Typical parts process analysis examples in CNC milling
Write the processing technology of the part shown in the figure.
(1) Analysis of the part drawing
As shown in the figure, the outer contour of the support part is composed of straight lines and arcs, and the others are mainly circular holes. Among them, the inner hole Φ40H7 has higher dimensional processing accuracy and surface roughness requirements.
Part material: HT200 (good cutting performance)
Blank size: 170mm×110mm
×45mm
(2) Part clamping and fixture selection
Use the milling machine vise to clamp the two sides of the blank and process the lower surface; after turning over, use the lower surface to position the milling machine vise to clamp the two sides of the blank, process the upper surface, step surface, drill holes and boring holes; use the "one face and two holes" positioning method, that is, use the bottom surface and the two holes Φ40H7 and Φ13 as the positioning reference for clamping and processing the outer contour.
(3) Determination of processing plan and processing sequence
Establish the workpiece coordinate system with the upper end face of the inner hole of the part Φ40 as the coordinate origin.
The processing sequence is determined according to the principle of base surface first, roughing first and finishing later.
The processing sequence is: milling the lower surface → turning over and flattening and then milling the upper surface → milling the Φ60 outer circle and its step surface → drilling 3 φ5 center holes → drilling φ38 inner holes → rough and fine boring φ40 inner holes → drilling 2×Φ13 holes → countersinking 2×Φ22 holes → milling the outer contour. (The tooling sequence is shown in the table).
(4) Selecting tools
Φ40H7 inner holes are drilled and bored, stepped holes Φ12 and Φ22 are drilled and countersunk, the outer contour of the part, Φ60mm outer circle
and its step surface are processed by end mills, and the upper and lower surfaces are processed by end mills. See the table for details.
(5) Cutting amount selection
See table for details
| Serial number | Tool Number | Tool specification name | Processing surface | Spindle speed S r/min | Feed rate f mm/min | Back cutting depth ap mm | Remarks |
| 1 | T01 | Φ125 carbide Face milling cutter | Milling upper and lower surfaces | 50 | 20 | 5 | |
| 2 | T02 | Φ63 carbide end mill | Milling Φ60 outer circle and its step surface | 100 | 30 | N/A | |
| 3 | T03 | Φ38 drill bit | Drill Φ40 hole | 200 | 40 | 19 | |
| 4 | T04 | Φ40 boring tool | Rough and fine boring of Φ40 inner hole | 650/1000 | 40/30 | 0.8/0.2 | |
| 5 | T05 | Φ13 drill bit | Drill 2×Φ13 holes | 500 | 30 | 6.5 | |
| 6 | T06 | 22×14 countersink drill | 2×Φ22 countersink drill | 350 | 25 | 4.5 | |
| 7 | T07 | Φ25 carbide end mill | Milling outer contour | 260 | 40 | 5 |