Views: 2 Author: Site Editor Publish Time: 2022-04-01 Origin: Site
Tool alignment is the main operation and important skill in NC machining. Under certain conditions, the precision of the tool can determine the machining precision of the parts, at the same time, the tool efficiency also directly affects the CNC machining efficiency. Just know the knife method is not enough, but also know the CNC system of all kinds of knife Settings, as well as these methods in the processing program to call the method, at the same time to know the advantages and disadvantages of a variety of knife, use conditions.
The purpose of the tool is to establish the workpiece coordinate system. Intuitively speaking, the tool is to establish the position of the workpiece in the machine tool workbench. In fact, it is to find the coordinate of the tool point in the machine tool coordinate system. For CNC lathes, before processing, the first choice of tool point, tool point refers to the workpiece processing with CNC machine tools, the starting point of the tool relative to the workpiece movement. The knife point can be located on the workpiece (such as the design datum or positioning datum on the workpiece), also can be located in the fixture or machine tool, if located in a point on the fixture or machine tool, the point must maintain a certain accuracy of the size relationship with the positioning datum of the workpiece. When the knife, should make the point of the knife and the knife point overlap, the so-called knife point refers to the positioning reference point of the tool, for turning tool, the knife point is the tip. The purpose of tool is to determine the absolute coordinate value of tool point (or workpiece origin) in the machine tool coordinate system, and measure the deviation value of tool position. The accuracy of tool point alignment directly affects the machining accuracy. In the actual processing of the workpiece, the use of a tool generally can not meet the processing requirements of the workpiece, usually use more than one tool for processing. In the use of multiple turning tool processing, in the case of changing the tool position unchanged, the geometric position of the tool point after changing the tool will be different, which requires different tools at different starting positions to start processing, can ensure the normal operation of the program. In order to solve this problem, the machine tool numerical control system is equipped with cutting tool geometric position compensation function, the use of cutting tool geometry position compensation function, as long as each knife in advance relative to a selected benchmark cutter location deviation measured in advance, the input to the numerical control system of cutting tool parameters corrected column specified in the group number, using T instruction in the process, The tool position deviation can be automatically compensated in the tool path. Tool position deviation is also measured by tool alignment.
In numerical control machining, the basic method of knife trial cutting method, tool instrument tool and automatic tool. Taking nc milling machine as an example, this paper introduces several common tool alignment methods.
Test cutting method.
This method is simple and convenient, but will leave cutting marks on the workpiece surface, and the tool accuracy is low. Taking the cutter point in the center of the workpiece surface as an example, bilateral cutter setting method is adopted.
X, y to the knife.
The workpiece is installed on the workbench through the fixture. When clamping, the four sides of the workpiece should be set aside for the position of the knife.
Start the spindle medium-speed rotation, quickly move the table and spindle, so that the tool quickly move to a safe distance near the left side of the workpiece, and then reduce the speed to move close to the left side of the workpiece.
When close to the workpiece, use fine-tuning operation to close to the workpiece, so that the tool slowly close to the left side of the workpiece, so that the tool just contact the left surface of the workpiece, and then back 0.01mm. Write down the coordinate values displayed in the machine tool coordinate system at this time.
Back along the z direction, to the workpiece surface above, with the same approach to the right side of the workpiece, write down the coordinate value displayed in the machine tool coordinate system.
The coordinate value of the origin of the workpiece coordinate system in the machine tool coordinate system can be obtained.
Similarly, the coordinate value of the origin of the workpiece coordinate system in the machine tool coordinate system can be measured.
Z to the knife.
Move the tool quickly to the top of the workpiece.
Start the spindle medium-speed rotation, quickly move the table and spindle, so that the tool quickly move to a position close to the workpiece surface has a certain safe distance, and then reduce the speed to move the tool end face close to the workpiece surface.
Near the artifacts to fine-tune operation to close, let the tool face slowly close to the surface (note tool especially when vertical milling cutter is best on the edge of the workpiece under the knife, knife face contact surface area is less than half round, try not to make vertical milling cutter center hole in the workpiece surface under the knife), the tool face is bumping on the surface of workpiece, the shaft to raise again, Write down the z value in the machine coordinate system at this time
Input the measured X, Y and Z values into the storage address G5* of the workpiece coordinate system of the machine tool (G54 ~ G59 codes are generally used to store tool setting parameters).
Enter panel input mode (MDI), enter "G5*", press the start button (in automatic mode), and run G5* to make it take effect. (5) Check whether the knife is correct.