First, the basic coordinate relationship

Generally speaking, there are two coordinate systems commonly used: one is the mechanical coordinate system; the other is the workpiece coordinate system, also called the programme coordinate system. In the mechanical coordinate system of the machine tool has a fixed reference point (assumed to be (X, Z). The role of this reference point is mainly used to give the machine itself a positioning. Because every time the machine is switched on, no matter what position the tool holder stays in, the system sets the current position to (0, 0), which will inevitably result in the non-uniformity of the reference, so the first step of the operation every time the machine is switched on for the return of the reference point (some call it back to zero), that is, by determining the (X, Z) to determine the origin (0, 0). For the convenience of calculation and programming, we usually set the program origin on the rotary centre of the right end face of the workpiece, and try to make the programming datum coincide with the design and assembly datum. The mechanical coordinate system is the only datum for the machine tool, so it is important to figure out where the program origin is located in the mechanical coordinate system. This is usually done in the next tool setting process.

Second, the method of tool aligning

Test cut method of knife test cut method of knife is the actual application of one of the most common method of tool setting. The following GSK CNC system lathe as an example, to introduce the specific operation method.

Workpiece and tool clamping is completed, drive the spindle rotation, move the tool holder to the workpiece to test cut a section of the outer circle. Then keep the X coordinate unchanged to move the Z-axis tool away from the workpiece, measure the diameter of the segment of the outer circle. Input it into the corresponding tool parameters in the tool length, the system will automatically use the tool's current X coordinate minus the diameter of the section of the outer diameter of the test cut, that is, to get the position of the workpiece coordinate system X origin. Then move the tool to cut the end face of the workpiece, enter Z0 in the corresponding tool parameters in the tool width, the system will automatically subtract the tool's Z coordinates just entered, that is, the location of the Z origin of the workpiece coordinate system.

For example, the outer diameter of X measured by 2# tool holder is Φ50.78mm; then input "X50.78 Measurement" for X-axis tool setting. The tool at the end face is 0, then the programmed origin Z value when cutting with this tool is 0.0. Deposit (50.78,0.0) into the X and Z of the 2# tool parameter tool length respectively, and use T0202 in the programme to successfully establish the workpiece coordinate system. In fact, to find the workpiece origin in the mechanical coordinate system is not to find the actual position of the point, but to find the tip of the point to reach (0, 0) when the position of the tool holder. Using this method of tool setting generally does not use a standard tool, and all of the tools to be used need to be set up before machining.