Print hammer bumper exhibiting dual resiliency characteristics

Claim 1

In an on-the-fly impact printer including a print hammer mechanism having a plurality of selectively actuable print hammers disposed in a lateral array with each hammer movable along a linear path for printing on a web composed of at least a single sheet of paper; the hammers exhibiting a forward movement directed toward the paper web during printing and a rebound movement produced by the abrupt termination of the forward hammer movement upon completion of a printing operation, an improved bumper mechanism for automatically adjusting the forward force of the hammer to the number of paper plys of the web and for damping the rebound energy of the hammer upon its return stroke comprising: a unitary elongated resilient bumper positioned to engage each of said print hammers during their printing stroke and for engaging said print hammers upon the return stroke; said unitary bumper defining a first portion fabricated of a first material for engaging each of the hammers during their printing stroke and exhibiting a hardness characteristic selected to reduce the forward impact force of each of the hammers upon the paper to that force necessary to produce an acceptable print upon each of the sheets in the web and having a first resiliency, and said unitary bumper defining a second portion fabricated of a second material for engaging each of said hammers during their return stroke and exhibiting a second resiliency lower than said first resiliency so as to quickly absorb the return forces of each hammer thereby greatly reducing the intensity and duration of the hammer rebound upon return to its nonprint condition.