A laser double-beam welding control system

Abstract

The present invention provides a laser dual-beam welding control system, which includes a controller and two synchronized robots connected to the controller, two laser welding heads and a welding beam, wherein the welding beam includes a first beam and a second beam that are laterally connected through a guide rail unit, the first beam is connected to the execution end of the first robot through a first flange, the second beam is connected to the execution end of the second robot through a second flange, the connecting end of the second beam and the second flange is equipped with a joint bearing, a displacement sensor is installed between the joint bearing and the second flange, and is used to detect the motion error between the second beam and the first beam through the deflection of the joint bearing, the displacement sensor is connected to the controller, and the two laser welding heads are both installed on the first beam.

Description

Technical Field

[0001] The invention relates to the field of automatic control technology, in particular to a laser double-beam welding control system. Background Art

[0002] The ribbed wall panel structure is a common skin wall panel structure in aviation and aerospace structural parts. It has a wide range of applications in aviation and aerospace. At present, the advanced ribbed wall panel structure manufacturing at home and abroad is manufactured using laser double-beam welding technology. The use of double-beam welding of this T-shaped structure can effectively prevent damage to the aerodynamic surface of the skin (bottom plate). The outer surface of the skin is smooth with a convex or concave surface not exceeding 0.1mm. The electromagnetic radiation is reduced by more than 50% compared with the riveted structure, which can achieve lightweight, high-strength and stealth wall panel manufacturing.

[0003] Double-beam welding siding is an advanced method for manufacturing ribbed siding developed in recent years. When laser welding this type of structure, two laser beams can be used to weld from both sides of the ribs. Using a double laser beam to weld from both sides of the T-joint to form a fillet weld is beneficial to the fusion of the ribs and the skin, and there is no damage to the back of the skin. It is generally believed that the use of a double-beam welding process can make both sides of the T-joint heated evenly, which is beneficial to controlling deformation. In addition, due to the simultaneous welding of two laser beams, the heat input can be reduced under the interaction of the molten pool to produce a 1+1>2 effect.

[0004] The existing laser dual-beam welding control system mainly adopts the PLC+robot controller mode. The motion control during the welding process is controlled by the robot controller. The laser dual-beam welding equipment usually uses two robots to exchange data through the industrial bus and implement synchronous control. However, this method cannot solve the problem of poor interpolation accuracy caused by the step-by-step amplification of errors caused by the robot series mechanical structure. It is easy to cause jitter during laser welding (speed>10m / min) and other problems. Ultimately, it is impossible to achieve the technical requirements of strict synchronization of the two laser beams during dual-beam laser welding. This causes large deformation of parts during welding. At the same time, since the synchronization of the two robots under high-speed welding must be considered during programming, it brings great difficulties to the preparation, verification and adjustment of the welding program, resulting in a long preparation time for welding and the high efficiency of laser welding cannot be brought into play. Summary of the invention

[0005] (1) Technical issues to be solved

[0006] The embodiment of the present invention provides a laser dual-beam welding control system, which solves the technical problem of low welding efficiency caused by relative offset of two robots during existing laser dual-beam welding.

[0007] (2) Technical solution

[0008] An embodiment of the present invention proposes a laser dual-beam welding control system, which includes a controller and two synchronized robots connected to the controller, two laser welding heads and a welding beam, wherein the welding beam includes a first beam and a second beam laterally connected through a guide rail unit, the first beam is connected to the execution end of the first robot through a first flange, the second beam is connected to the execution end of the second robot through a second flange, the connecting end of the second beam and the second flange is equipped with a joint bearing, a displacement sensor is installed between the joint bearing and the second flange, and is used to detect the motion error between the second beam and the first beam through the deflection of the joint bearing, the displacement sensor is connected to the controller, and the two laser welding heads are both installed on the first beam.

[0009] Furthermore, the guide rail unit includes three guide rail groups arranged laterally, so that the first crossbeam and the second crossbeam can make relative linear displacement along the guide rail groups.

[0010] Furthermore, a grating ruler is provided at the transverse connection portion between the first crossbeam and the second crossbeam for measuring the relative displacement value therebetween.

[0011] Furthermore, limit switches and corresponding limit blocks are installed at both ends of the guide rail group. When the first beam and the second beam are relatively displaced and the limit switch hits the limit block, the controller is triggered to immediately stop the movement of the two robots and the laser of the laser welding head from generating laser.

[0012] Furthermore, a cylinder is installed on the first beam at a side close to the first flange, and the cylinder output shaft is connected to a first mounting plate along the axis of the beam, and the first mounting plate is movably arranged on the first beam through a guide rail.

[0013] Furthermore, the cylinder is provided with a switch for detecting whether the laser welding head installed on the first mounting plate is in place. After it is in place, the controller starts the laser of the laser welding head to generate laser.

[0014] Furthermore, three displacement sensors are evenly installed along the circumference between the spherical bearing and the second flange.

[0015] (3) Beneficial effects

[0016] In summary, a laser dual-beam welding control system of the present invention establishes a new laser dual-beam welding control model, which calculates the relative offset adjustment of the two robots by adopting the relative positions and rotation angles of the welding beams under constraints in real time, and sends adjustment instructions to the robots through the real-time industrial controller bus to ensure the precise synchronization of the two laser beams during the dual-beam laser welding process. At the same time, it can greatly simplify the difficulty of compiling, verifying and adjusting the welding program, thereby improving the processing efficiency of laser welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic diagram of double beam welding.

[0019] Figure 2 It is a schematic diagram of an equipment application scenario of a laser dual-beam welding system using an embodiment of the present invention.

[0020] Figure 3 It is a schematic diagram of a welding beam structure in a laser dual-beam welding control system according to an embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram of the installation of a displacement sensor in a laser dual-beam welding control system according to an embodiment of the present invention.

[0022] Figure 5 Schematic diagram of a control system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments, and covers any modification, replacement and improvement of parts, components and connection modes without departing from the spirit of the present invention.

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] The embodiment of the present invention provides a laser dual-beam welding control system, see Figure 2-Figure 5As shown, the control system at least includes a controller and two synchronized robots connected to the controller, two laser welding heads and a welding beam, the welding beam includes a first beam (beam 1) and a second beam (beam 2) which are laterally connected through a guide rail unit (guide rail 3, guide rail 4, guide rail 5), the first beam (beam 1) is connected to the execution end of the first robot through a first flange (flange 1), the second beam (beam 2) is connected to the execution end of the second robot through a second flange (flange 2), the connecting end of the second beam (beam 2) and the second flange (flange 2) is equipped with a joint bearing, a displacement sensor is installed between the joint bearing and the second flange (flange 2), and is used to detect the motion error between the second beam (beam 2) and the first beam (beam 1) through the deflection of the joint bearing, the displacement sensor is connected to the controller, and the two laser welding heads are both installed on the first beam (beam 1).

[0026] Specifically, the guide rail unit includes three guide rail groups arranged transversely, so that the first beam and the second beam can make relative linear displacement along the guide rail group. A grating ruler is arranged at the transverse connection part of the first beam and the second beam, which is used to measure the relative displacement value between the two. A limit switch and a corresponding limit stopper are installed at both ends of the guide rail group. When the first beam and the second beam are relatively displaced and the limit switch hits the limit stopper, the controller is triggered to immediately stop the movement of the two robots and the laser of the laser welding head from generating laser. The two laser welding heads are respectively installed on the first beam through corresponding mounting plates. A cylinder is installed on the side of the first beam close to the first flange, and the cylinder output shaft is connected to the first mounting plate along the axis of the beam. The first mounting plate is movably arranged on the first beam through the guide rail. A switch is installed on the cylinder to detect whether the laser welding head installed on the first mounting plate is in place. After it is in place, the controller starts the laser of the laser welding head to generate laser. Three displacement sensors are evenly installed along the circumference between the joint bearing and the second flange.

[0027] See also Figure 3 As shown, flange 1 and flange 2 are connected to the execution end of the corresponding robot through robot 1 flange and robot 2 flange respectively.

[0028] During dual-beam laser welding, the two robots move synchronously along the direction of the weld, driving the welding beam to move together. Due to the motion error between the two robots, beams 1 and 2 will be affected by force and cannot maintain their initial state. Slippage will occur between them, and beam 2 will deflect in the joint bearing. However, since the two laser welding heads are fixed to beam 1 through mounting plates 1 and 2, the synchronization of the welding heads will not be affected.

[0029] In order to ensure the accuracy and stability of welding, the control system needs to compensate for the motion error between the two robots in real time.

[0030] At any moment in the welding process, the motion error between the two robots is

[0031]

[0032] in, and are the velocity vectors of robot 1 and robot 2, Model:

[0033] ε R =P*V M *θ

[0034] Where P is the grating scale reading, V M is the current set welding speed, θ is a constant coefficient. After experimental verification, θ is taken as 0.67 here. The direction is determined by the position of the grating ruler reading relative to the initial origin. Because the two laser welding heads are fixed on beam 1 through mounting plates 1 and 2, and beam 1 is connected to robot 1, in order to reduce the impact on welding, the movement of robot 2 is compensated.

[0035] ε R It is the robot's motion and speed, which cannot be used directly for motion error compensation. We need to know its projection ε in the X, Y, and Z axes of the rectangular coordinate system. RX , ε RY , ε RZ .

[0036] When beams 1 and 2 move in a straight line, beam 2 will produce a deflection on the joint bearing, causing the readings of displacement sensors 1, 2, and 3 to change. A plane is defined by three points, and the changes produced by these three sensors can be used to calculate a spatial angle. Using this spatial angle and ε R We can calculate ε RX , ε RY , ε RZ .

[0037] ε RX , ε RY , ε RZ Write into the controller of robot 2 to complete error compensation.

[0038] Limit switches are installed at both ends of guide rails 3, 4, and 5. When they are hit, the control system considers that the error of the two robots has exceeded the limit and may cause danger, and will immediately stop the movement of the robots and the generation of lasers by the lasers.

[0039] A magnetic switch is installed on the cylinder to detect whether the welding head 1 is in place. Only when the welding head 1 is in place, the control system allows the welding work to start.

[0040] In the specific implementation, see Figure 5 As shown, the components used in the control system of the present invention are required to be as follows:

[0041] PLC: Beckhoff CP6542-0000-0060 supports TwinCAT 3 as EtherCAT master;

[0042] Robot controller: KUKA KRC4 controller as EtherCAT slave, two units;

[0043] Displacement sensor: Panasonic HG-S1032;

[0044] Linear ruler: LS487 from HEIDENHAIN

[0045] I / O interface module: Beckhoff BK1120, connected to EtherCAT bus;

[0046] I / O analog input module: Beckhoff KL3012, receiving displacement sensor data;

[0047] I / O encoder interface terminal module: Beckhoff EL5021, receiving grating ruler data;

[0048] The bus is connected to the IPG fiber laser and the KUKA robot. The control program obtains the real-time movement speed of the robot's six axes by accessing the robot's internal registers, and calculates the robot's real-time movement speed.

[0049] In summary, the laser dual-beam welding control system of the present application can obtain the real-time movement speed of the welding robot and adjust the robot's movement trajectory in real time according to the data obtained by the displacement sensor. It solves the problem of robot precision measurement and compensation in the laser dual-beam welding process, ensures dual-beam synchronous welding, and improves production efficiency.

[0050] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.

[0051] The above are only embodiments of the present application and are not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A laser dual-beam welding control system, characterized in that: It comprises a controller and two synchronous robots connected to the controller, two laser welding heads and a welding beam, wherein the welding beam comprises a first beam and a second beam which are connected transversely through a guide rail unit, the first beam is connected to the execution end of the first robot through a first flange, the second beam is connected to the execution end of the second robot through a second flange, a joint bearing is installed at the connection end between the second beam and the second flange, a displacement sensor is installed between the joint bearing and the second flange, and is used to detect the motion error between the second beam and the first beam through the deflection of the joint bearing, the displacement sensor is connected to the controller, and the two laser welding heads are both installed on the first beam; a grating ruler is arranged at the transverse connection part between the first beam and the second beam, and is used to measure the relative displacement value between the two; three displacement sensors are evenly installed along the circumference between the joint bearing and the second flange; The changes generated by the three displacement sensors can be used to calculate a spatial angle, and this spatial angle and ε R We can calculate ε RX , ε RY , ε RZ , and ε RX , ε RY , ε RZ Write into the robot controller to complete the error compensation; where ε R is the robot's motion and speed, ε R =P*V M *θ, P is the grating scale reading, V M is the current set welding speed, θ is a constant coefficient, ε RX , ε RY , ε RZ They are ε R Projection in the directions of X, Y and Z axes on the rectangular coordinate system; The guide rail unit includes three guide rail groups arranged laterally, so that the first crossbeam and the second crossbeam can perform relative linear displacement along the guide rail groups.

2. The laser dual-beam welding control system according to claim 1, characterized in that: Limit switches and corresponding limit blocks are installed at both ends of the guide rail group. When the first beam and the second beam are relatively displaced and the limit switch hits the limit block, the controller is triggered to immediately stop the movement of the two robots and the laser of the laser welding head from generating laser light.

3. The laser dual-beam welding control system according to claim 1, characterized in that: The two laser welding heads are respectively mounted on the first crossbeam through corresponding mounting plates.

4. The laser dual-beam welding control system according to claim 3, characterized in that: A cylinder is installed on the first beam at one side close to the first flange, and the cylinder output shaft is connected to the first mounting plate along the axis of the beam. The first mounting plate is movably arranged on the first beam through a guide rail.

5. The laser dual-beam welding control system according to claim 4, characterized in that: The cylinder is provided with a switch for detecting whether the laser welding head installed on the first mounting plate is in place. After the laser welding head is in place, the controller starts the laser of the laser welding head to generate laser.

Images