Abstract:
Circular comb for a combing machine for combing textile fibers, comprising a base body with a center longitudinal axis, a peripheral surface and two end faces, a plurality of bar tacks, which are arranged on the peripheral surface of the base body and define a combing region of the circular comb, a plurality of fastening devices attached to the base body for the non-positive connection of one of the bar tacks in each case to the base body and unlocking units to release the non-positive connections, each unlocking unit having an unlocking device and an unlocking means to actuate the unlocking device, wherein the unlocking units are accessible from outside the combing region, in particular from at least one of the end faces, and an additional positive securing connection to secure the bar tacks is provided on the base body.

Description:
RELATED APPLICATIONS 
     This application claims the priority of German Patent Application, Serial No. 10 2009 018 058.3, filed Apr. 21, 2009, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein. 
     FIELD OF THE INVENTION 
     The invention relates to a circular comb for a combing machine for combing textile fibres. 
     BACKGROUND OF THE INVENTION 
     Combs for use in combing machines are known in the form of round combs from public prior use, at least one comb element, which is engaged with the fibres to be combed, being arranged on a base body. A comb, which has a plurality of comb elements along its entire periphery, is called a circular comb. The active combing region may be, in this case, 78°, 90°, 111°, 180° of the periphery of the surface line of the comb. Circular combs are also known, in which the entire surface line is taken up with comb elements, such as needles, needle strips, saw-tooth wire portions, comb teeth or saw-tooth stamped parts. These comb elements, which are per se preassembled, are also called bar tacks. 
     SUMMARY OF THE INVENTION 
     A bar tack thus has a plurality of saw-tooth stamped parts arranged one behind the other in the direction of a centre longitudinal axis of the base body or also toothed discs with teeth. The teeth wear because of their mechanical engagement in the fibres to be combed, so it is necessary for the bar tacks to be replaceable in design. For this purpose, various fastening devices are known: 
     Card clothings for flat lids of a carding machine are disclosed in DE 43 26 203 C1, EP 0 091 986 A1 and EP 0 322 472 A1, the card clothing consisting, similarly to a bar tack of a circular comb, of a plurality of saw-tooth wire strips arranged in parallel to one another. The individual saw-tooth wire strips are placed in a row on a base body and held by a positive connection by means of adjacent fastening strips. The lateral fastening of the saw-tooth wire strips on the base body can also take place by means of clamping, in other words by a non-positive connection. As EP 0 322 472 A1 shows, the individual saw-tooth wire strips can be repeatedly bent in the arrangement direction. The fastening of the card clothing on the cover of the carding machine also takes place by means of the fastening strips, which are pushed onto the cover. 
     A similar fastening system of toothed discs on a bar tack of a circular comb is known from DE 25 03 976 C3, the individual toothed discs of a bar tack being clamped by means of a spring clamp onto a bar section. The entire bar tack is screwed to the base body of the circular comb. This type of fastening of the bar tack on the base body is also known in principle from GB 274 698 and DE 30 05 399 A1, a better seat of the bar tacks on the base body being achieved, according to the latter, in that they additional have a clamping strip and are arranged therewith in a recess of the base body corresponding thereto. 
     Further configurations of clamping strips are known from DE 30 07 245 A1, EP 0 249 706 A2, EP 0 179 158 B1 and EP 0 839 934 A1, a screwing connection of the clamping strips in the operating state, in other words when the bar tack is pushed on, being accessible from the inner wall of the hollow cylindrical base body. This accessibility of the screw connections from the inner wall of the base body is limited. On the other hand, a clamping strip is positively held according to EP 1 523 591 B1 both in the base body and in the bar tack. The assembly and disassembly of this comb are very laborious. 
     Furthermore, various possibilities for positively connecting bar tacks in the form of tooth clothings on the base body of a round comb are described in EP 1 533 404 A1. 
     According to U.S. Pat. No. 4,716,629, the fastening of a bar tack in a base body takes place by means of a resilient clamping element, which may, for example, be configured as a slotted sleeve. The clamping element is inserted into a groove, which is formed by the base body and the bar tack and extends parallel to the centre longitudinal axis of the base body. The holding force of a clamp with a clamping element of this type is low. Moreover, an additional securing of the clamping element against unintentional release is necessary. 
     It therefore applies to all the fastening systems mentioned that an assembly and disassembly of the bar tack to or from the base body of the circular comb is only possible by laborious assembly and retrofitting operations. This takes place, for example, by means of numerous screwing operations of the clamping and fastening strips and/or by axially pushing them on in the direction of the centre longitudinal axis of the base body, causing long setting up times and therefore stoppage times of the combing machine. 
     Spring-like holding parts, which are rigidly connected to the base body of a circular comb and on which the bar tack is placed and held as a result of the resilient spring force, are known from EP 0 253 071 A2. The simplified assembly process is counteracted by a reduced mechanical holding force between the bar tack and the base body. 
     DE 10 2006 005 605 A1 discloses a device on a carder, wherein a clothing is held by a magnet. The translational speed of the carder is significantly reduced in comparison to the rotational speeds of the circular comb conventional in combing machines, so that the centrifugal forces acting on a bar tack of the circular comb, which quadratically depend on the rotational speed, are significantly greater than the negligible centrifugal forces acting on the carder. The magnetic holding force for the clothing of the carder is configured thereon to withstand the effects of force on the clothing caused by the process, these effects of force caused by the process being smaller than those which act on a bar tack of a circular comb when combing fibres. 
     It is therefore an object of the invention to design a circular comb for a combing machine in such a way that a bar tack can be directly and quickly connected to a base body, it being impossible to release the connection even with high loads. 
     This object is achieved according to the invention by a circular comb, in which the unlocking units are accessible from outside the combing region, in particular from at least one of the end faces, and an additional positive securing connection to secure the bar tacks is provided on the base body. 
     It was recognized according to the invention that a circular comb with a base body and a plurality of bar tacks connected thereto in a non-positive manner has unlocking units, which in each case comprise an unlocking device and an unlocking means, and a securing of the connection of the bar tacks to the base body against unintentional release is ensured by an additional positive connection. The bar tack can be released from the base body by actuating the unlocking device by means of the unlocking means, the unlocking process being facilitated, in particular because of the arrangement of the unlocking units outside a combing region, which is determined by the bar tacks, and, in particular on the end faces of the base body because of the good accessibility. Moreover, owing to the additional positive securing connection between the bar tack and the base body, a secured connection of the two components to one another is guaranteed in case, in the event of damage, the non-positive connection between the bar tack and the base body is not maintained. This is relevant, in particular, for circular combs, which are used at high rotational speeds of up to 500 min −1  and with a high comb load, so that a bar tack, which could possibly be released from the base body as a result of the very high force loads during combing operation, does not cause damage to the combing machine. A further advantage of the circular comb according to the invention is the uncomplicated configuration of the geometry of the base body, resulting in a reduction in its production costs, and therefore the production costs of the circular comb as a whole are reduced. 
     In a circular comb, in which the positive securing connection between one of the bar tacks and the base body in each case has a radial play, the positive securing connection between one of the bar tacks and the base body has radial play, so the positive connection only engages if the non-positive connection between the bar tack and base body is removed. The non-positive connection, which is present in the usual operation of the combing machine, is free of play. 
     Owing to the configuration of the radial play being smaller than a radial spacing of the bar tack non-positively connected to the base body from a machine wall of the combing machine, it is ensured that in the case of unintentional release of a bar tack from the base body during running operation of the combing machine, destruction of said combing machine by the released bar tack is avoided. 
     By using a bar tack and a fastening device designed such that assembly and disassembly of the bar tack on or from the base body substantially take place in the radial direction, it is possible to carry out the assembly and disassembly of the bar tack on or from the base body substantially in the radial direction in the combing machine. This dispenses with the withdrawal of the bar tack from the base body of the circular comb and therefore simplifies the necessary setting-up processes and therefore shortens the time outlay required for this. Moreover, a partial integration is possible in that a drive shaft of the combing machine and a base body, which is generally assembled on the drive shaft, are combined in the base body according to the invention. Production and assembly costs of the combing machine are therefore reduced. Moreover, the necessary space requirement in and on the combing machine is reduced when the unlocking means is assembled. 
     The use of an unlocking opening in the base body, which extends parallel to the centre longitudinal axis, as an unlocking device, and an unlocking pin, which can be moved to release the non-positive connection in the unlocking opening, as an unlocking means, makes possible a particularly rapid and easy unlocking of the bar tack from the base body by releasing the non-positive connection. Moreover, a very compact construction of an unlocking unit of this type is possible as the unlocking opening is integrated in the base body. Furthermore, the assembly and disassembly process between the bar tack and the base body is facilitated by using the radial play, the securing function of the positive connection being maintained at the same time. 
     With the design of a circular comb, in which the bar tack and the fastening device are designed such that a combing force acts as a closing force in a securing manner on the bar tack, a combing force active during combing operation acts as an additional securing mechanism on the non-positive connection of the fastening device to the base body, so the risk of unintentional unlocking of the fastening device and therefore a release of the bar tack is additionally reduced. 
     A fastening device comprising a profile strip and a leaf spring is distinguished by a compact and integrative mechanical structure. 
     A circular comb, in which each profile strip has a top piece with at least one laterally projecting nose to engage in undercut recesses of the bar tack, allows a secure and, at the same time, assemblable and disassemblable connection of the bar tack to the connection device. 
     Owing to the design of the fastening device and a bar tack, in which a T-shaped top piece with two laterally projecting noses, at least one nose, in the direction parallel to the centre longitudinal axis, having interruptions, which correspond with corresponding recesses of the bar tack for the assembly and disassembly thereof, assembly and disassembly of the bar tack on or from the base body take place easily and quickly. By displacing the bar tack parallel to a centre longitudinal axis of the base body by a certain amount of length, the bar tack can be inserted in or removed from the base body in the radial direction. 
     An assembly or disassembly process of a bar tack on the circular comb is additionally simplified with a fastening device comprising an L-shaped top piece with a laterally projecting nose. 
     With a circular comb, in which the leaf spring, to non-positively connect the bar tacks and base body, is held with a first spring part region in a receiving groove of the profile strip and rests with a second spring part region on a shoulder of a fastening groove of the base body, the non-positive connection of the bar tack and base body is produced by a prestressed leaf spring. The resulting holding force of the bar tack on the base body can be adjusted by adaptation of the leaf spring. 
     A fastening device, in which each profile strip has an T-shaped base with a contact face provided on a T-shaped side projection, wherein the contact face, to form the positive securing connection, can rest on the leaf spring and therefore indirectly also on the shoulder of the fastening groove and wherein the radial play is determined by the design of the contact face, the leaf spring and the fastening groove, allows the use of the radial play by unlocking the non-positive connection of the bar tack in the base body for disassembly. 
     A circular comb, in which the unlocking pin is rotatably arranged in the unlocking opening and the contour of the cross-sectional face of the unlocking pin running perpendicular to the centre longitudinal axis is not round, allows a simple unlocking process in that the unlocking pin is inserted in the unlocking opening and rotated about a longitudinal axis of the unlocking pin. 
     A fastening device, in which the fastening device is a rod-shaped magnet, the non-positive connection between the bar tack and the base body being provided by the magnetic force of the magnet, allows very good integration into the base body. Moreover, the effect of force on the holding force of the bar tack on the base body is integrated in the fastening device. The magnetic holding force of the fastening device can be influenced by the design thereof. 
     A fastening device, in which the magnet is a permanent magnet, ensures a secure and lasting holding force on the bar tack. 
     By using a fastening device, in which the magnet is an electromagnet, the magnetic effect of which can be activated and deactivated by means of a switch, the effect of force on the bar tack, in particular for an assembly or disassembly process, can be interrupted and then reproduced. 
     A particularly compact structure of the circular comb is produced by an arrangement of the fastening device, in which the magnet is rigidly arranged in a fastening groove of the base body. 
     In a circular comb, in which each bar tack has a hook-like step, which, to form the positive securing connection, engages in a receiving opening of the fastening groove limited by a projection, the radial play being determined by a radial spacing provided in a non-positive connection between the projection and the hook-like step engaging below the projection, the bar tack is secured by the positive securing connection against unintentional release from the non-positive connection of the bar tack on the base body. In this case, the bar tack and the base body are designed in such a way that with an existing non-positive connection, a radial play is present between the bar tack and the base body, which facilitates the assembly and disassembly of the bar tack on or from the base body. 
     With a circular comb, in which the magnet has a C-shaped cross-section perpendicular to the centre longitudinal axis, the unlocking opening being formed by the magnet and the bar tack connected thereto, the unlocking opening is integrated into the structure of the circular comb and does not have to be introduced into the base body of the circular comb in an additional manufacturing step. 
     The use of an unlocking pin in a circular comb which is conical at least in portions allows rapid and direct unlocking of the bar tack from the base body by insertion of the unlocking pin parallel to a centre longitudinal axis of the base body into the unlocking opening. 
     The exchange process of a worn bar tack is simplified with a configuration of the fastening devices and the unlocking units, in which the fastening devices and the unlocking units are attached to the base body in such a way that they are connected, both during combing operation and also during assembly and disassembly of the bar tack on or from the base body, to said base body and can be brought, at least partially, into a loosened, but not completely separated assembly or disassembly state. 
     It is a further object of the invention to design a circular comb for a combing machine in such a way that a bar tack can be connected directly, rapidly and without additional aids to a base body. 
     This object is achieved according to the invention by a circular comb, in which the unlocking units are accessible from outside the combing region, in particular from at least one of the end faces, and the fastening devices and the unlocking units are attached to the base body in such a way that both during combing operation and also during assembly and disassembly of the bar tack on or from the base body, they are connected to the latter and can, at least partially, be brought into a loosened, but not completely separated assembly or disassembly state. 
     The advantageous configurations described above can also be used in such a circular comb. 
     It was recognized according to the invention that a circular comb with a base body and a plurality of bar tacks non-positively connected thereto has fastening devices and unlocking units, which in each case comprise an unlocking device and an unlocking means. Both the fastening devices and the unlocking units are releasably attached, in particular, to the base body and, to assemble and disassemble the bar tack to or from the base body, remain mounted thereon. They are attached to the base body in such a way that both during combing operation and during the assembly and disassembly of the bar tack on or from the base body, they remain connected thereto and can be brought, at least partially, into a loosened, but not completely separated assembly or disassembly state. As a result, an exchange process of a worn bar tack is simplified. 
     An unintentional release of the bar tack from the base body is prevented by a circular comb, in which an additional positive securing connection is provided to secure the bar tacks on the base body. 
     Embodiments of the invention will be described in more detail below with the aid of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of a circular comb with nine bar tacks fastened thereon in the peripheral direction; 
         FIGS. 2 and 3  show enlarged views of a fastening device shown in  FIG. 1  according to a first embodiment, comprising a profile strip in the locked and unlocked state; 
         FIG. 4  shows a perspective view of a profile strip for use in a circular comb according to the first embodiment; 
         FIGS. 5 and 6  show views similar to  FIGS. 2 and 3  of a fastening device according to a second embodiment of a circular comb; 
         FIGS. 7 and 8  show views similar to  FIGS. 2 and 3  of a fastening device according to a third embodiment of a circular comb; and 
         FIG. 9  shows a view similar to  FIGS. 2 ,  5  and  7  of a fourth embodiment of a circular comb with a rod-shaped magnet as the fastening device. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A circular comb  1  shown in  FIG. 1  has a hollow cylindrical base body  2  with a centre longitudinal axis  3 , an outer peripheral surface  4  and two end faces  5 , of which only one is visible. The base body  2  is placed on a drive shaft  6 , which is also hollow cylindrical. It is also possible for the base body  2  to be driven directly, in other words without an additional drive shaft  6 . For this purpose, the base body  2  can be configured both as a hollow and as a solid shaft. 
     A total of nine bar tacks  9  fastened in each case by means of a fastening device  8  are attached to the base body  2  in the peripheral direction  7 . The bar tacks  9  define, with their axial extent parallel to the centre longitudinal axis  3 , a combing region of the circular comb. 
     Each fastening device  8  comprises a profile strip  10  and a leaf spring  11 , by means of which the respective bar tack  9  is fastened non-positively to the base body  2 . To unlock the non-positive connection, an unlocking means in the form of an unlocking pin  12  is used, which is arranged in an unlocking device, which extends as an unlocking opening  13  proceeding from at least one of the end faces  5  in the base body  2  parallel to the centre longitudinal axis  3 . Thus, the unlocking opening  13  is accessible from outside the combing region. To unlock the non-positive connection between the bar tack  9  and the base body  2 , the unlocking pin  12  can be introduced into the unlocking opening  13  and moved within the latter (here: rotated). During the combing operation of the circular comb  1 , for weight and safety reasons, no unlocking pin  12  is generally provided in the unlocking opening  13 . 
     Each bar tack  9  comprises a plurality of identically punched toothed discs, which are placed in a row one behind the other in the direction of the centre longitudinal axis  3  and connected to one another. Each toothed disc has a plurality of teeth  14 , which engage in the fibres to be combed. The bar tacks  9  are fastened to the base body  2  in such a way that each bar tack  9  has a radial spacing  15  from a machine wall  16  of a combing machine. 
     The fastening device  8  of the circular comb  1  is shown enlarged in  FIGS. 2 and 3 . The fastening device  8  is inserted in a fastening groove  17  of the base body  2 . In this case, the profile strip  10  has a substantially double-T-shaped cross-sectional face, a T-shaped base  18  to positively receive the profile strip  10  being provided in the fastening groove  17  and a T-shaped top piece  19  with laterally projecting noses  20  being used to engage in an undercut recess  29  of the bar tack  9 . 
     The unlocking opening  13  is arranged adjacent to the fastening groove  17  and connected thereto, so the fastening device  8  can be actuated with the inserted unlocking pin  12 . 
     The base  18 , on a first T-side projection  18   a , has a contact face  21 , adjoined by a receiving groove  22 , in which the leaf spring  11  is held by a first spring part region  11   a . The fastening device  8  is inserted into the fastening groove  17  in such a way that the leaf spring  11 , which rests with a second spring part region  11   b  on a shoulder  17   a  of the fastening groove  17  formed by a first undercut, is prestressed, as the spring force of the leaf spring  11  in the radial direction  23  with respect to the centre longitudinal axis  3  is directed inwardly. The fastening device  8  is pressed inwardly in the radial direction  23  thereby, the prestressing of the leaf spring  11  resulting from an abutment of the bar tack  9  on contact regions  24  of the peripheral surface  4 . 
     As a result of the adjacent arrangement of the contact face  21  and the leaf spring  11  held in the receiving groove  22 , a radial play  25  of the fastening device  8  in the fastening groove  17  is produced. The size of the radial play  25  can be fixed by the design of the contact face  21  facing the shoulder  17   a , the leaf spring  11  and the fastening groove  17 . Since the contact face  21  has a bevel, the radial play  25  is additionally increased. When the base  18  lies with its contact surface  21  on the leaf spring  11  and therefore indirectly also on the shoulder  17   a , the radial play  25  becomes zero, so the positive securing connection is formed. The radial play  25  is smaller than the radial spacing  15 . This ensures that if the non-positive connection is released between the bar tack  9  and the base body  2 , no damage to the machine wall  16  and therefore the combing machine as a whole takes place. The bar tack  9 , apart from the non-positive connection, is also thereby positively connected to the base body  2 . With an active non-positive connection, in other words during normal operation of the combing machine, the positive securing connection does not engage, but has the radial play  25 . 
     The base  18  furthermore comprises a second T-side projection  18   b  with a curvature  18   c  to rest in the fastening groove  17 . On actuation of the unlocking pin  12 , the profile strip  10  can pivot about a pivot axis  18   d  parallel to the centre longitudinal axis  3  by a certain angular amount, which is limited by the maximum radial play  25 . In this case, the profile strip  10  runs along the curvature  18   c  in a second undercut of the fastening groove  17  in an unlocking direction. A combing force occurring during combing operation acts as an additional closing force. The bar tack  9  then acts on the profile strip  10  in such a way that the latter rolls with the curvature  18   c  counter to the unlocking direction and is thus additionally held in the fastening groove  17 . The combing force is produced as the resultant of the individual combing forces on the individual teeth of the bar tack  9 . As a result, the non-positive connection between the bar tack  9  and the base body  2  is additionally secured and therefore increases the securing of the circular comb  1  against unintentional release of the bar tack  9  from the base body  2 . 
     The unlocking openings  13  reach at least up to at least one of the end faces  5 , so an actuation of the unlocking opening  13  with the unlocking pin  12  with a fully occupied circular comb is possible without providing accessibility of the base body  2  from its inside. As shown in  FIG. 3 , the unlocking pin  12  inserted in the unlocking opening  13  has a contour, the cross-sectional face of which perpendicular to the centre longitudinal axis  3  is not round and comprises a flattened side  26 . 
     The unlocking of the bar tack  9  from the base body  2  will be described below with the aid of  FIGS. 2 and 3 . Proceeding from the prestressed arrangement of the fastening device  8  and the bar tack  9  in the base body  2  according to  FIG. 2 , the unlocking pin  12  is inserted into the unlocking opening  13  in such a way that its flattened side  26  is oriented parallel to a lower side  27  of the base  18 . The unlocking pin  12  is then rotated automatically or by hand, for example by means of a special tool about the longitudinal axis  28  thereof. Because of its non-round contour, the unlocking pin  12  comes to rest in the unlocking opening  13  and simultaneously on the lower side  27 , as a result of which the profile strip  10  is pressed in the radial direction  23  outwardly against the spring force of the leaf spring  11  (cf  FIG. 3 ). In this state, the abutment of the top piece  19  with its noses  20  in contact flanks  30   a  of an undercut recess  29 , which is substantially swallow tail-shaped, is dispensed with. Thus, gaps  30  are produced between the T-shaped top piece  19  of the profile strip  10  and the undercut recess  29  of the bar tack  9  in the regions of the noses  20  and the recess  29  on which there was previously contact, in the unlocked state. The gaps  30  allow a displacement of the bar tack  9  along the centre longitudinal axis  3 , as the mechanical holding force of the leaf spring  11  is removed. 
       FIG. 4  shows the profile strip  10  in a perspective view, whereby it becomes visible that the nose  20  of the T-shaped top piece  19  arranged above the contact face  21  has interruptions  37  in the direction parallel to the centre longitudinal axis  3  of the base body  2 . With recesses of the bar tack  9  corresponding to this, assembly and disassembly of the bar tack  9  on or from the base body  2  is facilitated in that the profile strip  10  in the unlocked state is displaced in the direction of the centre longitudinal axis  3  by the amount of the longitudinal extent of the interruptions  37  and can be removed in the radial direction  23  when the interruptions  37  overlap with the recesses of the bar tack  9 , which have the same longitudinal extent as the interruptions  37 . As a result the pushing of the bar tack  9  onto the profile strip  10  over the entire lengths thereof in the direction of the centre longitudinal axis  3  is avoided, so that, in particular, a necessary space requirement on the combing machine is reduced and the assembly and disassembly process can be accelerated. 
       FIGS. 5 and 6  show a further embodiment of a circular comb  1 . Components which correspond to those which have already been described above with reference to  FIGS. 1 to 4  have the same reference numerals and will not be discussed again in detail. 
     An important difference of this embodiment from that described above is the design of the undercut recess  31  of the bar tack  32 . The recess  31  also has oblique contact flanks  33 , on which the noses  20  rest with an active non-positive connection between the bar tack  32  and the base body  2 . While a first side flank  34  is designed analogously to a swallow tail-shaped recess, a second side flank  35  is distinguished by a recess  36 , which extends in the bar tack  32  substantially in the peripheral direction  7 . 
     The disassembly process of the bar tack  32  from the base body  2 , which will be described below with the aid of  FIG. 5 , is simplified with the recess  36  in the following manner: 
     By actuating the unlocking pin  12  in the unlocking opening  13  by rotation about its longitudinal axis  28 , the profile strip  10 , as described above, is raised outwardly in the radial direction  23 . This results in a tilting of the profile strip  10  in the fastening groove  17  of the base body  2 . Because of the special design of the undercut recess  31 , the bar tack  32  can be raised in the unlocked position of the fastening device  8  from the peripheral surface  4  of the base body  2  and disassembled in the radial direction  23  from the base body  2 . For this purpose, a nose  20  is pushed into the recess  36 , so the raising of the bar tack  32  and therefore the radial disassembly is firstly made possible. 
       FIGS. 7 and 8  show a further embodiment of a circular comb  1 . Components which correspond to those which have already been described above with reference to  FIGS. 1 to 6  have the same reference numerals and will not be discussed again in detail. 
     An important difference of this embodiment from that described above is the design of the profile strip  10   a , which has an L-shaped top piece  19   a  with only one projecting nose  20 . 
     Therefore, with the unlocked non-positive connection, the bar tack  32   a , which comprises a recess  29   a  to receive the L-shaped top piece  19   a , can be directly withdrawn or lifted from the base body  2 . Furthermore, no bevel is provided on a contact face  21   a  of the first T-side projection  18   a , as, because of the design of the top piece  19   a , a comparatively small radial play  25   a  is sufficient to allow the unlocking process. The curvature on the second T-side projection  18   b  is configured as a plateau  18   e . The nose  20  of the top piece  19   a  is arranged on the same side of the profile strip  10   a  as the plateau  18   e  on the second T-side projection  18   b  and therefore opposing the leaf spring  11  and the contact face  21   a  adjacent thereto. 
       FIG. 9  shows a further configuration of a circular comb  1 . Components which correspond to those which have already been described above with reference to  FIGS. 1 to 8  have the same reference numerals and will not be discussed again in detail. 
     The important difference from the above-described embodiments of a circular comb  1  is the configuration of the fastening device which is configured as a rod-shaped magnet  38 . The magnet  38  is arranged in a fastening groove  39  of a holding body  40 , the holding body  40  being fastened in a holding groove  41  of the base body  2 . The fastening can, for example, take place by means of screwing or gluing. It is also possible for no separate holding body to be provided and for the fastening groove  39  to be directly incorporated in the base body  2 . 
     The holding force of the non-positive connection between the bar tack  42 , which is produced from ferromagnetic material, and the base body  2  is produced by the magnetic force of the magnet  38 , which can be configured as a permanent magnet or as an electromagnet, so the magnetic effect thereof can be activated and deactivated by means of a switch. 
     The bar tack  42  has a hook-like step  43 , which engages in a receiving opening  45  of the fastening groove  39  delimited by a projection  44 . The step  43  cooperates here with the magnet  38 , which has a T-shaped cross-section perpendicular to the centre longitudinal axis  3 , in such a way that side faces  46   a  and  46   b  of the step  43  are in contact with end faces  47   a  and  47   b  of the magnet  38 . As a result, the unlocking opening  48  is formed. With an active non-positive connection between the magnet  38  and the bar tack  42 , a radial play  49  is present between the step  43  of the bar tack  42  and the projection  44  of the fastening groove  39 . When the magnetic holding force of the bar tack  42  is released, the latter is moved outwardly in the radial direction  23 , the step  43  coming to rest with its outside  50  on an inner face  51  of the projection  44 . By a corresponding design of the fastening groove  39 , in particular the projection  44  and the step  43 , the desired size of the radial play  49  can be fixed. 
     The magnet  38  is configured as a rod with a C-shaped cross-section perpendicular to the centre longitudinal axis  3 , one C-end face being inclined inwardly and forming one end face  47   a  of the magnet  38 . Accordingly, the corresponding side face  46   a  of the step  43  is also configured in an inclined manner, so the resulting combing force occurring during the combing process acts as an additional closing force on the non-positive connection between the bar tack  42  and the base body  2 . The incline of the end face  47   a  and the side face  46   a  form an inwardly directed guide, which pulls the bar tack  42  inwardly under the influence of the combing force and therefore presses it on the base body  2 . 
     An unlocking pin, not shown, which is conical at least in portions and can be inserted into the unlocking opening  48  parallel to the centre longitudinal axis  3  or moved back and forth, is used to unlock the bar tack  42  from the fastening groove  39 . As soon as the magnetic holding force of the magnet  38  on the step  43  has been overcome by a corresponding positioning of the unlocking pin, the bar tack  42  can be displaced because of the existing radial play  49  in the fastening groove  39 . As a result, a release of the abutment of the bar tack  42  in the contact regions  24  takes place and thus the possibility of tilting about a pivot axis  52  parallel to the centre longitudinal axis  3 . 
     In this unlocked state, the bar tack  42  can be disassembled substantially radially outwardly from the fastening groove  39 . A displacement in the direction of the centre longitudinal axis  3  is unnecessary for the assembly and disassembly of the bar tack  42  on or from the base body  2 . Assembly of the bar tack  42  on the base body  2  takes place analogously to disassembly by pivoting the bar tack  42  with its step  43  into the receiving opening  45  of the fastening groove  39  and subsequent application of the magnetic holding force by bringing the step  43  of the bar tack  42  and the magnet  38  into contact. 
     Apart from the fastening devices mentioned, further configurations are possible to apply the holding force to a bar tack: 
     When using a tension band made of elastomer as the unlocking means, which is inserted into the unlocking opening and exerts a clamping force on the bar tack, it could be stretched by tensile loading and therefore its cross-section reduced in the direction of the centre longitudinal axis, so a release of the non-positive connection could take place. 
     Moreover, the holding force on a bar tack could also be produced in that a negative pressure is produced in the unlocking opening and is eliminated to release the connection by means of a venting and aeration line provided for this. 
     Alternatively, unlocking means would also be possible, which are produced from a shape memory alloy, so a shape of the unlocking means can be adjusted as a function of a required clamping or non-clamping effect. This could take place, for example, by varying the cross-section perpendicular to the centre longitudinal axis.