Abstract
A new technique and an application program for automating the programming of the milling operation during virtual basing of the workpiece on the CNC machine table is presented, when precise installation of the workpiece along the coordinate axes of the machine is difficult. The solution of such a scientific and technical problem allows you to perform contour milling of parts with their arbitrary location on the table of the CNC machine with guaranteed alignment of the allowance along the forming path. The method involves the sequential implementation of three stages with parallel use of the created application program. At the first stage, an electronic copy of the part drawing is prepared, which contains the selected part and workpiece contour highlighted in different colors. Thus, the scanning provides automatic creation of digital two-dimensional arrays of geometric images necessary to solve the problem. At the second stage, the coordinates of three points of the workpiece measured by the probe on the machine are entered into the created program. Based on the entered data, the created program solves the problem of alignment of the allowance using the Gauss-Seidel method using the Hausdorff dimension. This approach allows us to obtain a quantitative estimate of the similarity of polygonal objects, which is necessary to solve the problem of minimax location of the allowance. The task is to determine the correction of the control program for two linear coordinates and one angular around the center of mass of the workpiece. At the third stage, the correction values calculated in the program are entered into the CNC rack of the machine and the processing of the contour begins. The proposed technique and the created application program were tested when processing the part contour on a VF-3 HAAS milling machine. Practical testing has shown the effectiveness of the technique, which is to ensure milling without overloading the tool and reduce the processing time during virtual basing of the workpiece
Highlights
It is known that the program for processing any surface of a part on a CNC machine must be tied to a specific position of the workpiece in the machining zone [1]. This problem is solved in two ways: either the workpiece is installed in a device that is pre-oriented relative to the coordinate axes of the machine, or the workpiece is installed directly on the machine table with the subsequent alignment of its actual position relative to the axis of the machine
To implement the first method, it is necessary to ensure the presence of base surfaces of the workpiece, by which it is installed in the device, and when such conditions are met, binding the control program to the actual position of the workpiece on the machine does not cause difficulties [2]
A new method has been developed for preparing a control program for contour milling, which allows you to bind a control program to the actual position of the workpiece so that the maximum allowance value is as low as possible
Summary
It is known that the program for processing any surface of a part on a CNC machine must be tied to a specific position of the workpiece in the machining zone [1]. In case of accidental installation of the workpiece, to bind its position to the control program, it is necessary to perform numerous measurements of its actual position, usually with a contact probe, which leads to significant loss of time [3, 4] In such cases, a promising technology is that the workpiece is installed on the machine using simple tools, such as tacks, so that it can process its surfaces in one operation, and the control program adapts to its specific position. It is important to ensure the optimal location of the future parts in the body of the workpiece, for uniform distribution of the allowance along the entire path of movement of the tool Known solutions to this problem are associated with considerable difficulties, and it still remains relevant for solving practical problems of mechanical engineering
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