EP0485013A1

EP0485013A1 - Process and device for improving the degree of homogenisation of staple material, especially cotton staples, in a mixer or the like

Info

Publication number: EP0485013A1
Application number: EP91202810A
Authority: EP
Inventors: Luigi Pezzoli; Emilio Vezzoli
Original assignee: Fratelli Marzoli and C SpA
Current assignee: Fratelli Marzoli and C SpA
Priority date: 1990-11-05
Filing date: 1991-10-30
Publication date: 1992-05-13
Also published as: IT1244148B; IT9021970A0; IT9021970A1

Abstract

The staple material supplied to a mixer (1) in a current of air is subjected to a cleaning operation with the aid of offset before it reaches the mixer (1). The external surface of the supply duct (4) has a grate (14) at the deflection zone (12), the staple material hitting said grate so that the staples are opened and impurities are released, these impurities then being separated by centrifugal action, wherein the radially outermost fraction of the current of air, in which the impurities are located, is deflected towards the exterior of the supply duct (4) by a separating element (18).

Description

This invention relates to a process and a device for improving the degree of homogenisation of staple material, especially cotton staples, in a mixer or the like.
It is well known that staple fibres drawn sequentially from a plurality of adjacent bales by means of a movable sampler, removing a certain thickness of material from each bale in succession on each traverse, are supplied in a current of air to a mixer adapted to mix together the more or less different qualities of staples gradually removed and to provide a more homogeneous material at the outlet for the subsequent operations.
The quality and the degree of homogenisation of the material emerging from the mixer determine the quality of the yarn that is then produced by the subsequent machines.
In order to improve the homogeneity of the material, it is common practice to increase the number of adjacent vertical bins into which the mixer is subdivided or to dispose a preliminary mixer upstream of the real mixer, or even to vary and increase the path of the material within the mixer, by producing bins of differing lengths. However, all of these systems involve a not insignificant increase in the overall dimensions of the mixer.
The object of this invention is to provide a process and an associated device by means of which it is possible to improve the quality and the homogeneity of the material being mixed and, consequently, the quality of the yarn produced as a result of the subsequent operations, without having any substantial effect on the overall dimensions of the mixer.
In order to solve this problem, it is proposed according to the invention to subject the staple material to a cleaning operation upstream of the mixer, intended to remove the impurities present in the material supplied thereto, so that it is possible to eliminate the non-homogeneity of the mixed material attribuable to the normal non-homogeneous distribution of impurities and/or dirt particles in the mixed material, with the end result that the material obtained is not only more homogeneous, but is also cleaner and therefore has improved quality for the subsequent operations.
Cleaning operations of this kind can be carried out at no great expense or effort with the aid of a cleaning device associated with the supply duct of the mixer, the material removed by the sampler being passed through this cleaning device before entering the real mixer. The provision of a cleaning device of this kind involves virtually no noticeable increase in the overall dimensions of the mixer.
However, it is advisable for a cleaning device of this kind to satisfy specific requirements determined by the nature of the material being treated, so that there is no damage to the staples, whilst still achieving efficient cleaning.
In this connection, this invention proposes a cleaning device for staple fibres operating by means of offset, directing the current of air containing the staples in correspondence with a deflection zone of the supply duct, in which the impurities are released from the staples and therefore air separation is effected by centrifugal action, so that the impurities leave the duct tangentially through at least one peripheral opening at the outlet zone of the deflection zone, where an element for separating the current of air is disposed, adapted to deflect the radially outermost fraction of the current of air, in which the impurities released from the staple fibres are carried, to the exterior of the duct, while the staple fibres are advanced to the mixer in the associated supply duct. The supply duct may advantageously have a deflection zone preferably formed by an arc of between 100^o and 260^o, and a reel rotating at high speed, e.g. 800-1500 rpm, acting as an auxiliary transportation element for the material, can be disposed in said zone. A grate, which is preferably adjustable, can be provided on the outer surface of the deflection zone, the staple material hitting said grate, so that the staples are opened and the impurities are released, these impurities then being separated by centrifugal action, thereby effecting efficient removal of the said impurities.
In addition to the advantages already mentioned, the process and device according to the invention also offer the advantage that fewer impurities or dirt particles enter the mixer and therefore overall the mixer operates under more favourable conditions.
Further details and advantages of the invention will be more readily understood from the following description with reference to one preferred but not exclusive embodiment of the said invention, illustrated in the accompanying drawing, which shows a vertical section through a conventional mixer provided with a device according to the invention.
The mixer 1 has a plurality of adjacent vertical mixing bins 2, separated by associated dividing walls 3 and communicating with one another at the top and at the bottom. A supply duct 4 for the staple material leads to the inlet of the mixer, this staple material, removed by a sampler (not shown), being advanced in the direction of the arrow M in a current of air, generated by a fan 5, at the top of the mixer 1, where a transporting roller 6 and a belt conveyor 7 distribute the material to the various bins 2 in the manner known per se.
Pairs of feed rollers 8 are disposed at the bottom of each of the bins 2 and below each of these are disposed cutting cylinders 9, by means of which the material from the various bins 2 reaches, mixed, a table 10, from where it is sucked into the next machine, this all being known per se.
According to the invention, a cleaning device 11 is associated with the supply duct 4 for the staple material, the material traversing this cleaning device before it enters the mixer 1. This cleaning device 11 is advantageously constituted by a deflection zone 12 of the supply duct 4, preferably formed by the arc of a circle of 100^o-260^o and separating the impurities from the material by means of offset and centrifugal action. At this deflection zone 12, the duct 4 is suitably designed to house a reel 13 rotating at high speed, e.g. 800-1500 rpm, adapted to promote the advance of the material by mechanical means in the said deflection zone 12. The outer surface of the deflection zone 12 is at least partially formed by a curved grate 14, which may be adjustable in the peripheral and/or transverse direction of the zone 12 and which can also be of varying density, in that the transverse elements defining the grate can be disposed more or less closely together along the deflection zone 12. They are preferably disposed so that the density increases in the direction of movement of the material.
As can be seen in the drawing, a spiked plate 15 is disposed upstream of the grate 14, with nails or needles turned in the feed direction M of the material, so as to effect preliminary opening of the staples which subsequently hit the grate 14 as a result of the deviation of their course effected by the deflection zone 12.
At least one peripheral opening 16 is provided at the outlet zone of the deviation zone 12, defined at one side by a guide plate 17 for the material downstream of the grate 14, and at the other side by at least one separating element 18. This element 18 has a deflection surface 19 directed towards the exterior of the duct 4, in the direction of movement of the material. The separating element 18 can advantageously be adjustable in order to vary the angulation of the surface 19, as clearly indicated by the arrow R in the drawing. The element 18 is adapted to separate the current of air at the outlet of the deflection zone 12, as will be clearer shortly.
The deflection zone 12 is preferably enclosed within a casing 20, having a collecting hopper 21 at the bottom, in the base of which is disposed a removing screw 22. The staple material, advanced in the current of air generated by the fan 5, reaches the deflection zone 12, where, as a result of the offset of the duct 4, it hits the grate 14, advantageously resulting in opening of the staples, with consequent release of the impurities (dust, sand, metal chips, etc.) present in the material. The opening of the staples is promoted by the preliminary opening effected by the spiked plate 15.
The impurities which are released from the staples and which are generally heavier than the staples or which are less influenced by the action of the current of air, tend to be carried in the radially outermost fraction of the said current, as a result of the centrifugal force. At the outlet of the deflection zone 12, the current of air is separated substantially into two parts by the separating element 18, the radially outermost fraction carrying the impurities being deflected towards the exterior by the surface 19, while the radially innermost fraction, carrying the opened and cleaned staples, is advanced into the portion of the duct 4 directly connected to the inlet of the mixer 1 and penetrates therein. In this manner, efficient separation and removal of the impurities is achieved, known as air separation, supplying the mixer with a clean or in any case substantially clean staple material, so that a more homogeneous material is obtained at the outlet of the mixer 1, in that it is free of non-homogeneously distributed impurities, unlike material generally mixed in the conventional manner. The material mixed by the process and the device according to the invention is also of improved quality by virtue of the substantial lack of impurities, so that it is then possible to obtain yarns of improved quality.
By varying the position of the separating element 18 and/or the grate 14, it is possible to adapt the cleaning device 11 so as to obtain optimum cleaning conditions.
The impurities removed from the material are collected in the bottom of the hopper 21, from where they are evacuated with the aid of the screw 22.
By virtue of the transporting reel 13, it is advantageously possible to make uniform the movement of the material. The angle of deflection of the zone 12 can of course range from 100^o-260^o. More openings 16 and/or more separating elements 18 can also be provided. Instead of the grate 14, it is possible to provide for the arrangement of spiked surfaces or the like.
The device described necessitates virtually no modification of the structure of the conventional mixer and is of relatively limited overall dimensions, so that there is no significant increase in the space occupied by the mixer, whilst still obtaining a substantial increase in the degree of homogenisation of the mixed material.

Claims

Process for improving the degree of homogenisation of staple material, especially cotton staples, in a mixer or the like, in which the material is advanced to the mixer or the like in a current of air, characterised in that before entering the mixer or the like, the material is subjected to a cleaning operation in order to remove the impurities present in the material.
Process according to claim 1, characterised in that cleaning of the material is effected by means of offset, the impurities being separated by centrifugal action.
Process according to claim 2, characterised in that the material is deflected by a zone forming an arc of substantially 100^o-260^o.
Process according to claim 2 or claim 3, characterised in that the material is advanced substantially by mechanical means in correspondence with the deflection zone.
Process according to one of claims 2 to 4, characterised in that the material is subjected to preliminary opening of the staples at the beginning of the deflection zone.
Device for carrying out the process according to one or more of the preceding claims, comprising a mixer or the like for the material and a duct for supplying the material in a current of air upstream of the mixer of the like, characterised in that a cleaning device is associated with this duct, through which the material passes before entering the mixer or the like.
Device according to claim 6, characterised in that the said cleaning device is constituted by a deflection zone of the said supply zone, being provided at the outlet zone of the said deviation zone with at least one peripheral opening and at least one separating element for the current of air, having a deflection surface in order to deflect the radially outermost fraction of said current to the exterior of said duct.
Device according to claim 7, characterised in that the said deflection zone is formed substantially by an arc of 100^o-260^o.
Device according to claims 6 and 7 or claims 6 and 8, characterised in that the said cleaning device moreover comprises a rotating reel for advancing the material into the said deflection zone.
Device according to one of claims 7 to 9, characterised in that the outer surface of the said deflection zone is formed at least in part by a grate.
Device according to claim 10, characterised in that the grate is adjustable in the peripheral and/or transverse direction of the said deflection zone.
Device according to claim 10 or claim 11, characterised in that the grate is formed by transverse elements disposed with varying density, preferably so that the density increases in the direction of movement of the material.
Device according to one of claims 10 to 12, characterised in that at least one spiked plate for preliminary opening of the staples is disposed at the beginning of said deflection zone, upstream of said grate.
Device according to claim 7, characterised in that the said separating element is designed to be adjustable.
Device according to one of claims 7 to 13, characterised in that a hopper for collecting the impurities removed from the material is disposed below said deflection zone.