Abstract:
A toolholder unit for sheet metal bending brakes, comprising a bar ( 1 ) to be associated with a fixed or movable part of the brake, and provided with at least one recess ( 9 ) forming with a jaw ( 12 ) associated therewith a groove ( 11 ) to receive the shank ( 7 ) of the tool ( 5 ), there being provided elastic means ( 20 ) to maintain said jaw spaced from said recess and from the shank contained therein, and locking means to clamp said jaw against said shank, said locking means comprising: at least one slider axially slidable within a seat facing that side of the bar ( 1 ) facing the jaw; at least one appendix ( 175 ) projecting from said slider beyond that side of the bar facing the jaw; at least one cavity ( 21 ) provided in the bar ( 1 ), or in a part ( 2 ) rigid with it, to receive said appendix ( 175 ); and means ( 18 ) of variable profile to cause said slider ( 17 ) to undergo controlled translations relative to said bar ( 1 ).

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates in a totally general sense to presses for bending sheet metal, and more particularly to a fixing unit for the relative tools.  
         [0002]     For such work, bending brakes are known essentially comprising a bed and a crosspiece which are positioned respectively below and above a work station, and of which at least one is movable vertically.  
         [0003]     The bed carries a first tool, usually of female type, known as the die, the crosspiece carrying a second tool, usually of male type, known as the punch.  
         [0004]     The mutual position of the die and punch can be inverted with respect to the aforestated on the basis of particular operative requirements.  
         [0005]     Said die and said punch are of modular or sectional type, i.e. they comprise a series of sectors which can be fitted together to achieve the required working or bending length.  
         [0006]     For reasons of simplicity, express reference will be made hereinafter to the tool of punch type, which will be considered to be associated with the crosspiece, for example movable, of the brake, it being also understood that that to be stated is valid practically in total for the underlying tool of die type.  
         [0007]     The punch is known to be removably fixed to the crosspiece by way of a robust bar usually known as the adaptor.  
         [0008]     The adaptor is lowerly provided with a full-length groove of constant right-angled cross-section, to receive the fixing shank of the tool.  
         [0009]     Said adaptor is provided with fixing means acting transversely on the shank and arranged to assume two configurations, namely a rest and working configuration, corresponding to locking and release of the shank respectively.  
         [0010]     By many concerns, including the Applicant, said fixing means are operated manually with the aid of a lever implement which is removably associated with the adaptor.  
         [0011]     The use of said lever has proved unsatisfactory at least for the following reasons.  
         [0012]     Firstly, if inadvertently left on the adaptor, the lever can constitute a serious source of danger for operators in that it projects inconveniently beyond the outline of the adaptor.  
         [0013]     Secondly, said lever is hardly practical, seeing that at each tool change and/or adjustment it has to be engaged with and then removed from said fixing means.  
         [0014]     It can also happen, as indeed it has already happened, that the lever, once detached from the fixing means, is randomly left in an inadequate or unusual place, possibly together with materials and parts foreign to the operation underway, with the result that its finding is bothersome and represents a loss of time.  
       SUMMARY OF THE INVENTION  
       [0015]     The main object of the present invention is to provide a toolholder unit able to overcome the aforesaid problems within the context of a simple, rational, reliable, economical and practical construction of small overall size.  
         [0016]     Said object is attained by the means defined in the main claim.  
         [0017]     Preferred embodiments of the means proposed therefor are indicated on the dependent claims.  
         [0018]     The characteristics and constructional merits of the invention, together with its method of operation, will be apparent from the ensuing detailed description given with reference to the figures of the accompanying drawings, which illustrate a particular preferred embodiment thereof by way of non-limiting example. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is a perspective view showing the unit assembled.  
         [0020]      FIG. 2  shows the same unit in exploded view, with some parts omitted for reasons of clarity and simplicity.  
         [0021]      FIG. 3  is a view in the direction III of  FIG. 2 .  
         [0022]      FIG. 4  is the section IV-IV of  FIG. 3 .  
         [0023]      FIG. 5  is the section V-V of  FIG. 1 .  
         [0024]      FIG. 6  is the section VI-VI of  FIG. 2 .  
         [0025]      FIG. 7  is the view obtained in the direction VII indicated in  FIG. 1 , in a different operative configuration.  
         [0026]      FIG. 8  is a view totally similar to  FIG. 7 , in a different operative configuration.  
         [0027]      FIG. 9  is the view obtained in the direction IX indicated in  FIG. 8 .  
         [0028]      FIG. 10  is a view totally similar to  FIG. 9 , in a different operative configuration.  
         [0029]      FIG. 11  is a view obtained in the direction XI indicated in  FIG. 10 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]     Said figures, and in particular  FIGS. 1 and 2 , show a bar  1 , usually known as an adaptor, to be installed on a sheet metal bending brake, not shown for reasons of simplicity, and fixed thereto in known manner.  
         [0031]     In the illustrated example, the bar  1  is intended to be associated with the usually vertically movable crosspiece of said brake.  
         [0032]     Said bar  1  comprises a central core  2  which at its top presents a full-length salient lateral rib  3  for fixing said bar  1  to said crosspiece, and at its bottom presents a full-length descending central rib  4  against which the tool  5  is intended to be locked (see  FIGS. 7, 8  and  11 ).  
         [0033]     The tool  5  comprises ( FIG. 7 ) a lower blade or knife  6 , and an overlying shank  7  having, on one side, a full-length lateral groove  8 , and on the other side a step-shaped recess  9  intended to receive the rib  4  of the bar or adaptor  1 .  
         [0034]     In front of the rib  4  there is a clamping plate  10  positioned on the bar  1 , and which together with said rib  4  defines a groove  11  for receiving and locking the shank  7  of the tool  5 .  
         [0035]     Essentially the rib  4  and clamping plate  10  define a sort of clamp or gripper.  
         [0036]     It should be noted that the plate  10  is divided into several parts or jaws  12 , two in number in the illustrated example ( FIGS. 1, 2 ,  5 ,  9  and  10 ), and that the tool  5  is of modular or sectional type, i.e. it comprises a series of sectors usually of different length.  
         [0037]     The tool  5  and hence also the plate  10  can be arranged on one or the other side of the rib  4  as is easily apparent from  FIGS. 1, 2 ,  5 ,  7 ,  8  and  11 .  
         [0038]     Each jaw  12  is hinged to the core  2  of the bar  1  in the manner of a rocker arm.  
         [0039]     For this purpose it presents two side-by-side transverse holes  13  ( FIGS. 1, 2 ,  9  and  10 ) of different cross-sections ( FIGS. 7, 8  and  11 ) which receive with a certain radial slack two screws  14  which are screwed down into respective threaded holes  15  ( FIG. 2 ) in the core  2 , but are not tightened against the jaw  12 .  
         [0040]     Specifically, said screws  14  are of the spherical head type, i.e. they present at the base of their head a neck of curved cross-section which engages a matching cradle in the respective hole  18  ( FIGS. 7, 8  and  11 ).  
         [0041]     At the base of the jaw  12  there is a full-length internal anti-withdrawal tooth  16  arranged to engage a groove  8  in the tool  5  ( FIGS. 7-8 ).  
         [0042]     The jaw  12  is closed by a mobile assembly or slider, indicated overall by  17  in  FIGS. 2 and 5 , which is under the control of a unit indicated overall by  18  in  FIG. 2  and comprising an articulated operating lever  181 .  
         [0043]     The slider  17  comprises two identical profiled pieces  170  of T-shape ( FIG. 2 ) joined together by a screw  171  to form an H-shaped flat component ( FIG. 5 ).  
         [0044]     The crosspiece of said H profile is slidingly received, as an exact fit, in a longitudinally extending transverse slot  172  provided in the bar  1  ( FIG. 5 ), its arms lying in matching grooves  173  which extend along the sides of the core  2  and are connected together by said slot  172 .  
         [0045]     The outer faces of said arms are flush with the sides of the core  2  ( FIG. 5 ), at the end of each arm there being provided a through hole  174  into which a ball  175  of diameter exceeding the depth of the groove  173  is inserted as an exact fit.  
         [0046]     At the base of each side of the core  2  there is a series of cavities  19 , two for each jaw  12  ( FIG. 2 ), which house respective compression springs  20 .  
         [0047]     Said springs  20  press against the lower end of the jaw  12  such as to maintain the upper end of said jaw  12  constantly urged elastically against said ball  175 .  
         [0048]     In the inner face of the upper end of the jaw  12  there is also provided a cavity  21  intended to engage the ball  175  ( FIGS. 5, 8  and  11 ).  
         [0049]     The core  2  presents a longitudinal dead hole  176  lying between the grooves  173  ( FIG. 2 ) and traversing the slot  172  ( FIG. 5 ).  
         [0050]     A compression spring  177  is inserted into the bottom of said hole  176  to act against the crosspiece of said H profile of the slider  17 , into the opposite end there being inserted a pushrod  178  which is positioned between said crosspiece and the rear end of the lever  181  forming part of the unit  18 .  
         [0051]     The opposing ends of the pushrod  178  are convex ( FIG. 5 ).  
         [0052]     The lever  181  is hinged to the component  180  by a pin  182  positioned perpendicular to the bar  1 .  
         [0053]     The component  180  is in the form of a profiled plate, the lever  181  comprising a handgrip.  
         [0054]     The component  180  is hinged to one end of the core  2  by a pin  183  which is parallel to the bar  1 , from the core  2  there branching a second pin  184  ( FIGS. 1 and 2 ) which passes through an arched slot  185  provided in the component  180 .  
         [0055]     The centre of curvature of the slot  185  lies on the axis of the pin  183 , said slot  185  defining the range of rotation of the lever  181 .  
         [0056]     As shown in  FIGS. 3 and 4 , in that face of the component  180  facing the core  2  there is a cavity  186  with which the facing or proximal convex end of the pushrod  178  is arranged to engage ( FIG. 5 ).  
         [0057]     In plan view, the profile of the cavity  186  is bean-shaped (see  FIG. 3 ), its centre of curvature lying on the axis of the pin  183 , and its base providing an inclined surface ( FIGS. 4 and 5 ) for the sliding of said facing convex end of the pushrod  178 .  
         [0058]     To insert and extract the shank  7  of the tool  5  into and from the groove  11  of the adaptor  1  the following means are provided.  
         [0059]     In the upper part of each jaw  12  there is provided a longitudinal dead hole  22  ( FIGS. 2 and 6 ) from which two longitudinal slots indicated by  23  ( FIG. 2 ) and  24  ( FIG. 6 ) extend towards the upper edge and the inner face of the jaw  12  respectively.  
         [0060]     Starting from its base, each hole  22  houses, in succession, a pin  25 , a compression spring  26 , and a threaded abutment plug  27  ( FIGS. 2 and 6 ).  
         [0061]     The pin  25  presents a first  124  and a second  125  transverse peg which are slidingly inserted into the slots  24  and  23  respectively ( FIG. 1  and  FIG. 6 ).  
         [0062]     The first peg  124  ( FIG. 6 ) passes beyond the inner face of the jaw  12 , to be able to engage ( FIG. 11 ) the respective engagement seat  224  ( FIG. 2 ) of the core  2 , the second peg  123  carrying an operating head  223 .  
         [0063]     Finally, the head  223  presents a pointer  33  with which two reference marks  66  and  99  on the outer face of the jaw  12  correspond (FIGS.  9  an  10 ).  
         [0064]     The aforedescribed unit operates substantially as follows.  
         [0065]     When the tool  5  is working, the unit  18  with the articulated lever  181  is in its rest configuration shown in  FIG. 1 .  
         [0066]     Specifically, the component  180  and the lever  181  comprising the unit  18  lie at a right angle to each other; the hinge pin  182  between said two parts  180  and  181  is orientated vertically; and the handgrip of the lever  181  is positioned against the upper vertical band of the jaw  12  (see  FIGS. 1 and 5 ).  
         [0067]     In addition, the pushrod  178  of the slider  17  is in contact with a point of the plate  180  which is outside the cavity  186  ( FIG. 5 ), so that the balls  175  carried by the slider  17  lie outside the respective cavities  21  ( FIG. 5 ) and act against the jaws  12  in such a manner as to clamp them against the shank  7  which rests against the lower face of the rib  4  ( FIG. 7 ).  
         [0068]     At the same time the pointers  33  of the heads  223  are aligned with the reference marks  99  ( FIG. 9 ) by the effect of the springs  26  ( FIG. 6 ). If the tool  5  is merely to be loosened, for example to adjust its position along the groove  11 , the component  180  and the lever of the unit  18  are firstly aligned as shown in  FIG. 7 , and then rotated upwards.  
         [0069]     This rotation ( FIG. 8 ) of the lever  181  causes the cavity  186  to align with the pushrod  178  ( FIGS. 5 and 8 ), which slides towards the component  180  by the effect of the spring  177  ( FIG. 5 ), whereas the balls  175  of the slider  17  enter the cavities  21  ( FIG. 8 ), by which the jaws  12  open by the effect of the springs  20 .  
         [0070]     Said opening is not complete ( FIG. 8 ), but is limited by the pegs  124  which rest against the facing flat surface of the core  2 .  
         [0071]     By virtue of said limited opening, the shank  7  of the tool  5  slightly withdraws from the groove  11 , and remains hanging from the tooth  16  of the jaw  12  by virtue of its groove  8  ( FIG. 8 ).  
         [0072]     At this point the shank  7  can be adjusted along the groove  11 , evidently under conditions of maximum safety.  
         [0073]     If at least one part of the tool  5  has to be removed, then the operator using one hand makes the heads  223  approach to align the pointers  33  with the reference marks  66  ( FIG. 10 ), and with the other hand supports said at least one part of the tool from below.  
         [0074]     This mutual approach of the heads  223 , indicated by two opposing arrows in  FIG. 10 , results in compression of the springs  26  ( FIG. 6 ); insertion of the pegs  124  into the seats  224  ( FIG. 11 ) by the effect of the opening springs  20  for the jaw  12 ; and the consequent complete opening of the jaw  12 , to release the shank  7  as shown in  FIG. 11 .  
         [0075]     After the tool  5  has been subjected to whatever action is required, the operator proceeds in the reverse order to render it operative.  
         [0076]     Specifically, he supports the tool  5  with one hand while with the other hand he brings the pointers  33  into alignment with the reference marks  99 . To achieve said alignment, the lower end of the jaw  12  is pressed to overcome the thrust of the springs  20 , as indicated by two opposing arrows in  FIG. 11 , by which the springs  26  withdraw the pegs  124  ( FIG. 9 ) as soon as these latter emerge from the holes  224  ( FIG. 8 ). Having done this the lever  181  is rotated into the horizontal position of  FIG. 7 , by which the slider returns into the position of  FIG. 5 , where by means of the balls  175  it clamps the jaw  12  against the shank  7  ( FIG. 5 ).  
         [0077]     Finally the lever  181  is rotated through a right angle as shown in  FIGS. 1 and 5 .