[Scientific and technological achievements] Inner wall welding robot

The development of technology is always beyond people's imagination. Artificial intelligence has been applied and developed in transportation, finance, energy, manufacturing and other industries, affecting and changing people's lives in all aspects of clothing, food, housing and transportation. As a new "factor of production", artificial intelligence has a huge impact on the manufacturing industry. Machines will replace most people's work, including identification, management, decision-making, etc., which can also realize computer management and intelligent automation; artificial intelligence improves production efficiency by enhancing the skills of the labor force; the deep integration of artificial intelligence and manufacturing will subvert the original production process.

So what will the combination of artificial intelligence and traditional welding promote the development of welding technology and what problems will be solved in the field of welding? With these questions in mind, this issue will take you to learn about the AI visual intelligent weld tracking technology brought by the Institute of Power Transmission Applied Technology in our hospital ~

 

science and technology research and development]

Welding is one of the most common and important processes in metal processing. Unqualified welding quality is the main reason for the rapid occurrence of red rust or water quality indicators that do not meet the requirements. As the welded joint requires strict quality control measures, the requirements for welding equipment, argon quality, weld formation, weld color, weld surface roughness, slope, dead angle, etc. are also very strict.

Traditional Welding Technology

Welding technology is mainly used in the metal base material, commonly used mainly divided into welding, pressure welding and brazing three categories.

1. Fusion welding:Fusion welding is a method of heating the workpiece interface to a molten state during the welding process and completing the welding without pressure.

Fusion Welding Diagram

 

2. Pressure welding:Pressure welding is under pressurized conditions, so that the two workpieces in the solid state to achieve the combination of atoms, also known as solid-state welding. There are two forms. One is to heat the contact part of the welded metal to a plastic state or a local melting state, and then apply a certain pressure, such as forging welding, contact welding, friction welding and gas pressure welding. The second is not heating, only in the welded metal contact surface to apply sufficient pressure, this method has cold pressure welding, explosive welding, etc., mainly for composite steel plate.

Pressure welding diagram

3. Brazing:Brazing is the use of metal materials lower than the melting point of the workpiece as a solder, the workpiece and the solder are heated to a temperature higher than the melting point of the solder and lower than the melting point of the workpiece, and the liquid solder is used to wet the workpiece, fill the interface gap and realize the interdiffusion of atoms with the workpiece, so as to realize the welding method.

Brazing Illustration

Among the many welding technologies, the tube plate welding of the inner wall of the cylinder is a welding method with complex and changeable process parameters and welding torch posture, which is difficult to realize automation. The welding worker enters the cylinder and completes the welding operation with the posture of standing up, bending over or squatting. Therefore, the labor intensity of welding workers is large, the technical requirements are high, and the space is relatively closed and easy to gather welding fumes, which seriously affects the health of workers, which makes the talent gap in related industries increase year by year, and it is urgent to improve the level of automation.

Working status of inner wall welding workers

 

Difficulties in welding tube sheet on inner wall of cylinder

1. It belongs to all-position welding. The circumferential weld is distributed on the inner wall of the cylinder. It includes flat welding, vertical welding, overhead welding and transition welding on a workpiece. The welding process needs to be adjusted according to the weld position.

2. The weld is circumferential weld, and the attitude of the welding torch needs to be adjusted in time.

3, welding manipulator is difficult to imitate the operation experience of skilled welding workers.

Therefore, in view of the three major technical difficulties in automating the welding of the inner wall of the cylinder, the key technologies of digital collection of welding workers' experience, digital division of welding area segmentation experience and intelligent recognition of welding torch attitude have been studied in depth.

 

science and technology innovation]

According to the long-term accumulation, the inner wall welding robot developed by our institute has solved the technical difficulties of welding the inner wall of the cylinder. An intelligent recognition method for all-position welding torch space attitude is proposed: AI vision intelligent tracking.

AI Visual Intelligent Tracking Application Scenarios

 

Core technology: AI vision intelligent seam tracking technology

Traditional robot welding is the need to give a good trajectory of the robot running, in the entire implementation process, the robot coordinates can not be adjusted in real time, if the workpiece is not regular, the workpiece size changes in real time, will lead to welding failure. The welding of intelligent robot is to install "eyes" on the robot, which can automatically correct the trajectory in real time according to the coordinates provided by machine vision, and realize the welding of large-size inner wall workpieces through intelligent weld tracking.

 

AI visual intelligent tracking

Highly reflective metal weld tracking has always been a difficult problem, especially the large number of arcs generated in the welding process and the reflective interference of the metal itself bring great challenges to weld tracking. Traditional sensors can not adapt to multiple links and can not give real guidance to the robot. Robots need a pair of not afraid of arc light, intelligent resolution of the eyes. The weld tracking sensor independently developed by our hospital uses 650nm laser with the least content in arc light as the light source, with the first accuracy of more than 0.1mm and can collect data more than 30 times per second. Through the identification algorithm of artificial intelligence, this problem is perfectly solved.

Laser tracking de-noising (original image-noise image)

 

laser three-dimensional generation

At present, many people know that there is a coordinate system for robots, but there is another coordinate system for machine vision as eyes. The two coordinate systems cannot be unified, which makes it impossible to guide the robot to work by machine vision. Our hand-eye calibration technology perfectly solves this problem. The laser sensor and the robot can be unified by hand-eye calibration, and the robot can be perceived by vision. The vision and the robot communicate through the network protocol, which can be pre-scanned for welding path planning in advance, and can also be used for real-time path planning and error correction in the welding process. Achieve real-time high-precision seam tracking for highly reflective metal welding processes.

Most of the existing internal welding is carried out by manual welding, which is time-consuming and laborious, and the narrow internal space has great damage to the physical and mental health of people. Our institute has put forward a solution of internal welding by combining machine vision with robot. The robot and weld seam tracking system are equipped through the beam bracket. The welding spot is positioned by vision, and the spot welding is initially fixed. Then the robot is driven to move by the motion device. The vision recognizes the weld seam in real time and adjusts the position and posture of the welding robot, thus realizing high-precision and rapid welding of the inner wall circumferential seam.

The research and development application of visual inner wall robots is not limited to the field of weld seam tracking. The existing self-developed three-dimensional binocular blue light scanning equipment, weld seam tracking sensors, all-round human body three-dimensional scanners for large scenes, visual positioning systems, visual intelligent defect detection systems, etc. incubated based on this technology have been applied in many industries.

 

application value]

Advantages of inner wall welding robot technology

1. Improve production efficiency

The welding robot has a short response time and rapid action. The welding speed is 600 mm/min, which is much higher than that of manual welding. The robot does not stop or rest during operation. As long as the external water, electricity and other conditions are guaranteed, it can continue to work. This virtually improves the production efficiency of the enterprise.

2. Improve product quality

Welding robot in the welding process, as long as the welding parameters and trajectory, the robot will accurately repeat this action, welding parameters such as welding current, voltage, welding speed and welding wire length of the welding results play a decisive role. When using robot welding, the welding parameters of each weld are constant, and the quality of the weld is less affected by human factors, which reduces the requirements for workers' operation technology.

3. Reduce business costs

The reduction of enterprise costs by welding robots is mainly reflected in large-scale production. The robot has no fatigue and can be continuously produced 24 hours a day. In addition, with the application of high-speed and efficient welding technology, the cost reduction of robot welding is more obvious.

4. Easy to arrange production plan

Due to the high repeatability of the robot, as long as the parameters are given, it will always act according to the instructions, so the robot welding product cycle is clear and it is easy to control the product output. The robot's production rhythm is fixed, so the production plan is very clear. Accurate production planning should maximize the production efficiency and comprehensive utilization of resources.

5. Shorten the cycle of product modification.

Robot welding can shorten the cycle of product modification and reduce the corresponding equipment investment. Can realize the welding automation of small batch products. When the product is updated, only the corresponding tooling and fixtures need to be designed according to the updated product. The robot body does not need to make any changes. As long as the corresponding program commands are changed and called, the product and equipment can be updated.

6. Ensure product quality and stable output

Through visual intelligent tracking technology, it can detect whether there are defects in the finished product, read the label and two-dimensional code and bar code on the product and packaging to obtain product information, and measure the distance of the item. Improve production and optimize quality, eliminate errors, reduce costs, ensure stable production lines, high-quality output.

 

Industrial Applications

 

Application Schematic of Inner Wall Welding Robot

 

At present, this technology has been applied in the mold insert production line of Tianjin Automobile Mould Co., Ltd., which solves the problem of automatic production line manufacturing of single piece without batch insert. Hebei Hongtai Special Purpose Vehicle Co., Ltd. uses a vision-guided inner wall welding robot to realize the visual self-tracing welding of large container tanks.

 

Research Institute of Power Transmission Applied Technology

The Institute of Power Transmission Application Technology of our institute was established in November 2016. Relying on the comprehensive technical strength of the Department of Electrical Engineering and Applied Electronic Technology, the State Key Laboratory of Power System and Large Power Generation Equipment Safety Control and Simulation, it has established extensive cooperative relations with domestic and foreign motor design and simulation development institutions and enterprises. The team is headed by Professor Chai Jianyun, a senior expert from the Department of Electrical Engineering and Applied Electronic Technology of Tsinghua University. The core members of the team come from well-known universities and enterprises at home and abroad. They have many years of practical experience in power transmission and control, energy-saving design and simulation of motor systems, and product research and development, scientific research achievements have been applied to electric power, petroleum, rubber and plastics, papermaking, transportation, machinery and other industries, and have established technical cooperation relations with many enterprises in Shandong, Hebei, Jiangsu, Anhui, Shaanxi and other places.

 

Technical docking and business negotiation

Contact: Guo Qijiang

Fixed telephone: 022-84819376

Mobile Phone: 13332029286

E-mail: guoqj@tsinghua-tj.org

 

Source | Institute of Power Transmission Application Technology

Editor | Wang Xiao

 

The final interpretation of the above related technologies belongs to the Institute of Power Transmission Application Technology.