US3918649A

US3918649A - Liners for shredding machines

Info

Publication number: US3918649A
Application number: US456464A
Authority: US
Inventors: Donald G Miller
Original assignee: American Pulverizer Co
Current assignee: American Pulverizer Co
Priority date: 1974-04-07
Filing date: 1974-04-07
Publication date: 1975-11-11
Anticipated expiration: 1992-11-11

Abstract

A manganese steel liner for a reducing machine has antipeening slots opening out of the working surface thereof. When the metal of the liner experiences plastic flow at the working surface as a result of reduced fragments impinging against the working surface, the metal will flow into the slots without creating excessive stresses in or substantial deformation of the liner.

Description

ited States Patent 1 Miller 1 Nov. 11, 1975 1 LINERS FOR SHREDDING MACHINES [75] Inventor: Donald G. Miller, Glendale, Mo.

[73] Assignee: American Pulverizer Company, St.

Louis, Mo.

22 Filed: Apr. 7, 1974 211 Appl. No.: 456,464

[52] US. Cl. 241/189 R; 241/285 A [51] llnt. Cl. B02C 13/09 [58] lField of Search 241/189 R. 207, 285 A [56] References Cited UNITED STATES PATENTS 2185331 1/1940 Conway 241/189 R X 2463.223 3/1949 Verch 241/189 R X 3.6231174 11/1971 Alt 241/189 R Strom 241/189 R X Mertz 241/207 Primary ExuniinerGranvi11e Y. Custer. Jr. Assistant Erumz'ner-Howard N. Goldberg Artur/zen Agent. or Firm-Gravely, Lieder Woodruff [57] ABSTRACT A manganese steel liner for a reducing machine has antipeening slots opening out of the working surface thereof. When the metal of the liner experiences plastic flow at the working surface as a result of reduced fragments impinging against the working surface. the metal will flow into the slots without creating excessive stresses in or substantial deformation of the liner.

5 Claims, 6 Drawing Figures LINERS FOR SHREDDING MACHINES BACKGROUND OF THE INVENTION This invention relates in general to reducing machines and more particularly to liners for reducing machines.

The typical metal shredding machine has a housing and a rotor which revolves in the housing. Scrap metal is fed into the housing and torn into small fragments by hammers on the rotor. The rotor imparts high velocities to these fragments and to prevent the fragments from. damaging the housing walls. the walls are protected with replaceable liners. I

The most commonly used liner material is manganese steel, and when cast into relatively thin plates this material is ideally suited for use in relatively small ma chines such those used to shred steel turnings. metal cans, sheet metal or aluminum castings. In particular. manganese steel is extremely tough and can withstand high impacts without cracking. Also, the metal fragments impinging against the liner cold work it and in so doing create plastic flow. This tends to harden the steel at its exposed surface. leaving the liner with a hard working surface and a tough core. Thus. the rate of wear decreases with use.

The work hardening characteristics of manganese steel create difficulties where that steel is used in extremely thick liners, such as those required for large shredders capable of shredding automobiles. appliances, and the like, due to the extremely large amount of plastic flow. Indeed, the stressesset up within the top 2 to 3 inches of such casting may actually cause the top 2 to 3 inches to separate from the rest of the liner. Moreover, the surface peens or mushrooms over its edges, but the edges are usually confined quit e closely, so as a result the casting bows inwardly towardthe rotor. This in turn contributes to cracking and" also causes the bolts which hold the liner against the housing to fail.

SUMMARY OF THE INVENTION One of the principal objects of the present invention is to provide a manganese steel liner which can withstand severe impacts without failing. Another object is to provide a liner of the type stated which may beused in extremely thick configurations in heavy duty shredding machines. A further object is to provide a liner of the type stated which will not undergo a substantial increase in width when subjected to severe impacts. Still another object is to provide a liner of the type stated which is ideally suited for use in shredding machines capable of reducing automobiles, appliances. andother large metal objects. These and other objects and advantages will become apparent hereinafter.

The present invention is embodied in a liner having voids opening out of its working surface. As the rnetal of the liner undergoes plastic deformation, it flows into the voids. The invention also consists in the partsand in t the arrangements and combinations of parts herein'af .ter described and claimed.

DESCRIPTION or THE DRAWINGS refer to like parts wherever they occur:

FIG. I is a transverse sectional view of a shredder provided with liners constructed in accordance with and embodying the present invention;

FIG. 2 is a plan view of one of the spout liners in the shredder;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2: FIG. 4 isa plan view of a top liner; 7

'FIG. 5 is a sectional view taken along lines 5-5 of FIG. 4; and

FIG. 6 is a plan view of a side liner.

DETAILED DESCRIPTION due to the centrifugal forces on them, normally project.

outwardly and define a hammer circle C. Withinthe inlet l0,- the hammer circle C downwardly converges with the front wall 6 of the housing H. Moreover, the hammers 14 move toward the front wall 6 as they pass by the inlet 10.- At the lower end-of the inlet It the housing H supports a grinding plate 18, and beyond the grinding plate 18 it is provided with a plurality of grates 20 having openings through which shredded material is discharged. The grinding plate 18, and the grates 2010-.

gether occupy an are which extends about 180 along the hammer circle C.

The metal or other material to be shredded is intro-,

duced into the housing H through the inlet, 10. and as the hammers 14 pass by the inlet 10, they tear fragments from the scrap. These fragments are reduced still further along. the grinding plate 18 and grate 20. Most of the fragments are discharged through the openings.

in the grate 20, leaving the grate 20 at a high velocity. However, some of the fragments. particularly the oversized ones, are carried beyond the grate and hurled wit-h great velocity toward the top wall 8 of the housing H.

To prevent the scrap from damaging the housing I-I due to high forces appliedto it at the inlet 10, the front wall 6 at the inlet I0 is covered with spout liners 30.

Likewise, to protect the top wall 8 from the severe impactsof the fragments propelled upwardly beyond the grate 20, the top wall 8 is covered with top liners 32. Also, the sidewalls 2 are protected with

side liners

34, 35, 36 and37. The

liners

30, 32 34 and 36 are held in place with bolts 38.

All of the

liners

30, 3 2, 34, 35, 36 and 37 are castings with the cast metal being known as manganese steel.

The specific designation for standard austenitic manganese steel with a manganese content of from I 1 to 14 percent'manganese and about I percent carbon is A- l28-64, and is commonly referred to as Hadfield Manganese steel, or simply, manganese steel. Some specific alloys are made with small amounts of chrome and/or molybdenum and may also be known as chrom-manganese steel or moly-manganese steel or MOL.

The spout liners 30 which are located in the inlet 10 (FIGS. 2 and 3) are representative of the

liners

30, 32, I 34, 35, 36 and 37. Each spout liner 30 extends the width of the front wall 6 and has a working surface 40 presented toward the rotor R. The liner 30 is further provided with bolt holes 42 for receiving the bolts 38. Actually. the holes 42 are eounterbored from the working surface 40 so that the heads of the bolts 38 are set as close to the front wall 6 as possible. In addition. the liner 30 has antipeening grooves or slots 44 which open inwardly toward the rotor R. that is they open out of the working surface 40 which is exposed to the fragments propelled away from the rotor R and resist forces applied to the scrap by the rotor R. The slots 44 are parallel and extend transversely of the liner 30 the full width thereof. Hence, the slots 44 are oriented in the vertical direction. The bolt holes 42 are centered between the slots 44.

The depth dofeaeh slot should be between 25 and 50 percent of the total thickness 1 of the liner 30 with a depth of 33 percent being preferred (FIG. 3). Usually the thickness 1. which is the distance from the working surface 40 to the major surface area facing the front wall 6 of the housing H, is about 7 inches. Mounting bosses and locating ribs are excluded in measuring the thickness I. The side surfaces of each slot 44 are tapered slightly such that they diverge from the bottom of the slot 44. whereas the bottom is curved. The slots 44 should be wide enough to occupy between l and percent of the working surface 40 out of which they open. In other words. if the width of the liner is W and its length is l. the area of the outwardly opening ends of the slots 44 should be l5 to 25 percent of (w A I). The volume occupied by the slots 44 should be between 3 and 7 percent of the total volume of the liner 20 and should preferably be 5 percent. The area of the working surface 40 between any two adjacent slots 44 should not exceed 400 in. and should preferably be between IOO in. and 250 in, including the area of the bolt holes 42.

Wider liners such as the top liners 32 (FIGS. 4 and 5) in addition to the transverse antipeening slots 44, may be provided with longitudinal slots 46. The longitudinal slot 46 of each top liner 32 extends the full length of the liner 32 and possesses the same depth and cross sectional configuration as the transverse slots 42. The top liners 32 are also about 7 inches thick.

Where a liner is quite wide. such as the side liners 34, 35, or 36 (FIG. 6), it should have a plurality of both transverse antipeening slots 44 and longitudinal antipeening slots 46 which intersect and form a grid pattern. The

top side liners

34, 35 and 37 are about 2 inches thick.

In use. the

liners

30, 32, 34, 35, 36 and 37 do not develop stresses severe enough to cause the metal near the working surface to break away from the core metal, nor do they undergo substantial deformation. Thus. they have a much longer service life. In particular, when the metal ofthe liner 30 tends to flow as a result of being subjected to the forces applied by the scrap when acted upon by the rotor R, the flow is into the antipeening slots 44. The flow from adjacent areas may gradually fill the slots 44, but the work hardened metal at the working surface 40 still retains its continuity with the core of the liner 30 which is the portion adjacent the front wall 6. Moreover. the liner 30 does not experience any significant tendency to lengthen, and as a result it does not bow toward the rotor R. This in turn keeps the bolts 38 in tact. The

liners

32, 34, 35 and 37 function in the same manner, only the metal at the 4 working surface 40 can flow into the longitudinal slots 46 also. w g a Generally speaking the antipeening slots in the liners heed not form any pattern. The antipeening slots should however I. open toward the direction from which the fragments come or impact forces are applied so that they open out of the working surface area against which the fragments impinge;

2. having a depth between 25 and 50 percent of the thickness of the liner:

3. border or enclose a portion of the working surface not less than 50 in. and not greater than 400 inF;

4v occupy between 3 and 7 percent of the total volume of the liner;

5 occupy between 15 and 25 percent of the working surface out of which they open.

In measuring the thickness of a liner small mounting bosses, peripheral ribs, and similar protrusions from the major surface area at the back of the liner should not be considered Likewise. shallow recesses opening out of the back of the liner should not be computed. Thus, the thickness is the distance from the major surface area at the rear of the liner to the working surface 40. In computing thetotal area of the working surface. the areas of the outwardly opening ends of the

slots

44 and 46 and of the bolt holes 42 should be included. In other words. the areaof the working surface on a rectangular liner is for all intents and purposes its length times its width. In computing the surface area bordered or en- 7 closed by two or more slots. the areas of the bolt holes are included in that surface area,

This invention is intended to cover all changes and modifications of the example of the invention herein chosen for purposes ofthe disclosure which do not constitute departures from the spirit and scope of the, invention.

What is claimed is:

1. In a reducing machine including a housing having an inlet. a grate in the housing, and a rotor which revolves in the housing above the grate and about a horizontal axes so as to engage material introduced into the housing through the inlet to reduce that material to fragments of smaller size which will pass through the grate, the improvement comprising a liner attached firmly to the housing above the grate and outwardly from the rotor such that it is between the housing and rotor so as to protect the housing from fragments propelled by the rotor, the liner being formed from steel which tends to flow upon being subjected to impacts and having a working surface presented toward the rotor, the liner further having a plurality of grooves which open out of the working surface, the grooves having curved inner ends and further being tapered outwardly from their curved inner ends so that the grooves have their greatest width at the working surface, the depth of each groove being between about 25 and 50 percent of the thickness of the liner at the groove, and the area bordered by two or more grooves being between about 50 in} and 400 in whereby the metal of the liner will flow into the grooves asit undergoes plastic deformation and will not create excessive stresses or substantially deform the liner as a whole.

2. The structure according to claim 1 wherein the volumeof the gr'oove'is between 3 and 7 percent of the .total volume of the liner (groove included). included.

metal from which the lineris formed is manganese 3 T stmcwrc, ording to claim I wherein h 5. Thc'struct'ure according to claim I wherein the tween about 15 and 25 percent of the total area of the l I t working surface for the liner (groove area included in 4. A liner according to claim 1 wherein the grooves 5 mm] working Surface area);

intersect to form a grid pattern.

steel.

areaof the outwardly opening ends olthe grooves is he-

Claims

1. In a reducing machine including a housing having an inlet, a grate in the housing, and a rotor which revolves in the housing above the grate and about a horizontal axes so as to engage material introduced into the housing through the inlet to reduce that material to fragments of smaller size which will pass through the grate, the improvement comprising a liner attached firmly to the housing above the grate and outwardly from the rotor such that it is between the housing and rotor so as to protect the housing from fragments propelled by the rotor, the liner being formed from steel which tends to flow upon being subjected to impacts and having a working surface presented toward the rotor, the liner further having a plurality of grooves which open out of the working surface, the grooves having curved inner ends and further being tapered outwardly from their curved inner ends so that the grooves have their greatest width at the working surface, the depth of each groove being between about 25 and 50 percent of the thickness of the liner at the groove, and the area bordered by two or more grooves being between about 50 in.2 and 400 in.2, whereby the metal of the liner will flow into the grooves as it undergoes plastic deformation and will not create excessive stresses or substantially deform the liner as a whole.

2. The structure according to claim 1 wherein the volume of the groove is between 3 and 7 percent of the total volume of the liner (groove included). included.

3. The structure according to claim 1 wherein the metal from which the liner is formed is manganese steel.

4. A liner according to claim 1 wherein the grooves intersect to form a grid pattern.

5. The structure according to claim 1 wherein the area of the outwardly opening ends of the grooves is between about 15 and 25 percent of the total area of the working surface for the liner (groove area included in total working surface area).