Общий каталог Palbit - страница 392

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E THREAD work methods | CALCULATe THE HELIX ANGLE AND CHOOSe THE RIGHT ANVIL E

Métodos de trabalho de roscagem | Métodos de trabajo de roscado Calcular o ângulo de hélice e escolher o colchão adequado | Calcular el ángulo de hélice y elegir el colchón adecuado FLANK CLEARANCE ANGLE (a)

ThreadInserts & ToolholdersRotationFeed DirectionHelix MethodMethod
EX RHAnticlockwiseTowards chuckRegularA

Right Hand external

EX LHClockwiseFrom chuckReversedB
IN RHAnticlockwiseTowards chuckRegulara

Right Hand Internal

IN LHClockwiseFrom chuckReversedb
EX LHClockwiseTowards chuckRegularD

Left Hand External

EX RHAnticlockwiseFrom chuckReversedC
IN LHClockwiseTowards chuckRegulard

Left Hand Internal

IN RH Anticlockwise From chuck Reversed c

THREAD INFEED METHODS |

Métodos de roscagem infeed | Métodos de roscado infeed

RADIAL INFEED FLANK INFEED (modified) ALTERNATE FLANK INFEED

Palbit toolholders are designed to tilt the insert when seated in the toolholder (10º for external, 15º for internal tooling). This results in the differing flank clearance angles, based on the geometry a = arctan (tanØ/ 2 x tand) of insert. To ensure that the side of the insert cutting edge will not rub on the workpiece, it is most

important that the insert helix angle be correct - especially in profiles with small enclosed flank Where: a - flank clearance angle

angles. This correction is provided by Palbit anvils. d - Tilt angle Ø - Enclosed flank angle CALCULATING THE HELIX ANGLE (b) FORMULA

The helix angle is calculated by the following formula: b - Helix angle (º) P - Pitch (1/TPI) N - No. of starts D - Pitch diameter (mm) Lead = P x N TPI = Threads per inches The helix angle can also be found using the diagram below

HELIX ANGLE DIAGRAM

5º 4º 3º b=2º b=1º

1-3º

Radial infeed is the simplest and quickestFlank infeed is recommended in theUse of the alternate flank method is
method.following cases:recommended especially in large pitches
The feed is perpendicular to the turningwhen the thread pitch is greater than 16and for materials with long cihps.
axis, and both flanks of the insert performtpi., using the radial method, the effectiveThis method divides the load equally on
the cutting operation.cutting edge length is too large, resultingboth flanks, resulting in equal wear along
Radial infeed is recommended in 3 cases:in chatter.the cutting edges. Alternate flank infeed
  • when the pitch is smaller than 16 tpi
  • for TRAPEZ and ACME. The radial method requires more complicated programming,
  • for material with short chips result in three cutting edges, making chip and is not available on all lathes.
  • for work with hardened material flow very difficult.

1.5º

b=0º

1.5º

b=-2º b=-1º *For Multi-start threads, use the lead value instead of the pitch