Patent Document

TECHNICAL FIELD 
     This invention relates to bending brakes and more particularly to the means for retaining and locking the working tools used by these brakes. 
     BACKGROUND ART 
     Bending brakes generally comprise a structure supporting two vertically-positioned substantially coplanar opposing toolplates, of which one can move vertically. 
     To the facing edges of the toolplates are fixed the means for retaining and locking the punch and die respectively, each of these being formed from a plurality of tools aligned in succession, they having the same shape but different lengths. 
     The modular means for retaining and locking the tool are fixed to the respective toolplates by known means, and are arranged to receive the tool shank in a manner enabling it to be slid along an axis parallel to the toolplate edge and be locked in the desired position. 
     When the type of work changes, one or more tools have also to be changed, this being generally done by withdrawing or inserting the tools laterally from or into the respective retention and locking means in the direction of the edge of the metal sheet. 
     Withdrawing, adding or changing a tool is a particularly delicate and even dangerous operation, particularly with regard to the upper tools, which can also be very long and heavy. 
     For this reason, tool retention and locking means have been developed for bending brakes which enable the tool to be withdrawn vertically, in the brake working direction. 
     These known means are rather complicated because they have to utilize safety means to prevent the tool from falling down when it is released. 
     Equipment known in the art, comprising said tool retention and locking means, is fully described in EP 0494714, in which the tool retention and locking means includes a lower channel into which the upper portion of the tool, also known as the shank, is inserted. 
     The tool can be inserted from below into a seat having the same form as the shank, and locked in position by a plurality of pneumatically operated pistons which enter a longitudinal groove provided in the tool shank. Each of these devices also has a safety device which includes a lever-operated peg which is movable within a hole in the retention means so that when the shank has been inserted into the seat in the retention and locking means, is maintained elastically inserted in a longitudinal cavity provided in one of the vertical walls of the seat. 
     At this point the tool can be withdrawn in the direction of the sheet edge or, by pressing the lever, can be withdrawn in the vertical direction. 
     This solution is costly to implement, and in addition the peg present in the safety device is easily damaged during use, rendering it unable to perform its safety function. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to overcome the aforementioned drawbacks within the framework of a rational, reliable and low-cost solution. 
     A further object of the invention is to provide tool retention and locking means which can be used easily and safely by the operator. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention attains these and further objects by virtue of a modular tool retention and locking element having the characteristics defined in the claims. To better clarify the constructional and operational characteristics of the invention three preferred embodiments thereof are described hereinafter by way of non-limiting example and are illustrated on the accompanying drawings. 
     FIG. 1 is an isometric schematic view of that brake portion on which the device of the present invention is mounted. 
     FIG. 2 is a front view of the intermediary of FIG.  1 . 
     FIG. 3 is a section on the line III—III of FIG.  2 . 
     FIG. 4 is a section on the line IV—IV of FIG.  3 . 
     FIG. 5 is a section on the line V—V of FIG.  2 . 
     FIG. 6 is an isometric view of a second embodiment of the invention. 
     FIG. 7 is a front view in the direction VII of FIG.  6 . 
     FIG. 8 is a section on the line VIII—VIII of FIG.  7 . 
     FIG. 9 is a section on the line IX—IX of FIG.  7 . 
     FIG. 10 is a section on the line X—X of FIG.  7 . 
     FIG. 11 is a section on the line XI—XI of FIG.  8 . 
     FIG. 12 is an isometric view of a third embodiment of the invention. 
     FIG. 13 is a front view in the direction XIII of FIG.  12 . 
     FIG. 14 is a section on the line XIV—XIV of FIG.  13 . 
     FIG. 15 is a section on the line XV—XV of FIG.  13 . 
     FIG. 16 is a section on the line XVI—XVI of FIG.  15 . 
     FIG. 17 is a schematic view of a detail of the invention. 
     FIG. 18 is a side view of a variant of the third embodiment of the invention. 
     FIG. 19 is a section on the line XIX—XIX of FIG.  18 . 
     FIG. 20 is an exploded detail of said variant of the third embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The figures show the movable upper toolplate  2  of a sheet metal bending brake, which carries there below a series of aligned tools  4  having the same shape but different lengths, and forming overall the punch of the brake. Likewise the lower toolplate of the brake carries a series of usual counter-tools which do not concern this description and are therefore not shown. 
     In detail, the tools  4  forming the punch are secured to the respective toolplate  2  by a series of aligned intermediary members  6 , known hereinafter simply as intermediaries, which are in mutual contact. 
     The intermediaries  6  are fixed to the respective upper and lower toolplates by usual means. 
     In the first embodiment shown in FIGS. 1 to  5 , each intermediary comprises a central body  7  provided upperly with a salient lateral flange  71  for fixing the intermediary to the brake toolplate (FIG.  4 ). 
     In an opposite position to the position of the flange  71 , the central body comprises along its entire length a lower portion  72  and an intermediate portion  73 , which is wider than the portion  72 . 
     At the base of the portion  73  two symmetrical milled recesses  74  (FIG. 5) are provided equidistant from the center of the central body and perpendicular to the axis of the intermediary  6 , each of them receiving a bar  75  maintained in position by a central pin  76  of length equal to the length of the central body  7  and locked in position by a central setscrew  77 , as shown in FIG.  4 . 
     To the ends of each bar  75  there are hinged two symmetrical profiled jaws  81  and  82  which with the portion  72  of the body  7  define two symmetrical seats for receiving the shank of a tool. 
     Each jaw has at its end a raised edge  800 , the connection surface  801  of which is inclined, and which defines a channel in which the longitudinal tooth  802  of the shank of the tool  4  is positioned, as shown in FIG.  4 . 
     The profiled jaws are hinged to the respective bars by pins  78  of length equal to the length of the body  7 , and maintained in position by a central setscrew  79 . 
     Above the pin  76  the body  7  receives a profiled rotatable shaft  9 , positioned through the center of the portion  73 . 
     In proximity to its ends, the shaft  9  comprises two pairs of parallel milled cavities facing two through holes  92  in the body  7  having their axis perpendicular to the axis of the shaft  9 . 
     Each hole  92  receives, on one side of the shaft  9  and the other, a cup-shaped piece  93  the base of which rests against that milled recess  91  which faces it. 
     Each cup-shaped piece receives a pack of spring washers  94  through which a profiled pin  95  with a large head is inserted. 
     At its center, the shaft  9  presents a circumferential groove  96  extending through about 110° and receiving a stop piece  97  inserted through a hole in the body  7 . 
     It should be noted that in certain embodiments of the invention, the circumferential groove can conveniently extend through a different angle. 
     The upper portion of each of the jaws  81  and  82  is shorter, as can be seen in FIGS. 2 and 3. 
     In said portion there is provided an elongate cavity closed by a cover  83  provided with two projecting pins  84  which extend into the cavity. 
     Between the pins  84 , acting as stop pins, there is positioned a spring  85 , the purpose of which will be apparent hereinafter. 
     In an opposite position to the cover, each jaw has a slot  86  extending along its entire length, to movably receive a latch  100  comprising two opposing pairs of stop pins  101  which, when the latch is within the groove, lie respectively at the ends of the spring  85  (FIG.  4 ). 
     The latch  100  is therefore free to undergo movement in both directions, being always returned into a central position by the spring  85 . 
     The movements of the latch  100  are produced by the operator acting on its bent ends  103 . 
     The latch  100  is retained in the groove  101  by a central plate  104  (FIG. 4) screwed to the respective jaw  81 ,  82  by two fixing screws  105 . 
     To the sides of the plate  104  the latch  100  comprises two abutments  106  facing the large-headed pins  95  inserted through the spring washers  94 , as shown in FIG.  5 . 
     When the latch is in its central rest position, rotation of the shaft  9  through 110° causes the cup-shaped pieces  93  to emerge, the large-headed pins  95  consequently elastically acting on the abutments  106  to rotate the jaw about the pins  78  and clamp the tool. 
     When the latch  100  is moved from this position, the abutments  106  no longer lie in front of the large-headed pins  95 , so that the jaw can no longer be urged into its closed position, and moreover is free to open completely by rotating in the opposite direction, to enable the tool to be withdrawn from below. 
     The second embodiment of the invention is shown in FIGS. 6 to  11 , in which elements corresponding to those of FIGS. 1 to  5  are indicated by the same reference numerals. 
     In the second embodiment, each intermediary  6  comprises a central body  7  provided upperly with a salient lateral flange  71  for fixing the intermediary to the brake toolplate. 
     In an opposite position to the position of the flange  71 , the central body comprises along its entire length a lower portion  72  and an intermediate portion  73 , which is wider than the portion  72 . 
     At the base of the portion  73  two symmetrical milled recesses  74  are provided equidistant from the center of the central body and having their axis perpendicular to the axis of the intermediary  6 , each of them receiving a bar  75  maintained in position by a central pin  76  of length equal to the length of the central body and locked in position by a central setscrew  77 . 
     To the ends of each bar  75  there are hinged two symmetrical profiled jaws  81  and  82  which with the portion  72  of the body  7  define two symmetrical seats for receiving the shank of a tool. 
     The profiled jaws are hinged to the respective bars by pins  78  of length equal to the length of the body  7 , and maintained in position by a central setscrew  79 . 
     The portion  73  comprises two through holes  210  in proximity to its ends, in positions symmetrical about its center (FIG.  8 ). 
     Each hole  210  receives two identical guide pieces  211  arranged symmetrical to each other, and prevented from escaping from their respective hole by a locking ring  212 . 
     In the inside of each guide piece  211  there slides a piston having an end head  213  and a wide base  214 . 
     The base  214  of the two aligned pistons is maintained against a snap ring  215  located in a groove positioned at the centre of the hole  210 , but can freely move a certain distance towards the outside of the hole. 
     A compression spring  216  positioned between a shoulder on the guide piece  211  and the wide base  214  of the piston maintains this latter in said position as shown in FIG.  10 . 
     The body  7  has a through conduit  220  which intersects the axis of the holes  210  at the snap ring  215  against which the piston bases  214  rest. 
     Feed and shut-off means for a pressurized fluid (oil) are provided at the ends of the conduit  220 , these not being shown as they are easily implemented by an expert skilled in the art. 
     The jaws  91  and  92  are provided with the same means as in the first embodiment, to the detailed description of which reference should be made. 
     Their operation is also very similar to the first embodiment. 
     Feeding the pressurized fluid to the conduit  220  causes the pistons  212  to emerge so that they act on the abutments  106  of the latch  100 . 
     Said action causes the jaw to rotate about the pins  78 , with consequent clamping of the tool. 
     When the latch  100  is moved, the abutments  106  no longer lie in front of the heads  213 , hence the jaw is not only no longer urged towards its closed position but is free to open completely by rotating in the opposite direction. 
     From the a foregoing it will be apparent that when the latch  100  is in its central rest position and the shaft  9  or the pistons  212  are also in their rest position, the tool is supported by the modular support element without being clamped, and hence can be withdrawn from the modular element by sliding it in a horizontal direction. 
     When the latch  100  is moved from its rest position, the jaws can be moved further apart to enable the tool to be withdrawn from below. 
     In contrast, when the latch is in its rest position and the shaft  9  or the pistons  212  are operated, the tool is clamped in its working position. 
     The third embodiment of the invention is shown in FIGS. 12 to  17 , in which elements corresponding to FIGS. 1 to  5 , which show the initially described embodiment of the invention, are indicated by the same reference numerals. 
     In the third embodiment each intermediary  6  comprises a central body  7  provided upperly with a salient lateral flange  71  for fixing the intermediary to the brake toolplate. 
     In an opposite position to the position of the flange  71 , the central body comprises along its entire length a lower portion  72  and an intermediate portion  73 , which is wider than the portion  72 . 
     With reference to FIG. 16, at the base of the portion  73  two symmetrical milled recesses  74  are provided equidistant from the centre of the central body and having their axis perpendicular to the axis of the intermediary, each of them receiving a bar  75  maintained in position by a central pin  760  locked in position by a central setscrew  761 . 
     To the ends of each bar  75  there are hinged two symmetrical profiled jaws  300  and  301  which with the portion  72  of the body  7  define two symmetrical seats for receiving the shank of a tool. 
     The profiled jaws  300  and  301  are hinged to the respective bars  75  by pins  780 , each of which is locked in position by a setscrew  790 . 
     Above the central pin  760  the body comprises, in positions symmetrical about its centre, a longitudinal through hole  700  and three transverse through holes  701 ,  702  and  703 , the axes B, C, D of which are perpendicular to the axis A of the through hole  700 . 
     The axis C of the hole  701  coincides with the axis of transverse symmetry of the body  7 , the holes  702  and  703  being equidistant from said axis C. 
     Each end of the holes  702  and  703  receives a cup-shaped piece  93  receiving a pack of spring washers  94  through which a profiled pin  95  with a large head is inserted. 
     The base of said cup-shaped pieces  93  rests against a vertical cylinder  303  which is inserted into the fork-shaped end  304  of a cylindrical piece  305  received in the hole  700 . In detail, as shown in FIG. 17, from the crosspiece of said fork  304  there extends a cusp  306  the vertex of which is perpendicular to the inner facing faces of the arms  304 ′ of said fork  304 . The vertex of the cusp  306  is spaced from the free end of the arms  304 ′ of the fork  304 . 
     The hole  701  receives a shaft  307 , one end of which has a stem  308  which emerges from the body  7  to be fixed to an operating lever  309  for rotating said shaft  307 . At the hole  700  the shaft  307  has two parallel milled recesses, each of which receives the rear end of the cylindrical pieces  304  inserted into the hole  700 . 
     Into each end of the hole  700  there is screwed a plug  311  provided with two parallel threaded holes  312  equidistant from its centre. 
     Each of said holes  312  receives a roller  313  of horizontal axis having its front face resting against one of the vertical cylinders  303 . The rollers are retained in position by a rear setscrew  314  screwed into the hole  312 . 
     Each of the jaws  301  and  302  upperly comprises a central projection  315  and two lateral projections  316 . 
     The central projection  315  on the jaw  302  is provided with a hollow  317  for passage of the cylindrical stem  308  connecting the shaft  307  to the lever  309 . 
     The two lateral projections  316  have a through hole  319  with different sections  319 ′ and  319 ″, which receives a pin  318  about which a spring  320  is mounted. One end of the pin  318  emerges laterally from said projection  316  and is locked by a pin  321 . The opposite end of the pin  318  is enlarged to form a base for one end of the spring  320 , the other end of which rests on the base of the section  319 ′ of the hole  319 , as shown in FIG.  14 . 
     The enlarged ends of the two pins  318  are fixed by a screw  322  to one and the other end of a latch  323  having the same length as one of the jaws  301  or  302 . 
     The screws  322  also fix an external cover  324  to the jaw  301  and  302 . 
     The latch  323  is hence free to move in both directions, being always returned to its central rest position by the springs  320 . 
     From FIG. 14 it can be seen that the latch  323  is provided with two abutments  325  which when the latch  323  is in its rest position lie in front of the pins  95 . 
     The movements of the latch  323  are produced by the operator acting on its bent ends. 
     When the latch is in its central rest position, rotating the shaft  307  through 90° causes the pieces  305  to move and act on the cylinders  303 , so causing the cup-shaped pieces  93  to emerge and the large-headed pins  95  to act elastically on the abutments  325 , so that the jaws  301  and  302  rotate about the pins  780  with consequent clamping of the tool  4 . 
     To remove the tool  4 , the operator rotates the lever through 90°. after which he moves the latch  323 . In this manner the abutments  325  on the latch  323  no longer lie in front of the large-headed pins  95 , hence the jaws  301  and  302  are not only no longer urged towards their closed position but are free to open completely by rotating in the opposite direction, to enable the tool to be withdrawn from below. 
     FIGS. 18 to  20  show a variant of the third embodiment of the invention. In said figures, elements corresponding to those of 
     FIGS. 12 to  17 , which show the third described embodiment of the invention, are indicated by the same reference numerals. 
     This latter variant of the third embodiment of the invention differs therefrom in the means for rotating the jaws  301  in order to clamp and release the tool  4 . 
     In this variant, from the rear of the cup-shaped members  93  there branches a fork  330 , the arms  331  and  332  of which have a hole through which a cylinder  333  is inserted. Said cylinder  333  interferes with the conical end of a cylindrical element  334 , the other end of which rests on the base of two milled recesses  310  in the shaft  307 . 
     Two closure plugs  335  are inserted into the ends of the hole  700 . 
     In this case, when the operator rotates the shaft through 90° by means of the lever  309 , the cylindrical elements  334  are made to move and press against the lateral surface of the cylinders  333  to cause the cup-shaped pieces  93  and hence the large-headed pins  95  to move outwards. These latter rotate the jaws  301  and  302 , which clamp the tool in position. 
     To release the tool, the operator rotates the lever  309  in the reverse direction. In this manner the spring washers  94  retract the cup-shaped pieces  93  and the pins  95 , at the same time the cylinders  333  shifting the cylindrical elements  334 . 
     It should be noted that the invention can receive the tool  5  either from the front or the rear, and that although four possible versions of the invention all with two jaws have been described, it can also be usefully implemented with only one jaw.

Technology Category: 7