AU720190B2 - A plastic molded trowel handle having fingerguard and palm grip - Google Patents

Description

S F Ref: 26584102

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFCATION FOR A STANDARD PATENT

ORIGINAL

9* Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Marshalltown Trowel Company 104 South 8th Avenue Marshalltown Iowa 50158 UNITED STATES OF AMERICA Curtis Dwight Kelsay Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia A Plastic Molded Trowel Handle Palm Grip t is a full description of this ing it known to me/us:- Having Fingerguard and The following statement best method of perform invention, including the 5845 2 BACKGROUND OF THE INVENTION The present invention relates to a trowel handle and more particularly to a brick trowel handle which is injection molded from two separate types of plastic. A finger guard is integrally molded from a smooth surface thermoplastic resin which serves to protect the user's forefinger and thumb during troweling. An outer palm grip is molded from a thermoplastic rubber having a slightly soft, non-slip, rubber-like feel, surface which serves to provide favorable grippability to the handle and comfort to the user.

Present brick trowels include a flat trowel blade made of metal and have a metal post formed integrally with the blade. The post extends upward "from the blade and extends horizontally to become a tang for connecting the *handle. The handle is typically made of wood, but in recent years some are formed of plastic. The handle is typically cylindrical in shape.

When plastics such as cellulose acetate butyrate are used for the handle, the low coefficient of friction of the smooth outer surface of the handle allows slippage of the trowel in the 25 user's hand, particularly where the hand becomes wetted from perspiration or mortar. A firm grip upon the handle of a trowel is advantageous to prevent the trowel from turning when troweling the mortar or when its edge is being used for splitting or chipping bricks.

In addition, when trowels are used to spread mortar, or in breaking and trimming bricks, the user tends to position his thumb and forefinger against the metal trowel shank to provide better control in manipulating the trowel. The user's hand is thus prone to become chapped and worn and may develop callouses on the finger and thumb. This is particularly true where the metal shank includes one or more angled surfaces. A major factor promoting callousing of the hand is the presence of mortar.

Mortar serves as an irritant by its abrasiveness as well as its chemical effect on the skin.

4 Object of the Invention It is the object of the present invention to overcome or substantially ameliorate the above disadvantages.

Summary of the Invention s There is firstly disclosed herein a trowel, comprising: a flat blade; a shank extending upwardly from the top surface of said blade; a tang extending from said shank; and a handle secured to said tang and extending laterally from said shank, said handle being disposed above the top surface of said blade, said handle including: an inner core formed of a rigid plastic material, a first portion of said inner core being exposed to the user's hand at the end of said core proximal to said shank, said first portion providing a grip surface of a first coefficient of friction with the user's hand; 0. 15 (ii) an outer grip member formed of a thermoplastic rubber material formed onto a second portion of said core and providing a grip surface of a second coefficient of friction with the user's hand, said second coefficient of friction being higher than said first coefficient of friction; and (iii) a rear bumper formed of a hard rigid plastic material, said rear bumper being secured at the end of said core distal to said shank, said rear bumper providing a tapping surface of said hard rigid plastic material.

*a•a ft [R:\LIBLL]09366.doc:TCW Brief Description of the Drawings A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a perspective view of a trowel embodiment of the present invention; Figure 2 is a bottom view of the trowel handle of the trowel of Figure 1; Figure 3 is a side view of the trowel handle of the trowel of Figure 1; Figure 4 is a cross-sectional end view of the handle of Figure 3 taken along line 4-4 in Figure 3; Figure 5 is a partial cross-sectional side view of the distal end of the trowel handle of Figure 3; Figure 6 is an end view of the trowel handle of Figure 2.

a aoa IN:\LiBLLO1 828:PVH 6 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Fig. 1, a trowel 11 is constructed from a flat metal blade 13, a metal shank 15 and a handle 17. Shank 15 is integrally formed with, or is otherwise secured to, the top surface of blade 13 in a conventional manner. Shank 15 extends upwardly from the top surface of the blade providing a metal handle tang 19 which serves as the support structure of handle 17. Tang 19 extends distally from shank 15 and is raised above the plane of blade 13 in a generally parallel disposition thereto. Blade 13, shank 15 and tang 19 are typically forged of metal as one piece.

Referring to Figs. 2, 3, and 4, handle 17 includes an inner core 21 and an outer grip 23. A finger guard 25 is disposed at the proximal end of the handle and a bumper 27 is located rearward at the distal end. Inner core 21 is molded integral with finger guard 25 and may be molded or formed 20 directly onto tang 19. The molding may be accomplished by an injection molding procedure and serves to secure core 21 directly onto metal tang 19. As a result, core 21 and finger guard 25 are formed as a single unitary piece and are held fixed 25 to the trowel tang. Tang 19 extends into the inner core approximately three inches.

The inner core 21, fingerguard 25, and outer grip 23 may be formed initially as a unit and then pressed onto tang 19. The unit is formed with a bore for receiving the tang. The assembly may be facilitated in a number of ways including heating of the bore prior to forcing the unit over the tang.

Inner core 21 and finger guard 25 may be formed from polypropylene. The polypropylene forms a hard, durable finger guard 25 and provides a smooth outer surface 26 to the finger guard 25. The smooth outer surface 26 provides a low coefficient of friction with the users hand permitting the user's forefinger and thumb to freely slide along the surface during manipulation of the trowel without a chaffing drag.

As shown in Figs. 2. and 3, finger guard terminates at a distal end 51 having a circular configuration. From end 51, the inner core 21 extends distally beginning from a proximal end 53 having a circular configuration concentric with and of a diameter smaller than the distal end 51 of finger guard 25. The difference in -diameters 20 between ends 51, 53 provides an offset for housing outer grip 23 such that the outer surface 26 of finger guard 25 is contiguous to and flush with the outer surface 24 of grip 23. This provides continuity of surface between the outer surface of 25 grip 23 and the outer surface of finger guard After the first mold shot of polypropylene has formed inner core 21 and finger guard 25, outer grip 23 is injection molded around the formed inner core 21. Outer grip 23 is generally cylindrical in shape and of a uniform thickness, extending over the majority of the surface area of the handle. Inner core 21 increases in diameter as it extends from its proximal end 53 to the central area of the handle, and thereafter decreases in diameter as it extends to its distal end 28. Distal end 28 need not be covered by outer grip 23, as shown in Fig. Outer grip 23 may be formed from a thermoplastic rubber, for example, Santoprene

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a product of Monsanto Corporation. The surface of outer grip 23 may have a smooth or light texture and be felt as slightly soft or pliable like rubber.

The outer grip provides a non-slip gripping surface 24 for the user's hand. The gripping surface 24 provides a second and higher coefficient of friction with the user's hand as compared to the coeffecient of friction of finger guard 25. Normally the palm of the user's hand together with the user's last 20 three fingers grip the thermoplastic rubber surface.

Rear bumper 27 is a separate piece that is fastened tightly against the distal end 28 of the inner core 21. Rear bumper 27 may be made from a hard, rigid plastic, for example, urethane. The 25 plastic of the bumper is to be able to withstand tapping against brick as is the typical use of the end of a trowel handle by a brick layer.

Rear bumper 27 may be securely fastened to the trowel by many conventional means. As shown in Figs. 5 and 6, bumper 27 includes an aperture passing through it. Aperture 30 is formed of an enlarged cylindrical opening 29 and a smaller concentric cylindrical opening 31. The aperture provides a passage for receiving a screw 37.

An annular stop surface 33 is formed at the base of opening 29 at the interface of, the meeting of, openings 29 and 31. Stop surface 33 engages the head 35 of screw 37 (and a flat circular washer not shown-- which may be used) when the screw is secured into inner core 23. A bore 39 is formed in the inner core 21 (and outer grip 23 should the outer grip be molded over the distal end 28 of the inner core). Bore 39 receives the screw shank 41 for drawing bumper 27 tightly against *09 end 28. Rear bumper 27 protects the thermoplastic rubber outer grip from being destroyed by the continual tapping of the end of the handle against bricks.

Referring to Figs. 2 and 3, finger guard 25 is formed to include a depending member 43 which carries a forefinger engaging surface 45. Member 43 partially wraps around the rearward, or distal, surface of shank 15 co cover the shank 15 as shown in Figs. 2 and 3. Surface 45 provides a wide Ushaped curved surface upon which the user's forefinger may rest during troweling. Finger guard protects the user's finger from direct contact with the shank 15 preventing resulting irritation caused thereby. The outer surface 26 of the finger guard 25 may be smooth in the area of curved surface Finger guard 25 also includes a generally cylindrical section 47 which is slightly tapered from distal end 51 toward the forward, or proximal, end of the handle 17. Cylindrical section 47 presents a cylindrical outer surface which is smooth and upon which the user may rest his thumb for troweling manipulations.

While only a single, preferred embodiment cf the invention has been described hereinabove, those of ordinary skill in the art will recognize that the embodiment may be modified and altered withoudeparting from the central spirit and scope of the invention. Thus, the preferred embodiment described 20 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 or 25 equivalency of the claims are intended to e embraced herein.

Claims (3)

1. A trowel, comprising: a flat blade; a shank extending upwardly from the top surface of said blade; a tang extending from said shank; and a handle secured to said tang and extending laterally from said shank, said handle being disposed above the top surface of said blade, said handle including: an inner core formed of a rigid plastic material, a first portion of said inner core being exposed to the user's hand at the end of said core proximal to said shank, said first portion providing a grip surface of a first coefficient of friction with the user's hand; (ii) an outer grip member formed of a thermoplastic rubber material formed onto a second portion of said core and providing a grip surface of a second coefficient of friction with the user's hand, said second coefficient of friction being higher than said first coefficient of friction; and (iii) a rear bumper formed of a hard rigid plastic material, said rear bumper being secured at the end of said core distal to said shank, said rear bumper providing a tapping surface of said hard rigid plastic material.

2. The trowel of claim 1, wherein said first portion of said inner core is shaped so as to guard the user's finger from said shank.

3. The trowel of claim 1, wherein said hard rigid plastic material is the •go• same material as said rigid plastic material. Dated 29 March, 2000 Marshalltown Trowel Company 25 Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON R 3 \V (A/T [R:\LIBLL09366.doc:TCW