Abstract:
A tool-free blade change system in one embodiment includes a handle, an arbor bolt including a keyed portion configured to mate with a keyed bore of the handle to restrict rotation of the handle with respect to the arbor bolt, a blade washer defining a plurality of washer teeth which enmesh with the body teeth so as restrict rotation of the handle with respect to the blade washer in one direction while allowing rotation of the handle with respect to the blade washer in another direction, and a biasing member configured to bias the handle downwardly toward the blade washer, wherein the handle is axially movable with respect to the blade washer between a first position whereat the plurality of body teeth are enmeshed with the plurality of washer teeth and a second position whereat the plurality of body teeth are spaced apart from the plurality of washer teeth.

Description:
This application claims the benefit of U.S. Provisional Application No. 61/747,435, filed Dec. 31, 2012, the entire contents of which are herein incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure relates generally to power tools, and more particularly to power tools with a circular blade. 
     BACKGROUND 
     A circular saw generally includes a circular blade having a centrally located hole for mounting the blade to a rotatable shaft. The blade is conventionally mounted to an end of the rotatable shaft in compression between an inner flange and outer flange or washer, held by a conventional arbor bolt threaded into a threaded bore in the shaft. 
     Circular saw blades must be replaced periodically due to blade wear and to accommodate a variety of different cutting uses. In order to install or remove a blade, a wrench typically must be used to supply sufficient torque to remove the bolt from the shaft. Inconveniences are incurred by the use of a conventional bolt to mount a circular saw blade. For example, the task of obtaining an appropriate wrench can be time consuming, and using the wrench can be cumbersome. 
     Furthermore, a circular saw generates substantial torque when the saw blade rotationally accelerates or decelerates. In some instances, the saw can generate enough torque to loosen the arbor bolt holding the saw blade on the saw. It is therefore desirable to provide an improved mechanism for removing and replacing a circular saw blade. Additionally, it is desirable to provide a system that enables a quick and easy removal of the circular saw blade without additional tools. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     Embodiments of the disclosure are related to a tool-free blade change system. The system includes a main body, an arbor bolt, and a blade washer. The main body and blade washer have teeth that fit together to enable the body to lock with the blade washer to disable the system from loosening due to inertial forces. The bolt is configured to be operated by a user without a tool to enable quick and easy removal of the circular saw blade. 
     A tool-free blade change system in one embodiment includes a main body including a keyed bore and plurality of body teeth, an arbor bolt including a keyed portion configured to mate with the keyed bore to restrict rotation of the main body with respect to the arbor bolt while allowing for axial movement of the main body with respect to the arbor bolt, a blade washer defining a plurality of washer teeth configured to enmesh with the plurality of body teeth so as restrict rotation of the main body with respect to the blade washer in a first direction while allowing rotation of the main body with respect to the blade washer in a second direction, and a biasing member configured to bias the main body downwardly toward the blade washer, wherein the main body is axially movable with respect to the blade washer between a first position whereat the plurality of body teeth are enmeshed with the plurality of washer teeth and a second position whereat the plurality of body teeth are spaced apart from the plurality of washer teeth. 
     In another embodiment, a method of operating a tool-free blade change system includes inserting a threaded portion of an arbor bolt through a hole in a blade, inserting the threaded portion of the arbor bolt into a threaded bore in a rotatable shaft, rotating the threaded portion of the arbor bolt within the threaded bore by forcing a keyed portion of a handle against a keyed portion of the arbor bolt, forcing a blade washer against the blade by the rotation of the threaded portion of the arbor bolt, rotating at least one of a plurality of teeth of the handle past at least one of a plurality of teeth of the blade washer by the rotation of the threaded portion of the arbor bolt, and biasing the plurality of teeth of the handle into engagement with the plurality of teeth of the blade washer with a biasing member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a tool-free blade change system. 
         FIG. 2  is a cross-sectional view of the tool-free blade change system of  FIG. 1 . 
         FIG. 3  is a perspective view of a main body of the tool-free blade change system of  FIG. 1 . 
         FIG. 4  is a side perspective view of an arbor bolt of the tool-free blade change system of  FIG. 1 . 
         FIG. 5  is a side view of the tool-free blade change system of  FIG. 1  with the teeth disengaged. 
     
    
    
     DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the disclosure as would normally occur to one of ordinary skill in the art to which this disclosure pertains. 
       FIG. 1  illustrates an exploded view of one embodiment of a tool-free blade change system  100 . The tool-free blade change system  100  includes a main body  110 , a compression spring  200 , an upper washer  130 , a lower washer  134 , a first retaining member in the form of a snap ring  140 , a cap  150 , a blade washer  160 , an arbor bolt  170 , a second retaining member in the form of a retaining ring  194 , and a thrust bearing  190 . 
     With reference to  FIGS. 2 and 3  and continuing reference to  FIG. 1 , the main body  110 , also referred to as a “handle”, includes a plurality of outer surfaces  126 , an annular projection  112  having a plurality of teeth  114 , an inner cavity  116 , and an opening  120  defined by a keyed flange  121  having two flat surfaces  122  positioned on opposite sides of the opening. Two curved surfaces  123  are located between the two flat surfaces  122 . The inner cavity  116  is defined inside the main body  110 , and is defined in part by an upwardly facing annular inner surface  118 . The plurality of outer surfaces  126  are arranged around the outside of the main body  110  and are configured to enable a user to manually grip, pull, and twist the main body  110 . In the illustrated embodiment, the main body includes eight outer surfaces, though in other embodiments the main body can include any desired number of outer surfaces. The surfaces  126  in some embodiments are textured. 
     Referring to  FIGS. 1, 2, and 4 , the arbor bolt  170  includes a head  172  with an internal hex  171  and a threaded region  176  extending from the head  172 . The head  172  includes a keyed portion with two flat outer surfaces  174  and two rounded outer surfaces  175 . The head  172  further includes an upper shoulder  178 , a lower shoulder  180 , an upper groove  182 , and a lower groove  184 . The internal hex  171  is provided for use by a user who cannot or chooses not to rotate the arbor bolt  170  using the surfaces  126 . In such a case, the user can loosen the bolt with a hex head tool. 
     The upper groove  182  is located near the top of the arbor bolt and is configured to accommodate the snap ring  140  to retain the snap ring  140  in a fixed axial position relative to the arbor bolt  170  when assembled as shown in  FIG. 2 . The upper washer  130  rests on the upper shoulder  178 , while the lower washer  134  contacts the lower shoulder  180  of the arbor bolt  170 . The lower groove  184  accommodates the retaining ring  194  to hold the retaining ring  194  in a fixed axial position relative to the arbor bolt  170 . 
     In the configuration of  FIG. 2 , the flat outer surfaces  174  of the arbor bolt  170  are positioned in opposition to the flat surfaces  122  ( FIG. 3 ) of the main body  110  while the rounded surfaces  175  are in opposition to the rounded surfaces  123 . Because of this keyed relationship, rotational motion of the main body  110  is transferred to the arbor bolt  170  to enable the main body  110  and arbor bolt  170  to rotate together. 
     As further depicted in  FIG. 2 , the threaded region  176  includes a plurality of threads that extend past the outer blade washer  160 . Accordingly, the tool-free blade change system  100  can be used to mount a blade  161  to a tool  163  by inserting the threaded region  176  through an aperture  165  in the blade  161  and mated with a threaded bore  167  in a power shaft  169  of a circular saw or other tool to clamp the circular saw blade between the outer blade washer  160  and an inner blade washer (not shown) that is positioned between the saw blade and the threaded bore. In  FIG. 2 , the tool  163  and blade  161  and their various components are depicted with a dashed line to indicate that no particular proportions between the tool  163 , the blade  161 , and the tool-free blade change system  100  is to be inferred from  FIG. 2 . In the illustrated embodiment, the threads are arranged in a left-hand thread, by which is meant the bolt  170  is tightened by turning the bolt  170  counter-clockwise and loosened by turning the bolt  170  clockwise. However, the reader should appreciate that the system described herein can be applied to a bolt having a right-hand thread as well. 
     Referring to  FIGS. 1, 2, and 5 , the blade washer  160  includes a plurality of teeth  162 , an upper surface  164 , a lower surface  166 , and a well  168 . The plurality of teeth  162  of the blade washer  160  are configured such that the teeth  162  of the washer  160  can engage the teeth  114  of the main body  110  in a complimentary fashion. As will be described in more detail below, the complimentary engagement of the teeth  114  and  162  prevents the arbor bolt  170  from turning clockwise and loosening from the circular saw blade while the teeth  114  and  162  are engaged. As shown in  FIG. 5 , the teeth  162  are angled on one side to enable the teeth  162  to slip with the teeth  114  of the main body  110  to enable the main body  110  to rotate in the counter-clockwise direction with respect to the blade washer  160  to tighten the tool-free blade change system  100  against a circular saw blade. 
     Continuing with  FIG. 2 , the thrust bearing  190  rests on the upper surface  164  of the blade washer  160 , while the lower surface  166  is configured to rest against the blade (not shown). The retaining ring  194 , which is positioned within the groove  184  of the arbor bolt  170 , retains the thrust bearing  190  and lower washer  134  about the arbor bolt  170  when the main body  110  is disengaged from the blade washer  160 . 
     The compression spring  200 , upper washer  130 , snap ring  140 , and cap  150  are positioned within the inner cavity  116  of the main body  110 . The cap has a first surface  152  and a second surface  154  below and radially outward from the first surface  152 . The upper washer  130  rests on the upper shoulder  178  of the arbor bolt  170  and on the second surface  154  of the cap  150 . The system  100  is configured such that the compression spring  200  or other biasing member presses upwardly (in the view of  FIG. 2 ) against the upper washer  130  and downwardly against the inner surface  118  of the main body  110 . The snap ring  140  is positioned within the upper groove  182  of the arbor bolt  170  to hold the upper washer  130  in axial position relative to the arbor bolt  170  against the force of the compression spring  200 . The restoring force of the compression spring  200  therefore acts to urge the main body  110  downwardly to engage the teeth  114  of the main body  110  with the teeth  162  of the blade washer  160  in the absence of an external force. 
     The lower washer  134  and the thrust bearing  190  are positioned between the lower shoulder  180  of the arbor bolt  170  and the upper surface  164  of the blade washer  160 . The thrust bearing  190  engages the upper surface  164  of the blade washer  160  and the lower washer  134  to enable the arbor bolt  170  and lower washer  134  to rotate relative to the blade washer  160 , even with the arbor bolt  170 , lower washer  134 , thrust bearing  190 , and blade washer  160  in contact with one another. 
     In operation, the tool-free blade change system  100  is inserted through a circular working tool such as a saw blade into a threaded bore of a power shaft of a power tool such as a circular saw (not shown) and the threaded region  176  of the arbor bolt  170  is threaded into the threaded bore. The user grasps the surfaces  126  of the main body  110  to turn the main body  110  in the counter-clockwise direction. In response to the counter-clockwise rotation of the main body  110 , the arbor bolt  170  rotates counter-clockwise due to the engagement of the flat surfaces  122  of the main body  110  with the flat surfaces  174  of the arbor bolt  170 . Furthermore, as the main body  110  is turned counter-clockwise (or to the right in the view of  FIG. 5 ), the teeth  114  of the main body slip with the teeth  162  of the blade washer  160 . Specifically, the left side of each of the teeth  162  is angled while the right side is substantially vertical, and the right side of each of the teeth  114  is angled while the left side is substantially vertical (“left” and “right” are used herein in reference to the sides of the teeth  114  and  116  refers to the orientation as presented in  FIG. 5 ). This configuration allows the main body  110  and the arbor bolt  170  to rotate relative to the blade washer  160  to tighten the arbor bolt  170  to the threaded bore. 
     As the circular saw or other tool is used, inertia forces of the circular saw due to the torque generated during acceleration and deceleration of the saw blade urge the arbor bolt  170  to rotate in the clockwise direction. However, when the teeth  114  and  162  of the main body  110  and blade washer  160 , respectively, are engaged, the main body  110  and arbor bolt  170  are prevented from rotating in the clockwise direction. Thus, the tool-free blade change system  100  remains tightly affixed to the threaded bore and the blade remains tightly attached to the circular saw. 
     To remove the blade or other shaping device, the user pulls upwardly (in the view of  FIG. 2 ) on the main body  110 , against the force of the compression spring  200 , until the teeth  114  of the main body  110  disengage from the teeth  162  of the blade washer  160 , as shown in  FIG. 5 . The axial height of the keyed flange  121  is greater than the height of the teeth  114 / 162 . Accordingly, while the teeth become disengaged, the flat surfaces  122  are still at least partially in opposition to the flat surfaces  174 . Consequently, once the teeth  114  and  162  are disengaged, the user rotates the main body  110  clockwise, which results in the arbor bolt  170  turning clockwise. The arbor bolt  170  unscrews from the threaded bore of the circular saw, enabling removal of the blade from the circular saw. 
     While not shown in  FIG. 2 , in some embodiments the washer  160  is configured to assist in maintaining the washer  160  and the arbor bolt  170  in alignment when the teeth  114 / 162  are not engaged. For example, the well  168  in some embodiments is deeper than the height of the teeth  114 / 162 . Accordingly, as the teeth  114 / 162  disengage, the retaining ring  194  remains within the well  168 , assisting in maintaining the arbor bolt  170  aligned with the washer  160 . 
     Accordingly, a method of operating a tool-free blade change system includes inserting a threaded portion of an arbor bolt through a hole in a blade, inserting the threaded portion of the arbor bolt into a threaded bore in a rotatable shaft, rotating the threaded portion of the arbor bolt within the threaded bore by forcing a keyed portion of a handle against a keyed portion of the arbor bolt, forcing a blade washer against the blade by the rotation of the threaded portion of the arbor bolt, rotating at least one of a plurality of teeth of the handle past at least one of a plurality of teeth of the blade washer by the rotation of the threaded portion of the arbor bolt, and biasing the plurality of teeth of the handle into engagement with the plurality of teeth of the blade washer with a biasing member. 
     While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the disclosure are desired to be protected.