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.
Related topics
- Calibrate the workpiece touch probe automatically
- Touch probe table
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.
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 |
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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:
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Calibrating the radius of the workpiece touch probe
To calibrate a workpiece touch probe using a setting ring in the radius:
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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.