The basic principle for determining the three elements is: first determine the rear draft according to the cutting requirements, then look up the table to get the feed, and then calculate the main cutting speed through the formula. In many cases, we can use empirical data to determine the values of these three elements.
Selection method: Practice has proved that a reasonable selection of cutting parameters is related to many factors such as machine tools, tools, workpieces, and craftsmanship. The reasonable selection of processing volume is as follows:
1. In rough machining, high production efficiency is the main factor, so you should choose a large amount of back knife, a large amount of feed and low-to-medium cutting speed.
2. When finishing, the size and surface accuracy of the main parts are required, so choose a smaller back cut, a smaller feed rate and a higher cutting speed.
3. In rough machining, the potential of the machine tool and the cutting ability of the tool should be fully utilized. In the semi-finishing and finishing processes, how to improve the processing quality and productivity is an issue worthy of attention. When selecting the cutting parameters, the CNC turning factory should ensure that the tool can complete the processing of a part, or that the durability of the tool is not less than one work shift, or not less than half a work shift. The specific numerical value of the CNC lathe factory should be selected according to the provisions of the machine tool manual, tool durability and actual experience. Selection of the amount of back-cutting: The selection of the amount of back-cutting should be determined according to the rigidity of the machine tool, fixture, workpiece and the power of the machine tool. If the process system allows, choose a larger back cut as much as possible. Except for the allowance left for subsequent processes, the remaining rough machining allowance should be cut once as much as possible to reduce the number of cuts.
Generally on medium-sized power machine tools, the draft after roughing is 8-10 mm (single side). The amount of semi-finishing back knife of CNC lathe factory is 0.5-5mm, and the amount of back knife after finishing is 0.2-1.5mm. The determination of the feed rate: When the quality requirements of the workpiece are met, a higher feed rate can be selected to improve productivity. When CNC turning deep holes or fine turning, a lower feed rate should be selected. The feed speed should be suitable for the spindle speed and rear draught. In rough machining, the choice of feed is limited by the cutting force.
Discuss what are the factors that affect the machining accuracy of the turning-milling compound mach