US3186456A

US3186456A - Industrial hammer

Info

Publication number: US3186456A
Application number: US172641A
Authority: US
Inventors: Clarence O Glasgow
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-02-12
Filing date: 1962-02-12
Publication date: 1965-06-01
Anticipated expiration: 1982-06-01

Description

June 1, 1965 c. o. GLASGOW 3,186,456

INDUSTRIAL HAMMER Filed Feb. 12, 1962 2 Sheets-Sheet 1 m m a ggsg um 4 l. .3396 i V Quwmqx v M i NbQnSW xkan 1 7 mm L 7'70 NEYS June 1, 1965 c. o. GLASGOW INDUSTRIAL HAMMER 2 Sheets-Sheet 2 Filed Feb. 12, 1962 INVENTOR. CLAEE-NCE- 0a L/zsaaw United States Patent 3,186,456 INDUSTRIAL HAMMER Clarence 0. Glasgow, 2620 S. Yorktown, Tulsa, Okla. Filed Feb. 12, 1962, Ser. No. 172,641 1 Claim. (Cl. 145-49) The present invention relates to impact tools and more particularly, but not by way of limitation, relates to a utility hammer having a novel chuck for rigidly connecting either compressible or incompressible impact faces to a handle, and to a plurality of replaceable, special purpose impact faces cooperatively connected thereto, and further relates to new and improved soft impact faces especially adapted for use in the utility hammer.

As is well known in the art, many different types of jobs exist in industry and around the home which require special purpose impact tools. For example, it may be desired to deliver an impact blow to a material having a soft surface which is not to be ruptured or marred, such as a rubber tire or a piece of expensive metal machinery, in which case a soft-faced hammer must be used. Or, it may be necessary to strike a metal object, such as a nail, with a metal hammer in a locality where sparks would create a fire hazard. In this case, the face of the hammer must be fabricated from special non-spark producing metals. Or the impact head may be required to have a special shape, such as a large and flat face for automobile body work; various shapes of sharpened edges for industrial cutting and scraping, or for meat cleavage and plant pruning around the home; a spherical or ball-peen shape for industrial use; or a large flat face having a multitude of relatively sharp projections protruding therefrom for tenderizing meat in the market or at home. The many different uses to which a hammer can be put if it is provided with a specialized impact face make a utility hammer having a multitude of interchangeable, special purpose impact faces highly desirable, provided the utility hammer is of the same or better quality as a single purpose hammer, the special utility heads are easily interchanged, and the utility hammer may be economically manufactured.

Many attempts have heretofore been made to provide a hammer having replaceable impact faces. These hammer constructions have usually employed a chuck for securing the replaceable impact faces to the hammer handle, or more correctly, securing the impact faces to the impact mass of which the chuck usually constitutes a substantial portion, and of securing the impact mass to the hammer handles. Of the many different hammer chuck constructions heretofore developed, almost all are plagued by the difficult problem of securing the impact face in place in the chuck in such a manner that it will remain secure after severe use.

One of the most useful special purpose hammers is that which is provided with a so-called soft face. Many relatively soft materials have been used to fabricate softfaced hammers such as, for example, rubber, plastic, leather, fiber, wood, lead, copper, brass, and various other metals and metal alloys. Impact heads or faces formed of the soft metals usually perform with varying degrees of efliciency the specific functions desired, but have the objection of being nonresilient so that the face of the metal becomes excessively marred and deformed by use. Also, after excessive pounding, the soft metallic impact faces are permanently deformed at that part of the face which is secured in the chuck, which results in an insecure or loose connection to the chuck. A chuck which would securely hold a replaceable soft-metal impact head would be highly desirable because the face could be easily and economically replaced when permanently marred and deformed.

"ice

Perhaps the most extensively used material for softfaced hammers is rubber, which because of its high resiliency and elasticity enables it to Withstand pounding without permanent loss of shape. However, the surface of the rubber is susceptible to punctures and lacerations and cannot be used on sharp objects without destruction of the impact face. But an even greater disadvantage of all types of rubber heretofore used for fabricating hammers is the inherent high spring or rebound constant of the rubber. The high rebound constant produces an exaggerated bounce or rebound each time that the rubber impacts a solid object, or in terms of the physical sciences, results in a highly elastic collision in which relatively little energy is lost by the impact. Therefore, when a solid object is struck a hard blow, the rubber hammer rebounds to such an extent as to be hard to control, which is a hazard to the person using the hammer and to those around him, and also is likely to damage machinery or other articles which may be positioned close to the solid object being hammered. t

From the above discussion, it will be evident that the various types of impact faces fall into two rather general categories as to the type of materials used for fabricating the special purpose impact faces. The impact faces will either be fabricated from a relatively compressible material, such as rubber, or from a relatively incompressible material, such as metal. In order for a chuck to securely grip both types of faces, and still rigidly grip the handle of the hammer by a single adjustment, it must be sulficiently adjustable to compress the rubber, or compressible material, and also tightly clamp the handle, or be relatively larger in order to grip the incompressible metal while still tightly clamping the handle. This in eifect requires two modes of adjustment, one for clamping the impact faces, and one for clamping the chuck onto the hammer handle. Yet the chuck should preferably have but one adjusting member, such as a bolt, to both securely clamp the impact faces in the chuck and the chuck onto the hammer in order to promote ease of changing the impact faces and also economy of construction.

The present invention effectively solves the above dis cussed problems and several others which will hereafter become readily evident by the provision of a novel chuck means which is adapted to attach various impact faces to a hammer handle and which is especially well adapted to attach a compressible, very low rebound rubber to the handle of the impact tool as well as incompressible, metal impact faces. Another very important aspect of .the present invention is the provision of a novel low rebound impact face fabricated of butyl rubber. The butyl rubber is characterized by a very low rebound constant such that when the butyl rubber impact face strikes an object, the butyl rubber will absorb the force of impact Without producing an elastic rebound of the impact mass of the hammer.

More specifically, a preferred embodiment of the chuck means is comprised of first and second complementary mating jaws disposed on opposite sides of a handle. Transverse bores are provided in the mating jaws and are aligned with a bore in the handle, and a threaded bolt is inserted in the bores to securely clamp the mating jaws into rigid abutting relationship with the handle. One or more tapered threaded bores are formed by the mating jaws, the threaded bores formed by the mating jaws each defining a segment of a circle having parallel chords and having a dimension parallel to the bolt less than the diameter of the bore perpendicular thereto when the jaws are in abutting relationship against the handle. Each of the impact faces is provided with a threaded shank portion which is threaded into the bore in the mating jaws of the chuck so that when the threaded bolt is tightened, 'the impact'bodies will be securely clamped between the jaws. It is further contemplated by this invention to provide a series of novel utility heads which can be inserted in the novel chuck to provide a utility hammer which can easily be used for various specific functions in industry or around the home. 7

Therefore, it is an important object of the present in vention to provide an improved utility hammer.

It is also an important object of the present invention to provide an improved soft-faced impact tool having substantially no rebound as a result of impact with a solid structure.

Another important object of the present invention is the provision of a novel chuck which is especially adapted to securely clamp either one or two resilient or compressible impact faces, one or two relatively incompressible impact faces, or a combination of a resilient impact face and an incompressible impact face. a Still another important object of the present invention is the provision of a chuck of the type described which is of a very simple and economical construction and yet which is adjustable in two nodes so as to rigidly connect the chuck to the hammer handle and also to either a resilient or an incompressible impact face.

Still another object of the present invention is the provision of a utility hammer having a wide variety of specif- 1c uses.

Another object of the present invention is to provide a chuck of the type described which will securely hold an impact face or head against loosening even after prolonged use, and in particular, one which will securely hold a rubber impact face or head of the type described in such a manner that the force of impact will tend to further tighten the impact face.

Another important object of the present invention is the provision of a novel, long-wearing, soft impact face fabricated from rubber, plastic or other moldable synthetic material having a surface reinforced by a strong fabric, such as nylon, molded or otherwise bonded to the surface of the impact face.

Another important object of the present invention is the provision of an impact tool of the type described which can be economically produced on a mass production basis.

Many additional objects and advantages will be evident to those skilled in the art from a reading of the following detailed description and a perusal of the accompanying drawings which, taken in conjunction with the appended claim, constitute a disclosure of preferred embodiments of the present invention.

In the drawings:

FIG. 1 is a sectional view taken along the longitudinal axis of the impact mass of an impact tool constructed in accordance with the presentinvention.

FIG. 2 is a partial sectional view taken substantially on lines 22 of. FIG. 1.

FIG.' 3 is a cross sectional view taken on lines 3-3 of FIG. 1 showing some detailsof construction in dotted line.

FIG. 4 is a sectional view taken along the longitudinal axis of an impact face of the impact tool of FIG. 1.

FIG. 5 is a side view of another impact face for the impact tool of FIG. 1.

FIG. 6 is another view of the impact face of FIG. 5.

FIG.'7 is a plan view of still'another impact face for u the impact tool of FIG. 1.

FIG. 8 is a side view of the impact face of FIG. 7.-

FIG. 9 is a side view of yet another impact face for the impact tool of FIG. 1. V

FIG. 10 is a side view of a toolhead which may be used in combination with the tool ofFIG. 1 to convert the impact tool into a wrench and illustrates the broad utility of the device of FIG. 1.

FIG. 11 'is a longitudinal view of the toolhead of FIG. 10 oper-atively secured in the device of FIG. 1.

Referring now to the drawings, and in particular to FIGS. 1, 2 and 3, a utility hammer is indicated generally by the reference numeral 10. The utility hammer 10 has an elongated handle 12 which may be fabricated from metal, such as aluminum alloy'or stainless steel, or from a suitable synthetic plastic, and preferably has a rectangular cross section as can be seen in FIG. 2. An enlarged handgrip portion 14 having an oval-shaped cross section (not shown) may be formed in any suitable manner on the handle 12, such as, for example, by molding a synthetic material between plates 16 and 18 in the desired contour. One end of the elongated handle 12 is provided with an aperture or bore 20 which extends transversally through the handle for receiving a tightening bolt as hereafter described.

The utility hammer 10 has what may generally be de scribed as an impact mass indicated generally by the reference numeral 22. The impact mass 22 is comprised of a chuck, indicated generally by the reference numeral 24 and preferably two impact faces indicated in FIGS. 1 and 2 by reference numerals 26 and 218. The chuck 24 is comprised of first and second

mating chuck jaws

30 and 32 which 'are disposed on opposite sides of the handle 12. The mating faces of the

chuck jaws

30 and 32 are provided with grooves 33 and 34, respectively (see FIGS. 2 and 3), which receive the handle 12. The grooves 33 and 34 are dimensioned to closely receive the handle 12 and are of such a depth as to engage the handle 12 before the adjacent or mating faces of the

chuck jaws

30 and 32 come in contact so that the chuck may be rigidly. fastened to the handle 12 as hereafter described in greater detail.

The

mating jaws

30 and 32 have bores 36 and 38, respectively, which are aligned one with the other, and with the bore 20 in the handle 12. The bore 36 is provided with a counterbore 44), while the bore 38 is preferably provided with internal threads 42 The bore 38 may or may not extend completely through the chuck jaw 32, as desired. A threaded bolt 44 may then be passed through the bore 36 and through the bore 20 in the handle 12, and threaded into the bore 38 substantially as shown in FIGS. 2 and 3. The bolt 44 is preferably of the Allen head type, the head 45 of which is reecived in the counterbore 40. By tightening the bolt 44, the

mating jaws

30 and 32 of the chuck 24 can be drawn tightly against the handle 12 to rigidly clamp the chuck 24- around the handle 12 and also to securely grip the impact heads 26 and 28 as will presently be described in greater detail.

The

mating jaws

30 and 32 of the chuck 24 form threaded bores 56 and '52 for receiving the impact faces 26 and 28. The threaded bores 50 and 52 preferably have their axes aligned along a common line which intersects the bore 20 in the handle 12. The threaded bores 50 and 52 are so constructed as'to form a' pair of segments of a circle having parallel chords when the chuck jaw-s 30 and 32.are securely clamped around the handle 12. The threaded bores are round only when the chuck jaws 3t) and 32 are spaced'apart from the handle 12 in order to provide a clampingadju'stment as hereafter described. The

bores

50 and 52 may easily be made as described by any one of several methods. The

jaws

30 and 32 may be spaced apart the desired distance while the bores 54) and 52 are being drilled and tapped. Or, the

bores

50 and 52 may be drilled and tapped in a single piece of metal and then the single piece of metal sawed to form the

chuck jaws

30 and 32 and the grooves 33 and 34 then machined to the proper depth. In this case, the metal cut away by sawing the single piece of metal to form the

jaws

30 and 32 will result in the bores being segments as described when the

jaws

30 and 32 are abutted against the handle 12. Or, the mating faces of the

chuck jaws

30 and 32 can be planed or otherwise machined down after the

bores

50 and 52 are drilled and tapped with the jaws in abutting relationship. When any one of these three methods is used to drill and tap the

bores

50 and 52 in the

mating jaws

30 and 32, it will be evident that in order to establish a perfectly round bore so that a round threaded shank, to be presently described, can be easily screwed into either of the bores, it will be necessary to space the mating jaws 30 and 32 a slight distance apart. This can be accomplished by loosening the threaded bolt 44. Then when the shank of the impact face has been threaded into the bore, the bolt 44 can be tightened to securely clamp the shank of the face in place.

In accordance with an important aspect of this invention, the

bores

50 and 52 are preferably tapered from a larger diameter at the open end of the bores to a smaller diameter at the innermost end of the bores. In this regard, the taper of the

bores

50 and 52 and the threads used therein may conveniently be standard tapered pipe threads used in the pipe industry. The

threads

54 and 56 are continued to the innermost end of the

bores

50 and 52, respectively, Where flat bottom faces 58 and 60 are provided which receive a substantial portion of the force of an impact blow applied to the impact faces 26 and 28, respectively, as will hereafter be described in greater detail.

To further clarify the configuration of the threaded bores which are formed in the

mating jaws

30 and 32 of the chuck 24, these bores are formed by complementary grooves 61 in the opposed faces of the jaws 3t) and 32, which grooves are each formed on the periphery of a sector of a cone derived by passing a plane through the cone parallel to, and spaced from, a line extending from the apex of the cone perpendicular to the base thereof. Thus each of the grooves 61 extends through an arc of less than 180 and tapers inwardly toward the center of its respective jaw.

Impact faces 26 and 28 have threaded shank portions 62 and 64, respectively, which are sized to be threaded into the

bores

50 and 52, respectively. Of course, the threaded shank-s 62and 64 are tapered to the same degree as the

bores

50 and 52. The shank portions 62 and 64 are sufficiently long as to extend into contact with the

bottoms

68 and 60 of the

bores

50 and 52. As closely as is practical, the impact head portions may have

annular shoulders

66 and 68 which abut the outer faces of the chuck means 24 into which the

bores

50 and 52 are drilled at approximately the same point of travel as that at which the ends of the shank portions 62 and 64 abut the inner faces 58 and 60 of the

bores

50 and 52. However, it is preferred that the end of the shank port-ions 62 and 64 contact the

bottoms

58 and 60 of the respective bores at or before the shoulder engages the chuck face.

In accordance with an important aspect of the present invention, the impact faces 26 and 28 may be molded or otherwise fabricated of butyl rubber. The butyl has the unique characteristic of being resilient but substantially inelastic in the sense that the butyl rubber has a very low spring constant. The butyl rubber used for this purpose may be almost any of the many recipes produced by the Enjay Company, Inc., under the tradename Enjay Butyl. The butyl rubber impact faces 26 and 28 will absorb an impact blow, or conversely, will deliver an impact blow, without causing an elastic rebound of the impact mass 22 of the hammer 10. Yet the resiliency or softness of the butyl rubber impact faces 26 and 28 will not mar the surface of almost any material.

Referring now to FIG. 4, which is a cross section of the impact face 26, for example, the body of material indicated by the reference numeral 70, is covered by a layer of nylon fabric 72 which is molded or otherwise bonded to the surface of the body of material 70. The sheet of nylon fabric may be of any suitable weave so as to be pervious to the uncured rubber material and is preferably pretreated to promote bonding with the butyl rubber. The nylon fabric 72 may then be easily pressed into the mold and actually molded in the surface of the butyl rubber or other synthetic resin. The butyl rubber or resin will then extrude or otherwise pass through the nylon woven fabric 72 and form a very thin protective coating of material between and around the nylon fabric threads to securely bond the nylon fabric to the impact surface of the impact face. Of course, the nylon fabric is exceptionally strong and is highly resistant to puncture by sharp edges which the impact faces 26 and 28 may contact. Yet the nylon is sufliciently pliable as not to interfere with the resiliency of the butyl rubber. Therefore the nylon fabric cover 72 provides a novel and very tough impact face which will not mar or destroy most any of the surfaces or devices which it may be desired to hammer; and conversely, will not itself be as readily lacerated or destroyed by contact with a sharp, relatively hard metallic edge or the like. Yet the impact face fabricated of the butyl rubber will completely absorb the force of impact Without producing a dangerous and undesirable rebound of the hammer.

Although the particular use of butyl rubber for an impact face is, as mentioned, a principal objective of the present invention, it is to be understood that plastic or other synthetic materials of varying hardness may be utilized for the impact faces 26 and 28 in order to provide a soft-faced hammer which will not mar various surfaces, such as metal. These plastics or synthetic resins may have varying degrees of resiliency and may feel as hard as metal to the touch. Yet the plastics are much softer than metal and accordingly will not mar the finish on a metal product. At the same time the protective nylon fabric cover 72 which is molded or otherwise bonded to the surface of the plastic material from which the body of material 70 may be fabricated will protect the impact face from destruction. The impact faces 26 and 28 may also be fabricated from any desired metal, and particularly useful metal heads may be fabricated from special, Well-known metal alloys, such as Amico alloy, which will not produce sparks. Or, of course, steel, brass, or lead may be utilized for well-known purposes.

Referring now to FIGS. 5 and 6, another special purpose impact face is indicated generally by the reference numeral 80. The impact face is to be used in combination with the chuck means 24 and the handle 12 in the same general manner that either of the impact faces 26 and 2-8 is utilized as hereafter described. The impact face 89 is preferably fabricated from steel or a similar hard metal and has a threaded shank portion 82 of the same size as the shank portion 62 of the impact face 26, for example, so as to be threadably received in either of the threaded bores 50 or 52. The impact face 80 has an elongated, sharpened blade portion 84 and a wedgeshaped body portion 86, and thereby forms what is commonly known as an ax or hatchet. The impact face 80 can be used in industry in any manner that an ax or hatchet can be used, and can be used conveniently around the home as a meat cleaver or pruning device for trees, shiubs, and the like.

Referring now to FIGS. 7 and 8, an alternative impact face for tenderizing meat is indicated generally by the reference numeral 90. The tenderizing face preferably has a large impact area 92 so that the force of impact will be spread over a greater area to both increase the efficiency of the tool and also reduce the force of impact to any one spot. The impact face also has a threaded shank 94 adapted to be received in the

bores

50 and 52. The impact area 92 has a large number of sharp pointed projections 96 thereon which may conveniently take the conventional form of small pyramids, substantially as illustrated. It will be noted that the edges of the impact area 92 will extend substantially beyond the edges of the chuck 24 when the threaded shank portion is inserted in one of the bores 59 or 52. Therefore, should the impact face 90 by chance strike a slanting blow, one edge of the area. 92 will contact the meat or the pounding board first so that a severe torque or twisting force will be exerted on the'coating threads in the respective bore and on the shank 94 tending to pry the opposite side of the shank 94' out of the bore. However, due to the threaded connection between the shank and bore and the clamping action of the two

chuck jaws

30 and 32, as hereafter described, the twisting forces due to slanting blows will be effectively resisted so that the meat tenderizing face 90 will be securely held in the chuck 24, even after prolonged use.

Referring now to FIG. 9, an impact head, indicated generally by the reference numeral 1%, is in the conventional form of a ball-peen hammer. The impact head 101] has a tapered threaded shank 102 adapted to be threaded into either of the

bores

50 or 52 of the chuck 24. The impact head 1% may be fabricated of steel or other hard metal and has. asp-herically-shaped impact surface 104. The ball-peen hammer may be used in the conventional manner as required in industry. Again, as hereafter described, the special construction of the chuck tend to prolong the life of the shanks. Obviously, the butyl rubber shank cannot become loosened by use.

When it is desired to secure an impact face formed of incompressible material in the chuck'24, it will be appreciated that the

chuck jaws

30 and 32 will not be capable of compressing the threaded shanks 62 and 64 in order to permit the jaws 3t) and 32 to be clamped tightly against the handle 12. However, since the

bores

50 and 52 and the shanks 62 and 64 are provided with tapered threads,'the incompressible impact faces can be only partially inserted in the bores 51 and 52 or backed-out of the bores until the jaws can be tightened against the handle 12 to provide a rigid structure. The flex or resiliency of the

chuck jaws

30 and 32 will still tightly clamp the threaded shanks to prevent loosening. Impact of the face will merely tend to further tighten rather than loosen the threads. The increased area of contact and interlocking shoulders formed by the threaded connection will 24 readily holds the ball-peen hammer head 106 secure, 7

even against the glancing blows which from use of such a hammer.

' Referring now to FIG. 10, another utility head for use in combination with the chuck 24'and handle 12 is indicated by the reference numeral 111 The head 11% has a threaded shank 112 which is adapted to be received in either of the threaded bores 51) or 5-2 of the chuck 24 as described. The head 11! has any suitable conventional ratchet mechanism (not shown) housed within the head portion 114. A square male ratchet coupling 116 protrudes from the sideof the housing. A control lever 118 is provided to control the ratchet 116 and permit operation of the ratchet in either direction in the conventional manner. It will be noted that the ratchet coupling frequently result 116 protrudes from the side of the head 11!? at substantially a righ t angle to the shank portion 112. It will'be appreciated that since the bolt 44 can be tightened to securely clamp the shank 112 in any position between the

jaws

30 and 32 of the chuck 24, the head 111 may be rotated until the male coupling 116 is positioned at 90 degrees to the handle 12 and the head 11d securely clamped in place. The male coupling 116 may be connected to any conventional socket 120 (see FIG. 11) and the tool then operated as a ratchet wrench.

In order to secure an impact face molded of resilient material, such as butyl rubber, in the chuck 24, the bolt 44 is loosened and the

jaws

30 and 32 separated at least until the

bores

50 and 52 are round. Then the impact faces 26 and 23 may be easily screwed into the bores until the ends of the threaded shanks 62 and 64 abut the bottom faces 58 and 6d of the

bores

50 and 52 respectively. Then thebolt 44 is tightened until the

jaws

30 and 32 are rigidly clamped on each side of the handle 12. The frictional grip of the clamped jaws 3d and 32 together with the fact that the sides of the grooves 33 and 34 closely fit the handle 12 and the bolt 44 passes through the handle 12 rigidly and securely connects the chuck 24, and therefore the impact mass 22, onto the handle 12. Since the

bores

50 and 52 are of a slightly smaller dimension in a direction parallel with the bolt 44 than the diameter of the shanks 62 and 64 of the impact faces When the

chuck jaws

30 and 32 are clamped tightly around the handle 12, the resilient or compressible butyl rubber shanks 62 and 64 will be slightly compressed to securely lock the impact faces against loosening. When the butyl rubber faces 26 and 28 impact an object, the impact will compress and tend to expand the threaded shanks 62 and 64. Since the threaded shanks 62 and 64 are completely contained within the respective bores 59 and 52, the shanks tend to become even more tightly retained in the threads of the bores. The butyl rubber is therefore protected against internal shear forces and is subjected only to bulk compression within the bore, which securely hold all types of impact faces, such as the an face 81), the meat tenderizer face 90, or the ball-peen head 1% and the ratchet wrench head 11%).

It will also be noted that the synthetic resin of various hardness will also be compressible to various degrees. However, the tapered threads of the

bores

50 and 52 and the tapered shanks 62 and 64, for example, provide an adjustment which permits a single bolt 44 to securely tighten the chuck jaws 3t? and 32 against both the handle 12 and the shanks of the particular impact face being used.

From the above detailed description, it will be evident to those skilled in the art that a new and novel tool having great utility has'been described. A new and novel hammer having a relatively soft face which will not mar or harm very soft articles and materials has been described. Yet the novel soft-faced hammer will not produce any appreciable rebound as the result of impact with a solid object. The soft-faced hammer may be provided with a novel protective covering which contributes long life, even when used under severe conditions, to the relatively soft butyl rubber material from which the soft-faced hammer is fabricated. The novel protective covering for the softfaced hammer may also be used in combination with other synthetic materials or plastic resins which are relatively much harder than the butyl rubber, yet still softer than metals upon which the hammers may be used. Such synthetic plastics are normally relatively easily chipped along the edges. However, the bonded or embedded protective nylon covering greatly increases the life of the special purpose plastic impact faces. In theevent the special purpose faces do become damaged and unsuitable for use, the low cost impact heads may easily, quickly, and economically be replaced in the chuck merely by loosening the Allen head screw 44 and unscrewing the impact head from between the jaws Btl and 32. Also, by supplying a number of synthetic resin impact faces of varying hardness, a hammer having almost any degree of hardness is immediately available to the industrial worker.

It will be evident to those skilled in the art that a new and novel chuck has been disclosed which is especially adapted to securely hold a butyl rubber impact face for severe use, and. which is also particularly well suited for securely holding the various special purpose impact faces herein described and forming a part of the present invention. The novel chuck coacts with the threaded shank of the butyl rubber impact face to secure the rubber impact face against loosening because the shank 62 of the impact face 215, for example, is completely contained within the bore 50 of the chuck 24. Therefore, upon impact of the face 26 with an object, the body of rubber will not expand to loosen, but instead will expand and tend to tighten the threaded connection between the shank 62 and the bore 51?. In addition, the shank 62 is securely clamped in the bore 51 between the mating jaws 3t and 32 of the chuck which are tightly drawn together by the threaded bolt 44. Further, the bores 51? and 52 are tapered so that an impact force on the resilient impact face will be more evenly distributed to each of the threads rather than being borne almost entirely by the first thread. The tapered threads are particularly advantageous when a nonresilient or substantially non-resilient impact face is used, such as a face fabricated of metal or of the harder synthetic resins. In such a case, any movement of the face as a result of impact can only more tightly wedge the end of the threaded shank against the bottom of the respective bore. Also, the tapered threads more evenly distribute the force of impact to the inclined surfaces of the threads, thereby preventing damage to any particular thread. It will be noted that substantially the entire threaded area of the shank portion of the particular impact face being used is in frictional contact with threaded area of the mating jaws of the chuck to prevent loosening. In addition, as mentioned, the chuck jaws are tightly clamped on the shank of the impact face to further increase the frictional grip of the chuck on the shank of the impact face. It will be noted that the novel chuck, in addition to being particularly well adapted to hold a resilient face of butyl rubber, is also particularly well adapted to hold the special purpose impact faces. The many side forces which act on the threaded connection between the chuck bore 50 and the shank portion of the respective special purpose faces during normal use thereof are well resisted by the manner in which the respective shanks are gripped by the chuck and coating threads, as described above.

Having thus described the preferred embodiments of the invention, it will be evident to those skilled in the art that various changes and substitutions can be made therein without departing from the spirit and scope of my invention as defined by the appended claim.

What is claimed is:

A hammer comprising:

(a) an elongated handle having a rectangular cross sectional configuration near one end thereof; and further having an aperture passing therethrough normal to a first pair of opposed parallel faces on said rectangular portion of the handle;

(b) a chuck mounted on said handle, said chuck comprising:

(1) a first longitudinally extending jaw member having opposed parallel ends joined by a substantially fiat surface on one side of said first jaw member and by an arcuate surface opposite said substantially flat surface, said arcuate surface extending through an arc of less than 180, said first jaw member being further characterized by:

(i) a transverse rectangular groove formed in the central portion of said flat surface for receiving said handle, said groove having a depth equal to a distance less than half the thickness of said handle;

(ii) an aperture in said first jaw member passing through the center of said groove and said arcuate surface, the portion of said first jaw member aperture adjacent said arcuate surface having a countersink formed therein, and

(iii) a threaded, shank-receiving groove formed in each of said parallel ends, each of said threaded grooves decreasing uniformly in cross section from the respective end of said jaw member toward the central portion thereof, said threaded grooves each extending through an arc of less than 180, with said arcs being formed on a figure of revolution;

(2) a second longitudinally extending jaw member having opposed parallel ends joined by a substantially flat surface on one side of said second jaw member and by an arcuate surface opposite said substantially flat surface, said arcuate surface extending through an arc of less than 180, said second jaw member being further characterized by:

(i) a transverse rectangular groove formed in the central portion of said flat surface, said groove being substantially identical with the groove formed in the flat surface of said first jaw member, and adapted to cooperate therewith to receive said handle,

(ii) an aperture passing through the center of the groove formed in the flat surface of said second jaw member, said second jaw member aperture being threaded and adapted to be aligned with the corresponding aperture in said first jaw member, and

(iii) a threaded, shank receiving groove formed in each of said parallel ends, each of said threaded grooves in said second jaw member being substantially identical to the corresponding threaded grooves in said first jaw member and adapted to cooperate therewith to form a socket;

(c) a partially threaded bolt having an enlarged head passing through the countersink of the aperture in said first jaw member and the aperture in said handle and threaded into the threaded aperture in said second jaw member; and

(d) an impact face carried in each socket formed by the cooperating shank-receiving grooves in said first and second jaw members, said impact faces having a threaded, tapered shank portion of circular cross section, and being dimensioned to threadably engage the socket in which it is carried.

References Cited by the Examiner UNITED STATES PATENTS 974,021 10/ 10 Blake. 1,441,903 1/23 Balaziuk 3 X 1,737,497 11/29 Gibbs 14536 FOREIGN PATENTS 501,310 2/39 Great Britain. 575,211 2/46 Great Britain.

OTHER REFERENCES Nupla Hammers, New Plastic Corporation, 1026 North Sycamore, Los Angeles 38, Calif, Catalog No. 5451 (page 2 relied on).

WILLIAM FELDMAN, Primary Examiner.