An automated welding station and welding method for assembling a stator of an air-cooled generator

Abstract

The present application belongs to the technical field of generator welding manufacturing, and specifically discloses an automatic welding workstation for assembling a stator of an air-cooled generator and an automatic welding method for assembling a stator of an air-cooled generator. The automatic welding workstation comprises a six-axis industrial robot, an XYZ three-dimensional motion mechanism, a welding power source, a wire feeding mechanism, a welding torch, a gun cleaning and wire cutting device, a workstation control system, offline programming software, a safety protection device and the like. The present application realizes automatic welding of the whole process of assembling the stator of the air-cooled generator, including welding of the iron core clamping ring and the ear plate, welding of the ear plate and the back-shaped plate, and welding of the back-shaped plate and the spring plate of the machine base. By adopting a pulse welding power source and matching appropriate welding process parameters, a low-splashing welding effect is realized, which helps to improve the overall cleanliness of the generator stator. By adopting the offline programming software and matching the contact positioning of the welding torch, full automation of the welding process is realized, without the need for manual intervention, thereby reducing the cost of human resources.

Description

Technical Field

[0001] This invention relates to the field of generator welding manufacturing technology, and in particular to an automated welding workstation for assembling the stator of an air-cooled generator and an automated welding method for assembling the stator of an air-cooled generator. Background Technology

[0002] The stator assembly of an air-cooled generator refers to the assembly of the stator frame and the stator core, which is often achieved through welding. One commonly used welding structure is the "ear plate + U-shaped plate" structure, such as... Figure 1 As shown, the process involves first welding ear plates to the clamping ring of the stator core, and then connecting the ear plates to the spring plates on the frame via a U-shaped plate fitted onto the ear plates, thus forming the connection between the stator core and the stator frame. The welding joints include three types: welding the core clamping ring to the ear plate, welding the ear plate to the U-shaped plate, and welding the U-shaped plate to the frame spring plate.

[0003] To ensure sufficient connection strength between the stator frame and the stator core, the weld dimensions in stator assembly are generally designed to be relatively large. Traditional welding methods include manual shielded metal arc welding (SMAW) or manual CO2 gas shielded welding. These methods have the following problems: 1. Manual welding is unstable. Both SMAW and CO2 gas shielded welding are prone to producing significant welding spatter. To ensure the stator core is not damaged, complex core protection work is required before welding, resulting in low production efficiency; 2. Air-cooled generators have high production volumes and fast turnover rates, requiring a large number of welders. However, welders are currently in short supply in the labor market, causing difficulties for enterprises in recruiting workers; 3. Manual welding involves high labor intensity and harsh working environments, which is detrimental to the welders' physical and mental health and can easily lead to welding quality defects due to fatigue. Therefore, it is necessary to research automated welding technology for stator assembly welding of air-cooled generators to solve these problems encountered in production. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems existing in the background art. To this end, an automated welding workstation for assembling air-cooled generator stators and an automated welding method for assembling air-cooled generator stators are provided, which result in high production efficiency, stable welding process and weld quality, automatic identification of weld position and adjustment of welding trajectory, and no need for manual intervention during welding.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An automated welding method for assembling the stator of an air-cooled generator includes the following steps:

[0007] Step 1: Import the 3D model of the generator stator assembly welding workpiece into the offline programming software. The software automatically arranges the weld seams according to the input workpiece and weld seam size information. Based on the different welding sequence and welding position of each weld seam, the software selects single-pass welding parameters from the accumulated welding parameter library and automatically combines them to form the welding parameter group of the entire weld seam, thus forming a welding program for each generator model.

[0008] Step 2: Select the generator model in the host computer software interface, and the robot will automatically call the welding program for the corresponding generator model from the offline programming software;

[0009] Step 3: In the automated welding workstation, the robot automatically moves from a safe position to the welding area on the ground rail. First, it completes the welding of the core clamping ring and the ear plate. Before welding, the welding torch measures the deviation between the actual position and the theoretical position of the workpiece through contact positioning. The offline programming software automatically corrects the existing welding trajectory. After the correction is completed, the robot performs the welding operation.

[0010] Step 4: The robot then completes the welding of the spiral plate and the base spring plate. Before welding, the welding torch measures the deviation between the actual position and the theoretical position of the workpiece by contact positioning. The offline programming software automatically corrects the existing welding trajectory. After the correction is completed, the robot performs the welding operation.

[0011] Step 5: Finally, complete the welding of the ear plate and the U-shaped plate; before welding, the welding torch measures the deviation between the actual position and the theoretical position of the workpiece by contact positioning, and the offline programming software automatically corrects the existing welding trajectory; after the correction is completed, the robot performs the welding operation.

[0012] Step 6: After all welds are completed, the robot automatically returns to a safe position.

[0013] The following is a further defined technical solution for the welding method in this invention, which includes the following steps during the welding torch contact positioning process:

[0014] Establish a user coordinate system OXYZ on the 3D model workpiece, where the origin O and the three axes XYZ are set manually.

[0015] When the actual workpiece placement deviates from the theoretical position, the tip of the welding wire of the welding gun touches the workpiece surface from three mutually perpendicular directions. When they make contact, the open-circuit voltage of the welding power source drops to zero instantaneously.

[0016] When the robot detects a change in the no-load voltage, it stops moving and records its current position coordinates. It then calculates the user coordinate system O'X'Y'Z' of the actual workpiece. The positional relationship between the user coordinate systems OXYZ and O'X'Y'Z' can be calculated using the following formula:

[0017] [User coordinate system OXYZ] = [Transformation matrix] × [User coordinate system O'X'Y'Z'];

[0018] After obtaining the [transformation matrix], the [transformation matrix]' can be obtained through mathematical processing;

[0019] The coordinates of all label points on the multi-layer, multi-pass welding path are then calculated using the following formula, thereby obtaining all welding trajectories in the new user coordinate system and correcting the original welding trajectories:

[0020] [X′Y′Z′A′B′C′]=[Transformation Matrix]'×[XYZABC].

[0021] The following is a further technical solution for defining the welding method in this invention, wherein the welding procedure includes robot motion trajectory and welding process parameters.

[0022] An automated welding workstation for assembling air-cooled generator stators, used to implement the aforementioned welding method, includes an XYZ three-dimensional motion mechanism, on which a six-axis industrial robot is mounted, and on which a welding mechanism is mounted. The XYZ three-dimensional motion mechanism, the six-axis industrial robot, and the welding mechanism are all electrically connected to a workstation control system. The workstation control system is used to control the operation of the XYZ three-dimensional motion mechanism, the six-axis industrial robot, and the welding mechanism. The workstation control system includes offline programming software, which is used to generate welding programs for each generator model. Safety protection devices are installed on both sides of the workstation.

[0023] The following is a further defined technical solution for the welding workstation in this invention: the welding mechanism includes a welding torch, a wire feeding mechanism, and a torch cleaning and wire cutting device. The welding torch and the wire feeding mechanism cooperate with each other, and both the welding torch and the wire feeding mechanism cooperate with the torch cleaning and wire cutting device. The welding torch is electrically connected to a welding power source, and the welding power source is set as a pulse welding power source.

[0024] The following is a further defined technical solution for the welding workstation in this invention: the XYZ three-dimensional motion mechanism includes an X-axis motion mechanism, a Y-axis motion mechanism, and a Z-axis motion mechanism. The motion directions of the X-axis motion mechanism, the Y-axis motion mechanism, and the Z-axis motion mechanism are perpendicular to each other. The X-axis motion mechanism is a ground track, the Y-axis motion mechanism is a lifting track, the X-axis motion mechanism and the Y-axis motion mechanism are slidably coupled and their motion directions are perpendicular, and the Y-axis motion mechanism and the Z-axis motion mechanism are slidably coupled and their motion directions are perpendicular.

[0025] The following is a further technical solution for the welding workstation in this invention: two six-axis industrial robots are provided and are located on both sides of the generator stator frame. The two six-axis industrial robots weld simultaneously to avoid the relative positional displacement of the stator core and the frame that may be caused by welding on one side. The six-axis industrial robots are mounted on the Z-axis motion mechanism.

[0026] The following is a further defined technical solution for the welding workstation in this invention. The workstation control system includes a host computer, a PLC controller, a touch screen, and a main control cabinet. The touch screen is installed on the front panel of the main control cabinet, and the PLC controller is installed inside the main control cabinet.

[0027] Compared with the prior art, the present invention has the following technical effects:

[0028] 1. This invention improves the production efficiency of stator assembly welding for air-cooled generators by using robots to replace manual welding.

[0029] 2. This invention achieves a low-splash welding effect by using a pulse welding power source with appropriate welding process parameters, which helps to improve the overall cleanliness of the generator stator;

[0030] 3. This invention achieves full automation of the welding process by using offline programming software in conjunction with welding torch contact positioning, eliminating the need for manual intervention and reducing human resource costs.

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the weld position of the stator assembly of an air-cooled generator according to the present invention;

[0034] Figure 2 This is a schematic diagram of the overall front view structure of the welding workstation in this invention;

[0035] Figure 3 This is a side view of the overall structure of the welding workstation in this invention;

[0036] Figure 4 This is a top view of the overall structure of the welding workstation in this invention;

[0037] Figure 5This is a three-dimensional structural diagram of the welding workstation in this invention.

[0038] Reference numerals: 1. Clamping ring; 2. Ear plate; 3. Spring plate; 4. Recurve plate; 5. XYZ three-dimensional motion mechanism; 6. Six-axis industrial robot; 7. Workstation control system; 8. Safety protection device; 9. Welding torch; 10. Torch cleaner and wire cutter; 11. Welding power source. Detailed Implementation

[0039] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0040] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0041] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0042] This embodiment takes the stator assembly and welding of a 60MW air-cooled generator as an example:

[0043] like Figure 1-5 As shown, an automated welding method for assembling the stator of an air-cooled generator is provided, comprising the following steps:

[0044] Step 1: Import the 3D model of the 60MW air-cooled generator stator assembly welding workpiece into the offline programming software. The software automatically arranges the weld beads according to the input workpiece and weld size information. Based on the different welding sequence and welding position of each weld bead, the software selects appropriate single-pass welding parameters from the accumulated welding parameter library and automatically combines them to form the welding parameter group for the entire weld bead, forming a specific welding program for the 60MW air-cooled generator model. The welding program includes the robot motion trajectory and welding process parameters.

[0045] like Figure 1 As shown, for the welding of the core clamping ring 1 and the ear plate 2: the welds on the left and right sides are single V-shaped bevels, and after the bevels are filled, fillet welds are welded, with the welding position being vertical upward; the upper side is a fillet weld, with the welding position being flat; the lower side is a fillet weld, with the welding position being overhead. According to the automatic weld bead layout results of the offline programming software, vertical upward welding requires 2 layers, totaling 2 welds; flat welding requires 2 layers, totaling 3 welds; overhead welding requires 2 layers, totaling 3 welds.

[0046] For the welding of the U-shaped plate 4 to the base spring plate 3, and the welding of the ear plate 2 to the U-shaped plate 4: all four sides (top, bottom, left, and right) are fillet welds. The welding positions on the left and right sides are vertical welds, the welding position on the top side is a flat weld, and the welding position on the bottom side is an overhead weld. According to the automatic weld bead layout results of the offline programming software, vertical welds require 2 layers, totaling 3 welds; flat welds require 2 layers, totaling 3 welds; and overhead welds require 3 layers, totaling 6 welds.

[0047] Step 2: The operator selects the 60MW air-cooled generator model in the host computer software interface, and the robot automatically calls the corresponding welding program for the 60MW air-cooled generator model from the offline programming software;

[0048] To ensure accessibility of all welding positions within the constraints of the workpiece's shape, a non-standard, custom-made welding torch must be used. The torch handle diameter is 18mm, the straight section length is 320mm, and the gooseneck angle at the tip is 80°.

[0049] Based on the type of base material of the workpiece, select ER50-6 solid welding wire conforming to GB / T 8110-2008 standard, with a wire diameter of 1.2mm. The welding shielding gas is 80% Ar + 20% CO2.

[0050] Step 3: In the automated welding workstation, the robot automatically moves from a safe position to the welding area on the ground rail (X-axis motion mechanism), first completing the welding of the core clamping ring 1 and the ear plate 2; before welding, the welding torch 9 measures the deviation between the actual position and the theoretical position of the workpiece through contact positioning, and the offline programming software automatically corrects the existing welding trajectory; after the correction is completed, the Y-axis motion mechanism, the Z-axis motion mechanism and the robot work together to perform the welding operation;

[0051] Step 4: The robot then completes the welding of the spiral plate 4 and the base spring plate 3. Before welding, the welding torch 9 measures the deviation between the actual position and the theoretical position of the workpiece by contact positioning. The offline programming software automatically corrects the existing welding trajectory. After the correction is completed, the Y-axis motion mechanism, the Z-axis motion mechanism and the robot work together to perform the welding operation.

[0052] Step 5: Finally, complete the welding of ear plate 2 and U-shaped plate 4; before welding, welding torch 9 measures the deviation between the actual position and the theoretical position of the workpiece by contact positioning, and offline programming software automatically corrects the existing welding trajectory; after correction, the Y-axis motion mechanism, Z-axis motion mechanism and robot work together to perform welding operation.

[0053] Step 6: After all welds are completed, the robot automatically returns to a safe position.

[0054] It should be noted that in steps 3-5, the welding is carried out simultaneously and symmetrically by two robots on both sides of the base.

[0055] The welding torch contact positioning process includes the following steps:

[0056] Establish a user coordinate system OXYZ on the 3D model workpiece, where the origin O and the three axes XYZ are set manually.

[0057] When the actual workpiece placement deviates from the theoretical position, the tip of the welding wire of the welding torch 9 touches the workpiece surface from three mutually perpendicular directions. When they make contact, the open-circuit voltage of the welding power source drops to zero instantly.

[0058] When the robot detects a change in the no-load voltage, it stops moving and records its current position coordinates. It then calculates the user coordinate system O'X'Y'Z' of the actual workpiece. The positional relationship between the user coordinate systems OXYZ and O'X'Y'Z' can be calculated using the following formula:

[0059] [User coordinate system OXYZ] = [Transformation matrix] × [User coordinate system O'X'Y'Z'];

[0060] After obtaining the [transformation matrix], the [transformation matrix]' can be obtained through mathematical processing;

[0061] The coordinates of all label points on the multi-layer, multi-pass welding path are then calculated using the following formula, thereby obtaining all welding trajectories in the new user coordinate system and correcting the original welding trajectories:

[0062] [X′Y′Z′A′B′C′]=[Transformation Matrix]'×[XYZABC].

[0063] like Figure 2-5As shown, an automated welding workstation for assembling an air-cooled generator stator is used to implement the aforementioned welding method. It includes an XYZ three-dimensional motion mechanism 5, on which a six-axis industrial robot 6 is mounted. The six-axis industrial robot 6 is equipped with a welding mechanism, which includes a welding torch 9, a wire feeding mechanism, and a torch cleaner / wire cutter 10. The welding torch 9 and the wire feeding mechanism cooperate with each other, and both are in conjunction with the torch cleaner / wire cutter 10. The welding torch 9 is electrically connected to a welding power supply 11, which is a pulse welding power supply 11, enabling low-spatter welding and significantly simplifying pre-welding protection of the stator core. The welding torch 9 is a non-standard customized welding torch 9, ensuring accessibility to all weld positions during the assembly welding of different models of air-cooled generator stators. The XYZ three-dimensional motion mechanism 5, the six-axis industrial robot 6, and the welding mechanism are all electrically connected to a workstation control system 7, which controls the operation of the XYZ three-dimensional motion mechanism 5, the six-axis industrial robot 6, and the welding mechanism. The workstation control system 7 includes offline programming software, which is used to generate welding programs for each generator model. Safety guards 8 are installed on both sides of the workstation.

[0064] The XYZ three-dimensional motion mechanism 5 includes an X-axis motion mechanism, a Y-axis motion mechanism, and a Z-axis motion mechanism. The motion directions of the three motion mechanisms are perpendicular to each other. The X-axis motion mechanism is a ground track, and the Y-axis motion mechanism is a lifting track. The X-axis motion mechanism and the Y-axis motion mechanism are in sliding engagement and their motion directions are perpendicular. The Y-axis motion mechanism and the Z-axis motion mechanism are also in sliding engagement and their motion directions are perpendicular. Each of the X-axis, Y-axis, and Z-axis motion mechanisms includes a servo motor, a reducer, and a mechanical transmission mechanism.

[0065] Two six-axis industrial robots 6 are provided, located on both sides of the generator stator frame. The two six-axis industrial robots 6 are welded simultaneously to avoid the relative positional misalignment between the stator core and the frame that may be caused by welding on one side. The six-axis industrial robots 6 are mounted on the Z-axis motion mechanism and are mounted on a seat.

[0066] The workstation control system 7 includes a host computer, a PLC controller, a touch screen, and a main control cabinet. The touch screen is installed on the front panel of the main control cabinet, and the PLC controller is installed inside the main control cabinet.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention's technical solution. Therefore, all equivalent changes made based on the shape, structure, and principle of the present invention without departing from the scope of the present invention's technical solution should be covered within the protection scope of the present invention.

Claims

1. An automated welding method for assembling the stator of an air-cooled generator, characterized in that, Includes the following steps: Step 1: Import the 3D model of the generator stator assembly welding workpiece into the offline programming software. The software automatically arranges the weld seams according to the input workpiece and weld seam size information. Based on the different welding sequence and welding position of each weld seam, the software selects single-pass welding parameters from the accumulated welding parameter library and automatically combines them to form the welding parameter group of the entire weld seam, thus forming a welding program for each generator model. Step 2: Select the generator model in the host computer software interface, and the robot will automatically call the welding program for the corresponding generator model from the offline programming software; Step 3: In the automated welding workstation, the robot automatically moves from a safe position to the welding area on the ground rail. First, it completes the welding of the core clamping ring and the ear plate. Before welding, the welding torch measures the deviation between the actual position and the theoretical position of the workpiece through contact positioning. The offline programming software automatically corrects the existing welding trajectory. After the correction is completed, the robot performs the welding operation. Step 4: The robot then completes the welding of the spiral plate and the base spring plate. Before welding, the welding torch measures the deviation between the actual position and the theoretical position of the workpiece by contact positioning. The offline programming software automatically corrects the existing welding trajectory. After the correction is completed, the robot performs the welding operation. Step 5: Finally, complete the welding of the ear plate and the U-shaped plate; before welding, the welding torch measures the deviation between the actual position and the theoretical position of the workpiece by contact positioning, and the offline programming software automatically corrects the existing welding trajectory; after the correction is completed, the robot performs the welding operation. Step 6: After all welds are completed, the robot automatically returns to a safe position; The welding torch contact positioning process includes the following steps: Establish a user coordinate system OXYZ on the 3D model workpiece, where the origin O and the three axes XYZ are set manually. When the actual workpiece placement deviates from the theoretical position, the tip of the welding wire of the welding gun touches the workpiece surface from three mutually perpendicular directions. When they make contact, the open-circuit voltage of the welding power source drops to zero instantaneously. When the robot detects a change in the no-load voltage, it stops moving and records its current position coordinates, thereby calculating the user coordinate system of the actual workpiece. The user coordinate system OXYZ can be calculated using the following formula. Positional relationship between them: ； get Then, through mathematical processing, it can be obtained ; The coordinates of all label points on the multi-layer, multi-pass welding path are then calculated using the following formula, thereby obtaining all welding trajectories in the new user coordinate system and correcting the original welding trajectories: 。 2. The automated welding method for assembling an air-cooled generator stator according to claim 1, characterized in that, The welding procedure includes the robot's motion trajectory and welding process parameters.

3. An automated welding workstation for assembling the stator of an air-cooled generator, used to implement the welding method described in claim 1 or 2, characterized in that, The system includes an XYZ three-dimensional motion mechanism, on which a six-axis industrial robot is mounted, and on which a welding mechanism is mounted. The XYZ three-dimensional motion mechanism, the six-axis industrial robot, and the welding mechanism are all electrically connected to a workstation control system. The workstation control system is used to control the operation of the XYZ three-dimensional motion mechanism, the six-axis industrial robot, and the welding mechanism. The workstation control system includes offline programming software used to generate welding programs for each generator model. Safety protection devices are installed on both sides of the workstation.

4. The automated welding workstation for assembling an air-cooled generator stator according to claim 3, characterized in that, The welding mechanism includes a welding torch, a wire feeding mechanism, and a torch cleaning and wire cutting device. The welding torch and the wire feeding mechanism cooperate with each other, and both the welding torch and the wire feeding mechanism cooperate with the torch cleaning and wire cutting device. The welding torch is electrically connected to a welding power source, and the welding power source is set as a pulse welding power source.

5. An automated welding workstation for assembling an air-cooled generator stator according to claim 3, characterized in that, The XYZ three-dimensional motion mechanism includes an X-axis motion mechanism, a Y-axis motion mechanism, and a Z-axis motion mechanism. The motion directions of the three motion mechanisms are perpendicular to each other. The X-axis motion mechanism is a ground track, the Y-axis motion mechanism is a lifting track, the X-axis motion mechanism and the Y-axis motion mechanism are slidably coupled and their motion directions are perpendicular. The Y-axis motion mechanism and the Z-axis motion mechanism are also slidably coupled and their motion directions are perpendicular.

6. An automated welding workstation for assembling an air-cooled generator stator according to claim 5, characterized in that, Two six-axis industrial robots are provided, located on both sides of the generator stator frame. The two six-axis industrial robots are used for welding simultaneously to avoid misalignment between the stator core and the frame caused by welding on one side. The six-axis industrial robots are mounted on the Z-axis motion mechanism.

7. An automated welding workstation for assembling an air-cooled generator stator according to claim 3, characterized in that, The workstation control system includes a host computer, a PLC controller, a touch screen, and a main control cabinet. The touch screen is installed on the front panel of the main control cabinet, and the PLC controller is installed inside the main control cabinet.

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