APPARATUS AND METHOD FOR MAKING A Z-SHAPED PROFILE ON A SHEET METAL PART

Abstract

An apparatus for making a Z-shaped profile on a sheet metal part having a first mould element acting as punch, a second mould element acting as die and a third mould element acting as sheet pressing element is provided. The second and third moulds element have respective flat clamping surfaces extending parallel to each other and are movable between an open position which allows insertion of the sheet metal part, and a closed position, in which the clamping surfaces are in contact with opposite sides of the sheet metal part. The first mould element is movable by translation along a working direction inclined to a direction perpendicular to the clamping surfaces towards a final working position in which the first mould element presses the sheet metal part against the second mould element.

Claims

1. An apparatus for making a Z-shaped profile on a sheet metal part, the apparatus comprising a first mould element acting as punch, a second mould element acting as die, and a third mould element acting as sheet pressing element, wherein the second mould element and the third mould element have respective flat clamping surfaces extending parallel to each other, and are movable relative to each other between an open position, in which said clamping surfaces are spaced apart from each other to allow insertion of the sheet metal part to be worked, and a closed position, in which said clamping surfaces are in contact with opposite sides of the sheet metal part to clamp said part, wherein the first mould element is mounted so as to be movable by translation along a working direction inclined to a direction perpendicular to said clamping surfaces, once the second mould element and the third mould element are in the above-mentioned closed position with the sheet metal part clamped between the respective clamping surfaces, towards a final working position in which the first mould element presses the sheet metal part against the second mould element, wherein the first mould element and the second mould element have respective working surfaces shaped in such a way as to define, when said first and second mould elements are in the final working position, the geometry of a first 90-degree bend and the geometry of a second 90-degree bend of the Z-shaped profile to be made, wherein the apparatus further comprises a control system means arranged to control the movements of the first mould element along said working direction, of the second mould element in a horizontal direction and of the third mould element along the working direction, and wherein said control system comprises a first carriage, which is mounted so as to be movable by translation along said working direction and carries the first mould element and the third mould element, a second carriage, which is mounted so as to be movable by translation in a horizontal direction and carries the second mould element, and a wedge-shaped control member, which is mounted so as to be movable by translation in a vertical direction and forms a first flat control surface, configured to cooperate with a corresponding control surface of the first carriage, and a second flat control surface, configured to cooperate with a respective control surface of the second carriage, in such a manner that the vertical movement of the control member first causes the second mould element to move in a horizontal direction towards the sheet metal part, then the third mould element to move along said working direction towards the sheet metal part and finally the first mould element to move along said working direction towards the sheet metal part until reaching said final working position.

2. The apparatus of claim 1, wherein the third mould element is also mounted so as to be movable by translation along said working direction, in such a manner that the displacement of the respective clamping surface to and from the clamping surface of the second mould element occurs by translation along said working direction.

3. The apparatus of claim 2, wherein the first mould element and the third mould element have respective flat guide surfaces which extend along said working direction and are held in contact with each other.

4. The apparatus of claim 3, wherein the first mould element has a first flat working surface extending parallel to the clamping surfaces of the second mould element and of the third mould element, and a second flat working surface extending perpendicular to the first working surface of the first mould clement, joining the latter with the guide surface of the first mould element, and wherein the second mould element has a first flat working surface extending parallel to the clamping surfaces of the second mould element and of the third mould element, and a second flat working surface extending perpendicular to the first working surface of the second mould element, joining the latter with the clamping surface of the second mould element, in such a manner that, when the first mould element is in the final working position, the clamping surface of the third mould element forms with the second working surface of the first mould element the an extrados of the first 90-degree bend of the Z-shaped profile, the second working surface of the first mould element forms with the first working surface of the first mould element the an intrados of the second 90-degree bend of the Z-shaped profile, the clamping surface of the second mould element forms with the second working surface of the second mould element the an intrados of the first 90-degree bend of the Z-shaped profile, and the second working surface of the second mould element forms with the first working surface of the second mould element the an extrados of the second 90-degree bend of the Z-shaped profile.

5. The apparatus of claim 1, wherein said control system further comprises a hydraulic drive configured to control the translational movement of the control member in a vertical direction.

6. The apparatus of claim 1, wherein the first mould element is configured to make an additional bend on the sheet metal part, in addition to the Z-shaped profile.

7. The apparatus of claim 1, further comprising four groups of main mould elements, each configured to make a Z-shaped profile on a respective side of a perimeter edge of the sheet metal part, and four groups of corner mould elements, each configured to make a Z-shaped profile on a respective corner portion connecting two adjacent sides of the perimeter edge of the sheet metal part, wherein each of said groups of main mould elements and said groups of corner mould elements comprises said first mould element, said second mould element and said third mould element, whereby the apparatus is capable of making a Z-shaped profile on the entire perimeter edge of the sheet metal part.

8. A method for making a Z-shaped profile on a sheet metal part by means of an apparatus according to claim 1, the method comprising: (a) clamping the sheet metal part between the clamping surfaces of the second mould element and of the third mould element, and (b) urging the first mould element against the sheet metal part along said working direction until said final working position is reached, in which the first mould element presses the sheet metal part against the second mould element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further features and advantages of the present invention will become clearer from the following detailed description, given purely by way of non-limiting example with reference to the accompanying drawings, wherein:

[0019] FIG. 1 shows a first sheet metal part having a Z-shaped profile obtainable with an apparatus and a method according to the present invention, coupled with a second sheet metal part;

[0020] FIG. 2 schematically shows the mould elements forming part of the apparatus of the present invention, in the initial operating condition;

[0021] FIGS. 3 to 9 are schematic views showing in sequence the movements of the mould elements of FIG. 2, from the initial operating condition of said figure up to the final operating condition in which the first sheet metal part has been deformed to form the desired Z-shaped profile;

[0022] FIG. 10 is a side view of a sheet metal part on which a Z-shaped profile has been formed with the apparatus of the present invention;

[0023] FIG. 11 is a perspective view of only the lower block of the apparatus of the present invention;

[0024] FIG. 12 is a perspective view of only the upper block of the apparatus of the present invention, arranged in an upside-down position with respect to the normal operating position;

[0025] FIG. 13 is a sectional view of the apparatus of the present invention, in its initial operating condition;

[0026] FIG. 14 is a sectional view showing a detail of the apparatus of the present invention, in its final operating condition;

[0027] FIG. 15 is a sectional view of a group of corner mould elements of the apparatus of the present invention; and

[0028] FIG. 16 is a perspective view of part of the group of mould elements of FIG. 15.

DETAILED DESCRIPTION

[0029] With reference first to FIGS. 2 to 9, an apparatus for making a Z-shaped profile on a sheet metal part P basically comprises a first mould element 10 acting as a punch, a second mould element 12 acting as a die, and a third mould element 14 acting as a sheet pressing element.

[0030] The second mould element 12 and the third mould element 14 have respective flat clamping surfaces 12a and 14a, which extend parallel to each other. In particular, the clamping surfaces 12a and 14a extend vertically. The second mould element 12 and the third mould element 14 are movable relative to each other between an open position (shown in FIG. 2), in which they allow insertion of the sheet metal part P to be worked, and a closed position (shown in FIG. 4), in which they clamp the sheet metal part P from opposite sides, with the respective clamping surfaces 12a and 14a, so as to lock the sheet metal part P in position during the subsequent working steps. More precisely, according to the proposed embodiment, the second mould element 12 is translatable in a direction perpendicular to the respective clamping surface 12a, thus in particular in a horizontal direction (as indicated with double arrows F2), while the third mould element 14 is translatable along a direction (as indicated with double arrows F3) inclined by a certain angle a (preferably included in the range from 15 to) 40 with respect to a direction perpendicular to the respective clamping surface 14a, thus in particular with respect to the horizontal. 20

[0031] The first mould element 10 is translatable along a working direction (as indicated by double arrows F1) parallel to the direction of translation (double arrows F3) of the third mould element 14. In this regard, the third mould element 14 has a flat guide surface 14b, which extends along the aforementioned working direction, and the first mould element 10 has a corresponding flat guide surface 10b, which extends parallel to the guide surface 14b and is kept in contact with the latter.

[0032] The first mould element 10 and the second mould element 12 also have respective working surfaces configured to act on the sheet metal part P, as a result of the movement of the first mould element 10 towards the second mould element 12 along the aforementioned working direction, so as to deform the sheet metal part P until it takes the desired Z-shaped profile, as shown in FIGS. 8 and 9.

[0033] More specifically, with reference in particular to FIGS. 8 and 9, the first mould element 10 has a first flat working surface 10a, extending parallel to the clamping surfaces 12a and 14a of the second mould element 12 and of the third mould element 14, and a 35 second flat working surface 10c, extending perpendicular to the first working surface 10a, joining the latter with the guide surface 10b.

[0034] On the other hand, the second mould element 12 has a first flat working surface 12b, extending parallel to the clamping surfaces 12a and 14a of the second mould element 12 and of the third mould element 14, and a second flat working surface 12c, extending perpendicular to the first working surface 12b, joining the latter with the clamping surface 12a.

[0035] In this way, when the first mould element 10 is in the final working position (FIGS. 8 and 9), with the second mould element 12 and the third mould element 14 placed in the closed position to clamp the sheet metal part P between the respective clamping surfaces 12a and 14a, and with the edge joining the guide surface 10b and the second working surface 10c aligned with the clamping surface 14a of the third mould element 14, the clamping surface 14a of the third mould element 14 forms with the second working surface 10c of the first mould element 10 the extrados E1 of the first bend of the Z-shaped profile, the second working surface 10c of the first mould element 10 forms with the first working surface 10a of said element the intrados 12 of the second bend of the Z-shaped profile, the clamping surface 12a of the second mould element 12 forms with the second working surface 12c of said element the intrados 11 of the first bend of the Z-shaped profile, and finally the second working surface 12c of the second mould element 12 forms with the first working surface 12b of said element the extrados E2 of the second bend of the Z-shaped profile.

[0036] The method for making the Z-shaped profile on the sheet metal part P provides therefore for the execution in sequence of the following movements of the three mould elements 10, 12 and 14, as shown in FIGS. 2 to 9.

[0037] With the second mould element 12 and the third mould element 14 initially in the open position, the sheet metal part P to be worked is inserted into the free space between the clamping surfaces 12a and 14a of said elements, as shown in FIG. 2. Subsequently, as shown in FIGS. 3 and 4, the second mould element 12 and the third mould element 14 are moved towards each other until they clamp the sheet metal part P from opposite sides with the respective clamping surfaces 12a and 14a. In the example proposed herein, first the second mould element 12 is moved (in the direction indicated by the double arrows F2) towards the sheet metal part P until the respective clamping surface 12a comes into contact with said part and, at that point, the third mould element 14 is also moved (in the direction indicated by the double arrows F3) towards the sheet metal part P until the respective clamping surface 14a comes into contact with said part. The first working surface 10a of the first mould element 10 remains in a position further back than the clamping surface 14a of the third mould element 14, so that at this stage only the clamping surface 14a comes into contact with the sheet metal part P.

[0038] However, it can be envisaged that the movements of the second mould element 12 and the third mould element 14 occur simultaneously, or at least partially simultaneously, with respect to each other, instead of one after the other.

[0039] Starting from the condition in which the sheet metal part P is clamped between the clamping surfaces 12a and 14a of the second mould element 12 and the third mould element 14, with said mould elements held stationary in the closed position, the first mould element 10 is moved along the aforementioned working direction (identified by the double arrows F1), sliding with its guide surface 10b along the corresponding guide surface 14b of the third mould element 14, towards the second mould element 12. As a result of this movement, as shown in FIG. 5, initially the first working surface 10a of the first mould element 10 comes to a position where it is substantially aligned with the clamping surface 14a of the third mould element 14 and is thus in contact with the sheet metal part P.

[0040] Further movement of the first mould element 10 along the aforementioned working direction towards the second mould element 12 leads to a deformation of the sheet metal part P, as shown in FIGS. 6 and 7. This movement is stopped when the edge joining the second working surface 10c and the guide surface 10b of the first mould element 10 is aligned with the clamping surface 14a of the third mould element 14, or in any case does not protrude beyond the clamping surface 14a of the third mould element 14 towards the second mould element 12, as shown in FIGS. 8 and 9. In this regard, the mould elements 10 and 12 will be suitably configured so that in the final working position of FIGS. 8 and 9 the space between the working surfaces 10a and 10c of the first mould element 10 and the working surfaces 12b and 12c of the second mould element 12 corresponds to the geometry of the Z-shaped profile to be made on the sheet metal part P. This means that the distance between the first working surface 10a of the first mould element 10 and the clamping surface 14a of the third mould element 14, when the first mould element 10 is in the final working position, will have to correspond to the distance between the extrados E1 of the first bend and the intrados 12 of the second bend of the Z-shaped profile, while the distance between the clamping surface 12a and the first working surface 12b of the second mould element 12 will have to correspond to the distance between the intrados 11 of the first bend and the extrados E2 of the second bend of the Z-shaped profile.

[0041] As is apparent from the above explanations, the deformation of the sheet metal part P to form the Z-shaped profile is obtained by movement of the first mould element 10 along only one direction, namely the aforementioned working direction inclined by the angle a with respect to a direction perpendicular to the clamping surfaces 12a and 14a of the second mould element 12 and of the third mould element 14.

[0042] FIG. 10 shows an example of a sheet metal part P having a Z-shaped profile which can be obtained with an apparatus according to the present invention. According to this example, the sheet metal part P is a kitchen oven casing, thus a sheet metal part having a bottom wall BW and four side walls SW extending from the bottom wall BW and defining a cavity with the latter. The side walls SW are substantially flat, or at least mainly flat, and are joined to each other by means of arcuated corner portions AW. As shown in the detail A of said figure, the Z-shaped profile is made on the side walls SW, in particular in an end zone thereof opposite the bottom wall BW, as well as on the corner portions AW, in such a way as to extend along the entire perimeter of the sheet metal part P.

[0043] Furthermore, according to the example shown in FIG. 10, in the corner portions AW the wall below the Z-shaped profile is bent outwards, as indicated with arrow F in the detail A of said figure, in such a way as to give greater rigidity to the sheet metal part at these portions. This additional bend may have a straight or at least partially curved shape. Moreover, this additional bend may be made not only in the corner portions AW, but also in the side walls SW, so as to extend along the entire perimeter of the sheet metal part P.

[0044] In the example of FIG. 10, the Z-shaped profile has the function of accommodating an additional sheet metal part (not shown) and allowing it to be coupled with the sheet metal part P without creating discontinuity in feel, while the additional bend has the function of facilitating the insertion of the additional sheet metal part to be coupled with the sheet metal part P.

[0045] However, it is clear that the invention can also be applied to the working of sheet metal products having shapes other than the one of FIG. 10.

[0046] An example of an apparatus according to the present invention will now be described with reference to FIGS. 11 to 14. According to this embodiment, the apparatus is arranged to make the Z-shaped profile on the sheet metal part P shown in FIG. 10. Of course, depending on the specific shape of the sheet metal part P to be worked, the apparatus may be suitably modified with respect to the solution described and illustrated herein.

[0047] The apparatus, which is shown in its entirety in FIG. 13 (where it is indicated with 100), is essentially configured as a press which, by means of a hydraulic drive, controls the movement of the mould elements described above, transmitting the force required to perform the forming operation on the sheet metal part P to be worked.

[0048] The apparatus 100 basically comprises a lower block 102 (shown in FIG. 11), in which the mould elements 10, 12 and 14 described above are mounted, and an upper block 104 (shown in FIG. 12).

[0049] With regard to the lower block 102, given the shape of the sheet metal part P (which, as mentioned, is in this case a kitchen oven casing) on which the apparatus is arranged to make the Z-shaped profile, there are in this case four groups of mould elements, one on each side of the perimeter edge of the sheet metal part, wherein each group of mould elements comprises the first mould element 10, the second mould element 12 and the third mould element 14 described above. Furthermore, since in the present case the Z-shaped profile is also to be made at the arcuate corner portions, each of which connects a pair of adjacent sides, four further groups of mould elements are provided, hereinafter referred to as corner mould element groups (while the four groups of mould elements operating on the four sides will be hereinafter referred to as main mould element groups).

[0050] The sheet metal part to be worked is positioned on the lower block 102, resting on a plate 106 acting as a supporting and centring member, with the four sides of the perimeter edge extending vertically, and thus the arrangement of the mould elements of each main mould element group is similar to that illustrated above with reference to FIGS. 2 to 9, i.e., with the clamping surfaces 12a and 14a of the second mould element 12 and of the third mould element 14, respectively, extending vertically.

[0051] With reference not only to FIG. 11, but also to FIG. 13, the lower block 102 basically comprises a support base 108 to which a plurality of guide bodies 110 are fixed, in the present case four guide bodies, each associated with a respective main mould element group, and each having a flat guide surface 110a, which is inclined by the aforementioned angle a to the horizontal and thus extends parallel to the working direction of the respective main mould element group.

[0052] In the sectional view of FIG. 13 there are shown the guide bodies 110 associated with the main mould element groups operating on the two parallel short sides of the perimeter edge of the sheet metal part to be worked, but the same applies to the guide bodies associated with the main mould element groups operating on the parallel long sides of the perimeter edge of the sheet metal part to be worked.

[0053] As shown in FIG. 13, a first carriage 112 is mounted on each guide body 110 and forms at its bottom a flat guide surface 112a adapted to slide on the guide surface 110a of the guide body 110. The first carriage 112 carries both the first mould element 10 and the third mould element 14. With reference also to FIG. 14, according to the illustrated embodiment, the first carriage 112 forms at its top a first support surface 112b which extends parallel to the guide surface 112a and on which the first mould element 10 rests with a lower flat surface 10d thereof. In addition, the first carriage 112 forms, in a proximal portion thereof (i.e., in a portion thereof facing the centre of the lower block 102), a flat abutment surface 112c arranged adjacent to the first support surface 112b and extending perpendicular to the latter, so that the first mould element 10 is in abutment with its proximal side against the abutment surface 112c. The third mould element 14 is arranged on the first mould element 10, with its guide surface 14b in contact with the guide surface 10b of the first mould element 10, said guide surfaces 10b and 14b extending parallel to the guide surface 110a of the guide body 110, thus along the aforementioned working direction. The third mould element 14 further forms at its top a flat guide surface 14c, which extends parallel to the guide surface 14b of said mould element and runs along a corresponding flat guide surface 112d of the first carriage 112, which extends parallel to the guide surface 112a of said carriage.

[0054] Again with reference to FIG. 13, as well as to FIG. 14, on each first carriage 112 a second carriage 114 is slidingly mounted in a horizontal direction and the second mould element 12 is fixed thereto. In this respect, the first carriage 112 forms at its top a second support surface 112e which extends horizontally and on which the second carriage 114 rests with a flat lower surface 114a thereof. The second carriage 114 can thus slide horizontally on the second support surface 112e of the first carriage 112, carrying with it the second mould element 12.

[0055] The second carriage 114 is arranged between a proximal protrusion 116 and a distal protrusion 118 of the first carriage 112. The proximal protrusion 116 of the first carriage 112 forms, on its side facing the second carriage 114, an abutment surface 112c, while the distal protrusion 118 forms, on its side facing the second carriage 114, a flat control surface 118a which is inclined to the vertical by the same angle a mentioned above. In turn, as better shown in FIG. 14, the second carriage 114 forms, on its side facing the distal protrusion 118 of the first carriage 112, a flat control surface 114b which is inclined to the vertical by a certain angle (in particular an angle between 20 and) 60.

[0056] Depending on their length, the first carriages 112 may have a single control surface 118a, such as the first carriages 120 associated with the short sides of the perimeter edge of the sheet metal part to be worked, or a pair of control surfaces 118a arranged side by side at a certain distance from each other, such as the first carriages 112 associated with the long sides of the perimeter edge of the sheet metal part P to be worked. In the case of first carriages 112 having two control surfaces 118a, there will advantageously be provided, for each of said first carriages, a pair of second carriages 114, each arranged so that its control surface 114b faces one of the control surfaces 118a of the first carriage 112.

[0057] Referring now to FIGS. 12 and 13, the upper block 104 basically comprises a fixed plate 120, which is mounted on a plurality of support bodies 122 fixed to the support base 108 of the lower block 102, and a movable plate 124, which is arranged above the fixed plate 120 and is vertically movable relative to it by means of a hydraulic drive (which is neither shown nor described in detail, but nevertheless of a type per se known) between a lowered position, shown in FIG. 12 (where, as indicated above, the upper block 104 is shown in an upside-down position), and a raised position, shown in FIG. 13.

[0058] The upper block 104 further comprises, for each side of the perimeter edge of the sheet metal part P to be worked, thus for each main mould element group, at least one wedge-shaped control member 126, which is fixed to the lower face of the movable plate 124 and protrudes from it downwards, passing through a respective through opening 128 in the fixed plate 120. In particular, in the proposed embodiment there are one control member 126 for each of the two short sides of the perimeter edge of the sheet metal part P to be worked and two control members 126 for each of the two long sides of the perimeter edge of the sheet metal part P to be worked. Each control member 126 forms a first flat control surface 126a, which is adapted to cooperate with the control surface 118a of the respective first carriage 112 and has the same inclination to the vertical as the control surface 118a, and, on the opposite side with respect to the first flat control surface 126a, a second flat control surface 126b (which can be better observed in FIG. 14), which is adapted to cooperate with the control surface 114b of the respective second carriage 114 and has the same inclination to the vertical as the control surface 114b.

[0059] The control surfaces 118a, 114b, 126a and 126b of the first carriage 112, of the second carriage 114 and of the control member 126, respectively, are configured in such a way that, as a result of the movement of the movable plate 124 from the raised position to the lowered position, and therefore as a result of the downward movement of the control member 126, first the second control surface 126b of the control member 126 comes into contact with the control surface 114b of the second carriage 114, causing the second carriage 114 to move horizontally inwardly (in a leftward direction, relative to the point of view of a person looking at FIG. 13), and then the first control surface 126a of the control member 126 comes into contact with the control surface 118a of the first carriage 112, causing the first carriage 112 to move along the guide surface 110a of the guide body 110 upwardly and outwardly (in a rightward direction, relative to the point of view of a person looking at FIG. 13).

[0060] The horizontal inwardly translational movement of the second carriage 114 causes the second mould element 12 to move against the sheet metal part P, as described above with reference to FIG. 3. This movement is stopped when the second control surface 126b of the control member 126 is no longer in contact with the control surface 114b of the second carriage 114, but the control member 126 and the second carriage 114 are in contact with each other with respective vertical flat surfaces, as shown in FIG. 14. Naturally, such surfaces will be designed to ensure that the travel of the second carriage 114 is sufficient to bring the second mould element 12 into contact with the sheet metal part P. In addition, suitable compensation systems may be provided to compensate for any overtravel of the second carriage 114.

[0061] On the other hand, the translational upwardly and outwardly movement of the first carriage 112 along the guide surface 110a of the guide body 110 causes the third mould element 14 and the first mould element 10 to move along the aforementioned working direction, as described above with reference to FIGS. 4 to 9. As shown in FIG. 13, initially the third mould element 14 is positioned so that its clamping surface 14a is closer to the sheet metal part to be worked than the first working surface 10a of the first mould element 10, whereby as a result of the movement of the first carriage 112 there is first contact of the third mould element 14 with the sheet metal part P and then contact of the first mould element 10. Again, suitable compensation systems may be provided to compensate for any overtravel of the first carriage 112.

[0062] Referring now to FIGS. 15 and 16, as well as FIGS. 11 and 12, the corner mould element groups will also be briefly described, which groups are similar in configuration and operation to the main mould element groups described above. For ease of reference, the components of the corner mould element groups similar to those of the main groups are indicated in the figures by the same reference numbers, with the addition of the symbol .

[0063] As shown in FIG. 11, there are provided on the support base 108 a plurality of guide bodies 110, in the present case four guide bodies, each associated with a respective corner mould element group. In the present case, each guide body 110 is arranged at 45 to the two guide bodies 110 adjacent thereto.

[0064] With reference to FIG. 15, each guide body 110 has a flat guide surface 110a inclined to the horizontal, on which a carriage 112 is slidingly mounted and carries both the first corner mould element 10 acting as a punch and the third corner mould element 14 acting as a sheet pressing element. Also in this case, the movement of the carriage 112 along the flat guide surface 110a of the guide body 110 is controlled by a wedge-shaped control member 126, which is fixed to the lower face of the movable plate 124 and protrudes from it downwards. In this regard, each control member 126 forms a flat control surface 126a adapted to cooperate with a corresponding control surface 118a of the respective carriage 112.

[0065] As can be seen from FIG. 6, in the case of the corner mould element groups, the working surfaces of the mould elements will not be flat surfaces, but arcuate surfaces, since these surfaces have to operate on arcuate corner portions of the sheet metal part P.

[0066] Finally, as shown in FIG. 15, the first corner mould element 10 forms at its bottom, i.e., below the first working surface 10a, a working surface 10d arranged to make the outward bend in the corner portions of the sheet metal part P below the Z-shaped profile.

[0067] As can be seen from the above description, the present invention makes it possible to realise a Z-shaped profile along the entire perimeter of a sheet metal part, such as, for example, a kitchen oven casing, with at least the following advantages over the state of the art: [0068] fewer directions of movement of the mould elements, since the first and third mould elements are both moved in the working direction and the second mould element is moved in the horizontal direction; [0069] single control system (movable plate of the upper block, with its control members, and first and second carriages of the lower block) which controls the movement of all the mould elements; [0070] simplicity of the apparatus, which basically consists of a hydraulic press and a mould; [0071] reduction in production costs and time; [0072] reduction in maintenance costs and time; and [0073] increase in efficiency and reduction in production waste.

[0074] Furthermore, an apparatus according to the present invention allows not only to make a Z-shaped profile, but also to form additional geometries on the sheet metal part during the same operation, i.e., without performing additional working operations at other working stations.

[0075] The present invention has been described with reference to a preferred embodiment or mode of implementation thereof. It is to be understood that other embodiments or modes of implementation may be envisaged, which share the same inventive core with those described herein, as defined by the appended claims.