Patent Publication Number: US-7895923-B2

Title: Wrench with reinforced hollow handle

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation-in-part application of U.S. patent application Ser. No. 11/675,757 filed on Feb. 16, 2007, now U.S. Pat. No. 7,444,905, of which the entire disclosure is incorporated herein. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a wrench with a hollow handle and, more particularly, to a wrench with a reinforced hollow handle. 
       FIG. 1  illustrates a conventional wrench including a head  1 , a neck  2 , and a handle  3 . The head  1 , the neck  2 , and the handle  3  are integrally formed by forging, and each has a solid structure, which results in high manufacturing cost and a heavy wrench. The solid handle  3  is the largest element of the wrench, and, thus, a burden to the user, which may lead to low working efficiency. 
     The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a wrench with a reinforced hollow handle directed towards reducing weight and cost of manufacturing thereof, but does so in a way that does not give up structure rigidness. The wrench includes a head portion, a hollow handle portion, and a neck portion between the head portion and the handle portion. The handle portion includes a front portion having a wall thickness greater than a wall thickness of a rear portion, and a necking portion between the front and rear portions has a wall thickness greater than the wall thickness of the rear portion and smaller than the wall thickness of the front portion. The handle portion further includes an open rear end defining a rear end opening at the rear portion thereof. Furthermore, in order to avoid depression of the handle portion resulting from a holding force, the handle portion is made having hardness above 30 Rockwell C Hardness (HRC). 
     In one aspect of the present invention, the handle portion has increased wall thickness from the rear portion toward the front portion thereof. 
     In another aspect of the present invention, the handle portion has an open rear end. 
     In yet another aspect of the present invention, the handle portion has hardness greater than 30 Rockwell C Hardness (HRC). 
     The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The illustrative embodiments may best be described by reference to the accompanying drawings where: 
         FIG. 1  is a partly-cutaway perspective view of a conventional wrench having a solid handle. 
         FIG. 2  is a perspective view of a wrench with a reinforced hollow handle in accordance with a first embodiment of the present invention. 
         FIG. 3  is a cross-sectional view taken along line  3 - 3  in  FIG. 2 . 
         FIG. 4  is a cross-sectional view illustrating a second embodiment of a wrench with a reinforced hollow handle of the present invention. 
         FIG. 5  is a cross-sectional view illustrating a third embodiment of a wrench with a reinforced hollow handle of the present invention. 
         FIG. 6  is a cross-sectional view illustrating a fourth embodiment of a wrench with a reinforced hollow handle of the present invention. 
         FIG. 7  is a cross-sectional view illustrating a fifth embodiment of a wrench with a reinforced hollow handle of the present invention. 
         FIG. 8  is a perspective of a wrench with a reinforced hollow handle in accordance with a sixth embodiment of the present invention. 
     
    
    
     All Figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the Figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiments will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood. 
     Where used in the various Figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “third”, “front”, “end”, “portion”, “section”, “radial”, “annular”, “rearward”, “inward”, “circumference”, “thickness”, and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A first embodiment of a wrench according to the preferred teachings of the present invention is shown in  FIGS. 2 and 3  and includes a head portion  10 , a handle portion  30 , and a neck portion  20  between the head portion  10  and the handle portion  30 . 
     The neck portion  20  includes a front, larger end contiguous to the head portion  10  and a rear, smaller end contiguous to the handle portion  30 . The neck portion  20  and the head portion  10  are integrally formed through a forging process, whereas the neck portion  20  and the handle portion  30  are integrally formed through a frictional welding process including a step that one of the neck portion  20  and the handle portion  30  is rotated with respect to another of the neck portion  20  and the handle portion  30  about an axis and a step that the neck portion  20  and the handle portion  30  are moved along the axis brought into pressure engagement to produce frictional heat therebetween and soften and deform contacting portions of the neck portion  20  and the handle portion  30 . As best shown in  FIG. 3 , an interconnection  22  between the neck portion  20  and handle portion  30  clearly indicates the result of this process. 
     The head portion  10  is solid except a compartment  13 , which extends therethrough and is intended to receive a gear wheel or the like. The neck portion  20  is solid except a groove  21 , which extends axially from the rear end thereof and is in communication with the hollow interior of the hollow handle portion  30 . The groove  21  is intended to further reduce the overall weight of the wrench and cuts the manufacturing cost of the wrench. 
     In order to reinforce the handle portion  30  as well as accomplish objects to reduce weight and manufacturing cost thereof, the handle portion  30  is hollow and includes a front portion  32  having a front end contiguous to the neck portion  20 , a rear portion  31  adapted to be gripped by a user, and a necking portion  34  between the front portion  32  and rear portion  31 . The front portion  32 , the necking portion  34 , the rear portion  31  are integrally formed as single and inseparable component of a same material. The front portion  32  has an outer diameter D 4  the same as that of the rear end of the neck portion  20 . The front portion  32  also has a wall thickness d 4  greater than a wall thickness d 3  of the necking portion  34 , which, in turn, is greater than a wall thickness d 1  of the rear portion  31 . The necking portion  34  includes a small gradient section  341  having a rear end contiguous to the rear portion  31  and a front end. The necking portion  34  further includes a larger gradient section  342  having a rear end contiguous to the front end of the small gradient section  341  and a front end contiguous to the rear end of the front portion  32  of the handle portion  30 . The small gradient section  341  includes an outer periphery having a first tapering gradient from a rear end thereof to a front end thereof. The larger gradient section  342  includes an outer periphery having a second tapering gradient from a rear end thereof to a front end thereof. The second tapering gradient is greater than the first tapering gradient. Further, the small gradient section  341  has a wall thickness d 2  greater than the wall thickness d 1  of the rear portion  31 , and the larger gradient section  342  has a wall thickness d 3  greater than the wall thickness d 2  of the small gradient section  341  and smaller than the wall thickness d 4  of the front portion  32 . Further, the small gradient section  341  has increased wall thickness d 2  from the rear end thereof toward the front end thereof. The larger gradient section  342  has increased wall thickness d 3  from the rear end thereof toward the front end thereof. The wall thickness d 4  of the front portion  32  is two times of the wall thickness d 1  of the rear portion  31 . Further, the small gradient section  341  has an outer diameter D 2  smaller than an outer diameter D 1  of the rear portion  31 , the larger gradient section  342  has an outer diameter D 3  smaller than the outer diameter D 2  of the small gradient section  341 , and the front portion  32  has an outer diameter D 4  smaller than the outer diameter D 3  of the larger gradient section  342 . 
     In addition, the handle portion  30  includes an open rear end  33  defining a rear end opening at the rear portion  31 , and the open rear end  33  has a diameter corresponding to an inner diameter of the handle portion  30 . In order to avoid undesired radially inward depression of the rear end  33  of the handle portion  30  resulting from a holding force applied by the user&#39;s hand, the handle portion  30  is made from a material having inherent hardness above 30Rockwell C Hardness (HRC). Alternatively, the handle portion  30  could have hardness above 30 HRC by heat processing a material utilized. Typically, the material is metal-based. 
     It is understood that as the wall thickness d 1 -d 4  is increased, the structure strength is increased. For example, if the rear portion  31  with the wall thickness d 1  has hardness value approximately 40 HRC, the front portion  32  would have obtained hardness value greater than 40 HRC. 
       FIG. 4  shows a second embodiment of a wrench in accordance with present invention. The wrench is similar to the first embodiment. However, the neck portion  20  has no groove  21  included. 
       FIG. 5  shows a third embodiment of a wrench in accordance with the present invention. The wrench is similar to the second embodiment. However, the wrench includes a cap  40  mounted to and covering the rear end opening defined by the rear end  33  of the hollow handle portion  30 . Consequently, the hollow handle portion  30  may keep articles such as bits, fasteners such as bolts, nuts, screws or the like therein, and the cap  40  could prevent them from falling out of the hollow handle  30 . 
       FIG. 6  shows a fourth embodiment of a wrench in accordance with the present invention. The wrench is similar to the second embodiment. However, the wrench includes an outer cover  50  mounted to the rear portion  31  of the handle portion  30 . The outer cover  50  extends axially on an outer peripheral wall of the rear portion  31  of the handle portion  30  and could be used as a grip. Furthermore, the wrench has the head portion  10  modified to be pivotable with respect to the neck portion  20 . 
       FIG. 7  shows a fifth embodiment of a wrench in accordance with the present invention. The wrench is similar to the second embodiment. However, the head portion  10 , the neck portion  20 , and the handle portion  30  are integrally formed of a same material. 
       FIG. 8  shows a sixth embodiment of a wrench in accordance with the present invention. The wrench is similar to the second embodiment. However, the head portion  10  is modified to include a driving device  11  and a switching device  12 . 
     In a fifth embodiment of the wrench according to the preferred teachings of the present invention modified from the fourth embodiment shown in  FIGS. 7 and 8 , the neck portion  20  has no groove. 
     In one aspect of the present invention, the increased wall thickness d 1 -d 4  from the rear portion  31  toward the front portion  32  of the handle portion  30  enhances structural strength thereof to withstand larger torque and shear force during operation. In another aspect of the present invention, breakage of the handle portion  30  at the necking portion  34  is less likely to occur, notwithstanding the wall thickness of the necking portion  34  is smaller than the thickness d 4  of the front portion  32 . In yet another aspect of the present invention, the larger gradient section  342  and the smaller gradient section  341  provide a smooth contour while reducing concentration of stress. 
     It can also be appreciated that the hollow handle according to the preferred teachings of the present invention can be used for various types of wrenches, including but not limited to those illustrated in the drawings. It can be further appreciated that these wrenches can be manufactured by any suitable methods without departing from the teachings of the present invention. 
     Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be 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 therein.