A method for measuring the indentation depth of resistance spot weld nuggets

Abstract

This invention discloses a method for measuring the indentation depth of resistance spot weld nuggets, comprising the following steps: Step 1, equipment assembly; Step 2, sample fixing; Step 3, plate clamping; Step 4, weld nugget contact; Step 5, data analysis; Step 6, modeling analysis. This invention utilizes the piezoelectric properties of piezoelectric ceramics to convert voltage into pressure, and then uses that pressure to convert it into spring contraction, thereby detecting the indentation depth. After processing by a signal processor and modeling, it can achieve comprehensive measurement of the indentation depth in the weld nugget area. During the test, the movable pressure plate and fixed magnetic suction plate, combined with the detection movement of the detection housing, achieve the clamping function of the plate, preventing plate displacement during the detection process and thus improving detection accuracy. The upper and lower sets of tapered rods allow for the measurement of the indentation depth of individual steel plates after resistance spot welding of steel plates of different thicknesses and strengths, improving the practicality of the measurement method.

Description

Technical Field

[0001] This invention relates to the field of resistance welding technology, specifically a method for measuring the depth of indentation in resistance spot welding. Background Technology

[0002] In automobile body manufacturing, welding includes components such as the body floor, side panels, frame, and body assembly. Resistance spot welding is extensively used in the welding process. There are thousands of weld points on the vehicle body, and their performance significantly affects the vehicle's durability and crashworthiness. Therefore, the performance of resistance spot welding is particularly important. The depth of the weld indentation affects the mechanical properties of the weld point and is one of the important indicators for evaluating welding quality. Currently, the measurement methods mainly include two types: 1. Based on standard recommendations, the weld nugget is cut along a cross-section using wire cutting, the cross-section is ground smooth, and then the depth is measured using a wire cutter. The depth of weld indentation can be measured using calipers. For thinner steel plates, it is more accurate to measure the depth of weld indentation under a microscope after cutting it open. Alternatively, a thickness gauge can be used to measure the thickness of the plate. However, the first method, which involves cutting open the weld, is time-consuming and labor-intensive. The second method uses a thickness gauge with sensitive measuring contacts, which is more suitable for measuring the thinning rate of flat plates during stamping. However, the contacts are precise, and the surface of the weld is uneven. Under high welding current, burrs may form on the surface due to spatter, which can easily damage the contacts. Therefore, this equipment is generally not used for measuring the depth of weld indentation.

[0003] Chinese patent document CN206037907U (application number 201621089351.5) discloses "a device for measuring the depth of weld indentation", which includes a main scale and a vernier scale mounted on the main scale. The vernier scale can slide along the length direction of the main scale. The main scale is provided with a fixed measuring claw, and the vernier scale is provided with a movable measuring claw. The fixed measuring claw is provided with a first measuring head, and the movable measuring claw is provided with a second measuring head. The first measuring head and the second measuring head are arranged opposite to each other, and the opposite ends of the first measuring head and the second measuring head are both sharp. When the vernier scale slides, the ends of the first measuring head and the second measuring head come into contact.

[0004] The aforementioned patent has the following shortcomings: First, based on a vernier caliper, with the addition of a movable measuring jaw and a measuring head structure, it can only measure the total depth of a single weld nugget indentation at a time, and cannot measure the depth and positional distribution of the entire weld nugget; Second, it cannot measure the depth of weld nugget indentations after resistance spot welding of steel plates of different thicknesses and strengths, which affects the practicality of the measurement method; Therefore, it is necessary to design a method for measuring the depth of resistance spot welding weld nugget indentations. Summary of the Invention

[0005] The purpose of this invention is to provide a method for measuring the depth of indentation in resistance spot welding, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for measuring the indentation depth of resistance spot welding weld nuggets, comprising the following steps: Step 1, equipment assembly; Step 2, sample fixing; Step 3, plate clamping; Step 4, weld nugget contact; Step 5, data analysis; Step 6, modeling analysis;

[0007] In step one above, firstly, the connecting plate is fitted onto the slide rod. Then, one end of the connecting rod is hinged to the connecting plate, and the other end of the connecting rod is hinged to the turntable. Next, the turntable and slide rod are installed inside the structural bracket. Then, the motor is fixed on the outside of the structural bracket, so that the output end of the motor is fixedly fitted onto the turntable. Then, the detection assembly consisting of the detection housing, tapered rod, clamping spring and piezoelectric ceramic is fixed on the connecting plate. Next, the connecting piece, clamping spring and movable pressure plate are installed on the top detection housing. The electric telescopic rod and fixed magnetic suction plate are installed on one side of the top of the equipment base. Then, the structural bracket is fixed on the other side of the top of the equipment base, completing the assembly process of the measuring equipment.

[0008] In step two above, one end of the sample is placed on the fixed magnetic plate, the weld nugget is located between the upper and lower detection components, and then the fixed magnetic plate is moved up and down by controlling the electric telescopic rod to change the clamping height so that the welding joint surface of the two plates coincides with the detection center surface.

[0009] In step three above, the turntable is driven by a motor to rotate, causing the two sets of detection components to move closer to each other. The upper detection component moves the movable pressure plate down through the connector and the clamping spring, thereby clamping the plate with the fixed magnetic suction plate. Then the turntable continues to rotate, causing the conical rods in the two sets of detection components to approach the plate and the weld nugget from the top and bottom directions respectively.

[0010] In step four above, when the two sets of tapered rods come into contact with the weld nugget of the plate, the signal processor receives the voltage signal of the piezoelectric ceramic and calculates the initial shrinkage based on the voltage signal.

[0011] In step five above, the voltage signal obtained in step four is processed. The voltage corresponding to the weld nugget area is identified by the signal processor. The pressure corresponding to the piezoelectric ceramic is calculated based on this voltage. The shrinkage amount is calculated based on the elastic modulus of the clamping spring. The indentation depth is obtained by subtracting the shrinkage amount from the initial shrinkage amount obtained in step four.

[0012] In step six above, a three-dimensional model is created based on the indentation depth calculated in step five, and multiple points are bridged to form a surface to achieve measurement of the entire indentation area.

[0013] Preferably, in step one, the connecting plate, slide bar, connecting rod, motor, and turntable serve as the centering drive components of the equipment. The motor drives the connecting rod to rotate, thereby using the connecting rod to drive the connecting plate and detection components to move closer to the horizontal plane where the turntable axis is located.

[0014] Preferably, in step one, the detection housing is fixed to the connecting plate as a protective support for the tapered rod, the clamping spring, and the piezoelectric ceramic. The tapered rod, the clamping spring, and the piezoelectric ceramic are all installed in the through grooves evenly opened on the detection housing. The piezoelectric ceramic is fixed at the bottom of the through groove, and the tapered rod is slidably connected in the through groove. The clamping spring is located between the tapered rod and the piezoelectric ceramic, elastically connecting the tapered rod and the piezoelectric ceramic.

[0015] Preferably, in step one, the connector is fixed to the top detection housing, and the bottom and top ends of the compression spring are fixed to the movable pressure plate and the connector, respectively, so that the movable pressure plate and the connector are elastically connected.

[0016] Preferably, in step one, the electric telescopic rod is symmetrically arranged on the equipment base as the lifting drive for the fixed magnetic plate. The connector, the compression spring, the movable pressure plate, the fixed magnetic plate, and the electric telescopic rod together form the clamping assembly of the equipment to fix and clamp the sample during the measurement process.

[0017] Preferably, in step two, the horizontal plane where the detection center plane is located coincides with the horizontal plane where the rotation axis of the turntable is located.

[0018] Preferably, in step three, the voltage of the piezoelectric ceramic is zero before the tapered rod contacts the weld nugget.

[0019] Preferably, in step four, the calculation process for the initial shrinkage amount is as follows: First, the voltage corresponding to the plate is identified by the signal processor, and the pressure corresponding to the piezoelectric ceramic is calculated based on this voltage. Then, the shrinkage amount is calculated based on the elastic modulus of the tightening spring. This shrinkage amount is the initial shrinkage amount.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This method for measuring the indentation depth of resistance spot welding weld nuggets utilizes the piezoelectric properties of piezoelectric ceramics to convert voltage into pressure, and then uses the pressure to convert it into spring contraction, thereby detecting the indentation depth. After processing by a signal processor and modeling, it can achieve omnidirectional measurement of the indentation depth of the weld nugget area. During the test, the movable pressure plate and the fixed magnetic suction plate are combined with the detection movement of the detection shell to achieve the clamping function of the plate, preventing the plate from shifting during the detection process, thereby improving the detection accuracy. Through the setting of two sets of upper and lower tapered rods, it is possible to measure the indentation depth of a single steel plate weld nugget after resistance spot welding of steel plates of different thicknesses and strengths, thus improving the practicality of the measurement method. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method of the present invention;

[0022] Figure 2 This is a three-dimensional diagram of the overall structure of the measuring device in this invention;

[0023] Figure 3 This is a three-dimensional view of the detection housing in the measuring device of the present invention;

[0024] Figure 4 This is a schematic diagram showing the position of the tapered rod in the measuring device of the present invention;

[0025] Figure 5 This is a schematic diagram showing the position of the turntable in the measuring device of the present invention;

[0026] Figure 6 This is a three-dimensional diagram of part of the structure of the measuring device of the present invention;

[0027] In the diagram: 1. Equipment base; 2. Structural support; 3. Centering drive assembly; 4. Detection assembly; 5. Clamping assembly; 6. Detection housing; 7. Tapered rod; 8. Top spring; 9. Piezoelectric ceramic; 10. Connecting plate; 11. Slide rod; 12. Connecting rod; 13. Motor; 14. Turntable; 15. Connector; 16. Compression spring; 17. Movable pressure plate; 18. Fixed magnetic suction plate; 19. Electric telescopic rod. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Please see Figure 1-6 The present invention provides an embodiment of a method for measuring the indentation depth of resistance spot welding nuggets, comprising the following steps: Step 1, equipment assembly; Step 2, sample fixing; Step 3, plate clamping; Step 4, weld nugget contact; Step 5, data analysis; Step 6, modeling analysis.

[0030] In step one above, firstly, the connecting plate 10 is fitted onto the slide rod 11. Then, one end of the connecting rod 12 is hinged to the connecting plate 10, and the other end of the connecting rod 12 is hinged to the turntable 14. Next, the turntable 14 and the slide rod 11 are installed inside the structural support 2. Then, the motor 13 is fixed to the outside of the structural support 2, with the output end of the motor 13 fixedly fitted onto the turntable 14. The connecting plate 10, slide rod 11, connecting rod 12, motor 13, and turntable 14 serve as the centering drive assembly 3 of the equipment. The motor 13 drives the connecting rod 12 to rotate, which in turn drives the connecting plate 10 and the detection assembly 4 to move closer to the horizontal plane where the axis of the turntable 14 is located. Then, the detection assembly 4, consisting of the detection housing 6, the tapered rod 7, the clamping spring 8, and the piezoelectric ceramic 9, is fixed to the connecting plate 10. The detection housing 6 serves as a protective support for the tapered rod 7, the clamping spring 8, and the piezoelectric ceramic 9, and is fixed to the connecting plate 10. The tapered rod 7, the clamping spring 8, and the piezoelectric ceramic 9 are all evenly spaced on the detection housing 6. In the through groove, the piezoelectric ceramic 9 is fixed at the bottom of the through groove, and the tapered rod 7 is slidably connected in the through groove. The clamping spring 8 is located between the tapered rod 7 and the piezoelectric ceramic 9, elastically connecting the tapered rod 7 and the piezoelectric ceramic 9. Then, the connector 15, the clamping spring 16, and the movable pressure plate 17 are installed on the top detection housing 6. The connector 15 is fixed on the top detection housing 6, and the bottom and top ends of the clamping spring 16 are respectively fixed to the movable pressure plate 17 and the connector 15, elastically connecting the movable pressure plate 17 and the connector 15. Connect them together and install the electric telescopic rod 19 and the fixed magnetic suction plate 18 on one side of the top of the equipment base 1. The electric telescopic rod 19 is symmetrically arranged on the equipment base 1 as the lifting drive of the fixed magnetic suction plate 18. The connector 15, the compression spring 16, the movable pressure plate 17, the fixed magnetic suction plate 18 and the electric telescopic rod 19 together form the clamping assembly 5 of the equipment to fix and clamp the sample during the measurement process. Then, the structural bracket 2 is fixed on the other side of the top of the equipment base 1 to complete the assembly process of the measuring equipment.

[0031] In step two above, one end of the sample is placed on the fixed magnetic plate 18, and the weld nugget is located between the upper and lower sets of detection components 4. Then, the fixed magnetic plate 18 is moved up and down and extended by controlling the electric telescopic rod 19 to change the clamping height so that the welding joint surface of the two plates coincides with the detection center surface, and the horizontal plane where the detection center surface is located coincides with the horizontal plane where the rotation axis of the turntable 14 is located.

[0032] In step three above, the motor 13 drives the turntable 14 to rotate, causing the two sets of detection components 4 to approach each other. The upper detection component 4 drives the movable pressure plate 17 to descend through the connector 15 and the clamping spring 16, thereby cooperating with the fixed magnetic suction plate 18 to clamp the plate. Then, the turntable 14 continues to rotate, so that the conical rods 7 in the two sets of detection components 4 approach the plate and the weld nugget from the upper and lower directions respectively. Before the conical rods 7 contact the weld nugget, the voltage of the piezoelectric ceramic 9 is zero.

[0033] In step four above, when the two sets of tapered rods 7 come into contact with the weld nugget of the plate, the signal processor receives the voltage signal of the piezoelectric ceramic 9 and calculates the initial shrinkage amount based on the voltage signal. The calculation process of the initial shrinkage amount is as follows: First, the signal processor identifies the voltage corresponding to the plate and calculates the pressure corresponding to the piezoelectric ceramic 9 based on this voltage. Then, the shrinkage amount is calculated based on the elastic modulus of the tightening spring 8. This shrinkage amount is the initial shrinkage amount.

[0034] In step five above, the voltage signal obtained in step four is processed. The voltage corresponding to the weld nugget area is identified by the signal processor. The pressure corresponding to the piezoelectric ceramic 9 is calculated based on this voltage. The shrinkage amount is calculated based on the elastic modulus of the clamping spring 8. The indentation depth is obtained by subtracting the shrinkage amount from the initial shrinkage amount obtained in step four.

[0035] In step six above, a three-dimensional model is created based on the indentation depth calculated in step five, and multiple points are bridged to form a surface to achieve measurement of the entire indentation area.

[0036] Based on the above, the advantages of this invention are that it utilizes the piezoelectric properties of piezoelectric ceramic 9 to convert voltage into pressure, and then uses the pressure to convert it into spring contraction, thereby detecting the indentation depth. After processing by a signal processor and modeling, it can realize all-round measurement of the indentation depth of the weld nugget area. During the test, the movable pressure plate 17 and the fixed magnetic suction plate 18 are combined with the detection movement of the detection housing 6 to achieve the clamping function of the plate, preventing the plate from shifting during the detection process, thereby improving the detection accuracy. Through the upper and lower sets of tapered rods 7, it is possible to measure the indentation depth of a single steel plate weld nugget after resistance spot welding of steel plates of different thicknesses and strengths, thus improving the practicality of the measurement method.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for measuring the indentation depth of a resistance spot weld nugget, comprising the following steps: Step 1, equipment assembly; Step 2, sample fixing; Step 3, plate clamping; Step 4, weld nugget contact; Step 5, data analysis; Step 6, modeling analysis; Its features are: In step one above, firstly, the connecting plate (10) is fitted onto the slide rod (11), then one end of the connecting rod (12) is hinged onto the connecting plate (10), and the other end of the connecting rod (12) is hinged onto the turntable (14). Then, the turntable (14) and the slide rod (11) are installed inside the structural support (2). Next, the motor (13) is fixed to the outside of the structural support (2), so that the output end of the motor (13) is fixedly fitted onto the turntable (14). Then, the detection housing (6) is... The detection assembly (4), consisting of a tapered rod (7), a clamping spring (8), and a piezoelectric ceramic (9), is fixed on the connecting plate (10). Then, the connector (15), the clamping spring (16), and the movable pressure plate (17) are installed on the top detection housing (6). The electric telescopic rod (19) and the fixed magnetic suction plate (18) are installed on one side of the top of the equipment base (1). Then, the structural bracket (2) is fixed on the other side of the top of the equipment base (1) to complete the assembly process of the measuring equipment. In step two above, one end of the sample is placed on the fixed magnetic plate (18), and the weld nugget is located between the upper and lower detection components (4). Then, the fixed magnetic plate (18) is moved up and down by controlling the electric telescopic rod (19) to change the clamping height so that the welding joint surface of the two plates coincides with the detection center surface. In step three above, the motor (13) drives the turntable (14) to rotate, causing the two sets of detection components (4) to move closer to each other. The upper detection component (4) drives the movable pressure plate (17) to descend through the connector (15) and the clamping spring (16), thereby cooperating with the fixed magnetic suction plate (18) to clamp the plate. Then, the turntable (14) continues to rotate, so that the conical rods (7) in the two sets of detection components (4) approach the plate and the weld nugget from the upper and lower directions respectively. In step four above, when the two sets of tapered rods (7) come into contact with the weld nugget of the plate, the signal processor receives the voltage signal of the piezoelectric ceramic (9) and calculates the initial shrinkage based on the voltage signal. In step five above, the voltage signal obtained in step four is processed, the voltage corresponding to the weld nugget area is identified by the signal processor, the pressure corresponding to the piezoelectric ceramic (9) is calculated based on this voltage, and the shrinkage amount is calculated based on the elastic modulus of the tightening spring (8). The indentation depth is obtained by subtracting the shrinkage amount from the initial shrinkage amount obtained in step four. In step six above, a three-dimensional model is created based on the indentation depth calculated in step five, and multiple points are bridged to form a surface to achieve measurement of the entire indentation area. In step one, the detection housing (6) is fixed on the connecting plate (10) as a protective support for the tapered rod (7), the clamping spring (8) and the piezoelectric ceramic (9). The tapered rod (7), the clamping spring (8) and the piezoelectric ceramic (9) are all installed in the through grooves that are evenly opened on the detection housing (6). The piezoelectric ceramic (9) is fixed at the bottom of the through groove, and the tapered rod (7) is slidably connected in the through groove. The clamping spring (8) is located between the tapered rod (7) and the piezoelectric ceramic (9), elastically connecting the tapered rod (7) and the piezoelectric ceramic (9).

2. The method for measuring the indentation depth of resistance spot welds according to claim 1, characterized in that: In step one, the connecting plate (10), slide bar (11), connecting rod (12), motor (13) and turntable (14) serve as the centering drive assembly (3) of the equipment. The motor (13) drives the connecting rod (12) to rotate, and then the connecting rod (12) drives the connecting plate (10) and the detection assembly (4) to move closer to the horizontal plane where the axis of the turntable (14) is located.

3. The method for measuring the indentation depth of resistance spot welds according to claim 1, characterized in that: According to claim 1, the method for measuring the depth of the indentation of a resistance spot weld nugget is characterized in that: in step one, the connector (15) is fixed on the top detection housing (6), and the bottom and top ends of the compression spring (16) are respectively fixed on the movable pressure plate (17) and the connector (15), so that the movable pressure plate (17) and the connector (15) are elastically connected.

4. The method for measuring the indentation depth of resistance spot welds according to claim 1, characterized in that: In step one, the electric telescopic rod (19) is symmetrically arranged on the equipment base (1) as the lifting drive of the fixed magnetic suction plate (18). The connector (15), the compression spring (16), the movable pressure plate (17), the fixed magnetic suction plate (18) and the electric telescopic rod (19) together form the clamping assembly (5) of the equipment to fix and clamp the sample during the measurement process.

5. The method for measuring the indentation depth of a resistance spot weld nugget according to claim 1, characterized in that: In step two, the horizontal plane where the detection center plane is located coincides with the horizontal plane where the rotation axis of the turntable (14) is located.

6. The method for measuring the indentation depth of a resistance spot weld nugget according to claim 1, characterized in that: In step three, the voltage of the piezoelectric ceramic (9) is zero before the tapered rod (7) contacts the weld nugget.

7. The method for measuring the indentation depth of a resistance spot weld nugget according to claim 1, characterized in that: In step four, the calculation process of the initial shrinkage amount is as follows: First, the voltage corresponding to the plate is identified by the signal processor, and the pressure corresponding to the piezoelectric ceramic (9) is calculated based on this voltage. Then, the shrinkage amount is calculated based on the elastic modulus of the tightening spring (8). This shrinkage amount is the initial shrinkage amount.

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