Heat rolling machine

In 1862 the Great International Exhibition was held in London and was visited by six million people. At this exhibition a bronze medal was awarded to Parkes for his exhibit Ptu kesine. This was obtained by first preparing a suitable cellulose nitrate and dissolving it in a minimum of solvent. The mixture was then put on a heated rolling machine, from which some of the solvent was then removed. While still in the plastic state the material was then shaped by dies or pressure . In 1866 the Parkesine Co., Ltd was formed but it failed in 1868. This appears in part due to the fact that in trying to reduce production costs products inferior to... 

However, it is a challenging task to maintain a low error margin for the rollers. A heat rolling machine such as the one shown in Figure 14.4 can achieve an error margin as low as 1 pm. In addition, the temperature of the heated rollers... 

Illustration of a heat rolling machine producing pressures up to 4001 and temperatures up to 150°C. (With permission from Naknor Electrode Rolling Equipment Co. Ltd.)... 

Different methods are used. An online ordinary common blown or cast film line uses a machine direction orienter (MDO) on the front end of biaxially oriented film heated chamber extrusion line. If only the machine direction is to be stretched, a series of precision controlled heated rolls can be used. Film is fed through a series of rolls where it is sequentially heated, drawn around rolls that increase in rotational speed providing the stretching action, annealed around larger diameter roll(s), and cooled on a final roll(s). 

Gebr. Sachsenberg in Rosslau/Elbe (Germany) build the first expression rolls machine in Germany Henry Clayton introduces a double-acting piston extruder at the London World Exhibition De Wolfe builds an extruder in USA for cable sheathing Lipowitz carries out first trials for heating the clay with a double-walled extrusion barrel... 

Calendar n. (1) To produce or process sheets of material by pressing between a series of revolving heated rolls. (2) The machine performing the process of calendering. 

The complex thermal processes during shaping in the rolling machine can be described as follows the heat flow between the glass and the rollers is by means of conduction, convection, and radiation. The course of heat flow across the circumference of a roller is reflected in the heat flow diagram (see Fig. 3.19). 

Supercalenders are classic off-line machines as they have downtimes of 25-30% due to the fiUed roll change. To be able to keep pace with a high-speed paper machine at least two, sometimes even three, supercalenders were therefore required. This disadvantage of the supercalender led, at the begiiming of 1980, to the development of the soft calender. The soft calender consists of at least one heated roll and one resilient roll covered with synthetic material. Because synthetic rolls are much more resistant to marking than the filled rolls of the conventional supercalender, the soft calender was also able to be used on-line. In many cases, the online soft calender was very successful. However, not all quality demands on the paper surface could be met with it. For demanding papers, the supercalender equipped with filled rolls and which could therefore only be operated off-Hne remained the only alternative. 

The film can be further oriented uniaxiaUy via a secondary heated roll stacks, or oriented biaxially via a combination of machine direction and transverse direction stretching, which can be accomplished simultaneously or as a two-stage process. Greater detail of cast film extrusion and film orientation process, effects, and mechanics can be found in the referenced texts [18,19]. 

In this Fig. 8-41 view (a) the feeder-roll speed to puller-roll speed ratio can be set, such as 1 4, and simultaneously the ratio of width can be set as 1 4. The machined direction ratio is usually accomplished prior to the plastic s entering the temperature controlled oven that contains the tenter frame, by having it move around heat-controlled rolls where the rotational speed of the rolls increases from one roll to the next. View (b) is a schematic of the drawdown phenomenon with swell to produce orientation in the machined (longitudinal) direction. 

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