Abstract:
A cutting tool ( 1 ), and a method of exchanging an interchangeable blade as well as a cutting tool housing, in particular for severing flat and/or strand-form materials. The cutting tool ( 1 ) includes a housing ( 2 ), at least one interchangeable blade ( 8 ) arranged at a holding portion ( 6 ) of the housing ( 2 ), and a locking member ( 40 ) arranged movably on the housing ( 2 ) for locking the blade ( 8 ) to the housing ( 2 ). The housing ( 2 ) has first positively locking elements ( 23, 24, 26, 28 ) and the locking member ( 40 ) has second positively locking elements ( 42 ) which jointly lock the blade ( 8 ) in a given position to the housing ( 2 ).

Description:
BACKGROUND 
     The invention concerns a cutting tool, in particular for severing flat and/or strand-form materials. The invention further concerns an interchangeable blade in particular for use in a cutting tool of the foregoing kind as well as a cutting tool housing, in particular for use on a cutting tool of the foregoing kind. The invention further concerns a method of changing an interchangeable blade. 
     Cutting tools of that kind generally have a housing and a blade which is replaceable. The housing serves, on the one hand, to hold the blade and, on the other hand, to grip the cutting tool so that it can be guided with the hand. In principle a distinction can be drawn between two different kinds of cutting tool with interchangeable blades, more specifically on the one hand cutting tools with strip steel blades which for resharpening or resetting have a strip steel blade having a plurality of segments. The blade can be pushed out of the housing and, at the front thereof, individual segments which have become blunt can be separated off so that a sharp blade for cutting purposes is always available. On the other hand, there are also cutting tools which have a non-segmented blade which is replaceable as a whole. Such a cutting tool is disclosed for example in International patent application WO 2012/019589 A2 to the present applicant. 
     A disadvantage with cutting tools in which only the blade is replaceable as a whole is that the replacement operation is generally time-consuming and can only be performed with the aid of a tool like, for example, a screwdriver. 
     SUMMARY 
     Therefore, the object of the present invention is to provide a cutting tool of the kind set forth in the opening part of this specification as well as an interchangeable blade, a cutting tool housing and a method of the kind set forth in the opening part of this specification, by means of which replacement of an interchangeable blade is substantially simplified, and in particular can be carried out in a shorter time and without an additional tool. 
     The object of the invention is attained by a cutting tool having a housing and at least one interchangeable blade which is arranged at a holding portion of the housing, and the cutting tool has a locking member arranged moveably on the housing for locking the blade to the housing, wherein the housing has first positively locking elements and the locking member has second positively locking elements which jointly lock the blade in a given position on the housing. For that purpose, the housing has preferably at a front end a holding portion at which the blade is held and locked by means of the locking member and a rear gripping region at which the cutting tool can be gripped and guided by a user. When the blade is locked, it is locked or fixed in a given position on the housing and, accordingly, cannot be removed. If, in contrast, the blade is not locked by the locking member, the blade can be removed and can thus be replaced by a fresh blade. 
     Preferably, the locking member is arranged at or in the housing in such a way that it is actuable by a user from outside the housing. 
     That substantially simplifies replacing an interchangeable blade. There is no need for a screwing-on operation or the like in respect of the housing, but rather the locking member is only to be moved relative to the housing in such a way that it does not lock the interchangeable blade and the interchangeable blade is removable. A fresh blade can then be arranged and the locking member can in turn be moved relative to the housing so that it locks the blade in a given position to the housing. That substantially simplifies changing the interchangeable blade, which is possible in a shorter time and also more safely. 
     In a first preferred embodiment, the locking member is reciprocatingly movable between a first position in which the blade is locked and a second position in which the blade is released. Particularly preferably, the locking member is mounted pivotably to the housing. Thus, the blade can be released or locked by pivoting the locking member. Alternatively, the locking member is reciprocatingly movable with a translatory movement between the positions on a straight path of movement. Other paths of movement can also be advantageous and preferred. If the locking member is arranged pivotably between the first and second positions, then actuation of the locking member on the one hand is particularly simple, while on the other hand that also substantially prevents unwanted actuation. 
     In a further preferred embodiment, the locking member is arranged on a rotational lever mounted pivotably to the housing. That provides on the one hand that the locking member can be particularly easily actuated while on the other hand only a low force is to be applied to the rotational lever by the user to move the locking member into the first position and to move it out of that position into the second position to lock or release the blade. That further simplifies operation. Insofar as it is possible with the locking member to apply to the interchangeable blade a force which is greater in comparison with actuation, this arrangement also provides that the interchangeable blade is securely held to the housing. That also improves the safety aspect of the entire cutting tool. 
     In that respect, it is preferred that the rotational lever is arranged in the first position substantially within the housing. As a result, it forms substantially one unit from the outside with the housing and preferably does not project from the housing which would be a nuisance. Preferably, the rotational lever is pivoted out of the housing in the second position of the locking member and is sunk substantially in the housing in the first position. In that way, a user can also always easily sense by visual means and by touch, the position in which the locking member is disposed and can thus ascertain whether the blade is locked or released. 
     In a preferred development, provided on the rotational lever is a blade storage means for receiving at least one substitute blade. Particularly preferably, the substitute blade can be removed from the blade storage means in the second position of the rotational lever. That makes replacement of the interchangeable blade even easier. When the rotational lever is in the second position, the locking member is also in the second position and the interchangeable blade is not locked and can accordingly be removed. The user can now easily remove the fresh blade from the blade storage means and arrange it on the cutting tool in such a way that it is again lockable by means of the locking member by the rotational lever being pivoted into the first position. The replaced blade can, for example, be disposed of or can be inserted into the blade storage means by the user. That also improves the safety aspect as the arrangement affords a safe place for stowing the replaced blades and they do not have to be put, for example, into a trouser pocket or the like. 
     It is further preferred that the rotational lever has a snap hook and the housing has a holding slot into which a nose of the snap hook engages in the first position of the rotational lever to arrest same relative to the housing. The rotational lever cannot be released readily, that is to say only intentionally, from the housing, and pivoted. In addition, arresting the rotational lever in position by means of a snap hook is a particularly simple arresting option whereby replacement of the blade is further simplified. That also further improves and simplifies the construction and the production of the cutting tool. 
     In a further preferred embodiment, the blade has a blade head having a cutting edge and a blade foot, wherein provided at the blade foot are positively locking elements for positively lockingly cooperating with the positively locking elements of the housing and the locking member. In that way, the blade can be particularly well locked to the housing by means of the locking member and the cutting edge is free and is overall available for the cutting operation. 
     Preferably, the locking member as the positively locking element has at least one nose which engages into an opening on the blade for locking the blade. In particular, the nose of the locking member engages into an opening on the blade foot or into an opening between the blade head and the blade foot. It is further preferred that the housing as the positively locking element has at least one projection which engages into an opening on the blade. In particular the projection on the housing engages into an opening at the blade foot or into an opening between the blade head and the blade foot. In that way, the blade can be positively arrested to the housing or the locking member in a particularly simple fashion, and locked by means of the locking member. 
     In a preferred development in that case, the two openings at the blade foot are arranged in mutually opposite relationship and jointly define a hammerhead-like region, that can be engaged behind, of the blade. Because the two openings are arranged in mutually opposite relationship and jointly define a region which can be engaged behind and which is preferably of a waisted configuration, the blade can be particularly effectively arrested on the housing and locked by means of the locking member. On the one hand, that improves the safety aspect, while on the other hand replacement is also simplified. 
     In a further preferred embodiment, the blade has a flat abutment which bears against a corresponding abutment on the housing so that cutting reaction forces are transmitted into the housing. That further improves the safety aspect of the cutting tool. In the cutting operation, high cutting reaction forces can sometimes occur, which have to be absorbed in the housing and which then have to be counter-supported by the user. If the cutting reaction forces act on the blade in that way, it is preferable for them to be transmitted into the housing by way of the flat abutment and the corresponding abutment on the housing so that not all cutting reaction forces have to be carried by the positively locking elements of the housing and the locking member. That also further simplifies the structure. 
     In a further preferred development, the positively locking elements of the blade cooperate with the positively locking elements of the housing and the locking member in such a way that substantially no moments are introduced into the rotational lever by virtue of cutting reaction forces. Preferably, no moments which force the rotational lever into the second position are applied thereto. It can however be preferred for moments to be applied to the rotational lever, which urge it into or hold it in the first position. That further improves the safety aspect of the cutting tool. Unintentional release of the locking member and thus release of the blade by virtue of cutting reaction forces are prevented. 
     In a further preferred embodiment of the cutting tool, the cutting edge is oriented substantially perpendicularly to a longitudinal axis of the cutting tool. Preferably in that case, the cutting edge faces rearwardly, that is to say in the direction of the gripping region of the housing. By means of such an orientation of the blade or the cutting edge, the cutting tool is suitable for particularly well severing flat materials. For example, the cutting tool is to be applied to a distal end, as viewed by the user, of a material to be cut, and is then to be pulled in the direction of the user towards the proximal end of the material in order to completely sever it. The present invention can be particularly advantageously used with such cutting edge orientations as, with such a blade orientation, the use of strip steel blades with separable segments is only limitedly possible. 
     Preferably, the blade head has a holding portion for engaging into the housing and a guide portion for guiding material to be severed, wherein the cutting edge is arranged between said two portions. In that way, material to be severed is guided by that guide portion towards the cutting edge so that severing of the material is even more easily possible. That further simplifies handling of the cutting tool. 
     Preferably, the guide portion is substantially skid-shaped. Preferably, the skid-shaped guide portion is of a rounded-off or beak-shaped configuration. In that way, the material to be severed can particularly well slide on the guide portion and be guided towards the cutting edge. For that purpose, preferably, the guide portion has a substantially bend-free guide surface. In that way, the material to be severed is further treated carefully and it is possible to achieve a clean cut. 
     It is further preferred that the guide portion and the housing and/or the holding portion jointly form a guide passage for feeding the material to be severed to the cutting edge. Preferably, the guide passage enlarges away from the cutting edge. In that way, the material to be severed is even better guided on to the cutting edge whereby a clean severing cut and safe operation are possible. The fact that the guide passage is defined, on the one hand, by the housing and, on the other hand, by the guide portion of the blade means that a width of the guide passage can be suitably adjusted by replacement of the blade by a blade of another geometry. Thus, the cutting tool can be easily adapted to different cutting situations like, for example, different material thicknesses of material to be severed. 
     In a further aspect in an interchangeable blade of the kind set forth in the opening part of this specification, in particular for use in a cutting tool according to one of the above-described preferred embodiments, the invention attains the above-stated object in that the interchangeable blade has a blade head which has a holding portion for engagement into a housing of a cutting tool and a cutting edge, and also a blade foot which is in the form of a hammerhead-like projection and defines two openings on the blade for positively lockingly cooperating with a housing of a cutting tool and/or a locking member of a cutting tool. Such an interchangeable blade can be easily arranged on the cutting tool as also already described hereinbefore in connection with the cutting tool, and locked to the housing by means of the locking member. Handling of the cutting tool and replacement of the blade are substantially simplified and more safely possible. It is to be appreciated that the interchangeable blade as well as the cutting tool with the interchangeable blade have a large number of common aspects as are to be reflected in particular in appendant claims. In that respect, reference is directed in its full entirety to the foregoing description and the advantages of the cutting tool. 
     In a preferred development of the interchangeable blade, it has a guide portion for forming a guide passage together with the holding portion and/or a housing of a cutting tool, the cutting edge being arranged between the holding portion and the guide portion. The guide portion is accordingly provided on the interchangeable blade. When severing flat material, the guide portion generally bears against it and guides the material towards the cutting edge. In that way, the guide portion is subjected to a certain wear. Because the guide portion is arranged at the interchangeable blade and not the housing, it is replaced together with the interchangeable blade when the latter is blunt. That prolongs the service life of the cutting tool, in particular of the housing, and there is always an unworn guide portion, whereby a clean cut can be produced. 
     In a further aspect of the invention, the above-stated object is attained by a cutting tool housing of the kind stated in the opening part of this specification, in particular for use in a cutting tool according to one of the above-described preferred embodiments, comprising a holding portion for receiving an interchangeable blade, in particular an interchangeable blade according to one of the above-described preferred embodiments of an interchangeable blade, and a locking member arranged movably on the housing for locking the blade to the housing, wherein the housing has first positively locking elements and the locking member has second positively locking elements which jointly lock the blade in a given position in the housing. By means of such a cutting tool housing, replacement of blades is possible in a particularly simple fashion, as described in particular hereinbefore in connection with the cutting tool with an interchangeable blade. It is to be appreciated that the cutting tool housing and the cutting tool described in the opening part of this specification with interchangeable blade have a large number of common aspects as are reflected in particular in appendant claims. In that respect, attention is directed in its full entirety to the foregoing description and the advantages. 
     In a further aspect of the invention, the object set forth hereinbefore in regard to a method of changing an interchangeable blade of a cutting tool, in particular a cutting tool in accordance with one of the above-described preferred embodiments of a cutting tool is attained by the steps: moving a locking member into a second position to release an interchangeable blade; pulling the blade out of a housing of the cutting tool; inserting a fresh blade into the housing; and moving the locking member into a first position to lock the blade in a given position to the housing. Preferably, the movement of the locking member includes a rotation of the locking member, in particular a rotation of a rotational lever, the locking member being arranged on the rotational lever. In a further preferred development, the movement of the locking member includes a rotation of a blade storage means, the locking member being arranged on the blade storage means. It is to be appreciated that the method of changing an interchangeable blade has a large number of common aspect with the cutting tool described hereinbefore; in that respect attention is directed in its full entirety to the foregoing description and the advantages specified therein. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The invention is described in greater detail hereinafter by means of an embodiment by way of example with reference to the accompanying Figures. 
         FIG. 1  shows a side view of a cutting tool in the condition of readiness for operation. 
         FIG. 2  shows a side view of the cutting tool with the rotational lever in the second position. 
         FIG. 3  shows a side view of the cutting tool with the rotational lever in the second position and the blade removed. 
         FIG. 4  shows a side view of the cutting tool with the rotational lever in the second position and the arranged blade and with the housing opened. 
         FIG. 5  shows the cutting tool of  FIG. 4  with blade removed. 
         FIG. 6  shows the cutting tool of  FIG. 4  with the rotational lever pivoted into the first position. 
         FIG. 7  shows the cutting tool of  FIG. 5  with the rotational lever pivoted into the first position. 
         FIG. 8  shows a side view of the rotational lever with interchangeable blade. 
         FIG. 9  shows a side view of the interchangeable blade. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a cutting tool  1  has a housing  2  which can comprise two mirror-symmetrical housing halves that are arranged against each other. The housing  2  has a gripping portion  4  at which a user can grip the cutting tool  1  and guide it for severing material, as well as a holding portion  6  at which an interchangeable blade  8  is arranged. The interchangeable blade  8  has a cutting part  10  with a cutting edge  12 , which in this embodiment is oriented substantially perpendicularly to the longitudinal axis A of the cutting tool  1  and, more specifically, rearwardly, that is to say in the direction of the gripping portion  4 . For severing flat material, therefore, the cutting tool  1  is to be guided with the longitudinal axis A substantially parallel to that material and is to be pulled, for example, from a distal end of a material to be severed, as viewed from the user, towards the proximal end of the material, in order to sever it. 
     The blade  8  has a blade head  14  that at least partially projects from the housing  2  at the holding portion  6 . The cutting part  10  is at least partially engagingly fitted into a plastic body  16  in the region of the blade head  14 . The cutting part  10  itself is preferably made from a blade steel. Because the cutting part  10  is fitted into the plastic body  16 , outwardly projecting edges are enclosed, like in particular the blade tip of the cutting edge  12  which in this embodiment is engagingly fitted in a guide portion  18  of the blade, that is formed by the plastic body  16 . That substantially reduces the risk of injury by the cutting tool  1  and improves safety. At the same time, the guide portion  18  together with a guide portion  20  of the housing  2  forms a guide passage  22  for feeding material to be severed to the cutting edge  12 . Because the guide passage  22  is defined on the one hand by the guide portion  20  of the housing  2  and the guide portion  18  of the blade  8 , a width of the guide passage  22  can be adjusted by exchanging the blade  8  for a blade with a longer cutting edge  12 . In that way, the cutting tool  1  can be easily adapted to different cutting situations like for example different thicknesses of material to be severed. 
     In addition,  FIG. 1  shows an upper edge of the rotational lever  30  at the upper end of the housing  2  and a gripping portion  32  for gripping and rotating the rotational lever  30 . The gripping portion  32  is placed into the housing  2  in such a way as to project slightly thereon, and can be gripped and moved, for example, with a fingernail. Preferably, the gripping portion  32  is colored so that a user can easily see how the cutting tool  1  is to be operated. 
       FIGS. 2 and 3  again show the cutting tool  1  as in  FIG. 1 , but with the rotational lever  30  in the second position, that is to say pivoted out of the housing  2 . 
     The rotational lever  30  has a snap hook  34  by which the rotational lever  30  can be arrested to the housing  2 . The rotational lever  30  also has a blade storage means  36  in which an interchangeable blade  8 ′ is arranged (see  FIG. 2 ). The blade storage means  36  is in the form of a recess  37  of a contour substantially corresponding to the external contour of a blade  8 ,  8 ′. In addition, arranged in the recess  37  is an aperture  38  so that the operator of the cutting tool  1  can push the interchangeable blade  8 ′ arranged in the blade storage means  36  out of the recessed region  37 , by its passing from the side of the rotational lever  30 , that is opposite to the blade storage means  36 , through the aperture  38 , for example with a finger. As can be seen in particular from  FIG. 3 , the blade  8  can be removed from the holding portion  6  in the second position of the rotational lever  30 . In the second position of the rotational lever  30 , accordingly, the blade  8  is released and can be replaced. 
       FIG. 4 through 7  show the cutting tool  1  with the housing  2  opened, so that in particular the locking member  40  as well as the positively locking elements of the locking member  40  and of the housing  2  and thus the mode of operation of locking and release of the blade  8  can be seen. While in that respect the rotational lever  30  and thus also the locking member  40  are in the second position in  FIGS. 4 and 5 , the rotational lever  30  and the locking member  40  are in the first position in  FIGS. 6 and 7  so that the blade is locked in a given position to the housing  2 . 
     The rotational lever  30  has a mounting portion  31  (see in particular  FIG. 4 ) with which the rotational lever  30  is mounted pivotably to the housing  2  at a pivot mounting  39 . The pivot mounting  39  can include, for example, a cylindrical projection in the housing and the mounting portion  31  of the rotational lever  30  can have a cylindrical aperture so that the rotational lever  30  is mounted pivotably to the housing  2 . 
     The rotational lever  30  is connected to the locking member  40  by way of the mounting portion  31 . The locking member  40  is arranged on the rotational lever  30  at the end opposite to the gripping region  32  of the housing  2 . In this embodiment, the locking member  40  has a nose  42  as the positively locking element  42 . In the first position of the locking member  40  or the rotational lever  30  (see  FIG. 6 ), the nose  42  engages into a corresponding opening  48  on the blade  8  or the blade foot  15 . 
     Provided at the side of the holding portion  6  of the housing  2 , that is in opposite relationship to the cutting edge  12 , are a plurality of positively locking elements  23 ,  24 ,  26 ,  28 . Reference  24  denotes a projection, reference  26  denotes a straight opening and reference  28  again denotes a projection which also forms an abutment for the blade foot  15 . The projection  24  engages (as can be seen in  FIG. 4 ) into a corresponding opening  44  at the blade foot  15 . A hammerhead-like holding portion  46  which can be engaged behind is formed by the two oppositely disposed openings  44 ,  48  on the blade foot  15 . The holding portion  46  has two oppositely disposed cantilever projection portions  46   a,    46   b  (see  FIG. 9 ). In this case, the projection portion  46   a  is substantially of a right-angled and straight and slightly angled configuration so that it can be inserted into the straight opening  26  on the housing  2 . The straight opening  26  is defined by the projection  24  and the projection  28  on both sides. The projection portion  46   b  has the nose  42  engaging therebehind in the first position of the locking member  40  so that the blade  8  overall is locked in a given position relative to the housing  2 . The abutment  23 , which in this embodiment forms a right-angled wall on the housing  2 , serves as an abutment for the flat abutment  45  (see  FIG. 9 ) of the blade  8  and crucially carries the cutting reaction forces which act on the cutting edge  12 . In addition, cutting reaction forces are applied to the nose  42  and thus the locking member  40  substantially on an operative axis extending through the pivot mounting  39  so that the rotational lever  30  is not urged into the second position. Cutting reaction forces are also transmitted by way of the projection portion  46   a  to the projection  24  and the projection  28 . 
     As can be seen in particular from  FIG. 4 , it is easily possible in the second position of the rotational lever  30  in which the locking member  40  is also in the second position and the nose  42  is not engaging into the recess  48  but rather releases the blade  8 , for it to be removed from the housing  2 , in particular by being pulled out of same, for example downwardly in the direction of the projection  24  in relation to  FIG. 4 . 
     To insert a blade  8  into the cutting tool  1  or into the housing  2 , the procedure is accordingly to be as follows: firstly the rotational lever  30  is to be moved into the second position (as shown in  FIGS. 4 and 5 ) and then a blade is to be fitted into the holding portion  6  of the housing  2  so that the projection portion  46   a  engages into the opening  26 , the projection  24  engages into the opening  44  and the flat abutment  45  bears against the abutment  23 . The rotational lever  30  is then to be pressed down or moved into the first position whereby the locking member  40  is also moved into the first position and the nose  42  engages into the opening  48 . The rotational lever  30 , the locking member  40  and the nose  42  are then in the position as shown in  FIGS. 6 and 7 . 
     The present embodiment only shows a cutting tool  1  in which the cutting edge  12  is oriented perpendicularly to the longitudinal axis A of the cutting tool  1  and which has a guide passage  22  for material to be severed. It is to be appreciated however that the invention is not limited to such cutting tools but rather can also be used in relation to cutting tools with blades having a cutting edge which extends substantially parallel to the longitudinal axis A and in which the blade tip or the cutting edge tip is exposed.