CNC machining programming - Solutions - Huaqiang Electronic Network

Programmable Package SG-8018CA(SG7050C) 0.67M~170M

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First, CNC milling processing program preparation

Example: Milling grooved cam, the center line of the curve groove is R95(O ₃ )R90(O ₂ ) R150(O ₁ ) R72(O ₅ ) R92(O ₄ ) R69(O ₁ ) arc, and two straight lines AB GH composition, each adjacent line segment is tangent.

Process: the route of the knife ----- each line segment in turn processing, EFGHABCDE.

Cutting: cutting in the tangential direction of the starting point of the machining of the curve; for the milling groove, it cannot be directly milled to the groove depth dimension as the drilling depth in the groove depth direction, but is milled back and forth to the groove depth while the axial feeding edge.

Cut out: When a contour is finished, you cannot retract directly at the end point, but cut a distance along the tangent direction of the end point.

When the groove width has precision requirements, the outer wall and the inner wall of the machining groove are respectively corrected by the tool radius compensation command, and the dimensional accuracy of the groove width is ensured by selecting the compensation amount.

Programming size calculation: It is necessary to calculate the coordinates of the intersection or tangent point of adjacent line segments, also called base point coordinate calculation. The calculation accuracy is generally rounded to the minimum displacement increment. For non-circular curves and list curves, mathematical processing of curve fitting and approximation is also performed, and the intersection or tangent coordinates of adjacent approximation line segments are calculated, which is called node calculation.

The coordinates of the intersections in the example are calculated as follows:

A (37.601, 57.855) B (79.550, 87.463) C (102.740, 89.511) D (148.525, 20.984)

E (149.997, 0.974) F (122.565, -56.043) G (54.839, -75.443) H (-7.539, -68.589)

Programming with FANUC 3MC CNC system instructions:

N 001 G 92 X0 Y0 Z 1000000 M 03 coordinate system setting

N 002 G 17 G 90 G 00 X150000 Y-15000 S600

N 003 G 19 G 01 Z 30000 F 2000 M 08

N004 Z 0 F 200

N005 Y15000 Z-3000 axial feed

N006 Y-15000 Z-8000

N007 Y15000 Z-15000 to the depth of the slot

N 008 G 17 G 01 G 42 X149.997 Y947 H21 Cuts tangentially to point E to establish tool compensation. Processing the inner wall.

N 009 G 02 X1225656 Y–56043 R72 E--F

N010 X54839 Y-75443 R 93 F --G

N 011 G 01 G 42 X-75939 Y-68589 H 22 G --H

N 012 G 02 X- 37601 Y57855 R69 H--A

N 013 G 01 G 42 X79550 Y87463 H 23 A --B

N 014 G 02 X102740 Y89511 B--C

N015 X148525 Y 20984 C --D

N016 X149997 Y947 D--E

N 017 G 01 G 40 Y-15000 Cut out tangentially and remove the tool.

N018 Y20000

N 019 G 41 Y974 H21 Cuts tangentially to point E to establish tool compensation. Processing the outer wall.

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N 030 G 17 X0 Y 0 M 02

Second, the preparation of CNC drilling and tapping procedures

Drill collar tapping is a point-controlled process with two actions per machining position. Fast positioning of the XY plane (G00) and Z-axis feed machining. The machining action of each Z axis is composed of several fixed sub-actions, called the work cycle. Such as

Drilling: Feed quickly retreat from N--- GO1 Z- F-- N--- GOO Z---

Tapping: Feed Suspension - Spindle Reverse Reverse Feed N-G01 Z-F-M03 N-G 04 M 05 N—G01 Z—M04

If programmed as usual, the Z-axis action requires several blocks to complete. For the fixed cycle action of the Z axis, the numerical control system has the corresponding specified cycle function command to achieve. This is just a program segment.

Take the FANUC OMC system as an example:

Drilling: G 98 G 81 Z— R— F—

Tapping: G 98 G 84 Z— R— F—

The canned cycle instruction has a renewed effect (modal command). That is, once used, as long as a G00 is executed, a fixed cycle process is automatically executed. Until it is cancelled by the G80, or replaced by other fixed cycles.

The fixed-loop instruction greatly facilitates programming, and it must be well mastered and used by programmers. It is worth noting that the fixed cycle command is unique to the CNC system. Different CNC systems, fixed cycle G commands, implemented functions and writing formats are different. Therefore, the use of fixed cycle commands must carefully read the programming instructions of the CNC system. . Use it correctly according to the regulations and requirements in the manual.

Third, CNC turning machining program preparation

The coordinate system of CNC turning is: Z in the longitudinal direction and X in the radial direction.

Programming with absolute values: X dimension values ​​are expressed in diameter; programmed with incremental values: X dimension values ​​are expressed as two times the displacement value.

The absolute coordinate system is set to G50.

Or X, Z for absolute coordinate programming, U, W for incremental coordinate programming.

Due to the common bar stocks and forgings for turning blanks, the machining allowance is large. Therefore, CNC lathes often have different forms of fixed cycle commands for finishing the cutting allowance. Fixed cycle commands and functions of the FANUC OTC system.

Example: Forming turning fixed cycle G73

Used for roughing of forgings. Usually, the shape of the forging is similar to that of the part, so when roughing, the trajectory of the tool is parallel to the contour of the part. Therefore, G73 is written in two blocks, which are expressed as:

G73 U(Δi) W(Δk) R(d)

G73 P(ns) Q(nf) U(ΔU) W(ΔW) F(f) S(s) t(t)

Δi—X direction roughing allowance (radius value), Δk—Z direction roughing allowance, d—roughing is completed several times, so the first block explains the roughing allowance and the number of cuttings.

Ns—the sequence number of the block that starts the loop, nf—the sequence number of the block that ends the loop, and ns---nf is the finishing block of the contour of the part corresponding to the formed turning fixed cycle. ΔU---the margin for finishing in the X direction, and the finishing allowance in the ΔW-Z direction. F—feed speed, s—spindle speed, t—tool number.