Research on CNC Grinding System of Spiral Tooth Cutter (2)
In order to prevent the C-direction measurement overtravel error (since the distance between the tooth and the measuring head is less than one pulse equivalent, the error is less than one pulse equivalent) affects the accuracy of the spiral lead. On the one hand, the step-by-step should be reduced as much as possible. The arc length equivalent δ of the motor per step of the tool. A stepping motor with a small step angle is used, and the δ value can be reduced with a small gear ratio when sharpening a larger diameter tool. Previous page
On the other hand, increasing the Z-direction measurement length also reduces the effect of the C-direction overtravel error on the accuracy of the spiral lead.
5 control system software
The software adopts a modular structure, and the execution of the module depends on the mode switch state on the operation panel. After the main program of the system completes the setting of the I/O port and clears each data storage unit, it enters one of them according to the state of the mode switch. The main working methods are as follows:
(1) Parameter input method. According to the system prompt, input the number of teeth, the direction of the tooth, the length of the feed, the amount of sharpening, the number of feeds, the feed rate, the lower limit of the Z-axis and the C-axis, and the control parameters Z1min and C1min. .
(2) Measurement method. The measurement program flow utilizes the manual functions of the Z-axis and the C-axis to bring the teeth into contact with the measuring head and determine the starting point of the measurement. When measuring, the system determines the axial direction of the tool and the direction of circumferential feed according to the direction of the tooth rotation. When the measured value reaches or exceeds the preset Z1min and C1min, press the C key to turn the cutter to the measuring head. When the two are touched, the Z and C keys are pressed ineffective to avoid artificial overtravel error and damage measurement. The device then completes the calculation and returns to the main program.
(3) Tool setting method. When sharpening the front and rear flank, first turn the wheel frame dial so that the spark at the contact point is in line with the tangential direction of the point. Adjust the tool point in the manual mode. At this time, the system automatically records the tool movement from the starting point to the tool point. The number of steps is Z2, and then the mode switch is the tool setting mode. After starting the tool setting program, the system first takes out the internal recorded parameters Z1, C1 and Z2. According to the calculation, when the tool returns to the starting point, the tool rotates the number of steps C2, and finally (Z2, C2) as the starting point, the linear interpolation, the tool returns. To the starting point of the sharpening (0,0).
(4) Automatic mode. In the automatic sharpening program flow chart, i is the number of times of grinding each tooth; n is the number of teeth.
In the cycle, the teeth are internally looped, and the number of feeds is the outer loop, that is, each feed is once, and all the cutters are sharpened once, so that the cutter teeth are evenly deformed by heat, and the remaining amount of grinding is the same, and the sharpening knife can be guaranteed. The teeth are on the same circumference. When the number of steps is m with a decimal, it is rounded up and the decimal is added to the next step.
6 Conclusion
(1) The use of CNC cycle sharpening can reduce the influence of grinding temperature on the sharpening precision. The sharpening precision will be higher than the manual sharpening and the quality is stable.
(2) After measuring one time, all the teeth of one knife can be sharpened, and the sharpening efficiency and automation degree are high.
(3) Batch sharpening, no need to repeat measurement, just select the same clamping reference, the operation is simple and convenient.
(4) Only applicable to sharpening of unequal helical cutters.