US1301316A - Rotary hammer. - Google Patents

Description

H M. PhMSTED.

ROTARY HAMMiR.

APPLICATION mw mm at. 19m.

Pan-11ml A pr. 22, 1919.

HAROLD I. I'LAISTED, 0F GRANITE CITY, ILLINOIS.

ROTARY HAMMER.

Specification of Letters Patent.

Patented Apr. 22, 1919.

Application filed June 17, 1918. Serial ll'o. 840,898.

To all whom itmay concern:

Be it known that I, HAROLD M. PLAISTED, a citizen of the United States, residing at Granite City, in the county of Madison and State of Illinois, have invented certain new and useful Improvements in Rotary Hammers, of which the following is a specificalion.

This invention relates to certain new and useful improvements in a rotary hammer, the peculiarities of which will be hereinafter described and claimed.

The main object of my invention is the provision of a rotar hammer having one or more wide operative edges and a shank of small relative thickness compared to its width set transversly to said edges like a T, so as to present comparatively little surface to the material being reduced, and to provide means for avoiding interference between said hammers.

In the accompanying drawing on which like reference letters indicate corresponding parts, Figure 1 represents a partial transverse sectional elevation of a reducing machine embodying my invention; Fig. 2 a partial section of the cage taken in an opposite direction, showing the preferred relation of my rotary hammers by an ed view of their periphery; Fig. 3 a detail ace view of a shank of my hammer with its T head; Fig. 4 a similar side edge view of the shank and T head; and Fig. 5 a top view of the head shown in Figs. 3 and 4.

The letter A designates an arcuate cage of any suitable form concentric with a shaft B on which are fastened hammer mounts, preferably consisting of disks C--C supporting hammer rods D on which are pivoted rotary hammers, the pivot 'ends of which are mounted in suitable pockets S formed in said disks.

These hammers consist of flat bar shanks, or other shape in which the thickness is comparatively small with regard to the width. The hammer is so mounted that only this lesser dimension or edge thickness is presented to the material operated on during the forward rotation of the hammer. One end of said shank is provided with a pivot hole E, or other means for pivotally mounting said hammer. There are preferably two of said holes, the other hole E, being located the same distance on the opposite side of a lon itudinal central line F through said shank, as is the center of said hole E.

At the other end of said shank there is provided a cross piece extending laterally outward from each face of said shank in opposits directions and substantially the same distance, so as to form a T head. The lateral pro1ections forming said T-head extend out ward substantially at right angles to the flat faces of the shank; and are likewise of lesser thickness, measured radially throu h the pivot, than the Width measured in t e plane of rotation. The narrow side dimension or radial edge thickness of these lateral projections forming the head is presented to the material being reduced, similarly to the presentation of the side edge of the flat bar shank. By forming a T-head and shank on my rinciple, none of the flat or width of the ar is presented to the material being reduced, but only the side edge thickness or lesser dimension of said bar. My hammer therefore tends to slice through the material being reduced; and likewise tends to avoid carrylng around with the hammer the material'being operated on, as is the tendency with a hammer in which any of the flat, or width of a fiat bar is presented toward the material being reduced. This cross piece is preferably zigzag in plan view as shown in Fig. 5, and is preferably formed, when of this zigzag shape, by splitting the outer end of said shank for a portion of the length along the longitudina center line. and then forcing the respective halves of said end over in opposite directions until they are substantially at right angles to each face of said shank, and with each edge on the respective halves substantially equi-distant from the respective pivot hole center, measured diagonally across said central line F. In a quarter twist hammer the head and shank at the junction are not directl presenting the lesser dimension of the ar to the material being reduced, but inevitably present part of the width of the shank to the material at the junction of head and shank, and thereby carry around with the hammer some of the material and obstruct the slicing action that is desired. It is to overcome this objection in a previous form of hammer in which the head and shank are connected by a quarter twist, that the present T-head is formed directly extending laterally outward on each side of the flat bar shank, substantially as shown. In this zigzag form of T-head in which the cross plate forms the Thead, the operative edges on each side of the shank are 'not directly alined but are zigzag in the preferred form. The cross piece plate head may be otherwise formed however. Four operative edges are thus formed on said cross piece two edges on said sides of the shank G-G being separated substantially the width of the shank, and the other two operative edges being substantially in line with each other and traversing the central line F. In Fig. 3 full lines have been drawn from center of the hole E to the operative edges H and I at the side G, and the center line F, respectively. These lines indicate that these operative edges are substantially equi-distant from the center of the hole E. The dashed lines in the same figure indicate that the operative edges J and K respectively adjacent to the side G and the central line F are likewise e iii-distant from the center of the hole E. Ihis arrangement of the operative ed s causes the cross piece forming the T hea to assume the shape of two bevels as shown in Fig. 3. The action of a forgin machine in forming hammers of this kin will readily swage the split end of the hammer into the shape desired so that the operative edges will be substantially as shown in the drawing.

As will be seen by reference to Fig. 1, the forward operative ed e H is in front of a radial line L from t e shaft through the ivot center E, and the edge I-K is a little hind said radial line,when said hammer is in its normal position under rotation. Thus said forward edges H and I of the T head are substantially the same distance from the ca A, while the rear edge J is a further distance from said cage, due to the bevel of said 1' head and to the eccentric location of the pivot center E. When said hammer is reversed and mounted on the pivot hole E the edges J and K come into similar operation.

The operative ed es above described may be of any kind an shape desired that is, they may be sharp as shown in Fig. 1 throughout their length, or may be serrated with an under cut saw-tooth shape as shown in Figs. 3, 4 and 5; or may be otherwise formed. When the front edges H and I are of saw-tooth shape they are especiall adapted to cutting alfalfa and like material: and by their increased length of cutting edge facilitate the cutting action and make the power required for rotating the hammer's much less than other form of cutting edge. Alfalfa mills however have a tendency to thrown out the material entering the mill, and I have therefore shown the edges J and K as plain or square edge in Fig. 3. and the edges H and I in the opposite direction being formed with saw teeth. When a hammer of this design is mounted in disks as shown in Fig. 2,that

is, with the forward edges of one hammer plain and the following hammer with the forward edges serrated,the action of the hammers is to draw in as well as to cut the alfalfa or like material.

While the forward edge of a hammer of my construction only presents the lesser dimension or edge thickness of the bar to the material being cut and allows the cutting edges to operate upon the material and pass through said material with little obstructions, it is dmirable to extend the cutting edge opposite the sides G and G so as not to lose the benefit of the thickness of the bar. This I do by means of a cut-out or notch M by which the bevel of the operative edge, H for instance, is carried past and through the thickness of the-bar. In the use of a saw-tooth edge, this notch M would be sharpened, as shown at M Figs. 3 and 4, to avoid the alfalfa collecting on the side of the shank.

In a previous construction shown in Patent No. 1,281,829, dated Oct. 15th, 1918, I have likewise shown two pivot holes in the end of a rotary hammer and have claimed them broadly in connection with the operati ve edges there shown.

In Fig. 1 is shown a bearing edge P, and a bearin edge Q, located res ectively beyond, an inside, of the pivot o the hammer in its pocket S formed b a cut-out openin in the adjacent disk. hese edges in sai pocket are ada ted to contact with the side G of said shan and with a contact surface R at the inner end of said shank, ectively, and thus form stops for the oscillation of said hammer in both directions. It is especially necessary to limit the oscillation of hammers havin sharpredges and prevent two hammers hittin each other when one or both rebound, an thus dulling said edges. I avoid such interference by providing the bearing surfaces P and Q located on the wall of the ket as shown in this application. It wil be noted that the bearing surface Q and the contact surface R, that meet when the hammer is on a rebound from the dotted position shown in Fig. 1, are both located radially inside of the pivot on which the hammer is then operating, but are on the op osite side of a radius from the center of t e shaft through said pivot, from the stop or bearing surface P of said pocket. In my 1115 lication above referred to, I have shown such stop surfaces as both located on the same side of the ivot, but in a hammer of the construction s own in which the end that is pivoted is substantially square, I have claimed the location and stop surfaces as shown in this application.

I claim I. A rotary hammer comprising a flat bar shank having two holes at one end for pivotal mounting,said holes being located on opposite sides of a central longitudinal line,and a T-head on said shank having four operative ed es extending transversely in opposite directions from the faces of said shank,each pair of said edges being substantially equiistant from the center of the respective ivot holes, measured diagonally auross t e central longitudinal line.

2. A rotary hammer comprising a fiat bar shank having a pivot hole at one end and a zi zag cross iece forming a T-head at the 0 er end, said head having four operative edges,two of said edges being se arated by substantially the width of said ank, and the other two edges being substantially alined with each other and extending in opposite directions from the respective face of said shank.

3. A rotary hammer comprising a flat bar shank having a pivot hole near one end, and provided with a T-head having a saw-tooth cutting edge adjacent to one side of said shank, and a plain edge ad'aeent to the other side of said shank, su ntially as and for the purpose described. 7

4. A rotary hammer comprising a flat bar shank, havin a pivot hole near one end, and provided at the other end with a T- head having an operative cutting edge adjacent to one side of said shank,-said shank being sharpened for a portion of the side adjacent to said head, substantially as descri 5. The combination with a rotary pivot hammer having art of a side radiall beyond its pivot a apted for contact, an another part of the hammer radially inside of the pivot but on the o posits side of a central line through said shank also adapted for contact, of a disk having a pocket for the pivot end of said hammer,said pocket having bearing edges forming stops limiting the oscillation of said hammer and pre venting interierence with adjacent hammere and located radially beyond said pivot, and radially inside of said pivot respectively but on opposite sides of a radial line from the shaft through said ivot, respectively, substantially as described? In testimony whereof I have aflixed my signature. Y

HAROLD M. PLAISTED.

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