Reclaiming Machine for Scraps of Expanded Foam Thermoplastic Material

1. Field of the Invention

This invention relates to a reclaiming machine for scraps of expanded foam thermoplastic material.

2. Description of the Prior Art

Cutting scraps are generated in the process of manufacturing of insulating material or cases, etc., or are generated by punching completed items, especially foam products of thermoplastic synthetic resin material such as polysytrene, polyethylene, etc., having a high expansion rate of 15 to 70 times and having a variety of apparent specific weights, or volumes in accordance with differences of specific weight of the material yielded or the difference in the types of the products.

In order to reclaim scraps having characteristics as above stated, the inventor of this invention has previously proposed, by Japanese utility model application No. 47-148518 (Jitsu-Ko-Sho No. 56-2585), a machine with two cylinders in which scraps of expanded foam are to be reciprocated. This invention was very effective for reclaiming, however, the amount of generated expanded foam scrap often varies, and when the material is excessive, it is required to utilize a large capacity storage tank at a midpoint thereof. Also, if the machine is prepared to match a large amount of material, it will result in the continual operation of a large machine, and excessive energy will therefore be utilized. Furthermore, the heat radiation from the melting portion is undesirably large.

In consideration of the above deficiencies, the object of the present invention is to provide a reclaiming machine for scraps of expanded foam thermoplastic material by adopting three rows of cylinders, and is devised to respond to the variation of the amount of scraps generated by driving two rows of extruders separately and which is also to prevent heat radiation from the melting portion.

Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views and wherein:

FIG. 1 is a partly cut-away plan view of the first exemplary embodiment;

FIG. 2 is a front sectional view taken along the line II--II;

FIG. 3 is a sectional side view taken along the line III--III; and

FIG. 4 is a longitudinal sectional side view of the second exemplary embodiment.

Now, the structure of the invention is explained by way of an exemplary embodiment shown in FIGS. 1-4 illustrating a hollow test insulating housing or case 2 with a rectangular section and that is set on the base 1. A first cylinder 5 and second cylinder 6 are parallely positioned a predetermined space from each other, such that they pass through the upper parts of opposite side walls 3, 4 of the heat insulating case 2. Also, a third cylinder 7 is installed between the first and second cylinders 5, 6 and at a slightly lower level, so that such projects through both side walls 3, 4.

The first and the second cylinders 5, 6 have their material feeding ports 8, 8' respectively opened to the upper portion of the side wall 3 through the upper wall 9 of the insulation case 2. In the interior of the first and the second cylinders 5, 6 are installed screw shafts 10, 10' which have identical external thread diameters through their length wherein the diameter of the threaded bottom increases gradually from the ends of material feeding ports 8, 8' to the opposite ends, each resting on bearings, and the shafts 10, 10' are disposed so as to be driven in a clockwise direction by driving the pulleys 12, 12' positioned at an end of the insulating case 2 opposite the ends housing the material feeding ports 8, 8' side, through reduction gears (not shown) in the reduction gear box 11. Although driving sources (for example electric motors) for each shaft are to be separately installed, such have not been specifically illustrated.

Further, a discharging port 13 for the third cylinder 7 is located below the material feeding ports 8, 8' and within the interior of cylinder 7 is positioned a screw shaft 14 which has a uniform external threaded diameter, and the inner diameter increases gradually in the direction of discharge side 13. The screw shaft 14 is mounted on bearings, and the end of shaft 14 is made to be rotated in a counterclockwise direction by a pulley 15 through the reduction gear box 11. The driving source of the pulley 15 is not indicated in the drawings, however, a driving source with a change gear can be used.

Further, communicating with the underside of the first and the second cylinders 5, 6, and opposite the position of the material feeding ports 8, 8', material flow ports 16, 16' are provided and are in communication with the sides of the third cylinder 7 and are formed by connecting pipes 17, 17'. A vent 18 is opened from the underside of the third cylinder 7 and at a position adjacent the reduction gear box 11 and between the connecting pipes 17, 17' and gear box 11. Furthermore, a plurality of band heaters 19, 19, 19 are installed to cover exterior walls of the first, second and third cylinders 5, 6 and 7 for heating them.

Due to the above-noted structure of the exemplary embodiment, when a large amount of material scraps accumulate, after the cylinders are heated to the predetermined temperature by way of electric current applied to each band heater 19, 19, 19, screw shafts 10, 10' are driven in the clockwise direction by driving the pulleys 12, 12' separately. Then when finely crushed material scraps (hereinafter called material) are fed through material feeding ports 8, 8', the material is forced into the interior of the first and second cylinders 5, 6 by screw shafts 10, 10', and its volume 15 gradually decreased during its transfer through the first and second cylinders 5, 6, in accordance with changes in diameter of the screw shafts 10, 10' and the material heated by the band heaters 19, 19, 19 along the external surface of the first and second cylinders 5, 6 reaches a half-melted condition. Then, the half-melted material is formed into the connecting pipes 17, 17', then discharged into the third cylinder 7, and transferred to the discharging port 13 by means of the screw shaft 14 which is rotated by the driving pulley 15 at a certain speed corresponding to the amount of material being fed, and then pushed out through the discharging port 13 deaerating foam mingled in the material. On the other hand, gas generated by defoaming moves along the back pressure flow surface of the screw in the opposite direction to material movement and is exhausted to the exterior through vent 18.

When the material scrap feed is of a small quantity, either one of the first and second cylinders 5, 6 is disconnected from its driving source and the band heaters 19, 19, 19, and melting is performed by using only one or the other of the cylinders, and by way of the same operation as stated above.

Now, the second embodiment of the present invention is explained in accordance with FIG. 4 as follows: this exemplary embodiment serves to transfer the height dimension position of the third cylinder 7 so as to be nearer to the first and second cylinders 5, 6, and to connect the first and second cylinders 5, 6 with the third cylinder 7 by connecting pipes 17, 17', which are of simple horizontal configuration. Except as explained, this example is identical with the first exemplary embodiment, therefore further explanation is omitted by using the same symbols in FIG. 4. The second exemplary embodiment has the advantage of allowing a reduction of the total height of the reclaiming machine.

Because the invention has the structure and function as explained in the above-noted exemplary embodiment, the invention allows the use of both the first and second cylinders 5, 6 when the material fed is of large quantity, and the driving of only one of the other of the first and second cylinders 5, 6 when material fed is of a small quantity, serving to save energy as well as requiring no provision for equipment for storing materials. Also, as the materials move through the U-shaped passage, the whole floor area requirement for the installation becomes smaller.

Further, because the first, second and third cylinders 5, 6, 7 are installed in one heat insulated case 2, even when one of the first and second cylinders 5, 6 is stopped in operation by reason of a small amount of material being fed, that cylinder is kept warm due to heating of the other cylinder by the band heaters, 19, 19, 19 which makes warming-up time of the nonoperating cylinder shorter.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.