US2928444A - Shockless hammer - Google Patents

Description

H. IVINS 2,928,444

SHOCKLESS HAMMER Filed July 8, 1958 Fig: 1

Fig? 2 REBOUN D ENERGY 1 0 45 2p FEET/SECOND IN VEN TOR.

HERBERT L. Ivms BY ATTOR/VEWS SHOCKLESS HAL [MEIR Herbert L. lvins, Brooklyn, Ohio, assignor to Olin Mathieson Chemical Corporation, East Alton, 111., a corporation of Virginia Application July 8, 1958, Serial No. 747,229

9 Claims. (Cl. 145-29) This invention relates to a striking tool or implement for fastenerdriving and more particularly to a masonry type hammer having a novel construction for manually driving a pointed pin or stud into steel, concrete or the like with a minimum number of hard blows and with the least shock to the hand of the person using the hammer.

Nail, sledge and masonry hammers with a solid head rigidly attached to a handle are well known, but where such heretofore known hammers are used, it is a common experience that the shock and vibration to the operator are very tiring and uncomfortable. This is especially so where-the hammer is employed to drive fasteners into highly resist-ant materials such as masonry and steel. In recognition of thisdifliculty, hammers have been devised with springs, with separate movable bodies such as shot or a slug in the head, or with elastically cushioned handles in auction to improve their case of operation. prior devices have not been altogether satisfactory be cause of accompanying serious disadvantages. Some have a-disagreeably multiplied rebound and are subject to frequent breakdown which are more annoying than the type of shock which they reduce. Some fail to deliver a sufficient proportion of the driving energy and, thus, prolong the work. Still others are very ditficult on the working hand of the operator and tend to develop painfulblisters and calluses. I

Therefore, an object of this invention is to provide an improvement in hammers which is characterized both by effective performance as well as ease of operation.

Another object is to provide a hammer characterized by the lease rebound and shock transmission.

Another object is to provide a simple hammer structure including an elastic medium of a special type and in a special position so arranged as to not only dissipate the restitutional energy elfectively, but-to also have substantially no wear and breakage.

Another object is to provide an economical hammer construction characterized by practical elimination of the bounce while being at the same time capable of delivering a blow of maximum energy.

These and other objects which will become apparent from a description of an embodiment of this invention are achieved by providing a special hammer head fitted with a confined but movable elastic member, and a suitable handle. More specifically elastic O-rings and receiving grooves are employed in the head. Just how the objects of'this invention are accomplished will be better understood from the description of the preferred embodiment shown in the drawing wherein:

Fig. 1 is a side elevational view of this embodiment shown partly in cross section;

Fig. 2 is a fragmentary view showing the top of the hammer head of Figure l;

Fig. 3 is an enlarged fragmentary cross section showing the action at an O-ring in the device of Figure 1 during impact;

. Fig. 4 is a graphic representation of the comparative United States was performance characteristics of the device of this invention; and

Fig. 5 is a cross section through the handle grip taken on line V-V of Figure 1;

These I 'In accordance with this invention, a striking device such as a hammer or punch is provided which consists of separated telescoped parts having complementary recesses at which the parts are maintained in operatively connected relationship by intervening deformable means of recoverable shape allowing only limited relative movement of the parts, one of which is the striker and the other a restitutional counter weight. The arrangement is of such a nature because of the masses and elasticity as to eliminate rebound for all practical purposes or at least to reduce it so greatly as to eliminate perceptable bounce of the ram or hammer head. Elastomeric inserts constrained between the recesses are contemplated as connectives. A driving force is applicable in any suitable manner from the countering member to the head but for manual operation a handle is preferred. This is connected to the assembled striker and weight which take the form of a cylinder and surrounding barrel together constituting a head. 'For a hand-tool the handle is further provided with an elastic hand grip, preferable an oval sectioned rubber grip mounted on the opposite end of the handle, preferably a round hollow handle, with the major dimension of the grip aligned parallel with the striking axis of the head. This arrangement adds the least re bound rigidity to the hammer handle and gives the maximum of a super-added shock absorption in the handle to further dampen even the small fraction of residue of restitutional energy not put to good use by means of the afore mentioned special head construction.

As shown in Figures 1 and 2, the hammer head includes a tubular barrel 1 of steel of desired mass and dimensions. For driving fasteners such as pins and studs with penetrating shanks of a diameter of about *3 of an inch more or less into concrete and steel, the barrel is a tube about 2% inches long and about 1% inches outer diameter and about 1%; inches inside diameter leaving a wall of desired weight. The head also includes a solid striker cylinder 2' of steel received in the bore of the barrel and having an' impact head 3 at one end protruding out of the barrel and preferably of enlarged diameter. This mating striker has a diameter of 1 of an inch in the cylindrical shank in the barrel and has a 1 inch diameter head of inch length included in the overall length of 4 /2 inches of the striker. Each of these two parts are recessed at four V- grooves 4 and '5 spaced at intervals of V2 of an inch to a depth of about l of an inch.

The barrel consists of a suitable material such as S.A.E. 1020-1030 steel not heat treated, while the striker is a tough hard material such as SAE. 1045-1050 steel heat treated to a Rockwell hardness of Rc45-50.

The restrained elastic connective inserts 10, 11,12 and 13 are shaped so as to be not only deformable under compression with concomitant lateral distension, but alsov readily rolled even when deformed. Balls or rings of any suitable elastomer such as ordinary rubber, neoprene, silicone rubber, or polyfiuoroethylene are contemplated, pro-.

number are preferred for ease of assembly. The greater the number of rings the heavier the duty which the hammer can withstand, but the greater is the force needed to" press striker 2 into'head 1 with the rings between them. Four ringswere-found preferable for the hand-tool for' the load conditions contemplated. I

The receiving recessesfor' the insert are complementary Patented Mar. 15, 1960 ball-pockets or annular grooves such as the four grooves 4 in the barrel 1 and grooves 5 in striker 2 for the rings.

The sides of the recess are angularly sloped to avoid the total restraint of semi-circular or U-shaped grooves while providing limited' desired action and reaction force dissipating deformation and movement. These sides are shown in the enlarged view-of Figure to be tangential at an included angle of 120 to the inch "diameter" arcuate bottom of the grooves. The spacing -betweenparts 1- and'Z in the barrel-bore is about i of an inch for reception of O-rings having a torus diameter of 1% center to center and 'asection diameter of A1 of an inch; The diameter may be in excess of A of an inch to put the rings under a slight compression-at all times. a ,7

A round tubular handle 6 of about A; iiichouter diameter and inch inner diameter having a length of about 7 /z inches is joined cross-wise at one end-as by "welding at 7 to barrel 1. A rubber sleeve or grip 8 tightly envelops the handle at its other end to remain secured thereon. Grip 8 is of oval section; as shownin V As graphically represented in Figure 4, a hammer constructed with suchrestrained rolling rings (see curve Alwas found to have less rebound thaneitherastand aId masQnryhammer (-seeeurve Bjor .the-nextbest "no-bounce hammer (see curve C), While at the-same means without excessive loss of efiective energy complementary pair of recesses between said" members and maintained therein for compression, said-constrained resilient connection between said members permitting only limited relative movement of the members with respect to each other thereby substantially reducing the rebound of said tool and the shockimparted to said whenever said head is struck. v

2. The hand-tool or claim F'whE'ri'ri'the resilient member is a body shaped for rolling in said recesses and consists of a rubber-like materiatequivalenrto rubber having a Barometer" hardness of about 70. T

3. A hand-tool for striking a bodyisuch'as a pin, stud or the like comprising an outer hollow open-ended member, an inner solid member carried-in said outer member, said inner member having at one end an enlarged striking head, and a handle connected at one extremity to the outer of said members and carrying a resilient:

hand grip mounted at the other 'end, sa id members having-spaced juxtaposed surfaces each of which surfaces has' a plurality of spaced circumferential grooves each complementary to then-rating groove in the surface'of the other-member, and a resilient rubber-like composition ringmember ,of a suitableDurometer hardness wedged in each "of said' complementary-pair of grooves and maintained therein under'confinement; said-head being-longitudinally spaced from the other member surficie ntly' with respectto said n'ng 'members forming a constrained-resilient connection between said membe'rs to J permit: limited longitudinal relative movement-of said, innerand outer members toward each'othcnwithout interfere'nce-of any one memberfwitlftthejot her members, thereby substantiallyreducing therebdundof saidtbol time tests showed that agreater proportion of the. total impact energy (see curve X) was available for useful work withthe hammer of this invention (see curve N) than with the other heretofore available no bounce hammer" (see curve 0,) as compared to the masonry hammer (see curve P). Thus, there-is attained-a high degree of shock isolation and energy .transmittal.- To 7 the tool operator this means; less hazard, inconvenience and -f ati'gue,-- This may-be attributed.- to the high- :eoefficient of friction developed under-compression -the;hysteresis-in-the-elastonier and-to diversion of the-forces to an angle. athwart the axis of striker e The invention in its preferred embodiment takes the form of a hand tool, but it will be unders-todthat ithas advantages when. suitably designed in size for other types of hammers and rams to which operating force may be applied from a.p ower source by any suitable mechanism so" long as the steady pressing force; needed to dissemble the .parts is not exceeded for the particular arrangement which may be varied to suit the operating load' needed. r t a While in accordance with this invention one embodim'ent'now believeli' preferred has been specifically i1.- lust'rated and described, it should be understood that changes and modifications andequivalents thereof may oc'cur'ot those'skille'd in the art and that therefore, the scope and spirit of this invention is' n'otlimitedthereto or thereby exceptfas set forth in the appended claims.-

1. A tool 'for strikingc'om'pris'ing an outer hollow openended member, an 'inner'mernber carri'ed in said and-'shookr-imparted" to the hand orx'the tool? operator while transmitting az high proportien'of'the' energy sup plied, whenever said =head-is-struck against'said body in the-direction of 'said'movement 'th'e' number-of said rings being sufiicient to ettectuatvsaid 'energy; transmission longitudinally'. L i

I 4; An impact device comprising-an outer-hollow barrel, an inner cylinder'carried in' the'bore 'of said barrel, said-cylinder including a striking end; "said barreland cylinder having spaced juxtaposed inner and I 'o'uter' surfaces, respectively, each of which surfaces hasa cir cumferential groove'complementar'y to the otherof said grooVesf andan "elastoniericv O-ring confinedsaid complementary pairof grooves for-rolling undjer com pressiorgJ saidr grooves having angularly sloped sides arranged tangentially to normally-restrain" said-"- O-ring in the-' middle' o'f said; groove while permitting" only limited relative movement of said barrel and cylinder with respect to each other foridiverting the reaction forces at an angle ctothe striking axis and dissipating the energy of restitution in elastic deformation and hys teresis.--

5. The device of 'claim- 4 wherein'theslopingsides of the groove form an angle .of about 120.

6. The device of claim 4 wherein the O-ring: is rubber-having arDurometer hardness ofabout lo.

. 7. The device of elaim4- whereinrthe O ring is of an enlarged-diametersuflicient for: placing the-ring-under compression between said grooves at all times;

outer member," one" of said members including at an endthereof a striking headg' and means connected to the other of. said members for: imparting thereto 'a strik ing force, said members having spaced juxtaposed "SHE'- face's each' of which surfaces has a recess complementary i to therec'es's in the surface ofitlie other member; and a 1 resilient elastic composition member restrained in said 8. A hammer comprising an -open-ended barrel. have ing sides --'of relatively: elastic 'deformability, an; inner rigidscylinder-carried in" the: bore of said barrel and: having a 'striking end isaid barrel and=cylinderhaving hpaced r juxtaposed inner and outer V surface's respecttveiygesclr having about four circumferentiali grooves the grooves V of one "being complementary-to the' grpoves oi the other and-t having tstraightr sides i intersecting at an angle- 0f about a rubber O-ring of a Duronieter hardnessof about -70 disposedin each; complementaryfpair -of grooves, saidangular -sides being tangential to said-ring; thereby putting the ring into rolling motion and rsimnltaneouscompression when saidstriking =end-is impac'tid.

l i a 7 6 9. The hammer of claim 3 wherein the handle is of 1,707,787 Estwing Apr. 2, 1929 circular cross section and the hand grip is of oval cross 2,043,442 McNeil June 9, 1936 section, the major dimension of which is aligned in the 2,678,853 Reeder May 18, 1954 direction of the striking axis of the cylinder. 2,754,863 Yearley July 17, 1956 5 References Cited in the file of this patent 2'757694 1" r 4 Aug 7 1956 UNITED STATES PATENTS 1 FOREIGN PATENTS 1,210,539 Rudd Jan. 2, 1917 r 59,996 r y 1938

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