Patent Publication Number: US-2019176205-A1

Title: Machine for forming metal stampings having an edge portion folded over on itself

Description:
TECHNICAL FIELD 
     The present invention relates to a machine for forming metal stampings having an edge portion folded over on itself. 
     BACKGROUND ART 
     The requirement to have a metal stamping with an edge folded over on itself is common to many products, for both aesthetic and safety reasons. 
     As is well known to a person skilled in the art, the production of metal stampings having an edge folded over onto itself currently requires a sequence of operations each of which is performed by different machinery. In other words, the edge portion of the metal stamping is folded over on itself through several bending operations, each of which is carried out by different machinery. 
     As may be immediately seen, such a procedure for achieving the folding of the edge portion results in both a significant encumbrance and extremely lengthy production times. Both of these aspects necessarily constitute disadvantages in terms of productivity. 
     There is therefore a need to have a single machine, the technical characteristics of which make it possible to achieve the forming of a metal stamping, including achieving the folding of the edge portion, in a single solution. 
     DISCLOSURE OF INVENTION 
     The subject of the present invention is a machine for forming a metal stamping, the essential characteristics of which are set forth in claim  1 , and whose preferred and/or auxiliary characteristics are indicated in claims  2 - 5 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Below is a non-limiting example of an embodiment purely by way of illustration with reference to the figures of the accompanying drawings, wherein: 
         FIGS. 1 to 7  are cross-sections of the machine which is the subject of the present invention, in respective forming steps; and 
         FIG. 8  in particular is a cross-section along the line VIII-VIII of  FIG. 1 . 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     In  FIGS. 1-7  a machine for forming metal stampings according to the present invention is indicated as a whole with  1 . The machine  1  comprises a movable upper die holder  2  on which an upper die half  3  is mounted, and a fixed lower die holder  4  on which a lower die half  5  is mounted. The upper die holder  2  is movable with respect to the lower die holder  4 , to operate two guide columns  6 , each of which has a first end attached to the upper die holder  2  and a second end attached to the lower die holder  4 . The upper die half  3  and the lower die half  5  comprise respective, mutually complementary, forming surfaces  3   a  and  5   a , the coupling of which defines the shape of the metal stamping S. 
     The machine  1  comprises an upper clamping yoke  7  mounted on the upper die holder  2  and a lower clamping yoke  8  mounted on the lower die holder  4 . The upper clamping yoke  7  is arranged so as to surround the upper die half  3  and moves integrally with it. Similarly, lower clamping yoke  8  is arranged so as to surround the lower die half  5 . The upper clamping yoke  7  and lower clamping yoke  8  mutually cooperate in the clamping operation of the edge portion of a sheet that will constitute the stamping. 
     The machine  1  comprises an edge cutting/bending unit  9  arranged so as to surround the upper die half  3  and the lower die half  5  and positioned in a space between the two die halves and the two clamping yokes  7  and  8 . 
     The edge cutting/bending unit  9  comprises a cutting blade  10  which is specifically arranged to surround the upper die half and is positioned between it and the upper clamping yoke  7 . The cutting blade  10  is attached to a handling plate  11 , which is in turn attached to the upper die holder  2 . In this respect, the upper die holder  2  comprises a plurality of damper pistons  12  which make possible the movement of the handling plate  11  and therefore of the cutting blade  10  even when the upper die half  3  has reached the end of its travel onto the lower die half  5 . 
     The edge cutting/bending unit  9  comprises an outer bending blade  13  which is arranged to surround the lower die half  5  and is positioned between it and the lower clamping yoke  8 . The outer bending blade  13  is attached to a handling plate  14  on which the plurality of pistons  15  act. In particular, as clearly shown in the respective enlargements of  FIGS. 2-6 , the outer bending blade  13  is arranged directly below the cutting blade  10  in such a way that the vertical movement of the cutting blade must be accompanied by an opposite movement of the outer bending blade  13  and vice versa. 
     In particular, the outer bending blade  13 , having a thickness greater than that of the cutting blade  10  forms with the latter a step G facing toward the lower die half  5 . As described below, the presence of this step G serves a function in a first and a second bending operation of the edge portion. 
     The edge cutting/bending unit  9  comprises an inner bending blade  16  which is arranged to surround the lower die half  5  and is positioned between it and the outer bending blade  13 . The inner bending blade  16  is attached to a handling plate  17  on which a piston  18  acts. 
     As shown in the enlargements of  FIGS. 2-6 , the inner bending blade  16  has an oblique upper surface  19 . As described below, the inner bending blade  16  has the function of completing the operation of the edge portion bending on itself. 
     In particular, as shown in  FIG. 8 , the outer bending blade  13  and the inner bending blade  16  have two respective toothed sliding surfaces  13   a  and  16   a  which are mutually interlocked and arranged to slide against each another. The teeth of the toothed sliding surfaces  13   a  and  16   a  have a trapezoidal shape. 
     The following describes the operation of the machine which is the subject of the present invention with reference to the sequence of operations illustrated in  FIGS. 1-7 . 
     As shown in  FIG. 1 , when the machine is in its open configuration, with the upper die holder  2  spaced apart from the lower die holder  4 , a metal sheet L is inserted into the machine  1  resting on the lower clamping yoke  8 . 
     As shown in  FIG. 2 , the machine is brought into its closed position by the operation of the two guide columns  6 . In the closed position the upper clamping yoke  7  is arranged in abutment on the lower clamping yoke  8  to achieve the clamping of the sheet L and, simultaneously, the forming surface  3   a  of the upper die half  3  is forced onto the forming surface  5   a  of the lower die half  5  thus moulding the sheet L to form the stamping S. 
     As shown in  FIG. 3 , once the forming of the sheet L has taken place by means of the coupling of the two forming surfaces  3   a  and  5   a , the shearing of the edge takes place by means of the downward movement of the cutting blade  10 . In particular, the downward movement of the cutting blade always takes place by the action of the guide columns  6  and this is made possible because the damper pistons  12  ensure the downward movement of the handling plate  11  and therefore of the cutting blade  10 , despite the upper die half  3  having reached the end of its travel onto the lower die half  5 . 
     As is apparent from the enlargement of  FIG. 3 , while the cutting blade  10  and the outer bending blade  13  move downwards, the inner bending blade remains stationary and this causes the portion of the edge cut by the cutting blade  10  to be folded, arranging itself in the space formed by the step G between the cutting blade  10  and the inner bending blade  16 . 
     At this point, the first bending operation being made, as clearly shown in the enlargement of  FIG. 4 , the inner bending blade  16  moves downwards in order to leave the space necessary to achieve a second bending operation clearly shown in the enlargement of  FIG. 5 . The second bending operation is carried out by the upward movement of the outer bending blade  13  and therefore of the cutting blade  10 , while the inner bending blade  16  remains stationary. The upward movement of the outer bending blade  13  carries out the second bending operation because the step G engages with the already folded edge portion, sliding and thus forcing it into a further bending inside the space left free by the downward movement of the inner bending blade. 
     As clearly illustrated in the enlargement of  FIG. 6 , the third and last bending operation takes place by means of the upward movement of the inner bending blade which, thus, compresses the edge portion against a peripheral portion of the forming surface  3   a  of the die half  3 . 
     At this point, the stamping is completed with the edge portion folded and the machine  1  is returned to its open configuration ( FIG. 7 ) and the stamping can be removed. 
     From the above description, it is clear how the machine which is the subject of the present invention makes it possible to carry out the forming of a stamping ensuring, at the same time, the bending of an edge portion. 
     Being able to have a single forming machine for the creation of the stamping in its entirety (including the bending of the edge portion) certainly provides a great advantage in terms of productivity. In fact, the machine of the present invention makes possible a significant reduction in space and an equally significant reduction in throughput times.