Machining with polar kinematics with POLARKIN

Application

In a polar kinematic model, the path contours of the working plane are performed by one linear axis and one rotary axis instead of by two linear principal axes. The working plane is defined by the linear principal axis and the rotary axis while the working space is defined by these two axes and the infeed axis.

On milling machines, various linear principal axes can be replaced with suitable rotary axes. For example on large machines, polar kinematics enable you to machine much larger surfaces than with only the principal axes.

Requirements

  • Machine with at least one rotary axis
  • The polar rotary axis must be installed onto the table side so that it is opposite the selected linear axes and must be configured as a modulo axis. Thus, the linear axes must not be positioned between the rotary axis and the table. The maximum range of traverse of the rotary axis is limited by the software limit switches if necessary.

  • PARAX COMP DISPLAY NC function programmed with at least the main axes X, Y and Z
  • HEIDENHAIN recommends defining all of the available axes within the PARAX COMP DISPLAY function.

  • Defining behavior when positioning parallel axes with FUNCTION PARAXCOMP

Description of function

When the polar kinematics are active, the control displays an icon in the Positions workspace. This icon covers the icon for the PARAXCOMP DISPLAY function.

The function POLARKIN AXES allows you to activate the polar kinematics model with two linear axes and one rotary axis.

  • The first linear axis must be radial to the rotary axis.
  • The second linear axis defines the infeed axis and must be parallel to the rotary axis.
  • The rotary axis defines the polar axis and is defined last.
  • Any available modulo axis that is installed at the table opposite to the selected linear axes can be used as the rotary axis.
  • The two selected linear axes thus span a plane that also includes the rotary axis.

The following scenarios lead to deactivation of the polar kinematics:

  • Execution of the POLARKIN OFF function
  • Selection of an NC program
  • Reaching the end of the NC program
  • Abortion of the NC program
  • Selecting a kinematic model
  • Restarting the control

MODE options

The control provides the following options for positioning behavior:

MODE options:

Syntax

Function

POS

Seen from the center of rotation, the control performs machining in the positive direction of the radial axis.

The radial axis must be prepositioned correspondingly.

NEG

Seen from the center of rotation, the control performs machining in the negative direction of the radial axis.

The radial axis must be prepositioned correspondingly.

KEEP

The control remains with the radial axis on that side of the center of rotation on which the axis was positioned when the function was activated.

If the radial axis is positioned at the center of rotation upon switch-on, POS applies.

ANG

The control remains with the radial axis on that side of the center of rotation on which the axis was positioned when the function was activated.

If you set POLE to ALLOWED, positioning through the pole is possible. The pole side is changed and a 180-degree rotation of the rotary axis is prevented.

POLE options

The pole is the rotation center of the rotary axis which you define within POLARKIN.

The control provides the following options for machining at the pole:

POLE options:

Syntax

Function

ALLOWED

The control permits machining operations at the pole

SKIPPED

The control prevents machining operations at the pole

 
Tip

The disabled area corresponds to a circular surface with a radius of 0.001 mm (1 μm) around the pole.

Input

NC programs contained in this User's Manual are suggestions for solutions. The NC programs or individual NC blocks must be adapted before being used on a machine.

Change the following contents as needed:

  • Tools
  • Cutting parameters
  • Feed rates
  • Clearance height or safe position
  • Machine-specific positions (e.g., with M91)
  • Paths of program calls

Some NC programs depend on the machine kinematics. Adapt these NC programs to your machine kinematics before the first test run.

In addition, test the NC programs using the simulation before the actual program run.

 
Tip

With a program test you determine whether the NC program can be used with the available software options, the active machine kinematics and the current machine configuration.

11 POLARKIN AXES X Z C MODE: KEEP POLE: ALLOWED

; Activate polar kinematics with axes X, Z and C.

The NC function includes the following syntax elements:

Syntax element

Meaning

POLARKIN

Syntax initiator for polar kinematics

AXES or OFF

Activate or deactivate polar kinematics

X, Y, Z, U, V, A, B, C

Selection of two linear axes and one rotary axis

Only when AXES is selected

Other possibilities might be available, depending on the machine.

MODE:

Selection of the positioning behavior

MODE options

Only when AXES is selected

POLE:

Selection of machining in the pole

POLE options

Only when AXES is selected

Notes

  • The principal axes X, Y, and Z as well as the possible parallel axes U, V, and W can be used as radial axes or infeed axes.
  • Position the linear axis that will not be included in the polar kinematics to the coordinate of the pole, before the POLARKIN function. Otherwise, a non-machinable area with a radius that corresponds to at least the value of the deselected linear axis would result.
  • Avoid performing machining operations at the pole or near the pole, because feed-rate variations may occur in this area. For this reason, ideally use the following POLE option: SKIPPED.
  • The workpiece preset does not need to be in the pole.
  • Polar kinematics cannot be combined with the following functions:
  • Note that the traversing range of the axes may be limited.
  • Notes on software limit switches for modulo axes

  • Traverse Limits

Notes about machine parameters

  • The machine manufacturer uses the optional machine parameter kindOfPref (no. 202301) to define the behavior of the control when the path of the tool center point passes through the polar axis.
  • The machine manufacturer uses the optional machine parameter presetToAlignAxis (no. 300203) to define for each axis how the control will interpret offset values. For POLARKIN, the machine parameter applies only to the rotary axis that rotates about the tool axis (in most cases C_OFFS).
  • Comparison of offset and 3D basic rotation

    • If the machine parameter axis has not been defined or has been set to TRUE, the offset can be used to compensate for a misalignment of the workpiece in the plane. The offset affects the orientation of the workpiece coordinate system W-CS.
    • Workpiece coordinate system W-CS

    • If the machine parameter axis has been defined with FALSE, the offset cannot be used to compensate for a misalignment of the workpiece in the plane. The control will not take the offset into account when executing the commands.

Example: SL cycles in the polar kinematics

NC programs contained in this User's Manual are suggestions for solutions. The NC programs or individual NC blocks must be adapted before being used on a machine.

Change the following contents as needed:

  • Tools
  • Cutting parameters
  • Feed rates
  • Clearance height or safe position
  • Machine-specific positions (e.g., with M91)
  • Paths of program calls

Some NC programs depend on the machine kinematics. Adapt these NC programs to your machine kinematics before the first test run.

In addition, test the NC programs using the simulation before the actual program run.

 
Tip

With a program test you determine whether the NC program can be used with the available software options, the active machine kinematics and the current machine configuration.

0 BEGIN PGM POLARKIN_SL MM

1 BLK FORM 0.1 Z X-100 Y-100 Z-30

2 BLK FORM 0.2 X+100 Y+100 Z+0

3 TOOL CALL 2 Z S2000 F750

4 FUNCTION PARAX COMP DISPLAY X Y Z

; Activate FUNCTION PARAX COMP DISPLAY

5 L X+0 Y+0.0011 Z+10 A+0 C+0 FMAX M3

; Pre-position outside the disabled pole area

6 POLARKIN AXES Y Z C MODE: KEEP POLE: SKIPPED

; Activate POLARKIN

7 * - ...

; Datum shift in polar kinematics

8 TRANS DATUM AXIS X+50 Y+50 Z+0

9 CYCL DEF 14.0 CONTOUR

10 CYCL DEF 14.1 CONTOUR LABEL2

11 CYCL DEF 20 CONTOUR DATA ~

Q1=-10

;MILLING DEPTH ~

Q2=+1

;TOOL PATH OVERLAP ~

Q3=+0

;ALLOWANCE FOR SIDE ~

Q4=+0

;ALLOWANCE FOR FLOOR ~

Q5=+0

;SURFACE COORDINATE ~

Q6=+2

;SET-UP CLEARANCE ~

Q7=+50

;CLEARANCE HEIGHT ~

Q8=+0

;ROUNDING RADIUS ~

Q9=+1

;ROTATIONAL DIRECTION

12 CYCL DEF 22 ROUGH-OUT ~

Q10=-5

;PLUNGING DEPTH ~

Q11=+150

;FEED RATE FOR PLNGNG ~

Q12=+500

;FEED RATE F. ROUGHNG ~

Q18=+0

;COARSE ROUGHING TOOL ~

Q19=+0

;FEED RATE FOR RECIP. ~

Q208=+99999

;RETRACTION FEED RATE ~

Q401=+100

;FEED RATE FACTOR ~

Q404=+0

;FINE ROUGH STRATEGY

13 M99

14 TRANS DATUM AXIS X+0 Y+0 Z+0

15 POLARKIN OFF

; Deactivate POLARKIN

16 FUNCTION PARAX COMP OFF X Y Z

; Deactivate FUNCTION PARAX COMP DISPLAY

17 L X+0 Y+0 Z+10 A+0 C+0 FMAX

18 M30

19 LBL 2

20 L X-20 Y-20 RR

21 L X+0 Y+20

22 L X+20 Y-20

23 L X-20 Y-20

24 LBL 0

25 END PGM POLARKIN_SL MM