HAMMER FOR MATERIAL REDUCING MACHINES

Abstract

A multi-piece hammer for use in a reducing machine. The multi-piece hammer includes a base to be mounted to the reducing machine, a replaceable tip to be mounted to the base and to impact the material to be reduced, and a retainer to secure the replaceable tip to the base. The replaceable tip has a cavity with a single rail or groove that corresponds to a single groove or rail on the base.

Description

FIELD OF THE INVENTION

The present invention relates to industrial material reducing systems. More particularly, this invention relates to shredding systems that include shredder hammers.

BACKGROUND OF THE INVENTION

Industrial shredding equipment typically is used to break large objects into smaller pieces that can be more readily processed. Commercially available shredders range in size from those that shred materials like sugar cane, rocks, clay, rubber (e.g., car tires), wood, and paper to larger shredding systems that are capable of shredding scrap metal, automobiles, automobile body parts, and the like.

FIG. 1 schematically illustrates an exemplary industrial shredding system 10a. As an example only, the system is shown shredding sugar cane. Shredding system 10a includes a material intake 12a (such as conveyor) that introduces material 14a to be shredded to a shredding chamber 16a. The material 14a to be shredded may be of any desired size or shape. The material 14a is optionally pretreated, such as by heating, cooling, crushing, baling, etc. before being introduced into the shredding chamber 16a. The material intake 12a may optionally include levelers 11a, feed rollers 13a, or other machinery to facilitate feeding material 14a to chamber 16a, and/or to control the rate at which material 14a enters chamber 16a, and/or to prevent the material 14a from moving backward on the conveyor 12a.

Because there are a wide variety of applications for shredding machines, from sugar cane processing to automobile shredding, there is a wide range and variety of shredder configurations. As examples, there are generally two types of shredders for processing sugar cane: vertical shredders and horizontal shredders. In a vertical shredder (FIG. 1), knives 15a may be used to initially break up the sugar cane so that the material is the appropriate size for the shredding process. A rotary shredding head 18a spins with a direction of rotation indicated by arrow 27a that is in-line with the direction of rotation of the conveyor 12a. Rotary shredding head 18a is configured to rotate about a shaft or axis 20a, and is equipped with a plurality of shredder hammers 22a to impact the sugar cane against a hardened surface 24a to break the material apart. The hardened surface may be, for example, the feed roller, an anvil, a grate, chamber walls, or adjacent hammers. In the illustrated example, hammers 22a work in cooperation primarily with chamber walls and grates. The rotary shredding head may have, for example, 50 to 200 hammers to break up the material. Each shredder hammer 22a is independently pivotally mounted to the rotary shredding head 18a with a mounting pin 26a (FIGS. 3 and 4). In response to centrifugal forces as shredding head 18a rotates, each hammer extends outward, tending toward a position where the center of gravity of each hammer is spaced outward as far as possible from rotation axis 20a when no material is in the chamber. The shredding chamber 16a may have one or more additional rotary shredding heads 18a to further break up the material. The shredded material may then be discharged onto another conveyor for transportation to further processing.

FIG. 2 shows one example of a horizontal shredder. In this embodiment of a horizontal shredder, a rotary shredding head 18b spins with a direction of rotation indicated by arrow 27b. Similar to the vertical shredder the horizontal shredder is equipped with a rotary shredding head 18b that is configured to rotate about a shaft or axis 20b, and is equipped with a plurality of shredder hammers 22b to impact the sugar cane against a hardened surface 24b to break the material apart. The shredded material may then be discharged onto the same conveyor for transportation to further processing. Alternatively, the material may be discharged onto a separate conveyor as disclosed in US Patent Application 2008/0277514.

Shredder hammers are routinely exposed to extremely harsh conditions of use, and typically are constructed from especially durable materials, such as hardened steel materials, such as low alloy steel or high manganese alloy content steel.

Each shredder hammer may weigh, for example, between 50 and 1200 lbs. During typical shredder operations these heavy hammers impact the material to be shredded at relatively high rates of speed. Even when employing hardened materials, the typical lifespan of a shredder hammer may, for example, only be a few days up to approximately 45 days. In particular, as the shredder hammer blade or impact area undergoes repeated collisions with the material to be processed, the material of the shredder hammer tends to wear away.

Once the hammers have been worn, the worn hammers must be replaced with new hammers. The hammers often cannot be replaced very easily. In some shredders, such as sugar cane shredders, the hammers are located within the shredding equipment such that they must be replaced by a human operating under limited conditions. Because of the weight of the hammers and the confined space in which the installer must be located to replace the hammers, it can be a difficult process and the installer is at risk of being injured while replacing the worn hammers.

In an attempt to minimize the weight to be handled by those working on shredders and ease the replacement of worn hammers, multiple two piece hammers have been used with varying degrees of success. For example, U.S. Pat. No. 2,397,776 (US '776) discloses a two piece hammer with two shanks that are rotated into a replaceable tip. However, the two piece hammer in US '776 requires the entire hammer to be disassembled in order to replace the tip. Needing to disassemble each hammer to replace the tips increases the downtime of the material reducing machine. U.S. Pat. No. 3,367,585 (US '585) discloses another example of a two piece hammer. In US '585 the replaceable tip is slid onto the shank and a pin passes through the tip and shank. Once the pin has been welded to the replaceable tip, the tip is maintained on the shank. Welding a pin onto the replaceable tip increases downtime of the equipment as the weld must be removed and a new weld put in place each time a tip is replaced. In addition it can increase the potential danger to the installer if the welding equipment needs to be used in confined spaces.

It should be appreciated that the greater throughput that the shredding equipment can process, the more efficiently and profitably the equipment can operate (i.e., minimal downtime for the shredding machine is desired). Accordingly, there is room in the art for improvements in the structure and construction of two piece shredder hammers and the machinery and systems utilizing such hammers.

Examples of shredder hammers and industrial shredding equipment are disclosed in U.S. Pat. No. RE14865, U.S. Pat. No. 1,281,829, U.S. Pat. No. 1,301,316, U.S. Pat. No. 2,331,597, U.S. Pat. No. 2,467,865, U.S. Pat. No. 3,025,067, U.S. Pat. No. 3,225,803, U.S. Pat. No. 4,049,202, U.S. Pat. No. 4,083,502, U.S. Pat. No. 4,310,125, U.S. Pat. No. 4,373,679, U.S. Pat. No. 6,102,312 and U.S. Pat. No. 7,325,761. The disclosures of these and all other publications referenced herein are incorporated by reference in their entirety for all purposes.

SUMMARY OF THE INVENTION

The present invention generally pertains to material reducing operations and to multi-piece hammers that can quickly and easily be replaced when worn.

In one aspect of the present invention, a multi piece hammer includes a base, a replaceable tip and a retainer. The replaceable tip has a cavity with a single rail or groove that corresponds to a single groove or rail on the base. Having a single rail or groove between the base and the replaceable tip enables the bearing faces to be maximized especially when used on a hammer that has a narrow constrained width.

In another aspect of the invention, a replaceable tip for a multi-piece hammer includes a cavity having a front end, an open rear end, an open top end, a bottom end, and a pair of opposing sidewalls, and a single rail is provided on one of the sidewalls.

In another aspect of the invention, the tip has a rail or groove on one of the sides of the tip that has a thickness or depth that is approximately between one fifth and one half of the overall width of the cavity. In one preferred construction, the thickness or depth of the rail or groove is between one forth and two fifths the overall width of the cavity. In another preferred construction the rail or the groove is approximately one third the overall width of the cavity. Having a rail or groove that is relatively thick allows for the bearing surfaces between the base and tip to be maximized.

In another aspect of the invention, the tip has a rail(s) or groove(s) that is angled from the top end to the bottom end and from the front end to the rear end so that the replaceable tip will be held to the base of the hammer by centrifugal force when the hammer spins. The angle of the rail or groove is preferably between 35 and 65 degrees relative to the centrifugal force of the hammer spinning around the drum. In one preferred construction, the angle of the rail or groove is between 45 and 55 degrees relative to the centrifugal force. In another preferred construction the rail or groove is 50 degrees relative to the centrifugal force.

In another aspect of the invention, the tip has a transition surface within the cavity of the tip that is rounded. In one preferred construction, the rounded transition surface curves from the front end toward the bottom end. The curved surface of the replaceable tip generally matches the exterior wear profile of the tip once worn. Having an interior transition surface that matches the exterior wear profile of the worn tip allows the tip to be worn a significant amount without the base being worn.

In another aspect of the invention, the tip has a cavity with a bottom bearing surface in the bottom end of the tip that is generally parallel to the centrifugal force of the hammer spinning around the drum. The bottom bearing surface is transversely offset from a front bearing surface in the front end of the cavity of the tip. Preferably the front bearing surface and the bottom surface are connected to each other by a generally smooth transition surface and the bottom bearing surface directly opposes a front strike face of the tip.

In another aspect of the invention, the tip is secured to the base by a retainer that extends only into one side of the tip. In one preferred construction, the tip is free of an opening that extends from the cavity to the exterior surface of the tip and the tip is provided with a retainer that does not extend completely through any part of the tip and does not protrude through the exterior surface of the tip.

In another aspect of the invention, the retainer extends through the base and into a rail within the cavity of the tip. Having a retainer that extends into the rail within the cavity allows the retainer to secure the tip in the region where the tip is the thickest.

In another aspect of the invention, the hammer is provided with an integral retainer. The retainer can be adjusted between two positions with respect to the base: a first position where the tip can be installed or removed from the base, and a second position where the tip is secured to the base by the retainer. The retainer is preferably securable to the base or tip by mechanical means at the time of manufacture so that it can be shipped, stored and installed as an integral unit with the base or tip, i.e., preferably with the retainer in a “ready to install” position. Once the tip is placed onto the base, the retainer is moved to a second position to retain the tip in place for use in a material reducing machine. The retainer can continually be maintained in the base or tip throughout the life of the base or tip and does not need to be completely removed each time a tip is replaced. In the alternative of having the retainer integrally connected to the tip, a new retainer is provided with each new tip.

Other aspects, advantages, and features of the invention will be described in more detail below and will be recognizable from the following detailed description of example structures in accordance with this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a prior art vertical shredding system.

FIG. 2 is a schematic depiction of a prior art horizontal shredding system.

FIGS. 3 and 4 are perspective views of the rotating head of FIG. 1.

FIG. 5 is a schematic depiction of a horizontal shredding system equipped with one embodiment of hammers in accordance with the present invention.

FIG. 6 is a partial perspective view of the rotating head of FIG. 5.

FIG. 7 is a side view of the multi piece hammer shown in FIG. 5.

FIG. 8 is a cross sectional view of the multi piece hammer shown in FIG. 5 taken along lines 8-8 in FIG. 7.

FIG. 9 is a bottom view of the base of the hammer shown in FIG. 5.

FIG. 10 is a side view of the base of the hammer shown in FIG. 5.

FIGS. 11 and 12 are front and rear views of the base of the hammer shown in FIG. 5.

FIG. 13 is a partial side view of the base of the hammer shown in FIG. 5.

FIG. 14 is a cross sectional view of the base of the hammer shown in FIG. 5 taken along lines 14-14 in FIG. 13.

FIG. 15 is a cross sectional view of the base of the hammer shown in FIG. 5 taken along lines 15-15 in FIG. 13.

FIG. 16 is a side view of the tip of the hammer shown in FIG. 5.

FIG. 17 is a top view of the tip of the hammer shown in FIG. 5.

FIG. 18 is a bottom view of the tip of the hammer shown in FIG. 5.

FIG. 19 is a rear view of the tip of the hammer shown in FIG. 5.

FIG. 20 is a cross sectional view of the tip of the hammer shown in FIG. 5 taken along lines 20-20 in FIG. 16.

FIG. 21 is a side view of an alternative multi piece hammer in accordance with the present invention.

FIG. 22 is a perspective view of the retainer shown in FIG. 21.

FIG. 23 is a partial view of the base shown in FIG. 21 showing a hole for receiving a retainer.

FIG. 24 is a cross sectional view of the hammer taken along lines 24-24 in FIG. 21.

FIG. 25 is a perspective view of the retainer shown in FIG. 21.

FIG. 26 is a side view of another alternative multi piece hammer in accordance with the present invention.

FIGS. 27 and 28 are a cross sectional views of the retainer shown in FIG. 26 wherein the retainer is secured in both release and hold positions.

FIG. 29 is a side view of an alternative multi piece hammer in accordance with the present invention.

FIG. 30 is another side view of the hammer shown in FIG. 29.

FIG. 31 is a cross sectional view of the hammer shown in FIG. 29 taken along lines 31-31 in FIG. 30.

FIGS. 32 and 33 are side views of another alternative multi piece hammer in accordance with the present invention.

FIG. 34 is a front view of the multi piece hammer shown in FIGS. 32 and 33.

FIG. 35 is a bottom view of the multi piece hammer shown in FIGS. 32 and 33.

FIG. 36 is a cross sectional view of the multi piece hammer shown in FIGS. 32 and 33 taken along lines 36-36 in FIG. 32.

FIG. 37 is a cross sectional view of the multi piece hammer shown in FIGS. 32 and 33 taken along lines 37-37 in FIG. 33.

FIG. 38 is an exploded front perspective view of the hammer shown in FIGS. 32 and 33.

FIG. 39 is a bottom view of the shank of the hammer shown in FIGS. 32, 32, and 33.

FIG. 40 is a front view of the base of the hammer shown in FIGS. 32 and 33.

FIGS. 41 and 42 are side views of the base of the hammer shown in FIGS. 32 and 33.

FIG. 43 is a cross sectional view of the base of the hammer shown in FIGS. 32 and 33 taken along lines 43-43 in FIG. 41.

FIG. 44 is a detailed view of the base of the hammer shown in FIG. 43.

FIGS. 45 and 46 are side views of the tip of the hammer shown in FIGS. 32 and 33.

FIG. 47 is a bottom view of the tip of the hammer shown in FIGS. 32 and 33.

FIG. 48 is a cross section view of the tip of the hammer shown in FIGS. 32 and 33 taken along lines 48-48 in FIG. 45.

FIG. 49 is a cross sectional view of another alternative multi piece hammer in accordance with the present invention. The retainer is shown in a hold position where the retainer maintains the tip on the base.

FIG. 50 is a cross sectional view of the multi piece hammer shown in FIG. 49 with the retainer in a release position where the tip can be installed and removed from the base.

FIG. 51 is a cross sectional view of another alternative multi piece hammer in accordance with the present invention. The retainer is shown in a hold position where the retainer maintains the tip on the base.

FIG. 52 is a cross sectional view of the multi piece hammer shown in FIG. 51 with the retainer in a release position where the tip can be installed and removed from the base.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to material reducing machines. More particularly, this invention relates to material reducing machines that include hammers. The material reducing machine is preferably provided with multiple hammers with multiple pieces comprising a shank or base and a replaceable tip. The multi piece hammers are well suited for use in sugar cane shredders but other uses are possible.

Relative terms such as front, rear, top, bottom and the like are used for convenience of discussion, and are generally used to indicate the orientation of the shredder hammer while the hammer is at rest (i.e., while the drive shaft of the material reducing equipment is at rest). The front end is generally used to indicate the end that initially impacts the material to be reduced, the rear end is generally used to indicate the end opposite the front end, the top end is generally used to indicate the end closest to the drive shaft, and the bottom end is generally used to indicate the end opposite the top end. Nevertheless, it is recognized that when operating the shredding system the hammers attached to the drum may be oriented in various ways as the drum rotates. Additionally, as the hammers impact material they may move back and forth on the pin during use.

FIGS. 5 and 6 show an example of a horizontal shredder 10c equipped with hammers 22c of the present invention. It should be understood that aspects of the hammers of the present invention may be used with hammers for vertical shredders or other reducing machines for processing rocks, clay, rubber (e.g., car tires), wood, paper, scrap metal, automobiles, automobile body parts, and the like.

A material intake 12c (such as a conveyor) introduces material 14c to be shredded into a shredding chamber 16c. The material 14c to be shredded may be of any desired size or shape. The material intake 12c may optionally include levelers 11c, feed rollers 13c, or other machinery to facilitate feeding material 14c into chamber 16c, and/or to control the rate at which material 14c enters chamber 16c, and/or to prevent the material 14c from moving backward on the conveyor 12c.

A plurality of hammers 22c attached to the head 18c spin at very high speeds about a shaft or axis 20c in a direction of rotation indicated by arrow 27c to impact and separate material into smaller portions allowing the reduced material to be further processed in downstream operations. The rotary head 18c may have, for example, 50 to 200 hammers to break up the material. Each hammer 22c is independently pivotally mounted to the rotary head. In response to centrifugal forces as head 18c rotates, each hammer extends outward, tending toward a position where the center of gravity of each hammer is spaced outward as far as possible from rotation axis 20c when no material is in the chamber. The target material is initially impacted by a leading impact face of the hammer passing a hardened surface 24c near the material inlet. This hardened surface may be, for example, the feed roller, an anvil, chamber walls, or adjacent hammers; in this example, it is an anvil. In response to material in the system contacting the hammer leading face, the hammers, in some cases, deflect and rotate backwards on the mounting pins 26c as the hammers impact the material and crush it against the hardened surfaces 24c in the reducing chamber. Contact of the hammers 22c with the material 14c fed into the shredding machine fractures, compresses and shears the material into smaller pieces. The target material is reduced in size as the materials are compressed and shredded between the outer surface (i.e., the wear edge) of the hammer and the hardened surfaces in the reducing chamber. The shredded material may then be discharged onto a conveyor for transportation to further processing.

In one preferred embodiment of the invention (FIGS. 5 to 20), hammers 22c are made of a shank or base 101c and a replaceable tip 201c. The replaceable tip 201c is secured to the base 101c with a retainer 301c. Base 101c is shown as having a generally rectangular shape with a top surface 103c generally concentric to the mounting pin 26c on head 18c, a bottom surface 105c opposite the top surface 103c, a rear surface 107c facing away from the leading face of the hammer, and a front surface 109c facing the same direction as the leading face of the hammer, and two side surfaces 111c and 113c between the front and rear surfaces 107c and 109c. The general shape of the base is not intended to be limiting as the shape of the base will vary depending on the material to be reduced or processed and the type of reducing machine the hammer is to be used in. For example, in alternative embodiments the base may generally have a tear drop shape, an elliptical shape, or a cylindrical shape. In addition the base may have one or more recesses extending into either side surface to balance the hammer and obtain an optimal center of gravity for the hammer.

Base 101c has a top mounting end 115c for mounting the hammer onto the head 18c and a bottom mounting end 117c for mounting the replaceable tip 201c on the base 101c. The top mounting end has a through hole 119c for mounting the hammer on the mounting pin 26c of the head 18c. Thickened portions 121c may be provided on the sidewalls 111c and 113c adjacent through hole 119c to reinforce the hole.

Top surface 103c is shown as being rounded and generally concentric to through hole 119c, but other arrangements are possible. In addition, the thickness between the through hole 119c and the top surface 103c is preferably relatively thin so that most of the mass of the base 101c is below the through hole. Having a majority of the mass below the through hole 119c maximizes the force the hammer 22c will have when the leading face impacts the material 14c to be shredded or reduced. The top surface 103c, however, may have a variety of shapes and the thickness between the through hole 119c and the top surface 103c may have a variety of thicknesses as long as sufficient clearance is provided for the hammers to have the freedom of movement desired for the machine in which it is mounted. The hammers 22c may rotate on the mounting pins 26c without interference with other hammers 22c, pins, or the head 18c.

The bottom mounting end 117c of base 101c is provided with a groove 123c that corresponds to a rail 223c on the tip 201c. Groove 123c preferably extends into the side surface 111c to a depth between one fifth and one half of the overall width W of the base 101c, where the width W is distance between the sidewalls 111c and 113c when measured in the bottom mounting end 117c of base 101c as shown in FIGS. 11 and 12. In one preferred embodiment, the depth of the groove 123c extends into the side surface 111c to a depth between one fourth and two fifths of the overall width W of the base 101c. In another preferred embodiment, the depth of the groove 123c extends into the side surface 111c to a depth of approximately one third the overall width W of the base 101c. A groove that extends relatively deep into the width of the base 101c allows more surface area between the base 101c and the tip 201c to better withstand and resist the applied loads during use. Base 101c and tip 201c are shown as only having one groove on one of the sides 111c. Having a rail and groove on only one side allows the surface area to be maximized when the width of the base is constrained to be relatively narrow. However in some embodiments a groove and rail may be located on each side of the base 101c and tip 201c. Additionally, the rail or rails could be provided on the base and the groove or grooves could be provided on the tip, and the depth of the rails and grooves could be more than half the width of the base or less than one fifth the width of the base.

Groove 123c preferably extends all the way across the base 101c from the front surface 109c to the rear surface 107c. In alternative embodiments not shown, the groove may not extend completely across the rear end 107c. Groove 123c is preferably angled downward from the front surface 109c to the rear surface 107c so that the end of the groove closest to front surface 109c is generally closer to upper end 103c of base 101c and with the end of groove 123c closest rear end 107c is generally farther away from the upper end 103c. Thus, when the rail 223c of tip 201c is secured in groove 123c the centrifugal force F of the hammer 22c spinning around the head 18c tends to urge the tip 201 farther downward and into the groove 123c. The base 101c has a bottom bearing surface 137c that engages a bottom bearing surface 237c on the tip 201c to act as a stop to prevent the rail 223c on tip 201c from being urged out the bottom end of groove 123c. The groove 123c has a downward angle Θ_1c relative to the centrifugal force F between 35 and 65 degrees (FIG. 10). In the illustrated example, the centrifugal force is along the longitudinal axis of the base, i.e., radially vertical from through hole 119c. In one preferred embodiment, the angle Θ_1c of the groove 123c is between 45 and 55 degrees relative to the centrifugal force F. In another preferred embodiment, the angle Θ_1c of the groove 123c is 50 degrees relative to the centrifugal force F. Alternatively, the groove 123c may have an angle Θ_1c less than 35 degrees, greater than 65 degrees up to and including about 90 degrees (i.e., generally perpendicular to the centrifugal force F).

Groove 123c is shown as being generally U-shaped with an inner surface 125c and an upper and lower surface 127c and 129c. Inner surface 125c is generally perpendicular to upper and lower surfaces 127c and 129c and upper and lower surfaces 127c and 129c are generally parallel to each other (e.g., a small draft between 1 and 6 degrees may be provided for upper and lower surfaces 127c and 129c for manufacturing purposes so that the surfaces are not exactly parallel to each other). The shape of the groove 123c is not intended to be limiting as alternative shapes are possible. For example, the groove may be generally triangular, dovetail, or concave, and the upper and lower surfaces may converge toward each other as they extend toward the rear end 107c.

A recess 131c is preferably provided on the front surface 109c and above the upper surface 127c of the groove 123c. Recess 131c provides clearance to receive tip 201c so that tip 201c will have minimal wear on front surface 109c as the tip impacts the material to be shredded. Recess 131c also allows a tool to be inserted to pry the tip 201c out of the groove 123c and off of the base 101c.

An opening 133c extends into or through base 101c for receipt of a retainer 301c. Opening 133c preferably extends through inner surface 125c of groove 123c. Opening 133c is preferably located generally in the center of the primary and reactionary forces between the base 101c and the tip 201c as the hammer 101c engages the material to be reduced. Having the retainer 301c generally in the center of the primary and reactionary forces reduces the loading on the retainer 301c. Alternatively, opening 133c may extend into or through the upper or lower surfaces 127c and 129c of groove 123c or the opening 133c could be above or below groove 123c depending on the shape of the tip 201c. In alternative embodiments, the opening 133c may not extend completely through base 101c and may not be generally located in the center of the primary and reactionary forces.

A front surface 134c is provided adjacent the front surface 109c and adjacent the inlet of groove 123c. Front surface 134c is preferably spaced rearward from front surface 109c and has a slight rearward taper. With this arrangement, the tip is fit with the base so that tip 201c has a tendency to first bear against the upper surface 127c of groove 123c and then against front bearing surface 134c when impacting the material to be shredded. Front surface 134c is primarily provided as a secondary bearing surface for bearing against the tip 201c under rebound conditions.

Below groove 123c in the mounting section 117c of base 101c is a transition surface 135c. Transition surface 135c generally matches a transition surface 235c on tip 201c as it extends from front surface 134c. Transition surface 135c forms a curved surface from the front surface 134c towards the bottom surface 105c. The lower part of transition surface 135c may be generally parallel to groove 125c and the upper part may generally match an outer wear profile of tip 201c. Transition surface 135c and front surface 134c are preferably recessed from front surface 109c to allow tip 201c to have more material for wearing. At the bottom of transition surface 135c a bottom bearing surface 137c is provided. Bottom bearing surface 137c is generally parallel to the centrifugal force F to better resist the impact loads but other orientations are possible.

The replaceable tip 201c has an open top 203c and open rear end 207c for receipt of base 101c. Replaceable tip 201c has a front surface 209c facing the direction of the rotation of the hammer 22c and a bottom surface 205c generally facing perpendicular to the centrifugal force F of the hammer 22c spinning around the drum 18c. Two side surfaces 211c and 213c are provided between the front surface 209c and rear end 207c. Together side surfaces 211c and 213c, front surface 209c and bottom surface 205c make up the exterior surface 210c of the replaceable tip 201c.

Generally, front surface 209c initially impacts the material 14c to be shredded. Front surface 209c and bottom surface 205c could have a variety of shapes and orientations. For example, front face 209c may be generally parallel to the centrifugal force as shown or at an angle to the direction of the centrifugal force. The front face may also have a convex, concave, or irregular configuration. Similarly bottom surface 205c may have a variety of shapes, for example, the bottom surface may be generally perpendicular to the front surface 209c as shown, or may have a convex or concave curve, and may be provided with recesses or grooves. It should be appreciated that other shapes of the exterior surface 210c are possible. For example, the exterior surface of the tip may have an exterior surface with recesses and notches and front and bottom surfaces that are orientated similar to hammers and crushing tips disclosed in WO 2014/205123, WO 2014/153361 or US Patent Publications 2014-0151475, 2013-0233955, or 2009-0174252 each of which is incorporated herein by reference. Additionally the exterior surface may be provided with one or more wear indicators so that the operator can quickly tell if the replaceable tip needs to be replaced. The wear indicators may be placed anywhere along the wear profile of the tip and may, for example, be a notch located at the rear end of the tip. In addition the front surface and sides of the tip may be covered with hard facing 289d as shown in FIG. 21 or provided with inserts of a different material than the body of the tip as disclosed in US Patent Publication 2013-0233955 which is incorporated herein by reference (not shown). The inserts may comprise a hardened material such as diamond, tungsten carbide or carbon nitride. The inserts may be held in cast or drilled holes in the tip, may be cast in place when the hammer is manufactured or attached in other ways.

Although numerous shapes are possible, the top edge 212c and 214c of sidewalls 211c and 213c are shown as generally aligned and parallel with a rail 223c in a socket 239c of tip 201c. An opening 233c extends completely through the sidewalls 211c and 213c as shown in FIG. 20. Preferably opening 233c also extends through the rail 223c. A protrusion 241c may be provided along one or both of top edges 212c and 214c to provide additional support to opening 233c. Depending on the size of the retainer, the protrusion may extend into the rear end 207c (i.e., in general, the larger the retainer, the larger the protrusion will ordinarily be). A recess or countersink 243c may be provided on one or both side surfaces 211c and 213c adjacent opening 233c in order to minimize the wear that retainer 301c will experience and maintain retainer 301c in a shadow of the front leading surface 209c. In other embodiments, opening 233c may extend only through a portion of the tip and is largely dependent on the type of retainer to be used to hold the tip 201c onto the base 101c. Additionally the opening and retainer may be located in surfaces other than the sidewalls 211c and 213c and may, for example, be in the front surface 209c or the bottom surface 205c.

As shown in FIG. 19, cavity 239c extends into the top end 203c and rear end 207c so that the cavity 239c is provided with two sidewalls 245c and 247c that generally correspond to sidewalls 111c and 113c of base 101c. The front end of cavity 239c closest to front surface 209c has a front surface 234c to correspond to and bear against front surface 134c of base 101c. Front surface 234c preferably has a slight angle relative to the centrifugal force F so that tip 201c has a tendency to first bear against the upper surface 227c of rail 223c and then against front surface 234c when impacting the material to be shredded. Front surface 234c transitions into a transition surface 235c that corresponds to transition surface 135c on base 101c. Transition surface 235c generally curves from the front surface 234c towards a bottom bearing surface 237c. Parts of transition surface 235c may be generally parallel to rail 225c and parts may generally match an outer wear profile of tip 201c. At the bottom of transition surface 235c, a bottom bearing surface 237c is provided. Bottom bearing surface 237c is generally parallel to the centrifugal force F and bears against bottom bearing surface 137c of base 101c but other orientations are possible.

Sidewall 245c is provided with a rail 223c that corresponds to a groove 123c on the base 101c. Rail 223c preferably extends into the cavity 239c towards sidewall 247c to a depth between one fifth and one half of the overall width of the cavity 239c. A rail that extends relatively deep into the width of the cavity 239c allows more surface area between the base 101c and the tip 201c. In one preferred embodiment, the depth of the rail 223c extending into the cavity 239c is between one fourth and two fifths of the overall width of the cavity 239c. In another preferred embodiment, the depth of the rail 223c extending into the cavity 239c is approximately one third the overall width of the cavity. Additionally, the depth of the rails could be more than half the width of the cavity or less than one fifth the width of the cavity. Rail 223c and groove 123c have a width W large enough to support retainer 301c.

Rail 223c preferably extends from the front end of the cavity 239c all the way to the rear end 207c of tip 201c. Alternatively, the rail may not extend completely to the rear end 207c. Rail 223 corresponds to groove 123c and is angled downward from the front end of the cavity to the rear end 207c. As with the groove 123c, the rail 223c has a downward angle Θ_2c relative to the centrifugal force F of the tip 201 swinging with the hammer 22c around the drum 18c (FIG. 7 shows the rail 223 with phantom lines). Θ_2c is preferably between 35 and 65 degrees. In one preferred embodiment, the angle Θ_2c of the rail 223 is between 45 and 55 degrees relative to the centrifugal force F. In another preferred embodiment, the angle Θ_2c of the rail 223c is 50 degrees relative to the centrifugal force F. As with groove 123c, the rail 223c may have an angle Θ_2c less than 35 degrees, greater than 65 degrees up to and including about 90 degrees (i.e., generally perpendicular to the centrifugal force F). In the illustrated embodiment, the centrifugal force is generally along the longitudinal axis of base 101c

Rail 223c is shown as being generally U-shaped with an inner surface 225c and an upper and lower surface 227c and 229c. Inner surface 225c is generally perpendicular to upper and lower surfaces 227c and 229c and upper and lower surfaces 227c and 229c are generally parallel to each other. The surfaces 225c, 227c, and 229c bear on surfaces 125c, 127c, and 129c of base 101c as the tip 201 engages the material 14c to be shredded. The shape of the rail 223c is not intended to be limiting as alternative shapes are possible. For example, the rail may be generally triangular, or convex and the upper and lower surfaces may converge toward each other as they extend toward the rear end 207c.

To assemble tip 201c on base 101c, tip 201c with rail 223c is aligned with groove 123c in base 101c. The tip 201c is then slid onto base 101c until bottom bearing surface 137c of the base 101c abuts the bottom bearing surface 237c of tip 201c. At this point opening 133c of base 101c aligns with opening 233c of base 201c. A main body 303c of retainer 301c passes through opening 233c in side surface 213c of tip 201c and continues into opening 133c in base 101c until the leading end of the main body 303c passes into the recess 243c in sidewall 211c of tip 201c (FIG. 8). A securement mechanism 305c is affixed to the end of main body 303c of retainer 301c.

Many types of retainers are possible to hold tip 201c to base 101c. For example, retainer 301c may consist of a main body 303c and a securement mechanism 305c. The main body 303c may be, for example, a bolt and the securement mechanism may be, for example, a lock washer, nut, or cotter pin. Alternative locks may pivot, slide, rotate, or otherwise moved into position so that a first portion of the lock contacts the tip and a second portion of the tip contacts the base to secure the tip to the base.

In an alternative embodiment shown in FIGS. 21-25, a multi piece hammer 22d is provided with a base 101d and tip 201d that are similar in many ways to hammer 22c with many of the same benefits and purposes. The following discussion focuses on the differences and does not repeat all the similarities that apply to hammer 22d. For example hammer 22d is provided with a retainer 301d similar to the retainer disclosed in US Patent publication 2013-0174453 filed Jul. 12, 2012 incorporated herein by reference.

Retainer 301d includes a mounting component or collar 322d and a retaining component or pin 320d. Collar 322d fits in opening 133d of base 101d and lugs 336d, 337d, and 338d of collar 322d engage against shoulders 171d, 173d, and 175d of opening 133d of base 101d to mechanically hold collar 322d in opening 133d and effectively prevent inward and outward movement during shipping, storage, installation and/or use of base 101d. Collar 322d includes a bore or opening 323d with threads 358d for receiving pin 320d with matching threads 354d. The collar could be secured to the base in other ways. The collar could alternatively be omitted and threads or partial threads formed in opening 133d. In the illustrated embodiment, a retainer 324d, preferably in the form of a retaining clip, is inserted in opening 133d with collar 322d to prevent disengagement of the collar 322d from base 101d. Preferably, collar 322d and retainer 324 are inserted at the time of manufacturing of base 101d and never need to be removed from the base 101d. Nevertheless, if desired, collar 322d and retainer 324 could be removed at any time. Openings 133d and 233d are adapted to receive retainer 301d to secure the tip 201d to the base 101d. Alternatively, the collar could be secured in the tip, e.g., in the rail.

Pin 320d preferably includes a head 347d and a shank 349d. Shank 349d is formed with threads 354d or another means for positively engaging the collar 322d. Threads 354d extend along a portion of its length from head 347. Pin end 330d is preferably unthreaded for receipt into opening 233d in rail 223d of tip 201d to prevent tip 201d from sliding off of base 101d.

To install tip 201d on base 101d the collar 322d is first installed in opening 133d. As discussed above, the collar 322d is preferably installed at the time of manufacture and will not need to be reinstalled in the base 101d or the base may be provided with threads in opening 133d so that a collar 322d is not needed. Tip 201d is slid onto base 101d until the bottom bearing surfaces of the base abut the bottom bearing surfaces of the tip. Pin 320d is installed into collar 322d from side surface 213d of tip 201d so that pin end 330d is the leading end and pin threads 354d engage collar threads 358d. A hex socket (or other tool-engaging formation) 348d is formed in head 347d, at the trailing end, for receipt of a tool to turn pin 320d in collar 322d. Pin 320d is rotated until the pin end 330d engages the opening 233d within the rail 223d of tip 201d as shown in FIG. 24.

In another embodiment shown in FIGS. 26 to 28, a multi piece hammer 22e is provided with a base 101e and tip 201e that are similar in many ways to hammer 22c and hammer 22d with many of the same benefits and purposes. However, in this embodiment, tip 201e has a front leading surface 209e with a sloped surface 206e that extends forward of base 101e and ends with a forward most impact surface 208e. Tip 201c or 201d could be provided with a front leading surface similar to tip 201e. As seen in FIG. 26, sidewall 213e of tip 201e does not have a protrusion similar to the protrusion 241c of hammer 22c in FIG. 16. Instead, tip 201e has a recess 241e. Recess 241e is preferably large enough so that retainer 301e, which is similar to retainer 301d, may be left installed in a release position so that the tip 201e can be slide onto the base 101e while the retainer is in the base 101e. The retainer is preferably secured to the base by mechanical means at the time of manufacture so that it can be shipped, stored and installed as an integral unit with the base, i.e., with the retainer in a “ready to install” position.

The use of recess 241e allows the retainer 301e to only extend into one side of the tip 201e. Tip 201e preferably has an opening in a rail in tip 201e for receiving a pin and may be, for example, similar to opening 233d in tip 201d so that the tip has an opening extending from the cavity to a distance short of the exterior surface of the tip 201d. The retainer 301e will preferably only extend into an interior surface within the cavity of the tip 201e. In the illustrated embodiment, the retainer does not extend completely through any part of the tip and does not protrude through the exterior surface of the tip.

Retainer 301e has a threaded pin 320e and collar 322e. Threaded pin 320e preferably includes a biased latching tooth or detent 352e, biased to protrude beyond the surrounding thread 354e. A corresponding outer pocket or recess 356e is formed in the thread 358e of collar 322e to receive detent 352e, so that threaded pin 320e latches into a specific position relative to collar 322e when latching detent 352e aligns and inserts with outer pocket 356e. The engagement of latching detent 352e in outer pocket 356e holds threaded pin 320e in a release position relative to collar 322e, which holds pin 320e outside of the rail of tip 201e. Preferably, latching detent 352e is located at the start of the thread on threaded pin 320e, near the pin end 330e. Outer pocket 356e is located approximately ½ rotation from the start of the thread on collar 322e. As a result, pin 320e will latch into release position after approximately ½ turn of pin 320e within collar 322e. Further application of torque to pin 320e will squeeze latching detent 352e out of outer pocket 356e. An inner pocket or recess 360e is formed at the inner end of the thread of collar 322e. Preferably, the thread 358e of collar 322e ends slightly before inner pocket 360e. This results in an increase of resistance to turning pin 320e as pin 320e is threaded into collar 322e, when latching detent 352e is forced out of thread 358e. This is followed by a sudden decrease of resistance to turning pin 320e, as latching detent 352e aligns with and pops into the inner pocket. In use, there is a noticeable click or “thunk” as pin 320e reaches an end of travel within collar 322e. The combination of the increase in resistance, the decrease in resistance, and the “thunk” provides haptic feedback to a user that helps a user determine that pin 320e is fully latched in the proper service position with the pin end 330e extending into an opening in a rail similar to opening 233d. This haptic feedback results in more reliable installations of base and tip using the present combined collar and pin assembly, because an operator is trained to easily identify the haptic feedback as verification that pin 320e is in the desired position to retain the tip 201e on base 101e. Other kinds of detents could be used that latch in other ways such as to engage the inner surface of the opening in base 101e. Features of latching retainer 301e can be used with hammer 22d and retainer 301d to provide additional benefits. For example, retainer 301d may be provided with the latching detent 352e and inner pocket 360e to latch the retainer in a locked position when in use.

In an alternative embodiment shown in FIGS. 49 and 50, a retainer 301h similar to retainer 301d or 301e may be secured to the tip 201h by mechanical means at the time of manufacture so that it can be shipped, stored and installed as an integral unit with the tip 201h, i.e., with the retainer 301h in a “ready to install” position (i.e., in a release position as shown in FIG. 50). The retainer 301h may be integrally connected to the tip 201h. A collar 322h similar to 322d and 322e may be, for example, secured within an opening 233h in a side of tip 201h. The collar 322h may be, for example, secured in a rail 223h similar to rail 223c and a threaded pin 320h similar to 320d and 320e may be mechanically secured to the collar 322h in a release position where the tip 201h can be installed on the base 201h. Once the tip 201h is installed on the base 101h the pin 320h may be moved to a hold position, as shown in FIG. 49, where the pin 320h abuts a surface on the base 101h to maintain the tip 201h on the base 101h.

In an alternative embodiment shown in FIGS. 51 and 52, base 101i and tip 201i are similar to base 101h and tip 201i. The tip 201i has a collar 322i that is installed in a rail 223i. The base 101i, however, preferably does not have a through hole for receiving the threaded pin 320i. The base 101i has a recess 133i for receiving the threaded pin 320i. In addition opening 233i only extends into the side of the tip 201i with the rail 223i. Like retainer 301h, retainer 301i may be installed in tip 201i at the time of manufacture and be shipped, stored and installed as an integral unit with the tip 201i, i.e., with the retainer 301i in a “ready to install” position (i.e., in a release position as shown in FIG. 52). Once the tip 201i is installed on the base 101i the pin 320i may be moved to a hold position, as shown in FIG. 51, where the pin 320i abuts a surface of the recess 133i of base 101i to maintain the tip 201i on the base 101i.

In another embodiment shown in FIGS. 29 to 31, a multi piece hammer 22f is provided with a base 101f and tip 201f that are similar in many ways to hammers 22c, 22d and 22e with many of the same benefits and purposes. However, in this embodiment opening 133f in base 101f does not extend through groove 123f. Opening 133f is located above groove 123f. Likewise, opening 233f is above rail 223f in tip 201f. Sidewall 211f is provided with a protrusion 241f and opening 233f extends through the protrusion. Sidewall 213f of tip 201f does not extend as high as sidewall 211f. Tip 201f is installed on base 101f in a similar fashion as tip 201e is installed on base 101e in hammer 22e. First the retainer 301f is secured in a release position within base 101f so that pin end 330f of pin 320f does not protrude outside opening 133f. Next, tip 201f is slide onto base 101f and retainer 301f is rotated to a locked position where pin end 330f protrudes into opening 233f in tip 201f.

In another embodiment shown in FIGS. 32-48, a multi piece hammer 22g is provided with a base 101g and tip 201g that are similar in many ways to hammers 22c, 22d, 22e, and 22f with many of the same benefits and purposes. In this embodiment, base 101g has a recess 139g in sidewall 113g. Once the tip 201g has been slid onto the base 101g, recess 139g and sidewall 247g of tip 201g form a pocket 141g to receive a securement mechanism 305g.

Groove 123g is shown as being half of a dovetail joint that mates with rail 223g that forms the other half of the dovetail joint. Groove 123g has an inner surface 125g and an upper and lower surface 127g, 129g. Upper and lower surfaces 127g and 129g converge toward each other as they extend from inner surface 125g. Upper and lower surfaces 127g and 129g are shown as converging toward each other with an angle α_g. In the illustrated embodiment, the angle of convergence α_g is an acute angle, however the angle of convergence could be greater or the upper and lower surfaces 127g, 129g could have angles of convergence α_g that are different from each other. Similarly the rail 223g on tip 201g has a dovetail shape to form the other half of the dovetail joint. Rail 223g has an inner surface 225g and an upper and lower surface 227g, 229g to correspond to groove 123g (i.e., upper and lower surfaces 227g and 229g converge toward each other as they extend from inner surface 225g). Hammers 22c, 22d, 22e, and 22f may also have a groove and rail similar to hammer 22g.

As seen in FIGS. 36 and 43, base 101g is tapered from the rear end 107g to the front end 109g along a plane normal to the angle θ_1g of groove 123g (i.e., sidewalls 111g and 113g converge toward each other as they extend forward toward front end 109g). Tapering the base from the rear end 107g to the front end 109g allows the tip 201g to have more wear material and strength while still maintaining the overall thickness of the hammer 22g. Tapering the base 101g along a plane normal to the angle θ_1g of groove 123g allows the tip 201g to be able to slide onto the base 101g. As seen in FIG. 36, sidewalls 245g and 247g within cavity 239g of tip 201g generally correspond to sidewalls 111g and 113g of base 101g (i.e., sidewalls 245g and 247g converge toward each other as they extend forward toward front end 209g along a plane normal to the angle θ_1g of groove 123g and rail 223g.) Hammers 22c, 22d, 22e, and 22f may also taper similar to hammer 22g.

The outer side surfaces 211g and 213g of tip 201g are tapered backward from the front end 209g to the rear end 207g (i.e., the side surfaces 211g and 213g converge toward each other as they extend from front end 209g toward rear end 207g). The front end 209g has a larger width than the rear end 207g and the rear end 207g is in the shadow of front end 209g. This general tapered shape helps minimize the wear that the rearward portions of the tip 201g experience. In addition, the larger front end 209g minimizes the wear the base 101g will experience. Tips 201c, 201d, 201e, and 201f may also have a rearward taper similar to tip 201g.

To assemble tip 201g on base 101g, tip 201g with rail 223g is aligned with groove 123g in base 101g. The tip 201g is then slid onto base 101g until bottom bearing surface 137g of the base 101g abuts the bottom bearing surface of tip 201g. At this point, opening 133g of base 101g aligns with opening 233g of base 201g. The main body 303g of retainer 301g passes through opening 233g in side surface 211g of tip 201g and continues into opening 133g in base 101g until the leading end of the main body 303g passes into the other end of the opening in sidewall 213g of tip 201g (FIG. 37). The securement mechanism 305g (in this example a hair pin clip) is slid into pocket 141g until the securement mechanism 305g engages groove 307 on the main body 303g of retainer 301g. Securement mechanism 305g is designed to resist minimal loads as the hammer impacts the material to be reduced. The retainer is secured to the base 101g and the opposite ends of the main body 303g engage the through opening 233g on both sides 211g and 213g of tip 201g to prevent the tip 201g from sliding off of the base 101g.

The above disclosure describes specific examples of hammers for use with material reducing equipment. The hammers include different aspects or features of the invention. The features in one embodiment can be used with features of another embodiment. The examples given and the combination of features disclosed are not intended to be limiting in the sense that they must be used together.

Claims

1. A replaceable tip for a multi-piece hammer for a material reduction machine, the tip being mountable to a base on a driven roll, the tip comprising a leading surface to impact material to be reduced, and a cavity opening to receive the base, the cavity including a front end, a rear end, and opposing surfaces to be received over the base, and the opposing surfaces including only a single rail or groove on one of the opposing surfaces for receipt with a corresponding rail or groove on the base.

2. A replaceable tip in accordance with claim 1 including a front surface facing generally in the direction of rotation during use, wherein the rail or groove extends downward and rearward from the front surface.

3. A replaceable tip in accordance with claim 1 including an opening in the tip for receiving a retainer to secure the tip to the base.

4. A replaceable tip in accordance with claim 3 wherein the opening in the tip is in the rail or groove.

5. A replaceable tip in accordance with any one of claim 1 wherein the cavity includes a bottom end, a front bearing surface in the front end of the cavity, and a bottom bearing surface in the bottom end of the cavity, wherein the bottom bearing surface is generally parallel to a centrifugal force experienced as the base spins around the drum and the bottom bearing surface is transversely offset from the front bearing surface.

6. A replaceable tip in accordance with claim 1 wherein the cavity includes a transition surface that curves from the front end toward the bottom end.

7. A replaceable tip in accordance with claim 6 wherein the transition surface generally matches a shape of an exterior surface of the tip when the tip has experienced wear.

8. A replaceable tip in accordance with claim 1 wherein the rail or groove includes bearing surfaces along opposite sides of the rail or groove to support the tip on the base during use.

9. A replaceable tip in accordance with claim 1 wherein the rail or groove is inclined between 35 and 65 degrees relative to centrifugal force generated by the machine during use.

10. A replaceable tip in accordance with claim 1 wherein the rail or groove is inclined between 45 and 55 degrees relative to centrifugal force generated by the machine during use.

11. A replaceable tip in accordance with claim 1 wherein the rail or groove is inclined 50 degrees relative to centrifugal force generated by the machine during use.

12. A replaceable tip in accordance with claim 1 wherein the rail or groove generally extends from the front end to the rear end of the cavity.

13. A replaceable tip in accordance with claim 1 wherein the cavity has a width and the rail or groove has a thickness that is approximately between one fifth and one half of the width of the cavity.

14. A replaceable tip in accordance with claim 13 wherein the width of the rail or cavity is between one forth and two fifths the width of the cavity.

15. A replaceable tip in accordance with claim 13 wherein the width of the rail or groove is approximately one third the width of the cavity.

16. A replaceable tip in accordance with claim 1 wherein the cavity includes a top end, and a bottom end and wherein the top end and the rear end are open to receive the base.

17. A replaceable tip in accordance with claim 1 wherein the cavity includes the rail that receives the groove on the base.

18. A replaceable tip in accordance with claim 1 wherein the cavity includes the groove that receives the rail on the base.

19. A hammer for a reduction machine, the hammer comprising: a base including a first mounting end for mounting the base to a driven roll of the reduction machine, a second mounting end, a groove or rail, and an opening;a replaceable tip comprising a leading surface to impact material to be reduced, an opening that generally aligns with the opening on the base when the replaceable tip is mounted on the base, and a cavity opening to receive the second mounting end of the base, the cavity including a front end, a rear end, and opposing surfaces to be received over the base, and the opposing surfaces including only a single rail or groove on one of the opposing surfaces for receipt within the groove or rail on the base; anda retainer inserted into the opening in the base and the opening in the replaceable tip to secure the replaceable tip to the base.

20. A hammer in accordance with claim 19 wherein the retainer extends into a single side of the tip.

21. A hammer in accordance with claim 19 wherein the tip has an exterior surface and the opening in the tip for receiving the retainer extends from the cavity to a distance short of the exterior surface.

22. A hammer in accordance with claim 19 wherein the tip and the base experience forces between each other as the tip engages the material to be reduced, the tip and the base have a center about which the tip tends to rock as the tip and base experience the forces, and the retainer is generally located in the center.

23. A replaceable tip for a multi-piece hammer for a material reduction machine, the tip being mountable to a base on a driven roll, the tip comprising a front surface facing generally in the direction of rotation during use, and a cavity opening to receive the base, the cavity including a front end, a rear end, and opposing surfaces to be received over the base, and the opposing surfaces including a rail or groove on one of the opposing surfaces for receipt with a corresponding rail or groove on the base, wherein the rail or groove extends downward and rearward from the front surface.

24. A replaceable tip in accordance with claim 23 wherein the opposing surfaces include only a single rail or groove on one of the opposing surfaces.

25. A replaceable tip in accordance with claim 23 including an opening in the tip for receiving a retainer to secure the tip to the base.

26. A replaceable tip in accordance with claim 25 wherein the retainer is secured within the opening so that the retainer and the tip are maintained as a single integral unit.

27. A replaceable tip in accordance with claim 23 wherein the cavity includes a bottom end, a front bearing surface in the front end of the cavity, and a bottom bearing surface in the bottom end of the cavity, wherein the bottom bearing surface is generally parallel to a centrifugal force experienced as the base spins around the drum and the bottom bearing surface is transversely offset from the front bearing surface.

28. A replaceable tip in accordance with claim 23 wherein the cavity includes a transition surface that curves from the front end toward the bottom end.

29. A replaceable tip in accordance with claim 28 wherein the transition surface generally matches a shape of an exterior surface of the tip when the tip has experienced wear.

30. A replaceable tip in accordance with claim 23 wherein the rail or groove includes bearing surfaces along opposite sides of the rail or groove to support the tip on the base during use.

31. A hammer for a reduction machine, the hammer comprising: a base including a first mounting end for mounting the base to a driven roll of the reduction machine, a second mounting end, a groove or rail, and an opening;a replaceable tip comprising a front surface facing generally in the direction of rotation during use, an opening that generally aligns with the opening on the base when the replaceable tip is mounted on the base, and a cavity opening to receive the second mounting end of the base, the cavity including a front end, a rear end, and opposing surfaces to be received over the base, and the opposing surfaces including a rail or groove on one of the opposing surfaces for receipt with the groove or rail on the base, wherein the rail or groove on the base and the replaceable tip extends downward and rearward from the front surface; anda retainer inserted into the opening in the base and the opening in the replaceable tip to secure the replaceable tip to the base.

32. A hammer in accordance with claim 31 wherein the retainer extends into a single side of the tip.

33. A hammer in accordance with claim 31 wherein the tip has an exterior surface and the opening in the tip for receiving the retainer extends from the cavity to a distance short of the exterior surface.

34. A hammer in accordance with claim 31 wherein the tip and the base experience forces between each other as the tip engages the material to be reduced, the tip and the base have a center about which the tip tends to rock as the tip and base experience the forces, and the retainer is generally located in the center.

35. A replaceable tip for a multi-piece hammer for a material reduction machine, the tip being mountable to a base on a driven roll, the tip comprising: an exterior surface for engaging material to be reduced;a cavity opening in the exterior surface to receive the base, the cavity having a front end and a rear end;an opening in the exterior surface that aligns with an opening in the base; anda retainer to hold the tip to the base, the retainer secured within the opening for movement between a release position where the tip can be mounted on the base and a hold position where the tip is secured to the base, the retainer and the tip being maintained as a single integral unit in both the release and hold positions.

36. A replaceable tip in accordance with claim 35 wherein the cavity includes a bottom end, a front bearing surface in the front end of the cavity, and a bottom bearing surface in the bottom end of the cavity, wherein the bottom bearing surface is generally parallel to a centrifugal force experienced as the base spins around the drum and the bottom bearing surface is transversely offset from the front bearing surface.

37. A replaceable tip in accordance with claim 35 wherein the cavity includes a transition surface that curves from the front end toward the bottom end.

38. A replaceable tip in accordance with claim 37 wherein the transition surface generally matches a shape of an exterior surface of the tip when the tip has experienced wear.

39. A replaceable tip in accordance with claim 35 wherein the exterior surface includes a front surface facing generally in the direction of rotation during use, and the cavity includes opposing surfaces to receive the base, and a rail or groove that extends downward and rearward from the front surface.

40. A replaceable tip in accordance with claim 39 wherein the opposing surfaces include only a single rail or groove on one of the opposing surfaces.

41. A replaceable tip in accordance with claim 39 wherein the rail or groove includes bearing surfaces along opposite sides of the rail or groove to support the tip on the base during use.

42. A replaceable tip in accordance with claim 35 wherein the cavity includes opposing surfaces to receive the base, and the opposing surfaces include only a single rail or groove on one of the opposing surfaces.

43. A replaceable tip for a multi-piece hammer for a material reduction machine, the tip being mountable to a base on a driven roll, the tip comprising: an exterior surface for engaging material to be reduced;a cavity opening to receive the base, the cavity including a front end, a bottom end, and a transition surface that curves from the front end toward the bottom end, the transition surface generally matching an anticipated shape of the exterior surface when the exterior surface has experienced substantial wear; andan opening to receive a retainer to hold the tip to the base.

44. A replaceable tip in accordance with claim 43 wherein the cavity includes a bottom end, a front bearing surface in the front end of the cavity, and a bottom bearing surface in the bottom end of the cavity, wherein the bottom bearing surface is generally parallel to a centrifugal force experienced as the base spins around the drum and the bottom bearing surface is transversely offset from the front bearing surface.

45. A replaceable tip in accordance with claim 43 wherein the exterior surface includes a front surface facing generally in the direction of rotation during use, and the cavity includes opposing surfaces to receive the base, and a rail or groove that extends downward and rearward from the front surface.

46. A replaceable tip in accordance with claim 45 wherein the rail or groove includes bearing surfaces along opposite sides of the rail or groove to support the tip on the base during use.

47. A replaceable tip in accordance with claim 43 wherein the cavity includes opposing surfaces to receive the base, and the opposing surfaces include only a single rail or groove on one of the opposing surfaces.

48. A replaceable tip for a multi-piece hammer for a material reduction machine, the tip being mountable to a base on a driven roll, the tip comprising: an exterior surface for engaging material to be reduced;a cavity to receive the base, the cavity including a bottom end, a front end, a front bearing surface in the front end of the cavity to bear against a corresponding front bearing surface on the base, and a bottom bearing surface in the bottom end of the cavity to bear against a corresponding bottom bearing surface on the base, the bottom bearing surface being generally parallel to a centrifugal force experienced as the base spins around the drum, and the bottom bearing surface being transversely offset from the front bearing surface; andan opening to receive a retainer to hold the tip to the base.

49. A replaceable tip in accordance with claim 48 wherein the cavity includes a transition surface that curves from the front end toward the bottom end.

50. A replaceable tip in accordance with claim 49 wherein the transition surface generally matches a shape of an exterior surface of the tip when the tip has experienced wear.

51. A replaceable tip in accordance with claim 48 wherein the exterior surface includes a front surface facing generally in the direction of rotation during use, and the cavity includes opposing surfaces to receive the base, and a rail or groove that extends downward and rearward from the front surface.

52. A replaceable tip in accordance with claim 51 wherein the rail or groove includes bearing surfaces along opposite sides of the rail or groove to support the tip on the base during use.

53. A replaceable tip in accordance with claim 48 wherein the cavity includes opposing surfaces to receive the base, and the opposing surfaces include only a single rail or groove on one of the opposing surfaces.

54. A hammer for a reduction machine, the hammer comprising: a base including a first mounting end for mounting the base to a driven roll of the reduction machine, a second mounting end comprising a front bearing surface and a bottom bearing surface, and an opening;a replaceable tip comprising: an exterior surface for engaging material to be reduced;a cavity to receive the second mounting end of the base, the cavity including a bottom end, a front end, a front bearing surface in the front end of the cavity to bear against the front bearing surface on the base, and a bottom bearing surface in the bottom end of the cavity to bear against the bottom bearing surface on the base, the bottom bearing surface of the replaceable tip and the bottom bearing surface of the base being generally parallel to a centrifugal force experienced as the base spins around the drum, and the bottom bearing surfaces of the base and the replaceable tip being transversely offset from the front bearing surfaces of the base and the replaceable tip;an opening that generally aligns with the opening on the base when the replaceable tip is mounted on the base; anda retainer inserted into the opening in the base and the opening in the replaceable tip to secure the replaceable tip to the base.

55. A hammer in accordance with claim 54 wherein the retainer extends into a single side of the tip.

56. A hammer in accordance with claim 54 wherein the tip has an exterior surface and the opening in the tip for receiving the retainer extends from the cavity to a distance short of the exterior surface.

57. A hammer in accordance with claim 54 wherein the tip and the base experience forces between each other as the tip engages the material to be reduced, the tip and the base have a center about which the tip tends to rock as the tip and base experience the forces, and the retainer is generally located in the center.

58. A hammer for a reduction machine, the hammer comprising: a replaceable tip for a multi-piece hammer, the replaceable tip including a cavity and an opening; anda base including a first mounting end for mounting the base to a driven roll of the reduction machine, a second mounting end for receiving the cavity of the tip, an opening in alignment with the opening in the replaceable tip when the replaceable tip is mounted on the base, and a retainer secured in the opening of the base so that the retainer and the base are maintained as a single integral unit.

59. A hammer for a reduction machine, the hammer comprising: a base including a first mounting end for mounting the base to a driven roll of the reduction machine, a second mounting end, and an opening; anda replaceable tip for impacting the material to be reduced, the replaceable tip including an exterior surface and a cavity to receive the second mounting end, and an opening in alignment with the opening in the base, the opening extending from the cavity to a distance short of the exterior surface; anda retainer inserted into the opening in the base and the opening in the replaceable tip to secure the replaceable tip to the base.