螺母凸焊机 因其焊接时间短、热影响区小、效率高，是车身部件凸焊的选择 ，而高强度热成形钢板与螺母、螺栓的焊接也同样采用电阻焊设备。 Due to the ultra-high strength of high-strength hot-formed steel sheets and their extremely high mechanical safety, they are increasingly used in the automotive industry. The use parts are concentrated on the front / rear bumper frame, A pillar / B pillar, The central channel and the front and rear door crash plates and other key parts have nuts and bolts that need to be welded on the parts. The nut projection welder is a choice for the projection welding of body parts because of its short welding time, small heat affected area, and high efficiency. Welding of high-strength hot-formed steel plates with nuts and bolts also uses resistance welding equipment.
3. Case study:
Example 1: Suzhou Anjia projected welding of A column nut for a certain model, the plate is BTR165H hot-formed steel, thickness 1.8MM; nut is M10 projected flange nut, three-section crescent boss; welding requirements: torque 130N.M, thrust force 8KN, no damage to the thread, no obvious damage to the appearance;
3.1 Welder: The model is Anjia DR-30000J, which uses a mountain-shaped electrode to press vertically;
3.2 Adjustment of welding specifications:
3.2.1 When adjusting conventional resistance welding process parameters, there are three basic elements: welding time, welding current, and welding pressure are all indispensable. In the capacitor energy storage welding machine, there is no welding time adjustment. Welding current It is also reflected by the charging voltage. Therefore, the specification adjustment of the energy storage welder is mainly to match between the welding pressure and the charging voltage. In special cases, a tempering voltage will be added to refine the grain;
3.2.2 Difficulties to be overcome when adjusting the projection welding process of high-strength hot-formed steel nuts in this case: 1. The setting of welding pressure, because the strength of high-strength hot-formed steel plates is higher, greater pressure is required during welding, but The strength of the projection welding nut is low, and the larger pressure will cause the bump to collapse prematurely. Therefore, the saddle-shaped pressure curve is best used for welding pressure. In practice, the stepped two-stage pressure is more common, which can ensure The bump is not crushed and deformed too early, and it can not generate too much spatter in the later stage of nugget growth. 2. The setting of the charging voltage, the excessively high charging voltage generates excessive heat during welding, and the nut metal appears to be squeezed. There are two situations caused by splashing and splashing. One is that the welding connection area is reduced due to splashing (overheating), the nut push-out force is reduced, and the second is that the screw plug gauge cannot pass; the lower charging voltage will cause insufficient welding depth and nuts. The push-out force is not up to standard and the welding is false;
3.2.3 Process specification adjustment method. When adjusting two welding elements (charging voltage and welding pressure), one of them should be adjusted based on the other, and two adjustments cannot be made at the same time. Considering the application of experience, there are similar parameters for nut projection welding, which can effectively reduce the number of adjustments, but the welding of high-strength thermoformed plates requires greater current and pressure, which can be used on ordinary materials from the same specifications. The test data is adjusted as a starting point, and the best value is found after test welding and laboratory verification. When it is necessary to pay attention, the test welding data should be increased by 3-5% on the basis of mass production to meet other product requirements. Lower limit of fluctuation caused by the reason;
3.3 Confirmation of welding parameters:
Charging voltage setting
Welding pressure setting
Welding current monitoring
Welding pressure monitoring
Welding time monitoring
3.4 Push-out force and damage test of workpiece:
Torque sheet hand, universal testing machine, thread plug gauge
Torque ﹥ 180 NM; push-out force ﹥ 12KN, no abnormal thread, no damage to appearance
4． Electrode part process supplement:
4.1 In the high-strength hot-formed steel plate projection welding, due to the huge welding pressure and the very high peak current, the requirements for electrode materials are very high during welding, requiring a higher softening temperature, higher electrical conductivity and higher Hardness, and dispersed copper (alumina copper) has these advantages (softening temperature up to 950 °), becoming the most suitable electrode material for projection welding of high-strength hot-formed steel plates;
4.2 The commonly used materials for positioning pins are bakelite, ceramics, KCF, etc. In recent years, European and American car companies have used silicon nitride as a positioning pin for projection welding of high-strength hot-formed steel plates because of their longer service life (200,000 times) ), Good insulation effect, high hardness and other characteristics, making it a new favorite of the projection welding positioning pin material, but because of its high price, there is currently no universal use, but this is the direction of the future positioning pin.
4.3 Due to its physical characteristics and the use of hard gauge welding, high-strength hot-formed steel plates have a higher probability of metal extrusion. The lower electrode blowing method can effectively improve the welding process with a larger air pressure during welding. Area blowing can make the extruded metal oxidize and burn quickly, greatly reduce the adhesion of the extruded metal, and ensure the qualification of the thread.
Through the testing of the high-strength hot-formed steel plate projection welded parts, using Anjia capacitor energy storage welding machine and reasonable process conditions, the welding can meet the technical requirements, even much higher than the technical requirements. There is no doubt that the capacitor energy storage welding Machine is the most ideal projection welding equipment for high-strength hot-formed steel plate projection welding, which brings a major welding process breakthrough to the welding industry! Bringing spring to the industry's high-strength hot-formed steel plate nut projection welding!