Abstract:
A machine tool, in particular a circular power saw, for machining a workpiece, has a covering ( 10 ) for guarding a user against machining residues of the workpiece that occur in operation and an adjustable residue guide ( 12, 14 ) for carrying away at least some of the machining residues through an outlet opening in a defined direction in accordance with the position of the residue guide ( 12, 14 ). The residue guide is adjustable in such a way that in one position of the residue guide ( 12, 14 ), at least some of the machining residues are carried onward inside the covering ( 10 ).

Description:
CROSS-REFERENCE 
     The invention described and claimed hereinbelow is also described in PCT/DE 03/00691, filed Mar. 3, 2003 and DE 102 24 837.0, filed Jun. 5, 2002. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119 (a)-(d). 
     BACKGROUND OF THE INVENTION 
     The invention is based on a machine tool. 
     In most known circular power saws, the user is protected against the chips, or sawdust, created during sawing by means of a covering in the form of a guard hood. The chips are carried to the outside through a lateral outlet opening, and the outlet opening usually has a standard stub to which a vacuum cleaner or dust bag can be attached. Often, however, for reasons of convenience, circular power saws of this kind are used without a vacuum cleaner or dust bag, and the sawdust created during sawing then passes unhindered out of the outlet opening. However, this impedes the operation of the circular power saw, since the emerging sawdust could strike the user directly on his body. 
     For carrying the chips away, it is therefore known to use a rotatable elbow, so that the direction in which the chips are carried away can be varied by rotating the elbow. The user can then rotate the elbow in such a way that he is not struck by the emerging chips. 
     SUMMARY OF THE INVENTION 
     The invention includes the general technical teaching, for carrying away machining residues in a machine tool, of providing an adjustable residue guide; in one position, the residue guide carries at least some of the machining residues onward inside the covering. 
     The term “machining residues” used within the context of the invention should be understood in a general sense and includes not only the chips, or sawdust, already mentioned at the outset but abrasion from grinding, for instance, or residues from additive substances. 
     In a variant of the invention, the residue guide has a pivot tube, which is pivotable about a pivot axis that preferably extends perpendicular to the longitudinal axis of the pivot tube. In one pivoted position of the pivot tube, the pivot tube preferably discharges inside the covering, while conversely in another pivoted position, the pivot tube discharges outside the covering. Depending on the pivoted position of the pivot tube, the machining residues are accordingly either carried to the outside by the pivot tube or carried onward inside the covering. 
     In another variant of the invention, conversely, the residue guide has a pivot tube which is rotatable about an axis of rotation. Preferably, the axis of rotation is at an angle here to the longitudinal axis of the pivot tube, and angles between 10° and 50° are advantageous. 
     For delivering the machining residues, a feed tube is preferably provided, which discharges into the pivot tube and preferably has the same diameter as the pivot tube. 
     The axis of rotation is preferably also angled relative to the longitudinal axis of the feed tube; the longitudinal axes of the feed tube on the one hand and the pivot tube on the other preferably form the same angle with the axis of rotation. An advantageous aspect of this is that the pivot tube, in one rotated position, extends precisely parallel to the feed tube, since the angles of inclination of the feed tube and the pivot tube cancel one another out. 
     Moreover, in this respect it is preferably provided that the axis of rotation intersect the longitudinal axes of the feed tube and of the pivot tube at a common intersecting point. This offers the advantage that in a rotated position the pivot tube does not extend merely parallel to the feed tube but is instead aligned with it. 
     Preferably, the outer contours of the feed tube and of the pivot tube are circular at the abutting point; the feed tube and the pivot tube preferably have the same outer diameter at the abutting point. This offers the advantage that upon rotation of the pivot tube, no discontinuities occur at the abutting point. 
     It is especially advantageous if the outer contour of the pivot tube and the outer contour of the feed tube at the abutting point between the pivot tube and the feed tube are each formed spherically with the same outer diameter, so that the abutting point is embodied spherically. Because of this spherical shape, the rotation function of the abutting point is made clear to the user. The outer diameter of the spherically connection pieces of the feed tube and of the pivot tube is preferably greater than the normal outer diameter of the feed tube and of the pivot tube, so that the spherical shape is visually emphasized. 
     In a further variant of the invention, the residue guide conversely has a preferably drum-shaped rotary slide, which is rotatable about a predetermined axis of rotation. As a function of its rotary position, the rotary slide carries the machining residues onward inside the covering or discharges them to the outside through an outlet opening. 
     In a preferred embodiment, the rotary slide has an integrated guide tube, which rotates with the rotary slide. The guide tube can then discharge the machining residues in different directions, as a function of the rotary position of the rotary slide. 
     To make manual rotation of the rotary slide easier, various operator control elements are provided, such as grip indentations, a knurled structure on the surface, or a lever. 
     In the preferred embodiment, the residue guide has a connection stub, to which a dust bag or a vacuum cleaner can be connected. The fixation of the dust bag or of the vacuum cleaner hose to the connection stub can be done by means of a clamp connection, for instance, by slipping a connection piece of the dust bag or of the vacuum cleaner hose on in clamping fashion. 
     Preferably, the connection stub therefore has a conical shape, to improve the clamping action. In a variant, the connection stub has an outer shape which tapers conically toward the distal end of the connection stub, so that the corresponding connection piece of the dust bag or of the vacuum cleaner hose will clamp to an increasing extent on being slipped on. In another variant, conversely, the connection stub has an internal shape which widens conically toward the distal end of the connection stub, so that the connection piece of the dust bag or of the vacuum cleaner hose clamps to an increasing extent on being inserted inside. 
     Preferably, the residue guide is shaped and adjustable in such a way that the residue guide, in one position, has a common outer contour with the covering. 
     In all the embodiments described above, the adjustment of the residue guide can be done continuously or in stages. 
     In the event of adjustment of the residue guide in stages, detent means may be provided, so that the residue guide snaps into place in one or more detent positions. Preferably, such detent means make at least two different detent positions possible, and the residue guide carries the machining residues onward inside the covering in one detent position, while in the other detent position the machining residues are carried away to the outside. In the preferred embodiment, however, a plurality of detent positions are provided, so that the user can adjust the residue guide in such a way that the machining residues produced in operation will be carried away in the desired direction. 
     A spring element may also be provided, which puts the residue guide into a position in which the machining residues are carried away inside the covering. After a dust bag or a vacuum cleaner hose has been removed, the spring element then automatically assures that the machining residues produced in operation will be carried onward inside the covering, so as not to impede operation. 
     Further advantages will become apparent from the ensuing description of the drawings. In the drawings, one exemplary embodiment of the invention is shown. The drawings, description and claims include numerous characteristics in combination. One skilled in the art will expediently consider the characteristics individually as well and put them together to make useful further combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 , a circular power saw of the invention, with a pivot tube folded inward for carrying away chips, or sawdust; 
         FIG. 1   a , a perspective view of a detail of the pivot tube of  FIG. 1  in the folded-together state; 
         FIG. 1   b , a perspective view of a detail of the pivot tube of  FIG. 1  in the folded-out state; 
         FIG. 2   a , an alternative exemplary embodiment of a circular power saw of the invention, with a drumlike rotary slide for carrying away sawdust produced in sawing, the rotary slide being closed; 
         FIG. 2   b , the circular power saw of  FIG. 2   a , with a rotary slide open at the side; 
         FIG. 2   c , the circular power saw of  FIG. 2   a , with a rotary slide open at the top; 
         FIG. 3   a , an alternative exemplary embodiment of a circular power saw of the invention, with a pivot tube in the closed state; 
         FIG. 3   b , the circular power saw of  FIG. 3   a , with a pivot tube open at the back; 
         FIG. 3   c , a side view of the circular power saw of  FIG. 3   a;    
         FIG. 3   d , the circular power saw of  FIG. 3   a , with the pivot tube folded obliquely outward; and 
         FIGS. 4   a - 4   d , an alternative exemplary embodiment of a circular power saw of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The circular power saw shown in perspective in  FIGS. 1 through 1   b  is largely embodied conventionally and has an electric motor which drives a saw blade  8 . 
     The saw blade  8  is covered here by a covering  10  in the form of a guard hood, for protecting the user against sawdust produced in sawing operation and to prevent injury from the saw blade  8 . 
     A flap  12  with an integrated pivot tube  14  is disposed on the side of the covering  10 ; the flap  12  can be pivoted about a pivot axis  13  which extends parallel to the plane of the saw blade  8 . 
     In the state of the circular power saw shown in  FIGS. 1   a  and  1   b , the flap  12  is folded inward, so that the sawdust created during operation is guided to the rear (to the left in the drawing) inside the covering  10 , where it is carried away either through a lateral outlet opening  15  located on the lower end of the covering  10  or directly downward out of the covering  10 . 
     In contrast to this, in the state shown in  FIG. 1   b , the flap  12  is folded out, so that the discharge opening of the pivot tube  14  is uncovered. The sawdust produced in operation of the circular power saw is therefore carried away laterally by the pivot tube  14 . 
     For receiving the sawdust emerging from the pivot tube  14 , a dust bag or a vacuum cleaner hose can be connected to the pivot tube  14 . The pivot tube  14 , in the region of its outer discharge opening, therefore forms a connection stub  44  for a dust bag or a vacuum cleaner hose; the connection stub  44  is shaped conically, so that by means of a clamping action, a firm seat of the dust bag or of the vacuum cleaner hose on the connection stub  44  will be attained. The inside diameter of the pivot tube  14  accordingly tapers inward conically, by the same conical angle at which the connection stubs of corresponding conventional dust bags and vacuum cleaner hoses taper, as a result of which a good clamping fit is attained. 
     The flap mechanism moreover has a spring element  46 , which automatically fold the flap  12  inward along with the pivot tube  14  whenever no dust bag or vacuum cleaner hose is connected. 
     However, it is alternatively also possible for the flap mechanism to have detent elements  45 , which lock the flap  12  in either the folded-in or the folded-out state. This advantageously makes it possible, even without a dust bag or a vacuum cleaner hose, to operate the circulate power saw with the pivot tube  14  folded out, so that the sawdust produced in operation can be carried away laterally. 
     It should also be noted that the flap  12  completely seals off the covering  10  laterally in the closed state, so that no sawdust can escape laterally. The contours of the covering  10  and flap  12  are moreover adapted to one another in such a way that only minimal gaps occur between the covering  10  and the flap  12 , so that in the folded-out state, the sawdust escapes solely through the pivot tube  14 , while secondary streams are conversely avoided. 
     The exemplary embodiment of a circular power saw of the invention shown in  FIGS. 2   a  through  2   c  largely matches the exemplary embodiment described above, so that in part the above description can be referred to. Here only a fragmentary perspective view is shown, representing the mechanism of the invention. 
     This circular power saw likewise has a saw blade standing upright, which is driven in a conventional way by an electric motor and is enclosed by a covering  10 ′, to protect the user against sawdust produced in operation and to prevent injury from the saw blade. 
     During operation of the circular power saw, the sawdust is blown upward inside the covering  10  in a front region  16 , where it reaches a feed tube  18 , which widens conically in the flow direction and finally changes over into a cylindrical region. The feed tube  18  is open at the bottom here and discharges into a drumlike rotary slide  20 , which is rotatable about an axis of rotation  21  and which either carries the sawdust outward or onward into a rear region  22  of the covering  10 ′, depending on its rotary position. The cross-sectional shape of the feed tube  18  should be optimized for the flow and need not necessarily have a conical shape. 
     In the position of the rotary slide  20  shown in  FIG. 2   a , the sawdust is not carried away to the outside by the rotary slide  20  but instead is carried onward inside the covering  10 ′ into its rear region  22 , where it finally escapes through an outlet opening on the underside of the covering  10 ′. To that end, the rotary slide  20  has an integrated guide tube  24 , which rotates with the rotary slide  20  and carries the sawdust away in a defined direction, as a function of the rotary position of the rotary slide  20 . In the position of the rotary slide  20  shown in  FIG. 2   a , the guide tube  24  directs the sawdust, arriving from the feed tube  18 , obliquely downward into the covering  10 ′, where it finally escapes through the outlet opening disposed on the underside of the covering  10 ′. The covering  10 ′ is therefore shaped such that the discharge opening of the guide tube  24 , in the position of the rotary slide  20  as shown in  FIG. 2   a , is located entirely inside the covering  10 ′. The covering  10 ′ therefore extends along the underside of the rotary slide  20  in the lateral direction over an angular range that is larger than the opening angle of the discharge opening of the guide tube  24 , so that the discharge opening can be surrounded completely. 
     In contrast to this, in the position of the rotary slide  20  shown in  FIG. 2   b , the sawdust is carried away to the outside laterally, since in this position the guide tube  24  is rotated to the side, so that the discharge opening of the guide tube  24  is uncovered. 
     Finally, in the position of the rotary slide  20  shown in  FIG. 2   c , the sawdust is carried away obliquely upward by the guide tube  24 . 
     Accordingly, the user can adjust the rotary slide  20  in such a way that the emerging sawdust is as slight a hindrance as possible. To that end, a handle  26  which makes manual rotation of the rotary slide  20  easier is integrally formed onto the outside of the rotary slide  20 . The same purpose is served by grip indentations  28  and a knurled structure  30 , which are integrally formed onto the rotary slide  20 . 
     The rotatable support of the drumlike rotary slide  20  is accomplished at guide diameters that are received in the covering  10 ′ by suitably integrally formed bearing shells. 
     Detent elements are also provided, which make it possible to lock the rotary slide  20  in various rotary positions. 
     Moreover, the guide tube  24  integrated with the rotary slide  20  forms a connection stub  44 , to which a dust bag or a vacuum cleaner hose can be attached. The guide tube  24  therefore widens conically toward its discharge opening, in order to attain a clamping fit of the dust bag or vacuum cleaner hose on the connection stub  44 . 
     The exemplary embodiment of a circular power saw of the invention shown in  FIGS. 3   a  through  3   c  likewise largely agrees with the exemplary embodiments described above, so that the above description can be referred to for further information. In this exemplary embodiment as well, only a fragmentary perspective view is shown, illustrating the mechanism of the invention. 
     The sawdust that occurs in operation of the circular power saw is initially blown upward here in a front region  16 ′ of a covering  10 ″, where it reaches a largely cylindrical feed tube  18 ′, which discharges into a pivot tube  32  and has a substantially horizontally extending longitudinal axis  34 . 
     The pivot tube  32  here is pivotable about a predetermined axis of rotation  36 ; the pivot tube  32  has a longitudinal axis  38  which forms the same angle with the axis of rotation  36  as does the longitudinal axis  34  of the feed tube  18 ′. This geometric arrangement makes it possible for the pivot tube  32 , in the rotary position shown in  FIG. 3   b , to be aligned with the feed tube  18 ′, so that the sawdust emerges from the pivot tube  32  without being detoured. 
     In the rotary position of the pivot tube  32  shown in  FIG. 3   d , the sawdust is conversely discharged obliquely to the side. 
     At the abutting point between the pivot tube  32  and the feed tube  18 ′, the feed tube  18 ′ and the pivot tube  32  have spherically shaped connection pieces  40  and  42 , respectively; the connection pieces  40 ,  42  have the same outer diameter. 
     This offers the advantage first that the outer contours of the feed tube  18 ′ and of the pivot tube  32  merge with one another without discontinuities, which contributes to a visually attractive overall impression. 
     Second, in this way, discontinuities of contour at the abutting point are avoided even upon a rotation of the pivot tube  32 . 
     Finally, the spherical thickening at the abutting point between the feed tube  18 ′ and the pivot tube  32  clearly shows the rotary function of the pivot tube  32 , which is thus self-explanatory. 
     In the position of the pivot tube  32  shown in  FIGS. 3   a  and  3   c , the pivot tube  32  conversely discharges into a connection tube  43  in the covering  10 ″, so that the sawdust is carried onward inside the covering  10 ″ and finally escapes through an outlet opening on the underside of the covering  10 ″. 
     The exemplary embodiment of a circular power saw of the invention shown in  FIGS. 4   a  through  4   d  largely matches the exemplary embodiment described above and shown in  FIGS. 3   a  through  3   d , so that below, the same reference numerals are used for components that correspond to one another, and to avoid repetition, reference is made to the description above. 
     The special feature of this exemplary embodiment is that the feed tube  18 ″ and the pivot tube  32 ′ have no spherical thickening at the abutting point, so that a different visual impression is given. 
     The invention is not limited to the preferred exemplary embodiments described above. On the contrary, many variants and modifications are possible that likewise make use of the concept of the invention and are therefore within the scope of the invention. 
     LIST OF REFERENCE NUMERALS 
       8  Saw blade 
       10 ,  10 ′,  10 ″ Covering 
       12  Flap 
       13  Pivot axis 
       14  Pivot tube 
       15  Outlet opening 
       16 ,  16 ′ Front region of the covering 
       18 ,  18 ′,  18 ″ Feed tube 
       20  Rotary slide 
       21  Axis of rotation 
       22  Rear region of the covering 
       24  Guide tube 
       26  Handle 
       28  Grip indentations 
       30  Knurled structure 
       32 ,  32 ′ Pivot tube 
       34  Longitudinal axis of the feed tube 
       36 ,  36 ′ Axis of rotation of the pivot tube 
       38  Longitudinal axis of the pivot tube 
       40  Connection piece of the feed tube 
       42  Connection piece of the pivot tube 
       43  Connection tube