The command function removes most of the machining allowance of the bar stock, cutting is performed along the direction of the parallel Z axis, see Figure 1.
Figure 1 Cylindrical roughing cycle
A is the beginning of the cycle and A-A'-B is the finishing route. Instruction Description Δd denotes each cutting depth (radius value), no sign; e indicates the amount of retreat (radius value), no sign; Ns represents the sequence number of the first block of the finishing route; Nf represents the sequence number of the last block of the finishing route; Δu represents the finishing allowance in the X direction, diameter value; Δw represents the finishing allowance in the Z direction. To program using the cycle instructions, first determine the coordinate position of the tool change point, cycle point A, cutting start point A', and cutting end point B. In order to save the auxiliary working time of the CNC machine tool, the G00 quick positioning command is used from the tool change point to the cycle point A. The X coordinate of the cycle point A is outside the blank size, and the Z coordinate value is the same as the Z coordinate value of the cutting start point A'. Secondly, write the G71 command program segment in accordance with the instruction format and machining process requirements of the outer circle rough machining cycle. There are two address characters U in the cycle instruction. The former indicates the back knife quantity and the latter indicates the X machining accuracy. the amount. If there are P and Q address characters in the program segment, then the address character U represents the finishing allowance in the X direction, and vice versa. There is no negative value for back knife. A'→B is the outline of the workpiece, and A→A'→B is the finishing line. During roughing, the tool retracts from point A by Δu /2, Δw, which automatically reserves the finishing allowance. The block between sequence numbers ns to nf describes the path of the cutting tool. Example 1 As shown in Figure 2, programming is performed using the cylindrical roughing cycle instructions. 
Figure 2 Cylindrical roughing cycle application
N010 G50 X150 Z100 N020 G00 X41 Z0 N030 G71 U2 R1 N040 G71 P50 Q120 U0.5 W0.2 F100 N050 G01 X0 Z0 N060 G03 X11 W-5.5 R5.5 N070 G01 W-10 N080 X17 W-10 N090 W-15 N100 G02 X29 W-7.348 R7.5 N110 G01 W-12.652 N120 X41 N130 G70 P50 Q120 F30 2. Face roughing compound cycle (G72) Instruction Format G72 WΔd Re G72 Pns Qnf UΔu WΔw Ff Ss Tt Command Function This command has the same function as G71 except that cutting is performed along the parallel X axis. See Figure 3.Explanation of Instructions The meanings of Δd, e, ns, nf, Δu, and Δw are the same as those of G71.
Figure 3 Roughing cycle
Figure 4 Roughing cycle application
Example 2 As shown in Figure 4, program the end roughing cycle instruction. N010 G50 X150 Z100 N020 G00 X41 Z1 N030 G72 W1 R1 N040 G72 P50 Q80 U0.1 W0.2 F100 N050 G00 X41 Z-31 N060 G01 X20 Z-20 N070 Z-2 N080 X14 Z1 N090 G70 P50 Q80 F30 3. Fixed shape cutting compound cycle (G73) Command format G73 UΔi WΔk Rd G73 Pns Qnf UΔu WΔw Ff Ss TtInstruction function It is suitable for machining a type of workpiece caused by casting and forging. See Figure 5.
Figure 5 Fixed shape cutting compound cycle
Instruction Description Δi indicates the total retracting amount (radius value) in the X-axis; ΔK indicates the total retracting amount in Z axis; d represents the number of cycles; Ns represents the sequence number of the first block of the finishing route; Nf represents the sequence number of the last block of the finishing route; Δu represents the finishing allowance (diameter value) in the X direction; Δw represents the finishing allowance in the Z direction. The characteristics of the fixed shape cutting compound cycle instruction, the tool path is parallel to the contour of the workpiece, so it is suitable for machining the billet formed by casting and forging. The amount of the back knife is obtained by dividing the total retracting amount Δi in the X-axis direction and the total retracting amount ΔK in the Z-axis direction by the cycle number d. The total retracting amount Δi and ΔK are related to the cutting depth of the workpiece. To use a fixed-shape cutting compound cycle command, first determine the coordinate position of the tool change point, cycle point A, cutting start point A', and cutting end point B. Analyze the previous example. Point A is the cycle point, A'→B is the outline of the workpiece, and A→A'→B is the tool's finishing line. During roughing, the tool retracts from point A to point C. The backward distance is Δi + Δu /2, Δk + Δw, the finishing allowance Δu /2 and Δw are automatically left after the rough machining cycle.The block between sequence numbers ns to nf describes the path of the cutting tool.
Figure 6 Fixed shape cutting compound cycle application
Example 3 As shown in Figure 6, programming is performed using a fixed-shape cutting compound cycle instruction. N010 G50 X100 Z100 N020 G00 X50 Z10 N030 G73 U18 W5 R10 N040 G73 P50 Q100 U0.5 W0.5 F100 N050 G01 X0 Z1 N060 G03 X12 W-6 R6 N070 G01 W-10 N080 X20 W-15 N090 W-13 N100 G02 X34 W-7 R7 N110 G70 P50 Q100 F30 4. Finishing compound cycle (G70) Instruction format G70 Pns Qnf After the command function has finished roughing with the G71, G72, and G73 commands, the finishing cycle command can be used to make the tool perform A-A'-B finishing (Fig. 1, Fig. 3, Fig. 5). Instruction Description ns Indicates the sequence number of the first block of the specified finishing route; Nf represents the sequence number of the last block of the specified finishing route; The G70 to G73 cyclic instructions call a block between N (ns) and N (nf), where the subroutine cannot be called in the block. 5. Face drilling compound cycle command (G74) Command Format G74 Re G74 X(U) Z(W) PΔi QΔk RΔd FfThe command function can be used for interrupted cutting. The cutting path is shown in Figure 7. If the X(U) and P and R values ​​are omitted, it can be used for drilling.
Figure 7 End hole drilling compound cycle
Instruction Description e indicates the amount of retreat; X represents the X coordinate value of point B; U represents the incremental coordinate values ​​from A to B; Z represents the Z coordinate value of the C point; W represents incremental coordinate values ​​from A to C; Δi represents the amount of movement in the X-axis direction, no sign; ΔK indicates the amount of movement in the Z-axis direction, no sign; Δd indicates the amount of tool return at the bottom of cutting;F indicates the feed rate.
Example 4 As shown in Figure 8, program the face drilling compound cycle instruction.
Fig. 8 Face drilling combined cycle application
G50 X60 Z40 G00 X0 Z2 G74 R1 G74 Z-12 Q5 F30 S250 G00 X60 Z40 6. Cylindrical Grooving Combined Cycle (G75) Command Format G75 Re G75 X(U) Z(W) PΔi QΔk RΔd FfInstruction function For interrupted cutting of the end face, the cutting path is shown in Fig. 9. If the values ​​of Z(W) and Q and R are omitted, it can be used for interrupted cutting of the outer circular groove.
Figure 9 outer circular groove composite cycle
Instruction Description e indicates the amount of retreat;
X represents the X coordinate value of the C point; U represents the incremental coordinate value from point A to point C; Z represents the Z coordinate value of point B; W represents the incremental coordinate value from point A to point B; The other symbols have the same meaning as G74. If the tool used is a grooving tool, if the tool used is a grooving tool, the tool has two tool tips, and the left tool nose is set as the tool tool location of the tool. Before the programming, the cycle start point of the tool must be set. A and target point D, if the workpiece groove width is greater than the cutting edge width of the grooving knife, the overlapping amount of the cutting edge trajectory should be considered, so that the tool displacement in the Z-axis direction Δk is smaller than the cutting edge width of the grooving tool, and the cutting edge width of the grooving tool The difference between the displacement amount Δk and the tool nose is the overlap amount of the blade path.Example 5, shown in Figure 10, is programmed using a compound circular cycle instruction.
Figure 10 Cyclic grooving cycle application
G50 X60 Z70 G00 X42 Z22 S400 G75 R1 G75 X30 Z10 P3 Q2.9 F30 G00 X60 Z70 7. Thread cutting compound cycle (G76) Instruction Format G76 Pm r a QΔdmin Rd G76 X(U) Z(W) Ri Pk QΔd FfInstruction Function The thread cutting cycle has reasonable technology and high programming efficiency. The thread cutting cycle and feed method are shown in Figure 11.
Fig. 11 Thread cutting combined cycle and feeding method
Instruction Description m indicates the number of finishing repetitions; r represents the number of oblique retract units (0.01 to 9.9f, in units of 0.1f, specified by two digits from 00 to 99); a indicates the tip angle; Δd denotes the first rough cut depth (radius value); Calculation of decreasing depth of cut formula d2 =
Δd; D3 = 
Δd; Dn = 
Δd; Each rough cut depth: Δdn= Δd- 
Δd; Δdmin represents the minimum depth of cut. When the depth of cut Δdn is less than Δdmin, Δdmin is taken as the depth of cut. X represents the X coordinate value of D point; U represents the incremental coordinate value from point A to point D; Z represents the D point Z coordinate value; W represents incremental coordinate values ​​from point C to point D; i represents the difference in the radius of the taper thread; k indicates thread height (X-direction radius value); d represents the finishing allowance; F indicates thread lead. Example 6 As shown in Figure 12, using the thread cutting compound cycle instruction programming (the number of finishing is 1 time, the oblique retracting amount is 4mm, the tool tip is 60°, the minimum cutting depth is 0.1mm, and the finishing allowance is 0.1 Mm, thread height 2.4 mm, first cut depth 0.7 mm, pitch 4 mm, thread diameter 33.8 mm).
Figure 12 Application of thread cutting compound cycle
G00 X60 Z10 G76 P011060 Q0.1 R0.1 G76 X33.8 Z-60 R0 P2.4 Q0.7 F4Soft, odorless, tasteless white powder with strong hiding and coloring power, melting point 1560 ~ 1580℃. Insoluble in water, dilute inorganic acid, organic solvent, oil, slightly soluble in alkali, soluble in concentrated sulfuric acid. It turns yellow when heated and white when cooled. Rutile type (R type) has a density of 4.26g/cm3 and a refractive index of 2.72. R titanium dioxide has the characteristics of good weather resistance, water resistance and not yellowing, but the whiteness is slightly worse. Anatase type (type A) has a density of 3.84g/cm3 and a refractive index of 2.55. Type A titanium dioxide has poor light resistance and is not resistant to weathering, but its whiteness is better. In recent years, it has been found that nano-scale ultrafine titanium dioxide (usually 10 ~ 50 nm) has semiconductor properties, high stability, high transparency, high activity and high dispersion, and no toxicity and color effect.
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