Method for rapid non-destructive detection of welds of parts based on laser welding

Abstract

The application discloses a kind of based on laser welding part weld fast nondestructive testing method, to the part weld depth detection method includes: obtaining the laser welding power P corresponding to the part weld depth in a~ (a+b) Range;Select the same multiple different thickness test piece of part brand, obtain the test piece thickness t corresponding to the test piece back weld penetration degree reaches preset penetration rate under laser welding power P;Manufacture the test piece of thickness t, replace the test piece to be measured with laser welding, and obtain the weld depth of the test piece to be measured according to the penetration result of test piece back weld;Part weld offset detection method includes: selecting the part that has been welded, obtains the inner hole fitting circle by multi-section edge finding fitting to the inner hole of part;Then select a plurality of points on the weld surface of part to fit to obtain weld fitting circle, obtain part weld offset by comparing inner hole fitting circle and weld fitting circle.The application uses test piece to replace part, save cost and detection time, improve production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser welding detection, in particular to a part weld rapid non-destructive detection method based on laser welding. BACKGROUND

[0002] Laser welding is a kind of high-efficiency precision welding method using high-energy density laser beam as heat source, and is one of the main connection technologies of automobile gearbox gear assembly and is widely used. Laser welding detection is an indispensable process after laser welding, and the two important evaluation indexes in laser welding detection are weld depth and weld offset. In the application of gear laser welding (such as shown in the figure), weld depth and weld offset are the two most important parameters that directly affect the torque bearing capacity of the gear. However, with the continuous work of the laser welding machine, the metal vapor and spatter in the weld pool will pollute the glass protective lens and reduce the light transmittance, and the effective power acting on the welding position will decrease, which will lead to insufficient weld depth and cause scrap. In addition, due to the pollution of the protective lens, the protective lens will absorb part of the laser, causing the polluted part of the protective lens to generate high temperature under laser irradiation, resulting in temperature difference on the protective lens and deformation, which will cause the light path to deviate, and the weld offset will be too large, exceeding the design requirement, which will reduce the effective weld depth of the part and decrease the torque bearing capacity. Figure 1

[0003] For laser welding detection technology, most of the current methods are metallographic cutting destructive detection to detect weld depth and weld offset.

[0004] The metallographic cutting destructive detection mainly has the following two problems:

[0005] ① High cost, the part cannot be used again after cutting;

[0006] ② The destructive detection process is long, and the production cannot continue until the detection result is obtained, which affects the production efficiency. SUMMARY

[0007] In view of the problems in the prior art, one of the purposes of the present application is to provide a part weld rapid non-destructive detection method based on laser welding, and another purpose of the present application is to provide a part weld offset rapid non-destructive detection method based on laser welding, to solve the problems of the current metallographic cutting destructive detection of weld depth and weld offset.

[0008] To solve the above technical problems, the present application realizes the following technical scheme:

[0009] A part weld rapid non-destructive detection method based on laser welding, which comprises rapid non-destructive detection of part weld depth, comprising the following steps:

[0010] ​S1, obtaining a laser welding power P corresponding to a weld depth of the part in a range of a to (a+b); wherein a is a minimum weld depth requirement value of the part;

[0011] S2, selecting a plurality of test pieces of different thicknesses of the same part brand as the part, and obtaining a test piece thickness t corresponding to a penetration rate of a back weld of the test piece reaching a preset penetration rate under the laser welding power P, the preset penetration rate being less than 100%;

[0012] S3, making a test piece of thickness t of the same part brand as the part to be tested, and replacing the part to be tested with the test piece for laser welding, and obtaining a weld depth of the part to be tested according to a penetration result of the back weld of the test piece:

[0013] Result one, when the penetration degree of the back weld of the test piece reaches the preset penetration rate, the weld depth of the part to be tested is in the range of a to (a+b);

[0014] Result two, when the penetration degree of the back weld of the test piece is 100%, the weld depth of the part to be tested is greater than a to (a+b);

[0015] Result three, when the back of the test piece is not penetrated by the weld, the weld depth of the part to be tested is less than a to (a+b);

[0016] Result four, when the penetration degree of the back weld of the test piece is less than the preset penetration rate, the weld depth of the part to be tested is less than a to (a+b).

[0017] Preferably, based on the penetration result of the back weld of the test piece obtained in step S3, the adjustment method of the laser welding process comprises:

[0018] When the penetration result of the back weld of the test piece is result one, it indicates that the laser welding power barely meets the weld depth requirement of the part, and the laser welding power needs to be appropriately increased;

[0019] When the penetration result of the back weld of the test piece is result two, it indicates that the laser power can meet the weld depth requirement of the part, and the laser welding power does not need to be changed;

[0020] When the penetration result of the back weld of the test piece is result three or result four, it indicates that the laser welding power cannot meet the weld depth requirement of the part, and the machine needs to be stopped for inspection and replacement of the protective lens.

[0021] Preferably, in step S1, 0

[0022] Preferably, in step S2, the preset penetration rate is 80-95%. Further preferably, the preset penetration rate is 90%.

[0023] Preferably, in step S2, a < test piece thickness < a + c, where a is the minimum weld depth requirement for the part, and 0 < c < 0.5 mm.

[0024] Preferably, it also includes rapid non-destructive testing of weld offset of the part, including:

[0025] Select the welded parts, perform multi-segment edge matching on the inner hole of the parts to obtain the fitting circle of the inner hole of the parts, and keep the parts stationary after fitting.

[0026] Then, multiple points are uniformly selected along the circumference of the weld surface of the part to obtain the weld fitting circle of the part. The inner hole fitting circle and the weld fitting circle are compared in the same coordinate system to establish a mathematical model to obtain the weld offset of the part.

[0027] More preferably, the mathematical model for the offset of the weld seam of the part is: weld seam offset = (actual weld seam diameter - theoretical weld seam diameter) / 2 ± center distance, where the actual weld seam diameter is the diameter of the weld seam fitting circle, the theoretical weld seam diameter is the diameter of the welding surface of the part before welding, and the center distance is the difference between the inner hole fitting circle and the weld seam fitting circle.

[0028] More preferably, the method for adjusting the laser welding apparatus based on the weld seam offset of the part includes:

[0029] When (actual weld diameter - theoretical weld diameter) / 2 is greater than the center distance, it indicates that the laser head is not in the correct position and needs to be adjusted.

[0030] When (actual weld diameter - theoretical weld diameter) / 2 is less than the center distance, it indicates that the fixture has a large runout and the fixture stability needs to be adjusted.

[0031] More preferably, the fitting device for the inner hole fitting circle and the weld fitting circle is an image measuring instrument.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] In the process of inspecting the weld depth of a part, this invention uses a test piece instead of the part, eliminating the need for destructive metallographic cutting inspection and saving part costs. At the same time, it can quickly determine whether the weld depth of the part meets the design requirements based on the penetration degree of the weld on the back of the test piece, saving inspection time. Furthermore, it can adjust the laser welding process in a timely manner based on the penetration degree of the weld on the back of the test piece to meet the design requirements of the weld depth of the part, thereby improving production efficiency.

[0034] This invention eliminates the need for destructive metallographic cutting during the detection of weld seam offset in parts. It only requires two fitting operations on the welded part, and the weld seam offset can be obtained by comparison, saving part costs and providing a convenient and quick detection method. Furthermore, by observing the weld seam offset and comparing the contribution value of (actual weld diameter - theoretical weld diameter) / 2 with the distance from the center, the specific source of the weld seam offset can be identified, allowing for more targeted adjustments and improving production efficiency. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating the application of gear laser welding in the background technology.

[0036] Figure 2 This is a diagram showing the effect when the back of the test piece is not penetrated by the weld.

[0037] Figure 3 This is a diagram showing the effect when the weld penetration on the back of the test piece reaches 90%.

[0038] Figure 4 This is a diagram showing the effect when the weld penetration on the back of the test piece reaches 100%.

[0039] Figure 5 This is a comparison diagram of the theoretical weld and the actual weld (actual weld diameter > theoretical weld diameter, center-to-center distance = 0).

[0040] Figure 6 This is a comparison diagram of the theoretical weld and the actual weld (actual weld diameter < theoretical weld diameter, center-to-center distance = 0).

[0041] Figure 7 This is a comparison diagram of the theoretical weld and the actual weld (actual weld diameter > theoretical weld diameter, center-to-center distance ≠ 0); where... Figure 7 'a' indicates that the theoretical weld and the actual weld do not intersect. Figure 7 b represents the intersection of the theoretical weld and the actual weld.

[0042] Figure 8 This is a comparison diagram of the theoretical weld and the actual weld (actual weld diameter < theoretical weld diameter, center-to-center distance ≠ 0); where... Figure 8 'a' indicates that the theoretical weld and the actual weld do not intersect. Figure 8 b represents the intersection of the theoretical weld and the actual weld.

[0043] In the figure, 1-spindle; 2-clamp; 3-gear; 4-meshing tooth; 5-weld; 6-laser head; 7-laser beam; 8-45° mirror; 9-focusing mirror; 10-protective lens; 11-actual weld; 12-theoretical weld; 13-test piece. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable that some well-known structures and their descriptions may be omitted in the drawings for those skilled in the art. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting this patent. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained based on the embodiments of the present invention are within the scope of protection of the present invention, but are not intended to limit the present invention.

[0045] This invention provides a rapid non-destructive testing method for gear weld depth based on laser welding, comprising the following steps:

[0046] Production of test piece 13: Test piece 13 and gear 3 are made of the same grade of material.

[0047] Base fabrication: Refer to the dimensions of gear 3 to ensure that after test piece 13 is placed on the base, the surface of test piece 13 is at the same height as the surface of gear 3 to be welded.

[0048] Based on the required weld depth of gear 3, test pieces 13 of different thicknesses are selected. Generally speaking, the thickness of test piece 13 is greater than the required weld depth of gear, a < thickness of test piece 13 < a + c, where a is the minimum weld depth requirement of gear 3, 0 < c < 0.5 mm. The thickness of test piece 13 can be selected as (a + 0.2) mm, (a + 0.3) mm, (a + 0.4) mm, etc.

[0049] Under normal production laser welding power P0, weld a gear 3. Then, metallographically inspect the weld depth of gear 3. If the weld depth is greater than a, reduce the welding power until the weld depth is between [a~(a+b)] mm. Record the laser welding power P at this point. Weld three pieces consecutively at this power, and then inspect the weld depth using metallographic cutting. Theoretically, as long as the laser welding machine's output power is stable, the weld depth will always be between [a~(a+b)] mm. Where 0 < b < 0.5 mm, and here b = 0.2 mm is preferred.

[0050] Under laser power P, test pieces 13 of different thicknesses are welded. The laser focus position is adjusted to ensure that the surfaces of test pieces 13 of different thicknesses and the surface of the gear to be welded are at the same focal length. If the back of test piece 13 with thickness t1 is completely penetrated by the weld, it means that the thickness of test piece 13 is too small. If the back of test piece 13 with thickness t2 is not penetrated by the weld, it means that the thickness of test piece 13 is too large. If the back of test piece 13 with thickness t is penetrated by the weld by about 80-95%, it means that the thickness is moderate. Then the laser power is increased to P0, and test piece 13 is welded to ensure that the back of test piece 13 is completely penetrated by the weld. Then the laser power is reduced to P, and three test pieces 13 with thickness t are welded continuously. Theoretically, as long as the output power of the laser welding machine is stable, the back of test piece 13 will be penetrated by 80-95% of the weld.

[0051] Based on the steps above, the following four scenarios can be identified:

[0052] ① When the weld penetration on the back of test piece 13 reaches 80-95%, the weld depth of the gear to be tested is within the range of a to (a+b). Figure 3 As shown;

[0053] ② When the weld penetration on the back of test piece 13 is 100%, the weld depth of the gear to be tested is greater than a to (a+b), such as... Figure 4 As shown;

[0054] ③ When the back of test piece 13 is not penetrated by the weld (e.g.) Figure 2 If the depth of the weld on the gear to be tested is less than a to (a+b), then... Figure 2 As shown;

[0055] ④ When the penetration of the weld on the back of test piece 13 is less than 80-95%, the weld depth of the gear to be tested is less than a to (a+b).

[0056] During normal welding production, when it's time for random inspection, test piece 13 is used to replace the gear to be tested for laser welding. If the back of test piece 13 shows the first situation, it means that the laser power barely meets the weld depth requirement of the gear, but the welding power needs to be increased appropriately. If the back of test piece 13 shows the second situation, it means that the laser power can meet the weld depth requirement of the gear, and there is no need to change the power; production can continue. If the back of test piece 13 shows the third and fourth situations, it means that the laser power can no longer meet the weld depth requirement of the gear. The machine should be stopped immediately for inspection, the protective lens 10 should be replaced, the gear should be cut to test the weld depth, the already processed gear should be isolated, and traceability should be ensured.

[0057] This invention also provides a rapid non-destructive testing method for gear weld offset based on laser welding, comprising the following steps:

[0058] Prepare an image measuring instrument and perform relevant MSA (Maximum Sum Assurance) to ensure that the capability value of the image measuring instrument, Cg / Cgk, is ≥1.33; at the same time, prepare 5 gears and 2 employees, with each employee inspecting each gear 3 times to ensure repeatability and reproducibility %R&R ≤25%.

[0059] When it's time for gear sampling inspection, remove the welded gear, quickly cool it to room temperature, place the gear on the platform of the image measuring instrument, turn on the bottom light of the image measuring instrument, and perform a 4-segment edge search on the inner hole. The image measuring instrument will automatically use the least squares method to fit the image. After fitting, the diameter of the inner hole and the position of the center will appear on the image measuring instrument. Do not move the gear, and ensure that the position of the gear relative to the platform does not change.

[0060] Turn off the bottom light and turn on the top light of the image measuring instrument. Move the platform of the image measuring instrument to see the weld surface. Adjust the focus and find the tip of the ripple on the weld surface. Then take a point. Continue to move the platform and take 12 points evenly on the circumference of the weld. The image measuring instrument will automatically fit these 12 points using the least squares method. After fitting, the image measuring instrument will display the diameter of the weld and the position of the weld center. Select the inner hole fitting circle and the weld fitting circle, and click on the center distance to get the center distance between the inner hole and the weld.

[0061] There are three important parameters in establishing a mathematical model: the theoretical diameter of the weld, the actual diameter of the weld, and the distance between the centers.

[0062] The theoretical diameter of the weld is the diameter of the welding surface of gear 3 before welding, which is specified in the drawings or process cards; the actual diameter of the weld is the diameter fitted by the image measuring instrument using the least squares method based on the selected 12 points; since the gear inner hole and the welding surface are machined in the same process, the center distance (concentricity) between the center of the inner hole and the center of the welding surface is almost 0 and can be ignored.

[0063] The actual weld offset of weld 11 relative to the theoretical weld 12 can be categorized into the following four cases:

[0064] ① The actual diameter of the weld is greater than the theoretical diameter of the weld, and the distance between the centers is 0. Figure 5 As shown;

[0065] ② The actual diameter of the weld is less than the theoretical diameter of the weld, and the distance between the centers is 0. Figure 6 As shown;

[0066] ③ The actual diameter of the weld is greater than the theoretical diameter of the weld, and the distance between the centers is not zero, such as... Figure 7 As shown;

[0067] ④ The actual diameter of the weld is less than the theoretical diameter of the weld, and the distance between the centers is not zero. Figure 8 As shown;

[0068] Based on the four scenarios of weld offset, the following mathematical models are proposed:

[0069] In the first case, the weld offset = (actual weld diameter - theoretical weld diameter) / 2;

[0070] In the second case, the weld offset = (actual weld diameter - theoretical weld diameter) / 2;

[0071] In the third case, the weld offset = (actual weld diameter - theoretical weld diameter) / 2 ± center distance;

[0072] In the fourth case, the weld offset = (actual weld diameter - theoretical weld diameter) / 2 ± center distance;

[0073] Since the distance between the centers of the circles in the first and second cases is 0, the mathematical model formula can be unified as follows:

[0074] Weld offset = (actual weld diameter - theoretical weld diameter) / 2 ± center distance.

[0075] The theoretical diameter of the weld is derived from the drawings. The weld offset can be obtained by inputting the actual diameter of the weld and the distance between the center and the center of the circle detected by the image measuring instrument into the formula.

[0076] Observe the weld offset value. When (actual weld diameter - theoretical weld diameter) / 2 is greater than the center distance, it indicates that the laser head position is incorrect and the position of laser head 6 needs to be adjusted. When (actual weld diameter - theoretical weld diameter) / 2 is less than the center distance, it indicates that the fixture (i.e., gripper 2) has a large runout and the stability of the fixture needs to be adjusted.

[0077] Because this detection method measures the maximum and minimum weld offset values, while metallographic cutting measures weld offset values ​​at random locations, theoretically, the maximum weld offset value measured by this method should be larger than that measured by metallographic cutting. Actual paired testing has confirmed that this method does indeed produce larger and more representative weld offset values ​​than metallographic cutting. Based on the contribution value, the specific origin of the weld offset can be identified, allowing for more targeted adjustments.

[0078] Based on cost accounting and time comparison, the average cost of metallographic gear cutting is about 50 yuan per piece, and the testing time is 30 minutes; in the method described in this article, the cost of the test piece is about 2 yuan per piece, and the testing time is about 3-5 minutes.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A rapid non-destructive testing method for weld seams of parts based on laser welding, characterized in that, This includes rapid non-destructive testing of weld depth on parts, comprising the following steps: S1. Obtain the laser welding power P corresponding to the weld depth of the part within the range of a to (a+b); where a is the minimum weld depth requirement of the part, 0 ＜ b ＜ 0.5mm; S2. Select multiple test pieces of different thicknesses with the same part grade, and obtain the test piece thickness t corresponding to the weld penetration degree on the back of the test piece reaching the preset penetration rate under laser welding power P. The preset penetration rate is 80-95%; a ＜ Specimen thickness < a + c, 0 ＜ c ＜ 0.5mm; S3. Prepare a test piece with the same grade as the part to be tested and a thickness of t. Use the test piece to replace the part to be tested for laser welding. Obtain the weld depth of the part to be tested based on the penetration result of the weld on the back of the test piece. Result 1: When the penetration of the weld on the back of the test piece reaches the preset penetration rate, the weld depth of the test part is within the range of a to (a+b). Result 2: When the weld penetration on the back of the test piece is 100%, the weld depth of the test part is greater than a to (a+b). Result 3: When the back of the test piece is not penetrated by the weld, the weld depth of the test part is less than a ~ (a+b). Result 4: When the penetration degree of the weld on the back of the test piece is less than the preset penetration rate, the weld depth of the test part is less than a to (a+b). Rapid non-destructive testing of weld offset in parts, including: Select the welded parts, perform multi-segment edge matching on the inner hole of the parts to obtain the fitting circle of the inner hole of the parts, and keep the parts stationary after fitting. Then, multiple points are uniformly selected along the circumference of the weld surface of the part to obtain the weld fitting circle of the part. Under the same coordinate system, the inner hole fitting circle and the weld fitting circle are compared to establish a mathematical model to obtain the weld offset of the part. Weld offset = (actual weld diameter - theoretical weld diameter) / 2 ± circle center distance, where the actual weld diameter is the diameter of the weld fitting circle, the theoretical weld diameter is the diameter of the weld surface before welding, and the circle center distance is the difference between the inner hole fitting circle and the weld fitting circle. Adjustment methods for laser welding equipment based on weld seam offset include: When (actual weld diameter - theoretical weld diameter) / 2 is greater than the center distance, it indicates that the laser head is not in the correct position and needs to be adjusted. When (actual weld diameter - theoretical weld diameter) / 2 is less than the center distance, it indicates that the fixture has a large runout and the fixture stability needs to be adjusted.

2. The rapid non-destructive testing method for weld seams of parts based on laser welding according to claim 1, characterized in that, Based on the penetration results of the weld seam on the back side of the test piece obtained in step S3, the methods for adjusting the laser welding process include: When the penetration result of the weld on the back of the test piece is result one, it means that the laser welding power barely meets the weld depth requirements of the part, and the laser welding power needs to be increased appropriately. When the penetration result of the weld on the back of the test piece is result two, it means that the laser power can meet the weld depth requirements of the part, and there is no need to change the laser welding power. When the penetration result of the weld on the back of the test piece is result three or result four, it indicates that the laser welding power cannot meet the weld depth requirements of the part, and the machine needs to be stopped for inspection and the protective lens needs to be replaced.

3. The rapid non-destructive testing method for weld seams of parts based on laser welding according to claim 1, characterized in that, In step S1, b = 0.2 mm.

4. The rapid non-destructive testing method for weld seams of parts based on laser welding according to claim 1, characterized in that, The fitting equipment for the inner hole fitting circle and the weld fitting circle is an image measuring instrument.

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