Patent Publication Number: US-7584530-B2

Title: Method and apparatus for compressing scrap metal strip

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to equipment for processing scrap metal, and more particularly to equipment for compressing scrap metal strip into a more densified form. 
   Scrap metal strip is a residual by-product of manufacturing operations in which, typically, a coil of metal strip (e.g., a coil of steel strip) is subjected to a series of processing steps which may include slitting the edges of the strip and stamping pieces from the strip. The resulting residue includes a multiplicity of pieces having different contours and sizes: long pieces, both tangled and untangled; shorter pieces; skeletal pieces; sheet-like pieces; and rejected or defective stamped pieces. 
   Almost all scrap metal strip from manufacturing operations is recycled as part of the raw material to make new metal. In the case of scrap steel strip, it is part of the raw material charged into steel-making furnaces, of which there are two main types: the electric arc furnace in which most or all of the charge is steel scrap; and the basic oxygen furnace in which steel scrap is generally about 25-30% of the charge. 
   Scrap metal strip is typically light gauge (i.e., thin), and a given volume of uncompressed scrap metal strip has a relatively low density, too low to be a desirable part of the charge for a metal-making melting furnace, which requires a more compact, more densified charge. The percentage of recovery of new metal from scrap, when the scrap is melted in a metal-making furnace, depends in part on the compactness and density of the scrap metal in the charge. 
   To overcome the deficiency described in the preceding paragraph, scrap metal strip is typically compressed into bales which are compact, densified cubes of material. In the case of scrap steel strip, a bale thereof can have cross-sectional dimensions of 40×40 cm (16×16 in.) and a length of 60 cm (24 in.). Bales of other light gauge steel scrap can have cross-sectional dimensions of up to 60×60 cm (24×24 in.) and a length up to 150 cm (60 in.). 
   In addition to improving the recovery percentage of the scrap metal strip when it is melted, the bales facilitate the handling, storage and transportation of the scrap metal strip. 
   The current commercial process employed to compress scrap metal strip into bales is a batch operation in which a discrete volume of scrap is processed into a bale, after which a second discrete volume is subjected to the same processing operation in the same apparatus. The processing of the second volume cannot begin until the processing of the first volume has been completed (a delay, typically, of one minute or more). A more detailed description of the batch baling operation and apparatus is set forth below. 
   A discrete volume of scrap metal strip is loaded into a charging box which is then tipped to discharge its load into an opening in the top of an elongated, horizontally disposed compression chamber. The charging box is then returned to its loading position to receive another discrete volume of scrap, and the opening in the top of the compression chamber is closed with a hinged, hydraulically powered lid or cover which exerts a relatively small amount of vertical compression on the low density volume of scrap in the compression chamber. The scrap is then compressed, typically in two horizontal directions, each transverse to the other, by a pair of hydraulic rams movable between retracted and extended positions. One ram is extended to compress the scrap in a lateral, horizontal direction in the elongated compression chamber, and the other ram is extended to compress the scrap in a longitudinal, horizontal direction. The resulting bale is ejected from the compression chamber, the rams are retracted, the cover on the compression chamber is opened and the above-described sequence of processing steps is repeated on a new, discrete volume of scrap metal strip. 
   A problem can arise when a load of scrap metal strip is discharged from the charging box into the compression chamber. The load can contain long pieces of strip, parts of which can extend outside the top opening of the compression chamber and hang out over the edge of that opening. Before one can close the hinged lid for that opening, the overhanging strip parts (i.e., the excess scrap metal strip) have to be manually cut off i.e., trimmed, typically with an acetylene torch, or other device, wielded by a member of the crew that operates the baling apparatus. This interrupts and delays the sequence of processing steps and incurs an expenditure of non-productive time, effort and money. 
   Because of the problem described in the preceding paragraph, and because of the employment of a batch process with its inherent limitations on productivity, the current commercial operation for compressing scrap metal strip into bales is relatively inefficient. A continuous process for compressing scrap metal strip would be desirable. 
   The scrap metal strip discussed above is, as previously noted, a residual by-product of manufacturing operations performed on coils of new metal, e.g., coils of new steel strip. Scrap generated as a residual by-product of manufacturing operations is known as “industrial scrap”. Another type of scrap, called “obsolete scrap,” is composed of discarded articles made of metal. Light gauge, obsolete steel scrap and some heavier obsolete steel scrap are subjected to continuous processing in an apparatus known as a “shredder”. 
   In a shredder, the steel scrap is flailed, by rotating, free-swinging hammers, into relatively small, fist-sized pieces that provide a compact, densified charge in a melting furnace. Obsolete steel scrap is continuously fed into a shredder along a downwardly inclined path on which is located compacting equipment which can be a pair of compression rolls or a continuous, tread-like member having a portion converging toward the path in a downstream direction. The compacting equipment reduces the volume of the obsolete scrap before the scrap enters the shredder. Shredding is essentially a continuous process. 
   Earlier versions of the shredder dropped whole, obsolete autos, in free fall, along a vertical path onto the rotating hammers of the shredder. 
   A scrap-processing apparatus known as a “logger/shear” has an elongated, horizontally disposed chamber into which is loaded obsolete steel scrap which is then compacted vertically and laterally by hydraulically powered compacting elements to form an elongated cube, or log. The log is pushed downstream through the chamber, by a hydraulic ram, toward a stationary guillotine shear which cuts the log into smaller pieces. The shear comprises a hydraulically powered upper shear blade which is raised to allow a portion of the log to be pushed downstream of the shear blade following which the blade is lowered to sever that portion from the log. The logger/shear, like the baler, processes one batch of scrap at a time. 
   There are steel rolling mills that produce an elongated steel product which moves in a continuous stream along a horizontal path where the elongated product is cut into shorter lengths by a traveling or flying shear. The shear is mounted in a movable housing that moves in the same direction and at the same speed as the steel product during the shearing operation. After each cut, the housing moves back to its original position in preparation for the next cut. 
   Balers, shredders, loggers and shears are described in detail in the following publication: Nijkerk, A. A. and Dalmijn, W. L., Handbook of Recycling Techniques, Nijkerk Consultancy, The Hague, Netherlands, 1998. This publication will hereinafter be referred to an “Nijkerk.” Relevant parts of Nijkerk, designated herein below, are incorporated herein by reference. 
   SUMMARY OF THE INVENTION 
   The drawbacks and deficiencies of the baling operation described above are eliminated by the present invention, some embodiments of which provide an apparatus and method for continuously compressing scrap metal strip. A preferred embodiment of the apparatus comprises a pair of compression rolls and a traveling shear arranged, in that sequence, along an essentially vertical processing path having an upstream end. A volume of scrap metal strip is received at the upstream end and moves downstream along the processing path, preferably as a continuous stream, under the urging of gravity. The stream is compressed into a continuous slab of compressed strip by the compression rolls which move or feed the continuous slab downstream toward the traveling shear which cuts the continuous slab into slab portions each composed of compressed scrap metal strip. 
   The introduction of the scrap metal strip into the apparatus, the compression step and the shearing step are all performed without interrupting the downstream movement of the stream and the slab along the processing path. 
   The processing path includes a vertically disposed chamber having an opening at the upstream end of the processing path and through which the continuous stream of scrap metal strip is introduced. Because of the manner in which the apparatus is constructed and the manner in which the process is performed, it should be unnecessary to interrupt the processing operation to remove overhanging strip parts at the chamber&#39;s opening. This will be discussed in more detail below. 
   Other features and advantages are inherent in the method and apparatus described and claimed or will become apparent to those skilled in the art from the following detailed description in conjunction with the accompanying diagrammatic drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1   a  and  1   b  are fragmentary side views, partially in section, showing portions of an embodiment of an apparatus in accordance with the present invention; 
       FIG. 2  is a sectional view taken along line  2 - 2  in  FIG. 1   a;    
       FIG. 3  is a sectional view taken along line  3 - 3  in  FIG. 1   a;    
       FIG. 4  is an enlarged, fragmentary sectional view showing part of the structure illustrated in  FIG. 2 ; 
       FIG. 5  is an enlarged, fragmentary sectional view showing part of the structure illustrated in  FIG. 1   a;    
       FIG. 6  is an enlarged, fragmentary view showing another part of the structure illustrated in  FIG. 1   a;    
       FIG. 7  is a view similar to  FIG. 1   b  showing a portion of another embodiment of the present invention; 
       FIG. 8  is a side sectional view showing a component of the embodiment of  FIG. 7 ; 
       FIG. 9  is an enlarged, fragmentary side view, partially in section, showing a variation of the embodiment of  FIG. 1   b;    
       FIGS. 10-12  are enlarged, fragmentary side views, partially in section, illustrating another variation of the embodiment of  FIG. 1   b , in operation; 
       FIG. 13  is a fragmentary front view of a component of the apparatus illustrated in section in  FIG. 10 ; 
       FIG. 14  is a side view, partially in section, illustrating a portion of the apparatus downstream of those portions shown in  FIGS. 1   b  and  10 - 12 ; 
       FIG. 15  is a fragmentary side sectional view showing a component of the apparatus portion illustrated in  FIG. 14 ; 
       FIG. 16  is a front view of the whole of the component shown in  FIG. 15 ; 
       FIG. 17  is a side view, partially in section, and partially cut away, illustrating an embodiment of a traveling shear for use in an apparatus of the present invention; 
       FIG. 18  is a sectional view, partially cut away, taken along like  18 - 18  in  FIG. 17 ; 
       FIG. 19  is a block diagram of an embodiment of a control system for the traveling shear of  FIG. 17 ; 
       FIG. 20  is an end view illustrating a portion of the apparatus, downstream of the portion illustrated in  FIG. 14 , and for use in some embodiments of the present invention; 
       FIG. 21  is a plan view of one component of the embodiment shown in  FIG. 20 ; 
       FIG. 22  is a side view of the embodiment of  FIG. 20  and showing additional apparatus portions downstream of the portion shown in  FIG. 20 ; 
       FIG. 23  is a sectional view taken along line  23 - 23  in  FIG. 22 ; 
       FIG. 24  is a sectional view taken along line  24 - 24  in  FIG. 22 , with some parts deleted for purposes of clarity; 
       FIG. 25  is a fragmentary side view, similar to  FIG. 1   a , illustrating another embodiment of an apparatus in accordance with the present invention; 
       FIG. 26  is a sectional view taken along line  26 - 26  in  FIG. 25 ; 
       FIG. 27  is a fragmentary side view, similar to  FIG. 25 , illustrating a further embodiment of the present invention; 
       FIG. 28  is an end view, partially in section, of the embodiment illustrated in  FIG. 27 ; 
       FIG. 29  is a fragmentary side view, similar to  FIG. 25 , illustrating yet another embodiment of the present invention; 
       FIG. 30  is an end view, partially in section, showing a variation of the embodiment illustrated in  FIG. 28 ; 
       FIG. 31  is an end view, partially in section, showing a variation incorporating components from the embodiments of both  FIGS. 28 and 29 ; 
       FIG. 32  is a fragmentary side view, partially in section, illustrating a variation of the embodiment shown in  FIG. 1   a;    
       FIG. 33  is a side view, partially in section, illustrating a portion of yet another embodiment of the present invention; 
       FIG. 34  is a side view illustrating a downstream portion of the embodiment of  FIG. 33 ; 
       FIG. 35  is a diagrammatic side view of a traveling shear for use in an embodiment of the present invention; 
       FIG. 36  is a fragmentary side view, of a variation of the embodiment of  FIG. 33  with a portion of the apparatus removed; 
       FIG. 37  is a view taken along line  37 - 37  in  FIG. 36 , with a portion of the apparatus removed; 
       FIG. 38  is a fragmentary side view illustrating a variation of the embodiment of  FIG. 1   b ; and 
       FIG. 39  is a diagrammatic side view illustrating an embodiment employing a second shearing step. 
   

   DETAILED DESCRIPTION 
   Referring initially to  FIGS. 1   a  and  1   b , indicated generally at  40  is an apparatus for compressing scrap metal strip, in accordance with an embodiment of the present invention. Apparatus  40  comprises a processing path  41  having an upstream end  42  and, in the embodiment of  FIGS. 1   a  and  1   b , a vertical disposition. Located along path  41 , downstream of the path&#39;s upstream end  42 , are a pair of compression rolls  44 ,  45 . Located downstream of the compression rolls, along processing path  41 , is a traveling guillotine shear indicated generally at  47  in  FIG. 1   b . Shear  47  includes two shear blades  48 ,  49  and corresponding blade holders  50 ,  51 , all of which are shown here representationally, as in Nijkerk (p. 48, FIG. V-6-16a and p. 49, FIG. V-6-16b). 
   That portion of processing path  41  upstream of compression rolls  44 ,  45  is defined by a charging or receiving chamber  53  having an open upper end or entrance  54  at the path&#39;s upstream end  42 . Scrap metal strip is introduced through open upper end  54  into chamber  53 . The construction and disposition of chamber  53  enables scrap metal strip received within chamber  53  to move downstream along path  41 , as a continuous stream  56  ( FIG. 1   b ), under the urging of gravity, and toward compression rolls  44 ,  45 . 
   Referring to  FIG. 1   b , compression rolls  44 ,  45  are rotated to compress between them the scrap metal strip in stream  56  and form a continuous slab  57  composed of compressed scrap metal strip. The compressing step is performed by rolls  44 ,  45  without interrupting the downstream movement of continuous stream  56  along processing path  41 . Compression rolls  44 ,  45  may be provided with studs or projections to facilitate engagement with the stream of scrap metal strip (see Nijkerk, p. 94, FIG. V-11-3; p 98, FIG. V-11-5; and p. 106, FIG. V-11-9b). 
   Rolls  44 ,  45  rotate in a downstream direction (arrows  58 ,  59 ) as the rolls form slab  57 . This urges slab  57  to move downstream toward traveling shear  47  which cuts slab  57  into a plurality of slab portions  60  each composed of compressed scrap metal strip. Shear  47  is mounted for reciprocating movement alongside of and at the same speed as slab  57 . Shear  47  moves initially downstream and then upstream, as indicated by arrow  55 , and this enables the shear to perform the cutting step without interrupting the downstream movement of slab  57 . 
   As shown in  FIG. 1   b , the continuous stream  56  of scrap metal strip forms a vertical column in charging chamber  53 . In accordance with the present invention, the vertical column of scrap metal strip has a depth and a mass sufficient to exert a substantial vertical compressive force on that part of stream  56  immediately above compression rolls  44 ,  45  and thereby substantially flatten the scrap metal strip there. There will be at least some flattening of the strip at almost every level in the column downstream of the top of the column. The extent to which the strip is flattened at a given level in the column depends upon the depth and mass of the column above that level. The greater the depth of the column above the strip at a given level, the more the strip at that level is flattened by the column above it. For example, in a column 20-25 ft. high (600-750 cm) there will be more flattening at the bottom of that column than in a column 10 ft. (300 cm) high. 
   Referring now to  FIGS. 1   a ,  2  and  4 , chamber  53  has a plurality of vertical walls  62 - 65  joined together at concavely curved junctions  70 ,  70  ( FIGS. 2 and 4 ) to minimize the possibility of a hang-up on the part of stream  56  as the stream descends through chamber  53 . If vertical chamber walls  62 - 65  were joined at sharp corners instead of at curved junctions  70 ,  70 , the possibility of a hang-up would be increased. 
   As shown in  FIGS. 1   a  and  5 , open upper end  54  on chamber  53  is defined by a plurality of connected wall portions  67 ,  67  each of which flares outwardly along a convex curve and terminates in a downwardly depending flange  68 . This arrangement minimizes the possibility of a hang-up on the part of the scrap metal strip as the strip is received through open upper end  54 . If the chamber&#39;s open upper end  54  were defined by the terminal upper edges of vertical walls instead of by convexly curved wall portions terminating at downwardly depending flanges, the possibility of a hang-up at open upper end  54  would be increased. 
   Referring to  FIGS. 1   a  and  1   b , chamber walls  62 ,  63  each terminate at a respective lower edge  72 ,  73  located slightly above the surface of a respective compression roll  44 ,  45  to provide clearance for the roll to rotate. As shown in  FIG. 1   b , each lower edge  72 ,  73  is disposed at a location slightly inward of the highest point  76  on the surface of a corresponding roll so as to direct scrap metal strip at the outer margins  74 ,  75  of stream  56  toward that part of a roll surface that is curved inwardly and downwardly. 
   Each roll  44 ,  45  has a pair of opposite ends  77 ,  78  ( FIG. 3 ), and each vertical chamber wall  64 ,  65  is spaced inwardly relative to a respective roll end  77 ,  78  to contain stream  56  inwardly of the roll ends. Each chamber wall  64 ,  65  has a lower depending portion  66  ( FIGS. 1   a ,  3  and  6 ) which is disposed between rolls  44 ,  45 . Each depending portion  66  has a pair of side edges  80 ,  81  ( FIG. 3 ) each of which follows the contour of a respective roll  44 ,  45  and is spaced a slight distance from the surface of the adjacent roll to provide a clearance for rotation of the roll. Each depending wall portion  66  terminates at a lower edge  79  disposed at the narrowest gap between rolls  44 ,  45 , adjacent a respective pair of corresponding roll ends  77 ,  77  ( FIG. 3 ) or  78 ,  78 . The depending portions  66 ,  66  act to contain the strip in stream  56  from spilling out at the ends of the rolls when the stream undergoes compression in a horizontal direction between the rolls. More particularly, the depending portions prevent spill-out in a horizontal direction transverse to the horizontal direction of compression. 
   As noted above, the scrap metal strip moves as a continuous stream  56  downstream along a vertically disposed path  41  toward a compression location at rolls  44 ,  45 . The compression location is relatively remote from the upstream open end  54  through which strip is introduced. This should minimize, if not eliminate, the problems associated with overhanging strip parts (i.e., the excess scrap metal strip), problems which occur at the opening to the horizontally disposed chamber of a batch baling apparatus when a discrete volume of scrap metal strip is deposited there. 
   More particularly, to the extent that a strip part may occasionally initially overhang upstream open end  54 , this strip part is typically connected to another strip part that is inside chamber  53 . It is projected that the overhanging strip part will be pulled through open end  54  and into chamber  53  by the strip part that is inside chamber  53  and to which the overhanging strip part is connected. The inside strip part descends along vertical processing path  41 , with the rest of continuous stream  56 , under the urging of gravity and under the further downward urging, from above, by those portions of continuous stream  56  which are subsequently introduced on top of the aforementioned inside strip part. The aforementioned inside strip part may also be entangled with other strips in the descending stream inside chamber  53 , and this further assists in the downward pull on the overhanging strip part. An overhanging strip part pulled into the chamber in this manner should then merge into continuous stream  56  with subsequently introduced portions of the stream. 
   Even if an overhanging strip part remains at upstream open end  54  of chamber  53 , the overhanging strip part should not interfere with the downstream processing operations because upstream open end  54  is relatively remote from the downstream locations where the compressing and shearing operations are performed. It should be unnecessary to interrupt either (a) introduction of scrap metal strip through entrance  54  or (b) any other processing of the strip in order to remove any overhanging strip parts which remain at the upstream open end. Removal of such strip parts can be deferred until apparatus  40  is shut down at the end of a work shift, or the like. 
   Referring again to  FIGS. 1   a  and  1   b , chamber  53 , as noted above, is vertically disposed, and it has a uniform cross-section along substantially the totality of its vertical dimension upstream from compression rolls  44 ,  45 . The stream  56  of scrap metal strip has a continuous succession of adjacent, horizontally disposed stream parts extending upstream from the compression rolls. Each of these horizontally disposed stream parts has a uniform cross-section because the cross-section of each such stream part is defined by the cross-section of chamber  53  which, as noted above, is uniform along substantially its entire vertical dimension. The net result of all this is that, as stream  56  moves downstream toward compression rolls  44 ,  45 , the compression rolls are presented with a succession of adjacent stream parts each having the same cross-section, and this enhances the uniformity of continuous slab  57  produced by compression rolls  44 ,  45 . 
   Referring to  FIGS. 9 ,  10  and  13 , disposed along the processing path between compression rolls  44 ,  45  and traveling shear  47  is a guide chute  46  having an upper portion  52  that flares outwardly to receive slab  57  as the slab descends downstream from rolls  44 ,  45 . Guide chute  46  directs slab  57  toward shear  47 . In the embodiment of  FIG. 9 , chute  46  has a depending flange  61  to help contain the slab as it moves downstream toward shear blade  48  and its holder  50 . In the embodiment of  FIG. 10 , there is a freely rotating roller  69  which contains slab  57  as the slab moves downstream from chute  46 . Roller  69  travels with shear  47 . 
   Referring to  FIGS. 10-12 , traveling shear  47  includes an active shear blade  48  and a passive shear blade  49 . Active shear blade  48  and its holder  50  are mounted for reciprocal movement in a horizontal or first direction between a retracted position shown in  FIG. 10  and an extended position shown in  FIG. 11 . As shear blade  48  moves from its retracted position to its extended position, slab  57  is engaged between the two shear blades  48 ,  49 , and a slab portion  60  is severed from slab  57 . 
   Both shear blades  48 ,  49  and their respective holders  50 ,  51  are mounted for reciprocal movement together along the processing path, in a vertical or second direction, transverse to the first or horizontal cutting direction of the shear blades. Vertical movement of the shear blades occurs between an upper first position ( FIG. 10 ) and a lower second position ( FIG. 12 ). Downstream movement of shear blades  48 ,  49  is synchronized with the downstream movement of slab  57  ( FIG. 11 ) so that all of them move at the same speed downstream. As a result, the locus  71  of engagement between (a) slab  57  and (b) shear blades  48 ,  49  remains the same during all the movement described above. 
   After the shear blades sever slab portion  60  from slab  57  ( FIG. 11 ), active shear blade  48  and its holder  50  are returned from the extended position of  FIG. 11  to the retracted position of  FIG. 10 . During the retraction of active shear blade  48 , both shear blades and their holders continue to move vertically downward (i.e., downstream) until active shear blade  48  has been retracted to a slab-clearing position ( FIG. 12 ). In this position, blade  48  no longer protrudes into the path of slab  57  which has continued to move downstream along the processing path while the shear blades have been undergoing the movement illustrated in  FIGS. 10-12  and described above. 
   After active shear blade  48  has been retracted to the slab-clearing position shown in  FIG. 12 , both shear blades  48 ,  49  and their respective holders  50 ,  51  are returned vertically upwardly (upstream) to the upper first position shown in  FIG. 10 . 
   At start-up, chamber  53  is charged with scrap metal strip until the chamber contains a substantial amount of material, e.g., at least 25% full, preferably 50-75% full (or more in some cases). Compression rolls  44 ,  45  are inactive during the initial charging period at start-up. Active shear blade  48  and its holder  50  may be manually controlled to locate them in their extended positions ( FIG. 11 ) where they form a barrier to prevent scrap metal strip, which may have fallen through the gap between inactive rolls  44 ,  45 , from descending further. When rolls  44 , 45  are activated to perform their compression function, shear blade  48  and its holder  50  can be manually controlled to return them to their retracted positions ( FIG. 10 ), and they then function in accordance with their normal operation ( FIGS. 10-12 ). 
   Up to this stage of the process, apparatus  40  has functioned, in effect, as a continuous logger/shear, and slab portion  60  may be utilized in a manner similar to the uses to which scrap metal processors put logs made by a conventional logger/shear. Alternatively, slab portion  60  may be subjected to further processing in accordance with the present invention, as described below. 
     FIGS. 14-16  illustrate an embodiment of the invention in which slab portion  60  is subjected to additional compression after the slab portion is severed from slab  57  ( FIG. 11 ). 
   Located downstream of traveling shear  47 , below the shear, are a second pair of compression rolls  84 ,  85 . Located between traveling shear  47  and the second pair of compression rolls  84 ,  85  is a guide chute  82  having an outwardly flared upper portion  83  for directing a slab portion  60  into chute  82  which in turn directs slab portion  60  downwardly between compression rolls  84 ,  85  under the urging of gravity. Rolls  84 ,  85  further compress the scrap metal strip in slab portion  60  to increase the density of the slab portion. The second pair of compression rolls  84 ,  85  are axially disposed to compress the scrap metal strip in the same horizontal direction as the compression direction at the first pair of compression rolls  44 ,  45  (see  FIG. 1   b ). 
   Guide chute  82  has a pair of opposite ends  87 ,  88  ( FIG. 16 ) from each of which depends a lower containment portion  86  having opposite edges curved to follow the contours of rolls  84 ,  85  between which each containment portion  86  is disposed. Containment portions  86 ,  86  perform the same containment function at rolls  84 ,  85  as that performed at rolls  44 ,  45  by containment portions  66 ,  66  on chamber  53  (see  FIGS. 1   a ,  1   b ,  3  and  6 ). 
   As noted above, compression rolls  84 ,  85 , located downstream of traveling shear  47 , are axially disposed to compress the scrap metal strip in slab portion  60  in the same horizontal direction as the compression direction at compression rolls  44 ,  45  located upstream of traveling shear  47 . In a variation of this embodiment, the compression rolls located downstream of the traveling shear are axially disposed to compress the scrap metal strip in a horizontal direction transverse to the compression direction at compression rolls  44 ,  45  located upstream of the traveling shear. 
   In another variation of the embodiment of  FIG. 14 , there are two pairs of compression rolls located downstream of traveling shear  47 , with one of the two downstream pairs being located downstream of the other pair. Each pair of downstream compression rolls is axially disposed transversely to the other pair. One pair of downstream compression rolls compresses the scrap metal strip in the same horizontal direction as the compression direction at upstream compression rolls  44 ,  45 , and the other pair of downstream compression rolls compresses the scrap metal strip in a horizontal direction transverse to the compression direction at upstream compression rolls  44 ,  45 . 
   An arrangement employing two pairs of compression rolls, with each pair axially disposed transversely to the other pair, is illustrated and discussed, in another context, below in connection with  FIGS. 27-28 . 
     FIGS. 7-8  illustrate an embodiment of the present invention wherein slab  57  is subjected to further compression upstream of traveling shear  47 . 
   Located downstream of compression rolls  44 ,  45 , along the processing path, are an additional pair of compression rolls  94 ,  95 . As noted above, as continuous slab  57  leaves upstream compression rolls  44 ,  45 , the slab is moved or urged downstream by the rotation of upstream compression rolls  44 ,  45 . Located between downstream compression rolls  94 ,  95  and upstream compression rolls  44 ,  45  is a guide chute  91  having an outwardly flared upper portion  92  for directing continuous slab  57  into chute  91  which in turn directs slab  57  downwardly between compression rolls  94 ,  95 . Rolls  94 ,  95  further compress the scrap metal strip in slab  57  to increase the density of the slab. Rolls  94 ,  95  are axially disposed to compress the scrap metal strip in the same horizontal direction as the compression direction at the upstream pair of compression rolls  44 ,  45 . 
   Guide chute  91 , like guide chute  82  ( FIGS. 14-16 ) has a pair of opposite ends, only one of which is shown, at  90  in  FIG. 8 . Depending from each chute end (e.g.  90 ) is a lower containment portion  93  (shown in  FIG. 8 , only). Each containment portion  93  has opposed edges curved to follow the contours of rolls  94 ,  95  between which each containment portion  93  is disposed. Each containment portion  93 , depending from chute  91 , performs the same containment function at rolls  94 ,  95  as that performed at rolls  84 ,  85  by containment portions  86 ,  86  depending from chute  82  (see  FIGS. 14-16 ). 
   As noted above, compression rolls  94 ,  95 , located downstream of compression rolls  44 ,  45 , are axially disposed to compress the scrap metal strip in slab  57  in the same horizontal direction as the compression direction at upstream compression rolls  44 ,  45 . In a variation of this embodiment, the downstream compression rolls  94 ,  95  may be axially disposed to compress the scrap metal strip in a horizontal direction transverse to the compression direction at upstream compression rolls  44 ,  45 . As noted above, an arrangement employing two pairs of compression rolls, with each pair axially disposed transversely to the other pair, is illustrated and discussed, in another context, below in connection with  FIGS. 27-28 . 
   After slab  57  is further compressed at compression rolls  94 ,  95 , the slab leaves the rolls and is urged downstream by the rotation of compression rolls  94 ,  95 . The downstream moving slab is then directed toward traveling shear  47  by a guide chute similar to that shown at  46  in  FIGS. 9 ,  10  and  13 . 
   In the embodiment of  FIG. 7 , slab  57  undergoes compression at two pairs of compression rolls ( 44 ,  45  and  94 ,  95 ) before the slab is sheared. Slab  57 , in the embodiment of  FIG. 7 , is denser at the time the slab undergoes shearing than is slab  57  in the embodiment of  FIG. 1   b  wherein the slab undergoes compression at only one pair of compression rolls ( 44 ,  45 ) before the slab is sheared. The greater the density of the slab, the more powerful the shearing force required to cut the slab into slab portions  60  ( FIGS. 1   b  and  11 ). An advantage resides in the embodiment of  FIG. 14 , where the second compression occurs after slab portion  60  has been severed from slab  57 . Compared to the slab of  FIG. 7 , the slab of  FIG. 14  is less dense at the time it undergoes shearing so that a less powerful shearing force (i.e., a smaller, less expensive shear  47 ) is required. 
   As noted above, horizontally disposed, traveling shear  47  is a guillotine shear. Examples of vertically disposed guillotine shears are shown and described in Nijkerk at pp. 53-64, (although none are traveling shears). Note, for example the vertical guillotine shears shown in Nijkerk at p. 55, FIG. V-6-10 (mobile shear), at p. 56, FIG. V-6-14a (shear at logger) or at p. 58, FIG. V-6-15 (mobile shear). 
   An embodiment of a mounting arrangement for a horizontally disposed, traveling guillotine shear is illustrated in  FIGS. 17-18 . Shear blades  48 ,  49  and their corresponding blade holders  50 ,  51  are mounted on a traveling frame indicated generally at  100  in  FIG. 17 . As viewed in  FIG. 17 , frame  100  includes left and right vertical members  101 ,  102 , respectively, and these are connected by respective front and back bottom members  103 ,  104  and respective front and back top members  105 ,  106 . 
   Mounted on the movable frame&#39;s left vertical member  101  are a pair of freely rotating wheels or rollers  108 ,  109  which ride along the vertical surface  118  of a left vertical stationary member  113  mounted on a base  114 . Mounted on the movable frame&#39;s right vertical member  102  are a pair of freely rotating wheels or rollers  110 ,  111  which ride along the vertical surface  119  of a right vertical stationary member  115  mounted on a base  116 . Wheels  108 ,  109  and  110 ,  111  may ride along vertical channels or rails in lieu of vertical surfaces  118 ,  119 . Wheels  108 ,  109  and  110 ,  111  mount frame  100  for vertical movement. 
   Holder  51  for passive shear blade  49  is fixed on left vertical frame member  101 . Holder  50  for active shear blade  48  is carried on a carriage  112  from which depends a freely rotating roller (or wheels)  117  which rides along a base member  121  supported by the frame&#39;s front and back bottom members  103 ,  104 . The wheels at  117  mount carriage  112 , blade holder  50  and shear blade  48  for back and forth movement along base member  121  which supports the weight of the carriage, the blade holder and the shear blade as they undergo back and forth movement. 
   Mounted on right vertical frame member  102  are one or more hydraulic cylinders  123  each containing a reciprocating piston connected to a piston rod  124  extending outwardly from cylinder  123  and having an outer end connected to carriage  112  for moving the carriage with blade holder  50  and shear blade  48  back and forth between positions corresponding to the shear blade&#39;s retracted position ( FIG. 10 ) and its extended position ( FIG. 11 ). 
   Depending from front and back top frame members  105 ,  106  are a pair of vertically disposed members, only one of which is shown at  125  in  FIG. 17 . Mounted between vertical members  125 ,  125  is freely rotating guide roller  69  (see  FIGS. 10-12 ). Extending between each vertically disposed member  125  and the frame&#39;s right vertical member  102  is a horizontally disposed brace member  126 . 
   Everything mounted on frame  100  is vertically moveable with frame  100  which, as noted above, carries wheels  108 ,  109  and  110 ,  111  which ride along vertical surfaces  118 ,  119  to mount frame  100  for reciprocal vertical movement between (i) a position corresponding to the upper position of shear blades  48 ,  49  and holders  50 ,  51  shown in  FIG. 10  and (ii) a position corresponding to the lower position of the shear blades and their holders, discussed above in connection with  FIGS. 11 and 12 . One embodiment of equipment for producing the vertical movement of frame  100  will now be described. 
   Attached to the top of frame  100 , e.g. at one or both of top frame members  105 ,  106 , is an end  127  of at least one cable  129 . Each cable  129  is trained over a respective pulley  130  mounted on compression apparatus  40  externally of frame  100 . The cable has a terminal end  128  attached to a counterweight  132 . The mass of counterweight  132  (or the mass of a plurality of such counterweights, if that be the case) exceeds the total mass of frame  100  and the load carried by frame  100 . Accordingly, counterweight  132  normally urges frame  100  and its load to an upper position determined by a stop  133  extending horizontally toward frame  100  from right vertical external member  115 . Stop  133  engages the top of frame  100  to determine the upper position of frame  100 , a position that determines the upper position of shear blades  48 ,  49  and blade holders  50 ,  51 , shown in  FIG. 10 . Frame  100  and its load are moved from their upper position to their lower position by the equipment described in the following paragraph. 
   Attached to the bottom of frame  100  is one end  134  of a cable  136  trained around a rotatably mounted cable drum  137  and having a terminal cable end  135  fixed to cable drum  137 . Cable drum  137  is mounted on compression apparatus  40  externally of frame  100 . Cable drum  137  is drivably connected at  141  to one side  138  of a magnetic clutch having another side  139  drivably connected at  142  to an electric motor  140 . Drivable connection  142 , clutch  138 ,  139 , drivable connection  141 , cable drum  137  and cable  136 , in that sequence, link motor  140  to frame  100 . When motor  100  is operated, and magnetic clutch  138 ,  139  is engaged, cable  136  is wound up around cable drum  137 , and frame  100  and its load are moved in a downward direction, against the urging of counterweight  132 . 
   Motor  140  need have a horsepower only as large as is necessary to move the difference in mass between (a) counterweight  132  and (b) frame  100  and its load. The smaller the difference in mass, the less horsepower required of motor  140 . 
   When motor  140  is unlinked from frame  100 , e.g., by disengaging magnetic clutch  138 ,  139 , counterweight  132  urges frame  100  and its load in an upward direction, unwinding cable  136  from drum  137 , until frame  100  engages stop  133 . No motor is required to raise frame  100  and its load. That function is performed by counterweight  132 . The only motor required is frame-lowering motor  140 , and it is assisted in the performance of its function by the mass of frame  100  and its load. Frame-lowering motor  140  has a horsepower substantially less than the horsepower that would be required of a motor for raising frame  100  and its load in the absence of counterweight  132 . 
   One embodiment of a system for controlling (a) the horizontal movements of shear blade  48  and (b) the vertical movements of frame  100  and its load are illustrated in the block diagram of  FIG. 19  taken in conjunction with  FIG. 17 . 
   Hydraulic cylinder  123  ( FIG. 17 ) is part of a hydraulic system  147  actuated by a light-sensitive switch  145  mounted on frame  100  at a location alongside the downward path of movement of slab  57  ( FIG. 17 ). When the bottom or leading end  157  of slab  57  descends to the level of light sensitive switch  145 , the switch actuates hydraulic mechanism  147  causing hydraulic piston rod  124  to move carriage  112 , blade holder  50  and active shear blade  48  horizontally from (i) a position corresponding to the retracted position of the shear blade ( FIGS. 10 and 17 ) toward (ii) a position corresponding to the extended position of active shear blade  48  ( FIG. 11 ). 
   The horizontal movement described in the previous sentence is sensed by another light-sensitive switch  146  mounted on frame  100  below blade holder  50 . Switch  146  connects a power source  148  to (a) the electromagnet on magnetic clutch  138 ,  139  and to (b) electric motor  140  via a current regulator  152 . When switch  146  senses the start of horizontal shearing movement by active shear blade  48 , the switch closes to deliver electric current to magnetic clutch  138 ,  139  and to electric motor  140 , actuating the motor and the clutch and winding up cable  136  on cable drum  137  to pull frame  100  and its load downwardly. 
   The downward movement of shear blades  48 ,  49  is synchronized with the downward movement of slab  57  so that the slab and the shear blades move downwardly at the same speed. This is accomplished in the following manner, with reference to  FIG. 19 . 
   Electric motor  140  is a variable speed motor, the speed of which is controlled by the current delivered to motor  140  by current regulator  152 . A sensor  149  senses the downward speed of slab  57 , and another sensor  150  senses the downward speed of shear blade  48  or  49 . Both speed sensors  149 ,  150  are mounted on apparatus  40  externally of vertically movable frame  47 . Information on the speeds sensed by sensors  149 ,  150  are transmitted to a controller  151  where the speeds are compared. If an adjustment in the downward speed of shear blades  48 ,  49  is necessary to better synchronize the downward movement of the shear blades with the downward movement of slab  57 , this is accomplished by controller  151  which is adjustably linked at  153  to current regulator  152 . Controller  151  adjusts current regulator  152  so that the current flowing to variable speed motor  140 , via current regulator  152 , produces a motor speed that conforms the speed of downward movement of frame  100  and its load (including shear blades  48 ,  49 ) to the speed of downward movement of slab  57 . Any change in the speed of downward movement of slab  57  will be reflected by an adjustment in the speed of variable speed motor  140 . 
   When active shear blade  48  reaches its extended position ( FIG. 11 ), at which slab portion  60  is severed from slab  57 , a mechanical contact switch or the like (not shown) on frame  100  is engaged, e.g., by blade holder  50 , and this actuates hydraulic mechanism  147  ( FIG. 19 ) to retract the piston in hydraulic cylinder  123 , in turn retracting shear blade  48  and its holder  50  from their extended position ( FIG. 11 ) back toward the retracted position of  FIG. 10 . While this is occurring, motor  140  continues to operate, causing frame  100  and its load to continue their downward movement. 
   When active shear blade  48  and its holder  50  have returned to their retracted position ( FIGS. 10 and 17 ), this is sensed by light-sensitive switch  146  which shuts off the flow of current from power source  148  to electric motor  140  and magnetic clutch  138 ,  139 . This decouples or unlinks electric motor  140  from frame  100  and its load, allowing counterweight  132  to raise frame  100  and its load until the top of the frame engages stop member  133 . 
   In lieu of the speed control system for the vertically traveling shear described above ( FIG. 19 ), one may employ a speed control system akin to those utilized in conventional traveling shears that move along a horizontal path. In another variation, motor  140  and clutch  138 ,  139  may be drivingly connected to one or more of rollers  108 ,  109  or  110 ,  111 , and cable drum  137  and cable  136  may be eliminated. 
   Referring again to  FIG. 17 , slab  57  continues to descend while frame  100  and its load are raised by counterweight  132  (also see  FIG. 12 ). The severance of slab portion  60  from slab  57  ( FIG. 11 ) exposes a new slab bottom end  157 , and when the new slab bottom end has descended to a level where the slab is sensed by light sensitive switch  145 , there is a repeat of the entire cycle of operations described above. 
   The dimensions, in a downstream direction, of a severed slab portion  60  can be adjusted by adjusting the level of light sensitive switch  145  on frame  100 . The higher the level of switch  145  on frame  100 , the sooner the start of the shearing movement by active shear blade  48 , and therefore the smaller the dimension, in a downstream direction, of a slab portion  60 . 
   In lieu of light sensitive switches  145 ,  146 , one may employ other types of switches to control hydraulic system  147  and motor  140 . For example, light sensitive switch  145  may be replaced with a mechanical contact switch placed at the same vertical level as switch  145  (in  FIG. 17 ) but disposed along the margin of the path followed by slab  57  as the slab descends, for engagement of the switch with the slab. Similarly, light sensitive switch  146  may be replaced with a mechanical contact switch vertically aligned with the location of switch  146  in  FIG. 17  but disposed along the margin of the horizontal path followed by shear blade  48  and its holder  50  as they move toward the shear blade&#39;s extended position, for engagement of the switch with shear blade holder  50 . 
   When slab  57  is unengaged by traveling shear  47 , the slab is suspended from compression rolls  44 ,  45  and a gravitational force, corresponding to the mass or weight of the suspended slab, pulls downwardly on the slab. The greater the length of the suspended slab, the greater the downward pull of the gravitational force. If the downward pull of the gravitational force exceeds the cohesive force holding the slab together, the slab can be pulled apart before the slab is engaged by traveling shear  47 . 
   One expedient, for preventing the slab from being pulled art by gravitational force, is to place traveling shear  47  at a location, close to upstream compression rolls  44 ,  45 , where the gravitational force does not exceed the cohesive force of the slab. If structural or other considerations do not allow the traveling shear to be so located, another expedient may be employed. 
   Referring to  FIG. 38 , one such expedient, for preventing the slab from being pulled apart, utilizes one or more pairs of pincher rolls  143 ,  144 , located between traveling shear  47  and the upstream compression rolls  44 ,  45 . Each pair of pincher rolls  143 ,  144  engages slab  57  between the two rolls. In each pair, one or both of the rolls may be spring loaded or hydraulically loaded to urge a roll toward the slab so as to pinch the slab between the two rolls. This is indicated representationally by the arrows  119 ,  121  in  FIG. 38 . In this way, the pair of pincher rolls supports a substantial part of the weight of the slab upstream of the pair of pincher rolls and offsets enough of the downward pull of the gravitational force on the slab to prevent the slab from being pulled apart. 
   One or both of the pincher rolls may be freely rotating; or one or both may be rotatably driven, in which case the rotational speed of the driven rolls is controlled so that the speed of descent of the slab downstream of the pincher rolls is the same as the speed of descent of the slab between (a) the upstream compression rolls  44 ,  45  and (b) the pincher rolls. 
   Referring back to  FIG. 7 , the second pair of compression rolls  94 ,  95 , located between (a) upstream compression rolls  44 ,  45  and (b) traveling shear  47 , inherently acts as a pair of pincher rolls. Accordingly, when the embodiment of  FIG. 7  is employed, rolls  94 ,  95  should be situated along path  41  at a location, relative to shear  47 , for preventing the slab from being pulled apart. In this regard, any pair of pincher rolls (e.g.,  143 ,  144  in  FIG. 38 ) can also function to further compress slab  57 , but that additional function is optional. 
   Referring again to  FIG. 14 , each slab portion  60  has a pair of sheared edges  158 ,  159  corresponding to the two locations where a given slab portion  60  had been engaged by traveling shear  47  to separate the slab portion first from a preceding, downstream slab portion  60  and then from upstream slab  57  (see  FIG. 11 ).  FIGS. 20-24  are directed to an embodiment of the present invention comprising a pair of additional compression rolls  154 ,  155  for engaging a slab portion  60  along sheared edges  158 ,  159  to further compress the scrap metal strip in the slab portion to increase the density of slab portion  60 . 
   The additional pair of compression rolls  154 ,  155  may be used in conjunction with the embodiment of  FIG. 14 , in which slab portion  60  has previously undergone two upstream compression steps, first at compression rolls  44 ,  45  ( FIG. 16 ) and then at the second pair of compression rolls  84 ,  85  ( FIG. 14 ); or, alternatively, the additional pair of compression rolls  154 ,  155  may be used immediately downstream of the shearing step ( FIG. 11 ), without employing a compression step at compression rolls  84 ,  85  ( FIG. 14 ). In either alternative, slab portion  60  descends by gravity toward a pair of spaced-apart, vertically disposed guide plates  160 ,  161  ( FIGS. 20-21 ) each having a respective upper, outwardly flared portion  162 ,  163  at the upstream end of the guide plate. 
   Guide plates  160 ,  161  direct slab portion  60  downwardly between guide plates  160 ,  161  onto a conveyor  164  which conveys slab portion  60  downstream toward the additional pair of compression rolls  154 ,  155  which are horizontally disposed and vertically spaced apart ( FIGS. 22-24 ). Guide plates  160 ,  161  maintain slab portion  60  in a vertical disposition with sheared edges  158 ,  159  positioned for engagement by lower and upper compression rolls  154 ,  155 , respectively, as slab portion  60  is delivered to the compression rolls. 
   Located immediately upstream of compression rolls  154 ,  155  are a pair of vertically disposed, spaced apart, drive rolls  166 ,  167  which engage slab portion  60  between them and propel the slab portion into engagement with compression rolls  154 ,  155 . Each drive roll  166 ,  167  may have vertically disposed surface ribs or projections  168 ,  168  ( FIG. 23 ) to facilitate the driving engagement of a drive roll with slab portion  60 . The drive rolls maintain their engagement with slab portion  60  until at least a downstream part  165  of slab portion  60  has been compressed by the compression rolls. 
   As slab portion  60  undergoes compression, the slab portion is contained between a pair of vertically disposed containment plates  169 ,  170  each having an upper edge  171  that is contoured to follow the curve of a compression roll, along the lower, upstream quadrant  156  of the compression roll ( FIG. 22 ). Upper plate edge  171  is spaced from the adjacent surface of the compression roll, providing a slight clearance to allow for rotation of the roll. 
   Conveyer  164 , guide plates  160 ,  161  and drive rolls  166 ,  167  cooperate to deliver slab portion  60  to compression rolls  154 ,  155  in a disposition that enables a compression roll  154  or  155  to engage a respective sheared edge  158  or  159 . After it is compressed at rolls  154 ,  155 , the slab portion is conveyed downstream on conveyor  172 . 
   There are some embodiments of the present invention in which the scrap metal strip is subjected to one or more mechanical precompression steps upstream of compression rolls  44 ,  45 , and these embodiments will now be described. 
   Referring to  FIGS. 25-26 , located along processing path  41 , upstream of compression rolls  44 ,  45  is a mechanical precompression device  174  in the form of a continuous tread member having a portion  175  sloping inwardly in a downstream direction. Tread-like device  174  is akin to the treads or tracks on a crawler tractor. A more detailed illustration of a tread-like precompression device is contained in Nijkerk, p. 96, FIG. V-11-3a; also see p. 88, FIG. V-11-2, item (4). Tread-like device  174  cooperates with vertical wall  62  on chamber  53  to precompress the scrap metal strip in stream  56  (shown in  FIG. 1   b ) in a horizontal direction, without interrupting the downstream movement of the strip along processing path  41  toward compression rolls  44 ,  45 . Tread-like device  174  precompresses the strip in the same direction as the compression direction at compression rolls  44 ,  45 . 
   A variation of the embodiment of  FIGS. 25-26  is shown in  FIG. 29  which illustrates an apparatus that employs two tread-like devices  174 ,  174  that precompress the scrap metal strip between devices  174 ,  174  and in the same direction as the compression direction at compression rolls  44 ,  45 . 
   Another embodiment employing mechanical precompression is shown in  FIGS. 27-28  and comprises a pair of precompression rolls  178 ,  179  located upstream of compression rolls  44 ,  45  along processing path  41 . Precompression rolls  178 ,  179  are horizontally disposed in an axial direction transverse to the axial direction in which compression rolls  44 ,  45  are disposed. Accordingly, precompression rolls  178 ,  179  precompress the scrap metal strip in a direction transverse to the compression direction at rolls  44 ,  45 . 
   A variation of the embodiment of  FIGS. 27 ,  28  is illustrated in  FIG. 30  wherein upstream precompression rolls  178 ,  179  are axially disposed in a direction parallel to the axial disposition of compression rolls  44 ,  45 . In this embodiment, rolls  178 ,  179  precompress the scrap metal strip in the same direction as the compression direction at compression rolls  44 ,  45 . 
   In addition, in the embodiment of  FIG. 30 , chamber  53  includes a pair of vertical wall portions  182 ,  183  disposed between (i) upstream precompression rolls  178 ,  179  and (ii) downstream compression rolls  44 ,  45 . Wall portions  182 ,  183  depend tangentially downstream from respective precompression rolls  178 ,  179  and guide the precompressed scrap metal strip as the strip moves downstream toward compression rolls  44 ,  45 . Each wall portion  182 ,  183  has a respective lower edge  184 ,  185  which is located and functions in a manner akin to lower edges  72 ,  73  on chamber walls  62 ,  63  in the embodiment of  FIG. 1   a.    
   Referring now to  FIG. 31 , in this embodiment there are a pair of tread-like precompression devices  174 ,  174  located upstream of the compression rolls, as in  FIG. 29 . (The graphic limitations inherent in the sectional drawing of  FIG. 31  allow for the showing of only one precompression device  174  and one compression roll, here  45 , but two of each are included in the apparatus, as in  FIG. 29 .) Located upstream of precompression devices  174 ,  174  are a pair of precompression rolls  178 ,  179  similar to those shown in  FIGS. 28 and 30 . 
   Precompression rolls  178 ,  179  precompress the scrap metal strip in a direction transverse to the compression direction at compression rolls  44 ,  45  and help feed the precompressed strip downstream toward tread-like precompression devices  174 ,  174  which further precompress the strip, in a direction the same as the compression direction at compression rolls  44 ,  45 . 
   In a variation of the embodiment of  FIG. 31 , one may reverse the locations, along processing path  41 , of (a) tread-like devices  174 ,  174  and (b) precompression rolls  178 ,  179  so that rolls  178 ,  179  are downstream of devices  174 ,  174 . 
   In all the embodiments and variations of  FIGS. 25-31 , the precompression rolls  178 ,  179  and the precompression devices  174 ,  174  precompress the scrap metal strip without interrupting the downstream movement of the strip toward compression rolls  44 ,  45 . 
   From the standpoint of compressing the scrap metal strip and urging or moving the compressed strip downstream, a pair of tread-like devices  174 ,  174  and a pair of compression rolls, such as  178 ,  179  (or  44 ,  45 ), are functional equivalents, and a pair of one may be substituted for a pair of the other. 
   When precompression is employed, the linear surface speed of compression rolls  44 ,  45  is controlled to reflect the linear speed at which the precompressed stream of scrap metal strip is delivered to the compression rolls by the upstream precompression rolls or devices. 
   The processing path is, in its most preferable form, truly vertical, i.e., straight up and down ( FIGS. 1   a - 1   b ). In a slightly broader context, the processing path can be “essentially vertical”, a term which encompasses both (i) a path that is straight up and down, i.e., true vertical, and (ii) a path that deviates from true vertical by a few degrees, so long as the features and advantages provided by a true vertical path are substantially provided by the path that deviates from true vertical. Thus, an essentially vertical path enables a continuous stream of scrap metal strip to move downstream under the urging of gravity without substantial impediment; it provides each of a succession of adjacent stream parts with a substantially uniform cross section when the stream part arrives at the compression rolls; and it enables overhanging strip parts at the upstream end of the processing path to be pulled into the charging chamber as the continuous stream of scrap metal strip descends along the processing path. 
   Other embodiments of the present invention employ the combination of compression rolls and traveling shear, in that sequence, together with a processing path which, although not essentially vertical, has a substantial vertical component. A processing path with a substantial vertical component is a path that has a downward slope steep enough to enable the stream of scrap metal strip to move downstream along the path under the urging of gravity, prior to the stream undergoing compression. Any angle that satisfies this requirement defines a path that has a substantial vertical component. Preferably, the angle or slope is at least 45° and, most preferably, at least 60°. Devices which augment gravitational descent, such as a vibrating ramp along the sloping path, may be employed (see, e.g., Nijkerk, p. 61, FIG. V-6-18b), and that path would be defined as one that has a substantial vertical component. As used herein, the term “at least a substantial vertical component” encompasses all of the following dispositions: (1) a path that has a substantial vertical component; (2) a path that is essentially vertical; and (3) a path that is truly vertical, i.e., straight up and down. 
   Examples of embodiments of the present invention having a processing path with a substantial vertical component are illustrated in  FIGS. 32-34 . 
   Referring initially to  FIG. 32 , this embodiment comprises a charging chamber  253  in which the chamber wall  263  opposite vertical wall  62  is sloped and has a substantial vertical component. The other walls of chamber  253  are like the vertical walls of chamber  53  in  FIG. 1   a . Sloped chamber wall  263  terminates at a lower edge  273  which is tangential to the surface of roll  45  at a location where the surface of roll  45  is moving downwardly and inwardly as shown by arrow  59  in  FIG. 32 . There is a slight clearance between lower edge  273  and the surface of roll  45  to allow for the rotation of roll  45 . 
   Scrap metal strip in chamber  253  moves downwardly through chamber  253  under the urging of gravity and along a processing path  241 . The scrap metal strip in that part of processing path  241  adjacent vertical wall  62  moves vertically downwardly toward compression rolls  44 ,  45 ; the scrap metal strip in that part of processing path  241  adjacent sloped wall  263  moves along a path part that has a substantial downward vertical component. Other than the differences noted in the preceding sentences in this paragraph, or implicit therein, the operation of the embodiment illustrated in  FIG. 32  is substantially the same as the operation of apparatus  40  in  FIGS. 1   a - 1   b.    
     FIG. 33  is directed to an embodiment  340  in which the entire processing path  341  has a downward slope with a substantial vertical component, from the path&#39;s upstream end through those portions of the path where the compression and shearing steps are performed. 
   In this embodiment, a stream  356  of scrap metal strip moves, under the urging of gravity, along a ramp  353  having a substantial downward vertical component. Stream  356  is contained between a pair of vertical walls (one of which is shown at  362 ) as the stream moves along ramp  353 . 
   The scrap metal strip in stream  356  is compressed by compression rolls  344 ,  345  into a slab  357  which is cut into slab portions  360  by a traveling shear  347  located immediately downstream of compression rolls  344 ,  345 . Slab  357  is supported, between the compression step and the shearing step, by a supplemental ramp  354  located between lower compression roll  344  and passive shear blade holder  351 . 
   A conventional guillotine shear employs a hydraulic clamp immediately upstream of the active shear blade (Nijkerk, p. 53, FIG. V-6-8 and p. 58, FIG. V-6-16a). The hydraulic clamp holds in place a workpiece undergoing shearing; it also counteracts the upward pressure from that part of the workpiece immediately upstream of the shear&#39;s active blade, an upward pressure which occurs as a reaction to the downward stroke of the active shear blade. Absent the hydraulic clamp, the upstream part of the workpiece would tend to curl up against the head or holder of the active shear blade (see Nijkerk p. 61, col. 1). No such hydraulic clamp is employed with shear  347  of apparatus  340 ; to the extent that the functions performed by the hydraulic clamp may be needed, it is projected that they would be performed by compression rolls  344 ,  345  alone or together with guide roller  369 . Similarly, no hydraulic clamp would be employed with shear  47  in the embodiment of the apparatus discussed above; the functions of the hydraulic clamp, if needed, would be performed by compression rolls  44 ,  45  alone ( FIG. 1   a ) or together with guide roll  69 . In this connection,  FIG. 11  shows slab  57  pressed against guide roll  69  in reaction to the completion of the cutting stroke by active shear blade  48 . 
   Referring again to  FIG. 33 , after being severed from slab  357 , a slab portion  360  falls into a guide chute  382  like guide chute  82  shown in  FIG. 14 , and as in the embodiment of  FIG. 14 , guide chute  382  directs the slab portion vertically downwardly toward a second pair of compression rolls for further compression of the scrap metal strip in slab portion  360  (see  FIG. 14  and its accompanying description). 
   As an alternative to employing the arrangement of  FIG. 14 , one may employ the arrangement illustrated in  FIG. 34  to further compress the scrap metal strip in slab portion  360 . More particularly, after being severed from slab  357 , slab portion  360  falls, or is directed (e.g. by chute  382 ), onto a second ramp  361  along which slab  360  moves, under the urging of gravity, toward a second pair of compression rolls  384 ,  385  which further compress the scrap metal strip in slab  360  and direct the slab downstream onto a third ramp  365 . In lieu of second ramp  361 , one may employ a conveyor belt and/or drive rolls, as in the embodiment of  FIGS. 22-23 , to urge slab  360  toward compression rolls  384 ,  385 . 
   In the embodiment of  FIG. 33 , traveling shear  347  is, for the most part, akin to traveling shear  47  described above. Shear  347  includes active and passive shear blades  348 ,  349  and their respective blade holders  350 ,  351  as well as a guide roller  369  akin to guide roller  69  in  FIGS. 10-12 . 
   In addition, and unlike shear  47 , shear  347  comprises a support table  352  which, with supplemental ramp  354 , helps support slab  357  before the slab is engaged by active shear blade  348 . Support table  352  moves along a reciprocating path  367  in synchronism with the movement of active shear blade  348  along its reciprocating shearing path  368 . An arrangement of the type described in the preceding sentences of this paragraph is described and shown in more detail in Nijkerk at pp. 58-59, FIGS. V-6-16a and 16b. Support table  352  also moves upstream and downstream along the same reciprocating travel path  355  as the other components of traveling shear  347 . 
   Shear  347  is moved back and forth, downstream and upstream, along its travel path  355  by an arrangement similar to that employed for traveling shear  47  (see  FIGS. 17-19 ). The corresponding arrangement for traveling shear  347  is shown diagrammatically in  FIG. 35 . 
   Traveling shear  347  (shown in block diagram in  FIG. 35 ) has a base  358  supported by a plurality of wheels or rollers  370 ,  371  which ride on a plurality of rails, one of which is shown at  366 . The rails are disposed at the same slope as ramps  353  and  354  ( FIG. 33 ). Attached to the upstream end of traveling shear  347  at base  358  is a cable  329  which extends around a pulley  330  and terminates at a counterweight  332 . Attached to the downstream end of traveling shear  347  is a cable  336  which terminates at a cable drum  337  driven by an electric motor (not shown). 
   The operation of traveling shear  347  and the components thereof, described in the preceding paragraph, is essentially the same as the operation of traveling shear  47 , described above in connection with  FIGS. 17-19 . 
   Although the embodiment of  FIG. 33  may not provide all the features and advantages provided by the embodiments that employ an essentially vertical processing path (e.g.  FIGS. 1   a - 1   b ), the embodiment of  FIG. 33  does have the advantage of providing a process that is continuous. Moreover, although self-precompression of the strip, provided by embodiments that employ a vertical column of material ( FIGS. 1   a - 1   b ), is not available with the embodiments of  FIG. 33 , precompression upstream of compression rolls  344 ,  345  can be otherwise provided. For example, apparatus  340  may include, upstream of the compression rolls, another set of compression rolls or a tread-like precompression member, or both (e.g., see Nijkerk, p. 96, FIG. V-11-3a and p. 98, FIG. V-11-5, showing such devices positioned along a downwardly inclined processing path). 
     FIGS. 36 and 37  illustrate a variation of apparatus  340  ( FIG. 33 ) comprising a pair of precompression rolls  368 ,  369  located upstream of compression rolls  344 ,  345  along processing path  341 . Precompression rolls  368 ,  369  have an axial disposition transverse to the axial disposition of compression rolls  344 ,  345 . Accordingly, precompression rolls  368 ,  369  precompress the scrap metal strip in a direction transverse to the compression direction at rolls  344 ,  345 ; and rolls  368 ,  369  urge the precompressed scrap in a downstream direction. 
     FIG. 37  shows both containment walls  362 ,  363  of apparatus  340 . In the variation of apparatus  340  shown in  FIG. 33 , each containment wall (e.g.,  362 ) terminates at a respective compression roll (e.g.,  344 ). In the variation shown in  FIGS. 36 ,  37  each containment wall  362 ,  363  terminates at a respective precompression roll  368 ,  369 . There is another pair of containment walls  364 ,  364  each extending between a respective precompression roll  368 ,  369  and a respective compression roll  344 ,  345 . 
   Containment walls  362 ,  363  have respective downstream edges  372 ,  373  each spaced a short distance from the surface of an adjacent roll  368 ,  369  to provide a clearance for the roll to rotate. Containment walls  362 ,  363  direct scrap metal strip, moving downstream along processing path  341 , toward that part of a roll surface that is rotating in a direction having a downstream component (arrows  378 ,  379  in  FIG. 37 ). 
   Each containment wall  364  has an upstream edge  375  spaced a short distance from the surface of a respective precompression roll  368 ,  369  to provide a clearance for the roll to rotate. As shown in  FIG. 37 , each containment wall  364  extends tangentially downstream from a respective precompression roll  368 ,  369 . Walls  364 ,  364  guide the precompressed scrap metal strip as the strip moves downstream toward compression rolls  344 ,  345 . 
   Each wall  364  has an edge  380  which follows the contour of upper compression roll  344  and is spaced a short distance from the surface of the roll to provide a clearance for the roll to rotate. Each wall  364  is disposed adjacent a respective roll end  382 ,  383  ( FIG. 37 ). Each wall  364  has a downstream portion  384  terminating at an edge  381  disposed at the narrowest gap between rolls  344 ,  345 . Downstream wall portions  384 ,  384  function like depending portions  66 ,  66  in apparatus  40  ( FIGS. 3 and 6 ). 
   Referring again to precompression rolls  368 ,  369 , disposed between these rolls, adjacent an upper portion of the rolls, is an upper containment plate  374  having a pair of opposed side edges  385 ,  386  ( FIG. 37 ) each of which follows the contour of a respective precompression roll  368 ,  369 , with a slight clearance to allow for rotation of the rolls. Containment plate  374  is preferably slightly convexly curved in a downward and downstream direction ( FIG. 36 ) and terminates at a downstream edge  387  located at the narrowest gap between precompression rolls  368 ,  369  ( FIG. 37 ). 
   The precompressed scrap metal strip moving downstream from precompression rolls  368 ,  369  has a volume defined in part by the narrowest gap between rolls  368 ,  369  and in part by a dimension extending transversely to the direction of processing path  341 . Upper containment plate  374  puts a maximum limit on that dimension. The maximum limit can be adjusted by adjusting the distance between plate  374  and ramp  353 . 
   With reference to  FIGS. 1   b  and  33 , one may employ a semi-continuous version of the present invention in which the shear (e.g.  47  in  FIG. 1   b  or  347  in  FIG. 33 ) does not travel. Instead, the shear is stationary, and rotation of the compression rolls (e.g.,  44 ,  45  or  344 ,  345 ), which feed the slab to the shear, is interrupted long enough to enable the stationary shear to cut a slab portion ( 60  or  360 ) from the stationary slab. Rotation of the compression rolls is interrupted when the slab is at a predetermined position, relative to the shear, for cutting from the slab a slab portion having the desired dimension in a downstream direction. The non-rotating compression rolls clamp the slab between them and prevent the slab, and the scrap metal strip upstream of the slab, from descending downstream during the cutting operation. Because the slab is restrained against downstream movement by the clamping action of the compression rolls, there is no need to block the path of movement downstream of the shear while a slab portion is being cut from the slab by the shear. After a slab portion has been severed from the slab, rotation of the compression rolls is resumed to again move the slab downstream. As noted above, the shear does not travel downstream and upstream along the processing path, and the components for enabling the shear to do so are excluded from this version of the apparatus. Otherwise the apparatus and processing steps are essentially the same as in the fully continuous embodiments described above. The interruption and resumption of rotation of the compression rolls can be controlled manually with an on-off switch for activating a magnetic clutch that links the compression rolls to a motor that drives the compression rolls (like magnetic clutch  138 ,  139  and associated elements in  FIGS. 17 and 19 ); or the on-off functions may be performed automatically using a light-sensitive switch that is actuated by movement of the shear&#39;s active blade and holder (e.g., like light sensitive switch  146  in  FIGS. 17 and 19 ). 
   Referring again to  FIG. 1   a , scrap metal strip may be delivered to chamber entrance  54  at the upstream end  42  of processing path  41  with conventional delivery equipment heretofore utilized in conjunction with other types of scrap metal processing apparatuses. Such equipment includes a grapple or an electromagnet mounted at the end of a boom on a hydraulic or mechanical crane (Nijkerk: pp. 155-163). The crane can be mobile or it can be stationary, e.g. mounted atop a pedestal located adjacent apparatus  40  in  FIG. 1   a . One can also deliver scrap metal strip to the open upper end or entrance  54  of vertical chamber  53  with a steel-belted conveyor akin to that employed to deliver obsolete scrap to the upstream end of a shredder (e.g., see Nijkerk, p. 95 and p. 113, FIG. V-11-12 and FIG. V-11 at p. 86). Delivery equipment, similar to that described above in connection with the embodiment of  FIG. 1   a , may also be employed with the embodiments of the other Figures. 
   When a conveyor is employed to deliver the scrap metal strip to the apparatus, the strip can be continuously introduced through entrance  54  of chamber  53  at the upstream end of processing path  41 . When a grapple or electromagnet is employed to perform the delivery operation, introduction of scrap metal strip through entrance  54  can only be substantially continuous because there will be short periods of time, between successive discharges of scrap from a grapple or electromagnet into the entrance, during which the grapple or electromagnet is being reloaded; and there will be no introduction of scrap metal strip through the entrance during reloading. 
     FIG. 1   b  is a side view showing the thickness of slab  57  and slab portion  60 . The length or longest dimension of slab portion  60  is shown in  FIG. 22  and corresponds to the width of continuous slab  57 . If this dimension is considered to be too large, slab portion  60  can be cut into smaller parts, e.g., cut in half lengthwise, using a conventional, stationary, guillotine shear. One arrangement for doing so is shown in  FIG. 39 . 
   A slab portion  60  leaving downstream compression rolls  84 ,  85  (or leaving third pair of compression rolls  154 ,  155  ( FIG. 22 ), as the case may be) is directed by appropriate guide elements (not shown) onto a conveyor  171  which transports the slab portion downstream. Conveyor  171  is operated at a speed substantially greater than the speed at which slab portion  60  was moving at the compression rolls preceding conveyor  171 . The effect of this speed differential is to cause the slab portions  60 ,  60 , transported on conveyor  171 , to be spaced relatively far apart from each other compared to the spacing upstream of conveyor  171 . 
   Conveyor  171  delivers a slab portion  60  to a pair of vertically spaced drive rolls  176 ,  177  located immediately upstream of stationary guillotine shear  247 . Drive rolls  176 ,  177  are similar to drive rolls  166 ,  167  described above in connection with the discussion of  FIGS. 22 ,  23 . Drive rolls  176 ,  177  grip slab portion  60  and move the slab portion downstream to a position at which the slab portion can be cut by shear  247 . While the slab portion is being cut by shear  247 , drive rolls  166 ,  167  are at rest (not rotating), and they clamp shear portion  60  between them. Active shear blade  48  and its holder  50  move downwardly during the shearing operation ( FIG. 39 ). After a downstream part  180  of slab portion  60  has been severed by the shear, active shear blade  48  and its holder  50  are returned to their upper, retracted positions, and drive rolls  176 ,  177  are activated to propel the upstream part  181  of slab portion  60  downstream past the location of shear  247 . Simultaneously, conveyor  171 , which was at rest during the shearing operation, delivers a new slab portion  60  to drive rolls  176 ,  177 , and the sequence of operations described above is repeated. 
   If upstream part  181  has not cleared shear  247  under the momentum imparted to it by drive rolls  176 ,  177 , it is bumped clear of the shear by a succeeding slab portion  60  as the latter is moved by drive rolls  176 ,  177  into a position for cutting by shear  247 . 
   One will note from the foregoing description that the method described therein processes scrap metal strip into a plurality of individual packages of uncontained compressed material (the aforementioned slab portion). One will also note that absent from the method described herein is the trimming of excess scrap metal strip before compression or during performance of the method, the need for which is eliminated by the method described herein. 
   The method and apparatus of the present invention have been discussed above principally in the context of compressing scrap metal strip generated as a by-product of manufacturing operations. However, the invention can also be used on any of the scrap metal materials heretofore processed in commercial scrap baling operations, whether the material be ferrous or non-ferrous or industrial scrap or obsolete scrap, and the term “scrap metal strip” as used herein, encompasses, in its broadest sense, all of these materials. 
   The foregoing detailed description is a projection; it has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.