Elastic and Non-Elastic Narrow FabricsChapter I.Growth of Webbing Business—Attempts to Substitute Cut Products for Individually Woven Webs Made on Gang Looms—Loom Setting to Reduce Vibration—Capacity of Looms and Explanation of the Various Motions That Are Employed
Growth of Webbing Business—Attempts to Substitute Cut Products for Individually Woven Webs Made on Gang Looms—Loom Setting to Reduce Vibration—Capacity of Looms and Explanation of the Various Motions That Are Employed
When we think of the discovery of rubber vulcanization and the effect it has had on world affairs our minds naturally turn to the big things, such as the automobile industry with its millions of rubber tires in constant use. These may crowd from our notice a thousand and one smaller things of importance. It is difficult to fully realize how many comforts and conveniences we derive from rubber and not the least among them is the multiplicity of woven fabrics which are used both for comfort and convenience in a variety of ways and for innumerable purposes. It is not only in such things as garters and suspenders, with which our minds may first associate elastic webs, that these fabrics are used, but they find employment in a variety of other products, which are growing more numerous all the time. Today there are in operation thousands of looms and braiders, in which many millions of dollars are invested and in the operation of which, together with complementary machinery, about ten thousand people are employed.
It was about the year 1840 when the idea of weaving threads of elastic in connection with other materials was first conceived. After long experiments this was accomplished in the very simplest form of weaving. New ideas were from time to time introduced, and new uses found for the product, until now it covers a large variety of both plain and fancy weaves, and the multiplicity of uses are so varied that few realize them who are not closely associated with the business.
It was not until about the year 1860 that elastic web weaving was introduced into this country, although for a number of years previous England and Germany, and also France in a small way, had found here a market for their product, particularly in cords, braids and shoe goring, which at that particular time was fast growing in popularity. About 1860, a few looms which had been used, were brought over from England and located at Easthampton, Mass., and the manufacture of shoe goring commenced. The rubber thread required was for some time imported from England. The business grew rapidly, and factories were established in a number of cities, more particularly at Boston, Lowell and Brockton, Mass., Bridgeport, Conn., and Camden, N. J. An unfortunate labor dispute took place about the year 1890, which developed into a long-drawn out strike, ultimately precipitating friction between the shoe trade and the goring web manufacturers, which finally ended in a positive boycott of this product from which the trade has never recovered. Most of the looms which were up to this time devoted to shoe goring have been remodeled and are now used in the making of other types of elastic fabrics. In passing, it may be interesting to note that some of the looms originally brought from England 60 years ago are still in operation and doing excellent work along other lines.
Attempts have been made from time to time to weave elastics on wide looms, the cloth being divided at intervals by open spaces in the warps at the front reed, at either side of which spaces binding threads were woven in. These narrow strips were spaced in the front reed according to the different widths which might be required, and could easily be changed to meet the varying requirements by redrawing a few threads, inasmuch as the whole weave was uniform throughout the full width of the cloth. Between these spaces, but at a point away from the weaving line, were arranged stationary knives by which the cloth was cut into the requisite widths while it was being woven, and as it gradually passed by the knife edges. These knives were so arranged that they could be adjusted to new positions when it became necessary to change the widths of the individual strips.
While this method was more economical than weaving individual webs in gang looms, the labor cost being much less, the narrow webs produced having the cut selvages lacked the finished appearance which the individually woven webs had. And sometimes the binding threads would give way, so that the fabrics were not well received by the trade, and ultimately the demand for them died out.
Attempts were made to supersede the individually woven strips in another direction by the use of two finely woven pieces of cloth, one to form the back, and the other to form the face of the goods, with an elastic substance mechanically stretched out and inserted between the two. These different parts were calendered together and afterward cut into strips of the desired widths. This method was not without many advantages. Strips of different widths were easily made without the costly method of redrawing the warps in the looms. An unlimited choice of both plain and fancy fabrics could be used, having if desired distinctly different appearances and constructions for face and back, and this alone opened up a wide range of possibilities. The finished cloth lent itself admirably to fancy embossing and printing and to various other forms of elaboration. But somehow the trade did not take to it, and this also finally died out.
The trade ultimately settled down to the weaving of elastic goods of all kinds, both plains and fancies, in gang looms, and the business has steadily grown ever since along these lines.
The looms employed are very varied, inasmuch as the requirements cover a wide range and new uses are constantly arising with new demands. The simplest form of weaving is that employed on the making of webs such as are mostly used for garters, and which are also used for many other simple purposes in nearly every household. These webs are commonly known as loom webs, lisles and cables. They are generally made on plain, narrow, cam looms, some of which are capable of accommodating as many as 56 pieces or strips at one time.
There are two distinct types of loom employed, one of which is known as the straight shuttle and the other the circular shuttle loom. In the former type, the straight shuttle, in traveling across the different spaces, takes up more room than the circular shuttle, and thus somewhat curtails the number of pieces which can be operated in the loom, limiting capacity of production, and relatively increasing the cost. Very few of the straight shuttle looms accommodate more than 36 shuttles, according to the width of the goods required. The circular shuttles travel over a segment of a circle and cross over each other’s tracks in their movement through the shed, as shown in Fig. 1. This permits the crowding of the pieces of web closer together, so that many more can be accommodated in the same loom space than when the straight shuttle is used. This type sometimes runs as high as 56 shuttles to the loom.
Fig. 1.—Circular Shuttle Webbing Loom
Fig. 1.—Circular Shuttle Webbing Loom
Fig. 2.—Rack and Pinion Movement for Actuating Shuttles
Fig. 2.—Rack and Pinion Movement for Actuating Shuttles
These looms often are speeded as high as 180 picks per minute. To operate at this speed with so many pieces of web and make satisfactory goods, free from thick and thin places through irregularities of speed or variable momentum in running, a very heavy type of loom is necessary. They should be erected on solid foundations so as to eliminate all possible vibration. A solid concrete floor into which timbers have been properly set so that the feet of the looms may be securely anchored into them is the ideal way, but where this is not practicable at least heavy foundation timbers for anchoring the loom feet to should be arranged. The frames of the looms should be heavy; also the main driving shaft, which should have wide bearings so as to prolong the life of the shaft at the wearing points and obviate loose play in the boxes.
The crankshafts must also be very heavy and there should be enough of them so as to rigidly withstand the repeated beat of the lay without liability to take on any loose motion, which would be fatal to the production of perfect goods. Weight and strength here is very essential, inasmuch as it is not practical to get a direct line from the shaft to the lay on account of the harness movement, and they must be built to drop below the harnesses which form makes them subject to heavy strain at the beat of the lay. They should also be made adjustable, each arm having a heavy left and right threaded insert, so that the length of the weaving line may be changed to meet the varying requirements of different webs. They should also be constructed so that any wear may be taken up.
The lay itself must necessarily be very heavy. It is generally constructed of several thicknesses of timber of different kinds, so as to avoid any possibility of warping and shrinkage. The shuttles used are mostly made of applewood. While they must run smooth and be free from the risk of slivers they must at the same time be very light so as to be freely drawn across the multiple of web spaces. It will be easily seen that the drawing of so many shuttles over a space of about three times their length, at possibly 180 picks per minute, carrying and delivering the necessary weft to the webs, each thread of weft being checked to a certain extent by friction springs, requires great care and thought in construction. Shuttle wood must be thoroughly seasoned by age or it will not serve the purpose.
The shuttles themselves are very ingeniously constructed so as to accommodate the greatest possible amount of filling, together with the necessary space for springs to properly manipulate the tensions. Each shuttle is bored through at either side so as to allow for the insertion of a fine recoil spring, which is made fast at one end of the drilled hole at the back of the shuttle. To the other end of the spring is attached a small porcelain eye, through which is threaded the weft, making it possible to govern and take up by the action of the spring the loose filling which is thrown off as the shuttle passes and repasses through the shed. These side recoil springs are not only useful for the taking up of the loose filling but allow for a variety of threading up methods, so as to assist in the governing of the tension of the weft at one or both sides of the web, and thus afford a means of weaving the goods level. They aid in correcting any tendency to long and short sided goods, of which we will say more later.
At the back of the quill or shuttle spool is arranged another springon which is swivelled a porcelain device which presses against the quill, and can be so regulated as to govern the tension. This spring is so tempered that the most delicate adjustment of tension can be made.
The shuttles across the entire width of the loom are drawn to and fro by what is known as the rack and pinion movement. (See Fig. 2). This method has pretty generally superseded the old-time plan of rise and fall pegs. The rack runs back and forth in a slot grooved in the top of the lay bed, A, the entire length of the loom. To the rack is attached leather straps G, or heavily woven fabric straps, with which the rack B is pulled to and fro at each pick of the loom. The rack is of wood, having rounded teeth-paced approximately one-third of an inch apart. Into the rack are meshed pinions C, two to carry each shuttle E, the teeth of which are correspondingly spaced. The rack is set into a wood carrier which is about one inch deep and one inch wide, and the full length of the lay. The pinions are made of either raw hide or paper fibre, and these pinions again mesh into a series of racks D, grooved in on the under side of each shuttle, and thus drive the shuttle to and fro across the web spaces J.
The constant travel of the driving rack running in the groove at the top of the lay bed necessarily produces more or less wear at the bottom of the rack. It therefore is advisable to place underneath this rack a false bottom of wood of about ¼-inch thick, which after becoming worn by constant use and contact with the ever-moving rack may be easily taken out and replaced by a new one, thus keeping the rack and pinions and shuttles at all times in proper mesh with each other.
The rack is drawn backwards and forwards by the before-mentioned straps, which are passed over pulleys and are either fastened to the rack by means of wood screws, or securely locked with a metal clamp designed for this purpose. These straps are sometimes separated by a pair of cams set on a shaft making one revolution to each two picks of the loom. The power from these cams is first communicated to eccentrically-shaped wood pulleys, moving backwards and forwards, which are so formed as to start and stop the shuttles slowly, and to operate them at a higher rate of speed during their passage through the middle of the shed. This movement is necessary to avoid a too early entrance of the shuttle into the weaving shed before the harness is properly settled, and also to soften the hammering at the close of its travel so as to reduce the wear and tear.
It might be well to note here also that this hammering is also softened by the placing of a piece of soft rubber H at each end of the rack run, so that the rack strikes this soft cushion each time it goes home. While the cam method has been extensively used to produce the kind of movement most desirable for the travel of the shuttle, it has its drawback in the momentum produced, which it is often found difficult to control.
The Crompton & Knowles Loom Works have designed a shuttle motion which effectively governs the desired speeds in the travel of the shuttles while they are entering, passing through, and leaving the shed, by a dwelling movement operated by a series of gear wheels and oscillating slotted rocker. It is absolutely positive in action and does away with the uncontrollable and erratic movement so often met with in the cam drive.
Four-pick cams are all that are necessary to produce the plain webs which are used for ordinary purposes. However, it is not the practice to confine looms to the limitations of this capacity, but to put in either 8 or 12-pick cams. These, besides providing means to make the plain weave, open up possibilities for a number of other weaves and combinations of weaves, which add materially to the usefulness of the loom.
Fig. 3.—Direct Cam Movement
Fig. 3.—Direct Cam Movement
Fig. 4.—Loom with Side Cam Method of Harness Control
Fig. 4.—Loom with Side Cam Method of Harness Control
There are two distinct types of cam movements used in looms of this character for the making of ordinary webs. One is known as the direct cam drive, where the cams are fitted on a 4 to 1 shaft, as shown in Fig. 3, which runs lengthwise of the loom and from which the power is communicated to the harnesses through a series of levers A, rocking poles B, levers C, and lifting wires to the harness D.
The other movement is known as the end-cam method, where a small shaft is set at the end of the loom, running at right angles to the driving shaft (See Fig. 4) from which it is driven by bevel gears. On this short shaft are set the cams, usually 8 or 12 in number, which have a series of grooves at their center so as to afford means of timing them in different positions on a feather key which runs the full length of the shaft. These cams operate what is known as the cam jacks, which may also be seen in Fig. 4.
The jacks are hung at the middle and are moved backwards and forwards by the cams, communicating movement to the various harnesses. The harnesses are connected at both the top and bottom of the jacks. This connection at both ends of the jacks makes it possible to run the looms at a very high rate of speed, as there are no weights or springs to contend with, which limits speed.
While the first described method of direct cams has some advantages over the end cams, such looms are not nearly so economical to operate as the end cams on account of the limited speed attainable. While the harnesses are lifted by means of the cams they have to be pulled down by weights or springs. The means of shed adjustment, however, enables the attaining of a well graded shed. Furthermore, the cams themselves can be so set on the shaft as to afford means of timing the movements of the different harnesses so that excellent and easy shedding results may be obtained. But the one great disadvantage is the limitation of the weaves attainable, which limitation is largely overcome by the end-cam method.
When the direct cam movement is used, and where the goods being woven are of such a character as to demand a very slow speed of the loom, it is practicable to bring the harnesses down by weighting them with wide flat weights of the requisite size. But where higher speed is required than is advisable for weighted harnesses, springs are more desirable.
The simplest form of pulling do the harnesses is by the use of floor blocks and direct springs. There is, however, a disadvantage in using the direct spring on account of the pull increasing until the extreme lift of the harness is reached, which necessarily increases materially the power expended in operating same and makes an unnecessary strain. The better way is to use what is known as spring jacks, which have an easier pull than the direct spring inasmuch as the load eases off on the pull, diminishing from the greatest pull at the start to the lightest pull at the extreme lift on the lever, so that the load is uniformly distributed all through the movement and less power is employed.