How To Find The Center Coordinates Of The Circle For CNC Machining Center – Provisions On Coordinate Axes of CNC Machine

2022.4.27

How to find the center coordinates of the circle of CNC machining center? How to find the coordinates in CNC machining is one of the problems faced by many newcomers who have just come into contact with CNC machining center. Today we will introduce how to find the center coordinates of a circle on the machining center. We also explain the provisions of the coordinate axis of CNC machine.


How To Find The Center Coordinate Of A Circle In CNC Machining Center

1. Stick the dial indicator on the main shaft and move it to the center of the circle first. Manually rotate the dial indicator around the center of the shaft circle to see how much pressure is on the XY side. Shake it a little in the negative direction of the first wheel, and then manually rotate the main shaft for a circle. Slowly debug it. It is best to know that all three points are in the same position. Of course, all points of the bored hole must be in the same position.

2. Install a drill bit with the tip roughly aligned with the center of the circle. Lift up the z-axis, remove the knife, suck the gauge base on the main shaft (knife edge position), and the dial gauge is against the surface of the workpiece. Then you manually rotate the main shaft and observe the dial gauge. If there is more pressure on the gauge in which direction, you can move the hand wheel to the negative direction and calibrate it slowly.

3. Now there is a coaxiality deviation alignment device. As long as the instrument is clamped on the main shaft, the deviation size between the main shaft axis and the workpiece axis in XY coordinate can be displayed on the display screen by rotating the main shaft for two circles and moving the main shaft once. It is very convenient to shake the main shaft according to the size. It can be done in two or three minutes, with high precision and no technology.

 

Understand The Coordinates Of Machining Center

In CNC programming, in order to describe the motion of the machine tool, simplify the programming method and ensure the interchangeability of recorded data, the coordinate system and motion direction of the CNC machine have been standardized, and the naming standards have been formulated by ISO. The machine coordinate system is a rectangular coordinate system composed of X, y and Z axes, which is established with the machine origin o as the origin of the coordinate system and follows the right-hand Cartesian rectangular coordinate system. Machine tool coordinate system is the basic coordinate system used to determine the workpiece coordinate system. It is the inherent coordinate system on the machine tool and is equipped with a fixed coordinate origin.

 

Provisions On Coordinate Axes Of CNC Machine

When determining the coordinate axis of the machine tool, generally determine the Z axis first, then the X axis and Y axis, and finally other axes. Jb3051-82 standard stipulates that the positive direction of machine tool movement refers to the direction of increasing the distance between workpiece and tool.

 

(1) Z-axis the direction of z-axis is determined by the spindle transmitting cutting force, and the coordinate axis parallel to the spindle axis is the z-axis. If the machine tool has no spindle, the Z axis is perpendicular to the clamping surface of the workpiece. At the same time, the direction of the tool away from the workpiece is specified as the positive direction of the Z axis. For example, in drilling and boring, the direction of drilling and boring the workpiece is the negative direction of Z coordinate, while the exit is the positive direction.

(2) X-axis x-axis is horizontal, parallel to the clamping surface of the workpiece and perpendicular to the z-axis. This is the main coordinate of the movement in the positioning plane of the tool or workpiece. For machine tools with rotating workpiece (such as lathe, grinder, etc.), the direction of X coordinate is in the radial direction of the workpiece and parallel to the transverse sliding seat. The direction of the tool leaving the rotation center of the workpiece is the positive direction of the X axis. For machine tools with rotating tools (milling machine, boring machine, drilling machine, etc.), if the z-axis is vertical, when viewed from the tool spindle to the column, the positive direction of X movement points to the right. If the z-axis is horizontal, the positive direction of the spindle points to the right when viewed from the spindle to the workpiece.

(3) Y axis Y coordinate axis is perpendicular to X and Z coordinate axes. The positive direction of y motion is determined according to the positive direction of X and Z coordinates and the right-hand Cartesian coordinate system.

(4) Rotational motion the motion of rotating around the coordinate axes x, y and Z, represented by a, B and C respectively. Their positive direction is determined by the right-hand spiral law.

(5) If the additional axis has coordinates parallel to them in addition to the X, y and Z coordinates, they can be specified as P, Q and R respectively.

(6) The opposite direction of workpiece movement. For machine with workpiece movement rather than tool movement, the foregoing provisions for tool movement must be arranged in the opposite direction. The letter with “‘”, such as + y’, indicates the forward motion command of the workpiece relative to the tool. The letter without “‘”, such as + y, indicates the negative movement command of the tool relative to the workpiece. They represent the opposite direction of motion.