Liu Shoulong Ma Jia Sui Yongli Zeng Huilin 2, Yan Zheng 2, Li Jianjun 2 (1. Pipeline Bureau Welding Center, Langfang 065000, Hebei; 2. Pipeline Bureau Special Machinery Research Institute, Langfang 065000) The control method of the walking speed, wire feed speed and the vibration frequency of the welding torch in the welding process of the welding. : Long-distance pipeline; automatic welding technology; computer control system; process At present, pipeline construction has gradually developed from manual welding to fully automatic welding. Therefore, the development of automatic welding equipment for pipeline full-position has very important significance. The automatic welding of the pipeline in all positions means that the welding trolley drives the welding gun to move around the pipe wall along the track when the pipeline is relatively fixed, so as to realize automatic welding. The all-position automatic welding device is composed of welding trolley, walking track, automatic control system and other parts.
The purpose of developing an all-position automatic welding device is to improve welding quality and labor productivity, and reduce the labor intensity of workers.
1 Girth automatic welding device (welding trolley) The welding trolley is the driving mechanism of the automatic welding process. It is installed on the welding track and carries out a circular motion along the pipe wall with the welding gun. It is one of the important links to realize automatic welding of the nozzle. Its core part is the walking mechanism, wire feeding mechanism and welding gun swing adjustment mechanism. The walking mechanism is composed of a motor and a gear transmission mechanism. In order for the walking motor to execute the position and speed instructions issued by the computer control unit, the motor should be equipped with a speed feedback machine. Arc welding is difficult to ensure the final quality of the product. The track beam of the Three Gorges Permanent Shiplock is known as the "first beam of the hydropower system", with a length of 40m and a height of 4m. The conclusion is that the geometric dimensions after welding are very high. New requirements have been put forward in terms of internal quality assurance. The success of actual welding marks a new level of welding technology in the hydropower industry. We have all adopted C2 gas shielded welding and formulated detailed levels. At the same time, domestic semi-automatic The manufacturer of the automatic welding machine also needs the welding process guidance. During the welding process, according to the welding deformation, the hardware of the own equipment is perfected at any time according to the actual welding situation to meet the characteristics of user efficiency, but it can be displayed in the workpiece joint plate. Its advantages.
In the fabrication of the metal structure of the third section of the Three Gorges Permanent Ship Lock, the weld length of the butt plate is 6565), such as welding with electrode welding, 2 per person per day), 10 welders need to weld 328.25 days, and submerged arc welding For welding, it took only 218.8 days for five welders to weld, and the efficiency has increased by more than 3 times, which has won time for the next process. Submerged arc welding is basically used in the welding of the buried parts of the 14 hydraulic turbine units on the left bank of the Three Gorges, and the appearance of the weld seam is beautifully formed, which has been praised by the owners and experts.
2.2 The welding of prefabricated parts is applied to prefabricated parts, especially in the welding of T-shaped beams and I-beams. When welding with electrode arc welding, it is inevitable that the deformation of bending and side bending occurs. In the production, C2 gas shielded welding is used for welding, and two Lincoln welding machines are used for symmetric welding, which not only controls the deformation but also improves the welding efficiency, and greatly reduces the labor intensity of the welder.
2.3 Application of workpiece assembly welding In the assembly welding of workpieces, the quality requirements of the Three Gorges welding products are higher than those of similar products in terms of appearance and internal quality of the welds and the deformation control of the welding products. The inspection of geometric dimensions found that all the indexes were within the requirements of the specification. In the previous welding of similar products, the phenomenon of "tofu lump" inevitably appeared in the welding with the electrode arc welding, but it was overcome when welding with C2 gas shielded welding. Now all 16 track beams have been welded, and the geometric dimensions of each beam have been effectively controlled. Among them, 1 and 2 track beams have passed the joint inspection of national hydropower experts, Three Gorges Hydropower Development Corporation, and supervision units. Reached excellent, was rated as excellent engineering. The successful welding of the track beam provides a strong basis for the welding of the large-scale stacked beam door and the maintenance door of the permanent ship lock.
3 The next step of automatic welding and semi-automatic welding is now assumed. CO2 semi-automatic gas shielded welding has been used in the welding of embedded parts of hydraulic turbines (except for the volute). The next step is how to use it on the volute. The plate of the volute is a low-carbon high-strength steel with a tensile strength of 600MPa. The general welding wire cannot meet this welding requirement. At present, several solid core and flux cored welding wires are selected, such as Japan Kobelco for welding process evaluation. The test has been successful. The next step is to use gas shielded welding or flux cored self-shielded welding for the actual welding of the Three Gorges volute.
Ensure the accuracy of the adjustment process.
In the face of the increasingly fierce international market competition, in order to occupy a place in the pipeline welding market, we must improve the selection of construction equipment and technical water welding technology. Therefore, the research on the full-position automatic welding device of pipelines will improve the structure of our country to ensure The motor is accurately positioned at each position of the pipeline seam, and has a good speed tracking function. The wire feeding mechanism must ensure that the wire feeding speed is accurate and stable, has a small rotational inertia, has good dynamic performance, and should have sufficient driving torque. The welding torch swing adjustment mechanism should have the functions of the welding torch swinging left and right relative to the welding seam, staying at the left and right ends, controllable up and down and left and right postures, and adjusting the welding gun angle. The above-mentioned parts of the welding trolley are all programmablely controlled by the computer. After the program is started, the various parts of the welding trolley coordinate actions according to the logical sequence of the program. The welding process can also be manually intervened when needed, and at this time the program can automatically adjust and execute the welding parameters according to the amount of intervention. ! Welding track track is a special mechanism installed on the pipe for the positioning of the welding trolley. Therefore, the structure of the track directly affects the stability and position of the welding trolley, which also affects the welding quality. The track should meet the following conditions: certain The strength and hardness are wear-resistant and corrosion-resistant.
The rails commonly used in the world are nothing but flexible rails and rigid rails. The so-called rigid track is that the body of the track has a high rigidity and is not easily deformed, while the flexible track is relatively rigid. Both types of tracks have their own characteristics. The rigid rail has accurate positioning and small deformation after clamping, which can ensure that the welding trolley moves smoothly. The welding gun has a small radial adjustment during welding, but the weight is large and the assembly and disassembly are inconvenient. The flexible track is easy to assemble and disassemble, the weight is light, and the precision is not as high as the rigid track.
3 Wire feeding method The stability of wire feeding directly affects the welding quality. Wire feeding methods can be simply divided into wire drawing and wire pushing methods. Since the welding torch is closer to the wire feeder during wire drawing, the resistance of the welding wire after leaving the wire feeder during welding is less, so the wire feeding process can be ensured smoothly, but the wire feeder and the wire tray must be installed in the welding trolley In the above, the weight of the welding trolley is increased, which makes the manual assembly and disassembly more difficult, and the increase in weight is also likely to cause the welding trolley to walk unevenly. The use of a small coil of wire with a diameter of 0.8mm or 1.0 (weight about 5kg) reduces the weight and load of the welding trolley, and makes the welding process easy to control, but it has a certain effect on the welding efficiency. The wire pushing method is to install the wire feed mechanism outside the welding trolley, reducing the volume and weight of the welding trolley. A high-power wire feeder and a large-diameter welding wire with a diameter of 1.2 mm (weight about 20 kg) can be used. Thereby improving welding efficiency. However, because the wire feeder is far away from the welding gun when pushing the wire, there must be a wire feeding hose connected between the two. When the welding wire is continuously pushed to the nozzle of the welding gun, the friction resistance of the welding wire is greater, and the welding process The bending degree of the wire feeding hose has a certain effect on the stability of the wire feeding, and in serious cases, the wire feeding is not smooth, so the above factors must be fully considered when using the wire pushing. The welding process of flux cored wire self-shielded welding and manual welding is gradually transitioning to automatic welding.
The welding process using flux-cored wire and gas shielding, if it is formed multiple times, each time the surface of the weld seam is cleaned, it takes time and effort; if it is forced forming, it must be equipped with a shaped copper slider that moves with the welding gun, and access Circulating cooling water can greatly improve the welding efficiency, so that not only the structure of the welding device is complicated, but also the weight increases. Because the price of flux-cored welding wire is higher, and the gas source of the shielding gas must be solved at the same time, the welding cost is higher. The use of self-protected welding wire alone saves the protective gas, but it has the problem of difficult slag removal.
The welding process with solid core wire and gas protection. If it is formed in multiple passes, the welding process can be simply divided into three stages: priming, filling, and covering. The next process is directly performed without cleaning the weld surface, but welding The speed is slower than that of forced forming. Protective gas. The mixed gas of C2 + A6 can make the arc combustion stable and less spatter during welding, but the A6 gas source is difficult to find and the price is high in the field construction. From the economic point of view, it is best to use 1001CO2 as the best when welding oil pipelines Protective gas. It is ideal to use CO2 + A6 as protective gas when constructing in areas with conditions.
5 Control method In the welding process, the walking speed of the welding trolley, the wire feed speed and the left and right vibration frequency of the welding gun are the three main parameters, and the up and down adjustment of the welding gun can be ignored. Use a vertical line to divide the circumference of the pipe into two left and right semicircles, and then divide the two semicircles clockwise and counterclockwise to determine the welding node. Through a large number of tests, the ideal welding parameters can be obtained at each node of the cold wind. For example, after selecting a suitable welding process, through a large number of tests, the ideal welding current, arc voltage, and voltage at the nodes 0., 30., 60., 90., 120., 150., 180. A series of parameters such as wire speed, trolley traveling speed, welding gun vibration frequency, etc., and then input these parameters into the computer for automatic fitting and calculation, so that automatic welding from 0.180. However, the actual welding and test data will not be completely the same. During the welding process, the welding parameters can be adjusted according to the actual situation, and the parameters such as wire feed speed and vibration frequency can be added. However, the adjustment of these parameters is interrelated. The wire feed speed is adjusted properly, but the vibration frequency and welding car speed are not necessarily suitable. Only after a certain period of exploration can several parameters be adjusted and matched. If another control method is used, the situation is very different. The wire feed speed, welding car travel and welding gun vibration frequency are taken as three dependent variables, placed in a spatial coordinate system, with time as the independent variable, welding current and arc voltage as the boundary conditions, and finally the wire feed speed and welding The relationship between the traveling speed of the trolley and the vibration frequency of the welding torch is the spatial coordinate equation. In actual welding, each adjustment is the simultaneous adjustment of the above three parameters, thus confirming
A good night's sleep leaves you feeling refreshed and ready to take on the world, and having the right bed is the first step in creating a harmonious space. Choose a standard queen for the guest room, space-saving bunk beds for your child's room, or a luxuriously roomy cal-king for the master.We love designing with bed, and are so happy our clients are on board with it, too! The four-poster bed is a statement piece and adds a WOW factor in the bedroom and definitely gives off a glamorous side to the room without being too overly feminine; it still has a bit of an edge. Also, it is not very typical to find one in your standard master bedroom, so people are liking to be a little different and welcome this timeless trend back in their bedrooms!
Bedroom Beds,Kids Beds,Children Beds,Bunk Beds
HOPE IKEA , https://www.skywardrobes.com