Basic Study on Paper Crease Generation Mechanism in Printers and Copiers

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The study execution plan is (i)to find out what factors affect on a crease occurred in a paper passing through a fixing roller unit and to investigate friction force-slip velocity characteristics between rollers and paper. (ii)To construct a method for simulating two or three dimensional paper feed process with rubber rollers by means of FEM analyzing software MARC. (iii)To simulate the paper crease generation process and to find out ways to avoid it.The results of the study are summarized as follows.(1)The dynamic friction force increases suddenly from zero value and approaches a certain value as the slip velocity between the roller and paper increases.(2)A method for simulating the paper feed process by rubber rollers is constructed.(3)The simulation results of a paper feed velocity by rubber rollers have a good agreement with the experimental ones, when the friction force characteristics obtained by the experiments are used in the simulation.(4)The surface of the rubber roller exhibits an elongation strain in a nip (contact area between two flexible bodies). Because of the strain, the roller surface velocity, which is almost equal to the paper feed velocity, increases and exceeds the nominal circumferential velocity of the rubber roller.(5)A crease generated in a paper traveling direction is always observed when the paper, which is put on a guide plate tilting 3 degree against the roller horizontal axis, is fed to the fixing roller unit. The crease disappears when the tilt approaches zero.(6)Using three dimensional paper feed model with cylindrical rubber and steel rollers, the crease generation process (5)is simulated. The results show that the paper width projected on the horizontal plane becomes a little bit shorter at the instant when the paper leading edge comes into the nip and the paper slightly deforms in the out-of-plane direction. This enable us to think that the out-of-plane deformation will be pressed by the rollers and causes the paper crease.