Multi-sided shaft for a crusher

A shredder, crusher, hammer mill, ring mill or the like is provided with a multi-sided rotor shaft to which spider arms and hammers are mounted. The rotor shaft has at least one pair, and preferably two or more pairs, of opposing sides. The hammers are pivotally mounted between spider arms. The spider arms have bases which include openings. The spider arm base openings have straight sides corresponding to the number of straight sides on the rotor shaft. The spider arm straight sides engage the rotor shaft straight sides. Hence, the spider arms are rotationally fixed in place relative to the rotor shaft without the use of keys and keyways, pins, bolts, or other types of fasteners, allowing for easier assembly and reduced maintenance costs for the crusher.

BACKGROUND OF THE INVENTION

Crushers, shredders, hammer mills, ring mills, and the like, are often used to process scrap material and stone, to crush or reduce the size of the material so that it can more easily be handled by other equipment for further processing or use.

Such crushers typically include a plurality of hammers mounted about a rotatable shaft. As the shaft rotates, the hammers engage and crush whatever media is introduced into the crusher. The hammers can be mounted between spiders which are positionally fixed relative to the rotor shaft. Typically, the rotor shaft is cylindrical. The use of a cylindrical shaft requires that the spider arms be positively keyed to the shaft, for example, using a square or rectangular key on the spider and a corresponding keyway on the shaft, so that the spider arms cannot rotate relative to the shaft. The use of a keyway weakens the main shaft and makes removal of the spiders and end discs a much more difficult task. Further, the key will weaken over time, and eventually the rotor assembly will shift between the shredder housings. Obviously, this can necessitate a repair of the crusher, requiring that operation of the crusher be stopped for the duration of the repair. Depending on the location of the spider which is no longer positively fixed with respect to the shaft, the crusher can be shut down for a considerable period of time.

BRIEF SUMMARY OF THE INVENTION

A shredder, crusher, hammermill, ringmill or the like is provided with a multi-sided rotor shaft to which spider arms and hammers are mounted. The rotor shaft has at least at least one pair, and preferably two or more pairs, of opposing sides. The hammers are pivotally mounted between spider arms. The spider arms have bases which include openings. The spider arm base openings have straight sides corresponding to the number of straight sides on the rotor shaft. The spider arm straight sides engage the rotor shaft straight sides. Hence, the spider arms are rotationally fixed in place relative to the rotor shaft without the of a central key, or other types of fasteners, allowing for easier assembly and reduced maintenance costs for the shredder.

Corresponding reference numerals will be used throughout the several figures of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes what I presently believe is the best mode of carrying out the invention.

A crusher 10 is shown generally in FIGS. 1 and 2 . The crusher 10 includes a housing 12 having a front wall 14 , a back wall 16 , side walls 18 and 20 , and a top 22 . A feed inlet 24 is formed in the front wall, and, can extend only a portion of the side-to-side width of the crusher 10 , or can extend substantially the full side-to-side width of the crusher 10 .

A rotor or shaft 30 extends between the side walls 18 and 20 to rotate within the housing. As seen in FIG. 3 , the rotor 30 includes a multi-sided central section 32 and two cylindrical end sections 34 extending from opposite sides of the central section. As seen in FIG. 4 , the central section 32 has eight sides; however, it could be formed with fewer sides or more sides, as desired. The central section 32 as shown in FIG. 4 includes four long sides 36 which are angled generally 90 to each other and four short sides 38 positioned between the long sides 36 , and which are also angled generally 90 to each other. The short sides 38 are curved and define arcs of a circle. Thus, in cross-section, the rotor central section 32 can be defined as a circle which is flattened along four sides to form the long sides 36 . Alternatively, the central section 32 can be defined as a square in which the corners are truncated or beveled; the beveled or truncated sections forming the curved short sides 38 . The ends 34 of the rotor 30 extend through openings 40 in the side walls 18 and 20 . At least one end of the rotor 30 is in a bearing assembly 42 , to allow the rotor to rotate within the housing 12 . The other end 34 of the rotor 30 can be operatively connected to, and supported by, a drive, such as a motor to rotate the shaft along its axis X.

A plurality of spider arms 50 are positioned on the rotor central section 32 . The spiders have a generally square base 52 having with a central opening 54 . The opening 54 is a generally square opening having straight sides 56 and curved, rather than sharp, corners 58 . The square opening 54 of the spider arm is sized to fit over the rotor central section, such that the central section long sides 34 are adjacent the straight sides of the square opening 54 . Rods 60 extend transversely through the spider bases 52 to hold the spider arms 50 together on the rotor 30 . See FIG. 5. A pair of arms or mounts 62 extends from opposite sides of each spider base. The arms 62 of adjacent spiders alternate, such that one set is vertical, the next is horizontal, the next is vertical, etc. Hammers 64 are mounted between adjacent spiders which extend in the same direction. A hammer shaft 66 extends through the arms 62 , and the hammers 64 are journaled on the hammer shafts 66 . As can be appreciated, the hammers are positioned at intervals of 90 around the circumference of the rotor shaft 30 . The rotor shaft could be provided with more than two pair of opposing straight sides to reduce the interval between the hammers. For example, if the rotor shaft had three pair of opposing straight sides, the hammers could be spaced at intervals of 60 around the shaft. Four pair of opposing straight sides would allow for intervals of 45 between the hammers. Alternatively, the rotor shaft could be formed with only one pair of opposing straight sides, such that the hammers are positioned 180 apart from each other. This would require the use of spacers between the spider arm bases.

A grate 70 extends from the bottom of the inlet 24 beneath and around the rotor 30 and hammers 64 in a generally arcuate fashion. The grate 70 , as can be appreciated, will hold matter to be crushed in the housing to be impacted and crushed the hammers. As the material is crushed to a desired size, it will fall through the grate 70 .

The use of the multi-sided rotor shaft 30 facilitates assembly of the spider arms 52 and hammers 64 on to the rotor 30 , as well as operation of the crusher 10 . Because the shaft 30 includes the flat sides 36 , and the spider base openings 54 have the corresponding flat sides 56 , the spiders 50 cannot rotate relative to the rotor shaft 30 . Thus, the crusher 10 does not require keys and keyways, pins, bolts, or other fasteners to rotationally fix the spider arms 52 to the rotor shaft central section 32 . Additionally, the corresponding shape of the rotor shaft central section 32 to the spider openings 54 causes the rotor shaft 30 to positively drive the spiders, and hence the hammers. Again, because there are no keys and keyways, pin, bolts or other fasteners which secure the spiders to the rotor shaft 30 , there are no keys and keyways, pins, bolts, or fasteners which might sheer during operation. Hence, the use of the multi-sided rotor shaft 30 , with the spider arms having straight side walls reduces not only the construction costs of the crusher or mill 10 , but also reduces maintenance costs of the crusher or mill 10 .