特殊双曲柄机构300fps间歇相机主要问题分析

我们研制的35毫米300fps间歇相机的抓片机构是一个具有可调节环节的特殊双曲柄机构。这个机构是在齿轮双曲柄机构的一个连杆的交接点处增加了一个偏心调节环节(如图1示)。偏心调节环外圈为球面,与抓片爪(连杆BE)孔滑动配合,回转中心在E点,距E点e处是偏心9.5mm齿轮偏心轴轴心C。偏心轴与调节环间用滚动轴承连接,偏心环节与爪组成有三个自由度的连接付。

Main Problem Analysis of a 300 f.p. s. Intermittent Camera with Special Double Crank

The film-pulling-down mechanism in a 300 f.p.s.intermittent camera developed by us is a five-linkage mechanism,i e.an accentric adjustable loop is added to the rear hinge of the linkage for the double-crank mechanism.The gears with the accuracy of grade 6 by Chinese standard and the major parts with the machining accuracy of grade 1 to 2 could ensure that the mechanism runs normally and the moving characteristic of the claw-fingers is almost the same as that of the double crank.There are three main problems in the camera with above mechanism:1. To adapt the contraction of the film to a certain extent, both the radius r of the crank and the hight h of the claw-fingers must be less than the standard valuse. In this paper, the principle of choosing the valuses of r and h(?) analysed in detail.2. The moving characteristic of the film is not exactly the same as that of the claw-fingers. Therefore, when analysing the problems one shouldn’t replace the motion pattern the film by that of the claw-fingers. Beside the film-pulling-down-displacement, there are still four kinds of dis-placement which could not be ignored.3. No matter what frequency is used while taking pictures, the film must exactly be shifted the distance of a real frame, H(1-ε) (ε is the contracting ratio of the film), rather than the distance of a theoretical frame (19mm). The exact shift of the film could not be done only by the claw-fingers, in other words, the stroke of pulling down film couldnt be so accurate. The function of the registration pin is not only locking the film, but also assisting the daw-fingers in shifting the film an exact distance, i. e. when taking pictures in low frequency the registration pin has to assist a lot in shifting the film, but in high frequency it doesn’t have to or just has to do a little in correcting the film displacement. So that the photographing at 300 f.p.s. could be successfully achieved.