A spot welding process for preventing deformation of automobile parts during production

Abstract

The invention relates to the field of automobile spot welding, and discloses a spot welding process for preventing automobile parts from being deformed during production, comprising the following steps: S1, calculating the distance between adjacent parts after welding is completed; S2, using thermodynamics to calculate the heat input and heat conduction range generated by the parts during welding, and estimating the heating range generated by each part on the automobile floor during welding; S3, finding out the area with overlapping heating ranges; S4, using a heat-conducting clamp to clamp the area with overlapping heating ranges on the automobile floor; S5, adjusting the clamping force of the clamp based on the temperature of the area with overlapping heating ranges on the automobile floor, and using the clamp to fix the automobile floor, so as to dissipate heat in the area with overlapping heating ranges, so that the automobile floor dissipates heat in time after each heating, and can alleviate the embrittlement problem to a certain extent.

Description

Technical Field

[0001] The invention relates to the field of automobile spot welding, and in particular to a spot welding process for preventing automobile parts from being deformed during production. Background Art

[0002] When welding automotive parts, fixtures are usually used to fix the workpieces and parts to ensure that they do not move or deform during the welding process. However, the location of the fixture is usually designed to be away from the weld to avoid direct clamping in the heat area.

[0003] However, in some welding conditions, the fixture inevitably needs to be clamped to the heating area. This situation is usually due to complex structure, high welding precision requirements or process limitations. For example, when performing multi-layer welding on the car floor, specifically welding multiple layers of steel plates or multiple layers of materials on the car floor, the car floor itself is relatively thin, its thickness is usually 0.7-3mm, and the welding precision requirements are high. In order to avoid misalignment, the fixture should be as close to the welding point as possible to clamp the car floor, that is, in the above case, the clamping area of ​​the fixture will be restricted to the first layer, and because there are multiple parts that need to be welded on the car floor, in this case, the clamping area of ​​the fixture will be restricted to the second layer, making the clamping area of ​​the fixture extremely limited. Therefore, there is the above situation where the fixture needs to be clamped in the heating area, and because there are many parts that need to be welded, in the process of welding different parts, the heating areas corresponding to different parts will overlap, and repeated heating will also affect the microstructure of the car floor and reduce the fatigue resistance.

[0004] Current clamps usually ignore the possibility of heat expansion in the heating area and maintain the original clamping distance to clamp the car floor. As the heating area expands due to heat and increases in volume, the heating area will be compressed if the clamp spacing remains unchanged, which will cause surface damage to the heating area and even cause permanent deformation of the clamp or the heating area. Even if there are some automatic control means to adjust the clamping distance of the clamp, there is still a lack of effective means to reduce the impact of repeated heating on the car floor for overlapping heating areas. Summary of the invention

[0005] The purpose of the present invention is to provide a spot welding process for preventing automobile parts from being deformed during production to solve the above technical problems. The specific technical solution is as follows:

[0006] A spot welding process for preventing deformation of automobile parts during production is applied to welding parts on the floor of an automobile, comprising the following steps:

[0007] S1. Calculate the distance between adjacent parts after welding according to the predetermined welding positions of each part;

[0008] S2. Based on the material of the automobile floor, the heat input and heat conduction range generated by the parts during the welding process are calculated using thermodynamics, and the heat generation range generated by each part on the automobile floor during the welding process is estimated;

[0009] S3, comparing the estimated heating range of each component with the distance between adjacent components to find out the area where the heating range overlaps;

[0010] S4. Use a heat-conducting fixture to clamp the area of ​​the car floor where the heating range overlaps;

[0011] S5. Adjust the clamping distance of the clamp based on the temperature of the area where the heating range of the automobile floor overlaps, and then weld the parts to the automobile floor.

[0012] Preferably, in S4, a temperature sensor is arranged on the clamp to continuously detect the temperature of the area where the heating range of the automobile floor overlaps, and S5 adjusts the clamping distance of the clamp according to the temperature detected by the temperature sensor in S4.

[0013] Preferably, in S4, the fixture is provided with a heat-conducting metal block, one end surface of the heat-conducting metal block is used to contact the car floor, and the other end surface of the heat-conducting metal block is used to connect to the heat dissipation fins.

[0014] Preferably, in S4, a fan is further configured to assist the heat sink fins in heat dissipation, and the speed of the fan is adjusted according to the temperature detected by the temperature sensor, so that the temperature of the area where the heating range of the car floor overlaps continues to drop.

[0015] Preferably, in S4, a control module is further configured, and the clamp, temperature sensor and fan are respectively connected to the control module by signals.

[0016] Preferably, the temperature data T1 detected by the temperature sensor is uploaded to the control module, and the control module is pre-input with the temperature data T. When the control module determines that T1 exceeds T, the control module adjusts the fan to increase the air output power.

[0017] Preferably, the standard air output power of the fan is defined as a value P1, the value P1 corresponds to the temperature data T pre-input by the control module, and the actual air output power of the fan is defined as a value P2.

[0018] Among them, P2 = (T1 / T)×P1.

[0019] Preferably, the predetermined spacing reserved by the clamp for clamping the automobile floor is defined as X, and the clamping spacing actually used by the clamp for clamping the automobile floor is defined as X1.

[0020] Among them, X1=(T1 / T)×X.

[0021] Preferably, in S5, the clamp starts to adjust the clamping distance of the automobile floor to X1 only when the temperature data T1 value increases and the heating time T2 has passed.

[0022] Preferably, the clamp comprises a movable upper clamping part and a fixed lower clamping part, the upper clamping part is hinged to the lower clamping part, and the heat-conducting metal block is arranged on the lower clamping part.

[0023] The beneficial effects of the present invention are as follows: the use of a heat-conducting clamp is because timely heat dissipation helps to control the temperature variation range of the material and reduce the influence of thermal fatigue. Therefore, the clamp is used to fix the automobile floor and to dissipate heat in the area where the heating range overlaps, so that the automobile floor dissipates heat in time after each heating, which can alleviate the embrittlement problem to a certain extent; the speed of the fan is adjusted according to the temperature detected by the temperature sensor, so that the temperature of the area where the heating range of the automobile floor overlaps continues to decrease, avoiding the residual stress inside the metal caused by rapid cooling, which causes the automobile floor to deform or even crack.

[0024] Additional aspects and advantages of the present invention will be given in part in the description below, and in part will become apparent from the description below, or will be understood through the practice of the present invention. Of course, it is not necessary to achieve all of the advantages described above at the same time to implement any product or method of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 It is a structural schematic diagram of the present invention.

[0027] Figure 2 It is a schematic structural diagram of the clamp of the present invention.

[0028] In the figure: 1. clamp; 2. heat-conducting metal block; 3. fan; 11. upper clamping part; 12. lower clamping part; 13. cylinder; 21. heat dissipation fins. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] The existing clamp 1 usually ignores the possibility of heat expansion in the heating area and maintains the original clamping distance to clamp the car floor. As a result, after the heating area expands due to heat, the heating area will be compressed, causing surface damage to the heating area, and even causing permanent deformation of the clamp 1 or the heating area. There is a lack of effective means to reduce the impact of repeated heating on the car floor. Please refer to Figure 1-2 The present invention provides an embodiment to solve the above problem, which specifically includes the following steps:

[0032] S1. Calculate the distance between adjacent parts after welding according to the predetermined welding positions of each part. Generally, multiple parts need to be welded on the car floor, and before welding, the positions of each part are determined in advance on the relevant design drawings. Based on these position information, the distance between adjacent parts after welding can be calculated to facilitate the subsequent confirmation of the heat generation area of ​​each part on the car floor during the welding process.

[0033] S2. Based on the material of the automobile floor, thermodynamics is used to calculate the heat input and heat conduction range generated by the parts during the welding process. Specifically, the heat formula is used in combination with Fourier's law to calculate the conduction of welding heat and the relevant values ​​of the material thermal diffusion efficiency are introduced. Then, the distribution of the temperature field during the welding process can be estimated, and then the heat conduction range can be obtained. In the actual calculation process, numerical simulation and finite element analysis can also be used to calculate the temperature field and heat conduction range during the welding process. A welding model can be established through software (such as ANSYS, ABAQUS, etc.), and welding parameters and material thermal properties can be input to perform numerical solutions, thereby obtaining the range of heat generated by each part on the automobile floor during the welding process;

[0034] S3. After clarifying the corresponding heating ranges generated by each part on the automobile floor during the welding process, the estimated heating ranges of each part are compared with the distances between adjacent parts to find out the areas where the heating ranges overlap. Furthermore, markings can be made in the areas where the heating ranges overlap to facilitate the subsequent clamping with the fixture 1.

[0035] S4. A heat-conducting clamp 1 is used to clamp the area of ​​the automobile floor where the heating range overlaps. The heat-conducting clamp 1 is used because timely heat dissipation helps to control the temperature change range of the material and reduce the impact of thermal fatigue. Therefore, the clamp 1 is used to fix the automobile floor and to dissipate heat in the area where the heating range overlaps, so that the automobile floor can dissipate heat in time after each heating, which can alleviate the embrittlement problem to a certain extent.

[0036] S5. Adjust the clamping distance of the clamp 1 based on the temperature of the area where the heating range overlaps on the car floor. It is understandable that the above area will expand due to heat, so it is necessary to detect the area where the heating range overlaps in real time and adjust the clamping distance of the clamp 1 according to the temperature of the area to avoid permanent deformation of the clamp 1 or the heating area, and finally weld the parts to the car floor.

[0037] In the above S4 and S5, in order to ensure that the clamp 1 can detect the temperature of the car floor or the clamped area in real time, a temperature sensor is configured on the clamp 1, and the temperature sensor is used to continuously detect the temperature of the area where the heating range of the car floor overlaps. S5 adjusts the clamping distance of the clamp 1 according to the temperature detected by the temperature sensor of S4. The specific implementation steps are:

[0038] A control module is installed on the fixture 1, and the fixture 1 and the temperature sensor are respectively connected to the control module signal. The fixture 1 is configured to reserve a clamping distance matching the car floor, and the temperature sensor is set on the fixture 1. When the fixture 1 clamps the car floor, the temperature sensor will abut or contact the car floor. The temperature sensor will detect the temperature in real time and generate corresponding data to upload to the control module. The control module adjusts the clamping distance of the fixture 1 according to the data uploaded by the temperature sensor. Specifically:

[0039] The temperature data T1 detected by the temperature sensor is uploaded to the control module. The control module is pre-input with the temperature data T. The predetermined spacing reserved by the clamp 1 for clamping the car floor is defined as X, and the actual clamping spacing of the clamp 1 for clamping the car floor is defined as X1.

[0040] Where, X1=(T1 / T)×X;

[0041] It can be understood that when the temperature data T1 detected by the temperature sensor increases, the control module will control the clamp 1 to increase the clamping distance to X1, to ensure that the clamped area (that is, the heating area or the area where the heating range overlaps) will not be compressed due to the thermal expansion of the clamped area, thereby avoiding permanent deformation of the clamped area (that is, the heating area or the area where the heating range overlaps) or the clamp 1;

[0042] Preferably, in consideration of heat transfer during the welding process, a heating time T2 needs to be introduced, which requires that the temperature data T1 value becomes larger and after the heating time T2, the clamp 1 starts to adjust the clamping distance of the automobile floor to X1. It can be understood that when the automobile floor is welded to the parts, the surface of the automobile floor will heat up first, and in order to make the heated area expand due to heat, it usually takes a period of heating to occur. Therefore, it is necessary to design the heating time T2 to avoid the clamp 1 from clamping empty space.

[0043] Regarding the heat conduction of the clamp 1: specifically, a heat-conducting metal block 2 is arranged on the clamp 1, and one end surface of the heat-conducting metal block 2 is used to contact the car floor, and the other end surface of the heat-conducting metal block 2 is used to connect the heat dissipation fins 21. By arranging the heat-conducting metal block 2, heat can be dissipated in time. Repeated heating and cooling will cause thermal expansion and contraction, generate thermal stress, and may form micro cracks inside the material. Over time, the material will become brittle. By dissipating heat in time, the temperature change amplitude of the material can be reduced, the thermal stress can be reduced, and the embrittlement caused by thermal fatigue can be slowed down. Timely heat dissipation can prevent the material from staying at high temperature for a long time and reduce the chance of phase change.

[0044] Preferably, in S4, a fan 3 is also configured to assist the heat dissipation fins 21 in heat dissipation. The rotation speed of the fan 3 is adjusted according to the temperature detected by the temperature sensor, so that the temperature of the area where the heating range of the car floor overlaps continues to drop. The temperature sensor and the fan 3 are respectively connected to the control module signal.

[0045] The heat dissipation efficiency can be improved by setting the fan 3. However, in this embodiment, the air volume of the fan 3 is also strictly limited. It is understandable that if the air volume of the fan 3 is always maintained at a high level, the car floor will be cooled very quickly, and the car floor will be cooled quickly. Rapid cooling usually causes residual stress inside the metal. Because the cooling speeds of the surface and the inside of the material are different during the cooling process, the surface layer will shrink first due to the faster cooling, while the inside will shrink later due to the slower cooling. This uneven stress distribution will cause the car floor to deform or even crack. Therefore, it is necessary to adjust the air volume of the fan 3. When using the fan 3 to assist in heat dissipation, higher requirements are also put forward for the air volume control of the fan 3, that is, the air volume of the fan 3 must match the temperature of the car floor to ensure that the heating area on the car floor or the area overlapping the heating range generated during the welding of parts will not cool quickly, but a relatively stable trend will allow the temperature to gradually decrease. The specific implementation method is as follows:

[0046] The temperature sensor uploads the detected temperature data T1 to the control module. The control module is pre-input with the temperature data T. When the control module determines that T1 exceeds T, the control module adjusts the fan 3 to increase the air output power. The standard air output power of the fan 3 is defined as the value P1. The value P1 corresponds to the temperature data T pre-input by the control module. The actual air output power of the fan 3 is defined as the value P2.

[0047] Among them, P2 = (T1 / T)×P1.

[0048] It can be understood that the actual air output power of fan 3 is the value P2, which will directly affect the air output volume of fan 3, and thus affect the heat dissipation effect. By introducing the above calculation formula, it can be ensured that the actual air output power of fan 3 is the value P2 and increases with the increase of temperature data T1, or the actual air output power of fan 3 is the value P2 and decreases with the decrease of temperature data T1, thereby achieving that the rotation speed of fan 3 is adjusted according to the temperature detected by the temperature sensor, so that the temperature of the area where the heating range of the car floor overlaps continues to decrease.

[0049] In this embodiment, the clamp 1 includes a movable upper clamping portion 11 and a fixed lower clamping portion 12. The upper clamping portion 11 is hinged to the lower clamping portion 12, and the heat-conducting metal block 2 is arranged on the lower clamping portion 12. The reason for limiting the heat-conducting metal block 2 to the fixed lower clamping portion 12 is to cooperate with the fan 3 for heat dissipation. Generally, the lower clamping portion 12 of the clamp 1 for clamping the car floor is usually fixed. Based on the above characteristics, the advantage of arranging the heat-conducting metal block 2 on the lower clamping portion 12 is that if the heat-conducting metal block 2 is arranged on the upper clamping portion 11, it will increase The overall weight of the upper clamping part 11 means that a greater force is required to drive the upper clamping part 11, and the upper clamping part 11 and the lower clamping part 12 must be kept in a clamping state to achieve the heat dissipation effect. As for the lower clamping part 12, as long as the car floor is placed on the lower clamping part 12, under the influence of gravity, the car floor itself will fit with the heat-conducting metal block 2, and even if no clamping occurs, it can still play a heat dissipation role. Preferably, the clamp 1 includes a cylinder 13 for driving the upper clamping part 11, and the cylinder 13 is connected to the upper clamping part 11.

[0050] It should be noted that the terms "first", "second", etc. in this document are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0051] 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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A spot welding process for preventing deformation of automobile parts during production, which is applied to welding parts on the floor of an automobile, characterized in that: The following steps are involved: S1. Calculate the distance between adjacent parts after welding according to the predetermined welding positions of each part; S2. Based on the material of the automobile floor, the heat input and heat conduction range generated by the parts during the welding process are calculated using thermodynamics, and the heat generation range generated by each part on the automobile floor during the welding process is estimated; S3, comparing the estimated heating range of each component with the distance between adjacent components to find out the area where the heating range overlaps; S4, using a heat-conducting fixture to clamp the area of ​​the automobile floor where the heating range overlaps. Specifically, a temperature sensor is configured on the fixture to continuously detect the temperature of the area of ​​the automobile floor where the heating range overlaps; S5. Adjust the clamping distance of the clamp based on the temperature of the area where the heating range of the automobile floor overlaps, and then weld the parts to the automobile floor. S5 adjusts the clamping distance of the clamp according to the temperature detected by the temperature sensor of S4.

2. A spot welding process for preventing automobile parts from being deformed during production according to claim 1, characterized in that: In S4, the fixture is provided with a heat-conducting metal block, one end surface of the heat-conducting metal block is used to contact the car floor, and the other end surface of the heat-conducting metal block is used to connect to the heat dissipation fins.

3. A spot welding process for preventing automobile parts from being deformed during production according to claim 2, characterized in that: In the S4, a fan is further configured to assist the heat dissipation fins in heat dissipation, and the speed of the fan is adjusted according to the temperature detected by the temperature sensor, so that the temperature of the area where the heating range of the car floor overlaps continues to drop.

4. A spot welding process for preventing automobile parts from being deformed during production according to claim 3, characterized in that: In S4, a control module is further configured, and the fixture, temperature sensor and fan are respectively connected to the control module by signals.

5. A spot welding process for preventing automobile parts from being deformed during production according to claim 4, characterized in that: The temperature data T1 detected by the temperature sensor is uploaded to the control module. The control module is pre-input with the temperature data T. When the control module determines that T1 exceeds T, the control module adjusts the fan to increase the air output power.

6. A spot welding process for preventing automobile parts from being deformed during production according to claim 5, characterized in that: The standard air output power of the fan is defined as a value P1, the value P1 corresponds to the temperature data T pre-input by the control module, and the actual air output power of the fan is defined as a value P2, Among them, P2=(T1 / T)×P1.

7. A spot welding process for preventing automobile parts from being deformed during production according to claim 6, characterized in that: Define the predetermined spacing reserved by the clamp for clamping the car floor as X and the actual clamping spacing of the clamp for clamping the car floor as X1, Among them, X1=(T1 / T)×X.

8. A spot welding process for preventing automobile parts from being deformed during production according to claim 7, characterized in that: In S5, the clamp starts to adjust the clamping distance of the automobile floor to X1 only when the temperature data T1 value increases and the heating time T2 has passed.

9. A spot welding process for preventing automobile parts from being deformed during production according to claim 8, characterized in that: The clamp comprises a movable upper clamping part and a fixed lower clamping part, the upper clamping part is hinged to the lower clamping part, and the heat-conducting metal block is arranged on the lower clamping part.

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