A multi-stage reduction flexible shaft adaptive zero-backlash gearbox and its backlash elimination assembly method

Abstract

This invention provides a multi-stage reduction gearbox with a flexible shaft and an adaptive zero-backlash gearbox, and its backlash elimination assembly method. The gearbox includes a housing and a multi-stage gear transmission mechanism, and also includes a backlash elimination mechanism. The backlash elimination mechanism includes a backlash elimination gear set meshing with each stage of the gear pair, a flexible shaft, and a locking mechanism, forming a parallel backlash elimination transmission branch. During assembly, a reverse preload is applied to the backlash elimination gear set to cause the flexible shaft to twist and deform, and then the locking mechanism locks it to maintain an elastic preload state. This invention uses a single backlash elimination mechanism to simultaneously eliminate backlash in multiple stages, simplifying assembly; it utilizes the elastic restoring torque of the flexible shaft instead of rigid fixing, providing impact resistance and reliable operation; it can adaptively compensate for backlash after gear wear, achieving zero-backlash transmission throughout its lifespan; it reduces the requirements for bearing precision and significantly reduces manufacturing costs.

Description

Technical Field

[0001] This invention relates to the technical field, specifically to a multi-stage reduction flexible shaft adaptive zero-backlash gearbox and its backlash elimination assembly method. Background Technology

[0002] Gearboxes, as core components of mechanical transmission systems, are widely used in various industrial equipment. In the field of high-speed round bar and steel pipe sawing, the transmission accuracy of the gearbox directly determines the sawing quality. During the sawing process, if there is backlash in the gear pair at the moment the saw blade contacts the workpiece, the instantaneous impact of the driving torque will cause the saw blade to vibrate and shake, leading to serious quality problems such as broken saw blade teeth, uneven saw cut surfaces, and reduced workpiece dimensional accuracy. Therefore, such high-speed sawing gearboxes place extremely stringent requirements on zero-backlash transmission of the gear pair; any minute backlash can directly affect the final sawing product quality.

[0003] To eliminate backlash in gear pairs, existing multi-stage reduction gearboxes typically employ the following technical solutions to achieve backlash elimination and ensure spindle rotation accuracy: First, each gear pair within the gearbox is equipped with an independent backlash elimination mechanism, eliminating backlash at each stage through step-by-step adjustments. Second, high-precision P5-grade cylindrical roller bearings with tapered bores are selected, and the bearing clearance is finely adjusted during assembly to ensure spindle rotation accuracy. Third, backlash elimination adjustment is primarily achieved through the reverse rotational displacement of the backlash elimination gear. Once the backlash is eliminated, bolts are used to axially rigidly fix the backlash elimination gear to maintain the backlash-free state. Fourth, after the gearbox assembly is completed, spindle runout is tested. If the test results are unsatisfactory, the backlash and bearing clearance must be repeatedly adjusted until the accuracy requirements are met.

[0004] However, the aforementioned existing technologies have revealed many shortcomings in practical applications. First, since each gear pair in a multi-stage reduction gearbox needs to be backlash-eliminating separately, the backlash elimination process requires repeated disassembly and reassembly of the gearbox. Furthermore, adjusting the backlash of a single gear pair often affects the meshing state of other gear pairs, making the adjustment process extremely cumbersome. Repeated disassembly and reassembly during assembly not only consumes a significant amount of time but also easily damages components, resulting in low assembly efficiency. Second, the P5-grade high-precision cylindrical roller bearings mounted in tapered bores are themselves expensive, and the tapered bore surface of the journal bearings that mate with them requires precision grinding. This places extremely high demands on the machining process of the components, making machining difficult and resulting in a high overall manufacturing cost for the gearbox. Third, the method of axially fixing the backlash-eliminating gears with bolts is a rigid fixation. Under harsh operating conditions where the gearbox is subjected to sawing impact loads, the bolts are prone to loosening, and the backlash-eliminating gears are prone to relative displacement. This causes the backlash elimination state of the gearbox to frequently fail during operation, making it difficult to guarantee reliability. More importantly, gear pairs inevitably experience tooth surface wear during long-term operation, and the tooth backlash gradually increases after wear. However, the existing backlash elimination mechanism lacks the ability to adaptively compensate for wear. Once the tooth backlash exceeds the allowable range, the machine needs to be stopped and readjusted, resulting in high equipment maintenance costs and long downtime, which seriously affects the continuous operation capability of the sawing production line.

[0005] In summary, existing technologies, when applied to high-speed sawing multi-stage reduction gearboxes, generally suffer from several technical problems, including cumbersome backlash elimination adjustment processes, high precision requirements for component machining, high manufacturing costs, weak impact resistance of the backlash elimination mechanism, and the inability to achieve adaptive backlash compensation after wear. These issues make it difficult to simultaneously meet the comprehensive performance requirements of high-speed sawing equipment for gearboxes that are low-cost, highly reliable, long-lasting, and maintenance-free. Therefore, it is necessary to propose a novel, low-cost, reliable multi-stage reduction gearbox zero-backlash transmission technology solution with wear adaptive compensation capabilities to address the aforementioned problems in existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-stage reduction gearbox with a flexible shaft and an adaptive zero-backlash gearbox and a backlash elimination assembly method thereof. By setting a backlash elimination transmission branch in parallel with the main drive in the multi-stage reduction gearbox, the torsional elastic deformation of the flexible shaft is used to provide a continuous circumferential preload for the backlash elimination gear set, and the elastic deformation is locked and sealed from the input end by a spline coupling sleeve, thereby realizing zero-backlash transmission and wear adaptive compensation of multi-stage gear pairs with a single mechanism.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A multi-stage reduction flexible shaft adaptive zero-backlash gearbox includes a housing and a multi-stage gear transmission mechanism disposed within the housing. The multi-stage gear transmission mechanism includes an input gear shaft, an output gear shaft, and at least one intermediate transmission gear pair disposed between the input gear shaft and the output gear shaft. The gearbox further includes a backlash elimination mechanism, which includes a backlash elimination gear set, a flexible shaft, and a coupling locking mechanism. The backlash elimination gear set includes multiple backlash elimination gears, and each backlash elimination gear pair meshes and forms a backlash elimination transmission branch in parallel with the multi-stage gear transmission mechanism, wherein at least... Part of the backlash-free gear is loosely fitted on the shaft; one end of the flexible shaft is connected to one of the backlash-free gears in the backlash-free gear set, and the other end is connected to the output gear shaft. The flexible shaft is in a torsional elastic deformation state in the assembled state to apply a continuous circumferential preload to the backlash-free gear set; the coupling locking mechanism is connected between the input gear shaft and another backlash-free gear in the backlash-free gear set, and is used to lock the input gear shaft and the backlash-free gear set after the flexible shaft undergoes torsional elastic deformation, so as to maintain the torsional elastic deformation state of the flexible shaft.

[0008] Furthermore, the module and number of teeth of each backlash-free gear in the backlash-free gear set are consistent with the module and number of teeth of the corresponding meshing gear pair in the multi-stage gear transmission mechanism.

[0009] Furthermore, in the backlash-free gear set, at least two of the backlash-free gears that are hollowly fitted onto the shaft are made from a single blank.

[0010] Furthermore, the connection locking mechanism is an axially movable spline coupling sleeve. The inner spline and outer spline of the axially movable spline coupling sleeve are respectively engaged with the outer spline of the input gear shaft and the inner spline of the backlash-free gear in the backlash-free gear set. The axially movable spline coupling sleeve realizes the engagement or disengagement between the input gear shaft and the backlash-free gear set by moving axially.

[0011] Furthermore, an axially movable spline coupling sleeve is also provided with an axial limiting component, which is used to restrict the axial movement of the axially movable spline coupling sleeve after it moves to the engagement position.

[0012] Furthermore, the flexible shaft has an elastic deformation section between its two ends for generating torsional elastic deformation.

[0013] Furthermore, the torsional stiffness of the elastic deformation section of the flexible shaft satisfies the following: within the range of tooth backlash increments caused by tooth surface wear in each gear pair of the multi-stage gear transmission mechanism, the torsional elastic restoring torque of the flexible shaft can continuously eliminate the tooth backlash.

[0014] Furthermore, the input gear shaft and the output gear shaft are respectively supported on the housing by cylindrical bore bearings.

[0015] Furthermore, each gear pair in the multi-stage gear transmission mechanism is a cylindrical gear pair, and each backlash-free gear in the backlash-free gear set is a cylindrical gear that meshes with the corresponding cylindrical gear pair.

[0016] The present invention also provides a backlash elimination assembly method for a multi-stage reduction flexible shaft adaptive zero-backlash gearbox as described above, characterized by comprising the following steps: S1: Install the input gear shaft, output gear shaft, and intermediate transmission gear pair of the multi-stage gear transmission mechanism into the housing, and mesh and assemble each backlash-free gear pair in the backlash-free gear set, wherein the empty backlash-free gear is loosely fitted on the corresponding shaft, and at the same time connect one end of the flexible shaft to one of the backlash-free gears in the backlash-free gear set and the other end to the output gear shaft; S2: Apply a reverse preload force relative to the driving direction of the multi-stage gear transmission mechanism to the backlash-free gear set, so that the tooth surface of each backlash-free gear is in close contact with the non-working tooth surface of the corresponding gear in the intermediate transmission gear pair, thereby eliminating the tooth backlash of each stage of the gear pair and causing the flexible shaft to undergo torsional elastic deformation; S3: While the flexible shaft remains in a state of torsional elastic deformation, the input gear shaft is locked to the backlash-free gear set by the coupling locking mechanism, so that the torsional elastic restoring torque of the flexible shaft continues to act on the backlash-free gear set; S4: Release the reverse preload applied to the backlash-free gear set to complete the backlash-free assembly of the gearbox.

[0017] Compared with the prior art, the present invention has the following advantages: I. This invention sets up a backlash-eliminating transmission branch in parallel with the multi-stage gear transmission mechanism, and integrates a backlash-eliminating gear set, a flexible shaft, and a connecting locking mechanism in this backlash-eliminating transmission branch. Only one backlash-eliminating mechanism is needed to simultaneously eliminate the tooth backlash of each gear pair in the multi-stage gear transmission mechanism. This overcomes the problems of cumbersome assembly process, repeated disassembly and assembly of the gearbox, and low assembly efficiency caused by the need to adjust the backlash of each gear pair separately in the prior art. It significantly simplifies the backlash-eliminating assembly process of the multi-stage reduction gearbox and greatly improves the assembly efficiency of the gearbox.

[0018] Second, this invention creatively utilizes the torsional elastic deformation of a flexible shaft to provide a continuous circumferential preload for the backlash-eliminating gear set, replacing the existing method of using bolts to rigidly fix the backlash-eliminating gears axially. Because the torsional elastic restoring torque of the flexible shaft is a continuously acting elastic preload, even when the gearbox is subjected to sawing impact loads, the flexible shaft can still stably maintain the required circumferential preload state of the backlash-eliminating gear set. This fundamentally solves the reliability problem of existing rigid-fixed backlash-eliminating methods being prone to loosening under impact conditions and frequent failures in the backlash-eliminating state, significantly improving the impact resistance and operational reliability of the backlash-eliminating mechanism.

[0019] Third, the flexible shaft in this invention features a specific torsional stiffness design in its elastic deformation section. When the gear pair experiences increased backlash due to tooth surface wear during long-term operation, the flexible shaft can release its stored elastic deformation energy to automatically drive the backlash-eliminating gear set to further eliminate the newly generated backlash, thus ensuring that the transmission system maintains a zero-backlash transmission state throughout its entire lifespan. This wear-adaptive compensation capability is not present in existing backlash-eliminating mechanisms, effectively solving the problems of high maintenance costs and long downtime caused by the need for shutdown and readjustment after backlash wear in existing technologies. This gives the gearbox a long lifespan and maintenance-free operating characteristics.

[0020] Fourth, since the backlash elimination mechanism of this invention relies on the elastic preload of the flexible shaft, the dependence on the rotational accuracy of the main shaft is reduced accordingly. Therefore, the input gear shaft and the output gear shaft can be supported by ordinary cylindrical bore bearings, eliminating the need to select expensive tapered bores to install P5 grade high-precision cylindrical roller bearings, and eliminating the need to perform matching grinding on the tapered bore surface of the journal. This greatly reduces the processing difficulty of the parts and significantly reduces the overall manufacturing cost of the gearbox.

[0021] Fifth, since the present invention only requires applying a reverse preload force to the backlash elimination gear set once during the assembly process and locking it through the connection locking mechanism to complete the backlash elimination, it avoids the cumbersome process of repeatedly adjusting the backlash and bearing clearance due to the failure of the spindle runout test in the prior art. This makes the gearbox assembly process simpler and more controllable, and effectively improves the assembly qualification rate. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the multi-stage reduction flexible shaft adaptive zero-backlash gearbox of the present invention.

[0023] In the picture: 1. Housing; 2. Input gear shaft; 3. Output gear shaft; 4. Intermediate transmission gear pair; 5. Backlash-free gear set; 5-1. Backlash-free gear one; 5-2. Backlash-free gear two; 5-3. Backlash-free gear three; 5-4. Backlash-free gear four; 5-5. Backlash-free gear five; 6. Flexible shaft; 6-1. Elastic deformation section; 7. Axially movable spline coupling sleeve; 8. Axial limiting component; 9. Cylindrical bore bearing. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] This invention provides a multi-stage reduction flexible shaft adaptive zero-backlash gearbox, primarily used in high-speed sawing of round bars and steel pipes, but not limited to this application. During high-speed sawing, the impact of the driving torque at the moment the saw blade contacts the workpiece acts on the gear transmission chain. If backlash exists in the gear pair, this impact torque will cause the saw blade to vibrate and shake, leading to broken teeth and uneven cut surfaces. Therefore, the core problem this invention aims to solve is to eliminate backlash in a multi-stage reduction gearbox and maintain this backlash-free state throughout the entire service life of the gearbox.

[0027] This invention provides a multi-stage reduction flexible shaft adaptive zero-backlash gearbox, primarily used in high-speed sawing of round bars and steel pipes, but not limited to this application. During high-speed sawing, the impact of the driving torque at the moment the saw blade contacts the workpiece acts on the gear transmission chain. If backlash exists in the gear pair, this impact torque will cause the saw blade to vibrate and shake, leading to broken teeth and uneven cut surfaces. Therefore, the core problem this invention aims to solve is to eliminate backlash in a multi-stage reduction gearbox and maintain this backlash-free state throughout the entire service life of the gearbox.

[0028] Please see Figure 1In this embodiment, the gearbox includes a housing 1 and a multi-stage gear transmission mechanism disposed within the housing 1. The multi-stage gear transmission mechanism includes an input gear shaft 2, an output gear shaft 3, and at least one intermediate transmission gear pair 4 disposed between the input gear shaft 2 and the output gear shaft 3. The input gear shaft 2 receives power input from the drive motor, which is then reduced in speed through the multi-stage gear transmission mechanism before being output to the working end by the output gear shaft 3. In this embodiment, the gearbox is a gearbox for a high-speed sawing device, and the output end of the output gear shaft 3 is used to connect the saw blade. Each intermediate transmission gear pair 4 in the multi-stage gear transmission mechanism is a cylindrical gear pair, that is, both the driving gear and the driven gear of each intermediate transmission gear pair 4 are cylindrical gears. It should be understood that the specific number of stages in the multi-stage gear transmission mechanism can be designed according to the actual reduction ratio requirements, and this invention does not limit this.

[0029] The key feature of this invention is the inclusion of a backlash elimination mechanism within the gearbox. This mechanism operates independently of the main transmission chain of the multi-stage gear transmission mechanism, forming a parallel backlash elimination transmission branch. The backlash elimination mechanism comprises three core components: a backlash elimination gear set 5, a flexible shaft 6, and an axially movable splined coupling sleeve 7. The force flow path of the backlash elimination transmission branch is as follows: input gear shaft 2 → axially movable splined coupling sleeve 7 → backlash elimination gear five 5-5 → backlash elimination gear four 5-4 → backlash elimination gear three 5-3 → backlash elimination gear one 5-1 → backlash elimination gear two 5-2 → flexible shaft 6 → output gear shaft 3. The structure and function of these three components will be described in detail below.

[0030] The backlash-eliminating gear set 5 consists of multiple backlash-eliminating gears, specifically including backlash-eliminating gear 5-1, 5-2, 5-3, 5-4, and 5-5 in this embodiment. These backlash-eliminating gears mesh to form a complete backlash-eliminating transmission branch connected in parallel with the main transmission chain. To ensure proper meshing and synchronous backlash elimination, the module and number of teeth of each backlash-eliminating gear in the backlash-eliminating gear set 5 are consistent with the module and number of teeth of the corresponding transmission gears meshing in the multi-stage gear transmission mechanism. In this embodiment, all backlash-eliminating gears in the backlash-eliminating gear set 5 are cylindrical gears.

[0031] The installation method and interrelationship of the backlash-eliminating gears in the backlash-eliminating gear set 5 are important structural features of the backlash-eliminating mechanism of this invention. Backlash-eliminating gear one 5-1 and backlash-eliminating gear three 5-3 are integral components. Backlash-eliminating gear one 5-1, backlash-eliminating gear three 5-3, and backlash-eliminating gear four 5-4 are all loosely fitted onto their respective shafts; that is, there is no fixed connection between these three backlash-eliminating gears and their respective shafts, allowing them to rotate freely relative to the shafts. It should be explained here that "loosely fitted" means that the inner hole of the backlash-eliminating gear is in clearance fit with the shaft; the backlash-eliminating gear is not circumferentially locked to the shaft through key connections, interference fits, or other fixing methods. In the backlash-eliminating transmission branch, the torque of backlash-eliminating gear two 5-2 is transmitted to backlash-eliminating gear five 5-5 via backlash-eliminating gear one 5-1, backlash-eliminating gear three 5-3, and backlash-eliminating gear four 5-4.

[0032] Backlash-eliminating gear 2 5-2 is located at the output end of the backlash-eliminating transmission branch and is connected to the flexible shaft 6. It is the object directly affected by the elastic preload of the flexible shaft 6. Backlash-eliminating gear 5-5 is located at the input end of the backlash-eliminating transmission branch and is connected to the axially movable spline coupling sleeve 7. It is the interface through which the locking mechanism locks the backlash-eliminating transmission branch to the input gear shaft 2.

[0033] The flexible shaft 6 is the core functional component of the backlash elimination mechanism of this invention. The flexible shaft 6 is connected to the output end of the backlash elimination transmission branch. Specifically, one end of the flexible shaft 6 is connected to the backlash elimination gear 5-2, and the other end is connected to the output gear shaft 3. The flexible shaft 6 has an elastic deformation section 6-1 between its two ends for generating torsional elastic deformation. The term "flexible shaft 6" refers to a shaft that can generate a certain angle of torsional elastic deformation under torque and can stably store elastic deformation energy after deformation, returning to its original shape when the external force is removed. This differs from a rigid transmission shaft, which hardly undergoes observable elastic torsional deformation under normal operating conditions. The torsional stiffness of the flexible shaft 6 is a key design parameter, and its torsional stiffness must meet the following condition: within the range of tooth backlash increments caused by tooth surface wear in each stage of the intermediate transmission gear pair 4 of the multi-stage gear transmission mechanism, the torsional elastic restoring torque of the flexible shaft 6 can continuously eliminate tooth backlash. In other words, the elastic deformation stored in the flexible shaft 6 during initial assembly should be large enough so that, throughout its entire service life, even if the tooth surfaces of the intermediate transmission gear pairs 4 experience a certain degree of wear, the elastic restoring torque of the flexible shaft 6 is still sufficient to drive the backlash-eliminating gear set 5 to eliminate the new tooth backlash caused by wear. The elastic deformation section 6-1 of the flexible shaft 6 can achieve the required torsional stiffness by selecting appropriate materials, cross-sectional dimensions, and lengths. In specific design, it can be calculated and determined based on the transmission torque of the gearbox, the expected wear of the intermediate transmission gear pairs 4, and the required backlash-eliminating preload torque.

[0034] An axially movable splined coupling sleeve 7 is disposed at the input end of the backlash-free transmission branch, connecting the input gear shaft 2 and the backlash-free gear set 5-5. It is used to lock the input gear shaft 2 and the backlash-free gear set 5 together after the flexible shaft 6 undergoes torsional elastic deformation, thus maintaining the torsional elastic deformation state of the flexible shaft 6. One internal spline of the axially movable splined coupling sleeve 7 mates with the external spline of the input gear shaft 2, and the other internal spline mates with the external spline of the backlash-free gear set 5-5. The axially movable splined coupling sleeve 7 achieves engagement or disengagement between the input gear shaft 2 and the backlash-free gear set 5-5 by moving axially. When the axially movable splined coupling sleeve 7 is in the disengaged state, there is no torque transmission relationship between the input gear shaft 2 and the backlash-free gear set 5. The backlash-free gear set 5 is only connected to the output gear shaft 3 through the backlash-free gear 5-2 and the flexible shaft 6. At this time, torque can be freely applied to the backlash-free gear 5-5 for backlash-free adjustment. When the axially movable splined coupling sleeve 7 moves axially to the engaged position, the two internal splines of the axially movable splined coupling sleeve 7 mesh with the input gear shaft 2 and the backlash-free gear 5-5 respectively, thereby locking the input gear shaft 2 and the backlash-free gear set 5 into a whole. The backlash-free transmission branch forms a complete closed force flow loop, and the torsional elastic deformation state of the flexible shaft 6 is reliably maintained. It should be further explained here that the axially movable splined coupling sleeve 7 uses spline fit as the torque transmission method. Compared with ordinary flat key connection or friction fit, spline connection has the advantages of large load-bearing capacity, good centering, and strong guiding, and can withstand the impact load during gearbox operation without slippage or disengagement.

[0035] To further improve the reliability of the backlash elimination mechanism during gearbox operation, an axial limiting component 8 is also provided at the axially movable splined coupling sleeve 7. The axial limiting component 8 is used to restrict the axial movement of the axially movable splined coupling sleeve 7 after it has moved to the engagement position. In actual gearbox operation, due to the impact vibration of the sawing process, axial forces may be generated between the transmission components. If the axially movable splined coupling sleeve 7 is not axially limited, it may gradually move axially and disengage under long-term vibration conditions, leading to failure of the backlash elimination mechanism. The axial limiting component 8 can adopt conventional limiting methods such as snap rings, shaft shoulders, or lock nuts. This invention does not limit its specific form, as long as it can effectively prevent the axially movable splined coupling sleeve 7 from moving axially after it reaches the engagement position.

[0036] Regarding bearing selection, in this invention, the input gear shaft 2 and the output gear shaft 3 are respectively supported on the housing 1 by cylindrical bore bearings 9. Since the backlash elimination mechanism of this invention relies on the continuous elastic preload of the flexible shaft 6, the zero-backlash state of the gear pair no longer depends on extremely strict control of the spindle rotation accuracy. Therefore, ordinary cylindrical bore bearings 9 can be used instead of the P5-grade high-precision tapered roller bearings with tapered bores commonly used in the prior art. Ordinary cylindrical bore bearings 9 not only have a lower cost than P5-grade tapered bore bearings, but their mounting surface is a simple cylindrical surface, eliminating the need for grinding. This significantly reduces the processing difficulty of the components, thereby significantly reducing the overall manufacturing cost of the gearbox.

[0037] The following describes the gap-eliminating assembly method and gap-eliminating working principle of the present invention.

[0038] During the backlash-free assembly of the gearbox, the input gear shaft 2, output gear shaft 3, and intermediate transmission gear pair 4 of the multi-stage gear transmission mechanism are first installed into the housing 1, and the backlash-free gears in the backlash-free gear set 5 are then meshed and assembled. Specifically, backlash-free gear one 5-1, backlash-free gear three 5-3, and backlash-free gear four 5-4 are loosely fitted onto their respective shafts, backlash-free gear two 5-2 is connected to one end of the flexible shaft 6, and the other end of the flexible shaft 6 is connected to the output gear shaft 3. At this time, the axially movable spline coupling sleeve 7 is in a disengaged state, and a connection has not yet been established between the input gear shaft 2 and the backlash-free gear set 5.

[0039] Next, a reverse preload torque relative to the driving direction of the multi-stage gear transmission mechanism is applied to the backlash-eliminating gear 5-5 to eliminate the tooth backlash of each stage of the intermediate transmission gear pair 4. Specifically, a circumferential force opposite to the main drive direction is applied to the backlash-eliminating gear set 5 using an external tool or fixture, causing the tooth surfaces of each backlash-eliminating gear in the backlash-eliminating gear set 5 to come into close contact, thereby eliminating all the tooth backlash of each stage of the intermediate transmission gear pair 4. During the application of the reverse preload force, the backlash-eliminating gear 5-2 undergoes a circumferential angular displacement relative to the output gear shaft 3, and the flexible shaft 6 connects the backlash-eliminating gear 5-2 and the output gear shaft 3. As a result, the flexible shaft 6 is forced to undergo torsional elastic deformation, and the corresponding elastic deformation energy is stored in its elastic deformation segment 6-1. It should be explained here that, under the action of the reverse preload torque, the backlash elimination gears 5-1, 5-3, and 5-4 in the empty sleeve cause the torque at backlash elimination gear 2 5-2 to be transmitted to backlash elimination gear 5-5 through the entire backlash elimination gear set 5, thereby achieving synchronous elimination of tooth backlash in all rotating gear pairs.

[0040] Then, while the flexible shaft 6 remains in a state of torsional elastic deformation, the axially movable spline coupling sleeve 7 is moved axially to the engagement position, so that one internal spline of the axially movable spline coupling sleeve 7 meshes with the external spline of the input gear shaft 2, while the other internal spline meshes with the external spline of the backlash-free gear 5-5, thereby locking the input gear shaft 2 and the backlash-free gear 5-5 together. At this time, the backlash-free transmission branch forms a complete closed torque flow loop of "input gear shaft 2 → axially movable spline coupling sleeve 7 → backlash-free gear 5-5 → backlash-free gear 4-4 → backlash-free gear 1-5-1 → backlash-free gear 3-3 → backlash-free gear 2-5-2 → flexible shaft 6 → output gear shaft 3". The torsional elastic deformation of the flexible shaft 6 is "frozen" in the transmission branch by the locking action of the axially movable spline coupling sleeve 7, and its torsional elastic restoring torque continues to act on the backlash-free gear set 5, maintaining the zero backlash state of each stage of intermediate transmission gear pair 4. After the axially movable splined coupling sleeve 7 is assembled, the axial limiting component 8 is installed to axially limit the axially movable splined coupling sleeve 7.

[0041] Finally, the external reverse preload applied to the backlash-eliminating gear set 5-5 is released. Since the torsional elastic restoring torque of the flexible shaft 6 is continuously applied to the backlash-eliminating gear set 5 through the locking action of the axially movable splined coupling sleeve 7, even after the external reverse force is released, the backlash-eliminating gear set 5 remains tightly fitted under the elastic restoring torque of the flexible shaft 6, and the tooth flank backlash of each intermediate transmission gear pair 4 remains zero. At this point, the backlash-eliminating assembly process of the gearbox is complete.

[0042] During normal operation of the gearbox, the backlash elimination mechanism operates as follows: The multi-stage gear transmission mechanism undertakes the main power transmission function. Under the preload of the flexible shaft 6, the tooth surfaces of the backlash elimination gear set 5 remain in close contact. Under the elastic torque of the backlash elimination gear set 5, the tooth backlash of each intermediate transmission gear pair 4 remains zero. The empty-set backlash elimination gears 1-5-1, 3-3, and 4-4 transmit the preload applied by the flexible shaft 6 through backlash elimination gear 2-2 to backlash elimination gear 5-5, ensuring that each gear pair in the backlash elimination transmission branch is in a zero-backlash state. When the saw blade cuts the workpiece, the impact load is transmitted to the gear transmission chain through the output gear shaft 3. Since there is no tooth backlash in each intermediate transmission gear pair 4, the driving torque will not be momentarily interrupted or reversed, thus preventing the saw blade from vibrating and shaking, ensuring the flatness of the cut surface and the service life of the saw blade.

[0043] As the gearbox operates for longer periods, the tooth surfaces of the intermediate transmission gear pairs 4 at each stage inevitably wear, leading to a gradual increase in tooth flank clearance. At this point, the adaptive compensation function of the backlash elimination mechanism of this invention demonstrates its key value: the flexible shaft 6 stores sufficient elastic deformation energy during initial assembly. When tooth surface wear causes an increase in tooth flank clearance, the elastic deformation section 6-1 of the flexible shaft 6 automatically releases a portion of the elastic deformation, generating a corresponding torsional angular displacement. This displacement drives the backlash elimination gears in the backlash elimination gear set 5 to rotate further in the backlash elimination direction via the second backlash elimination gear 5-2, thus eliminating the tooth flank clearance caused by wear. Since the empty backlash elimination gears 5-1, 5-3, and 5-4 are clearance-fitted with the shaft, their circumferential positions can be freely adjusted according to the elastic restoring torque of the flexible shaft 6, thereby achieving adaptive compensation for tooth flank clearance at each stage. This compensation process is completely automatic, requiring no manual intervention or machine downtime for adjustment. As long as the cumulative increase in tooth flank clearance caused by tooth surface wear is within the design compensation range of the elastic deformation section 6-1 of the flexible shaft 6, the transmission system can always maintain a zero-backlash transmission state. This is precisely the meaning of the word "adaptive" in the name of this invention—the backlash elimination mechanism can automatically adjust the amount of backlash elimination preload applied according to the change in the wear degree of the intermediate transmission gear pair 4, adapt to the change in the state of the gear pair, and achieve zero backlash transmission throughout the entire life cycle.

[0044] It should be further noted that, in the above embodiments, the preferred embodiment of the connecting locking mechanism is the axially movable spline coupling sleeve 7, but the connecting locking mechanism of the present invention is not limited to this form. Any mechanical connection structure that can achieve the function of "locking the input gear shaft 2 and the backlash-free gear 5-5 after the flexible shaft 6 undergoes torsional elastic deformation to maintain the torsional elastic deformation state of the flexible shaft 6" can be used as an implementation of the connecting locking mechanism of the present invention, such as a nested clutch structure, an end face gear plate connection structure, etc., and the present invention does not limit this. Similarly, the specific number and arrangement of the backlash-free gears in the backlash-free gear set 5 can be adjusted according to the actual number of stages and structural layout of the multi-stage gear transmission mechanism, and the present invention also does not limit this.

[0045] Furthermore, although this embodiment describes a gearbox for a high-speed sawing equipment as a specific application scenario, the flexible shaft adaptive zero backlash elimination technology provided by this invention is not limited to the sawing field. Any multi-stage reduction gearbox with strict requirements for controlling the tooth backlash of the gear transmission system can adopt the technical solution of this invention.

[0046] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A multi-stage reduction flexible shaft adaptive zero-backlash gearbox, comprising a housing and a multi-stage gear transmission mechanism disposed within the housing, the multi-stage gear transmission mechanism comprising an input gear shaft, an output gear shaft, and at least one intermediate transmission gear pair disposed between the input gear shaft and the output gear shaft, characterized in that, The gearbox further includes a backlash elimination mechanism, which comprises a backlash elimination gear set, a flexible shaft, and a locking mechanism. The backlash elimination gear set includes multiple backlash elimination gears, each of which meshes with a gear pair in a stage of the multi-stage gear transmission mechanism to form a backlash elimination transmission branch in parallel with the multi-stage gear transmission mechanism. At least some of the backlash elimination gears are loosely fitted on the shaft. One end of the flexible shaft is connected to one of the backlash elimination gears in the backlash elimination gear set, and the other end is connected to the output gear shaft. The flexible shaft is in a torsional elastic deformation state in the assembled state to apply a continuous circumferential preload to the backlash elimination gear set. The locking mechanism is connected between the input gear shaft and another backlash elimination gear in the backlash elimination gear set, and is used to lock the input gear shaft and the backlash elimination gear set after the flexible shaft undergoes torsional elastic deformation to maintain the torsional elastic deformation state of the flexible shaft.

2. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to claim 1, characterized in that, The module and number of teeth of each backlash-free gear in the backlash-free gear set are consistent with the module and number of teeth of the corresponding meshing gear pair in the multi-stage gear transmission mechanism.

3. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to claim 1, characterized in that, In the backlash-free gear set, at least two of the backlash-free gears that are hollowly fitted onto the shaft are made from a single blank.

4. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to claim 1, characterized in that, The connection locking mechanism is an axially movable spline coupling sleeve. The inner spline and outer spline of the axially movable spline coupling sleeve are respectively engaged with the outer spline of the input gear shaft and the inner spline of the backlash-free gear in the backlash-free gear set. The axially movable spline coupling sleeve realizes the engagement or disengagement between the input gear shaft and the backlash-free gear set by moving axially.

5. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to claim 4, characterized in that, An axially movable spline coupling sleeve is also provided with an axial limiting component, which is used to restrict the axial movement of the axially movable spline coupling sleeve after it moves to the engagement position.

6. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to claim 1, characterized in that, The flexible shaft has an elastic deformation section between its two ends for generating torsional elastic deformation.

7. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to claim 6, characterized in that, The torsional stiffness of the elastic deformation section of the flexible shaft satisfies the following condition: within the range of tooth backlash increments caused by tooth surface wear in each gear pair of the multi-stage gear transmission mechanism, the torsional elastic restoring torque of the flexible shaft can continuously eliminate the tooth backlash.

8. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to claim 1, characterized in that, The input gear shaft and the output gear shaft are respectively supported on the housing by cylindrical bore bearings.

9. The multi-stage reduction flexible shaft adaptive zero-backlash gearbox according to any one of claims 1 to 8, characterized in that, The gear pairs in the multi-stage gear transmission mechanism are cylindrical gear pairs, and each backlash-free gear in the backlash-free gear set is a cylindrical gear that meshes with the corresponding cylindrical gear pair.

10. A backlash elimination assembly method for a multi-stage reduction flexible shaft adaptive zero-backlash gearbox as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Install the input gear shaft, output gear shaft, and intermediate transmission gear pair of the multi-stage gear transmission mechanism into the housing, and mesh and assemble each backlash-free gear in the backlash-free gear set with each stage of the gear pair in the multi-stage gear transmission mechanism, wherein the empty backlash-free gear is loosely fitted on the corresponding shaft, and at the same time, connect one end of the flexible shaft to one of the backlash-free gears in the backlash-free gear set and the other end to the output gear shaft; S2: Apply a reverse preload force relative to the driving direction of the multi-stage gear transmission mechanism to the backlash-free gear set, so that the tooth surface of each backlash-free gear is in close contact with the non-working tooth surface of the corresponding gear in the intermediate transmission gear pair, thereby eliminating the tooth backlash of each stage of the gear pair and causing the flexible shaft to undergo torsional elastic deformation; S3: While the flexible shaft remains in a state of torsional elastic deformation, the input gear shaft is locked to the backlash-free gear set by the coupling locking mechanism, so that the torsional elastic restoring torque of the flexible shaft continues to act on the backlash-free gear set; S4: Release the reverse preload applied to the backlash-eliminating gear set to complete the backlash-eliminating assembly of the gearbox.

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