Double-needle thermocouple temperature measuring device adapted to in-plane deformation and use method thereof

Abstract

The present invention provides a double-needle thermocouple temperature measuring device adaptable to in-plane deformation and a method for using the same, comprising a top end cover, a positioning needle, a variable diameter spring, a thermocouple needle, a housing and a radial constraint sheet. The top end cover and the mounting ends of the flange sleeve are respectively fixedly connected to the upper end and the lower end of the housing, the axial constraint collar is in contact with the first end of the upper radial constraint sheet, the notch of the upper radial constraint sheet is connected to the first mounting end of the positioning needle, the notch of the lower radial constraint sheet is connected to the second mounting end of the positioning needle, and the first end of the lower radial constraint sheet is in contact with the upper end of the flange sleeve. The mounting ends of the thermocouple needles are respectively connected to the first ends of the wiring terminals through the semi-conical holes of the upper radial constraint sheet, the locking retaining ring is fixedly connected to the thermocouple needle by a locking screw, and the adjusting screw is connected to the third end of the axial constraint collar. The present invention can not only compensate for the degree of freedom of the thermocouple needle, but also provide an adjustable preload force for the front end contact of the thermocouple needle, effectively preventing the temperature measurement point from being misaligned due to workpiece deformation.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature measurement and control in a material processing process, and in particular to a double-needle thermocouple temperature measurement device capable of adapting to in-plane deformation and a method for using the same. Background Art

[0002] Thermocouples are commonly used temperature measuring elements in temperature measuring instruments. They directly measure temperature and convert temperature signals into thermoelectric potential signals, which are then converted into the temperature of the measured medium through electrical instruments such as secondary instruments. The shapes of various thermocouples often vary depending on needs, but their basic structures are roughly the same. They are usually used in conjunction with display instruments, recording instruments and electronic regulators.

[0003] In the process of cold or hot deformation of plate-shaped or block-shaped metals, temperature monitoring technology during deformation is a necessary link. In the experiment, in order to accurately obtain the voltage across the two measured points, a double-needle thermocouple is usually used for contact temperature measurement. Since the positive and negative poles of the thermocouple adopt an open-circuit design, it is necessary to manually apply pressure to the two terminals of the thermocouple measuring end during contact temperature measurement to achieve full contact and achieve the purpose of measuring temperature. In the conventional temperature measurement process, manual pressure cannot achieve constant regulation of contact pressure, and a pressure variable is introduced. At the same time, the position of the temperature measurement point changes before and after the material undergoes plastic deformation. The traditional double-needle thermocouple operation cannot provide reasonable position compensation as the material deforms, resulting in temperature measurement errors.

[0004] In order to solve the above problems, the present invention designs a novel double-needle thermocouple measuring device with constant adjustable pressure and in-plane deformation adaptability. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a double-needle thermocouple temperature measuring device adaptable to in-plane deformation and a method of using the same. The axial position of the upper radial constraint plate is changed by adjusting the screw-in depth of the screw, thereby adjusting the contact pressure between the measuring end of the thermocouple needle and the workpiece; at the same time, a symmetrical stepped hole is provided in the middle of the upper radial constraint plate, the large hole end of the stepped hole is a semi-circular arc groove, and the small hole end of the stepped hole is a semi-conical hole, and the semi-conical hole reduces the interference and wear caused by the movement of the thermocouple needle; a symmetrical stepped hole is provided in the middle of the lower radial constraint plate, the large hole end of the stepped hole is a semi-circular arc groove, and the small hole end of the stepped hole is a semicircular hole, and the semi-circular hole provides freedom for the follow-up of the thermocouple needle, thereby effectively preventing the temperature measurement point from being misaligned due to the deformation of the workpiece.

[0006] The present invention provides a double-needle thermocouple temperature measuring device with in-plane deformation adaptability, which includes a top end cover, a terminal, an axial constraint collar, a positioning pin, a variable diameter spring, a locking retaining ring, a thermocouple pin, a housing, a radial constraint sheet and a flange sleeve. The radial edge of the radial constraint sheet is symmetrically provided with notches, the middle part of the upper radial constraint sheet is provided with symmetrical stepped holes, the large hole end of the stepped hole is a semi-circular arc groove, the small hole end of the stepped hole is a semi-conical hole, and the semi-conical hole reduces the interference and wear caused by the movement of the thermocouple pin, and the middle part of the lower radial constraint sheet is provided with symmetrical stepped holes, the large hole end of the stepped hole is a semi-circular arc groove, the small hole end of the stepped hole is a semi-circular hole, and the semi-circular hole provides freedom for the follow-up of the thermocouple pin. According to the radius z of the maximum semicircular arc area of ​​the thermocouple needle, the cross-sectional radius r of the thermocouple needle, the maximum length L of the thermocouple needle, the thickness t of the radial constraint sheet, and the distance h between the upper radial constraint sheet and the lower radial constraint sheet, the radius expression of the large hole end in the upper radial constraint sheet can be obtained as follows:

[0007]

[0008] The radius expression of the small hole end in the lower radial constraint plate is as follows:

[0009]

[0010] The radius expression of the large hole end in the lower radial constraint piece is as follows:

[0011]

[0012] Among them, y' is the radius of the small hole end of the upper radial constraint plate, x is the radius of the large hole end of the lower radial constraint plate, y is the radius of the large hole end of the upper radial constraint plate, and α is the draft angle.

[0013] The mounting ends of the top end cover and the flange sleeve are respectively fixedly connected to the upper end and the lower end of the outer shell, the first end of the axial constraint ring contacts the lower end of the top end cover, the second end of the axial constraint ring contacts the first end of the upper radial constraint plate, the notch of the upper radial constraint plate is connected to the first mounting end of the positioning pin, the notch of the lower radial constraint plate is connected to the second mounting end of the positioning pin, and the first end of the lower radial constraint plate contacts the upper end of the flange sleeve. The mounting ends of the first thermocouple needle and the second thermocouple needle pass through the first semi-conical hole and the second semi-conical hole of the upper radial constraint plate and are connected to the first ends of the positive terminal and the negative terminal respectively. The second ends of the positive terminal and the negative terminal pass through the through holes of the top end cover and the axial constraint ring in turn and are suspended outside. The measuring ends of the first thermocouple needle and the second thermocouple needle pass through the variable diameter spring and the locking retaining ring in turn and extend out of the flange sleeve. The locking retaining ring is fixedly connected to the thermocouple needle by a locking screw, and the adjusting screw is connected to the third end of the axial constraint ring.

[0014] Preferably, the axial restraint ring, the positioning needle, the variable diameter spring, the locking retaining ring, the upper radial restraint plate and the lower radial restraint plate are located inside the outer shell; the axes of the top end cover, the axial restraint ring, the adjusting screw, the radial restraint plate, the outer shell and the flange sleeve are in the same straight line; the axes of the thermocouple needle, the variable diameter spring and the locking retaining ring are in the same straight line.

[0015] Preferably, the cross section of the variable diameter spring is semicircular, and the variable diameter spring is symmetrically arranged at both ends of the locking retaining ring.

[0016] Preferably, the relationship between the screw-in amount Δh of the adjusting screw and the stiffness coefficient and contact pressure of the variable diameter springs symmetrically distributed on both sides of the locking retaining ring is expressed as follows:

[0017]

[0018]

[0019] Among them, F u is the maximum regulated contact pressure in the surface, F d is the minimum adjustment contact pressure in the surface, k1 is the spring constant on the first thermocouple needle close to the upper radial constraint plate, and k2 is the spring constant close to the measuring end.

[0020] Preferably, the thermocouple needle moves under the action of contact pressure, and the expression of the contact pressure F1' on the first thermocouple needle is:

[0021]

[0022] Among them, F1 is the size of the contact pressure on the first thermocouple needle before material deformation, F1' is the size of the contact pressure on the first thermocouple needle after material deformation, k1 is the spring stiffness coefficient of the first thermocouple needle close to the upper radial constraint plate, k2 is the spring stiffness coefficient close to the measuring end, α1 is the inclination angle between the actual displacement length of the material and the center axis of the device, △h is the screw-in amount of the adjusting screw, r is the radius of the cross section of the thermocouple needle, L is the maximum length of the thermocouple needle, and z1 is the actual displacement length of the first thermocouple needle during the test.

[0023] Preferably, at this time, the expression of the contact pressure F2' on the second thermocouple needle is:

[0024]

[0025] Among them, F2 is the contact pressure on the second thermocouple needle before material deformation, k3 is the spring stiffness coefficient of the second thermocouple needle close to the upper radial constraint plate, k4 is the spring stiffness coefficient close to the measuring end, △h is the screw-in amount of the adjusting screw, r is the radius of the cross section of the thermocouple needle, L is the maximum length of the thermocouple needle, and z2 is the actual displacement length of the second thermocouple needle during the test.

[0026] Another aspect of the present invention provides a method for using a double-needle thermocouple temperature measuring device with in-plane deformation adaptation, and the specific steps are as follows:

[0027] S1. First, thread the flange sleeve and the lower end of the housing together, then sequentially position and fit the lower radial constraint sheet, the variable diameter spring, the thermocouple needle, the locking retaining ring, the upper radial constraint sheet and the positioning needle together, finally insert the axial constraint collar, and install the top end cover to complete the final assembly;

[0028] S2. Perform preliminary positioning by adjusting the screws and fix the double-needle thermocouple temperature measuring device at the test position;

[0029] S3, placing the extended ends of the first thermocouple needle and the second thermocouple needle in the double-needle thermocouple temperature measuring device against the predetermined temperature measurement positions of the measured material, and setting the contact pressure of the measured material by changing the screwing depth of the adjusting screw;

[0030] S4. Connect the positive terminal connected to the first thermocouple needle and the negative terminal connected to the second thermocouple needle, apply a certain test force to the material under test and conduct a test. During the test, continuously measure and record the span temperature data.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. When the present invention is working, the front measuring end of the thermocouple needle is pressed against the workpiece, and the axial position of the upper radial adjustment plate is changed by adjusting the screw insertion depth, thereby adjusting the contact pressure between the thermocouple needle measuring end and the workpiece. The preset contact pressure maintained by a simple mechanical structure is within an adjustable constant range, which controls the experimental variables and reduces the experimental errors.

[0033] 2. In the present invention, when the workpiece undergoes in-plane deformation due to test forces such as tension and shear, its original temperature measuring point changes due to the plastic deformation of the workpiece. The thermocouple needle can move with the deformation of the workpiece due to the preset appropriate contact pressure, so that it always maintains its preset temperature measuring point during the measurement process.

[0034] 3. The under-positioning cooperation between the semicircular arc-shaped variable-section spring and the thermocouple needle in the present invention provides a movable space for the thermocouple needle while providing a pre-tightening contact pressure for the thermocouple needle, thereby providing a degree of freedom for the thermocouple needle to follow the deformation of the workpiece.

[0035] 4. The present invention can measure the span temperature between two points. The movable double-needle thermocouple can perform passive in-plane deformation compensation adjustment when the workpiece is deformed. The design of the semicircular arc spring gives the thermocouple needle freedom of compensation adjustment while providing an adjustable preload for the front end contact of the thermocouple needle, effectively preventing the temperature measurement point from being misaligned due to workpiece deformation.

[0036] 5. The present invention designs semicircular holes and semi-conical holes on the upper radial constraint plate and the lower radial constraint plate according to the working mode and installation and assembly relationship of the thermocouple needle during the test process. The semicircular holes provide freedom for the follow-up of the thermocouple needle, and the semi-conical holes simulate the movement of the top of the thermocouple needle when it follows, effectively reducing the interference and wear that may be caused by the movement of the thermocouple needle. The device is easy and convenient to install, has a simple and flexible structure, is low in cost, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a cross-sectional view of the overall structure of the double-needle thermocouple temperature measuring device with in-plane deformation adaptation of the present invention;

[0038] Figure 2 It is a schematic diagram of the cooperation between the radial constraint sheet, the thermocouple needle and the spring in the double-needle thermocouple temperature measuring device with in-plane deformation adaptation of the present invention;

[0039] Figure 3 It is a structural diagram of the upper radial constraint sheet in the double-needle thermocouple temperature measuring device with in-plane deformation adaptation of the present invention;

[0040] Figure 4 It is a structural diagram of the lower radial constraint piece in the double-needle thermocouple temperature measuring device with in-plane deformation adaptation of the present invention;

[0041] Figure 5 It is a dimensional relationship diagram of the radial constraint piece in the double-needle thermocouple temperature measuring device adapted to in-plane deformation of the present invention;

[0042] Figure 6 This is a diagram showing the use of the double-needle thermocouple temperature measuring device adapted to in-plane deformation in a heat treatment uniaxial tensile test;

[0043] Figure 7 A flow chart of a method for using the double-needle thermocouple temperature measuring device adapted to in-plane deformation of the present invention;

[0044] Figure 8 This is a diagram of the measurement results of a 6061 aluminum alloy sample in the double-needle thermocouple temperature measuring device adapted to in-plane deformation of the present invention.

[0045] Main reference numerals:

[0046] Top end cover 1, positive terminal 2, axial restraint ring 3, positioning needle 4, variable diameter spring 5, locking retaining ring 6, first thermocouple needle 7, outer shell 8, lower radial restraint plate 9, flange sleeve 10, locking screw 11, second thermocouple needle 12, upper radial restraint plate 13, negative terminal 14, adjusting screw 15. DETAILED DESCRIPTION

[0047] In order to fully describe the technical content, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0048] The double-needle thermocouple temperature measuring device adapted to in-plane deformation of the present invention is as follows: Figure 1 and Figure 2 As shown, it includes a top end cover 1, a positive terminal 2, a negative terminal 14, an axial restraint collar 3, a positioning pin 4, a variable diameter spring 5, a locking retaining ring 6, a first thermocouple pin 7, a locking screw 11, a second thermocouple pin 12, an outer shell 8, a lower radial restraint plate 9, an upper radial restraint plate 13, an adjusting screw 15 and a flange sleeve 10.

[0049] The upper radial constraint sheet 13, the lower radial constraint sheet 9, the locking retaining ring 6, and the locking screw 11 are all made of ceramic materials, and the variable diameter spring 5 is surface-insulated to reduce the measurement error generated when it contacts the measuring end of the thermocouple needle. The top end cover 1 is a threaded flange-type transparent cover with an oblate cylindrical outer profile and a thread on the flange, which cooperates with the thread on the fixed housing 8. A through hole is opened on the top end cover 1 to facilitate the wiring operation of the positive and negative terminals of the thermocouple. Similar to it, the axial constraint collar 3 has two cylindrical through holes in addition to the central M6 threaded hole to facilitate the wiring operation of the positive and negative terminals of the thermocouple.

[0050] The radial edges of the lower radial constraint sheet 9 and the upper radial constraint sheet 13 are symmetrically provided with notches, such as Figure 3 As shown, a symmetrical stepped hole is provided in the middle of the upper radial constraint sheet 13. The large hole end of the stepped hole is a semicircular groove. The depth of the semicircular groove is 1mm. The semicircular groove cooperates with the large end surface of the variable diameter spring 5 to achieve axial freedom of positioning. The small hole end of the stepped hole is a semiconical hole. The semiconical hole simulates the movement of the top of the thermocouple needle when it moves, effectively reducing the interference and wear that may be caused by the movement of the thermocouple needle. Figure 4 As shown, a symmetrical stepped hole is provided in the middle of the lower radial constraint plate 9, and the large hole end of the stepped hole is a semicircular groove, the depth of the semicircular groove is 1 mm, and the semicircular groove cooperates with the large end face of the variable diameter spring 5 to realize the positioning of the axial freedom; the small hole end of the stepped hole is a semicircular hole, and the semicircular hole provides freedom for the follow-up of the thermocouple needle.

[0051] In a preferred embodiment of the present invention, the radius z of the maximum semicircular arc area of ​​the thermocouple needle, the cross-sectional radius r of the thermocouple needle, the maximum length L of the thermocouple needle, the thickness t of the radial constraint sheet, and the distance h between the upper radial constraint sheet 13 and the lower radial constraint sheet 9 are known, as shown in FIG. Figure 5 As shown, according to the similar triangle theory, the ratio of the apertures on the lower radial constraint sheet 9 is equal to the ratio of the distances from the upper radial constraint sheet 13 to the upper vertices of the similar triangles. The specific expression is:

[0052]

[0053]

[0054]

[0055] The distance between the upper radial constraint sheet 13 and the upper vertex of the similar triangle can be calculated by constraining the draft angle. The specific expression is:

[0056]

[0057] The radius expression of the large hole end in the radial constraint sheet 13 is as follows:

[0058]

[0059] The radius expression of the small hole end in the lower radial constraint sheet 9 is as follows:

[0060]

[0061] The radius expression of the large hole end in the lower radial constraint plate 9 is as follows:

[0062]

[0063] Among them, y' is the radius of the small hole end of the upper radial constraint plate, x is the radius of the large hole end of the lower radial constraint plate, y is the radius of the large hole end of the upper radial constraint plate, and α is the draft angle.

[0064] like Figure 1 As shown, the mounting ends of the top end cover 1 and the flange sleeve 10 are respectively fixedly connected to the upper and lower ends of the outer shell 8, the first end of the axial constraint ring 3 contacts the lower end of the top end cover 1, the second end of the axial constraint ring 3 contacts the first end of the upper radial constraint plate 13, the notch of the upper radial constraint plate 13 is connected to the first mounting end of the positioning needle 4, the notch of the upper radial constraint plate 13 is connected to the positioning needle 4 and fits with the end face of the adjusting screw 15 to achieve axial positioning, the notch of the lower radial constraint plate 9 is connected to the second mounting end of the positioning needle 4, the notch of the lower radial constraint plate 9 is connected to the positioning needle 4 and fits with the flange of the threaded flange sleeve 10 to achieve axial positioning, and the first end of the lower radial constraint plate 9 contacts the upper end of the flange sleeve 10.

[0065] like Figure 2 As shown, the mounting ends of the first thermocouple needle 7 and the second thermocouple needle 12 respectively pass through the first semi-conical hole and the second semi-conical hole of the upper radial constraint plate 13 and are connected to the first ends of the positive terminal 2 and the negative terminal 14, and the second ends of the positive terminal 2 and the negative terminal 14 pass through the through holes of the top end cover 1 and the axial constraint ring 3 in turn and are suspended outside, and the measuring ends of the first thermocouple needle 7 and the second thermocouple needle 12 pass through the variable diameter spring 5 and the locking retaining ring 6 in turn and extend from the flange sleeve 10, and the locking retaining ring 6 is respectively fixed to the first thermocouple needle 7 and the second thermocouple needle 12 by the locking screw 11, and the adjusting screw 15 is connected to the third end of the axial constraint ring 3, and when the screw-in amount of the adjusting screw 15 increases, the upper radial constraint plate 13 is pushed downward, and the variable diameter spring 5 increases the preload force thereby.

[0066] The cross-section of the variable diameter spring 5 is semicircular, and the variable diameter spring 5 is symmetrically arranged at both ends of the locking retaining ring 6. The end surface of the variable diameter spring 5 with a small cross-sectional diameter is tightly fitted with the locking retaining ring 6, and the end surface of the variable diameter spring 5 with a large cross-sectional diameter is respectively embedded in the upper radial constraint plate 9 and the lower radial constraint plate 9. The upper semicircular arc groove.

[0067] The locking ring 6 is fitted on the thermocouple needle and then cooperates with the variable diameter spring 5 whose axial position is limited to achieve the axial positioning of the thermocouple needle. In this way, the thermocouple needle can move to a certain extent within the constraint range of the variable diameter spring 5 when it is not rigidly fixed. When the material undergoes plastic deformation due to the test force and the position of its original temperature measurement point changes, the thermocouple needle maintains dynamic compensation of the measurement position by following up under the action of the preset contact pressure.

[0068] Specifically, the axial constraint collar 3, the positioning pin 4, the variable diameter spring 5, the locking retaining ring 6, the upper radial constraint sheet 13 and the lower radial constraint sheet 9 are located inside the housing 8; the axes of the top end cover 1, the axial constraint collar 3, the adjusting screw 15, the upper radial constraint sheet 13, the lower radial constraint sheet 9, the housing 8 and the flange sleeve 10 are on the same straight line; the upper radial constraint sheet 13 and the lower radial constraint sheet 9 are respectively on the same straight line with the axes of the variable diameter spring 5 and the locking retaining ring 6 located thereon. There are two positioning pins 4, which are symmetrically distributed on both sides of the upper radial constraint sheet 13 and the lower radial constraint sheet 9.

[0069] It is known that the stiffness coefficient of the variable diameter spring 5 near the upper radial constraint plate 13 on the first thermocouple needle 7 is k1, the stiffness coefficient of the variable diameter spring 5 near the lower radial constraint plate 9 is k2, and the contact pressure is F1; the stiffness coefficient of the variable diameter spring 5 near the upper radial constraint plate 13 on the second thermocouple needle 12 is k3, the stiffness coefficient of the variable diameter spring 5 near the lower radial constraint plate 9 on the second thermocouple needle 12 is k4, and the contact pressure is F2.

[0070] Specifically, on a single thermocouple needle, the two variable diameter springs 5 ​​are connected in series, and their total deformation is the screw-in amount Δh of the adjusting screw 15. The deformations of the two variable diameter springs 5 ​​are Δh1 and Δh2, respectively. The relationship between the deformation and the preset contact pressure is shown in the following formula:

[0071]

[0072] The relationship between the screw-in amount Δh of the adjusting screw 15 and the stiffness coefficient and contact pressure of the variable diameter spring 5 symmetrically distributed on both sides of the locking retaining ring 6 is expressed as follows:

[0073]

[0074] In the whole device, the variable diameter spring 5 is connected in parallel on the first thermocouple needle 7 and the second thermocouple needle 12, and their adjustable range is the same. However, in most cases, the offset of the thermocouple needle, that is, the screw-in amount Δh of the adjusting screw 15, is a certain range, and a variable diameter spring 5 with a certain stiffness coefficient needs to be customized. Assuming that the spring stiffness coefficient of the first material thermocouple needle 7 near the upper radial constraint plate 13 is k1, the stiffness coefficient of the variable diameter spring 5 near the lower radial constraint plate 9 can be calculated to be k2,

[0075]

[0076] Among them, F u is the maximum regulated contact pressure in the surface, F d is the minimum adjustment contact pressure within the surface, k1 is the stiffness coefficient of the variable diameter spring 5 on the first thermocouple needle 7 close to the upper radial constraint plate 13, and k2 is the stiffness coefficient of the variable diameter spring 5 close to the measuring end.

[0077] Among them, F u is the maximum value of the contact pressure on the thermocouple needle, F d is the minimum value of the contact pressure on the thermocouple needle, k i (i=1,2) is the stiffness coefficient k of the variable diameter spring 5. The stiffness coefficient k can be obtained by the following formula:

[0078]

[0079] Among them, G is the shear elastic modulus of the variable diameter spring 5, d is the wire diameter of the variable diameter spring 5, n is the number of turns of the variable diameter spring 5, and D is the median diameter of the variable diameter spring 5.

[0080] When the material under test undergoes plastic deformation, the position of the temperature measurement point deviates in the plane, and the thermocouple needle moves under the action of the contact pressure. Assuming that the thermocouple needle drives the variable diameter spring 5 to deviate outward, the variable diameter spring 5 near the upper radial constraint piece 13 is compressed by a length Δh1 that becomes shorter, and the compression force F1 becomes smaller. At the same time, the variable diameter spring 5 near the lower radial constraint piece 9 is compressed by a length Δh2 that becomes longer, and the compression force F1 becomes larger, and Δh = Δh1 + Δh2 is still maintained. If the follow-up length of the first thermocouple needle 7 is z1, the expression of the contact pressure F1' on the first thermocouple needle 7 is:

[0081]

[0082] Among them, F1 is the size of the contact pressure on the first thermocouple needle 7 before the material is deformed, F1' is the size of the contact pressure on the first thermocouple needle 7 after the material is deformed, k1 is the spring stiffness coefficient of the first thermocouple needle 7 close to the upper radial constraint plate 13, k2 is the spring stiffness coefficient close to the measuring end, α1 is the inclination angle between the actual displacement length of the material and the center axis of the device, △h is the screw-in amount of the adjusting screw 15, r is the radius of the cross section of the thermocouple needle, L is the maximum length of the thermocouple needle, and z1 is the actual displacement length of the first thermocouple needle 7 during the test.

[0083] The follow-up length of the second thermocouple needle 12 is z2, and the expression of the contact pressure F2' on the second thermocouple needle is:

[0084]

[0085] Among them, F2 is the size of the contact pressure on the second thermocouple needle 12 before the material is deformed, k3 is the spring stiffness coefficient of the second thermocouple needle 12 close to the upper radial constraint plate 13, k4 is the spring stiffness coefficient close to the measuring end, △h is the screw-in amount of the adjusting screw 15, r is the radius of the cross section of the thermocouple needle, L is the maximum length of the thermocouple needle, and z2 is the actual displacement length of the second thermocouple needle 12 during the test.

[0086] The following is a further description of the use method or test method of the double-needle thermocouple temperature measuring device with in-plane deformation adaptation of the present invention in combination with the embodiments:

[0087] The method for using the double-needle thermocouple temperature measuring device that is adaptable to in-plane deformation of the present invention adopts a double-needle thermocouple. During the experiment, the span temperature between two points can be freely detected. Due to the existence of the preset contact pressure, the distance, position and other conditions between the two points to be measured can be freely changed. During operation, the measuring end of the thermocouple needle is pressed against, and the axial position of the upper radial constraint plate 13 is changed by adjusting the screw-in depth of the screw 15, thereby adjusting the contact pressure between the measuring end of the thermocouple needle and the workpiece. When the material undergoes in-plane deformation due to test forces such as tension and shear, its original temperature measurement point changes due to the plastic deformation of the workpiece. The thermocouple needle can move in coordination with the deformation of the material due to the preset appropriate contact pressure, so that it always maintains its preset temperature measurement point during the measurement process. The thermocouple needle can move freely in the semicircular groove of the lower radial constraint plate 9 without interference, and the function of the semi-variable cross-section spring 5 is similar. The upper radial constraint sheet 13 is provided with a semi-conical hole to cooperate with the thermocouple needle. The semi-conical hole simulates the motion trajectory of the top end of the thermocouple needle when it moves and provides a degree of freedom for it.

[0088] In the uniaxial tensile test of the 6061 aluminum alloy sample during thermal deformation, the present invention is used to continuously obtain the temperature difference data between two temperature measurement points of the 6061 aluminum alloy sample during the deformation process. At the same time, an infrared temperature measuring probe is used for synchronous tracking to verify the accuracy of the experimental data. Figure 7 As shown, the specific steps are as follows:

[0089] S1. First, thread the flange sleeve 10 and the lower end of the shell 8, and then position and connect the lower radial constraint plate 9, the variable diameter spring 5, the first thermocouple needle 7, the second thermocouple needle 12, the locking retaining ring 6, the upper radial constraint plate 13 and the positioning needle 4 in sequence, and finally insert the axial constraint ring 3 and install the top end cover 1 to complete the final assembly.

[0090] S2. Perform preliminary positioning by adjusting screw 15 and fix the double-needle thermocouple temperature measuring device at the test position.

[0091] S3, such as Figure 6 As shown, the extended ends of the first thermocouple needle 7 and the second thermocouple needle 12 in the double-needle thermocouple temperature measuring device are respectively pressed against the predetermined temperature measuring positions of the 6061 aluminum alloy sample, and the contact pressure of the 6061 aluminum alloy sample is given by changing the screw-in depth of the adjusting screw 15.

[0092] S4, connect the positive terminal 2 connected to the first thermocouple needle 7 and the negative terminal 14 connected to the second thermocouple needle 12, apply a certain test force to the 6061 aluminum alloy sample to make it deform and conduct the test, continuously measure and record the span temperature data during the test, the experimental data is as follows Figure 8 shown.

[0093] Depend on Figure 8 It can be seen from the image that the data continuously acquired by the present invention is basically consistent with the data synchronously tracked by the infrared temperature measuring probe. At the same time, the results show that when the 6061 aluminum alloy sample material undergoes plastic deformation, the thermocouple double needles against the temperature measuring points on the surface of the 6061 aluminum alloy sample follow the preset contact pressure and accurately obtain the temperature difference data between the preset temperature measuring points during the deformation process.

[0094] The above embodiments are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A double-needle thermocouple temperature measuring device with in-plane deformation adaptation, comprising a top end cover, a terminal, an axial constraint collar, a positioning needle, a variable diameter spring, a locking retaining ring, a thermocouple needle, a housing, a radial constraint sheet and a flange sleeve, characterized in that: The radial edge of the radial constraint sheet is symmetrically provided with notches, the middle part of the upper radial constraint sheet is provided with symmetrical stepped holes, the large hole end of the stepped hole is a semicircular groove, the small hole end of the stepped hole is a semiconical hole, the semiconical hole reduces the interference and wear caused by the movement of the thermocouple needle, the middle part of the lower radial constraint sheet is provided with symmetrical stepped holes, the large hole end of the stepped hole is a semicircular groove, the small hole end of the stepped hole is a semicircular hole, the semicircular hole provides freedom for the follow-up of the thermocouple needle; According to the radius z of the maximum semicircular arc area of ​​the thermocouple needle, the cross-sectional radius r of the thermocouple needle, the maximum length L of the thermocouple needle, the thickness t of the radial constraint sheet, and the distance h between the upper radial constraint sheet and the lower radial constraint sheet, the radius expression of the large hole end in the upper radial constraint sheet is obtained as follows: The radius of the small hole end of the lower radial constraint sheet is expressed as follows: The radius expression of the large hole end in the lower radial constraint sheet is as follows: Among them, y' is the radius of the small hole end of the upper radial constraint sheet, x is the radius of the middle and large hole end of the lower radial constraint sheet, y is the radius of the middle and large hole end of the upper radial constraint sheet, and α is the draft angle; The mounting ends of the top end cover and the flange sleeve are respectively fixedly connected to the upper end and the lower end of the shell, the first end of the axial constraint collar contacts the lower end of the top end cover, the second end of the axial constraint collar contacts the first end of the upper radial constraint sheet, the notch of the upper radial constraint sheet is connected to the first mounting end of the positioning pin, the notch of the lower radial constraint sheet is connected to the second mounting end of the positioning pin, and the first end of the lower radial constraint sheet contacts the upper end of the flange sleeve; The mounting ends of the first thermocouple needle and the second thermocouple needle pass through the first semi-conical hole and the second semi-conical hole of the upper radial constraint plate and are connected to the first ends of the positive terminal and the negative terminal respectively. The second ends of the positive terminal and the negative terminal pass through the through holes of the top end cover and the axial constraint ring in turn and are suspended outside. The measuring ends of the first thermocouple needle and the second thermocouple needle pass through the variable diameter spring and the locking retaining ring in turn and extend out of the flange sleeve. The locking retaining ring is fixedly connected to the thermocouple needle by a locking screw, and the adjusting screw is connected to the third end of the axial constraint ring.

2. The double-needle thermocouple temperature measuring device adapted to in-plane deformation according to claim 1, characterized in that: The axial restraint collar, the positioning needle, the variable diameter spring, the locking retaining ring, the upper radial restraint plate and the lower radial restraint plate are located inside the outer shell; the axes of the top end cover, the axial restraint collar, the adjusting screw, the radial restraint plate, the outer shell and the flange sleeve are in the same straight line; the axes of the thermocouple needle, the variable diameter spring and the locking retaining ring are in the same straight line.

3. The double-needle thermocouple temperature measuring device with in-plane deformation adaptation according to claim 1 or 2, characterized in that: The cross section of the variable diameter spring is semicircular, and the variable diameter spring is symmetrically arranged at both ends of the locking retaining ring.

4. The double-needle thermocouple temperature measuring device with in-plane deformation adaptation according to claim 1, characterized in that: The relationship between the screw-in amount Δh of the adjusting screw and the spring coefficient and contact pressure of the variable diameter spring symmetrically distributed on both sides of the locking retaining ring is expressed as follows: Among them, F u is the maximum regulated contact pressure in the surface, F d is the minimum adjustment contact pressure in the surface, k1 is the spring constant on the first thermocouple needle close to the upper radial constraint plate, and k2 is the spring constant close to the measuring end.

5. The double-needle thermocouple temperature measuring device with in-plane deformation adaptation according to claim 1 or 4, characterized in that: The thermocouple needle moves under the action of the contact pressure. At this time, the expression of the contact pressure F1' on the first thermocouple needle is: Among them, F1 is the size of the contact pressure on the first thermocouple needle before material deformation, F1' is the size of the contact pressure on the first thermocouple needle after material deformation, k1 is the spring stiffness coefficient of the first thermocouple needle close to the upper radial constraint plate, k2 is the spring stiffness coefficient close to the measuring end, α1 is the inclination angle between the actual displacement length of the material and the center axis of the device, △h is the screw-in amount of the adjusting screw, r is the radius of the cross section of the thermocouple needle, L is the maximum length of the thermocouple needle, and z1 is the actual displacement length of the first thermocouple needle during the test.

6. The double-needle thermocouple temperature measuring device with in-plane deformation adaptation according to claim 1 or 4, characterized in that: The thermocouple needle moves under the action of the contact pressure. At this time, the expression of the contact pressure F2' on the second thermocouple needle is: Among them, F2 is the contact pressure on the second thermocouple needle before material deformation, k3 is the spring stiffness coefficient of the second thermocouple needle close to the upper radial constraint plate, k4 is the spring stiffness coefficient close to the measuring end, △h is the screw-in amount of the adjusting screw, r is the radius of the cross section of the thermocouple needle, L is the maximum length of the thermocouple needle, and z2 is the actual displacement length of the second thermocouple needle during the test.

7. A method for using the in-plane deformation adaptive double-needle thermocouple temperature measuring device according to any one of claims 1 to 6, characterized in that: The specific steps are as follows: S1. First, thread the flange sleeve and the lower end of the housing together, then position and fit the lower radial constraint sheet, the variable diameter spring, the thermocouple needle, the locking retaining ring, the upper radial constraint sheet and the positioning needle in sequence, finally insert the axial constraint collar, and install the top end cover to complete the assembly; S2. Perform preliminary positioning by adjusting the screws and fix the double-needle thermocouple temperature measuring device at the test position; S3, placing the extended ends of the first thermocouple needle and the second thermocouple needle in the double-needle thermocouple temperature measuring device against the predetermined temperature measurement positions of the measured material, and setting the contact pressure of the measured material by changing the screwing depth of the adjusting screw; S4. Connect the positive terminal connected to the first thermocouple needle and the negative terminal connected to the second thermocouple needle, apply a certain test force to the material under test and conduct a test. During the test, continuously measure and record the span temperature data.

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