Torque wrench calibration loading lever device

Abstract

The utility model provides a kind of torque wrench calibration loading lever device, belong to torque wrench calibration loading lever technical field, this torque wrench calibration loading lever device includes lever arm body, loading arm, support seat and force joint;The lever arm body is in slender strip structure, the loading arm is hinged connection with one end of the lever arm body by pivot axle, adjustable included angle is formed between the loading arm and the lever arm body, the support seat is fixedly arranged in the middle position of the lever arm body, the bottom of the support seat has plane support surface for carrying the weight of the lever arm body, the force joint is arranged in the other end of the lever arm body;It can solve the problem that the existing torque wrench calibration device cannot produce accurate torque output at force end after applying standard load when calibrating and loading due to unreasonable force arm proportion design between loading mechanism and supporting mechanism.

Description

Technical Field

[0001] This utility model belongs to the field of torque wrench calibration loading lever technology, specifically, it relates to a torque wrench calibration loading lever device. Background Technology

[0002] A torque wrench is a specialized tool used to precisely control the tightening torque of bolts. It is widely used in critical connection parts in fields such as automotive manufacturing, aerospace, machinery assembly, and petrochemicals. To ensure the accuracy of torque wrench measurements, it needs to be calibrated periodically using a calibration device. The commonly used torque wrench calibration method in existing technology employs a lever loading method. This involves suspending a standard weight at one end of the lever arm, using the lever principle to generate a standard torque at the other end, and then connecting the torque wrench to be calibrated to the output end for reading comparison. Traditional calibration devices typically consist of a simple lever arm and a support base. The lever arm rests directly on the support base, and the distance between the weight hanging position and the torque wrench connection position is fixed. While this structure is simple in principle, it has several problems in practical use. Because the contact between the lever arm and the support base is only a simple line or surface contact, lacking effective lateral positioning constraints, the lever arm is prone to lateral slippage during loading, leading to instability in the fulcrum position and changes in the lever arm length, thus affecting the accuracy of the output torque. Meanwhile, the weight mounting points of traditional devices are usually simple hooks or straight rods, making the weights prone to wobbling or falling off. This is especially inconvenient and poses safety hazards when changing weights of different weights. Furthermore, the lever arms of traditional devices often use round or square tubes, which lack sufficient bending stiffness and are prone to bending deformation under large loads, resulting in an actual lever arm length shorter than the theoretical design value and introducing systematic errors. While some existing technologies use fixed hinge connections to improve lever arm stability, improper hinge position and angle design, or inadequate hinge clearance control, lead to low force transmission efficiency between the loading arm and the lever arm, or the hinge may jam, affecting its service life. These problems severely restrict the accuracy and efficiency of torque wrench calibration, making it difficult to meet the high-precision torque control requirements of modern precision manufacturing. Utility Model Content

[0003] In view of this, the present invention provides a torque wrench calibration loading lever device, which can solve the problems of existing torque wrench calibration devices. Due to the unreasonable design of the lever arm ratio between the loading mechanism and the support mechanism, the existing torque wrench calibration devices cannot generate accurate torque output at the force application end after applying a standard load. Furthermore, the existing devices suffer from improper clearance control or unreasonable angle settings in the hinge structure, resulting in an unstable force transmission path during loading, easy displacement of the relative position between the loading arm and the lever arm, and poor positioning constraint effect of the support seat on the lever arm. These issues lead to decreased calibration accuracy, making it difficult to meet the calibration requirements of high-precision torque wrenches and affecting the reliable application of torque wrenches in the field of precision assembly.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a torque wrench calibration loading lever device for calibrating torque wrenches. It includes a lever arm body, a loading arm, a support base, and a force-applying connector. The lever arm body has a long, thin strip structure. The loading arm is hinged to one end of the lever arm body via a pivot shaft, forming an adjustable angle between the loading arm and the lever arm body. The support base is fixedly located at the middle of the lever arm body, and its bottom has a flat support surface for bearing the weight of the lever arm body. The force-applying connector is located at the other end of the lever arm body, with its axis perpendicular to the axis of the lever arm body. The force-applying connector is used to connect the torque wrench to be calibrated. The distance from the hinge position of the loading arm to the lever arm body to the geometric center of the support base is less than the distance between the force-applying connector and the geometric center of the support base. When the loading arm is subjected to a vertically downward external force, the loading arm transmits torque to the lever arm body through the pivot shaft.

[0006] The technical effects of the torque wrench calibration loading lever device provided by this utility model are as follows: By hingedly connecting the loading arm and the lever arm body and setting it close to the support, the external force applied to the loading arm is transmitted to the lever arm body through the pivot shaft to form a torque. Since the distance between the hinged position of the loading arm and the center of the support is less than the distance between the force application joint and the center of the support, the force is amplified according to the lever principle, thereby generating a larger output torque at the force application joint for calibrating the torque wrench. At the same time, the hinged structure ensures that a stable force transmission path is maintained when the angle between the loading arm and the lever arm body changes, improving the adaptability and accuracy of the calibration device. The entire device has a simple and compact structure and is easy to operate and use.

[0007] Based on the above technical solution, the torque wrench calibration loading lever device of this utility model can be further improved as follows:

[0008] The free end of the loading arm is provided with a mounting part, which has a U-shaped groove structure, and the groove of the mounting part faces the extension direction of the lever arm body.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting a U-shaped groove-shaped mounting part at the free end of the loading arm, with the groove opening facing the extension direction of the lever arm body, the calibration weight or hook can be stably mounted in the mounting part. The U-shaped groove structure can effectively prevent the weight from sliding laterally or falling off during the loading process, ensuring that the loading force always acts vertically downward on the loading arm, avoiding the influence of lateral force on calibration accuracy. At the same time, the groove opening orientation design facilitates the operator to quickly mount and unmount the weight, improving the efficiency and safety of the calibration work.

[0010] Furthermore, the cross-sectional shape of the lever arm body is rectangular or I-shaped, and the length direction of the lever arm body is parallel to the support surface of the support seat.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by designing the cross-section of the lever arm body as rectangular or I-shaped and setting its length direction parallel to the support surface of the support seat, the rectangular or I-shaped cross-section has a large bending section modulus, which can effectively resist the bending deformation generated during loading, ensuring the rigidity and stability of the lever arm body when bearing torque. At the same time, the parallel setting allows the lever arm body to be placed stably on the support seat, avoiding poor contact or stress concentration caused by irregular cross-section or improper installation angle, ensuring a clear and accurate force transmission path, and improving the measurement accuracy and reliability of the entire device.

[0012] Furthermore, the force-applying joint has a cylindrical structure, and the outer surface of the force-applying joint is provided with anti-slip texture, which extends along the axial direction of the force-applying joint.

[0013] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by designing the force-applying connector as a cylindrical structure and setting anti-slip textures extending axially on the outer surface, the cylindrical structure matches the standard interface form of the torque wrench, facilitating connection. The anti-slip textures increase the friction coefficient between the force-applying connector and the output shaft of the torque wrench, effectively preventing measurement errors caused by slippage of the contact surface during torque application. At the same time, the axially extending texture design does not significantly affect the cylindricity of the force-applying connector, ensuring the coaxiality of the connection, so that the torque can be accurately transmitted to the calibrated torque wrench, improving the authenticity and repeatability of the calibration results.

[0014] Furthermore, the support surface of the support seat is provided with a V-shaped groove, the axis of the V-shaped groove is perpendicular to the axis of the lever arm body, and the bottom edge of the lever arm body is embedded in the V-shaped groove.

[0015] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by setting a V-shaped groove on the support surface of the support seat, with the groove axis perpendicular to the lever arm body axis, and embedding the bottom edge of the lever arm body into the V-shaped groove, the two inclined surfaces of the V-shaped groove form a bidirectional constraint on the lever arm body, effectively limiting the lateral displacement of the lever arm body in the direction perpendicular to its axis, so that the lever arm body always remains in the predetermined position during the loading process, avoiding changes in the lever arm length or the shift of the fulcrum position caused by lateral movement. At the same time, the V-shaped structure has a self-centering effect, so even if the lever arm body is slightly disturbed, it can automatically return to the correct position, ensuring the stability and consistency of the calibration process.

[0016] Furthermore, the pivot shaft passes through the connecting end of the loading arm and the hinge hole of the lever arm body. The diameter of the hinge hole is 0.5~1mm larger than the diameter of the pivot shaft, and both ends of the pivot shaft are fixed by cotter pins.

[0017] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by having the pivot shaft pass through the connecting end of the loading arm and the hinge hole of the lever arm body, and making the diameter of the hinge hole 0.5~1mm larger than the diameter of the pivot shaft, and fixing both ends of the pivot shaft with cotter pins, this clearance fit allows the loading arm to rotate flexibly relative to the lever arm body without jamming. This ensures that the loading arm can freely adjust its angle to adapt to different loading states when under force. The cotter pin fixing method is simple, reliable, and easy to disassemble and assemble, facilitating the maintenance and repair of the device. At the same time, the appropriate clearance can also compensate for the poor fit caused by manufacturing errors or wear, extend the service life of the device, and ensure the reliability of the hinge connection during long-term use.

[0018] Furthermore, the length of the loading arm is 1 / 4 to 1 / 3 of the distance between the lever arm body from the hinge position to the force application joint, and the angle between the loading arm and the lever arm body in the natural state is 85 to 95°.

[0019] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by setting the length of the loading arm to 1 / 4 to 1 / 3 of the distance between the lever arm body from the hinge position to the force application joint, and making the angle between the loading arm and the lever arm body in the natural state 85 to 95°, this length ratio makes the device have a reasonable leverage ratio, which can achieve sufficient torque amplification, and will not cause the loading arm stroke to be too small or the structural stability to decrease due to an excessively large leverage ratio. The design of the angle close to 90° makes the direction of the loading force basically consistent with the axis of the loading arm, reducing the loss of force decomposition. At the same time, the loading arm has good load-bearing capacity and deformation control capacity within this angle range, ensuring the force transmission efficiency and measurement accuracy during the calibration process.

[0020] Furthermore, the lever arm body is made of alloy steel or carbon structural steel, the loading arm is made of alloy steel or carbon structural steel, and the support seat is made of cast iron or cast steel.

[0021] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by using alloy steel or carbon structural steel to manufacture the lever arm body and loading arm, and using cast iron or cast steel to manufacture the support seat, alloy steel and carbon structural steel have the characteristics of high strength and high elastic modulus, which can withstand the large stress generated during the calibration process without plastic deformation, thus ensuring the dimensional stability and shape retention of the lever arm body and loading arm under repeated loading. Cast iron or cast steel materials have good shock absorption performance and compressive strength, making them suitable as the base material for the support seat, and can absorb the vibration and impact during the calibration process. At the same time, these materials are well-known materials widely used in industry, easy to process and manufacture, and reasonably priced, thus ensuring the economy and practicality of the device.

[0022] Furthermore, the end of the force-applying connector is provided with an internal threaded hole, the axis of which coincides with the axis of the force-applying connector, and the internal threaded hole is used for threaded connection with the output shaft of the torque wrench.

[0023] The beneficial effects of adopting the above-mentioned improved scheme are as follows: By setting an internal threaded hole at the end of the force-applying connector, and aligning the axis of the internal threaded hole with the axis of the force-applying connector, this structure allows the force-applying connector to be reliably connected to the output shaft of the torque wrench via a threaded connection. The threaded connection has the advantages of being firmly connected and easy to install and disassemble, while also being able to transmit a large torque without loosening. The design of the aligning axes ensures the coaxiality of the force-applying connector and the output shaft of the torque wrench after connection, avoiding additional bending moment or stress concentration caused by eccentric connection, so that the calibration torque can be accurately transmitted to the measuring mechanism of the torque wrench, improving the accuracy of calibration. At the same time, the internal thread structure is easy to adapt to the output shaft of torque wrenches of different specifications, enhancing the versatility of the device.

[0024] Furthermore, the angle between the support surface of the support base and the V-shaped groove is 90°, the height of the support base is 20~50mm, and the bottom of the support base is provided with an anti-slip pad layer.

[0025] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by making the support surface of the support base form a 90° angle with the V-shaped groove, and setting the height of the support base to 20~50mm, while setting an anti-slip pad at the bottom, the 90° angle ensures that the support surface is horizontal, allowing the lever arm body to work in a horizontal state, which meets the ideal working conditions of the lever principle. The height of 20~50mm provides sufficient support rigidity without making the overall height of the device too high and affecting stability. The anti-slip pad increases the friction coefficient between the support base and the worktable surface, effectively preventing the support base from slipping or overturning during the calibration process, ensuring the positional stability of the entire device, and enabling the calibration work to be carried out in a safe and reliable state, improving the safety of operation and the reliability of measurement results.

[0026] Compared with existing technologies, the beneficial effects of the torque wrench calibration loading lever device provided by this utility model are as follows: This utility model establishes a reasonable lever arm ratio by optimizing the distance relationship between the hinge position of the loading arm and the support seat and force application joint. This allows the calibration device to accurately convert the external force on the loading arm into the output torque at the force application joint based on the lever principle, significantly improving the accuracy of torque transmission during calibration. By setting a U-shaped groove-shaped mounting part at the free end of the loading arm, lateral slippage and detachment of the weights are effectively prevented, ensuring that the loading force always acts vertically downwards and eliminating interference from lateral components in the measurement. By using a rectangular or I-shaped cross-section lever arm body, the bending stiffness of the device is greatly improved, elastic deformation during loading is reduced, and the stability of the lever arm length is ensured. By setting a V-shaped groove on the support seat to provide bidirectional constraint on the lever arm body, precise lateral positioning and self-centering functions are achieved, avoiding measurement errors caused by fulcrum position offset. By rationally designing the clearance fit between the hinge hole and the pivot shaft, the flexible rotation of the loading arm is ensured while avoiding loosening of the connection caused by excessive clearance, thus improving the working stability of the device. By optimizing the ratio between the loading arm length and the lever arm length, as well as the included angle between them, an optimal balance between torque amplification and structural stability is achieved. This allows the device to generate a sufficiently large calibration torque under relatively small loading forces, while maintaining good measurement accuracy and repeatability. Overall, this significantly improves the efficiency and reliability of torque wrench calibration, providing a high-performance calibration tool for the precision assembly industry. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of a torque wrench calibration loading lever device;

[0029] Figure 2 This is a structural schematic diagram of the mounting section;

[0030] Figure 3 This is a schematic diagram of the force-applying joint.

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 10. Lever arm body; 20. Loading arm; 30. Support seat; 40. Force application joint. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figure 1-3 The diagram shows a structural schematic of a torque wrench calibration loading lever device provided by this utility model. The device, used for calibrating a torque wrench, includes a lever arm body 10, a loading arm 20, a support seat 30, and a force-applying connector 40. The lever arm body has a long, thin strip structure. The loading arm is hinged to one end of the lever arm body via a pivot shaft, forming an adjustable angle between the loading arm and the lever arm body. The support seat is fixedly located in the middle of the lever arm body, and its bottom has a flat support surface to support the weight of the lever arm body. The force-applying connector is located at the other end of the lever arm body, with its axis perpendicular to the axis of the lever arm body. The force-applying connector is used to connect the torque wrench to be calibrated. The distance between the hinge position of the loading arm and the lever arm body and the geometric center of the support seat is less than the distance between the force-applying connector and the geometric center of the support seat. When the loading arm is subjected to a vertically downward external force, the loading arm transmits torque to the lever arm body via the pivot shaft.

[0035] In the above technical solution, the free end of the loading arm is provided with a mounting part, which has a U-shaped groove structure, and the groove of the mounting part faces the extension direction of the lever arm body.

[0036] Furthermore, in the above technical solution, the cross-sectional shape of the lever arm body is rectangular or I-shaped, and the length direction of the lever arm body is parallel to the support surface of the support seat.

[0037] Furthermore, in the above technical solution, the force-applying joint has a cylindrical structure, and the outer surface of the force-applying joint is provided with anti-slip texture, which extends along the axial direction of the force-applying joint.

[0038] Furthermore, in the above technical solution, a V-shaped groove is provided on the support surface of the support seat, the axis of the V-shaped groove is perpendicular to the axis of the lever arm body, and the bottom edge of the lever arm body is embedded in the V-shaped groove.

[0039] Furthermore, in the above technical solution, the pivot shaft passes through the connecting end of the loading arm and the hinge hole of the lever arm body. The diameter of the hinge hole is 0.5~1mm larger than the diameter of the pivot shaft, and both ends of the pivot shaft are fixed by cotter pins.

[0040] Furthermore, in the above technical solution, the length of the loading arm is 1 / 4 to 1 / 3 of the distance between the lever arm body from the hinge position to the force application joint, and the angle between the loading arm and the lever arm body in the natural state is 85 to 95°.

[0041] Furthermore, in the above technical solution, the lever arm body is made of alloy steel or carbon structural steel, the loading arm is made of alloy steel or carbon structural steel, and the support seat is made of cast iron or cast steel.

[0042] Furthermore, in the above technical solution, the end of the force-applying connector is provided with an internal threaded hole, the axis of which coincides with the axis of the force-applying connector, and the internal threaded hole is used for threaded connection with the output shaft of the torque wrench.

[0043] Furthermore, in the above technical solution, the angle between the support surface of the support base and the V-shaped groove is 90°, the height of the support base is 20~50mm, and the bottom of the support base is provided with an anti-slip pad layer.

[0044] The following is a specific embodiment 1 of this utility model: The torque wrench calibration loading lever device in this embodiment is used to calibrate torque wrenches with a measurement range of 50~500kN. The lever arm body is made of No. 40 carbon structural steel and is machined into a rectangular solid structure with a cross-sectional size of 40mm*60mm. The total length of the lever arm body is 800mm, and the surface is polished to reduce friction and prevent corrosion. The loading arm is also made of No. 40 carbon structural steel and has a rectangular structure with a cross-sectional size of 30mm*50mm. The length of the loading arm is 200mm. A connecting ear plate with a thickness of 15mm is formed at one end of the loading arm through machining. A circular hinge hole with a diameter of 16mm is drilled on the connecting ear plate. The pivot shaft is made of No. 45 high-quality carbon structural steel and has a surface hardness of HRC40~45 after tempering heat treatment. The diameter of the pivot shaft is 15mm and the length is 70mm. A cotter pin hole with a diameter of 2mm and a depth of 10mm is machined at each end of the pivot shaft. The mounting portion at the free end of the loading arm is formed by bending. The U-shaped groove has a width of 35mm, a depth of 25mm, and a rounded bottom with a radius of 5mm. The groove opening faces the force-applying joint along the axial direction of the lever arm body. The support base is cast from HT200 gray cast iron and has a rectangular structure with dimensions of 120mm long, 100mm wide, and 35mm high. The support surface at the top of the support base is a horizontal surface that has been precision ground, with a flatness error of less than 0.02mm. A V-shaped groove is formed along the width direction at the center of the support surface. The groove angle is 90°, the groove depth is 8mm, and the groove width is 48mm. The angle between the two inclined surfaces of the groove and the support surface is 45°. A 3mm thick nitrile rubber anti-slip pad is attached to the bottom of the support base, with a Shore hardness of 60 to 70°. The force-applying joint is made of 40Cr alloy structural steel, and after quenching and tempering, its overall hardness reaches HRC28~32. The joint is cylindrical, with a diameter of 32mm and a total length of 80mm. Straight anti-slip grooves, 1mm deep, 2mm wide, and 5mm spaced, are machined axially on its outer surface. One end of the force-applying joint is fixed to the end of the lever arm body by welding or threaded connection. After connection, the axis of the force-applying joint is perpendicular to the axis of the lever arm body at 90°. The other end of the force-applying joint has a 45mm deep internal thread hole. The internal thread is an M20*2.5 metric coarse thread with a thread accuracy grade of 6H. A hinge hole, 16mm in diameter, is drilled on the lever arm body 150mm from the centerline of the force-applying joint. The axis of the hinge hole is parallel to the width direction of the lever arm body. During assembly, align the connecting lug of the loading arm with the hinge hole of the lever arm body, insert the pivot shaft, insert cotter pins with a diameter of 2mm into the cotter pin holes at both ends of the pivot shaft, and separate the two legs of the cotter pins to achieve the hinge connection.The angle between the loading arm and the lever arm body in the natural unloaded state is 90°. When a loading force is applied, the angle between the loading arm and the lever arm body will change slightly but will still remain within the range of 85~95°. When the device is working, the long rectangular side of the bottom of the lever arm body is embedded into the V-shaped groove of the support seat, and the geometric center line of the lever arm body coincides with the geometric center line of the support seat. At this time, the horizontal distance between the center of the hinge hole of the lever arm body and the geometric center of the support seat is 150mm, and the horizontal distance between the center of the axis of the force application joint and the geometric center of the support seat is 550mm, forming a lever arm length ratio of 1:3.67. When a 20 kg standard weight is suspended from the loading arm, the weight generates a force of 196 N. This force is transmitted through the loading arm to the hinge point, where the torque is 196 N * the effective lever arm length. Since the loading arm is 200 mm long and its angle with the lever arm body is close to 90°, the effective lever arm is approximately 200 mm. Therefore, the torque generated at the hinge point is 39.2 kN. According to the lever balance principle, the reaction torque generated at the force application joint is 39.2 kN * lever arm length ratio 3.67, resulting in an output torque of approximately 143.9 kN at the force application joint. By changing the standard weights of different masses, this device can achieve continuous torque calibration output within the range of 50~500 kN, meeting the calibration requirements of commonly used torque wrenches. The device in this embodiment has a compact structure and few parts, including only four main components: the lever arm body, the loading arm, the support seat, and the force application joint. It is easy to assemble and disassemble, simple to operate, and the calibration accuracy can reach within ±2%. It is suitable for use in places such as machining workshops and tool testing laboratories.

[0045] The following is another specific embodiment 2 of this utility model: Embodiment 2 is based on Embodiment 1, with improvements and optimizations to the structure of the support seat. The support seat is cast from QT450 ductile iron, which has higher strength and toughness and better impact resistance compared to HT200 gray cast iron in Embodiment 1. The V-shaped groove of the support seat, based on the original 90° groove angle, has a 3mm wide planar transition area added to the bottom of the groove. This planar transition area forms line contact with the bottom edge of the lever arm body, further improving the stability of the contact. Simultaneously, a reinforcing rib with a thickness of 8mm is added to each of the two sides of the support seat. The reinforcing rib extends from the bottom of the support seat to the support surface, forming a triangular support structure with the support seat body, significantly improving the overall rigidity of the support seat and reducing the possible minor deformation of the support seat under large loads. The anti-slip pad layer at the bottom of the support seat is replaced with a 5mm thick neoprene rubber material. Neoprene rubber has better oil resistance and weather resistance, making it suitable for long-term use in industrial environments. Furthermore, a raised frame with a height of 2mm was added around the support surface of the support base. This frame is used to prevent the lever arm body from slipping out of the V-shaped groove in extreme cases, improving safety during use. The improvements in this embodiment enable the device to maintain good stability and accuracy when subjected to greater loads, making it suitable for heavy-duty torque wrenches with a wider calibration range. The calibration torque range can be extended to 100~800kN, and the calibration accuracy is maintained within ±1.5%.

[0046] The following is another specific embodiment 3 of this utility model: This embodiment 3 is based on embodiment 1, with optimized design of the loading arm and mounting part. The material of the loading arm is changed to 6061 aluminum alloy, which achieves a strength of over 310 MPa after T6 heat treatment. Aluminum alloy is lighter than steel, reducing the overall weight of the device and making it easier to carry and move. The cross-sectional shape of the loading arm is changed to a hollow rectangular tubular structure with an outer dimension of 40mm*60mm and a wall thickness of 5mm. This hollow structure further reduces weight while ensuring sufficient strength, and the hollow cross-section has a large moment of inertia and good bending resistance. Based on the original design, the U-shaped groove structure of the mounting part has three transverse anti-slip stripes with a depth of 0.5mm and a width of 1mm added to the inner walls of both sides of the groove. The anti-slip stripes are evenly distributed along the depth direction of the groove with a spacing of 6mm. These anti-slip stripes increase the coefficient of friction between the inner wall of the mounting part and the weight hook, further preventing the weight from sliding during loading. Meanwhile, the slot of the mounting section is equipped with an inwardly tapering guide ramp. The ramp makes a 15° angle with the vertical direction and has a length of 10mm. This guide ramp facilitates the operator to quickly and accurately guide the weight hook into the U-shaped slot, improving operational efficiency and safety. The total weight of the device in this embodiment is reduced by approximately 40% compared to Embodiment 1, making it easier to transfer between different work locations. At the same time, the optimized mounting section structure makes loading and unloading weights more convenient, reducing operation time and improving the overall efficiency of calibration work. It is particularly suitable for applications requiring frequent movement and high-frequency calibration operations.

[0047] Specifically, the principle of this invention is as follows: This device achieves precise torque transmission and amplification by establishing a scientific lever mechanics model. Specifically, the loading arm is hinged to the lever arm body via a pivot shaft, forming a rotatable force input end. When a vertically downward external force is applied to the mounting portion at the free end of the loading arm, this force is transmitted through the loading arm to the pivot shaft, generating a torque around the support fulcrum on the lever arm body. According to the lever balance principle, this torque equals the external force multiplied by the distance from the loading arm hinge point to the center of the support. The reaction torque generated at the force application joint equals the output force multiplied by the distance from the force application joint to the center of the support. Since the distance from the loading arm hinge point to the center of the support is less than the distance between the force application joint and the center of the support in the design, according to the torque balance condition, the force generated at the force application joint must be greater than the force applied at the loading arm, achieving a force amplification effect. By precisely controlling the length ratio of the two lever arms, the output torque value at the force application joint can be accurately calculated, thus providing a standard calibration torque for the torque wrench. This device employs a hinged connection instead of a rigid fixation, allowing the loading arm to automatically adjust the angle between itself and the lever arm body according to the load size. This ensures that the loading force is always transmitted in the most favorable direction, avoiding stress concentration and deformation problems that may occur with rigid connections. The V-shaped groove on the support base provides geometric constraints to the lever arm body through its two inclined surfaces. When the lever arm body is subjected to a lateral force, the inclined surfaces of the V-shaped groove generate a center-directing component force, automatically pushing the lever arm body back to the correct position. This self-centering mechanism ensures high stability of the fulcrum position and eliminates the influence of lateral displacement on the lever arm length. The U-shaped mounting section provides spatial constraints to the weights through its three-sided enclosing structure, limiting the weights' degrees of freedom of movement in the horizontal plane. This ensures that the point of application of the loading force is fixed and that the direction of the force is always vertically downward, eliminating measurement errors caused by force decomposition. The lever arm body is made of high-strength steel and designed with a rectangular or I-shaped cross section. Utilizing the high elastic modulus of the material and the large moment of inertia of the cross section, the lever arm deflection is minimal when subjected to bending moment, ensuring the geometric accuracy of the lever arm length during loading. The combined effect of these technical principles enables this device to achieve high-precision and high-stability torque calibration, effectively solving problems such as unstable fulcrum, inaccurate force transmission path, and insufficient structural stiffness in existing technologies.

[0048] In use, first place the support base on a flat and stable workbench, ensuring the anti-slip pad on the bottom of the support base is in full contact with the surface. Then, align the bottom edge of the lever arm body with the V-shaped groove on the support surface of the support base, ensuring the lever arm body rests horizontally and stably on the support base. Next, check the hinge connection between the loading arm and the lever arm body for flexibility, confirming that the cotter pins at both ends of the pivot shaft are securely installed, allowing the loading arm to rotate freely relative to the lever arm body without jamming. Then, take out the torque wrench to be calibrated, align its output shaft with the internal threaded hole at the end of the force application connector, and rotate it clockwise to securely connect the torque wrench output shaft to the force application connector via threads. During connection, ensure that the axis of the torque wrench coincides with the axis of the force application connector to avoid eccentric connection. After connection, select a standard weight of appropriate mass according to the required torque value for calibration, and hook the weight's hook into the U-shaped groove-shaped mounting part at the free end of the loading arm, ensuring the weight is suspended stably and centered in the mounting part. Under the influence of the weight, the loading arm applies a torque to the lever arm body. This torque is transmitted through the lever to the force application joint and acts on the output shaft of the torque wrench. Observe the indicated value or digital display of the torque wrench and record the currently displayed torque value. Then, calculate the theoretical standard torque value based on the mass of the weight, the acceleration due to gravity, and the ratio of the lever arm length to the device. Compare the actual displayed value of the torque wrench with the theoretical standard value to determine whether the measurement error of the torque wrench is within the allowable range. If different torque points need to be calibrated, replace the standard weights of different masses one by one and repeat the above measurement process to obtain the error data of the torque wrench at multiple torque points. After calibration, first remove the weight from the mounting part, then rotate counterclockwise to remove the torque wrench from the force application joint, and finally lift the lever arm body from the V-shaped groove of the support seat to complete the entire calibration operation.

Claims

1. A torque wrench calibration loading lever device for calibrating a torque wrench, comprising a lever arm body, a loading arm, a support base, and a force-applying connector; the lever arm body is an elongated strip structure, the loading arm is hinged to one end of the lever arm body via a pivot shaft, the loading arm and the lever arm body form an adjustable angle, the support base is fixedly disposed at the middle position of the lever arm body, the bottom of the support base has a flat support surface for bearing the weight of the lever arm body, the force-applying connector is disposed at the other end of the lever arm body, the axis of the force-applying connector is perpendicular to the axis of the lever arm body, and the force-applying connector is used to connect the torque wrench to be calibrated, characterized in that... The distance between the hinge position of the loading arm and the lever arm body and the geometric center of the support is less than the distance between the force-applying joint and the geometric center of the support. When the loading arm is subjected to a vertically downward external force, the loading arm transmits torque to the lever arm body through the pivot axis.

2. The torque wrench calibration loading lever device according to claim 1, characterized in that, The free end of the loading arm is provided with a mounting part, which has a U-shaped groove structure, and the groove of the mounting part faces the extension direction of the lever arm body.

3. The torque wrench calibration loading lever device according to claim 2, characterized in that, The cross-sectional shape of the lever arm body is rectangular or I-shaped, and the length direction of the lever arm body is parallel to the support surface of the support seat.

4. The torque wrench calibration loading lever device according to claim 3, characterized in that, The force-applying joint has a cylindrical structure, and the outer surface of the force-applying joint is provided with anti-slip texture, which extends along the axial direction of the force-applying joint.

5. A torque wrench calibration loading lever device according to claim 4, characterized in that, The support surface of the support seat is provided with a V-shaped groove, the axis of the V-shaped groove is perpendicular to the axis of the lever arm body, and the bottom edge of the lever arm body is embedded in the V-shaped groove.

6. A torque wrench calibration loading lever device according to claim 5, characterized in that, The pivot shaft passes through the connecting end of the loading arm and the hinge hole of the lever arm body. The diameter of the hinge hole is 0.5~1mm larger than the diameter of the pivot shaft. The two ends of the pivot shaft are fixed by cotter pins.

7. A torque wrench calibration loading lever device according to claim 6, characterized in that, The length of the loading arm is 1 / 4 to 1 / 3 of the distance between the lever arm body from the hinge position to the force application joint, and the angle between the loading arm and the lever arm body in the natural state is 85 to 95°.

8. A torque wrench calibration loading lever device according to claim 7, characterized in that, The lever arm body is made of alloy steel or carbon structural steel, the loading arm is made of alloy steel or carbon structural steel, and the support seat is made of cast iron or cast steel.

9. A torque wrench calibration loading lever device according to claim 8, characterized in that, The end of the force-applying connector is provided with an internal threaded hole, the axis of which coincides with the axis of the force-applying connector, and the internal threaded hole is used for threaded connection with the output shaft of the torque wrench.

10. A torque wrench calibration loading lever device according to claim 9, characterized in that, The support surface of the support base has an angle of 90° with the V-shaped groove, the height of the support base is 20~50mm, and the bottom of the support base is provided with an anti-slip pad layer.

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