Device for guiding and coupling the sliding flat with the drive belt in a flat card

Abstract: A carding flat (7) and a system for guiding and driving it in a card with moving flats driven by toothed belts (23,33), in which coupling between the flats and belts is achieved by a form fit between cavities (26) and projections (28) without fixed retention means, so enabling these elements to freely rotate about the coupling axis.

Description: This invention relates to cards with sliding flats in which fibrous material in thin layer form is worked by a series of surfaces provided with a plurality of points of various shape, inclination and rigidity and driven to move relative to each other, in which the fibrous material is opened into single fibre form, the small trash particles being eliminated together with waste and tangles, the fibres undergoing mutual mixing to form a sliver of untwisted fibres to be fed to the subsequent working stages. To highlight the technical problems involved in carding and confronted by the present invention, the flat carding process is described briefly with reference to the scheme of Figure 1. The raw material 1 consisting of staple fibres collected into the form of a web of approximately rectangular cross-section is fed to the machine by a feed roller 2 which presses and controls it against the board 3 to feed a strip 4 to the opening cylinder 5. This cylinder is provided with clothing, ie points inclined in its direction of rotation, and is driven at a considerable rotational speed. The fibre strip 4 is hence roughly combed and distributed over the opening cylinder into a layer thinner than the original layer 1. During its anticlockwise rotation the fibre layer encounters clothed segments and blades for removing impurities, after which the fibres pass to the subsequent carding drum 6. The drum 6 is driven at a rotational speed less than the cylinder 5, but as it has a much larger diameter its peripheral speed is higher. The points on the drum 6 are also inclined in the direction of movement, to remove the fibres from the surface of the cylinder 5 along the closest generating lines between 5 and 6. The moving flats 7 are located above the top of the drum 6. The moving flats are in the form of bars having a useful length corresponding to the generating line of the carding drum 6 and a few centimetres in width. That part thereof which faces the drum 6 is provided with clothing in the form of points pointing in the direction of movement. Generally the moving flats move slowly in a direction of rotation which is the same as or opposite to the that of the drum. The two clothings cooperate with typical carding action to provide fibre extension, cleaning, retention and depth control within the point clothing. It should however be noted that the peripheral drum speed is generally within the range of 15-40 metres per second, whereas the flat speed is of the order of a few millimetres per second. The flats 7 circulate about the drum periphery conveyed by a drive member, for example a pair of chains 8 circulating about a series of drive and guide sprockets 9. Along the carding path between the drum and flats, the flats are guided by guides 10 which are preset with a precision of the order of a tenth and even down to a hundredth of a millimetre, to determine the distances between the drum clothing and the flat clothing, which are essential for the good outcome of the operation. The guides 10 are positioned at the edge of the flat faces of the drum, and on them there slide the end parts, without points, of the flats 7. The extended and cleaned fibres become arranged into a thin layer on the carding drum 6. They are then detached by a discharge cylinder 11, also provided with points inclined in the direction of rotation, to enable the fibres carded by the drum 6 to be withdrawn and then discharged from the cylinder 11 by detachment cylinders not shown in the figure. The present invention relates in particular to an improved sliding flat for said flat cards and a system for guiding and driving it. In the traditional art the flats are generally driven by drive chains 8 to which the flats are fixed by means of bushes, brackets and various supports, either on the chain joints or plates, by screw elements, by snap rings, form fits and so on. European patent application EP-A-693584 in the name of the present applicant describes and claims various form fits between flats and chains without fixed means for retention in the direction perpendicular to the chain movement, with high accuracy in the direction of the guides 10 and with the facility for removal even with the machine in motion. In the traditional art the bodies of the flats are generally constructed of ferrous material by casting, typically of cast iron, to which the point clothing for the carding is then applied. This type of construction satisfies the requirements of reliability, reproducibility, rigidity and iife, but at the cost of an overall very heavy structure which results in considerable construction, installation and maintenance costs of the overall machine. For these reasons the current tendency of the art is to pursue a lighter and more economical construction, for example by using card fiat bodies produced from aluminium or light alloy sections, on which the card clothing is then fixed. These flats, formed from hollow sections of suitable moment of inertia, satisfy the need for good flexural and torsional rigidity, and are lighter and overall less costly even though a more valuable material is used. These light flats allow, inter alia, the general architecture of the machine to be modified, and enable toothed belt drives to be used instead of traditional metal chains. European patent application EP-A-361 219 of Truetzschler GmbH describes a flat card system of this type. European patent application EP-A-567 747, again of Truetzschler GmbH, describes the insertion of stronger cylindrical pins into the external parts of the flats so that these pins would rest on the guides 10 instead of the ends of the light alloy section, which would wear more rapidly. These pins can be constructed of more wear-resistant materials and can be replaced during periodic machine maintenance at low cost. European patent application EP-A-627 507 of Maschinenfabrik Rieter AG represents the closest prior art and describes a flat card system of this type with coupling between the flat and the toothed drive belt by means of the actual pins which slide on the guides 10. The technical arrangements of the cited prior patents have the drawback that the coupling between the card flat and the toothed drive belt is such as to angularly constrain the flat to the belt, so endangering the accuracy with which the flat can follow the guides 10 directionally, given that the belt has a certain intrinsic rigidity. An object of the invention is to provide an improved lightweight flat for said flat cards, and a system for guiding and driving it which uses a toothed belt drive but without the stated drawbacks of this type of drive when used in the aforesaid systems. A further object of the present invention is to provide a coupling system between the flat and belt which enables said elements to be easily released from each other for maintenance and for removal during maintenance. These objects are achieved by the characteristics of claim 1. To further illustrate the characteristics and advantages of the present invention, it is described hereinafter with reference to some typical embodiments thereof shown by way of non-limiting example in Figures 2 to 7. Said figures show various embodiments of the belt/flat system according to the invention, and also show the overall path of the flats to illustrate the modifications made to the scheme of the machine and the benefits deriving from the present invention. Figures 2A, B, C show a flat/toothed belt system according to the invention. Figure 2A is a transverse view of the flat/belt coupling, Figure 2B is a perspective view thereof with the guide 10 and Figure 2C is a schematic view of the overall path of the flats. The flat 7 is preferably of inverted T cross-section to provide sufficient rigidity against flexural stress between the two guides 10, which are spaced apart transversely by a distance D 10 of the order of one metre. The shank 20 of the T is made hollow to achieve a high flexural moment of inertia. The body of the flat is obtained from a light alloy section of indefinite length, which is cut to size to a length less than the distance between the guides 10. Its lower face 21 is not involved with the guides 10 and carries the card clothing 22 indicated roughly as a series of points. The toothed belt 23 has a flat lower face 23a and a face 23b worked in relief. Generally it is constructed of material of good flexibility, such as elastomeric materials possibly reinforced longitudinally with textile fibre threads and/or metal wires. On the worked face 23b there is provided a series of projecting teeth 24 intended to engage the sprockets 9, and spaced apart by a series of lower longer portions 25, in which there is provided an upwardly open cylindrical cavity 26 of circular cross-section 26 for housing the element by which it is coupled to the flats. On the terminal faces at the two ends of the body of the flats 7, and in particular on the part forming the "cross-member of the T", there are fixed in a position closer to the face 21 two support pins 27 of wear-resistant material, for example alloy steel, which are positioned horizontally and intended to slide on the card guides 10 to support the working flats facing the drum 6. Again on the terminal faces of the body of the flats 7, but in a position relatively further from the lower face 21, there is fixed a horizontal pin 28 for insertion into the cylindrical cavity 26. The pin 28 is of cylindrical shape and has a size coherent with said cavity 26, not only to enable the flat to be driven along its working path but also to enable it to undergo adaptive rotary movements via the pin 28 within the cavity 26, to enable the flat to adhere accurately to the profile of the guides 10. To allow freedom of said rotational movements in adapting to the path determined by the guides 10, in a preferred embodiment of the invention the support pins 27 are mounted at a substantial distance from the bottom 23a of the toothed belt. In other words, between the flat 7 and the toothed belt 23 there is provided a cylindrical form fit, without fixed retention means, with the toothed belts positioned at its ends by means of cavities 26 and pins 28 of circular cross-section having their axes transverse to the toothed belt, by which the flat 7 is free to adapt itself angularly by rotating about the coupling axis in the direction of the guide 10 without angular constraints provided by the cylindrical fit. The pins 27 and 28 can be fixed to the body of the flat in known manner, for example by a forced fit or by a screwed connection. The embodiment shown in Figures 3A, B, C shows a modification to the belt/flat coupling of Figures 2. In it, the worked face 23b of the belt 23 is provided with a series of projecting teeth 24' extending further in the longitudinal direction than the depressed portions 25'. Within the teeth 24' there is provided an upwardly open cylindrical cavity 26'intended to house the pin 28'. It can be seen that this embodiment requires a lesser belt thickness than the embodiment of Figure 2. It also has further advantages which are described hereinafter. Figure 3D shows a preferred embodiment of the invention, applicable advantageously to the circular coupling pins of the other described embodiments, in which that part of the pin 28 projecting from the flat 7 is provided with an antifriction rolling bush 29, interposed between the pin 28 and its cavity 26, which reduces friction during mutual rotation. Figures 2C and 3C are a side view of the overall path of the flat/toothed belt system. Along the path guided by the guides 10, for which on the other side of the drum there is another corresponding guide 10 parallel to it, the series of flats 7 is driven by the toothed belts 23 which follow the path defined by the sprockets 9, of which at least one is motorized and at least one is provided with belt tensioning members. As in the case of the guides 10, the sprockets are also provided in pairs, one for each side of the drum 6. With the coupling systems shown in the embodiments of Figures 2 and 3 when the flats separate from the guides 10, the toothed belts retain the flats during their engagement with the sprockets 9 until they have overturned with the clothing 22 on top. After this overturning the flat is supported on the belt 23. Figures 4A,B,C,D show a modified embodiment of the invention. Figure 4A is a transverse view of the flat/belt coupling, Figure 4B is a perspective view thereof with the guide 10, Figure 4C is a side view of the overall path of the flats, and Figure 4D shows a varied configuration of the toothed belt. The toothed belt 33 has its lower face 33a worked to engage the pins 28 and its upper face 33B toothed to engage the sprockets 9 by means of its teeth. In the lower face 33a there is provided a series of downwardly open cylindrical cavities 34 intended to house the coupling element 28 for the flats 7. In the version of Figure 4D, the toothed belt 33 is made more flexible and light by a series of lightening cavities 35, which alternate with the coupling cavities 34. It should be noted that in the aforedescribed embodiments the cavities 26, 26', 34 are formed with an open cylindrical section, resulting in. easier connection between the toothed belt and the flat. It is also possible to form the device of the present invention with the cavities 26, 26', 34 of closed cylindrical section, as shown in particular in Figure 2D, resulting in a connection with a greater guarantee of retention between the flat and the toothed belt, even if the belts are stressed to the extent of undergoing considerable deformation by elongation. With the coupling system shown in the embodiments of Figures 4, when the flats separate from the guides 10 the toothed belts 33 do not retain the flats during their engagement with the sprockets 9, and consequently supplementary guides 36, of L cross-section and extending as a semicircle, are required to compel the series of flats 7 passing about the sprockets 9A, B on the belt 33 not to separate from them until they have overturned with the clothing 22 on top. This difference has however an advantageous side deriving from the fact that along their inoperative upper path from 9B to 9A the flats 7 always simply rest on the pair of belts 33. In this respect it must be noted that in carding, the material is such as to require the cylinders and the flats to be subjected to frequent cleaning and to regeneration of the clothing. In consideration of this and of the large number of flats installed on the machine, of the order of a hundred, it is advantageous to be able to remove and replace a flat by simply lifting it from its site on the pair of belts along its upper path. In devices of the known art, the flats are generally removed and replaced with greater complication. In the embodiment of Figure 4 the flat is withdrawn without having to remove restrictions. If there are no particular safety regulations the flats can even be removed when in movement, given their low peripheral speed and their instant removability. Along the working lower path the belts are guided by the flats, which in their turn rest continuously on the guides 10. Along the inactive upper path the flats rest on the toothed belts, which are considerably stressed by the weight of the flats and may not be able to by themselves support all the flats without dangerous elongation. For this reason, according to a preferred embodiment of the invention, the upper parts joining the sprockets 9A, 9C and 9B to be provided with support guides 40 on which the inverted inoperative flats 7 are supported. A further technical problem relating to the upper path of the guides 40 derives from the fact that the relative position between the belts and flats is in this case inverted. The flats rest on the belts which could slide on the guides 40, with considerable friction and wear. According to a preferred embodiment of the present invention, the coupling pins 28, 28' between the belt and flat are made to project from their cavity 26, 26', 34 in the toothed belt 23, 33 such that they rest - with the flats inverted - on the return guides 40 in place of the projecting teeth 24, 24' of the toothed belt. This improvement is illustrated with greater detail in the embodiments of Figures 5 and 6, by way of non-limiting example. The embodiment of Figures 5A,B,C,D uses the type of coupling shown in Figures 3 in which however the coupling pin 41 between the belt and flat is constructed with a length projecting from the end of the flat 7 which is substantially in excess of the width of its toothed belt 23 and consequently projects from it by a portion 42. As already described, this projecting portion 42 can advantageously have applied to it a further separate antifriction rolling bush 43, which reduces contact friction in its resting on the guide 40. Figure 5A is a perspective view of the flat/belt coupling, Figure 5B is a side view thereof, Figure 5C shows the flat/guide configuration in the inoperative upper path of the flats along the guides 40, and Figure 5D shows the flat/guide configuration in the working path along the guides 10. In it, the upper pair of support guides 40 which have to support the weight of the flats 7 along their inoperative path are located at a transverse distance apart D 40 which is greater than the transverse overall dimension of the pair of belts 23, which corresponds substantially to the distance D 10 between the guides 10 plus the thickness of the guides themselves, so that the profile of the teeth 24 of the pair of belts 23 remains within guides 40 and does not come into contact with them. The guides 40 are positioned a distance apart D 40 corresponding to that of the two portions 42 so that it is not the toothed belt which rests on the guides 40 but instead the portion 42, preferably provided with an antifriction bush 43, which slides on them along the inoperative path of the flats. The flats, which are supported along the path of the guides 10 by the pins 27, are hence supported along the return path of the guides 40 by the pins 42, with reduced friction and wear. In the embodiment shown in Figures 5, the cavities 26 are formed with a closed circular cross-section. In the embodiment of Figures 6A, B, C, D the type of coupling illustrated in Figures 3 is again used, but with the coupling pin 46 between the belt and flat being constructed of "pear" configuration with a small protuberance 47 projecting from the tooth 24' of the toothed belt 23, in which tooth there is provided the cavity 26' into which the pin 46 is inserted. Figure 6A is a perspective view of the flat/belt coupling, Figure 6B is a side view thereof, Figure 6C shows the flat/guide configuration in the inoperative upper path of the flats along the guides 40, and Figure 6D shows the flat/guide configuration in the working path along the guides 10. The upper pair of support guides 40 which have to support the weight of the flats 7 along their inoperative path are located at a transverse distance apart D 40 substantially equal to the distance D 10 between the guides 10. The projection 47 projects from the teeth 24' such that their contour along the pair of belts 23 remains separated from the guides 40 and does not make contact with them, it being the projection 47 itself, preferably formed of material of good antifriction and antiwear characteristics, which slides on them along the inoperative path of the flats. The flats, which are supported by the pins 27 along the path of the guides 10, are supported along the upper return path of the guides 40 by the pins 46, with reduced friction and wear. Figures 7A, B show a modification of the coupling of Figures 6, in which the cavity 26' into which the pin 46 is inserted has a smaller depth than the pin diameter so that, during the inoperative path of the flat, said pin 46 projects from the belts and raises them, analogously to the embodiment of Figure 6, so that the pin itself slides on the upper guides instead of the teeth of the belts, with substantial reduction in friction.

Claims: A sliding flat with its body produced from section bars for carding devices, and a system for guiding and driving it in a card with moving flats driven by toothed drive belts, said flats being provided in their ends with cylindrical pins (27) for resting on the guides (10) and provided on their lower face (21) with card clothing (22), characterised in that coupling between the flat (7) and toothed belt (23, 33) is achieved by a cylindrical form fit, without fixed retention means, with the toothed belts positioned at its ends by means of cavities (26, 26', 34) provided in the toothed belt (23, 33) and one pin (28, 28', 41, 46) of circular cross-section having their axis transverse to the toothed belt at each end of the flat (7), by which the flat (7) is free to adapt itself angularly by rotating about the coupling axis in the direction of the guide (10) without angular constraints provided by the cylindrical fit. A sliding flat as claimed in claim 1, characterised in that the upper face (23b) of the toothed belt is provided with projecting teeth (24) alternating with lower portions (25), in said portions (25) there being provided a cylindrical cavity (26) of circular cross-section, on the terminal faces at the two ends of the body of the flats (7), in a position relatively further from is lower face (21) than the pins (27), there being fixed at each end of the flat (7) one horizontal pin (28) of circular cross-section for insertion into the cylindrical cavity (26) (figures 2A to 2D). A sliding flat as claimed in claim 1, characterised in that the upper face (23b) of the toothed belt is provided with projecting teeth (24') alternating with lower portions (25'), in said teeth (24') there being provided a cylindrical cavity (26') of circular cross-section, on the terminal faces at the two ends of the body of the fiats (7), in a position relatively further from is lower face (21) than the pins (27), there being fixed at each end of flat (7) one horizontal pin (28') of circular cross-section for insertion into the cylindrical cavity (26') (figures 3A to 3D). A sliding flat as claimed in claim 1, characterised in that the lower face (33a) of the toothed belt (33) is intended to engage the pins, whereas the upper toothed face (33b) is intended to engage the sprockets (9), in the lower face (33a) there being provided a series of cylindrical cavities (34) of circular cross-section intended to house one element (28) for coupling to the flats (7), provided at each end of the flat (figures 4A to 4D). A sliding flat as claimed in one or more of the preceding claims, characterised in that on that part of the coupling pin (28, 28') which projects from the fiat (7) there is applied an antifriction rolling bush (29), interposed between the pin (28, 28') and its cavity (26, 26', 34) (figure 3D). A sliding flat as claimed in one or more of the preceding claims, characterised in that , in the projecting part of the flat (7), the coupling pins (28, 28') between the belt and flat are made to project transversely from their cavity (26, 34) in the toothed belt (23, 33) by a portion (42) such that they rest via this portion (42) on the return guides (40) instead of the teeth (24, 24') of the toothed belt (figures 5A to 5D). A sliding flat as claimed in claim 3, characterised in that the coupling pin (46) between the belt and flat is constructed of "pear" configuration with a small protuberance (47) projecting from the tooth (24') of the toothed belt (23) into which the pin (46) is inserted, such that the contour of the teeth (24') of the pair of belts (23) remains separated from the guides (40) and does not make contact with them, instead it being the projection (47) which slides on them along the inoperative path of the flats (figures 6A to 6D). A sliding flat as claimed in claim 3, characterised in that the cavity (26') into which the pin (46) is inserted is formed with a depth less than the diameter of the pin itself, so that along the inoperative path of the flat, said pin (46) projects from the belts and raises them, so that it is the pin itself which slides on the upper guides instead of the belt teeth (figures 7A, 7B).

Inventors: COSSANDI ANTONIO, PASINI GIOVANNI BATTISTA, PATELLI SILVANO, COSSANDI, ANTONIO, PASINI, GIOVANNI BATTISTA, PATELLI, SILVANO
Applicants: MARZOLI SPA, MARZOLI S.P.A.
Application year: 1997
Main classification: D01G15
IPC codes: D01G15