They are allowed to perform control functions in three coordinate systems at the same time by being equipped with trigger probes. Through the control system, the CNC machining process can be controlled by a certain geometric quantity to improve the automation of the machining center and the machining quality of the machining room. At present, the line probe in the machining center performs relatively simple geometric control tasks, such as point detection, cylinder detection, circular hole detection and so on.
Of course, these tests are necessary. However, from the perspective of the high cost of the online control system, if the online detector only stays in the control stage of these simple geometric quantities, the performance price ratio will reduce the motivation of users to adopt this control method, and it will not promote the long-term development of the online detection system.
After in-depth study of the working characteristics of the on-line measuring touch probes for cnc machines, it can go beyond the original working framework to be applied to more fields. One of the most promising aspects is its application, the detection of free curve.
If it is needed to refer to the geometric features of the shape in the process of product design and molding, it will be necessary to collect the specific information of the shape to provide necessary data for design and product development, that is, the so-called reverse engineering. The on-line probe is used to detect the free curve in the machining center, which makes the on-line control system of the machining center a product modeling tool for computer-aided designers.
At present, the surface modeling function of CAD system basically adopts the modeling method of "point first and surface second". The same is true for solid shape, but it has some special requirements for curve processing. Therefore, from the perspective of CAD modeling, the three-dimensional control method should focus on the detection of curves. Therefore, under the background of surface construction, the central point of CMM is the planning of curve detection path. The detection of free curve is a complex problem, which is mainly reflected in two aspects:
1. Number of sampled points
Generally speaking, the more sampled points, the more accurate the free curve. However, the more the number of sampled points, the greater the deformation probability of the free-form curve. By describing a strong deformation curve, the more the surface can be deformed. In short, increasing the number of sampled points will make the shape of the curve difficult to control.
2. Automatic degree of detection of touch probes for cnc machines
Data acquisition involves a lot of point detection work, which is very difficult to complete by hand. Therefore, it is necessary to envisage a certain automation of point detection. Due to the spatial flexibility of the degree of freedom curve, it is impossible to completely give up human intervention in the detection path planning, otherwise it is easy to transfer the detection path planning. The detection of free curve needs a certain degree of automation and appropriate intervention of operators.