Is it necessary to preheat the vertical machining center every morning?

1. Why do we need to preheat the vertical machining center?

The thermal characteristics of CNC vertical machining center have an important influence on machining accuracy, accounting for almost half of the machining accuracy. The guide rails, lead screws and other components used in the machine tool spindle and XYZ moving axis will heat up and deform due to load and friction during movement, but the displacement of the spindle and XYZ moving axis components relative to the worktable will eventually affect the machining accuracy in the thermal deformation error chain.

The machining accuracy of vertical machining center machines that have been stopped for a long time and thermally balanced machines is very different. The reason is that the temperature of the spindle and moving axis of CNC machine tools remains at a relatively fixed level after running for a period of time. As the processing time changes, the thermal accuracy of CNC machine tools tends to be stable, indicating that it is very necessary to preheat the spindle and moving parts before processing.

However, many factories ignore or do not know the preparation of the machine tool "warm-up exercise".

2. How to preheat the vertical machining center?

If the vertical machining center is left idle for more than a few days, it is recommended to preheat for more than 30 minutes before high-precision machining; if the static condition is only a few hours, it is recommended to preheat for 5-10 minutes before high-precision machining.

The preheating process is to allow the vertical machining center to participate in the repeated movement of the machining axis. It is best to perform multi-axis linkage, such as moving the XYZ axis from the lower left corner of the coordinate system to the upper right corner, and repeatedly walking diagonally.

When executing, a macro program can be written on the vertical machining center so that the vertical machining center can perform preheating actions repeatedly. For example, when a CNC machine tool stops running for a long time or before processing high-precision parts, according to the mathematical three-dimensional elliptical parameter curve and the spatial range of the machine tool after preheating, T is used as the independent variable, the coordinates of the three motion axes of XYZ are used as parameter variables, and a certain incremental step size is used to specify the maximum range of the XYZ motion axis as the boundary condition of the parameter curve. The spindle speed and the feed speed of the XYZ motion axis are associated with the independent variable T, and are allowed to change continuously within the specified range. An identifiable CNC program for the CNC machine tool is generated to drive the various motion axes of the machine tool to produce synchronous no-load motion, accompanied by control changes in the spindle speed and feed speed during the motion process.