A gear transmission device

Abstract

This utility model discloses a gear transmission device, including a first gear, a second gear, an adjusting mechanism, and a transmission shaft. The first gear meshes with the second gear for transmission. The adjusting mechanism includes a backlash-eliminating gear, a fixed seat, a worm, and a worm wheel. The backlash-eliminating gear is coaxially mounted on the transmission shaft with the second gear and can rotate relative to the second gear. One tooth of the second gear and one tooth of the backlash-eliminating gear can simultaneously mesh with the same tooth groove of the first gear. The fixed seat is disposed between the second gear and the backlash-eliminating gear and is fixedly connected to one of the two gears. The worm wheel is coaxially fixedly connected to the other gear. The fixed seat is evenly distributed around the transmission shaft. The worm is rotatably mounted on the fixed seat and meshes with the worm wheel. This utility model has a simple structure and eliminates gear meshing backlash without requiring slots or mounting holes on the side of the gear.

Description

Technical Field

[0001] This utility model relates to the field of machine tool processing technology, and in particular to a gear transmission device. Background Technology

[0002] Centrifugal force-free cutting machine tools are innovative machining equipment, mainly used to solve the problems caused by centrifugal force, vibration and deformation in the traditional machining of slender shafts. In the application of the machine tool, the degree of gear meshing will greatly affect the machining accuracy of slender shafts. The higher the degree of gear meshing, the higher the machining accuracy of slender shafts.

[0003] However, existing machine tools frequently experience gear meshing defects, leading to the accumulation of errors in the transmission chain, such as base pitch error and tooth profile error. These errors are transmitted to the machined parts through the transmission system, directly affecting the machine tool's positioning accuracy and repeatability. Furthermore, under high-speed, heavy-load conditions, dynamic changes in gear meshing clearance and tooth flank clearance introduce additional errors. For example, when gear wear or installation misalignment increases meshing clearance, instantaneous speed fluctuations during transmission can cause slight deviations in the machining trajectory, especially noticeable in high-precision machining (such as IT6 level and above).

[0004] Therefore, eliminating backlash is of paramount importance for improving the machining accuracy of machine tools. Double-gear misalignment is a commonly used method for eliminating gear backlash. It utilizes two coaxial gears to automatically compensate for the backlash between the driven and driving gears by creating a relative misalignment, ensuring complete meshing of the two tooth surfaces within the same tooth groove. However, it has been found that after a certain period of use, this double-gear misalignment structure is prone to poor meshing between the driven and driving gears. Utility Model Content

[0005] Therefore, the purpose of this utility model is to overcome the defects or deficiencies of the prior art and provide a gear transmission device.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A gear transmission device includes a first gear, a second gear, an adjusting mechanism, and a transmission shaft; the first gear meshes with the second gear for transmission; the adjusting mechanism includes a backlash-eliminating gear, a fixed seat, a worm, and a worm wheel; the backlash-eliminating gear and the second gear are coaxially mounted on the transmission shaft, the second gear rotates with the transmission shaft, and the backlash-eliminating gear can rotate relative to the second gear around the transmission shaft; one tooth of the second gear and one tooth of the backlash-eliminating gear can simultaneously mesh into the same tooth groove of the first gear; the fixed seat is disposed between the second gear and the backlash-eliminating gear and is fixedly connected to one of the second gear and the backlash-eliminating gear, the worm wheel is coaxially fixedly connected to the other, the fixed seat is uniformly arranged circumferentially around the transmission shaft, and the worm is rotatably disposed on the fixed seat and meshes with the worm wheel.

[0008] The gear transmission device described in this utility model eliminates the need for slots or mounting holes on the side of the gears, allowing for adjustment and elimination of gear meshing clearance without compromising the original gear structure's strength. This simplifies parts manufacturing. By adding a fixed base evenly distributed around the shaft, the uneven distribution of axial force during transmission is effectively improved, making the entire device structure more stable and thus mitigating the problem of poor meshing that often occurs after a period of use. Adjusting the gear meshing clearance is as simple as rotating the worm gear, making operation convenient.

[0009] Furthermore, the extension direction of the worm is perpendicular to the axis, which allows for a more uniform distribution of force along the axial direction.

[0010] Furthermore, the fixed base has an annular structure extending around the axis of the transmission shaft, and its side wall is provided with two through holes for the two ends of the worm gear to pass through.

[0011] Furthermore, the second gear has a keyway extending axially along the transmission shaft in the middle, and a fixing key protrudes from the outer side of the transmission shaft. The fixing key is engaged in the keyway to achieve coaxial rotation between the second gear and the transmission shaft.

[0012] Furthermore, the adjustment mechanism also includes a locking unit, which includes a positioning ring and a positioning element. The positioning ring is sleeved on the outside of the transmission shaft and located on the side of the backlash-eliminating gear facing away from the second gear, abutting against the backlash-eliminating gear to restrict the movement of the backlash-eliminating gear along an axial direction away from the second gear. The positioning ring is provided with a positioning hole extending radially along the transmission shaft. The positioning element is inserted into the positioning hole and abuts against the outer wall of the transmission shaft to complete the positioning and locking function.

[0013] Furthermore, the worm includes a main worm and extension rods located at both ends in the extension direction of the main worm. The main worm and the extension rods are connected by a thread, which can adapt to adjust the length of the main worm as needed.

[0014] Furthermore, the two extension rods are respectively inserted into the fixed base and fitted with a clearance to facilitate their assembly and disassembly and the rotation of the worm gear.

[0015] Furthermore, adjustment grooves extending radially along the main worm are respectively provided on the two opposite end faces of the two extension rods, which makes it easier to rotate the worm for adjustment.

[0016] Furthermore, a double-row angular contact ball bearing is provided between the second gear and the worm gear. The double-row angular contact ball bearing is sleeved on the transmission shaft, and its two sides abut against the second gear and the worm gear respectively, so as to restrict the movement of the backlash-free gear along the axial direction close to the second gear and reduce friction factors.

[0017] Furthermore, the first gear, the second gear, and the backlash-eliminating gear are helical gears, which further improves the meshing degree of the device.

[0018] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the gear transmission device of this utility model after the fixing seat has been removed;

[0020] Figure 2 This is a partial schematic diagram of the gear transmission device of this utility model;

[0021] Figure 3 This is an exploded view of the worm gear of this utility model;

[0022] Figure 4 This is a side perspective view of the gear transmission device of this utility model after the backlash-eliminating gear has been removed;

[0023] Figure 5 The right view of the gear transmission device of this utility model after removing the backlash-eliminating gear and locking unit;

[0024] Figure 6 This is a schematic diagram of the keyway structure of the gear transmission device of this utility model;

[0025] Figure 7 This is a side perspective view of the mounting base of the gear transmission device of this utility model;

[0026] Reference numerals: 10, first gear; 20, second gear; 22, keyway; 24, fixed key; 30, adjusting mechanism; 31, backlash-eliminating gear; 32, fixed seat; 33, worm gear; 34, worm; 35, locking unit; 322, base plate; 324, side wall; 326, through hole; 342, main worm; 344, extension rod; 346, adjusting groove; 352, positioning ring; 354, positioning hole; 356, positioning element; 40, drive shaft; 50, double-row angular contact ball bearing. Detailed Implementation

[0027] In response to the issue that poor meshing between the driven and driving gears is prone to occur in existing double-gear staggered tooth structures after a certain period of use, the applicant analyzed and studied the existing double-gear staggered tooth structures used to eliminate gear backlash. It was found that existing double-gear staggered tooth structures usually have slots or mounting holes on the side of the gears to accommodate elastic elements (such as springs) connected between the two gears as an adjustment mechanism. The preload of the elastic element drives the two gears to generate angular displacement in opposite directions, thereby achieving dynamic compensation of tooth backlash. However, this scheme has several inherent defects: First, the slots / holes on the side of the gear pose a hidden danger to the reliability of the entire gear transmission system. On the one hand, the slot / hole structure reduces the effective bearing area of ​​the gear body by 20%-30%, and the stress concentration coefficient is 1.5-2 times higher than that of a complete gear. Under high-frequency meshing impact, fatigue cracks are easily generated at the edge of the slot, significantly reducing the bending fatigue life of the gear. On the other hand, the asymmetrical slot / hole distribution disrupts the radial mass balance of the gear, resulting in uneven weight distribution along the radial direction. This causes periodic radial off-center loading when the gear is running at high speed. This off-center loading further induces bending deformation and wear of the gear shaft, causing the center distance between the driving gear and the driven gear to shift, which in turn leads to poor meshing between the gears. Second, elastic elements such as springs are significantly affected by environmental factors such as temperature conditions. Under long-term alternating loads, they are prone to fatigue relaxation. The preload decay rate increases exponentially with working time. Typically, after 1000 hours of operation, the preload loss can reach more than 30%, eventually losing the clearance compensation capability, which directly affects the transmission accuracy and stability of the gear system.

[0028] To address this, the applicant proposes a gear transmission device that eliminates gear backlash without requiring slots or mounting holes on the gear side. This device, based on the traditional meshing transmission of a first and second gear, adds an adjustment mechanism. This mechanism includes a backlash-eliminating gear coaxially mounted with the second gear, a worm gear and worm connecting the second gear and the backlash-eliminating gear, and a fixed base evenly distributed around the shaft. By fixing the fixed base coaxially to the second gear, the worm gear coaxially to the backlash-eliminating gear, and the worm gear symmetrically arranged axially and rotatably mounted on the fixed base to mesh with the worm gear, the mass distribution on the shaft of the gear transmission device becomes more uniform. This avoids the problems of reduced gear strength, stress concentration, and center of gravity shift caused by traditional slotted designs, improving gear meshing while ensuring the stability of the gear system during high-speed rotation.

[0029] To enable those skilled in the art to better understand this utility model, the technical solution of this utility model will be further described below in conjunction with the accompanying drawings and embodiments.

[0030] Please see Figure 1-2 This is a schematic diagram of the overall structure of the gear transmission device of this application. The gear transmission device includes a first gear 10, a second gear 20, an adjusting mechanism 30, and a transmission shaft 40. The first gear 10 is either a driving gear or a driven gear, while the second gear 20 is correspondingly either a driven gear or a driving gear. The axes of the second gear 20 and the first gear 10 are both parallel to and mesh with the axis of the transmission shaft 40, and the second gear 20 is sleeved on the transmission shaft 40 and coaxially driven with it. The adjusting mechanism 30 is mounted on the transmission shaft 40 and cooperates with the second gear 20 to adjust the meshing clearance with the first gear 10.

[0031] Specifically, the adjusting mechanism 30 includes a backlash-eliminating gear 31, a fixed base 32, a worm gear 33, and a worm 34. The transmission shaft 40 passes through the middle of the backlash-eliminating gear 31 and the second gear 20, and the backlash-eliminating gear 31 can rotate about its axis relative to the second gear 20. As the backlash-eliminating gear 31 rotates, one tooth of the second gear 20 and one tooth of the backlash-eliminating gear 31 can simultaneously mesh into the same meshing groove of the first gear 10. The fixed base 32 is disposed between the second gear 20 and the backlash-eliminating gear 31 and is fixedly connected to one of the second gear 20 and the backlash-eliminating gear 31, and the worm gear 33 is fixedly connected to the other. The fixed base 32 can be a bracket or annular structure evenly distributed around the transmission shaft 40. In this embodiment, the fixed base 32 includes a base plate 322 and a side wall 324. The base plate 322 is a circular plate structure, and its plate surface is in contact with the side of the second gear 20 facing the backlash-eliminating gear 31 and is coaxial with the second gear 20. The sidewall 324 extends around the outer periphery of the base plate 322 and protrudes toward the backlash-eliminating gear 31, thus forming a ring structure. The fixed seat 32 can be integrally formed with the second gear 20 through a precision casting process; the worm 34 is mounted on the fixed seat 32, and its extension direction is perpendicular to the axis of the transmission shaft 40. The sidewall 324 of the fixed seat 32 is provided with two through holes 326 for the two ends of the worm 34 to pass through. The worm wheel 33 is located on the side of the backlash-eliminating gear 31 facing the second gear 20 and is coaxial with the backlash-eliminating gear 31. The worm 34 is rotatably mounted on the fixed seat 32 and meshes with the worm wheel 33. In this embodiment, the worm wheel 33 and the backlash-eliminating gear 31 are integrally formed through a differential pressure casting process to ensure that the coaxiality error is less than 0.02 mm.

[0032] In this embodiment, the worm gear 34 adopts a three-section modular structure. Please refer to [link / reference]. Figure 3 The worm 34 includes a main worm 342 and extension rods 344 located at both ends of the main worm 342 in its extension direction. The segments are threaded together via trapezoidal internal and external threads to accommodate different axial length requirements. During installation, the worm 34 is first disassembled into three parts. The main worm 342 is placed inside the fixed base 32. Then, the extension rods 344 are inserted through the through holes 326 of the fixed base 32, and finally assembled with the two ends of the main worm 342 through threaded rotation. A gap exists between the extension rods 344 and the through holes 326 to facilitate their assembly, disassembly, and rotation of the worm 34. Furthermore, the opposite end face of the extension rods 344 is provided with an adjustment groove 346 extending radially along the main worm 342. The adjustment groove can be a slotted groove, a cross groove, or a hexagonal blind hole to facilitate adjustment of the worm's rotation angle. In this embodiment, a slotted groove is preferred.

[0033] During adjustment, the first gear 10 and the backlash-eliminating gear 31 are respectively provided with a first tooth surface and a second tooth surface facing opposite directions in one of the meshing tooth grooves, wherein the first tooth surface of the first gear 10 is in contact with one side tooth surface of one of the meshing tooth grooves of the second gear 20; rotating the worm 34 on the second gear 20 or the backlash-eliminating gear 31 can drive the worm wheel 33 to rotate, and the second tooth surface of the backlash-eliminating gear 31 will turn to the other side tooth surface of one of the meshing tooth grooves of the second gear 20 until it is in contact with it, thereby realizing the adjustment of the tooth gap.

[0034] The second gear 20 and the transmission shaft 40 can be fixedly connected by means including key connection, interference fit, or welding, to achieve the effect of coaxial rotation of the second gear 20 and the transmission shaft 40. In this embodiment, the second gear 20 and the transmission shaft 40 are connected by a fixing key 24. Specifically, a fixing key 24 with an interference fit is provided on the outer surface of the transmission shaft 40. A keyway 22 extending along the axis of the transmission shaft 40 is provided on the contact surface between the second gear 20 and the transmission shaft 40. In this embodiment, the keyway 22 passes through the bottom plate 322 of the fixing seat 32 from the second gear 20. The fixing key 24 is inserted into the keyway 22 to fix the second gear 20 and the fixing seat 32 to the transmission shaft 40. The backlash-free gear 31 and the worm gear 33 are sleeved on the outside of the transmission shaft 40 through a central hole, and the two form a clearance fit with the transmission shaft 40, thereby being able to rotate relative to the transmission shaft. The backlash-free gear 31 and the worm gear 33 are sleeved outside the transmission shaft 40 to achieve relative rotation with the shaft.

[0035] Furthermore, the adjusting mechanism 30 also includes a locking unit 35, which includes a positioning ring 352 and a positioning element 356. The positioning ring 352 is sleeved on the outside of the transmission shaft 40 and located on the side of the backlash-eliminating gear 31 facing away from the second gear 20, abutting against the backlash-eliminating gear 31 to restrict the backlash-eliminating gear 31 from moving away from the second gear 20 along the axial direction. The positioning ring 352 has a positioning hole 354 extending radially along the transmission shaft 40. The positioning element 356 is inserted into the positioning hole 354 and abuts against the outer wall of the transmission shaft 40 to complete the positioning and locking function. In this embodiment, the positioning element 356 is preferably a locking screw. The positioning ring 352 and the positioning element 356 are rotated and engaged by threaded engagement. The positioning element 356 and the transmission shaft 40 are connected with a sandblasted layer to increase friction and restrict the axial movement of the backlash-eliminating gear 31.

[0036] A double-row angular contact ball bearing 50 is also provided between the second gear 20 and the worm gear 33. The double-row angular contact ball bearing 50 is sleeved on the transmission shaft 40, and its two sides on the axis respectively abut against the second gear 20 and the worm gear 33. In this embodiment, the double-row angular contact ball bearing 50 is disposed between the base plate 322 of the fixed seat 32 and the worm gear 33, and abuts against both of them, so as to restrict the movement of the backlash-free gear 31 along the axis direction close to the second gear 20 and reduce friction factors.

[0037] Preferably, the first gear, the second gear, and the backlash-eliminating gear are all helical gears. Helical gears can change the tooth surface contact line from a straight line to an oblique line, and have a higher degree of overlap. The number of meshing teeth increases, which can distribute the contact pressure more evenly, making the load distribution more uniform and improving the backlash elimination effect.

[0038] In specific implementation, the adjusting groove 346 of the worm 34 is rotated, causing the worm wheel 33 to rotate, which in turn drives the backlash-eliminating gear 31 to rotate. At this time, the backlash-eliminating gear 31 rotates relative to the transmission shaft 40. Since the second gear 20 is fixed to the transmission shaft 40, the backlash-eliminating gear 31 rotates relative to the second gear 20, causing the backlash-eliminating gear 31 to be coaxially offset from the second gear 20 by a certain angle. This continues until the two opposing tooth surfaces on the second gear 20 and the backlash-eliminating gear 31 respectively abut against the two opposing gears in the same tooth groove of the first gear 10, achieving complete meshing with the first gear 10. When the gear backlash is eliminated, the rotation of the worm 34 can be stopped. At this time, due to the self-locking property between the worm wheel and the worm, the worm wheel 33 cannot drive the worm 34 in the opposite direction due to load vibration, tooth surface impact, or other factors. This prevents the angle of the backlash-eliminating gear 31 relative to the second gear 20 from regressing, ensuring that the backlash-eliminating gear set 20 and the first gear 10 remain fully meshed, ensuring precise and stable meshing.

[0039] To restore to the original state or disassemble the components, simply rotate the worm 34 in the opposite direction via the adjustment groove 346. This reverse rotation of the worm 34 will cause the worm wheel 33 to rotate in the opposite direction, thereby restoring the backlash-free gear set 20 and the first gear 10 to a state where there is meshing clearance.

[0040] Compared to existing technologies, this invention adds an adjustment mechanism, eliminating the need for slots or mounting holes on the sides of the gears to adjust and eliminate gear meshing backlash, thus improving the meshing degree. Furthermore, by setting a fixed seat evenly distributed around the shaft to balance the worm gear, the mass distribution on the transmission shaft is more uniform, avoiding the center of gravity shift problem caused by traditional asymmetrical slot / hole designs, thereby improving the stability of the gear transmission. Further, by setting a locking unit to restrict the axial movement of the backlash-eliminating gears and using double-row angular contact ball bearings to reduce friction between the worm gear and the fixed seat, and by employing helical gears, the overall operation of the device is optimized, further enhancing the meshing effect between the gears. Simultaneously, the worm gear adopts a three-section modular structure, making disassembly and installation more convenient, and the adjustment groove at one end of its extension rod facilitates adjustment of gear meshing backlash.

[0041] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” means two or more; the terms “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. The term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0042] This utility model is not limited to the above-described embodiments. If any modifications or variations to this utility model do not depart from the spirit and scope of this utility model, and if such modifications and variations fall within the scope of the claims and equivalent technologies of this utility model, then this utility model also intends to include such modifications and variations.

Claims

1. A gear transmission device, comprising a first gear, a second gear, an adjusting mechanism, and a transmission shaft; the first gear meshes with the second gear for transmission; the adjusting mechanism comprises a backlash-eliminating gear, a fixed base, a worm, and a worm wheel; The backlash-free gear is coaxially mounted on the transmission shaft with the second gear. The second gear rotates with the transmission shaft, and the backlash-free gear can rotate relative to the second gear around the transmission shaft. The second gear and one of the teeth of the backlash-free gear can simultaneously mesh into the same tooth groove of the first gear; the fixed seat is disposed between the second gear and the backlash-free gear and is fixedly connected to one of the second gear and the backlash-free gear; the worm gear is coaxially fixedly connected to the other; the fixed seat is uniformly arranged around the transmission shaft; the worm is rotatably disposed on the fixed seat and meshes with the worm gear.

2. A gear transmission as claimed in claim 1, characterised in that: The worm extends in a direction perpendicular to the axis of the transmission shaft.

3. A gear transmission as claimed in claim 2, characterised in that: The fixed base has an annular structure extending around the axis of the transmission shaft, and its side wall is provided with two through holes for the two ends of the worm gear to pass through.

4. A gear transmission as claimed in claim 3, characterised in that: The second gear has a keyway extending axially along the transmission shaft in the middle, and a fixing key protrudes from the outer side of the transmission shaft, the fixing key being engaged in the keyway.

5. A gear transmission as claimed in claim 4, characterised in that: The adjustment mechanism further includes a locking unit, which includes a positioning ring and a positioning element. The positioning ring is sleeved on the outside of the transmission shaft and located on the side of the backlash-eliminating gear facing away from the second gear, abutting against the backlash-eliminating gear. The positioning ring has a positioning hole extending radially along the transmission shaft. The positioning element is inserted into the positioning hole and abuts against the outer wall of the transmission shaft.

6. A gear transmission as claimed in claim 5, characterised in that: The worm gear includes a main worm and extension rods located at both ends in the extension direction of the main worm, and the main worm and the extension rods are connected by threads.

7. A gear transmission as claimed in claim 6, characterised in that: The two extension rods are respectively inserted into the fixed base and fitted with a clearance.

8. A gear transmission as claimed in claim 7, characterised in that: Adjustment grooves extending radially along the main worm are respectively provided on the two opposite end faces of the two extension rods.

9. A gear transmission as claimed in claim 8, characterised in that: A double-row angular contact ball bearing is also provided between the second gear and the worm gear. The double-row angular contact ball bearing is sleeved on the transmission shaft, and its two sides abut against the second gear and the worm gear respectively.

10. A gear transmission as claimed in any one of claims 1 to 9, characterised in that: The first gear, the second gear, and the backlash-eliminating gear are helical gears.

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