Database construction method and system for storing laser welding process parameters and fusion depth information

Abstract

The invention belongs to the related technical field of laser welding, and discloses a database construction method and system for storing laser welding process parameters and fusion depth information. The method comprises the following steps that welding process parameters in laser welding are determined, and welding heat input is calculated; welding is conducted according to the welding parameters, a fusion depth curve of a weld joint is obtained, and the fusion depth mean value and the standard deviation are calculated through the fusion depth curve; and the welding parameters and the fusion depth mean values corresponding to the welding heat are stored, and laser welding is carried out for multiple times, so that a database in which the welding parameters and the welding heat correspond to the fusion depth mean values one to one is formed. The method and the device have the advantages that disordered inspection of process parameters and welding results is avoided, production efficiency is improved, and the method and the device are high in flexibility, applicable to various welding materials and various process conditions and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field related to laser welding, and more specifically, relates to a database construction method and system for storing laser welding process parameters and penetration information. Background Art

[0002] As an advanced welding process, laser welding has the advantages of high energy density, small welding deformation, fast welding speed, small heat input and heat-affected zone, etc. It is widely used in automobile manufacturing, rail transportation, aerospace and other fields, and has become a key equipment production process. However, laser welding has many process parameters and a complex adjustment process, which makes it difficult to quickly match the target process with the corresponding welding quality results in a variety of process parameter combinations. Therefore, in the actual equipment manufacturing process, a large number of process experiments and their results need to be stored and recorded for quick query in subsequent production to avoid the problem of repeated experiments caused by failure to count the process parameters of completed experiments.

[0003] Among a series of quality results of laser welding, penetration is an important characterization indicator that reflects the internal formation of the weld. Penetration has a great influence on the joint stability and strength of the weld. On the one hand, if the overall penetration is too large or the penetration at certain positions exceeds the limit, the excessive heat generated will cause overheating, burn-through and other undesirable phenomena; on the other hand, if the overall penetration is too small or the penetration at certain positions is insufficient, it is difficult to ensure the connection strength, resulting in the weld being unable to withstand complex and variable working loads. Therefore, it is also crucial to pay attention to the fluctuation of the penetration curve during welding.

[0004] In summary, in laser welding, it is urgent to develop a process knowledge database that can not only store the values ​​of the various process parameters used, but also obtain the information of the obtained penetration curve.

[0005] However, in the current research on laser welding process and penetration depth, there is still a lack of an efficient database construction method that has both the functions of process parameter recording and penetration depth information query, which makes it difficult to further carry out in-depth research on laser welding process optimization and quality assessment. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a method and system for constructing a database for storing laser welding process parameters and penetration information, so as to solve the problem that the penetration information cannot be quickly queried using process parameters.

[0007] To achieve the above object, according to one aspect of the present invention, a method for constructing a database for storing laser welding process parameters and penetration information is provided, the method comprising the following steps:

[0008] Determine welding process parameters in laser welding and calculate welding heat input;

[0009] Welding is performed according to the welding parameters to obtain a penetration curve of the weld, and a mean value and a standard deviation of the penetration are calculated using the penetration curve;

[0010] The welding parameters and the average values ​​of the penetration depth corresponding to the welding heat are stored, and laser welding is performed multiple times to form a database in which the welding parameters, welding heat and the average values ​​of the penetration depth correspond one to one.

[0011] Further preferably, the calculation formula of the welding heat is as follows:

[0012]

[0013] Where I is the welding heat, P and V are the laser power and welding speed, respectively, and η is the energy absorption coefficient.

[0014] Further preferably, the calculation formula of the mean penetration depth is as follows:

[0015]

[0016] Among them, Me is the mean value of penetration depth, Me is the mean value of penetration depth, H i is the corresponding penetration value at each moment / position, N is the total number of points in the sample, and i is the sample number.

[0017] Further preferably, the calculation formula of the standard deviation of the penetration depth is as follows:

[0018]

[0019] Where Sd is the standard deviation of penetration depth.

[0020] Further preferably, the welding process parameters are the workpiece material used for welding, laser power, laser inclination angle, welding speed, defocus amount, type and flow rate of shielding gas, and the gap between two plates to be welded.

[0021] Further preferably, the protective gas is argon, helium or carbon dioxide.

[0022] Further preferably, the welding material includes one of stainless steel, galvanized steel, aluminum alloy, aluminum-magnesium alloy, aluminum-copper alloy and titanium alloy.

[0023] Further preferably, before using the penetration curve to calculate the mean penetration and the standard deviation, it is first detected whether the penetration curve has abnormal points, and if so, the abnormal points are deleted before calculating the mean penetration and the standard deviation.

[0024] Further preferably, the Laida criterion is used to detect whether there are abnormal points in the penetration curve.

[0025] According to another aspect of the present invention, a database construction system for storing laser welding process parameters and penetration information is provided, the method comprising an actuator for executing the above-mentioned database construction method for storing laser welding process parameters and penetration information.

[0026] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0027] 1. The database construction method for storing laser welding process parameters and penetration information provided by the present invention records the value of each process parameter and the corresponding penetration fluctuation status information, so that the corresponding penetration information can be quickly queried by inputting the process parameters before subsequent welding. This method provides a new means for matching laser welding process and results, can avoid disorderly checking process parameters and welding results, improve production efficiency, and has the advantages of high flexibility and applicability to various welding materials and various process conditions.

[0028] 2. The database construction method for storing laser welding process parameters and penetration information provided by the present invention makes it easy to calculate and obtain penetration information, which is conducive to achieving full automation; it can fully perceive the fluctuation of penetration depth and thus obtain a reflection on the welding quality, which is of great significance to the quality assurance and process optimization of laser welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of a method for constructing a database for storing laser welding process parameters and penetration information constructed according to a preferred embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of a welding process constructed according to a preferred embodiment of the present invention, wherein (a) is a front view of the welding process, and (b) is a side view of the welding process;

[0031] Figure 3 is a schematic diagram of a penetration curve and its fluctuation information constructed according to a preferred embodiment of the present invention;

[0032] Figure 4 It is a schematic diagram of the interface of the process knowledge database constructed according to the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] like Figure 1 As shown, a method for constructing a database for storing laser welding process parameters and penetration information includes:

[0035] S1, determine the combination of process parameters used in the laser welding process.

[0036] Specifically, the welding process and the process parameters in the embodiment of the present invention are shown as follows: Figure 2 shown.

[0037] For the welding task to be carried out, first clarify the material of the workpiece used, such as stainless steel or galvanized steel or aluminum alloy or aluminum-magnesium alloy or aluminum-copper alloy or titanium alloy, etc.; then determine the values ​​of the laser power P and welding speed V used, and then calculate the corresponding heat input I value. The calculation formula is:

[0038]

[0039] Among them, P and V are laser power and welding speed respectively, and η is the energy absorption coefficient.

[0040] Furthermore, for the welding task to be performed, the value of the defocus amount D and the type of shielding gas used (such as argon or helium or carbon dioxide, etc.) and the flow rate F are determined; then the value and sign of the laser inclination angle A are determined, wherein if the laser beam deflects in the welding direction, the laser inclination angle A is a negative value, and conversely, if the laser beam deflects in the opposite direction of the welding, the laser inclination angle A is a positive value.

[0041] Preferably, the welding material is not limited, including various metals such as stainless steel, galvanized steel, aluminum alloy, aluminum-magnesium alloy, aluminum-copper alloy, and titanium alloy.

[0042] Preferably, the protective gas includes inert gases such as argon, helium, and carbon dioxide.

[0043] Preferably, if the laser beam deflects toward the welding direction, the laser inclination angle A is a negative value; if the laser beam deflects toward the opposite direction of the welding, the laser inclination angle A is a positive value.

[0044] Preferably, the laser welding joint is in the form of butt joint, and there is a gap G between the two workpiece plates.

[0045] For the laser butt welding joint form described in the present invention, the gap G as an important process parameter also needs to be determined.

[0046] S2, to carry out welding experiments and obtain the penetration curve based on the determined values ​​of each process parameter.

[0047] like Figure 3 As shown, for the weld obtained from the welding experiment, a weld processing method is used to obtain a penetration curve, and the method includes but is not limited to metallographic processing or X-ray detection, etc., all of which are within the protection scope of the present invention.

[0048] Specifically, taking the metallographic processing method as an example, the process of obtaining the penetration curve is introduced. The weld is cut longitudinally along the center line of the weld, and the longitudinal section of the weld is grinded, polished, corroded, and scanned in sequence to obtain a clear longitudinal metallographic picture of the weld.

[0049] Furthermore, the metallographic image is digitally processed on a computer, the penetration curve is extracted, and the depth of each point on the curve is calculated as the penetration value of each position of the weld.

[0050] S3, extracting mathematical information of the penetration depth curve and defining the fluctuation range of the penetration depth.

[0051] For the obtained penetration curve, first calculate its mean value Me and standard deviation Sd. The calculation formula is:

[0052]

[0053]

[0054] Where N is the number of all data points on the penetration curve H(t), H i For each data point.

[0055] Furthermore, the Laida criterion is used to detect outliers in H(t). The probability that any point on the curve falls within the range of 6 times the standard deviation around the mean is 99.74%, and falling outside this range is a low-probability event that is impossible to occur. Data points in H(t) that exceed this range are considered outliers and are removed.

[0056] Specifically, the calculation formulas for the upper boundary Ub and lower boundary Lb of normal fluctuation of H(t) are:

[0057] Ub=Me+3Sd

[0058] Lb=Me-3Sd

[0059] If there are data points in H(t) that are beyond Ub or Lb, these points are considered as outliers. After removing them, recalculate Me and Sd of H(t) without outlier points, and use the new Me+3Sd as the upper boundary Ub of the final penetration fluctuation, and the new Me-3Sd as the lower boundary Lb of the final penetration fluctuation.

[0060] The penetration curve and its fluctuation information (mean value, upper and lower boundaries, etc.) obtained in the embodiment of the present invention are shown as follows: Figure 4 shown.

[0061] Preferably, the calculation formulas for the mean value Me and the standard deviation Sd of the penetration depth are:

[0062]

[0063]

[0064] Where N is the number of all data points on the penetration curve H(t), H i For each data point.

[0065] In one embodiment of the present invention, it is checked whether there are abnormal points in the penetration curve, and if there are, Me and Sd are recalculated after being removed;

[0066] Preferably, the Laida criterion is used to check whether there are abnormal points in the penetration curve.

[0067] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for constructing a database for storing laser welding process parameters and penetration information, characterized in that: The method comprises the following steps: Determine welding process parameters in laser welding and calculate welding heat input; Welding is performed according to the welding parameters to obtain a penetration curve of the weld, and a mean value and a standard deviation of the penetration are calculated using the penetration curve; The welding parameters and the average values ​​of the penetration depth corresponding to the welding heat are stored, and laser welding is performed multiple times to form a database in which the welding parameters, welding heat and the average values ​​of the penetration depth correspond one to one.

2. A method for constructing a database for storing laser welding process parameters and penetration information according to claim 1, characterized in that: The calculation formula of the welding heat is as follows: Where I is the welding heat, P and V are the laser power and welding speed, respectively, and η is the energy absorption coefficient.

3. A method for constructing a database for storing laser welding process parameters and penetration information according to claim 1, characterized in that: The calculation formula of the mean penetration depth is as follows: Among them, Me is the mean value of penetration depth, H i is the corresponding penetration value at each moment / position, N is the total number of points in the sample, and i is the sample number.

4. A method for constructing a database for storing laser welding process parameters and penetration information as claimed in claim 3, characterized in that: The calculation formula for the standard deviation of the penetration depth is as follows: Where Sd is the standard deviation of penetration depth.

5. A method for constructing a database for storing laser welding process parameters and penetration information according to claim 1, characterized in that: The welding process parameters include the workpiece material used for welding, laser power, laser inclination angle, welding speed, defocusing amount, type and flow rate of protective gas, and the gap between the two plates to be welded.

6. A method for constructing a database for storing laser welding process parameters and penetration information as claimed in claim 5, characterized in that: The protective gas is argon, helium or carbon dioxide.

7. A method for constructing a database for storing laser welding process parameters and penetration information according to claim 1, characterized in that: The welding material includes one of stainless steel, galvanized steel, aluminum alloy, aluminum-magnesium alloy, aluminum-copper alloy and titanium alloy.

8. A method for constructing a database for storing laser welding process parameters and penetration information according to claim 1, characterized in that: Before using the penetration curve to calculate the mean penetration value and the standard deviation, first check whether the penetration curve has abnormal points. If so, delete the abnormal points and then calculate the mean penetration value and the standard deviation.

9. A method for constructing a database for storing laser welding process parameters and penetration information as claimed in claim 8, characterized in that: The Laida criterion is used to detect whether there is an abnormal point in the penetration curve.

10. A database construction system for storing laser welding process parameters and penetration information, characterized in that: The method includes an actuator, which is used to execute a database construction method for storing laser welding process parameters and penetration information as described in any one of claims 1-9.

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