Общий каталог Yamawa 2022 - 2023 - страница 1228

22. Features of MC-Helical Thread Mills
Description of products


■Feed speed
Feed speed is decided by the characteristic of work materials. Feed speed
is an important factor because machining time, thread finish and tool Feed speed of tool
durability are getting influenced by the feed speed.
Vf = fz・Z・n・(D-Dc)/D (mm/min)
In the material of low tensile strength, feed per tooth can be set up rather
large. However, if you set up feed per one tooth too large, thread milling fz : Feed per tooth(mm/t)
z : Number of tooth
cutters can cause deflection and may badly cause thread limit. n : Spindle RPM Revolution Speed (min-1)
Dc : Outer diameter of tool (mm)
D : Nominal size of internal thread (mm)

■Cut of cutters
Side of
Generally, Cut of cutter is decided by the machine programming in which internal threads
the machine enables the cutter to cut the thread height in one
revolution. MC helical cutter is so designed that its minor diameter does
not cut, and the same bored hole size as that for cutting tap is adopted.


Side of milling cutters


─Metric thread ─Metric thread
[ Minor dia. basis] [ Tool basis]
Tool cut Tool transverse


where,
: Nominal size of internal threads
: Basic minor diameter of internal threads
: Minor diameter before cutting
: Outside diameter of tool
: 0.866025P
: Pitch
: Tolerance of pitch diameter for producing internal thread
: Shrinkage after cutting
(Set up in the middle of pitch diameter tolerance)
: Difference between of basic thread profile and O.D. of the cutters.


■Approaching and leaving to and from work material
Information
Technical


On approaching and leaving to and from work material, the cutter must always be traversed in
helical interpolating movement so that the cutter enables smooth cutting in and out. And it is
necessary to cut the material gradually by the lead of screw thread. Otherwise, threads can be
thinned.
Initial cutting A＜B

Technical-77