Calibrating the workpiece touch probe

Application

The touch probe must be calibrated in order to enable determining precisely the actual switching point of a 3D touch probe. Otherwise, the control cannot ascertain exact measuring results.

Description of function

During calibration, the control finds the effective length of the stylus and the effective radius of the ball tip. To calibrate the 3D touch probe, clamp a ring gauge or a stud of known height and known radius to the machine table.

The effective length of the workpiece touch probe refers to the tool carrier preset.

Tool carrier reference point

You can calibrate the workpiece touch probe with various tools. For example, the workpiece touch probe can be calibrated using an overmilled surface in length and a calibration ring in the radius. This creates a reference between the workpiece touch probe and the tools in the spindle. In this procedure, measured tools and the calibrated workpiece touch probe correspond using the tool presetting device.

Calibrating an L-shaped stylus

Before you calibrate an L-shaped stylus you first must define the parameters in the touch probe table. Based on these approximate values, the control can align the touch probe during the calibration and determine the actual values.

At first, define the following parameters in the touch probe table:

Parameter

Value to be defined

CAL_OF1

Length of extension

The extension is the angled length of the L-shaped stylus.

CAL_OF2

0

CAL_ANG

Spindle angle at which the extension is parallel to the main axis

For this, manually position the extension in the direction of the main axis and read the value from the position display.

After the calibration, the control overwrites the previously defined values in the touch probe table with the determined values.

Touch probe table tchprobe.tp (#17 / #1-05-1)

When calibrating the length, the control aligns the touch probe with the calibration angle defined in the CAL_ANG column.

While calibrating the touch probe, ensure that the feed rate override is 100%. That way you can always use the same feed rate for the subsequent probing processes as was used for the calibration. Hence, you can exclude inaccuracies during the probing caused by modified feed rates.

Reversal measurement

When calibrating the ball-tip radius, the control executes an automatic probing routine. In the first run the control finds the midpoint of the calibration ring or pin (approximate measurement) and positions the touch probe in the center. Then, in the actual calibration process (fine measurement), the radius of the ball tip is ascertained. If the touch probe allows probing from opposite orientations, the center offset is determined during another cycle.

HEIDENHAIN touch probes are predefined as to whether or how a touch probe can be oriented. Other touch probes are configured by the machine manufacturer.

When calibrating the radius, up to three circular measurements can be taken depending on the possible orientation of the workpiece touch probe. The first two circular measurements determine the center offset of the workpiece touch probe. The third circular measurement determines the effective stylus tip radius. If orientation of the spindle is not possible or only a certain orientation is possible due to the workpiece touch probe, circular measurements are omitted.

Calibrating the length of the workpiece touch probe

To calibrate a workpiece touch probe using an overmilled surface in length:

  1. Measure the end milling cutter on the tool presetting device
  2. Store the measured end milling cutter in the tool magazine of the machine
  3. Enter the tool data of the end milling cutter in tool management
  4. Clamp the workpiece blank

  1. Select the Manual operating mode

  1. Replace the end milling cutter in the machine
  2. Switch on spindle (e.g., with M3)
  3. Use the handwheel to scratch the workpiece blank
  4. Setting a preset with milling cutters

  5. Set preset in the tool axis (e.g., with Z)
  6. Position the end milling cutter next to the workpiece blank
  7. Set a small value in the tool axis (e.g., -0.5 mm)
  8. Overmill the workpiece blank using the handwheel
  9. Set the preset again in the tool axis (e.g., with Z=0)
  10. Switch off spindle (e.g., with M5)
  11. Replace the tool touch probe
  12. Select the Setup application

  1. Select Calibrate touch probe

  1. If necessary, check the values of the active preset or choose a different preset

  1. Select the Length calibration measurement method
  2. The control displays the current calibration data.
  3. Enter the reference surface position (e.g., with 0)
  4. Position the workpiece touch probe close to the surface of the overmilled area
  5.  
    Tip

    Check that the area to be probed is flat and free of chips before you start the touch probe function.

  1. Press the NC Start key
  2. The control performs the probing process and then automatically retracts the workpiece touch probe to the starting point.

  1. Check results

  1. Select Apply calibration data
  2. The control transfers the calibrated length of the 3D touch probe to the tool table.

  1. Select Exit probing
  2. The control closes the Calibrate touch probe function.

Calibrating the radius of the workpiece touch probe

To calibrate a workpiece touch probe using a setting ring in the radius:

  1. Clamp the setting ring on the machine table (e.g., with clamps)

  1. Select the Manual operating mode
  2. Position the 3D touch probe in the hole of the setting ring
  3.  
    Tip

    Make sure that the stylus tip is completely recessed into the calibration ring. This causes the control to probe with the largest point of the stylus tip.

  4. Select the Setup application

  1. Select Calibrate touch probe

  1. If necessary, check the values of the active preset or choose a different preset

  1. Select the Radius measurement method

  1. Select the Setting ring calibration standard

  1. Enter the diameter of the ring gauge

  1. Enter the start angle

  1. Enter the number of touch points

  1. Press the NC Start key
  2. The 3D touch probe probes all required touch points in an automatic probing routine. The control calculates the effective stylus tip radius. If probing from opposite orientations is possible, the control calculates the center offset.
  3. Check results

  1. Select Apply calibration data
  2. The control stores the calibrated radius of the 3D touch probe in the tool table.

  1. Select Exit probing
  2. The control closes the Calibrate touch probe function.

Instructions for calibration

  • In order to be able to determine ball-tip center misalignment, the control needs to be specially prepared by the machine manufacturer.
  • If you press the OK button after the calibration process, the control accepts the calibration values for the active touch probe. The updated tool data then becomes immediately effective, and it is not necessary to repeat the tool call.
  • HEIDENHAIN guarantees the proper operation of the touch probe cycles only in conjunction with HEIDENHAIN touch probes.
  • If you want to calibrate using the outside of an object, you need to pre-position the touch probe above the center of the calibration sphere or calibration pin. Ensure that the probing points can be approached without collisions.
  • Use the +, -, *, /, (, and ) keys for calculations in the numerical input fields.
  • The control saves the effective length and effective radius of the touch probe in the tool table. The control saves the touch probe center offset in the touch probe table. The control uses the TP_NO parameter to link the data from the touch probe table with the data from the tool table.
  • Touch probe table tchprobe.tp (#17 / #1-05-1)