US2323882A - Drafting mechanism for roving frames - Google Patents

Description

July 6, 1943, B. c. SHAW DRAF TING MECHANISM FOR ROVING FRAMES Filed Apiil 24, 1941 2 Sheets-Sheet l QIMHUHHHHWHHr' July 6, 1943. B. c. SHAW 1 2,323,832

' DRAFTING MECHANISM FOR ROVING FRAMES Filed April 24, 1941 2 Sheets-Sheet 2 Patented July ,6, 1943 DRAFTING MECHANISM F OR ROVING FRAMES Benjamin C. Shaw. Saco. Maine, assignor to Saco-Loweli Shops, Boston, Mass., a corporation of Maine Application April 24, 1941, Serial No. 390,089

(Cl. l9130) 13 Claims.

This invention relates to roving frames. As is well understood by those skilled in the art of manufacturing cotton textiles, the sliver delivered by a card usually is subsequently subjected to one or more drawing operations and then goes to a roving frame which prepares it for delivery to a spinning frame. The roving frame includes a drawing mechanism which drafts or attenuates the strands of sliver, both for the purpose of disposing the fibers in a more nearly parallel relationship to each other and also reducing the cross-sectional dimensions of the strands to those suitable for the next succeeding operation.

A serious dimculty in drafting cotton and similar slivers is to maintain that control of the fibers necessary to produce a roving having the desired degree of uniformity, In other words, as the fibers are drawn out there is a strong. tendency for them to bunch and thus to produce a product that varies greatly in cross-sectional dimensions and in the number of fibers present in successive portions of the-strand. In fact, close examination of commercial rovings shows a sur prising degree of irregularity or non-uniformity amounting, at times. to as much as 200% or 300% in the same roving. It is obvious that when such a roving is twisted into a yarn the inch for inch strength of that yam will vary correspondingly, or perhaps to an even higher degree, so that this matter of uniformity in the roving is extremely important in producing a yarn ofgood quality.

The present invention deals particularly with these conditions, and it aims to devise a drafting mechanism for roving frames which will be exceptionally simple in construction, reliable in operation, easy to'take care of, and will be so organized as to maintain an exceptionally high degree of control of the fibers as the strands are drawn out and attenuated.

The nature of the invention will bereadily understood from the following description when read in connection with the accompanying drawings, and the novel features will be particularly pointed out in the appended claims.

In thedrawings,

Figure 1 is a vertical, sectional view, partly in elevation, of a drawing mechanism constructed in accordance with this invention;

Fig. 2 is a similar view but the plane of section being taken through the necks of the drawing rolls; and

- Fig. 3 is a sectional view on the lin 3-3, Fig. 1, with the rolls" shown partly in elevation and partly in section. v

The construction shown in the drawings comprises a pair of top and bottom front rolls 2 and 3, respectively, a second pair of top and bottom rolls 4 and 5, and a pair of rear rolls t and I. These rolls are arranged in series so that a strand rolls.

of roving fed through them is drawn between the rear and middle rolls and again between the latter rolls and the front rolls. Between the first and second bottom rolls is an intermediate bottom roll 8, preferably smaller in. diameter than the other bottom rolls, and it is mounted closely adjacent to the lower surface of the second top roll 4.

All of the bottom rolls are supported in bearing blocks mounted in a roll'stand ill for relative adjustment to vary the roll spacing as may be required for different staples, and these rolls are driven from gearing usually mounted at one end of the frame. Such gearing has provision for adjustment to change the draft exerted on the sliver as it travels through the rolls. The top rolls are held in spaced relationship to each other by a suitable cap bar it equipped with adjustable guiding blocks for the front and rear rolls, as is customary in mechanisms of this character. Also, a weighting mechanism is provided to maintain the roll 4 pressed continuously against its cooperating lower roll 5 so that a firm-bite is provided between them enabling these rolls to draw the fibers fromthe rear rolls 5 and l, and also to exert the necessary holding action on the sliver while the front rolls 2 and 3 perform their drawing function.- In addition, this weighting mechanism acts on the front and rear rolls to maintain firm bites on the sliver as it is fed by them.

Since the slivers fed to a roving frame are almost entirely devoid of twist, a substantial draft in the neighborhood of, say, 2% or 3, is customarily applied between the rear and middle rolls, and a higher draft such, for example, as 5 or 6, may be used between the middle and front The chief difficulty in the control of the fibers, therefore, is in the front draft,

The present invention solves this difilculty by so mounting the intermediate lower roll 8 and the second top roll a that they are always spaced apart by a small distance, say five or ten thousandths of an inch. For this purpose two spacing collars l3--fi3; best shown in Fig. 3, are mounted for rotation on the gudgeons projecting from the opposite ends of the top roll t and the peripheral edges of these collars rest on the reduced portions of the bottom intermediate roll .8. These parts are made of such dimensions that the desired minimum spacing will be maintained between the bosses t-& of the upper roll and those of the lower roll.

This arrangement has been found to produce exceptionally uniform roving, and experiments have shown that this is due directly to the spaced relationship of the intermediate lower roll 8 to the top roll 4. The reasons for this favorable result are somewhat obscure. The best explanation which I am able to give at this time is that the rolls I and 8 cooperate to exert a limited com- I such travel and for a distance after leaving pressing action on the fibers in the region between the front andmiddle firm bites where the maximum movement of the fibers over each other presumably is taking place. As the front rolls draw the fibers through the restricted space between the rolls 4 and 8, any transversely disposed ends between this space and the middle firm bite are yieldingly restrained so that the I drawing action tends to straighten them out. The higher surface speed of the bottom roll 8, as compared to that of its cooperating roll 4, also contributes to this fiber straightening action.

The shorter fibers which momentarily are not gripped at either bite can only be drawn forward by their contact with longer fibers. There is a strong tendency for the free ends of any of the fibers to spring out away from the main body of the sliver, if they are free to do so, probably due to the presence of static charges created by the movements of the slivers over each other. The pressure applied to the slivers by the rolls 4 and 8 controls this action and, in addition, it presses the shorter fibers more firmly into contact with the longer ones so that the latter can carry them along.

In addition, it should be observed that as any.

of the fibers leave the middle bite, the portion of the sliver of which they form a part is held for a considerable distance in contact with the peripheral surface of the top the latter roll, this part of the sliver is held in contact with the peripheral surface of the lower roll 8. The angle of this contact with the upper roll should be between 45 and 60 and with the lower roll should be in the neighborhood of as in the arrangement shown, so that so long as the slivers are in contact with the surface of either of these two rolls and are being drawn through the reversely curved path provided by these rolls, they are still under a restraining pressure which tends to hold the shorter fibers in contact with the longer ones and thus to assist in making the short fibers travel with the longer ones. This action thus contributes to the production of a more uniform sliver.

A further factor which is believed to contribute to the favorable-results produced by this mechanism is that the surfaces between which the restriction just referred to is provided, are continuously moving forward in the direction of travel of the sliver. They do not move as fast as do the fibers, due to the drafting action of the front rolls, but they do seem to modify beneficially the retarding action of the restriction through which the fibers are pulled by the front rolls. That. this factor is helpful is indicated by the fact that the best results have been produced by sand blasting the fiber engaging bosses of the lower roll 8 instead of making these surfaces smooth or polished.

Whatever may be the reasons for the improved results obtained, the important fact is that this mechanism has been found in practice to produce exceptionally uniform rovings.

Preferably the intermediate lower roll 8 is driven at a slightly higher peripheral speed than the roll 5 in order to exert a rubbing and pulling action on the forward ends of the fibers tending to straighten and parallelize them as they come in contact with it, to prevent the creation of any slack in the sliver between these two rolls and toincrease the pressure of the sliver against the lower surface of the upper roll a. Such a difference in speed, while maintaining the desired roll 4, and during relative spacing of the rolls with reference to each other, is facilitated by the fact that the spacing collars can revolve with reference to both the of the collars produced by their contact with the lower roll 8 will not adversely affect the rotation of the upper roll. The clearance between the rolls 4 and 8 can .be increased from the figure of five thousandths of an inch above given to in the neighborhood of thirty-five thousandths of an inch while still producing good results. Usually it is preferable to maintain this clearance somewhere between five and twenty or twentyfive thousandths. In general, it is desirable to make this clearance as small as is consistent with good operating conditions. In this connection, however, it should be noted that the density of the fiber inthe restricted space between the rolls 4 and 8 can be adjusted by suitably varying the relationship between the two drafts. That is, if the density of the fiber is too high the rear draft can be increased slightly to bring the density'down to the desired value, and the overall draft can still be maintained unchanged by decreasing the front draft to compensate for the increase in the rear draft. Thus a very considerable operating flexibility is obtainable with a given spacing between the rolls 4 and 8.

Since the top roll 4 is mounted in the crotch of the lower roils5 and 8, or more accurately stated, is positioned transversely of the frame by the engagement of its bosses with the lower roll 5 and the contact of the spacing collars with the intermediate lower roll 8, no engagement with the cap bars is required so far as the matter of holding it properly spaced from the front and rear rolls is concerned. However, the cap bars are provided with blocks I4-l4, Fig. 3, to limit any tendency of the top roll to move axially of itself. The spacing of the middle assembly of rolls, including those designated at 4, 5 and 8, may be changed by adjusting the bearing block l5, Fig. 1, backward or forward with the slide IS on the roll stand [0. Also, the lower rear roll I may be adjusted toward and from roll 5 by moving its bearing block l8 on the slide l6. Bolts are provided to lock these elements in their adjusted positions.

As in any drafting system, the spacing of the three sets of rolls will depend largely upon the average length of staple undergoing operation, the distance between the bite of the middle roll andthe rear rolls, as well as that between the middle and front rolls, than such average length. It should be observed, however, that when the parts are adjusted, as

' shown in Fig. l, the distance from the bite of the in accordance with front roll to the point at which the sliver leaves the bottom roll 8. is less than half the staple length, which is a good operating condition. Also, that the machine has provision for a wide range of adjustment of the roll spacings so that it is well adapted for operation on the longer staples, such as combed cotton and mixtures of cotton or wool with rayon.

The bottom rolls 3, 5 and 1 preferably are fluted the usual practice and the top rolls are covered, as is common in mechanisms of this type, with some cushioning material, such as leather, synthetic rubber, or synthetic plastics having the desired cushioning and oil-resisting properties.

The weighting mechanism showncomprises a hanger 20 hooked over the neck of the front roll 2 and a saddle 2| with its front end hooked over rolls 4 and 5 so that the speed of rotation the middle being somewhat greater asaaasa the neck of the top middle roll 4, and its rearward end resting on the neck of the rear roll 8. A stirrup 22 has a hooked end resting in the V-shaped bend in the saddle 2| and the lower ends of this stirrup and of the hook 213 are pivoted to opposite ends of a floating lever 23 connected by a link 24 with aweighting lever 25 mounted in a manner well known in this art. It will be evi= dent from an inspection of Fig. 2 that the angle of pull exerted by this mechanism on the second top roll 4 is directed downwardly and rearwardly at such an angle that it passes through the lower roll 5 and thus maintains the firm bite of these rolls referred to above.

While I have herein shown and described a preferred embodiment of my invention, it will be evident that the essential features of the invention may be embodied in other forms.

Having thus described my invention, what I desire to claim as new is:

1. In a drafting mechanism for roving frames, the combination of a pair of top and bottom front rolls, a second pair of top and bottom rolls behind the front pair and driven at a slower speed than the first pair for grippinga sliver and feed-" ing it toward the front rolls, weighting means for loading the second top roll to produce a firm bite between the rolls of said second pair, an intermediate bottom roll between said front and second bottom rolls cooperating with said second top roll to engage and compress the sliver without gripping it firmly as it is drawn forward between them by the front rolls, and means for maintaining said second top roll and said intermediate bottom roll spaced apart by a predeter mined minimum distance, whereby a positive draft is produced between said first and second pairs of rolls and a slip control of the fibers is provided between said second top roll and said intermediate bottom roll.

2. A drafting mechanism according to preceding claim 1, in which said spacing means is supported for rotation relatively to both said second top roll and said intermediate bottom roll.

3. A drafting mechanism according to preceding claim 1, in which said spacing means includes spacing collars mounted to roll relatively to both said second top roll and said intermediate bottom roll and supporting said second top roll.

4. A drafting mechanism according to preceding claim 1, in which. said spacing means includes collars rotatably mounted on the gudgeons of said second top roll and resting on said intermediate bottom roll.

5. A drafting m'echanismaccording to preceding claim 1, in which said bottom rolls run at progressively increased speeds with the front roll running at the highest speed. I

6. A draftingmechanism according to preceding claim 1, in which said second top roll is located in. the crotch between said second and intermediate bottomrolls and the latter are so spaced apart that the sliver is in contact with the top roll for an angle of at least 45 contact with the bottom roll for in the hood of 7. A drafting mechanism according to precedneighboring claim 1, in combination with weighting means for said top rolls and the weight is so applied to said second top r011 that'the line of pull exerted on it passes through said second bottom roll.

8. A drafting mechanism according to preced-' ing .claim 1, in which thespace so maintained between said second top roll and said intermediate bottom roll is in the neighborhood of five thousandths of an inch.

9. A drafting mechanism according to preceding claim 1, in which the space so maintained between said second top roll and said intermediate bottom roll is between five and thirtyfive thousandths of an inch.

10. In adrafting mechanism for roving frames, the combination of a pair of top and bottom front rolls, a pair of upper and lower back rolls and an intermediate set of rolls comprising two bottom rolls and a top roll positioned in the crotch between said intermediatebottom rolls, all of said rolls cooperating to feed and draw a strand of andisin' the top rolls to maintain a firm sliver, means maintaining the foremost of said intermediate bottom rolls and said intermediate top roll separated by a narrow space of predetermined minimum thickness such that the sliver is 'compressed between them but is not gripped firmly by them, and weighting means acting on bite between each of said front and back top rolls and its respective lower roll and also between said intermediate top roll and the rearmost of said intermediate bottom rolls.

11. In a drafting mechanism for roving frames, the combination of pairs of top and bottom front and rear rolls, a second pair of top and bottom rolls between said front and rear rolls, all of said rolls being arranged in a series to grip and feed a sliver and to subject it to two drafting operations, weighting means acting on said top rolls to produce a firm bite between each of them and their respective bottom rolls, an intermediate bottom roll between said front and second bottom rolls, driven at a higher speed than said second bottom roll and cooperating with said second top roll to engage and compress the sliver as it moves forward to the front rolls, means for maintaining said second top roll spaced from said intermediate bottom roll by a predetermined minimum distance, and means supporting said rolls in cooperative relationship to each other with the second top roll located in the crotch between said second and intermediate bottom rolls and thereby causing the sliver to remain in contact with the peripheral surface of the second top roll for an angular distance of at least 30.

12. A drafting mechanism according to preceding claim 1, in which said intermediate bottom roll is driven at a higher surface speed than its cooperating second top roll and said spacing means between these two rolls includes collars mounted in a fixed radial relationship to said top roll for rotation around the axis of the latter roll while bearing on the peripheral surface of said intermediate bottom roll.

13. In a drafting mechanism according to preceding claim 10, a construction in which the foremost of said intermediate bottom rolls is driven at a higher surface speed than its cooperating top roll and these two rolls are spaced apart by BENJAMIN c. snaw.

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