2. Machining center, CNC milling machine tool compensation machining center, CNC milling machine CNC system, tool compensation function includes tool radius compensation, angle compensation and length compensation.
(1) Tool radius compensation (G41, G42, G40) The radius value of the tool is stored in the memory HXX in advance, and XX is the memory number. After the tool radius compensation is executed, the CNC system automatically calculates and automatically compensates the tool according to the calculation result. Tool radius left compensation (G41) refers to the left side of the tool direction of the programmed machining path (as shown in Figure 1), and the tool radius right compensation (G42) refers to the tool to the right of the programmed machining path. Cancel the tool radius compensation with G40, cancel the tool radius compensation and also use H00.
Pay attention to the use: When setting or canceling the tool compensation, the block using G41, G42, G40 command must use G00 or G01 command, G02 or G03 should not be used, when the tool radius compensation takes negative value, the function of G41 and G42 exchange.
The tool radius compensation has two compensation modes: B function and C function. Since the B function tool radius compensation is only calculated according to the program in this section, the transition between the blocks cannot be solved, and the workpiece contour is required to be processed into a rounded transition. Therefore, the workability of the workpiece corner is not good, and the C function tool radius is not good. The compensation can automatically handle the transfer of the tool center trajectory of the two blocks, which can be programmed according to the workpiece contour. Therefore, most CNC CNC machine tools use the C function tool radius compensation. At this time, the following two blocks of the tool radius compensation block are required to have the displacement command (G00, G01, G02, G03, etc.) of the specified compensation plane. Otherwise, the correct tool compensation cannot be established.
(2) Angle compensation (G39) The intersection of the two planes is an angle, which may cause over-cutting and over-cutting, which may cause machining error, which can be solved by the angle compensation (G39). Note that when using the angle compensation (G39) command, this command is non-modal and valid only in the block of the command. It can only be used after the G41 and G42 commands.
(3) Tool length offset (G43, G44, G49) The tool length offset (G43, G44) command can be used to compensate for changes in tool length without changing the program. The compensation amount is stored in the memory of the H code command. G43 indicates that the compensation amount in the memory is added to the end point coordinate value of the program command, G44 indicates the subtraction, and canceling the tool length offset can be performed by the G49 command or the H00 command. In the block N80G43Z56H05 and if, if the value of the 05 memory is 16, it means that the end point coordinate value is 72mm.
The value of the compensation amount in the memory can be pre-stored in the memory by MDI or DPL, or the compensation amount in the memory No. 05 can be 16mm by the block instruction G10P05R16.0.
Third, the calculation of tool path in economical CNC machine tools
For economical CNC machine tools, if there is no tool compensation command, only the motion track size of the tool point can be calculated, and then programmed according to this, or local compensation processing.
1. Calculation of tool center (tool point) trajectory
In the numerical control system that needs to calculate the tool center trajectory, the coordinates of the base point and the node on the tool center corresponding to the base point and the node of the part contour are calculated. Figure 1 shows the tool center motion trajectory when machining a workpiece curve with a φ8 end mill. It can be seen that the tool motion trajectory is an equidistant line of the part contour, which can be obtained from the part contour and the tool radius.
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