The manufacture of rubber goods : a practical handbook for the use of manufacturers, chemists, and others . Fig 21a. teeth always give rise to a certain amount of back-lash, whichmakes itself evident in the form of striped markings right acrossthe calendered sheet, where the rubber runs thin. The arrangement for adjusting the top and bottom rolls shouldbe fixed in a convenient position about half-way up the machine,and it should be possible to adjust either top or bottom roll bymanipulating a single wheel. The bearings of the middle roll arefixed. The gearing, as also the worm-wheels for the s
The manufacture of rubber goods : a practical handbook for the use of manufacturers, chemists, and others . Fig 21a. teeth always give rise to a certain amount of back-lash, whichmakes itself evident in the form of striped markings right acrossthe calendered sheet, where the rubber runs thin. The arrangement for adjusting the top and bottom rolls shouldbe fixed in a convenient position about half-way up the machine,and it should be possible to adjust either top or bottom roll bymanipulating a single wheel. The bearings of the middle roll arefixed. The gearing, as also the worm-wheels for the spindles, andthe spindles themselves, cannot be chosen large enough to allow ofa certain and easy raising and lowering of the rolls. Chain-driveshould be altogether avoided, and the vertical shaft with bevel- THE RAW MATERIAL. 49 wheel gearing should be selected as the best arrangement. Thenormal speed of the rolls is 4 revs, per minute, but for friction-ing the lower rolls should be geared up so as to work with a. maximum speed-ratio of 1: 3. In large factories it is, however,always better to use, for proofing purposes, special calenders con-structed for the purpose, as illustrated in fig. 22, and to use theordinary calenders only for running sheet. It is of fundamental 4 50 RUBBER MANUFACTURE. importance that every set of calenders should be withreliable apparatus for heating and cooling the rolls, and that thecontrolling valves should be placed in a convenient , attention must be paid to apparatus for reeling and un-reeling, which should always accompany a set of calenders. Themethod still frequently employed for effecting these two purposes,consisting in the use of a simple wooden roller, on to which therubber sheet is still more simply wound by several workmen, isquite irrational. On a closer consideration of the process of run-ning a sheet of rubber, it will be found that in the case of the three-roll calenders the upper and middle rolls do the wo
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Keywords: ., bookcentury1900, bookdecade1910, bookidmanufactureo, bookyear1919
