Open AccessWhen machining the work-pieces a range of scatter of the work-piece dimensions to the tolerance limit is displaced in response to the errors. To improve an accuracy of machining and prevent products from defects it is necessary to diminish the machining error components, i.e. to improve the accuracy of machine tool, tool life, rigidity of the system, accuracy of adjustment. It is also necessary to provide on-machine adjustment after a certain time. However, increasing number of readjustments reduces the performance and high machine and tool requirements lead to a significant increase in the machining cost.
To improve the accuracy and machining rate, various devices of active control (in-process gaging devices), as well as controlled machining through adaptive systems for a technological process control now become widely used. Thus, the accuracy improvement in this case is reached by compensation of a majority of technological errors. The sensors of active control can provide improving the accuracy of processing by one or two quality classes, and simultaneous operation of several machines.
For efficient use of sensors of active control it is necessary to develop the accuracy control methods by means of introducing the appropriate adjustments to solve this problem. Methods based on the moving average, appear to be the most promising for accuracy control, since they contain information on the change in the last several measured values of the parameter under control.
When using the proposed method in calculation, the first three members of the sequence of deviations remain unchanged, therefore 1 1 x x , 2 2 x x , 3 3 x x Then, for each i-th member of the sequence we calculate that way: , ' i i i x x k x , where instead of the i x values will be populated with the corresponding values ' i x calculated as an average of three previous members:
3 ' 1 2 3 i i i i x x x x .
As a criterion for the estimate of the control effectiveness is taken an improving accuracy coefficient
у Т .
Then a mathematical model of the work-piece measurement process was made with available random component of the error and multiple measurements with 100 repeats were taken. And there was a comparison of the correction for the Standard and the proposed method, from which we can conclude the following: when changing a value of the tolerance range, and with displacement of the tolerance range of the constant value, the adjustment proposed in the existing Standard, gives a negative effect in terms of the selected magnification of accuracy, which in the case of changing value of the tolerance range is the best obtained with shifting the tolerance of the constant value, but, as before, remains negative.
At the same time it can be seen that the introduction of adjustments according to the proposed formula, as a whole, has a positive effect, occasionally reaching a zero effect of the adaptive control at magnifications of accuracy Т 1 without making a process worse.