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This document, and the content contained herein, is intended for customers, users and other persons with the operation and features of the covered Hegla products. While Hegla makes every effort to include accurate and useful information, it is not possible to anticipate or address every possible situation or to account for conditions at unknown locations or interactions with unknown systems or components. Therefor, these documents must be used only for informational purposes and used in conjunction with best practices and with due care. Hegla shall not be responsible for any injuries or losses that occur as a result of the information in this document. Moreover, as products and offerings change over time, the usefulness of the information in this document may become obsolete. It is the responsibility of the reader or consumer to ensure that the information contained herein is timely and reflects the current reality of Hegla products and offerings. Hegla disclaims any and all warranties regarding the information in this document.
***Read chapter 1 of your operators manual before undertaking any work in the area of the linear drives equipment.***
When in doubt please contact Hegla service before taking action (404) 763-9700
Adjustment of the grinding height
The location of the floating position sensor bracket and milled "window" may vary slightly depending on year model, however the concept is the same.
If the parameters and sensors described in this document are set correctly then the grinding head should be 5mm above the glass when using glass that is equal too or greater than 5mm thick. If the glass is less than 5mm thick, then the grinding wheel should be 11mm above the felt when the stepping motor is in the target position. This ensures that the grinding wheel cannot grind into the felt of the tabletop because the maximum pneumatic stroke of the cylinder for the grinding head is 10mm.
The height is calculated based on a number of different components:
- The setting of the “floating position sensor”.
- The height of the measuring block in relation to the tabletop.
- The glass thickness and even what type of grinding wheel is being used on the machine.
Floating position sensor
The floating position sensor must be adjusted so that the sensor is switched when the pneumatic is in its upper position or in its lower position. During grinding the Sensor is not switched, it is in the middle position, otherwise an error will be generated that will appear on the HMI (Grinding head too high/too low) (Floating Position Error).
Picture 1: Pneumatic is in upper position, Picture 2: Pneumatic is in lower position,
grinding wheel is up. grinding wheel is down.
***The newer style sensor and bracket shown below (Concept is the same as above):
Procedure for adjustment:
1. Adjust the sensor in the upper position (Picture 1) grinding wheel is up.
2. Switch the pneumatic down through the HMI (Grinding wheel up/down).
3. Adjust the sensor in the lower position (Picture 2) grinding wheel is down.
4. Switch the pneumatic up through the HMI (Grinding wheel up/down).
5. Switch the pneumatic several times up and down through the HMI and check if the sensor is
switching reliably in the up and down position, if not repeat from point 1.
When measuring the grinding wheel, the pneumatics engage down (cylinders extended), then the stepping motor slowly lowers the grinding wheel onto the measuring block. Once the wheel is on the block it compresses the cylinders and in doing so, the floating position sensor becomes not made. The step motor registers the position measurement and stores it as reference value for calculation of the height for each independent article based on the grinding wheel diameter that was just measured. Depending on how the floating position sensor is adjusted the sensor make an open contact sooner or later and this in turn affects the measurement of the wheel. When changing the adjustment of the sensor it affects the height of the grinding wheel above the glass and when grinding, it also affects how much of the wheel gets removed when dressing with the diamond and the calculation of the RPMs of the grinding wheel.
Measuring block
A further influence on the height of the grinding wheel when grinding comes from the physical
position of the measuring block on the machine. Depending on the height below tabletop of the
measuring block the floating position sensor becomes free earlier or later.
Picture 3: Measuring block
Procedure for adjustment:
1. Put any sheet of glass on the table so that it is laying on the felt above the measuring block (Picture 4).
2. Measure the distance between the measuring block and the lower glass edge. (Picture 5).
3. Enter the measured distance in the P-Field menu of the HMI under P-field no. 1432 "offset measuring plate under felt in mm" (Picture 6)
Picture 4: Picture 5:
Picture 6:
Alternatively the offset could be located in the MK (Machine Data) as shown below:
Grinding Wheel
Another effect on the height can come from the type of the grinding wheel that is used. Depending on if the grinding wheel is softer or harder it can affect the compression of the grinding wheel when measuring on the measuring block. Hegla recommends using the supplied Norton abrasive disks (20mm=31-4067-5200, 10mm=31-4067-5100) at the time of delivery of the machine. There is another offset that influences the calculation of the height adjustment, unfortunately this parameter is not in the same file on all machines to date. In future this parameter will be located in the P-Field menu, but on older machines you will find it in the PLC program under MK_Glas_Offset_Schleifscheibe WORD := 0;.
Example how to set this value: If it is set to 2 then the grinding wheel is positioned 2mm higher above the glass than it was before.
If it is set to -2 then the grinding wheel would be positioned 2mm lower above the glass than it was before. Postive value =
Negative value =
Note: For the fine adjustment of the grinding wheel to the dressing pin use the P1430 and P1431 fields (May not be an option on every machine).
