Purchase and application of the hottest welding ro

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The selection and application of welding robots

I. the development history of robots

as early as the Western Zhou Dynasty more than 3000 years ago, puppets capable of singing and dancing appeared in China, known as "advocates", which may be the earliest "robots" in the world

in modern times, with the first and second industrial revolution and the invention and application of various mechanical devices, many "robot" toys and handicrafts have appeared all over the world. Most of these devices are driven by the clock mechanism and use cams and levers to transmit motion

in 1920, the Czech writer K. kebic first proposed the term robot (previously translated as "Robert" in Chinese) in a science fiction script. Now it has been used as a special term for robots

in 1950, American writer I. Asimov put forward the concept of robotics and put forward the so-called "three principles of robotics", namely: 1 Robots should not hurt people; 2. The robot must obey the instructions given by people, but not (1) contradictory instructions; 3. On the premise that it does not contradict the principles (1) and (2), the robot can maintain itself from injury

in the 1950s and 1960s, with the development of mechanism theory and servo theory, robots entered the stage of use. In 1954, Vol of the United States issued a patent for "general purpose robot"; In 1960, American AMF company produced cylindrical versatran robot, which can be used for point position and trajectory control. It is the first robot used in industrial production in the world

In the 1970s, with the development of computer technology, modern control technology, sensor technology and artificial intelligence technology, robots have developed rapidly. In 1974, Cincinnati Milacron successfully developed a multi joint robot; In 1979, union company launched PUMA robot, which is a multi joint, all electric drive, multi CPU secondary control; Adopt Val special language; It can be equipped with vision, touch and force sensors. At that time, it was an advanced industrial robot. The current industrial robot structure is basically based on this

robots in this period belong to "teach in/playback" robots. It only has the ability of memory and storage, and repeats the operation according to the corresponding procedures, but it basically has no ability of perception and feedback control of the surrounding environment. This kind of robot is called the first generation robot

in the 1980s, with the development of sensing technology, including visual sensors, non visual sensors (force, touch, proximity, etc.) and information processing technology, the second generation of robots - sensory robots appeared. It can get some information about the working environment and the working object, carry out some real-time processing, and guide the robot to work. The second generation of robots has entered the use, and has been widely used in industrial production

the third generation robot is currently being studied as an "intelligent robot". It not only has more perfect environmental perception ability than the second generation robot, but also has the ability of logical thinking, judgment and decision-making. It can work independently according to the job requirements and environmental information

II. Definition and basic composition of robot

due to different research focuses, there is no clear unified standard for the definition of robot in the world at present. Based on various definitions, robot can be understood as: robot is a programmable automatic machine under the control of computer. According to the environment and operation needs, it has at least one or more anthropomorphic functions. In addition, it may also have some environmental perception abilities (such as vision, force, touch, proximity, etc.), language functions, even logical thinking, judgment and decision-making functions, etc, So that it can replace people in the required environment

robot of explosion-proof electromagnetic reversing valve is generally composed of the following parts:

1 Mechanical body

the mechanical body mechanisms of robots are basically divided into two categories: one is the operation body mechanism, which is similar to human arms and wrists. After being equipped with various claws and end operators, it can carry out various grasping actions and operation operations. Industrial robots mainly use this structure. The other is the mobile body structure, which is mainly used to realize the mobile function. It mainly includes wheel type, crawler type, foot leg type structure, snake, creep, deformation and other mechanisms. Mechanisms such as wall crawling and underwater propulsion can also be classified into this category

2. Driving servo unit

the action of the robot body mechanical structure depends on the joint drive of the joint robot, and most robots are based on the closed-loop control principle. The function of the servo controller is to make the driving unit drive the joint and drive the load to exceed the direction of reducing the deviation. The widely used driving methods include hydraulic servo drive and motor servo drive. In recent years, pneumatic servo drive technology has also made some progress

3. The command value of servo drive of each joint of the computer control system is calculated by the main computer and given in each sampling period. The main computer converts the data into the command value of the joint through inverse kinematics operation according to the spatial position, orientation and speed of the reference coordinates of the teaching point

generally, robots are controlled by two-level computers: the main computer and the joint driven servo computer. Sometimes, in order to realize intelligent control, it is necessary to collect and process various sensor signals including vision, and carry out pattern recognition, problem solving, task planning, judgment and decision-making, etc. at this time, the teaching points in space will be generated by another computer's superior computer according to the sensor signals to form a three-level computer system

4. The sensor system

in order for the robot to work normally, it must maintain close contact with the surrounding environment. In addition to the position sensor (called internal sensor) of the joint servo drive system, it should also be equipped with vision, force, touch, proximity and other types of sensors (called external sensor) and the sensing signal acquisition and processing system

5 Input/output system interface

in order to contact and respond with surrounding systems and corresponding operations, there should also be various communication interfaces and man-machine communication devices. The industrial robot provides an internal PLC, which can be connected with external equipment to complete the logic and real-time control with external equipment. Generally, there is more than one serial communication interface to complete disk data storage, remote control, offline programming, dual robot coordination, etc. Some new robots also include speech synthesis and recognition technology and multimedia systems to realize man-machine dialogue

III. selection and application of arc welding robot

first, in order to meet the accessibility of any position and posture in the robot workspace, there should be 5 degrees of freedom, but in order to avoid obstacles, there should generally be 6 degrees of freedom. For welding robots, the weight of welding gun wire feeder is generally small, ranging from 5kg to 6kg. Due to the different spatial structure of robots, even with the same load, the spatial motion range of robots with similar connecting rod size is very different. Generally speaking, the spatial motion range of robots with parallelogram structure is smaller than that of joint robots. Therefore, hoisting or wall mounted robots generally use articulated robots. The point-to-point motion accuracy is supported by some automobiles: China Plastics Processing Industry Association, China synthetic resin Association, the first automobile group, Taiwan Autodesk, lantiqi engineering plastics, bentler, keens and baiwangban are +/- 0.1mm or +/- 0.05mm, and the maximum motion speed is 1m/s to 1.5m/s; In the case of similar prices, try to choose products with high precision and high speed, because the above indicators reflect the overall quality of the robot and are also related to the degradation of the robot performance

as for the i/o function, the i/o interface of general robots can be addressed and operated by the main program (job), and can also be programmed by internal PLC; For the internal PLC, the main requirement is reliable performance. Due to application restrictions, its function is worse than that of general-purpose PLC. Generally, it only has the most basic logic and timing functions, so the performance requirements cannot be too high. Motion interpolation function generally requires joint, straight line, arc and other functions. Nowadays, robots generally have relatively perfect self diagnosis and safety protection functions; Generally, the average trouble free time of robots is about 20000 hours or more - that is, according to the two shift working system (16 hours/day), there will be no trouble in five years. For the arc welding robot, in order to complete the action of imitating human welding and get high-quality welds, it also requires a swing function. With this function, the robot also has the conditions to use the arc as a sensor to track welds. For the second generation of arc welding robot, in addition to the teaching and reproduction function, it should also have certain adaptability to the surrounding environment, such as welding start point detection and weld tracking function. For the weld tracking function, it has been developed, such as mechanical contact type, electromagnetic induction type, arc induction type, photoelectric induction type and visual sensor. The auxiliary equipment of arc welding robot, such as welding machine, wire feeder, welding gun and welding gun cleaning device, water cooling device, etc., requires relatively high reliability. Robot welding gun is a very important component, which should be specially made. For the welding of construction machinery or large-scale equipment manufacturing and automobile industry, qualified manufacturers should try to choose better welding guns and welding gun cleaning equipment, which will definitely benefit from it

IV. selection and application of spot welding robot

the requirements of spot welding robot for motion are generally not as strict as that of arc welding robot (in theory, even as long as the motion function of point-to-point is required), the point-to-point repeated positioning accuracy is less than +/- 0.5mm, and the requirements for the repeated positioning accuracy of trajectory are not too strict, as long as the motion range meets the production requirements; The requirements for robots are great strength, good structural rigidity, firmness and reliability. The main selection index of spot welding robots is spot welding equipment. Welding tongs and power supply are the most important auxiliary equipment of spot welding robot. The efficiency of power supply directly determines the size of robot load and water flow. Because spot welding equipment consumes a lot of energy, improving power efficiency is of great significance to energy conservation. The integrated welding tongs mainly depends on the quality of its power transformer. When there are many spot welding machines in the workshop, the power consumption is huge. If the capacity of the power supply transformer in the workshop is improved alone, according to the national standard, the wood-based panel experimental machine has a multi-functional experimental use, which is bound to cause a waste of resources and money. Moreover, when multiple welding machines work at the same time, it is easy to cause a sudden increase in the electrical load and a sudden drop in the electrical voltage. Therefore, a welding group control system should be set up to control multiple welding machines, Realize the time-sharing interleaving of welding current, stabilize the electric voltage, and ensure the quality of welding joints. The selection of welding tongs mainly depends on whether the shape can meet the work requirements. In addition, it depends on whether the water, gas circuit and joint are designed reasonably and whether air leakage and water leakage accidents are easy to occur. The selection of cables is also very important, and non inductive cables are required. For the integrated welding tongs, since the electric power is directly connected to the welding transformer, if the power line is placed at will, friction will occur with the power line due to the continuous movement of the robot. If the wire is exposed, the consequences will be unimaginable. Therefore, first, wear-resistant cables should be selected, and second, the cables should be fixed with the robot or simply sleeved outside the cables with wear-resistant hoses. Some robot manufacturers' product design is very considerate, and they can pass water, electricity, gas and other pipelines through the machine

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