Multi-source monitoring method and system for synchronous laser welding process

Abstract

The invention belongs to the technical field of laser welding, and particularly relates to a synchronous laser welding process multi-source monitoring method and system.The method comprises the following steps that S1, the target temperature of a workpiece to be welded, the target position of operation of a lower mold and the target pressure borne by the workpiece to be welded are set; s2, the real-time temperature, the real-time position and the real-time pressure in the laser welding process of the workpiece to be welded are collected through a temperature sensor, a displacement sensor and a pressure sensor correspondingly, and fuzzy processing is conducted on the obtained real-time data; s3, the actual output and the expected output which are subjected to fuzzification processing are used for adjusting fuzzy control parameters through a self-adaptive algorithm, and then the output power of laser welding, the position of a lower die and the laser welding time are controlled; synchronous monitoring and adjustment of a plurality of welding parameter sources can be achieved, so that the welding quality and stability are improved, meanwhile, good self-adaptability is achieved, the system can adapt to different system characteristics and environment changes, and the response speed and precision of the system are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of laser welding, and in particular relates to a multi-source monitoring method and system for a synchronous laser welding process. Background Art

[0002] Laser welding plastic technology has the advantages of high precision, high speed, and less pollution, and is suitable for application fields with high requirements for connection quality and appearance. Among the many laser welding plastic technologies, synchronous laser welding of plastics has the widest applicability and the highest efficiency. However, in the synchronous laser plastic welding system, a sealed optical waveguide is required to focus the laser energy on the welding area. The closed space makes the synchronous laser plastic welding system lack effective real-time process detection means, and it is impossible to monitor and inspect the quality of the closed welding process.

[0003] For example, the patent document with publication number CN103781618A discloses a device and method for implementing and monitoring plastic laser transmission welding process, which uses an auxiliary light source to detect the weld area and welding depth. However, this method is only applicable to quasi-synchronous welding and track welding with a large welding equipment space. For synchronous welding, the waveguide above the workpiece forms a closed space, which cannot be detected using this method. Another example is the patent document with publication number CN109693031A discloses a method and laser welding equipment for determining the laser intensity in a laser welding system, a method for using a sensor to detect the light intensity of an optical fiber during welding, and a method for determining the output power of a laser channel by testing the output light intensity of a portion of the optical fiber arm. There is a certain degree of randomness in the method, and the measured value is not accurate. If a closed control loop is superimposed, it will produce an unfavorable welding effect.

[0004] Based on this, it is necessary to improve the defects of the prior art to overcome the deficiencies in practical applications. Summary of the invention

[0005] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide a synchronous laser welding process multi-source monitoring method and system that meets one or more of the above-mentioned needs.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for multi-source monitoring of a synchronous laser welding process, comprising the following steps:

[0008] S1. Setting the target temperature of the workpiece to be welded, the target position of the lower mold and the target pressure of the workpiece to be welded;

[0009] S2, respectively collecting the real-time temperature, real-time position and real-time pressure of the workpiece to be welded during laser welding through a temperature sensor, a displacement sensor and a pressure sensor, and performing fuzzy processing on the acquired real-time data;

[0010] S3. The actual output and expected output of the fuzzy processing are used to adjust the fuzzy control parameters through an adaptive algorithm, thereby controlling the output power, lower mold position and laser welding time of the laser welding.

[0011] As a preferred solution, step S2 includes:

[0012] S21, according to the detected actual temperature, actual position and actual pressure, respectively calculating the deviation and change rate of the target parameter, and then calculating the deviation membership and change rate membership;

[0013] S22. Fuzzification processing is performed according to the deviation membership, change rate membership and fuzzy rule base of different parameters.

[0014] As a preferred solution, step S21 includes:

[0015] S211, calculating the temperature deviation according to the actual detected temperature and the set target temperature, calculating the temperature change rate according to the actual detected current temperature and the temperature at the previous moment, and calculating the temperature deviation membership and the temperature change rate membership according to the temperature change rate;

[0016] S212, calculating the position deviation according to the actual detected position and the set target position, calculating the position change rate according to the actual detected current position and the position at the previous moment, and calculating the position deviation membership and the position change rate membership according to the position change rate;

[0017] S213, calculating the pressure deviation according to the actual detected pressure and the set target pressure, calculating the pressure change rate according to the actual detected current pressure and the pressure at the previous moment, and calculating the pressure deviation membership and the pressure change rate membership according to the pressure change rate.

[0018] As a preferred solution, step S3 includes:

[0019] S31, forming respective fuzzy rule bases between the laser current, the servo electric cylinder position and the laser output time, the actual temperature of the weld seam of the workpiece to be welded, the movement position of the upper mold and the clamping force borne by the workpiece to be welded;

[0020] S32, performing corresponding defuzzification processing on each fuzzy rule base, and adaptively adjusting the input of each fuzzy rule base to control the output power, lower mold position and laser welding time of laser welding.

[0021] As a preferred solution, during the adaptive adjustment process, it is determined whether the temperature skewness deviation, displacement skewness deviation and pressure skewness deviation have reached a preset value. If so, the adjustment is stopped; if not, step S2 is repeated.

[0022] The present invention also provides a multi-source monitoring system for a synchronous laser welding process, which uses the monitoring method described in any of the above schemes, including:

[0023] A multi-source sensor network module, including a temperature sensor, a displacement sensor and a pressure sensor, and used to detect process data of laser welding respectively;

[0024] Real-time monitoring module, used to monitor and process the collected process data;

[0025] The execution module is used to drive the workpiece to be welded to the detection position and provide welding pressure.

[0026] As a preferred solution, the real-time monitoring module includes:

[0027] A data acquisition unit, used to receive data from each sensor in the multi-source sensor network in real time and send the corresponding data to the data processing unit;

[0028] A data processing unit, used to analyze and process sensor data received by the real-time monitoring system;

[0029] The adjustment output unit is used to receive the results obtained by the data processing unit and control the execution modules respectively to adjust the pressure during welding, the displacement of the workpiece to be welded and the welding time.

[0030] As a preferred solution, the execution module includes a servo electric cylinder, an upper mold, a lower mold and a laser. The laser is installed on the upper mold, the laser is used to generate laser, and the lower mold is used to load the workpiece to be welded. The servo electric cylinder drives the lower mold to move so that the lower mold cooperates with the upper mold so that the workpiece to be welded is arranged opposite to the laser.

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

[0032] The present invention provides a multi-source monitoring method for a synchronous laser welding process, which can realize the synchronous monitoring and adjustment of multiple welding parameter sources, thereby improving the welding quality and stability. The monitoring process has high robustness and fault tolerance. Even if there is a lack or deviation in the detection data, it will not affect the operation of the system. At the same time, it has good adaptability, can adapt to different system characteristics and environmental changes, and improve the response speed and accuracy of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 is a flow chart of a method for multi-source monitoring of a synchronous laser welding process according to an embodiment of the present invention;

[0035] Figure 2 is another flow chart of a method for multi-source monitoring of a synchronous laser welding process according to an embodiment of the present invention;

[0036] Figure 3 4 is a structural diagram of a multi-source monitoring system for a synchronous laser welding process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the embodiments of the present application, the specific implementation methods of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0038] In the description of the embodiments of the present application, the terms "upper", "lower", "front", "rear", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", etc. are only used to distinguish in the description and have no special meaning.

[0039] According to some embodiments of the present application, please refer to Figure 1 to Figure 2 As shown, a method for multi-source monitoring of a synchronous laser welding process is now provided, comprising the following steps:

[0040] S1. Set the target temperature of the workpiece to be welded, the target position of the lower mold and the target pressure of the workpiece to be welded.

[0041] Specifically, the target temperature is set to T0±△T, temperature unit: ℃; the target position is set to S0±△S, displacement unit: um; the target pressure is set to F0±△F, pressure unit: KN.

[0042] S2. The real-time temperature, real-time position and real-time pressure of the workpiece to be welded during laser welding are respectively collected through temperature sensors, displacement sensors and pressure sensors, and the acquired real-time data are fuzzy processed.

[0043] The actual detected temperature at the current moment is t1, the actual position is s1, and the actual pressure is f1; the actual detected temperature at the previous moment is t0, the actual position is s0, and the actual pressure is f0.

[0044] In temperature parameters, temperature deviation ET: E T =t1-T0; Temperature change rate △ET: ΔE T =t1-t0.

[0046] In the position parameter, the position deviation ES: E S =s1-S0; Position change rate △ES: ΔE S =s1-s0.

[0047] In the pressure parameter, the pressure deviation EF:E F =f1-F0; pressure change rate △EF: ΔE F =f1-f0.

[0048] Specifically, the step S2 includes:

[0049] S21, according to the detected actual temperature, actual position and actual pressure, respectively calculating the deviation and change rate of the target parameter, and then calculating the deviation membership and change rate membership;

[0050] S22. Fuzzification processing is performed according to the deviation membership, change rate membership and fuzzy rule base of different parameters.

[0051] Furthermore, the step S21 includes:

[0052] S211, calculating the temperature deviation according to the actual detected temperature and the set target temperature, calculating the temperature change rate according to the actual detected current temperature and the temperature at the previous moment, and calculating the temperature deviation membership and the temperature change rate membership according to the temperature change rate.

[0053] Temperature deviation membership function E TH 、E TM 、E TL :

[0054]

[0055] Temperature change rate membership function △E TP , △E TE , △E TN :

[0056]

[0057] S212, calculating the position deviation according to the actual detected position and the set target position, calculating the position change rate according to the actual detected current position and the position at the previous moment, and calculating the position deviation membership and the position change rate membership according to the position change rate.

[0058] Position deviation membership function E SH 、E SM 、E SL :

[0059]

[0060] Displacement change rate membership function △E SP , △E SE , △E SN :

[0061]

[0062] S213, calculating the pressure deviation according to the actual detected pressure and the set target pressure, calculating the pressure change rate according to the actual detected current pressure and the pressure at the previous moment, and calculating the pressure deviation membership and the pressure change rate membership according to the pressure change rate.

[0063] Pressure deviation membership function E FH 、E FM 、E FL :

[0064]

[0065]

[0066] Pressure change rate membership function △E FP , △E FE , △E FN :

[0067]

[0068] S3. The actual output of the fuzzy processing and the expected output are adjusted through an adaptive algorithm to adjust the fuzzy control parameters, thereby controlling the output power, lower mold position and laser welding time of the laser welding.

[0069] Further, step S3 includes:

[0070] S31, forming respective fuzzy rule bases between the laser current, the servo electric cylinder position and the laser output time and the actual temperature of the weld seam of the workpiece to be welded, the movement position of the upper mold and the clamping force borne by the workpiece to be welded.

[0071] Taking the laser current and temperature change as an example, the membership corresponding to the temperature deviation and the temperature change rate jointly determine the adjustment method M of the laser current. IT Correspondingly, there is also an adjustment method M between the laser current, the table movement position, and the product's pressing force. IS and M IF There is an adjustment method M between the servo electric cylinder position and temperature changes, table movement position, and product clamping force. PT 、M PS and M PF There is an adjustment method M between the laser output time and temperature changes, table movement position, and product pressing force. TT 、M TS and M TF .

[0072] S32, performing corresponding defuzzification processing on each fuzzy rule base, and adaptively adjusting the input of each fuzzy rule base to control the output power, lower mold position and laser welding time of laser welding.

[0073] Taking the laser current and temperature change as an example, the laser current adjustment △IT satisfies the following formula:

[0074]

[0075] Among them, n IT M is the laser current adjustment amount determined by temperature change; IT This is how the laser current is adjusted according to temperature changes.

[0076] Accordingly, according to the table movement position and the product pressure, the laser current adjustment amount △I S and △I F The adjustment between the servo cylinder position and temperature change, table movement position, and product clamping force is △P T , △P S and △P F The adjustment between the laser output time and the temperature change, the table movement position, and the pressing force on the product is △T T , △T S and △T F .

[0077] Furthermore, during the adaptive adjustment process, it is determined whether the temperature skewness deviation, the displacement skewness deviation and the pressure skewness deviation have reached a preset value. If so, the adjustment is stopped; if not, step S2 is repeated.

[0078] PLC controls the laser output current D I :D I =ΔI T +ΔIS +ΔI F ;

[0079] Servo motor controls the position of the lower mold of the synchronous plastic welding equipment D P :D P =ΔP T +ΔP S +ΔP F ;

[0080] PLC controls the laser output time D T :D T =ΔT T +ΔT S +ΔT F .

[0081] Furthermore, let the learning rate of laser current, temperature deviation and temperature change rate be η IET and η I△ET , when △I T When the value of continuous t is not 0, if the adjustment method M IT Value unchanged:

[0082]

[0083] Correspondingly, there are corresponding adaptive adjustment methods for the relationship between the laser current and the movement position of the table, the pressing force exerted on the product, the relationship between the servo cylinder position and temperature change, the movement position of the table, the pressing force exerted on the product, and the relationship between the laser output time and temperature change, the movement position of the table, and the pressing force exerted on the product.

[0084] When the temperature skewness deviation E T <ΔT and displacement skewness deviation E S <ΔS and pressure skewness deviation E F When <ΔF, the adjustment is completed.

[0085] According to some embodiments of the present application, Figure 3 As shown, a synchronous laser welding process multi-source monitoring system is also provided, which applies the above-mentioned monitoring method and includes:

[0086] A multi-source sensor network module, including a temperature sensor, a displacement sensor and a pressure sensor, and used to detect process data of laser welding respectively;

[0087] Real-time monitoring module, used to monitor and process the collected process data;

[0088] The execution module is used to drive the workpiece to be welded to the detection position and provide welding pressure.

[0089] Furthermore, the real-time monitoring module includes:

[0090] A data acquisition unit, used to receive data from each sensor in the multi-source sensor network in real time and send the corresponding data to the data processing unit;

[0091] A data processing unit, used to analyze and process sensor data received by the real-time monitoring system;

[0092] The adjustment output unit is used to receive the results obtained by the data processing unit and control the execution modules respectively to adjust the pressure during welding, the displacement of the workpiece to be welded and the welding time.

[0093] Furthermore, the execution module includes a servo electric cylinder, an upper mold, a lower mold and a laser, the laser is installed on the upper mold, the laser is used to generate laser, the lower mold is used to load the workpiece to be welded, and the servo electric cylinder drives the lower mold to move so that the lower mold cooperates with the upper mold so that the workpiece to be welded is arranged opposite to the laser.

[0094] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0095] The above description is only a detailed description of the preferred embodiments and principles of the present application. For ordinary technicians in this field, there will be changes in the specific implementation methods based on the ideas provided by the present invention, and these changes should also be regarded as the scope of protection of the present application.

Claims

1. A method for multi-source monitoring of a synchronous laser welding process, characterized in that: The following steps are involved: S1. Setting the target temperature of the workpiece to be welded, the target position of the lower mold and the target pressure of the workpiece to be welded; S2, respectively collecting the real-time temperature, real-time position and real-time pressure of the workpiece to be welded during laser welding through a temperature sensor, a displacement sensor and a pressure sensor, and performing fuzzy processing on the acquired real-time data; S3. The actual output and expected output of the fuzzy processing are used to adjust the fuzzy control parameters through an adaptive algorithm, thereby controlling the output power, lower mold position and laser welding time of the laser welding.

2. The method for multi-source monitoring of a synchronous laser welding process according to claim 1, characterized in that: The step S2 comprises: S21, according to the detected actual temperature, actual position and actual pressure, respectively calculating the deviation and change rate of the target parameter, and then calculating the deviation membership and change rate membership; S22. Fuzzification processing is performed according to the deviation membership, change rate membership and fuzzy rule base of different parameters.

3. The method for multi-source monitoring of a synchronous laser welding process according to claim 2, characterized in that: The step S21 comprises: S211, calculating the temperature deviation according to the actual detected temperature and the set target temperature, calculating the temperature change rate according to the actual detected current temperature and the temperature at the previous moment, and calculating the temperature deviation membership and the temperature change rate membership according to the temperature change rate; S212, calculating the position deviation according to the actual detected position and the set target position, calculating the position change rate according to the actual detected current position and the position at the previous moment, and calculating the position deviation membership and the position change rate membership according to the position change rate; S213, calculating the pressure deviation according to the actual detected pressure and the set target pressure, calculating the pressure change rate according to the actual detected current pressure and the pressure at the previous moment, and calculating the pressure deviation membership and the pressure change rate membership according to the pressure change rate.

4. The method for multi-source monitoring of a synchronous laser welding process according to claim 2, characterized in that: Step S3 includes: S31, forming respective fuzzy rule bases between the laser current, the servo electric cylinder position and the laser output time, the actual temperature of the weld seam of the workpiece to be welded, the movement position of the upper mold and the clamping force borne by the workpiece to be welded; S32, performing corresponding defuzzification processing on each fuzzy rule base, and adaptively adjusting the input of each fuzzy rule base to control the output power, lower mold position and laser welding time of laser welding.

5. The method for multi-source monitoring of synchronous laser welding process according to claim 4, characterized in that: During the adaptive adjustment process, it is determined whether the temperature skewness deviation, displacement skewness deviation and pressure skewness deviation have reached a preset value. If so, the adjustment is stopped; if not, step S2 is repeated.

6. A synchronous laser welding process multi-source monitoring system, characterized in that: The monitoring method according to any one of claims 1 to 5 is applied, comprising: A multi-source sensor network module, including a temperature sensor, a displacement sensor and a pressure sensor, and used to detect process data of laser welding respectively; Real-time monitoring module, used to monitor and process the collected process data; The execution module is used to drive the workpiece to be welded to the detection position and provide welding pressure.

7. A synchronous laser welding process multi-source monitoring system according to claim 6, characterized in that: The real-time monitoring module includes: A data acquisition unit, used to receive data from each sensor in the multi-source sensor network in real time and send the corresponding data to the data processing unit; A data processing unit, used to analyze and process sensor data received by the real-time monitoring system; The adjustment output unit is used to receive the results obtained by the data processing unit and control the execution modules respectively to adjust the pressure during welding, the displacement of the workpiece to be welded and the welding time.

8. A synchronous laser welding process multi-source monitoring system according to claim 6, characterized in that: The execution module includes a servo electric cylinder, an upper mold, a lower mold and a laser. The laser is installed on the upper mold. The laser is used to generate laser. The lower mold is used to load the workpiece to be welded. The servo electric cylinder drives the lower mold to move so that the lower mold cooperates with the upper mold so that the workpiece to be welded is arranged opposite to the laser.

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