A real-time tracking off-axis wire feeder for complex lap welds and method

Abstract

The present application relates to the field of welding, and discloses a kind of real-time tracking complex lap weld seam's off-axis wire feeder, the device includes wire feeder gun, the wire feeder gun includes wire feeder gun head, first wire feeder gun body, second wire feeder gun body, the wire feeder gun head is connected with the first wire feeder gun body front end, the rear end of the first wire feeder gun body is connected with the pressure sensor arranged in the bottom of second wire feeder gun body by elastic element, the second wire feeder gun body is provided with photosensitive plate, light source, the photosensitive plate is oppositely arranged with light source, the welding wire channel in the wire feeder gun is connected with wire feeder through wire feeder pipeline, the bottom of the wire feeder gun is connected with movement mechanism, the photosensitive plate, movement mechanism, pressure sensor are connected with industrial computer.The present application solves the problem that the existing lap weld seam tracking means is difficult to track with high precision, and is easy to cause welding heat source or welding wire to deviate from the welding position and burn the welding piece or produce welding defects such as welding spatter when welding.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding, more particularly to a side-shaft wire feeding device and method for real-time tracking of complex lap welds. BACKGROUND

[0002] Lap joints are very common joint forms in today's industrial manufacturing, and most of such joints are welded by the method of melting wire. Maintaining the precision and stability of wire feeding is the key to ensuring the quality of lap welds. If the wire feeding position deviates from the weld or the wire feeding speed is too slow, the lap weld will not be filled in time and will be burned out. If the wire feeding speed is too fast, the wire will stick to the molten pool or produce spatter.

[0003] In addition, some lap joint welds in actual production are inclined lap welds, S-shaped lap welds or complex lap welds with irregular contours, such as ship skeletons or automobile bodies. In actual welding, the welding robot needs to be manually programmed before welding to accurately find the welding position, otherwise it is easy to cause the welding heat source or the wire to deviate from the welding position, resulting in the burning of the welded part or the generation of welding defects such as spatter. Although there are currently various weld tracking methods, such as visual tracking based on image processing and non-visual tracking based on peripheral sensors. However, due to the variable contour of the complex lap weld welding position, the asymmetry of the two sides of the welding position or the complexity and bulkiness of the weld tracking device, it is difficult to use existing weld tracking methods for high-precision tracking, which is easy to cause the welding heat source or the wire to deviate from the welding position during welding, resulting in the burning of the welded part or the generation of welding defects such as spatter. SUMMARY

[0004] To solve the problem that the existing lap weld tracking method in the prior art is difficult to track with high precision, which is easy to cause the welding heat source or the wire to deviate from the welding position during welding, resulting in the burning of the welded part or the generation of welding defects such as spatter, the present application provides a side-shaft wire feeding device and method for real-time tracking of complex lap welds.

[0005] The specific scheme adopted by the present application is as follows: a side-shaft wire feeding device for real-time tracking of complex lap welds, the device comprising a wire feeding gun, the wire feeding gun comprising a wire feeding gun head, a first wire feeding gun body and a second wire feeding gun body, the wire feeding gun head being connected to the front end of the first wire feeding gun body, the rear end of the first wire feeding gun body being connected to a pressure sensor arranged at the bottom of the second wire feeding gun body through an elastic member, a photosensitive plate and a light source being arranged in the second wire feeding gun body, the photosensitive plate being arranged opposite to the light source, a wire channel in the wire feeding gun being connected to a wire feeder through a wire feeding pipeline, the bottom of the wire feeding gun being connected to a movement mechanism, the photosensitive plate, the movement mechanism and the pressure sensor all being connected to an industrial computer.

[0006] The light source is a strip-shaped light source.

[0007] The first wire feeder body is sleeved in the second wire feeder body, and the photosensitive plate, the light source and the elastic member are arranged at intervals.

[0008] The second wire feeder body is connected with one end of the screw rod mechanism, and a welding heat source is arranged on the screw rod guide of the screw rod mechanism.

[0009] The motion mechanism is a three-axis motion mechanism, and the three-axis motion mechanism is a three-axis mechanical arm.

[0010] The photosensitive plate comprises a photosensitive resistor, the photosensitive resistor comprises a semiconductor, metal electrodes are arranged at two ends of the semiconductor, and a glass bottom plate is arranged at the bottom of the semiconductor; and the photosensitive resistor is connected with a protective resistor, a galvanometer, a protective resistor and a power supply in series.

[0011] The galvanometer is connected with the industrial computer.

[0012] A signal sensor is arranged on the screw rod guide, and the signal sensor is connected with the industrial computer.

[0013] In another aspect, the present application provides a side-axis wire feeding method for tracking a complex lap joint weld in real time, which comprises the following steps:

[0014] Step one: finding a starting point: the motion mechanism drives the wire feeder to step along a direction perpendicular to the welding direction, and when the elastic member is compressed and shrunk, it indicates that the wire feeder contacts the lap joint weld at this moment, and the pressure sensor reading gradually rises; when the pressure sensor reading reaches a preset threshold value, the wire feeder is stopped and the point is recorded as the starting point and saved to the industrial computer;

[0015] Step two: contour identification: the motion mechanism drives the wire feeder to step along the welding direction, and the elastic member freely stretches and shrinks according to the lap joint weld contour, driving the first wire feeder body to enter and exit the second wire feeder body; the first wire feeder body affects the change of the light receiving area of the photosensitive plate and the pressure sensor, the photosensitive plate transmits signals to the industrial computer, and the change amount of the light receiving area of the photosensitive plate and the change amount of the pressure sensor reading during the process are recorded, reflecting the contour shape of the complex lap joint weld;

[0016] Step three: finding an end point: when the wire feeder is separated from the weld, the industrial computer controls the motion mechanism to drive the wire feeder to step in a direction perpendicular to the weld; if the step counter reading of the industrial computer reaches a preset threshold value and the pressure sensor reading is still zero, it can be judged that the weld has reached the end point;

[0017] Step four: welding preparation: after determining the end point, the industrial computer controls the motion mechanism to drive the wire feeder to return to the starting point by the steps of retracting along a direction perpendicular to the welding direction, retreating along the welding direction, and advancing along a direction perpendicular to the welding direction; the motion mechanism drives the wire feeder to retreat along a direction perpendicular to the welding direction and ascend to reach the welding starting point.

[0018] Step five: after the welding wire is sent to the welding seam at a uniform speed by the wire feeder controlled by the industrial computer, the motion mechanism is driven by the industrial computer to step along the welding seam direction and start welding, the wire feeder is continuously adjusted by the industrial computer according to the change amount of the light receiving area of the previous light board and the change amount of the pressure sensor reading to change the wire feeding speed, so as to keep the relative distance between the welding wire and the welding seam unchanged, the motion mechanism is controlled by the industrial computer according to the stepping record of the stepping counter to step or retreat in the direction perpendicular to the welding direction, and the distance between the welding heat source and the welding wire is continuously adjusted by the industrial computer according to the change amount of the light receiving area of the previous light board and the change amount of the pressure sensor reading, so as to keep the welding heat source above the welding seam all the time, and the effect of welding seam tracking is achieved.

[0019] After the contour recognition in the step, if the pressure sensor reaches the preset maximum value or the preset minimum value during the stepping of the motion mechanism along the welding direction, the following two steps are respectively processed:

[0020] If the pressure sensor reading is not less than the preset maximum value: the motion mechanism drives the welding wire feeder to retreat in the direction perpendicular to the welding direction, and the stepping counter in the industrial computer is added by 1 every time the welding wire feeder retreats once, when the pressure sensor reading reaches the preset threshold value, the welding wire feeder retreats is stopped and the retreat times are recorded to the industrial computer, the contour recognition step is returned and the stepping counter in the industrial computer is cleared.

[0021] If the pressure sensor reading is not less than the preset minimum value: the motion mechanism drives the welding wire feeder to step in the direction perpendicular to the welding direction, and the stepping counter in the industrial computer is added by 1 every time the welding wire feeder steps once, when the pressure sensor reading reaches the preset threshold value, the welding wire feeder feeding is stopped and the retreat times are recorded to the industrial computer, the contour recognition step is returned and the stepping counter in the industrial computer is cleared.

[0022] The present application has the following beneficial effects compared with the prior art:

[0023] The application discloses a kind of tracking complex lap weld seam's off-axis wire feeder and method, the device includes wire feeder gun, wire feeder gun includes wire feeder gun head, first wire feeder gun body, second wire feeder gun body, first wire feeder gun body is inserted into the inside of second wire feeder gun body, wire feeder gun head is connected with the front end of first wire feeder gun body, the rear end of first wire feeder gun body is connected with the pressure sensor arranged in the bottom of second wire feeder gun body by elastic member, light-sensitive plate is arranged in second wire feeder gun body, light source is arranged, light-sensitive plate is oppositely arranged with light source, the welding wire channel in wire feeder gun is connected with wire feeder by wire feeder pipeline, the bottom of wire feeder is connected with movement mechanism, the light-sensitive plate, movement mechanism, pressure sensor are connected with industrial computer, the pressure of gun head is sensed by pressure sensor, to thereby feedback pressure to industrial computer, and combining the shielding of first wire feeder gun body to light source in second wire feeder gun body, the problem that existing weld seam tracking means is difficult to track with high precision is solved, welding heat source or welding wire is easily deviated from the part to be welded when welding, and welding defects such as welding spatter and burning loss of welded part are caused. On the other hand, the present application is applied to the tracking and welding process of complex lap weld seam, can complete the automatic tracking and welding task of complex lap weld seam, solves the problems of difficult manual operation, high labor intensity, manual operation cannot reach in part welding environment and the like, has the advantages of high weld seam tracking efficiency, high precision, high intelligent degree, good welding quality and the like. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 it is the internal structure schematic diagram of wire feeder gun of the present application;

[0025] Figure 2 it is the connection relationship schematic diagram of first wire feeder gun body and second wire feeder gun body of the present application;

[0026] Figure 3 it is the top view of wire feeder gun of the present application;

[0027] Figure 4 it is the structure schematic diagram of off-axis wire feeder of the present application;

[0028] Figure 5 it is the complex lap weld seam contour identification process schematic diagram of the present application;

[0029] Figure 6 it is the profile identification preparation schematic diagram in the method of the present application;

[0030] Figure 7 it is the starting point finding schematic diagram in the method of the present application;

[0031] Figure 8 it is the beginning to identify profile schematic diagram in the method of the present application;

[0032] Figure 9 it is the termination point determination schematic diagram in the method of the present application;

[0033] Figure 10 Schematic diagram for finding the welding starting point in the method of the present application;

[0034] Figure 11 Schematic diagram for starting welding in the method of the present application;

[0035] Figure 12 Schematic diagram for ending welding in the method of the present application;

[0036] Figure 13 Flow chart for tracking the weld in the present application.

[0037] In the figure: 1, welding wire; 2, welding wire channel; 3, wire feeder head; 4, first wire feeder body; 5, second wire feeder body; 6, light source; 7, photosensitive plate; 8, elastic member; 9, pressure sensor; 10, wire feeding pipeline; 11, wire feeder; 12, wire feeding disc; 13, movement mechanism; 14, lead screw mechanism; 15, welding heat source; 16, industrial computer; 17, power supply; 18, protective resistor; 19, metal electrode; 20, semiconductor; 21, glass bottom plate; 22, galvanometer; 23, wire feeder; 24, lap welding structural member; 25, lap weld. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the present application clearer and more comprehensible, the present application will be described below through specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0039] The present application discloses a kind of real-time tracking complex lap weld's side shaft wire feeder device, the device includes wire feeder gun 23, the wire feeder gun 23 includes wire feeder gun head 3, first wire feeder gun body 4, second wire feeder gun body 5, the wire feeder gun head 3 is connected with the first wire feeder gun body 4 front end, the rear end of the first wire feeder gun body 4 is connected with the pressure sensor 9 arranged in the bottom of second wire feeder gun body 5 by elastic member 8, light-sensitive plate 7, light source are arranged in the second wire feeder gun body 5, the light-sensitive plate 7 is oppositely arranged with light source 6, the welding wire channel 2 in the wire feeder gun 23 is connected with wire feeder 11 by wire feeder pipe 10, the bottom of the wire feeder gun 23 is connected with movement mechanism 13, the light-sensitive plate 7, movement mechanism 13, pressure sensor 9 are connected with industrial computer 16.The first wire feeder gun body 4 is sleeved in the second wire feeder gun body 5, the light-sensitive plate 7, light source 6 and elastic member 8 are spaced apart, and there is no interference in working space.The light source 6 is strip light source.In one embodiment, the strip light source is arranged in the mode of being closely attached to the second wire feeder gun body and being arranged vertically downward.The industrial computer in the application is a conventional computer of prior art, and the step counter is a conventional counting software in the computer.The front end of the second wire feeder gun body is provided with a circular through hole, the size of the through hole is matched with the size of the first wire feeder gun body, so that the first wire feeder gun body can move relative to the second wire feeder gun body, and the wire feeder gun head 3 is connected with the first wire feeder gun body 4 in the mode of welding.

[0040] The second wire feeder gun body 5 is connected with one end of the lead screw mechanism 14, and the lead screw guide rail on the lead screw mechanism 14 is provided with a welding heat source 15.The movement mechanism 13 is a three-axis movement mechanism 13, and the three-axis movement mechanism 13 is a three-axis mechanical arm.The light-sensitive plate can be a light-sensitive plate of prior art, or a light-sensitive plate as follows: the light-sensitive plate includes a photosensitive resistor, the photosensitive resistor includes a semiconductor 20, metal electrodes 19 are arranged at both ends of the semiconductor 20, and a glass bottom plate 21 is arranged at the bottom of the semiconductor 20; the photosensitive resistor is connected in series with a protective resistor 18, a galvanometer 22 and a power supply 17.The galvanometer 22 is connected with the industrial computer 16.The light-sensitive plate 7, the movement mechanism 13, the pressure sensor 9 and the galvanometer in the application are signal-connected with the industrial computer 16.A signal sensor is arranged on the lead screw guide rail, and the signal sensor is connected with the industrial computer 16.The wire feeder in the application is a variable-speed wire feeder.

[0041] The present application discloses a kind of real-time tracking complex lap weld's side shaft wire feeder device, the device includes wire feeder gun 23, the wire feeder gun 23 includes wire feeder gun head 3, first wire feeder gun body 4, second wire feeder gun body 5, the wire feeder gun head 3 is connected with the first wire feeder gun body 4 front end, the rear end of the first wire feeder gun body 4 is connected with the pressure sensor 9 arranged in the bottom of second wire feeder gun body 5 by elastic member 8, light-sensitive plate 7, light source are arranged in the second wire feeder gun body 5, the light-sensitive plate 7 is oppositely arranged with light source 6, the welding wire channel 2 in the wire feeder gun 23 is connected with wire feeder 11 by wire feeder pipe 10, the bottom of the wire feeder gun 23 is connected with movement mechanism 13, the light-sensitive plate 7, movement mechanism 13, pressure sensor 9 are connected with industrial computer 16.The first wire feeder gun body 4 is sleeved in the second wire feeder gun body 5, the light-sensitive plate 7, light source 6 and elastic member 8 are spaced apart, and there is no interference in working space.The light source 6 is strip light source.In one embodiment, the strip light source is arranged in the mode of being closely attached to the second wire feeder gun body and being arranged vertically downward.The industrial computer in the application is a conventional computer of prior art, and the step counter is a conventional counting software in the computer.The front end of the second wire feeder gun body is provided with a circular through hole, the size of the through hole is matched with the size of the first wire feeder gun body, so that the first wire feeder gun body can move relative to the second wire feeder gun body, and the wire feeder gun head 3 is connected with the first wire feeder gun body 4 in the mode of welding.

[0042] Step one: find the starting point P: the motion mechanism 13 drives the wire feeder 23 to step along the direction perpendicular to the welding direction, when the elastic member 8 is compressed and shrunk, it indicates that the wire feeder 23 contacts the lap weld at this moment, the pressure sensor 9 shows the gradually rising, when the pressure sensor 9 shows the preset threshold F0, stop the wire feeder 23 feeding and save this point as the starting point to the industrial computer 16; step two: the motion mechanism 13 drives the wire feeder 23 to step along the welding direction, the elastic member is a spring, the elastic member 8 can be freely stretched and contracted according to the lap weld profile, drive the first wire feeder body 4 to enter and exit the second wire feeder body 5, further affect the light receiving area of the photosensitive plate 7 and the change of the pressure sensor 9, respectively use the industrial computer 16 to record the change of the light receiving area of the photosensitive plate 7 and the change of the pressure sensor 9 during the process, that is, the change of the light receiving area of the photosensitive plate 7 and the change of the pressure sensor 9, which can reflect the complex lap weld profile shape. Step three: find the end point: when the wire feeder is separated from the weld, the industrial computer controls the motion mechanism to drive the wire feeder to step in the direction perpendicular to the weld, if the step counter of the industrial computer reaches the preset threshold, and the pressure sensor still shows zero, it can be judged that the weld has reached the end point; step four: welding preparation: after determining the end point Q, the industrial computer 16 controls the motion mechanism 13 to drive the wire feeder 23 to return to the starting point P (profile recognition starting point) according to the steps of withdrawing along the direction perpendicular to the welding direction, retreating along the welding direction, and feeding along the direction perpendicular to the welding direction, further the motion mechanism 13 drives the wire feeder 23 to retreat d h and rise h, reach the welding starting point P1 (welding starting point), here d h and h are artificially set in advance, h is negatively related to the height of the lap weld, d h is positively related to the height of the lap weld; step five: welding process, after the industrial computer 16 controls the wire feeder 11 to feed the welding wire 1 into the weld at a constant speed, the industrial computer 16 controls the motion mechanism 13 to drive the wire feeder 23 to step along the weld and start welding, during this process, the industrial computer 16 controls the wire feeder 11 to constantly adjust the wire feeding speed v according to the change of the light receiving area of the photosensitive plate 7 and the change of the pressure sensor 9, so as to keep the relative distance between the welding wire 1 and the weld unchanged, where v is positively related to ΔS, the industrial computer controls the motion mechanism to drive the wire feeder to step or retreat in the direction perpendicular to the welding according to the step record of the step counter, at the same time, the industrial computer 16 constantly adjusts the distance s between the welding heat source 15 and the wire feeder 23 according to the change of the light receiving area of the photosensitive plate 7 and the change of the pressure sensor 9, so as to keep the welding heat source 15 always above the weld, so as to achieve the effect of weld tracking, where s is positively related to ΔS.

[0043] After the profile recognition in step two, if the pressure sensor 9 reaches the preset maximum value or the preset minimum value during the process of the motion mechanism 13 stepping along the welding direction, the following two steps are respectively taken:

[0044] If the pressure sensor 9 shows a value not less than the preset maximum value: the movement mechanism 13 drives the wire feeder 23 to retreat in the direction perpendicular to the welding, and the step counter value is added by 1 every time the wire feeder 23 retreats, when the pressure sensor 9 shows a value reaching the preset threshold F0, the wire feeder 23 stops retreating and the retreat times are recorded to the industrial computer 16, returns to the contour identification step and the step counter value is cleared; if the pressure sensor 9 shows a value not less than the preset minimum value: the movement mechanism 13 drives the wire feeder 23 to step in the direction perpendicular to the welding, and the step counter value is added by 1 every time the wire feeder 23 steps, when the pressure sensor 9 shows a value reaching the preset threshold F0, the wire feeder 23 stops stepping and the step times are recorded to the industrial computer 16, returns to the contour identification step and the step counter value is cleared.

[0045] The method adopted by the present application is divided into two parts, one part is the complex lap joint weld contour identification stage, and the other part is the complex lap joint weld welding stage.

[0046] The specific steps of the complex lap joint weld contour identification stage in the present application are as follows: first, fix the welding parts and adjust the posture of the wire feeder, adjust the wire feeder and the starting point of the lap joint weld to the same straight line perpendicular to the welding direction, and adjust the movement direction of the wire feeder to be parallel to the welding direction; further, the movement mechanism drives the wire feeder to step in the direction perpendicular to the welding, so that the wire feeder contacts the welding part; further, the movement mechanism drives the wire feeder to step in the direction parallel to the welding until the wire feeder is separated from the welding part. In this process, the first wire feeder body constantly enters and exits the second wire feeder body due to the change of the lap joint welding contour, and the light receiving area of the photosensitive plate changes; at the same time, the change of the light receiving area of the photosensitive plate is fed back to the wire feeder and the welding system through the industrial computer; in addition, the movement mechanism automatically adjusts the position of the wire feeder according to the pressure between the wire feeder and the lap joint weld, so that the relative distance between the wire feeder and the lap joint weld is kept within the set range, and the path experienced is recorded.

[0047] The principle of this stage is that when the wire feeder gun is fed to the lap joint and does not contact the weld, the spring connecting the first wire feeder gun body and the second wire feeder gun body is in a relaxed state, at which time the pressure sensor shows zero; when the wire feeder gun continues to feed to the lap joint and contacts the weld, the spring connecting the first wire feeder gun body and the second wire feeder gun body is gradually in a compressed state, at which time the pressure sensor gradually increases; continue to feed and when the pressure sensor reaches a preset threshold F0, stop feeding and record this point as the starting point P; the wire feeder gun is stepped along the welding direction, because the first wire feeder gun body is compressed by the weld contour, part of the wire feeder head retracted into the second wire feeder body blocks part of the strip-shaped light source in the second wire feeder body, so that the light receiving area of the photosensitive plate in the second wire feeder body changes, and the change AS of the light receiving area of the photosensitive plate and the change AF of the pressure sensor in this process are recorded; according to the change AS of the light receiving area of the photosensitive plate and the change AF of the pressure sensor in this process, the profile shape of the complex lap joint can be fed back to the industrial computer, and the termination point Q is recorded.

[0048] The specific steps of the welding stage of the complex lap joint are as follows: the motion mechanism drives the wire feeder gun to return to the position where the wire feeder gun contacts the lap joint in the last stage, and retreats a certain distance upward, reserving enough space for the welding wire; the industrial computer constructs the motion path of the motion mechanism according to the feedback signal; further, the industrial computer extracts the constructed path to control the motion mechanism to drive the wire feeder gun to step at a constant speed parallel to the welding direction and start welding; further, the industrial computer controls the variable wire feeder to constantly change the wire feeding speed according to the feedback signal, so as to ensure that the relative distance between the welding wire and the weld remains unchanged until the welding is completed.

[0049] The principle of this stage is that after obtaining the profile of the complex lap joint, the motion mechanism drives the wire feeder gun to return to the starting point P; further, the motion mechanism drives the wire feeder gun to retreat d h and rise h along the direction perpendicular to the welding direction, reaching the welding starting point P1; further, the wire feeder feeds the welding wire to the lap joint and then starts welding; further, the motion mechanism drives the wire feeder gun to step at a constant speed along the welding direction; in this process, the variable speed wire feeder constantly adjusts the wire feeding speed to compensate and maintain the relative distance between the weld and the welding wire, thereby achieving the effect of weld tracking.

[0050] Example 1

[0051] This invention discloses a method for real-time tracking of complex lap weld seams using a bypass wire feeding device. In the preparation stage of contour recognition, the threshold F0 of the pressure sensor is first set on the industrial control computer to half of the total range of the pressure sensor. For example, if the total range of the pressure sensor is 1000N, then F0 = 500N is set. The threshold n of the step counter is set to 5. In step one of the contour recognition stage, when the pressure sensor reaches the set threshold of 500N, it is determined that the wire feed gun is in contact with the weld seam, and the weld seam contour recognition begins. During the recognition process, the change in the light-receiving area of ​​the photosensitive plate inside the wire feed gun causes a change in the galvanometer reading. The contour of the lap weld seam can be determined based on the rate of change of the galvanometer reading. For example, if the rate of change of the galvanometer reading is constant, then the weld seam contour can be identified. The weld contour is a slanted straight weld. If the rate of change of the galvanometer reading first gradually increases and then gradually decreases, then the weld contour is a semi-circular weld. To prevent the weld contour from being too complex and affecting the movement of the motion mechanism or causing the motion mechanism to detach from the weld, a stepping and retraction mechanism perpendicular to the weld direction is added. This process is controlled by a threshold set by the industrial control computer and a step counter. For example, when the motion mechanism detaches from the weld, the industrial control computer controls the motion mechanism to step in a direction perpendicular to the welding. If the number of steps is less than the set threshold, the pressure sensor reading reaches the threshold of 500N again, then it is determined that the wire feeder is in contact with the weld again, and the identification task continues. If the number of steps reaches the set threshold, and the pressure sensor reading is still zero, then the last point where the pressure sensor showed a reading is determined to be the termination point of the weld. In the welding preparation stage, the retraction distance d is set according to the deflection angle of the wire feeder. h And the ascent height h, for example, when the deflection angle is 30°, then d is set. h =1.732cm, h=1cm; further based on the retreat distance d h The initial wire feeding length is set by the rising height h, and the setting d is used. h =1.732cm, h=1cm, then the initial wire feeding length is 2cm; during the welding process, the rate of change of the wire feeding speed of the variable speed wire feeder is positively correlated with the rate of change of the galvanometer reading during the contour recognition stage. For example, if the rate of change of the galvanometer reading is constant and is a, then the rate of change of the wire feeding speed of the variable speed wire feeder is also constant and is ka, where k is a positive proportionality factor; this process is maintained until the welding is completed, which solves the problem that existing lap weld seam tracking methods are difficult to perform high-precision tracking, and are prone to welding defects such as welding heat source or welding wire deviating from the part to be welded during welding, resulting in burnt welded parts or welding spatter.

[0052] Although the disclosed embodiments of the present application are as above, the content is only for the purpose of facilitating the understanding of the technical solutions of the present application, and is not used to limit the present application. Any person skilled in the art to which the present application belongs can make any modification and change in the form and details without departing from the disclosed core technical solutions of the present application, but the protection scope of the present application shall still be limited by the scope defined in the appended claims.

[0053] The above drawings and explanatory descriptions are only one specific embodiment of the present application, but the specific protection scope of the present application is not limited to the above explanatory description, any simple replacement or change within the technical idea disclosed by the present application and according to the technical solutions of the present application shall be within the protection scope of the present application.

Claims

1. A method of off-axis wire feeding for real-time tracking of complex lap welds, characterized by, The method is realized based on the device comprising a wire feeder gun (23), the wire feeder gun (23) comprising a wire feeder gun head (3), a first wire feeder gun body (4), a second wire feeder gun body (5), the wire feeder gun head (3) being connected with the front end of the first wire feeder gun body (4), the rear end of the first wire feeder gun body (4) being connected with the pressure sensor (9) arranged at the bottom of the second wire feeder gun body (5) through the elastic element (8), the second wire feeder gun body (5) being arranged with a photosensitive plate (7) and a light source, the photosensitive plate (7) being arranged opposite to the light source (6), the wire channel (2) in the wire feeder gun (23) being connected with the wire feeder (11) through the wire feeder pipeline (10), the bottom of the wire feeder gun (23) being connected with the movement mechanism (13), the photosensitive plate (7), the movement mechanism (13) and the pressure sensor (9) all being connected with the industrial computer (16), and the method comprises the following steps: Step one: finding the starting point: the movement mechanism (13) drives the wire feeder gun (23) to step along the direction perpendicular to the welding direction, when the elastic element (8) is compressed and shrunk, it indicates that the wire feeder gun (23) contacts the lap weld at this moment, the pressure sensor (9) gradually increases, when the pressure sensor (9) reaches the preset threshold, the wire feeder gun (23) is stopped and the point is recorded as the starting point and saved to the industrial computer (16); Step two: contour identification: the movement mechanism (13) drives the wire feeder gun (23) to step along the welding direction, the elastic element (8) freely stretches and shrinks according to the lap weld contour, drives the first wire feeder gun body (4) to enter and exit the second wire feeder gun body (5), the first wire feeder gun body (4) affects the light receiving area of the photosensitive plate (7) and the change of the pressure sensor (9), the photosensitive plate (7) transmits the signal to the industrial computer (16), and records the change amount of the light receiving area of the photosensitive plate (7) and the change amount of the pressure sensor (9) in the process, and reflects the complex lap weld contour shape; Step three: finding the termination point: when the wire feeder gun is separated from the weld, the industrial computer controls the movement mechanism to drive the wire feeder gun to step in the direction perpendicular to the weld, if the step counter of the industrial computer reaches the preset threshold and the pressure sensor still shows zero, it can be judged that the termination point of the weld has been reached; Step four: welding preparation: after the termination point is determined, the industrial computer (16) controls the movement mechanism (13) to drive the wire feeder gun (23) to return to the starting point according to the steps of withdrawing along the direction perpendicular to the welding direction, retreating along the welding direction, and feeding along the direction perpendicular to the welding direction, the movement mechanism (13) drives the wire feeder gun (23) to retreat along the direction perpendicular to the welding direction and rise to the welding starting point. Step five: After the work station (16) controls the wire feeder (11) to send the welding wire (1) into the weld at a constant speed, the work station (16) controls the motion mechanism (13) to drive the wire feeder (23) to step along the direction of the weld and start welding. The work station (16) controls the wire feeder (11) to constantly adjust the changing wire feeding speed according to the changing amount of the light receiving area of the previous light board (7) and the changing amount of the pressure sensor (9) reading, so as to keep the relative distance between the welding wire (1) and the weld unchanged. The work station controls the motion mechanism to drive the wire feeder to step or back up in the direction perpendicular to the welding according to the step record of the step counter. The work station (16) constantly adjusts the distance between the welding heat source (15) and the wire feeder (23) according to the changing amount of the light receiving area of the previous light board (7) and the changing amount of the pressure sensor (9) reading, so as to keep the welding heat source (15) always above the weld, achieving the effect of weld tracking.

2. The off-axis wire feeding method of real-time tracking complex lap welds of claim 1, wherein, After the contour recognition in step two, if the pressure sensor (9) reaches the preset maximum value or the preset minimum value during the process of the motion mechanism (13) stepping in the welding direction, the following two steps are taken respectively: If the pressure sensor (9) reading is not less than the preset maximum value: the motion mechanism (13) drives the wire feeder (23) to back up in the direction perpendicular to the welding. The step counter in the work station (16) adds 1 to the reading every time the wire feeder (23) backs up. When the pressure sensor (9) reading reaches the preset threshold value, stop the wire feeder (23) from backing up and record the number of back-ups to the work station (16), return to the contour recognition step and clear the step counter reading in the work station (16); If the pressure sensor (9) reading is not less than the preset minimum value: the motion mechanism (13) drives the wire feeder (23) to step in the direction perpendicular to the welding. The step counter in the work station (16) adds 1 to the reading every time the wire feeder (23) steps. When the pressure sensor (9) reading reaches the preset threshold value, stop the wire feeder (23) from feeding and record the number of steps to the work station (16), return to the contour recognition step and clear the step counter reading in the work station (16).

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