Saw blade clamp arrangement for a power tool

Abstract: A reciprocating saw 10 with a reciprocating shaft 30 connected to a cutting member 38 has a clamping arrangement 56'' comprising a pincer for retaining the saw blade. The pincer is formed by a locking member 310 and a locating pin 360 which cooperate to prevent inadvertent removal of the saw blade. The saw blade clamping arrangement further includes a support member 58 carried by the drive shaft for movement therewith. The support member at least partially defines a longitudinal slot 318 for receiving the saw blade. The locating pin extends into the longitudinal slot and is adapted for partial insertion into the aperture 40 from a first side of the saw blade. The locking member, which in the preferred embodiment is a spherical bearing 310 , is operative for selectively engaging the saw blade with the drive shaft. The locking member is movable to a locking position in which the locking member is partially inserted into the aperture 40 from a second side of the saw blade.

Description: The present invention relates in general to power tools. In particular, the present invention relates to a power reciprocating saw according to the preamble of claim 1 and as known, for example from US-A-3.750.283. Power reciprocating saws include jigsaws and other reciprocating saws generally referred to in the trade as "recip" saws. These saws incorporate reciprocating shafts for driving generally linear saw blades along a predetermined path so as to provide one of a rectilinear or orbital cutting action. In a conventional manner, the saw blades used with such power tools are attached to the reciprocating drive shafts through a blade holder having a slot for receiving the saw blade and a set screw which is received in a hole in the blade. The blade is clamped in place relative to the reciprocating drive shaft through tightening of the set screw. While this manner of saw blade attachment has proven to be generally satisfactory and commercially successful, it is not without inherent disadvantages. For example, power reciprocating saws are subject to high vibration forces during operation which frequently result in loosening of the set screw. If the set screw does not remain sufficiently tightened, the saw blade may become disengaged from the drive shaft. An additional disadvantage with the conventional mounting of saw blades to reciprocating drive shafts relates to an inability to quickly and easily remove saw blades which become worn or fractured. Because it is often desirable to cut a workpiece with minimum material loss, it is desirable to correspondingly minimize the saw blade thickness. As a result, breakage due to the forces encountered during typical use is not an uncommon occurrence. This potential frequency of blade changing makes the ease and rapidity of such action desirable. A further disadvantage of conventional blade mounting arrangements is the necessity for a separate tool such as a wrench for fixation and removal of the saw blade. Many previous attempts have been made to overcome the disadvantages associated with the above-described conventional mounting of saw blades through elimination of the use of a set screw. One example of such a saw blade mounting arrangement is shown in U.S. Patent No. 5,322,302. The saw blade mounting arrangement described in this patent includes a mounting body which urges a clamping sphere through the biasing force of a spring into clamping engagement with a saw blade. Removal of the saw blade is facilitated through actuation of a lever which serves to overcome the biasing force exerted by the spring. Operation of this device requires a first of the operator's hands to actuate the lever and a second of the operator's hands for removal or installation of the saw blade. In other words, the actuating lever of this device is not movable to a stable, non-clamping position and necessarily requires two-handed operation - an action which is not always convenient. Other previous attempts to secure saw blades to a reciprocating drive shaft of a power tool without the conventional use of a set screw are shown in U.S. Patent Nos. 3,542,097; 3,823,473; 4,020,555; 4,106,181; 4,441,255; 4,594,781; 4,470,196; 4,528,753; 4,601,477; 4,648,182; 5,113,565; 5,263,972; and 5,324,052. In general, each of the devices shown in these patents represents an attempt to overcome one or more of the disadvantages associated with conventional set screw attachment of a saw blade to a reciprocating drive shaft, including but not limited to the disadvantages discussed above. However, all of these devices are subject to further refinement and improvement. For example, many of the devices, including U.S. Patent No. 5,322,302, disadvantageously require two-handed operation. Additionally, most of the devices shown in these patents are complicated and expensive to manufacture and assemble as a result of a construction including many separate parts. Further, operation of many of the prior devices requires application of force which is often significant for securing the saw blade in place and loosening of the blade for separation from the drive shaft. Achieving a sufficient force often requires the use of a wrench or other tool. Other disadvantages associated with these prior devices include an inability to cooperate with conventionally shaped saw blades. US Patent Application Serial No. 3750283 discloses a number of embodiments of a blade attachment means for attaching a saber saw blade to the reciprocating portion of a saber saw assembly. In the embodiment shown in Figures 7a-c in particular, a saw blade is secured within the slot of an extension of a shaft, whereby the shaft is secured to a power device such that the shaft, and thereby the blade, can reciprocate. The attachment means includes a ball bearing, which is located on the extension within the slot, and a pin which is also located on the extension within the slot, whereby the ball bearing may be urged towards one side of the saw blade, and the pin may be urged towards the opposite side of the saw blade, thereby clamping the saw blade in place within the slot. Further still, the attachment means includes a control member in the form of a sleeve, which surrounds the extension, and which is axially biased to one side wherein the ball bearing and pin are urged towards the blade in order to secure the blade in place within the slot. According to the present invention, there is provided a power reciprocating saw comprising: a housing; a drive shaft mounted for reciprocating movement in a longitudinal direction relative to the housing; a saw blade having an aperture; and a clamping arrangement for selectively mounting said saw blade to said drive shaft, said clamping arrangement including: (i) a support member carried by the drive shaft for movement therewith, said support member at least partially defining a longitudinal slot for receiving the saw blade; and (ii) a pincer attached to the support member for insertion into the aperture from first and second sides of the blade; and (iii) a control member moveable from a first position to a second position to control insertion of the pincer into the aperture; characterized in that the saw further comprises an actuation member attached to the reciprocating saw, said actuation member being longitudinally fixed with respect to said housing, said actuation member moveable between a clamping position in which said control member is translated to said first position for urging at least part of said pincer into operative engagement with said saw blade and a release position in which said control member is translated to said second position for permitting displacement of said part of pincer from said saw blade. The pincer preferably comprises a locating pin extending into the slot from the first side of the blade and locking member operative for selectively engaging with the saw blade and movable to a locking position wherein the locking member is partially inserted into the aperture from the second side of the blade. The locking member may comprise a spherical bearing. Preferably, said control member is translatable from a first position to a second position for moving said locking member to said locking position. A biasing member preferably biases the control member to the first, locked, position. The control member may include a camming surface for urging said locking member into engagement with said saw blade. The actuation member is preferably a release lever mounted for pivotal movement about a pivot axis parallel to and spaced apart from said saw blade between the clamping position and the release position. Additional objects and advantages of the present invention will become apparent from a reading of the following detailed description of the preferred embodiments which makes reference to the drawings of which: Figure 1 is a side elevational view of a reciprocating saw incorporating a saw blade clamping arrangement constructed in accordance with the teachings of an embodiment of the present invention; Figure 2 is an exploded perspective view of the saw blade clamping arrangement of the present invention; Figures 3-12 illustrate an earlier embodiment of the present invention and serve to show some components of the present invention primarily illustrated in Figures 13-27. Figure 3 is an enlarged side view of the clamp support member shown in Figure 2; Figure 4 is an enlarged end view of the clamp support member; Figure 5 is an enlarged side view of the clamp spring member shown in Figure 2; Figure 6 is an enlarged end view of the clamp spring member; Figure 7 is a partial side view of the saw blade clamping arrangement of Figure 1, illustrating interconnection of the drive shaft with a conventional saw blade; Figure 8 is a partial cross-sectional view of the keyless saw blade clamp of Figure 1 taken along the line 8-8 of Figure 1 illustrated with the end plate of Figure 2 removed for purposes of clarity; Figure 9 is a partial view of a mounting portion of a first alternative saw blade configuration acceptable for use with the saw blade clamping arrangement of the present invention; Figure 10 is a partial view of a mounting portion of a second alternative saw blade configuration acceptable for use with the keyless saw blade clamping arrangement of the present invention; Figure 11 is a cross-sectional view of the clamping assembly of Figure 1 taken along the line 11-11 of Figure 1, illustrating the release lever rotated to a first stable position in which the clamp spring member of the clamping assembly biases the saw blade into operative connection with the drive shaft; Figure 12 is a cross-sectional view similar to that shown in Figure 11, illustrating the release lever in a second stable position in which the clamp spring member is displaced from the saw blade by the release lever, thereby permitting the saw blade to be easily removed from the clamp assembly; Figure 13 is a side view of a portion of a reciprocating saw illustrated to include a partial cross-sectional view of a saw blade clamping arrangement constructed in accordance with the teachings of a preferred embodiment of the present invention; Figure 14 is an end view of the reciprocating saw of Figure 13, illustrating the saw blade clamping arrangement in a clamped position; Figure 15 is an end view similar to Figure 14, illustrating the saw blade clamping arrangement in a release position; Figure 16 is an enlarged side view of the saw blade clamping arrangement of Figure 13 shown removed from the reciprocating saw for purposes of illustration; Figure 17 is an end view of the saw blade clamping arrangement of Figure 15; Figure 18 is a top view of the clamp support member of Figure 17; Figure 19 is a top view of the clamp support member of Figure 17; Figure 20 is a side view of the slider member of Figure 17; Figure 21 is a cross-sectional view taken along the line 21-21 of Figure 20; Figure 22 is an end view of the collar of Figure 17; Figure 23 is a side view of the collar of Figure 17; Figure 24 is a cross-sectional view taken along the line 24-24 of Figure 22; Figure 25A is a perspective view of a first end of an outer member of an alternative collar for use with saw blade clamping arrangement of the preferred embodiment of the present invention; Figure 25B is a perspective view of a second end of the outer member; Figure 26A is a perspective view of a first end of an inner member intended to cooperate with the outer member of Figure 23; Figure 26B is a perspective view of a second end of the inner member; and Figure 27 is a view similar to Figure 19, enlarged and illustrating the saw blade held in position within the clamp by the bearing and the locating pin. The present invention provides an improved saw blade clamping arrangement for a power tool. While shown throughout the drawings in various embodiments for a saw blade clamping arrangement specifically adapted for a reciprocating saw, those skilled in the art will appreciate that the invention is not so limited in scope. In this regard, the teachings of the present invention will be understood to be readily adaptable for use with any power tool incorporating one or more reciprocating cutting members (e.g., reciprocating saws, jig saws, various surgical saws and culinary knives, etc.). Turning generally to the drawings in which identical or equivalent elements have been denoted with like reference numerals. Figures 1 and 2 illustrate a power tool embodying the present invention generally. Figures 3-12 illustrate an earlier embodiment of the present invention and serve to explain certain aspects and components of the present invention. A power tool with a clamping arrangement of the present invention is primarily illustrated in Figures 13-27. The exemplary power tool in Figures 1 and 2 embodying the teachings of the present invention is a power reciprocating saw which has been identified generally at reference numeral 10. In a conventional manner, power reciprocating saw 10 is powered by a motor (not shown) that is actuated by a trigger switch 12. The delivery of electrical energy to the motor through a power cord (partially shown at 14) is controlled by trigger switch 12. In the exemplary embodiment illustrated, power tool 10 is shown to include a handle portion 16 which carries trigger switch 12. Power tool 10 is also shown to include a housing 18 that includes a centrally located motor housing portion 20 and a forwardly located gear case housing portion 22. As shown most clearly in Figure 2, gear case housing portion 22 is formed to include a front face 24 having a generally rectangular aperture 26 which defines the opening of a longitudinally extending drive shaft channel 28. Power tool 10 further includes a drive shaft 30 partially extending within drive shaft channel 28 and operatively connected with a drive mechanism (not shown) housed within gear case housing portion 22. This interconnection between the drive mechanism and drive shaft 30 can be in any manner well known in the art. Drive shaft 30 is mounted for reciprocating motion generally along the longitudinal axis defined by power tool 10. As shown in Figures 1 and 2, the housing 18 includes first and second forwardly extending sidewall members 32 and 34 interconnected with gear case housing portion 22. In the preferred embodiment, first and second forwardly extending side wall members 32 and 34 are integrally formed with gear case housing 22 and are constructed of aluminum, magnesium or other suitable lightweight metal. The particular configuration and function of first and second forwardly extending sidewall members 32 and 34 will be described in detail below. Drive shaft 30 is adapted to cooperate with a cutting member such as a saw blade 38 for driving the saw blade 38 back and forth in a cutting motion along a rectilinear path. In this regard, reciprocating drive shaft 30 is formed to include a transversely extending aperture 40 for receiving a drive pin 42 (shown in Figure 7). An interference fit retains drive pin 42 within aperture 40. The saw blade construction shown in Figures 1 and 7 conventionally includes a forwardly located cutting portion 44 integrally formed with a rearwardly located mounting portion 46. In a manner well known in the art, an aperture 48 formed in mounting portion 46 of saw blade 38 receives drive pin 42 when saw blade 38 is mounted to reciprocating drive shaft 30. The exposed end of drive pin 42 extends from a first side wall 52 (shown in Figure 8) of reciprocating shaft 30 in a dimension approximately equivalent to the thickness of saw blade 38. According to an earlier embodiment of the present invention, power tool 10 may include a clamping arrangement 56 for releasably maintaining saw blade 38 in operative connection with reciprocating drive shaft 30. Clamping arrangement 56 is shown throughout the drawings to include a clamp support member 58, a biasing member 60, and a actuation member 62. The remainder of this detailed description of the preferred embodiment will be primarily directed to the construction and operation of clamping arrangement 56 which is the focus of the present invention. Referring specifically to Figures 3 and 4, the construction and operation of the clamp support member 58 will be described. In the exemplary embodiment shown throughout the drawings, clamp support member 58 is illustrated as a separate element which is adapted to be interconnected with reciprocating drive shaft 30 for movement therewith. However, it will be appreciated by those skilled in the art that clamp support member 58 and drive shaft 30 may alternatively be integrally formed as a single component. Clamp support member 58 is unitarily constructed of a hardened steel or other suitable material. Interconnection between clamp support members 58 and drive shaft 30 is established through a roll pin 68 in interference fit engagement with a transversely extending aperture 70 passing through clamp support member 58 and a corresponding aperture 72 disposed in reciprocating drive shaft 30. Clamp support member 58 includes a main body portion 73 which partially defines a longitudinally extending channel 74 sized to receive reciprocating drive shaft 30. More particularly, the longitudinal channel 74 is defined by an inner wall 75 and by first and second opposing side walls 76 and 78 which each terminate at end walls 80 and 82, respectively. Inner wall 75 is concavely curved to receive a second side wall 79 of reciprocating drive shaft 30. In the first preferred embodiment, a first side wall 52 of reciprocating drive shaft 30 is adapted to sit flush with end walls 80 and 82 (as shown in Figures 11 and 12). End walls 80 and 82 cooperate with first side wall 52 to provide a surface against which saw blade 38 is disposed when operatively connected with a power tool 10. Adjacent an upper surface 86, clamp support member 58 is formed to integrally include an L-shaped flange 88 which partially defines a channel 90 for receiving an upper surface 94 of saw blade 38. Adjacent a lower surface 96, clamp support member 58 includes an outwardly extending portion 98 adapted to abut a lower surface 100 of saw blade 38. Upper surface 86 of clamp support member 58 includes a pair of spaced, upwardly extending flange portions 102 and 104. As will be appreciated below, flange portions 102 and 104 cooperate to limit longitudinal movement of biasing member 60. A second transversely extending channel 108 is partially defined between the main body portion 73 of clamp support member 58 and a downwardly extending portion 110 of a rear wall 112 of clamp support 58. Channel 108 is open along a bottom side. Referring specifically to Figure 6, the biasing member of the present invention is preferably illustrated as a spring clamp member 60. Spring clamp member 60 is adapted to be directly carried by clamp support member 58 for movement with reciprocating drive shaft 30. Spring clamp member 60 is generally C-shaped and is integrally formed of a resilient metal or other suitable material to include a curvilinear central portion 120 and first and second ends 122 and 124. In one application, spring clamp member 60 is constructed of .050 inch steel. A side view of clamp spring member 60 is shown in Figure 6 in a substantially unloaded condition. An aperture 125 passes through central portion 120 which is adapted to accept an end of drive pin 42 when a saw blade is not in clamping arrangement 56. Clamp spring member 60 further includes generally linear upper and lower segments 126 and 128 integrally attached to opposite ends of curvilinear central portion 120. Upper and lower segments 126 and 128 are disposed generally transverse to curvilinear central portion 120 and cooperate with the curvilinear central portion 120 to partially define a longitudinally extending opening 130 for receiving a portion of clamp support member 58 and reciprocal drive shaft 30. Spring clamp member 60 is further shown to include a retaining portion 132 adjacent second end 124 which is adapted to be constrained within longitudinal channel 108 of clamp support member 58. Spring clamp member 60 further integrally includes a spring tab portion 136 adjacent first end 122 which extends upwardly relative to upper segment 126 and is angled slightly rearwardly in the direction of curvilinear central portion 120. Spring tab portion 136 is free from direct constraint with respect to clamp support member 58. When assembled and in clamping engagement with drive shaft 30 and saw blade 38, lower segment 128 of spring clamp member 60 is positioned adjacent bottom surface 96 of clamp support member 58. In an unloaded condition, upper segment 126 of spring clamp member 60 is arranged to be positioned substantially adjacent upper surface 86 of clamp support member 58. As discussed above, longitudinal translation of spring clamp member 60 is limited by flange portions 102 and 104 of clamp support member 58. Curvilinear central portion 120 includes a lower, outwardly curved segment 139 which accommodates saw blade 38 and an upper, outwardly curved segment 140. Curvilinear central portion 120 further includes an inwardly curved central portion 142 arranged to directly contact saw blade 38. It will be appreciated by those skilled in the art that the particular construction of spring clamp 60 is subject to modification without departing from the scope of the present invention. Any construction will be suitable which incorporates a portion for fixation to clamp support member 58, a portion for directly biasing saw blade 38 and a displaceable free end. While in a clamping position such as that shown in Figure 11, clamp spring member 60 functions to exert a biasing force against saw blade 38 through contact of central portion 142 and saw blade 38. The biasing force serves to retain saw blade 38 in operative connection with reciprocating drive shaft 30 by preventing saw blade 38 from moving transversely with respect to drive shaft 30. It will be appreciated by those skilled in the art that clamping arrangement 56 of the earlier embodiment of the present invention is able to accommodate saw blades of various configurations without modification. By way of example and not of limitation, two alternative saw blade constructions suitable for use with clamping arrangement 56 are illustrated in Figures 9 and 10. Referring to Figure 9, a first alternative saw blade 38' includes a generally rectangular mounting portion 46' formed with an aperture 48' sized to receive drive pin 42. In Figure 10, a second alternative saw blade 38'' is shown to include an aperture 48" and a longitudinally extending slot 144. Any of a number of other known saw blade constructions may be releasably interconnected to drive shaft 30 through clamping arrangement 56 of the present invention. As shown throughout the drawings, actuation member of the present invention is preferably illustrated as a release lever 62 operative to overcome the biasing force of spring clamp member 60 and thereby facilitate removal and replacement of saw blade 38. In the exemplary embodiment illustrated, release lever 62 is mounted for pivotal movement between a first stable position or clamped position (shown in Figure 11) and a second stable position or unclamped position (shown in Figure 12). Significantly, when release lever 62 is in its first stable position, it is spaced apart from spring clamp member 60 permitting release lever 62 to remain longitudinally fixed with respect to housing 18. Thus, release lever 62 remains relatively stationary as reciprocating drive shaft 30 operates, thereby reducing the weight translated back and forth by drive shaft 30 and also reducing attendant vibration forces. To facilitate pivotal mounting of release lever 62, power tool 10 further includes an end plate 150 interconnected with first and second forwardly extending sidewall members 32 and 34. As shown in Figure 2, end plate 150 is generally planar and has a configuration similar to front face 24 of gear case housing 22. End plate 150 includes an aperture 152 through which saw blade 38 is permitted to pass. In the embodiment illustrated, end plate 150 is attached to first and second forwardly extending side wall members 32 and 34 by a plurality of threaded fasteners 154 adapted to pass through four apertures 156 provided in the end plate. Fasteners 154 are adapted to engage threaded holes 158 located in boss portions 160 on each of the forwardly extending side walls members 32 and 34. In the embodiment illustrated, boss portions 160 are located along the free ends of first and second forwardly extending side wall members 32 and 34. It will be appreciated by those skilled in the art that end plate 150 can be alternatively attached to forwardly extending side wall members 32 and 34 in any of a number of other well known manners. In this regard, it is anticipated that end plate 150 could alternatively be welded to forwardly extending side walls members 32 and 34. Release lever 62 has a generally L-shaped cross section including a first leg 170 and a second leg 172. The longitudinal length of release lever 62 is sufficient to extend along the entire travel path of spring clamp member 60 as drive shaft 30 is reciprocated. A longitudinally extending aperture 174 passes through the length of release lever 62 at the junction of first and second legs 170 and 172 and is adapted to receive a pivot pin 176. Pivot pin 176 includes a first end 178 adapted to engage an aperture 180 formed in front face 24 and a second end 182 adapted to engage an aperture 184 located in end plate 150. Second end 182 is of a reduced diameter so as to prevent forward translation of pin 176. As shown in Figures 11 and 12, release lever 62 is formed to include a recess or pocket 188 configured to accommodate a torsion spring 190. Torsion spring 190 functions to bias release lever 62 towards its first stable position (as shown in Figure 11) and includes a central portion surrounding an adjacent portion of pivot pin 176. Torsion spring 190 also includes a fixed end 194 in engagement with a boss portion 196 of recess 188. Torsion spring 190 further includes a free end 198 adapted to engage a stop pin 200 extending from front face 24 of gear case housing 22. Stop pin extends into recess 180 to avoid interference with release lever 62. As shown most clearly in Figures 11 and 12, second forwardly extending wall member 34 is generally S-shaped in cross section and includes an upper segment 208 providing a stop surface 210 arranged to support release lever 62. Upper segment 208 serves to prevent further rotation of release lever 62 in a counterclockwise direction as shown in Figures 11 and 12. First leg 170 of release lever 62 transversely extends slightly beyond an upper vertical segment 212 of second forwardly extending wall member 34 so that the operator can grasp a free end 214 of first leg 170. First forwardly extending side wall member 32 is generally L-shaped in cross-section and is formed along the perimeter of a corresponding portion of front face 24 of gear case housing 22. An upper segment 216 of second forwardly extending side wall member 34 terminates at a stop surface 218 for engaging release lever 62 when release lever 62 is rotated to its second stable position (as shown in Figure 12). Second leg 172 of release lever 62 includes an engagement surface 222 adapted to contact spring tab portion 136 of spring clamp member 60. As shown in Figure 12, clockwise rotation of release lever 62 about a longitudinal pivot axis defined by pivot pin 176 results in contact between engagement surface 216 of second leg 172 and spring tab portion 136 of spring clamp member 60. The length of second leg 172 is significantly less than the length of first leg 170, thereby providing a mechanical advantage for overcoming the biasing force exerted by spring clamp member 60. The pivot axis of release lever 62 defined by pivot pin 176 is disposed relative to engagement surface 222 of second leg 172 so as to provide an over-centered relationship therebetween. As a result, as release lever 62 approaches its second stable position (as shown in Figure 12), the opposing biasing force of spring clamp member 60 urges release lever 62 against stop surface 218 of first forwardly extending wall portion 32. With particular reference to Figures 11 and 12, the operation of the clamping arrangement 56 of the earlier embodiment of the present invention heretofore detailed will now be described. Beginning with saw blade 38 operatively connected to reciprocating drive shaft 30, release lever 62 is rotated in a clockwise direction from its first stable position (shown in Figure 11) by manual urging of first leg 170 to overcome the biasing force of torsion spring 190. Initial clockwise rotation causes second leg 172 of release lever 62 to engage spring tab portion 136 of spring clamp member 62. Continued clockwise rotation of release lever 62 serves to transversely displace spring tab portion 136 and to overcome the biasing force of spring clamp member 62 by elastically deforming spring clamp member 60. More specifically, elastic displacement of spring tab portion 136 creates a gap 224 between curvilinear central portion 120 of spring clamp member 60 and saw blade 38. As release lever 62 approaches its second stable position, the over-centered relation between engagement surface 222 of second leg 172 and the pivot axis defined by pivot pin 176 causes the biasing force of spring clamp member 60 to further urge release lever 62 in a clockwise direction against stop surface 218. At this point, release lever 62 will stay in its second stable position until urged in the direction of its first stable position. As a result, both of the operator' hands are free for handling replacement of saw blade 38 or other necessary tasks. Saw blade 38 can now be removed from power tool 10 and a new blade can be inserted into gap 224 between spring clamp member 60 and reciprocating drive shaft 30. Upper edge 94 of saw blade 38 is located in channel 90 and aperture 48 is positioned over drive pin 42. Operating interconnection between saw blade 38 and reciprocating drive shaft 30 is established by manual urging of release lever 62 in a counterclockwise direction. Following initial counterclockwise movement of lever 62, the biasing force of spring clamp member 60 urges release lever 62 to its first stable position. Turning now to Figures 13-27 of the drawings, a saw blade clamping arrangement 56" constructed in accordance with the preferred embodiment of the present invention will now be described. Components similar to those identified with respect to the earlier embodiment will be designated in the drawings with conesponding reference numerals. As with the earlier embodiment, saw blade clamping arrangement 56'' is operative for use with power tool 10 such as reciprocating saw or other tool including a reciprocating drive shaft 30. As with earlier embodiment of the present invention, saw blade clamping arrangement 56'' of the preferred embodiment includes a support member 58, a biasing member 60 and an actuation member 62. Saw blade clamping arrangement 56'' of the preferred embodiment departs from the earlier embodiment in that it additionally incorporates a pincer (constituted by a locking member 310 and a locating pin 360) to operatively interconnect saw blade 38 to drive shaft 30, a control member 312 operative to engage the pincer by displacing locking member 310, and a collar 314 movably supporting control member 312. The remainder of this detailed description will address departures in construction and function of the preferred embodiment from the prior embodiment. Drive shaft 30 of the preferred embodiment is generally cylindrical and includes an open distal end 232 for receiving a first end 234 of support member 58. Preferably, first end 234 of support member 58 and shaft 30 are press-fit together and brazed. Alternatively, it will be appreciated by those skilled in the art that any suitable manner may be utilized to operatively interconnect support member 58 with drive shaft 30. With specific reference to Figures 18 and 19, clamp support member 58 of tool 56 is shown to include a pair of spaced apart legs 316. A generally rectangular channel 318 (best shown in Figure 17) is partially defined by the pair of legs 316 and extends substantially the entire length of legs 316 and is adapted to receive mounting portion 46 of saw blade 38. Support member 58 further includes a transversely extending elongated hole 320. Aperture 320 extends through a first leg 316a and intersects rectangular channel 318. Upon insertion of saw blade 38 into channel 318, aperture 320 is substantially aligned with aperture 48 in mounting portion 46 of saw blade 38. As will become apparent immediately below, aperture 320 is configured to receive locking member 310 (which constitutes one element of the pincer). Locking member 310 of the preferred embodiment is shown to preferably comprise a spherical bearing 310. Bearing 310 has a diameter slightly smaller than the width of elongated hole 320. The elongated configuration of the hole allows the bearing 310 to float and easily locate hole 48 in saw blade 38. With reference now to Figures 14, 15, 20 and 21, control member 312 of the preferred embodiment will now be described. Control member 312 is interconnected to support member 58 so as to be linearly translatable with respect thereto. In the embodiment illustrated, control member 312 is linearly translatable in a direction substantially perpendicular to the direction of reciprocal motion of drive shaft 30 between a first position and a second position. As will be discussed further below, control member 312 is operatively retained relative to support member 58 through collar 314. Control member 312 is operative for selectively urging bearing 310 into engagement with saw blade 38 to thereby operatively engage saw blade 38 with drive shaft 30. More particularly, in a first position, as shown specifically in Figure 14, control member 312 urges bearing 310 into engagement with saw blade 38. In this first position, bearing 310 is partially inserted into aperture 46 from a first side of saw blade 38. In its second position, as shown in Figure 15, control member 312 permits bearing 310 to be displaced from a position engaged with aperture 46 of saw blade 38, thereby permitting removal and replacement of saw blade 38. With continued reference to Figure 20 and the cross-sectional view of Figure 21, control member 312 is shown to include a channel 326 for at least partially receiving bearing 310. The channel 326 includes a dish-shaped pocket 328 and a concavely curved trough 330. Trough 330 is defined by a camming surface which is angled such that trough 330 is most shallow at a point displaced from cavity 328. When control member 312 is in its second position (as shown in Figure 15), locking member 310 is substantially centered within cavity 328 of channel 326. As a result, bearing 310 can be displaced from a position in which it is engaged with aperture 46 of saw blade 38. As control member 312 is moved from its second position to its first position, bearing 310 rides along trough 330. Given the angular orientation of trough 330, bearing 310 is resultantly forced toward rectangular channel 318 and into engagement with aperture 46 of saw blade 38. With reference to Figures 22-24, collar 314 of the preferred embodiment of the present invention will now be described. As noted above, collar 314 functions to interconnect control member 312 with support member 58, and in turn drive shaft 30. Collar 314 includes a main body portion 332 which defines a central aperture 334 adapted to receive the pair of legs 316 of the support member 58. As a result, collar 314 effectively circumferentially surrounds support member 58. A cotter pin 336 passes through a hole 338 in main body portion 332 and a corresponding hole 340 in support member 58 to thereby releasably interconnect 314 and support member 58. As shown specifically in Figure 23, collar 314 defines a generally T-shaped channel 339 adapted to slidingly receive control member 312. More particular, T-shaped channel 339 includes a vertically oriented portion 340 and a horizontally oriented portion 342. Vertically oriented portion 340 is specifically adapted to receive a pair of outwardly extending flanges 344 which are integrally formed with control member 312. A flange 346 extends through horizontally oriented portion 342 and slightly beyond. It will be appreciated that in certain applications it may be desirable to provide the collar 314 in two components. For example, a two-component collar may provide manufacturing advantages. With reference to Figures 25 and 26, an alternative two-piece collar 314 for use with the saw blade clamping arrangement 56" of the preferred embodiment. The collar 314 is shown to include two components, namely. An outer member 350 is shown in Figures 25A and 25B. An inner member 352 is shown in Figures 26A and 26 B. The outer and inner members 350 and 352 cooperate to accomplish the functions on the collar 314 discussed above. In the embodiment illustrated, biasing member 60 comprises a coil spring 60 which circumferentially surrounds support member 58. As shown in Figure 16, a first end 350 of coil spring 60 engages an aperture 352 formed in support member 58. A second end 354 of coil spring 60 and aperture 356 formed in flange 346 below control member 312. Coil spring 60 functions to normally bias control member 312 towards its first position (as shown in Figure 14) in which bearing 310 is forced into engagement with aperture 46 of saw blade 38. Referring now to Figures 13-15, the release lever of the preferred embodiment is shown pivotally interconnected to housing 18 for movement between a first position (as shown in Figure 14) and a second position (as shown in Figure 15). In this regard, a pivot pin 176 passes through a longitudinally aperture in release lever 62. First end 182 of pivot pin 186 engages apertures 184 formed in cover plate 150. Second end 178 of pivot pin 176 engages aperture 180. Alternatively, it will be appreciated by those skilled in the art that release lever 62 can be integrally formed to include cylindrical portions extending in opposite directions and effectively replacing pivot pin 176. In the first position, release lever 62 is spaced apart from flange 346 of control member 312. It will be appreciated that release lever 62 does not reciprocate with drive shaft 30. In its second position, release lever 62 displaces control member 312 to its second position, thereby permitting removal and replacement of saw blade 38 in the manner discussed above. In the preferred embodiment, release lever 62 of the preferred embodiment is mounted to tool 10 such that an interference fit is established so as to maintain release lever 62 in its release position. Alternatively, release lever 62 may be mounted to tool 10 such that its second position (as shown in Figure 15) is an over-centered position. In the exemplary embodiment illustrated, the saw blade clamping arrangement 56" of the preferred embodiment is shown to include a locating pin 360 which extends into the longitudinal opening of the support member 58 and is adapted to engage the aperture 46 of the saw blade 38 from a second side of the saw blade 38. Spherical bearing 310 and locating pin 360 together function as a pincer and cooperate to prevent inadvertent removal of saw blade 38 from the longitudinal slot. In this regard, locating pin 360 prevents spherical bearing 310 from being pushed out of aperture 46 when saw blade 38 is under severe loads. Locating pin 360 is adapted to seat in aperture 46 of blade 38 and accordingly serves to further lock blade 38 in place. The diameter of locating pin 360 is smaller than aperture 46 of saw blade 38, thereby permitting spherical bearing 310 and the spring force applied to spherical bearing 310 to locate blade 38 within clamp 58. Specifically, to prevent release of blade 38 from clamp 58 when spherical bearing 310 tends to slide out of the longitudinal blade opening slot, the sidewall of aperture 46 of saw blade 38 engages locating pin 360 and blade 38 is retained within clamp 58. While the above description constitutes a preferred embodiment of the invention, it will be appreciated that the invention is susceptible to modification, variation, and change without departing from the proper scope or fair meaning of the accompanying claims. For example, it will be understood that the teachings of the present invention are directly applicable to other power tools having reciprocating drive shafts, including but not limited to jigsaws.

Claims: A power reciprocating saw comprising: a housing (10); a drive shaft (30) mounted for reciprocating movement in a longitudinal direction relative to the housing; a saw blade having an aperture (40); and a clamping arrangement (56'') for selectively mounting said saw blade to said drive shaft, said clamping arrangement including: (i) a support member (58) carried by the drive shaft for movement therewith, said support member at least partially defining a longitudinal slot (318) for receiving the saw blade; and (ii) a pincer (310, 360) attached to the support member for insertion into the aperture from first and second sides of the blade; and (iii) a control member (312) moveable from a first position to a second position to control insertion of the pincer into the aperture; characterized in that the saw further comprises an actuation member (62) attached to the reciprocating saw, said actuation member (62) being longitudinally fixed with respect to said housing (10), said actuation member (62) moveable between a clamping position in which said control member (312) is translated to said first position for urging at least part of said pincer (310,360) into operative engagement with said saw blade and a release position in which said control member (312) is translated to said second position for permitting displacement of said part of pincer (310,360) from said saw blade. A saw according to claim 1 wherein the pincer comprises: a locating pin (360) extending into the slot from the first side of the blade; and locking member (310) operative for selectively engaging with the saw blade and movable to a locking position wherein the locking member (310) is partially inserted into the aperture from the second side of the blade. A saw according to claim 2, wherein said locking member comprises a spherical bearing (310). A saw according to claims 2 or 3, wherein said control member (312) is translatable from a first position to a second position for moving said locking member (310) to said locking position. A saw according to any of the preceding claims, further comprising a biasing member (60) for biasing said control member (312) to said first position. A saw according to any of the preceding claims, wherein said actuation member (62) is a release lever mounted for pivotal movement between said clamping position and said release position. A saw according to claim 6, wherein said release lever is mounted for pivotal movement about a pivot axis parallel to and spaced apart from said saw blade. A saw according to any one of claims 2 to 7, wherein said control member (312) includes a camniing surface (330) for urging said locking member (310) into engagement with said saw blade.

Inventors: DASSOULAS STEPHEN, MELVIN JASON R, MOORES ROBERT G JR, DASSOULAS, STEPHEN, MELVIN, JASON R., MOORES, ROBERT G., JR.
Applicants: BLACK & DECKER INC, BLACK & DECKER INC.
Application year: 1999
Main classification: B23D51
IPC codes: B23D51