Solid material comminution or disintegration – Apparatus – With automatic control
Patent
1980-03-05
1982-09-28
Rosenbaum, Mark
Solid material comminution or disintegration
Apparatus
With automatic control
241236, 241285B, B02C 2500
Patent
active
043514855
DESCRIPTION:
BRIEF SUMMARY
This invention relates to rotary shredding machines of the kind (hereinafter referred to as a "machine of the kind hereinbefore specified") having a comminuting chamber, a pair of parallel cutting shafts extending through the chamber, disc-like cutters on the shafts in said chamber, drive means for driving said shafts in simultaneous contra-rotation, and a feed hopper above the comminuting chamber for feeding material to the cutters, the cutters on one shaft being interleaved with those on the other so that said material is comminuted by the cutters in a cutting zone lying between the said shafts.
Although machines of the above kind are normally referred to as shredding machines or shredders, their comminuting action takes a form or forms which depend largely on the nature of the material being comminuted, and on the design of the cutters. The latter may in practice perform very little cutting as such; for example, glass will tend to be crushed into small pieces, whilst other common materials, such as thin metal, will tend to be torn and/or deformed by crushing. The material to be comminuted is most usually scrap or waste material, though shredders can be used to break up solid materials as part of, or in preparation for, industrial processes of various kinds.
Various types of shredding machine of the kind hereinbefore specified are in commercial use or have been proposed.
The specification of our co-pending British patent application No. 34262/76 describes shredding machines within the aforementioned definition of kind, in which an automatically disengageable clutch is interposed in the drive mechanism, and in which those working components directly or indirectly controlled by the clutch are so constructed that they will not fail under their own or each other's inertia effects when subject to so-called "crash-stop" conditions, e.g. when so-called tramp material in the form of an intractable object is encountered by the cutters which cannot comminute the tramp material.
It is well known to provide a shredder with an automatic reversing facility, whereby under crash-stop conditions, or under conditions of cutter obstruction less severe than this, e.g. when a particularly tough piece of material is nevertheless capable of being comminuted by the cutters, rotation of the cutters is momentarily halted and reversed through a short distance, after which forward rotation is resumed. Typically the machine has a control system such that this reversal may be repeated several times, but also so that, if the tough piece of material has still not been dealt with by the cutters, the machine can be stopped. The offending piece of material can then be removed, usually by hand through the hopper. In a machine of the kind described in our said specification No. 34262/76, the clutch will disengage when the torque imposed by resistance to material being handled reaches a certain predetermined value, but in many instances this torque need not reach that value where one or more reversals will suffice to deal with a "difficult" piece of material. The machine is therefore preferably arranged so that a series of reversals can take place and so that the clutch only disengages if either this is unsuccessful in clearing the obstruction, or the tramp material imposes a force on the cutters such that a torque of at least the abovementioned predetermined value is immediately imposed on the clutch.
Where a clutch or other suitable torque-limiting device is not provided, the control system will be so arranged that the drive motor is stopped.
Arrangements for recirculating material within the comminuting chamber, so as to enable the material to be passed through the cutting zone several times until it has been comminuted into sufficiently small pieces, have also been proposed. One such arrangement is described in British Patent Specification No. 1,310,057, in which the cutter shafts of a machine, which is generally of the kind hereinbefore specified, have their axes in a common plane inclined to the horizontal, the comminuting chamber bein
REFERENCES:
patent: 3587983 (1971-06-01), Heinrich
patent: 3677478 (1972-07-01), Schutte
patent: 4034918 (1977-07-01), Culbertson et al.
Hardwick John P.
Pezet Michael J.
Sarvestany Asadollah A.
Satharasinghe Dayananda
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