Method and device for measuring pitch diameter of nut at limiting temperature

Abstract

The invention provides a method and a device for measuring the pitch diameter of a nut at a limiting temperature. The measuring device comprises a detection base, a nut placement table, a dial indicator, a guide cylinder, a thermal insulation rod, a thermal insulation block, a ball and a thermodetector. The measuring method comprises the following steps: providing a to-be-measured nut and a required limiting temperature, and selecting a corresponding ball according to the nut; a nut is placed on the nut placing table, and the measuring device is adjusted according to the size of the nut. The temperature of the nut is set to a proper temperature through the heating / cooling machine, then the nut is taken out and rapidly installed in the measuring device, the temperature is monitored through the thermodetector, and when the temperature of the nut reaches the required limit temperature, the measuring result of each dial indicator is recorded. And measuring the pitch diameter value at the room temperature, and calculating to obtain the pitch diameter value at the limiting temperature. According to the technical scheme, the problems that the pitch diameter of the nut is difficult to measure and inaccurate in measurement at the limiting temperature are solved.

Description

Technical Field

[0001] The invention belongs to the field of nut measurement, in particular to a method and a device for measuring a nut center diameter at an extreme temperature. Background Art

[0002] Nuts are key components in mechanical transmission systems and are often used in conjunction with bolts or lead screws to connect or fix various parts. Nuts mesh with the outer threads of bolts or lead screws through internal threads to achieve precise axial movement and positioning. Nuts used in conjunction with bolts are also called nuts, and the internal thread raceway is often a triangular thread. Nuts used in conjunction with lead screws have different normal sections of internal threads due to different forms of cooperation with the lead screw. When the nut and the lead screw are directly matched with a spiral pair to form a spiral sliding transmission, the internal thread will use a rectangular thread, a trapezoidal thread or a serrated thread; when a ball is inserted between the nut and the lead screw to form a rolling spiral pair, the nut is also called a ball nut, and the normal section of its internal thread is often a single arc or a Gothic double arc; when a planetary roller is used as an intermediate between the nut and the lead screw. At this time, the nut is called a roller nut, and the normal section of its internal thread is often similar to the tooth shape of a gear. Regardless of which of the above nuts, they all have a very important thread geometry parameter, the median diameter. The pitch diameter is located between the crest and the bottom of the thread and is the key dimension that determines the fit and strength of the thread. The pitch diameter of the nut plays a vital role in thread design and application. It affects the fit, force conditions and overall performance of the connection. Correct design and control of the pitch diameter of the nut can ensure the safety, reliability and durability of the threaded connection.

[0003] The conventional method for measuring the middle diameter of a nut is to first measure the outer diameter of the nut, then put a corresponding ball into the raceway, use a micrometer to measure the distance from the ball to the surface of the ball to the outer circle of the nut, and then calculate the middle diameter of the nut. Of course, with the development of technology, some new types of nut middle diameter measuring equipment have been developed, such as a ball nut middle diameter measuring structure (CN208349988U), a heavy-duty nut middle diameter measuring gauge (CN207600352U), etc. These devices improve the measurement efficiency of the nut middle diameter, but can only measure the nut middle diameter at room temperature. Because in these measurement methods, the human hand needs to directly contact the nut, when the temperature is lower than -5°C or higher than 55°C, even a short-term contact will cause damage to the skin on the surface of the human body. In addition, direct contact between the measuring tool and the extreme temperature will also cause inaccurate measurement results and even damage to the measuring tool.

[0004] However, with the development of science and technology, nuts are increasingly used at extreme temperatures. For example, various nuts are used in cars working outdoors in Northeast China and Xinjiang, in nuclear power plant drive mechanisms, and in various mechanisms in the aerospace field. In order to achieve the best performance of the nut at the corresponding extreme temperature, it is necessary to know the middle diameter of the nut at the corresponding temperature in order to better guide the design. Therefore, it is very necessary to invent a method and device for measuring the middle diameter of a nut at extreme temperature. Summary of the invention

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

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A testing platform for fixing a nut placement table and multiple testing brackets;

[0008] A nut placement table, used to place and position the nut to be tested;

[0009] A detection bracket is used to connect the temperature insulation unit and adjust the position of the temperature insulation unit so that the temperature insulation unit contacts the object to be tested;

[0010] The temperature-isolating unit has a lower end in contact with the object to be measured and a micrometer connected to the upper end;

[0011] Thermometer, used to detect the temperature of the contact point between the ball inside the nut and the nut;

[0012] The micrometers include a geodetic micrometer, a top micrometer and a raceway micrometer, which are in contact with the nut placement table, the outer circle of the nut to be measured and the ball in the raceway of the nut to be measured through corresponding temperature insulation units respectively; the geodetic micrometer is used to detect the change in surface height of the nut placement table when the temperature returns from the required extreme temperature to room temperature, the top micrometer is used to detect the change in outer diameter of the nut to be measured when the temperature returns from the required extreme temperature to room temperature, and the raceway micrometer is used to detect the change in height of the top of the ball in the raceway of the nut to be measured when the temperature returns from the required extreme temperature to room temperature;

[0013] The nut median diameter at the extreme temperature is obtained by detecting the change in the ball diameter when it returns to room temperature from the required extreme temperature and the detection values ​​of the above three micrometers.

[0014] A device for measuring the middle diameter of a nut at an extreme temperature, and a method for measuring the middle diameter of a nut at an extreme temperature.

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

[0016] S2: placing the nut to be tested on a nut placement table, and adjusting the positions of the testing bracket, the micrometer, the temperature isolation unit, and the thermometer according to the size of the nut to be tested;

[0017] S3: Heating or cooling the nut and ball under test so that the heating or cooling temperature of the nut and ball under test exceeds or falls below the required limit temperature T c , so that the thermometer can measure the required limit temperature T c value;

[0018] S4: Install the nut to be tested in place; at least one of the holes on the circumference of the nut to be tested faces upward; place the balls on the raceway opposite the hole, at least two balls, to ensure that the top of the balls of the insulation unit can be placed stably; press down the micrometer by a sufficient amount to ensure that the micrometer 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 the dial gauge, and wait for the temperature of the thermometer to reach the required limit temperature T c When the micrometer is at x, record the value of the micrometer at that moment; record the value of the micrometer at this moment as x 1 , the value of the top micrometer at this time is x 2 The value of the micrometer measuring the rolling track is x 3 ;

[0020] S6: Continue to monitor the temperature of the thermometer. When the temperature reaches room temperature, record the value of the micrometer at that moment. The value of the micrometer at this moment is x 10 , the value of the top micrometer at this time is x 20 , the value of the micrometer of the rolling track is x 30 ;

[0021] S7: Take out the nut to be tested and measure the median diameter of the nut at room temperature, which is recorded as D m0 ;

[0022] S8: Calculate the nut diameter D at the corresponding limit temperature using the following formula m :

[0023] D m =D m0 +(x 1 -x 10 )+(x 2 -x 20 )-2(x 3 -x 30 )+ΔD b

[0024] Where, ΔD b D is the diameter of the ball b The change affected by temperature is calculated as follows:

[0025] ΔD b =α l (T c -T 0 )D b

[0026] Among them, α l is the thermal expansion coefficient of the ball material, T c is the limit temperature, T 0 is the room temperature, take T 0 =20℃.

[0027] Compared with the prior art, the present invention has the following significant advantages:

[0028] The present invention can test the temperature that cannot be directly touched by human hands (T c ≤-5℃ or T c The median diameter of the nut at ≥55℃ is calculated by the corresponding calculation formula to ensure the accuracy of the result, which can provide a basis for the subsequent design of nuts under the same extreme temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the nut being placed on the test device for testing;

[0030] Figure 2 A schematic diagram of the nut placement platform;

[0031] Figure 3 Shows the details of the detection location.

[0032] Explanation of symbols:

[0033] 1. Detection base; 101. Platform; 102. Support rod; 103. Guide rod; 2. Nut placing table; 201. Stop block; 3. Micrometer; 301. Geodetic micrometer; 302. Top micrometer; 303. Track micrometer; 4. Guide cylinder; 5. Insulation rod; 6. Insulation block; 7. Ball; 8. Thermometer; 9. Nut. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figure 1 As shown, the present invention provides a device for measuring the middle diameter of a nut under extreme temperatures, including: a detection base 1, a nut placement table 2, a micrometer 3, a guide cylinder 4, a thermal insulation rod 5, a thermal insulation block 6, a ball 7, and a thermometer 8. The detection base 1 is composed of a detection platform 101 and a detection bracket, and the detection bracket is composed of no less than 3 support rods 102 and a guide rod 103. The combination of 3 support rods and guide rods can realize the most basic detection of the middle diameter of a nut raceway. In order to reduce the measurement error, the middle diameter of the nut at multiple positions can be measured and the average value can be taken, so more support rod and guide rod combinations are needed. As Figure 1 , Figure 2 As shown, the nut placement platform 2 is installed on the platform 101, and the nut placement platform 2 has at least one stop block 201 to limit the nut 9 to be tested. The platform 101 has multiple holes for the support rod 102 to be installed, and the support rod 102 is installed in the hole selected according to the size of the nut 9. The 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 can be adjusted. The guide cylinder 4 is installed on the guide rod 103. There is a clearance fit between the insulation rod 5 and the guide cylinder 4, and the insulation rod 5 can move smoothly in the guide cylinder 4. A micrometer is connected to the insulation rod 5, and the micrometer is installed on the corresponding micrometer base (not shown in the figure). The insulation rod 5 is connected to the insulation block 6 below, and the thermal elongation coefficient and thermal conductivity of the insulation rod 5 and the insulation block 6 are very low. The insulation block 6 is placed on the corresponding test object, and the placement position is determined by the geodetic micrometer 301, the top micrometer 302 and the raceway micrometer 303. There are no less than 2 balls 7, and the material and diameter of the balls 7 are determined by the nuts 9. The thermometer 8 is placed outside the detection base 1, and can measure the temperature of the contact between the balls 7 and the nuts 9. The micrometer 3 and the thermometer 8 can measure the corresponding data at any time.

[0036] By adopting the technical solution of the present invention, when in use, after placing the nut 9 on the nut placing table 2 with temperature-insulating gloves, there is no need to directly touch the nut with hands during measurement. When the nut is designed to be under working conditions with a temperature lower than -5°C or higher than 55°C, the present technical solution can be used to measure whether the middle diameter of the nut at this temperature meets the requirements to avoid abnormal operation.

[0037] Furthermore, the material of the platform 101 is cast iron, and the accuracy of the cast iron platform shall not be less than level 2. By adopting the technical solution of the present invention, the cost of the cast iron platform is lower than that of the marble platform. The level 2 platform accuracy can ensure sufficient flatness, laying the foundation for accurately measuring the nut mid-diameter.

[0038] Furthermore, a plurality of threaded holes are processed on the surface of the platform 101 according to certain rules. By adopting the technical solution of the present invention, the range of measuring nuts 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 material of the nut placement platform 2 is marble. The accuracy of the marble platform shall not be less than level 2. The technical solution of the present invention can improve the thermal stability of the device, reduce deformation, and reduce the measurement error of the nut center diameter measurement.

[0040] Furthermore, if Figure 2 As shown, the stopper 201 is made of the same material as the nut placement platform 2 and is integrally formed. The technical solution of the present invention can prevent the nut from rolling on the platform. The integral forming can ensure thermal stability.

[0041] Furthermore, the guide tube 4 is made of polyetheretherketone (PEEK), which is resistant to high temperatures, self-lubricating, and has a low friction coefficient. The technical solution of the present invention allows the temperature-insulating rod that is deformed by temperature to deform smoothly inside the guide tube 4 without getting stuck and causing measurement errors.

[0042] Furthermore, the material of the thermal insulation rod 5 is ceramic. Ceramic materials have a low thermal expansion coefficient and excellent thermal insulation performance. The technical solution of the present invention can ensure that the temperature cannot be transmitted to the probe of the micrometer during the measurement process, thereby protecting the probe and ensuring the accuracy of the measurement result.

[0043] Furthermore, the material of the insulation block 6 is quartz glass. The thermal conductivity of quartz material is low, and the thermal expansion coefficient is one order of magnitude smaller than that of ceramic material. During the test, the size is less affected by temperature. Therefore, the technical solution of the present invention can reduce the measurement error.

[0044] Furthermore, the dial gauge and the thermometer 8 can transmit data to the computer at any time, and the measured data can be transmitted to the computer and recorded. By adopting the technical solution of the present invention, the temperature and dial gauge value at each moment can be accurately obtained, and the reliability of data measurement can be ensured.

[0045] Furthermore, the support rod 102 is threadedly connected to the platform 101. The technical solution of the present invention is adopted to facilitate rapid installation and measurement according to the size of the nut.

[0046] Furthermore, the guide rod 103 is connected to the support rod 102 by a locking mechanism. When the locking mechanism is unlocked, the two are connected in a cylindrical pair, with two degrees of freedom (rotation and up and down sliding). After the position is adjusted, the locking mechanism is used to lock it, and the degree of freedom is zero. With the technical solution of the present invention, the guide rod and the support rod have high degrees of freedom, and can be freely positioned in a larger range, thereby expanding the range of measuring nuts.

[0047] Furthermore, the locking mechanism is composed of no less than one set screw. The technical solution of the present invention can be used to quickly lock and unlock.

[0048] Furthermore, the connection between the guide cylinder 4 and the guide rod 103 is an interference fit connection. The technical solution of the present invention is advantageous for the processing of the guide cylinder 4 and the guide rod 103, and the assembly is simple.

[0049] In addition, if Figure 1 and Figure 3 As shown, the present invention also provides a method for measuring the middle diameter of a nut at an extreme temperature, comprising the following steps:

[0050] S1: Provide the nut 9 to be tested and the required limit temperature. A hole is machined on the circumference of the nut 9, through which the internal thread raceway can be contacted. Furthermore, the nut 9 is a ball nut. Furthermore, the return form of the nut 9 is an internal circulation, and there is a return device hole on the circumference of the nut. Select the corresponding ball 7 according to the nut 9; the limit temperature T c Refers to the temperature that fingers cannot touch for a long time, the general range is: T c ≤-5℃ or T c ≥55℃;

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

[0052] S3: When the limit temperature T c ≤-5℃, put the nut 9 and the ball 7 into the refrigerator for cooling. The cooling temperature is higher than T c To ensure that the thermometer 8 can measure the required T during formal measurement. c Value; when the limit temperature T c ≥55℃, put the nut 9 and the ball 7 into the heating machine for heating, and the heating temperature is higher than T c It should be high to ensure that the thermometer 8 can measure the required T during formal measurement. c value;

[0053] S4: Take out the nut 9 from the refrigeration / heating machine and quickly install it in place; further, the nut 9 has a flange, and the flange is used to directly contact the nut placement table for rapid positioning; at least one of the holes on the circumference of the nut 9 faces upward; put the ball 7 on the raceway opposite the hole, at least two balls, to ensure that the insulation block can be stably placed on the top of the ball; press down the micrometer by a sufficient amount to ensure that when the nut 9 cools to room temperature, the micrometer 3 is still in contact with the insulation rod 5;

[0054] S5: Monitor the measurement data of the thermometer 8 and the dial gauge, and wait until the temperature of the thermometer 8 reaches the required limit temperature Tc When the value of the micrometer at that moment is recorded, the value of the micrometer 301 at that moment is x 1 , the value of the top micrometer 302 at this time is x 2 , the value of the rolling track micrometer 303 at this time is x 3 .

[0055] S6: Continue to monitor the temperature of the thermometer 8. When the temperature reaches room temperature, record the value of the micrometer 3 at that moment; record the value of the micrometer 301 at that moment as x 10 , the value of the top micrometer 302 at this time is x 20 , the value of the rolling track micrometer 303 at this time is x 30 ;

[0056] S7: Take out the nut and use the conventional nut diameter measurement method to measure the nut diameter at room temperature, which is recorded as D m0 ;

[0057] S8: Calculate the nut diameter D at the corresponding limit temperature using the following formula m :

[0058] D m =D m0 +(x 1 -x 10 )+(x 2 -x 20 )-2(x 3 -x 30 )+ΔD b

[0059] Where, ΔD b is the diameter D of ball 7 b The change affected by temperature is calculated as follows:

[0060] ΔD b =α l (T c -T 0 )D b

[0061] Among them, α l is the thermal expansion coefficient of the material of the ball 7, T c is the limit temperature, T 0 is the room temperature, usually T 0 =20℃.

[0062] By adopting the technical solution of the present invention, the median diameter value of nuts of any function and any model under extreme high temperature or extreme low temperature conditions can be measured, providing a basis for designing nuts that can work normally under these extreme working conditions.

Claims

1. A device for measuring the mid-diameter of a nut at an extreme temperature, characterized in that: include: A testing platform for fixing a nut placement table and multiple testing brackets; A nut placement table, used to place and position the nut to be tested; A detection bracket is used to connect the temperature insulation unit and adjust the position of the temperature insulation unit so that the temperature insulation unit contacts the object to be tested; The temperature-isolating unit has a lower end in contact with the object to be measured and a micrometer connected to the upper end; Thermometer, used to detect the temperature of the contact point between the ball inside the nut and the nut; The micrometers include a geodetic micrometer, a top micrometer and a raceway micrometer, which are in contact with the nut placement table, the outer circle of the nut to be measured and the ball in the raceway of the nut to be measured through corresponding temperature insulation units respectively; the geodetic micrometer is used to detect the change in surface height of the nut placement table when the temperature returns from the required extreme temperature to room temperature, the top micrometer is used to detect the change in outer diameter of the nut to be measured when the temperature returns from the required extreme temperature to room temperature, and the raceway micrometer is used to detect the change in height of the top of the ball in the raceway of the nut to be measured when the temperature returns from the required extreme temperature to room temperature; The nut median diameter at the extreme temperature is obtained by detecting the change in the ball diameter when it returns to room temperature from the required extreme temperature and the detection values ​​of the above three micrometers.

2. The device for measuring the nut median diameter at extreme temperature according to claim 1, characterized in that: The detection bracket includes support and guide rods; The support rod is installed on the nut placement platform, and the guide rod is connected to the support rod, and the relative positions of the two are adjustable, and the length of the guide rod is adjustable.

3. The device for measuring the nut median diameter at extreme temperature according to claim 2, characterized in that: The thermal insulation unit comprises a thermal insulation rod and a thermal insulation block, and the guide cylinder is installed on the guide rod; the thermal insulation rod cooperates with the guide cylinder and can move inside the guide cylinder; the thermal insulation rod is connected to a micrometer on the top and to a thermal insulation block on the bottom.

4. The device for measuring the nut median diameter at extreme temperature according to claim 3, characterized in that: The material of the guide tube is polyetheretherketone.

5. The device for measuring the nut median diameter at extreme temperature according to claim 3, characterized in that: The material of the thermal insulation rod is ceramic, and the material of the thermal insulation block is quartz glass.

6. The device for measuring the nut median diameter at extreme temperature according to claim 1, characterized in that: The material of the detection platform is cast iron and the accuracy shall not be less than grade 2.

7. The device for measuring the nut median diameter at extreme temperature according to claim 1, characterized in that: The nut placing table is made of marble and its precision shall not be less than grade 2.

8. The device for measuring the nut median diameter at extreme temperature 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 unlocked, the two are connected in a cylindrical pair and have two degrees of freedom. After the position is adjusted, the locking mechanism is used to lock them and the degree of freedom is zero.

9. The device for measuring the nut median diameter at extreme temperature according to claim 8, characterized in that: The locking mechanism is composed of no less than one set screw.

10. The device for measuring the middle diameter of a nut at an extreme temperature according to any one of claims 1 to 9, which is used for detecting a method for measuring the middle diameter of a nut at an extreme temperature, characterized in that: S1: Provide the nut to be tested and the required limit temperature T c , a hole is machined on the circumference of the nut to be tested, and the hole is passed through to contact the internal thread raceway; and a corresponding ball is selected according to the nut to be tested; S2: placing the nut to be tested on a nut placement table, and adjusting the positions of the testing bracket, the micrometer, the temperature isolation unit, and the thermometer according to the size of the nut to be tested; S3: Heating or cooling the nut and ball under test so that the heating or cooling temperature of the nut and ball under test exceeds or falls below the required limit temperature T c , so that the thermometer can measure the required limit temperature T c value; S4: Install the nut to be tested in place; at least one of the holes on the circumference of the nut to be tested faces upward; place the balls on the raceway opposite the hole, at least two balls, to ensure that the top of the balls of the insulation unit can be placed stably; press down the micrometer by a sufficient amount to ensure that the micrometer 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 the micrometer, and wait for the temperature of the thermometer to reach the required limit temperature T c When the value of the micrometer at that moment is recorded; the value of the ground micrometer at that moment is x1, the value of the top micrometer at that moment is x2, and the value of the raceway micrometer at that moment is x3; S6: Continue to monitor the temperature of the thermometer. When the temperature reaches room temperature, record the value of the micrometer at that moment. The value of the micrometer at this moment is x 10 , the value of the top micrometer at this time is x 20 , the value of the micrometer of the rolling track is x 30 ; S7: Take out the nut to be tested and measure the median diameter of the nut at room temperature, which is recorded as D m0 ; S8: Calculate the nut diameter D at the corresponding limit 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 affected by temperature is calculated as follows: ΔD b =α l (T c -T0)D b Among them, α l is the thermal expansion coefficient of the ball material, T c is the limit temperature, T0 is the room temperature, and T0=20℃.

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