Arm ratio adjustment system and method for lever amplification type torque standard device

Abstract

The invention relates to an arm ratio adjusting system and method for a lever amplification type torque standard device, and belongs to the technical field of torque measurement. The system comprises an electromagnetic force measuring system and an arm ratio fine tuning structure. The arm ratio fine adjustment structure is used for finely adjusting the arm length; the electromagnetic force measuring system is used for measuring unbalanced torque introduced by the arm length difference so as to calculate the arm length difference after fine adjustment of the arm length. The problems of arm length adjustment and arm length measurement of the lever amplification type torque standard device can be effectively solved, and then the standard torque value is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of torque measurement, and relates to an arm ratio adjustment system and method for a lever-amplified torque standard device. Background Art

[0002] The lever-amplified torque standard device adopts the principle of static weight balance loading, such as Figure 1 As shown in the figure, a standard weight is loaded on the flexible suspension at one end of the lever arm. The downward force generated by the weight is obtained according to the mass of the standard weight and the local gravity acceleration. The standard torque value can be obtained by multiplying the force value by the length of the lever arm. The standard torque value is transmitted to the calibrated torque sensor or the calibrated torque measuring instrument through the central output shaft of the standard device, thereby realizing the output of the standard torque value. In actual situations, the lever arm of the lever amplification torque standard device is divided into two directions, left and right, such as Figure 1 shown.

[0003] M + 、M - Indicates the positive and reverse torque values ​​of the lever-amplified torque standard device:

[0004] M + =m1×L1

[0005] M - =m2×L2

[0006] m1 is the mass of the weight loaded on the left pan, the length of the left arm is L1, and the length of the right arm is L2; ​​m2 is the mass of the weight loaded on the left pan. The implementation method of the lever fulcrum in the lever-type torque standard device is a crucial link. Common lever fulcrums are generally of two types: knife bearing type and hanging spring type. The knife bearing type lever fulcrum has a simple structure and is easy to install and adjust, with low processing cost, but it has the problem of poor repositionability, that is, when the lever balance tilts during operation, the lever fulcrum is prone to displacement, resulting in changes in the lever arm length. Therefore, the arm length value should be regularly checked for correction. The detection process requires in-situ measurement to avoid the impact of the difference in arm length values ​​before and after disassembly and assembly. It is not realistic to use traditional geometric measurement methods to measure the arm length of the knife bearing fulcrum type lever. Another structure is to use a hanging spring type flexible suspension structure as the fulcrum of the lever system. The hanging spring structure is such as Figure 2 The schematic diagram of the torque standard device of the spring-type flexible suspension structure lever system is shown in Figure 3 .

[0007] The spring-type flexible suspension structure solves the problem of poor repositioning of the lever fulcrum very well. However, the sensitive part of the spring is inside the spring and cannot be reached by traditional contact measurement methods. That is, the position of the lever fulcrum cannot be measured directly, which leads to the inability to accurately measure the lever arm L1 and L2, and the standard torque value cannot be effectively traced. Summary of the invention

[0008] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose an arm ratio adjustment system and method for a lever-amplified torque standard device, which can effectively solve the problem of arm length adjustment and arm length measurement of the lever-amplified torque standard device, and thus obtain a standard torque value.

[0009] The solution of the present invention is:

[0010] An arm ratio adjustment system for a lever-amplified torque standard device comprises an electromagnetic force measuring system and an arm ratio fine-tuning structure; the arm ratio fine-tuning structure is used to fine-tune the arm length; the electromagnetic force measuring system is used to measure the unbalanced torque introduced by the arm length difference to calculate the arm length difference after the arm length is fine-tuned.

[0011] Preferably, the arm ratio fine-tuning structure includes a left angle wedge, a left fine-tuning screw, a middle angle wedge, a balance beam, a right fine-tuning screw, and a right angle wedge; a groove is processed on the lower surface of the balance beam, and the left angle wedge, the middle angle wedge, and the right angle wedge are all located in the groove; the middle angle wedge is fixed to the base by a hanging spring, and the middle angle wedge is an isosceles trapezoidal structure, and the middle angle wedge is located between the left angle wedge and the right angle wedge, and the left angle wedge and the right angle wedge have the same structure, and are both A right-angle trapezoidal structure, the inclined surfaces of the left angle wedge and the right angle wedge are in contact with the inclined surfaces on both sides of the middle angle wedge, and the left angle wedge and the right angle wedge are symmetrical along the center of the middle angle wedge; the left angle wedge is connected to the balance beam through a left fine-tuning screw, and the right angle wedge is connected to the balance beam through a right fine-tuning screw; the vertical surface of the left angle wedge is parallel and close to the left vertical surface of the groove of the balance beam, and the vertical surface of the right angle wedge is parallel and close to the right vertical surface of the groove of the balance beam.

[0012] Preferably, the inclination angles of the inclined surfaces of the left-angle wedge block, the right-angle wedge block, and the middle-angle wedge block are 80°.

[0013] Preferably, for every 1° rotation of the left fine-tuning screw, the vertical displacement of the left angle wedge relative to the balance beam is 0.00278 mm; for every 1° rotation of the right fine-tuning screw, the vertical displacement of the right angle wedge relative to the balance beam is 0.00278 mm.

[0014] Preferably, the electromagnetic force measurement system includes a torquer, a damper, a displacement sensor, a torque processing unit, a speed signal amplifier, a speed converter, a displacement converter, and an amplifying unit; the torquer is fixed at one end of the balance beam, and the damping coil and the displacement sensor are located at the other end of the balance beam; the displacement sensor is used to sense the angular displacement change of the balance beam, and the output value is output to the amplifying unit after being converted by the displacement converter; the damper provides damping for the system, and the output damping force is converted into a speed signal by the speed converter, which is amplified by the speed signal amplifier and then output to the amplifying unit; the PID processing unit processes the signal amplified by the amplifying unit to obtain a feedback current, which is fed back to the torquer to make the torquer generate a balancing force; the feedback current reflects the magnitude of the unbalanced torque.

[0015] Preferably, the arm length difference can be reversely calculated based on the unbalanced torque.

[0016] A method for adjusting the arm ratio of a lever-amplified torque standard device, comprising:

[0017] 1) According to the actual use conditions, the length of the left arm is defined as L1 and the length of the right arm is defined as L2;

[0018] 2) The left and right weight plates are empty, and the output voltage V1 is calculated based on the feedback current of the electromagnetic force measurement system;

[0019] 3) Load a weight on the left pan with a mass of m1, and load a weight of the same specification on the right pan with a mass of m2. Calculate the output voltage V2 of the electromagnetic force measurement system. During the test, the output voltage and torque of the electromagnetic force measurement system are in a linear relationship, and their ratio is the sensitivity of the electromagnetic force measurement system, recorded as A, and we get:

[0020] m1gL1-m2gL2=(V2-V1)A (1)

[0021] 4) Swap the weights on the left and right pans and measure again. Load the weight of mass m2 on the left pan and the weight of mass m1 on the right pan. Calculate the output voltage V3 based on the feedback current of the electromagnetic force measurement system. The change in the voltage output of the electromagnetic force measurement system is directly caused by the unequal arms, and we get:

[0022] m2gL1-m1gL2=(V3-V1)A (2)

[0023] 5) Remove the weights loaded on the left and right pans, and then load other weights of E1 grade on the left pan, with the mass recorded as m3. Calculate the output voltage V4 based on the feedback current of the electromagnetic force measurement system; compared with the no-load state, the change in the voltage output value of the electromagnetic force measurement system is directly caused by the weight with a mass of m3, and we get:

[0024] m3gL1=(V4-V1)A (3)

[0025] 6) After the balance beam is processed, use a three-coordinate machine to measure its total length, recorded as L, then:

[0026] L1+L2=L (4)

[0027] By combining equations (1) to (4), we can calculate the specific values ​​of the arm lengths on both sides:

[0028]

[0029] According to the difference in specific values ​​of the arm lengths on both sides, adjust the arm ratio fine-tuning structure until the arm lengths are completely equally divided.

[0030] Preferably, the method for adjusting the arm ratio fine-tuning structure is as follows:

[0031] When it is necessary to fine-tune the balance beam to the left, first loosen the right fine-tuning screw, then adjust the left fine-tuning screw, press the left angle wedge to make it move upward along the inclined surface of the middle angle wedge, thereby squeezing the balance beam to force it to deviate to the left. At this time, the left arm becomes longer and the right arm becomes shorter. After adjusting the arm length to the appropriate position, tighten the right fine-tuning screw and lock the right angle wedge to complete the fine-tuning of the balance arm length to the left.

[0032] When it is necessary to fine-tune the balance beam to the right, first loosen the left fine-tuning screw, then adjust the right fine-tuning screw, press the right angle wedge to make it move upward along the inclined surface of the middle angle wedge, thereby squeezing the balance beam and forcing it to deviate to the right. At this time, the right arm becomes longer and the left arm becomes shorter; after adjusting the arm length to the appropriate position, tighten the left fine-tuning screw, lock the left angle wedge, and complete the fine-tuning of the balance arm length to the right.

[0033] The beneficial effects of the present invention compared with the prior art are:

[0034] (1) The present invention uses an angle wedge block on the left and right sides to cooperate with an adjusting screw, and utilizes an inclined surface to convert the vertical displacement of the angle wedge block into the horizontal displacement of the balance beam, and subdivides the displacement to achieve micrometer-level arm length fine-tuning.

[0035] (2) The present invention designs an electromagnetic force measuring system that can convert the unbalanced torque of a lever into a voltage signal, and constructs an automatic measuring system with a negative feedback circuit to realize the measurement of the unbalanced torque of the lever.

[0036] (3) The present invention designs a calculation method, which uses the unbalanced torque generated by the standard weights and the difference in the length of the left and right arms to be equivalent to the voltage signal output by the electromagnetic force measurement system, and eliminates the error introduced by the unequal amount of standard weights by exchanging the weights of the left and right pans, and calculates the left and right arm length ratio. The total length of the lever arm is measured by geometric means, and the specific values ​​of the left and right arm lengths can be obtained. Combined with the arm ratio adjustment structure, the lever arm length can be quantitatively fine-tuned at the micron level. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the working principle diagram of the lever amplification torque standard device;

[0038] Figure 2 This is the structure diagram of the suspension spring;

[0039] Figure 3 It is a torque standard device adopting a spring-type flexible suspension structure;

[0040] Figure 4 It is a schematic diagram of the left and right angle wedges;

[0041] Figure 5 It is a schematic diagram of a medium angle wedge;

[0042] Figure 6 and Figure 7 Fine-tune the structure for arm ratio;

[0043] Figure 8 Schematic diagram of electromagnetic force measurement system for converting unbalanced torque into voltage signal;

[0044] Fig. 9 This is a schematic diagram of the empty left and right weight pans;

[0045] Fig.10 It is a schematic diagram of loading the left and right weight plates;

[0046] Fig.11 This is a schematic diagram of swapping the left and right weights;

[0047] Fig.12 Schematic diagram of loading the left weight pan. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with the accompanying drawings.

[0049] The present invention realizes arm length fine adjustment by designing an arm ratio fine adjustment structure; designs an electromagnetic force measuring system with a negative feedback circuit to realize the measurement of unbalanced torque introduced by the arm length difference; and designs an arm length measurement method to realize accurate arm length measurement.

[0050] (1) Arm ratio fine-tuning structure

[0051] Design arm ratio fine-tuning structure such as Figure 6-7 The suspension spring is the fulcrum of the balance beam, one end of the middle angle wedge 3 is connected to the base 9 through the suspension spring 8, and the other end is connected to the balance beam 4 through the connecting screw 5, so as to achieve the purpose of fixing the balance beam 4 on the base 9 through the suspension spring 8.

[0052] Specifically, a groove is processed on the lower surface of the balance beam 4, and the left angle wedge 1, the middle angle wedge 3, and the right angle wedge 7 are all located in the groove; the middle angle wedge 3 is fixed to the base 9 by a hanging spring 8, and the middle angle wedge 3 is an isosceles trapezoidal structure, and the middle angle wedge 3 is located between the left angle wedge 1 and the right angle wedge 7. The left angle wedge 1 and the right angle wedge 7 have the same structure, both of which are right-angled trapezoidal structures. The inclined surfaces of the left angle wedge and the right angle wedge are in contact with the inclined surfaces on both sides of the middle angle wedge, and the left angle wedge 1 and the right angle wedge 7 are symmetrical along the center of the middle angle wedge 3; the left angle wedge 1 is connected to the balance beam 4 by a left fine-tuning screw 2, and the right angle wedge 7 is connected to the balance beam 4 by a right fine-tuning screw 6; the vertical surface of the left angle wedge is parallel and close to the left vertical surface of the balance beam groove, and the vertical surface of the right angle wedge is parallel and close to the right vertical surface of the balance beam groove. Figure 7 In the middle, 11 is a torque output shaft.

[0053] The vertical freedom of the balance beam is constrained, but there is a gap in the threaded hole of the connecting screw. The angle wedge can be fine-tuned to make the beam translate horizontally, so that the beam is displaced horizontally relative to the suspension spring, thereby achieving the purpose of fine-tuning the arm length.

[0054] When the balance beam needs to be fine-tuned to the left, first loosen the right fine-tuning screw 6, then adjust the left fine-tuning screw 2, press the left angle wedge 1 to move it upward along the inclined surface of the middle angle wedge 3, thereby squeezing the balance beam and forcing it to deviate to the left. At this time, the left arm becomes longer and the right arm becomes shorter. After adjusting the arm length to the appropriate position, tighten the right fine-tuning screw 6 and lock the right angle wedge 7 to complete the fine-tuning of the balance arm length to the left.

[0055] When the balance beam needs to be fine-tuned to the right, first loosen the left fine-tuning screw 2, then adjust the right fine-tuning screw 6, press the right angle wedge 7 to make it move upward along the inclined surface of the middle angle wedge 3, thereby squeezing the balance beam and forcing it to deviate to the right. At this time, the right arm becomes longer and the left arm becomes shorter. After adjusting the arm length to the appropriate position, tighten the left fine-tuning screw 2 and lock the left angle wedge 1 to complete the fine-tuning of the balance arm length to the right.

[0056] The inclination angles of the left angle wedge, right angle wedge and middle angle wedge are designed to be 80°, and the left fine-tuning screw and right fine-tuning screw are designed to be M6×1 threads. When the screw rotates 1°, the vertical displacement of the angle wedge relative to the balance beam is 0.00278mm, which is converted to a horizontal displacement of the balance beam relative to the lever origin (suspension spring) of 0.0005mm, thereby achieving micron-level arm length fine-tuning.

[0057] The left and right angle wedge structure diagram is shown in Figure 4 , the structure diagram of the medium angle wedge is shown in Figure 5 .

[0058] (2) Electromagnetic force measurement system - quantification of unbalanced torque

[0059] On the basis of the arm length being fine-tunable, it is also necessary to quantitatively measure the length of the arm length fine-tuning, so that the fine-tuning mechanism has practical value. The change in arm length is reflected in the lever system in the form of torque, so the present invention relates to an electromagnetic force measurement system that converts the unbalanced torque of the lever into a voltage signal, and an automatic measurement system with a negative feedback circuit is added to realize the automatic measurement of the unbalanced torque of the lever. Figure 8 This is a schematic diagram of an automatic measurement system. The torquer is fixed at one end of the balance beam, and the damping coil and displacement sensor are located at the other end of the balance beam. The principle is that when the lever is subjected to an unbalanced torque, it tilts to one side. The displacement sensor is used to sense the change in the angular displacement of the balance beam. The output value is converted by the displacement converter and output to the amplifier unit. The damper provides damping for the system, and the output damping force is converted into a speed signal by the speed converter, which is amplified by the speed signal amplifier and output to the amplifier unit. The PID processing unit processes the signal amplified by the amplifier unit to obtain a feedback current, which is fed back to the torquer to make the torquer produce a balancing force. The feedback current reflects the size of the unbalanced torque. Through this system, the unbalanced torque in the lever system can be converted into a voltage signal.

[0060] (3) Method for accurately dividing arm length into equal parts

[0061] On the basis that the arm length can be fine-tuned and the unbalanced torque can be quantified, a set of calculation methods is needed to establish a relationship between the quantified value of the torque and the arm length, so as to ultimately achieve accurate equal division of the arm length. The method is as follows:

[0062] 1) According to the actual use conditions, the length of the left arm is defined as L1 and the length of the right arm is defined as L2;

[0063] 2) The left and right weight plates are empty, and the output voltage V1 is calculated based on the feedback current of the electromagnetic force measurement system, such as Fig. 9 As shown;

[0064] 3) Load a weight on the left pan with a mass of m1, and load a weight of the same specification on the right pan. Considering that the masses of the two weights are not exactly the same, the mass is recorded as m2. The output voltage is calculated as V2 based on the feedback current of the electromagnetic force measurement system. The change in the voltage output of the electromagnetic force measurement system is directly caused by the unequal arms. Fig.10 As shown, during the test, the voltage output and torque of the electromagnetic force measurement system are in a linear relationship, and their ratio is the sensitivity of the electromagnetic force measurement system, recorded as A (Nm / V), and we can get:

[0065] m1gL1-m2gL2=(V2-V1)A (1)

[0066] in:

[0067] m1: equal weight loaded on the left pan, kg;

[0068] m2: the equal weight loaded on the right pan, kg;

[0069] g: acceleration due to gravity, m / s 2 ;

[0070] L1: left arm length, m;

[0071] L2: right arm length, m;

[0072] V2: Output voltage of electromagnetic force measurement system, V;

[0073] A: Sensitivity of small torque sensor, Nm / V.

[0074] 4) In order to eliminate the influence of unequal weights on the left and right pans, swap the weights on the left and right pans and measure again. Load the weight of mass m2 on the left pan and the weight of mass m1 on the right pan. Read the output voltage of the electromagnetic force measurement system as V3. The change in the voltage output of the electromagnetic force measurement system is directly caused by the unequal arms, such as Fig.11 As shown. We can get:

[0075] m2gL1-m1gL2=(V3-V1)A (2)

[0076] in:

[0077] V3: Output voltage of electromagnetic force measurement system, V.

[0078] 5) Remove the weights from the left and right pans, then load other weights of E1 grade on the left pan, record the mass as m3, and read the voltage output of the electromagnetic force measurement system as V4. Compared with the no-load state, the change in the voltage output value of the electromagnetic force measurement system is directly caused by the weight of mass m3, such as Fig.12 As shown, we can get:

[0079] m3gL1=(V4-V1)A (3)

[0080] in:

[0081] m3: another weight loaded on the left pan, a known quantity, kg;

[0082] V4: Output voltage of electromagnetic force measurement system, V.

[0083] 6) The total arm length of the lever can be easily measured by geometric method. After the lever crossbeam is processed, the total length is measured by a three-coordinate machine, recorded as L, and then:

[0084] L1+L2=L (4)

[0085] By combining equations (1) to (4), we can calculate the specific values ​​of the arm lengths on both sides:

[0086]

[0087] According to the difference in the specific values ​​of the arm lengths on both sides, adjust the arm ratio fine-tuning structure mentioned in (1) until the arm lengths are completely divided equally.

[0088] The invention is mainly used for adjusting the arm length ratio of a torque standard device, thereby providing an accurate torque standard value.

Claims

1. An arm ratio adjustment system for a lever-amplified torque standard device, characterized in that: Including electromagnetic force measuring system and arm ratio fine-tuning structure; The arm ratio fine-tuning structure is used to fine-tune the arm length; The electromagnetic force measuring system is used to measure the unbalanced torque introduced by the arm length difference to calculate the arm length difference after the arm length is fine-tuned.

2. The arm ratio adjustment system for a lever-amplified torque standard device according to claim 1, characterized in that: The arm ratio fine-tuning structure comprises a left angle wedge (1), a left fine-tuning screw (2), a middle angle wedge (3), a balance beam (4), a right fine-tuning screw (6), and a right angle wedge (7); a groove is processed on the lower surface of the balance beam (4), and the left angle wedge (1), the middle angle wedge (3), and the right angle wedge (7) are all located in the groove; the middle angle wedge (3) is fixed to a base (9) by a hanging spring (8), and the middle angle wedge (3) is an isosceles trapezoidal structure, and the middle angle wedge (3) is located between the left angle wedge (1) and the right angle wedge (7). The wedge blocks (7) have the same structure, which are both right-angle trapezoidal structures. The inclined surfaces of the left angle wedge block and the right angle wedge block are in contact with the inclined surfaces on both sides of the middle angle wedge block, and the left angle wedge block (1) and the right angle wedge block (7) are symmetrical along the center of the middle angle wedge block (3); the left angle wedge block (1) is connected to the balance beam (4) through a left fine-tuning screw (2), and the right angle wedge block (7) is connected to the balance beam (4) through a right fine-tuning screw (6); the vertical surface of the left angle wedge block is parallel to and closely attached to the left vertical surface of the groove of the balance beam, and the vertical surface of the right angle wedge block is parallel to and closely attached to the right vertical surface of the groove of the balance beam.

3. The arm ratio adjustment system for a lever-amplified torque standard device according to claim 2, characterized in that: The inclination angles of the inclined surfaces of the left angle wedge, the right angle wedge and the middle angle wedge are 80°.

4. The arm ratio adjustment system for a lever-amplified torque standard device according to claim 2, characterized in that: The electromagnetic force measurement system includes a torquer, a damper, a displacement sensor, a torque processing unit, a speed signal amplifier, a speed converter, a displacement converter, and an amplification unit; the torquer is fixed at one end of the balance beam, and the damping coil and the displacement sensor are located at the other end of the balance beam; the displacement sensor is used to sense the angular displacement change of the balance beam, and the output value is output to the amplification unit after being converted by the displacement converter; the damper provides damping for the system, and the output damping force is converted into a speed signal by the speed converter, which is amplified by the speed signal amplifier and output to the amplification unit; the PID processing unit processes the signal amplified by the amplification unit to obtain a feedback current, which is fed back to the torquer to make the torquer generate a balancing force; the feedback current reflects the magnitude of the unbalanced torque.

5. The arm ratio adjustment system for a lever-amplified torque standard device according to claim 4, characterized in that: The arm length difference can be calculated based on the unbalanced torque.

6. A method for adjusting the arm ratio of a lever-amplified torque standard device, characterized in that: include: 1) According to the actual use conditions, the length of the left arm is defined as L1 and the length of the right arm is defined as L2; 2) The left and right weight plates are empty, and the output voltage V1 is calculated based on the feedback current of the electromagnetic force measurement system; 3) Load a weight on the left pan with a mass of m1, and load a weight of the same specification on the right pan with a mass of m2. Calculate the output voltage V2 of the electromagnetic force measurement system. During the test, the output voltage and torque of the electromagnetic force measurement system are in a linear relationship, and their ratio is the sensitivity of the electromagnetic force measurement system, recorded as A, and we get: m1gL1-m2gL2=(V2-V1)A (1) 4) Swap the weights on the left and right pans and measure again. Load the weight of mass m2 on the left pan and the weight of mass m1 on the right pan. Calculate the output voltage V3 based on the feedback current of the electromagnetic force measurement system. The change in the voltage output of the electromagnetic force measurement system is directly caused by the unequal arms, and we get: m2gL1-m1gL2=(V3-V1)A (2) 5) Remove the weights loaded on the left and right pans, and then load other weights of E1 grade on the left pan, with the mass recorded as m3. Calculate the output voltage V4 based on the feedback current of the electromagnetic force measurement system; compared with the no-load state, the change in the voltage output value of the electromagnetic force measurement system is directly caused by the weight with a mass of m3, and we get: m3gL1=(V4-V1)A (3) 6) After the balance beam is processed, use a three-coordinate machine to measure its total length, recorded as L, then: L1+L2=L (4) By combining equations (1) to (4), we can calculate the specific values ​​of the arm lengths on both sides: According to the difference in specific values ​​of the arm lengths on both sides, adjust the arm ratio fine-tuning structure until the arm lengths are completely equally divided.

7. The arm ratio adjustment method for a lever-amplified torque standard device according to claim 6, characterized in that: The method of adjusting the arm ratio fine-tuning structure is as follows: When it is necessary to fine-tune the balance beam to the left, first loosen the right fine-tuning screw, then adjust the left fine-tuning screw, press the left angle wedge to make it move upward along the inclined surface of the middle angle wedge, thereby squeezing the balance beam to force it to deviate to the left. At this time, the left arm becomes longer and the right arm becomes shorter. After adjusting the arm length to the appropriate position, tighten the right fine-tuning screw and lock the right angle wedge to complete the fine-tuning of the balance arm length to the left. When it is necessary to fine-tune the balance beam to the right, first loosen the left fine-tuning screw, then adjust the right fine-tuning screw, press the right angle wedge to make it move upward along the inclined surface of the middle angle wedge, thereby squeezing the balance beam and forcing it to deviate to the right. At this time, the right arm becomes longer and the left arm becomes shorter; after adjusting the arm length to the appropriate position, tighten the left fine-tuning screw, lock the left angle wedge, and complete the fine-tuning of the balance arm length to the right.

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