Hammer locking arrangement for impact crusher rotor
United: States Patent Lowe et al.  
 1 HAMMER LOCKING ARRANGEMENT FOR IMPACT CRUSHER ROTOR [75] Inventors: Keith B. Lowe; William R. Gray,  
 both of Appleton, Wis.  
 [73] Assignee: Allis-Chalmers Corporation,  
 Milwaukee, Wis.  
  22 Filed: Jan. 16,1974  
  21 Appl. No: 433,882  
 Primary Examiner-Roy Lake Assistant E.\&#39;un1inerE. F. Desmond Attorney, Agent, or Firm-Arthur M. Streich [57] ABSTRACT An impact crusher is disclosed having a rotor carrying a pair of hammer bars, with each hammer partly within an axially extending peripheral slot diametrically opposite each other. A portion of each leading hammer face within the slot and a facing wall of the slot cooperate to define therebetween a generally cy- [111 3,874,603 [451 Apr. 1, 1975 lindrical cavity parallel to an axis about which the rotor rotates. A two-piece bushing is fitted in the cylindrical cavity at each end of the rotor, and each of the bushings comprises a pair of bushing halves each having a convex semi-cylindrical outer surface. The bushing halves are arranged within the cylindrical cavity with one convex surface engaging the hammer defined portion of the cavity and the other convex surface engaging the slot wall defined portion of the cavity, and with a diametrical plane along which the bushing is split into halves, being substantially parallel to the adjacent leading hammer face. The halves of each bushing define therebetween an internal conical shaped cavity with an apex end pointed inwardly of the adjacent end of the rotor. A frusto-conical plug is inserted into each bushing with apex ends pointed inwardly of adjacent ends of the rotor. A rod passes through central bores in both plugs, and nuts threaded on both rod ends hold the plugs relative to each other. Retaining walls are provided within the cylindrical cavity to limit movement of the bushings inwardly of their respective adjacent rotor ends. Movement of the frusto-conical plugs toward each other therefore moves each pair of bushing halves apart. As each pair of bushing halves move apart their convex outer semicylindrical surfaces move apart and apply forces which are directed radially of the bushings to both push the hammer radially into its slot and tangentially against the back wall of the slot, to securely lock the hammer in its slot.  
 1 Claim, 2 Drawing Figures AIENIEB APR 1 I975 SHEET 1 [IF 2 PATENIEDAPR 1 I915 sum 2 [IF 2 HAMMER LOCKING ARRANGEMENT FOR IMPACT CRUSHER ROTOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to impact crushers which have a rotor carrying hammers arranged to strike and throw rock to disintegrate upon impact with target members spaced from the rotor, and in particular to an improved arrangement for attaching hammers to the rotor.  
 2. Description of the Prior Art It has long been known to provide the rotor of impact crushers with easily replaceable hammers, by inserting the hammers endwise into axially extending peripheral slots which in end view appear as a dovetail (or partial dovetail), and with centrifugal force acting to wedge the hammers into seating engagement with slot walls. An example of such a crusher is the machine shown in a patent assigned to Allis-Chalmers Manufacturing Company, U.S. Pat. No. 1,331,969 of Feb. 24, 1920. However, as explained in U.S. Pat. No. 2,310,758 of Feb. 9, 1943, it was considered desirable to hold such hammers against very large centrifugal forces, by clamping arrangements acting with dovetail slots and having bolts in a plane perpendicular to the rotor axis. Other U.S. Pat. Nos. disclosing such arrangements include 2,747,803 of May 29, 1956; 2,767,928 of Oct. 23, 1956; 2,862,669 of 1958&#39;, and 3,151,816 of 1964.  
  Another clamping arrangement for holding hammers in dovetail slots, involves members having wedging stirfaces and movable by bolts parallel to the rotor axis. There are many U.S. Pat. Nos. showing such arrangements, including 2,192,606 and 2,223,584 of 1940; 2,258,075 of 1941; 2,325,605 of 1943&#39;, 2,373,691 and 2,378,475 of 1945; 2,585,943 and 2,588,434 of 1952; 2,646,224 of 1953; 3,096,035 of 1963; 3,146,961 of 1964; 3,295,773 of 1967; and 3,455,517 of 1969.  
  As will appear from the description ofthe present invention to follow, the object of the present invention is to provide a new and improved arrangement of the last mentioned type. Of the prior patents referred to perhaps the most pertinent to the present invention is U.S. Pat. No. 2,258,075 of Oct. 7, 1941. This prior patent shows several arrangements including one in which a pair of conical members are drawn toward each other along an axis parallel to the rotor axis, to lock hammers with rotor slots.  
 SUMMARY OF THE PRESENT INVENTION According to a preferred embodiment of the present invention an impact crusher is provided with a rotor carrying a pair of hammer bars with each hammer partly within an axially extending peripheral slot diametrically opposite each other. A portion of each leading hammer face within the slot and a facing wall of the slot cooperate to define therebetween a generally cylindrical cavity parallel to an axis about which the rotor rotates. A two-piece bushing is fitted in the cylindrical cavity at each end of the rotor, and each of the bushings comprises a pair of bushing halves each having a convex semi-cylindrical outer surface. The bushing halves are arranged within the cylindrical cavity with one convex surface engaging the hammer defined portion of the cavity and the other convex surface engaging the slot \vall defined portion of the cavity, and with a diametrical plane along which the bushing is split into halves, being substantially parallel to the adjacent leading hammer face. The halves of each bushing define therebetween an internal conical shaped cavity with an apex end pointed inwardly of the adjacent end of the rotor. A frustoconical plug is inserted into each bushing with apex ends pointed inwardly of adjacent ends of the rotor. A rod passes through central bores in both plugs, and nuts threaded on both rod ends hold the plugs relative to each other. Retaining walls are provided within the cylindrical cavity to limit movement ofthe bushings inwardly of their respective adjacent rotor ends. Movement of the frusto-conical plugs toward each other therefore moves each pair of bushing halves apart. As each pair of bushing halves more apart their convex outer semi-cylindrical surfaces move apart and apply forces which are directed radially of the bushings to both push the hammer radially into its slot and tangentially against the back wall of the slot, to securely lock the hammer in its slot.  
  Other features and objects of the invention that have been attained will appear from the more detailed description to follow with reference to an embodiment of the present invention shown in the accompanying drawings.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I of the drawings is a view in elevation and partly in section, showing an impact crusher according to the present invention: and  
  FIG. 2 is an exploded isometric view of a rotor for the crusher shown in FIG. 1.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, an impact crusher is shown which comprises a housing I having disposed within a lower area thereof a rotor 2 mounted on a shaft 3 which is carried by suitable journal bearings 4. The housing 1 defines a material feed opening 5 over a feed chute 6 inclined downwardly toward the rotor 2. The feed chute 6 delivers rock to hammers 7 and 8 which are carried by the rotor 2 in a manner which will hereinafter be described in detail.  
  Chute 6 directs feed rock to rotor 2 at a location where its hammers 7 and 8 are ascending with the result that the impact of hammers 7 and 8 on rock breaks the rock into smaller particles which are thrown upwardly to break into even smaller particles upon impact with a complement of primary target breaker bars 12 and 13 which are carried by the casing I. A secondary crushing occurs when such particles drop downwardly from bars 12 and 13 to be again struck by hammers 7 and 8 and thrown toward a discharge area 14 where the particles impact with a vertical array of secondary target bars 15. Close to the periphery of rotor 2, one or more adjustable and yieldable breakerbars I6, 16&#39; may be arranged. Adjustable and yieldable mounts such as for bars 16, 16 are well known and one example of such mounts is shown in U.S. Pat. No. 2,486,421 of Nov. 1, 1949. Any particles not passing between the bars 15 and into discharge area 14, progress downwardly toward the bar 16&#39; where such particles are subjected to a final crushing as the particles are nipped and urged through the space between rotor 2 and bar 16&#39; to the lowest portion of the discharge area. The casing I may include a pivotal portion 18 connected to base structure 19 by a hinge 20, operative to open the casing and provide access to the internal mechanisms.  
  The rotor 2, shown in elevation in FIG. 1 and the exploded isometric in FIG. 2, will now be described. The rotor may be thought of as comprising an elongated central body portion 23 with a pair of axially extending slots 24, 25 and a pair of diametrically opposed spiral body extensions 26, 27. With reference to FIG. 2, slot 24 is shown as having a leading wall 28, a floor 29 and a back wall 30. The body extensions 26, 27 each project progressively farther radially outward beginning at leading wall 28 of one slot and reaching maximum radial projection at a terminus defining a face 31 planar with back wall of the other slot.  
  First and second hammer means, shown in both FIG. 1 and FIG. 2 as the hammer bars 7 and 8, are each arranged in one of the slots 24, 25, and project outwardly of such slots with a leading hammer face 34 extending outwardly and terminating with an edge 35 outward of slot edge 28 at least as far the radially outer edge of the face 31.  
  Referring now again to FIG. 2, a radial inner surface portion 38 of the leading hammer face 34 of bar 7, is shaped to define a concave semi-cylindrical cavity. The leading slot wall 28 is also shaped to define a concave semi-cylindrical cavity. The surface 38 and the wall 28 therefore cooperate in the assembly to define therebetween a generally cylindrical cavity 28, 38 parallel to shaft 3. A two-piece bushing 39, 40 is provided for insertion in the cylindrical cavity 28, 38 at each end thereof. The two bushing pieces 39, 40 are each halves of a complete bushing and each have a convex semicylindrical outer surface 41, 42, respectively. The two bushing pieces 39, 40 each also have an inner concave surface 43, 44, respectively, which together define a frusto-conical cavity. A frusto-conieal plug is provided for each bushing 39, 40 and each plug 45 conforms to the shape of the frusto-conical cavity defined by bushing surfaces 43, 44. Each plug 45 has a central bore 46 through which a rod 47 may be inserted. The rod 47 is threaded on both ends for engagement with threaded nuts 48, 49.  
  In the assembly of rotor 2, hammer 7 for example is placed in slot 24 on floor 29 and abutting against back wall 30, with wall 38 and surface 38 thereby cooperating to define therebetween a generally cylindrical cavity. One of the two-piece bushings 39, 40 is inserted from each end of the rotor 2 with apex ends of the inner frusto-conical cavities 43, 44 pointed inwardly of adjacent rotor ends. The bushings 39, 40 are moved inwardly until the pieces abut against semi-annular retaining walls 50, 51 in the cavity defined by slot wall 28 and semi-annular retaining walls 52, 53 in the cavity defined by surface 38. The retaining walls -53 limit movement of the bushings inwardly their respective adjacent rotor ends. With the two-piece bushings 39, 40 each abutting against a pair of retaining walls 50, 52 and 51, 53, respectively, the bushing surface 41 is aligned to engage hammer surface 38 and bushing surface 42 is aligned to engage slot wall surface 28, preferably with a diametrical plane XX&#39; (see FIG. I) along which the bushing is split into the halves 39, 40, being substantially parallel to the adjacent slot back wall 30. Referring again to FIG. 2, the frusto-conical plugs 45 are aligned with their apex ends pointed inwardly, and each is inserted into one of the bushing cavities defined by surfaces43, 44. The rod 47 is then inserted through the bores of plugs 45 and the nuts 48, 49 are secured to its ends. i  
  In the operation of the described assembly to secure a hammer, such hammer 7, as the plugs 45 are driven in their respective bushings 39, 40, the plugs 45 are moved inwardly toward each other. As plugs 45 move toward each other, the bushing halves 39, 40 surrounding each plug 45 move apart. Finally, as bushing halves 39, 40 move apart, their convex semi-cylindrical outer surfaces 41, 42 move apart and apply forces which are directed radially of the bushing halves 39, 40 to both push hammer 7 radially toward shaft 3 and into its slot 24, and push hammer 7 tangentially with respect to the central body portion 23 of rotor 2, against the back wall 30 of slot 24, to securely lock the hammer 7 in its SlOt 24.  
  From the foregoing detailed description of the present invention it has been shown how the object of the present invention has been attained in a preferred manner. However, modification and equivalents of the disclosed concepts such as readily occur to those skilled in the art are intended to be included in the scope of this invention. Thus, the scope of the invention is intended to be limited only by the scope of the claims such as are or may hereafter be, appended hereto.  
  The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
  l. A hammer rotor for an impact crusher having an elongated central body portion with at least a pair of axially extending peripheral slots diametrically opposite each other and extending the entire axial length of the rotor, and first and second hammer means each comprising a hammer bar arranged in one of said slots with a portion of a leading hammer face within said slot and a portion thereof extending outwardly of said slot, characterized by:  
 a. portion of the leading hammer face within the slot and a facing wall of the slot cooperating to define therebetween a generally cylindrical cavity parallel to an axis about which the rotor rotates;  
 b. a pair of bushing assemblies in said cylindrical cavity with one located at each end of the cavity and with each said bushing assembly comprising a pair of separate semi-cylindrical bushing halves each having a convex semi-cylindrical outer surface, with the convex surface of one semi-cylindrical bushing half engaging the hammer defined portion of the cylindrical cavity and the convex surface of the other semi-cylindrical bushing half of such a pair engaging the slot wall defined portion of the cylindrical cavity, and said pair of bushing halves cooperating to define therebetween an internal conical shaped cavity with an apex end pointed inwardly of the adjacent end of the rotor;  
 c. A frusto-conical plug within each pair of said bushing halves and arranged with its apex end also pointed inwardly of the adjacent end of the rotor, and movable inwardly of the adjacent end of the rotor; and  
 d. a threaded rod projects through both plugs for engaging means operative to hold the plugs in a position applying uniform locking forces at both ends