Radial play control technique for trapezoidal screw pair

Abstract

The application discloses a kind of trapezoidal screw pair radial matching gap control technical methods, it is related to trapezoidal screw pair radial matching gap technical field, solve the actual processing problem of non-standard middle thread specification, supplement the processing technical parameter of non-standard middle trapezoidal screw pair, from the selection of trapezoidal screw pair trapezoidal thread tolerance, the determination of trapezoidal screw and matching nut thread middle diameter limit deviation, the measurement of actual normal tooth thickness value at the middle diameter of internal thread and external thread in actual processing process, the control of trapezoidal screw pair radial matching gap, trapezoidal screw pair matching gap VB calculation program is prepared etc. Process has obtained the complete set of technical scheme that trapezoidal screw pair radial matching gap meets acceptance requirement, introduces a new method to control the middle diameter of internal thread and external thread.This technical method provides technical support and method guidance for the processing of trapezoidal screw pair, injects new vitality for the rapid development of industry.Based on the new method that tooth thickness digital caliper controls internal and external trapezoidal thread middle diameter value improves the efficiency and precision of trapezoidal screw pair workshop processing, ensures processing quality.

Description

Technical Field

[0001] This invention relates to the field of radial clearance control technology for trapezoidal lead screw pairs, and in particular to a method for controlling the radial clearance control of trapezoidal lead screw pairs. Background Technology

[0002] Trapezoidal lead screw pairs have the function of converting helical motion into linear motion with a conversion efficiency of about 70%. Compared with other types of lead screws, trapezoidal lead screw pairs have a larger lead, which can provide faster feed at low speeds and have a strong load-bearing capacity. They are widely used in machine tools, mining, medical, defense and other fields.

[0003] A trapezoidal lead screw assembly consists of two parts: a trapezoidal lead screw and a mating nut. Currently, the machining of trapezoidal lead screw assemblies is mainly carried out according to the mechanical industry standard JB / T 2886-2008. The radial clearance of the trapezoidal lead screw assembly is a crucial indicator for its acceptance and a key factor determining its transmission performance. Whether the radial clearance of the trapezoidal lead screw assembly is acceptable is ensured by the pitch diameter tolerances of the trapezoidal lead screw and the mating nut. Therefore, the key to meeting the acceptance criteria for a trapezoidal lead screw assembly is controlling the pitch diameter deviations of the external thread of the trapezoidal lead screw and the internal thread of the mating nut. Referring to the technical specifications for trapezoidal lead screws and nuts on machine tools, the limit deviation of the thread pitch diameter of the trapezoidal lead screw can be found in Table 6 of the mechanical industry standard JB / T 2886-2008 (5.6.1). The limit deviation of the thread pitch diameter of the matching nut needs to be controlled based on the radial clearance between the nut and the lead screw. The radial clearance can be found in Appendix B of the mechanical industry standard JB / T 2886-2008 (5.7.2). However, the pitch range in the technical standard is 2 to 20 mm, and non-standard thread specifications cannot be machined according to this pitch range. Summary of the Invention

[0004] To address the shortcomings in the aforementioned background technology, this invention proposes a method for controlling the radial clearance of trapezoidal lead screw pairs, which solves the problem of difficulty in determining the radial clearance of non-standard trapezoidal lead screw pairs in the prior art.

[0005] The technical solution of this invention is implemented as follows: a method for controlling the radial clearance of a trapezoidal lead screw pair, characterized by comprising the following steps:

[0006] S1: Based on the manufacturing precision requirements of the trapezoidal lead screw pair to be machined and the effective thread length of the trapezoidal lead screw, select the corresponding radial clearance value according to Appendix B of the mechanical industry standard JB / T 2886-2008, and use the clearance fit formula: maximum clearance value X max =ES-ei, minimum gap value X min=EI-es, where ES is the upper deviation of the hole; es is the upper deviation of the shaft; EI is the lower deviation of the hole; ei is the lower deviation of the shaft, the trapezoidal screw is the shaft, and the matching nut is the hole; combined with the tolerance value of the pitch diameter of the external thread, the limit deviation size of the pitch diameter of the external thread of the trapezoidal screw and the internal thread of the matching nut in the target trapezoidal screw pair is set to meet the target clearance;

[0007] S2: Use CAD design software to draw the internal and external thread groove diagrams with limit deviation dimensions. Use CAD design software to mark and measure the tooth thickness values ​​at the mean diameter of the trapezoidal screw and the mating nut with limit deviation dimensions, and then obtain the normal tooth thickness setting range at the mean diameter of the trapezoidal screw and the mating nut.

[0008] S3: Based on the tooth thickness value obtained in step S2, process the trapezoidal lead screw and matching nut parts. Use a tooth thickness digital caliper to measure and record the normal tooth thickness at the mean diameter of the internal and external threads as the actual normal tooth thickness value.

[0009] S4: Number the processed parts, compare and analyze the actual normal tooth thickness value measured in step S3 with the normal tooth thickness setting range in step S2, and determine whether the processing requirements are met; perform matching processing on parts whose actual normal tooth thickness value is outside the normal tooth thickness setting range.

[0010] Preferably, the matching process in step S4 satisfies the formula: Where A is the half angle of the trapezoidal thread, P is the pitch of the trapezoidal thread, x1 is the tooth thickness at the mean diameter of the external thread of the trapezoidal screw, and x2 is the tooth thickness at the mean diameter of the internal thread of the nut.

[0011] Preferably, the method for determining whether the machined part meets the processing requirements in step S4 is as follows: if the actual normal tooth thickness values ​​of the trapezoidal lead screw and the mating nut are both within the normal tooth thickness setting range in step S2, then the radial clearance of the paired trapezoidal lead screw pair meets the requirements of the mechanical industry standard JB / T 2886-2008; if at least one of the actual normal tooth thickness values ​​of the trapezoidal lead screw or the mating nut is not within the setting range in step S2, it needs to be mated. During mating, the tooth thickness value at the middle diameter of the mating part required to achieve the target clearance is determined according to the normal tooth thickness value at the middle diameter of the manufactured part, and the mating part is obtained by processing according to this value.

[0012] Preferably, the process of measuring the normal tooth thickness at the pitch diameter of the internal and external threads using a tooth thickness digital caliper in step S3 includes:

[0013] S3.1: Set the vertical ruler value of the tooth thickness digital caliper so that the measuring position of the tooth thickness digital caliper is at the mean diameter of the external thread of the trapezoidal lead screw or the internal thread of the nut.

[0014] S3.2: Rotate the measuring direction of the tooth thickness digital caliper by a thread helix angle γ. At this time, the reading of the tooth thickness digital caliper is the actual normal tooth thickness value.

[0015] Preferably, the formula for calculating the degree of the thread helix angle γ is: Where n is the number of starts in the trapezoidal thread; P is the pitch of the trapezoidal thread; and d2 is the pitch diameter of the external thread for the basic and designed tooth profiles of the trapezoidal thread.

[0016] Preferably, when setting the value of the vertical ruler in step S3.1, first use an inside micrometer to measure the actual measured value D1 of the minor diameter of the internal thread of the mating nut, and then use the formula: Calculate and set the vertical ruler value z when measuring the tooth thickness of the mating nut, where h is the tooth height of the basic tooth profile of the thread specification, and D2 is the minor diameter of the internal thread on the basic tooth profile and the designed tooth profile of the thread specification.

[0017] Preferably, when setting the value of the vertical ruler in step S3.1, first use an outside micrometer to measure the actual measured value D3 of the major diameter of the external thread of the trapezoidal lead screw, and then use the formula: Calculate and set the vertical ruler value Z when measuring the tooth thickness of the trapezoidal lead screw, where h is the tooth height of the basic tooth profile of the thread specification, and D4 is the major diameter of the external thread on the basic tooth profile and the design tooth profile of the thread specification, i.e., the nominal diameter.

[0018] Preferably, the following steps are also included:

[0019] S5: Using the relationship between the actual normal tooth thickness values ​​at the mean diameter of the trapezoidal lead screw and the mating nut in step S4, a Visual Basic visualization program is developed. The program calculates the mating tooth thickness value that meets the expected radial mating clearance based on the known tooth thickness value at the mean diameter, providing data support for subsequent mating machining.

[0020] The beneficial effects of this invention are as follows: This solution addresses the practical machining challenges of non-standard thread specifications, supplements the machining technical parameters for non-standard trapezoidal screw pairs, and obtains a complete technical solution for ensuring the radial fitting clearance of trapezoidal screw pairs meets acceptance requirements through processes such as selecting the tolerance of trapezoidal threads in trapezoidal screw pairs, determining the limit deviation of the pitch diameter of the trapezoidal screw and mating nut threads, measuring the actual normal tooth thickness at the pitch diameter of the internal and external threads during actual machining, controlling the radial fitting clearance of the trapezoidal screw pair, and developing a VB calculation program for the fitting clearance of the trapezoidal screw pair. A new method for controlling the pitch diameter of the internal and external threads is introduced. This technical method provides technical support and methodological guidance for the machining of trapezoidal screw pairs, injecting new vitality into the rapid development of the industry. The new method of controlling the pitch diameter of internal and external trapezoidal threads based on a digital caliper of tooth thickness improves the efficiency and accuracy of workshop machining of trapezoidal screw pairs, ensuring machining quality. It solves the problem of difficulty in determining the radial fitting clearance of non-standard trapezoidal screw pairs in existing technologies. It supplements the machining technical parameters for non-standard trapezoidal screw pairs, improving the feasibility of machining trapezoidal screw pairs of all specifications. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the radial fitting gap control method of the present invention;

[0023] Figure 2 This is a schematic diagram of the trapezoidal lead screw tooth profile of the present invention;

[0024] Figure 3 A schematic diagram of the nut tooth profile is provided for this invention.

[0025] Figure 4 This is a schematic diagram of the tooth thickness digital caliper of the present invention;

[0026] Figure 5 This is a schematic diagram of the trapezoidal lead screw tooth profile of the present invention at an accuracy level of 8;

[0027] Figure 6 This is a schematic diagram of the nut tooth profile for the present invention when the accuracy class is 8;

[0028] Figure 7 This is a flowchart illustrating the machining process for the trapezoidal lead screw assembly of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figure 1 As shown in Example 1, a method for controlling the radial clearance of a trapezoidal lead screw pair includes the following steps:

[0031] S1: Based on the manufacturing precision requirements of the trapezoidal lead screw pair to be machined and the effective thread length of the trapezoidal lead screw, select the corresponding radial clearance value according to Appendix B of the mechanical industry standard JB / T 2886-2008, and use the clearance fit formula: maximum clearance value X max =ES-ei, minimum gap value X min =EI-es, where ES is the upper deviation of the hole; es is the upper deviation of the shaft; EI is the lower deviation of the hole; ei is the lower deviation of the shaft. In this embodiment, the trapezoidal lead screw is the shaft, and the nut is the hole.

[0032] Based on the tolerance value of the pitch diameter of the external thread, set the limit deviation dimensions of the pitch diameter of the external thread of the trapezoidal screw and the internal thread of the matching nut in the target trapezoidal screw pair to meet the target clearance.

[0033] S2: Use CAD design software to draw the internal and external thread groove shapes with limit deviation dimensions. Use the CAD design software to annotate and measure the tooth thickness values ​​at the pitch diameter of the trapezoidal lead screw and the mating nut with limit deviation dimensions. Then, obtain the set range of normal tooth thickness values ​​at the pitch diameter of the trapezoidal lead screw and the mating nut. Figure 2 , Figure 3 As shown, d0 is the optimal diameter of the three needles in the three-needle measurement method, according to the formula... Calculate, where P is the pitch of the trapezoidal thread, A is the half angle of the trapezoidal thread, X1 in the figure is the normal tooth thickness deviation 1 at the actual pitch diameter of the trapezoidal screw, X2 is the normal tooth thickness deviation 2 at the actual pitch diameter of the trapezoidal screw; X3 is the normal tooth thickness deviation 1 at the actual pitch diameter of the mating nut, and X4 is the normal tooth thickness deviation 2 at the actual pitch diameter of the mating nut.

[0034] S3: Based on the tooth thickness value obtained in step S2, process the trapezoidal lead screw and matching nut parts. Use a tooth thickness digital caliper to measure and record the normal tooth thickness at the pitch diameter of the internal and external threads as the actual normal tooth thickness value. The measurement process includes:

[0035] S3.1: Set the vertical ruler value of the tooth thickness digital caliper so that the measuring position of the tooth thickness digital caliper is at the mean diameter of the external thread of the trapezoidal lead screw or the internal thread of the nut.

[0036] S3.1.1: When setting the value of the vertical ruler, first use an inside micrometer to measure the actual measured value D1 of the minor diameter of the internal thread of the mating nut, and then follow the formula: Calculate and set the vertical ruler value z when measuring the tooth thickness of the mating nut, where h is the tooth height of the basic tooth profile of the thread specification, and D2 is the minor diameter of the internal thread on the basic tooth profile and the designed tooth profile of the thread specification.

[0037] S3.1.2: When setting the vertical ruler value, first use an outside micrometer to measure the actual measured value D3 of the major diameter of the external thread of the trapezoidal lead screw, and then follow the formula: Calculate and set the vertical ruler value Z when measuring the tooth thickness of the trapezoidal lead screw, where h is the tooth height of the basic tooth profile of the thread specification, and D4 is the major diameter of the external thread on the basic tooth profile and the design tooth profile of the thread specification, i.e., the nominal diameter.

[0038] S3.2: Rotate the measuring direction of the tooth thickness digital caliper by a thread helix angle γ. At this time, the reading of the tooth thickness digital caliper is the actual normal tooth thickness value.

[0039] S3.2.1: The formula for calculating the degree measure of the thread helix angle γ is: Where n is the number of starts in the trapezoidal thread; P is the pitch of the trapezoidal thread; and d2 is the pitch diameter of the external thread for the basic and designed tooth profiles of the trapezoidal thread.

[0040] S4: Number the machined parts, and compare the actual normal tooth thickness value measured in step S3 with the normal tooth thickness set value range in step S2 to determine whether the machining requirements are met; parts outside the normal tooth thickness set value range need to be fitted, where the fitting process satisfies the formula: A is the half angle of the trapezoidal thread, P is the pitch of the trapezoidal thread, x1 is the tooth thickness at the mean diameter of the external thread of the trapezoidal screw, and x2 is the tooth thickness at the mean diameter of the internal thread of the nut.

[0041] The following methods should be used to determine whether the machined parts meet the machining requirements:

[0042] S4.1: If the actual normal tooth thickness values ​​of the trapezoidal lead screw and the mating nut are both within the normal tooth thickness setting range in step S2, then the radial clearance of the paired trapezoidal lead screw pair meets the requirements of mechanical standard JB / T 2886-2008.

[0043] S4.2: If at least one of the actual normal tooth thickness values ​​of the trapezoidal lead screw or the matching nut is outside the range set in step S2, it needs to be matched. During the matching process, the tooth thickness value at the middle diameter of the matching part required to achieve the target clearance is determined based on the normal tooth thickness value at the middle diameter of the manufactured part, and the matching part is obtained by processing according to this value.

[0044] S5: Using the relationship between the actual normal tooth thickness values ​​at the mean diameter of the trapezoidal lead screw and the mating nut in step S4, a Visual Basic visualization program is developed. The program calculates the mating tooth thickness value that meets the expected radial mating clearance based on the known tooth thickness value at the mean diameter, providing data support for subsequent mating machining.

[0045] Example 2: Based on Example 1, a Tr150×24 lead screw pair was machined according to GB / T 5796-2005. The thread accuracy grade meets the requirements of Grade 8 of JB / T 2886-2008. The effective thread length of the trapezoidal lead screw is 1200mm.

[0046] S1: Based on the manufacturing precision requirements of the trapezoidal lead screw pair to be processed and the effective thread length of the trapezoidal lead screw, select the corresponding radial clearance value according to Appendix B of JB / T 2886-2008. In this embodiment, the radial clearance value of the nut and lead screw is selected as (0.12~0.20) mm.

[0047] Clearance fit formula: Maximum clearance value X max =ES-ei, minimum gap value X min =EI-es, where ES is the upper deviation of the hole; es is the upper deviation of the shaft; EI is the lower deviation of the hole; ei is the lower deviation of the shaft. In this embodiment, the trapezoidal lead screw is the shaft, and the nut is the hole. In this embodiment, the maximum clearance value X max =0.20, minimum gap value X min =0.12, the upper deviation of the matching nut is ES = +0.1, the lower deviation is es = +0.04, the upper deviation of the trapezoidal screw is EI = -0.08, and the lower deviation is ei = -0.1.

[0048] Based on the calculation of the pitch diameter grade tolerance of external threads in section 9.3 of GB / T 5796.4-2005, and using the calculated values, the limit deviation dimensions at the pitch diameter of the external thread of the trapezoidal screw and the internal thread of the mating nut in the target trapezoidal screw pair are set to meet the target clearance of (0.12~0.20) mm. In this embodiment, to obtain the trapezoidal screw pair with the target radial mating clearance, the limit deviation values ​​of the pitch diameter of the trapezoidal screw and the mating nut are set as follows:

[0049] S2: Referring to the trapezoidal thread groove diagram (GB / T 5796.1-2005), use CAD design software to draw the internal and external thread groove diagrams with limit deviation dimensions. Use the CAD design software to annotate and measure the tooth thickness values ​​at the pitch diameter of the trapezoidal screw and the mating nut with limit deviation dimensions, thereby obtaining the set range of normal tooth thickness values ​​at the pitch diameter of the trapezoidal screw and the mating nut. In this embodiment, by... Figure 5 and Figure 6It can be seen that the setting range of the trapezoidal lead screw is (11.97~11.98) mm, and the setting range of the matching nut is (11.97~11.99) mm.

[0050] S3: Based on the tooth thickness value obtained in step S2, process the trapezoidal lead screw and matching nut parts. Use a tooth thickness digital caliper to measure and record the normal tooth thickness at the pitch diameter of the internal and external threads as the actual normal tooth thickness value. The measurement process includes:

[0051] S3.1: As Figure 4 As shown, set the vertical ruler value of the tooth thickness digital caliper so that the measuring position of the tooth thickness digital caliper is at the mean diameter of the external thread of the trapezoidal lead screw or the internal thread of the nut.

[0052] S3.1.1: When setting the value of the vertical ruler, first use an inside micrometer to measure the actual measured value D1 of the minor diameter of the internal thread of the mating nut, and then follow the formula: Calculate and set the vertical ruler value z when measuring the tooth thickness of the mating nut, where h is the tooth height of the basic tooth profile of the thread specification, and D2 is the minor diameter of the internal thread on the basic tooth profile and the designed tooth profile of the thread specification. Referring to GB / T 5796.1-2005 trapezoidal thread tooth profile, in this embodiment, h=12, D2=126.

[0053] S3.1.2: When setting the vertical ruler value, first use an outside micrometer to measure the actual measured value D3 of the major diameter of the external thread of the trapezoidal lead screw, and then follow the formula: Calculate and set the vertical ruler value Z when measuring the tooth thickness of the trapezoidal leadscrew, where h is the tooth height of the basic tooth profile of this thread specification, and D4 is the major diameter (nominal diameter) of the external thread on the basic and designed tooth profiles of this thread specification. Referring to GB / T 5796.1-2005 Trapezoidal Thread Tooth Profile, in this embodiment, h = 12, D4 = 150.

[0054] S3.2: Rotate the measuring direction of the tooth thickness digital caliper by a thread helix angle γ, so that the reading of the tooth thickness digital caliper is the actual normal tooth thickness value.

[0055] S3.2.1: The formula for calculating the degree measure of the thread helix angle γ is: According to the formula, where n is the number of starts in the trapezoidal thread; P is the pitch of the trapezoidal thread; and d2 is the pitch diameter of the external thread for the basic and designed tooth profiles of the trapezoidal thread. In this embodiment, n = 1, P = 24, and d2 = 138. From the above formula, we can obtain...

[0056] S4: Number the machined parts, and compare the actual normal tooth thickness value measured in step S3 with the normal tooth thickness set value range in step S2 to determine whether the machining requirements are met; parts outside the normal tooth thickness set value range need to be fitted, where the fitting process satisfies the formula: A is the half-angle of the trapezoidal thread profile, P is the pitch of the trapezoidal thread, x1 is the tooth thickness at the pitch diameter of the external thread of the trapezoidal screw, and x2 is the tooth thickness at the pitch diameter of the internal thread of the mating nut. In this embodiment, let the tooth thickness at the pitch diameter of the trapezoidal screw be x1, and the tooth thickness at the pitch diameter of the mating nut be x2; then the tooth thickness at the pitch diameter of the nut groove is: 24 - x2. The radial clearance of the trapezoidal screw pair is related to the tooth thickness at the pitch diameter as follows:

[0057] The following methods should be used to determine whether the machined parts meet the machining requirements:

[0058] S4.1: If the actual normal tooth thickness values ​​of the trapezoidal lead screw and the mating nut are both within the normal tooth thickness setting range in step S2, then the radial clearance of the paired trapezoidal lead screw pair meets the requirements of JB / T 2886-2008.

[0059] S4.2: If at least one of the actual normal tooth thickness values ​​of the trapezoidal lead screw or the matching nut is outside the range set in step S2, it needs to be matched. During the matching process, the tooth thickness value at the middle diameter of the matching part required to achieve the target clearance is determined based on the normal tooth thickness value at the middle diameter of the manufactured part, and the matching part is obtained by processing according to this value.

[0060] S5: As Figure 7 As shown, by utilizing the relationship between the actual normal tooth thickness values ​​at the mean diameter of the trapezoidal lead screw and the mating nut in step S4, a Visual Basic visualization program is developed. The program calculates the mating tooth thickness value that satisfies the expected radial mating clearance based on the known tooth thickness value at the mean diameter, providing data support for subsequent mating machining.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the radial clearance of a trapezoidal lead screw pair, characterized in that: Includes the following steps: S1: Based on the manufacturing precision requirements of the trapezoidal lead screw pair to be machined and the effective thread length of the trapezoidal lead screw, select the corresponding radial clearance value according to Appendix B of the mechanical industry standard JB / T 2886-2008, and use the clearance fit formula: Maximum gap value Minimum gap value , Where ES is the upper deviation of the hole; es is the upper deviation of the shaft; EI is the lower deviation of the hole; ei is the lower deviation of the shaft, the trapezoidal lead screw is the shaft, and the nut is the hole; Based on the tolerance value of the pitch diameter of the external thread, set the limit deviation dimensions of the pitch diameter of the external thread of the trapezoidal screw and the internal thread of the nut in the target trapezoidal screw pair to meet the target clearance. S2: Use CAD design software to draw the internal and external thread groove diagrams with limit deviation dimensions. Use CAD design software to mark and measure the tooth thickness values ​​at the mean diameter of the trapezoidal screw and the mating nut with limit deviation dimensions, and then obtain the normal tooth thickness setting range at the mean diameter of the trapezoidal screw and the mating nut. S3: Based on the tooth thickness value obtained in step S2, process the trapezoidal lead screw and matching nut parts. Use a tooth thickness digital caliper to measure and record the normal tooth thickness at the mean diameter of the internal and external threads as the actual normal tooth thickness value. S4: Number the processed parts, compare and analyze the actual normal tooth thickness value measured in step S3 with the normal tooth thickness setting range in step S2, and determine whether the processing requirements are met; perform matching processing on parts whose actual normal tooth thickness value is outside the normal tooth thickness setting range.

2. The method for controlling the radial clearance of the trapezoidal lead screw pair according to claim 1, characterized in that: The matching process in step S4 satisfies the following formula: ， Where A is the half-angle of the trapezoidal thread, and P is the pitch of the trapezoidal thread. This refers to the tooth thickness at the mean diameter of the external thread of the trapezoidal leadscrew. The tooth thickness value at the pitch diameter of the internal thread of the nut.

3. The radial clearance control method for the trapezoidal lead screw pair according to claim 2, characterized in that: The method for determining whether the machined parts meet the processing requirements in step S4 is as follows: If the actual normal tooth thickness values ​​of the trapezoidal lead screw and the matching nut are both within the normal tooth thickness setting range in step S2, then the radial clearance of the paired trapezoidal lead screw pair meets the requirements of the mechanical industry standard JB / T 2886-2008; if at least one of the actual normal tooth thickness values ​​of the trapezoidal lead screw or the matching nut is not within the setting range in step S2, it needs to be matched and processed. During the matching and processing, the tooth thickness value at the middle diameter of the matching part required to achieve the target clearance is determined according to the normal tooth thickness value at the middle diameter of the already manufactured part, and the matching part is obtained by processing according to this value.

4. The radial clearance control method for the trapezoidal lead screw pair according to claim 3, characterized in that: The process of measuring the normal tooth thickness at the pitch diameter of the internal and external threads using a tooth thickness digital caliper in step S3 includes: S3.1: Set the vertical ruler value of the tooth thickness digital caliper so that the measuring position of the tooth thickness digital caliper is at the mean diameter of the external thread of the trapezoidal lead screw or the internal thread of the nut. S3.2: Rotate the measuring direction of the tooth thickness digital caliper by a thread helix angle γ. At this time, the reading of the tooth thickness digital caliper is the actual normal tooth thickness value.

5. The radial clearance control method for the trapezoidal lead screw pair according to claim 4, characterized in that: The formula for calculating the degree of the thread helix angle γ is as follows: Where n is the number of starts in the trapezoidal thread; P is the pitch of the trapezoidal thread; The mean diameter of the external thread for the basic and designed tooth profiles of the trapezoidal thread.

6. The radial clearance control method for the trapezoidal lead screw pair according to claim 5, characterized in that: When setting the value of the vertical ruler in step S3.1, first use an inside micrometer to measure the actual measured value of the minor diameter of the internal thread of the mating nut. Then follow the formula: ； Calculate and set the vertical ruler value when measuring the tooth thickness of the mating nut. Where h represents the basic tooth height of the thread specification. This refers to the minor diameter of the internal thread on the basic tooth profile and the designed tooth profile of this thread specification.

7. The radial clearance control method for the trapezoidal lead screw pair according to claim 6, characterized in that: When setting the value of the vertical ruler in step S3.1, first use an outside micrometer to measure the actual measured value of the major diameter of the external thread of the trapezoidal lead screw. Then follow the formula: ； Calculate and set the vertical ruler value when measuring the tooth thickness of the trapezoidal lead screw. Where h is the basic tooth height of this thread specification. The nominal diameter is the major diameter of the external thread on the basic and designed tooth profiles of this thread specification.

8. The method for controlling the radial clearance of the trapezoidal lead screw pair according to claim 7, characterized in that: It also includes the following steps: S5: Using the relationship between the actual normal tooth thickness values ​​at the mean diameter of the trapezoidal lead screw and the mating nut in step S4, a Visual Basic visualization program is developed. The program calculates the mating tooth thickness value that meets the expected radial mating clearance based on the known tooth thickness value at the mean diameter, providing data support for subsequent mating machining.

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