The present invention concerns a crush roll arraftigement for a card web with two co-operating working rolls, such as used in staple fibre spinning, particularly in processing natural fibres.

Crushing a very thin fibre web, such as it is taken off e.g. from the doffer cylinder of a card, is aimed at reducing im- purities still contained in the web by crushing them, parti¬ cularly the harder seed and Shell particles in such a manner that their detrimental effect in subseguent processing oper- ations is less disturbing and that their elimination from the fibre material is effected more easily.

For achieving good results using a crush roll ^' arrangement of such type the uniformity of the crushing pressure generated over the whole working width of the rolls, which is of the order of 1 m, is of decisive importance. If the pressure is too low, the impurities are not crushed or are not crushed sufficiently, i.e. the crush roll arrangement does not achieve the desired effect, whereas excessive pressures cause damage to the fibre material. Many efforts thus have been taken for achieving uniform loading of crush rolls which have resulted in a number of proposed Solutions, which however, are still unsatisfactory.

Thus, e.g. from German DT-PS 177 241 a crush.roll arrange¬ ment for paper, textiles, wσod, leather and similar mater- ials, is known, in which, for achieving better smoothness, the axes of the cylindrical crush rolls are arranged at an angle with respect to each other. In a crossed arrangement of this type a uniform pressure distribution can be achieve over the whole working width of the rolls in spite of the lateral loading of the rolls at the bearing support members. This known crush roll arrangement, however, shows substanti disadvantages: The use of pendulum bearings is reguired, which for setting the pressure are to be arranged adjustabl A design of this type, especially the crush roll drive mechanism, is complicated and expensive.

A further disadvantage is seen in that a certain crossing angle between the crush rolls permits uniform pressure dis¬ tribution only if a precisely determined load is applied to the bearing support members. If the bearing support member e.g. are loaded excessively, the crush rolls are loaded at the edges, i.e. the pressure is higher toward the side portions of the rolls than at the centre. For varying the pressure between the rolls - a uniform distribution being maintained - thus also the crossing angle is to be adapted; a tedious Operation which is difficult to control.

A further disadvantage of this known crush roll arrangement is seen in that rolls which are bent in their axes, are sub ject to a constant reciprocating load, which reguires, amon other inconveniences, a corresponding bending work.

According to another proposed solution (German DT-PS 904 150 a uniform pressure distribution is to be effected using a crush roll arrangement with two working rolls which are supported over their length in such a manner that each working roll is supported by at least one loaded support

support member being designed preferentially as a member of constant strength.

In a further development of this idea (German DT-PS 918 676) it has beco e known, that between the working roll and the support member a pressure transmitting element is inserted which is elastic. The disadvantage of this crush roll arrangement is seen in that the rotating cylindrical crush roll surface contacts frictionally under the füll pressure force the loaded support member or the pressure transmitting member respectively. Thus considerable energy losses and great danger of damage to the very susceptible roll surface prevails.

Furthermore, from US Pat. No. 3 457 618 magnetic crush rolls for card webs are known. Such crush rolls consist of a thin tubular steel sleeve, inside which a plurality of permanent magnets are uniformly distributed over the whole width of the rolls, providing the magnetic flux required. Such crush rolls per it establishment of a uniform pressure distribution. They show the disadvantage, however, that their manufacture is very expensive and that the pressure cannot be adapted.

It thus is the object of the present invention to propose a crush roll arrangement, which eliminates the disadvantages of the known arrangements and in particular, permits achieve- ent of a uniform and easily adjustable pressure distribution over the whole width of the rolls. Furthermore the arrange¬ ment is to be of simple design, economically feasible and 0 reliable.

These objectives are achieved with a crush roll arrangement for a card web with two co-operating working rolls, which are characterised in that at least one of the two rolls is s designed as a hollow member, the substantially cylindricaJr^rrTg Tjζ-j

sleeve of which is under the influence of a pressurized edium wetting the roll inside, and which is elastically defor able in radial direction, and that the second roll is supported at such distance that it counteracts the deform- ation of the deformable roll locally.

According to an alternative design example of the inventive crush roll arrangement the second roll also can be a hollow member which is elastically deformable radially toward the outside by a pressurized medium.

According to a further alternative design example, the roll inside available for the pressure medium is reduced by a rigid body, in which arrangement the rigid body in a parti- cular embodiment can be designed as a cylinder on the out¬ side surface of which the roll sleeve is supported if the medium is in its unpressurized State.

The invention is described in ore detail in the following with reference to illustrated design examples. It is shown in:

Fig. 1 the web take-off elements of a card, shown sche- matically in a side view;

Fig. 2 an inventive crush roll arrangement, shown sche- matically in a longitudinal section;

Figs.3a a section along the line A-A of the crush roll arrangement according to Fig. 2, na ely in Fig. 3a in its unpressurized State and in Fig. 3b in its pressurized loaded State;

Fig. 4 an alternative design example of the crush roll arrangement in a longitudinal section;

Figs. 5 further alternative design examples of crush rolls, ^u " the crush rolls being shown without bearing members and loading elements.

A doffer cylinder 1 of a card transports on its point cloth- ing 2 a fibre web 3 (indicated with a dash-dotted line) from below in the rotational direction indicated by arrow f.. upward to a point where the web 3 is deflected from the doffer cyl¬ inder 1 by the point clothing 4 of a take-off roll 5 which rotates in the same direction (arrow f_) . The fibre web 3 contacts the substantially cylindrical smooth surface of a lower working roll 6, a transfer roll 7, which normally is provided with a structured surface (in Fig. 1 four suitably directed longitudinal grooves 8 provided in its surface are shown) and which ensures that the fibre web 3 is taken off the point clothing 4 and is deposited onto the surface of the lower working roll 6. Arrows f_ and f. indicate the rotational direction of the rolls 6 and 7, the length of the arrows not indicating any relation with the actual roll speeds. Above the take-off roll 5 furthermore a rotating brush 9 is provided, which ensures the elimination of any rest fibres from the point clothing 4 of the take-off roll 5.

The fibre web 3 is transported to the right by the lower working roll 6 and reaches the contact zone between the lower working roll 6 and the upper working roll 10 which forms a crushing line with roll 6 and rotates in the direc¬ tion of arrow f_. Here the web is subject to a crushing action known as such, in which the impurities contained in the fibre web 3, such as e.g. seed particles, sand particles, etc., are crushed. The fibre web 3 upon leaving the

ing line is e.g. Condensed by a funnel 11, and. is taken off by two rolls 12 and 13 in the form of a fibre sliver 14 (see also Fig. 2) and is transferred to a depositing device not shown.

The position of the working rolls 6 and 10 as shown in Fig. 1 can be chosen within the scope of the present invention also in a different manner; in particular, e.g. in such a manner that the axes of both rolls are located in one vertical plane.

In Fig. 2 the lower working roll 6 is a solid roll, the sur¬ face of which is substantially cylindrical, deviations from this shape being entirely possible within the scope of the present invention, as explained later on. The lower working roll 6 is rotatably, but not movably with respect to the roo , supported in two anti-friction bearings 17 and 18 mounted each in a side member 15 and 16 of the card frame not shown in ore detail.

The upper working roll 10 consists of a substantially cylin¬ drical, thin sleeve 19 which is tightly sealed at each end by a cover 20 and 21 respectively, in such a manner that a pressure can be built up in the roll inside room 22. A suitable tight connection can be achieved, e.g. by welding (comp. Fig. 5 wherein the welding seam is designated 23) . Also a tight press fit between the covers 20,21 and the sleeve 19, or a sliding fit with a tight seal (both not shown) , can be considered.

Each cover 20 and 21 respectively, extends towards the out- side in an axis 24 and 25 respectively, concentrical to the sleeve 19. The axes 24 and 25 are rotatably supported in two support members 26 and 27 each with an anti-friction bearing 28 and 29 respectively. The support members 26

27 in turn are slidably güided in the two frame side members 15 and 16 respectively, as shown in Fig. 2 wherein fixing screws (not shown) which adjustably connect the support members and the frame side members, are indicated schemati- cally with their axes m and n. For this purpose the side member 15 furthermore contains a stop 30 for the support member 26, which is pressed against the stop 30 by a pressure spring 32 arranged between an upper extension 31 of the side member 15 and the support member 26, the position of the stop 30 being chosen such, that the whole force of the pressure spring 32 is taken up by the stop 30. A correspon- ding symmetrical arrangement is provided at the ^' left hand side. In this case the pressure spring 32 has no influence onto the area pressure between the working rolls 6 and 10. This support arrangement provides a certain possibility of yielding to the rolls in case any non-crushable impurities are present in the fibre web 3 (Fig. 1) , such as, e.g. a ^• metal particle; in this case the upper pressure roll 10 can be lifted, the pressure force of one or both pressure Springs 32 being overcome, in such a manner that the uncrushable impurity can pass between the working rolls without damaging the roll surface, as it would be the case with rigid support of both working rolls 6 and 10.

Furthermore it is noticed that in the frame side elements 15 and 16, bores are provided for the axes 24 and 25 of the working roll 10, the diameter of which bores exceeds the diameter of the axes, in such a manner that they penetrate the side frames with sufficient clearance.

The left-hand side axis 25 of the roll 10 contains a coaxial bore 33 connecting the roll inside room 22 with the supply duct 35 from a pump 34 by which a medium is pressurized. Between the rotating bore 33 and the stationary supply duct a pressure-tight connection (not shown) is provided. To the

supply duct 35 furthermore a pressure measuring device 36 is connected.

The pump 34 is supplied with the liquid 38 contained in reserve tank 37. Any compressible medium, however, e.g. a gas, can be used without difficulty, as the only reguirement of the medium is that it is sufficiently pressurized. If a gaseous medium is used, a comprössor can be used instead of a pump 34. The reserve -tank 37 in this case is not reguired anymore. The radial arrows f _fi indicated on the roll inside room indicate the radial forces exerted by the medium onto the roll sleeve 19. Under the influence of these forces the sleeve 19 is deformed elastically over a distance r. - r _n in such a manner that it bulges outwards, as shown schematicall in Figs. 3a and 3b.

In its non-pressurized State the working roll 10 (Fig. 3a) the distance M between the centres of the working rolls 6 and 10 eguals the sum of the radiuses r« und R _n of both rolls 6 and 10, i.e. in the non-pressurized State the upper working roll 10 contacts the lower working roll 6 without load, or possible with a minimal load. The upper working roll 10 thus is not deformed, i.e. its cross-section remains circular. In order to achieve this, the axes of the rolls 6 and 10 with the corresponding support members can be suppor¬ ted in the most simple manner at fixed centres at a distance M, which is differing from the arrangement according to Fig. 2. The area pressure between the working rolls according to the invention is generated by the deformation of the working roll 10 caused by the pressure prevailing in the roll inside room 22, as clearly indicated in Fig. 3b.

In Fig. 3b the increase of the diameter of the sleeve 19 of the upper working roll 10 under the influence of the pressure is shown. But as the distance M between the centres of

rolls 6 and 10 is maintained constant, the deformation of the roll 10 is locally impeded by the roll 6, as roll 10 necessarily contacts roll 6. Thus the area pressure req- uired for crushing the fibre web (Fig. 1) is generated.

The uniformity of the area pressure along the whole length of the nip line between the two working rolls 6 and 10 furthermore can be ensured very reliably in the manner des- cribed in the following:

By, e.g. suitably choosing the contour of- the sleeve 19 of the upper roll 10 and/or of the lower roll 6, an egualisation of the deformation influence which varies over the width of the rolls can be effected. In a roll 10, which in its non- loaded State is cylindrical, the lower, solid roll 6 can be shaped correspondingly concave. Furthermore, the effective width L (Fig. 2) of the pair of rolls, which corresponds to the width of the throughpassing web, can be chosen smaller than the total width of the rolls. Thus the influence of the radially not deformable roll end portions can be elimi- nated to a large extent.

The two working rolls 6 and 10 are connected by two gears 39 and 40 for drive purposes. As the axes of the rolls 6 and ιo are maintained parallel at all times and as the centre distance M is maintained constant at all times, Optimum conditions are ensured for the pair of gears 39,40.

In Fig. 4 an alternative of the crush roll arrangement according to Fig. 2 is shown, differing from the latter mainly in that both working rolls are designed as hollow members deformable in radial direction under the influence of a pressurized medium wetting the roll inside rooms.

-BÜ t

O PI A, W1P0

In Fig. 4 an upper working roll 41 and a lower working roll 42 are provided, designed in the same manner as the upper working roll 10 according to Fig. 2. The diameters of the rolls 41 and 42 can be different however. Also in this arrangement of the crush rolls the effective roll width L is smaller than the total width of the rolls 41 and 42, in such a manner that also in this arrangement the influence of the roll end portions onto the pressure distribution over the nip line is eliminated to a large extent. Furthermore, the pressure prevailing in each roll differs. For this purpose the upper working roll 41 is pressurized by means of a first pump 43 via a supply duct 44. By a second pump 46 and via a supply duct 47 on the other hand, the lower working roll 42 is pressurized and thus is deformed. The pressures applied are controlled by the two pressure measuring instruments 45 and 48.

Both pumps 43 and 46 are supplied with a liquid contained in a common reserve tank 49. The pumps 43 and 46, however, also can be supplied from separate reserve tanks with the same liquid or with different liquids.

In Fig. 4 also the possibility is shown of influencing the function of one of the working rolls by increasing or by lowering the temperature of the medium. This arrangement can prove advantageous in Special applications of crush rolls, if e.g. the impurities can be rendered brittle or less sticky by lowering their temperature. For this purpose the lower working roll 42 is provided with a back-flow duct 50 connecting the roll inside room with the reserve tank. The liquid supplied by the pump thus can flow through the roll. The liquid is heated, or chilled respectively, by a heat exchanger 51 provided in the circulation, e.g. in the reserve tank.

' .

In Figs. 5 through 9 further alternative design exa ples of working rolls are shown which can be applied within the scope of the present invention. As in all these examples the pairs of rolls are supported in the same manner as described with reference to the examples shown in Figs. 2 and 4, the further description can be limited to the actual design of the rolls.

In Fig. 5 a working roll 52 is shown, in which the roll inside room available for the pressure medium is reduced by spherical rigid bodies 53 arranged in the roll inside room.

Any other shape desired of the bodies also can be considered, from powdery material to one solid cylindrical body filling the room partially or wholly. By reducing the room available for the pressure medium a reduction of the total volume of the medium reguired is achieved. Considering the fact that any medium is of a certain compressability, this arrangement proves advantageσus, as it ensures better constancy of the pressure maintained inside the roll.

The working roll 53 shown in Fig. 6 also consists, as all design examples according to the invention, of a sleeve 54 deformable in radial direction, which at both its face sur- faces 55 and 56, is welded to a cylindrical body,r ^" " Between the sleeve 54 and the cylindrical body 57 an annular gap room 58 extends over almost the füll width of the sleeve 54, into which gap room 58 the supply duct 59 for the pressure medium merges.

In Fig. 7 a further alternative design example is shown of the working rolls according to Fig. 6, ^' in which the sleeve 61 in the non-pressurized State of the medium contacts the outside surface of the cylindrical body 60, the diameter of which corresponds to the sleeve inside diameter. In Fig. 7 the upper half of the roll is shown in its non-pressurized

State, whereas the lower half of the roll (below the- centre line x) is shown in its pressurized State..

As different from the roll according to Fig. 6 no annular gap room prevails here between the face sides 62 and 63, but the cylindrical body 60 fills the whole roll inside deter- -mined by the sleeve 61 in the non-pressurized State. This alternative design example presents the advantage that the sleeve 61 in the non-pressurized State is supported and thus is aligned by the very massive, precise cylindrical body 60.

A plurality of connecting duets erconnect the central medium supply bore 66 with the cylindrical periphery of the cylind¬ rical body 60. In this manner the distribution of the pressure medium throughout the gap 64 between the sleeve 61 and the cylindrical body 60 is favoured. The same effect can be achieved by strueturing the surface of the cylindri¬ cal body 60, e.g. by grooves.

in this design example, furthermore, the application of an outside pressure source is dispensed with. The pressure inside the roll simply is established by providing an adjust- able pressure piston 67 which displaces the medium in the " roll inside. The piston 67 guided in a bore 68 of the hub 69 and provided with a suitable seal (not shown) if needed, is pressed against the liquid, filling the roll inside room by means of a set screw 70 which is screwed into a corres¬ ponding threaded nut 71 of the hub 69. The advantage of this design example is seen in the utmost design simplicity. The use of particularly pressure resistant mediums, of course, is required in this example, such that the pressure and thus also the deformation of the sleeve 61 is maintained constant over time.

-"B

^' ^

The uniformity of the area pressure between the two working rolls can be achieved also in a different manner, na ely in that the face Covers 73 and 74 (Fig. 8) are centrally conn- ected mutually by a shaft 76 forming two hubs 77 and 78 as bearing positions for the working rolls outside the face covers. Between the sleeve 72 and the covers 73 and 74 connected therewith via the welding seam 75 an inside room formed is subdivided into individual chambers 81 by ring- shaped intermediate walls 79 and 80. In this arrangement the intermediate walls 79 and 80 are designed in such a manner that they can yield to a radial deformation of the sleeve 72, whereas they are pressure-tight at the face side. Suitably chosen, concentrically, annularly ondulated sheet metal plates, e.g. can fulfill these requirements.

Using suitable supply ducts, the individual chambers 81,82 and 83 can be pressurized. A pump 84 via a supply duct 85 pressurizes the chambers 81 and 83 at the pressure p. ,whereas the chamber 82 is pressurized by a second pump 86 via the supply duct 87 at the pressure p- . The pressure p, and p„ respectively, can be checked by two pressure measuring Instruments 88 and 89 respectively. By suitably choosing the pressures p. and p_, the shape of the sleeve surface in its loaded State (indicated by the broken line t) can be influenced. Normally the pressure p. will be chosen greater than the pressure p_, as indicated in Fig. 8, by the differ¬ ent length of the arrows indicating the pressure.

In Fig. 9 the equalisation of the area pressure is achieved by choosing varying sleeve thicknesses over the roll width. In the upper half of Fig. 9, e.g. the sleeve 90 of the roll is varied in Steps towards the middle, whereas in the lower half, the sleeve thickness gradually increases and decreases.

By such variations in thickness, which in Fig. 9 are shown exaggerated for better clarity, the resistance to deformation of the sleeve 90 can be influenced along the width of the roll, in such a manner that in turn the shape of the sleeve in its loaded State can be adapted to the requirements as desired. Thus, e.g. the dash-dotted line r indicates the outline of a sleeve 90 of constant thickness. The broken line s, on the other hand, indicates the deformation of a sleeve 90, the thickness of which is varied in Steps over the roll width.

Furthermore, the various measures proposed for equalisation of the area pressure between the working rolls of a crush roll arrangement can be combined for achieving Optimum re- sults. Thus, e.g. a working roll can be provided with a sleeve of varying thickness and can be subdivided in indivi¬ dual chambers.

The most important advantages of the inventive crush roll arrangement are:

a) Parallel instead of crossed arrangement of the working rolls, such that any card can be equipped with a crush roll arrangement, without complicated bearing problems to be overcome, and that the area pressure between the working rolls can be adapted in a simple manner, the working rolls being maintained parallel.

b) Simple and economically feasible design, ensuring highly reliable crushing action.

c) Easy retrofitting on existing card, as no particular reguire ents are imposed for the bearing arrangement.

d) Good influenciability and Optimum uniformity of the area pressure along the width of the roll.

e) Easy change from Operation with fibre web crushing action to Operation without such action. For this pur¬ pose it is sufficient to release the pressure inside the working roll. This advantage is of utmost import- ance in practical Operation, as with each change in the material to be processed the question of suitability is to be re-checked anew.

- _B U EA

OMPI