BACKGROUND OF THE INVENTION

This invention relates to a machine that is suitable for folding sheet metal, and in particular edges of sheet metal.

PRIOR ART

Machines are known for folding sheet metal, for example for making panels and other components of domestic appliances such as refrigerators, washing machines and dryers, dish washers, ovens and other. Such machines comprise a sheet metal supporting tool, a sheet metal pressing tool, and a sheet metal folding tool, which are parallel to one another, and each have a particular profile.

The sheet metal supporting tool normally moves according to a horizontal axis X, the sheet metal pressing tool normally moves according to a vertical axis Y perpendicular to the axis X, and the folding tool moves according to the two axes X and Y or, by interpolation, according to any rectilinear and/or curvilinear path.

The sheet metal that has to be folded, for example along a longitudinal edge thereof, is tightened between the sheet metal supporting tool and the sheet metal pressing tool with the edge to be folded protruding. The folding tool, with a preset folding movement, folds the edge of the sheet metal over the profile of one or the other of the two sheet metal supporting and sheet metal pressing tools. The profile of the tools correspondingly defines the folding profile.

Folding the edges of the sheet metal to make a box component, for example the door of a refrigerator, is critical at the corners of the sheet metal where the ends of consecutive edges are folded towards one another. After folding, in fact, in such corners, sharp-edged profiles may form and/or cusps that are sharp points of the formed box component. Further, as the sheet metal to be folded is already painted, such points constitute points of rust formation.

OBJECT OF THE INVENTION

The object of the present invention is to propose a machine for folding sheet metal that is able to solve the aforesaid problems.

BRIEF DESCRIPTION OF THE INVENTION

This object is achieved by a sheet metal folding machine according to claim 1. BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the invention, a description is given below of a non- limiting exemplary embodiment thereof, illustrated in the attached drawings in which:

fig.1 is a front perspective view of a sheet metal folding machine according to the invention;

fig.2 is a rear perspective view of the machine of fig.l;

figs. 3-8 are perspective views of details of the machine of fig. l ;

fig. 9 shows schematically the operating principle of the machine of fig. l ;

figs. 10,11 show prospectively an alternative embodiment of the machine of fig. l .

DETAILED DESCRIPTION OF THE INVENTION With reference to figs 1,2, the illustrated machine for folding sheet metal, indicated generally by 10, provides a base 11 and a frame 12 slidably fitted on the base 11. The frame 12 is moved along the base 11 according to a horizontal axis X (indicated in fig.2) by means of an electric motor Ml . A longitudinal frontal wall 13 is integral with the frame 12; a rectilinear sheet metal supporting tool 14, having a horizontal longitudinal extent perpendicular to the axis X, is fixed to the wall 13. To the frame 12 a slide 15 is fitted, which is arranged in a position opposite and parallel to the wall 13. The slide 15 is moved according to the horizontal axis X by two electric motors M2.

With reference to fig.3, to the slide 15, at the wall 13 (fig.2), a longitudinal plate 16 is slidably fitted; to the plate 16 a rectilinear sheet metal folding tool 17 is fixed, which has a longitudinal horizontal extent perpendicular to the axis X. The plate 16 is slidable according to a vertical axis Y, perpendicular to the axis X, by two electric motors M3 (fig 2).

With reference to figs 3,5, the sheet metal folding tool 17 has a cylindrical bar 18, which has a longitudinal horizontal extent, with a flat face 19 that extends over the entire length of the bar 18. The bar 18 is fitted rotatably to a series of supports 20 fixed to a shelf 21 that is in turn fixed to the plate 16 and is hinged on two end supports 22, one of which is visible in fig.8, which are also fixed to the shelf 21. As can be seen in fig.5, the supports 20 each have a semicylindrical seat 23 in which the bar 18 is rotatably received. With reference to figs 7,8, to one end of the bar 18 a lever 24 is connected that is in turn connected to the rod 25 of an actuator cylinder 26; the cylinder 26 is fitted to an arm 27 fixed to the plate 16.

With reference to figs 1, 2, a longitudinal beam 28 is fitted to the upper part of the frame 12. The beam 28 is slidable with respect to the frame 12 and is moved along the vertical axis Y by two electric motors M4. A tool supporting longitudinal bar 29 is rotatably fitted to the beam 28. To the bar 29, a plurality of sheet metal pressing tools is fixed, one of which is clearly visible in detail in figs 4,6, indicated with 30; each sheet metal pressing tool has a horizontal longitudinal extent, perpendicular to the axis X, and has a preset section profile that is different from that of the other sheet metal pressing tools. The bar 29 is rotated by an electric motor M5 fixed to the beam 28.

The motors M1-M5 are all connected to a command and control unit that is not illustrated.

The operation of the disclosed and illustrated machine 10 for folding sheet metal is as follows.

The sheet metal is brought along a plane P at the machine 10 until it comes to rest, along a side to be folded, on the sheet metal supporting tool 14.

The motor Ml is above all driven so as to move the frame 12 with respect to the base 11 along the axis X so as to position correctly the tool 14 with respect to the sheet metal in order to fold the edge.

The two motors M4 are then driven so as to lower the beam 28 and the tool supporting bar 29 therewith along the axis Y until the selected tool of the bar, in the figs the tool 30, presses the sheet metal against the tool 14 so as to keep clamped the sheet metal .

The edge of the sheet metal rests on the flat face 19 of the cylindrical bar 18. At this point, the motors M2 and M3 are suitably driven so as to move the folding tool 17 to fold the edge of the sheet metal with a movement according to a path that follows the profile of the tool 30. As shown in fig.9, during this folding movement the cylindrical bar 18 rotates in the cylindrical seats 23 around the hinging axis thereof, accompanying the edge of the sheet metal, indicated by L, around the profile of the tool 30.

Once folding has terminated, the actuator cylinder 26 is activated that rotatingly brings, through the lever 24, the bar 18 back to the initial position with the flat face 19 arranged horizontally.

Alternatively to the actuator cylinder 26, the simple mechanical system illustrated in figs 10, 11 can be used. In this case, there is always a lever, indicated by 50, connected to one end of the bar 18. The lever 50 interacts however with an abutment 51. When the folding tool 17 moves to fold the edge of the sheet metal and the cylindrical bar 18 rotates, also the lever 50 rotates, as shown in sequence in figs 10, 11. When the folding tool 17 returns to the initial position, a protruding portion 50A of the lever 50 interferes with the abutment 51 so as to rotate the cylindrical bar 18 in the opposite direction and return the cylindrical bar 18 to the initial position.

If it is desired to change the sheet metal pressing tool, the motor M5 is driven that determines the rotation of the tool holder bar 29 until the selected sheet metal pressing tool is above the sheet metal supporting tool 14.

The disclosed and illustrated machine 10 has several advantages.

The rotational movement of the cylindrical bar 18 causes a folding of the edge of the sheet metal with rounding, such as to prevent the formation of sharp-edged profiles or sharp cusps and may constitute points of rust formation, in particular at the corners of the sheet metal.

This is obtained with a simple and thus not expensive mechanism. Further, the simplicity of the mechanism gives the machine high reliability, thus avoiding costly machine downtime.

The possibility of selecting the sheet metal pressing tool by rotating the tool supporting bar 29 enables a variety of curvature radii of the edge of the sheet metal to be selected. And this is obtained without having to disassemble and reassemble the sheet metal pressing tools.

It is clear that variations on and/or addition to what has been disclosed and illustrated in the attached drawings can be provided.

In particular, the configuration and the number of the various components can vary according to technical needs.