1. NC milling machine tool alignment: assuming the parts are symmetrical, the length of the blank has been measured as L 1, the width as L2, and the diameter of the flat-bottomed end mill has also been measured. After the workpiece is clamped on the milling machine workbench, it is manually operated. The specific steps are as follows:

(1). Manual tool alignment: firstly, make the tool close to the left side of the workpiece (subject to the start of micro-cutting, adopt inching operation). When the tool position is as shown in Figure A, press the set programming zero key, and X0, Y0 and Z0 will be displayed on the CRT, and the programming zero setting in the X direction is completed. Then make the tool close to the front side of the workpiece, keep the tool in the Y direction, and make the tool retreat in the X direction.

When the coordinate value of X on CRT is 0, press the programming zero key to complete the programming zero in X and Y directions. Finally, raise the Z axis and move the tool. Considering the existence of milling cutter radius, when the coordinate value of X is displayed on CRT as (L 1/2+ milling cutter radius) and the coordinate value of Y is (L2/2+ milling cutter radius), make the bottom of milling cutter close to the upper surface of workpiece.

Press the programming zero key, and all the coordinate values of X, Y and Z displayed on the CRT screen will be cleared (i.e. X0, Y0 and Z0), and the system will complete the programming zero function. The cutting point of the milling cutter is set at the symmetrical center of the workpiece, which is the origin of the workpiece coordinate system.

(2) Establish the workpiece coordinate system: at this time, the current position of the cutter (the cutter position of the milling cutter) is at the programming zero point (the workpiece origin). Because the method of manual trial cutting and tool alignment is simple, reliable and economical, it is widely used.

(3) Operation of returning to reference point: Zero point (returning to reference point) is used to return to reference point and establish coordinate system of NC machine tool. At this time, the coordinate values of the current position of the milling cutter center (tool setting reference point) in the coordinate system will be displayed on the CRT.

2, CNC lathe tool alignment. The tool setting method of CNC lathe is basically the same. First, after the workpiece is clamped on the three-jaw chuck, it is manually operated. The specific steps are as follows:

(1), try to cut and align the knife. First, turn the excircle surface of the workpiece with the selected tool, keep the dimension in the X direction unchanged, retract the tool in the Z direction, and program the zero key according to the setting. When the X coordinate value displayed on the CRT is -(D/2), program the zero key according to the setting, and the X and Z coordinate values displayed on the CRT screen will be cleared (i.e. X0, Z0).

(2) Establish the workpiece coordinate system. The current position of the tool tip (the tool position of the turning tool) is at the programming zero point (the workpiece origin).