CUTTING TOOL, ESPECIALLY FOR THE CUTTING OP DISCARDED CABLE.
The invention relates to a cutting tool for cutting discarded cables and wires comprising a rotating -cutting means and a bottom blade co-operating with said cutting means.
Almost all electric wires and cables contain copper, this metal having a high degree of conductivity. How¬ ever, copper is fairly expensive, and thus it is very advantageous to recycle copper from discarded wires and cables.
Wires and cables can be constructed in many different ways, but it is a common feature that each conductor is insulated. To facilitate a rational recycling of the copper from discarded cables it is thus necessary that this insulation, primarily made of plastics, can be removed in an inexpensive and rational way.
Apparatuses for this purpose are known, but these necessitate that the discarded cables are fed in small lengths, e.g. 5-20 cm.
Pur such a cutting of discarded cables various kinds of rasps and the like are known, but all of these have very high energy consumption,the discarded cables often being torn or beaten to pieces.
The object of the present invention is to provide a cutting tool without the above disadvantages, as the cutting tool according to the present invention
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can cut up discarded cable with lower energy con¬ sumption than any hitherto known tools.
This object is achieved if the rotating cutting tool comprises one or more plate shaped, projecting knife blades being secured to a rotating shaft or drum in such a manner that the plane formed by each knife blade when the knife blade is in a position parallel to the bottom blade before the cutting takes place, is staggered parallel to the plane formed by the bottom blade in the direction towards the direction of motion of the knife blade.
The projecting knife blade or blades can be made very strong, and as the knife blade is staggered in rela¬ tion to the bottom blade, the cutting of the discard¬ ed cable will take place as a smooth cut which does not require high energy consumption. The material is carried by a feeding device towards the knife. Mate- rial which may fall through the openings of the edge of the bottom blade is already of a length suitable for further processing. Furthermore, the discarded cable is safely secured during the cutting as the knife blade moving from above secures that discarded cable is not pressed to the sides during the cutting.
If the cutting tool is constructed with knife blades with one and one only front part with a maximum distance to the periphery of the shaft, and the cut- ting edges of each knife blade run evenly towards the shaft from this part, a cutting with even less energy consumption can take place, as the immediate cutting points will be displaced along the cutting edge during the cutting. Thus no large amounts of cable are to be cut at the same time.
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If triangular knife blades are applied, as referred to in claim 3, a strong knife is achieved which is easy to manufacture and which gives a smooth and clean cut. Furthermore, this clean cut helps to make the blades more durable.
If the axis of rotation of the shaft is in the plane formed by the bottom blade a simple and expedient construction of the tool is achieved.
It is expedient, as mentioned in claim 5, to place the knife blades in continuation of each other thus forming one long connected cutting edge, and if, as dealt with in claim β, the knife blades are distri¬ buted along the periphery of the shaft, an even load of the motor is achieved, as only one or a few- of the knifes cut simultaneously.
A cutting tool according to the invention may, more- over, as dealt with in claims 7 and 8, be characte¬ ristic in that the knife blades can be released from their attachment to e.g. a back. It is expedient that individual knife blades may be replaced in case of damage. A back behind the knife blades will support this efficiently and provide a safe cut and at the same time provide a good attachment for the knife blade.
In the following the invention will be described in more- detail with reference to the drawing, where
fig. 1 shows a cutting tool according to the invention with a feeding device and control means,
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fig. 2 shows a shaft with knife blades accord¬ ing to the invention,
fig. 3 shows a section of a shaft with a knife blade according to the invention, seen from the front on a larger scale, and
fig. 4 shows a section through the shaft as in fig. 3_ seen in the direction of the arrows along the line IV-IV.
In fig. 1 a cutting tool according to the invention with reference number 1 is shown. Discarded cable can be fed through a funnel 2 and drops on a plate 3 in a feeding device where carrier teeth carry the cable- forwards for being cut. The one end of the plate 3 is designed as a bottom blade 7 having triangular cutouts from its edge.
Corresponding to these cutouts the cutting tool has triangular knife blades situated on a rotating shaft 4. The whole cutting tool 1 is driven by a motor 5. e.g. by belt or chain drive. After the cutting the cut pieces of cable are removed by a conveyor belt 6 or the like.
In fig. 2 is shown a shaft 4 with knife blades 8 ac¬ cording to the invention. The knife blades are flat plate shaped parts, e.g. made of iron plate and pro- jecting from the periphery of the shaft 4. To the rear the knife blades 8 are supported by a back 9 which e.g. by welding is secured to the shaft 4. The knife blades 8 may be secured to the back 9 or the shaft 4 in any known way, e.g. by means of screws or
bolts, but it is expedient if the assembly can be disassembled to facilitate replacement of one or more of the knife blades
In fig. 3 and 4 details of the knife blades 8 are shown on a larger scale, and it is seen how the plane of the knife blades is staggered in relation to the plane of the bottom blade 7.
As appears from particularly fig. 2 the knife blades 8 are placed in continuation of each other in the longitudinal direction of the shaft 4. Thus it be¬ comes possible to make a knife with large capacity. It is expedient if the knife blades 8 are distributed along the periphery of the shaft 4 in order that only one or perhaps two knife blades 8 cut simultaneously. This evens the load of the motor as this need not have a capacity for more than one cut.
If each knife blade 8 is to cut at two points only at a time, the knife blades should be e.g. triangular or tongue shaped in order that the cutting points, when a knife blade 8 passes the bottom blade 7, are staggered from the point of the knife blade 8 towards the shaft 4. Thus it is moreover achieved that discarded cable is cut through without being pressed to the sides, and a very clean cut is achiev¬ ed. This cut requires considerably lower effect than if the discarded cable e.g. were to be torn or beaten to pieces.
It is obvious that the bottom blade 7 must be con¬ structed to fit the shape and size of the knife blade 8 exactly. Like the knife blades 8 the bottom
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blade 7 can ideally be made of iron plate.
A cutting tool according to the invention may be constructed in various ways as to the shape of the knife blades 8 and the bottom blade 7. The cutting tool may also be applied for cutting other material than discarded cable, which may involve other re¬ quirements concerning choice of material and con¬ struction. Also the number of knife blades will de- pend on the use, but often six to ten and preferably eight knife blades will be ideal.