Device for adjusting the work gap between the points of flat clothings and the points of the cylinder clothing of a card

[0001] The present invention concerns a device for adjusting the work gap between the points of flat clothings and the points of the cylinder clothing of a card, whereby the flat bars provided with clothings are led across a partial area of the drum circumference on both sides of the card on respective, convex bent sliding guides, and whereby their sliding surfaces with regard to the drum axis of rotation are being radially adjustable.

[0002] Devices of this kind are known in various designs.

[0003] For example the old U.S. patent specification 528007 of 23.10.1894 describes a revolving flat card, with which the flat bars provided with flat clothings are fastened to respective endless chains to their ends and are pulled on both sides of the card by means of these endless chains over sliding guides provided thereto, so that the clothing points are moved relatively to the clothing points of the drum and at a constant space from this over a partial area of the circumference of the drum and thereby carry out the desired carding work. After the movement along the sliding guides the flat bars are diverted around a pair of chain wheels and led back to a further chain wheel, which serves also as a diverter, and end-up in this way again on the sliding guides, so that they can carry out again the desired carding work with the clothing points of the drum. Thus the flat bars arrive again and again on the sliding guide and carry out carding repeatedly work with the drum.

[0004] At the ends of the flat bars so-called flat heads are present, with sliding surfaces, which slide on the respective sliding guides along the two sides of the card. These sliding surfaces determine the space between the points of the flat clothings and the points of the cylinder clothings with the sliding surfaces of the sliding guides. This space must be adjusted precisely during manufacturing of the card and during a new furnishing of the card with clothing, whereby one nowadays aims for carding spaces, i.e. spaces between the points of the flat clothings and the cylinder clothing, within the range of approximately 0.2 mm. Only then high-quality carding work is possible at a high production of the card.

[0005] During adjustment of this carding gap, the sliding guide at the card according to the U.S. 528007 is being displaced radially in relation to the axis of rotation of the drum, in order to keep the desired carding space. For this purpose the sliding guides are designed as so-called flex bends, which are, according the US patent specification, attached at three different places by means of adjustment rods on the side frames of the carding frame. By adjusting the respective adjustment rod which are furnished with left and right-hand threads, the three points at which the adjustment rods engage with the flex bends, can be adjusted in each case radially in relation to the carding frame and therefore to the drum axle, whereby it is to be understood that with the radial adjustment at three circumferentially distributed points, the curvature of the flex bends, i.e. the sliding guides is slightly changed, i.e. a bending of the flex bends takes place.

[0006] After adjustment of the carding space along the sliding guides the card can be put into operation. In the course of time wear and tear of the points of the flat clothings and the cylinder clothing takes place, so that the carding space increases itself in an undesirable manner. In order to work against this enlargement of the carding space, also in the case of the old U.S. patent specification 528007, all adjustment rods can be adjusted together, in order to readjust the carding space to the originally set value.

[0007] For this purpose the adjustment rods on their far end, opposite the flex bends, are not fastened directly to the side frames of the carding frame, but on respective angular levers, which are rotatably mounted on the side frames of the carding frame. The other arms of the respective knee lever are connected with one another and with an adjusting wheel by respective tie bars, so that by turning the adjusting wheel, a mutual adjustment of the knee levers takes place and thus, by means of the adjustment rods of the respective engagement points of the adjustment rods on the flex bends.

[0008] From this one can see that the basic adjustment is possible via the adjustment rods for each support point of the flex bend, that is independently of the other support points, and that thereafter a mutual adjustment of all support points of the flex bend can be made, so that the carding space is adjusted evenly along the flex bend, whereby, as previously mentioned, the flex bend is slightly bent for adjustment to the changed curvature.

[0009] A change of the adjustment of the flex bends is necessary not only because the wear of the flat clothings and/or the cylinder clothings, but also after grinding of the cylinder clothing and/or the flat clothings.

[0010] It is actually known, to mount a sharpening mechanism onto a card and after interruption of the carding work, to grind the clothings for example twice or three times during their life span, in order to give the clothing points, both the cylinder clothing as well as the flat bar clothings, a sharp form, which ensures a better quality of the carding work.

[0011] It is also known from various patent specifications, for example the EP-A 0 565 486, to build a sharpening mechanism into a card which is used substantially more frequently during the operation of the card, in order to guarantee that the respective clothings remain sharp. This latter possibility has the great advantage that for sharpening of the drum and flat clothings the card does not have to be stopped, so that production is not impaired. Beyond that it is guaranteed that the clothings always have an optimal sharpness and a card sliver with even and high-quality characteristics is thus always produced, which benefits the succeeding yarn production. Furthermore such a sharpening system leads to the fact that the clothings experience an overall longer life span.

[0012] Independently of this, whether the clothings are ground only a few times during their life span with a rather larger material removal each time or more frequently with a rather smaller material removal each time, such sharpening procedures lead to changes of the carding space, whereby the possibility of the radial adjustment of the flex bends allows it to always adjust the carding space correctly.

[0013] Various further suggestions were made, how one can achieve a radial adjustment of the flex bends.

[0014] For example around 1975 a card was offered by the company SACM, in which the adjusting of the flat was made on each side of the machine from only one single point by means of two side by side arranged spirals which were shiftable against each other.

[0015] With this type of design the outer spiral on each side of the card has the form of an elongated, curved wedge with small wedge angle, whose radially outer surface forms the sliding guide and whose radially internal surface slides on the radially outer surface of the respective internal spiral. The inner spirals also have each the form of an elongated, curved wedge, however on the radially internal side they are additionally provided with teeth and can thus be rotated by means of a gear set, so that with the cooperation of the radially outer surface of the internal spiral with the respective radially internal surfaces of the outer spirals the sliding guides on both sides of the card can be adjusted at the same time. Thereby all flats can approach the drum of the card at the same time and/or be moved away from the same.

[0016] From this arrangement it was also known to slightly offset the drum in relation to the axis of the curved sliding guide in order to provide an “entrance” for the flat chain, i.e. to adjust the carding space within the zone, where the flat bars at the beginning of the carding path of the drum approach, somewhat larger than towards the end of the carding path when it leaves the drum in order to return to the beginning of the carding path.

[0017] The same suggestion was also again brought forward in the DE 196 51 894 A1.

[0018] In connection with the adjustment of the flex bends of a card the DE 29 48 825 A1 is also of interest. In fact it is being recognized that the carding space can change during operation, both due to elongations, which are caused by centrifugal force and due to thermal expansions, which occur during warming up or cooling of the card.

[0019] Such elongations, i.e. due to centrifugal force or thermal causes, are, as is described in more detail in the DE-A 29 48 825, particularly problematic during start-up or stopping of the card. As is described, the tendency for the increase of the production rate of cards on the one hand leads to the fact that the number of revolutions of the processing elements is increased and on the other hand, that the dimensions of the machine cylinders become larger, both the diameter and the working width. With the increased rotary speed and the increased dimensions an undesired deformation of the cylinders, i.e. bulging caused by the centrifugal force can take place whereas said bulging increases gradually.

[0020] It is also explained that in direct connection with the increase of the production rate and of the carding work, there is a further influence to be seen in the tendency to suppress, to a large extent, the air interchange between the cylinders and the environment for the prevention of dust emissions, whereby the natural cooling of the operating components is made more difficult.

[0021] In the DE-A 29 48 825 is expressed that the temperature of the cylinders involved during the period of operation increases until a balance of temperature is reached, whereat this rise in temperature causes a change of the dimensions of the cylinders and in particular an enlargement of the diameters of the drum. Both the influence of the centrifugal force and the influence of the temperature rise do not have not an immediate effect when starting up the machine, but only after a certain time delay, which, regarding the influence of centrifugal force, takes at least as long as the acceleration time of the elements involved with the card e.g. the tambours.

[0022] According to experience, the influence of the temperature rise, until a balance of temperature has been reached, requires a longer periods of operation, which can amount to several hours.

[0023] In order to solve the problem, in the DE-A 29 48 825 a procedure is described to control the operating condition between two operating components equipped with clothing of points, for example the drum and the revolving flats of a revolving flat card, by which a value being directly related to the dimensions of the drum, is continuously or temporarily registered and by means of a suitable regulating device the carding space is held in dependence of the registered value at a defined value.

[0024] In the realistic solution shown therein for the adjustment of the flex bends, i.e. the sliding guides, heatable metal bars are applied, which are warmed up either by means of a fluid being heatable by a heat supply device or by way of an electrical heating means and are therefore forced to expand thermally. Since the temperature control makes a relatively exact adjustment of the lengths of the respective metal bars possible, the mechanism described there can work with a high accuracy.

[0025] There are also various other suggestions known for the radial adjustment of the flex bends of a card. For example the U.S. Pat. No. 5,625,924 shows a card with different possibilities for the radial adjustment of the sliding guide, amongst other things this disclosure describes the application of controllable actuators, which are specifically controlled in order to periodically adjust the changed carding gap newly or to compensate the wear of the clothings after a sharpening procedure. Therein it is expressed that the controllable actuator can be applied and controlled in connection with an integrated sharpening system. Different types of the actuator are mentioned. For example the use of servo motors or piezoelectric translators for the execution of the adjustment are mentioned. It is also shown how an eccentric cam arrangement of a controllable drive mechanism is applicable in order to accomplish a sensitive adjustment.

[0026] Furthermore, from the application WO 93/07314 an adjustment system is known with several adjustment devices which are arranged in respective places along the sliding guide and which extend between the sliding guide and a fixed point of reference, whereby each adjustment device is furnished with a blocking mode by which an adjustable clamping mechanism is effective in order to keep a once reached adjustment through blocking.

[0027] Despite the multiplicity of suggestions already made these are difficult and complex to be realized in practice and/or expensive for manufacturing.

[0028] The extent of the adjustment movements at the individual points of adjustment of the flex bends is indeed relatively small, whereby a total adjustment from more than three to four millimeters is rarely necessary and an adjustment in steps is aimed at by approximately 0.01 mm. Due to such small steps it can easily be seen, that already small clearance spaces in mechanical joints and similar will raise questions regarding the accuracy of the adjustment. Furthermore thermal expansions, which nevertheless require a certain control effort, can be impaired by dead play, particularly since the adjustment requires at one time a movement radially outward and at another time a movement radially inward. The problem arises that temperature measurements are actually indirect measurements and direct measurements of the carding space has proved so far being relatively inaccurate.

[0029] Furthermore in the case of adjustable wedge systems, the manufacturing costs are relatively high since close tolerances must be maintained over a wide range.

[0030] The applicant has also discovered that the applied materials for the sliding guide show frequently a hysteresis, so that the spaces for adjustment in one direction are not the same in the opposite direction and for this reason the accuracy of the adjustment also suffers. Additionally the friction forces, which arise with some constructions, are so large, that the resetting forces, which develop due to the tension of the flex bends, are too small in order to guarantee a reliable and precise resetting.

[0031] In some materials a plastic deformation already arises at lower tensions, which likewise leads to an inaccuracy of the adjustment. Moreover the pre-loadings, which are applied during processing of the flex bends, can have a disturbing effect on the accuracy of the adjustment.

[0032] If windows which are useful for the flat adjustment, are present in the flex bend, these windows can disturb the maintenance of the constant course of the carding gap in unwanted way.

[0033] It is thus known to radially adjust the flex bends or sliding guides for the flat bars of a card respectively, for different reasons, those are:

[0034] for new adjusting of the carding gap during manufacturing of the card or after renewed clothing of the card, whereby a respective radial adjustment is necessary at various adjusting points, in order to be able to adjust the carding space along the sliding guide at all points,

[0035] to effect a radial adjustment of the sliding guides, in order to hinder the wear of the clothings and to keep the carding space constant, whereby an even adjustment at the respective points of adjustment is desired here, since an even wear is to be expected and the once correctly adjusted carding space may only be readjusted evenly,

[0036] to effect a radial adjustment of the sliding guides, in order to hinder the change of the carding space after sharpening of the clothings, whereby here also only an even adjustment is necessary,

[0037] to radially adjust the flex bends, in order to hinder the change of the carding space due to centrifugal force and/or thermal expansion, whereby also this adjustment is to be understood as an even adjustment.

[0038] In all the previous suggestions a buckling of the sliding guides takes place at the end, in order to obtain the necessary adjustment of the carding gap, so that the sliding guide is to be regarded as a flexible part, even though it is partially of a very high rigidity.

[0039] In order to effect the adjustment the individual adjustment devices are supported on comparatively rigid structures, such as the side frames of the carding frames, or on so-called fix bends which in principle also form components of the side frames of the carding frames.

[0040] It is the object of the present invention to provide a new device of the initially mentioned type which does not have the stated disadvantages or only has these disadvantages to a smaller extent and which allows low-cost manufacturing and an exact adjustment of the carding gap across the entire effective range for all of the existing adjustment.

[0041] This task, as an object of the invention, is solved by a device of the type initially specified, whereby each sliding guide is of a sandwich type design with a radially inner support, which can also be divided into individual supporting sections, and which is divided into a radially outer, continuous flex bend, whereat between the flex bend and the radially inner support a central zone is provided which is being furnished with one or several adjusting elements.

[0042] Thus on each side of the card, the radially inner support or the discrete supporting sections provided there, can be rigidly designed and be rigidly connected with the respective side frame of the card. Because the radially outer positioned flex bend is supported by adjusting elements arranged within the centre core of the sandwich type elements, there is an arrangement which is spatially very close to the radial inner support, whereby the accuracy of the sliding surface being formed or carried respectively, by the sliding guide is considerably affected by the accuracy of the radially inner support. Because the centre core of the arrangement at least basically extends along the entire flex bend, the flex bend is supported on a multiplicity of supporting points or all over the surface respectively, on the centre core so that a very exact adjustment of a relatively flexible flex bend can take place without having large deformations of the flex bend due to the effect of local forces at discrete positions.

[0043] Altogether, the device has a relatively small radial overall height which saves weight and which increases the accessibility for possible measurements or adjusting works at the card.

[0044] In an actual example the adjusting element is designed as piezoelement, which can for example have the form of a piezoelement extending over, at least basically, the entire length of the flex bend and which is designed in a multi-layer manner to generate the necessary adjustment movements.

[0045] However with such an arrangement only a relatively limited radial adjustability is attainable, this can however be quite sufficient in particular if this radial adjustability is to be used not for the basic adjustment of the carding gap, but for the micro-adjustment to compensate for evenly changing carding spaces during operation. Furthermore such an arrangement ensures that the change of the carding gap remains the same along the entire carding gap.

[0046] Instead of using one single piezoelement extending along the entire guidance bend, several such piezoelements can also be arranged next to each other, being controlled individually or together, and which, for example, are available in the form of known piezotranslators.

[0047] Alternatively, piezoelectric adjustment devices could be applied instead like those being described in the German patent application DE 198 33 782.5.

[0048] According to a further embodiment the adjusting element can also be realized as a pneumatically operating element, for example in the form of a cushion element, expandable under air pressure, which elastically expands depending upon the applied air pressure and along with the reduction of the applied air pressure contracts again. The pneumatically operating element can at least partially be formed by the radially inner support and the flex bends themselves, if for example an oblong groove is mill-cut into one of the two elements, into which a tongue of the respective other part projects and which in that way forms an air chamber, which is to be locked at the ends.

[0049] A further alternative for the adjusting element consists of a design with a thermal expansion element for example in the form of a corrugated, heatable metal strip, which is fixed at the ends, so that an even thermal expansion in longitudinal direction of the corrugated element leads to a respective enlargement of the radial height of the waves and therefore to a radial adjustment of the flex bend. During cooling of the corrugated metal strip due to the throttling or disconnection of the heat supply this strip shrinks in length and the radial height becomes lower.

[0050] A possibility of designing such a thermal expansion element consists of forming said thermal expansion element as a bimetallic strip whereby here also a corrugated form can be applied. Due to the design as a bimetallic strip, even more distinct radial adjustments ought to be possible. Furthermore individual leaf spring-type bimetal elements can be applied between the radially inner support and the flex bend.

[0051] A further possibility for the realization of the adjusting element consists of designing this as an electro-magnetically operating element.

[0052] The adjusting elements can also be designed as spring elements and can for example consist of several, individual small leaf springs. Such spring elements would tend to push-away the flex bend from the radially inner support, whereby it is necessary then, in order to adjust the space between these two parts and therefore the carding space, to exert forces on the flex bend which are variable and thereby determine the degrees of the compression of the springs. A possibility to generate these forces consists in changing the tension in the driving belt or driving chain of the flat bars respectively, since by changing this tension the resulting forces acting in radial direction on the flat bars and therefore on the flex bends, are adjustable. Another possibility would consist of providing piston-cylinder arrangements which exert radially inward acting forces on the flex bend. A particularly favourable spring arrangement results if the spring element consists of a polyurethane spring, which extends as a strip element along the radially internal side of the flex bends and which lays between this and the radially inner support. Such a spring can be designed with a high internal absorption, so that vibrations can be suppressed. Instead, damping elements could be provided, for example friction type dampers which prevent the flex bend from starting to vibrate.

[0053] For example the radially inner support could be provided with side walls, which slide onto side walls of the flex bend, whereat a friction lining between the side walls and the flex bend can be provided for absorption purposes.

[0054] If there are several adjusting elements applied over the length of the flex bend, then these can be controlled together or independently from each other.

[0055] Preferred embodiments of the device according to the invention are to be derived from the claims and the further description.

[0056] In the following the invention is described in more detail on the basis of exemplified embodiments with reference to the accompanying drawing, where shows:

[0057]
FIG. 1 a schematic illustration of a conventional card,

[0058]
FIG. 2 a side view of the card according to FIG. 1 within the zone of the revolving flat for the more detailed explanation of the basic construction,

[0059]
FIG. 3 a schematic cross section within the zone of the revolving flat of a card, seen at the cutting plane III-III of FIG. 2, whereby the illustrations of the FIGS. 1, 2 and 3 are shown in different scales,

[0060]
FIG. 4 a schematic side view of a sliding guide for a card according a first type of embodiment of the invention,

[0061]
FIG. 5 a sectional drawing along the cutting plane V-V of FIG. 4,

[0062]
FIG. 6 a side view of a sliding guide according to the invention similarly to that of FIG. 4, however in modified form,

[0063]
FIG. 7 a further side view of a sliding guide according to the invention similar to that of FIG. 6, however in the form of a further modification,

[0064]
FIG. 8 a side view of a further type of embodiment of a sliding guide for a card according to the invention,

[0065]
FIG. 9 a perspective illustration of one of the adjusting elements in the embodiment according to FIG. 8,

[0066]
FIG. 10 a schematic cross section at the cutting plane X-X of FIG. 9,

[0067]
FIG. 11 a schematic side view of a still further embodiment according to the invention of a sliding guide of a card,

[0068]
FIG. 12 a cross section along the cutting plane XII-XII of FIG. 11,

[0069]
FIG. 13 a cross sectional drawing along the cutting plane XIII-XIII of FIG. 11,

[0070]
FIG. 14 a schematic side view of a still further possible type of embodiment of a sliding guide according to the invention,

[0071]
FIG. 15 an enlarged illustration of a section of an adjusting element shown in FIG. 14 in the form of a bimetallic strip,

[0072]
FIG. 16 a schematic side view similar to FIG. 14, however from a further modified embodiment with individual adjusting elements in each case in the form of a bimetallic strip,

[0073]
FIG. 17 a schematic illustration of an individual bimetallic strip,

[0074]
FIG. 18 a schematic side view of a still further type of embodiment according to the invention of a sliding guide with spring elements realized in the form of a leaf spring,

[0075]
FIG. 19 an illustration of an individual spring element of the sliding guide according to FIG. 18,

[0076]
FIG. 20 a schematic side view of a sliding guide of a card similar to that of FIG. 18, however by applying a coil spring as spring elements,

[0077]
FIG. 21 a further schematic side view of a sliding guide of a card, which is furnished with an oblong polyurethane spring,

[0078]
FIG. 22 a cross section through the sliding guide of FIG. 21 seen along the cutting plane XXII-XXII,

[0079]
FIG. 23 a further schematic side view of a sliding guide according to the invention of a card with an electromagnetic actuator,

[0080]
FIG. 24 a cross section according to the cutting plane XXIV-XXIV of FIG. 23, and

[0081]
FIG. 25 a schematic side view of a further type of embodiment of a sliding guide, which is laid out according to a magnetic suspension railway.

[0082]
FIG. 1 shows in schematic illustration a side view of an actually known revolving flat card 10, for example the Card C50 of the applicant.

[0083] The fibre material for carding, which can consist of natural fibres or synthetic fibres or mixtures of the same, is fed, in the form of dissolved and cleaned fibre flakes, into the filling box 12, taken over by a licker-in or a taker-in 14 respectively, as coffon wool, handed over to a tambour or a drum 16 respectively, and is being parallelized by a revolving flat set 18, which is driven by means of diverting rollers 20, 22, 24, 26 in opposite directions to the direction of rotation 28 of the tambours 16.

[0084] Fibres of the fibre band being on the tambour 16 are then removed by a doffing roller 30 and in an actually known manner they are formed into a card sliver 34 by way of different rollers within the existing discharge zone 32. This card sliver 34 is then deposited by a sliver layer 36 in cycloidal manner into a transportation can 38.

[0085]
FIG. 2 and FIG. 3 show the card of FIG. 1 within the zone of the revolving flat chain in a larger scale and in further detail.

[0086] For simplification of the illustration only a few flat bars 40 are shown, all of which consist of a carrying body 42 formed as a hollow profile which carry the flat clothing 44, and two end heads 46, which are fastened to respective ends of the hollow-profile carrying body, for example in such a way that they fit into the ends of the hollow profile and that they are connected by a squeezing procedure which is described in detail in the EP-A-627,507 in order to create a positive connection with the hollow profile.

[0087] The actual preferred design of the flat heads 46 and the driving belt 48 which drive them, is described in the application EP-A-753 610, whereat the belt can be designed in particular according to FIG. 4 of that disclosure.

[0088] The belt 48 is furnished on one side, that is on the internal side in FIG. 2, with teeth 48A, which mesh with teeth 48B on the gear wheels 20 and 26, whereat, for simplification of the illustration, only a few teeth 48A and 48B are shown, it is, however, understood that the entire inside of the belt 48 is being furnished with teeth 48A and the entire circumference of the gear wheels 20 and 26 is provided with respective teeth 48B.

[0089] On the exterior side of the belt 48 there are further, bar-like or girder-like teeth 49 respectively, which are arranged in pairs, whereat here as well, for the sake of simplification, only a few pairs 49 are shown and each pair of teeth 49 engages into a corresponding recess 41 of a respective flat head, as is being described in more detail in the EP-A 0 753 610.

[0090] One sees from FIG. 2 that the endless driving belts, from which only the one on side of the card is being shown here, pull the flat bars 40 from the intake zone 50 on the right side of the drawing across a carding path along a sliding guide 52, which comprises a flex bend 54, up to a discharge zone 56, and that afterwards the flat bars 40 are diverted around the gear wheel 20 by which the driving belt is driven and led back again to the intake point 50, whereat the driving belt is diverted directly before the intake place 50 around the further gear wheel 26 and is being supported between the two gear wheels 20, 26 by two further support wheels 22, 24 and a support means 58.

[0091] It is understood that an arrangement as is shown according to FIG. 2, is also arranged on the other side of the card in an actually known way, whereby the driven gear wheels 20 are driven by a corresponding motor via a common shaft 60, whereat the two gear wheels 20 and therefore the two toothed belts 48, together with the thereon via the pairs of teeth 49 fastened flat bars 40, rotate synchronously, so that the longitudinal axes of the flat bars 40 always extend parallel to the drive axle 62 of the drum 16. This parallel situation is always maintained during the movement by the flat chain. Furthermore it is understood that during operation the flat bars 40 are arranged evenly distributed over the entire length of the driving belts 48.

[0092] As is more closely described in the EP-A-753,610, lie the sliding surfaces 64 of the flat heads 46 lay, within the zone of the flex bends 5,4 in sliding contact with those, that is on the one hand due to their own weight and on the other hand due to the tension of the belt, which within the zone of each flat head generates a radially inward directed force. In other words they get pressed onto the sliding guide 52, i.e. onto the sliding surfaces 66 of the flex bends 54, on the one hand due to their own weight and on the other hand they are pressed by the tension in the driving belts 48. Thereby the necessary carding space A (FIG. 3) between the flat clothings 44 and the cylinder clothing 68 is ensured. Due to the positive engagement of the pairs of bars 49 of the driving belt 48 into the corresponding recesses 41 of the flat heads and due to the synchronized circulation of the driving belts 48 on both sides of the card, the flat bars 40 are moved synchronously over the two flex bends 54, whereat the longitudinal axes of the flat bars 40 are always led parallel to the drum axle.

[0093] The positive engagement between the driving belt 48 and the flat heads 46 transfers the traction force of the driving belts 48 to the flat bars 40, so that these are moved evenly along the carding path between the intake zone 50 and the discharge zone 56.

[0094] A particular characteristic of the suggestion according to the EP-A-753 610 is based on the fact that within the diverting zone the bars of the pairs of bars 49 of the driving belts 48 tend to spread apart and hold the flat heads 46 in such a way that these are diverted around the gear wheels 20, 26, without the danger that the flat bars 40 are being lost and without the need of additional guidance within this area.

[0095] On the upper side of the revolving flat 18 however the flat bars 40 are lying loosely on the upper strands of the driving belts; thus they can easily be detached from the driving belt 48, particularly if they for example are to be cleaned or replaced. The force of gravity makes sure that the flat bars 40 in this zone do not separate from the driving belts 48 in an undesired manner.

[0096] As can be seen from the sectional drawing of FIG. 3, the flex bends 54 of the sliding guides 52 define the carding space A between the flat clothings 44 and the cylinder clothing 68 which for the simplification of the illustration is only partially shown in FIG. 3, whereat in this example the sliding guides are furnished with a respective embedded, strip-shaped guiding element 70 made of plastic, which forms the sliding surface for the flat heads, as is more closely described in the DE-A-39 07 396 or in the EP-A-0 620. In principle, such an imbedded element or such embedded elements respectively, being partitioned into sections, can be applied in all the embodiment being described more closely in the following and according to the present invention are used to form the actual sliding surface 66 for the flat heads 46 to be used. It can also be done without such an element, in particular if the flat head is furnished with a sliding shoe or sliding surface respectively, which usually slides onto the sliding guide being made of metal.

[0097] From FIG. 3 it is also seen, that each sliding guide 52 also shows a radially inner support 72, which is frequently called fix bend, whereat each radially inner support 72 is firmly connected with the respective assigned side frame 74 of the card or is an integral part of it, for example in the form of a respective cast part. The side frames 74 of the card also carry, in addition, the axis of rotation 62 of the drum (not shown in FIG. 3) and also form a radial guidance for the flex bends 54 (not shown).

[0098] Between each radially inner support 72 and the flex bends 54 assigned to it, there are provided—as can be seen from the FIG. 2 and 3—lengthwise adjustable, in this example five, mechanisms 76, which for example consist of an internal part 78 provided with external thread and an outer part 80 provided as a threaded sleeve with internal thread. By turning the internal part 78 in relation to the outer part 80, the length of the respective adjusting mechanism 76 can be set and thus a radial adjustment of the flex bends 54 within the zone of the respective supporting area can be accomplished. Thereby the curvature of the respective flexible flex bends 54 can be adapted to the curvature of the drum and the radial position of the sliding surface 66 of the respective flex bends 54 can be set in such a way that the carding space A remains constant over the entire length of the carding path and over the entire width of the drum or—if desired —that it allows the desired course along the carding path.

[0099] Referring to the FIG. 4 and 5 a first exemplified embodiment of a sliding guide 100 according to the invention is shown. This is provided with a sandwich type design with a radially inner support 102 and a radially outer continuous flex bend 104, whereby between the flex bend and the radially inner support a centre core 106 exist, which is provided with an adjusting element 108 in the form of a piezoelectric adjustment device. The reference numeral 62 here also points out the axis of rotation of the drum. From FIG. 4 it is seen that the sliding guide 100 runs at least basically concentrically with respect to the axis of rotation of the drum 62, whereby the angle extension of the sliding guide 100 includes approximately 100°.

[0100] The radially inner support 102 could either be designed as a part corresponding to the radially inner support 72 of FIG. 2 and 3 which is firmly fastened with the side frames of the card, whereby this design then presupposes that the radial outer surface 110 of the radially inner support 100 is already concentrically aligned to the axis of rotation of the drum, or that it shows the desired alignment in relation to the axis of rotation of the drum. The piezoelectric adjusting element 108 serves then as the micro-adjustment of the sliding surface 112 of the flex bend 104, along which the flat heads slide, in the sense that upon changes of the carding space A under centrifugal force and/or thermal expansions and/or wear and/or sharpening procedures, a control and/or a regulation means 114 controls an adjusting element 108 in such a way that the sliding surface 112 of the flex bend is radially adjusted by the same amount over the entire length of the flex bends.

[0101] The sliding surface 112 could be furnished in the form of oblong strips or sections of an element as described before in connection with the reference numeral 66 and in the EP-A-0 620 296.

[0102] If the control 114 is designed as a regulation means, then the carding space A is regularly or continuously being measured by means of a corresponding, actually known sensor technology (not shown) and the adjusting element 108 is controlled in such a way, that the measured actual value of the carding space A is always kept at a predetermined set value. Instead, however, the control 114 can receive control commands from a higher ranking control means, for example in the form of a microprocessor, which, due to empirical values, makes a radial adjustment for the sliding surface 112 possible, so that the carding space always maintains the desired target value.

[0103] It is possible for example, to take into account the run-up and/or slow-down behaviour of a card in such a way that the impending, time-dependent changes, caused by centrifugal force and thermal expansion of the carding space, which are known due to measurements or historical values, are being regulated by the higher ranking control means. This can take place in that corresponding, time-dependent target values for the carding space are being supplied by the higher ranking control means to the control 114, so that this control regulates, by radial adjustment of the sliding surface 112 the otherwise impending changes of the carding space. Both the expansion due to centrifugal force and the thermally caused expansion lead to a reduction of the carding space, so that the sliding surfaces 112 must be adjusted in radially outward direction, in order to set the carding space back to the nominal space.

[0104] Likewise it is possible to consider empirical values for the wear of the flat clothings 44 and the cylinder clothing 68 and to make a radial adjustment of the sliding surface 112 in such a way, that the carding space A despite wear of the clothings remains at least basically constant.

[0105] Furthermore it is possible, to record the effect of sharpening procedures on the carding space and to carry out a corresponding time-adapted adjustment of the radially outer sliding surface 112 via the control 114, so that the carding space A always has the target value. Both wear of the clothings and sharpening procedures lead to an increase of the carding space, so that here a radially inward directed adjustment of the sliding surfaces 112 is necessary, in order to compensate the impending enlargement of the carding space and to keep this at least basically constant. First attempts for a time-dependent control of an actuator for the radial adjustment of a flex bend are described in the EP-A-0 787 841. The present example is concerned with an adjusting element 108 in the form of a piezo type adjustment device requiring little space in radial direction.

[0106] More precisely said, and as can be seen from FIG. 5, this piezo-type adjustment device 108 consists of a multiplicity of strip-shaped elements laid one above the other and being provided with electrodes each, which, when connected with suitable control voltages, cause an enlargement or reduction of the radial thicknesses of the strips. The respective voltage is applied on the piezoelectric strips by way of the control 114 via lines 111, 113 which are schematically indicated in FIG. 4.

[0107] Since the radial change of thickness of such a piezoelectric strip is relatively limited, several such strips must be provided, in order to cover a reasonable adjusting range. The adjusting range required to accomplish the overall required micro-adjustments over the life span of the card amounts to about 0,2 to 0,3 mm maximum.

[0108] Since the arrangement shown in the FIG. 4 and 5 provides mainly the fine adjustment of the flex bend 104, it must be assumed—as was previously mentioned—that either the radially outer surface 110 of the radially inner support 102 due to respective treatment, has the desired position regarding to the axis of rotation of the drum or to the rotating circle of the clothing points 68 of the drum 16 respectively. Or the radially inner support 100 itself must be radially adjustable, for which for example an arrangement according to FIG. 2 and 3 could be applied. That means, the radially inner support 102 itself could be used as a kind of flex bend and being adjusted by means of radial adjustment devices like 76 in FIG. 2 and 3 by a fix bend 72, in order to achieve the initial adjustment of the carding space during manufacturing of the card or during renewal of the clothing (in the following called the basic adjustment). In order to accomplish this basic adjustment a set space of up to 2 mm is required.

[0109] Since such an radial adjustment of the radially inner support 102 means a not insignificant bending of this part, it can be useful—as shown in FIG. 7—to partition the radially inner support into individual radially inner supporting elements, which then can be adjusted in radial direction each for itself at the side frames 74 of the card, and afterwards they can be fastened to these, as is more closely described in the following.

[0110]
FIG. 6 shows a type of embodiment which in principle is very similar to the form of the embodiment according to FIG. 4 and 5. Instead of an oblong, piezoelectric adjusting element 108 several individual piezoelectric adjusting elements 116 are used here, whereat in the illustration of the FIG. 6 eight such adjusting elements are shown. However there could also be distinctly more such piezoelectric adjusting elements. Here also a radially inner support 102 and a radially outer flex bend 104 are applied, whereat the piezoelectric adjusting elements 116 form the centre core and individual piezoelectric adjusting elements 116 have a space 118 from each other.

[0111] In this example and in all following examples the same reference numerals are used for the respective same parts. If not otherwise stated it is understood that the previous description will also apply for further embodiments for some of the parts.

[0112] Accordingly the small box 114 refers also here to a control or regulating means, which is furnished with a direct current energy source 115 (here schematically shown in the form of a battery) and which either receives measured values for the carding space A from a corresponding measuring instrument or control commands from a higher ranking control means—as described so far.

[0113] Since separate elements are used for the piezoelectric adjusting elements 116 all these elements must be parallel controlled, if a radial adjustment of the radially outer sliding surface 112 of the flex bend 104 is aimed for.

[0114] Thus from the control means 114 corresponding control lines 111 and 113 lead to the respective piezoelectric adjusting elements.

[0115] The piezoelectric adjusting elements 116 can consist of simple piles of several piezoelectric elements, whereat then in principle each pile has the same expansion behaviour as in the type of embodiment according to FIG. 5. Or they can consist of specific piezoelectric translators which are laid out for a larger adjusting range.

[0116] A possibility to realize such a piezoelectric adjustment device is shown and described in the DE-A-198 33 782 in the form of a drive arrangement for a printing head. With the arrangement shown there, a compact piezoelectric drive component together with the application of corresponding levers, adjustments within the range of up to 2 mm can easily be achieved, which might be sufficient for the adjustment of the carding space A, not only in the sense of the micro-adjustment, but also in the sense of the original adjustment during manufacturing or during renewal of the clothing of the card. Since with a piezoelectric element the impending dimensional change is proportional to the applied voltage, the extent of the radial adjustment can be defined by the value of the applied voltage.

[0117] It is also possible to use a part of the piezoelectric drive arrangement according to DE-A-198 33 782 for example if such arrangements are used only for the micro-adjustment. For example the piezoelectric drive arrangement could be limited to the piezoelectric elements with the yoke or to the piezoelectric elements with the yoke and with the flexible strips, so that only the first stage of enlargement or the first and second stage of enlargement is being applied.

[0118] If the adjusting elements are not only used for the micro-adjustment, but also for the basic adjustment, then it is necessary to control the piezoelectric elements individually so that different radial adjustments can be made at the respective spots along the flex bend 104. If the individual piezoelectric adjusting elements 116 are used only for the micro-adjustment, then they can be controlled together, so that an even radial adjustment of the flex bends at the different engaging points of the piezoelectric adjusting elements 116 takes place.

[0119]
FIG. 7 shows an arrangement which is very similar to the arrangement according to FIG. 6, whereat for simplification the control equipment 114 with an energy source 115 and lines 111 and 113 is omitted. The difference to the embodiment according to FIG. 6 consists in principle of the fact that the radially inner support 102 here is not designed as a continuous element, but is divided into individual sections 102A whereat in the variant shown, a piezoelectric adjusting element 116 is assigned to each section 102A of the radially inner support. In addition, several piezoelectric adjusting elements 116 can be assigned to each section 102A, if this is wished by the technical designer for any reason.

[0120] The individual supporting elements 102A can be components of the side frames 74 of a card, or they can be—according to the double arrows 120—radially adjustably guided on each of the respective assigned side frames 74 of the card and be fastened for example by means of clamping screws 122 after adjustment on the side frames 74. This means that during manufacturing of the card or with the renewal of the clothing an adjustment can be made in the direction of the double arrows 120, for example by a mechanism like numeral 76 in FIG. 2 and 3. This initial adjustment can be defined by means of the clamping screws 122. The further adjustment for the micro-adjustment of the flex bend 104 is then made by the piezoelectric elements 116.

[0121]
FIG. 8 shows an alternative design of a sliding guide 100 according to the invention, here also with a radially inner support 102 and a radially outer sliding bend 104. In this example the centre core 106 is provided with adjusting elements which are designed as respective cushion elements 124 which are arranged with respective, mutual space 119 between each other at the centre core 106.

[0122] In this type of embodiment seven cushion elements are applied. However one could use more or less of said cushions. An individual cushion element is shown in FIGS. 9 and 10. Each element consists of upper and lower shell parts 126,128, which are welded together all around their boundary line 130 and which together define a cavity 132. This cavity 132 is connectable via a piping 134 to a pressure source, whereat over a corresponding control means 114 the prevailing pressure level in the chamber 132 is adjustable for each cushion individually or for all cushions together.

[0123] By increasing of the internal pressure in the chamber 132 this cushion element 124 expands and leads thus to a radially outward directed adjustment of the flex bend 104 and thus to a corresponding change of the carding space A. If the pressure in the chamber 132 is lowered the spring behaviour of the sheet metal or material respectively, used for the shells 126,128 leads to a reduction of the height of the respective cushion so that a radially inward directed adjustment of the flex bend 104 occurs.

[0124] Either air pressure or hydraulic pressure can be applied. Also here the control means 114 can be designed in the sense of a regulation and can regulate the carding space based on measured actual values to a given target value or to a target value gradient pattern respectively, or said control means can be laid out in such a way that it receives corresponding commands from a higher ranking control means and adapts the carding space A to the respective prevailing conditions, that means it can adapt to the respective target value i.e. to those changes of the carding space caused by centrifugal force and thermal influence as well as changes of the carding space due to wear during the course of time and through sharpening procedures. That means that the cushion elements can be used for the micro-adjustment.

[0125] Since with such cushion elements a radial adjustment is quite attainable within the range of some millimeters, they also can be applied for the initial adjustment for which they must be controlled individually.

[0126] Also here the radially inner support 102 in the form of sections 102A according to FIG. 7 can be realized. Then the individual sections 102A can, if necessary, be laid out radially adjustably according to the embodiment according to FIG. 7. Instead of cushion type adjusting elements also piston-cylinder arrangements can be put to use.

[0127] The embodiment according to the invention according to FIG. 11 to 13 is also concerned with a device for adjustment by means of a pressure fluid, i.e. compressed air or hydraulic liquid. With this type of embodiment the flex bend 104 has a T-shaped outline in its cross section which can be recognized from FIG. 12. The radially inner support 102 in contrast is of a U-shaped outline and has thus a radially outward open, U-shaped groove 136, into which projects the tongue 138 of the flex bend.

[0128] Between the lower end 140 of the tongue 138 and the bottom 142 of the U-shaped groove 136 there is a chamber 144 of a rectangular cross section wherein there is a hose 146. On the side walls of the radially internal support being of U-shaped cross section, there are friction linings 148 and 150, which rest against the corresponding sides of the tongue 138 and produce a friction force there, which avoids the generation of vibrations of the flex bend 104 with regard to the radially inner support 102.

[0129] By increasing or reducing the pressure within the chamber 144, which can take place by means of a line 134 according to FIG. 9, the flex bend 104 can be moved away in radial direction from the radially inner support 102 or towards the radially inner support.

[0130] From FIG. 12 it can be seen that the hose 146 is enclosed on all four sides, whereat it is well supported also due to the effect of a higher internal pressure and thus it cannot not burst. In order to lock the chamber being formed by the U-shaped groove 136 and the lower end 140 of the tongue 138 at their ends and to make sure that the hose 146 is supported also here and therefore cannot burst, plates 152 are attached according to FIG. 13 at the ends of the flex bend 104 with the T-shaped cross section, which are being shiftably guided within deeper made zones 154 of the groove 136. That means, that the ends of the hose 146 abut respective plates 152 and thus are also supported in this zone.

[0131] Furthermore with this type of embodiment the pressure prevailing in the chamber 144 can be controlled by a control means 114, whereat an increase of the internal pressure in the chamber 144, i.e. within the hose 146, leads to a radially outward directed shift of the flex bend 104. A reduction of the internal pressure, due to the forces which develop from the flat heads (dead weight of the flat bars plus force component due to the tension prevailing in the driving belt 48), leads to a radially inward directed shift of the flex bends.

[0132] Since the pressure in the chamber 144 is equal at all points along the flex bend 104, measures must be taken to achieve the desired even bending of the flex bend 104, so that its sliding surface 112 always remains circular.

[0133] A possibility to accomplish this is given by varying the radial dimension of the flex bend 104 along the length of the flex bend 104, so that under the prevailing forces it deforms in such a way that the sliding surface 112 always runs concentrically in relation to the axis of rotation 62.

[0134] Another possibility (not shown here) consists of distributing individual hose sections along the guidance bend 104 and to control these separately. With the separate control there is additionally the possibility to use the individual hose sections in such a way that by this the control for the basic adjustment is obtained during manufacturing of the card or during renewal of the clothing, and thereupon the hose sections are controlled in such a way that the micro-adjustment is used for compensation of deformations caused by the centrifugal force, thermal expansions, wear or sharpening procedures.

[0135] Since the compensation of deformations due to centrifugal force and thermal expansions, as a rule, require a radially outward directed movement of the flex bend, while the compensation of wear and/or the reduction in height of the clothings as cause of the sharpening procedures require a radially inward directed movement of the flex bend 104, it is to be made certain that the home position of the flex bend is such that movements are possible in both directions (this consideration applies to all forms of embodiments). That means, that in the starting position a certain pressure must already prevail in the pressure chamber 144.

[0136]
FIG. 14 and FIG. 15 show a further type of embodiment of a sliding guide 100 according to the invention. In this type of embodiment an adjusting element 160 in the form of a wave-shaped bimetallic strip with heating element is imbedded between the flex bend 104 and the radially inner support 102 within the centre core 106. An enlarged section of this bimetallic strip 160 is shown in FIG. 15. As is shown in this drawing, there are—in the usual manner with such bimetallic strip—two metal strips 162 and 164 of different thermal expansion which are fastened to one another at their boundary surface 166. The bimetallic strip rests within the centre core 106 with its end portions against the respective stops 168 and 170, so that at a temperature increase of the bimetallic strip said strip cannot grow in lengthwise direction, but the radial amplitude of the wave shape increases. Thereby the flex bend 104 is radially adjusted, that is, during a temperature rise in radial outward direction, away from the radially inner support 102, and in the case of temperature reduction in radial inward direction toward the radially inner support 102. With this type of embodiment only an even radial adjustment of the flex bend is possible along its entire circumference, so that this type of embodiment is suitable only for the micro-adjustment of the carding space. However, also here the radially inner support 102 itself can be radially shiftable or deformable or be divided into segments respectively, in order to accomplish the basic adjustment during manufacturing of the card or during renewal of the clothing.

[0137] Since—as already mentioned—the compensation due to changes of the carding gap caused by centrifugal force and warming-up, requires a radially outward directed movement, while the compensation of wear of the clothings or increase of the carding space due to sharpening procedures requires radially inward directed movement of the flex bend, the bimetallic strip should already be warmed up in the start-out condition, so that radial adjustments are possible in both directions.

[0138] The temperature control of the bimetallic strip preferably takes place by means of an oblong resistor element 171, which extends along the entire length of the bimetallic strip 160.

[0139] A current is sent through the lines 111 and 113 by the resistor element 172 from the control means 114, which is here operated either with a DC voltage energy source or—as shown—with an alternate current power source 11A. The reference numeral 174 points to a temperature sensor which is coupled with the control means 14 via a line 176 and which supplies the actual value for the respective temperature of the bimetallic strip. The control means 114 can therefore be designed as regulation means and be operated in such a way that the bimetallic strip has an actual temperature which corresponds with a given target temperature or a target temperature gradient, whereat the target temperature or the target temperature gradient respectively, correlate with the desired adjustment of the carding space.

[0140]
FIG. 16 shows a modified type of embodiment which in principle is very similar to the type of embodiment according to FIG. 14 and FIG. 15. Here, instead of one oblong, corrugated bimetallic strip, merely single leaf spring-type bimetallic strip elements 160A are used, whereat in the illustrated type of embodiment there are eight of those applied altogether, however, other amounts of bimetal elements, i.e. more or less, are also possible.

[0141] As is illustrated in FIG. 17 each bimetal element has its own control means 114 so that the bimetallic strips can be controlled individually. With this type of embodiment as likewise with the type of embodiment according to the FIG. 14 and 15, the radially inner support 102 can easily be designed segment-like according to the type of the embodiment according to FIG. 7. The basic adjustment can be achieved by adjusting of the corresponding segments 102A.

[0142] With the type of embodiment according to the FIG. 15 and 16 the bimetal elements can be used in order to realize both the basic adjustment and the micro-adjustment of the carding space since, with such bimetallic strips, the necessary amplitude of motion can be realized. In this type of embodiment it is also necessary to operate the bimetallic strips at a temperature during starting condition, said temperature being above the ambient temperature so that radial adjustments of the sliding surface 112 of the flex bend 104 are possible both radially inward and radially outward which is possible through reduction or increase respectively, of the temperature of the respective metal strips.

[0143]
FIG. 18 shows a sliding guide 100 according to the invention which at first sight is very similar to the sliding guide of FIG. 16. The leaf spring-type elements 180 however are not bimetallic strips, but only simple leaf springs, as can be seen from FIG. 19. The radial adjustment with this type of embodiment takes place only by way of the tension of the driving belts 48. If in fact the sliding surfaces 112 of the flex bends 104 are to be adjusted radially outward, the tension of the drive belts is lowered and these then exert smaller forces over the flat heads 46 onto the sliding surfaces 112, so that the leaf spring elements 180 can expand and the desired movement of the sliding surfaces 112 takes place radially outward. If instead the position of the sliding surfaces 112 is to be adjusted radially inward, then the tension of the driving belts is increased, for example by putting a braking force onto the axis of rotation 182 of the gearwheel 26 according to FIG. 2 (if necessary with an increase of the torque on the axle 60 of the gear wheel 20) whereat the forces acting in radial direction, which are applied by the flat heads onto the flex bend 104, increase and the desired adjustment of the sliding surface 112 takes place radially inward.

[0144]
FIG. 20 shows a possible, modified type of embodiment of the FIG. 18, where coil springs 190 are used instead of leaf springs 180, whereat several pressure exerting-type coil springs 190 are applied, which are arranged and distributed along the flex bend as is indicated by the radially extending, broken lines.

[0145]
FIG. 21 and FIG. 22 show a further type of embodiment according to the invention of a sliding guide 100 which is equipped with a spring element 200. This spring element 200 consists of an oblong plastic element, for example made of polyurethane, which is located in the bottom zone of the groove 202 of a U-shaped flex bend 104. With this type of embodiment the cross section of the radially inner support has an upside-down T-shaped outline, whereat the spring element 200 together with the radially inner support 102 extends into the groove 202 of the flex bend 104 and the upper surface 206 of the inner support 102 presses onto the lower side of the spring element 200.

[0146] The control of this type of embodiment takes place—as in the type of embodiments according to FIG. 18 to 20—by way of the control of the tension of the driving belts 48. Also an arrangement in reverse would be possible, i.e. an arrangement in which the flex bend 104 has a T-shaped cross section and the radially inner support 102 a U-shaped cross section, as can in principle for example be seen in FIG. 12. With all these variants of embodiments applying spring type elements, whether these are ordinary spring elements or bimetallic strips, it can be of advantage to provide friction absorbers so that the flex bends 104 do not tend to develop vibration.

[0147] The friction absorbers can for example have the form of friction linings which are attached on corresponding cheeks of the element (radially inner support 102 or flex bend 104) and co-operate in each case with corresponding friction surfaces of the mating element as shown with 148 and 150 in FIG. 12.

[0148] The FIG. 23 and 24 show a type of embodiment according to the invention of a sliding guide 100 which works with adjusting elements 220 in the form of roller elements which are adjusted electro-magnetically.

[0149] In this type of embodiment the radially inner support 102 is of wedge-shaped rising elements 222 which co-operate with the roller elements 220. These in fact contact the wedge-shaped elements 222 on their lower surface and on their top side they contact the radially inner surface 224 of the flex bend 104. The ends 206 and 208 of the respective roller elements 220 are held in corresponding holes of respective lateral guide plates 210 and 212. The plate elements 210, 212 can be shifted by a common pushing member 214 according to the double arrow 216 in the clockwise or anti-clockwise direction along the sliding bend 104, whereat the applied thrust is being derived from an electromagnetic actuator 218 which is controlled by a control means 114.

[0150] The concerned electromagnetic actuator 218 can be a linear, electromagnetic motor or it can also be a rotary drive, whereat the element 214 would then have to be provided as a screw spindle which co-operates with a nut element which engages at a yoke 215 of the two plate elements 210, 212.

[0151] With the movement in clockwise direction the rollers 220 are moved along the wedge-shaped elements in the sense that the flex bend 104 is shifted radially outward. If in contrast a radially inward directed movement of the flex bend 104 is to take place, then the rollers 220 are moved in anti-clockwise direction along the wedge surfaces, whereat the flex bend 104, due to the pressure forces of the flat bars (dead weight of the flat bars plus radial tension component due to the driving belt tension) is pressed inward.

[0152] This type of embodiment is suitable particularly for the fine adjustment. It would however be possible, if the wedge-shaped elements could be shifted in a respective radial direction, for example by means of adjusting bolts which extend in radial direction within the radially inner support, to use this type of embodiment also for the basic adjustment, provided that the side plates 210, 212 have a certain flexibility. In principle one could also shift each roller element 220 separately by itself in relation to the other elements according to the double arrow 216 in order to make the basic adjustment and thereafter move all roller elements 220 evenly in order to realize the micro-adjustment.

[0153] Finally FIG. 25 shows a further type of embodiment of a sliding guide 100 according to the invention which works according to the principle of a magnetic suspension railway. The flex bend 104 in fact is provided with several permanent magnets 240 which are all arranged in such a way that the north poles point radially inward (or the south poles).

[0154] Within the radially inner support 102 are electromagnets 242 inserted opposite each permanent magnet 240, said electromagnets are operated in such a way that radially outward directed front ends, i.e. the front ends which oppose the permanent magnets 240 also represent north poles. Thus magnetic forces act between the radially inner support 102 and the flex bend 104 which tend to shift the permanent magnets 240 and therefore the flex bend 104 in the direction radially away from the radially inner support 102.

[0155] The electromagnets 242 which are only partly represented by broken lines, consist of a magnet core 246 of a magnetizable material, such as soft iron and a coil 248 which is controlled by a control means 114. By means of the control of the amperage of the electric current which flows through the coil 248 the strength of the magnetic force can be controlled which acts between the electromagnets 242 and the permanent magnets 240. If the flex bend 104 itself moves away from the radially inner support 102 due to these magnetic forces, the forces, which are exerted on the flex bend 104 decrease by the increasing gap width. Each of the flex bends 104 finds its balanced position if the forces, which come from the electromagnets 242 due to the radially inward directed forces which act on the sliding surface 112 (dead weight of the flat heads 46 and radial component of the driving belt tension), become compensated.

[0156] Thus it is evident that by increasing the electric current through the coils 248 the radial width of the gap 250 can be increased and vice versa. Since the electromagnets 242 can be controlled individually and air gaps of up to 3 mm are possible without any problems, this type of embodiment can be applied both for the micro-adjustment and for the basic adjustment. Here, also however, the arrangement must be operated in such a way that in the starting condition a certain current flows through the respective electromagnets 242 so that both radially inward directed movements of the flex bend 104 and radially outward directed movements are possible.

[0157] Another attractive version would be possible by which the flex bends 104 are being supported by radially outward acting compression springs, as for example numeral 190 with the type of embodiment according to FIG. 20, and where, due to opposite polarity of the permanent magnets 240 and electromagnets 242, the flex bends 104 are being drawn into the direction of the respective radially inner support 102, whereat the compression springs are compressed. The system always finds its equilibrium if the forces, which are being generated by the compression springs 190, become balanced by the radially inward directed forces which act from the electromagnets, whereat naturally also the further forces acting in radial direction (dead weights of the flat heads 46 and radial tension component of the tension of the driving belt) must be considered.

[0158] The magnets 240 need not necessarily be realized as permanent magnets; also these could be designed as electromagnets. Accordingly then the electromagnets 242 could be replaced by permanent magnets. Also other arrangements of repulsive or attracting forces generating magnets are possible.

Device for adjusting the work gap between the points of flat clothings and the points of the cylinder clothing of a card

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