Abstract:
The present blade device invention comprises an elongated housing wherein the housing comprises forward and rearward end portions and wherein the forward end portion defines an opening. The invention further comprises a blade holder moveable along a length of the housing toward the forward end portion and an actuator moveable along the length of the housing toward the forward end portion wherein the actuator is associated with the blade holder to impart movement to the blade holder toward the forward end portion of the housing. The invention further comprises a projection secured to one of the blade holder and the actuator wherein the projection extends in a direction transverse to the length, wherein the projection comprises a control surface which extends in a direction nonparallel to the length, wherein the other of the actuator and the blade holder to which the projection is not secured contacts the control surface and wherein the blade holder is movable in the direction nonparallel to the length.

Description:
RELATED APPLICATION  
       [0000]     Foreign Application Priority Data:  
         [0001]     Filed Dec. 22, 2004 [DE] Germany DE 10 2004 063 046.1.  
       FIELD OF THE INVENTION  
       [0002]     This invention relates to a blade holding device and more particularly a blade holding device wherein the blade is extendable and retractable.  
       SUMMARY OF THE INVENTION  
       [0003]     The present blade device invention comprises an elongated housing wherein the housing comprises forward and rearward end portions and wherein the forward end portion defines an opening. The invention further comprises a blade holder moveable along a length of the housing toward the forward end portion and an actuator moveable along the length of the housing toward the forward end portion wherein the actuator is associated with the blade holder to impart movement to the blade holder toward the forward end portion of the housing. The invention further comprises a projection secured to one of the blade holder and the actuator wherein the projection extends in a direction transverse to the length, wherein the projection comprises a control surface which extends in a direction nonparallel to the length, wherein the other of the actuator and the blade holder to which the projection is not secured contacts the control surface and wherein the blade holder is movable in the direction nonparallel to the length.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is a side plan elevational view of one embodiment of the present invention with a portion of the housing removed and the blade in a retracted position;  
         [0005]      FIG. 2  is the view of the present invention of  FIG. 1  with the actuator moved forward from the retracted position such that the end of the coupling member makes a contact with the blade holder;  
         [0006]      FIG. 3  is the view of the present invention of  FIG. 2  with the actuator and blade holder moved further toward the forward end portion of the housing thereby positioning the blade in an extended working position;  
         [0007]      FIG. 4  is the view of the present invention of  FIG. 3  with the blade receiving a force from a work piece, which results in the blade holder being displaced in two directions and the end of the coupling arm being removed from the contact it had with the blade holder;  
         [0008]      FIG. 4   a  is partially broken away view of another embodiment of the present invention as shown in  FIG. 4 ;  
         [0009]      FIG. 5  is the view is the view of the present invention of  FIG. 4  wherein the blade holder retracts the blade toward the rearward end portion of the housing; and  
         [0010]      FIG. 6  is the view of the present invention of  FIG. 5  wherein the actuator has moved closer toward the rearward end portion of the housing and the coupling arm is moved in a direction nonparallel to the direction of the length of the device for aligning the end of the coupling arm with the area of the contact as seen in  FIG. 1  with the actuator in its fully retracted position.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     In the drawings of the present invention an embodiment of the invention is shown in  FIGS. 1-4  and  5 - 6 .  
         [0012]     In  FIG.1 , knife  10  is shown with only one shell half  12  of a casing or housing  11  of a knife  10 , here a safety knife.  
         [0013]     The casing half  12  has a longitudinally extending cavity  13  in which a blade holder  14  is displaceable in a straight line along a center axis M in an forward extension direction x and an rearward retraction direction z.  
         [0014]     A front end  15  of the blade holder  14  holds a sheet-steel knife blade  16  here of trapezoidal shape. The blade  16  has a cutting edge  17 .  
         [0015]     A part of the front end  15  of the blade holder  14  is shown broken away so as to expose other parts of the knife  10 . Immediately rearward in the direction z of the front end  15  of the blade holder  14  is a guide formation  18  defining a longitudinally extending slot  19  holding a tension spring  20 . A front end  21  of the tension spring  20  is anchored on the blade holder  14  and a rear-end eye  22  is hooked on the casing shell  12 . The tension spring  20  urges the blade holder  14  rearward in the retraction direction z in the knife casing  11 .  
         [0016]     The front end  15  of the blade holder  14  has a laterally projecting slide formation GV that defines a planar slide face GE that forms a small acute angle β with the extension direction x.  
         [0017]     Inside the cavity  13  there is also an actuating slide  24  that can move longitudinally in the extension direction x and retraction direction z in the longitudinal cavity  13 .  
         [0018]     The actuating slide  24  has a rear end  25  and a front end  26 , the latter with a front slide edge GK.  
         [0019]     Another tension spring  27  has a front-end eye  28  hooked on the actuating slide  24  and a rear-end eye  29  anchored to the housing shell  12  at the rearward end portion of housing  12 . The tension spring  27  urges the actuating slide  24  rearward in the retraction direction z.  
         [0020]     The blade holder  14  and actuating slide  24  can move in parallel paths with a limited relative lateral play Q.  
         [0021]     The rear end  25  of the actuator slide  24  also carries in the longitudinal cavity  13  a generally T-shaped part  30  that is formed of an elastically deformable material, in particular spring steel. The T-shaped part  30  has a center leg  31  seated in the rear end  25  of the actuating slide  24  at  40 . The end of the leg  31  projecting from the rear end  25  of the actuating slide  24  meets a T-crosspiece  32  at an intersection  42 . The part of the crosspiece  32  extending forward from the intersection  42  in the extension direction x is a coupling arm  33 . The part of the crosspiece  32  extending rearward in the retraction direction z is a control arm  34  that coacts with a control face SF of a cam bump  35  that is formed on the casing shell  12 .  
         [0022]     The control face SF according to  FIGS. 1-4  and to  FIGS. 5 and 6  forms a slide face for the coupling arm  34  and defines a small acute angle a with the retraction direction z.  
         [0023]     In this embodiment, mating coupling members comprise a front end of the coupling arm  33  which forms a primary coupling element P while a coupling opening (cutout) forms a recess open in the rearward retraction direction z of the blade holder  14  forms a secondary coupling element S.  
         [0024]     The crosspiece  32  thus forms a two-arm lever that has the coupling arm  33  of the coupling element P extending forward in the extension direction x from a pivot formed by the center leg  31  and on the other side of the pivot the control  34  arm extending rearward in the retraction direction z.  
         [0025]     The control arm  34  can engage the control face or surface SF when the actuating slide  24  is drawn in the retraction direction into a rear position. This pivots the crosspiece  32  such that the primary coupling element P moves out of a freeing position outside the path of the secondary coupling element S into a ready position engageable in the secondary coupling element S.  
         [0026]     The knife  10  operates as follows:  
         [0027]     In  FIG. 1  the knife  10  is in a rest position. The tension spring  27  has pulled a rear end face  36  of the actuating slide  24  against an abutment face  37  of the casing shell  12 . At the same time the primary coupling element P is spaced at a slight distance (in the ready position) from the secondary coupling element S.  
         [0028]     As shown in  FIG. 2 a  manual force H is applied in the extension direction x to an actuating projection  38  so that the control arm  34  pulls out of contact with the control face SF. At the start of outward movement in the direction z the primary coupling element P fits into the secondary coupling element S since the control arm  34  as a result of the springiness of the T-shaped part  30  continues to bear on the control face SF. This holds the primary coupling element P aligned with the secondary coupling element S.  
         [0029]     The manual force H effective in extension direction causes the control arm  34  to move off the control face SF so that as shown in  FIG. 3  the knife blade  16  projects through a slot or opening  23  in the knife housing  11 .  
         [0030]     A comparison of  FIGS. 2 and 3  shows that the slide edge GK of the control projection  26  during the entire travel in the direction x from the  FIG. 2  position to the  FIG. 3  position is below the slide plane or control surface GE of the slide projection or projection GV.  FIG. 3  shows that the blade holder  14  and the blade  16  are not completely extended.  
         [0031]     When as shown in  FIG. 3 a  cutting force D is applied, e.g. perpendicular to the edge  17  of the blade  16 , the blade carrier  14  shifts downward as seen by comparing  FIGS. 3 and 4  with its planar slide face GE along the slide edge GK through the transverse play Q and through a longitudinal offset R as shown in  FIG. 4 . This displacement of blade holder  14  relative to the actuator  24  separates the elements P and S from each other while leaving the actuating part  24  advanced in the direction x into a forward position.  
         [0032]     In any of the positions moving from  FIG. 1  and to  FIG. 4  it is clear that the force converter GE/GK formed by the slide face or control surface GE and the slide edge GK is always effective independent of the extended or withdrawn position in the directions x or y, so long as there is a lateral force D which can of course also be angled to the blade edge  17 .  
         [0033]     It is therefore possible for the knife  10  in the position of  FIG. 4  to cut until the blade  16  exits the workpiece, whereupon the blade  16  is no longer held by the workpiece and the spring  20  pulls back the blade holder  14  until the position of  FIG. 5  is reached. Once the edge  17  of the blade  16  is disengaged from the unillustrated workpiece the spring  20  is effective and the blade holder  14  along with the blade  16  it is holding are pulled in the retraction direction z back into a protected position in the knife casing  11 .  
         [0034]     It is also possible with an unillustrated embodiment as a result of the separation of the coupling or decoupling between the elements P and S for the blade holder  14  with the blade  16  not to pull back in the refraction direction into the knife casing  11 . Instead the potential energy of the tension spring stretched in the direction x can be used to extend a shield, for example a standard shield pin, parallel to the center axis along the blade edge  17  in order to reduce the likelihood of accidental cuts.  
         [0035]      FIG. 5  also shows that the manual force H is that same and that the actuating element or actuator  24  remains in its position advanced in the direction x.  
         [0036]     When the manual force H is removed, the position of  FIG. 6  is assumed, with the slide edge GK back at the lower end of the slide face GE. The rear end face  36  of the actuating slide  24  is still spaced from the knife-housing abutment face  37 . Meanwhile the primary coupling element P is below the secondary coupling element S while the end of the control arm  34  of the T-shaped part  30  touches the control face SF of the control cam  35 . The part  30  starts to deform elastically. This makes the control arm  34  work on moving backward in the retraction direction x against an axial spring force while at the same time the coupling arm  33  moving in the retraction direction z passes with its primary coupling element P the secondary coupling element S.  
         [0037]     Going from the position of  FIG. 6  to that of  FIG. 1  makes the tension spring  27  fully effective since the rear end face  36  of the actuating slide  24  bears against the casing abutment face  37 . At the same time the control arm  34  of the T-shaped part  30  pushes with increasing force against the control face SF of the control cam  35  and bends the T-shaped part  30  so much that the coupling arm  33  of the crosspiece  32  bears against a lower longitudinal edge  39  of the guide projection  18  and thus sets the primary coupling element P in a ready position at a slight spacing forward of the secondary coupling element S.  
         [0038]      FIG. 4A  corresponds to the functional position shown in  FIG. 4 . Here the crosspiece  32  is differently shaped as shown in  FIG. 4A , in that it is formed of two offset rigidly interconnected parts forming a Z, namely a rigid coupling arm  33 , a central rigid connection bight  44 , and a rigid control arm  34  projecting from the rigid bight  44 .  
         [0039]     The central bight  44  is mounted at a pivot G in the rear end of the actuating slide  24 . The coupling arm  33  forming the primary coupling element P is biased downward by a spring  41  against a schematically illustrated abutment A. Otherwise the operation of the system of  FIG. 4A  is analogous to that of  FIGS. 5, 6 , and  1 .  
         [0040]     The embodiment according to  FIG. 4A  has the advantage that as a result of the rigidity of the crosspiece  32  larger forces can be transmitted via the slide part  24  in the direction x to the blade holder  14 , serving for instance for stabbing the blade  16  into thick cardboard.  
         [0041]     In any case the T-shaped part  30  according to  FIGS. 1-6  as well as the rigid crosspiece  32  of  FIG. 4A  form a two-arm lever in the broadest sense, having a lever arm  33  (coupling arm) and a lever arm  34  (control arm). The pivot axis is either defined by the flexible leg  31  above its anchor point  40  ( FIGS. 1-6 ) or by the pivot G ( FIG. 4A ).  
         [0042]     A particular feature of the embodiment of  FIG. 4A  is that the control arm  34  holds a spring-loaded bumper  43  effective parallel to the two directions x and z and that can be pushed through a spring travel AF created by a compression spring F to be flush with a rear end face  37  of the rear end  25 .  
         [0043]     The embodiment of  FIG. 4A  functions as follows:  
         [0044]     Once the cutting operation is completed and the edge  17  of the blade  16  has separated from the workpiece, the tension spring  20  pulls the blade holder  14  back into its retracted position as shown in the position of  FIGS. 5 and 6 . The tension springs  20  and  27  are for clarity&#39;s sake not shown in  FIG. 4A  but are the same as in  FIGS. 1-6 .  
         [0045]     Shortly before the actuating slide  24  (see  FIG. 6 ) shown in  FIG. 4  reaches its retracted position (see  FIG. 1 ), in which the end face  36  of the actuating slide  24  engages the casing abutment face  37 , the free end of the spring bumper  43  engages the casing abutment face  37 . It is clear that in this embodiment of  FIG. 4A , abutment face  37  forms control face SF (not shown in  FIG. 4A ) such as shown in  FIG. 4  wherein the control surface would be aligned to engage spring bumper  43  with retraction of actuator  24 .  
         [0046]     At the same time the primary coupling part P formed by the coupling arm  33  is swung upward against the guide extension  18  of the blade holder  14  and the bumper spring F in the control arm  34  is compressed until the spring bumper  43  is entirely in the control arm  34  and thus disappears in the rear end  25  of the actuating slide  24 . During such inward travel of the spring bumper  43  the coupling arm  33  with its primary coupling element P travels also in the retraction direction z past the secondary coupling element S. This holds the coupling arm  33  in an upper pivoted position.  
         [0047]     At the start of a subsequent outward movement of the actuating slide  24  in the direction x the bumper spring F extends somewhat. The bumper  43  projects to a certain extent from the control arm  34  and projects from the rear end  25  of the actuating slide  24  so that the primary coupling element P is shifted forward in the direction x out of its ready position (see  FIG. 1 ) into the secondary element S (see  FIG. 2 ) while the spring bumper  43  holds the coupling arm  33  in its upper pivoted position.