Flat plate nut automatic welding machine

Abstract

The application is suitable for the field of automatic welding equipment, and provides a flat plate type nut automatic welding machine, which comprises a welding table, characterized in that a clamping mechanism is arranged on the welding table, the clamping mechanism is used for clamping and fixing the flat plate, a supporting mechanism is arranged on the lower side of the clamping mechanism, the supporting mechanism is used for elastically supporting the flat plate, a positioning mechanism is arranged on one side of the clamping mechanism, the positioning mechanism is used for clamping and positioning the nut placed on the flat plate, a welding mechanism for welding the flat plate and the nut is arranged on one side of the positioning mechanism; and the welding precision control system is further included. The application effectively reduces the position deviation of the nut caused by welding thermal deformation, compensates the positioning error caused by the assembly gap and surface roughness, and realizes the dynamic optimization of the supporting force along the welding process.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of automatic welding equipment, and particularly relates to a flat plate type nut automatic welding machine. BACKGROUND

[0002] As an important connecting component, flat plate type nuts are widely used in the fields of automobile manufacturing, aerospace, etc. Traditional welding processes mainly rely on manual operation, which has problems such as low efficiency and unstable quality. With the development of industrial automation, although the existing automatic welding equipment has realized basic clamping, positioning and welding functions, it still faces many technical problems in actual application.

[0003] The thermal deformation problem in the welding process is the primary factor affecting the precision. The high temperature generated during welding will cause thermal expansion of the metal material, and shrinkage deformation will occur during the cooling process. This thermal-mechanical coupling effect causes complex deformation of the flat plate and the nut, which not only affects the flatness of the product appearance, but also causes the nut position to deviate or tilt. The existing equipment lacks real-time monitoring and deformation prediction capability of welding parameters, and it is difficult to effectively control this thermal deformation.

[0004] Insufficient initial positioning accuracy is another key problem. Factors such as assembly gap between the nut and the positioning hole of the flat plate, and flat plate surface roughness will affect the final welding position accuracy. Although the existing equipment is equipped with a positioning mechanism, it lacks accurate evaluation means for the actual pose of the nut, and cannot effectively compensate for micron-level positioning errors.

[0005] The lack of adaptability of the support mechanism also restricts the welding quality. The traditional support mechanism adopts a fixed support force design, which cannot be dynamically adjusted according to the state changes of the workpiece during welding. This rigid support method may cause uneven distribution of support force when the workpiece is deformed, and thus cause poor welding contact or aggravated deformation.

[0006] In addition, the existing equipment lacks a cooperative control mechanism between the functional modules. Welding parameters, positioning state, support force and other key factors interact with each other, but the existing system cannot realize closed-loop control of these parameters, resulting in large fluctuations in welding quality. Especially in high-precision application scenarios, this open-loop control method cannot guarantee the consistency and reliability of the product.

[0007] In view of the above problems, the existing technology needs to be improved. SUMMARY

[0008] The purpose of the embodiment of the application is to provide a flat plate type nut automatic welding machine, which aims to solve the lack of cooperative control mechanism between the functional modules of the existing equipment.

[0009] The application is achieved, a flat plate nut automatic welding machine, including welding table, the welding table is provided with clamping mechanism, the clamping mechanism is used for clamping and fixing flat plate, the lower side of the clamping mechanism is provided with support mechanism, the support mechanism is used for the elastic support of flat plate, the clamping mechanism one side is provided with positioning mechanism, the positioning mechanism is used for the clamping and positioning of nut placed on flat plate, the positioning mechanism one side is provided with the welding mechanism for the welding of flat plate and nut;Also includes:

[0010] Welding precision control system, it includes:

[0011] Welding state evaluation module: according to the welding current, welding voltage and welding time of welding mechanism, the welding state evaluation model is constructed, and the welding state coefficient is output;

[0012] Deformation degree prediction module: under the influence of flat plate thickness, nut diameter, according to the welding state coefficient, flat plate linear expansion coefficient, nut linear expansion coefficient, the deformation degree prediction model is constructed, and the deformation degree prediction is output;

[0013] Position state evaluation module: according to the horizontal gap distance of nut and positioning hole on flat plate, the vertical spacing between nut and positioning hole on flat plate and the roughness of flat plate welding surface, the position state evaluation model is constructed, and the position state coefficient is output;

[0014] Position state-deformation degree matching degree: under the influence of positioning mechanism clamping force and nut verticality, according to the position state coefficient and deformation degree prediction, the position state-deformation degree matching model is constructed, and the position state-deformation degree matching degree is output;

[0015] Flat plate state adjustment module: according to the preset support force of support mechanism to flat plate, position state-deformation degree matching degree, the flat plate state adjustment model is constructed, and the target support force of support mechanism is output;

[0016] Welding precision control system is electrically connected with support mechanism through PLC controller.

[0017] Further technical solutions, the clamping mechanism includes fixed seat A, electric telescopic rod A and U-shaped seat;

[0018] Two fixed seats A are fixedly connected on the welding table, each fixed seat A is fixedly connected with electric telescopic rod A, the telescopic end of electric telescopic rod A is fixedly connected with U-shaped seat, the U-shaped seat is fixedly connected with guide rod, the U-shaped seat is also provided with clamp, the clamp is vertically slidably connected with guide rod, and the two clamps are oppositely arranged.

[0019] Further technical solutions, the support mechanism includes fixed frame, electric push rod, limiting plate and spring.

[0020] The bottom of the U-shaped seat is fixedly connected with a fixing frame, the fixing frame is fixedly connected with an electric push rod, the output end of the electric push rod is fixedly connected with a limiting plate, the guide rods are all sleeved with springs, the springs can elastically support the clamps, and the limiting plate can vertically push the springs to compress.

[0021] Further technical solutions, the positioning mechanism comprises a guide rail A, a sliding seat A and a driving rod A;

[0022] The guide rail A is fixedly connected with the welding table through a fixing seat B, the sliding seat A is slidably connected in the guide rail A, the driving rod A is threadedly connected with the sliding seat A, the driving rod A drives the sliding seat A to slide along the guide rail A through threaded transmission, the electric telescopic rod B is fixedly connected with the sliding seat A, and the electric clamp is fixedly connected to the telescopic end of the electric telescopic rod B.

[0023] Further technical solutions, the welding mechanism comprises a guide rail B, a sliding seat B and a driving rod B;

[0024] The guide rail B is fixedly connected with the welding table through a fixing seat C, the sliding seat B is slidably connected in the guide rail B, the driving rod B is threadedly connected with the sliding seat B, the driving rod B drives the sliding seat B to slide along the guide rail B through threaded transmission, the electric telescopic rod C is fixedly connected with the sliding seat B, and the welding machine is fixedly connected to the telescopic end of the electric telescopic rod C.

[0025] Further technical solutions, the welding current, the welding voltage and the welding time of the welding mechanism are substituted into the maximum and minimum value normalization formula respectively for processing, and welding current index, welding voltage index and welding time index are obtained respectively;

[0026] The welding state evaluation model is:

[0027] ;

[0028] Wherein is a welding current weight coefficient, is a welding voltage weight coefficient, is a welding time weight coefficient, is a welding current index, is a welding voltage index, is a welding time index, is a welding state coefficient.

[0029] Further technical solutions, the thickness of the welded plate, the diameter of the nut and the plate linear expansion coefficient and the nut linear expansion coefficient are substituted into the maximum value normalization formula respectively for processing, and the plate thickness index, the nut diameter index, the plate linear expansion index and the nut linear expansion index are obtained respectively.

[0030] The deformation degree prediction model is as follows:

[0031] ;

[0032] in The weighting factor for the influence of welded component specifications. The weighting coefficients for the effects of linear expansion of flat plates are as follows: The weighting factor for the effect of linear expansion of the nut. For flat plate thickness index, This is the nut diameter index. This is the linear expansion index of a flat plate. This is the linear expansion index of the nut. This is the welding condition coefficient. This is a prediction of the degree of deformation.

[0033] A further technical solution involves substituting the horizontal clearance distance between the nut and the positioning hole on the plate, the vertical spacing between the nut and the positioning hole on the plate, and the surface roughness of the plate weld into the maximum value normalization formula for processing, and obtaining the horizontal clearance index, the vertical spacing index, and the plate roughness index respectively.

[0034] The location status assessment model is as follows:

[0035] ;

[0036] in The horizontal gap affects the weighting coefficient. The vertical spacing affects the weighting coefficient. The weighting coefficient for the influence of plate roughness. The horizontal gap index, This is the vertical spacing index. The roughness index of the flat plate. This is the position state coefficient.

[0037] A further technical solution involves substituting the clamping force of the positioning mechanism on the nut and the verticality of the nut into the maximum value normalization formula for processing, and obtaining the clamping force index and the verticality index respectively.

[0038] The position-deformation matching model is as follows:

[0039] ;

[0040] in The clamping force index, Verticality index For position state coefficients, To estimate the degree of deformation, is a constant, is a position state-deformation degree matching degree.

[0041] Further technical solutions, the flat state adjustment model is:

[0042] ;

[0043] wherein is a preset support force, is an adjustment gain coefficient, is a position state-deformation degree matching degree, is a matching degree reference value, is a target support force.

[0044] Compared with the prior art, the beneficial effects of the present application are:

[0045] The present application effectively reduces the nut position deviation caused by welding thermal deformation, compensates for the positioning error caused by the assembly gap and surface roughness, and realizes the dynamic optimization of the support force with the welding process. The specific performance is that the nut position deviation after welding is reduced, the bolt assembly qualification rate is improved, and the incidence of virtual welding defects caused by improper support force is reduced.

[0046] The present application can dynamically perceive the coordinated fluctuation of welding current, voltage and time parameters, and real-time evaluate the comprehensive state of heat input. The welding state coefficient as a continuous variable can identify local overheating or heat deficiency caused by abnormal parameter combination, so as to inhibit the welding thermal deformation and unstable welding quality caused by uneven heat input. The model provides reliable input parameters for the subsequent deformation prediction module, forming a closed-loop system for welding quality control.

[0047] The present application can dynamically perceive the influence of clamping force fluctuation and nut inclination state on positioning accuracy, real-time evaluate the superposition effect of welding thermal deformation and initial position error, and accurately calculate the target support force required by the support mechanism. This scheme effectively suppresses the nut displacement caused by insufficient clamping force, compensates for the pose deviation caused by thermal deformation, ensures the dynamic matching of nut position accuracy and thermodynamic state during the welding process, and significantly improves the assembly qualification rate of the welded joint.

[0048] The present application can dynamically offset the flat deformation caused by welding thermal deformation and keep the pressure of the nut and flat contact surface stable. The model suppresses the sudden change of support force through a nonlinear function, avoids the interference of mechanical vibration on the welding process. The introduction of the matching degree reference value makes the system have self-balancing characteristics, which maintains the control stability while ensuring the adjustment accuracy. This scheme effectively solves the problems of virtual welding and position deviation caused by thermal deformation, and improves the reliability and assembly accuracy of the welded joint. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1It is a structural schematic diagram of the present application;

[0050] Figure 2 It is a schematic diagram of the cooperation of the clamping mechanism and the supporting mechanism in the present application;

[0051] Figure 3 It is a structural schematic diagram of the positioning mechanism;

[0052] Figure 4 It is a structural schematic diagram of the welding mechanism;

[0053] Figure 5 It is a principle schematic diagram of the welding precision control system.

[0054] In the drawings: 1, welding table; 2, clamping mechanism; 21, fixed seat A; 22, electric telescopic rod A; 23, U-shaped seat; 24, guide rod; 25, clamp; 3, supporting mechanism; 31, fixed frame; 32, electric push rod; 33, limiting plate; 34, spring; 4, positioning mechanism; 41, guide rail A; 42, sliding seat A; 43, driving rod A; 44, electric telescopic rod B; 45, electric clamp; 5, welding mechanism; 51, guide rail B; 52, sliding seat B; 53, driving rod B; 54, electric telescopic rod C; 55, welding machine; 6, fixed seat B; 7, fixed seat C. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0056] The specific implementation of the present application is described in detail below in combination with specific examples.

[0057] As shown in Figures 1-5 , a flat plate type nut automatic welding machine provided by one embodiment of the present application, comprising a welding table 1, the welding table 1 is provided with a clamping mechanism 2, the clamping mechanism 2 is used for clamping and fixing the flat plate, the clamping mechanism 2 is provided with a supporting mechanism 3 at the lower side, the supporting mechanism 3 is used for elastically supporting the flat plate, the clamping mechanism 2 is provided with a positioning mechanism 4 at one side, the positioning mechanism 4 is used for clamping and positioning the nut placed on the flat plate, the positioning mechanism 4 is provided with a welding mechanism 5 at one side for welding the flat plate and the nut; further comprising:

[0058] A welding precision control system, comprising:

[0059] A welding state evaluation module: a welding state evaluation model is constructed according to the welding current, welding voltage and welding time of the welding mechanism 5, and a welding state coefficient is outputted;

[0060] Deformation degree prediction module: under the influence of plate thickness and nut diameter, a deformation degree prediction model is constructed according to the welding state coefficient, the plate linear expansion coefficient and the nut linear expansion coefficient, and the deformation degree prediction is outputted;

[0061] Position state evaluation module: a position state evaluation model is constructed according to the horizontal gap distance between the nut and the positioning hole on the plate, the vertical spacing between the nut and the positioning hole on the plate and the plate welding surface roughness, and the position state coefficient is outputted;

[0062] Position state-deformation degree matching degree: under the influence of the positioning mechanism 4 on the nut clamping force and the nut verticality, a position state-deformation degree matching model is constructed according to the position state coefficient and the deformation degree prediction, and the position state-deformation degree matching degree is outputted;

[0063] Plate state adjustment module: a plate state adjustment model is constructed according to the preset support force of the support mechanism 3 on the plate and the position state-deformation degree matching degree, and the target support force of the support mechanism 3 is outputted;

[0064] The welding precision control system is electrically connected with the support mechanism 3 through the PLC controller.

[0065] In this embodiment, the welding state evaluation module refers to a calculation unit that normalizes the welding current, voltage and time parameters and fuses them into a welding state coefficient by using a Sigmoid function, which can be realized by using an industrial control computer loaded with a data processing algorithm, and is used to quantify the influence of welding heat input on workpiece deformation. The deformation degree prediction module refers to a calculation model that predicts thermal deformation by combining material linear expansion coefficient and welding state coefficient, which can be constructed by combining finite element simulation and data regression analysis, and is used to predict the deformation difference between the plate and the nut in advance. The position state evaluation module refers to a detection unit that evaluates the positioning accuracy of the nut through geometric gap measurement and surface roughness detection, which can be realized by using a laser displacement sensor in cooperation with a machine vision system, and is used to capture the initial assembly error. The position state-deformation degree matching degree module refers to a matching algorithm that coordinates the positioning accuracy and deformation compensation demand, which can be realized by using a fuzzy logic controller, and is used to determine the optimal support adjustment strategy. The plate state adjustment module refers to an execution unit that dynamically calculates the target support force according to the matching degree, which can be realized by using a servo motor to drive a pressure adjusting device, and is used to real-time correct the support force parameter.

[0066] Specifically, the current and voltage signals collected in real time during the welding process are input into the welding state evaluation model after normalization processing, and the state coefficient representing the heat input intensity is output. The coefficient and the material linear expansion coefficient are jointly input into the deformation degree prediction model to generate a deformation prediction to quantify the thermal deformation risk. At the same time, the visual system detects the gap data between the nut and the positioning hole, and calculates the position state coefficient combined with the roughness parameter. The matching degree module calculates the matching degree of the current state and the deformation trend by comprehensively matching the clamping force parameter and the position state coefficient. The flat plate state adjustment model dynamically adjusts the target support force through the hyperbolic tangent function according to the preset support force and the real-time matching degree, and the PLC controller drives the support mechanism 3 to execute pressure compensation, forming a negative feedback control loop of thermal deformation-support force.

[0067] Compared with the prior art, the traditional device cannot associate the welding parameters and support adjustment using open-loop control. The present scheme realizes adaptive adjustment of the support force by establishing a closed-loop control chain of welding state-deformation prediction-position evaluation. The prior art relies on fixed support parameters, and the present scheme realizes dynamic pressure compensation through matching degree calculation, effectively inhibiting the positioning deviation caused by thermal deformation. The existing positioning mechanism 4 only provides mechanical clamping, and the present scheme integrates gap detection and roughness evaluation, significantly improving the initial positioning accuracy.

[0068] As shown in Figure 2 As a preferred embodiment of the present application, the clamping mechanism 2 includes a fixed seat A21, an electric telescopic rod A22, and a U-shaped seat 23.

[0069] The welding table 1 is fixedly connected with two fixed seats A21, each fixed seat A21 is fixedly connected with an electric telescopic rod A22, the telescopic end of the electric telescopic rod A22 is fixedly connected with a U-shaped seat 23, the U-shaped seat 23 is fixedly connected with a guide rod 24, and the U-shaped seat 23 is also provided with a clamp 25, the clamp 25 is vertically slidably connected with the guide rod 24, and the two clamps 25 are oppositely arranged.

[0070] In this embodiment, two fixed seats A21 are symmetrically fixed on both sides of the welding table 1, and the U-shaped seat 23 is driven to move horizontally by the synchronous extension and retraction of the electric telescopic rod A22, so as to adjust the distance between the two clamps 25 to adapt to flat plates of different sizes. When the flat plate is placed between the two clamps 25, the electric telescopic rod A22 pushes the U-shaped seat 23 to move inward, so that the two clamps 25 contact the two sides of the flat plate. The guide rod 24 limits the clamp 25 to slide only in the vertical direction, ensuring that the clamp 25 does not deviate horizontally or tilt during clamping. During clamping, the clamp 25 can slide up and down along the guide rod 24 to adapt to slight differences in the thickness of the flat plate, avoiding local deformation of the flat plate due to excessive clamping force. The two oppositely arranged clamps 25 form a symmetrical clamping force in the horizontal direction, and at the same time release the constraint in the thickness direction through the vertical sliding structure, so as to maintain the natural flatness of the flat plate while ensuring the stability of the clamping.

[0071] Through the above technical solutions, the flat plate of different sizes can be stably clamped and the flatness thereof can be maintained, the horizontal deviation risk can be eliminated through symmetrical clamping force distribution, the thickness tolerance can be adaptively compensated through the vertical sliding structure, and local deformation caused by concentrated clamping force can be prevented, so as to provide a flat and position-accurate workpiece basis for subsequent welding procedures.

[0072] As shown in Figure 2 , as a preferred embodiment of the present application, the support mechanism 3 comprises a fixed frame 31, an electric push rod 32, a limiting plate 33 and a spring 34;

[0073] The bottom of the U-shaped seat 23 is fixedly connected with the fixed frame 31, the fixed frame 31 is fixedly connected with the electric push rod 32, the output end of the electric push rod 32 is fixedly connected with the limiting plate 33, and the guide rod 24 is sleeved with the spring 34, the spring 34 can elastically support the clamp 25, and the limiting plate 33 can vertically push the spring 34 to compress.

[0074] In this embodiment, when the electric push rod 32 drives the limiting plate 33 to move in the vertical direction, the displacement of the contact end of the limiting plate 33 and the spring 34 causes the spring 34 to compress and deform. The compression amount of the spring 34 is directly controlled by the displacement amount of the limiting plate 33, and the elastic force of the spring 34 is linearly related to the compression amount, so that the support force of the spring 34 can be continuously adjusted by adjusting the stroke of the electric push rod 32. During welding, when it is detected that the contact pressure changes due to thermal deformation of the flat plate, the electric push rod 32 adjusts the position of the limiting plate 33 in real time, changes the compression amount of the spring 34, and keeps the support force of the clamp 25 on the flat plate within a set range. The guide rod 24 provides axial constraint for the compression deformation of the spring 34, avoids lateral bending of the spring 34, and ensures that the elastic support force is in the same direction as the deformation direction of the flat plate.

[0075] By the technical scheme, the application solves the problem of poor contact caused by mismatch of supporting force due to thermal deformation in the welding process, and effectively avoids the generation of virtual welding or welding-through defects. The elastic supporting property of the spring 34 and the active adjusting capability of the electric push rod 32 are combined, so that the supporting mechanism 3 can adaptively compensate for the deformation of the flat plate and maintain stable contact pressure in the welding area, thereby improving the stability and consistency of the welding quality.

[0076] As shown in Figure 3 , as a preferred embodiment of the application, the positioning mechanism 4 comprises a guide rail A41, a sliding seat A42, and a driving rod A43;

[0077] The guide rail A41 is fixedly connected with the welding table 1 through a fixing seat B6, the sliding seat A42 is slidingly connected in the guide rail A41, and the driving rod A43 is threadedly connected with the sliding seat A42. The driving rod A43 drives the sliding seat A42 to slide along the guide rail A41 through thread transmission. The electric telescopic rod B44 is fixedly connected with the sliding seat A42, and the electric clamp 45 is fixedly connected with the telescopic end of the electric telescopic rod B44.

[0078] In this embodiment, the rigid cooperation of the guide rail A41 and the sliding seat A42 forms a horizontal reference plane, the thread transmission of the driving rod A43 is driven by a stepping motor, and each unit angle of rotation corresponds to a fixed displacement amount of the sliding seat A42, so as to accurately control the horizontal gap between the electric clamp 45 and the flat plate positioning hole. The electric telescopic rod B45 adjusts the telescopic length according to a preset program or a real-time detection signal, so that the vertical spacing between the nut and the positioning hole reaches a target value. When clamping the nut, the electric clamp 45 monitors the clamping force through the built-in pressure sensor, and automatically adjusts the opening angle of the clamping jaw when the clamping force is detected to exceed a threshold value, so as to ensure that the nut axis is perpendicular to the flat plate surface. The combined mechanism forms three-dimensional positioning constraints through mechanical precise adjustment of the horizontal gap, electric compensation of the vertical spacing, and closed-loop control of the clamping force, so that the spatial pose of the nut and the positioning hole meets the welding precision requirement.

[0079] As shown in Figure 4 , as a preferred embodiment of the application, the welding mechanism 5 comprises a guide rail B51, a sliding seat B52, and a driving rod B53;

[0080] The guide rail B51 is fixedly connected with the welding table 1 through a fixing seat C7, the sliding seat B52 is slidingly connected in the guide rail B51, and the driving rod B53 is threadedly connected with the sliding seat B52. The driving rod B53 drives the sliding seat B52 to slide along the guide rail B51 through thread transmission. The electric telescopic rod C54 is fixedly connected with the sliding seat B52, and the welding machine 55 is fixedly connected with the telescopic end of the electric telescopic rod C54.

[0081] In this embodiment, the rigid connection of the guide rail B51 and the fixed seat C7 forms a stable movement reference plane, eliminating the influence of the welding table 1 vibration on the welding gun movement trajectory. The drive rod B53 pushes the sliding seat B52 to slide along the guide rail B51 through threaded transmission, and the non-reverse clearance characteristic of the ball screw can avoid the positioning error accumulation caused by mechanical clearance in the traditional gear and rack transmission. The precise gap between the sliding seat B52 and the guide rail B51 further restricts the freedom of the welding gun in the horizontal plane, ensuring that the welding gun only moves along the predetermined trajectory. The electric telescopic rod C54 adjusts the vertical height of the welding gun in real time through axial telescoping, and when the plate thickness changes or the height difference exists on the nut welding surface, the contact distance between the welding gun and the workpiece can be dynamically corrected. The combination structure provides accurate displacement through threaded transmission, restricts the degree of freedom through guide rail, and compensates for the vertical error through telescopic rod, forming a closed-loop control of three-dimensional space pose, thereby suppressing the welding position deviation caused by transmission clearance and structural deformation of the traditional sliding table.

[0082] As a preferred embodiment of the present application, the welding current, welding voltage and welding time of the welding mechanism 5 are substituted into the maximum and minimum value normalization formula respectively for processing, and welding current index, welding voltage index and welding time index are obtained respectively;

[0083] The welding state evaluation model is:

[0084] ;

[0085] wherein is a welding current weight coefficient, is a welding voltage weight coefficient, is a welding time weight coefficient, is a welding current index, is a welding voltage index, is a welding time index, is a welding state coefficient.

[0086] In this embodiment, the maximum and minimum value normalization formula refers to a data processing method for linearly transforming original parameters to the [0, 1] interval, which is used to eliminate the numerical difference of parameters with different dimensions. The welding state evaluation model refers to a mathematical expression for fusing multiple parameters through a logistic regression model, which can specifically use a Sigmoid function as an activation function to realize the mapping of normalized parameters in linear combination to continuous variables between 0 and 1. The welding current weight coefficient, the welding voltage weight coefficient and the welding time weight coefficient refer to the relative importance parameters of the influence of each parameter on heat input, which can be obtained by training historical welding data and are used to quantify the influence degree of different parameters on the welding state.

[0087] Specifically, after the welding current, voltage and time parameters are collected, the dimension difference is first eliminated by maximum minimum value normalization processing to obtain standardized welding current index, voltage index and time index. The normalized parameters are linearly combined with the preset weight coefficients to input the Sigmoid function to generate the welding state coefficient. The coefficient dynamically reflects the comprehensive state of the welding heat input, and when the parameter fluctuation causes the linear combination value to deviate from the normal range, the welding state coefficient changes accordingly. For example, when the welding current is too high and the time is too long, the linear combination value increases, causing the welding state coefficient to tend to 1, indicating the risk of excessive heat input. By calculating the welding state coefficient in real time, the system can identify abnormal parameter combinations and provide a quantitative basis for subsequent deformation prediction.

[0088] As a preferred embodiment of the present application, the welded plate thickness, nut diameter, and plate linear expansion coefficient and nut linear expansion coefficient are respectively substituted into the maximum normalization formula for processing, and the plate thickness index, nut diameter index, plate linear expansion index and nut linear expansion index are respectively obtained.

[0089] The deformation degree prediction model is:

[0090] ;

[0091] wherein is the welding piece specification influence weight coefficient, is the plate linear expansion influence weight coefficient, is the nut linear expansion influence weight coefficient, is the plate thickness index, is the nut diameter index, is the plate linear expansion index, is the nut linear expansion index, is the welding state coefficient, is the deformation degree prediction.

[0092] In this embodiment, the welding piece specification influence weight coefficient refers to an adjustment parameter representing the influence of plate thickness and nut diameter on structural stiffness, which can be determined by experimental calibration or numerical simulation method, and is used to reflect the dominant effect of geometric size difference on thermal deformation. Among them, the plate linear expansion influence weight coefficient refers to a parameter representing the contribution degree of the thermal expansion characteristics of the plate material to the deformation, which can be obtained by fitting the welding test data combined with thermodynamic simulation, and is used to quantify the coupling effect of material thermal expansion and welding heat input. Among them, the nut linear expansion influence weight coefficient refers to a parameter representing the contribution degree of the thermal expansion characteristics of the nut material to the deformation, which can be determined by comparing the welding deformation data of different material combinations, and is used to distinguish the thermal response difference between the plate and the nut material.

[0093] Specifically, in the welding process, the plate thickness and the nut diameter are normalized to form a geometric parameter index, and the product of the geometric parameter index and the welding state index is multiplied by a weight coefficient to reflect the comprehensive influence of the synergistic effect of the two on the structural deformation resistance. The linear expansion coefficients of the plate and the nut are normalized, respectively, and multiplied by the welding state coefficient , and then the weight coefficients are superimposed and to form a thermal expansion dynamic coupling term and , thereby relating the welding heat input intensity to the material thermal expansion characteristics. By adjusting the proportional relationship of each weight coefficient, the differentiated contributions of geometric constraints, material thermal expansion, and welding heat input to deformation can be accurately distinguished, and the final output is a quantitative deformation degree estimate.

[0094] Through the above technical solution, the present application can dynamically predict the deformation amount caused by the difference in thermal expansion between the plate and the nut during the welding process, solving the deformation prediction deviation problem caused by ignoring the synergistic effect of geometric size and material characteristics in the prior art, providing accurate deformation data basis for subsequent support force adjustment, thereby effectively improving the welding position accuracy and avoiding assembly errors caused by thermal deformation.

[0095] As a preferred embodiment of the present application, the horizontal gap distance between the nut and the positioning hole on the plate, the vertical spacing between the nut and the positioning hole on the plate, and the plate welding surface roughness are respectively substituted into the maximum value normalization formula for processing, and the horizontal gap index, the vertical spacing index, and the plate roughness index are respectively obtained;

[0096] The position state evaluation model is:

[0097] ;

[0098] wherein is the horizontal gap influence weight coefficient, is the vertical spacing influence weight coefficient, is the plate roughness influence weight coefficient, , and , and are all greater than 0, is the horizontal gap index, is the vertical spacing index, is the plate roughness index, is the position state coefficient.

[0099] In this embodiment, the clamping force index is the ratio of the actual clamping force exerted by the positioning mechanism 4 to the theoretical maximum clamping force, the verticality index is the cosine value of the angle between the nut axis and the preset vertical direction, the position state coefficient is a parameter representing the initial positioning accuracy of the nut, the deformation degree estimation is a parameter for predicting the strength of the welding thermal deformation, the constant is a correction quantity to prevent the denominator from being zero, and the position state-deformation degree matching degree is an index reflecting the dynamic relationship between clamping stability and thermal deformation.

[0100] wherein the clamping force index is a dimensionless parameter converted from the actual clamping force by a maximum value normalization formula, which can be calculated by inputting the real-time measured clamping force into the normalization formula using a pressure sensor, and is used to eliminate the dimensional differences of clamping forces required for nuts of different specifications. The verticality index is a directional consistency parameter calculated from the nut inclination angle obtained by an angle measuring device, which can be converted from the height difference of the nut edge detected by a laser displacement sensor, and is used to quantify the pose deviation generated during clamping. The position state coefficient is a positioning accuracy parameter calculated by comprehensively considering the horizontal gap, vertical spacing and surface roughness, which can be calculated by a model after measuring the actual assembly gap using a vision detection system, and is used to reflect the initial positioning quality of the nut. The deformation degree estimation is a deformation strength parameter predicted based on welding parameters and material properties, which can be calculated using a thermal-mechanical coupling simulation model, and is used to represent the dynamic change trend of welding thermal deformation. The constant is a preset small positive number, which can be set to an order of magnitude ten times the calculation accuracy, and is used to avoid numerical calculation abnormalities caused by the denominator approaching zero. 、 and respectively represent the influence weight of the horizontal gap index, the vertical spacing index and the plate roughness index on the position state coefficient, which can be determined by experimental calibration or numerical simulation method.

[0101] Specifically, the clamping force index is normalized by the actual clamping force and the maximum clamping force of the equipment, making the clamping effect of nuts of different specifications comparable. The verticality index converts the angle deviation into a directional consistency parameter by a cosine function, which reaches the maximum value when the nut is completely vertical. In the matching model, the product term of the clamping force index and the verticality index reflects the compensation effect of clamping stability on the position state, and the deformation degree estimation and the constant in the denominator form a dynamic reference value. When the clamping force is insufficient or the nut is inclined, the matching degree decreases due to the decrease of the numerator value, at which time the support mechanism 3 adjusts the support force to offset the influence of thermal deformation. For example, when the welding thermal deformation causes the plate to warp, the deformation degree estimation increases, which reduces the matching degree, at which time the support force is increased to suppress the deformation.

[0102] By the technical solution, the application solves the problem of positioning accuracy reduction caused by clamping force fluctuation and verticality deviation, and through dynamic matching of position state and thermal deformation degree, the support mechanism 3 can adjust the support force according to the real-time matching degree. The introduction of the clamping force index eliminates the clamping parameter difference of nuts of different specifications, and the cosine conversion of the verticality index strengthens the importance of vertical clamping. The superposition of the deformation degree estimation and the constant in the denominator avoids the calculation anomaly in the extreme working condition, and ensures the reliability of the matching degree index.

[0103] As a preferred embodiment of the application, the nut clamping force of the positioning mechanism 4 and the nut verticality are respectively substituted into the maximum normalization formula for processing, and the clamping force index and the verticality index are respectively obtained.

[0104] The position state-deformation degree matching model is:

[0105]

[0106] Among them, the clamping force index, the verticality index, the position state coefficient, the deformation degree estimation, the constant, the position state-deformation degree matching degree.

[0107] In this embodiment, the clamping force index refers to the value after the clamping force is standardized by the maximum normalization method, which can be realized by calculating the ratio of the actual measurement value to the preset maximum clamping force after the clamping force is measured in real time by a pressure sensor, and is used to eliminate the dimensional difference of the clamping force required by nuts of different specifications, and reflects the stable clamping ability of the clamping mechanism 2 to the nut. The verticality index refers to the normalized processing result of the angle value after the angle between the nut axis and the vertical direction is obtained by an angle measuring device, which can be realized by measuring the inclination angle by a laser range finder or an inclination sensor, and then converting it by ratio with the maximum allowed deviation angle, which is used to quantitatively represent the spatial posture deviation of the nut. The position state coefficient refers to the position stability index calculated based on the horizontal gap, the vertical distance and the surface roughness, which can be evaluated by measuring the gap data by a visual detection system and combining the detection result of a roughness meter, and is used to reflect the initial positioning accuracy of the nut. The deformation degree estimation refers to the comprehensive influence value of the prediction of the thermal deformation on the position accuracy, which can be obtained by a thermodynamic simulation model combined with real-time welding parameters, and is used to represent the deformation trend caused by heat input. The constant ε is a very small positive number used to prevent the denominator from being zero, which is used to ensure the numerical stability of the model calculation.

[0108] ​Specifically, during the welding process, the clamping force sensor collects the clamping force data applied by the positioning mechanism 4 in real time, and converts it into a clamping force index in the range of 0-1 through a maximum value normalization formula. At the same time, the tilt angle sensor measures the angle between the nut axis and the vertical direction, and obtains the verticality index after normalization processing. The position state coefficient is calculated from the gap data and surface roughness data detected by the vision system, and the deformation degree estimate is generated by the welding parameter and material attribute prediction model. After substituting the above parameters into the matching model, the product of the clamping force index and the cosine value of the verticality constitutes the numerator term, reflecting the positive contribution of clamping stability to position accuracy; the superposition of the deformation degree estimate and the constant constitutes the denominator term, representing the negative impact of thermal deformation on matching degree. This model calculates the real-time matching degree value through the dynamic coupling of clamping state and thermal deformation, providing a quantitative basis for subsequent support force adjustment.

[0109] Compared with the prior art, the existing positioning mechanism 4 only maintains the position of the nut by fixing the clamping force, and cannot perceive the influence of clamping force fluctuations and verticality deviations on welding accuracy, and lacks a compensation mechanism when thermal deformation occurs. The present scheme builds a quantitative evaluation system of clamping force and verticality, and combines a dynamic matching model of position state and deformation prediction, realizing real-time interactive analysis of clamping stability and thermal deformation trend during the welding process, and breaking through the technical limitations of the disconnection between clamping parameters and thermal response in traditional equipment.

[0110] As a preferred embodiment of the present application, the flat state adjustment model is:

[0111] ;

[0112] wherein is a preset support force, is an adjustment gain coefficient, is a position state-deformation degree matching degree, is a matching degree reference value, is a target support force.

[0113] In this embodiment, the preset support force refers to the initial support force preset before welding according to the flat plate material and thickness, which can be realized by closed-loop control of a pressure sensor and an electric push rod 32, and is used to maintain the stable support of the flat plate in the undeformed state. The adjustment gain coefficient refers to a proportional parameter for controlling the adjustment amplitude of the support force, which can be dynamically optimized by experimental calibration or adaptive algorithm, and is used to adjust the support force change rate to avoid system oscillation. The position state-deformation degree matching degree refers to a quantitative index reflecting the dynamic relationship between the nut position deviation and the thermal deformation, which can be obtained by fusion calculation of the position sensor and the deformation prediction model, and is used to represent the urgency of the current support force adjustment. The matching degree reference value refers to the ideal matching degree threshold when the system is in a balanced state, which can be set as an empirical constant according to the welding process specification, and is used as a reference benchmark for support force adjustment. The target support force refers to the real-time dynamic support force required to be applied to the flat plate after model calculation, which can be executed by a PLC controller driving the electric push rod 32, and is used to compensate for the contact surface state change caused by thermal deformation.

[0114] Specifically, the model takes the preset support force as the reference, and converts the matching degree deviation into a nonlinear adjustment amount through the hyperbolic tangent function. When the actual matching degree exceeds the reference value, the saturation characteristic of the hyperbolic tangent function automatically limits the adjustment amplitude of the support force, avoiding system instability caused by excessive compensation. The adjustment gain coefficient controls the slope of the support force change curve, ensuring fine tuning when the matching degree deviates slightly and rapid response when the matching degree deviates seriously. The model continuously updates the target support force parameter by real-time acquisition of position state and deformation prediction data, forming a closed-loop control loop.

[0115] Compared with the prior art, the traditional support mechanism 3 adopts a fixed preset support force, which cannot respond to the dynamic change of the thermal deformation during welding, resulting in mismatch between the support force and the workpiece state. The present scheme establishes a nonlinear mapping relationship between the matching degree and the support force, and can automatically adjust the support force according to the real-time welding state, starting the compensation mechanism at the initial stage of thermal deformation. The passive support system in the prior art lacks predictive adjustment capability, while the present scheme combines position detection and deformation prediction data to realize feedforward-feedback compound control of the support force.

[0116] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A flat nut automated welding machine comprising a welding table, characterized in that, The welding station is provided with a clamping mechanism for clamping the plate, the clamping mechanism is connected with a supporting mechanism for elastically supporting the plate, one side of the clamping mechanism is provided with a positioning mechanism for positioning the nut, one side of the positioning mechanism is provided with a welding mechanism for welding the plate and the nut, and the welding precision control system comprises: The welding state evaluation module: a welding state evaluation model is constructed according to the welding current, welding voltage and welding time of the welding mechanism, and a welding state coefficient is output; The deformation degree prediction module: a deformation degree prediction model is constructed according to the welding state coefficient, the plate linear expansion coefficient and the nut linear expansion coefficient under the influence of the plate thickness and the nut diameter, and a deformation degree prediction value is output; The position state evaluation module: a position state evaluation model is constructed according to the horizontal gap distance between the positioning holes on the nut and the plate, the vertical spacing between the positioning holes on the nut and the plate and the plate welding surface roughness, and a position state coefficient is output; The position state-deformation degree matching degree: a position state-deformation degree matching model is constructed according to the position state coefficient and the deformation degree prediction value under the influence of the nut clamping force and the nut verticality of the positioning mechanism, and a position state-deformation degree matching degree is output; The plate state adjustment module: a plate state adjustment model is constructed according to the preset supporting force of the supporting mechanism on the plate and the position state-deformation degree matching degree, and a target supporting force of the supporting mechanism is output; The welding precision control system is electrically connected with the supporting mechanism through the PLC controller; The nut clamping force and the nut verticality of the positioning mechanism are respectively substituted into the maximum value normalization formula for processing, and a clamping force index and a verticality index are respectively obtained; the position state-deformation degree matching model is: ； wherein is a clamping force index, is a verticality index, is a position status coefficient, is a deformation degree estimation, is a constant, is a position status-deformation degree matching degree; The plate state adjustment model is: ； wherein is a preset support force, is an adjustment gain coefficient, is a position state-deformation degree matching degree, is a matching degree reference value, is a target support force.

2. The flat nut automated welding machine according to claim 1, wherein The clamping mechanism comprises a fixed seat A, an electric telescopic rod A and a U-shaped seat; Two fixed seats A are fixedly connected on the welding station, each fixed seat A is fixedly connected with an electric telescopic rod A, the telescopic ends of the electric telescopic rods A are fixedly connected with U-shaped seats, guide rods are fixedly connected in the U-shaped seats, clamps are further arranged in the U-shaped seats, and the clamps are vertically slidably connected with the guide rods. Two clamps are oppositely arranged.

3. The flat nut automated welding machine according to claim 2, wherein, The supporting mechanism comprises a fixed frame, an electric push rod, a limiting plate and a spring; The bottom of the U-shaped seat is fixedly connected with the fixed frame, the fixed frame is fixedly connected with the electric push rod, the output end of the electric push rod is fixedly connected with the limiting plate, the guide rods are all sleeved with springs, the springs can elastically support the clamps, and the limiting plate can vertically push the springs to be compressed.

4. The flat nut automated welding machine of claim 1, wherein, The positioning mechanism comprises a guide rail A, a sliding seat A and a driving rod A; The guide rail A is fixedly connected with the welding station through a fixed seat B, the guide rail A is slidably connected with the sliding seat A, the sliding seat A is threadedly connected with the driving rod A, the driving rod A drives the sliding seat A to slide along the guide rail A through thread transmission, the sliding seat A is fixedly connected with an electric telescopic rod B, and the telescopic end of the electric telescopic rod B is fixedly connected with an electric clamp.

5. The flat nut automated welding machine of claim 1, wherein, The welding mechanism comprises a guide rail B, a sliding seat B and a driving rod B; The guide rail B is fixedly connected with the welding table through the fixing base C, the guide rail B is slidably connected with the sliding base B, the sliding base B is threadedly connected with the driving rod B, the driving rod B drives the sliding base B to slide along the guide rail B through threaded transmission, the sliding base B is fixedly connected with the electric telescopic rod C, and the telescopic end of the electric telescopic rod C is fixedly connected with the welding machine.

6. The flat nut automated welding machine of claim 1, wherein, The welding current, the welding voltage and the welding time of the welding mechanism are substituted into the maximum-minimum value normalization formula respectively for processing, and the welding current index, the welding voltage index and the welding time index are obtained respectively; The welding state evaluation model is: ； wherein is a welding current weight coefficient, is a welding voltage weight coefficient, is a welding time weight coefficient, is a welding current index, is a welding voltage index, is a welding time index, is a welding condition coefficient.

7. The flat nut automated welding machine of claim 6, wherein, The thickness of the welded plate, the diameter of the nut, the linear expansion coefficient of the plate and the linear expansion coefficient of the nut are substituted into the maximum value normalization formula respectively for processing, and the thickness index, the diameter index, the plate linear expansion index and the nut linear expansion index are obtained respectively; The deformation degree prediction model is: ； wherein is a weight coefficient of the plate thickness, is a weight coefficient of the plate linear expansion, is a weight coefficient of the nut linear expansion, is a plate thickness index, is a nut diameter index, is a plate linear expansion index, is a nut linear expansion index, is a welding state coefficient, is a deformation degree estimation.

8. The flat nut automated welding machine according to claim 7, wherein, The horizontal gap distance between the nut and the positioning hole on the plate, the vertical spacing between the nut and the positioning hole on the plate and the plate welding surface roughness are substituted into the maximum value normalization formula respectively for processing, and the horizontal gap index, the vertical spacing index and the plate roughness index are obtained respectively; The position state evaluation model is: ； wherein is a horizontal gap influence weight coefficient, is a vertical separation influence weight coefficient, is a flat roughness influence weight coefficient, is a horizontal gap index, is a vertical separation index, is a flat roughness index, is a position state coefficient.

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