(191) The process of combing is only carried out when the finer and better qualities of yarn, such as are used for thread and lace purposes, are spun. The production of these is conducted with greater care than is necessary with the ordinary quality, and it is essential that the short fibres and neps shall be removed. This can only be done to the extent required by a process of combing. It was pointed out in paragraph 23 that in Egyptian cotton a good many short fibres are found, and as the better qualities of yarn are spun from that class of cotton there is a great advantage to be derived from combing. Carding, as was shown, is a continuous process, while combing is an intermittent one, in which small portions of the fibre are dealt with separately and successively. The parallelisation of the fibres is very completely effected, and in addition they are, in a sense, sorted, all below a certain length being removed. It is true that the mechanism can be adjusted to treat fibres of various lengths, within certain limits, but once it is adjusted only the fibres which approximate to the fixed length pass onward through the machine. This procedure results, as will be very readily understood, in the production of a strong thread or yarn, as, in any portion of its length, the number of fibres contained in the cross section will be almost always the same. The nearly complete parallel order given to the fibres has the same effect, and tends to the production of a thread in which exists all the conditions of absolute strength. The combing machine is, with the exception of the mule, the most interesting from a mechanical point of view in the whole range of spinning machines. In the form which is mostly used it was invented by Heilmann, about 1845, and is best known by his name. Although many attempts have been made to construct machines on a different principle, they have not been more than moderately successful, and the Heilmann machine remains to-day the most approved one for the purpose.

(192) The carded slivers intended for use in the combing machine are first treated by a special set of machines, the object of which is to draw the fibres into an approximately parallel condition. It was remarked in paragraph 153 that, although the fibres in the sliver as it left the carding engine were in a more or less crossed condition, they were so openly laid that a slight endwise pull would draw them into a practically parallel order. In spinning ordinary yarns this is done by the drawing frames, which are described in the next chapter. Although the sliver eventually delivered from the combing machine is also drawn, it has been found desirable to commence this action before combing commences, and the result is that a sliver is produced which is exceptionally even and strong. The exact operation of drawing will not at this juncture be described, as it will be necessary to go over the same ground at a later stage.

(193) The first machine by which the slivers are treated is known as the Sliver Lap Machine, and as made by Messrs. Dobson and Barlow, is shown in perspective in Fig. 112. It consists essentially of drawing rollers, to the action of which the slivers are fed from the cans. From 12 to 16 slivers are treated at one time, and on their way from the guide plate to the rollers, they pass over the spoons formed at the ends of detector levers, this part of the mechanism being clearly shown. The failure of any one of the slivers causes the machine to be stopped as in the drawing frame, so that any unevenness in the lap is avoided. The slivers in passing the drawing rollers are laid side by side, and are in this way flattened, so that when they are delivered by the rollers, they have assumed the form of a ribbon, which is rolled up into a lap, by means of a specially driven roller. This treatment straightens the fibres, and prepares them for further treatment.

(194) This is given on the Ribbon Lap Machine, which is illustrated in Fig. 113. The laps obtained in previous machines are to the number of six, placed behind the drawing rollers in the machine. Four lines of rollers are provided, as in the drawing machine, and the laps are thus reduced in thickness until they become like a thin ribbon. By this time the various fibres of cotton are pulled into parallel order, and are in a good condition for combing. They are respectively guided round the curved plates shown, and are laid flat upon a highly polished iron plate. The lap which is delivered at the end of the machine furthest from the driving head is laid upon the plate first, and all the others are subsequently imposed upon it. The combined six laps are then passed through a pair of calender rollers at the end of the machine, by which they are compressed, and the combined lap is subsequently wound into rolls of 7¹/₂ or 8¹/₂ inches wide. These rolls or laps are fed to the combing machine. The chief advantages of this arrangement are those arising from the parallel order of the fibres. These are evenly laid in an uncrossed state, and there is consequently little danger of any rupture of them by the comb teeth. Further, the latter are not strained in the effort to disentangle the fibres, and a fruitful source of breakage is thus avoided. There is another point, to which special reference was made in Chapter V., namely, the equalisation of the thickness arising from the imposition of the laps upon each other.

(195) The lap being produced is placed upon two rollers, A A¹, as shown in Fig. 114, which is a transverse section through one head of a Heilmann machine, as made by Messrs. John Hetherington and Sons. Enlarged views of portions of the mechanism are shown in Figs. 115 and 116. A combing machine is usually constructed with from six to eight heads, the driving mechanism for all of which is placed at one end of the machine. The lap rollers A A¹ are positively rotated at a speed corresponding to that of the passage of the cotton through the machine. The lap as it is unrolled is carried along the trough B, made of its full width, the lower end of which terminates a little distance from the feed rollers C C¹. The bottom rollers of each head are suitably carried on brackets fixed to the roller beam, being made of steel, and a little longer than the width of the lap. They are fluted longitudinally, and drive the top rollers by frictional contact. The top rollers are also made of steel, being plainly cylindrical and covered with a sheath of cloth and leather, but a porcupine roller is often used instead of a pair of rollers. This, it is contended, opens the lap and decreases the waste. They are weighted by means of hooks on their axes, to which springs are attached. Immediately in front of the rollers the nipper is placed. This consists of two jaws, the upper one, D, being fastened to the lever E, which oscillates on the short shaft F, receiving its motion from a cam at the driving end of the machine through a shaft, short lever, and the connecting rod G. The lower jaw, H, is also made of steel, being rounded at its outer edge and covered with smooth leather. As the upper jaw is peculiarly fluted, as shown, the contact of the two establishes a nip of the cotton at the points of the flutes. The lower nipper blade, H, is fixed to two levers, I, which rock upon the shaft J. The spiral springs, K, are attached to the tail ends of the levers, I, and ordinarily keep the lower jaw in the position shown in Fig. 116, but also permit of it making a slight receding motion when pressed by the upper jaw after the nip is created.

(196) The foregoing portion of the machine constitutes what may be called the feed part, there being three distinct operations in the process—feeding, combing, and detaching. In front of the nipper the top comb, L, is fixed, being attached to the lever M in such a way that the necessary adjustment can be made. Below the nippers the comb cylinder N is placed, being constructed with a barrel or “comb stock,” to which is attached the comb needles. Of these there are seventeen rows, fixed in a metallic bed, or piece, known as the “half lap.” These should be accurately shaped, so as to be readily renewed or replaced when required, and are fastened to the comb stock by screws. The width of each row of combs is a little greater than that of the lap, and each row is parallel to the others. The needles are set at different pitches, beginning with one of ¹/₃₀th inch in the first row and terminating with one of ¹/₉₀th inch in the last. On the opposite side of the barrel a segment N¹ is fixed, which is fluted longitudinally. A circular brush, O, is fixed so as to clear the needles as they revolve, and can be easily set up so as always to be in touch with the combs. This brush revolves between the comb stock and the doffing cylinder P, and running at a higher velocity than the latter, it removes the waste taken from the cylinder and transfers it to the doffer, which is clothed with a metallic brush surface. An oscillating comb removes the waste from the doffer and beats it into a receptacle formed to receive it.

(197) The detaching portion of the mechanism consists of the three rollers Q S and T, but the fluted segment N¹ also aids in this portion of the work. The roller S is known as the “steel detaching” roller, and receives an intermittent motion in both directions from a cam at the end of the machine. The roller Q is known as the “top detaching” or the “leather” roller, and is covered with leather, being borne by levers R, to which the necessary oscillation is given by a cam and the connecting rod R¹. The heads of the levers R are arranged with a block and setting screw, by which the period of contact of the roller Q and segment N¹ is regulated. The movement of Q is round the detaching roller towards the comb cylinder until it comes in contact with the fluted segment N¹, after which it is again returned to its original position. The top roller T is made brass-covered, having longitudinal flutes, and is of sufficient weight to nip the sliver firmly. It, of course, receives its rotary motion from the detaching roller, and is carried in a lever known as the “horse tail.” After passing the rollers S T the combed sliver is carried along a trough through a trumpet-shaped guide to the calender rolls U V, which deliver it on to a highly-polished plate. It is thus guided to a draw box at the front of the machine, in which are drawing rollers, and is then passed into a coiler, as in the carding engine, being delivered into similar cans.

(198) Having thus described the mechanism employed, its method of action can now be explained. The lap, being passed to the feed rollers, is delivered by them intermittently in short lengths corresponding to that of the staple. This intermittent rotation is obtained by the use of a star wheel, which is revolved by a train of gearing from the cylinder shaft. The extent of the forward movement is regulated by the length of the fibre, the roller making such a portion of a revolution as causes its surface to move that distance, usually from ¹/₈th to ¹/₁₀th of a revolution. The roller being one inch diameter, the relative distance its surface would travel, and the length of fibre delivered in each case, would be ·39 or ·31 inch. The nipper jaw D, while this movement is being made, is open, and the top comb L is dropped. As soon as the rotation of the feed rollers ceases the nipper closes and grips the fibre. The downward movement of the top nipper blade D is, however, continued beyond that point, and the lower jaw H receives a further downward movement which puts the helical springs K into tension. In the ordinary position of the nippers the comb needles in their revolution would pass the cotton, but the recession of the nipper, as described, brings the uncombed end of the lap into the path of the needles, which accordingly pass through and comb it. It may be here explained that after the process of combing the combed and uncombed parts of the lap are separated, and that, after the free end of the latter is combed, a small portion is pulled away from it, and joined to the previously combed portion in the manner about to be described. For convenience it will be as well to refer to the uncombed cotton as the lap, and to the combed cotton as the sliver.

(199) The circular combs having passed, the continued revolution of the nipper cam allows the nipper to again move forward, and to carry the combed end of the lap into a position in which it can be dealt with by the fluted segment N¹. The top comb L drops into the lap at a point in advance of the uncombed portion, and the leather roller Q at the same time is moved round the detaching roller S. As the fluted segment N¹ comes under the cotton the leather roller engages with it, and the continued revolution of the former causes the two to act as a sort of revolving nipper. The nipper D has been previously opened and a tuft of cotton is drawn away from the lap, partially by the action of the segment and leather roller. To the latter a peculiar motion is given by a cam, which acts through special mechanism. It is not enough that the combed tuft should be detached from the lap, but it must also be attached to the sliver. In order to effect this the detaching roller moves backward to the amount of one-third of a revolution, previously to the engagement of Q with N¹. This, of course, carries a corresponding length of the sliver with it, and lays the free end of the combed tuft on to the free end of the sliver, to which it is at once attached by the pressure of the leather roller Q. The backward motion of the detaching roller commences after the combs have passed through the lap end, before which it is stationary. The piecing being complete, the segment N¹ and leather roller Q recede from each other, and the detaching roller makes a forward movement of two-thirds of a revolution. This results in the complete attachment of a tuft of cotton, the uncombed part of which is drawn through the top comb, this preventing the passage of short fibres and nep, which are retained in the lap, and removed by the next passage of the rotating combs. The attachment having been accomplished the detaching roller becomes stationary, the top comb is raised, a fresh portion of lap is fed, and the process is recommenced.

(200) There are thus three distinct stages in combing, viz., the feeding, combing, and detaching, and in the course of the operation the tuft of cotton is completely separated from the lap, and joined to the sliver. It is, of course, absolutely necessary in a machine the movements of which are so delicate, to establish and maintain a very accurate setting. For this reason ample provision is made by which the adjustment of the various parts can be accurately effected, as a reference to Fig. 114 will show. Although the motion given by the cams is of necessity a positive one, and its range fixed to suit the material, the timing of the movements of the different portions of the mechanism is secured by the facilities named. The full importance of this power will be appreciated when it it is stated that from 80 to 95 “nips” or beats are made per minute. Without the most delicate setting it would be impossible to ensure successful work, and this explains the reason for the many adjusting screws shown in Fig. 114.

(201) In treating of the carding engine it was explained that the production of an even sliver was of high importance. This is equally so in the combing machine. It has been explained that the cotton is held by the nipper jaws, while the projecting end of the lap is combed, and it will be readily understood that this action will tend to widen or flatten it a little. This result is also produced by the action of the feed and detaching rollers. Thus a sliver is produced with uneven edges, which is very undesirable. In order to remedy this, Messrs. John Hetherington and Sons have adopted the device which is shown in front elevation and section in Figs. 117 and 118. In this case the lower nipper jaw, or cushion plate A, has attached to it at each side a guide plate, which has two projecting pieces C D, one at the front and the other at the back of the nipper. D is curved so as to allow the jaw B to descend without difficulty. The two guiding portions C and D are coupled by a connecting piece E so as to form one casting. The nipper plate is cut away, as shown at F, to clear the front guide, which is arranged so as to be in contact with the front edge of the cushion plate A. By this arrangement it is practically impossible for the fibres to escape sideways as the lap is nipped. The length of the nipper plate is sufficient to hold all the fibres firmly, thus ensuring their perfect combing. The fibres are prevented from lifting during the descent of the nipper by a small projecting piece and by the back guide D. The cylinder is also formed with a flange to obviate spreading. By these arrangements a wider lap can be used than would otherwise be the case, and the amount of cotton passed is therefore greater. In addition to this the selvedge is much more even, and the sliver produced in better condition for drawing.

(202) In Fig. 119 a perspective view, and in Fig. 120 a sectional view is given of Messrs. Dobson and Barlow’s Heilmann combing machine. In the main it is similar to the machine previously described, but there are some alterations in detail which require explanation. One of these is shown in elevation and plan in Figs. 121 and 122, and is an improvement in the mode of working the detaching rollers, which it was shown have to revolve a little distance in each direction alternately. This motion is placed at the end of the machine, and consists of a large cam F, which is suitably driven and with which a bowl fastened in quadrant C engages. C is formed on its outer edge with a toothed rack, which engages with the pinion B, loose and sliding upon the spindle of the detaching roller C¹. B is part of a toothed clutch, as shown at E, and has a ring groove formed on its boss, with which a claw at the end of the lever G engages. The sliding half of the clutch is usually drawn inwards by the spiral spring shown in the plan, so that the normal tendency of the two parts is to engage. At the end of the lever G a pin carrying a bowl is fastened, the latter being constantly in contact with a cam surface fixed on the shaft on which the cam F is secured. The action of this mechanism is easily understood. The cam surface which actuates the lever G at the moment when the detachment of the tuft of cotton is completed, allows the clutch to become engaged. Simultaneously with this the cam F causes the quadrant to make its stroke, and thus rotate the detaching roller C¹ as much as is required when the lever G is moved, so as to disengage the clutch, and the detaching roller is free to revolve. The advantage of this motion is principally its simplicity, which causes it to be easily worked at a high speed without endangering its positive action. It can readily be adjusted to suit different staples of cotton, without any change pieces.

(203) Referring now more particularly to Fig. 120, it will be noticed that a change is made in the construction of the nippers. In the machine as usually constructed, the lower blade H is used as a cushion, being covered with leather, an operation which is a somewhat delicate and difficult one. In Messrs. Dobson’s machine the lower nipper blade H is made a somewhat blunt V shape, while the upper blade or knife D is fitted with a narrow strip of india-rubber or leather. The nip is obtained between these surfaces, and owing to the yielding nature of the strip, an efficient grip is always established. As a corollary of this the lower nipper blade D is fixed, and does not yield as in the ordinary mode of construction. The cam for working the nipper is shown at K, and its motion is communicated through the lever and rod G. Its shape is such that it works easily and smoothly without any difficulty, at a speed of from 80 to 95 nips per minute.

(204) In order to avoid misapprehension, it may be as well to say at this point that the mechanism employed being similar to that in the ordinary machine, the various parts are all marked with the same reference letters in each case. The cotton is marked Z and its passage through the machine can be clearly followed. This will avoid any special reference to the mechanism common to both machines. The leather roller Q is in this case carried at the ends of two levers R, which are coupled directly to the lever W, which receives the necessary reciprocal motion, and the joint X at the end of W is so arranged, that it can be very readily set. The setting is very easily made, and as the operation of the “leather” or “piecing” roller is one of the most delicate in the machine, any means by which this can be more readily adjusted is of importance. The top roller T is made of a large size, so as to press well down upon the detaching roller, and not to vibrate, however high the speed of the machine may be. A minor improvement is made by arranging that as the bristles of the cleaning brush wear, they can be driven at a quicker speed.

(205) Although the Heilmann machine has been in use for about 40 years, it is a singular fact that no other machine for the same purpose has had anything like the same success. A machine, invented by Mons. Imbs, has been used to a certain extent on the Continent, but it has not been adopted except in a small percentage of the cases in which the Heilmann has been used. A machine, which is extremely ingenious in its mechanism, and which has been a little used for short stapled cotton, is the joint invention of Messrs. Pinel, Lecoeur, and Hetherington. In this machine the principle of a revolving nipper is adopted. A long pipe forms the main moving piece of the machine, and is of sufficient length to constitute six heads, its circumference being divided into three parts. For each head three longitudinal slots are cut in the pipe equal in length to the width of the lap. Three sets of nippers are fitted to each head, the fixed jaw of each coming up to the edge of the slot, which, when the nipper is closed, is covered by the loose jaw. When the nipper is open the slot is exposed. Between each pair of nippers is placed a comb segment with thirteen rows of needles. A feed nipper presents the end of the lap to the needles, the pipe then revolving at its highest speed. When the end of the lap has been combed the revolving nipper comes opposite the feed nipper, which is stationary, and the pipe revolves at a slower speed to allow the combed end of the lap to be drawn into the nipper. This is effected by the suction of an air current induced by a fan connected to the tube. This operation being completed, the revolving nipper closes on the lap and the feed nipper allows a short length of lap to be taken through. The separation of the tuft is then made, and its other end is combed by being drawn through a top comb as in the Heilmann. The pipe then continues to revolve, and while the next in the series of nippers is taking its feed, the one holding the combed tuft opens slightly on arriving at a table placed at the front of the machine. By the aid of a pusher the fibres are superposed on those already on the table, a continuous fleece being thus made which is taken forward by two pairs of draw rollers. The sliver is made exactly as in the Heilmann. The Lecoeur machine is not suitable for long stapled cotton, but it will comb very effectively the short Indian and American staples. Of these it will produce 400lbs. per week, with a per centage of waste of from 16 to 20. It is only in special cases that the combing of this class of cotton is remunerative.

(206) The waste from the combs, which varies from 15 to 17 per cent, is carried away by the brush, which in turn is stripped by a comb, and the strippings fall upon a lattice. By this they are carried to a calender roll and made into a lap which, as it contains fibres of good quality, but of insufficient length for the ordinary combed yarns, is used up in the manufacture of coarser qualities. The waste from the combing machine being considerable, its utilisation is important.