Double-needle thermocouple temperature measuring device adaptable to multi-degree-of-freedom body deformation and its use method

Abstract

This invention provides a dual-needle thermocouple temperature measuring device and its method of use for adapting to deformation of a multi-degree-of-freedom body. The device includes a thermocouple, a thermocouple clamp, a housing, a slider, a fixing block, a stop lock, a swing block, and a spring. The threaded hole of the slider is connected to the connecting cylinder of the thermocouple clamp. The fixed end of the thermocouple is connected to the first cylindrical hole in the thermocouple clamp. The input ends of the first and second thermocouples are connected to the positive and negative poles, respectively. The mounting end of the swing block is connected to the first end of the first return spring, and the second end of the first return spring is connected to the second cylindrical hole in the thermocouple clamp. The fixing end of the stop lock is connected to the mounting end of the thermocouple. The first end of the rectangular spring is connected to the first fixing groove of the slider, and the second end of the rectangular spring is connected to the second fixing groove of the fixing block. A positioning spring is connected to a positioning ball. This invention can test the temperature of a thermoformed specimen and can compensate for displacement during large deformation of the thermoformed specimen, thus improving the accuracy of the temperature test.

Description

Technical Field

[0001] This invention relates to the field of dual-needle thermocouple temperature measurement, and particularly to a dual-needle thermocouple temperature measurement device with multi-degree-of-freedom body deformation adaptability and its usage method. Background Technology

[0002] When testing the thermoforming performance of specimens, the accuracy and control of temperature testing are very important. Temperature is usually measured by using a thermocouple as the temperature sensing element. By applying pressure to the two terminals of the thermocouple, the rectangular springs attached to the two terminals are deformed, thereby achieving full contact and directly measuring the temperature. The temperature signal is then converted into a thermoelectric potential signal, which is then converted into the temperature of the measured medium by an electrical instrument (secondary instrument).

[0003] In the processing of sheet and block metals through cold or hot deformation, temperature monitoring during deformation is essential. In experiments, a double-needle thermocouple is typically used for contact temperature measurement to accurately obtain the voltage between two measured points. Because this thermocouple has an open-circuit design, manual pressure must be applied to the two terminals of the thermocouple during contact temperature measurement to achieve full contact and thus measure the temperature. However, in conventional temperature measurement, manual pressure cannot maintain constant contact pressure, introducing a pressure variable. When the deformation of the specimen is large or the deformed area is made of dissimilar materials, the temperature test results will deviate, reducing temperature control accuracy and affecting the testing of the specimen's thermoforming properties.

[0004] To address the aforementioned problems, this invention presents a multi-degree-of-freedom deformation-adaptive dual-needle thermocouple temperature measuring device capable of compensating for large deformation displacements and accurately testing the temperature of large deformation specimens. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device and its usage method. The dual-needle thermocouple in this device possesses both rotational and translational degrees of freedom, enabling it to compensate for large deformation displacements of the specimen. This allows for more precise temperature measurement during body thermal deformation. The device primarily utilizes a first return spring, a locking mechanism, and a swing block in the rotating assembly, as well as a fixed block, a slider, and a rectangular spring in the translational assembly. This allows the thermocouple to move with the large deformation of the specimen, ensuring continuous contact between the thermocouple and the specimen. By adjusting the fixed block and slider in the translational assembly, along with a positioning ball, the position and preload of the rectangular spring are adjusted, creating an adjustable initial contact pressure between the thermocouple and the specimen. This allows the thermocouple to move with the large deformation of the specimen without changing the measuring point, thereby improving the accuracy of temperature control during deformation.

[0006] This invention provides a multi-degree-of-freedom deformable dual-needle thermocouple temperature measuring device, comprising a thermocouple, a thermocouple clamp, a housing, a slider, a rectangular spring, a fixing block, a stop lock, a swing block, a return spring, a spring column, a protective cylinder, a magnet, a positioning spring, a positioning ball, and a sleeve. The first end of the thermocouple clamp is a connecting cylinder with a second fixing hole inside. The second end of the thermocouple clamp is a U-shaped plug with symmetrical cylindrical holes on both sides. The slider has a first threaded hole at its center, with a hexagonal nut groove and a circular groove on either side. The slider has a first fixing hole on one side inside and a first fixing groove on one side outside. The fixing block has a protective cylindrical hole in its center, with a second fixing groove and a moving hole at its upper and lower ends. The fixing block has a second positioning hole and a placement hole on both sides of its center. The fixed end of the thermocouple is connected to the first end of the first cylindrical hole on the U-shaped plug in the thermocouple clamp. The first mounting end of the swing block is connected to the second end of the first cylindrical hole on the U-shaped plug in the thermocouple clamp. The input ends of the first thermocouple and the second thermocouple are connected to the positive and negative wires, respectively. The second mounting end of the swing block is connected to the first end of the first return spring. The second end of the first return spring is connected to the second cylindrical hole of the U-shaped plug in the thermocouple clamp through a spring post. The fixed end of the stop lock is connected to the mounting end of the thermocouple. The movable end of the stop lock contacts the swing block. The swing block realizes the reset of the double-needle thermocouple temperature measuring device. The sliding end of the connecting cylinder of the thermocouple clamp contacts the slide rail. The first threaded hole of the slider is connected to the fixed end of the connecting cylinder of the thermocouple clamp. The first end of the rectangular spring is connected to the first fixed groove of the slider. The second end of the rectangular spring is connected to the second fixed groove of the fixed block. The positioning spring is connected to the positioning ball. The first end of the protective cylinder is located inside the rectangular spring. The second end of the protective cylinder passes through the protective cylinder hole and is connected to the sleeve. The degree of freedom of the device is realized by adjusting the distance between the slide rail and the first positioning hole to change the compression of the rectangular spring and to give the thermocouple an initial contact pressure.

[0007] Preferably, the second return spring is located in the circular groove of the slider, the first hexagonal nut is located in the hexagonal nut groove of the slider, the two ends of the second return spring are respectively connected to the first fixing hole and the second fixing hole, the sleeve is located in the moving hole of the fixing block, the mounting end of the sleeve is connected to the magnet, the positioning spring is located inside the sleeve, the positioning ball is located between the second positioning hole of the fixing block and the first positioning hole on the outer shell, and the magnet is located in the placement hole of the fixing block.

[0008] Preferably, the U-shaped plug of the thermocouple clamp, the first return spring, the spring post, the stop lock, and the swing block constitute a rotating assembly.

[0009] Preferably, the slider, the connecting cylinder of the thermocouple clamp, the rectangular spring, the second return spring, the fixing block, the positioning spring, the positioning ball, the protective cylinder, and the sleeve constitute a translational assembly; the axes of the rectangular spring, the first fixing groove of the slider, the second fixing groove of the fixing block, and the protective cylinder are on the same straight line.

[0010] Preferably, the translational components are symmetrically distributed inside the housing, and the rotational components are symmetrically distributed outside the housing.

[0011] Preferably, in the horizontal direction of the translational assembly, the expression for the distance the slider moves towards the rectangular spring is:

[0012]

[0013] Δs 1max ≤L1

[0014] Where s0 is the vertical distance from the head of the double-needle thermocouple to the center point of the slider, s1' is the vertical distance from the head of the thermocouple to the center point of the slider when the slider moves towards the rectangular spring, Δs1 is the distance the slider moves backward, r0 is the straight-line length of the thermocouple needle from the center of the thermocouple clamp to the needle head, l0 is the vertical distance between the thermocouple needle head and the upper part of the thermocouple, l1' is the distance the thermocouple needle head moves upward, and Δs 1max L1 is the maximum distance the slider moves backward, and L2 is the distance between the center of the connecting cylinder sliding end and the end of the slide.

[0015] When l1' < l0, the slider moves away from the rectangular spring; when l1' = l0, the slider moves to its maximum distance. When l1' > l0, the slider moves back towards the rectangular spring.

[0016] The expression for the distance the slider moves away from the rectangular spring is:

[0017]

[0018] Δs 2max ≤L2

[0019] Where s0 is the vertical distance from the thermocouple head to the center point of the slider, s2' is the vertical distance from the thermocouple needle head to the center point of the slider when the slider moves away from the rectangular spring, Δs2 is the distance the slider moves forward, r0 is the straight-line length from the center of the thermocouple clamp to the thermocouple needle head, l0 is the vertical distance between the thermocouple needle head and the upper part of the thermocouple, l2' is the distance the thermocouple needle head moves downward, and Δs 2max L1 represents the maximum distance the slider can move forward, and L2 represents the distance between the center of the connecting cylinder's sliding end and the front end of the slide.

[0020] Due to the limitation of the slide length, the distance Δs2 ≤ L2 that the slider moves away from the rectangular spring is limited. max =s 1max -s 2max Δs max This represents the maximum distance the slider can move.

[0021] Preferably, in the rotation direction of the rotating assembly, to prevent the thermocouple from interfering with the outer casing, the angle α through which the thermocouple rotates is less than the friction angle β. The specific relationship is expressed as follows:

[0022] α < β

[0023]

[0024] L'>L

[0025] Where α is the angle through which the thermocouple rotates, β is the friction angle, r0 is the straight-line length of the thermocouple needle from the center of the thermocouple clamp to the needle head, l0 is the vertical distance between the thermocouple needle head and the upper part of the thermocouple, l2' is the distance the thermocouple needle head moves downward, L' is part of the length of the double-needle thermocouple, and L is the movable distance of the slider on the slide.

[0026] Preferably, the first end, the second end, and the third end of the outer casing are respectively provided with a second threaded hole, a first positioning hole, and a slide rail, and the first threaded hole, the first positioning hole, and the slide rail are symmetrically distributed on both sides of the outer casing.

[0027] In another aspect, the present invention provides a method of using a dual-needle thermocouple temperature measuring device that adapts to the deformation of a multi-degree-of-freedom body, comprising the following steps:

[0028] S1. Assemble the rotating assembly: Fix the thermocouple and the swing block to the thermocouple clamp in sequence, fix the stop lock to the thermocouple, and install the first return spring between the swing block and the U-shaped plug of the thermocouple clamp.

[0029] S2. Assemble the translational components: Install the magnet, positioning spring, sleeve and positioning ball on the fixed block in sequence. Then install the rectangular spring between the fixed block and the slider. Place the protective cylinder inside the rectangular spring. Place the second reset spring between the first fixing hole of the slider and the second fixing hole of the thermocouple clamp with screws. Use the first reset spring and the second reset spring to bring the first thermocouple and the second thermocouple to the initial state.

[0030] S3. Install the double-needle thermocouple temperature measuring device in a suitable position on the experimental machine through the second threaded hole of the outer shell. Connect the measuring ends of the first thermocouple and the second thermocouple to the large deformation specimen respectively. Adjust the horizontal movement distance of the thermocouple by changing the position of the positioning ball in the first positioning hole and the position of the slider. Adjust the rotation angle of the thermocouple by adjusting the angle of the swing block relative to the thermocouple clamp, so that the double-needle thermocouple temperature measuring device fits the large deformation specimen better.

[0031] S4. Connect the first thermocouple connected to the positive line and the second thermocouple connected to the negative line respectively, apply a certain test force to the large deformation specimen and conduct the test. During the test, the first thermocouple and the second thermocouple are attached to the large deformation specimen and move with the deformation of the large deformation specimen. Continuously measure the temperature of the large deformation specimen during hot deformation and record the temperature data between the two sides.

[0032] Preferably, during operation, the thermocouple in the temperature measuring device needs to ensure that the length of the protective cylinder meets the following conditions:

[0033]

[0034] Among them, F I L is the maximum force that the thermocouple can withstand. k Let L be the length of the rectangular spring. y To protect the length of the cylinder and thus prevent bending damage.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. The temperature measuring device of the present invention uses a fixed block and a slider, in conjunction with a positioning ball, to adjust the position of the rectangular spring so that the initial contact pressure between the double-needle thermocouple and the specimen is adjustable. The under-positioning fit between the thermocouple clamp and the slider allows the thermocouple clamp to rotate and move along the slide. The double thermocouple needles have multiple degrees of freedom and can measure the temperature of the specimen when it undergoes complex three-dimensional deformation.

[0037] 2. When the specimen undergoes three-dimensional deformation, the double-needle thermocouple can move under the force of the slider, thermocouple clamp and rectangular spring as the specimen undergoes severe deformation. The double thermocouple needles are always in contact with the surface of the specimen, and displacement compensation is performed as the amount of deformation increases, thereby improving the temperature control accuracy during the deformation process.

[0038] 3. The temperature measuring device of the present invention is provided with a first reset spring, a second reset spring, a swing block and a stop lock, etc., to ensure that the first thermocouple and the second thermocouple have the same initial state.

[0039] 4. The temperature measuring device of the present invention is equipped with a thermocouple double needle protection device. When the specimen undergoes complex three-dimensional deformation, it is difficult to conservatively estimate the amount of deformation in advance and the deformation location cannot be predicted. A protective cylinder is installed in the rectangular spring. When the rectangular spring is subjected to force that reaches the stiffness of the thermocouple double needle, it will compress to the protective cylinder. The protective cylinder can hit the positioning spring sleeve to move the fixing block, thus protecting the thermocouple double needle from bending due to excessive force.

[0040] 5. The temperature measuring device of the present invention is easy to adjust, and the thermocouple double needles have a large range of motion, enabling temperature measurement at points with a large span distance; the thermocouple double needles have a small distance, enabling more precise coordination of displacement and a larger adaptability range; when the deformable body is made of two dissimilar materials, and the heating time to the required temperature is different, the double needle thermocouples can be placed on different materials respectively, allowing for more accurate measurement of the temperature of each material. Attached Figure Description

[0041] Figure 1 This is an overall structural diagram of the dual-needle thermocouple temperature measuring device for multi-degree-of-freedom body deformation adaptation of the present invention.

[0042] Figure 2 This is an internal structural diagram of the dual-needle thermocouple temperature measuring device for multi-degree-of-freedom body deformation adaptation of the present invention;

[0043] Figure 3 This is a cross-sectional view of the dual-needle thermocouple temperature measuring device for multi-degree-of-freedom body deformation adaptation of the present invention;

[0044] Figure 4 This is a structural diagram of the thermocouple clamp in the multi-degree-of-freedom body deformation-adaptive double-needle thermocouple temperature measuring device of the present invention;

[0045] Figures 5a-5b This is a structural diagram of the slider in the multi-degree-of-freedom body deformation-adaptive double-needle thermocouple temperature measuring device of the present invention;

[0046] Figures 6a-6b This is a structural diagram of the fixed block in the multi-degree-of-freedom body deformation-adaptive double-needle thermocouple temperature measuring device of the present invention;

[0047] Figure 7This is a calculation diagram of the motion range of one side of the thermocouple in the multi-degree-of-freedom body deformation-adaptive double-needle thermocouple temperature measuring device of the present invention.

[0048] Figure 8 A flowchart illustrating the usage of the dual-needle thermocouple temperature measuring device for multi-degree-of-freedom body deformation adaptation according to the present invention;

[0049] Figure 9 This is a graph showing the temperature difference between two measuring points on a 7A04 aluminum alloy sample during deformation, as measured by the dual-needle thermocouple temperature measuring device for adapting to multi-degree-of-freedom body deformation according to the present invention.

[0050] Key reference numerals:

[0051] 1. First thermocouple 2. Bolt 3. Thermocouple clamp 4. Positive wire 5. First positioning hole 6. Housing 7. Slider 8. Rectangular spring 9. Positioning ball 10. Fixing block 11. Negative wire 12. Screw 13. First hexagonal nut 14. Second thermocouple 15. Second hexagonal nut 16. Hexagonal nut slot 17. First threaded hole 18. First fixing slot 19. Second threaded hole 20. Slide rail 21. Second positioning hole 22. Second fixing slot 23. Circular slot 23. Lock 24. Swing block 25. First return spring 26. Spring column 27. Second return spring 28. Protective cylinder 29. Magnet 30. Positioning spring 31. Sleeve 32. Placement hole 33. Moving hole 34. First fixing hole 35. Second fixing hole 36. Cylindrical hole 37. Protective cylindrical hole 38. Detailed Implementation

[0052] To fully describe the technical content, structural features, objectives, and effects of this invention, a detailed description will be provided below in conjunction with the accompanying drawings.

[0053] The present invention provides a multi-degree-of-freedom deformation-adaptive dual-needle thermocouple temperature measuring device, such as... Figures 1 to 3 As shown, the device includes a first thermocouple 1, a second thermocouple 14, a thermocouple clamp 3, a housing 6, a slider 7, a rectangular spring 8, a fixing block 10, a stop lock 24, a swing block 25, a first return spring 26, a second return spring 28, a spring column 27, a protective cylinder 29, a magnet 30, a positioning spring 31, and a sleeve 32. Both the first thermocouple 1 and the second thermocouple 14 have rotational and translational degrees of freedom. The translational degree of freedom adjusts the position of the thermocouple by adjusting the position of the slide 20 and the first positioning hole 5. The rotational degree of freedom can compensate for large deformation displacements, making it suitable for more accurate temperature measurement due to thermal deformation of the body.

[0054] like Figure 4 As shown, the first end of the thermocouple clamp 3 is a connecting cylinder, and the interior of the connecting cylinder is provided with a second fixing hole 36. The second end of the thermocouple clamp 3 is a U-shaped plug, and cylindrical holes 37 are symmetrically provided on both sides of the U-shaped plug; as shown... Figures 5a-5bAs shown, the slider 7 has a first threaded hole 17 at its center, and hexagonal nut grooves 16 and circular grooves 23 on its two sides. A first fixing hole 35 is located on one side inside the slider 7, and a first fixing groove 18 is located on one side outside the slider 7. Figures 6a-6b As shown, the middle part of the fixing block 10 is provided with a protective cylindrical hole 38, the upper end and the lower end of the protective cylindrical hole 38 are respectively provided with a second fixing groove 22 and a moving hole 34, and the two sides of the middle part of the fixing block 10 are respectively provided with a second positioning hole 21 and a placement hole 33.

[0055] like Figure 1 As shown, specifically, the first end, the second end and the third end of the outer shell 6 are respectively provided with a second threaded hole 19, a first positioning hole 5 and a slide 20. The second threaded hole 19, the first positioning hole 5 and the slide 20 are symmetrically distributed on both sides of the outer shell 6. The second threaded hole 19 is used to install the double-needle thermocouple temperature measuring device on the experimental platform.

[0056] like Figure 2 and Figure 3 As shown, the fixed end of the first thermocouple 1 and the fixed end of the second thermocouple 14 are respectively connected to the first end of the first cylindrical hole on the U-shaped plug of the thermocouple clamp 3, which is symmetrically distributed on both sides of the outer shell 6, through bolt 2 and second hexagonal nut 15. The first mounting end of the swing block 25 is connected to the second end of the first cylindrical hole on the U-shaped plug of the thermocouple clamp 3. The input ends of the first thermocouple 1 and the second thermocouple 14 are respectively connected to the positive line 4 and the negative line 11. The fixed end of the first thermocouple 1 and the second thermocouple 14 can be adjusted in position through slider 7, fixed block 10, positioning hole 5 and rectangular spring 8. The thermocouple clamp 3 has rotational freedom and can move on the slide 20. The second mounting end of the swing block 25 is connected to the first end of the first return spring 26. The second end of the first return spring 26 is connected to the second cylindrical hole of the U-shaped plug in the thermocouple clamp 3 through the spring post 27. The fixed end of the stop lock 24 is connected to the mounting ends of the first thermocouple 1 and the second thermocouple 14 respectively. The movable end of the stop lock 24 is in contact with the swing block 25. The swing block 25, the stop lock 24 and the first return spring 26 together realize the reset of the double-needle thermocouple temperature measuring device.

[0057] like Figure 2As shown, the sliding end of the connecting cylinder of the thermocouple clamp 3 contacts the slide 20, the first threaded hole 17 of the slider 7 is connected to the fixed end of the connecting cylinder of the thermocouple clamp 3, the first end of the rectangular spring 8 is connected to the first fixed groove 18 of the slider 7, and the second end of the rectangular spring 8 is connected to the second fixed groove 22 of the fixing block 10. The fixing block 10 and the slider 7 jointly adjust the position of the rectangular spring 8, thereby adjusting the position of the first thermocouple 1 and the second thermocouple 14. The positioning spring 31 is connected to the positioning ball 9. The first end of the protective cylinder 29 is located inside the rectangular spring 8, and the second end of the protective cylinder 29 passes through the protective cylinder hole 38 and is connected to the sleeve 32. The protective cylinder 29 can strike the sleeve 32 to move the fixing block 10 and protect the thermocouple. By adjusting the position of the thermocouple and the preload of the rectangular spring 8 together with the positioning ball 9 and the slider 7, the thermocouple and the test piece can be fully contacted. The compression of the rectangular spring 8 can be changed by adjusting the distance between the slide 20 and the first positioning hole 5 to realize the degree of freedom of the device and give the thermocouple an initial contact pressure.

[0058] The second return spring 28 is located in the circular groove 23 of the slider 7, and the first hexagonal nut 13 is located in the hexagonal nut groove 16 of the slider 7. The two ends of the second return spring 28 are connected to the first fixing hole 35 and the second fixing hole 36 respectively. The return spring keeps the thermocouple in the same static initial state. The screw 12 is located inside the second return spring 28. The screw 12 connects the slider 7 and the thermocouple clamp 3. The sleeve 32 is located in the moving hole 34 of the fixing block 10. The mounting end of the sleeve 32 is connected to the magnet 30. It is connected to the fixing block 10 by the magnetic force of the magnet 30. The positioning spring 31 is located inside the sleeve 32. The positioning ball 9 is located between the second positioning hole 21 of the fixing block 10 and the first positioning hole 5 on the outer shell 6. The positioning ball 9 connects the fixing block 10 to the outer shell 6. The positioning spring 31 and the positioning ball 9 are connected. Pressing the positioning ball 9 inward pushes the positioning spring 31 to adjust the position of the fixing block 10. The magnet 30 is located in the placement hole 33 of the fixing block 10.

[0059] In a preferred embodiment of the present invention, the U-shaped plug, swing block 25, first return spring 26, spring post 27 and stop lock 24 of the thermocouple clamp 3 form a rotating assembly, which is symmetrically distributed on the outside of the housing 6.

[0060] The rotating assembly allows the thermocouple to rotate within a certain range on the plane. Since the temperature measurement process requires full contact between the thermocouple and the specimen, considering the dimensions of the testing device, the angle α of rotation of the thermocouple needle head is:

[0061]

[0062] Therefore, the expression for the arc length s1 of the thermocouple during rotation can be obtained as follows:

[0063]

[0064] Based on the maximum moving distance Δs of slider 7 max The maximum area S that the thermocouple needle head can rotate through. max The expression is:

[0065] S max =Δs max *2*(l0+l2')

[0066] In the experiment, the preset contact pressure F0 between the thermocouple and the specimen must be controlled within a reasonable range. Therefore, in the deformation-adaptive double-needle thermocouple temperature measuring device for multi-degree-of-freedom bodies, the preset contact pressure of the rectangular spring 8 must also be present when the slider 7 reaches its maximum sliding distance; therefore, F0 > k*Δs. max In the formula, k is the spring constant, and its expression is as follows:

[0067]

[0068] Where G is the shear modulus of the spring, d is the spring wire diameter, n is the number of spring coils, and D is the spring mean diameter. Assuming the spring deforms uniformly, the spring constant k of the rectangular spring 8 is a constant value, obtained experimentally.

[0069] When the thermocouple needle moves, if the force F1 perpendicular to the elastic force of the rectangular spring 8 is too large, the thermocouple needle will slide in this direction, and the thermocouple needle will not make sufficient contact with the specimen. Therefore, F1 < F μ F μ Let μ be the frictional force on the surface of the specimen, μ be the friction coefficient related to the material surface, and β be the friction angle. The expression is as follows:

[0070] μ = tanβ

[0071] To prevent the thermocouple from interfering with the outer casing 6, and to ensure that the angle α through which the thermocouple rotates is less than the friction angle β, the specific relationship is expressed as follows:

[0072] α < β

[0073]

[0074] To prevent the first thermocouple 1 and the second thermocouple 14 from interfering with and hitting the outer casing 6 during movement, the length L' of the thermocouples must be greater than the movable distance L of the slider 7 on the slide rail 20. The specific expression is as follows:

[0075] L'>L

[0076] Where α is the angle through which the thermocouple rotates, β is the friction angle, r0 is the straight-line length of the thermocouple needle from the center of the thermocouple clamp to the tip of the thermocouple needle, l0 is the vertical distance between the tip of the thermocouple needle and the upper part of the thermocouple, l2' is the distance the thermocouple needle tip moves downward, L' is part of the length of the thermocouple, and L is the movable distance of the slider 7 on the slide 20.

[0077] Specifically, because thermocouples have a certain stiffness, excessive force from the rectangular spring 8 can cause them to bend and become damaged. To protect the thermocouple, a protective cylinder 29 is added. The length of the protective cylinder 29 is:

[0078]

[0079] Among them, F I L is the maximum force that a thermocouple can withstand. k Let L be the length of the rectangular spring 8. y To protect the length of cylinder 29.

[0080] The slider 7, the connecting cylinder of the thermocouple clamp 3, the rectangular spring 8, the second return spring 28, the fixing block 10, the positioning spring 31, the positioning ball 9, the protective cylinder 29 and the sleeve 32 form a translational assembly, which is symmetrically distributed inside the outer shell 6; the axes of the rectangular spring 8, the first fixing groove 18 of the slider 7, the second fixing groove 22 of the fixing block 10 and the protective cylinder 29 are on the same straight line.

[0081] like Figure 7 As shown, the position of the positioning ball 9 is determined according to the length of the rectangular spring 8. The slider 7 is moved towards the position of the fixed block 10, so that the rectangular spring 8 has a pre-tightening contact force F0 to prevent insufficient contact between the thermocouple and the specimen during temperature measurement. When the rectangular spring 8 is in the pre-tightened state, the center of the slider 7 is located at O', and the needle tip of the thermocouple is located at O. Under the action of the pre-tightening force, the first thermocouple 1 and the second thermocouple 14 are in full contact with the specimen. When the contact position between the thermocouple and the specimen is deformed, the slider 7 will move under the action of the elastic force of the rectangular spring 8.

[0082] In the horizontal direction of the translational assembly, as the specimen deforms, the first thermocouple 1 and the second thermocouple 14 also move due to the preload F0. When the thermocouple moves upward, its movement distance is l1', and the vertical distance from the head of this double-needle thermocouple to the center point of the slider is s1'. The specific expression is as follows:

[0083]

[0084]

[0085] The expression for the distance that slider 7 moves towards the rectangular spring 8 is:

[0086]

[0087] Δs 1max ≤L1

[0088] Where s0 is the vertical distance between the thermocouple needle head and the center point of slider 7, s1' is the vertical distance between the thermocouple needle head and the center point of slider 7 when slider 7 moves towards the rectangular spring 8, Δs1 is the distance slider 7 moves backward, r0 is the straight-line length of the thermocouple from the center position of thermocouple clamp 3 to the thermocouple needle head, l0 is the vertical distance between the thermocouple needle head and the upper part of the thermocouple, l1' is the distance the thermocouple needle head moves upward, and Δs 1max L1 is the maximum distance the slider moves backward, and L2 is the distance between the center of the connecting cylinder sliding end and the end of the slide.

[0089] When l1' < l0, slider 7 moves away from rectangular spring 8; when l1' = l0, slider 7 moves to its maximum extent. When l1' > l0, slider 7 moves back towards the rectangular spring 8. When the thermocouple needle head moves a distance of 2l0 + l2' from point O, the maximum moving distance of the thermocouple is reached. Slider 7 moves to the front end of slide 20 and is limited, and can no longer move.

[0090] When the thermocouple moves downwards, the distance it moves is l2'. At this time, the vertical distance between the thermocouple needle head and the center point of the slider 7 is s2', and the specific expression is as follows:

[0091]

[0092] The expression for the distance that slider 7 moves away from rectangular spring 8 is:

[0093]

[0094] Δs 2max ≤L2

[0095] Where s0 is the vertical distance from the thermocouple head to the center point of slider 7, s2' is the vertical distance from the thermocouple head to the center point of slider 7 when slider 7 moves away from rectangular spring 8, Δs2 is the distance slider 7 moves forward, r0 is the straight-line length from the center of thermocouple clamp 3 to the tip of thermocouple needle, l0 is the vertical distance between the tip of thermocouple needle and the upper part of thermocouple, l2' is the distance the thermocouple needle head moves downward, and Δs 2max L1 represents the maximum distance the slider can move forward, and L2 represents the distance between the center of the connecting cylinder's sliding end and the front end of the slide.

[0096] Due to the length limitation of the slide rail 20, the distance Δs2 that the slider 7 moves away from the rectangular spring 8 is ≤ L2, Δs max =s 1max -s 2max Δs max This represents the maximum distance the slider can move.

[0097] The following describes in further detail, with reference to embodiments, a multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device and its usage method according to the present invention:

[0098] The method of using the multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device of the present invention, as follows: Figure 8 As shown, a double-needle thermocouple is used, which can freely detect the temperature between two points during the experiment. Due to the existence of preset contact pressure, the distance, position, and other conditions between the two points being measured can be freely changed. The outer shell 6 is installed on the testing machine. During operation, according to the size of the measurement space and the estimated deformation, the measuring ends of the thermocouple needles are placed against the workpiece being tested. The contact pressure between the measuring ends of the thermocouple needles and the workpiece is adjusted by adjusting the position of the positioning ball 9.

[0099] When the workpiece deforms due to tensile, shear, or other test forces, its original temperature measurement point changes due to the plastic deformation of the workpiece. The thermocouple needles, under the action of a pre-set appropriate contact pressure, can move in accordance with the material deformation, ensuring that they maintain their pre-set temperature measurement point throughout the measurement process. The thermocouple needles have translational and rotational freedom within the plane under the action of the slider 7, rectangular spring 8, fixing block 10, and thermocouple clamp 3. The first return spring 26, swing block 25, and stop lock 24 installed on the thermocouple clamp 3, as well as the second return spring 28 located between the slider 20 and the connecting cylinder of the thermocouple clamp 3, can reset the thermocouple needles.

[0100] In this embodiment, during the hot deformation uniaxial tensile test of a 7A04 aluminum alloy specimen, the device of this invention is used to continuously acquire the temperature difference data between two temperature measurement points of the 7A04 aluminum alloy specimen during the deformation process. The specific operation steps are as follows:

[0101] S1. Assemble the rotating assembly: Sequentially fix the first thermocouple 1, the second thermocouple 14 and the swing block 25 on the thermocouple clamps 3 symmetrically distributed on both sides of the outer shell 6, then fix the stop lock 24 on the first thermocouple 1 and the second thermocouple 14, and install the first return spring 26 between the swing block 25 and the U-shaped plug of the thermocouple clamp 3.

[0102] S2. Assemble the translational components: Install the magnet 30, positioning spring 31, sleeve 32 and positioning ball 9 on the fixing block 10 in sequence. Install the rectangular spring 8 between the fixing block 10 and the slider 7. Place the protective cylinder 29 inside the rectangular spring 8. Select a suitable first positioning hole 5 on the outer shell 6. Fix the positioning ball 9 inside the first positioning hole 5 by the elastic force of the positioning spring 31. Place the second return spring 28 between the first fixing hole 35 of the slider 7 and the second fixing hole 36 of the thermocouple clamp 3 by the screw 12. Use the first return spring 26 and the second return spring 28 to bring the first thermocouple 1 and the second thermocouple 14 to their initial state.

[0103] S3. Install the double-needle thermocouple temperature measuring device in a suitable position on the experimental machine through the second threaded hole 19 of the outer shell 6. Connect the measuring ends of the first thermocouple 1 and the second thermocouple 14 to the large deformation specimen respectively. Adjust the horizontal movement distance of the thermocouple by changing the position of the positioning ball 9 in the first positioning hole 5 and the position of the slider 7. Adjust the rotation angle of the thermocouple by adjusting the angle of the swing block 25 relative to the thermocouple clamp 3, so that the double-needle thermocouple temperature measuring device fits the large deformation specimen better.

[0104] S4. Connect the first thermocouple 1 connected to the positive line 4 and the second thermocouple 14 connected to the negative line 11 respectively. Apply a certain test force to the large deformation specimen and conduct the test. During the test, the first thermocouple 1 and the second thermocouple 14 are in contact with the large deformation specimen and undergo rotation, translation, or a combination of rotation and translation as the specimen deforms. This allows for continuous measurement of the temperature of the large deformation specimen during hot deformation, and the inter-span temperature data is recorded. The data results are as follows: Figure 9 As shown.

[0105] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A multi-degree-of-freedom deformation-adaptive dual-needle thermocouple temperature measuring device, comprising a thermocouple, a thermocouple clamp, a housing, a slider, a rectangular spring, a fixing block, a stop lock, a swing block, a return spring, a spring column, a protective cylinder, a magnet, a positioning spring, a positioning ball, and a sleeve, characterized in that, The first end of the thermocouple clamp is a connecting cylinder, and the interior of the connecting cylinder is provided with a second fixing hole. The second end of the thermocouple clamp is a U-shaped plug, and cylindrical holes are symmetrically provided on both sides of the U-shaped plug. The center of the slider is provided with a first threaded hole, and hexagonal nut groove and circular groove are respectively provided on both sides of the first threaded hole. The inner side of the slider is provided with a first fixing hole, and the outer side of the slider is provided with a first fixing groove. The middle of the fixing block is provided with a protective cylindrical hole, and the upper and lower ends of the protective cylindrical hole are respectively provided with a second fixing groove and a moving hole. The middle of the fixing block is provided with a second positioning hole and a placement hole on both sides. The fixed end of the thermocouple is connected to the first end of the first cylindrical hole on the U-shaped plug in the thermocouple clamp. The first mounting end of the swing block is connected to the second end of the first cylindrical hole on the U-shaped plug in the thermocouple clamp. The input ends of the first thermocouple and the second thermocouple are connected to the positive and negative wires, respectively. The second mounting end of the swing block is connected to the first end of the first return spring. The second end of the first return spring is connected to the second cylindrical hole of the U-shaped plug in the thermocouple clamp through a spring post. The fixed end of the stop lock is connected to the mounting end of the thermocouple. The movable end of the stop lock contacts the swing block. The swing block realizes the reset of the double-needle thermocouple temperature measuring device. The sliding end of the connecting cylinder of the thermocouple clamp contacts the slide rail. The first threaded hole of the slider is connected to the fixed end of the connecting cylinder of the thermocouple clamp. The first end of the rectangular spring is connected to the first fixed groove of the slider. The second end of the rectangular spring is connected to the second fixed groove of the fixed block. The positioning spring is connected to the positioning ball. The first end of the protective cylinder is located inside the rectangular spring. The second end of the protective cylinder passes through the protective cylinder hole and is connected to the sleeve. The degree of freedom of the device is realized by adjusting the distance between the slide rail and the first positioning hole to change the compression of the rectangular spring and to give the thermocouple an initial contact pressure. The U-shaped plug of the thermocouple clamp, the first return spring, the spring post, the stop lock, and the swing block constitute a rotating assembly.

2. The multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device according to claim 1, characterized in that, The second reset spring is located in the circular groove of the slider, the first hexagonal nut is located in the hexagonal nut groove of the slider, the two ends of the second reset spring are respectively connected to the first fixing hole and the second fixing hole, the sleeve is located in the moving hole of the fixing block, the mounting end of the sleeve is connected to the magnet, the positioning spring is located inside the sleeve, the positioning ball is located between the second positioning hole of the fixing block and the first positioning hole on the outer shell, and the magnet is located in the placement hole of the fixing block.

3. The multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device according to claim 1, characterized in that, The slider, the connecting cylinder of the thermocouple clamp, the rectangular spring, the second return spring, the fixing block, the positioning spring, the positioning ball, the protective cylinder, and the sleeve constitute a translational assembly; the axes of the rectangular spring, the first fixing groove of the slider, the second fixing groove of the fixing block, and the protective cylinder are on the same straight line.

4. The multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device according to claim 3, characterized in that, The translational components are symmetrically distributed inside the housing, and the rotational components are symmetrically distributed outside the housing.

5. The multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device according to claim 3, characterized in that, In the horizontal direction of the translational assembly, the expression for the distance the slider moves towards the rectangular spring is: ； ； in, This is the vertical distance from the head of the double-needle thermocouple to the center point of the slider. This is the vertical distance from the center point of the thermocouple head to the slider when the slider moves towards the rectangular spring. This represents the distance the slider moves backward. The straight-line length of the thermocouple needle from the center of the thermocouple clamp to the needle tip. This is the vertical distance between the tip of the thermocouple needle and the top of the thermocouple. This represents the distance the thermocouple needle tip moves upward. L1 is the maximum distance the slider moves backward, and L2 is the distance between the center of the connecting cylinder sliding end and the end of the slide. when The slider moves away from the rectangular spring; when At that time, the maximum movement of the slider ;when At that time, the slider moves back towards the rectangular spring; The expression for the distance the slider moves away from the rectangular spring is: ； ； in, This is the vertical distance from the thermocouple head to the center point of the slider. This is the vertical distance from the center point of the thermocouple needle to the slider when the slider moves away from the rectangular spring. This represents the distance the slider moves forward. Let be the straight-line length of the thermocouple from the center of the thermocouple clamp to the tip of the thermocouple needle. This is the vertical distance between the tip of the thermocouple needle and the top of the thermocouple. This is the distance the thermocouple needle tip moves downwards. L1 represents the maximum distance the slider can move forward, and L2 represents the distance between the center of the connecting cylinder's sliding end and the front end of the slide. Due to the limitation of the slide length, the distance the slider moves away from the rectangular spring is limited. , , This represents the maximum distance the slider can move.

6. The method of using the multi-degree-of-freedom body deformation-adaptive double-needle thermocouple temperature measuring device according to claim 1, characterized in that, In the direction of rotation of the rotating assembly, the angle through which the thermocouple rotates... Less than the friction angle Its specific relational expression is: ； ； ； in, The angle through which the thermocouple rotates. Let be the friction angle. The straight-line length of the thermocouple needle from the center of the thermocouple clamp to the needle tip. This is the vertical distance between the tip of the thermocouple needle and the top of the thermocouple. This is the distance the thermocouple needle tip moves downwards. L represents a portion of the length of the double-needle thermocouple, and L is the distance the slider moves on the slide.

7. The multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device according to claim 1, characterized in that, The first, second, and third ends of the outer casing are respectively provided with a second threaded hole, a first positioning hole, and a slide rail, and the first threaded hole, the first positioning hole, and the slide rail are symmetrically distributed on both sides of the outer casing.

8. A method of using a multi-degree-of-freedom body deformation-adaptive dual-needle thermocouple temperature measuring device according to any one of claims 1-7, characterized in that, It includes the following steps: S1. Assemble the rotating assembly: Fix the thermocouple and the swing block to the thermocouple clamp in sequence, fix the stop lock to the thermocouple, and install the first return spring between the swing block and the U-shaped plug of the thermocouple clamp. S2. Assemble the translational components: Install the magnet, positioning spring, sleeve and positioning ball on the fixed block in sequence. Then install the rectangular spring between the fixed block and the slider. Place the protective cylinder inside the rectangular spring. Place the second reset spring between the first fixing hole of the slider and the second fixing hole of the thermocouple clamp with screws. Use the first reset spring and the second reset spring to bring the first thermocouple and the second thermocouple to the initial state. S3. Install the double-needle thermocouple temperature measuring device on the experimental machine through the second threaded hole of the outer shell. Connect the measuring ends of the first thermocouple and the second thermocouple to the large deformation specimen respectively. Adjust the horizontal movement distance of the thermocouple by changing the position of the positioning ball in the first positioning hole and the position of the slider. Adjust the rotation angle of the thermocouple by adjusting the angle of the swing block relative to the thermocouple clamp, so that the double-needle thermocouple temperature measuring device fits the large deformation specimen better. S4. Connect the first thermocouple connected to the positive line and the second thermocouple connected to the negative line respectively, apply a certain test force to the large deformation specimen and conduct the test. During the test, the first thermocouple and the second thermocouple are attached to the large deformation specimen and move with the deformation of the large deformation specimen. Continuously measure the temperature of the large deformation specimen during hot deformation and record the temperature data between the two sides.

9. The method of using the multi-degree-of-freedom body deformation-adaptive double-needle thermocouple temperature measuring device according to claim 8, characterized in that, During operation, the thermocouple in the temperature measuring device requires the length of the protective cylinder to meet the following conditions: ； in, This is the maximum force that the thermocouple can withstand. Let the length of the rectangular spring be _____. To protect the length of the cylinder and thus prevent bending damage.

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