Patent Document

FIELD OF THE INVENTION 
       [0001]    The present invention relates to a woodworking machine, in particular a circular saw, provided with a machine frame on which a table board is accommodated, and further provided with a swivel frame arranged underneath the table board, which can be swivelled about a swivel axis coplanar with the top side of the table board, which swivel frame accommodates a height adjustable tool bracket carrying at least one cutting tool engaging an associated slot in the table board, which tool can be clamped onto a shaft drivable by a motor attached to the tool bracket. 
       BACKGROUND OF THE INVENTION 
       [0002]    An arrangement of this kind is known, for example, from EP 0 235 683 B1. In this known arrangement, the swivel frame, in the region of its front and rear end, is provided with sliding stones which in pairs engage an associated curved slot of a front and rear stationary end shield which is integrated into the machine frame. Such end shields, at their bottom rim which is concentric to the curved slot, are provided with gear teeth which are in engagement with a pinion that can be driven by a handwheel. The pinion shaft associated with the pinions and accommodating the handwheel is mounted on the swivel frame and projects from the machine frame requiring, for that purpose, a reach-through slot which is arranged in concentric position to the curved slot of the stationary end shields. 
         [0003]    The disadvantage, however, of such an arrangement lies in the fact that the pinion shaft carries out all swivel movements of the swivel frame, so that the handwheel accommodated on the pinion shaft changes its position during each swivel movement of the swivel frame. This constitutes an undesirable effect with regard to operation. Furthermore, the reach-through slot of the machine frame, through which the pinion shaft extends may constitute a safety risk and has to be guarded accordingly. The direct transmission of the rotary movement of the handwheel to the swivel frame has an unfavourable effect also with regard to the obtainable degree of accuracy. Furthermore, in the known arrangement the swivel frame suspended in the machine frame is separated from the table board, rendering assembly difficult. 
         [0004]    On the basis of the foregoing, it is thus the object of the present invention to improve a device as described initially above by using simple and low-cost means, so that not only a high degree of user-friendliness, safety and accuracy, but also a clear-cut design are achieved. 
       SUMMARY OF THE INVENTION 
       [0005]    According to the invention, this object is achieved in that the swivel frame in the region of its ends, which in cutting direction lie opposite each other, is swivel-suspended on bearing brackets which are mountable on the bottom side of the table board, and can be swivelled by means of an articulated adjusting rod arranged with a degree of freedom for swivel movements, and further in that the tool bracket accommodated on the swivel frame can be height adjusted by means of an adjusting element provided on the swivel frame, such adjusting element being arranged in driving linkage with an extendable articulated shaft, and further in that the adjusting rod and the articulated shaft can be operated by at least one actuating means firmly mounted on the operating side of the machine frame. 
         [0006]    In this example, the table board as well as the swivel frame together with the tool bracket constitute a group of components all of which, in an advantageous manner, can be pre-assembled. This fact ensures an exact position of the swivel axis of the swivel frame, which is coplanar with the table surface, and thus a high degree of obtainable working accuracy. The adjusting rod associated with the swivel frame and actuatable by means of an actuating means further ensures a high reduction ratio which has an advantageous effect on the achievable degree of operating accuracy. The same applies to the articulated shaft associated with the tool bracket, ahead of and/or following which provision may be made for reduction devices. A further advantage of the measures according to the invention lies in the fact that each actuating means, due to its flexibility within the drive train, is in a stationary position relative to the swivel frame and/or the tool bracket, so that neither in this case a reach-through slot in the housing associated with a shaft connected with an actuating means is required. As a result, a high degree of user-friendliness and safety as well as high stability of the machine housing is obtained. The measures according to the invention thus in an advantageous manner completely avoid the disadvantages of the prior art arrangement. 
         [0007]    Advantageous embodiments and expedient developments of the main-claim measures will be evident from the sub-claims. 
         [0008]    Thus, the adjusting rod associated with the swivel frame may advantageously be designed as a threaded spindle which on one side engages a bolt which is swivel-mounted in the swivel frame and in axial direction accommodated stationary in the same, and is on the other side swivel-mounted about the axle of the associated actuating means and acts together with the associated actuating means via angle drive. By using a threaded spindle, a comparatively high reduction ratio is achieved which, if required, may even be increased by a suitable design of the angle drive. Furthermore, the threaded spindle in an advantageous manner causes a self-locking effect which enhances operating convenience and accuracy. 
         [0009]    In a further development of the main-claim measures, the adjusting element associated with the tool bracket may advantageously be designed as a threaded spindle which is provided on the swivel frame in a vertical position, which threaded spindle engages a bolt firmly attached to the tool bracket and, via an angle drive, is connected with an articulated shaft provided with joints at both ends thereof. This arrangement likewise ensures in an advantageous manner a high reduction ratio as well as a self-locking effect. 
         [0010]    A further, particularly preferable measure may consist in that the adjusting rod and the adjusting spindle are associated with an actuating means each which may be provided in an advantageous manner at a certain lateral distance and at the same level. Said measures enable the swivel device and the height adjustment to be actuated synchronously. 
         [0011]    Expediently, the swivel frame may be designed as a casting comprising a vertical wall which is provided with at least one window opening toward the top through which passes a shaft carrying a cutting tool and, on the side away from the tool comprises a projection accommodating the vertical threaded spindle associated with the tool bracket, as well as guiding means for the tool bracket in a direction parallel to the spindle. This arrangement permits a low-cost and torsion-resistant design of the swivel frame. It is therefore sufficient to provide one adjusting rod. 
         [0012]    Advantageously, the swivel frame, at least on its tool side, may be provided with a circumferential marginal flange to which a cover plate is attached and which is preferably interrupted in the tool area. Thus, a chamber associated with the tool and opening towards the top is advantageously formed which can be connected to an exhaust device, which facilitates chip removal. 
         [0013]    Expediently, the tool bracket may likewise be designed as a casting comprising a vertical wall which, on the one hand, is provided with projections having guide sleeves, as well as a bearing region associated with the tool carrying shaft, and, on the other hand, with a projection comprising the nut acting together with the threaded spindle thus forming the adjusting element. This arrangement results in a tool bracket which combines the advantages of low-cost and torsion-resistant construction. Simultaneously, the use of castings for the swivel frame and the tool bracket permit a high degree of freedom from vibration, which likewise has a positive effect on the obtainable degree of accuracy. 
         [0014]    Further advantageous embodiments and expedient developments of the main-claim measures will be evident from the remaining sub-claims and from the description of an example given below in conjunction with the accompanying drawing(s), wherein— 
     
    
     
       BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS 
         [0015]      FIG. 1  shows a view of the operator side of a circular saw according to the invention with removed inspection cover and a partly broken out front wall; 
           [0016]      FIG. 2  shows a longitudinal section of the arrangement according to  FIG. 1 ; 
           [0017]      FIG. 3  shows a schematic top view of the arrangement according to  FIG. 1  with the table board removed; 
           [0018]      FIG. 4  shows a perspective view of the swivel frame with integrated tool bracket and the associated bearing brackets; 
           [0019]      FIG. 5  shows a view of a scoring unit which can be attached to the swivel frame; and 
           [0020]      FIG. 6  shows a view of the circular saw according to the invention corresponding to  FIG. 1  with fitted inspection cover comprising display units. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    The present invention is mainly used for circular saws which are provided with a cutting tool having the form of a circular saw blade. The circular saw underlying the drawing possesses a housing-shaped machine frame  1  on which a table board  2  is accommodated. The housing-shaped machine frame  1 , as is evident from  FIG. 1 , is on the operator side provided with an inspection window  3  which can be closed by an inspection cover shown in removed position in  FIG. 1 . In  FIG. 6  the inspection cover  4  is fitted. The table board  2  possesses a slot not shown in detail in the drawings through which the tool, in this example designed as a saw blade  5 , extends. Associated with the saw blade  5  is a board splitter  6  which can best be seen in  FIG. 2 , to which an exhaust hood  7  may be attached. 
         [0022]    The saw blade  5  can be adjusted in height, which fact permits the machining of workpieces of a different thickness. In order to make angular cuts which are inclined relative to the surface of the table board  2 , it is possible to tilt the saw blade  5 . The swivel axis is practically formed by the intersection line of the surface of the table board  2  with the centre plane of the saw blade  5 . Based on a vertical midway position shown by solid lines in  FIG. 1 , provision can be made for a swivel movement to each side (right or left) or to both sides. In  FIG. 1 , two possible adjusting positions are indicated by dotted lines. 
         [0023]    The saw blade  5 , as can be seen in the  FIGS. 2 and 3 , can be clamped on a tool shaft  8  located underneath the table board  2  which is drivable by an associated electric motor  9 . Expediently, the motor shaft is offset relative to the tool shaft  8  and arranged in drive linkage with a stepping down unit  10  as can best be seen in  FIG. 2 , which stepping down unit may be designed as a belt drive. The tool shaft  8 , as is further shown in the  FIGS. 2 and 3 , is mounted on a tool bracket  11  to which the motor  9  is likewise attached. The tool bracket  11  on its part is height adjustable and accommodated on a swivel frame  12  arranged underneath the table board  2 , which is swivellable about the swivel axis as described above which is coplanar with the upper side of the table board. 
         [0024]    Said swivel frame  12 , as can best be seen in  FIG. 4 , is provided with ring segment-shaped bearing strips  13  arranged at its ends lying opposite each other in cutting direction and extending concentrically to the above-described swivel axis, such swivel frame  12  being swivel-mounted together with the said bearing strips  13  on the bearing brackets  14  which are attachable by means of screws to the bottom side of the table board  2 . The bearing brackets  14  are provided with segment grooves  15  associated with the bearing strips  13  which engage the segment grooves  15  in a groove and tongue engagement. The table board  2 , the bearing brackets  14  mountable thereon as well as the swivel frame  12  which can be accommodated on the latter and the tool bracket  11  which is receivable on said swivel frame  12  form a group of components which can be pre-assembled as a unit. The tool bracket  11  and the swivel frame  12  are expediently designed as castings, as is clearly illustrated in  FIG. 4 . 
         [0025]    In order to swivel the swivel frame  12 , an adjusting rod  17  is associated therewith, as can be seen in the  FIGS. 1 and 3 , which can be actuated by means of a handwheel  16  provided in the region of the operator side of the machine frame  1 , which adjusting rod  17  is articulated to the swivel frame  12  and possesses the required degree of freedom for tilting movements. The adjusting rod  17  may be designed, for example, as a threaded rod or the like. In the illustrated example, the adjusting rod  17 , in an advantageous manner, is designed as a threaded spindle which, on the one hand, engages a nut  18  which is swivel-mounted in the swivel-frame  12 , and in an axial direction accommodated stationary in the same, and, on the other hand, can be swivelled about the axis of rotation of the associated handwheel  16  and acts together with the handwheel  16  via an angle drive  19 , as is evident from  FIG. 3 . The angle drive  19  is formed by two bevel gears, one of which is accommodated on a shaft butt  20  held in a bearing on the frame and connected with the handwheel  16 , while the other is received by the neighbouring end of the adjusting rod  17  engaging a bearing housing  21  which can be swivelled about the axis of the shaft butt  20 . The design of the adjusting rod  17  as a threaded spindle provides a self-locking effect combined with a large reduction ratio. The nut  18  associated with the threaded spindle, as can best be seen in  FIG. 4 , is designed as a pin which can be moved about its axis and is held by a fork shaped bearing  22  attached to the swivel frame  12 , which pin is provided with a tapped hole which extends transverse to its axis and is engaged by the threaded spindle forming the adjusting rod  17 . 
         [0026]    The height adjustable tool bracket  11  accommodated on the swivel frame  12 , as is evident from the  FIGS. 2 to 4 , is guided on vertical guiding rods  23  of the swivel frame  12 . In the illustrated example, provision is made for two guiding rods  23  flanking a window  24  for the tool shaft  8  and/or the bearing device associated therewith. The tool bracket  11  is provided with guide bushes  25  associated with the guiding rods  23 . In order to permit adjustment of the tool bracket  11  in a vertical direction on the swivel frame  12 , provision is made for a threaded spindle  26 , as can further be seen in the  FIGS. 2 to 4 , which is parallel to the guiding rods  23 , accommodated on the swivel frame in a vertical position and which serves as an adjusting device associated therewith, which spindle is in engagement with a nut  27  mounted on the tool bracket  11 . 
         [0027]    The threaded spindle  26  is accommodated on a projection  28  of the swivel frame  12  extending underneath the tool bracket  11  and drivable by an angle drive  29  which is provided on the bottom side of the projection  28 . The nut  27  is arranged on a projection  30  of the tool bracket  11  and extends over the projection  28 . 
         [0028]    The angle drive  29  is formed by two bevel gears, one of which is mounted on a receiving butt of the threaded spindle  26  and extends through the projection  28 , while the other is accommodated on an associated gear shaft  31  mounted on a gear housing which is formed by a bow attached to the projection  28 . Joined to the gear shaft  31  is an articulated shaft  32  which, with its other end, is joined to a drive wheel  33 , as can best be seen from  FIG. 2 , which is swivel-mounted on the inner side of the operator side wall of the machine frame  1 . Said drive wheel  33 , as is evident from the  FIGS. 2 and 3 , is connected in terms of drive with an associated counter wheel  35  via a circulating element  34 , such counter wheel  35  being received by a shaft butt  36  which is swivel-mounted on the operator side of the machine frame  1 , the outer end of such shaft butt  36  carrying an associated handwheel  37 . Expediently, the circulating element  34  is designed as a chain. The drive wheel  33  and the counter wheel  35  are thus designed as sprockets. The handwheel  37  could of course likewise be mounted on a shaft receiving the drive wheel  33 . The illustrated embodiment, however, facilitates the provision of the handwheels  16  and  37  at the same height level. 
         [0029]    By turning the handwheel  37 , the threaded spindle  26  is driven via the drive train in the form of the chain drive comprising the circulating element  34 , the articulated shaft  32  fitted with joints on both sides, and the angle drive  29 . The rotational movement of the threaded spindle  26  is converted into an adjustment movement of the tool bracket  11  by means of the nut  27 . As a result, this arrangement provides for a high reduction ratio as well as a self-locking effect. 
         [0030]    The length of the articulated shaft  32 , which is fitted with joints at both ends, is adjustable, so that such articulated shaft  32  permits a swivel movement of the swivel frame  12 . For this purpose, the articulated shaft  32  is designed as a two-part shaft comprising two shaft sections  32   a, b  having multi edge areas which engage each other in a telescope-like manner. Said multi edge areas may be formed integral with each of the associated shaft sections. 
         [0031]    In the illustrated example, provision is made for two handwheels  16  and  37 , with the handwheel  16  serving for carrying out a swivel movement of the swivel frame  12  and the handwheel  37  serving for carrying out a height adjustment of the tool bracket  11  received on the swivel frame  12 . The handwheels  16  and  37  are arranged at a certain lateral distance from each other and at approximately the same height level in the region of the operator side of the machine frame  1 , as is evident from  FIG. 1 . It would, however, be equally conceivable to provide solely one common handwheel to carry out the swivel movement and the height adjustment. Such handwheel could be arranged in an axially adjustable manner and could be alternatively coupled in its end positions with an element acting together with the adjusting rod  17  and/or the articulated shaft  32 . 
         [0032]    As previously mentioned, the swivel frame  12  is expediently designed as a casting. The latter, as can be seen in the  FIGS. 3 and 4 , possesses a vertical wall  38  comprising a reach-through window  24  associated with the tool shaft  8  which wall, on the side away from the cutting tool, is provided with ribs  39  comprising a rim flange extending along the rim of said wall. The ribs are designed in such a manner that two chambers  40  are formed which flank the reach-through window  24  and extend over the entire height of the swivel frame  12 , and in each of such chambers provision is made for an adjusting rod  23 . The adjusting rods  23  with their upper and lower ends are attached to the rim flange areas closing each of the associated chambers. The tool bracket  11  is provided with protrusions  41  projecting into the chambers  40 , such protrusions  41  comprising an adjusting rod  23  each held by a guide bush  25 . In the region underneath the reach-through window  24  provision is made for the projection  28  of the swivel frame  12  associated with the threaded spindle  26  which may be integrated into the rib arrangement  39 . The fork shaped bearing  22  for receiving the nut  18  associated with the adjusting rod  17  is attached to the swivel frame  12  and expediently formed integral therewith in the region of the end of the swivel frame  12  facing the operator side. 
         [0033]    On the side facing the cutting tool  5 , the wall  38  of the swivel frame  12  does not possess any ribs. In this area, provision is solely made for a rim flange  42  extending at least laterally of and underneath the wall, but omitted on top of it or interrupted at least in the region of the cutting tool, to which rim flange  42  a cover plate  43  extending parallel to the wall is attached, as shown in  FIG. 3 . In this manner, a chamber  44 , which is open at the top, is formed for receiving the tool  5 . A connector  45  as shown in the  FIGS. 2 and 3  for attaching a suction line branches off from the chamber  44 . The connector  45 , via a pipe not shown in detail here, may be connected with a sleeve  46  provided in the area of a wall of the machine frame  1 , which sleeve  46  may possess a further connector  47  for a suction line extending from the exhaust hood  7  and may in a manner known to the art be connected with an exhaust blower. A pin  48  projecting from the wall  38  and accommodating a board splitter  6  extends through the chamber  44 , as is evident from  FIG. 3 . 
         [0034]    The tool bracket  11  is likewise formed as a casting comprising, as is shown in the  FIGS. 3 and 4 , a vertical wall  49  parallel to the wall  38  of the swivel frame  12 , to which wall  49 , on the one hand, a bearing device  50  is attached which is associated with the tool shaft  8  and the protrusions  41  comprising the bearing bushes  25 , and to which, on the other hand, the projection  30  carrying the nut  27  is attached. On the side away from the swivel frame  12  the wall  49  is in an expedient manner provided with ribs. As can be seen in the  FIGS. 2 to 4 , an adjustable retaining plate  51  parallel to the wall and carrying the motor  9  is attached to the ribs. Due to the adjustability of the retaining plate  51 , a reliable tension of the belt of the belt drive  10  is ensured. In the illustrated example, the retaining plate  51  is held by screws passing through associated oblong holes. 
         [0035]    When cutting coated boards etc, a scoring tool is usually required which rotates in a direction opposite to the direction of rotation of the actual sawing tool  5 . In  FIG. 5  a scoring unit  53  is shown which comprises a scoring tool  52  which can optionally be attached to the swivel frame  12 . In the  FIGS. 2 and 3 , the scoring unit  53  is mounted on the swivel frame  12 . In  FIG. 4  the scoring unit is removed. The scoring tool  52  is arranged in the same plane as the tool  5  and scores the coating of a board which can subsequently be cut through with the aid of the sawing tool  5  without causing the risk of the coating breaking. The scoring unit  53  comprises an electric motor  54  which, via a stepping down unit  55  expediently designed as a belt drive, is connected in terms of drive with a shaft  56  receiving the scoring tool  52 . The scoring unit  53 , as mentioned on an earlier occasion, is designed as an add-on unit. For this purpose, the scoring unit  53  comprises an add-on device which is attachable to a suitable associated fixture of the swivel frame  12 . 
         [0036]    In the example illustrated, the vertical wall  38  of the swivel frame  12 , as can be seen in  FIG. 4 , is provided with mandrels  57  projecting from the side away from the tool and forming the fixture for accommodating the scoring unit  53 . The latter comprises an add-on shield  58  which is adjustably attachable by means of screws to the mandrels  57 , as is indicated by the curved slots  59 . 
         [0037]    Attached to the add-on shield  58 , as can best be seen in  FIG. 5 , is, on the one hand, the motor  54  and, on the other hand, a support block  60  on which an adjusting block  61  is accommodated comprising the scoring tool  52  which is both height and axially adjustable. The shaft  56  carrying the scoring tool  52  is mounted in the adjusting block  61  and, with sufficient play to allow for axial and vertical adjustment, can be passed through an associated recess in the wall  38 . Said recess is covered by a cover plate  62 , as is shown in  FIG. 4 . As can further be seen in  FIG. 5 , the adjusting block  61  is provided with two adjusting screws  63 , one of which serving for height adjustment and the other for axial adjustment. The height is adjusted via the thread of the associated screw  63 . The motor  54  is arranged in such a manner that the belt of the stepping down unit  55  is in tensioned condition in any position of the adjusting block  61 . In order to effect axial adjustment, the associated screw  63  is provided with a worm not shown in  FIG. 5 . Such worm acts together with an axially movable worm gear  75  fitted along its circumference into an associated recess of the adjusting block, which worm gear has a lateral provided with a thread engaging a counter thread of the adjusting block. Held in the worm gear  75  together with the collar is the shaft  56 . The adjusting screws  63  are accessible from above via holes  64  (shown in  FIGS. 2 and 4 ) in the table board  2  and in the upper side of the swivel frame  12 , and can be actuated by an appropriate tool. 
         [0038]    To facilitate an exact setting of the desired height of the tool  5  and/or the desired swivel angle of the tool  5  provision is made for associated display devices from which the selected height and/or swivel angle can be read off. Each of the display devices comprises a scale and an associated pointer which are arranged in such a way that readings can be taken on the operator side of the machine, as can be seen in  FIG. 6 . 
         [0039]    The angle display unit comprises an angle scale  66  provided on a board  65  shown in  FIG. 4  which is attached to the end of the swivel frame  12  facing the operator side of the machine frame  1  and extends parallel to the operator-side wall of the machine frame  1 . The operator-side wall of the machine frame  1 , in this example the inspection cover  4  forming an element of the wall, is provided with a window  67  exposing the angle scale  66 , as is evident from  FIG. 6 . Attached to the rim of the window  66  is a pointer  68  indicating the selected angle position. An enlargement lens may be associated with the window  67  to improve readability. 
         [0040]    The height display device comprises at least one height scale  70  which is provided in the rim area of a window  69  of the inspection cover  4  and with which a movable pointer  71  is associated appearing in the area of the window  69 . Such pointer, as is shown in  FIG. 4 , is attached to a plate  72  which is parallel to the operator-side wall of the machine frame  1  and which is attached to the height adjustable tool bracket  11  by means of a bow  73 . In the area of the window  69  provision is expediently made for several different height scales  70  which are associated with different tool diameters. In the example illustrated, provision is made for two different height scales  70 , as is evident from  FIG. 6 .

Technology Category: 4