US3236463A

US3236463A - Centrifugal hammer and renewable tip

Info

Publication number: US3236463A
Application number: US336415A
Authority: US
Inventors: Thomas A Ratkowski
Original assignee: American Brake Shoe Co
Current assignee: American Brake Shoe Co
Priority date: 1964-01-08
Filing date: 1964-01-08
Publication date: 1966-02-22
Anticipated expiration: 1983-02-22

Description

Feb. 22, 1966 T, A, RATKOWSK] 3,236,463

Thomas abkowski 3 wag, m4 m q-Hzome Feb. 22, 1966 RATKQWSK] 3,236,463

GENTRIFUGAL HAMMER AND RENEWABLE TIP Filed Jan. 8, 1964 3 Sheets-Sheet 2 ;L i "i ;;nve ntor ThomasA- Rm. kowski I M57"? I 4 35/ wall/m, and PM g fi .aq-i-kornegs Feb. 22, 1966 'r, ows 3,236,463

CENTRIFUGAL HAMMER AND RENEWABLE TIP Filed Jan. 8, 1964 3 Sheets-Sheet 5 vii 1 J33, ZI/aiiue, M4 m )qHLorrze 14,6

United States Patent 3,236,463 CENTRIFUGAL HAMMER AND RENEWABLE TIP Thomas A. Ratkowski, Chicago Heights, 111., assignor to American Brake Shoe Company, New York, N.Y., a corporation of Delaware Filed Jan. 8, 1964, Ser. No. 336,415 8 Claims. (Cl. 241-197) This invention relates to two-part hammers for a hammer mill, being of the kind wherein a replaceable tip is removably mounted on the lower end of the hammer shank. This application is a continuation-in-part of application Serial No. 202,181, filed June 13, 1962, entitled, Hammers, now abandoned.

In operating a hammer mill where large size chunks are broken and crushed to smaller size, the tip of the hammer is the part that displays the most wear, and it has become common practice in the art to construct hammers for a hammer mill in such a way that the tip, when unduly worn, can be replaced. The shank of the separable assembly for the most part merely serves to secure the hammer to the mill shaft for rotation therewith, and to locate the tip in proper working position within the mill.

There is not a great deal of room available within the mill for repairing the hammer, and in particular when replacing the tip, it is advantageous to be able to do this quickly without the necessity for removing the entire hammer assembly from the shaft which carries the hammer.

The primary object of the present invention is to enable these desirable ends to be accomplished, and in particular by having resort to a retainer plate welded in place to hold the tip on the hammer, and which can be removed incidental to replacing the tip merely by applying a torch to melt the weldment.

Another object of the invention is to secure a replaceable tip on a hammer shank so that an integral wall of the tip prevents transverse movement of the tip relative to the shank in a first direction, and a slidable wall is interfitted into the opposite end of the tip to prevent transverse movement in the opposite direction of the tip relative to the shank so that a mechanical fastening device merely prevents the inward or vertical sliding movement of the slidable plate. Thus, the interlocking retainer plate rather than the mechanical fastener secures the tip against transverse sliding relative to the hammer shank. More specifically, in accordance with a further object of the invention, a replaceable tip is secured to the hammer shank by a retainer plate which is adapted to interlock with the three side walls of the recess in which the hammer shank is disposed so that a mechanical locking means such as a fastener or detent which merely retains the retainer plate against radially inward movement rather serving to hold the tip on the hammer shank.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and the principles thereof and what are now considered to be the best mode for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

FIG. 1 is a sectional view of a hammer to which the present invention is applied;

FIG. 2 is a view illustrating the parts of the hammer of FIG. 1 in disassembled relationship, the tip of the hammer being partly broken away;

FIG. 3 is an elevational view of a preferred form of retainer plate;

FIG. 4 is an elevational view of another form of retainer plate contemplated by the present invention;

FIG. 5 is a fragmentary sectional detail View illustrating aspects of the retainer plate of FIG. 4 in relation to the tip of the hammer;

FIG. 6 is a fragmentary sectional detail view illustrating the nature of the weldments joining the retainer plate to the hammer tip;

FIG. 7 is a front elevational view of another embodiment of the invention having a retainer plate secured against vertical movement by a bent rod;

FIG. 8 is an end elevational View of the rod and retainer plate of the embodiment of the invention shown in FIG. 7;

FIG. 9 is an end elcvational view of a retainer plate held against vertical movement by a detent;

FIG. 10 is a sectional view of another embodiment of the invention wherein a bolt secures a retainer plate against vertical movement;

FIG. 11 is a front elevational view of the retainer plate employed with the embodiment of the invention shown in FIG. 10; and

FIG. 12 is a plan view of the retainer plate of FIG. 11.

The present invention is illustrated as embodied in a hammer 10, FIG. 1, which includes a shank member 11 and a related tip member 12. The tip is formed with a recess extending downwardly from the top thereof, and the lower end of the shank is nested therein.

The hammer shank or arm 11 is of the type to be secured within a hammer mill for rotation with the rotor of the mill. Usually, the rotor is in the form of a disc or plate having a plurality of shafts or supporting pins of large diameter projecting therefrom for carrying a like number of hammers, and to this end the shank 11 is formed at the head or upper end thereof with a relatively large opening 14 adapted to receive such a shaft or mill pin.

The tip 12 represents that part of the hammer which acts directly on the material that is to be crushed or comminuted within the mill. As a result, the tip 12 tends to wear rather rapidly, and it becomes necessary periodically to replace the tip. The wearing action is so severe that the usual tip is cast from austenitic manganese steel.

The shank member 11 and the tip member 12 have complementally interfitting parts slidably related to enable the tip to be slipped on and off the lower end of the shank, that is, the end opposite the opening 14, and such sliding movement occurs in a direction normal to the longitudinal axis of the shank.

To this end, the lower end of the shank member 11 is provided with a pair of outwardly projecting shoulders or

wings

17 and 18 which project from the leading and

trailing faces

19 and 20 of the mill, considered from the path of travel of the hammer in the mill indicated by the curved arrow in FIG. 1. p The other sides of the hammer shank, such as the side 21, FIG. 2, face the sides of the mill.

As shown in FIG. 1, the wings or

ribs

17 and 18 are positioned above the flat lower face 23 representing the remote face of the shank at the end thereof opposite the shaft opening 14.

The

shoulders

17 and 18 are of dovetail form in cross section for reasons to be explained hereinafter and are adapted to neatly fit in complemental grooves or

slots

24 and 25 located within the hammer tip. Thus, the tip 12 is formed with a relatively large recess 26, FIG. 2, extending downwardly thereinto and terminating in a flat face 28 of the hammer tip. In this connection, it may be noted that the tip is of generous size in comparison to the shank so that there is adequate metal for prolonged use.

In addition to the flat face 28, the tip includes flat vertical fore and aft impacting

faces

30 and 31 considered from the standpoint of the path of rotation of the hammer, and these faces at their lower ends are joined by an arcuate lower face 33 of the tip having a curve substantially complemental to the arcuate interior wall of the mill along which crushing action occurs.

As best shown in FIG. 2, the recess 26 is open at one of the sides of the tip which will face the side plate of the mill. It may further be observed that the cross-sectional geometry of the end of the shank remote from the opening 14 therein, and the complemental geometry of the recess 26, is substantially cruciform. As a consequence, the tip, from the exposed side of the tip, FIG. 2, can be easily slid onto the lower end of the shank in a direction normal to the longitudinal axis of the shank, bringing the mating surfaces of the shank and the tip into fully seated or nested contact.

The excessive centrifugal forces during operation of the mill might tend to encourage spreading of the

end walls

30W and 31W of the hammer tip, but in the present hammer this is resisted by so orienting the upper surfaces of the

projections

17 and 18 as to have the same in

planes

17A and 18A that define acute angles with the

adjacent faces

19 and 20 of the hammer shank.

The primary aspect of the present invention is that the tip is secured against displacement or dismounting relative to the tip, along a path normal to the longitudinal axis of the hammer shank, by a flat retainer plate 35 welded in place at the open side of the tip recess that is visible in FIG. 2. Thus, after the tip has been complementally related to the cruciform end of the shank 11, the retainer plate 35 is positioned in a manner described in detail hereinafter, whereafter weldments are afforded between portions of the retainer plate and adjacent surfaces of the tip to in effect immobilize the tip on the end of the hammer shank.

As was mentioned above, the recess 26 in the tip 12 not only opens at the top of the tip as viewed in FIGS. 1 and 2, but also opens at one of the sides thereof which will lie adjacent one of the side plates of the hammer mill. The opposite side of the recess 26 in the tip 12 is closed by a solid wall 36 that is an integral part of the cast body which is the tip 12.

The

grooves

24 and 25 within the hammer tip recess 26 are defined by spaced

ledge elements

37 and 38, and these are foreshortened in comparison to the width of the

end walls

30W and 31W of the hammer tip. Resultantly, a pocket 12F, FIGS. 2 and 6, of rectangular area is defined at the open side of the recess in the hammer tip, and the retainer plate 35 is dimensioned to fit neatly and entirely therein to afford a wall that closes off the side of the recess 26 that is opposite the wall 36.

Therefore, after the hammer shank and tip have been complementally fitted together, the retainer plate 35 is positioned in the pocket aforesaid, and is to be welded to the tip as will now be explained.

The plate 35 at the face thereof that will be outwardly of the hammer tip is preferably provided with quarterround recesses or pockets 35F at the four corners thereof. These pockets expose adjacent surfaces of the tip 12 when the plate 35 is in place, and weldments W, FIG. 6, can be deposited in such pockets, firmly joining the retainer plate to the hammer tip at the open side of the recess 26 therein. In this manner, the tip is immobilized in its working attitude on the end of the hammer shank.

When it is desired to replace a worn tip under and in accordance with the present invention, it is merely necessary to apply a torch to the aforesaid weldments to melt the same, and the plate 35 can be lifted out of its pocket, permitting the tip to be Withdrawn from the end of the shank in a direction opposite to that in which it was moved onto the shank initially.

As an aid to positioning the retainer plate, it is advantageous to afford a tongue thereon adapted to fit in a corresponding slot in the tip of the hammer in the pocket portion thereof. This will serve to temporarily position the retainer plate during completion of the welding operations.

The modified form of retainer plate is identified by reference character 40 in FIG. 4, such being identical to the retainer plate 35 described above except that a tongue or flange 41 is provided thereon to project from what amounts to the edge thereof which will be adjacent the surface 28 of the hammer tip. As shown in FIG. 5, the tongue 41 is preferably tapered and adapted to fit into a complementally shaped receiving slot 42 formed in the edge of the surface 28 of the hammer ti corresponding to the plate receiving pocket as 12P defined as aforesaid.

In the embodiment of the invention shown in FIGS. 7, 9, and 10, a retainer plate 50 is disposed to interlock with the tip 12 to prevent transverse sliding of the tip 12 relative to the hammer shank or arm 11. That is, rather than Welding a retainer, such as retainer plate 35 to the tip 12, as in the embodiments of the invention illustrated in FIGS. 1 and 2, the retainer plate 50 of these later embodiments of the invention has an interfitting relationship with the tip to prevent the retainer plate moving all but vertically and vertical movement is limited by either a bent rod 54-, a detent 56 or a threaded bolt 58.

The recess 26 in the tip 12 has the cruciform geometry of the hereinbefore discussed embodiments of FIGS. 1 and 2, but the pocket 121 is provided with a recess 60 in the side wall 30W, and a recess 61 in the side wall 31W. The

recesses

60 and 61 are adapted to receive complementary shaped

projections

63 and 64 extending outwardly from the opposite sides of the retainer plate 50, FIGS. 11 and 12. Additionally, the retainer plate 50 is provided with a downwardly extending tongue or flange 65 adapted to be disposed in a complementally shaped receiving slot 66 formed in the edge of the bottom surface 28 of the recess 26 in the hammer tip. Thus, it will be seen that with the shank 11 moved fully into the recess 26 to abut the rear side wall 36 and the retainer plate 50 disposed to close the open end of the recess 26 in the tip 12 the

flanges

63 and 64 will be in their

respective grooves

60 and 61, and the bottom tongue 65 will be in its complementally shaped recess 66. Thus, the retainer plate 50 is interlocked with the tip 12 and the shank 11 cannot be moved transversely relative to tip 12 due to the retainer plate 58 and the blind end wall 36.

For the purpose of mechanically holding the retainer plate 50 against radially inward or vertical movement, that would remove the retainer 51 from closing the end of the recesses 26, the retainer rod 54 has a first end 68 bent transversely over the retainer plate 519 and seated within a grooved recess 69 therefor and has its lower end '70 bent transversely in the opposite direction and seated in a recess 71 therefor in the wall of the hammer shank abutting the interior side '72 of the retainer plate 50. As shown in FIG. 8, the retainer plate 51) is provided with a longitudinally extending groove 74 in the interior wall of the retainer plate 50 extending from the recess 69 and to the recess 71 for receiving the longitudinally extending intermediate portion 75 of the rod 54. To remove the retainer plate 50, the end 68 of the rod 54 is bent to an upward dotted line position, FIG. 8, and then the retainer plate 50 is moved vertically upward so that the tip 12 can be slid transversely to the shank 11.

For the purpose of retaining the retainer plate 50 against vertical movement in the embodiment of the invention of FIG. 9, there is provided a detent 56, which includes a hemispherically shaped ball 76 of metal or the like adapted to be seated in a complementary shaped recess 77 formed in the rear surface 72 of the retainer plate 50 at an elevation to receive the ball 76 when the tongue 65 of the retainer plate 50 is seated in the recess 66. The ball 76 is seated in a recess 79 in the hammer shank 11 and is urged outwardly by a resilient plug 80 of rubber or the like to seat in the recess 77. Preferably, a front face 82 of the retainer 50 is provided with a notch 83, so a pry bar or the like can be inserted in a notch and used to apply sufiicient force to move the retainer plate 50 vertically upward past the detent ball 76.

For the purpose of retaining the retainer plate 59 on the shank 12 in the embodiment of the invention of FIG. 10, a threaded fastener 58 has its threaded portion threaded into a plug of rubber or soft metal 85 in a hammer shank 12 opposite an aperture 86 through which extends the fastener 58 when the retainer plate 50 is properly positioned with its tongue 65 in the recess 66. The threaded fastener 58 is seated in an annular recess 88 so that the head 87 of the fastener 58 is protected during operation of the hammer in the hammer mill.

It will be seen from the foregoing that in accordance with the present invention, the replaceable tip of a twopart hammer of the kind described is quite conveniently immobilized or secured against displacement by a separable retainer plate anchored in place at the open side of a recess in the tip which, initially, enables the tip to be mounted on the end of the shank with a simple movement transverse to the longitudinal axis of the hammer shank. By the same token, it is a relatively simple operation to remove the plate by the use of a torch invariably available. By disposing the plate in a pocket afforded at the open side of the recess, the plate is in effect disposed in a protected position and is not exposed to impact by the material being crushed.

Moreover, it will be seen that a retainer plate 50 is mechanically interlocked with the tip 12 to bear the brunt of attempted sliding of the tip transversely in a first direction and a blind wall 36 prevents transverse sliding in the opposite direction, upward, that is radially inward along a hammer shank attached to a hammer mill, being prevented by a mechanical fastener or detent.

Hence, while I have illustrated and described preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. A two-part hammer of the kind to be used in a hammer mill and comprising a shank member adapted at one end to be supported by a shaft of the mill, and a replaceable tip member formed with a recess extending downwardly from the top thereof and terminating in an upwardly disposed face that bounds the bottom of said recess and in which said opposite end of the shank is to be disposed, said recess being bounded on three sides by an upwardly extending side wall and a pair of opposed end walls, said members having complemental interfitting cruciform parts slidably related to enable the tip to be mounted on said opposite end of the shank, and firmly secured against displacement due to centrifugal forces, by movement of the tip onto the shank in a direction normal to the longitudinal axis of the shank, said interfitting parts including inwardly directed projections on the end walls that extend inwardly of said recess, said recess in the tip being open at one side to enable the tip to be moved as aforesaid and the cruciform parts in the tip being joined to said side wall and terminating short of the open side of the recess in the tip to define a side pocket, and a separable plate adapted to be disposed in said pocket to afford a wall closing off the open side of the recess substantially to immobilize the tip on the shank.

2. A hammer according to claim 1 wherein the plate is recessed at a corner thereof to enable a weld deposit to be laid down therein in contact with an opposed surface of the tip adjacent said pocket.

3. A one-piece cast replaceable tip for a twopart hammer to be used in a hammer mill and comprising a body portion having a pair of end walls each presenting an impacting face generally in a vertical plane in an operative position of the tip, and a lower face joining the firstnamed faces, said body portion having a relatively large recess extending downwardly therein from the top of the tip and terminating in an upwardly disposed face that bounds the bottom of said recess, said recess being bounded on three sides by an upwardly extending side wall and a pair of upwardly extending end walls and being open at the fourth side; inwardly directed projections on the inner faces of said end walls to alford a sliding fit of the tip with the end of a hammer shank having a complemental configuration, and said projections commencing at the inner faces of said side wall and extending but part way along the extent of the inner faces of said end walls thereby to afford a pocket at the open side of the recess of said tip adapted to receive a retainer plate affording a wall at and closing off the open side of said recess.

4. A tip according to claim 3 wherein said projections are tapered in an undercut relationship.

5. A two-part hammer of the kind to be used in a hammer mill and comprising a shank member adapted at one end to be supported by the shaft of the mill and a replaceable tip member formed with a recess extending downwardly from the top end of and terminating in an upwardly disposed face that bounds the bottom of said recess in which said opposite end of said shank is to be disposed, said recess being bounded on three sides by an upwardly extending side wall and a pair of opposed end walls, said recess in said tip being open at one side to enable the tip to be moved on the opposite end of said shank, said shank member and tip member having complemental elements constituting a dovetail when slideably related to each other to firmly secure said tip against displacement from said shank member due to centrifugal force, said recess at said open end extending beyond the hammer shank and including receiving seats in said opposed end Walls and in said bottom of the recess, a separable plate adapted to be inserted into said recess and having portions thereon adapted to be seated in said receiving seats in said opposed end walls and said bottom of said recess to afford a wall closing off the open side of the recess substantially to immobilize the tip member on said shank member, and locking means for locking said retainer plate to said shank member to prevent radial movement of said separable plate from closing 01? said recess.

6. The hammer of claim 5 wherein said locking means includes a detent means having a complementally shaped recess and a resiliently urged ball disposed in opposing faces of said separable plate and said hammer shank to hold said separable plate within said recess.

7. The hammer of claim 5 wherein said locking means includes threaded seat means in said hammer shank and a threaded fastener is disposed through an aperture in said separable plate, and threaded into said seat means to hold said separable plate against radial movement from said recess.

8. The hammer of claim 5 wherein said locking means includes an aperture in said hammer shank, and a key disposed to have one end in said aperture and a main body portion extending along a longitudinal surface of said hammer shank, and said key having its opposite end bent to extend transversely to overlay the upper end of said separable plate to hold said separable plate against radial movement from said recess.

References Cited by the Examiner UNITED STATES PATENTS ROBERT C. RIORDON, Primary Examiner.

Claims

3. A ONE-PIECE CAST REPLACEABLE TIP FOR A TWO-PART HAMMER TO BE USED IN A HAMMER MILL AND COMPRISING A BODY PORTION HAVING A PAIR OF END WALLS EACH PRESENTING AN IMPACTING FACE GENERALLY IN A VERTICAL PLANE IN AN OPERATIVE POSITION OF THE TIP, AND A LOWER FACE JOINING THE FIRSTNAMED FACES, SAID BODY PORTION HAVING A RELATIVELY LARGE RECESS EXTENDING DOWNWARDLY THEREIN FROM THE TOP OF THE TIP AND TERMINATING IN AN UPWARDLY DISPOSED FACE THAT BOUNDS THE BOTTOM OF SAID RECESS, SAID RECESS BEING BOUNDED ON THREE SIDES BY AN UPWARDLY EXTENDING SIDE WALL AND A PAIR OF UPWARDLY EXTENDING END WALLS AND BEING OPEN AT THE FOURTH SIDE; INWARDLY DIRECTED PROJECTIONS ON THE INNER FACES OF SAID END WALLS TO AFFORD A SLIDING FIT OF THE TIP WITH THE END OF A HAMMER SHANK HAVING A COMPLEMENTAL CONFIGURATION, AND SAID PROJECTIONS COMMENCING AT THE INNER FACES OF SAID SIDE WALL AND EXTENDING BUT PART WAY ALONG THE EXTENT OF THE INNER FACES OF SAID END WALLS THEREBY TO AFFORD A POCKECT AT THE OPEN SIDE OF THE RECESS OF SAID TIP ADAPTED TO RECEIVE A RETAINER PLATE AFFORDING A WALL AT AND CLOSING OFF THE OPEN SIDE OF SAID RECESS.