1. Tool length compensation G43, G44, G49 instructions
The tool length compensation command is generally used for tool axis compensation (Z direction). It makes the actual displacement of the tool in the Z direction increase or decrease by one offset value compared to the program reference value, so that when the tool length in the dimension occurs When changing (if the drill bit is sharpened), the required part size can be machined by changing the offset amount without changing the program.
Instruction format:
G43 Z__ H__
G44 Z__ H__
G49
Instruction function: compensate the length of the tool
Instructions instructions:
(1) G43 command is positive compensation for tool length;
(2) The G44 instruction is a tool length negative compensation;
(3) G49 command cancels tool length compensation;
(4) Tool length compensation refers to the fact that the actual displacement of the tool in the Z direction is increased or decreased by one offset value from the program reference value;
(5) The Z value in the format refers to the instruction value in the program, ie the coordinates of the target point;
(6) H is the tool length compensation code, and the last two digits are the address characters of the tool length compensation register. H01 refers to the No. 01 register in which the offset value of the corresponding tool length is stored.
When G43 and G44 are used, the coordinate of the end point of the Z-axis move instruction specified in the program is calculated with the offset in the memory of the H code instruction regardless of the absolute size or the incremental size instruction programming.
When G43 is executed: Z actual value = Z command value + offset in H__
When G44 is executed: Z actual value = Z command value - offset value in H__
Example: As shown in Figure 1, point A is the starting point of the tool, and the processing route is 1→2→3→4→5→6→7→8→9. It is required that the tool is offset 3 mm downwards from the zero point of the workpiece coordinate system in the Z-axis direction and programmed in increments of coordinates (it is recommended to store the offset 3 mm in the register with the address H01).
Figure 1 Tool length compensation G43, G44, G49 command example
N01 G91 G00 X70 Y45
S800 M03
N02 G43 Z-22 H01
N03 G01 Z-18 F100 M08
N04 G04 X5
N05 G00 Z18
N06 X30 Y-20
N07 G01 Z-33 F100
N08 G00 G49 Z55 M09
N09 X-100 Y-25
N10 M30
2. Tool radius compensation G41, G42 instructions
When machining a workpiece contour A with a cylindrical cutter with a radius R, if the machine tool does not have a tool compensation function, the programmer must program the tool center movement path B with a distance R (R is the tool radius) from the contour A. The operation is sometimes very complicated. When the tool is sharpened, the radius of the tool is reduced. Then the new tool path trajectory must be programmed. Otherwise, the machined part must increase a margin (ie, the amount of tool wear).
Instruction format:
G41 G00 X__ Y__ H (or D)__
G41 G01 X__ Y__ H (or D)__
G42 G00 X__ Y__ H (or D)__
G42 G01 X__ Y__ H (or D)__
Instruction function: The CNC system automatically calculates the tool center trajectory according to the workpiece contour and the tool radius, controls the tool to move along the tool center trajectory, processes the required workpiece contours, and avoids calculating the complex trajectory of the trajectory during programming.
Figure 2 Tool radius compensation position judgment
Instructions instructions:
(1) X__ Y__ represents the coordinate value of the point where the tool moves to the contour of the workpiece;
(2) H (or D)__ is the tool radius compensation register address, and the register stores the tool radius compensation value;
(3) As shown in the left figure of Figure 2, in the direction of tool feed, the center of the tool is on the left side of the part contour, and the left radius of the tool radius is compensated. Use the G41 command;
(4) As shown in the right figure in Figure 2, in the direction of the tool infeed, the tool center is on the right side of the part contour, and the right radius of the tool radius is compensated. Use the G42 command;
(5) Establish tool radius compensation with G00 or G01 motion command.
Example: As shown in Fig. 3, the tool goes from point O to point A. After the tool radius left compensation command G41 is used, the tool will be offset to the left by a radius value during the linear interpolation process and move the tool center to point B. The program segment is:
G41 G01 X50 Y40 F100 H01
Figure 3 Tool radius compensation process
(1) H01 is the tool radius offset code, and the offset amount (tool radius) is registered in advance in the register specified by the H01 instruction.
(2) The tool radius compensation command is used to compensate the tool wear amount and regrind amount by adjusting the tool radius compensation value. As shown in Fig. 4, r1 is the radius of the new tool, and r2 is the radius of the tool after wear.
Figure 4 Tool radius compensation after tool wear
(3) In addition, the tool radius compensation instruction can also be used to perform rough and finish machining on the workpiece with the same tool. As shown in FIG. 5, the tool radius r1 is r+Δ during rough machining, and the tool radius compensation value during finishing is r, where Δ is the finishing allowance.
Figure 5 Tool radius compensation for rough and fine machining
3. Cancel tool radius compensation G40 command
Instruction format:
G00
G40 X__ Y__
G01
Command function: Tool radius compensation canceled
Instructions instructions:
(1) X__Y__ in the instruction indicates that the coordinate value of the tool radius compensation point is canceled in the tool path;
(2) Cancel tool radius compensation by G00 or G01 motion command;
(3) G40 must be paired with G41 or G42.
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