Sorting and Marking of Piston Rings

Certain types of piston ring have a very small angle on their edge, it is vital that these are fitted the correct way up into the engine. This system uses a pair of opposed probes to measure the small difference in diameter between the two surfaces of the ring.
This diagram exaggerates the difference, it varies with different products but generally is only a few 10's of microns.
The machine has a reciprocating blade which extracts rings from the bottom of a vertical loader stack and presents them to the measuring station. If the ring is the correct way-up then the top surface is stamped with an identity mark. Subsequent rings then push the preceding ones along the machine bed till they reach the off- load position, where they are diverted according to their orientation. Because the off-load stations are down stream of the measuring position, the computer has to track the rings to ensure the correct ones are accepted. Rings that are the wrong way-up are automatically turned over and passed through the system a second time, for confirmation, before being stamped.
As well as the usual start/stop buttons and other controls, the front panel includes an LCD display screen and associated push buttons, which enable the operator to adjust various parameters which control the system.
All screen displays use context sensitive help messages to guide the operator, and restrict the entered parameters to safe values. The system has to cope with a variety of rings. Simple and rapid set-up is an important feature. The operators merely have to present a sample ring, both ways-up, to the system, which then calculates the required measurement tolerances which it will use to differentiate the rings. As well as measuring the piston rings, the computer also controls the ring loader, ring transfer motor, off-loader pneumatics, etc. It also monitors that rings are present at key positions on the machine and that the loaders and off-loaders are performing correctly. In addition it has to respond to the operation of front panel controls. These various tasks all occur asynchronously and make full use of the multi-tasking features of the object-orientated, high-level control language. The first of these systems was a conversion of an existing machine, with obsolete electronics which was difficult to setup. This has been in full production since early 1993. Subsequent systems have been both similar conversions and completely new machines.