US3148716A

US3148716A - Impact tool with chip-resistant striking face

Info

Publication number: US3148716A
Application number: US184289A
Authority: US
Inventors: Jr Howard A Vaughan
Original assignee: Vanghan & Bushnell Manufacturing Co
Current assignee: Vanghan & Bushnell Manufacturing Co
Priority date: 1962-04-02
Filing date: 1962-04-02
Publication date: 1964-09-15
Anticipated expiration: 1981-09-15

Description

N k L P 1964 H. A. VAUGHAN, JR 3,148,716

IMPACT TOOL WITH CHIP-RESISTANT STRIKING FACE Filed A ril 2, 1962 INVENTOR. HOWARD A. VAUGHAN, JR.

United States Patent M 3,143,716 IMPACT TGGL WITH C-RESISTANT STRIKING FACE Howard A. Vaughan, 3n, Fontana, Wis., assignor to Vaughan & Bushnell Mfg. (10., Bushnell, Ill., a corporation of Illinois Filed Apr. 2, 1962, Ser. No. 184,289 1 Claim. (Cl. 14529) The present invention relates to portable impact tools and has particular reference to a standard carpenters claw hammer.

As a prelude to a discussion of the present invention, it is to be understood that a standard carpenters claw hammer usually has a 16-ounce head and a handle which is approximately 13 inches in length. The over-all longitudinal extent or length of the hammer head is approximately five and one-half inches. Any material deviation from these dimensions or from such weight of the hammer head will not be tolerated by a carpenter. These dimensions are applicable to hammers of the hickory handle type and also to hammers of the so-called indestructable type wherein the shank portion of the handle is formed of steel and is integral with the hammer head. They also are applicable to hammers employing tubular steel shanks. It follows, therefore, that an appreciable amount of steel is involved in the forging of a carpenters claw hammer, especially a hammer of the indestructible type wherein the head and shank are integral.

In order that the striking face of the hammer head be of such toughness as to resist fracturing or spalling and of such hardness as to resist denting or mushrooming under ordinary circumstances of use, it has heretofore been found necessary, especially in the better grades of hammers, to forge the hammer head or the head and shank in the case of an indestructible type hammer of steel having a high carbon content, for example, 0.80 carbon steel.

The present invention is designed to overcome the limitation that is attendant upon the quality of steel that may be employed in the production of a hammer head to produce a satisfactory striking face, and toward this end, it contemplates the provision of a hammer head, or in the case of an indestructible-type of hammer, an integral hammer head and shank wherein a limited portion of the head in the vicinity of the striking face thereof is separately formed from the main body of the head and is of a superior grade of chip-resistant steel or alloy tool steel.

According to the present invention, the separatelyformed portion of the hammer head is in the form of an insert or tip of chip-resistant tool steel and constitutes an appreciable portion of the impact head proper at the forward or striking end of the hammer head. It is of full Width or diameter in the vicinity of the striking face thereof, but is provided with a shank which is of reduced diameter and projects with a tapered fit into a correspondingly shaped socket in the remaining or main body portion of the impact head proper, the longitudinal axis of the shank of the tip and the socket in the main body portion of the head proper extending in the striking direction of the hammer head as a whole so that the blows which normally are struck by the hammer will tend to drive the shank of the impact tip into tighter engagement with the wall of the socket which receives it. The insert-like impact tip, when in operative position on the main body of the hammer head, provides a hammer head which does not depart noticeably in size, shape or weight from the size, shape and weight of a conventional hammer head so that the hammer as a whole, in the case of a carpenters claw hammer, will meet the exacting requirements of the experienced carpenter who demands 3,148,715 Patented Sept. 15, 1364 that his hammer not only be of correct or accepted proportions, but that it also possesses other less definable qualities such as balance and proper feel.

In United States Patent No. 2,884,969, granted on May 5, 1959 to Clarence M. Lay and entitled Hammer Construction with Shock Absorbing Means, there has been disclosed a carpenters claw hammer, and in connection therewith, a full discussion of the requirements of such a hammer has been given. Reference may be had to such patent for a full understanding of these requirements which need not be set forth in detail herein, suffice it to say that thevibrational effects which are set-up in a hammer after impact are not only objectionable to the sense of touch, but they set up stresses in the body of the hammer head in the vicinity of the claw region, which in time crystallizes the metal in this region so that upon a subsequent occassion when the claws are used for leverage purposes or when continued blows are struck, one or both claws may break-away from the hammer head. Various means have recently been devised for minimizing vibration in the claw region of a carpenters claw hammer, and the present invention, in addition to providing a chip-resistant hammer of higher quality than has heretofore been economically feasible, also presents vibration-inhibiting qualities which afford an appreciable degree of protection to the claw region of the hammer head.

Another phenomenon which is discussed in the aforementioned patent is that of shock-absorption by means of which there is materially reduced the tendency of the hammer and through the hammer head body to the claw region, and then, after a brief period of claw vibration, to return to the hammer head body and from thence travel along the shank portion of the handle to the hand of the user. The present invention in a novel manner further minimizes the degree of shock or sting which ordinarily is imparted to the hand of the user of a conventional claw hammer.

A further feature of novelty which is associated with the present invention resides in the fact that the means which are employed for inhibiting both vibration in the claw region of the hammer and shock to the hand of the user also affords a visual means for distinguishing a hammer which is constructed according to the present invention from hammers not so constructed, this despite the fact that the over-all size, shape, and weight of such hammers are identical.

Finally, it is an advantageous feature of the present invention that by manufacturing the impact tip separately from the main body of the hammer head, as briefly outlined above, the tip may, by reason of its relatively small size, conveniently be handled en masse and annealed, quenched or otherwise heat-treated in its entirety bodily as a unit so that localized operations, such as annealing, hardening, or the like, are eliminated.

The provision of a carpenters claw hammer possessing certain or all of the advantageous features briefly outlined above being among the principal objects of the present invention, numerous other objects and advantages will readily suggest themselves as the following description ensues.

In the accompanying single sheet of drawing forming a part of this specification, one illustrative embodiment of the invention, incorporating the features thereof in a carpenters claw hammer of the indestructible type, has been shown.

In this drawing:

FIG. 1 is a fragmentary side elevational view of a carpenters claw hammer of the indestructible type constructed in accordance with the principles of the present invention with certain parts being broken away in the interests of clarity;

FIG. 2 is an enlarged fragmentary sectional view taken substantially centrally and longitudinally through a portion of the hammer head of the improved hammer; and

FIG. 3 is a sectional view taken on the line 3-3 of FIG. 2.

Referring now to the drawing in detail, and in particular to FIG. 1, the improved impact tool comprising the present invention has, for exemplary purposes, been illustrated as being in the form of a carpenters claw hammer of the indestructible type. As shown in the drawing, the hammer comprises a head and a handle. For purposes of discussion herein, it is contemplated that the hammer is of more or less standard dimensions, i.e., it is provided with a sixteen-ounce head, a thirteen-inch handle, and has a longitudinal spread across the head of five and one-half inches. While other dimensions and weights are contemplated, the weights and dimensions above will, if adhered to, provide a hammer which is generally acceptable to carpenters and similar tradesmen.

The hammer head has been designated in its entirety by the reference numeral and is of a composite nature. It consists of two principal parts, namely, a main body portion 11, and a permanently-aifixed impact tip 12, the nature and function of which will be made clear presently. The main body portion 11 of the head is provided with an integral, laterally extending, shank 13 which forms a part of the handle of the hammer. The head 10 in the illustrated form of the invention is of the bell-faced type and includes a cylindrical impact head proper 14 which is formed in part by the previously-mentioned impact tip 12. The impact head proper 14 is connected to one side of the medial body region 18 of the head 10 by a constricted portion 20 which is polygonal in cross section. The other side of the medial body region 18 of the head is connected to a claw region 22, the latter being bifurcated as at 24 to provide the usual diverging claws 26. The shank 13 merges with the medial region 18 of the head 10 along gradually-formed curved surfaces 28 as is customary in the formation of an indestructible-type hammer. The medial body region 18 of the hammer head 10 is provided with a relatively deep socket 36 which is generally rectangular in cross section and is filled with a vibration dampening substance 32 which may be wood or a suitable thermoplastic or thermosetting resin.

The shank 13 consists of a proximate grip section 34 and a distal connecting section 36 by means of which the grip section is operatively connected to the medial region 18 of the head 10. The distal section 36 is generally elliptical in transverse cross section, the ellipse having a relatively short minor axis and a relatively long major axis so that this section of the shank is relatively thin in the transverse direction of the hammer as a whole. The proximate grip section 34 is generally flat and the longitudinal side edges thereof are formed with marginal ribs 38 so that the section is H-shaped in cross section. The grip section telescopically receives thereover a tubular sheath 40 which may be formed of any suitable material but is preferably formed of a material having good shock-absorbing qualities, as, for example, an elastomer such as rubber. The shank 13 and the sheath 40 together form the handle of the hammer.

The arrangement of parts thus far described, with the exception of the permanently affixed impact tip 12, is substantially the same as the arrangement shown and described in aforesaid Patent No. 2,884,969 and no claim is made herein to any novelty associated with the lastmentioned arrangement. The novelty of the present invention consists rather of the provision of the separatelyformed impact tip 12 at the impact end of the hammer head It) and of its association with, and its mode of connection to, the main body portion 11 of the head of the indestructible-type of hammer selected for illustration herein.

The impact tip 12 is of mushroom-shape design and includes a generally cylindrical striking head 42 and a relatively short, tapered shank 44. The striking head 42 presents a forward, substantially circular, impact face 46 which merges with the cylindrical side face 48 of the tip on a small radius as indicated by the reference numeral 50. The thickness, i.e., the axial extent of the striking head 42, is approximately one-half of the axial extent of the entire impact head proper 14.

The shank 44 0f the impact tip 12 is tapered on a slant angle of approximately 3, and the end face 52 of the shank merges with the frusto-conical side face 54 on a small radius as indicated by the reference numeral 56. This side face 54 similarly merges with the rear or inner annular face 58 of the striking head 42 on a small radius as indicated by the reference numeral 60.

The tapered shank 44 of the impact tip 12 is telescopically received within a tapered socket 62 in the forward or front end face 64 of the main body portion 11 of the head 10, the socket 62 being shaped conformably to the shape of the shank 44. A fiber or other shockabsorbing washer 66 surrounds the shank 44 at the base region thereof and is interposed between the two annular faces 58 and 64. The impact tip 12, the washer 66, and the adjacent portion of the main body portion 11 of the head 16 are so designed that the composite impact head proper 14 formed by these parts is substantially cylindrical and follows the contour of the impact head proper of a conventional carpenters claw hammer of correct or acceptable proportions.

The annular end face 64 of the main body portion 11 of the head 10 merges with the tapered side wall 68 of the socket 62 on a small radius as indicated by the reference numeral 70, and the depth of the socket is such that when the impact tip 12 is driven into position on the end of the body portion 11 with the washer 66 in position between the faces 58 and 64, there is a small clearance or air pocket 72 between the end face 52 of the shank 44 and the bottom face 74 of the socket, this pocket being hermetically-sealed by reason of the tightfriction fit between the shank 44 and the side wall of the socket 62.

According to the present invention, the impact tip 12 is formed of the finest chip-resistant steel obtainable on the market, for example, alloy tool steel which is manufactured and sold under the trade named Wizard.

The main body portion 11 of the hammer head 10 is formed of a lower carbon steel, as, for example, steel having a carbon content as low as .60 or even less. Such a steel is susceptible to the necessary degree of hardening in the claw region 22 in the case of the illustrated indestructible type hammer, or in the peen region of a machinists hammer, for example. The usual heat-treatment and water or oil quenching operations resulting in such localized hardening in the desired regions may be resorted to in accordance with conventional practice. The impact tip 12 of special chip-resistant steel may similarly be heat-treated in any desired manner to obtain the necessary degree of toughness to withstand the shock of impact without fracturing or chipping. The specific annealing or other heat-treatment operations which are performed on either the main body portion 11 or the impact tip 12 form no part of the present invention and these operations will be carried out according to conventional engineering expediencies to impart to the constituent parts of the composite hammer head 10 the desired over-all or localized physical properties.

In assembling the hammer head 10, the shank 44 of the impact tip 12 is driven into the socket 62 so as to have a tight friction or drive fit therein. The union thus formed is intended to be a permanent one, and due to the small slant angle of the mating frusto-conical side face 54 and side wall 68, there will be little danger of the impact tip becoming dislodged from the body portion 11. In fact, each blow that is struck by the hammer when the same is in operation will tend merely to increase the tightness of the fit.

In the aforementioned Patent No. 2,884,969, the deleterious effects of the vibration which is set up in the claw region of the hammer head after each impact have been outlined in detail, and it has also been pointed out how the provision of the socket 30 minimizes such vibration. The Washer 66 which is interposed between the two faces 58 and 64 and the entrapped air within the air pocket 72 absorb some of the impact that is imparted to the impact tip 12 and further minimizes such harmful effects of claw vibration.

As an incidental feature, the washer 66 further provides a means whereby a hammer Which is constructed according to the present invention may be visually distinguished from conventional hammers having one-piece hammer heads. In the absence of the Washer, the line or seam between the striking head 42 of the impact tip 12 and the remainder of the impact head 14 would be indistinguishable. With the washer 66 in position, the impact tip 12 is clearly visible to an observer.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawing or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention. Therefore, only insofar as the invention has particularly been pointed out or defined in the accompanying claim is the same to be limited.

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

In a claw hammer, in combination, a composite hammer head comprised of two principal parts including a main body portion and an impact tip, said main body portion being in the form of a one-piece metallic body and including a medial body portion from which there projects forwardly on one side thereof an impact head proper, and rearwardly on the other side thereof a bifurcated claw region, said impact head proper presenting a forwardly facing end face and having formed therein an inwardly tapered socket arranged so that its large end intersects said end face and embodying a frusto-conical side wall surface of small slant angle, said impact tip being in the form of a one-piece chip-resistant metallic body of tool steel hardened quality and including an enlarged striking head from which there projects rearwardly a reduced tapered shank having a frusto-conical side surface, the slant angle of which is commensurate with the slant angle of said side wall surface of the socket, said shank being press-fitted within said socket, said striking head presenting a forwardly facing impact surface, and a washer formed of relatively soft shock-absorbing material surrounding the shank at the base thereof and interposed between said enlarged striking head and said forwardly facing end face of the impact head the combined thickness of said washer and the depth of said socket being slightly greater than the axial extent of said shank whereby a sealed air pocket is created in the bottom region of the socket when the shank is in position therein.

References Cited in the file of this patent UNITED STATES PATENTS 147,427 Parker Feb. 10, 1874 561,409 Mann June 2, 1896 1,711,505 McCracken May 7, 1929 1,781,344 Salazar Nov. 11, 1930 2,874,738 Lay Feb. 24, 1959 OTHER REFERENCES Materials Handbook, 8th Ed. N. Y., McGraw-Hill Book Co. Inc., 1956, p. 778-780 Copy in Group 330.