Currently, there are not many maturely developed dynamic resistance monitoring instruments for medium frequency spot welding machines, with most being experimental and developmental in nature. The sensors in the control system typically utilize Hall effect chips or soft belt coil sensors to collect voltage between electrodes and welding current. This information is then processed and controlled using microcomputer processing units and thyristor circuits. Although the front-end circuits may vary, the principles are similar.
The circuit of the dynamic resistance monitoring system comprises current channels, voltage channels, and conductance channels. The current channel includes a current sensor input terminal, amplifier, and precise full-wave rectified current. The voltage channel consists of voltage transmission wires, limiting amplifiers, absolute value amplifiers, and precise full-wave rectified current. The conductance channel is composed of dividers and control gates.
The divider calculates the conductance, providing a conductance proportional to the input signal. The control gate (VF) is controlled by pulses generated by the differential circuit (Z). With every peak in Z per half cycle, a narrow pulse is generated and sent to VF, opening the gate. VF settings isolate the influence of periodic induced voltage due to rapid current changes. The conductance channel transfers the signal to the CPU, where calculations are performed and control commands issued. According to data, such resistance monitoring systems can control within a range of ±4% of the predetermined resistance curve.
The dynamic resistance monitoring portion of the resistance rate monitor comprises current sensors, voltage transmission circuits (including induction voltage elimination circuits), resistance calculation units, resistance change inspection units, comparators, and semi-control units. The resistance calculation is performed every half cycle, but the output is the average resistance value per cycle. The voltage part must include circuits to eliminate voltage interference to obtain the true voltage drop across the electrodes.
Suzhou Agera Automation Equipment Co., Ltd. specializes in the development of automated assembly, welding, testing equipment, and production lines, primarily serving industries such as household appliances, automotive manufacturing, sheet metal, and 3C electronics. We offer customized welding machines, automated welding equipment, assembly welding production lines, and assembly lines tailored to meet specific customer requirements. Our goal is to provide suitable overall automation solutions to facilitate the transition from traditional to high-end production methods, thereby helping companies achieve their upgrade and transformation goals. If you are interested in our automation equipment and production lines, please feel free to contact us: leo@agerawelder.com
Post time: Mar-28-2024