The pulse weighing system is mainly composed of the raw material storage bin, the electric vibration feeder, the hopper scale, the weighing module, the hopper motor, and the PLC control system. According to the requirements of the task, this high-precision weighing system is applied to the weighing of metal powder in the weighing batching machine. It adopts the intermittent static weighing principle and, in accordance with the technical requirements, weighs 30 times per minute, that is, the process of discharging, weighing, and discharging is completed in each cycle period (2 seconds).

The process of weighing system is mainly the batching metering and feeding process. In batching metering process, firstly, the time of discharging from the material feeder to the metering tank is controlled according to the weighing requirements, so as to control the amount of material entering the metering bin, and then the time of discharging from the feeder to the metering tank is controlled according to the material proportioning requirements, so as to control the weight entering the metering tank, thus completing the weighing process once until the specified weighing times for each batching are completed.

The weighing loading machine is mainly controlled by PLC for the electrical control of the system, the display of the weighing instrument and the control of the weighing module. It can realize the control of the frequency converter of the separator, remote start and stop of the main motor, control of the size and speed of the tensioning station screw, display of the thrust and temperature of the main motor, and remote start and stop of the batching machine, etc. The 4~20mA analog signals collected on site are converted into weighing signals through the analog input module of the PLC. The PLC program compares the instantaneous value of the detected screw with the set value in real time internally, and controls the start and stop of the screw conveyor by the digital output template.

The feeding system adopts Siemens PLC to control the automatic operation of all its interlocking devices (start-stop, interlocking, position switching and other operations), and the upper computer is programmed by Siemens WINCC configuration software. The whole configuration operation screen is embedded into the whole weighing system, and the operation of equipment start-stop operation, operation display, fault inquiry record and maintenance are carried out. The system has the characteristics of friendly interface, concise operation and reliable operation.

The movement of the mixed weighing and retaking machine is driven by two motors simultaneously. A frequency converter is added to the circuit to control the left and right movement of the screw conveyor system. The protection is mainly provided by the frequency converter without protection. When driving dual motors according to the usage requirements of the frequency converter, thermal relays are used in conjunction. The PLC outputs forward and reverse operation instructions to activate the corresponding intermediate relays. Then, the normally open point of the intermediate relay controls the frequency converter. The PLC directly sends 4~20mA to the frequency converter, and the frequency converter feeds back the speed regulation signal to form a closed-loop control.

To reduce the mechanical inertia and the deviation in loading caused by factors such as the spiral feeding of the feeding equipment, the weighing discharge machine requires the PLC to issue a signal indicating that the loading is complete before stopping the feeding equipment. The loading completion signal is sent when the weight of the hopper reaches the loading completion control value. An appropriate loading completion advance amount should be selected. After one weighing cycle is completed, the loading deviation can be calculated, and the loading advance amount for each material in the next weighing cycle can be corrected using this loading deviation.

The weighing and lifting machine adopts a method of moving while the feeding and discharging positions are fixed for material transfer. According to the actual situation on site, the position of the material silo is set as the feeding and discharging position, and a chain conveyor is installed. After the PLC issues the feeding command, the transfer machine starts to simultaneously deliver the two barrels of materials to the conveying position. The conveyor rises and rotates to send the materials to the feeding machine. After the feeding machine detects the materials, it moves to the selected material silo. After the frequency converter of the feeding machine starts to increase at high speed to the deceleration position, it reduces the speed to pour the materials into the corresponding silo. To ensure that the materials are fully and thoroughly poured out, it is set to two feedings through the PLC program control.

The weighing and seasoning machine adopts positive pressure feeding. The weighing instrument is located at the upper part of the silo body and is connected to the interior of the silo. The weighing instrument is located at the lower part of the silo body and is connected to the interior of the silo. The weighing module signals detected by the two pressure-taking weighing instruments are sent to the PLC for display and comparison. Then, by comparing with the set value, an alarm signal is output. By comparing the changes in the differential pressure value, the material level of the silo can be known.

The distributed batching system integrates relay control, computer control and PLC control. As the core component of the control system, the PLC controller processes the input information according to the preset program. Strain transmitters and temperature transmitters collect and adjust the signals from the load cell and temperature sensor, and input them into the PLC controller in real time. The switch signals from the limit switches and the contacts of each primary circuit component are directly input into the PLC.