US2874912A - Impact hammer - Google Patents

Description

Feb.r24, 1959 c. E. sENNHoLTZ ETAL 2,874,912

IMPACT HAMMER Filedl March 14, 195'/ 2 sheets-sheet 1 Feb.2`4, l959-l c; E. SENNHOLTZ ETAL 2,874,912

Y IMACT HAMMER Filed March 14, 1957 2 sheds-sheet 2 time@ Sees IMPACT HAMMER Charles EVSennholtz and Thomas E. Bridgewater,

` Chicago, Ill.

Application March 14, 1951, `serial No. 646,665 4 Claims. (ci. :4l-i197) This invention relates generally to crushing and pulverizing hammer mills, andmore particularly to a two-piece rotary impacthammerlfor use in suchV devices;

In hammer mills designed for rotary crushing it is well known to mountr'emovable impact hammers on rotatable drums so that the hammersmay be replaced when worn `from service use. However, these hammers are commonly "formed ofmanganese steel andare quite heavy, an average hammer weighing approximately 400 lbs. Therefore, va considerable amount of metal must `be used earch time the head of the hammer becomes too worn for further use. Moreoventhe weight not only makes replacement ldifcult in the actualphysical handling of the hammer,

but also contributes toproducing a considerable centrifugal force during operationwhich requires heavy duty `fastenings tosecurethe hammer to its drum. The need cal toJ operate,` and yet is formed so as to be easily and inexpensively manufactured.

1t is "anotherlbjct tolprovide a two-piece impact hammerfof the""ty`p`ereferredtoabove whose parts are notupset or jammed into engagement bythe normal work- "ing impacttorces to` which it"`is subjected so' that replace* ment of the removablefportion may be readily accomu l"plished even"af`ter""long .periods of use. 1

d It isf a furtherob'jebt "to" provide a two-piece hammer of theaboyecharacter which is locked into operating po sition with nolpossibilityofrelative movement or play'by `a singlejeasilyreplaceable `fastener.`

"Other objects "and advantages of the invention will become` apparent uponi reading the attached detailed .de-

"'scriptionanjd upon reference tofthe drawingsin which:

.Figure 1 showsanexploded perspective view of a two piece impact hammer constructed according tothe present invention g `Fig; 2is apartial endview of the hammer shown in Fig. lm when assembled.

Fig. 3 is"a"fragmentarysectionalview taken along the line`3--3 of FigfZ.` l

Fig. 4 is afragmentary sectional view of the impact hammer of Fig. l assembled and mounted atthe periphery of a rotatable drum. d d

Fig.f5is-afragmentarysectional view taken along the 'line 5 5 ofl Fig. `2.

Fig. 6 is a transverse sectional view taken along line 646 of Fg.5.

Fig. 7 is `a frgamentary bottom view of the replace- -able hammer-head shown in Figpl,

structed according to the` present invention `shown "in partial section.

Fig. 9 is a side view ofthe hammer base designed to cooperate with the head shown in Fig. `8.

Fig. 10 is a transverse sectional view taken along line 1liitl of Fig. 9.

Fig. 11 is a fragmentary plan view of the hammerfbas'e shown in Fig. 9. d Fig. l2 is an end view ofthe hammer headishown'in Fig. 8.

Fig. 13 is an end view of the hammer base and head shown in Fig. 9 in assembled relation. d

Fig. 14 is a perspective view of` a lockingplugiu'sedto secure the hammer `shown in Fig. 13. Y

While the invention will be described in connection with certain preferred embodiments,=it will be understood that l do not intend to limit the invention to such embodiments but, on the contrary, intend to cover 4such alternative embodiments and constructionsas may be included within the spirit and scope of t'he appended claims.

Turning iirst to Fig. 1, there is shown a two-piece impact hammer 10 constructed according to the present invention and consisting of ashank or body portion `11 and a hammer head 12, which is firmly but removably secured onto the shank. in a conventional hammer millaplurality of `such hammers are mounted at the periphery of a rotatable drum 13, a portion of which is shown in'Fig. `4. For attaching the body of the hammer 10 to a drum, the

shank is formed having two longitudinally `extending grooves le and l5, one on each side, which denes an enlarged foot portion .le that is received Within an undercut groove i7 in the drum 1?. The hammer shank 11 is rmly secured within the groove 17` by forming one of the latters walls as a key portion 13 shaped to t within the groove 14 and by providing a removable wedge 19 of similar shape to engage andt withinthe groove 17. The assembly is locked in place by tightening a bolt 21, which is threaded through a hole 2 in drum 13, against `wedge 19 and thus holding the wedge 19, shank -11 and drum 13 rigidly together.

ln accordance with the present invention, the upper rsurface of the shank 11 has a seating surface from which `projects a series of overhanging wedges, and the lower surface of hammer head 12 has'a complementary seating surface with a series of wedge-receiving openingsand a `complementary series of Wedges arranged so that the two series of wedges inter-engage upon relative edgewise lmovement of theshank and head with the seating sur- "faces in Contact, and, thus, firmly lock theheadonto the shank. in the present embodiment, the seating surface 24 on the shank l1 is at and the overhanging series of Wedges 25 extend laterally from a central opstanding ridge 26. For receiving the ridge 26 and the seriesof wedges `12.5, the head 12 has a groove 27 surrounded by a flat `seating surfaced which matches the surface 24 on shank lll. Arranged on each of the side walls of the groove 27 `'are a series ofcomplernentary wedges 30, spaced from one another (see Fig. 7) to allow the ridge 26 and the wedges 25 to pass therebetween.

When the head 12 and shank 11 are to be brought into association, the groove 27 in head 12 is alined with the ridge 26 and the head is lowered so that the wedges 30 are moved on either side of the ridge and between the wedges 25. When the seating `surface 28 rests on the surface 24, the head 12 may be movedlengthwise of the shank to carry the wedges 30 beneath the complementary wedges 25 and thus lock the head and shank together.

It is a feature of the invention that the head and shank of the hammer 10 are locked together without looseness'or play by providing the wedges 25 and 30 with complementary tapering surfaces. In the disclosed embodiment eachwedge 25 has two tapering surfaces 31, 32 and' overlies a third wedge-shaped portion 33 formed integrally with ridge 26 (see Fig. 1). Cooperating with these tapered surfaces are'the surfaces 34, 35 on wedges 30 and wedge portions 36 formed on the sides of groove 27 (see Fig. 6), so that when the shank and head are relatively shifted to lock the wedge 30 beneath the complementary wedges 25, the surfaces 31 and 36, 32 and 35, and 33 and 34 will sliderinto tight wedging engagement against one another and the head 12 will lbe firmly locked on the shank 11.

In carrying out the invention, means are provided to secure the head 30 against sliding movement when the head and shank are locked together so that these parts cannot be separated accidentally. In the first embodiment disclosed, this securing means takes the form of a bolt 40 which may be passed through a ange 41 formed on the head 12 and threaded into a nut which is positioned and secured within the recess 43 formed in the top, and at one end, of the ridge 26. A hole 44 provides access to the recess 43 for the bolt 40. Flange 41 is spaced inwardly from the end of head 12 and the head 11 so that the head of bolt 40 is protected by the surrounding portions of the hammer unit 10 from direct contact with the material being crushed or pulverized. In the present instance, the nut 42 is secured in proper position within the recess 43 by being brazed into place.

To ensure that the head 12 may be slid far enough along surface 24 to be securely wedged into place, the ange 41 and the end of ridge 26 at which recess 43 is located are proportioned so that when they are drawn into abutment -by tightening bolt 40 the head 12 is tightly wedged into proper position on the shank 11. Pursuant to the invention, an alternative form of securing means is shown in Figs. 8 to 13. In this embodiment elements similar to those referred to above in connection with the first modification have been given the same numerical designations with the suflix a added.

In order to secure the head 11a and shank 12a against relative sliding movement a projecting leg 50 is extended downwardly from the head 12a to be received in a rectangular recess 51 that extends through the ridge 26a and into the center of the shank 11a. It can be noted that the recess 51 is substantially longer than the width of leg 50, so'that the leg may be received and longitudinally moved therein when the head 12a is lowered onto the surface 24a and the wedges 25a are passed between, and slid beneath the wedges 30a.

When the head 12a is slid along surface 24a, to the left in Fig. 9, and is locked in full wedging engagement onto the shank 11a, it can be seen that the depending leg 50 will be disposed at the left of the recess 51. To restrain the head 12a against sliding movement in the opposite direction, which would release the head from the shank 11a, a yblocking plug 55 is disposed in the path of leg 50 by inserting the plug in a tapered hole 56 formed through the shank 11a. When tightly wedged into position, the tapered plug 55 snugly engages a notch 57 formed in leg 50 and holds the head 12a tightly wedged onto the shank 11a. So that the plug 55 may be properly positioned, it is formed with a circular flange 57 at its wider end, which engages and fits within a recess 58 on the side wall of shank 11a. Thus, the plug 55 can be properly positioned by driving it home until further movement is prevented by flange 57 being seated within the recess 58. To remove the plug, it is only necessary to strike it from the opposite side of the opening 56 and force it outwardly. When the plug 57 is in its fully inserted position, it can be seen that the hammer 10a can be placed within groove 17 in the rotary drum 15 and the key portion 18 and wedge 19 can snugly engage the shank 11a and thus prevent the plug from being accidentally dislodged as an incident to holding the hammer 10a onto the drum 15.

It will be appreciated that hammers of this type are subjectto violent shock loads during the normal course tion ofthe impact forces, and transverse to the centrifugal force which tends to throw the hammer head outwardly from the rotating drum. Moreover, it will be appreciated that the securing means shown in each of the disclosed embodiments are not called upon to resist the forces imposed on the hammer as an incident to normal operation. And thus these securing means need be only of light duty, easy to manipulate, types which make removal and replacement of a hammer head simple and convenient.

Furthermore, it can be seen that the disclosed hammer head and shank can be conveniently cast as single structural units, which both increases their strength and durability and decreases their cost of manufacture.

While, in the two preferred embodiments shown, each of the complementary wedges 25, 30 and 25a, 30a are formed with matching tapered surfaces so that each is truly wedge-shaped, it will be apparent that only one set of tapered wedges may be utilized with a complementary set of non-tapered wedge blocks without departing from the inventive concept. This is because a wedging action can be obtained when only one of two relatively sliding surfaces is tapered as well as when both such surfaces are tapered.

We claim as our invention:

1. A two-piece impact hammer adapted for luse in a rotary hammer mill comprising, in combination, an elongated shank having an upper seating surface and a longitudinally extending ridge projecting from said surface, a hammer head having a lower seating surface in smooth, uniform engagement with said upper seating surface and havinga groove to receive said ridge, two complementary series of locking members, one series projecting laterally from said ridge to overhang said surface and the other series projecting inwardly from the sides of said groove to snugly underlie corresponding members of said rst series, said locking members of each series being spaced so that the members of one series can pass between the members of the other for permitting said head to be removed from said shank, the mutually engaging surfaces of said locking members being oppositely tapered so as to exert a wedging force holding said head against said seating surface, and the inner edges of the locking members projecting inwardly from the sides of said groove and the side portions of the ridge which said inner edges engage also being oppositely tapered so as to wedge said head into fixed longitudinal alinement on said shank.

2. A two-piece hammer adapted to be mounted on a rotatable drum comprising, in combination, an elongated hammer body having a longitudinal upstanding ridge on its upper surface, an elongated hammer head having a longitudinal groove on its lower surface adapted to receive said upstanding ridge, a first group of spaced wedges projecting from the sides of said ridge, a second group of spaced wedges projecting inwardly from the sides of said groove, the wedges of each group being oppositely pointed and vertically spaced so that the second group of wedges on the head can be slid under the,

first group of wedges on the body so as to wedgingly lock the head onto the body, and releasable means to restrain the head from sliding on said body when the head and body are locked together.

3. A two-piece impact hammer adapted to be mounted on a rotatable drum comprising, in combination, an elongated hammer body having a longitudinal upstanding ridge on its upper surface, an elongated hammer head having a longitudinal groove on its lower surface adapted to receive said upstanding ridge, a first group of spaced wedges projecting from the sides of said ridge, a second group of spaced wedges projecting inwardly from the sides of said groove, the wedges of each group being oppositely pointed and vertically spaced so that the second group of wedges on the head can be slid under the rst group of wedges on the body so as to wedgingly lock the head onto the body, a ilange extending across said groove and spaced from one end so as to define an outwardly facing recess, and means permitting a bolt to be extended through said flange into threaded engagement with said body to restrain the head from sliding on the body when they are wedgingly locked together, the head of said bolt being shielded in said recess from accidental damage.

4. A two-piece impact hammer adapted to be mounted on a rotatable drum comprising, in combination, an elongated hammer body having a longitudinal upstanding ridge on its upper surface, an elongated hammer head having a longitudinal groove on its lower surface adapted to receive said upstanding ridge, a first group of spaced wedges projecting from the sides of said ridge, a second group of spaced Wedges projecting inwardly from the sides of said grooove, the Wedges of each group being oppositely pointed and vertically spaced so that the second group of Wedges on the head can be slid under the first group of wedges on the body so as to wedgingly lock the head onto the body, said body defining .a longitudinally extending groove, a depending leg carried by said head to slide within said last named groove when the groups of wedges are inter-engaged, and a tapered plug inserted through a hole in said body so as to Wedge said leg longitudinally in said groove and thus positively urge and retain said head in locked engagement on said body.

i References Cited in the le of this patent UNITED STATES PATENTS 1,305,311 Sheldon et al. v June 3, 1919 2,065,471 Krider Dec. 22, 1936 2,568,077 Loufek Sept. 18, 1951 2,588,434 Unti et al Mar. 11, 1952 2,620,989 Keiper Dec. 9, 1952

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