Ultrasonic Detection Method and Detection Device before Welding for Laser Welding Robot

Abstract

The present invention belongs to the technical field of ultrasonic detection, and specifically relates to an ultrasonic detection device and a detection method for a welding robot, including a fixing frame assembly; a C-shaped working section; a slider; a limiting block; a spring; the spring contacts with the ultrasonic probe, so that when the probe is pressed against the panel, there is a certain elastic compensation. By fixing the above components on the tooling of the welding head, moving the slider, making the laser on the welding head pass through the light-transmitting small holes on the light-blocking cover and shine on the photoresistor, and then moving and locking the limiting block to press the probe against the panel, the first and last positions of the core in the panel can be judged, replacing manual dotting and line drawing, and whether there is a gap can also be judged. When the first and last points are completed, moving once according to the positions of the first and last points in the operation program can also judge whether the core is bent. It can replace complex manual operations and greatly improve the welding efficiency and accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic testing, and specifically relates to an ultrasonic testing method and device for laser welding robots before welding. Background Art

[0002] Currently, for welding sandwich structures, manual scribing and pressing are used first, and then a laser welding robot is used for welding operations. This method has the following problems:

[0003] 1. Manual scribing operation is prone to human error in judgment, resulting in easy omission of welding between the panel and the core of the sandwich structure; 2. It is impossible to detect whether there is a gap between the panel and the core, resulting in virtual welding between the panel and the core; these problems cannot guarantee the strength requirements of the sandwich structure. Ultrasonic flaw detection technology can perform all-round flaw detection on surface cracks, embedded cracks, internal defects, etc. For this design, by using ultrasonic flaw detection technology, the relationship between the core and the panel can be judged through the waveform returned by the ultrasonic wave, and the position of the core and the gap between the core and the panel can be accurately judged by the distance between waves. For traditional ultrasonic probe flaw detection, manual operation is required. For welding the panel and the core, the probe needs to be moved back and forth during detection, which is relatively troublesome to operate and may often result in mistakes in actual operation, which may affect the welding position and thus the quality of the sandwich structure. Summary of the Invention

[0004] The purpose of the present invention is to provide an ultrasonic detection device for laser welding robots before welding to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] An ultrasonic detection device for laser welding robots before welding, including a fixed frame assembly. The fixed frame assembly includes an upper fixed frame fixed end and an upper fixed frame extension end. The upper fixed frame fixed end and the welding head tooling are fixed together by bolts. The upper fixed frame extension end is provided with a stepped hole for placing a hexagonal bolt. Symmetric U-shaped through grooves are opened on both sides of the lower bracket. The upper fixed frame extension end and the lower bracket are also fixed together by bolts;

[0007] There is a C-shaped working end at the lower end of the lower bracket. A slider is arranged on the C-shaped working end. Symmetric circular through holes are opened at the end of the C-shaped working end. Bolts are inserted into the circular through holes and tightened to clamp the slider so that it no longer moves. Symmetric protruding ends are arranged on the upper surface of the slider. The slider is restricted by the symmetric protruding ends to move back and forth within the C-shaped working end. A limit block is arranged on the C-shaped working end and is locked by an internal hexagonal bolt on it;

[0008] A circular hole is opened in the center of the slider. The ultrasonic probe is concentric with the circular hole opened in the center of the slider, and the ultrasonic probe moves up and down with the circular hole. A spring is arranged between the ultrasonic probe and the slider. The upper and lower ends of the spring are respectively abutted against the ultrasonic probe and the slider, and are compressed when the ultrasonic probe moves up and down. A photoresistor is connected to the ultrasonic probe, and a light-blocking cover is covered on the photoresistor. The light-blocking cover is fixed to the slider, and a light-transmitting small hole is opened at the center of the top end of the light-blocking cover;

[0009] The detection steps of the detection device are as follows: First, place the panel and the core to be welded on the bottom tooling at the bottom. The fixed end of the upper fixing frame is fixed to the welding head tooling by bolts. Adjust the positions of the U-shaped through groove and the bolts so that the lower bracket is in a suitable position. Then, by moving the position of the slider, the laser emitted by the welding torch passes through the light-transmitting small hole opened at the center of the top end of the light-blocking cover and irradiates on the photoresistor. After measuring the change in the resistance value of the photoresistor, it can be known that the ultrasonic probe and the welding torch are centrosymmetric at this time. The position where the center of the ultrasonic probe is close to the panel is the position where the welding torch will weld subsequently. Then, tighten the bolts on the circular through hole opened at the end of the C-shaped working end, and tighten the inner hexagon bolts to fix the limiting block. Then, lower the welding torch to keep the defocus amount. At this time, the ultrasonic probe is close to the panel, and the spring is also compressed, giving the ultrasonic probe flexible compensation. Then, operate the program to move the position of the probe, and it can be simply judged through the waveform the position of the core under the panel to complete the operation of the dotted line. At the same time, by moving the probe according to the start and end points, it can also be judged whether the core is bent. Through the waveform generated by the wave receiver, judge the deviation information of the position and condition of the core. Then, move the slider away and adjust the position by controlling the robot arm to perform accurate welding.

[0010] The extension end of the upper fixing frame and the lower bracket are fixed on both sides of the lower bracket by changing the bolts at the positions of the symmetric U-shaped through grooves, so that the fixing mechanism is adapted to the welding head tooling mechanisms of different heights.

[0011] Symmetric protruding ends are arranged on the upper end surface of the slider to limit the slider so that it is slidably connected along the outer surface of the C-shaped working end.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] 1. Before the first workpiece is welded, through the grooves opened on the fixing frame assembly and the symmetric U-shaped through grooves opened on both sides of the lower bracket, it can be moved and locked with a lock nut to adapt to different welding toolings.

[0014] 2. When the laser spot emitted by the welding head irradiates on the photoresistor through the light-transmitting small holes on the light-blocking cover and the resistance value of the photoresistor changes, the laser welding head and the ultrasonic probe are centrosymmetric at this time. Then, symmetric circular openings are made at the end of the C-shaped working end, and bolts are inserted and tightened. Adjust the position of the robot to reach the position away from the focus so that the ultrasonic probe is closely attached to the panel when compressing the spring. Moving the probe through the program can replace the cumbersome manual movement.

[0015] 3. Due to the existence of the spring, when the probe contacts the panel, the probe can still be closely attached while moving with the panel, providing a certain flexible compensation.

[0016] 4. The position of the core and the panel can be simply viewed through the results detected by the ultrasonic probe. The start and end point positions can be detected, and then the operation of dot-dash line marking can be easily completed, solving the errors that may be caused by manual dot-dash line marking.

[0017] 5. Whether there is a gap between the core and the panel can be observed through the results detected by the ultrasonic probe.

[0018] 6. By moving the probe according to the start and end point positions, the condition of the core can be judged through the results detected by the ultrasonic probe to determine whether it is bent.

[0019] 7. Through the waveform generated by the wave receiver, the deviation information of the position and condition of the core is judged. Then, the position of the robot arm is adjusted through the control program to adjust the accurate welding of the welding head. The deviation of the workpiece position in the welding work is corrected, reducing the errors that may be generated by manual dot-dash line marking.

[0020] 8. After the welding is completed, due to the existence of the limit block, there is no need to repeatedly calibrate the position of the slider, improving the welding accuracy and work efficiency and shortening the working cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present invention, form a part of this application, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 is a schematic structural diagram of the present invention;

[0023] Figure 2 is a schematic structural diagram of the present invention during welding;

[0024] Figure 3 is a schematic overall diagram of the clamping detection structure of the present invention;

[0025] Figure 4 is a schematic structural diagram of the up and down extension frame of the present invention;

[0026] Figure 5 Schematic structural diagram when the limit block is working;

[0027] Figure 6 Enlarged schematic structural diagram of the ultrasonic probe;

[0028] Figure 7 Schematic structural diagram of the laser alignment of the present invention. Specific embodiments

[0029] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. In the following paragraphs, the present invention will be described more specifically by way of example with reference to the accompanying drawings. The advantages and features of the present invention will be clearer according to the following description and the claims. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0030] Please refer to Figures 1 to 7 , a pre-welding ultrasonic detection device for a laser welding robot, characterized in that: it includes a fixed frame assembly 2, which includes an upper fixed frame fixed end 3 and an upper fixed frame extension end 4. The upper fixed frame fixed end 3 and the welding head tooling 1 are fixed together by bolts, and the upper fixed frame extension end 4 is provided with a stepped hole 5 for placing a hexagonal bolt. Symmetric U-shaped through grooves 10 are opened on both sides of the lower bracket 6, and the upper fixed frame extension end 4 and the lower bracket 6 are also fixed together by bolts.

[0031] There is a C-shaped working end 11 at the lower end of the lower bracket 6. A slider 8 is arranged on the C-shaped working end 11. Symmetric circular through holes 12 are opened at the end of the C-shaped working end 11. When a bolt is inserted through the circular through holes 12, it can clamp the slider 8 to make it no longer move. Symmetric protruding ends 13 are arranged on the upper surface of the slider. The slider 8 is restricted by the symmetric protruding ends 13 to move back and forth within the C-shaped working end 11, and a limit block 7 is arranged on the C-shaped working end 11. The limit block is locked by an internal hexagonal bolt 14 on it.

[0032] A circular hole 22 is opened at the center of the slider 8. The ultrasonic probe 9 is concentric with the circular hole 22 opened at the center of the slider 8, and the ultrasonic probe 9 can move up and down along with the circular hole 22. A spring 21 is arranged between the ultrasonic probe 9 and the slider 8, and its upper and lower ends are respectively abutted against the ultrasonic probe 9 and the slider 8, and can move up and down along with the ultrasonic probe 9. A photoresistor 15 is connected to the ultrasonic probe 9, and a light-blocking cover 16 is covered on the photoresistor 15. The light-blocking cover 16 is fixed to the slider 8, and a light-transmitting small hole 17 is opened at the center of the top end of the light-blocking cover 16.

[0033] When the laser spot emitted by the welding torch passes through the light-transmitting small hole 17 at the center of the top end of the light-blocking cover 16 and irradiates the photosensitive resistor 15, and a change in the resistance value of the photosensitive resistor is detected, it indicates that the position where the center of the ultrasonic probe 9 is closely attached to the panel is the position where the subsequent welding torch will weld. After the position of the slider 8 is determined, it can be inserted and locked with the bolt on the circular through hole 12 opened at the end of the C-shaped working end 11, and then the position can be detected. A limit block 7 is provided at the lower part of the C-shaped working end 11. The advantage of this is that when the position of the slider 8 is determined, the limit block 7 is locked. When welding, the slider 8 is moved away. After welding is completed, there is no need to re-align the point. Just move the slider 8 to the position where it is closely attached to the limit block 7. At this time, the center position of the ultrasonic probe 9 is the position to be welded, which greatly saves time.

[0034] Working principle: First, place the panel and the core to be welded on the bottom tooling at the bottom. The fixed end 3 of the upper fixing frame is fixed to the welding head tooling 1 with bolts, and the positions of the U-shaped through groove 10 and the bolts are adjusted so that the lower bracket 6 is in a suitable position. Then, by moving the position of the slider 8, the laser emitted by the welding torch passes through a light-transmitting small hole 17 opened at the center of the top end of the light-blocking cover 16 and irradiates on the photosensitive resistor 15. After measuring the change in the resistance value of the photosensitive resistor 15, it can be known that at this time, the ultrasonic probe 9 and the welding torch are centrosymmetric, and the position where the center of the ultrasonic probe 9 is closely attached to the panel is the position where the subsequent welding torch will weld. Then, tighten the bolt on the circular through hole 12 opened at the end of the C-shaped working end 11, and tighten the hexagon socket head cap screw 14 to fix the limit block 7. Then lower the welding torch to maintain the defocus amount. At this time, the ultrasonic probe 9 is closely attached to the panel, and the spring 21 is also compressed, giving a certain flexible compensation to the ultrasonic probe 9. Then, the operation program moves the position of the probe 9, and it can be simply judged through the waveform that the position of the core under the panel can easily complete the operation of aligning and scribing. At the same time, by moving the probe according to the first and last points, it can also be judged whether the core is bent. Through the waveform generated by the wave receiver, the deviation information of the position and condition of the core is judged, and then the slider is moved away and the position is adjusted by controlling the robot arm to accurately weld.

[0035] Correcting the deviation of the workpiece position in the welding work reduces the possible errors caused by manual aligning and scribing, improves the accuracy of the weld seam and the working efficiency. And the existence of the limit block means that when re-detecting after welding, as long as the slider is moved to be closely attached to the limit block, there is no need to re-align, shortening the working cycle.

Claims

1. An ultrasonic detection device before welding for a laser welding robot, characterized in that, it includes a fixing frame assembly (2), and the fixing frame assembly (2) includes an upper fixing frame fixed end (3) and an upper fixing frame extending end (4). The upper fixing frame fixed end (3) and the welding head tooling (1) are fixed together by bolts. A stepped hole (5) for placing hexagon bolts is opened in the upper fixing frame extending end (4). Symmetric U-shaped through grooves (10) are opened on both sides of the lower bracket (6). The upper fixing frame extending end (4) and the lower bracket (6) are also fixed together by bolts; there is a C-shaped working end (11) at the lower end of the lower bracket (6). A slider (8) is arranged on the upper surface of the C-shaped working end (11). Symmetric circular through holes (12) are opened at the end of the C-shaped working end (11). Bolts are inserted into the circular through holes (12) to clamp the slider (8) when tightened so that it no longer moves. Symmetric protruding ends (13) are arranged on the upper surface of the slider. The slider (8) moves back and forth in the C-shaped working end (11) due to the limitation of the symmetric protruding ends (13). A limit block (7) is arranged on the C-shaped working end (11), and the limit block (7) is locked by an inner hexagon bolt (14) on its upper surface; a circular hole (22) is opened in the center of the slider (8). The ultrasonic probe (9) is concentric with the circular hole (22) opened in the center of the slider (8), and the ultrasonic probe (9) moves up and down along with the circular hole (22). A spring (21) is arranged between the ultrasonic probe (9) and the slider (8), and its upper and lower ends are respectively abutted against the ultrasonic probe (9) and the slider (8), and is compressed when the ultrasonic probe (9) moves up and down. A photoresistor (15) is connected to the ultrasonic probe (9), and a light-blocking cover (16) is covered on the photoresistor (15). The light-blocking cover (16) is fixed to the slider (8), and a light-transmitting small hole (17) is opened at the center of the top end of the light-blocking cover (16); The detection steps of the detection device are as follows: First, place the panel and the core to be welded on the bottom fixture at the bottom. The fixed end (3) of the upper fixing frame is fixed to the welding head fixture (1) by bolts. Adjust the positions of the U-shaped through groove (10) and the bolts so that the lower bracket (6) is in a suitable position. Then, by moving the position of the slider (8), the laser emitted by the welding torch passes through a light-transmitting small hole (17) opened at the center of the top of the light-blocking cover (16) and irradiates on the photoresistor (15). After measuring the change in the resistance value of the photoresistor (15), it can be known that at this time, the ultrasonic probe (9) and the welding torch are centrosymmetric. The position where the center of the ultrasonic probe (9) is close to the panel is the position where the welding torch will weld subsequently. Then, tighten the bolts on the circular through hole (12) at the end of the C-shaped working end (11), and tighten the socket head cap screw (14) to fix the limit block (7). Then, lower the welding torch to maintain a defocus amount. At this time, the ultrasonic probe (9) is close to the panel, and the spring is also compressed, providing a flexible compensation to the ultrasonic probe (9). Then, operate the program to move the position of the ultrasonic probe (9), and it is possible to simply judge the position of the core under the panel through the waveform to complete the operation of the dotted line. At the same time, moving the probe according to the start and end points can also judge whether the core is bent. Through the waveform generated by the wave receiver, judge the deviation information of the position and condition of the core. Then, move the slider away and adjust the position by controlling the robotic arm to perform accurate welding.

2. The device according to claim 1, characterized in that: The extended end (4) of the upper fixing frame and the lower bracket (6) are fixed to both sides of the lower bracket (6) with symmetric U-shaped through grooves (10) by changing the bolts, so that the fixing mechanism is adapted to the welding head fixture (1) mechanism of different heights.

3. The device according to claim 1, characterized in that: Symmetric protrusion ends (13) are provided on the upper end surface of the slider (8) to limit the slider (8) so that it is slidably connected along the outer surface of the C-shaped working end (11).

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