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Preventive Operation of EDM Machine Tool Thermal Deformation

Mar. 05, 2020

During the development of the automation and precision machining of the on-line cutting process, higher and higher requirements are placed on the machining accuracy and accuracy stability of wire-cut EDM machines. Under the influence of EDM internal and external heat sources, various parts will undergo thermal deformation to varying degrees, which will damage the relative movement relationship between the workpiece and the molybdenum wire and reduce the accuracy of the machine. In general, in order to make the thermal deformation of the machine tool reach a stable value, it takes a lot of time to warm up the machine tool, which directly affects the productivity of the machine tool. For CNC EDM machine tools, because the entire machining size is controlled by pre-programmed instructions, the effect of thermal deformation is even more serious. The High-Speed CNC Machine Tool Supplier will tell you next.

Deformation cause: The main cause of the thermal deformation of the wire cutting machine is the temperature difference between the heat source and each part of the machine. The heat source usually includes chips in processing, running motors, hydraulic systems, friction of transmission parts, and heat radiation from the outside of the machine tool. In addition to heat sources and temperature differences, the inconsistencies in material, structure, shape, and dimensions of machine tool parts are also important factors that cause thermal deformation.

Solution: In order to reduce the thermal deformation of CNC wire cutting machine tools, the following measures should be taken during design.

1. Reduce fever

The internal heat of the Wire Cutting EDM Holes Machine is the main heat source that generates thermal deformation. The heat source should be separated from the host as much as possible. At present, the motors, gearboxes, hydraulics, and fuel tanks of most CNC wire-cutting machine tools have been externally installed. For heat sources that cannot be separated from the host, such as spindle bearings, screw nut pairs, high-speed motion guide pairs, etc., the friction characteristics and lubrication conditions must be improved to reduce heat generation inside the machine.

Wire Cutting EDM Holes Machine

Wire Cutting EDM Holes Machine

2. Controlling temperature rise

After taking a series of measures to reduce the heat source, the situation of thermal deformation will be improved, but it is usually very difficult or even impossible to completely eliminate the internal and external heat sources of the wire cutting machine, so good heat dissipation and cooling must be adopted. To control temperature rise to reduce the impact of heat sources. A more effective method is to perform forced cooling on the hot parts of the machine. At present for multi-axis CNC machine tools, because it requires high accuracy in several directions, it is difficult to use compensation methods to reduce the effect of thermal deformation. For this kind of machine tools, the cooling system for forced cooling of the lubricant can get good results. However, the cooling capacity of the refrigeration system must be appropriate. If the heat absorption capacity is greater than the heating capacity of the internal heat source of the machine tool, the temperature of the machine tool will be lower than the ambient temperature, which will not only cause shrinkage, but also the humid air will condense on the surface of the machine tool and make the machine tool healthy rust.

3. Improve machine structure

Under the same heating conditions, the machine tool structure also has a great impact on thermal deformation. At present, the numerical control wire cutting machine designed based on the principle of thermal symmetry has achieved good results. Therefore, the single-column structure adopted by CNC wire cutting machine tools in the past may be replaced by the double-column structure. Due to the left-right symmetry of the double-column structure, in addition to the vertical axis translation after heating, the deformation in other directions is small, and the vertical axis movement can be easily compensated by a coordinate correction amount.

The above is the prevention of thermal deformation of EDM machine tools introduced by Drilling Machine EDM supplier.

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