009] Preferably, the rolling bearing is a crossed roller bearing.

[0010] Preferably, the hydrostatic guide rail is a circumferentially distributed hydrostatic cavity sliding track.

[0011] Preferably, the deceleration mechanism is located on the inner side and is a planetary deceleration mechanism;

[0012] The planetary reduction mechanism includes a housing, a sun gear, a planetary carrier, planetary gears, and a planetary carrier output shaft. The housing is fixedly connected to the base. The housing is provided with an internal gear ring. The sun gear is driven by the motor shaft. The planetary gears are rotatably mounted on the planetary carrier. The sun gear meshes with the internal gear ring through the planetary gears. The planetary carrier output shaft is fixedly connected to the planetary carrier and is driven by the drive gear.

[0013] Preferably, a two-stage reduction gear is provided between the sun gear and the motor;

[0014] The secondary reduction mechanism includes a housing, in which a reduction gearbox main power input shaft, an intermediate shaft, and a main power output shaft are rotatably mounted. The main power output shaft is coaxially arranged with the reduction gearbox main power input shaft, and the output end of the main power output shaft is connected to the sun gear drive.

[0015] The gearbox's main power input shaft is connected to the motor via a drive. The gearbox's main power input shaft is equipped with a main power gear. The intermediate shaft is equipped with an intermediate shaft pinion and an intermediate shaft large gear. A two-axis transmission gear is slidably mounted on the main power output shaft. The two-axis transmission gear can selectively mesh with either the main power gear or the intermediate shaft pinion.

[0016] Preferably, the reduction mechanism is located on the outside and is a gear reducer. The power output shaft of the gear reducer is connected to the drive gear through a bevel gear pair.

[0017] The beneficial technical effects achieved by this utility model after adopting the above technical solution are as follows:

[0018] 1. Double-row crossed roller bearings can withstand radial and axial moments and possess technical characteristics such as high speed, high rigidity, low coefficient of friction, and high rotational accuracy. Combining relatively small-diameter crossed roller bearings with large-diameter, wide-surface hydrostatic guideways satisfies load-bearing requirements while overcoming the eccentricity problem caused by unstable hydraulic pressure during hydrostatic guideway rotation. Simultaneously, the low coefficient of friction and good vibration absorption performance of hydrostatic guideways meet the high-speed rotation requirements of CNC machine tool rotary tables. Therefore, the entire machining process is smoother and it is easier to maintain machining accuracy, making it particularly suitable for unmanned CNC machine tools. Both crossed roller bearings and hydrostatic guideways can be directly purchased, resulting in low cost and easier installation and maintenance.

[0019] 2. Utilizing the principle of backlash elimination with dual motors, multiple rotary drive units are set up, and an encoder is installed at the bottom of the rotary table. Together with several motors, this ensures that at least one drive gear generates tension with the rotary table's drive ring gear during operation. This guarantees that the motor output torque will never be zero simultaneously. Under this torque, the backlash of the main gear is eliminated, thus ensuring output stability. In particular, fixing the motors and reduction mechanisms to the base plate of the worktable creates an integrated backlash-free transmission structure consisting of several motors, planetary reduction mechanisms, drive gears, and the large ring gear. This results in a short transmission chain, high output rigidity, energy saving, and high rotational accuracy. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the installation structure in which the motor and planetary reduction gear are placed inside the base;

[0021] Figure 2 This is a schematic diagram of the installation structure of the reduction mechanism using a single-stage gear reducer direct drive;

[0022] Figure 3 This is a schematic diagram of the installation structure of the reduction mechanism using a two-stage gear reducer direct drive;

[0023] Figure 4 This is a schematic diagram of the explosion state of the planetary deceleration mechanism in this utility model;

[0024] Figure 5 This is an internal schematic diagram of the two-stage reduction mechanism in this utility model;

[0025] In the diagram,

[0026] 1. Base; 11. Hydrostatic guide rail; 12. Crossed roller bearing; 13. Bevel gear pair; 14. Gear reducer;

[0027] 2. Rotary table body; 21. Drive gear ring; 22. Encoder; 23. Drive gear;

[0028] 3. Planetary reduction mechanism; 31. Motor shaft; 311. Sun gear; 32. Planetary support; 321. Planetary support output shaft; 322. Planetary gear; 33. Intermediate shaft; 331. Intermediate shaft pinion; 332. Intermediate shaft gear; 34. Main power output shaft; 341. Secondary shaft transmission gear; 35. Housing; 351. Internal gear ring; 36. Housing; 37. Main power input shaft; 371. Main power gear;

[0029] 4. Motor. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model.

[0031] See Figures 1-5 This invention provides a CNC machine tool rotary table with a dual-track support structure, comprising: a base 1, a rotary table body 2 rotatably mounted on the top of the base 1, a drive gear ring 21 fixedly mounted on the rotary table body 2, the drive gear ring 21 being driven by an even number of drive gears 23, each drive gear 23 being driven by a motor through a reduction mechanism; a feedback shaft fixedly mounted on the rotary table body 2, and an encoder 22 matching the feedback shaft mounted on the base 1; a hydrostatic guide rail 11 and a rolling bearing are respectively provided between the rotary table body 2 and the base 1, the hydrostatic guide rail 11 being located between a pair of upper and lower surfaces of the rotary table body 2 and the base 1, located externally and close to the drive gears, and the rolling bearing being located between a pair of inner and outer circumferential surfaces of the rotary table body and the base, located internally and close to the feedback shaft. Utilizing the heavy-duty characteristics of the hydrostatic guide rail 11, combined with the crossed roller bearing 12, the CNC machine tool rotary table assembly of this invention is suitable for heavy-duty applications while maintaining good machining accuracy.

[0032] This utility model generally uses a direct-drive motor, that is, the motor 4 is directly connected to the drive gear 23. The entire motor 4 can be installed inside the base 1, and the rotation speed of the rotary table body 2 is controlled by controlling the rotation speed of the motor 4. This method of placing the motor 4 internally results in a relatively complex installation process and higher processing and maintenance costs. Compared to... Figure 1 The motor 4 can be installed vertically in the vertical carriage, or horizontally in the vertical carriage. See [reference needed]. Figure 2 and Figure 3In this design, the power output direction is adjusted using a bevel gear pair 13. This is achieved by installing the bevel gear pair 13 in an angle reducer, changing the power transmission angle, while still maintaining the power transmission using direct-drive motor technology. External installation is the most common method, offering greater convenience for installation and maintenance. Based on common mechanical knowledge regarding backlash elimination with dual motors, this invention typically uses an even number of drive gears 23 meshing with the drive gear ring 21, preferably 2, 4, 6, or 8 drive gears 23. The rotary table body 2 is fixedly equipped with a feedback shaft, and the base 1 is equipped with an encoder 22 or circular grating that matches the feedback shaft.

[0033] The rolling bearing used in this invention is a crossed roller bearing 12 (first track). To ensure load-bearing capacity, a double-row crossed roller bearing 12 is generally purchased and used directly. The crossed roller bearing 12 and the hydrostatic cavity sliding track are existing technologies, and the required model can be selected.

[0034] In this invention, the hydrostatic guide rail 11 is a circumferentially distributed hydrostatic cavity sliding track (second track). The load-bearing range of the hydrostatic cavity sliding track is controlled by changes in oil pressure, and it is paired with crossed roller bearings 12 to further ensure high-precision machining.

[0035] See Figure 1 , Figure 4 and Figure 5 The reduction mechanism of this utility model is a planetary reduction mechanism 3. Planetary reduction is a relatively mature existing technology, and a smooth output power can be obtained after using planetary reduction. When multiple drive gears 23 drive the same gear ring, not only can transmission backlash be eliminated, but also a larger output torque can be obtained, which is suitable for large rotary table bodies 2. The reduction mechanism of this utility model can also be directly replaced by a single gear, which is cheaper, but the accuracy is relatively lower. Since the planetary reduction mechanism 3 has a compact structure, a large reduction ratio, and high accuracy, the planetary reducer structure 3 is preferred, which can further shorten the transmission chain, realize direct drive, and achieve better results.

[0036] The planetary reduction mechanism 3 of this utility model includes a housing 35, a sun gear 311, a planetary carrier 32, planetary gears 322, and a planetary carrier output shaft 321. The housing 35 is fixedly connected to the base 1. The housing 35 is provided with an internal gear ring 351. The sun gear 311 is drivenly connected to the motor shaft 31. The planetary gears 322 are rotatably mounted on the planetary carrier 32, and the sun gear 311 meshes with the internal gear ring 351 through the planetary gears 322. The planetary carrier output shaft 321 is fixedly connected to the planetary carrier 32, or it can be integrally formed. The planetary carrier output shaft 321 is fixedly connected to the drive gear 23. The sun gear 311 is directly connected to the motor shaft 31 of the motor 4. Multiple planetary gears 322 rotate around the sun gear 311 and transmit power to the planetary carrier output shaft 321 through the planetary carrier 32. The drive gear 23 is drivenly connected to the drive gear ring 21, thereby transmitting the power of the motor to the drive gear ring 21. The drive gear ring 21 can be an internal gear ring 351 or an external gear ring. In both cases, the power transmission can be achieved using a planetary reduction mechanism 3.

[0037] See Figure 2 In this invention, a two-stage reduction mechanism is provided between the sun gear 311 and the motor 4. The two-stage reduction mechanism includes a housing 36, within which a main force input shaft 37, an intermediate shaft 33, and a main force output shaft 34 are rotatably mounted. The main force output shaft 34 is coaxial with the main force input shaft 37, and its output end is connected to the sun gear 311. The main force input shaft 37 is connected to the motor shaft 31, and it is equipped with a main force gear 371. The intermediate shaft 33 is equipped with a small intermediate shaft gear 331 and a large intermediate shaft gear 332. A second-axis transmission gear 341 is slidably mounted on the main force output shaft 34, and can selectively mesh with either the main force gear 371 or the small intermediate shaft gear 331. The two-stage reduction mechanism is based on a single-stage planetary reduction gear, with a gearbox added to the output end of the motor 4 to enable gear shifting and thus increase the output torque. A dual-shaft transmission gear 341 slides on the main power output shaft 34. The dual-shaft transmission gear 341 can generally connect to a shifting mechanism, or it can directly drive the main power input shaft 37. Alternatively, the input speed of the main power input shaft 37 can be reduced by a gearbox, passing through a small gear 331 and a large gear 332 on an intermediate shaft, before being output to the sun gear 311. There can be multiple intermediate shafts 33 in the housing 36, but two are generally preferred and symmetrically installed. The module of the small gear within the housing 36 is generally relatively small; multi-gear drive is used to output greater torque.

[0038] The reduction mechanism of this invention is located on the outside and is a gear reducer 14. The power output shaft of the gear reducer 14 is connected to the drive gear 23 via a bevel gear pair 13. The gear reducer 14 is existing technology; the transmission ratio can be set according to the transmission requirements. Figure 3 The one shown is a single-stage gearbox, but a two-stage or three-stage gearbox can also be selected.

[0039] Of course, there may be other embodiments of this utility model. Without departing from the spirit and essence of this utility model, those skilled in the art can make various corresponding changes and modifications based on this utility model, but these corresponding changes and modifications should all fall within the protection scope of the appended claims of this utility model.

Claims

1. A CNC machine tool rotary table with a double-track support structure, characterized in that, include: A base is provided, and a rotary table body is rotatably mounted on the top of the base. A hydrostatic guide rail and a rolling bearing are respectively provided between the rotary table body and the base. A drive gear ring is fixedly provided on the rotary table body. The drive gear ring is driven by an even number of drive gears. The hydrostatic guide rail is located between a pair of upper and lower surfaces of the rotary table body and the base, located on the outside and close to the drive gears. A feedback shaft is fixedly provided on the rotary table body. The rolling bearing is located between a pair of inner and outer circumferential surfaces of the rotary table body and the base, located on the inside and close to the feedback shaft. Each of the drive gears is connected to a motor via a reduction mechanism; the base is equipped with an encoder that matches the feedback shaft.

2. The CNC machine tool rotary table with a double-track support structure according to claim 1, characterized in that, The rolling bearing is a crossed roller bearing.

3. The CNC machine tool rotary table with a double-track support structure according to claim 1, characterized in that, The hydrostatic guide rail is a circumferentially distributed hydrostatic cavity sliding track.

4. The CNC machine tool rotary table with a double-track support structure according to claim 1, characterized in that, The deceleration mechanism is located on the inner side and is a planetary deceleration mechanism; The planetary reduction mechanism includes a housing, a sun gear, a planetary carrier, planetary gears, and a planetary carrier output shaft. The housing is fixedly connected to the base. The housing is provided with an internal gear ring. The sun gear is driven by the motor shaft. The planetary gears are rotatably mounted on the planetary carrier. The sun gear meshes with the internal gear ring through the planetary gears. The planetary carrier output shaft is fixedly connected to the planetary carrier and is driven by the drive gear.

5. The CNC machine tool rotary table with a double-track support structure according to claim 4, characterized in that, A two-stage reduction mechanism is provided between the sun gear and the motor; The secondary reduction mechanism includes a housing, in which a main force input shaft, an intermediate shaft, and a main force output shaft are rotatably mounted. The main force output shaft is coaxially arranged with the main force input shaft, and the output end of the main force output shaft is connected to the sun gear drive. The main power input shaft is connected to the motor drive. The main power input shaft is provided with a main power gear. The intermediate shaft is provided with an intermediate shaft pinion and an intermediate shaft large gear. The main power output shaft is slidably provided with a two-axis transmission gear. The two-axis transmission gear can selectively mesh with the main power gear or the intermediate shaft pinion.

6. The CNC machine tool rotary table with a double-track support structure according to claim 1, characterized in that, The deceleration mechanism is located on the outside and is a gear reducer. The power output shaft of the gear reducer is connected to the drive gear through a bevel gear pair.

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