CNC machining center
CNC programming is an important step in CNC machining. NC programming is generally divided into manual programming and automatic programming. Manual programming is mainly used for some parts with simple processing shape, small amount of calculation and few procedures. Therefore, manual programming is mainly used in point processing or contour processing consisting of straight lines and circular arcs. For parts with complex shapes, especially parts with non-circular curves, list curves, and curved surfaces, automatic programming is often used.
The machining center often needs to process some porous parts, especially the holes with a large number of holes and each hole must be processed by several processes, for example, processing the dot group holes on the plate parts. The SIEMENS CNC system has fixed-loop machining instructions for linear holes and annular holes, but there are no linear holes and annular holes for fixed-cycle machining instructions on some older CNC systems such as FANUC and China Middle Ages. There must be no set of user macro programs. Macro programs and macros are more difficult to understand concepts and instructions, so most people in programming do not want or want to use macro programs. At the same time subject to the constraints of objective conditions, automatic programming (computer programming) has not yet been popularized. Therefore, when programming a porous part machining program, if the conventional programming, you need to calculate the coordinate value of each node, not only the calculation volume is large, the grouping speed is slow, the program is lengthy, and it is extremely easy to make mistakes. If we can flexibly use the auxiliary programming function in the CNC system to program, the programming of the group hole machining will become simple, clear, and the programming time will be short. The following is a programming example for using a subroutine and a drilling canned cycle to perform mesh dot matrix processing.
Example: In the VMC750E China Middle Ages HNC-21M machining center, 100 φ6mm linear matrix array holes are machined on a 12mm thick workpiece (as shown in Fig. 1), and the starting point of the tool is (12, 0, 80). The process analysis is as follows:
1. Tool and reasonable cutting amount (see the attached table for details) 
Schedule
CNC machine tools
2. Programming (1) The processing route is shown in Figure 2.
(2) Processing procedures
%0086; main program number
N02 T1 M06; T1 is A2.5 center drill
N04 G90 G54 GOO X12 Y0 M03 S1200; Tool idling to knife point
N06 G43 H01 Z30 M07; Tool length compensation, cutting fluid
N08 M98 P6000 F60 Z5 L5; Call drill subroutine 5 times
N10 C49 G80 G90 G00 Z80 M09; Cancel length compensation and canned cycles
N12 T2 M06; T2 is φ6 twist drill
N14 G90 G54 G00 X12 Y0 S600 M03; Tool quickly moves to cutter
N16 G43 H02 MZ30 M08; Tool length compensation, open cutting fluid
N18 M98 P6000 F120 Z16 L5; Call drill subroutine 5 times
N20 G49 G80 G90 G00 Z80 M09; Cancel length compensation and canned cycles
N22 T3 M06; T3 is a 45o chamfer cutter
N24 G90 G54 G00 X12 Y0 S600 M03; Tool quickly moves to cutter
N26 M98 P6000 F50 P1 Z0.3 L5; Call drill subroutine 5 times
N28 G49 G80 G90 G00 Z80 M09; Cancellation of K-degree compensation and canned cycles
N30 G00 X-100 Y0 M05; Spindle stop
N32 M30; The program ends and returns to the beginning of the program
%
%6000; program number
N10 G99 G81 G91 Y12 G90 Z[- #25] R3 F150 P[#15];
Call the canned cycle (1) hole
N15 G91 X12 Y0 L9; Drill holes in holes (2) to (10)
N20 X0 Y12; Drilled in hole (11)
N25 X-12 Y0 LO; Drill holes in holes (12) to (20)
N30 M99; Subroutine ends and returns to main program
%
In the HNC-21M numerical control system, the subroutine is used to process the linear matrix hole. This method has been successfully used in the actual processing. It has the advantages of fast programming, clear program liquid, and saving CNC memory. And as long as the matrix hole row number, the number of columns, and hole spacing and starting point size parameters as a variable on the subroutine call instruction after the programming, the subroutine is fixedly stored in the system memory, it has a certain Versatility; Therefore, we can also use subroutines to program circular hole clusters.
