METHOD AND APPARATUS FOR PROCESSING COTTON FIBERS IN PRESSED BALES FOR REMOVING THEREFROM ADHERING ORGANIC WASTE RELEASED BY INSECTS

Abstract: The present invention relates to a method and apparatus for processing textile fibers,in parti­ cular pressed bale cotton fibres,for removing there­ from possible adhering organic waste released by insects,which method comprises the step of process­ ing in a microwave oven,by a substantially continuous cycle,the cotton bales by means of microwaves having given frequency and power,so as to dry the organic waste in such a way that the organic waste can be easi­ ly removed from the single fibers by a simple beating treatment. The apparatus substantially comprises a micro­ wave processing tunnel thereto the cotton bales are supplied,in succession,by means of a loading conveyor belt,a plurality of microwave generating units arranged in said tunnel and a discharging conveyor belt for unloading the microwave processed cotton bales.

Description: BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for processing cotton fibers arranged in pressed bales, for removing therefrom possible insect organic waste adhering to the fibers. As is known, cotton fibers coming from some cotton production regions, such as Sudan, are frequently contaminated by organic waste and/or excrements of insects, mainly the so-called "white fly". This organic waste substantially consists of a yellowish substance of glue consistency which is usually called "honey dew". Because of this organic waste, which strongly adheres to the singe cotton fibers, the fibers can be hardly processed for making them suitable for possible spinning operations, with a consequent poor yield and a poor quality of the spun fibers. None process is presently available for easily and fully removing the mentioned organic waste from cotton fibers in bale form. For example, EP-A-0186449, which is considered to represent the most relevant prior art, discloses a process and device for rendering sticky material adhering to cotton fibres hard and brittle by heating (convection, conduction, radiation...) by heating the cotton fibres (not in bale form) for a brief period to an adequate temperature. EP-A-0186449 further discloses that only the upper layer of cotton bales can be processed to render the sticky material adhering to the cotton fibres hard and brittle. SUMMARY OF THE INVENTION Accordingly, the task of the present invention is to overcome the above mentioned drawbacks, by providing a method for processing cotton fibre pressed bales adapted for efficiently removing from said fibers, in a quick and easy way, possible adhering organic waste. Within the scope of this taks, a main object of the present invention is to provide such a method which is adapted to process great amounts of cotton fibers, with a great hourly yield. Another object of the present invention is to provide such a method which is adapted to efficiently remove the mentioned organic waste without negatively affecting the textile properties of the cotton fibers. Yet another object of the present invention is to provide such a method which is effective to process cotton fibers arranged in pressed bales having conventional shapes and size. Yet another object of the present invention is to provide and apparatus for carrying out the above mentioned method which apparatus is very simple construction-wise and can be made starting from easily available materials and components. According to one aspect of the present invention, the above mentioned task and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a method for processing cotton fibre pressed bales according to the main claim. According to a further aspect of the present invention, the pressed cotton bales are subjected, in said tunnel, to a combined action of microwaves and air for cooling the outer surfaces of said bales. The apparatus for carrying out the above mentioned methods comprises a loading platform, consisting of an endless conveyor belt, thereon the single cotton bales are arranged one after the other. This loading platform is adapted to convey the pressed cotton bales to a processing runnel therein there are arranged, with a given predetermined arrangement, a plurality of microwave generating units, adapted to microwave process the individual cotton bales supplied to the tunnel, the microwave processed bales being discharged from the processing tunnel by means of a further output conveyor. BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the apparatus and method for processing textile fibers, in particular cotton fibers collected in pressed bales, for removing therefrom adhering organic waste, will become more apparent hereinafter from the following detailed disclosure of a preferred embodiment thereof, which is illustrated, by way of an indicative example, in the figures of the accompanying drawings, in which: figure 1 is a partially sectioned front view of an apparatus for carrying out the method according to the present invention; figure 2 is a top view of the apparatus shown in figure 1; figure 3 shows a cotton bale which can be processed by means of the method and apparatus according to the present invention; figure 4 shows cotton yarns spun from not processed cotton fibers, according to the prior art; and figure 5 shows some cotton yarns spun from cotton fibers processed by the method and apparatus according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS As mentioned, cotton fibers coming from some cotton producing regions are contaminated by glue type of waste, of an insect called "white fly". This waste negatively affects the spinning operations of said fibers and the obtained spun yarns have a poor quality, since this waste firmly adhers to the fibers. The present invention affords the possibility of overcoming or at least reducing the mentioned drawback by subjecting the cotton fibers, preferably arranged in pressed bales, to a microwave processing. In fact the microwaves, which generate heat inside the overall body of the pressed cotton bale, are effective to completely dry the insect excrements so as to cause said excrements to assume a hard crystalline consistency which will facilitate the detaching thereof, such as by simple beating operations. Thus, the cotton fibers can be spun easily and will provide a cotton yarn having very good properties. Moreover it has been found that the microwave processing does not alter the textile characteristics of the cotton fibers, since it exclusively affects the contaminating substances or organic waste. For carrying out the method according to the present invention, several types of microwave generators have been tested and it has been found that very good results were obtained by using microwave generators or sources adapted to provide microwave beams having a frequency of substantially 2,450 MHz, with microwave powers from 0.3 to 20 KW. With reference to figure 1, there is shown a possible embodiment of an apparatus for carrying out the method according to the invention, which has been briefly disclosed thereinabove, said apparatus being indicated overally at the reference number 1. As is shown, this apparatus essentially comprises three main components and, more specifically, a loading conveyor belt assembly 2, a processing tunnel 3 and a discharging conveyor belt assembly 4. The single cotton bales, indicated overally at the reference number 7 are supplied in succession, one after the other, or in parallel rows, through the loading gate 8 in the direction of the arrow to the inlet of the tunnel 3 and enter said tunnel, in the inside of which there are arranged a plurality of microwave generating units or sources, indicated at the reference number 9. These generating units are arranged in such a way as to cover a broad radiating region, so as to cover all of the zone therethrough the pressed cotton bales will pass. As discussed, inside said tunnel 3 air generating units can also be arranged, which have not been specifically shown, in order to accelerate the drying process of the excrements adhering to the cotton fibers of said bales. In an effectively constructed system, the loading assembly was designed for supporting 30 bales and it operated as a dampening element at the output of the microwave generating units. This loading assembly, in particular, included a bearing or supporting frame with related fittings or stainless steel for a dampening chamber and its size was of 15,000 × 2,000 × 1,100 mm. The microwave heating tunnel 3 consisted of an inner strip conveyor belt which, in the drawings has been indicated at the reference number 10, with polytetrafluoroethylene (PTFE) supporting elements, not specifically shown, of the reinforced and low loss coefficient type for precenting them from being excessively heated. The bearing framework of the heting tunnel or oven was made of AISI 304 stainless steel and defined a multimode microwave heating chamber; the oven further included a forced air cooling assembly. The microwave generating assembly, which represent the core of the method and apparatus according to the present invention, was formed, in the disclosed embodiment, ten microwave generating units or sources adapted to generate microwaves having a frequency of 2,450 MHz, of the 1540/03 MW type, providing a variable microwave power from 300 to 1,100 W, and ten generators of the 1540/01 type with a microwave power of 1,200 W (a fixed power) with a supply voltage of 220 V and a frequency of 50 Hz. The single microwave generators were designed either for manual control or for computer control(not specifically shown). The apparatus also included a discharging conveyor belt, of the strip type, having substantially the same characteristics as the loading conveyor belt. With the disclosed apparatus or system 7,000 Kg per day of cotton fibers have been processed, with a speed of substantially 300 Kg/hour. The apparatus size was of 42,500 × 2,400 × 2,700 mm; in particular the apparatus had a length of 42,500 mm, a useful width of 2,400 mm and a useful height at the inlet of the processing tunnel of 800 mm; the processing tunnel was lined by a thermally insulating mat and means were provided for automatically adjusting the microwave power. The processed cotton bales were pressed cotton bales, produced in Sudan, and two types of these bales, different for volume, weight and density were processed. More specifically, the first processed bale type had a volume of 0.553 m³, a weight of 185 kg and a density of 334.5 kg/m³; the second type had a volume of 0.705 m³, a weight of 220 Kg and a density of 312 kg/m³. In both the processing examples the moisture of the pressed cotton bales had a value of about 6%. The above discussed cotton bales types are fully standard types and have been shown in order to demonstrate that the method according to the present invention can be directly applied to conventional cotton bales without any preprocessing of said bales. The cotton bales processed by the method and apparatus according to the present invention were fed to a conventional beating working step.It has been found that the excrements were well dried and immediately detached from the cotton fibers, which could be easily spun, providing cotton yarns having very good properties, as is shown in figure 5, contrarily from the yarns produced by the same cotton fibers but not processed by the inventive method, as shown in figure 4. From the above discussion it should be apparent that the invention fully achieves the intended task and objects. While the invention has been disclosed and illustrated with reference to a preferred embodiment thereof, it should be apparent that the disclosed embodiment is susceptible to several modifications and variations within its scope.

Claims: 1. A method for processing pressed cotton bales (7), for removing from the cotton fibers insect organic excrements or waste, characterized in that said method comprises the steps of: supplying, in a substantially continuous way, a plurality of pressed cotton bales (7) to a processing tunnel (3), radiating the pressed cotton bales (7) in said tunnel (3) by microwaves (9) having predetermined frequency and power, said microwaves (9) being adapted to fully dry said excrements, subjecting said microwave processed cotton bales (7) to a beating action for removing the dried excrements from said microwave processed cotton bales (7), and discharging from said tunnel (3) the thus processed cotton bales (7). 2. A method according to Claim 1, characterized in that said method comprises a further step of subjecting the pressed cotton bales (7) to acooling step. 3. A method according to Claim 1, characterized in that the frequency of said microwaves (9) is of substantially 2,450 MHz and essentially included in the frequency range of 500 to 4,500 MHz. 4. An apparatus for carrying out the method according to one or more of the preceding claims, characterized in that said apparatus comprises, in cascade: a loading conveyor belt assembly (2) adapted to supply a plurality of pressed cotton bales (7) to a processing tunnel (3), a plurality of microwave generating units (9) arranged along the length of said tunnel (3), removing means for removing insect dried excrements from the cotton bales (7) processed by said microwave generating units (9), and a discharging conveyor belt assembly (4) for removing from said tunnel (3) the processed cotton bales (7). 5. An apparatus according to Claim 8, characterized in that saud apparatus comprises, in said tunnel (3), at least one air generating unit.

Inventors: POLLI, EDOARDO
Applicants: POLLI, EDOARDO
Application year: 1988
Main classification: D01G37
IPC codes: H05B6, D01G99