PUNCHING AND SHEARING MACHINE WITH VARIABLE CUTTING ANGLE

Abstract: The machine includes a supporting frame (2) for a worktable (3) through which a C-shaped head (7) is vertically movable and is actuated by a fluidodynamic means (4) pivoted on the lower face (3a) of the worktable and is guided by a pair of vertical cylindrical and parallel columns (13), fixed to said worktable, and by a shaped slider (6) arranged below the worktable, the upper wing (7a) of said head supporting two blades (8) directed towards the worktable and mounted on two respective first upper sectors (9) which both rotate scissors-like abut a vertical axis, said worktable having horizontal lower counter-blades (10) also supported by two second respective lower sectors (11) which rotate about said vertical axis, there being means (12) for connecting said first upper sectors and said second lower sectors during rotation and means (18,23) for positioning and locking them once their position is reached said head being furthermore controlled by adjustable elastic elements (27) for adjusting the maximum value of force applicable to the first upper blades according to the thickness and to the mechanical resistance of the material being processed.

Description: The present invention relates to a punching and shearing machine with variable cutting angle. Punching and shearing machines are known having a structure essentially consisting of a box-like supporting frame. The actuation elements of the shearing parts are coupled to the frame so as to provide a set pivoting point for a good operation of the machines. For some workings these machines can furthermore be provided with a group of blades (upper and lower ones) to vary the cutting angle as required. The blades are mounted on supports rotating relatively to one another along arcs of circles. Finally, all shearing and punching machines share the common problem of defining the applicable shearing force and of keeping constant the required play between the upper blades and the lower blades, the extent of said play being always very limited and, indicatively, in any case of the order of tenths or hundredths of a millimeter. Known machines have considerable disadvantages as to their general construction: in fact they must necessarily be completely supported by the above described box-like structures, thus making maintenance and/or general and partial disassembly operations extremely complicated and troublesome. These known machines furthermore have mostly manually actuated devices for determining the applicable forces and for adjusting the play between the blades, their precision therefore depending on the experience of their operator. Finally, the devices for varying the cutting angle are constructively very complicated and are not easy to operate. GB-A-1 542 529 shows a shearing machine having a pair of C-frames extending in vertical planes and each having a first upper horizontal portion and a second lower horizontal portion connected to each other by a third vertical portion so as to define the C-shape. The free ends of the horizontal portions of the C-frames which are opposite to the third portions are hinged to a supporting main frame along a vertical axis, and hence the mutual angle between the C-frames is adjustable. Guides which are parallel to the C-frames hinge axis are provided on the upper horizontal portions, and supporting plates which support upper cutters are slidingly movable on such guides by means of actuating means. Fixed lower cutters are attached to the lower horizontal portions of the C-frames, and such lower cutters have cutting edges which are substantially coplanar with a backing plate support surface for a sheet material to be sheared. Adjusting means are provided for adjusting the angle between the C-frames. The aim of the present invention is to overcome the disadvantages of the known machines by providing a punching and shearing machine with variable cutting angle having a simple construction and being easy in maintenance, and which at the same time allows to define in a practically automatic manner the value of the forces applicable to the blades for the various punching and/or cutting operations and of the required micrometric plays according to the thicknesses of the materials being processed, and which finally allows to vary the cutting angle in a continuous manner and with a structure which is simple in concept but safe and reliable operation. This aim is achieved by a punching and shearing machine with variable cutting angle as defined in claim 1. Claims 2-7 concern preferential embodiments of the punching and shearing machine. Further characteristics and advantages of the invention will become apparent from the detailed description of a preferred but not exclusive embodiment of a punching and shearing machine with variable cutting angle, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a schematic and partially sectional side view of the machine; figure 2 is an equally schematic enlarged-scale and partially sectional side view of a detail of the C-shaped head and of the means for connecting said first upper sectors and said second lower ones; figure 3 is a plan view taken along the sectional plane III-III of figure 1; figure 4 is a detail top view of said coupling means related to a single second lower sector; figure 5 is a schematic and partially sectioned view of the machine according to a second aspect of the invention; figures 6 and 7 are enlarged partial sectioned views of two different embodiments of the means for regulating the blade force of the machine of figure 5. With reference to figures 1-4, the reference numeral 1 generally indicates a punching and shearing machine, with variable cutting angle, of the type comprising a box-like frame 2 for supporting a horizontal worktable 3 through which a C-shaped head 7 is vertically movable. The head 7 is actuated by conventional fluidodynamic means 4 pivoted on the lower face 3a of said worktable 3 and is guided by at least one pair of vertical cylindrical and mutually parallel columns 5 and by a shaped prismatic slider 6 arranged below said worktable. The upper extension 7a of said head has two downwardly directed blades 8 which are mounted on two respective first circular sectors 9 both of which rotate scissors-like about a vertical axis A. Also the worktable 3 has lower counter-blades 10 which are arranged horizontally and are supported by two second lower sectors 11 which rotate about said axis A coaxially to said first sectors. Between said first upper sectors 8 and said second lower ones 11, means 12 connect them only during their rotation; said means consist of at least one pair of vertical prismatic columns 13, each whereof is rigidly coupled to a respective first upper circular sector 9 and has a hollow seat 14, at a level below the worktable 3. A tab 15 engages the seat 14 and protrudes from the perimeter of a cylindrical head 16 rigidly associated with a support 17 which is in turn rigidly associated with means 18 for locking said second lower sectors 11 in position. Said means 18 comprises at least one pair of fluidodynamic cylinders 19 which are located below the worktable 3 in related seats 20; at the ends of the stems 19a there are articulations 21 to which the upper ends of respective rockers 22 are coupled, their lower opposite ends 22a being J-shaped, their horizontal portions 22b making contact with the lower face 3a of the worktable 3, in a locked position of the machine. Also the first upper sectors 9 have means 23 for locking in position once said position is reached, and said means essentially consist of respective vertical cylinders 24 associated with the extension 7a; related stems 25 protrude from said cylinders and support an arc-like flange 26 which is adapted to compress the first upper sectors 9 against the lower face of the extension 7a when the machine is in the working position. The head 7 has adjustable elastic means 27 for controlling the maximum applicable force and for automatically determining the play between the upper blades 8 and the lower counter-blades 10 according to the thickness of the material being processed and to its mechanical resistance. Said means consist of a group of helical compression springs 28 arranged horizontally in a pack-like configuration in related seats 29 and having corresponding ends directly in contact with the lower portion of the columns 5 and the opposite ends in contact with respective vertical plates 30 which are micrometrically horizontally movable on related guiding pins 31. The operation of the invention is as follows: if for example, a sheet of metal has to be sheared at an angle, the positions of the first upper sectors 9 and of the second lower sectors 11 are set, said sectors being completely separated from one another in the position of non-rotation. For this purpose, the fluidodynamic cylinders 19 are therefore first actuated, their stems 19a pushing the supports 17 and, consequently, the heads 16 and the related tabs 15 towards the hollow seats 14 until said tabs enter said seats with a consequent perfect insertion coupling. After said coupling, the first upper sectors 9 and the second lower ones 11 are rigidly associated with one another. The handwheels 32 are then acted upon, causing the scissors-like micrometric rotation of said sectors to increase or decrease the value of the angle comprised therebetween. Once said required value has been obtained, the cylinders 19 are actuated again and cause the return of the heads 16, extracting the tabs 15 from their respective hollow seats 14: in this manner the first upper sectors 9 and the second lower ones 11 are again completely disengaged from one another. The return action of said cylinders 19 furthermore induces a movement of the rockers 22, which move their horizontal portions 22a to press forcefully on the lower face 3a of the worktable 3, thus locking any further possible rotation of said second lower sectors 11; in turn, the first upper ones 9 are simultaneously locked by the means 23: the arc-like flange 26 supported by the stems 25 of the cylinders 24 compresses, when the latter are actuated, the first upper sectors 9 against the extension 7a, pulling said sectors upwards and locking the configuration obtained thereby. Once these elements have been thus positioned, the metal sheet to be processed is inserted between the blades 8 and 10; if, for example, the cut has to be of the maximum depth, at least one edge of said sheet is pushed to abut against one of the columns 13; said column is also usable as fixed reference if the cutting is to continue in a plurality of strokes. Subsequently, the fluidodynamic means 4 are actuated, causing the downward return of the head 7 and performing the cutting action; said head is guided, during its motion, by two vertical columns 5 which are slideable in related bushes, not shown in the figures, and by a shaped prismatic slider 6 the position whereof is such as to set both the resultant of the cutting forces generated by the upper extension 7a and the resultant of the moving forces of the fluidodynamic means 4 substantially onto the same line of action, in opposition to one another, so as to compensate each other; this substantially eliminates any bending moments so harmful in known machines that the worktable 3 thickness must be considerable; the latter, according to the invention, can thus instead be considerably reduced with great savings in construction material and therefore in cost with equal performance. Said head 7, during the cutting step, is capable of automatically adjusting the play between the upper blades 8 and the lower ones 10; this occurs by presetting the helical compression springs 28 to preset values so that the head 7, under the cutting force, spontaneously recovers the centesimal plays occurring between the columns 5 and the respective accommodation seats, as well as between the fluidodynamic means 4 and the shaped prismatic slider 6. Finally, it should be noted that the particular construction of the invention makes it structurally very solid and compact in its dimensions; at the same time it makes the worktable 3 and the box-like frame 2 fully independent, said frame thus having almost exclusively the function of containing the elements and of merely supporting said plane 3, all said elements being associated and rigidly coupled to said plane and only thereto. This allows to easily intervene thereon, both for ordinary maintenance and for repairs. In practice it has been observed that the described invention achieves the intended aims. The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept. For example, in figure 5-7 is illustrated a machine 101 comprising a frame 102 supporting an horizontal worktable 103. A head 104 is movable across the worktable in a vertical direction. The head 104 is C-shaped and provided with a first blade 105. The head 104 is operated by a fluidodynamic cylinder 106 pivoted on the lower side 103a of worktable 103. Head 104 is guided by guide means 107 affixed to the worktable 103. The shear force of first blade 105 and of a second blade 108 counterposed to the first blade, is regulated by means of adjustable elastic means 109 according to the thickness of the material to be worked. The cylinder 106 comprises a body 110, fixed to the horizontal lower projection 104a of head 104, and a stem base 111 fixed to the lower side 103a of the worktable 103 by means of a threaded ring 112. The guide means 107 comprises at least a pair of parallel cylindrical columns 113, fixed to the worktable 103 and slideable in corresponding through holes 115 with the interposition of antifriction bushes 114. The holes 115 are bored in the upper horizontal projection 104b of the head 105 at its vertical section 104c The adjustable elastic elements 109 comprise a helicoidal spring assembly 116. The springs are disposed horizontally in respective seats 117 and have ends 116a abutting against the lower portion of columns 113. The opposed ends 116b of springs 116, have plates 118 disposed vertically and horizontally movable micrometrically on respective guide pins 119. Figure 6 shows spring 116 compressed by means of screws 120 while figure 7 shows springs 116 compressed automatically by means of a fluidodynamic cylinder 121. The machine operates as follows: a sheet of metal to be sheared is positioned between the first upper blade 105 and the lower blade 108. Springs 116 are adjusted depending on the thickness of the sheet of metal so that they can provide a maximum stress value for the head 104. The cylinder 106 actuates the head 104 which moves vertically to either shear or punch the sheet of metal. The required play between the blades 105 and 108 is automatically obtained by the head 104 which is subjected to a bending moment and recovers centesimal plays existing between the bushes 114 and the columns 113 and between the stem 111 of the cylinder 110 and a respective guide bush 122. This peculiar design of the machine makes the frame 102 and the worktable 103 totally indipendent, all the elements of the machine 101 being associated to the worktable 103. Naturally the helicoidal springs 116 are selected with a coefficient of elasticity suitable for the use. Furthermore all the details may be replaced with other technically equivalent elements. In practice, the materials employed and the dimensions may be any according to the requirements without thereby abandoning the scope of the protection of the following claims. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Punching and shearing machine with variable cutting angle comprising a frame (2,102) supporting a worktable (3,103), a head (7,104) substantially vertically moving across said worktable and actuated by fluidodynamic means (4,106) associated to the lower side (3a,103a) of said worktable, said head being guided by guide means (5,107) associated to said worktable, said head being substantially C-shaped and having at least one first blade (8,105), said head being controlled by adjustable elastic means (27,109) for regulating the maximum value of shear strength for said at least one first blade depending on the thickness of the material to be worked, at least one second blade (10,108) being associated to said worktable, said at least one second blade being counterposed to said at least one first blade, said head (7) having an upper extension (7a) supporting at least two blades (8) directed towards the worktable (3) and mounted on two respective first upper sectors (9) which both rotate scissors-like about a vertical axis, said worktable (3) having at least two horizontal lower counter-blades (10) also supported by two second respective lower sectors (11) which rotate about said vertical axis, means (12) being provided for connecting said first upper sectors and said second lower sectors during a single step of rotation and means (18,23) being provided for positioning and locking them once their position is reached, said head being furthermore controlled by adjustable elastic elements (27) for adjusting the maximum value of the force applicable to the first upper blades according to the thickness and the mechanical resistance of the material being processed, said means (12) for connecting the first upper sectors and the second lower sectors comprising at least one pair of vertical prismatic columns (13) which are rigidly coupled to the upper sectors and have respective hollow seats (14) provided below the worktable, for the engagement, in a rotation configuration of the sectors, of tabs (15) with shaped cross sections which protrude from the perimeters of cylindrical heads (16) rigidly associated with supports (17) rigidly associated with said means (18) for locking in position. Machine, according to claim 1, characterized in that said fluidodynamic means comprises a cylinder (4,106) having its base associated to a lower horizontal projection (104a) of said head, the stem of the piston of said cylinder being associated to said worktable. Machine, according to claims 1 and 2, characterized in that said guide means comprise at least one pair of parallel cylindrical columns (113) associated to the worktable and slideable, with the interposition of antifriction bushes (114) in through holes (115) bored in a horizontal upper projection (104b) of said head. Machine, according to one or more of the preceding claims, characterized in that said elastic means comprises a helicoidal spring assembly (116), said springs (116) being disposed horizontally in respective seats (117), each of said springs having a first end (116a) abutting against the lower portion of said columns (113) and a second end (116b) provided with a vertical plate (118) micrometrically movable on respective guide pins (119). Machine, according to one or more of the preceding claims, characterized in that said means (18) for locking said second lower sectors once they have reached their position comprise at least one pair of fluidodynamic cylinders (19) located below the sectors in related seats (20), said cylinders having articulated to corresponding ends, according to substantially horizontal axes, the upper ends of rockers (22) the lower opposite ends whereof are J-shaped with horizontal portions (22b) acting, in an intervention configuration, by contact on the lower face of the worktable, said supports being, in said intervention configuration, retracted centripetally in a configuration for the release of the rockers or being pushed radially with consequent insertion coupling of the tabs of the heads in the related hollow seats provided in said vertical prismatic columns. Machine, according to claim 1, characterized in that said means (23) for locking said first upper sectors (9) once they have reached their position consist of respective cylinders (24) associated with the upper extension (7a) of said head (7), their stems (25) supporting a substantially horizontal arc-like flange (26) for compressing said first upper sectors (9) against said upper extension (7a) of the head. Machine according to claim 1, characterized in that said adjustable elastic means (27) for controlling the maximum applicable force and the play between the blades are constituted by a group of helical compression springs (28) arranged horizontally in a pack-like configuration in related seats (29) and having corresponding ends directly in contact with the lower portion of said columns (5) and the opposite ends in abutment against respective vertical plates (30) which are micrometrically horizontally movable on related guiding pins (31).

Inventors: LENZOTTI, EUGENIO
Applicants: LENZOTTI, EUGENIO
Application year: 1988
Main classification: B23D15
IPC codes: B23D15, B23D33