The cement bag double-head sewing machine is a fully automatic bag sewing equipment. Relying on computer-controlled industrial sewing machines and conveyor belts, it can automatically complete the folding and sewing of the two ends of the woven bags, and can also automatically cut the stitches and stack the bags neatly. Workers only need to put the woven bags one by one on the conveyor belt, and the bag sewing machine will separate the bags according to the set spacing, and simultaneously realize automatic folding and sewing. It is a typical application of efficient industrial sewing machines.
The cement bag double-head hemming machine consists of a feeding conveyor belt, teeth, main conveyor belt, unloading conveyor belt, industrial sewing machine, paper feeder, gas shear, etc.
The feeding conveyor belt runs continuously, and workers place woven bags one by one; the teeth separate the bags according to the preset spacing on the touch screen to ensure sewing operations; the main conveyor belt sends the bags to the sewing machine for sewing, and the unloading conveyor belt outputs the finished products. The industrial sewing machine is responsible for folding and fine sewing, and the paper feeder and gas shear assist in operation.
Its control system is based on a touch screen and PLC, equipped with 4 inverters and tooth solenoid valves, etc. Operators can set key parameters through the touch screen, flexibly adjust the machine, and optimize production efficiency.
This electric control system consists of a touch screen, PLC, 4 1.5KW FRECON FR500A series inverters, tooth solenoid valves, etc. The operator can set parameters such as bag width, spacing, and production line speed through the touch screen. Since the linear speeds of the working transmission mechanisms are the same, the PLC will calculate the target frequencies of each process of feeding, main conveyor belt, left and right sewing machine inverters in real time based on relevant formulas, and adjust the speed with the help of MODBUS communication.
The difficulty of system control lies in the control of the retaining teeth and the main conveyor belt inverter. The PLC timer is required to accurately calculate the retaining teeth action time and control the operation of the main conveyor belt inverter. When the left and right retaining teeth photoelectric signals are blocked by the bag at the same time, the retaining teeth are immediately retracted, and the main conveyor belt inverter runs in advance or delays for a certain period of time, which requires a high response speed of the inverter. In addition, the main conveyor belt is heavily loaded and has a large starting torque. When the system's maximum linear speed is 30m/min, the host inverter reaches 58Hz and the current reaches 110% of the rated value. FR500A inverter meets the requirements with its excellent vector control performance.
The inverter system has the following advantages: the host inverter has a strong overload capacity and can operate for a long time under 110% overload. It has short acceleration and deceleration time and fast response, and can accurately control the bag spacing to improve production speed and efficiency. It adopts external terminal given operation mode, which can accurately control the running time of the main conveyor belt to avoid MODBUS communication interference affecting the bag spacing. It has high speed stabilization accuracy, which can ensure consistent speed of the entire line and prevent the sewing machine needle from being broken. It also has a low failure rate and easy maintenance.
