High-rigidity high-precision machine tool spindle box counterweight balancing system

Abstract

The application relates to a high-rigidity and high-precision machine tool spindle box counterweight balancing system, and belongs to the technical field of machine tool manufacturing. The structure of the balancing system comprises a support frame, a balancing unit, a spindle unit and a B-axis unit. The B-axis unit is fixedly arranged at the bottom of the support frame. The spindle unit is arranged at one end of the B-axis unit, and the B-axis unit is used for driving the swing of the spindle box body. One end of the support frame is fixedly provided with a spring seat. The balancing unit comprises a tension spring, a counterweight arm and a spring plate. One end of the spring plate is arranged on the spring seat, and one end of the tension spring is connected with the other end of the spring plate. One end of the counterweight arm is arranged at the other end of the B-axis unit. The other end of the tension spring is connected with the other end of the counterweight arm. The application has the technical effects of effectively offsetting eccentric moment, avoiding shaking and shaking problems, and significantly improving machining positioning precision and motion stability.

Description

Technical Field

[0001] This application relates to the technical field of machine tool equipment manufacturing, and in particular to a high-rigidity, high-precision machine tool spindle box counterweight balancing system. Background Technology

[0002] As the core component that carries the cutting spindle and realizes workpiece cutting, the spindle box's motion stability directly determines the machining accuracy of the parts. To meet the needs of machining complex curved surfaces and multiple angles, the spindle box usually needs to be driven by the B-axis unit to achieve oscillation. However, the spindle box itself carries the cutting spindle, tool, and fixture, resulting in a large overall weight. During oscillation, it is prone to generating eccentric torque due to the shift of the center of gravity, leading to oscillation instability and decreased positioning accuracy. Therefore, a special counterweight balancing system is required to counteract the eccentric torque and ensure machining stability. Existing high-rigidity, high-precision machine tool spindle box counterweight balancing systems mostly adopt direct suspension of counterweight blocks or lever-type counterweight structures, achieving balance through the gravity of the counterweight blocks and the eccentric torque of the spindle box. However, such structures have obvious shortcomings, such as large counterweight blocks, occupying a lot of space, and poor flexibility in adjusting the balancing torque.

[0003] Patent (CN 116871925 A) discloses a CNC turntable with gravity balancing function, including a support, a tray mounted on the support, and a motor, the motor driving the tray to rotate on the support; it also includes a rotating shaft, a left balance wheel, a right balance wheel, and a drive assembly; one end of the rotating shaft is fixed relative to the tray, and the other end of the rotating shaft is fixedly connected to the drive assembly; the number of left and right balance wheels is equal, and they are all rotatably connected to the rotating shaft; the drive assembly drives the left and right balance wheels to rotate synchronously in opposite directions, and when the CNC turntable is in operation, it interacts with the left and right balance wheels. The aforementioned patent, through its limit-locking mechanism, enables the left and right balance wheels to rotate synchronously in opposite directions via a drive component, forming a limit-locking mechanism to achieve gravity balance during pallet rotation, thereby improving the stability and positioning accuracy of the pallet during rotation. However, it is limited to achieving gravity balance in a single dimension by relying on the limit-locking mechanism of the balance wheels. For heavy-load, complex oscillating conditions such as machine tool spindle units that carry heavy tools and fixtures and require multi-angle oscillation, it cannot flexibly adjust the magnitude of the balancing torque according to load changes, nor can it accurately cancel the eccentric torque during the oscillation of the spindle unit, making it difficult to guarantee the stability and machining accuracy of the spindle oscillation under heavy-load conditions.

[0004] Regarding the aforementioned technologies, the inventors believe that the spindle box is prone to shaking and wobbling due to center of gravity shift during B-axis drive swing, resulting in insufficient machining positioning accuracy and motion stability. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a high-rigidity, high-precision machine tool spindle box counterweight balancing system.

[0006] This application provides a high-rigidity, high-precision machine tool spindle box counterweight balancing system, which adopts the following technical solution:

[0007] A high-rigidity, high-precision machine tool spindle box counterweight balancing system includes a support frame, a balancing unit, a spindle unit, and a B-axis unit. The B-axis unit is fixedly mounted at the bottom of the support frame. The spindle unit is located at one end of the B-axis unit and is used to drive the spindle box to swing. A spring seat is fixedly mounted at one end of the support frame. The balancing unit includes a tension spring, a counterweight arm, and a spring plate. One end of the spring plate is mounted on the spring seat, and one end of the tension spring is connected to the other end of the spring plate. One end of the counterweight arm is located at the other end of the B-axis unit, and the other end of the tension spring is connected to the other end of the counterweight arm.

[0008] By adopting the above technical solution, this system, through the linkage structure of the tension spring, counterweight arm, and spring plate, can accurately counteract the eccentric torque generated by the spindle unit during the B-axis unit's swing drive. This avoids the spindle unit from wobbling and shaking due to center of gravity shift, significantly improving the positioning accuracy and motion stability of the spindle unit during machining, and ensuring dimensional consistency of machined parts. The spindle box's swing drive needs to overcome its own weight-based load, which can easily lead to excessive load on the drive motor and high energy consumption. This balancing system, through the balancing effect of the tension spring and the counterweight arm's torque, can significantly counteract the gravitational load of the spindle unit. This design reduces power loss in the B-axis unit's drive mechanism, lowers motor operating load, and extends the service life of drive components. The lightweight combination structure of the spring seat, spring plate, and tension spring is directly integrated into the support frame and the end of the B-axis unit, eliminating the need for significant modifications to the original machine tool layout. It is compatible with different specifications of machine tool spindle box structures, offering convenient installation and a small footprint. By adjusting the installation position of the tension spring, the magnitude of the balancing torque can be flexibly changed to meet the center of gravity balance requirements of the spindle unit when carrying different tools and fixtures, adapting to diverse machining scenarios and enhancing the system's versatility and flexibility.

[0009] Preferably, one end of the counterweight arm is provided with a tension mounting position for mounting the tension spring, the tension mounting position including a main pin and a mounting hole; the mounting hole is provided at one end of the counterweight arm, and one end of the main pin is fixedly disposed in the mounting hole.

[0010] By adopting the above technical solution, the tension mounting position adopts a combination structure of main pin and mounting hole. The main pin is fixed in the mounting hole and can serve as a stable connection fulcrum for the tension spring, avoiding slippage and displacement of the spring during the swing of the counterweight arm. This ensures the continuity and stability of torque transmission in the balancing unit, thereby maintaining the balance accuracy of the spindle box swing. The main pin setting can evenly distribute the tension of the tension spring to the end of the counterweight arm, avoiding local stress concentration caused by direct contact between the spring and the edge of the mounting hole, reducing the risk of deformation and cracking of the counterweight arm due to long-term stress, and improving the structural reliability of the balancing system.

[0011] Preferably, a roller and a nut are sleeved on the main pin shaft. The roller is fixedly mounted on the main pin shaft and is used to roll against the counterweight arm. The nut is connected to the main pin shaft by a thread and is used to axially fix the main pin shaft.

[0012] By adopting the above technical solution, the rollers added to the main pin shaft roll against the counterweight arm, replacing the traditional rigid sliding contact method. This significantly reduces the frictional resistance between the counterweight arm and the main pin shaft during the swing process. On the one hand, it reduces the wear rate between components, and on the other hand, it reduces frictional loss and improves the efficiency of torque transmission in the balancing system. The nut threaded to the main pin shaft plays an axial locking and fixing role, which can effectively limit the axial movement of the main pin shaft in the mounting hole, prevent the main pin shaft from shifting or loosening due to force, and ensure that the tension of the tension spring always acts on the preset lever arm path, maintaining the stability of the torque of the balancing system, thereby ensuring the balance accuracy and machining positioning accuracy when the spindle box swings.

[0013] Preferably, a first washer is provided between the roller and the nut.

[0014] By adopting the above technical solution, the first washer can evenly distribute the axial pressure generated when the nut is tightened to the end face of the roller, avoiding the nut from directly squeezing the roller and causing local stress concentration, preventing the roller from deforming, indenting or cracking. The filling effect of the washer can eliminate the assembly gap between the roller and the nut, avoiding the problem of component movement and abnormal noise caused by the gap during the swing of the spindle box, enhancing the connection rigidity between the main pin, the roller and the nut, ensuring the stable transmission of the tension spring force, and maintaining the accuracy of the torque of the balance system.

[0015] Preferably, the bottom of the spring seat is provided with a lower pin, and the spring seat is connected to one end of the spring plate through the lower pin, which is used to support the spring plate.

[0016] By adopting the above technical solution, the lower pin shaft serves as the connection fulcrum between the spring seat and the spring plate, providing stable rotational support for the spring plate. This allows the spring plate to adjust its angle synchronously with the swing of the spindle box and the movement of the counterweight arm, ensuring that the direction of the tension spring's force always matches the direction of the counterweight arm's torque. This guarantees the continuity and accuracy of torque transmission in the balancing system, avoiding balance failure caused by jamming in the connection structure. The lower pin shaft concentrates the force on the spring plate to the bottom of the spring seat, replacing the surface contact or rigid fixed connection between the spring plate and the spring seat. This allows the tension spring's force to be evenly distributed on the load-bearing structure of the spring seat, preventing localized stress concentration at the connection between the spring seat and the spring plate, reducing the risk of cracking and deformation, and improving the structural strength and load-bearing stability of the entire balancing system.

[0017] Preferably, the lower pin is provided with a cotter pin, the cotter pin is used to axially fix the lower pin, and a flat washer is provided between the cotter pin and the spring seat.

[0018] By adopting the above technical solution, the cotter pin is directly embedded in the pin hole of the lower pin shaft, which can fundamentally restrict the axial movement of the lower pin shaft and prevent the lower pin shaft from loosening due to vibration during the swing of the spindle box. In conjunction with the flat washer set between the cotter pin and the spring seat, the assembly gap can be further filled, the contact friction can be increased, and the cotter pin can be prevented from loosening or falling off due to long-term alternating vibration. This ensures that the lower pin shaft supports and positions the spring plate stably and guarantees the accuracy of torque transmission of the balance system.

[0019] Preferably, the upper part of the spring seat is provided with two sets of elongated holes, and the spring seat is bolted to the support frame through the two sets of elongated holes. The spring seat slides longitudinally along the support frame through the elongated holes.

[0020] By adopting the above technical solution, the spring seat is bolted to the support frame through two sets of elongated holes. By loosening the bolts, the spring seat can slide longitudinally along the support frame to adjust its installation position, thereby changing the connection fulcrum between the tension spring and the spring seat, the initial tension length of the tension spring, and the direction of the tension force. Through this position adjustment, the torque of the balance system can be flexibly changed, accurately matching the center of gravity offset requirements when the spindle unit is equipped with tools and fixtures of different weights. This ensures that the spindle box can maintain torque balance under all working conditions and avoids fluctuations in machining accuracy caused by load changes.

[0021] Preferably, the B-axis unit includes a housing, which is fixedly disposed at the bottom of the support frame; a torque motor is rotatably disposed inside the housing, and the torque motor is used to drive the spindle unit to swing.

[0022] By adopting the above technical solution, the torque motor is directly built into the B-axis unit housing, which can directly drive the spindle unit to swing. The torque motor has the characteristics of high torque, low speed and fast response, and can accurately execute the angle positioning command of the spindle unit, realize rapid start and stop and micro-angle adjustment, and greatly improve the machining accuracy and dynamic response performance of the machine tool.

[0023] Preferably, the spindle unit includes a spindle box and a cutting spindle; one end of the spindle box is disposed at one end of the torque motor, and the cutting spindle is disposed at the other end of the spindle box.

[0024] Preferably, a pressure cap is provided at the other end of the torque motor, and the counterweight arm is fixedly connected to the other end of the torque motor of the B-axis unit through the pressure cap.

[0025] By adopting the above technical solution, the pressure cap acts as a connection medium between the torque motor and the counterweight arm, stably locking the counterweight arm to the end of the torque motor, ensuring that the counterweight arm and the torque motor rotate synchronously, eliminating the assembly gap between the counterweight arm and the motor shaft, avoiding lag or swaying of the counterweight arm during the swing of the spindle box, ensuring that the torque transmission of the balancing system is precisely matched with the swing action of the spindle unit, and maintaining the balance and stability of the spindle box.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. The tension mounting position adopts a combination structure of main pin and mounting hole. The main pin is fixed in the mounting hole and can serve as a stable connection fulcrum for the tension spring, avoiding slippage and displacement of the spring during the swing of the counterweight arm. This ensures the continuity and stability of torque transmission in the balancing unit, thereby maintaining the balance accuracy of the spindle box swing. The main pin setting can evenly distribute the tension of the tension spring to the end of the counterweight arm, avoiding local stress concentration caused by direct contact between the spring and the edge of the mounting hole. This reduces the risk of deformation and cracking of the counterweight arm due to long-term stress and improves the structural reliability of the balancing system.

[0028] 2. The lower pin serves as the fulcrum connecting the spring seat and the spring plate, providing stable rotational support for the spring plate. This allows the spring plate to adjust its angle synchronously with the swing of the spindle box and the movement of the counterweight arm, ensuring that the direction of the tension spring's force always matches the direction of the counterweight arm's torque. This guarantees the continuity and accuracy of torque transmission in the balancing system, avoiding balance failure caused by jamming in the connection structure. The lower pin concentrates the force on the spring plate to the bottom of the spring seat, replacing the surface contact or rigid fixed connection between the spring plate and the spring seat. This evenly distributes the tension spring's force onto the load-bearing structure of the spring seat, preventing localized stress concentration at the connection between the spring seat and the spring plate, reducing the risk of cracking and deformation, and improving the structural strength and load-bearing stability of the entire balancing system. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure in the embodiment.

[0030] Figure 2 yes Figure 1 A magnified view of part A in the middle.

[0031] Explanation of reference numerals in the attached drawings: 1. Support frame; 11. Spring seat; 111. Lower pin; 112. Cotter pin; 113. Flat washer; 114. Oblong hole; 2. Balancing unit; 21. Tension spring; 22. Counterweight arm; 23. Spring plate; 24. Tension mounting position; 241. Main pin; 2411. Roller; 2412. Nut; 2413. First washer; 242. Mounting hole; 3. Spindle unit; 31. Spindle box; 32. Cutting spindle; 4. B-axis unit; 41. Housing; 42. Torque motor; 43. Pressure cap. Detailed Implementation

[0032] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0033] This application discloses a high-rigidity, high-precision machine tool spindle box counterweight balancing system. (Refer to...) Figure 1 and Figure 2 The system includes a support frame 1, a balancing unit 2, a main spindle unit 3, and a B-axis unit 4. The B-axis unit 4 is fixedly mounted at the bottom of the support frame 1. The main spindle unit 3 is located at one end of the B-axis unit 4 and is used to drive the swing of the main spindle housing 31. A spring seat 11 is fixedly mounted at one end of the support frame 1. The balancing unit 2 includes a tension spring 21, a counterweight arm 22, and a spring plate 23. One end of the spring plate 23 is mounted on the spring seat 11, and one end of the tension spring 21 is connected to the other end of the spring plate 23. One end of the counterweight arm 22 is located at the other end of the B-axis unit 4, and the other end of the tension spring 21 is connected to the other end of the counterweight arm 22. The torque motor 42 of the B-axis unit 4 drives the main spindle unit 3. When the spindle unit 3 swings, its own weight and the load of the tool and fixture it carries will generate an eccentric torque that deviates from the center of rotation. The counterweight arm 22, which is connected to the other end of the B-axis unit 4, swings synchronously with the spindle unit 3. The counterweight arm 22 is connected to the spring plate 23 on the spring seat 11 through the tension spring 21. When the spindle unit 3 swings to one side and generates an eccentric torque, the tension spring 21 is pulled or released, generating a reverse tension. This reverse tension acts on the counterweight arm 22 to form a reverse balancing torque. This torque is equal in magnitude and opposite in direction to the eccentric torque of the spindle unit 3. The two cancel each other out, thereby achieving torque balance of the spindle box 31 during the swing process, ensuring that the spindle unit 3 moves smoothly and is positioned accurately.

[0034] One end of the counterweight arm 22 is provided with a tension mounting position 24 for mounting a tension spring 21. The tension mounting position 24 includes a main pin 241 and a mounting hole 242. The mounting hole 242 is located at one end of the counterweight arm 22, and one end of the main pin 241 is fixedly installed in the mounting hole 242. A roller 2411 and a nut 2412 are sleeved on the main pin 241. The roller 2411 is fixedly installed on the main pin 241 and is used to roll against the counterweight arm 22. The nut 2412 is connected to the main pin 241 by a thread and is used to axially fix the main pin 241. A first washer 2413 is provided between the roller 2411 and the nut 2412. The main pin 241 is fixed in the mounting hole 242 at the end of the counterweight arm 22 as a connection for the tension spring 21. The fulcrum provides a stable mounting base for the spring. The roller 2411 forms a rolling contact with the counterweight arm 22, converting the sliding friction between the counterweight arm 22 and the main pin shaft 241 under the tension of the tension spring 21 into rolling friction, reducing motion resistance and component wear. Tightening the nut 2412 and cooperating with the first washer 2413 between the roller 2411 and the nut 2412 completes the axial locking and fixation of the main pin shaft 241. The first washer 2413 eliminates the assembly gap and prevents the main pin shaft 241 from moving axially. When the counterweight arm 22 swings with the B-axis unit 4, the tension of the tension spring 21 is transmitted to the counterweight arm 22 through the main pin shaft 241. The rolling structure of the roller 2411 ensures that the tension transmission process is unimpeded, realizing the coordinated movement of the counterweight arm 22 and the tension spring 21, and providing a stable reverse torque for the balance system.

[0035] A lower pin 111 is provided at the bottom of the spring seat 11. The spring seat 11 is connected to one end of the spring plate 23 via the lower pin 111, which supports the spring plate 23. A cotter pin 112 is provided on the lower pin 111 to axially fix the lower pin 111. A flat washer 113 is provided between the cotter pin 112 and the spring seat 11. Two sets of elongated holes 114 are provided at the upper part of the spring seat 11. The spring seat 11 is bolted to the support frame 1 through the two sets of elongated holes 114, and the spring seat 11 slides longitudinally along the support frame 1 through the elongated holes 114. The bottom of the spring seat 11 is hinged to one end of the spring plate 23 via the lower pin 111, providing the spring plate 23 with the freedom to rotate around the lower pin 111, ensuring that the spring plate 23 swings with the counterweight arm 22. The angle is adjusted step by step to ensure that the tension direction of the tension spring 21 is adapted to the torque balance requirement; the end of the lower pin 111 is axially fixed by the cotter pin 112, and the flat washer 113 between the cotter pin 112 and the spring seat 11 disperses the locking pressure of the cotter pin 112, eliminates the assembly gap, and prevents the lower pin 111 from moving due to vibration. The upper part of the spring seat 11 is bolted to the support frame 1 through two sets of elongated holes 114. When the spindle unit 3 is equipped with different tools and fixtures, causing the center of gravity to change, the fixing bolts are loosened to allow the spring seat 11 to slide longitudinally along the support frame 1, changing the connection fulcrum position between the spring plate 23 and the tension spring 21, thereby adjusting the initial tension and torque of the tension spring 21. After adjustment, the bolts at the elongated holes 114 are tightened to fix the position of the spring seat 11.

[0036] B-axis unit 4 includes a housing 41, which is fixedly mounted on the bottom of support frame 1. A torque motor 42 is rotatably mounted inside the housing 41, driving the spindle unit 3 to swing. The spindle unit 3 includes a spindle housing 31 and a cutting spindle 32. One end of the spindle housing 31 is located at one end of the torque motor 42, and the cutting spindle 32 is located at the other end of the spindle housing 31. A pressure cap 43 is provided at the other end of the torque motor 42, and a counterweight arm 22 is fixedly connected to the other end of the torque motor 42 in B-axis unit 4 via the pressure cap 43. The housing 41 is fixed to the bottom of the support frame 1. The torque motor 42 directly outputs driving force to drive the spindle box 31 and the cutting spindle 32 to swing, so as to achieve precise angle positioning and rapid response of the spindle unit 3. The other end of the torque motor 42 is connected to the counterweight arm 22 through the pressure cover 43. When the torque motor 42 drives the spindle unit 3 to swing, the counterweight arm 22 rotates synchronously with the motor in the same direction, forming a symmetrical torque structure with the spindle unit 3. During the rotation of the counterweight arm 22, the tension spring 21 connected to it generates a reverse tension force, which acts on the counterweight arm 22 to form a balancing torque.

[0037] The working principle of the counterweight balancing system for a machine tool spindle box 31 in this application is as follows: The housing 41 of the B-axis unit is fixed to the bottom of the support frame 1. The torque motor 42 directly outputs driving force to drive the spindle box 31 and the cutting spindle 32 to swing, thereby achieving precise angular positioning and rapid response of the spindle unit 3. The other end of the torque motor 42 is connected to the counterweight arm 22 through a pressure cap 43. When the torque motor 42 drives the spindle unit 3 to swing, the counterweight arm 22 rotates synchronously and in the same direction with the torque motor 42, forming a symmetrical torque structure with the spindle unit 3. The mounting hole 242 at the end of the counterweight arm 22 houses the main pin 241, and the roller 2411 mounted on the main pin 241 rolls with the counterweight arm 22. The tension spring 21 is mounted on the main pin 241. Tightening the nut 2412 and engaging the first washer 2413 locks the main pin 241 axially, eliminating assembly gaps. When the counterweight arm 22 rotates with the torque motor 42, the tension of the tension spring 21 is transmitted to the counterweight arm 22 through the main pin 241. The roller 2411 converts sliding friction into rolling friction, ensuring smooth force transmission. The bottom of the spring seat 11 is hinged to one end of the spring plate 23 via the lower pin 111, providing rotational freedom for the spring plate 23 and ensuring that the spring plate 23 can adjust its angle synchronously with the swing of the counterweight arm 22. The tension direction of the tension spring 21 always adapts to the torque balance requirement; the cotter pin 112 at the end of the lower pin 111, in conjunction with the flat washer 113, achieves axial anti-loosening fixation of the lower pin 111, disperses the locking pressure and eliminates gaps, preventing the lower pin 111 from moving due to vibration. When the spindle unit 3 is equipped with different tools or fixtures, causing a change in the center of gravity, the bolt at the elongated hole 114 on the upper part of the spring seat 11 is loosened, and the spring seat 11 is slid longitudinally along the support frame 1, changing the connection fulcrum position between the spring plate 23 and the tension spring 21, thereby adjusting the initial tension and torque of the tension spring 21 to adapt to the balance of different loads. After adjustment, tighten the bolts to secure the spring seat 11. Due to its own weight and load, the spindle unit 3 will generate an eccentric torque that deviates from the rotation center, which is prone to shaking and vibration. When the spindle unit 3 swings to one side, the counterweight arm 22, which rotates synchronously with it, will stretch or release the tension spring 21, causing the tension spring 21 to generate a reverse tension force. This tension force acts on the counterweight arm 22 to form a reverse balancing torque. This torque is equal in magnitude and opposite in direction to the eccentric torque of the spindle unit 3. The two cancel each other out, and finally achieve torque balance of the spindle box 31 during the swing process, ensuring that the spindle unit 3 moves smoothly and is positioned accurately.

[0038] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-rigidity, high-precision machine tool spindle box counterweight balancing system, characterized in that: The system includes a support frame (1), a balancing unit (2), a main spindle unit (3), and a B-axis unit (4). The B-axis unit (4) is fixedly installed at the bottom of the support frame (1). The main spindle unit (3) is installed at one end of the B-axis unit (4), and the B-axis unit (4) is used to drive the swing of the main spindle box (31). A spring seat (11) is fixedly installed at one end of the support frame (1). The balancing unit (2) includes a tension spring (21), a counterweight arm (22), and a spring plate (23). One end of the spring plate (23) is installed on the spring seat (11), and one end of the tension spring (21) is connected to the other end of the spring plate (23). One end of the counterweight arm (22) is installed at the other end of the B-axis unit (4), and the other end of the tension spring (21) is connected to the other end of the counterweight arm (22). The upper part of the spring seat (11) is provided with two sets of elongated holes (114). The spring seat (11) is bolted to the support frame (1) through the two sets of elongated holes (114). The spring seat (11) slides longitudinally along the support frame (1) through the elongated holes (114). By changing the connection fulcrum position between the spring plate (23) and the tension spring (21), the initial tension and torque of the tension spring (21) can be adjusted to meet the balance requirements of different loads. The bottom of the spring seat (11) is provided with a lower pin (111), and the spring seat (11) is connected to one end of the spring plate (23) through the lower pin (111). The lower pin (111) is used to support the spring plate (23). One end of the counterweight arm (22) is provided with a tension mounting position (24) for mounting the tension spring (21). The tension mounting position (24) includes a main pin (241) and a mounting hole (242). The mounting hole (242) is provided at one end of the counterweight arm (22), and one end of the main pin (241) is fixedly disposed in the mounting hole (242). A roller (2411) and a nut (2412) are fitted on the main pin (241). The roller (2411) is fixedly mounted on the main pin (241) and is used to roll against the counterweight arm (22).

2. The high-rigidity, high-precision machine tool spindle box counterweight balancing system according to claim 1, characterized in that: The nut (2412) is connected to the main pin (241) by a thread, and the nut (2412) is used to axially fix the main pin (241).

3. The high-rigidity, high-precision machine tool spindle box counterweight balancing system according to claim 2, characterized in that: A first washer (2413) is provided between the roller (2411) and the nut (2412).

4. The high-rigidity, high-precision machine tool spindle box counterweight balancing system according to claim 1, characterized in that: The lower pin (111) is provided with a cotter pin (112), which is used to axially fix the lower pin (111), and a flat washer (113) is provided between the cotter pin (112) and the spring seat (11).

5. The high-rigidity, high-precision machine tool spindle box counterweight balancing system according to claim 1, characterized in that: The B-axis unit (4) includes a housing (41), which is fixedly disposed at the bottom of the support frame (1); a torque motor (42) is rotatably disposed inside the housing (41), which is used to drive the spindle unit (3) to swing.

6. The high-rigidity, high-precision machine tool spindle box counterweight balancing system according to claim 5, characterized in that: The spindle unit (3) includes a spindle box (31) and a cutting spindle (32); one end of the spindle box (31) is located at one end of the torque motor (42), and the cutting spindle (32) is located at the other end of the spindle box (31).

7. A high-rigidity, high-precision machine tool spindle box counterweight balancing system according to claim 5, characterized in that: The other end of the torque motor (42) is provided with a pressure cap (43), and the counterweight arm (22) is fixedly connected to the other end of the torque motor (42) of the B-axis unit (4) through the pressure cap (43).

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