GB2066698A - Cutting element for solid waste comminutor - Google Patents

Abstract

A cutting element for use in a comminuting apparatus including a generally disc-shaped body portion adapted to receive a shaft of the apparatus along a central axis for rotation about the central axis, and a plurality of teeth members 18 projecting radially from the body portion. Each of the teeth members includes a filleted portion 20 which joins the body portion and which defines an outer cutting edge. The outer cutting edges 22 of the teeth members in turn define a cutting path coaxial with the body portion central axis and the filleted portions each further include a concave surface 24, 26 angled with respect to the cutting path for urging material from the filleted portion. The cutting edges 28, 30 may be angled with respect to the cutting path and the teeth members may include a second and opposite cutting edge and concave surface as shown in the drawing for operation in a second rotational direction. <IMAGE>

Description

SPECIFICATION Cutting element for solid waste comminutor Field of the Invention This invention relates generally to solid waste comminutors and more particularly to an improved cutting element thereof.

Background Various apparatus are known for the comminution of solid waste material into minute particles. One such comminuting apparatus is described in U.S. Patent No. 4,046,324 which was in a continuation-in-part application of U.S.

application number 372,818, filed June 22, 1973.

The aforementioned patent was issued to Chambers, the applicant herein, and is incorporated herein by reference. The apparatus described therein includes a comminution chamber within which is located a first and a second shreading stack. Each shreading stack includes a shaft that carries a plurality of laminar cutting elements which are separated in an axial direction by a plurality of laminar spacers. The shreading stacks are disposed within the comminution chamber such that the cutting elements of a first stack are in an interspaced relationship with the cutting elements of the second stack to thereby perform the comminution function.

The cutting elements of the above-described apparatus are generally configured in the form of a disc from which a plurality of teeth radially project.

Each tooth has a first and a second concave surface which lie along an axis generally parallel to the central axis of the cutting element. Although these cutting elements may accomplish the comminution of solid materials whether or not the materials are entrained in a liquid, it has been found that in the absence of liquid, particles resulting from the comminution of solid dry material frequently become entrappsd by the concave surfaces of the cutting element teeth.

This build up of material dulls the cutting surfaces associated with the cutting elements and may cause the teeth to be broken from the cutting element, thus decreasing the efficiency and effectiveness of the apparatus.

Another cutting element that is known for use in comminuting apparatus is disclosed in U.S.

Patent No. 3,664,592 to Schweigert et al. The cutting element there described includes a single filleted or beveled tooth having a cutting edge which lies in a plane perpendicular to the axis of the cutting element for shearing the material introduced into the apparatus. The tooth, however, is not self-cleaning and thus the cutting element must also include a back tooth which combs the free space between adjacent cutting elements to help remove granulated material therefrom.

Additionally, this cutting element is effective only for operation in a single direction of rotation and thus may not be reversed to prolong its useful life.

Summary of the Invention The cutting element of the present invention overcomes the limitations described above and provides a cutting element having self-cleaning teeth which are effective for the comminution of dry solid materials and which further result in a substantially more efficient operation of the comminuting apparatus. Accordingly, the cutting element of the present invention includes a generally disc-shaped body portion which is adapted to receive the shaft of a comminuting apparatus. Projecting from the body portion are a plurality of teeth members which each include oppositely facing lateral cutting edges and a filleted portion including concave surfaces connecting the cutting edges and the body portion. The lateral cutting edges define a cutting path coaxial with the body portion and the concave surfaces are angled with respect to this cutting path.The lateral cutting edges and the curve of the concave surfaces cooperate to cut or slice the materials introduced into the apparatus into generally tightly formed curls or balls producing relatively uniform sized particles. The angled concave surfaces then discharge the particles thus created to the side of the cutting element and thus prevent the particles from accumulating or packing into the filleted portions.

The cutting edges are similarly angled with respect to the cutting path, both features resulting in a more efficient comminution of solid materials and thereby increasing the operating efficiency of the comminuting apparatus by approximately 70%.

It is thus an object of the present invention to provide an improved cutting element for a comminuting apparatus.

It is another object of the present invention to provide a substantially self-cleaning cutting element for use in a comminuting apparatus.

It is yet a further object of the present invention to provide a more efficient cutting element that may be used in a comminuting apparatus.

These objects as well as other objects and advantages of the present invention will become apparent through a consideration of the following detailed description when taken in conjunction with the accompanying drawings.

Brief Description of the Drawings Figure 1 is a plane view of a cutting element according to the present invention.

Figure 2 is a side view of'the cutting element taken substantially along the line 2-2 of Figure 1.

Detailed Description of the Drawings With reference now to the drawings, a cutting element 10 includes a generally disc-shaped body portion 12. Formed centrally within the body portion 12 is a hexagonal-shaped opening 14 that is adapted to receive a shaft of a comminuting apparatus such as the shaft of the shreading stack previously described. The hexagonal opening 14 is formed coaxially with a central axis 1 6 of the body portion 12.

Projecting from the body portion 12 are a plurality of teeth members 18. Although the cutting element 10 of Figs. 1 and 2 includes three teeth members 1 8a-c, it will be understood by those who are skilled in the art that the number of teeth members 1 8 may be varied but preferably a minimum of two teeth members are provided. It will be further understood that the number of teeth members is determined according to several factors, including the material to be introduced into the apparatus, the fineness of the resulting particles, and the power and gear reduction employed by the apparatus.

Each of the teeth members 1 8at includes a filleted portion 20 extending from the body portion 12, the filleted portion 20 defining a peripheral surface 22. The peripheral surface 22 of each of the teeth members 18 in turn defines a portion of a cylindrical surface which is coaxial with the central axis 16 of the body portion 12.

The filleted portion 20 further includes a first and a second concave surface 24 and 26 which smoothly join the outer surface of the body portion 12 and which intersect the peripheral surface 22 to define first and second cutting edges 28 and 30.

The cutting edges 28 and 30 lie generally along a portion of a circular helix that is coaxial with the axis 1 6 and which is inclined preferably approximately 30 degrees therefrom. The concave surfaces 24 and 26 are generally parallel to the cutting edges 28 and 30. Although this helical relationship is described here to provide a complete and detailed description of Figs. 1 and 2, it is to be noted that this particular relationship is not critical to the present invention. Thus the cutting edges 28 and 30 may be generally considered to define a cutting path designated 32 in Fig. 1 and 2.The cutting path 32 is coaxial with the axis 1 6 and the concave surfaces 24 and 26 and the cutting edges 28 and 30 are angled approximately thirty degrees from a position across the path and parallel to the axis 1 6. The thirty degree angle is to be considered exemplary and variations therefrom will provide the benefits associated with the cutting element of the present invention.

It will be resognized by those skilled in the art that the thickness of the cutting element 1 0 may be varied along with the number of teeth members 18 to vary the particle size. Thus the cutting element 10 thickness may be decreased or increased to correspondingly decrease or increase the resulting particle size.

In use, a plurality of the cutting elements 10 may, for example, be installed in the comminuting apparatus described in Patent No. 4,046,324 and may be rotated about the central axis 1 6. If the cutting element 10 were rotated clockwise with respect to Fig. 1 ,the cutting edge 30 of each of the teeth members 1 8 will cut or slice generally tightly wound curl- or ball-shaped particles from the material introduced into the apparatus and these particles will be in turn deflected or guided away from the cutting element 10 by the concave surface 26 of each of the teeth members 1 8 into the area provided between adjacent cutting elements 10 by the previously described laminar spacers. Once the cutting edge 30 of each of the teeth members 1 8 has dulled or has otherwise become inoperative, the cutting element 10 may be reversed and the cutting edge 28 and the concave surface 24 will then cooperate as just described.

While an examplary embodiment of the invention has been described, it is to be understood that the invention is not limited to the details herein described. It is expected that those skilled in the art will recognize numerous variations and equivalents which come within the spirit of the invention and which are intended to be included herein.

Claims (8)

1. A cutting element for use in a comminuting apparatus comprising a body portion adapted to receive a shaft of said apparatus along a central axis of said body portion, and a plurality of teeth members each including a filleted portion joining said body portion and defining an outer cutting edge, the cutting edges of said teeth members defining a cutting path coaxial with said central axis, and the filleted portions each further including a concave surface angled with respect to said cutting path for urging material from the filleted portion.

2. The cutting element of claim 1 wherein said cutting edges are angled with respect to said cutting path.

3. The cutting element of claim 2 wherein the angle between said concave surface and said cutting path and the angle between said cutting edge and said cutting path are substantially equal.

4. The cutting element of claim 3 wherein said angle is approximately thirty degrees from a position across said cutting path.

5. A cutting element for use in a comminuting apparatus comprising a body portion adapted to receive a shaft of said apparatus along a central axis of said body portion, and a plurality of teeth members each including a filleted portion joining said body portion and defining an outer cutting edge, said cutting edges of said teeth members defining a cutting path coaxial with said central axis, the filleted portions each further including a concave surface, said cutting edge and said concave surface angled with respect to said cutting path.

6. A cutting element as in claim 5 wherein said cutting edge and said concave surface are angled approximately 30 degrees with respect to a position across said cutting path.

7. A cutting element as in claim 5 wherein said cutting element includes at least two of said teeth members.

8. A cutting element as in claim 5 wherein each of said teeth members includes a second and opposite cutting edge and a second and opposite concave surface for cutting in a second direction of rotation of said cutting element with respect to said central axis.