Causes: Under the influence of internal and external heat sources, various components of a gantry milling machine will undergo varying degrees of thermal deformation, disrupting the relative motion between the workpiece and the cutting tool. For gantry milling machines, because the entire machining process is controlled by calculated instructions, the impact of thermal deformation is even more severe.
To reduce thermal deformation, the following measures are typically adopted in the structure of gantry milling machines:
Controlling Temperature Rise: After implementing a series of measures to reduce heat sources, the thermal deformation situation will improve. However, completely eliminating internal and external heat sources in a gantry milling machine is usually very difficult, or even impossible. Therefore, it is necessary to control the temperature rise through good heat dissipation and cooling to reduce the influence of heat sources. One relatively effective method is forced cooling of the heat-generating parts of the gantry milling machine. Alternatively, heating can be used in the low-temperature parts of the gantry milling machine to make the temperature at all points on the machine more uniform, thus reducing warping deformation caused by temperature differences.
Reducing Heat Generation: The main heat sources causing thermal deformation when the gantry milling machine heats up internally should be separated from the main machine as much as possible.
Improvements to the spindle box for gantry milling machines should aim to minimize thermal deformation of the spindle in the direction perpendicular to the tool's entry point. This reduces the impact of spindle thermal deformation on the machining diameter. Structurally, the distance between the spindle center and the ground should be minimized to reduce the total amount of thermal deformation. Simultaneously, the temperature rise at the front and rear of the spindle box should be consistent to prevent spindle tilting after deformation.
Improving the gantry milling machine mechanism also significantly affects thermal deformation under the same heating conditions. For example, the single-column mechanism previously used in gantry milling machines can potentially be replaced by a double-column mechanism. Due to its left-right symmetry, the double-column mechanism experiences minimal deformation in other directions after heating, except for vertical translation. The vertical axial movement can be easily compensated for with a single coordinate correction.
