Basic Study on Paper Crease Generation Mechanism in Printers and Copiers

研究的实施方案是：(1)找出影响纸张通过固定辊单元的折皱的因素，并研究辊与纸之间的摩擦力-滑移速度特性。(2)利用有限元分析软件MARC，建立了橡胶辊进纸过程的二维和三维数值模拟方法。(3)建立了模拟胶辊送纸过程的方法。(3)建立了胶辊送纸过程的模拟方法。(3)胶辊送纸速度的模拟结果与实验结果吻合较好。将实验得到的摩擦力特性应用于仿真。(4)橡胶辊表面在NIP(两个柔性体之间的接触区)内表现出伸长应变。由于张力，滚筒表面速度几乎等于进纸速度，增加并超过橡胶滚筒的名义圆周速度。(5)当放在相对于滚筒水平轴倾斜3度的导板上的纸张被送入固定滚筒单元时，总是在纸张移动方向上观察到产生折痕。当倾斜度接近零时，皱纹消失。(6)利用圆柱形橡胶和钢辊的三维进纸模型，对皱纹的产生过程进行了模拟。结果表明，在纸张前缘进入压区且纸张沿平面外方向轻微变形的瞬间，投射在水平面上的纸张宽度略有变短。这使我们认为，平面外的变形会被滚筒压住，从而引起纸张的折皱。

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.