Page:EB1911 - Volume 23.djvu/753

Rh sequence of operations is very similar to that described for the simple hand-wheel.

Machine or Factory Rope-Making.—The most modern methods of rope-making are far superior to the foregoing, which, as stated, have been introduced to show the principle. One of the greatest drawbacks in the formation of a strand from a haul or chain, even for a small number of yarns, is the irregularity of the tension of the yarns at different parts of the strand. If a large number of yarns be required for each strand, it would be almost impossible to make a satisfactory rope by the above system. If, however, the strand be made from bobbins, each yarn bears its proper share of the tension, and an almost perfect rope is obtained.

Two mechanical methods are in use for the spinning of long vegetable fibres—the ordinary and the special. When flax or jute yarns are required, they are almost invariably spun on the ordinary spinning frames, and the yarn rewound from the spinning bobbins on warping bobbins, or else rewound in the shape of rolls or cheeses. Hemp yarns, especially the finer kinds, are sometimes treated in the same manner, but Manila hemp, New Zealand hemp (Phormium), and similar fibres, are invariably spun on bobbins by special machinery. The strands for light ropes may then be made on the twisting frames, and the rope finished on what is called a “house machine.” When a large rope is desired, at slightly different method is usually employed. The bobbins from the automatic spinner, or the rolls from the winding frame, are placed upon pegs in a frame which answers the same purpose as a bank or creel used in conjunction with a warping machine. If the rope is to be say 3 in. in circumference, there may be, with fine yarns, 300 or more individual threads in its composition. Suppose that 300 threads are to be used, then 300 bobbins would be placed on the pegs of the bobbin bank or creel, and divided into three sets of too threads each for a three-strand rope. The threads are passed separately through a register plate, which is simply a plate containing a sufficient number of holes for the maximum quantity required, and arranged in a series of concentric circles. There are three sets of concentric rings used in the plate for a three-strand rope, and four sets for one of four strands. As the threads emerge from the register plate they are grouped together and passed through a tapered tube, the sectional area of the smaller end of the tube being equal to the sectional area of the strand. This operation is done for each group of 100 threads, and finally the three or four groups are attached to separate rotating hooks of the forming machine or “traveller.” As the latter moves down the walk on rails, it draws the threads from the bobbins in the bank, and through the register plate and tubes, while the hooks put in the twist. A perfectly circular strand, without slack threads, is thus formed; and, at the same time, a uniform strand is obtained, since the ratio of the speed of the traveller to the number of turns per inch of the hooks is constant. The process is continued until the desired length of strand is made—about 150 fathoms (300 yds.) of each of the three strands are required for 100 to 120 fathoms of rope—then a little more twist is introduced. Afterwards, all three strands are placed on one hook of the traveller, and the ends from the shaping tubes are cut off and put on the hooks of the fixed machine, called the “fore-turn.” The carriage containing the “top” is now brought close to the traveller, and the strands are placed in the grooves of the top as explained under hand-laying. Similar means to those used in hand-spinning are adopted for keeping the rope off the ground. The two machines are now started, the three hooks of the fore-turn machine revolving in one direction and the single hook of the traveller revolving in the opposite direction. Simultaneously the carriage with the laying top moves forward towards the head of the walk.

Fig. 9, Plate I., shows many stages in the process of rope-making. The most prominent part shows the carriage with the top in position approaching the fore-turn machine at the head of the walk. The person on the right of the carriage is holding a top in his left hand, while the top in the carriage is laying a rope of four strands. At other parts of the figure appear three or four travellers, some twisting the strands, others moving up the walk as the laying proceeds, while on the extreme right one machine is laying two ropes, of three strands each, at the same time.

We have already stated that the yarns for the above machine may be prepared by two systems. When the hemp fibre is spun on the ordinary frame, the method of preparation for such a frame is somewhat similar to that employed for flax, but since the fibre is harsher than flax, it invariably requires softening. The softening machines crush the streaks as in the case of jute, but the fluted rollers are arranged to form part of a circle. The coarser fibres receive a somewhat different treatment; the first process in the reparation of Manila hemp and similar fibres used for rope yarn is illustrated in fig. 10, Plate I. The streaks are clearly shown as being led between fluted rollers on to the pins of the hackling and spreading machine; the lanterns or skeleton rollers, seen on the extreme right, press the fibres into the pins. A little oil is made to drop on to the fibre in order to soften it and to facilitate the operation. The oiling apparatus is usually of a simple character, and consists of a revolving roller partly immersed in an oil bath. The roller is driven as shown in the figure, and the oil which it draws up is scraped off its surface by a knife-edge, and led, by means of a sheet, upon the fibre between the fluted rollers and the gill-pins. A view of a similar machine is shown in fig. 11, Plate II., from which it will be seen that there are two sheets of revolving gill-pins. The sheet nearest the feed-cloth revolves slightly quicker than the surface speed of the fluted feed rollers, while the second sheet moves at a much higher rate. The difference in the speeds of the gill-pins results in the fibre being combed out and straightened, while the delivery rollers, the surface speed of which is slightly greater than that of the second sheet of gill-pins, help further to complete the process, and finally deliver the fibre in the form of a broad ribbon, termed a sliver.

In general, three such machines are used for the process; the pins in the gill-sheets are graded, those in the second machine being finer and more closely set than those in the first machine, while a still finer and closer arrangement obtains in the third machine. The slivers from the third hackling and spreading machine are now placed at the back of the first drawing frame, one type of which appears in fig. 12, Plate II. Each sliver is passed separately over a guide pulley, led upon the pins, drawn out and joined by others, and finally delivered as a sliver ready for the second drawing frame. A similar process is carried on in this machine, from which the sliver emerges ready for the spinning frame. It will thus be seen that a system of doubling, as well as of drawing, obtains in these processes as in flax-preparing; such a system is adopted in order to obtain uniformity of sliver and the correct weight.

The slivers are taken from the drawing frame to the automatic spinner—a beautiful piece of mechanism. Fig. 13, Plate II., illustrates the machine as it leaves the makers. Two sliver cans from the second drawing frame are placed behind the machine, and the slivers passed between the rollers. They are then deflected and made to enter a trumpet-mouthed conductor which guides them on to the pins of the chain-sheet. As the two slivers emerge from these pins, each enters a separate self-feeding and adjusting apparatus, the function of which is, as its name implies, to regulate the delivery of the sliver to the nippers. The delivery is increased or decreased according as the sliver is thin or thick. Consequently, a very even yarn results; indeed, it is claimed that for uniformity of yarn this system of spinning has no equal. The bobbins, which