CNC Z32 - Programming Guide (LATHES)
Thread type:
E =100
Metric screw 60° UNI 4535-64
E =200
Metric lead screw 60° UNI 4535-64
E =300
Whitworth screw UNI 2709
E =400
Whitworth lead screw UNI 2709
E =500
Trapezoidal screw UNI 2902
E =600
Trapezoidal lead screw UNI 2902
E =700
Square section screw (depth 0.5*K/NF)
E =800
Square section lead screw (depth 0.5*K/NF)
E =900
Generic screw (custom)
E =1000
Generic lead screw (custom)
1. Cutting methods and thread types
The macro cuts the thread by removing a chip with constant section, and advancing on the thread side.
The advancement on the thread side allows to obtain a chip with “flat” section, warranting a longer duration of the
cutting edge.
On metric ISO and WHITWORTH threadings, an angle smaller by 5 degrees with respect to the thread side slope
is used.
On TRAPEZOIDAL threadings, an angle smaller by 4 degrees with respect to the thread side slope is used.
Square and custom threadings allow only radial advancements.
Custom thread
The custom (generic) threading is a threading with radial pass increment. Unlike the square section threading
(where tooth height is equal to the pitch), with the custom threading it is possible to define the thread depth with the
parameter (NU) defining the “breakthrough”.
2. Threads with more starting worms
The cycle executes threadings with more starting worms, by displacing the threading starting point by a quantity
equal to the thread pitch (K) divided by the number of worms (I).
3. Threading cycle
After the “on air” positioning defined by the programmer, the threading macro G905 executes the following
operations:
Computes radial and axial increments, and positions the tool according to the preparatory function active before the
M63 and the following may be executed:
a linear segment, if G1 or G0 is active
a circular arc if G2/G3 is active
Executes a “sliding” thread, as indicated in the preceding figure. The pass depth is computed by maintaining
constant the chip section.
In order to avoid dangerous loads on the tool, the first and second pass are executed by halving the pass depth
resulting from the computation.
Exits from the thread with a connecting radius, to retract from the workpiece by the quantity defined by the
parameter J (in mm).
Returns in rapid, parallel to the workpiece, at the same Z position of the starting point.
Computes and reaches in rapid the new incremented point
Repeats from point 2 to point 6 to execute the programmed roughing passes
Repeats the last executed movement without increments, for the programmed lapping (finishing) passes.
It is important to note the following:
The initial, “on air”, tool position must be defined to allow the spindle to reach the programmed speed (normally
two-three profile pitches) before the start of the thread.
For taper threads, the nominal diameter must be computed as a function of the NZ parameter, the “on air”
coordinate of Z axis for the first positioning.
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Summary of Contents for CNC Z32 Florenz Series
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