SHEET METAL DRAWING MACHINE

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the general field of shaping or forming sheets (in particular metal sheets) by means of drawing presses.

It relates more particularly to a machine for forming sheet metal by drawing, which machine comprises a central longitudinal axis and a frame receiving a forming tool placed between two lines of drawing jaws arranged opposite each other and carried by mechanical means allowing their movement in space.

STATE OF THE ART

In the field mentioned above, we know of machines called transverse drawing machines.

Transverse drawing is used to draw sheet metal across its width, typically along the leading edges. This particular method applies a vertical force to the line of jaws. The sheet metal is clamped in the jaws of the line of jaws and then wraps around them during the forming process. This allows for the production of very narrow parts.

The machine configuration for this mode is defined by a straight line of jaws. The drawing cylinders are extended so that the drawing head is fully retracted into the rocker arm. Oscillation and rotation are in position for this configuration. A support beam for transverse forming is positioned above the line of jaws to absorb the vertical forces applied to it. The rocker arm cylinders also absorb this vertical force and allow control of the rocker arm angle during part forming.

We also know of machines called longitudinal drawing machines, designed to draw sheet metal along its length, typically fuselage components. This mode allows a drawing force to be applied to the sheet metal tangential to the tool throughout the process.

To keep the sheet metal tangent to the tool as described above and maintain a constant force across its entire width, the line of jaws is equipped with several axes to keep it “floating.” In this way, each jaw is articulated along an axis that allows the entire line of jaws to curve, keeping the sheet metal tangent to the tool during forming.

Current drawing machines are generally structured to perform either longitudinal or transverse drawing.

For the “longitudinal drawing” mode, the sheets are limited in width; and for the “transverse drawing” mode, it is advantageous to have a wider line of jaws than in longitudinal drawing.

Some known machines comprise lines of jaws that serve both modes: longitudinal and transverse.

In this case, the lines of jaws are limited to certain widths, otherwise, beyond that, forming problems will arise, in particular limits in terms of forces or radius of curvature.

Presentation of the Invention

In order to remedy the aforementioned drawback of the prior art, the present invention proposes a machine for forming sheet metal by drawing, which machine comprises a machine frame having a central longitudinal axis, equipped with a table structure for receiving a forming tool placed between two lines of drawing jaws arranged opposite each other and supported by mechanical means allowing their movement in space,

This machine is characterized by the fact that the said lines of jaws have an adjustable length,

each one of the said lines of jaws comprising:

• • a first group of jaws arranged in a line, which first group of jaws is designed to allow the forming of a sheet by longitudinal drawing, the line of jaws of said first group of jaws, called the central line of jaws, comprising two end jaws, and
  • a second group of jaws comprising at least two jaws suitable for being in:
    • (a) an inactive position in which the jaws of said first group of jaws are positioned at a distance from the jaws of said second group of jaws, to enable said central line of jaws to perform a forming of a sheet by longitudinal drawing, and
    • (b) an active position in which the jaws of said first group of jaws are positioned in line between the jaws of the second group of jaws, in line with the two end jaws of said first group of jaws,
    • the resulting line of jaws, which is called the complete line of jaws and comprises said first group of jaws and said second group of jaws, being designed to allow the forming of a sheet by a transverse type drawing.

Therefore, by its structure, such a drawing machine can achieve, under optimal conditions, either transverse or longitudinal drawing.

The principle of the present invention is to propose two possible configurations of the lines of jaws, namely:

• • a configuration adapted to the longitudinal drawing mode, comprising a line of curvable (or bendable) jaws, and
  • a configuration adapted to the transverse drawing mode, comprising a straight line of jaws, composed of the curvable line of jaws in the straight position (jaws aligned) in the center and two fixed parts on either side of the central line of jaws.

Other non-limiting and advantageous features of the forming machine according to the invention, taken individually or in all technically possible combinations, are as follows:

• • the central line of jaws is supported by a central line of jaws frame, the second group of jaws is supported by a second group of jaws frame, and the machine comprises means for the relative movement of said central line of jaws frame and said second group of jaws frame, so as to allow said second group of jaws to occupy the aforementioned active position and inactive position;
  • the frame of the second group of jaws comprises a base which extends into two lateral extensions at the distal ends of which are formed the jaws of said second group of jaws,
  • said central line of jaws frame comprises a cylindrical guide column, centered or approximately centered on said central longitudinal axis and which slides through the base of said second jaw group frame,
  • means for maneuvering in translation, constituting said means of movement, and means for maneuvering in rotation of said guide column are interposed between the base of said second group of jaws frame and the free end of said guide column, located on the other side of said base of the second group of jaws frame with respect to the central line of jaws frame;
  • the distal ends of the lateral extensions of the second group of jaws frame are carried by support carriages movable along two longitudinal beams, constituting said machine frame, which extend parallel to said central longitudinal axis, which support carriages are maneuverable along the length of said longitudinal beams by means of carriage cylinders;
  • the central line of jaws frame and the second group of jaws frame together form a rocker arm which is articulated around a horizontal axis passing through the rocker arm/carriage connecting shafts, which rocker arm is operated in rotation by rocker arm cylinders interposed between itself and the connecting shafts;
  • the central line of jaws is carried by a jaw-carrying head, itself carried by the central line of jaws frame via an oscillation axis associated with one or more oscillation cylinders interposed between said central line of jaws frame and said jaw-carrying head;
  • The jaw-carrying head comprises bending cylinders for bending the central line of jaws;
  • the drawing machine comprises a support beam arranged to bear on the top of said complete line of jaws configured in a straight line, to take up the vertical forces applied thereto.

Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways as long as they are not incompatible or mutually exclusive.

DETAILED DESCRIPTION OF THE INVENTION

Furthermore, various other features of the invention become apparent from the attached description made with reference to the drawings which illustrate one non-limiting embodiment of the invention, and where:

• • FIG. 1 is a schematic side view of a possible embodiment of a machine for forming sheet metal by drawing according to the invention, here without any forming tool and the lines of jaws being spread apart, and in transverse drawing configuration;

FIG. 2 is a schematic top view of the forming machine illustrated in FIG. 1;

FIG. 3 is a schematic cross-sectional front view of the forming machine illustrated in FIGS. 1 and 2;

FIG. 4 is a schematic cross-sectional side view of the forming machine illustrated in FIGS. 1 to 3, in transverse drawing configuration, equipped with a forming tool, and with two closely spaced lines of jaws;

FIG. 5 is a schematic top view of the forming machine illustrated in FIG. 4;

FIG. 6 is a schematic cross-sectional side view of the same forming machine, here in longitudinal drawing configuration and equipped with a forming tool;

FIG. 7 is a schematic top view of the forming machine in FIG. 6 (with forming tool and in longitudinal drawing configuration);

FIG. 8 is a partial schematic top view of the machine in FIGS. 6 and 7 (longitudinal drawing configuration) illustrating the possible oscillating movement of the lines of jaws;

FIG. 9 is a partial schematic top view of the machine in FIGS. 1 to 5 (transverse drawing configuration) illustrating the possible angulation movement of the lines of jaws;

FIG. 10 is a schematic cross-sectional front view of the machine in FIGS. 6 and 7 (longitudinal drawing configuration) illustrating the possible rotational movement of the lines of jaws;

FIG. 11 is a schematic view that illustrates the possibilities of curvature of the lines of jaws in longitudinal drawing configuration.

The machine 1 for forming sheet metal by drawing illustrated in the attached figures is structured so that it can be configured for the longitudinal drawing mode or for the transverse drawing mode.

This forming machine 1 comprises a machine frame 2 having a central longitudinal axis 3 and a central transverse axis 4.

The machine frame 2 is equipped with a table structure 5 for receiving a forming tooling 6 placed between two lines of drawing jaws 7 arranged opposite each other and supported by mechanical means 8 allowing their movement in space.

The sheet metal drawing means, located on either side of the table structure 5 equipped with the forming tooling 6, are identical or similar.

The table structure 5 here comprises a central table 51 positioned on the central transverse axis 4 and bordered by two auxiliary tables 52.

The central table 51 and the two auxiliary tables 52 are controlled in vertical movement by guides 53 and operating cylinders 54.

The active face of the forming tooling 6 is adapted according to the final shape of the sheet metal parts to be obtained. FIGS. 4 and 5 illustrate a forming tooling 6 adapted for transverse drawing; and FIGS. 6 and 7 illustrate a forming tooling 6 adapted for longitudinal drawing.

The means for drawing the sheet metal consist of two lines of jaws 7 facing each other, carried by mechanical means 8 which are adapted to give it the desired spatial movements.

These lines of jaws 7 are designed to clamp the width edge of the sheet metal being worked, by gripping it. Here, each one consists of a juxtaposition of jaws 71, 72 and they are arranged in a plane perpendicular to the direction of drawing, or substantially perpendicular to this direction of drawing (this direction of drawing being placed on the central longitudinal axis 3), to properly fulfill their function.

According to the invention, the lines of jaws 7 have an adjustable length, and each one of them comprises:

• • a first group of jaws 71a arranged in a line, which first group of jaws 71a is designed to allow the forming of a sheet by longitudinal drawing, the line of jaws of this first group of jaws 71a, called the central line of jaws 71a, comprising two end jaws 71b, and
  • a second group of jaws 72a comprising at least two jaws 72 suitable for being in:
  • (a) an inactive position in which the jaws 71 of the first group of jaws 71a are positioned at a distance from the jaws 72 of the second group of jaws 72a, to allow the central line of jaws 71a to perform a forming of a sheet by longitudinal drawing, and
  • (b) an active position in which the jaws 72 of the second group of jaws 72a are positioned in line on either side of said first group of jaws 71a, in line with the two end jaws 71b of the first group of jaws 71a,
  • the resulting line of jaws, called the complete line of jaws 7c, comprising said first group of jaws 71a and said second group of jaws 72a, being designed to allow the forming of a sheet by a transverse drawing.

The jaws 71 of the central line of jaws 71a are carried by a jaw-carrying head 10, itself carried by a central line of jaws frame 11 by means of a vertical or approximately vertical oscillation axis 12, associated with oscillation cylinders 13. These oscillation cylinders 13 are designed to allow the jaw-carrying head 10 to rotate about the oscillation axis 12.

The jaw-carrying head 10 comprises bending cylinders 101 for bending the central line of jaws 71a, as illustrated in FIG. 11.

For this purpose, the juxtaposed jaws 71 of this central line of jaws 71a are articulated in pairs and subjected in pairs to the action of a bending cylinder 101.

The central line of jaws frame 11 has a rear extension (opposite the associated line of jaws 71a), in the form of a cylindrical guide column 14 with a horizontal or approximately horizontal axis.

This guide column 14 is centered or approximately centered on the central longitudinal axis 3.

For their part, the jaws 72 of the second group of jaws 72a are supported by a second group of jaws frame 15 in the general shape of a U.

This second group of jaws frame 15 comprises a base 151 which extends into two lateral extensions 152 at the distal ends of which are provided the jaws 72 of the second group of jaws 72a.

Each one of these distal ends supports at least one jaw 72. For example, each one of these distal ends supports two juxtaposed jaws 72, attached to said distal ends (FIG. 10 in particular).

The cylindrical guide column 14 of the central line of jaws frame 11 slides and rotates through the base 151 of the second group of jaws frame 15, and the forming machine 1 comprises:

• • means of translational maneuvering 16, interposed between the base 151 of the second group of jaws frame 15 and the free end of the guide column 14 (located on the other side of the base 151 of the second group of jaws frame 15 with respect to the central line of jaws frame 11), and
  • means for rotational maneuvering 17 of the guide column 14, also interposed between the base 151 of the second group of jaws frame 15 and the free end of the guide column 14.

The translational maneuvering means 16 consist of cylinders, for example two of them. They allow the two groups of jaws 71a and 72a to be moved closer together or further apart to obtain the aforementioned active and inactive positions.

They constitute the aforementioned means of movement, for the relative movement of the central line of jaws frame 11 and the second group of jaws frame 15.

These cylinders 16, also called drawing cylinders 16, are also used for sheet metal drawing operations, in longitudinal drawing mode.

The means of rotational maneuvering 17 here consist of a single cylinder 17. Alternatively, several cylinders 17 can be used.

The distal ends of the lateral extensions 152 of the second group of jaws frame 15 are carried by support carriages 18, movable along two longitudinal beams 21, constituting the machine frame 2, and which extend parallel to the central longitudinal axis 3.

The support carriages 18 are maneuverable along the length of the longitudinal beams 21 by means of carriage cylinders 181.

The central line of jaws frame 11 and the second group of jaws frame 15 together form a rocker arm which is articulated around a horizontal (or approximately horizontal) axis passing through rocker arm/carriage linkage means, in the form of connecting shafts 182, 183.

This rocker arm 11-15 is operated in rotation by rocker arm cylinders 19 interposed between itself and the connecting shafts 182, 183.

The forming machine 1 further comprises a support beam 20 arranged to bear on the top of each complete line of jaws 7c (with all jaws 71 and 72 aligned in a straight line), for operation in transverse drawing mode.

This support beam 20 allows the vertical forces applied to the complete line of jaws 7c to be absorbed during forming maneuvers.

It is made to be joined to the distal ends of the lateral extensions 152 in the forming configuration by a transverse drawing.

Such a configuration, with the support beam 20 in the active position, is illustrated in particular in FIGS. 1, 3, and 4.

The machine 1 for forming sheet metal by drawing according to the invention is illustrated in transverse drawing configuration in FIGS. 1 to 5 and 9.

In this transverse drawing configuration, the jaws 71 of the first group of jaws 71a are aligned; and the jaws 72 of the second group of jaws 72a extend the two end jaws 71b and are aligned with them. This results in a complete, straight line of jaws 7c. The support beam 20 is positioned resting on top of this complete line of jaws 7c.

This alignment of the first and second groups of jaws 71a, 72a is obtained by the operation of the drawing cylinders 16 and the appropriate configuration of the line of jaws frames in rotation and oscillation.

Starting from a position far apart from the two lines of jaws 7 facing each other, as illustrated in FIGS. 1 and 2, the two lines of jaws 7 are brought together by means of the carriages 18 operated by the carriage cylinders 181, to obtain the close position illustrated in FIGS. 4 and 5, on either side of the forming tooling 6.

The edges of the sheet metal to be formed can then be supported by the two lines of jaws 7; and this sheet metal can be formed on the forming tooling 6 using:

• • the rocker arm cylinders 19 and the table cylinders 54, for vertical movements and rotation around the central longitudinal axis 3,
  • the drawing cylinders 16 and the carriage cylinders 181, for horizontal movements, and
  • the carriage cylinders 181 for the angular movements, by a different movement of the carriages 18, as illustrated in FIG. 9 (rotational movement around a vertical axis of a carriage called “reference carriage”).

The machine 1 for forming a sheet metal by drawing according to the invention is illustrated in longitudinal drawing configuration in FIGS. 6, 7, 8, 10, and 11.

In this longitudinal drawing configuration, only the jaws 71 of the first group of jaws 71a are used; and these jaws 71 of the first group of jaws 71a are separated from the jaws 72 of the second group of jaws 72a, the latter being positioned in the background.

This retraction of the jaws 72 of the second group of jaws 72a is obtained by a maneuver of the drawing cylinders 16, guided by the guide column 14 and the appropriate configuration of the frames 8 of lines of jaws 7 in rotation and oscillation.

Starting from a position far from the two lines of jaws 7 facing each other, the two lines of jaws 7 are brought together by means of the carriages 18 operated by the carriage cylinders 181, to obtain the close position illustrated in FIGS. 6 and 7, on either side of the forming tooling 6.

The edges of the sheet metal to be formed can then be supported by the two lines of jaws 7; and this sheet metal can be formed on the forming tooling 6 using:

• • the rocker arm cylinders 19 and the table cylinders 54, for vertical movements and rotation around the central longitudinal axis 3,
  • the drawing cylinders 16 and the carriage cylinders 181, for horizontal movements,
  • the oscillating cylinders 13, for the oscillating movement of the lines of jaws 71a with the aligned constituent jaws 71, around the oscillating axis 12 (as illustrated in FIG. 8),
  • the rotation cylinder(s) 17, for the rotational movements of the lines of jaws around the axis of the guide column 14 (as illustrated in FIG. 10),
  • the bending cylinders 101, for the bending operation of the central lines of jaws 71a (as illustrated in FIG. 11).

The result is a sheet metal forming machine that is particularly versatile and very easy to configure for transverse or longitudinal drawing.

In particular, it allows for small radii of curvature for longitudinal drawing while maintaining a significant line of jaws length for transverse drawing.