"Design and Implementation of Balance Testing Machine for Grinding and Cut-off Wheels "

Abstract

In this project a device for measuring unbalance in cutoff and grinding wheels that are manufactured in the factory of JELANCO has been implemented successfully, in addition to determining the value of the unbalance in a given cutoff or grinding disc, the device is able to measure the disc's weight and it can calculate the mass that should be compensated on the outer perimeter of the wheel in order to remove unbalance, and in order to facilitate compensation for unbalance the wheel perimeter is divided into ten sectors and the one on which the compensation must take place will light.

The device is static and there exist no rotating parts and the results takes only a few seconds to appear as if it is a commercial weigh scale. The device is based on static unbalance measurements for planner objects in which object is put on some fixture and three reaction forces are measured on the surface of the object, from these reaction forces, the unbalance, the weight and the angle of compensation can be calculated.

Three load cells are used to measure the three reaction forces on the cutoff or grinding wheel, the output of these load cells is in mill volts at the rated loads so it must be amplified and filtered, the signal conditioning circuits have been implemented such that they provide large amplification with minimum noise.

External analog to digital converters are used to convert the load cell's amplified voltage into digital form that is suitable for processing in the PIC microcontroller that is used as a processing unit that performs the computations in the device. The ADC communicates with the microcontroller through serial communication protocol and it can provide a noise free resolution of 14 bit which corresponds to a weight resolution of 0.0382 gram. Experimental results showed that the device is accurate and repeatable to a value that is enough for measuring unbalance in cutoff and grinding wheels.