Clamping device for toolless clamping of a saw blade

A clamping device for toolless clamping of saw blades equipped with the clamping shank for a hand machine tool has two clamping parts that are pressable against each other. Each of the clamping parts is provided with a support surface for the clamping shank of a saw blade insertable between the clamping parts. At least one of the clamping parts is movable in relation to the other of the clamping parts in order to clamp and release the clamping shank. An independent actuating element is movable by hand and provides a sliding movement or a rotating movement.

BACKGROUND OF THE INVENTION

The present invention is based on a clamping device for toolless clamping of a saw blade with a clamping shank for a hand machine tool, in particular a hand-guided power reciprocating saw.

A known clamping device of this kind has a support plate for supporting the clamping shank of a jigsaw blade embodied in the form of a single-cam shank, which support plate is snugly inserted into the electric motor-driven lifting rod of the hand-guided power reciprocating saw. The support plate is provided with a number of cams whose placement is adapted to the contour of the single-cam shank so that after the insertion of the single-cam shank, the cam device secures the saw blade against shifting axially on the support plate. Opposite from the support plate, there is a leaf spring whose free end is bent into a hook shape that engages the lower end of the support plate and a likewise bent grip part extending away from it for opening and closing the clamping device. A slot-shaped opening in the bent end permits the lower end of the support plate to pass through when the leaf spring with the bent catch is slid onto the back side of the support plate between the bent end and the grip part. In order to clamp a saw blade, after the grip is grasped, the leaf spring is lifted away from the support plate, the single-cam shank is inserted into the cam device between the leaf spring and the support plate and then the leaf spring is clamped against the back side of the support plate by means of its bent catch. This clamps the single-cam shank to the support plate and prevents a movement lateral to the stroke direction so that it cannot come out of the cam device.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a clamping device for tools clamping of a saw blade, which is a further improvement of the existing devices.

In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a clamping device for toolless clamping of saw blades equipped with the clamping shank for a hand machine tool, said clamping device comprising two clamping parts that are pressable against each other, each of said clamping parts being provided with a support surface for the clamping shank of a saw blade insertable between said clamping parts, at least one of said clamping parts being movable in relation to the other of said clamping parts in order to clamp and release the clamping shank; and an independent actuating element that is movable by hand and providing a movement of said at least one clamping part selected from the group consisting of a sliding movement and rotating movement.

When the clamping device is designed in accordance with the present invention, it has the advantage that by coupling at least one clamping part to an actuating element that executes an axial sliding motion or a rotating motion, a significantly higher clamping force can be exerted on the clamping shank of the saw blade inserted between the clamping parts and can optionally be maintained by means of static friction so that it is possible to clamp different thicknesses of saw blade with different shank designs, e.g. the single-cam shank of universal saw blades or the ½″ universal shank of sabre saw blades, with a sufficient degree of snugness and reliability.

According to one advantageous embodiment form of the present invention, at least one of the support surfaces of the clamping parts has a recess whose contour replicates the contour of a clamping shank of at least one of the saw blades to be clamped. This structural measure also allows particular jigsaw blades with a single-cam shank to be secured in the clamping device in a form-locked manner.

According to one advantageous embodiment form of the present invention, a positioning pin protrudes from one of the support surfaces of the clamping parts; this pin can be retracted behind the support surface counter to a spring force and is designed to be inserted in a form-locked manner into a positioning hole provided in a clamping shank of at least one of the saw blades to be clamped. This structural measure allows the clamping device to also hold universal saw blades with a ½″ universal shank in a form-locked manner. The spring-elastic embodiment of the positioning pin means that this positioning pin does not interfere with the clamping of a jigsaw blade with a single-cam shank or the clamping of other saw blades.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The clamping devices described below for an electric motor-driven hand-guided power reciprocating saw are used to clamp saw blades11that not only have different thicknesses, but also have different designs of their clamping shank111. Examples of such saw blades11are shown in a perspective top view inFIG. 1, with their respective rows113of saw teeth oriented away from the back112of the saw blade not shown in order to simplify the drawing. The two saw blades11at the top inFIG. 1are so-called universal saw blades with a ½″ universal shank that has a positioning hole114, and the two lower saw blades11are so-called jigsaw blades with a single-cam shank. The clamping devices are attached to the lifting rod of the electric motor-driven hand-guided power reciprocating saw as described, for example, in WO 02/22297.

Basically, each clamping device has two clamping parts12,13that can be pressed against each other in a nonpositive, frictional manner, each of which has a support surface for the clamping shank111of a saw blade11and at least one of the clamping parts can be slid in relation to the other in order to clamp and release the clamping shank111that is inserted between the clamping parts12,13and rests against the support surfaces. The sliding movement of the at least one clamping part12,13is derived from a sliding or rotating movement of an independent actuating element14that is moved by hand.

In the exemplary embodiment of the clamping device according toFIGS. 2 through 4, the one clamping part12is embodied in the form of a tool clamp15and the other clamping part13is embodied in the form of a slidable plate-shaped counterpart holder16that functions as a press part. The tool clamp15can be screwed to the lifter rod of the hand-guided power reciprocating saw and the counterpart holder16is guided in the tool clamp15so that it can move in relation to it. To this end, the tool clamp15has a base plate17with a flat support surface171for the clamping shank111of a saw blade11and two side walls18integral to the base plate17and protruding up from it, which are integrally connected at the two ends of the base plate17by means of cross pieces33and34. The cross piece33is provided with a slot-like opening35to allow the clamping shank111of a saw blade11to pass through. The strut34is integrally connected to a fastening tang36with a fastening hole37. The tool clamp15is screwed to the lifter rod of the hand-guided power reciprocating saw by means of the fastening hole37.

The side walls18are the shape of a segment of the outer circumference of a hollow cylinder while the base plate17is flat. Each side wall18has two parallel guide slots19let into it, which are spaced apart from each other and extend at right angles to the base plate17. The guide slots19in the side walls18are situated diametrically opposite from each other. On its side oriented toward the base plate17, the counterpart holder16has a support surface163for the clamping shank111and on each of its narrow longitudinal sides161oriented away from each other, has two protruding guide pins20that pass through the guide slots19and can slide in them in the longitudinal direction of the guide slots19. A hollow, cylindrical sliding sleeve21is slid onto the tool clamp15. The ends of the sliding sleeve21are each closed by an end flange211, which has a recess22that axially guides the sliding sleeve21against the side walls18. The circumference or sleeve wall of the sliding sleeve21is provided with two diametrically opposed pairs of guide slots23.

In each pair of guide slots23, the guide slots23extend parallel to each other and at the same angle of inclination to the sleeve axis; the parallel spacing of the guide slots23corresponds to the spacing of the guide slots19in the side walls18. The ends of the guide pins20passing through the guide slots19in the side walls18protrude into these guide slots23. A rotating sleeve24that constitutes the actuating element14is placed onto the sliding sleeve21; the sliding sleeve21and rotating sleeve24are coupled to each other by means of a trapezoidal thread32. The above-described assembly of the clamping device shown in the exploded view inFIG. 1is held together by a spring washer25and a retaining washer26.

If the rotating sleeve24is turned, then the sliding sleeve21moves in the direction of the fastening tang36, as a result of which the guide pins20on the counterpart holder16are lifted by means of the inclined guide slots23in the guide slots19of the side walls18so that a gap opens-up between the counterpart holder16and the base plate17. The clamping shank111of a desired saw blade11is then inserted into the open clamping device; the insertion is facilitated by a guide plate27that is fastened to the tool clamp15between the counterpart holder16and the base plate17. In order to lock the clamping device, the rotating sleeve24must be turned back again, which causes the sliding sleeve21to slide in the opposite direction and by means of the inclined guide slots23, slides the guide pins20downward in the guide slots19of the side walls18. The counterpart holder16is pressed with its support surface163against the saw blade shank111resting on the support surface171of the base plate17. The pressing force is reliably maintained by the static friction in the trapezoidal thread32.

As is particularly clear fromFIG. 3, the base plate17is provided with a recess28that constitutes a cavity in the support surface171, which is adapted to the contour of a clamping shank111embodied in the form of a single-cam shank. The single-cam shank is accommodated in a form-locked manner in this recess28and cannot be pulled out of the clamping device even when powerful axial forces are exerted on the saw blade11.

In order to axially immobilize a saw blade11equipped with a ½″ universal shank, a positioning pin29is provided, which can engage in a form-locked manner in the positioning hole114provided in the clamping shank111. This positioning pin29passes through a guide hole30extending through the support surface163of the counterpart holder16and is subjected to a spring force acting in the direction of the base plate17, which causes it to protrude beyond the support surface163of the counterpart holder16. The spring force is generated by a leaf spring31, which is fastened to the back side162of the counterpart holder16oriented away from the support surface163and presses against the end of the positioning pin29oriented away from the base plate17. If a universal saw blade is accommodated in the clamping device, then the action of the leaf spring31causes the positioning pin29to travel through the positioning hole114in the ½″ universal shank and presses it in a spring-elastic fashion against the base plate17. If the single-cam shank of a saw blade11is in the clamping device, then the leaf spring31presses the positioning pin29against the single-cam shank.

In the clamping device shown inFIGS. 5 through 8for the saw blades11shown inFIG. 1, the stationary clamping part12is once again embodied in the form of a tool clamp40and the clamping part13that can move in relation to it is once again embodied in the form of a counterpart holder41that is held in the tool clamp40so that it can move in relation to it, which functions as a press part. The tool clamp40is press-fitted and hard soldered or laser welded to the lifter rod of the hand-guided power reciprocating saw. The tool clamp40is comprised of a base body42and a cover43, which covers the base body42and is connected to it in detent fashion by means of detent projections44and detent recesses45.

At the bottom of the base body42, a support surface421is provided for the clamping shank111of a saw blade11. The rectangular counterpart holder41provided with the other support surface411for the clamping shank111is guided in a movable fashion on two locating pins47, which are press-fitted into a matrix49and protrude into two through openings48spaced apart from each other in the counterpart holder41. A compression spring is slid onto each locating pin47. The two compression springs50are supported at one end against the counterpart holder41and at the other end against the matrix49and in the unstressed state, place the counterpart holder41at a definite distance from the matrix49.

The matrix49, which acts as a coupling element between the movable clamping part13and the actuating part14, is guided in an axially movable fashion on four parallel guide pins51anchored in the base body42, which are inserted into slide bores491in the matrix49. A compression spring52is slid onto each guide pin51. The four compression springs52rest against the base body42at one end and rest against the matrix49at the other and place the matrix49against the underside of the cover43.

The actuating element14for closing and opening the clamping device acts on the counterpart holder41by means of the matrix49and, by increasing the clamping force of the compression springs52, presses it with its support surface441against the support surface421of the base body42or against a clamping shank111of a saw blade11lying between the support surfaces411,421. The actuating element14has a slider54, which is attached to a grip part53and cooperates with a ramp55provided in the top side of the matrix49oriented toward the cover43. The ramp55rises from one end of the matrix49to the other (from left to right inFIGS. 5 and 8) so that when the slider54is slid along the ramp55from left to right inFIGS. 5 and 8, the slider54supported on the underside of the cover43shifts the matrix49downward, placing stress on the compression springs52on the guide pins51. The grip part53has a knob531and a shaft532integrally connected to it, which protrudes through a slot56in the cover43aligned with the ramp55and is anchored in the slider54.

If the clamping shank111of a saw blade11is placed against the support surface421of the base body42and the knob531is moved manually in the slot56of the cover43from left to right inFIGS. 5 and 8, then the matrix49is slid toward the base body42on the guide pins51, counter to the force of the compression springs52and, by means the compression springs50on the locating pins47, presses the counterpart holder41with its support surface411against the clamping shank111so that the latter is clamped tight between the counterpart holder41and the base body42in a nonpositive, frictionally engaging way by the stressed compression springs50. If the knob531is moved back again, then the stressed compression springs52push the matrix49back up again until it rests against the underside of the cover43. The compression springs50lift the counterpart holder41away from the clamping shank111.

As is clear fromFIG. 6, the support surface411of the counterpart holder41is provided with a recess57that constitutes a cavity that accommodates the single-cam shank of a jigsaw blade in a form-locked manner. In order to clamp a universal saw blade, a positioning pin58is once again provided, which can protrude through the positioning hole114in the ½″ universal shank in a form-locked manner. The positioning pin58is supported on a holding piece59by means of a compression spring, not shown here, that is clipped to the base body42. The positioning pin58is guided in a guide hole46extending through the support surface421in the base body42and protrudes slightly beyond the support surface421so that it can protrude into the positioning hole114of the ½″ universal shank when a universal saw blade is being clamped. If a jigsaw blade with a single-cam shank is inserted into the clamping device, then the single-cam shank pushes the positioning pin58back behind the support surface421.

In the clamping device shown inFIGS. 9 through 13, the one clamping part12is once again embodied in the form of a tool clamp60, which is press-fitted and hard soldered or laser welded to the lifter rod of the hand-guided power reciprocating saw at its left end inFIG. 9and the clamping part13that can move in relation to it is provided in the form of several clamping pins61, three clamping pins61in the exemplary embodiment, that function as a press part. The tool clamp60, which is approximately U-shaped in cross section, has a base plate62with a support surface621onto which the clamping shank111of a saw blade11is to be placed and two side walls63that are integral to the base plate62and protrude up from it at right angles spaced apart from each other. The support surface621of the base plate62is provided with a recess75for the form-locked accommodation of a single-cam shank of a jigsaw blade. Each side wall63has a number of guide slots64integrated into it that corresponds to the number of clamping pins61, three in this case. The guide slots64extend parallel to one another and at the same angle of inclination to the longitudinal axis of the tool clamp60. The guide slots64in the two side walls63are aligned with one another. The tool clamp60has a sliding sleeve65with a box-shaped profile slid onto it, which is guided so that it can move axially on the tool clamp60and represents a coupling element between the mobile clamping part13and the actuating element14.

The sleeve wall651of the sliding sleeve65covering the lower side wall63inFIG. 9has three parallel transverse grooves66that extend at right angles to the longitudinal axis of the sliding sleeve65and the parallel spacing of these grooves corresponds to the spacing between the guide slots64in the side walls63of the tool clamp60. The sleeve wall652of the sliding sleeve65covering the upper side wall63inFIG. 9has transverse slots67that are situated and embodied in the same way as the transverse grooves66in the lower sleeve wall651. The transverse grooves66and the transverse slots67are flush with one another. The groove width of the transverse grooves66, the slot width of the transverse slots67, and the slot width of the guide slots64are selected to be slightly greater than the outer diameter of the clamping pins61so that the latter can slide in the guide slots64, the transverse slots67, and the transverse grooves66.

After the sliding sleeve65is slid onto the tool clamp60, the clamping pins61are guided through the transverse slots67in the upper sleeve wall652of the sliding sleeve65and through congruent underlying regions of the inclined guide slots64in the upper side wall63and in the lower side wall of the tool clamp60and are inserted into the transverse grooves66in the lower sleeve wall651of the sliding sleeve65(FIG. 12). The actuating element14is embodied with a U-shaped inner profile so that its legs68can embrace the sleeve walls653of the sliding sleeve65that extend at right angles to the sleeve walls651and652containing the transverse slots67and transverse grooves66. The cross piece69that joins the legs68of the actuating member14has grooves70let into it that are the same as the ones in the lower sleeve wall651of the sliding sleeve65(FIG. 10).

When the actuating element14is placed onto the sliding sleeve65, the ends of the clamping pins61protruding from the sliding sleeve65are accommodated in the transverse grooves70and detent projections71(FIG. 10) on the legs68engage in detent fashion with detent holes72(FIG. 12) provided in the sleeve walls653. A compression spring73that maintains the clamping force of the clamping device is inserted into a groove74extending in the sliding direction of the sliding sleeve65in the tool clamp60and rests against the tool clamp60at one end and rests against the sliding sleeve65at the other. The above-described design of the clamping device is shown inFIG. 11.

If the actuating element14is then slid in the direction of the arrow76inFIG. 11on the tool clamp60, then the clamping pins61are slid in the transverse grooves66and70, in the transverse slots67, and in the inclined guide slots64. The inclination of the guide slots64in the tool clamp60causes their distance from the base plate62to increase. This produces an open space between the base plate62and the clamping pins61into which the clamping shank111of a saw blade11can be inserted. If the actuating element14is released after the insertion of the saw blade11, then the compression spring73that has been stressed by the sliding of the actuating element14in the direction of the arrow76pushes the sliding sleeve65back again, as a result of which the clamping pins61at the other end of the guide slots64are slid back and thus press against the clamping shank111resting on the support surface621of the base plate62.

In the clamping device for a saw blade11shown inFIGS. 14 through 17, the clamping parts12,13are embodied in the form of two plate-shaped clamping jaws80,81that can be moved toward and away from each other, whose large surfaces oriented toward each other constitute the support surfaces801and811for the clamping shank111of a saw blade11and each have a recess82that is adapted to the contour of a single-cam shank in order to permit them to accommodate a single-cam shank in a form-locked manner. The sum of the depths of the two recesses82is less than the narrowest saw blade thickness of the saw blades11they are intended to clamp. Each clamping jaw80,81is provided with two bores83spaced apart from each other and parallel to the support surface801to811and a guide bolt84is guided through each of them.

The guide bolts84are long enough that their ends protrude beyond the narrow sides802and812extending at right angles to the support surfaces801,811and constitute four guide pins841(FIGS. 16 and 17) there for the clamping jaws80,81. In order to produce a sliding motion of the clamping jaws80,81, these guide pins841protrude through guide slots85in a holder86at one end and protrude through guide slots87in a counterpart holder88at the other. Two pairs of respective guide slots85and87are spaced the same distance apart from each other as the bores83in the clamping jaws80and extend parallel at an angle of inclination to the longitudinal axis of the holder86and counterpart holder88.

The guide slots85and87for the one clamping jaw80and the guide slots85and87for the other clamping jaw81in the holder86and counterpart holder88are oriented in relation to one another to produce a wedge-shaped or herringbone-like pattern of the guide slots85and87in the holder86and counterpart holder88. The holder86is press-fitted and hard soldered or laser welded to the lifter rod of the hand-guided power reciprocating saw and the counterpart holder88is attached to the holder86by means of a rivet89. Two grooves90extending in the axial direction of the holder86are provided on the opposite sides of the holder86and are each intended to accommodate a clamping spring91embodied in the form of a compression spring.

The actuating element14for moving the clamping jaws80,81is embodied in the form of a two-part sliding grip92with two essentially U-shaped grip parts921,922that can engage with each other in detent fashion. The bridge piece bottom of each grip part921,922has two transverse grooves93spaced apart from each other incorporated into it, which extend at right angles to the movement direction of the actuating element14or to the longitudinal axis of the holder86. The distance between the transverse grooves93corresponds to the distance between the guide slots85and87in the holder86and counterpart holder88. The two grip parts921,922are slid from below and above onto the preassembled unit comprised of the holder86and counterpart holder88, with clamping jaws80,81lying between them, supported on the guide bolts84(FIG. 16) so that the guide pins841at the upper and lower ends of the guide bolts84protrude into the transverse grooves93in the two grip parts921,922. The two grip parts921,922engage each other in detent fashion by means of detent projections94protruding from the lower grip part921and detent recesses95incorporated into the upper grip part922.

The end-mounted clamping device is shown inFIG. 15, whileFIG. 16shows the clamping device with the sliding grip92removed.FIGS. 16 and 17show one of the clamping springs91contained in the grooves90of the holder86in the installed position in which it rests against the holder86and the upper grip part922of the sliding grip92. By means of the sliding grip92, the clamping springs91embodied in the form of compression springs press the clamping jaws80,81into the end position depicted inFIG. 16in which the two clamping jaws80,81are pressed against each other.FIG. 17shows the partially assembled clamping device in which not only has the counterpart holder88been removed from the holder86, but also the clamping jaw81has been removed from the guide bolts84.

If the sliding grip92is moved in the direction of the arrow96inFIG. 15, then the guide pins841protruding out from the clamping jaws80,81and into the transverse grooves93in the grip parts921and922are moved in the guide slots85and87of the holder86and counterpart holder88toward the other end of the guide slots85and87. This moves the clamping jaws80,81away from each other, producing an opening slot through which the clamping shank111of a saw blade11can be inserted between the clamping jaws80,81. If this is a jigsaw blade11with a single-cam shank, then the latter is inserted into the congruent recesses82on the support surfaces801and802of the clamping jaws80,81.

If the sliding grip92is released, then the clamping springs91slide the sliding grip92back into the end position shown inFIGS. 15 through 17until the clamping jaws80,81press with their support surfaces801and802against the clamping shank111, fixing it between themselves in a form-locked manner; in the case of the single-cam shank, an additional form-locked connection is produced between the clamping shank111and the clamping jaws80,81.

While the invention has been illustrated and described as embodied in a clamping device for toolless clamping of a saw blade, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will reveal fully revela the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention.