Device for preparation and opening of flock fibres to be supplied to a carder

Abstract: Silo for supply of flock fibres to a carder, which silo is subdivided into superimposed chambers (3,10), between which there is interposed a set of rollers which regulate the descending flow, and carry out breaking and separation of the fibrous material, in which a supply roller (25), an auxiliary supply roller (27) and a breaker roller (26) are disposed in a triangle, in which the surface of the auxiliary roller opposite that which is tangent to the supply roller is exposed to the flow of air which descends downwards, together with the fibres worked by the breaker roller.

Description: The present invention relates to supply to carders, in which fibrous flock material is worked by a series of surfaces which are provided with a multiplicity of tips, by which the fibrous material is opened up into the form of individual fibres, particles of dirt are eliminated, the fibres are mingled with one another, and a strip of non-twisted fibres is formed, to be conveyed to the successive processing stages. A device for such a purpose is known from GB2104560 which represents the most relevant state of the art. In its most general outline, the operation of supply to carders of the cotton-industry type is carried out according to the significant aspects of the diagram illustrated in figure 1. The light-coloured arrows indicate the flow of flock fibres, whereas the dark arrows indicate the flow of the conveying and control air. The untreated material 1 is obtained in general from an opener, not shown in the figure, and consists of flock fibres. The supply device consists of a vertical silo, which is subdivided into two chambers, one above the other, between which there is interposed a set of rollers which regulate the descending flow, and carry out initial breaking and separation of the material. This fibrous material is conveyed by means of pneumatic transport in an air current, and is accumulated in the end part 2 of the descending duct or upper chamber 3 for intake of the fibres. The transport air is discharged from the apertures 4; as the fibrous material is deposited in the end part 2, it covers these holes, and increases the pressure in the duct 1. Monitoring of the differential pressure value, or load loss, in the upper duct, makes it possible to detect the level of filling of the upper chamber in the end part 2. On the basis of the level of filling of the chamber, there is regulation of the conveyance of flock fibres from the preceding set of openers. If the carding unit consists of several carders in parallel, the flow of fibres, conveyed by the opener unit upstream to the carder downstream, is preferably distributed to the carders which have their ducts 3 least filled, and which thus provide a lower load loss relative to the flow of fibres. Downstream from the end part 2, there is disposed the supply cylinder or roller 5, which supplies the flock fibres to the breaker cylinder or roller 6, which carries out the breaking of the material. The two cylinders operate with simultaneous rotation, in order to transfer the material into the duct 7 beneath. According to the known art, the supply roller 5 is actuated at a variable speed of rotation, and is produced lobed, or is provided with a covering with saw teeth. In general, the saw-tooth covering is produced with positive angling, i.e. with the steepest edge facing in the direction of feed, with the effect of thrusting the fibre flock towards the tips of the breaker cylinder 6. The supply roller 5 works facing the wall 2' of the end part 2 of the duct 3 for intake of the fibres 1, in order to create between the roller and the wall a gap 2'' for passage of the fibres. The breaker roller 6 works at a constant linear speed, and is provided with a series of tips or needles 8, which are spaced from one another. The said breaker roller 6 works facing the curved wall 9 which surrounds it, in order to create a second gap 9' for passage of the fibres. The air current in order to maintain the pressure in the lower chamber 10 at the end of the duct 7 is supplied by a blower 11, which provides a flow of air which is tangential relative to the output of the fibres from the breaker cylinder 6, and is then discharged from the holes 12. In the duct 7 there is installed a pressure switch, which controls the speed of rotation of the roller 5, such as to regulate the density of the fibres which are contained in the lower chamber 10, and form the mat supplied to the carder. The base of the second descending duct 7 is equivalent to conventional storage of fibres in a silo, in which the density of the fibres is controlled and regulated by pneumatic effect. The set of discharge cylinders or lobed rollers 13, which rotate at a controlled speed, in order to regulate the flow of fibres, discharges the fibres onto a slide 14, which supplies the fibres in the form of a mat 15 to the carder. The transverse dimension of the mat supplied depends on that of the processing cylinders of the carder; for carders of the cotton-industry type, this transverse dimension is in general between 0.7 and 1.5 m, depending on the models. The supply system according to the known art described hitherto has some problems. Significant amongst these problems is the inefficient opening action by the system on the flock fibrous material supplied, and particularly when operation takes place with a high level of hourly production of the carder. This reduced efficiency of opening of the flock is caused by poor action of penetration of the tips of the breaker roller, which is carried out only on the fibres which are held between the said roller and the wall which surrounds it, which acts as a supply table for the silo. There is also premature wear of the tips of the breaker roller, which must be replaced at brief intervals. A further disadvantage consists of the formation of neps, or tangles of fibres caused by curling of the fibres as a result of sliding of the latter on the wall 2' opposite the roller 5. The present invention relates more particularly to a device for preparation of the supply of flock fibres to a carder, which permits increased production, and at the same time provides more open and homogeneous fibres, which are also worked less aggressively. The substantial characteristics of the device according to the invention are defined in the first claim, and its preferred embodiments are defined in the dependent claims. In order to illustrate more clearly the characteristics and advantages of the present invention, it is described with reference to a typical embodiment shown by way of non-limiting example in figures 1 to 3, which illustrate schematically: in figure 1, the state of the art and the technical problem of supply in general to the carder; in figure 2, a schematic embodiment of the present invention; and in figure 3, a diagram for regulation of the device in figure 2. In the embodiment illustrated in figure 2, there can be seen the unit of the supply roller and of the breaker roller, on a scale which is enlarged in relation to the preceding figure. The supply roller 25 is disposed at, and upstream from the breaker roller 26, and these two units are disposed in the form of a triangle together with an auxiliary supply roller 27 which is provided with a covering, which for example consists of saw teeth. The triangle constituted by the three rollers is contained within guide walls, consisting of a wall which ends at the wedge 30 which separates the supply roller 25 and the auxiliary roller 27, and a wedge 31 which separates the breaker roller 26 and the auxiliary roller 27, whereas at the opposite side, the delimiting walls 32 and 33 have substantially the same configuration and function as in figure 1. Towards the outer part of the said triangle, the surface of the auxiliary roller 27 opposite that which is tangent relative to the roller 25, and is free between the two wedges 30 and 31, is exposed to the flow of air obtained from the blower 11 with the duct 28, and moves downwards together with the fibres worked by the breaker roller 26. The functioning of the supply unit is designed to break up the material, providing smaller and better opened up flock fibres, and supplying to the chamber 10 beneath a column of fibres which is homogeneous throughout the width of the chamber, in order to obtain a mat with a regular yarn count. The two rollers 25 and 27 are rotated simultaneously, such as to press the fibres together in the passage 40, and thrust them from the upper chamber 3 into the triangle formed by the three rollers through the said passage. In general, the supply roller 25 and the auxiliary roller 27 operate at linear speeds which are substantially the same, and are within the range of 1-6 metres per minute. The distance d 40 between the tips of the teeth of the rollers 25 and 27 is between 3 and 10 mm, and is preferably between 4 and 7 mm. According to a preferred embodiment of the present invention, the coverings of the said rollers 25 and 27 have saw teeth with negative angling, as shown in figure 2, i.e. with the steepest edge opposite the direction of advance, with the effect of conveying the fibre flock further towards the tips of the breaker cylinder or roller 26, but also to retain them between the less inclined edges of the toothing, such that the action of breaking of the flock by the needles 8 of the said roller is more efficient. Most of the fibres which enter the triangle of the rollers go directly to the passage 41 between the breaker roller 26 and the auxiliary roller 27, which has a width d 41 . This distance d 41 between the tips of the teeth of the roller 27 and the needles of the roller 26 is in the interval of 0.5 - 3 mm. The breaker roller 26 operates at a constant speed, in general of between 800 and 1600 metres per minute, and removes the fibres from the passage 41 towards the lower chamber 10, rotating simultaneously with the auxiliary roller 27, which has a linear speed which is substantially lower, and from which the fibres are then removed by the roller 26. As a result of the preferred use of a saw-tooth covering with negative angling for the auxiliary roller 27, in the passage 31 also there is a specific further effect of retention of the fibres, in opposition to the action of the needles 8, such as to obtain in this passage 41 a further effect of breaking of the flock. As a consequence of this action of retention, a small but significant quantity of fibres can remain on the covering of the auxiliary roller 26 downstream from the passage 41. The flow of air which travels through the duct 28 makes it possible to release substantially from the covering of the roller 27 residual fibres which are held downstream from the passage 41, and this action is also assisted by the negative angling of the saw-teeth of the covering. According to a preferred embodiment of the present invention, the auxiliary roller 27 is produced and mounted such as to project substantially from the two wedges 30 and 31, such that in the area 42 of the duct 28 in which there is this contact between the flow of air from the blower 11 and the covering of the roller 27, there is restriction of the passage, and thus a contracted jet of air, which is therefore more efficient in removing the fibres. As an alternative, this restriction of the passage can be obtained by placing a deflection element on the opposite wall of the duct 28. On the other hand, the fibres which are at the upper part of the triangle within the rollers are removed into the passage 43 between the supply roller 25 and the breaker roller 26, which rotate discordantly relative to one another. In this passage, the needles 8 remove the fibres from the roller 25, and convey them to the passage 31 towards the lower chamber 7. The distance d 43 between the tips of the teeth of the roller 25 and the needles of the roller 26 is in the interval of 0.5 - 1 mm. Figure 3 shows the diagram for regulation of the set of cylinders 25,26,27. In general, the breaker cylinder or roller 26 is actuated at a constant, predetermined speed. On the other hand, the two covered supply rollers 25 and 27 are actuated at a speed which is variable according to the level of filling of the lower chamber 10 of the silo as a whole, measured as loss of load in the chambers. For each processing operation which is carried out, there is regulation of the reciprocal distances between the tips of the respective coverings d 40 , d 41 and d 43 of the set of three rollers. The position of the axis of rotation of the breaker rollers is not modified in general, whereas the position of the two horizontal axes of the two supply rollers 25 and 27 can be modified, in order to regulate the distances between the rollers. In particular, the supply roller 25 is regulated by modification of its distance in the meeting point between the centres of the rollers 25 and 27, according to the double arrow 50, thus regulating the distance d 40 . On the other hand, the auxiliary supply roller 27 is regulated by modification of its distance in the meeting point between the centres of the rollers 26 and 27, according to the double arrow 51, thus regulating the distance d 41 . By way of example, the positions of the axes of rotation of the supply rollers 25 and 27 can be modified by mounting the horizontal shafts of the rollers on supports which are provided with through slots, which are elongate in the direction of the arrows 50 and 51, and by locking the shafts in their slot in the required position by known means, for example by threading the ends of the said shafts and locking them with washers, nuts and counternuts. In general, for processing with higher productivity, and with fibres which are less tangled and cleaner, operation takes place with larger distances d 40 , d 41 and d 43 , and consequently with greater flows of fibres, and in general, with lesser differences between the linear speeds of the supply rollers 25,27 and that of the breaker roller 26. In this operation there is already release of a significant quantity of dust from the flock fibres, which are discharged together with the flows of air through the slots 12, and do not reach the carder which follows. This characteristic provides the present invention with a significant advantage. Furthermore, the device according to the present invention makes it possible to eliminate the disadvantages previously described. As far as the action of opening up the flock fibrous material supplied is concerned, even when operation takes place with a high level of hourly production of carding, the action of penetration of the tips of the breaker roller, which is exerted between the breaker roller 26 and the two covered supply rollers, is far more efficient than that which can be exerted relative to a surrounding fixed, smooth wall, which brakes the motion of the fibres and does not accompany them. There is also reduced wear of the tips 8 of the breaker roller, which can be replaced at longer intervals. As already stated, the fibres are treated less aggressively, and thus there are fewer broken fibres, although the fibres are well separated and cleaner.

Claims: Device for supply of flock fibres to a carder, consisting of a vertical silo which is subdivided into two chambers (3,10), one above the other, between which there is interposed a set of rollers comprising a supply roller (25) and a breaker roller (26) which regulate the descending flow, and carry out breaking and separation of the fibrous material, characterised in that the two rollers (25,26) are disposed in a triangle together with an auxiliary supply roller (27) which is provided with a covering, and that the triangle which is constituted by the three rollers is contained within guide walls, which leave free the surface of the auxiliary roller (27) opposite that which is tangent to the supply roller (25) and said free surface being exposed to the flow of air of the duct (28) which descends downwards, together with the fibres worked by the breaker roller (26). Device for supply of flock fibres to a carder according to claim 1, characterised in that the coverings of the rollers (25) and (27) have saw teeth with negative angling, with the steeper edge opposite the direction of advance. Device for supply of flock fibres to a carder according to claim 1, characterised in that the distance (d 40 ) between the tips of the teeth of the rollers (25) and (27) is in the interval of 3 - 10 mm. Device for supply of flock fibres to a carder according to claim 1, characterised in that the distance (d 41 ) between the tips of the teeth of the rollers (27) and the needles of the roller (26) is in the interval of 0.5 - 3 mm. Device for supply of flock fibres to a carder according to claim 1, characterised in that the auxiliary roller (27) is produced and mounted such that in the area (42) of the duct (28) in which there is contact between the flow of air from the blower (11) and the covering of the roller (27), there is restriction of the passage, and a contracted jet of air. Device for supply of flock fibres to a carder according to claim 1, characterised in that the position of the horizontal axes of the supply rollers (25) and (27) can be modified, in order to regulate the distances (d 40 ,d 41 ).

Inventors: MASCHERETTI MARIO, PASINI GIOVANNI BATTISTA, MASCHERETTI, MARIO, PASINI, GIOVANNI BATTISTA
Applicants: MARZOLI SPA, MARZOLI S.P.A.
Application year: 1999
Main classification: D01G23
IPC codes: D01G9, D01G23