Solid material comminution or disintegration – Apparatus – With separation or classification of material
Reexamination Certificate
1999-06-24
2001-07-17
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Apparatus
With separation or classification of material
C241S101761, C241S186400
Reexamination Certificate
active
06260778
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to tub grinders and in particular a tub grinder in which the swing diameter of the hammer mill incorporated therein is adjustable.
Tub grinders are used for chopping or grinding various materials to facilitate handling, disposal or processing. Tub grinders generally comprise a stationary floor with a cylindrical side wall which rotates relative to the floor. Projections or fins extending inwardly from the sidewall engage material positioned in the tub causing the material to rotate with the cylindrical side wall relative to the floor. A hammer mill having a plurality of hammers extending radially outward is rotatably mounted below the floor of the tub grinder such that the hammers extend above the floor and into contact with the material to be ground during a portion of the hammers path of rotation.
Traditionally, tub grinders have been equipped with a hammer mill having a fixed swing diameter. However, variations in the properties of the material to be ground can significantly affect the efficiency of the tub grinder. Therefore, existing tub grinders are limited in the type or size of materials they can process efficiently. For example, for some materials, the depth of cut provided by the hammer mill will be too deep causing the machine to bog down. For other materials, the same hammer mill will take in less material than it is capable of efficiently processing, adding time and cost to the grinding process.
Due to the costs of tub grinders, it is generally impractical for the operator to purchase different tub grinders for processing different materials. The operators generally must base their purchasing decision on the efficiency of the particular hammer mill (based in part on its hammer mill swing diameter) in processing the material most commonly processed by that operator. There remains a need for tub grinders which provide greater flexibility in efficiently processing different materials.
SUMMARY OF THE INVENTION
The present invention comprises a tub grinder having a hammer mill having a swing diameter which is adjustable. The tub grinder includes: a first and second set of interchangeable hammers, the second set being shorter than the first; first and second interchangeable semi-cylindrical screen assemblies, the second screen assembly having a smaller diameter than the first; and a pair of shear bars and adapter plates.
In a first configuration, the first set of hammers are mounted to a rotor assembly and have a first swing diameter. The first semi-cylindrical screen assembly, having a radius of curvature slightly greater than the radius of the first set of hammers, is secured within a cylinder box or hammer mill housing in co-axial alignment and outwardly spaced relationship with the first set of hammers. The first screen assembly is supported on screen tracks mounted on opposite ends of the hammer mill housing and are held thereagainst by inside screen retainers which are also mounted to the opposite ends of the hammer mill housing.
The shear bars are mounted to shear bar mounts on the floor of the tub grinder on opposite sides of the hammer mill housing. The shear bar mounts are angled downward and inward toward the axis or rotation of the rotor assembly, such that the shear bars are similarly angled toward the axis of rotation of the rotor assembly. A small gap extends between the outer rotational path or swing diameter of the first set of hammers and the shear bars and the first screen assembly to produce a shearing or chopping action between the hammers and the shear bar and a grinding action between the hammers and the first screen assembly which has a plurality of openings extending therethrough.
In a second configuration, the first set of hammers are replaced by the second set of hammers which are mounted to the rotor assembly and have a second swing diameter which is smaller than the first swing diameter. The first semi-cylindrical screen assembly is removed and replaced by the second screen assembly which has a smaller radius of curvature. The screen tracks and screen retainers used to support the first semi-cylindrical screen assembly are replaced by a second set thereof adapted to support the second screen assembly relative to the cylinder box.
An adapter bar is mounted to each of the shear bar mounts and a shear bar is mounted to each adapter bar to move a leading edge of each shear bar closer to the path of rotation of the hammers. Each adapter bar positions a leading edge of an attached shear bar approximately the same distance away from the second set of hammers as the shear bars are positioned away from the rotational path of the first set of hammers when mounted directly to the shear bar mounts in the first configuration. Similarly, the distance between the rotational path of the second set of hammers and the second screen assembly is approximately the same as the distance between the rotational path of the first set of hammers and the first screen assembly.
OBJECTS AND ADVANTAGES OF THE INVENTION
It is an object of this invention to provide a tub grinder in which the rotational path of a hammer mill assembly associated therewith is adjustable; to provide such a tub grinder which incorporates a first and second set of interchangeable hammers, one set being longer than the other, which are selectively and interchangeably securable to a hammer mill rotor assembly of the tub grinder; to provide such a tub grinder having first and second semi-cylindrical screen assemblies which are selectively and interchangeably securable to a hammer mill housing of the hammer mill to selectively accommodate the swing diameter of the first and second set of hammers respectively; to provide such a hammer mill in which the shear bars may be moved closer or further away from an axis of rotation of the rotor assembly to accommodate the swing diameter of the first and second set of hammers respectively; to provide such a tub grinder in which it is relatively easy to modify the swing diameter of the hammers; to provide such a tub grinder in which it is relatively easy to interchange the first screen assembly with the second screen assembly; and to provide such a tub grinder which is particularly well adapted for its intended uses thereof.
Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.
The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.
REFERENCES:
patent: 4106706 (1978-08-01), Burrows
patent: 4773601 (1988-09-01), Urich
patent: 5419502 (1995-05-01), Morey
patent: 5570849 (1996-11-01), Anderson
patent: 5626298 (1997-05-01), Arnoldy
patent: 5887808 (1999-03-01), Lucas
patent: 688523 (1953-03-01), None
C. W. Mill Equipment Co., Inc.
Rosenbaum Mark
Shughart Thomson & Kilroy P.C.
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