DRYER FOR DRYING EXTRUDABLE MATERIALS

Abstract: In a dryer for drying extrudable materials, a worm is rotatably disposed in a tubular sleeve which is equipped at its front portion with a hopper to supply extrudable materials. The worm is supported at its both ends by bearings in the sleeve or outside the sleeve. A seal screw is formed around the rear portion of the worm, and an outlet for discharging the extrudable materials is formed on the side surface of the sleeve near the end of the seal screw. The end of the seal screw is connected with a flushing ring which is protruded from the end of the worm,

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dryer for drying extrudable materials, which prevents metal pieces from entering into an extrudable material such as rubber, and which dries it efficiently until a desired water content is reached without permitting the quality of rubber to deteriorate. 2. Related Art Statement In a conventional screw-type rubber dryer disclosed, for example, in Japanese Patent Publication No. 6105/1976, Japanese Patent Publication No. 37055/1981, Japanese Patent Publication No. 4462/1966, an extruding mechanism consisting of a worm without bearing is provided near the outlet for discharging the rubber. When the rubber is nonuniformly charged, therefore, the worm shaft swings or is deflected to a considerable degree, and the worm and the cylindrical sleeve often come into violent contact with each other. Therefore, it is inevitable that the contacted portions are worn out and metal places are peeled off to enter into the rubber, causing the quality of the rubber to be greatly deteriorated. The known dryers as those ones referred to EP-A-140 986 and DE-B-1 252 175 don't provide any peculiar feature which allows the reduction of the water content of a rubber from 5-20% to 0.3% or smaller as the invention's dryer, particularly they don't disclose the water circulating mechanism for cooling a portion around the seal screw. Prior to this invention, there has been no effective solution for prevention of contact between the worm and the cylindrical sleeve. SUMMARY OF THE INVENTION The object of the present invention is to provide a dryer for drying extrudable materials, employing the structure in which the worm shaft is supported at its both ends by bearings so that the worm shaft will not come into contact with the tubular sleeve. The above object of the present invention is accomplished by a dryer for drying extrudable materials characterized in that a worm is rotatably disposed in a tubular sleeve which is equipped at its front portion with a hopper to supply extrudable materials such as rubber and the like, said worm being supported at its both ends by bearings in the sleeve or outside the sleeve, a seal screw is formed around the rear portion of said worm, and a discharge outlet for discharging the extrudable materials is formed in the side surface of said sleeve near the front end of said screw. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side vertical section view of a rubber dryer according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION The invention will now be described below in detail by way of an embodiment which treats the rubber in conjunction with the drawing. In Fig. 1, reference numeral 1 denotes a decelerating mechanism coupled to a drive mechanism that is not diagramed, 2 denotes a tubular sleeve provided at its front portion with a rubber hopper 3. A worm 4 is rotatably disposed in the sleeve 2. That is, a front end 4a and a rear end 4b of the worm 4 are supported by bearings 5a and 5b such as roller bearings inside or outside the sleeve. Preferably, the outer surface of the cylindrical sleeve 2 is surrounded by a heating jacket 2a, and the interior thereof is filled with steam etc. Reference numeral 2b denotes breaker bolts. Further, a seal screw 4c is formed around the rear portion of the worm 4. To perfectly maintain the sealing performance, furthermore, provision is made of a cooling water circulating mechanism 4d to effect the local cooling. A pressure-boosting extrusion worm 4e having a large lead is formed on the worm 4 in front of the seal screw 4c, in order to boost the pressure and to increase the efficiency for extruding the rubber. The tubular sleeve 2 is provided with an outlet 6 for discharging the rubber at the back of the worm 4 near the front end of the seal screw 4c. A flushing ring 7 is protruded from the rear end of the worm 4 so that the rubber will not stay in a space. Further, a cylinder cutter with dies is juxtaposed to the rubber discharge outlet 6. In its place, however, it is also allowable to arrange a fixed plate with dies in combination with a rotary cutter. In the thus constructed dryer, the rubber which is dehydrated in advance to a water content of 5 to 20% by a hydroextractor that is not shown, is sent into the dryer through the hopper 3 and is subjected to the compression, kneading and heating repetitively by the worm 4 as it moves toward the discharge outlet 6. The rubber which is compressed and heated to 40 to 90 kgf/cm²G and 180°C or higher, is allowd to blow through dies of the cylinder cutter mounted on the discharge outlet and instantaneously undergoes the distension, whereby the water vaporizes and the water content of rubber becomes 0.3%, preferably 0.15% or smaller. The rubber flew from the dies is cut into pieces by the cylinder cutter that rotates in the cylinder, and is discharged from a cylinder nozzle. In the above-mentioned embodiment, the cylinder cutter with dies was provided at the end of the discharge outlet 6. In its place,however, it is also allowable to arrange a fixed plate with dies in combination with the rotary cutter. According to the present invention in which both ends of the worm are supported by the bearings 5a and 5b, the worm 4 does not swing or is not deflected unlike that of the conventional art. Therefore, the worm is not brought into violent contact with the tubular sleeve 2, and metal pieces do not enter into the rubber, thereby making it possible to maintain the quality of rubber very high. Moreover, the number of revolutions of the worm 4 can be freely increased to increase the amount of processing the rubber. As required, furthermore, it is allowed to greatly reduce the length of the worm 4 to increase its rigidity, from which strikingly improved effects can be expected. Owing to the combination of pressure-boosting extrusion worm 4e, seal screw 4c and flushing ring 7, furthermore, the rubber stays no more in the dryer. Namely, the rubber is not thermally deteriorated or is not deteriorated that may result when the rubber is compressed and kneaded in narrow gaps. The rubber can be efficiently discharged by the cylinder cutter with dies mounted on the discharge outlet, or by the fixed plate with dies in combination with the rotary cutter. Though the above embodiment has dealt with the case where the rubber was dried, it should be noted that the present invention is in no way limited thereto only but can also be adapted to the fields of synthetic resins or foods in the form of extrudable materials.

Claims: A dryer for drying extrudable materials having a water content of 5-20% to obtain materials having a water content of 0.3% or smaller by blowing through dies the extrudable materials compressed to 40 to 90 kgf/cm² G and heated to at least 180°C comprising a worm (4) rotably disposed in a tubular sleeve (2) which is equipped at its front portion with a hopper (3) to supply the extrudable materials to be dried, with a seal screw (4c) formed around the rear portion of said worm (4) and with an outlet (6) for discharging the extrudable materials provided on the side surface of said sleeve (2) near the front end of the seal screw (4c) characterised by the fact that said worm (4) is supported at both of its ends by bearings (5a, 5b) connected to the sleeve (2); a cooling water circulating mechanism (4d) is provided for cooling said seal screw (4c) and said end is connected with a flushing ring (7) which protrudes from the end of said worm (4). A dryer according to claim 1. characterised by the fact that said flushing ring (7) is provided on the outer surface of the worm (4) near the outlet for discharging the material. A dryer according to claims 1. and 2. characterised by the fact that the extrudable material to be dried is rubber.

Inventors: SHOGENJI, TOSHIHIRO, TAKAHASHI, KENICHI
Applicants: JAPAN BUTYL COMPANY LIMITED
Application year: 1987
Main classification: B30B9
IPC codes: B29C47, B30B9, B29B7, B29B13, B29K21