Method and device for measuring the diameter of a nut at extreme temperatures

Abstract

The application provides a nut diameter measurement method and device under extreme temperature, and the measurement device comprises a detection base, a nut placing table, a micrometer, a guide cylinder, a temperature insulation rod, a temperature insulation block, a ball, and a temperature measuring instrument. The measurement method comprises providing a nut to be measured and a required extreme temperature, and selecting a corresponding ball according to the nut. The nut is placed on the nut placing table, and the measurement device is adjusted according to the size of the nut. The temperature of the nut is set to a suitable temperature by a heating / cooling machine, and then the nut is quickly installed in the measurement device. The temperature is monitored by the temperature measuring instrument, and when the temperature of the nut reaches the required extreme temperature, the measurement results of each micrometer are recorded. The diameter value under room temperature is measured, and the diameter value under the extreme temperature is obtained by calculation. The technical scheme of the application solves the problems of difficult measurement and inaccurate measurement of the nut diameter under the extreme temperature.

Description

Technical Field

[0001] This invention belongs to the field of nut measurement, and in particular to a method and apparatus for measuring the mean diameter of a nut under extreme temperatures. Background Technology

[0002] Nuts are key components in mechanical transmission systems, often used in conjunction with bolts or lead screws to connect or secure various parts. Nuts achieve precise axial movement and positioning through the engagement of their internal threads with the external threads of the bolt or lead screw. Nuts used with bolts are also called nuts, and their internal thread raceways are often triangular. Nuts used with lead screws have different normal cross-sections of their internal threads depending on the type of engagement. When the nut and lead screw are directly engaged in a helical pair to form a helical sliding transmission, their internal threads will be rectangular, trapezoidal, or sawtooth-shaped. When balls are inserted between the nut and lead screw to form a rolling helical pair, the nut is called a ball nut, and its internal thread normal cross-section is often a single circular arc or a Gothic double circular arc. When planetary rollers are used as an intermediate component between the nut and lead screw, the nut is called a roller nut, and its internal thread normal cross-section often resembles the tooth profile of a gear. Regardless of the type of nut, they all share a crucial thread geometry parameter: the pitch diameter. The pitch diameter, located between the crest and root of a thread, is a critical dimension that determines the nature and strength of the thread fit. The pitch diameter of a nut plays a vital role in thread design and application, affecting the thread fit, stress distribution, and overall connection performance. Proper design and control of the nut's pitch diameter ensures the safety, reliability, and durability of threaded connections.

[0003] The conventional method for measuring the pitch diameter of a nut is to first measure the outer diameter of the nut, then place a corresponding ball bearing into the raceway, and use a dial indicator to measure the distance from the ball bearing's surface to the outer diameter of the nut. The pitch diameter is then calculated. However, with technological advancements, newer nut pitch diameter measuring devices have been developed, such as a ball bearing nut pitch diameter measuring structure (CN208349988U) and a heavy-duty nut pitch diameter measuring instrument (CN207600352U). These devices improve the efficiency of nut pitch diameter measurement, but they can only measure the pitch diameter of nuts at room temperature. This is because these methods require direct human contact with the nut, and even short-term contact at temperatures below -5℃ or above 55℃ can damage the skin. Furthermore, direct contact with extreme temperatures can lead to inaccurate measurement results or even damage to the measuring instrument.

[0004] However, with the development of technology, nuts are increasingly used under extreme temperatures. For example, they are indispensable in various applications such as automobiles operating outdoors in Northeast China and Xinjiang, nuclear power plant drive mechanisms, and aerospace systems. To ensure that nuts achieve optimal performance under extreme temperatures, it is necessary to know their pitch diameter at those temperatures to better guide design. Therefore, it is essential to invent a method and device for measuring the pitch diameter of nuts under extreme temperatures. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for measuring the pitch diameter of nuts under extreme temperatures, so as to solve the problem that the pitch diameter of nuts cannot be measured or cannot be measured accurately under extreme temperature conditions, thereby guiding the design of nuts that can work normally at the corresponding temperatures.

[0006] The technical solution to achieve the purpose of this invention is as follows:

[0007] The testing platform is used to fix the nut placement platform and multiple testing brackets;

[0008] Nut placement platform, used to place and position the nut to be tested;

[0009] The testing bracket is used to connect the insulation unit and adjust its position so that it comes into contact with the object being tested.

[0010] The temperature insulation unit is in contact with the object being measured at its lower end and connected to a dial indicator at its upper end.

[0011] A thermometer is used to detect the temperature at the contact point between the ball bearings inside the nut and the nut itself.

[0012] The dial indicator includes a ground-measuring dial indicator, a top-measuring dial indicator, and a raceway-measuring dial indicator, which respectively contact the nut placement platform, the outer diameter of the nut being measured, and the inner ball bearings of the raceway of the nut being measured through corresponding heat insulation units. The ground-measuring dial indicator is used to detect the change in the surface height of the nut placement platform when the temperature returns from the required extreme temperature to room temperature. The top-measuring dial indicator is used to detect the change in the outer diameter of the nut being measured when the temperature returns from the required extreme temperature to room temperature. The raceway-measuring dial indicator is used to detect the change in the height of the top of the inner ball bearings of the raceway of the nut being measured when the temperature returns from the required extreme temperature to room temperature.

[0013] The nut pitch diameter at the extreme temperature is obtained by measuring the change in ball diameter as it returns to room temperature from the desired extreme temperature, along with the readings from the three dial indicators mentioned above.

[0014] A device for measuring the pitch diameter of a nut under extreme temperatures, and a method for measuring the pitch diameter of a nut under extreme temperatures.

[0015] S1: Provide the nut to be tested and the required extreme temperature T. cA hole is machined on the circumference of the nut to be tested, and the ball passes through the hole to contact the internal thread raceway; the corresponding ball is selected according to the nut to be tested;

[0016] S2: Place the nut to be tested on the nut placement platform, and adjust the positions of the testing bracket, dial indicator, insulation unit and thermometer according to the size of the nut to be tested;

[0017] S3: Heat or cool the nut and ball bearings under test so that their heating or cooling temperature exceeds or falls below the required limit temperature T. c This enables the thermometer to measure the required extreme temperature T. c value;

[0018] S4: Install the nut to be tested into place; at least one side of the hole on the circumference of the nut to be tested should face upwards; place the ball bearings on the raceway opposite the hole, at least two of them, to ensure that the top of the ball bearings of the insulation unit can be placed stably; press down the dial indicator to a sufficient amount to ensure that the dial indicator is still in contact with the insulation unit when the nut to be tested cools to room temperature;

[0019] S5: Monitor the measurement data of the thermometer and dial gauge until the temperature of the thermometer reaches the required limit temperature T. c At that moment, record the value of the dial gauge; record the value of the geodetic dial gauge at that moment as x1, the value of the top dial gauge at that moment as x2, and the value of the raceway dial gauge at that moment as x3.

[0020] S6: Continue monitoring the temperature of the thermometer. When the temperature returns to room temperature, record the reading of the dial gauge at that moment; record the value of the dial gauge at this moment as x. 10 The value of the dial gauge at this time is x. 20 The value of the dial indicator for the raceway is x at this time. 30 ;

[0021] S7: Remove the nut to be tested and measure its pitch diameter at room temperature, denoted as D. m0 ;

[0022] S8: Calculate the nut's mean diameter D at the corresponding extreme temperature using the following formula. m :

[0023] D m =D m0 +(x1-x 10 )+(x2-x 20 )-2(x3-x 30 )+ΔD b

[0024] Where, ΔD b D is the diameter of the ball. b The change in temperature is calculated using the following formula:

[0025] ΔD b =α l (T c -T0)D b

[0026] Where, α l T is the coefficient of thermal expansion of the ball bearing material. c The extreme temperature is T0, where T0 is the room temperature, and T0 = 20℃.

[0027] The significant advantages of this invention compared to existing technologies are:

[0028] This invention can test temperatures (T) that cannot be directly touched by the human hand. c ≤-5℃ or T c The mean diameter of nuts at ≥55℃ was calculated using the corresponding formula, ensuring accurate results and providing a basis for the design of nuts at the same extreme temperature. Attached Figure Description

[0029] Figure 1 A schematic diagram showing the nut placed in the testing apparatus for testing;

[0030] Figure 2 This is a schematic diagram of the nut placement platform;

[0031] Figure 3 This is a detailed diagram showing the detection location.

[0032] Symbol explanation:

[0033] 1. Testing base; 101. Platform; 102. Support rod; 103. Guide rod; 2. Nut placement platform; 201. Stop block; 3. Dial indicator; 301. Geometry dial indicator; 302. Top dial indicator; 303. Raceway dial indicator; 4. Guide cylinder; 5. Insulation rod; 6. Insulation block; 7. Ball bearing; 8. Thermometer; 9. Nut. Detailed Implementation

[0034] 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.

[0035] like Figure 1As shown, this invention provides a nut pitch diameter measuring device under extreme temperatures, comprising: a detection base 1, a nut placement platform 2, a dial indicator 3, a guide cylinder 4, a heat insulation rod 5, a heat insulation block 6, a ball bearing 7, and a thermometer 8. The detection base 1 consists of a detection platform 101 and a detection bracket, which is composed of no fewer than three support rods 102 and guide rods 103. The combination of three support rods and guide rods enables the most basic measurement of the pitch diameter of a nut raceway. To reduce measurement error, the pitch diameter of the nut can be measured at multiple locations and the average value taken; however, this requires a combination of more support rods and guide rods. Figure 1 , Figure 2 As shown, a nut placement platform 2 is mounted on platform 101. The nut placement platform 2 has at least one stop block 201 to limit the movement of the nut 9 to be tested. Platform 101 has multiple holes for mounting support rods 102, and the support rods 102 are installed at the selected holes according to the size of the nut 9. A guide rod 103 is connected to the support rod 102, and the position of the guide rod 103 is determined by the size of the nut 9. The length of the guide rod 103 is adjustable. A guide cylinder 4 is mounted on the guide rod 103. A clearance fit is made between the insulation rod 5 and the guide cylinder 4, allowing the insulation rod 5 to move smoothly within the guide cylinder 4. A dial indicator is connected to the insulation rod 5, and the dial indicator is mounted on a corresponding dial indicator base (not shown in the figure). A insulation block 6 is connected to the bottom of the insulation rod 5. The insulation rod 5 and the insulation block 6 have very low thermal elongation and thermal conductivity. The heat insulation block 6 is placed on the corresponding test object, and its placement is determined by the ground micrometer 301, the top micrometer 302, and the raceway micrometer 303, respectively. There are at least two ball bearings 7, the material and diameter of which are determined by the nut 9. The thermometer 8 is placed outside the testing base 1 and can measure the temperature at the contact point between the ball bearing 7 and the nut 9. The micrometer 3 and the thermometer 8 can continuously measure the corresponding data.

[0036] When using the technical solution of this invention, after placing the nut 9 on the nut placement platform 2 with heat-insulating gloves, the nut can be measured without direct contact with the nut by hand. When the nut is designed for working conditions with a temperature below -5℃ or above 55℃, this technical solution can be used to measure whether the nut's mean diameter meets the requirements at that temperature, so as to avoid failure to work properly.

[0037] Furthermore, platform 101 is made of cast iron, and the accuracy of this cast iron platform must be no less than grade 2. Using the technical solution of this invention, the cost of the cast iron platform is lower than that of a marble platform. The grade 2 platform accuracy ensures sufficient flatness, laying the foundation for accurate measurement of the nut's mean diameter.

[0038] Furthermore, the surface of the platform 101 is machined with multiple threaded holes according to certain rules. By employing the technical solution of this invention, the range of nut measurement can be increased, and different threaded holes can be selected to install the support rod 102 according to the size of the nut.

[0039] Furthermore, the nut placement platform 2 is made of marble. The accuracy of this marble platform must not be less than grade 2. By adopting the technical solution of this invention, the thermal stability of the device can be improved, deformation can be minimized, and the measurement error of the nut's mean diameter can be reduced.

[0040] Furthermore, such as Figure 2 As shown, the stop block 201 and the nut placement platform 2 are made of the same material and are integrally formed. Using the technical solution of this invention, the nut can be prevented from rolling on the platform. The integral forming process ensures thermal stability.

[0041] Furthermore, the guide cylinder 4 is made of polyetheretherketone (PEEK), which is heat-resistant, self-lubricating, and has a low coefficient of friction. Using the technical solution of this invention, the temperature-sensitive insulating rod can deform smoothly inside, preventing it from getting stuck and causing measurement errors.

[0042] Furthermore, the insulating rod 5 is made of ceramic. Ceramic materials have a low coefficient of thermal expansion and excellent thermal insulation performance. By adopting the technical solution of this invention, it can be ensured that the temperature cannot be conducted to the dial indicator probe during the measurement process, thereby protecting the probe and ensuring the accuracy of the measurement results.

[0043] Furthermore, the insulation block 6 is made of quartz glass. Quartz has a low thermal conductivity and its coefficient of thermal expansion is an order of magnitude smaller than that of ceramic materials, resulting in minimal dimensional changes due to temperature during testing. Therefore, the technical solution of this invention can reduce measurement errors.

[0044] Furthermore, the dial gauge and thermometer 8 can transmit data to the computer in real time, transferring and recording the measured data. By employing the technical solution of this invention, the temperature and dial gauge readings at every moment can be accurately obtained, ensuring the reliability of the data measurement.

[0045] Furthermore, the support rod 102 is threadedly connected to the platform 101. The technical solution of this invention facilitates quick installation and measurement based on the nut dimensions.

[0046] Furthermore, the guide rod 103 and the support rod 102 are connected by a locking mechanism. When the locking mechanism is released, the two are connected as a cylindrical pair, with two degrees of freedom (rotation and up / down sliding). After the position is adjusted, the locking mechanism is used to lock them, and the degrees of freedom are zero. By adopting the technical solution of this invention, the guide rod and support rod have high degrees of freedom and can be freely positioned within a wider range, thus expanding the range of measuring nuts.

[0047] Furthermore, the locking mechanism consists of at least one set screw. Using the technical solution of this invention, locking and unlocking can be performed quickly.

[0048] Furthermore, the connection between the guide cylinder 4 and the guide rod 103 is an interference fit connection. Using the technical solution of this invention facilitates the processing of the guide cylinder 4 and the guide rod 103 and simplifies assembly.

[0049] In addition, such as Figure 1 and Figure 3 As shown, the present invention also provides a method for measuring the mean diameter of a nut at extreme temperatures, comprising the following steps:

[0050] S1: Provide the nut 9 to be tested and the required extreme temperature. A hole is machined on the circumference of the nut 9, allowing contact with the internal thread raceway. Furthermore, the nut 9 is a ball nut, and even further, the return mechanism of the nut 9 is internal circulation, with a return valve hole already present on its circumference. Select the corresponding ball 7 based on the nut 9; Extreme temperature T. c The temperature that fingers should not touch for extended periods of time, generally within the range of: T c ≤-5℃ or T c ≥55℃;

[0051] S2: Place the nut 9 on the nut placement platform 2, and adjust the positions of the support rod 102, guide rod 103, dial indicator, insulation rod 5, insulation block 6 and thermometer 8 according to the size of the nut.

[0052] S3: When the extreme temperature T c When the temperature is ≤-5℃, place the nut 9 and ball bearing 7 in a refrigeration machine for cooling. The cooling temperature is higher than T. c The temperature should be low enough to ensure that the thermometer can measure the required temperature during the actual measurement. c Value; when the limiting temperature T c When the temperature is ≥55℃, place the nut 9 and ball bearing 7 into a heating machine for heating. The heating temperature is higher than T. c The temperature must be high enough to ensure that the thermometer can measure the required temperature during the actual measurement. c value;

[0053] S4: Remove nut 9 from the refrigeration / heating unit and quickly install it into place; furthermore, nut 9 has a flange, which is used to directly contact the nut placement platform for quick positioning; at least one side of the hole on the circumference of nut 9 faces upward; place at least two ball bearings 7 on the raceway opposite the hole to ensure that the heat insulation block can be placed stably on top of the ball bearings; press down the dial indicator to a sufficient amount to ensure that when nut 9 cools to room temperature, dial indicator 3 is still in contact with heat insulation rod 5;

[0054] S5: Monitor the measurement data of thermometer 8 and dial gauge, and wait for the temperature of thermometer 8 to reach the required limit temperature T. c At that moment, record the value of the dial gauge; record the value of the ground micrometer 301 as x1, the value of the top micrometer 302 as x2, and the value of the raceway micrometer 303 as x3.

[0055] S6: Continue monitoring the temperature of thermometer 8. When the temperature returns to room temperature, record the value of dial gauge 3 at that moment; record the value of dial gauge 301 at this moment as x. 10 The value of the dial gauge 302 at this time is x. 20 The value of dial indicator 303 on the raceway is x at this time. 30 ;

[0056] S7: Remove the nut and measure its pitch diameter at room temperature using a standard nut pitch diameter measurement method. Record this diameter as D. m0 ;

[0057] S8: Calculate the nut's mean diameter D at the corresponding extreme temperature using the following formula. m :

[0058] D m =D m0 +(x1-x 10 )+(x2-x 20 )-2(x3-x 30 )+ΔD b

[0059] Where, ΔD b The diameter D of ball 7 b The change in temperature is calculated using the following formula:

[0060] ΔD b =α l (T c -T0)D b

[0061] Where, α l T is the coefficient of thermal expansion of the material of the ball bearing 7. c The extreme temperature is T0, where T0 is the room temperature, typically T0 = 20℃.

[0062] Using the technical solution of this invention, the mean diameter of any type and function nut can be measured under extreme high or low temperature conditions. This provides a basis for designing nuts that can function normally under these extreme conditions.

Claims

1. A device for measuring the pitch diameter of a nut under extreme temperatures, characterized in that, include: The testing platform is used to fix the nut placement platform and multiple testing brackets; Nut placement platform, used to place and position the nut to be tested; The testing bracket is used to connect the insulation unit and adjust its position so that it comes into contact with the object being tested. The temperature insulation unit is in contact with the object being measured at its lower end and connected to a dial indicator at its upper end. A thermometer is used to detect the temperature at the contact point between the ball bearings inside the nut and the nut itself. The dial indicator includes a ground-measuring dial indicator, a top-measuring dial indicator, and a raceway-measuring dial indicator, which respectively contact the nut placement platform, the outer diameter of the nut being measured, and the inner ball bearings of the raceway of the nut being measured through corresponding heat insulation units. The ground-measuring dial indicator is used to detect the change in the surface height of the nut placement platform when the temperature returns from the required extreme temperature to room temperature. The top-measuring dial indicator is used to detect the change in the outer diameter of the nut being measured when the temperature returns from the required extreme temperature to room temperature. The raceway-measuring dial indicator is used to detect the change in the height of the top of the inner ball bearings of the raceway of the nut being measured when the temperature returns from the required extreme temperature to room temperature. The nut pitch diameter at the extreme temperature is obtained by measuring the change in ball diameter as it returns to room temperature from the desired extreme temperature, along with the readings from the three dial indicators mentioned above.

2. The nut pitch diameter measuring device under extreme temperatures according to claim 1, characterized in that, The detection bracket includes a support rod and a guide rod; The support rod is mounted on the nut placement platform, and the guide rod is connected to the support rod. The relative position of the two is adjustable, and the length of the guide rod is also adjustable.

3. The nut pitch diameter measuring device under extreme temperatures according to claim 2, characterized in that, The insulation unit includes an insulation rod and an insulation block, and a guide cylinder is installed on the guide rod; the insulation rod cooperates with the guide cylinder and can move inside the guide cylinder; a dial indicator is connected to the top of the insulation rod and the insulation block is connected to the bottom.

4. The nut pitch diameter measuring device under extreme temperatures according to claim 3, characterized in that, The material of the tube is polyetheretherketone.

5. The nut pitch diameter measuring device under extreme temperatures according to claim 3, characterized in that, The insulation rod is made of ceramic, and the insulation block is made of quartz glass.

6. The nut pitch diameter measuring device under extreme temperatures according to claim 1, characterized in that, The testing platform is made of cast iron and its precision level must be no less than 2.

7. The nut pitch diameter measuring device under extreme temperatures according to claim 1, characterized in that, The nut placement platform is made of marble and its precision must be no less than grade 2.

8. The nut pitch diameter measuring device under extreme temperatures according to claim 2, characterized in that, The guide rod and the support rod are connected by a locking mechanism. When the locking mechanism is released, the two are connected as a cylindrical pair with two degrees of freedom. After the position is adjusted, the locking mechanism is used to lock them, and the degrees of freedom are zero.

9. The nut pitch diameter measuring device under extreme temperatures according to claim 8, characterized in that, The locking mechanism consists of at least one set screw.

10. The nut pitch diameter measuring device under extreme temperatures according to any one of claims 1-9, and the method for measuring the pitch diameter of a nut under extreme temperatures, characterized in that, S1: providing a measured nut and a required limit temperature T c , a hole is processed on the circumference of the measured nut, and the inner thread raceway is contacted through the hole; according to the measured nut, a corresponding ball is selected; S2: Place the nut to be tested on the nut placement platform, and adjust the positions of the testing bracket, dial indicator, insulation unit and thermometer according to the size of the nut to be tested; S3: heating or cooling the measured nut and the ball so that the heating or cooling temperature of the measured nut and the ball exceeds or is lower than the required limit temperature T c so that the temperature measuring instrument can measure the required limit temperature T c value; S4: Install the nut to be tested into place; at least one side of the hole on the circumference of the nut to be tested should face upwards; place the ball bearings on the raceway opposite the hole, at least two of them, to ensure that the top of the ball bearings of the insulation unit can be placed stably; press down the dial indicator to a sufficient amount to ensure that the dial indicator is still in contact with the insulation unit when the nut to be tested cools to room temperature; S5: Monitor the measurement data of the thermometer and dial gauge until the temperature of the thermometer reaches the required limit temperature T. c At that moment, record the value of the dial gauge; record the value of the geodetic dial gauge at that moment as x1, the value of the top dial gauge at that moment as x2, and the value of the raceway dial gauge at that moment as x3. S6: Continue monitoring the temperature of the thermometer. When the temperature returns to room temperature, record the reading of the dial gauge at that moment; record the value of the dial gauge at this moment as x. 10 The value of the dial gauge at this time is x. 20 The value of the dial indicator for the raceway is x at this time. 30 ; S7: Remove the nut to be tested and measure its pitch diameter at room temperature, denoted as D. m0 ; S8: Calculate the nut's mean diameter D at the corresponding extreme temperature using the following formula. m : D m =D m0 +(x1-x 10 )+(x2-x 20 )-2(x3-x 30 )+ΔD b Where, ΔD b D is the diameter of the ball. b The change in temperature is calculated using the following formula: ΔD b =α l (T c -T0)D b Where, α l T is the coefficient of thermal expansion of the ball bearing material. c The extreme temperature is T0, where T0 is the room temperature, and T0 = 20℃.

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