Abstract:
A power scroll saw with a housing and a saw blade capable of being driven in a reciprocating manner, and with tongs-like guides that guide the saw blade in a laterally-supported manner is capable of being used in a variety of work applications due to the fact that the guide means are capable of being switched by hand selectively into a position having lateral clearance from the saw blade and into a position in which they laterally support the saw blade.

Description:
BACKGROUND INFORMATION 
   The present invention is relates to a power scroll saw  1 . 
   A power scroll saw with saw blade guidance system is made known in WO 02/22297, which guides the flat sides of the saw blade between two lateral clamping jaws. According to the invention, the clamping jaws are controlled using a servomotor. 
   SUMMARY OF THE INVENTION 
   The present invention has the advantage that the guide system is selectively activated and/or deactivated. 
   In addition, the clamping means—which automatically adjust to the position of the saw blade—have the advantage that the two flat sides of the saw blade are guided with matching, minimal bearing force, and undesirably high friction forces between the guide means and the saw blade are prevented. 
   Due to the fact that the guide means are elastically situated in such a manner that they attempt to move into the activated position bearing on the saw blade, an abrupt activation of the guide means is selectively possible in the deactivated position as soon as the working conditions require this. Due to the fact that a push-button is provided that, when it is actuated, the clamping means move into their activated position of supporting the saw blade, activation of the guide means is particularly convenient. 
   Due to the fact that an actuation means for deactivating the guide means is located on the saw blade clamping mechanism, the guide means are automatically deactivated when the saw blade is replaced or removed. 
   Due to the fact that the chuck lever serving as actuating lever for moving the guide tongs into the “open” position for removing or clamping the saw blade is provided with wedge means, in particular a ramp, with which the driving pin, together with the sliding members, is capable of being displaced downward, a reliable, robust actuating mechanism for deactivating the guide means is created. 
   Due to the fact that two sliding members for closing and/or opening the tongs-like guide means are supported such that they are relatively parallel to each other and are displaceable along a straight line, whereby one sliding member forcibly carries along the other in a direction of travel and is capable of being moved back in the opposite direction of travel independently of the sliding member that was carried along, simple and robust machine elements are used that ensure a high level of reliability of the power scroll saw. 
   Due to the fact that spring-preloaded sliding members, with slide guide slots, overlap lobes of the guide means, in particular guide jaws, a simple and reliable actuating mechanism is created for closing and/or opening the guide tongs. Due to the fact that the sliding members are capable of being displaced, coupled together, in such a manner that a certain amount of play relative to each other exists along their displacement path, a self-orienting positioning of the clamping jaws relative to the saw blade is possible, with which deviations in the saw blade position from the ideal position are tolerated. This is achieved by situating a driving means between the first and second sliding member, whereby, in the “closed” position of the guide tongs, an axial clearance of approximately 0.5 mm exists between the driving means and the second sliding member in the direction of displacement toward the “open” position. 
   Due to the fact that the slide guide slots of the sliding members are situated at an angle relative to vertical compared to the glide bolt of the tong jaws in the self-locking range, in particular 5 to 6 degrees of inclination from vertical, the clamping jaws are capable of being closed with a high amount of holding force, so that the clamping tongs cannot be opened by external forces and/or if the saw blade bears against it with a high amount of force. 
   Due to the fact that a finger protection mechanism is mounted on the housing, the risk of injury when working with the power scroll saw is markedly reduced, and the U-shaped configuration of the finger protection mechanism allows the saw blade to be easily discernable and guidable in a controlled manner. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a schematic depiction of a first exemplary embodiment of the invention, 
       FIG. 2  shows a side view of a second exemplary embodiment of the invention, 
       FIG. 3  shows the assembly of the guide means, 
       FIG. 4  shows a cross section with inside view, from behind, of the guide means, 
       FIG. 5  shows the guide means in the closed position, and 
       FIG. 6  shows the guide means in the open position. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a schematically depicted, handheld reciprocating saw  10  at an angle from above, which accommodates a not-shown electric motor with a gearset in a housing  12  for the reciprocating driving of a reciprocating rod  16 . A saw blade  18  is detachably but captively coupled to reciprocating rod  16  with its clamping end, the saw blade passing downward—as shown in the figure—through a base plate  14  of reciprocating saw  10 . 
   Saw blade  18  bears—with its saw blade back  23 , which is diametrically opposed to toothed side  17 —against a support roller  22  that, oscillating back in forth in feed direction  19 , can impart a reciprocating motion to saw blade  18 , being energizable as necessary. 
   In addition, guide means configured as guide tongs  26  extend in front of toothed side  17  of saw blade  18  above base plate  14 , the guide means being capable of supporting saw blade  18  on its flat sides in a diametrically opposed manner. 
   Using spring tension, a distance between guide jaws  24 ,  25  of guide tongs  26  is capable of being adapted to the particular thickness of clamped saw blade  18 . Guide jaws  24 ,  25  are capable of being pivoted around a rotation point  30  ( FIG. 4 ) between the dosed position and the open position. In the closed position, the outermost ends of guide jaws  24 ,  25  bear laterally against the flat sides of the saw blade. 
   The lower end of reciprocating rod  16  is equipped with a clamping device  20  in which the clamping end of saw blade  18  is capable of being clamped in a captive manner and is capable of being detached by actuating a chuck lever  21 . When chuck lever  21  is actuated, guide tongs  26  are switched to the open position, whereby this position is capable of being selectively changed to the closed position—in which guide jaws  24 ,  25  bear against saw blade  18 —by actuating a side button  52 . 
     FIG. 2  shows a further exemplary embodiment of a reciprocating saw  100 , which conforms, in principle, with that according to  FIG. 1 , the guide tongs  260  of which, however, extend laterally relative to support roller  220  and, as shown in the figure, are angled to the right, so that it extends behind reciprocating rod  160  and into the interior of housing  120 . As shown in the figure, a U-shaped protective frame  27  extends parallel with said reciprocating rod from top to bottom, attached to housing  120 , the protective frame serving as finger protection against accidental contact with saw blade  180  and protecting the operator of reciprocating saw  100  from injury. 
   Housing  120  is capable of being coupled with a base plate  140  in a pivoting manner, and saw blade  180  is capable of being supported laterally by guide jaws  240 ,  250 . A chuck lever  210  is situated above the region where reciprocating rod  160  exits housing  120 , which is capable of being pivoted to the left, as viewed in the figure-transversely across the front region of housing  120 -to remove saw blade  180 . A push-button  520  is situated below operating lever  210 ; when it is actuated, guide tongs  260  close abruptly to laterally support saw blade  180 . 
   A pivoted lever  15  for adjusting the reciprocating stroke of pendulum roller  220  is provided behind push-button  520 , as viewed in the figure. 
   The functional elements that are explained in  FIG. 1  and are equally-acting and identically configured in  FIG. 2  have the same reference numerals as in  FIG. 1 , but with a zero added at the end. 
     FIG. 3  shows the assembly of guide tongs  260  in their position relative to reciprocating rod  160  and pendulum roller  220 . It is clear that guide jaws  240 ,  250  extend—angled horizontally—from toothed side  170  of saw blade  180  rearward toward pendulum roller  220  and, angled once more, vertically upward, are coupled at rotation point  30  so as to be secured to the housing. Mounted on each guide jaw  240 ,  250  is a glide bolt  35 ,  36 —which extends toward the front out of the viewing plane—each of which passes through a slide guide slot  38 ,  39  of two sliding members  45 ,  46 , which are displaceable upward and/or guided to the bottom left. Slide guide slots  38 ,  39  extend with an approximately 5-degree inclination from the vertical and/or toward the axis of reciprocating rod  160 , so that, when sliding members  45 ,  46  are slid upward—as viewed in the figure—guide bolts  35 ,  36  are displaced outwardly and, with this displacement, guide jaws  240 ,  250  pivot outwardly and open. If sliding members  45 ,  46  are slid dowward, slid guide slots  38 ,  39  carry guide bolts  35 ,  36  along with them in such a manner that said guide bolts move toward each other, so that guide tongs  260  close and the lower ends of guide jaws  240 ,  250  bear laterally against saw blade  180 . Sliding members  45 ,  46  are elastically preloaded by compression springs  42 ,  43  ( FIGS. 5 ,  6 ) and attempt to press sliding members  45 ,  46  axially upward. 
   Mounted on the axial extension of push-button  520  is a sliding element that extends—on a lobe  56  in the upper region of sliding member  45 —toward push-button  520 . In  FIG. 3 , push-button  520  is slid toward the left—as viewed in the figure—whereby it bears against a compression spring  53  and has displaced its sliding element  54  in the “released” position relative to lobe  56 . As a result, sliding member  45  can be abruptly displaced into its upwardly oriented position, whereby it releases the second sliding member  46  that is pressed downward with its driving pin  48 . When actuating lever  210  is pivoted toward the left—as viewed in the figure—an arm on which a ramp  50  is mounted, the arm being rigidly coupled with said actuating lever—is rotated approximately centrally around the axis of reciprocating rod  160 , whereby driving pin  48  and the two sliding members  45 ,  46  are pressed downward. Sliding member  54  reaches its locked position relative to lobe  56  as soon as said lobe is slid downward together with sliding member  45 . Lobe  56 —which previously was holding sliding member  54  in its closed position—thereby releases sliding member  54  again, so that push-button  520 —preloaded by compression spring  53 —is capable of being displaced into its open position again, in which lobe  56  is locked in the vertical direction of motion by sliding member  54 . 
     FIG. 4  shows a cross section of power scroll saw  100  in the region of guide tongs  260  as viewed from the rear, whereby rotation point  30  of guide jaws  240 ,  250  is particularly clearly visible, and is formed by a stud. Sliding members  45 ,  46 —which are partially covered by guide jaws  240 ,  250 —are slid into their position vertically upward, so that guide tongs  260  are in the closed position. Ramp  50  has thereby released driving pin  48  end, with this, sliding member  45  shown an the left in the figure, which is followed by shorter sliding member  46 . Driving pin  48  is captively pressed into longer sliding member  45  in a bore (not shown in greater detail) transversely to its direction of displacement, whereby it partially penetrates, with its exposed end, a groove-like recess (not shown in greater detail) in the upper front side of shorter sliding member  46 . 
   Push-button  520  remains in its inwardly-pressed position as long as sliding member  45  remains in its vertically uppermost position. Glide bolts  35 ,  36 , the rear views of which are visible in guide jaws  240 ,  250 , are thereby pivoted toward each other, so that guide tongs  260  are in the closed position. 
     FIG. 5  shows guide tongs  260  in their closed position, in which sliding members  45 ,  46  are upwardly displaced and lobe  56  locks sliding member  54  in place, so that push-button  520  remains pressed axially inwardly. As long as chuck lever  210  is pivoted to the left—as viewed in the figure—ramp  50  glides in a wedge-like manner toward driving pin  48 , so that, as described previously, sliding members  45 ,  46  are displaced downwardly—as viewed in the figure—and the clamping tongs are opened. 
     FIG. 6  shows guide tongs  260  according to  FIG. 5  in the open position, because sliding members  45 ,  46  are slid vertically downward against compression springs  42 ,  43 , thereby spreading apart guide bolts  35 ,  36  and, therefore, guide jaws  240 ,  250 . Lobe  56  has slid past sliding member  54  to the right—as viewed in the figure—and has released said sliding member from the preload force of compression spring  53 —so that push-button  520  can be displaced into the open position to the right, as viewed in the figure. In this position, sliding member  54  is positioned above lobe  56  and locks it and/or sliding member  45  in the upward direction of motion. Since sliding member  45  with its driving pin  48  at the top bears against adjacent sliding member  46 , this sliding member  46  must follow the motion of driving pin  48  downward, acted upon by ramp  50 . In the closed position according to  FIG. 4 , driving pin  48  has a vertical clearance of approximately 0.5 mm relative to sliding member  46 , so that driving pin  48  first must be pressed downward by this amount before sliding member  46  is acted upon and can follow the motion. As a result, in the closed position, adjustments can be made within a certain tolerance range relative to the center position of saw blade  180 . If saw blade  180 , as a result of a center position, is closer to guide jaw  240 , it will bear laterally against saw blade  180  first, displaced by sliding member  46  and/or by guide bolt  35 , so that adjacent guide claw  250 —adjusted by the free, upwardly movable, longer sliding member  45 —comes to rest at the side of saw blade  180  somewhat later. Due to the self-locking in slide guide slot  38 ,  39 , slide guide bolts  35 ,  36  are positioned in the locked position, and guide jaws  240 ,  250  cannot be moved outwardly, into the position in which guide tongs  260  are open. If, as a result of an inclined position of saw blade  180 , guide jaw  250  is the first to comes to rest on saw blade  180  due to the upward motion of sliding member  45  and the inward displacement of guide pin  36  in the guide slot, the left—as viewed in the figure—guide jaw  240  must cover a longer actuating path, which it realizes by left sliding member  46  being able to move toward driving pin  48  by the amount exceeding the amount of approximately 0.5 mm above its zero position, and thereby very securely come to rest on the lateral surface of saw blade  180 . A secure, uniform guidance of saw blade  180  is thereby ensured within the foreseeable tolerance range.