Abstract:
A taping knife which includes a blade with an elongated handle secured to the blade. The plastic handle includes a durable inner member and a grippable outer core. The hollow inner member is formed from adjoining member halves which have an inner structural support network of ribs. The handle component parts sealably interlock and are secured together upon formation of the outer grippable core whose material flows into certain ribbed network compartments and secures the interlocking parts together.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a taping knife and more particularly to a taping knife having an ergonomically shaped handle formed of lightweight, yet strong, interlocking component parts. Furthermore, this invention accepts a hammer head that can be molded in place without the need for a fastener. 
     Taping knives, which have varying blade widths, are used to finish drywall construction projects and create a smooth transition between abutting drywall surfaces. After drywall boards are in place, a smaller (e.g. 4-6 inch) taping knife is generally used to apply a drywalling compound (often referred to as &#34;mud&#34;) and drywall tape to the joints formed by the abutting drywall surfaces. At this stage, unseated nails must also be finally set into the boards. After the mud dries, progressively larger (e.g. 8 inch-14 inch) knives are used to apply more mud to the joint areas. This step is repeated until the joint is sufficiently flat and smooth. 
     A firm grip upon the handle of a taping knife is advantageous to prevent the knife from turning or slipping when smoothing mud or when its handle end is being used to sink nails. Present taping knives often use plastics, such as glass-filled nylons, polyolefins, or wood, for the handle. However, the low coefficient of friction on the smooth outer surface of the handle allows slippage of the trowel in the user&#39;s hand, particularly where the hand becomes wetted from perspiration or mud. 
     When taping knives are used to spread mud, the user tends to grasp the body of the handle with three to five fingers. The index and middle fingers are often extended forward, towards or resting on the blade, for added control of the angle and pressure of the blade&#39;s working face as presented to the work surface. The user&#39;s fingers and palm are prone to become chapped and may develop callouses wherever slippage or chafing occurs between the handle and the hand. A major factor promoting callousing of the hand is the presence of mud. Mud serves as an irritant by its abrasiveness as well as its chemical effect on the skin. 
     Present taping knives often use injection moldable plastics, such as glass-filled nylons or polyolefins, for the handle. However, when hollow plastic handles are used, watertight seals must be maintained around the joints in the component plastic parts because the complete tool is often submerged in water for cleaning. If water leaks into the handle&#39;s hollow cavities, then the weight advantage of a hollow structure may be reduced significantly. Often the manufacturing and final assembly processes, to achieve the necessary tolerances for proper handle assembly with watertight seals, become complex and expensive. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to overcome the deficiencies of prior art taping knives which make use of solid plastic, metal, wood or other handle materials, or which make use of hollow materials with expensive or ineffective component part seals. 
     It is a further object of the present invention to provide a taping knife with a grippable, non-slip outer surface. 
     It is a further object of the present invention to provide a taping knife which utilizes the outer grippable material to secure the assemblage of the handle&#39;s component parts. 
     It is a further object of the present invention to provide an improved taping knife in the combination of handle, the backing-plate and blade. 
     These and other objects are achieved in a taping knife having a lightweight, hollow handle with interlocking parts and inexpensive watertight seals. 
     In one embodiment, the handle is ergonomically shaped to fit the user&#39;s hand. The handle consists of lightweight, yet strong, component parts. The parts include an inner member of hollow adjoining halves with inner structural ribs, a protruding ridge on one half which is received by recessed groove on the opposite half, an endcap, a hammering head, and an outer grip member. The outer grip member surrounds areas of maximum exposure to the user&#39;s hand, secures the hammering head against the endcap, and seals the inner member assembly. 
     In one embodiment the handle can be injection molded from two separate types of plastic, where the outer hand grip is molded from a thermoplastic rubber having a slightly soft, non-slip, rubber-like surface which provides a favorable grippability to the handle and added ergonomic comfort for the user. The inner member of the handle, as molded from a harder, stronger plastic, provides inner strength for mounting the knife blade and subsequently using the tool. 
     In one embodiment, an inner member can be formed from polypropylene which provides a strong, durable, and resilient blade mounting surface. The friction of the polypropylene, relative to the friction of the outer hand grip, can be controlled by varying the finish on the exposed portions of the inner member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a taping knife embodiment of the present invention. 
     FIG. 2 is an exploded view of the taping knife blade and backing plate. 
     FIG. 3 is a side view of the proximal blade securement region of the taping knife handle. 
     FIG. 4 is a 3--3 cross sectional view of the taping knife of FIG. 1. 
     FIG. 5 is a 6--6 cross sectional view of the taping knife of as shown in FIG. 4. 
     FIG. 6 shows enlarged portions of the 6--6 cross sectional of the taping knife handle as shown in FIG. 4. 
     FIG. 7 is an exploded view of the handle endcap and hammering head components. 
     FIG. 8 is a side view of the hammering head component. 
     FIG. 9 is an top view of the hammering head component. 
     FIG. 10 is a end view of the hammering head component. 
     FIG. 11 is a 11--11 cross-sectional view of the adjoined inner member halves of the taping knife handle of FIG. 4. 
     FIG. 12 is an enlarged cross-sectional view of the adjoined inner member halves of FIG. 11 where the protruding ridge of the outside wall ridge is received by the opposing recessed groove. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a taping knife 11 is constructed of a flat metal blade 13, a backing-plate 15, and a handle 17. Handle 17 is ergonomically shaped and comprised of a proximal blade securement region 19, a distal region 15, a distal endcap 21, a hammering head 23, an outer grip member 25, and a grippable portion 140. Outer grip member 25 provides a soft, grippable, rubber-like material in areas of maximum exposure to the user&#39;s hand, forming grippable areas. A hanging hole 27 extends through handle 17 and provides space for a cord, thong, or string (not shown) to be threaded though hole 27. Alternatively, hanging hole 27 may be threaded over a hanging bracket for sales viewing or for storage. Referring to FIG. 2, blade 13 is rectangular in shape and has a thin dimension. A proximal section 29 of the blade is located nearest to the work surface (not shown) during blade use, and a distal section 31 of the blade provides an area for mounting to backing plate 15. Distal section 31 includes a series of five or more blade-mounting holes 33, spaced along the width of the blade. Backing-plate 15 includes a proximal section 35 which is of the same width as blade 13, and a distal section 37 which is curved at its corners 39, 41. Proximal section 35 is thicker than distal section 37 and terminates in a blade-receiving slot 43 for receiving distal section 31 of blade 13. Slot 43 bifurcates proximal section 35 of backing-plate 15 along its entire length. Slot 43 extends deep enough distally within section 35 to receive and encompass blade-mounting holes 33. A stamping operation is used to force portions of section 35 at the slot interface into blade-mounting holes 33, rigidly holding blade 13 to backing-plate 15. The stamping operation creates indentations 45. Distal section 37 of backing-plate 15 includes a pair of backing-plate holes 47 for use in mounting the backing plate to handle 17. Referring to FIGS. 1, 3 and 5 handle 17 is formed of an inner plastic core member 49 about which outer grip member 25 is formed. As shown in FIGS. 4 and 5, core member 49 is integrally molded as one piece with blade securement region 19. 
     As shown in FIG. 5, inner member 49 is comprised of two adjoining member halves 51, 53. Each half includes an inside surface 55, an outside surface 57, an outer wall 58, and a structural rib network 59 extending between the two inside surfaces 55 of each half 51, 53 so as to provide structural support to handle 17. The structural ribs 59 are integrally formed with the inside surface 55 of member halves 51, 53. 
     As shown in FIG. 4, outer wall 58 of member half 51 includes a centered, protruding ridge 120 which extends around the perimeter of outer wall 58 of member half 51. Ridge 120 extends from ridge end 122 distally to ridge end 124, and from ridge end 126 distally to ridge end 128. Outer wall 58 of member half 53 includes a corresponding centered, recessed groove 130 which extends around the perimeter of outer wall 58 of member half 53 (mirroring ridge 120 of FIG. 4). 
     As further shown in FIG. 11, when member halves 51, 53 are joined, groove 130 receives ridge 120 to provide a seal around the perimeter of the joined member halves 51, 53. FIG. 12 shows an enlargement of the interlocking ridge 120 and groove 130. 
     Referring back to FIGS. 4 and 6 each member half 51, 53 also includes a pair of guide posts 61, 63 and a pair of corresponding guide receiver tubes 65, 67 which align with mirrored tubes and posts of the other member half. Posts 61, 63 and tubes 65, 67 further assure proper alignment and mating of the member halves 51, 53. 
     Referring again to FIGS. 1 and 3, blade securement region 19 of handle 17 terminates at its proximal end with a plate-receiving slot 69 for receiving backing-plate 15. As shown in FIGS. 1, 4 and 5, section 19 includes a pair of backing-plate fastening holes 71, which extend through both member halves 51, 53. As shown in FIGS. 4 and 5, holes 71 align with a pair of backing-plate fastening hole walls 73. 
     Referring to FIG. 4, inside surface 55 of each adjoining member half 51, 53 includes a least one structural rib 75 connecting axially with backing-plate fastening hole wall 73 for added support in mounting the combination of backing-plate 15 and blade 13. 
     Additionally, backing-plate fastening hole 71 aligns with backing-plate mounting hole 47 (FIG. 2) upon mounting of backing-plate 15 in plate-receiving slot 69. A rivet 77 (FIG. 1) secures backing-plate 15 to inner member 49. A first circumferential flange 74 extends from outside surface 57 of inner member 49 and is located in proximal blade securement region 19 where plate-receiving slot 69 terminates at its distal end. 
     Referring to FIGS. 4-6, inner member 49 terminates at its most distal end 15 in a flat surface 80. A second circumferential flange 81 extends from outside surface 57 of inner member 49 in distal region 15. As shown in FIG. 6, flange 81 has an outer surface 95 which extends proximally forward from flat surface 80 and parallels the proximally expanding shape of inner member 49. Flange 81 has a maximum outer diameter 82 (FIG. 6) at the most proximal end of flange 81. 
     Distal region 15 also includes at least one enclosed compartment 83 as formed from structural ribs 59 of inner member 49. Compartment 83 is formed proximally forward from surface 80 and lies substantially proximal of flange 81. At least one access hole 84 leads into each enclosed compartment 83 through outer surface 57 of member halves 51, 53. Surface 80 includes a first tongue-receiving slot 87 which extends proximally forward through structural ribs 59 and into compartment 83. Tongue-receiving slot 37 includes a proximal and a distal end. 
     Referring to FIG. 1 and FIGS. 4-7, an endcap 21 is formed of a plastic material which is the same as the material forming inner member 49. Endcap 21 includes an inner surface 90 and an outer surface 91. Endcap 21 also includes a proximal end 27, nearest to inner member 49, and a distal end 28. 
     Referring to FIG. 7, endcap proximal end 27 terminates in an endcap wall 92 which has an inner diameter 93 and outer diameter 94. Inner diameter 93 is larger than maximum outer diameter 82 of flange 81. Endcap&#39;s inner surface 90 is substantially similar to flange outer surface 95 so that endcap 21 fits conformingly over flange surface 95. Endcap 21 also includes a lip 100 extending inwards around the circumference of inner surface 90, with lip 100 being flush with terminating endwall 92. Lip 100 hooks onto the proximal end of flange 81 and allows endcap 21 to lock into place, thus easing further assembly of handle 17. Referring to FIGS. 6 and 7, endcap 21 also includes a flat surface 98 terminating its distal end. Surface 98 includes a second tongue-receiving slot 96 which aligns with first tongue-receiving slot 87 of inner member 49. 
     Referring to FIGS. 8-10, a hammering head 23 includes a proximal end 105, nearest to inner member 49, and a distal end 106. Hammering head 23 is usually formed from metal. Hammering head 23 includes a generally convex headcap 107 and a tongue 108 which extends proximally from headcap 107. Tongue 108 terminates proximally with notches 109 on each side of tongue 108. Referring to FIGS. 4-6, tongue 108 extends proximally a sufficient distance to place notches 109 inside contained compartment(s) 83 of inner member 49. 
     Referring again to FIG. 1 and FIGS. 4 and 5, outer grip member 25 extends from endcap wall 92 to first circumferential flange 74, where the material comprising grip member 25 abuts and seals against these surfaces. Also, upon formation of outer grip member 25, member 25 material flows into and is forced through access holes 84 which lead into enclosed compartment(s) 83. As a result, member 25 material fills compartment(s) 83 and encloses proximal end 105 of tongue 108 and tongue notches 109 (FIG. 6). Upon filling notches 109 and compartment(s) 83, member 25 material, when hardened, seals and secures hammering head 107 firmly against endcap 21, thus completing distal region 15 assembly of handle 17 without need for further adhesives or fasteners. 
     Referring again to FIGS. 4, 11 and 12, the sealing receipt of ridge 120 into groove 130 prevents outer grip member 25 material from flowing into unintended structural cavities. For instance, outer grip 25 material is intended to flow only into compartments(s) 83. Without the seal achieved by ridge 120 and groove 130 around the perimeter of inner member halves 51, 53, outer grip 25 material might leak, and/or be forcibly introduced, into hollow inner member 49. This would negate any weight advantages gained by using a hollow inner structure. 
     Referring to FIG. 6, hanging hole 27 is aligned with a hanging hole wall 110. Hole wall 110 terminates in an annular rim 111 which extends outward from outside surface 57 on each member half 51, 53. Outer grip member 25 surrounds and seals against rim 111, so as to provide a relatively flush surface for contact with the user&#39;s hand. 
     While only one preferred embodiment of the invention has been described hereinabove, those of ordinary skill in the art will recognize that the embodiment may be modified and altered without departing from the central spirit and scope of the invention. Thus, the preferred embodiment described hereinabove is to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced herein.