Cast iron material offers high rigidity and heat dissipation, it is the most stable material for manufacturing machine tool structure parts. Not only does it reduce the amount of work involved, but it can also cut complex workpieces such as bumpers, dashboards and headlamp lenses. For any machine tool used for milling large parts, the first requirement is to have a very strong cast iron structure and be equipped with a spindle with heat dissipation function. Here we will discuss several problems you should pay attention to mold processing of cast iron machine tool.
- Proper machine and cutting tools
The spindle of the machine must adopt the built-in cooling technology to cool the spindle from the outside of the bearing, so as to ensure that the spindle itself will not be burnt out or cause a precision loss due to thermal expansion during the long processing. These factors are important because processing large molds takes a long time, and in heavy cutting conditions, this increases the heat and stress in the molds. Therefore, the structural parts of the machine tool must have good rigidity and heat dissipation characteristics, which is the premise of processing a large quality mold. So it is necessary to limit the vibration of machine tools in the process of machining to the greatest extent, and quickly spread the heat generated in the process of machining. Choosing the right machine tools and tools can reduce costs and production cycles.
- Thermal stabilization technology
In the case of long time processing, the influence of environmental temperature must also be considered. Large mold on the machine in normal, for example, that the environment temperature change about 10 ℃ will cause a 6 ℃ change of the machine tool column, leading to the main shaft Angle plate parallel degree change of 0.07 mm. Therefore, the design of machine tools must take into account the effect of environmental temperature to avoid the impact of environmental temperature on the precision of parts.
For a large mold machining center whose stroke can be moved rapidly, the spindle speed of the large mold machining machine should reach at least 20000r/min and the cutting speed of the metal should meet 762 ~ 20000mm/min.
Precision control is always the key in each stage of mold processing. If coarse machining and fine machining of large molds need to be realized on a machining center, then the positioning accuracy and repeated positioning accuracy of the machine must be strictly controlled. For large molds, the positioning accuracy can be up to 1.5 m and repeat positioning accuracy should be up to 1 m. At the same time, the pitch accuracy should be kept within 5μm.
- Feedback resolution
For high precision surface machining, the feedback resolution of the machine tool itself is very important for detecting the precision of machining parts. The standard 1 m feedback resolution is not ideal. If the resolution can reach 0.05 m, the finish is almost ideal. In addition, the machining quality of parts can be further improved by controlling the resolution of the machine tool, ruler feedback and bar pitch ball screw.
(to be continued…)