Abstract:
Embodiments are disclosed for a tool-less clamping apparatus for a reciprocating tool having a reciprocating spindle having a center axis and at least one radially oriented aperture and a receiving slot at its forward end for receiving a tool accessory, the apparatus having an unclamped position and a clamped position, and comprising a hollow generally cylindrical sleeve secured to the spindle, a hollow generally cylindrical collar configured to fit on the sleeve and being rotatable relative to the spindle and the sleeve, the collar having an inner cam surface that increases in radius from the axis through a first predetermined circumferential arc in a first direction, a spring operatively connected to provide a biasing force to the collar toward its clamped position, and a detent pin positioned in the spindle aperture and configured to engage a hole in the tool accessory and thereby firmly hold the tool accessory in the apparatus when urged into contact with the tool accessory.

Description:
BACKGROUND OF THE INVENTION  
       [0001]    The present invention generally relates to tools, and more particularly, to mechanisms for clamping tool accessories to such tools. 
         [0002]    Reciprocating tools such as jigsaws, saber saws and the like have been the subject of extensive research and development efforts over the years. A focus of many designers is the mechanisms for attaching a tool attachment such as a cutting blade, a saw blade, an abrasive, polishing or smoothing member or the like to the reciprocating portion of such tools. 
         [0003]    Early attachment mechanisms required separate tools of one kind or another, typically screwdrivers, wrenches or levers, to attach the tool attachment to a reciprocating member by tightening screws or the like. Because special tools were often required, it was necessary to have such tools available during use in the event the tool attachment breaks or otherwise needs to be changed because it is worn out or a different type of tool attachment is needed. 
         [0004]    Recently, there has been a concerted effort to develop new kinds of attachment or clamping mechanisms that do not require the use of tools to mount and remove tool attachments from the tool. While mechanisms are known in the prior art that have this capability, the various known designs have varying degrees of effectiveness in securely holding the tool attachment in the tool, or in the ease and convenience of operation in mounting or removing tool attachments from the tool or in the degree of complexity and therefore cost of manufacture. Known mechanisms often do not exhibit reliable operation in construction, demolition, metal cutting, and similar types of work that produce considerable amounts of particulate matter, such as drywall dust and demolition dust. 
       SUMMARY OF THE INVENTION  
       [0005]    The preferred embodiment discloses a clamping apparatus for a reciprocating tool having a reciprocating spindle having a center axis and at least one radially oriented aperture and a receiving slot at its forward end for receiving a tool accessory that has a shank portion with a hole at one end and a working portion, the shank being configured to be inserted in the slot, the apparatus being configured to be attached to the spindle, the apparatus having an unclamped position and a clamped position, and comprises: 
         [0006]    a hollow generally cylindrical sleeve secured to the spindle, the sleeve having a radial aperture aligned with the spindle aperture and an annular recess oriented in a plane perpendicular to the center axis and extending around a substantial portion of the outside surface near the forward end, 
         [0007]    a hollow generally cylindrical collar configured to fit on the sleeve and being rotatable relative to the spindle and the sleeve, the collar having an inner cam surface that increases in radius from the axis through a first predetermined circumferential arc in a first direction, a spring operatively connected to provide a biasing force to the collar in a second direction opposite the first direction, and 
         [0008]    a detent pin positioned in the spindle aperture and configured to engage the hole in the tool accessory and thereby firmly hold the tool accessory in the apparatus when urged into contact with the tool accessory, the collar being biased by the spring to rotate the collar to its clamped position when the tool accessory is inserted in the slot, the rotation causing the cam surface to engage the detent pin and move it into the hole in the tool accessory and firmly hold the tool accessory in the apparatus. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a preferred embodiment of the clamping apparatus shown with a blade inserted in the apparatus in its clamped position; 
           [0010]      FIG. 2  is an exploded perspective illustrating the components of the apparatus shown in  FIG. 1 ; 
           [0011]      FIG. 3  is a cross-section taken generally along a line perpendicular to the orientation of the slot of the spindle at a location through the center of a detent pin; 
           [0012]      FIG. 4  is a perspective view of the sleeve of the apparatus shown in  FIG. 1 ; 
           [0013]      FIG. 5  is a side view of the sleeve of the apparatus shown in  FIGS. 1 and 4 ; 
           [0014]      FIG. 6  is a perspective view of the collar of the apparatus shown in  FIG. 1 ; and 
           [0015]      FIG. 7  is another perspective view of the collar shown in the  FIGS. 1 and 6 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    While embodiments of the present invention can be used with various power hand tools, jig saws, saber saws and other reciprocating saws used in the construction, demolition, metal cutting, and woodworking applications, it should be understood that the clamping apparatus is certainly susceptible for use in applications other than these. It is contemplated that the clamping apparatus may be used in the medical field, particular with surgical instruments that are used with reciprocal saw and cutting blades. Also, while the embodiments of the present invention are particularly suited for use with power hand tools, they could be used with a non-power hand tool as well as larger stationary power tools that employ tool attachments in a reciprocating manner and where such tool attachments are replaced. The detailed description of the preferred embodiments are described with regard to saber and reciprocating saws which use commercially available saw blades. The present invention should not be limited to the described applications. 
         [0017]    The embodiments of the clamping apparatus of the present invention are particularly suited for use with a saber saw which has a generally cylindrical plunger rod or spindle, although spindles or structure may be utilized which are other than the circular cross-section. However, if it is other than a circular cross-section throughout a significant part of its length, the spindle necessarily requires a generally cylindrical distal end portion in which the embodiments of the present invention are installed. The blade described herein in which the clamping mechanism of the embodiments of the present invention are to be used is of conventional design for saber saw blades, but it should be understood that the various embodiments could be modified to operate with other styles of blades if desired. 
         [0018]    The preferred embodiments of the present invention exhibit reliable operation and are not adversely affected by particulate contamination, such as dust from wood, plaster and drywall or metal particles that are often produced in significant quantities during use. It is also effective to retain the blade in jam situations or when scroll cutting which often applies side and twisting forces to the blade. The clean design also utilizes a small number of parts and has a relatively low weight of the assembly which is desirable in order to minimize vibrations. 
         [0019]    Turning now to the drawings, preferred embodiments of which are shown in  FIGS. 1-7 , a tool-less locking mechanism is indicated generally at  10  that has a relatively few number of parts that collaborate with a reciprocating spindle or plunger that is part of a reciprocating tool such as a jigsaw or reciprocating saw that is not shown in the drawings. The spindle  12  has a preferably cylindrical shape with a slightly reduced diameter front portion  14  that forms an annular shoulder  16 . 
         [0020]    The front portion  14  has an axially oriented slot  18  that is configured to receive a blade such as blade  20 . The blade  20  has a shank portion  22  that has a hole  24  which the mechanism  10  engages to retain the blade in the slot  18  of the spindle  12 . The shank portion has an elongated extension  26  which is helpful to hold the blade  20  at a constant angle in the slot  18  when the mechanism is in a clamped position. 
         [0021]    As best shown in  FIG. 2 , the front portion  14  has an aperture  28  that extends from the near side of the spindle to the slot  18 , and may extend completely through the entire spindle if desired. However, it is preferred that the aperture extending to the other side of the slot  18  have a reduced diameter as shown in  FIG. 3  so that the a detent pin  34  cannot fall through the other side. Alternatively, the other side of the slot could merely have a recess of sufficient depth that it would securely hold the blade  20  as shown in  FIG. 3 . A second aperture  30  is also provided and it extends completely through the entire spindle and is sized to receive a roll or solid pin  32  that is force fit therein when the mechanism is finally assembled. 
         [0022]    The aperture  28  is sized to receive a detent pin  34 , which is slidable in the aperture  28  and has a truncated conical inner end portion  36  as best shown in  FIG. 3 . The detent pin  34  is sized so that the conical end portion  36  will penetrate into the aperture  24  and engage the blade  20 . The opposite end of the detent pin  34  preferably has a slightly rounded surface  38 . 
         [0023]    The mechanism  10  also has a sleeve, indicated generally at  40 , a rotatable collar, indicated generally at  42 , a cover, indicated generally at  44 , a spring, indicated generally at  46 , and in some of the embodiments also a clip  48 . Embodiments of the mechanism may not include the cover  44 , inasmuch as it is an aesthetic component that does not perform an important operational function. 
         [0024]    The sleeve  40  also has an aperture  50  and a second smaller aperture  52 . The aperture  50  is substantially the same size as the aperture  28  of the spindle portion  14 , but may be slightly larger if desired. The aperture  52  is substantially the same size as the aperture  30  in the spindle front portion  14 , but it too may be slightly larger if desired. It is important that the aperture  50  be sized to enable the detent pin  34  to slide within it and the aperture  52  must be sufficiently large that the roll pin  32  may be inserted into it. 
         [0025]    It is preferred that the inside diameter of the sleeve  40  be substantially the same size as the front portion  14  of the spindle  12  and in fact may be slightly smaller than the diameter. It is preferred that the sleeve  40  be pressed onto the front portion  14  and if it is slightly smaller than the diameter of this front portion  14 , it will slightly narrow the width of the slot  18  by flexing the two sides together and thereby control the width of the blade gap or slot  18 . If the size of the apertures  52  are substantially the same size as the aperture  30 , then the roll pin  32  will engage the sleeve  40  on opposite sides. Since the sleeve  40  is preferably press fit on the spindle front portion  14 , the extreme front edge is preferably chamfered or otherwise rounded to more easily assemble the cover as well as the sleeve  40   
         [0026]    Certain embodiments of the sleeve  40  may include an annular recess  54  that has a width preferably slightly larger than the thickness of the clip  48  so that the clip can be installed in the recess  54 . For those embodiments which do not utilize a clip  48 , the recess  54  may not be present. There is a pair of axial grooves  56  located on opposite sides of the front end of the sleeve. These do not perform a function with regard to the operation of the mechanism, but are provided for manufacturing purposes to angularly orient the sleeve when it is pressed onto the spindle so that the apertures  50  and  52  are in alignment with the apertures  28  and  30  of the spindle. 
         [0027]    The preferred embodiments of the mechanism also have a plurality of spiral grooves  58  in the outer surface of the sleeve  40 . While there are four of such grooves  58  shown in the drawings, it should be understood that a greater or lesser number of grooves can be provided. It is also contemplated that the grooves may not have the spiral angle as shown, but may be at a different angle, including a 0 degree angle (parallel to the axis of the sleeve  40 ) or a 90 degree angle or they may intersect one another. Also, as is best shown in  FIGS. 4 and 5 , the spiral grooves  58  extend from the annular groove  54  rearwardly to the back end surface  60 . In the event that the annular recess  54  is not present, the grooves may desirably extend from the front surface  62  to the rear surface  60  so that during operation, dust can be more effectively expelled from the front of the sleeve. The grooves can also have a width greater than that shown and may be somewhat deeper as well. It is preferred that the depth and width not be excessive relative to the thickness of the sleeve itself so as to compromise its structural rigidity and strength. 
         [0028]    The grooves are provided to improve the reliability of operation of the mechanism in an environment that produces large amounts of dust, such as dust or particulate material and the like. When the collar  42  is rotated during insertion of the blade  20  in the slot  18 , the rotating movement of the collar will move dust particles into the grooves  58 . When the tool is operated, the reciprocating movement of the spindle  12  will eject the dust particles from the grooves  58  and the blade holder mechanism thereby achieves a self-cleaning capability. Such self-cleaning capability may be improved by embodiments that do not include the clip  48 . 
         [0029]    The collar  42 , best shown in  FIGS. 6 and 7  but also shown in  FIGS. 1 ,  2  and  3 , is designed and configured to fit over the sleeve  40 , with an inside surface  64  being slightly larger than the outside surface of the sleeve  40 . The collar  42  has an inner member  66  which is preferably made of steel or other strong material and also has an outer layer  68  that is preferably made of a resilient material such as rubber, plastic or other flexible material. The outer layer  68  has a number of raised ribs  70  that provide a gripping surface for a user. Alternatively, recesses rather than ribs may be formed in the outer layer  68 . 
         [0030]    The inner member  66  has an aperture  72  that is sized and configured to receive an axially oriented end  74  of the spring  46 , an opposite end  76  of the spring being perpendicular to the end  74  and being inwardly directed relative to the coils of the spring so that it will fit within the end of the slot  18 . The collar  42  is rotatable on the sleeve  40  and it has a pair of opposed slots  78  that extend through an angular arc of approximately 60-90°. These slots  78  are sized to receive respective ends of the roll pin  32 . The roll pin  32  has a length so that it extends slightly beyond the inner member  66  but does not extend beyond the outer surface of the outer layer  68 . The roll pin  32  that extends through the entire assembly, provides limits for the collar rotation and securely mounts the mechanism to the spindle  12 . 
         [0031]    It should be understood that the length of the slots  78  effectively limits the angle of rotation of the collar  42  relative to the sleeve  40  and effectively controls the rotation from a clamped to an unclamped position. The inner member  66  also has a cam surface  80  that gradually changes from the center axis of rotation from a maximum radius at location  82  to a minimum radius at location  84 . The cam surface is axially positioned on the collar  42  so that it is positioned to contact the rounded end  38  of the detent pin  34 . The fact that the roll pin  32  extends through both sides of the collar  42  provides added stability to the cam surface  80  controlling the detent pin  34 . 
         [0032]    As the collar is rotated to engage the rounded end  38  and move it into its clamped position shown in  FIG. 3 , the portion of the cam surface approaching the end  84  will cause it to be held so that the conical end portion  36  is inserted into the hole  24  in the blade and hold it in this position. The spring  46  is a torsion spring and it is twisted relative to the end  76  so that when the end  74  is placed in the aperture  72  a biasing force is produced which tends to move collar toward its clamped position, i.e., counterclockwise as shown in  FIG. 6 . 
         [0033]    When a user wishes to insert a blade  20  into the slot  18  and have it clamped, it is necessary for the user to rotate the collar  42  in a clockwise direction as shown in  FIG. 6  which will enable the blade to be pushed into the slot  18  and the shank end  22  of the blade can impinge upon the conical end portion  36  and push it away from the blade so that it can be fully inserted whereby the hole  24  is aligned with the detent pin  34 . The user can then merely release the collar  42  and the spring  46  will cause the collar  42  to rotate into the clamped position where the blade will be firmly held in place. 
         [0034]    It should be understood that the roll pin  32  effectively retains the collar  42  in place in an axial direction, even though it is free to rotate through the arc defined by the slots  78 . However, in those embodiments in which additional support is desired, the clip  48  can be employed. 
         [0035]    The illustrated mechanism also includes the cover  44  which has an outer conical shaped portion  86 , an end portion  88  having an outer surface that engages the shoulder  16  of the spindle  12  and an inner portion  90  that has a diameter approximating the outside diameter of the reduced front portion  14 . It is hollow inside and fits around the spring  46 . The outside diameter of a front end portion  92  is slightly less than the diameter of the inner member  66  of the collar  42 . The cover  44  also has a slot  94  through which the spring end can pass to enter the slot  18  of the spindle front portion  14 . 
         [0036]    In the event that the various embodiments of the present invention are installed on power tools that experience excessive forces during operation, the materials from which the present apparatus are made is preferably steel or other hard metal, with the exception that the spring retainers do not normally experience excessive stresses and therefore may be fabricated from plastic or plastic-like material. 
         [0037]    While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims. 
         [0038]    Various features of the invention are set forth in the following claims.