Patent Publication Number: US-2022234177-A1

Title: Tool bit

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/027,691 filed on Jul. 5, 2018, which is a continuation of U.S. patent application Ser. No. 14/596,739 filed on Jan. 14, 2015, now U.S. Pat. No. 10,022,845, which claims priority to U.S. Provisional Patent Application No. 61/928,266 filed on Jan. 16, 2014, the entire contents of all of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to tool bits, and more particularly to tool bits configured for interchangeable use with a driver. 
     BACKGROUND OF THE INVENTION 
     Tool bits, or insert bits, are often used with drivers configured to interchangeably receive the bits. For example, typical insert bits each include a hexagonal drive portion, a head or tip configured to engage a fastener, and a cylindrical shank connecting the drive portion and the tip. Drivers include a socket having a hexagonal recess in which the hexagonal drive portion of an insert bit is received and a stem or shank extending from the socket, which can be coupled to a handle for hand-use by an operator, or a power tool (e.g., a drill) for powered use by the operator. An interference fit between the hexagonal drive portion of the insert bit and the socket may be used to axially secure the insert bit to the driver, or quick-release structure may be employed to axially secure the insert bit to the driver. 
     SUMMARY OF THE INVENTION 
     The invention provides, in one aspect, a tool bit including a hexagonal drive portion, a working end, and a shank. The working end is made of a first material having a first hardness. The shank connects the drive portion to the working end. The shank defines a longitudinal axis about which the tool bit is rotatable. The shank is made of a second material having a second, different hardness. The shank includes a protrusion and an annular shoulder. The shank extends within a portion of the working end and has a distal end. The annual shoulder surrounds the protrusion. At least one of the distal end or the shoulder is oriented perpendicular to the longitudinal axis. 
     The invention provides, in another aspect, a tool bit including a hexagonal drive portion, a working end, and a shank. The working end is made of a first material having first hardness. The shank connects the drive portion to the working end. The shank defines a longitudinal axis about which the tool bit is rotatable. The shank is made of a second material having a second, different hardness. The working end includes a blind bore in which a portion of the shank is receivable. The interior surface of the blind bore is perpendicular to the longitudinal axis. 
     The invention provides, in yet another aspect, a tool bit hexagonal drive portion, a working end, and a shank. The working end is made of a first material having a first hardness. The shank connects the drive portion to the working end. The shank defines a longitudinal axis about which the tool bit is rotatable. The shank is made of a second material having a second, different hardness. The shank includes a distal end oriented perpendicular to the longitudinal axis. 
     Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a tool bit in accordance with an embodiment of the invention. 
         FIG. 2  is a perspective view of a tool bit in accordance with another embodiment of the invention. 
         FIG. 3  is a perspective view of a tool bit in accordance with yet another embodiment of the invention. 
         FIG. 4  is a perspective view of a tool bit in accordance with a further embodiment of the invention. 
         FIG. 5  is a perspective view of a tool bit in accordance with another embodiment of the invention. 
         FIG. 6  is a perspective view of the tool bit of  FIG. 5  with a working end of the bit removed. 
         FIG. 7  is a side view of the tool bit of  FIG. 5 . 
         FIG. 8  is a cross-sectional view of the tool bit of  FIG. 5  through section line  8 - 8  in  FIG. 7 . 
         FIG. 9  is a front view of the tool bit of  FIG. 5 . 
         FIG. 10  is a rear view of the tool bit of  FIG. 5 . 
         FIG. 11  is a schematic of a process for manufacturing the tool bit of  FIG. 5 . 
       Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a tool bit  10  including a hexagonal drive portion  14 , a working end, head, or tip  18  configured to engage a fastener, and a shank  22  interconnecting the drive portion  14  and the tip  18 . The hexagonal drive portion  14  is intended to be engaged by any of a number of different tools, adapters, or components to receive torque from the tool, adapter, or component to rotate the bit  10 . For example, the bit  10  may be utilized with a driver including a socket (not shown) having a corresponding hexagonal recess in which the hexagonal drive portion  14  of the bit  10  is received. The driver may also include a stem extending from the socket, which may be coupled to a handle for hand-use by an operator or to a chuck of a power tool (e.g., a drill) for powered use by the operator. A sliding, frictional fit between the hexagonal drive portion  14  of the bit  10  and the socket may be used to axially secure the bit  10  to the driver. Alternatively, a quick-release structure may be employed to axially secure the bit  10  to the driver. As shown in  FIG. 1 , the drive portion  14  of the bit  10  includes a groove  26  into which the quick-release structure (e.g., a ball detent) may be positioned to axially secure the bit  10  to the driver. Alternatively, the groove  26  may be omitted from the drive portion  14  of the bit  10  should a sliding frictional fit between the socket and the drive portion  14  be employed. 
     With continued reference to  FIG. 1 , the tip  18  of the bit  10  is configured as a Philips-style tip  18 . Alternatively, the tip  18  may be differently configured to engage different style fasteners. For example, the tip  18  may be configured as a straight blade (otherwise known as a “regular head”) to engage fasteners having a corresponding straight slot. Other tip configurations (e.g., hexagonal, star, square, etc.) may also be employed with the bit  10 . 
     In the illustrated embodiment of  FIG. 1 , different manufacturing processes can be used to impart a greater hardness to the tip  18  compared to the hardness of the shank  22 . For example, the entire bit  10  can be heat treated to an initial, relatively low hardness level and then a secondary heat treating process can be applied only to the tip  18  to increase the hardness of the tip  18  to a relatively high hardness level to reduce the wear imparted to the tip  18  during use of the bit  10 . Alternatively, in a different manufacturing process, the entire bit  10  can be heat treated to an initial, relatively high hardness level and then a secondary annealing process (e.g., an induction annealing process using an induction coil  28 ) can be applied to the shank  22  (and, optionally, the drive portion  14 ) to reduce the hardness of the shank  22  (and optionally the drive portion  14 ) to a relatively low hardness level to increase the torsional resiliency of the shank  22 , and therefore its impact resistance, during use of the bit  10 . 
     In operation of the bit  10 , the concavity of the shank  22  is configured to increase the impact resistance or the toughness of the bit  10 , such that the drive portion  14  and the shank  22  of the bit  10  are allowed to elastically deform or twist relative to the tip  18  about a longitudinal axis of the bit  10 . Specifically, the polar moment of inertia of the shank  22  is decreased by incorporating the concavity, thereby reducing the amount of torsion required to elastically twist the shank  22 , compared to a shank having a cylindrical shape. The reduced hardness of the shank  22  relative to the tip  18  further increases the impact resistance of the bit  10 , compared to a similar bit having a uniform hardness throughout. 
       FIG. 2  illustrates a tool bit  10   a  in accordance with another embodiment of the invention, with like reference numerals with the letter “a” assigned to like features as the tool bit  10  shown in  FIG. 1 . Rather than using multiple heat treating processes to impart the desired hardness profile to the bit  10   a , the tip  18   a  of the bit  10   a  is made of a first material having a first hardness, and the shank  22   a  of the bit  10   a  is made of a second material having a second, different hardness. The first and second materials are chosen such that the first hardness is greater than the second hardness. Accordingly, the hardness of the tip  18   a  is greater than the hardness of the shank  22   a  to reduce the wear imparted to the tip  18   a  during use of the bit  10   a . The reduced hardness of the shank  22   a  relative to the tip  18   a , however, also increases the impact-resistance of the bit  10   a  as described above. 
     In the particular embodiment of the bit  10   a  shown in  FIG. 2 , an insert molding process, such as a two-shot metal injection molding (“MIM”) process, is used to manufacture the bit  10   a  having the conjoined tip  18   a  and shank  22   a  made from two different metals. Particularly, the tip  18   a  is made of a metal having a greater hardness than that of the shank  22   a  and the drive portion  14   a . Because the dissimilar metals of the tip  18   a  and the shank  22   a , respectively, are conjoined or integrally formed during the two-shot MIM process, a secondary manufacturing process for connecting the tip  18   a  to the remainder of the bit  10   a  is unnecessary. The MIM process will be described in detail below. Alternatively, rather than using an insert molding process, the tip  18   a  may be attached to the shank  22   a  using a welding process (e.g., a spin-welding process). 
       FIG. 3  illustrates a tool bit  10   b  in accordance with yet another embodiment of the invention, with like reference numerals with the letter “b” assigned to like features as the tool bit  10  shown in  FIG. 1 . Rather than using different materials during the manufacturing process to create the tool bit  10   b , the tip  18   b  includes a layer of cladding  42  having a hardness greater than the hardness of the shank  22   b . Furthermore, the hardness of the cladding  42  is greater than the hardness of the underlying material from which the tip  18   b  is initially formed. The cladding  42  may be added to the tip  18   b  using any of a number of different processes (e.g., forging, welding, etc.). The addition of the cladding  42  to the tip  18   b  increases the wear resistance of the tip  18   b  in a similar manner as described above in connection with the bits  10 ,  10   a.    
       FIG. 4  illustrates a tool bit  10   c  in accordance with a further embodiment of the invention, with like reference numerals with the letter “c” assigned to like features as the tool bit  10  shown in  FIG. 1 . At least one of the hexagonal drive portion  14   c , the tip  18   c , and the shank  22   c  is made using a three-dimensional printing process. With such a process, different materials (e.g., metals) can be used for printing the tip  18   c  and the shank  22   c  to impart a greater hardness to the tip  18   c  relative to the shank  22   c  to reduce the wear imparted to the tip  18   c  during use of the bit  10   c . For example, the tip  18   c  of the bit  10   c  may be printed from a first material having a first hardness, and the shank  22   c  of the bit  10   c  may be printed from a second material having a second, different hardness. The first and second materials are chosen such that the first hardness is greater than the second hardness. The tip  18   c  and the shank  22   c  may be conjoined or integrally formed during the printing process. Alternatively, separate printing processes using different materials may be used and a secondary manufacturing process (e.g., welding, etc.) may be used for joining the tip  18   c  and the shank  22   c . 
     In the illustrated embodiment shown in  FIG. 4 , the shank  22   c  is comprised of several individual strands  46  interconnecting the tip  18   c  and the drive portion  14   c . Each of the strands  46  is offset from a longitudinal axis of the bit  10   c  in a radially outward direction, thereby creating a void between the collection of individual strands  46 . Such a configuration of the shank  22   c  decreases the polar moment of inertia of the shank  22   c , thereby reducing the amount of torsion required to elastically twist the shank  22   c  compared to a shank having a solid, cylindrical shape. The reduced hardness of the shank  22   c  relative to the tip  18   c  further increases the impact resistance of the bit  10   c , compared to a similar bit having a uniform hardness throughout. 
       FIG. 5  illustrates a tool bit  10   d  in accordance with another embodiment of the invention, with like reference numerals with the letter “d” assigned to like features as the tool bit  10  shown in  FIG. 1 . The tool bit  10   d  includes a hollow core  30  that extends from a portion of the shank  22   d  adjacent the tip  18   d , through the shank  22   d , and towards the hexagonal drive portion  14   d  ( FIG. 8 ). In the illustrated embodiment of the bit  10   d , the hollow core  30  extends entirely through the hexagonal drive portion  14   d , terminating in an opening  34  opposite from the tip  18   d  ( FIGS. 5 and 8 ). Alternatively, the core  30  may terminate prior to reaching the distal end of the drive portion  14   d . For example, the core  30  may extend entirely through the shank  22   d , but only partially through the drive portion  14   d . Or, the core  30  may terminate prior to reaching the drive portion  14   d . As shown in  FIG. 8 , the hollow core  30  includes a substantially uniform diameter D1 along its length L1. The tool bit  10   d  includes a major longitudinal axis  38 , which also defines a rotational axis of the tool bit  10   d , that is collinear or coaxial with the hollow core  30 . Alternatively, the hollow core  30  may terminate prior to reaching the end of the drive portion  14   d  opposite the tip  18   d , so that the opening  34  is omitted. For example, in another embodiment of the tool bit, the hollow core  30  may coincide only with the shank  22   d , with the length L1 of the hollow core  30  being substantially equal to that of the shank  22   d . 
     For the two-inch bit  10   d  shown in  FIG. 8 , the length L1 of the hollow core  30  is about 1.45 inches to about 1.53 inches, with a nominal length L1 of about 1.49 inches. Furthermore, the diameter D1 of the hollow core  30  is about 0.100 inches to about 0.150 inches, with a nominal diameter D1 of about 0.125 inches. As a result, a ratio of the length L1 to the diameter D1 of the hollow core  30  is about 9.6:1 to about 15.3:1, with a nominal ratio of about 11.9:1. Alternatively, the ratio of the length L1 to the diameter D1 of the hollow core  30  may be greater than about 15.3:1 or less than about 9.1:1 to accommodate different size or length bits  10 . In addition, the ratio of the total length of the two-inch bit  10   d  to the length L1 of the hollow core  30  is about 1.3:1 to about 1.4:1, with a nominal ratio of about 1.35:1. Alternatively, the ratio of the total length of the bit  10   d  to the length L1 of the hollow core  30  may be greater than about 1.4:1 or less than about 1.3:1 to accommodate different size or length bits  10 . 
     With reference to  FIG. 6 , the tip  18   d  is omitted from the tool bit  10   d  exposing a protrusion  40  extending from the shank  22   d  and coaxial with the major longitudinal axis  38 . As is described in greater detail below, the protrusion  40  facilitates manufacturing the tool bit  10   d  using the two-shot MIM process. The protrusion  40  defines a cylindrical shape having a fillet  48  and a chamfer  50  at opposite ends of the protrusion  40 . Alternatively, the protrusion  40  may be differently configured as a cone, a semi-sphere, or the like. Further, the protrusion  40  may be configured with one or more radially extending keyways, splines, or teeth, or the protrusion  40  may be cylindrical yet offset from the longitudinal axis  38 , to facilitate torque transfer between the shank  22   d  and the tip  18   d . As a further alternative, the protrusion  40  may be formed on the tip  18   d , and the shank  22   d  may be molded around the protrusion  40  thereby positioning the protrusion  40  within the core  30 . 
     With reference to  FIGS. 5-7 , the shank  22   d  is defined by a peripheral surface  54  that extends between the working end  18   d  and the hexagonal drive portion  14   d . The peripheral surface  54  defines a uniform diameter D2 of the shank  22   d  ( FIG. 7 ). Alternatively, the shank  22   d  may be differently configured. For example, in another embodiment of the tool bit, the shank  22   d  may be configured to include a non-uniform diameter with a concave shape similar to the tool bits  10 ,  10   a , and  10   b . 
     The shank  22   d  includes slots  58  spaced about the peripheral surface  54  at  90  degree angular increments, with each of the slots  58  defining a minor longitudinal axis  62  ( FIG. 7 ). The slots  58  extend radially with respect to the major longitudinal axis  38  between the hollow core  30  and the peripheral surface  54 . Therefore, the slots  58  communicate the hollow core  30  with the ambient surroundings of the tool bit  10 . Alternatively, the tool bit  10   d  may be configured with more or fewer than four slots  58 , and the slots  58  may be located or dispersed about the shank  22   d  at different angular increments other than 90 degrees. For example, in an alternative embodiment of the tool bit  10   d , the slots  58  may be omitted entirely and the presence of the hollow core  30  through the shank  22   d  is sufficient to provide the desired amount impact resistance to the bit  10   d . For the two-inch bit  10   d  shown in  FIG. 7 , each of the slots  58  includes a length L2 of about 0.250 inches to about 0.350 inches, with a nominal length L2 of about 0.300 inches. Furthermore, the slots  58  include a width W of about 0.030 inches to about 0.100 inches, with a nominal width of about 0.065 inches. As a result, a ratio of the length L2 to the width W of the slots  58  is about 2.5:1 to about 11.7:1, with a nominal ratio of about 4.6:1. Alternatively, the ratio of the length L2 to the width W of the slots  58  may be greater than about 11.7:1 or less than about 2.5:1 to accommodate different size or length tool bits  10   d . Regardless of the total length of the bit  10   d , a length dimension L3 ( FIG. 8 ) extending between a front end of the core  30  and the distal end of the tip  18   d  is about 0.38 inches to about 0.58 inches, with a nominal value of 0.48 inches. 
     With continued reference to  FIG. 7 , the slots  58  are oriented at an oblique angle β between the major longitudinal axis  38  and the minor longitudinal axis  62 . The oblique angle β is about 0 degrees to about 20 degrees, with a nominal value of about 10 degrees. Alternatively, the oblique angle β may be greater than about 20 degrees to accommodate different size or length tool bits  10 . In some embodiments, the oblique angle β may be zero degrees, thereby orienting the slots  58  parallel with the longitudinal axis  38 . However, orienting the slots  58  with a positive value for angle β as shown in  FIG. 7  causes the shank  22   d  to elongate as it twists (i.e., assuming application of torque to the drive portion  14   d  in a clockwise direction from the frame of reference of  FIG. 10 ), thereby displacing the tip  18   d  toward the fastener as it is driven into a workpiece. Accordingly, the contact surface between the fastener head and the tip  18   d  may be increased simultaneously as the reaction torque applied by the fastener to the bit  10   d  is increased, reducing the likelihood that the tip  18   d  slips on the fastener head. 
     The hollow core  30  and the slots  58  in the tool bit  10   d  work in conjunction to increase the impact resistance or the toughness of the tool bit  10   d , such that the tip  18   d  of the tool bit  10   d  is allowed to elastically deform or twist relative to the hexagonal drive portion  14   d  about the major longitudinal axis  38  of the tool bit  10   d . Specifically, the polar moment of inertia of the shank  22   d  is decreased by incorporating the hollow core  30  and slots  58 , thereby reducing the amount of torsion required to elastically twist the shank  22   d , compared to a configuration of the shank having a solid cylindrical shape without the slots  58  (e.g., shanks  22 ,  22   a ,  22   b ). 
     In the illustrated embodiment of the tool bit  10   d , the tip  18   d  made of a first material having a first hardness and the shank  22   d  is made of a second material having a second, different hardness. Particularly, the hardness of the tip  18   d  is greater than the hardness of the shank  22   d  to reduce the wear imparted to the tip  18   d  during use of the bit  10   d . The reduced hardness of the shank  22   d  relative to the tip  18   d , however, also increases the impact-resistance of the bit  10   d . For example, the first hardness is about 55 HRC to about 65 HRC, with a nominal hardness of about 62 HRC, while the second hardness is about 40 HRC to about 55 HRC, with a nominal hardness of about 45 HRC. Therefore, a ratio between the first hardness and the second hardness is about 1:1 to about 1.7:1, with a nominal ratio of about 1.4:1. Alternatively, the ratio between the first hardness and the second hardness may be greater than about 1.7:1 to provide optimum performance of the tool bit  10   d . The first and second materials are each comprised of a ferrous alloy composition, though different materials may alternatively be used. 
     As mentioned above, the two-shot metal MIM process is used to manufacture the bit  10   d  to make the conjoined tip  18   d  and shank  22   d  from two different materials. In other embodiments, the two-shot MIM process may be used to manufacture tool bits  10 ,  10   a ,  10   b , and  10   c . Particularly, in the illustrated embodiment of the tool bit  10   d , the tip  18   d  is made from a material having a greater hardness than that of the shank  22   d  and the hexagonal drive portion  14   d . Because the dissimilar materials of the tip  18   d  and the shank  22   d , respectively, are conjoined or integrally formed during the two-shot MIM process, a secondary manufacturing process for connecting the tip  18   d  to the remainder of the bit  10   d  is unnecessary. Furthermore, the protrusion  40  provides a greater surface area between the tip  18   d  and the shank  22   d  so that the bond between dissimilar metals of the tip  18   d  and the shank  22   d  is stronger compared, for example, to using a flat mating surface between the tip  18   d  and the shank  22   d . In addition, the protrusion  40  increases the shear strength of the bit  10   d  at the intersection of the tip  18   d  and the shank  22   d . 
     With reference to  FIG. 11 , the two-shot MIM process includes in sequence a feedstock mixing process  70  to mix the first and the second materials  74 ,  78  with a binder composition  82 , an injection molding process  86  using a mold  90 , a debinding process  94  to eliminate the binder composition  82 , and a heat treating process  98 . 
     During the feedstock mixing process  70 , the binder composition  82  is added to the first and the second materials  74 ,  78  to facilitate processing through the injection molding process  86 . As a result, the first material  74 , which is in a powder form, is homogeneously mixed with the binder composition  82  to provide a first feedstock mixture  102  of a determined consistency. In addition, the second material  78 , which is also in a powder form, is also homogeneously mixed with the binder composition  82  to provide a second feedstock mixture  106  with substantially the same consistency as the first mixture  102 . In the illustrated embodiment of the tool bit  10   d , the binder composition  82  includes a thermoplastic binder. Alternatively, the binder composition  82  may include other appropriate binder compositions (e.g., wax). The amount of binder composition  82  in each of the first and second feedstock mixtures  102 ,  106  is chosen to match the shrink rates of the tip  18   d  and the drive portion  14   d /shank  22   d , respectively, during the sintering process  122  described below. 
     The injection molding process  86  includes processing the first and the second feedstock mixtures  102 ,  106  through an injection molding machine  134 . Particularly, the process  86  includes injecting the first feedstock mixtures  102  into a first portion  110  of the mold  90 , and injecting the second feedstock mixture  106  into a second portion  114  of the mold  90 . In the illustrated embodiment shown in  FIG. 11 , the tip  18   d  of the tool bit  10   d  is generally formed in the first portion  110  of the mold  90 , while the shank  22   d  and the drive portion  14   d  of the tool bit  10   d  are generally formed in the second portion  114  of the mold  90 . Upon completion of the injection molding process  86 , a temporary (otherwise known in the MIM industry as a “green”) tool bit  126  is produced that includes the first and the second materials  74 ,  78  and the binder composition  82 . The “green” tool bit  126  is larger than the final tool bit  10   d  due to the presence of the binder composition  82 . 
     The injection molding process  86  may be carried out in various ways to form the “green” tool bit  126 . For example, the “green” tool bit  126  can be initially formed along the major longitudinal axis  38  from the hexagonal drive portion  14   d  to the tip  18 , or from the tip  18   d  to the hexagonal drive portion  14   d . Alternatively, the “green” tool bit  126  can be initially formed from a side-to-side profile as oriented in  FIG. 7 . 
     After the injection molding process  86 , the “green” tool bit  126  is removed from the mold  90  and proceeds through the debinding process  94 . The debinding process  94  eliminates the binder composition  82 . During the debinding process  94 , the “green” tool bit  126  transforms into a “brown” tool bit  130  (as it is known in the MIM industry) that only includes the first and the second materials  74 ,  78 . In the illustrated embodiment, the debinding process  94  includes a chemical wash  118 . Alternatively, the debinding process  94  may include a thermal vaporization process to remove the binder composition  82  from the “green” tool bit  126 . The “brown” tool bit  130  is fragile and porous with the absence of the binder composition  82 . 
     To reduce the porosity of the “brown” tool bit  130 , the heat treating process  98  is performed to atomically diffuse the “brown” tool bit  130  to form the final tool bit  10   d . The heat treating process  98  exposes the “brown” tool bit  130  to an elevated temperature to promote atomic diffusion between the first and the second materials  74 ,  78 , allowing atoms of the dissimilar materials  74 ,  78  to interact and fuse together. The heat treating process  98  reduces the porosity of the “brown” tool bit  130  to about 95% to about 99% to yield the final tool bit  10   d . In the illustrated embodiment, the heat treating process  98  includes a sintering process  122 . Alternatively, the debinding process  94  and the heat treating process  98  may be combined as a single process such that, at lower temperatures, thermal vaporization will occur during the debinding process  94  to eliminate the binder composition  82 . And, at higher temperatures, atomic diffusion will reduce the porosity in the “brown” tool bit  130  to yield the final tool bit  10   d.    
     Various features of the invention are set forth in the following claims.