Springs under control

摘要

In the industry of spring manufacturing, in order to improve quality and reducing discards, systems which control dimensional features (fundamentally length and diameter) of every manufactured piece are more and more widespread. These systems discard the pieces which do not fall within a prearranged range. The dimensional differences among the various pieces, which are mainly brought about by faults of the coiling machine or lack of homogeneity in the mechanical strength of the wire, can cause a malfunction in coiling and therefore produce springs which are not exactly alike. This can bring about possible problems in the application stage. In order to compensate for these problems, systems which allow to control the dimensions of every manufactured spring have been made ready. The most simple and wide-spread system consists of fixed or moving mechanical feelers which, by rushing along the spring, measure its length and diameter. These devices are effective, but they show limits in preciseness and in addition are exposed to dirty, breaking, and wear. Above all, these systems do not dispose of controlling programmes which can interface with the controlling programmes of the coiling machine and therefore do not allow automatic corrections of the working parameters of the machine itself. These operating limits can be overcome by using a special electronic system which on the one hand carries out the dimensional control of every manufactured and on the other hand can manage the running of the machine. This system consists fundamentally in a computerized working station which is put on board of the machine and its sensor is a high definition telecamera. The telecamera takes a photograph for every spring, recording both its free length and diameter. The values which are recorded this way are put in comparison with the values of a sample spring, which has been previously measured with high preciseness by a gauge. When a spring does not respect the fixed dimensions, the system sends automatically to the digital control system of the machine drives for a correction in real time of the running parameters.