The customers who upgrade hot flying saw to cold flying saw, have this feeling that the cutting precision of tube length is much higher than previous. So that customers no need preserve length for second cutting, for example a 6 meters long tube, can be cut into two pieces with 3 meters length while need 6.2 meters for hot saw cutting into two 3 meters pieces. Why cold flying saw has better cutting precision than hot flying saw? The secret is the difference of control methods between the two.
The cutting length measuring principle for hot flying saw is, converting the pulse signal of the speed encoder into the speed signal. When controller get the speed signals, it will calculate a speed tracking curve according to the position of tube and blade-carriage, and it output analogue signal in order to drive the blade-carriage motor running under certain acceleration to trace the tube. When the speed of carriage achieves the tube running speed, the carriage and tube go in same pace. With this method, the speed of tube, blade-carriage and driving motor should be calculated repeatedly. When the speed of tube is not uniform speed(in real production, the tube speed is not always under uniform speed), the calculation errors appear and motor respond can not adjust to it quickly. So the cutting length is not that precise.
While the cold flying saw controlling system, it doesn't need change the pulse signal into speed signal. It calculates the tube length by counting number of pulse. The drive motor of carriage is on”position” mode, the drive motor take the setting length of tube as a moving cycle, and in this cycle, the carriage and tube move in the same pace, no matter how much of the speed, the carriage always keep the cut-point as target. The cold flying saw is driven by a high-performance servo motor. The response characteristics of the servo motor are several grade higher than that of the DC motor and the AC variable frequency motor. Therefore, the cold cutting saw can achieve higher cutting accuracy.
The video demonstrate the cutting length precision during tube producing. The setting length is 11.7 meters, the machine can guarantee over 95% cutting with tolerance within ±1mm(Marking width is 2mm).
，The secret of cold saw high precision cutting
The cutting length measuring principle for hot flying saw is, converting the pulse signal of the speed encoder into the speed signal. When controller get the speed signals, it will calculate a speed tracking curve according to the position of tube and blade-carriage, and it output analogue signal in order to drive the blade-carriage motor running under certain acceleration to trace the tube. When the speed of carriage achieves the tube running speed, the carriage and tube go in same pace. With this method, the speed of tube, blade-carriage and driving motor should be calculated repeatedly. When the speed of tube is not uniform speed(in real production, the tube speed is not always under uniform speed), the calculation errors appear and motor respond can not adjust to it quickly. So the cutting length is not that precise.
While the cold flying saw controlling system, it doesn't need change the pulse signal into speed signal. It calculates the tube length by counting number of pulse. The drive motor of carriage is on”position” mode, the drive motor take the setting length of tube as a moving cycle, and in this cycle, the carriage and tube move in the same pace, no matter how much of the speed, the carriage always keep the cut-point as target. The cold flying saw is driven by a high-performance servo motor. The response characteristics of the servo motor are several grade higher than that of the DC motor and the AC variable frequency motor. Therefore, the cold cutting saw can achieve higher cutting accuracy.
The video demonstrate the cutting length precision during tube producing. The setting length is 11.7 meters, the machine can guarantee over 95% cutting with tolerance within ±1mm(Marking width is 2mm).
