What is a CNC machine tool?

The machining process of CNC machine tools

Numerical control system to complete a lot of information storage and processing work, and the information processing results in the form of control signals to the subsequent servo motor, the effect of these control signals rely on two core technologies: one is the interpolation of curves and surfaces, one is the machine tool multi-axis motion control.

(3) The shape of the part is too "free"? It's a matter of interpolation

If the motion trajectory can be expressed analytically, the entire motion can be decomposed into a composite motion of several coordinates of independent motion, and the motor can be directly controlled.

However, the shape of many parts in the manufacturing process can be said to be very "Free", neither round nor square, and even do not know what shape, such as automobiles, ships, aircraft, molds, art and other products often encounter Curves and surfaces that cannot be described analytically, which are called Free Form Curves or free surfaces.

 Parts containing free-form surfaces

To cut out these "free" shapes, the relative motion between the tool and the workpiece is correspondingly very complex. Specifically in the operation, it is necessary to control the workpiece table and the tool to move according to the designed position-time curve, and control the two to reach the specified position at the specified time with the specified attitude.

Machine tools can be well between the workpiece and the tool to complete the linear segment, arc or other analytical spline curve relative movement, and this complex "free" movement and how to complete? The answer depends on interpolation.

CNC machine tool for complex surface processing

The so-called interpolation is the process of determining the motion path of the tool on the CNC machine tool according to a certain method. According to the given speed and trajectory, add some new intermediate points between the known points of the trajectory, and control the workpiece table and the tool through these intermediate points, and then the whole movement can be completed.

Between these intermediate points, they are connected by line segments, arcs or splines. It is equivalent to using several small line segments and arcs to approximate the required curves and surfaces, which is the essence of interpolation.

The popular interpolation algorithms include point-by-point comparison method, digital increment method, etc. The interpolation using Nurbs spline curve is favored by high-end CNC machine tools because of its high efficiency and good precision.

(4) The posture of the knife is not correct and can not be processed? Five-coordinate linkage can be done in minutes

Machining complex surfaces not only needs to be machined in theory, but also needs to consider the relative position relationship between the tool and the surface being machined.

On the one hand, if the posture of the tool is not suitable, it will lead to the low quality of the surface of the machining; On the other hand, the tool will also interfere with the structure of the machined parts, and there is no way to process without adjusting the relative posture of the tool. This requires giving more freedom of movement to CNC machine tools to make them more dexterous.