Solid material comminution or disintegration – Apparatus – Cooperating comminuting surfaces
Patent
1988-12-09
1990-03-06
Eley, Timothy V.
Solid material comminution or disintegration
Apparatus
Cooperating comminuting surfaces
241207, B02C 206, B02C 1900
Patent
active
049059203
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a milling device comprising two milling bodies, one of which is hollow and encloses the other, and a driving unit connected to one of said milling bodies via a shaft nonrotatably connected with said one milling body to cause it to rotate about its own axis in rolling contact with the milling body.
Milling devices of this type, such as pendulum mills, are previously known and operate efficiently in that the milling stock, because of the active rotation of one of said milling bodies, is subjected to both compressive forces and shear forces, whereby a highly efficient comminution of the milling stock is achieved. Prior art pendulum mills comprise a sleeve-shaped and stationary casing, against the inner side of which a rotor is caused to roll for crushing the milling stock introduced therebetween. A major proportion of the energy supplied to the rotor is transferred to the stationary casing which thus is subjected to heavy vibrations and must be given a very sturdy construction in order not to shake apart. As a consequence, also the efficiency of such pendulum mills will be unsatisfactory, and furthermore there is a risk that the crushed milling stock will adhere to the inner side of the casing.
SUMMARY OF THE INVENTION
It therefore is the object of the present invention to provide a milling device which is of the above-mentioned type and which eliminates the shortcomings of prior art pendulum mills.
To this end, the milling device is characterised in that both milling bodies are universally movable in a surface essentially transverse to the axis of rotation, but are actuated by a return force which increases as the pendulum movement increases.
To generate the return force, both milling bodies can be supported in pendulum fashion, such that the pendulum centers lie on the same side of said milling bodies or each on one side thereof. Alternatively, or in combination with the pendulum suspension, elastic means, such as springs, may be provided in order to generate the return force.
Preferably, both milling bodies are symmetrical with respect to rotation, but there is nothing to prevent their being oval or of some other noncircular shape, whereby the crushing force can be varied along the path of movement of the contact point.
The milling bodies are suitably arranged to move about a common center and, more particularly, to effect their pendulum movements in balanced phase opposition.
The milling surfaces of the milling bodies preferably are designed such that the contact point therebetween constitutes the apex of a gap which is wedge-shaped in the direction of the axis of rotation, thereby to facilitate multiple crushing of particles during a single run through the milling device.
Preferably, only one of said milling bodies is rotated so that the other milling body is essentially nonrotatable in the surface of the universal movability. However, it is also possible that both milling bodies are actively driven for rotation, either in the same direction or in opposite directions, and naturally in mutual rolling contact in both instances.
If one milling body is driven and the other essentially nonrotatable, both milling bodies being symmetrical with respect of rotation, the geometrical location of the contact point between the milling bodies will be a circle whose diameter is less than the diameter of the milling surface of the surrounding milling body. Each point on the surrounding milling body will move along a circle whose diameter is essentially less than the diameter of the milling surface of the surrounding milling body, and each point on the milling surface of the enclosed milling body will describe a hypocycloid.
A number of advantages are obtained by a milling device designed in accordance with the present invention. Thus, the milling bodies are counterbalanced, such that no essential vibration will occur in the frame of the milling device. Furthermore, the transfer of energy to the milling stock will be optimal, and u
REFERENCES:
patent: 1799476 (1931-04-01), Newhouse
patent: 1976728 (1933-11-01), McCatrell
patent: 2186596 (1940-01-01), Spohn, Jr.
patent: 4434944 (1984-03-01), Bodine
Loodberg Jan A. T.
Siwersson Olle L.
Wall Arne E.
AB Scaniainventor
Eley Timothy V.
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