Approach functions APPR CT and APPR PCT

Application

The control uses these functions to approach a contour on a circular path with tangential connection. You use APPR CT to define the starting point of the contour with Cartesian coordinates, and APPR PCT for polar coordinates.

Description of function

8H000_40
  • The control approaches the contour as follows:
  • On a straight line from the starting point PS to an auxiliary point PH
  • On a circular path that tangentially transitions to the first contour element, from the auxiliary point PH to the first contour point PA
  • The circular path from PH to PA is defined by center angle CCA and radius R. The direction of rotation of the circular path depends on the active radius compensation and the algebraic sign of radius R.

The table shows the relationship between the radius compensation, the algebraic sign of the radius R, and the direction of rotation:

Radius compensation

Algebraic sign of R

Direction of rotation

RL

Positive

Counterclockwise

RL

Negative

Clockwise

RR

Positive

Clockwise

RR

Negative

Counterclockwise

  • The following applies regarding the center angle CCA:
  • Only positive input values
  • Maximum input value 360°

Programming APPR CT and APPR PCT

 
Tip

If you want to program this path shape with polar coordinates, then you must first define a pole CC.

Polar coordinate datum at pole CC

  1. To define the approach function:
  2. Use any path function to approach the starting point PS
ApprDep

  1. Select APPR DEP
  2. The control opens the Insert NC function window.
ProgramApprCtIcon

  1. Select the path shape, for example APPR CT
  2. Define the coordinates of the first contour point PA
  3. Define the circle center angle CCA
  4. Define the radius R of the circular path
  5. Select radius compensation RR/RL

Notes

  • If you enter a negative value for the radius R, the position of the auxiliary point PH changes.
  • If you program R0, the control stops the machining/simulation with an error message. This behavior differs from the iTNC 530 control.

Example APPR CT

11 L X+40 Y+10 R0 FMAX M3

; Approach PS without radius compensation

12 APPR CT X+10 Y+20 Z-10 CCA180 R+10 RR F100

; PA with radius compensation RR, radius of the circular path: R 10

13 L X+20 Y+35

; End point of first contour element

14 L ...

; Next contour element