1. Decision on cutter point and cutter point
For CNC machine tools, it is very important to determine the relative position of the tool and the workpiece at the beginning of processing, This is the "to tool point" executed for the tool point, which refers to the reference point that determines the position of the tool relative to the workpiece through the tool setting. During the programming process, whether the tool actually moves relative to the workpiece or the workpiece moves relative to the tool, the workpiece is considered to be stationary, and the tool is also moving. The tool point is also the origin of the part processing.
The selection principle of tool point is as follows:
(1) It is convenient for mathematical processing and simplifies programming.
(2) It is easy to find the position to determine the machining origin of the part on the machine tool;
(3) The inspection is convenient during processing.
(4) The resulting processing error is small.
You can set a tool point example on a part, fixture or machine tool, but it must have a known precise relationship with the position datum of the part. If the accuracy of the tool is very high, the tool point should be selected as much as possible in the design or technical basis of the part. For parts placed as holes, the center of the hole can be used as a pair of tool points
If facing the tool, the tool point must match the position of the tool. The tool position is the reference point for determining the tool position. For example, if the machining position of the flat milling cutter is the center of the normal plane. The turning tool of ball-end milling cutter is spherical center. The drill bit is the tip of the drill bit.
The replacement point must be configured according to the process content, and the principle of workpiece, fixture and machine tool should not be followed when replacing tools. The tool point is always a fixed point, located away from the workpiece.
2. Tool setting method
Because the tool accuracy directly affects the machining accuracy, the tool movement must be careful, and the tool method must meet the requirements of the part machining accuracy.
If the machining accuracy of the part is high, the dial indicator can be used to find the correct tool path. The position of the tool is consistent with the tool point. However, this method is not efficient.
At present, some factories have adopted new methods such as optics and electronic instruments in order to reduce working hours and improve accuracy.