A numerical control system in the offline <br> <br> interpolated numerical control system, the conventional method must first be interpolated offline modeling geometric modeling system, based on this, the input processing information by manual interaction mode, The relevant tool location file is generated by offline mode, and then the code sequence of the specific machine tool is generated by post-processing. It can be seen from this that this offline mode not only has many links, but also consumes a large amount of labor and machine time, and occupies more hardware and software resources. Moreover, due to the separation of the tool path planning and the trajectory, it is difficult to achieve three-dimensional real-time accurate compensation of the tool size. Processing and programming need to be performed multiple times, extending processing time. At the same time, the process needs to encode, decode, transmit, store and process a large amount of data, which greatly increases the probability of error and adversely affects the reliability of the numerical control. Next page
In order to avoid the inherent deficiencies of offline programming, a technique of real-time interpolation is proposed, that is, the numerical control system generates a non-interfering tool path trajectory and a control command for generating tool motion in real time according to the information about the surface to be machined, thereby realizing the machining process. control. However, this method requires high interpolation technology, that is, the interpolation algorithm is required to be efficient. Because real-time interpolation is implemented, the interpolation system must calculate the coordinates of the next interpolation point in the interpolation period, and perform interference. Processing of related art. Therefore, many CNC machines can only directly interpolate straight lines and arcs, and they cannot interpolate the surfaces in real time. In order to improve the above situation, we carefully studied the related technology of NC machining and real-time surface interpolation, and proposed a real-time interpolation algorithm for parametric surfaces. The algorithm has unique ideas, which greatly shortens the time of real-time interpolation of parametric surfaces and significantly improves the time. The real-time interpolation efficiency makes real-time interpolation of free-form surfaces possible.
Second, the basic principle of interpolation
The interpolation methods of the current CNC machining system are mainly divided into two categories: one is pulse incremental interpolation, that is, the stroke scalar interpolation: the other is data sampling interpolation, that is, time scalar interpolation. Pulse incremental interpolation is used as the interpolation unit for the interpolation of the stepper in each pulse time. This method is mainly used in open-loop CNC systems for interpolation of linear and circular arcs, interpolation. The speed is generally slower. The data sampling interpolation is interpolated by the distance the tool travels in an interpolation cycle. This method can be used for interpolation of more complex curves and can realize fast interpolation. Considering the inherent shortcomings of pulse delta interpolation, this paper uses the data sampling method for interpolation. The principle of the method is to first calculate the feed amount of the tool in the direction of the combined speed in an interpolation cycle according to the feed speed and the interpolation period, and then pass the difference between the measured value and the theoretical value in real time during the actual interpolation. The servo mechanism controls each motion axis for interpolation.
Third, the curved surface parameters in real-time interpolation surfaces <br> <br> proposed real-time interpolation method using the section plane. The method is divided into three parts. Firstly, the surface to be processed is discretized, then a set of parallel faces is intercepted, the intercept line is obtained, and the initial interpolation points are obtained. Finally, the initial interpolation points are subjected to interference processing to generate a tool path trajectory.