Tool compensation in CNC machining

First, the tool compensation proposed:

Using an end mill to machine a workpiece on a CNC machine tool, it can be clearly seen that the tool center movement gauge does not coincide with the contour of the workpiece. This is because the workpiece contour is formed by the movement envelope of the end mill. The center of the end mill is called the cutter location (4, 5 coordinate CNC machine tool is called cutter location vector), and the movement track of the cutter location represents the tool's trajectory. In CNC Machining,programs are programmed according to the contour size of the workpiece or programmed according to the trajectory dimension of the tool location. This should be handled according to the specific situation.

CNC machine tool end mill processing

In the full-function CNC machine tool, the CNC system has tool compensation function, which can be programmed according to the workpiece contour size. After the tool compensation is established and executed, the CNC system automatically calculates and the tool position is automatically adjusted to the tool movement path. By directly using the workpiece size to compile the machining program, the tool wears, and the replacement machining program does not change. Therefore, the use is simple and convenient.

Economical CNC machine tools are simple in structure, low in price, and have a certain amount of ownership in production enterprises. In the economical CNC machine tool system, if there is no tool compensation function, the machining program can only be programmed according to the trajectory size of the tool location. This requires that the trajectory size of the tool location should be calculated based on the workpiece contour size and tool diameter. Therefore, the calculation volume is large and complex, and the tool wear and replacement need to recalculate the trajectory size of the tool location and reprogram the machining program.

Second, the tool compensation in the full-function CNC machine tool system:

1. CNC lathe tool compensation

The CNC lathe tool compensation includes tool position compensation and tool arc radius compensation. In the machining program, it is specified by T function. The first two XX in T***X are the tool number, and the last two XX are the tool compensation number, such as T0202. If the tool offset number is 00, tool offset is canceled.

(1) Tool position compensation Tool wear or tool position change caused by reinstallation of the tool. After the tool position compensation is established and executed, the machining program does not need to be reprogrammed. The method is to measure the position of each tool and input it into the specified memory. After the program executes the tool compensation command, the actual position of the tool replaces the original position.

If there is no tool compensation, the tool moves from 0 to 1 point. The corresponding block is N60G00C45X93T0200. If the tool compensation is X=3 and Z=4, it will be stored in the corresponding compensation memory. After the tool compensation is executed, the tool will be from 0 point. Move to 2 instead of 1 and the corresponding block is N60G00X45Z93T0202.

(2) Tool arc radius compensation When programming a CNC lathe, the tool nose is regarded as a point (imaginary point P), but in fact, in order to improve the tool life and reduce the surface roughness of the workpiece, the vehicle The tip of the knife is ground to a radius with a small radius (blade tip AB arc), which inevitably results in a shape error of the machined workpiece. On the other hand, the position of the tool nose arc, the shape of the turning tool will also have an impact on the workpiece processing, and these can be solved by tool arc radius compensation. The shape and position parameters of the turning tool are called the tool nose orientation and are represented by parameters 0 to 9. P point is the theoretical tool tip point.

(3) Tool offset parameters Each tool offset number corresponds to 4 parameters of tool position compensation (X and Z values) and tool arc radius compensation (R and T values), and is input to the corresponding memory before machining and displayed on the CRT. . In the automatic execution process, the numerical control system automatically corrects the position error of the tool and automatically performs the tool nose arc radius compensation according to the values of X, Z, R, and T in the memory.