Application and development of steel barrel automatic seam welding machine (2)

(Experience of developing FN250 steel drum automatic seam welding machine)

Nanjing Mining Machinery Factory Deng Jianliang

Fourth, the main components of the steel drum automatic welding machine and its working conditions.

At present, the working process of automatic seam welding machines for barrels produced in various countries is similar. Generally include coiling, conveying, welding, and weld correction. Due to the high degree of automation and welding speed, the requirements for the steel plate for making the barrel are high: the length and width error of the steel plate should not exceed ±0.5 mm. The two diagonal errors must not exceed ± 1.5 mm. The welded edge of the steel plate must have no impurities such as an oxide layer. For hot-rolled steel sheets, the edges are subjected to rust removal to avoid increased resistance during welding, sparks, splashes and burrs. According to the empirical data provided by Calendo, the main chemical elements of welded steel sheets can be converted into equivalent carbon content according to the following formula to determine the weldability.

Equivalent carbon content C, E=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15

The letter to the right of the equation is the chemical element symbol. When the equivalent carbon content C and E is equal to about 0.09, the welding performance is the best.

According to the above work process, the welder will complete the following processes:

1. Roll forming. The cut steel plate is fed into a triaxial forming roll. The feeding port of the forming roller is automatically opened by a pneumatic valve according to a certain procedure, and the feeding to the welding machine can be avoided. There is also a set of small diameter shoe rolls at the exit of the three forming rolls to prevent overly visible straight sections from being formed at the edges of the rolled barrel.

2. Conveyor barrel. Use a linear thruster to feed the barrel to the welding station. At present, the following two types of propulsion mechanisms are generally used in welding machines in various countries: (1) Crank propellers. In the starting and stopping stages of the propeller movement process, the speed of the mechanism changes gently, and the stability of the barrel movement is ensured (2) the chain and the pawl type propeller. In order to reduce the inertia force in starting and in place, the chain drive is driven by a two-speed motor.

3. Positioning and welding. The welding station consists of a 'Z' shaped rod, a positioning roller and upper and lower rollers. The barrel is pushed by a pneumatic pawl push rod along the "Z" shaped rod between the upper and lower welding wheels. The barrel depends on 'Z The positioning grooves on both sides of the rod are positioned, and in the process of advancing, as the 'Z'-shaped rod positioning groove gradually approaches, the sides of the barrel gradually close together. When the barrel leaves the guide bar and enters the upper and lower rollers, the sides of the barrel are smoothly overlapped, and the "Z" shaped rod is used to ensure that the overlapping portion is aligned with the center of the roller. The upper and lower rollers and the outer diameter positioning roller are important parts for welding and stabilizing the barrel position. The roller is made of a copper alloy of high hardness and high electrical conductivity (it is generally required to have a hardness of more than HB65 and a conductivity of 751 ACS or more). In order to prevent the roller from being deformed and damaged due to high current heating, the upper and lower welding circuits together with the upper and lower welding wheels adopt a circulating water internal cooling system. In addition, the upper and lower welding wheels are equipped with a lateral shifting mechanism. For each barrel, the upper and lower welding wheels are moved laterally by a certain distance, thus ensuring the heat dissipation effect of the welding wheel and the uniform use of the surface. The outer diameter positioning roller is generally composed of a set of copper rolls, and generally has a single row of three rolls and a double row of six rolls. When the barrel is fed into the welding wheel, it also enters the positioning roller to ensure that the weld is not offset during welding. When the barrel enters and leaves the welding station, the conduction and cut-off of the welding power source is controlled by a set of infrared barrel position detecting devices.

4. Weld correction. Due to the lap welding process, the barrel welds welded by the ordinary welder have certain steps, and the thickness of the lap joint is about twice the thickness of the steel plate. This brings a very unfavorable factor to the inner and outer coating process and the bottom, cover and barrel packaging of the steel drum. Therefore, in the automatic welding machine of the steel drum, close to the welding wheel, there is a set of rolls and welding. The wheel rotates at the same line speed. When the weld of the barrel has just left the welding wheel and is still in a red hot state, it enters a group of rolls. Under a pressure of about one ton, not only the internal structure of the weld is made more dense, but also the steps of the weld bead are eliminated, forming a flat and smooth flat weld. Its thickness is only about 1.2 times the thickness of the barrel steel plate.

5. Heat and control procedures. Due to the extremely short formation time of the solder joints, the narrow temperature field distribution and many influencing factors, the stability of solder joint quality is a key issue in resistance welding for a long time. The automatic welding machine for steel drums is no exception. The design of the welding machine and the determination of the welding process have a very prominent position. The quality control of seam welders is very extensive, but in the welding process to ensure a specific accurate temperature field, its thermal control is clearly the first means. In order to achieve this control, various steel drum automatic welders are equipped with special controllers. The British Federal Company's DW250/6 welder is controlled by the company's dedicated UZDVR (uphill, impedance, downhill, voltage adjustment) components, and Figure 5 shows the machine's thermal control curve. Changes from this curve reflect the UZDVR component's ability to:

1. Thermal control. The welding current is adjusted from 40% to 100% with stepless adjustment.

2. Uphill control. In the 10 cycles from the start of welding, the initial percentage of the stepless adjustment welding current is adjusted to 40% of the maximum current required to form a certain slope of the welding current rise curve.

3. Impedance adjustment. During the entire welding process, the welding current is gradually reduced to offset the impedance change of the welding circuit caused by the barrel leaving the welding circuit. (The secondary rectifier welder does not require impedance adjustment).

4. Downhill control. In the 10 cycles of the end of the welding, the welding current decreases at a speed, and the slope of the welding current drop curve is formed.

According to the preset current curve, the barrel can maintain a stable welding current and temperature field during the welding process, thus ensuring the quality of the weld.

With the development of computer technology, the whole process of the welding machine is controlled by programmable control. For example, the DW250/6 welding machine recently produced by the British Federal Welding Machine Company adopts the West German Siemens Company. U-105 programmable controller. Thus, not only is the traditional program control system greatly reduced, but the welder can be monitored and quickly trouble-checked by the programmer, and the program can be modified directly through the keyboard.

Figure 5 heat control curve

V. China introduces and digests and absorbs the technology of foreign steel drum automatic welding machine.

China's barrel industry uses a seam welder to weld barrels for up to 40 years. Until 1981, Shanghai Dyeing 13 Factory first introduced a DW250/6 early steel drum automatic welding machine from the British Federal Welding Machine Company in the country, which was achieved in improving the production speed and quality of steel drums. The remarkable effect has aroused widespread concern in the national barrel industry. Four years later, Dalian Co., Ltd. and Nanjing Mining Machinery Factory introduced an improved DW250/6 steel drum automatic welding machine from the company, and jointly organized a delegation to the UK to conduct special technical inspections and exchanges. In 1986, Beijing Chemical Co., Ltd. introduced the 1424-3 secondary rectification steel drum automatic welding machine from Karendo Company of the United States. With the rise of the 'circular curling' heat and large-scale technological transformation in the domestic barrel industry, some conditional barrel factories have introduced such automatic steel barrel seam welding machines from abroad. According to the statistics of China Packaging Corporation in 1987, China has introduced and signed contracts for such welding machines up to 13 units, accounting for one-fifth of the country's barrel factories that have introduced such welding machines. Most of them were introduced from the British Federal Welding Machine Company and the American Calendo Company.

At the same time of introducing foreign welding machines, China has also done a lot of work in absorbing foreign technology and developing self-made steel barrel automatic seam welding machines. In 1981, the engineering and technical personnel of the barrel factory of the East China Branch of the Petrochemical Sales Corporation equipped with a self-made steel drum automatic sewing machine on the basis of the relevant foreign technical materials. welder. Subsequently, with reference to the welding machine of the British Federal Welding Machine Company, the redesigned and prototyped two new prototypes explored many useful experiences in the development of China's own steel barrel automatic seam welding machine. Since then, many domestic research institutes and professional factories have done a lot of research and investigation on foreign steel drum automatic seam welding machines, and have made a lot of attempts in the development of domestic welding machines, and have also gained a lot of experience. On this basis, in October 1986, Nanjing Mining Machinery Factory comprehensively analyzed the technical status of such domestic welding machines, and summarized the experience and lessons of domestic development work, and cooperated with Shanghai Electric Welding Machine Factory. Practical and feasible technical solutions for digesting and absorbing British welders. Therefore, the leaders of China Packaging Corporation and the Metal Container Committee, such as the barrel branch, received strong support and care, and adopted this plan. After more than a year of hard work, Nanjing Mining Machinery Factory and Shanghai Electric Welder Factory overcame many difficulties. On the basis of filling a number of domestic manufacturing process gaps, the first prototype was finally assembled in July 1988. Initially debugged successfully in September of that year. It is planned to equip the new barrel factory after further testing and testing. In addition, the second prototype that was put into production at the same time will soon be trial-produced. The era of China's steel drum automatic seam welding machine relying on imports will never return.

A few years of research and development work. Although the chanting has achieved initial success, in the course of practice we have also clearly seen that our basic industries are weak. China's steel drum automatic welding machine technology, to reach the current advanced level in the world, in the short term, there are still certain difficulties, for example: the quality of China's high-power thyristor rectifier components is not stable enough, still need to import. Therefore, we must rely solely on domestic conditions to directly develop advanced secondary rectification, and even three-phase secondary rectification steel drum full free seam welding machine, there are still some difficulties. However, we believe that it is an inevitable trend to further develop the steel barrel automatic seam welding machine for secondary rectification. As long as we strengthen cooperation between domestic industries, the technical level of China's steel drum automatic seam welding machine must be continuously developed and innovated. We can look forward to the hard work through three to five years, and it is sure to reach the international advanced level. .

Technical indicators of steel drum automatic welding machine of major foreign manufacturers

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