WO2007082972A1 - Machine for shaping sheet metal and shaping method - Google Patents

Abstract

The machine comprises securing means (2) that secure a metal sheet (1), substantially at its perimeter, a first tool (3) arranged on a first side of the metal sheet (1), provided with at least three degrees of freedom corresponding to movements along the X, Y and Z axes, and a second tool (3’), arranged on an opposite side from the first side of the metal sheet, provided with at least two degrees of freedom corresponding to movements along the X and Y axes. Between the second tool (3’) and the securing means (2) there is a relative movement along the Z axis.

Description

 MACHINE FOR SHEET CONFORMING AND PROCEDURE OF

CONFORMED

D E S C R I P C I Ó N

OBJECT OF THE INVENTION

The present invention is applicable to the manufacture of parts according to an incremental process of treatment of metal sheets or plates.

The object of the invention is a machine and a method for forming sheet metal in which no matrices are used and in which two mobile tools are used that act, in combination, on both sides of the sheet for timely and progressive deformation until conform the final shape of the piece.

BACKGROUND OF THE INVENTION

The pieces produced by deformation of metal sheets used in industrial sectors such as automotive, aeronautics and others, are generally obtained by stamping processes. The stamping operation requires the use of a press and two dies or dies, upper and lower, which reproduce the shape that is to be obtained from the sheet. These dies or dies are especially expensive and are only amortized when used for the manufacture of large volume series of parts.

On the other hand, there are certain industrial sectors in which the manufacture of very short series of parts is demanded, for example prototypes, products with a high degree of customization or specific components, which do not justify the investment in matrices used in a conventional stamping process.

In this context, an incremental sheet forming technology is known that is based on the local plastic deformation of a metal sheet by the action of a mobile tool that forms the sheet against supports or dies that have a simpler geometry than what they require. stamping dies, which normally show the exact geometry of the piece to be formed.

The incremental forming process is much slower than conventional printing, but it requires a much smaller investment in matrices, which is supposed to be profitable in the case of short series production.

This process is also characterized by its great flexibility, since the fact of not requiring matrices with the exact geometry of the piece allows the same matrix to be used to form pieces of different geometries and it is also easier to make changes in the design of the piece. Once the matrices have been manufactured.

According to this method, the sheet is held by a perimeter frame and the tool can be moved along the entire surface of the sheet.

This technology is applicable in any sector and the only requirement that arises for its use is that the material must be ductile. Stainless steel parts, low carbon steels and various types of aluminum that have been manufactured with this technology are known. According to these methods, costs are reduced, with respect to conventional stamping processes, by eliminating one of the matrices, however the cost associated with the use of a fixed lower die is still high, especially when it comes to obtaining a piece of complex geometry

In the patent of invention EP 0 970 764 for example an apparatus for the forming of sheets is described which comprises an upper punch with displacements in X, Y, Z and a lower die that can move in the direction of the Z axis for the forming of The piece. This same solution is reflected in the invention patent JP 2002102944.

In the invention patent JP 2003053436 it is contemplated that the lower matrix is movable in the vertical direction by the action of a cylinder.

In the case of the invention patent JP 7 132 329 the essence of the patent EP 0 970 764 is maintained, but unlike this, the lower matrix consists of a punch. The vertical movement of the mechanism that holds the plate, in combination with the movement of the upper punch against the plate in contact with the fixed lower punch, determines the shape of the piece.

This same system is used in the invention patent 2003080320.

On the other hand, in the patent of invention JP 2000153313 a device is provided with a tool that is equipped with a rotating movement that is applied under pressure on the contour of the piece to be obtained, which is supported by its lower face on a fixed tool located in opposite arrangement to the incremental tool.

In the invention patent JP 9 085 355 an apparatus is also described which is provided with an upper punch that moves in the vertical direction and a lower punch provided with movement in the direction of the X-axis, Y and Z.

In the invention patent WO 92/07672 the sheet to be formed has a relative movement, in X and Y, with respect to an upper tool and a lower die. The upper tool and the lower die are provided with a vertical displacement along the Z axis.

DESCRIPTION OF THE INVENTION

The invention described below is applicable for forming metal sheets or plates by means of the progressive or dynamic action produced by two tools located on both sides of the sheet, which are shaping the material while moving in a coordinated manner on the sheet following specific paths to obtain the final geometry of the piece, by deformations of the sheet, punching or grooving and even trimming the outer edges of the sheet.

The machine of the invention comprises:

- fastening means that hold a sheet, substantially on its perimeter,

- a first tool arranged on a first side of the sheet,

- a second tool arranged on an opposite side to the first side of the sheet,

According to the object of the invention, the first tool is provided with at least three degrees of freedom, corresponding to displacements along the X, Y, Z axis, and the second tool is provided with at least two degrees of freedom, corresponding to displacements along the X and Y axes, there being a relative displacement along the Z axis between the second tool and the clamping means.

It is preferably contemplated that the second tool is also provided with a movement of movement along the Z axis. In this case, the fastening means of the sheet remain fixed.

In this way, the first tool and the second tool define a combined path on both sides and in contact with the sheet, causing the occasional deformation of the sheet in each sector according to the intended design to form the final piece.

The first and / or the second tool may comprise any of the following elements: a punch, a drill, a mill, a welding head or a laser head, to perform all kinds of operations on the sheet, such as deformations, grooves, holes , cuts, final trimming of the outer edge of the piece, heating on the sheet, welding, until the desired final shape for the piece is achieved.

When punches are used, their size varies depending on the application that is desired to be provided thereto and will preferably incorporate a spherical tip.

The possibility is also contemplated that the first and / or the second tool rotate with respect to its own axis and that the speed of rotation of the first and second tools are the same or different.

Depending on the particular geometry of each piece it is possible to form the sheet in a single stage or it may require several stages. The use of several stages is derived from the need to increase the plastic limit so that angles and geometries are obtained that cannot be achieved in one stage. The machine can incorporate a lubrication device that applies lubricant on the sheet, either directly or through the first or second tool, for example by means of an internal duct that flows into a sphere whose rotating movement distributes the lubricant on the sheet.

In accordance with the invention, the machine comprises fastening means that hold the sheet by its periphery, forming a frame provided with a wide opening, which defines the work area in which the tools move during the forming of the piece. The machine can comprise piezoelectric actuators that hold the sheet by several points and sensors that detect the tensions of the sheet and transmit the information to a controller that acts on the piezoelectric actuators to vary the clamping force of the sheet allowing more or more flow less material towards the sector that is being formed.

The controller will be able to execute a program derived from a 3D CAD / CAM that will contain the information of the positions and speeds of the different axes of each of the tools and will therefore act by directing the trajectory and speed of the first and second tools . The controller can also act on the force that the piezoelectric actuators that hold the sheet must exert.

The forming process according to the present invention can therefore proceed according to the following phases:

- mooring of the sheet, on its periphery, by means of fastening, leaving free the working area of the sheet,

- positioning of a first tool on a first side of the sheet, corresponding to the work area,

- positioning of a second tool on a side opposite the first side of the sheet, corresponding to the work area,

- definition of the trajectory of the first and second tools through a CAD / CAM program,

- displacement of the first tool, according to the X, Y, Z axes on one side of the sheet and the second tool according to the X and Y axes, on the other side of the sheet, in accordance with the paths defined by the CAD program / CAM and relative displacement between the second tool and the clamping means, according to the Z axis, to produce a punctual and fundamental deformation of the sheet.

The forming process preferably comprises the displacement of the second tool, along the Z axis, the fixing means remaining fixed.

The forming process further comprises the continuous detection of the stresses in the sheet and the action on the clamping means to vary the clamping force thereof, depending on the tensions detected. In this way, the sheet can flow, to a greater or lesser extent according to the tensions detected, in the deformation zones.

DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, in accordance with a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. where, for illustrative and non-limiting purposes, the following has been represented:

Figure 1.- Shows a perspective view of the elements basic that incorporates a sheet forming machine in which the tools consist of respective punches mounted on heads located on both sides of the sheet.

Figure 2.- Shows a schematic view in which the movements of the tools represented in the previous figure are observed.

PREFERRED EMBODIMENT OF THE INVENTION

Next, with reference to the figures, a preferred embodiment of the sheet forming machine that constitutes the object of this invention is described.

In the represented figures, the basic elements involved in the operation of forming a piece from a sheet (1) according to the invention are observed. In Figure 1, a schematic representation of the machine of the invention is included, comprising:

fastening means (2) that hold the sheet through its perimeter, constituting a perimeter frame (5) that determines a large central space corresponding to the work area on the sheet (1),

- a first tool (3), located next to the sheet (1),

- a second tool (3 '), located on one side opposite the first side of the sheet (1).

The first tool (3) is provided with at least three degrees of freedom along the X, Y, Z and the second tool (3 ') is provided with at least two degrees of freedom corresponding to displacements along the X and Y axes, There is a relative displacement along the Z axis between the second tool (3 ') and the clamping means (2). In a preferred embodiment, the second tool is provided with a movement along the Z axis, while the fastening means (2) remain fixed, as shown in Figure 2.

The fastening means (2) of the sheet (1) can comprise piezoelectric actuators (6) that establish the fastening of the sheet (1) to the perimeter frame (5) with a variable clamping force, so that depending on The tension generated in the sheet, due to the deformation that is being caused, can release the clamping of the sheet allowing it to flow towards the zone of deformation.

The sheet forming machine incorporates a controller (7), represented in Figure 1, which controls the trajectory and speed of the first tool (3) and the second tool (3 ') and the clamping force of the sheet ( 1) exerted by the piezoelectric actuators (6) to regulate the flow of material in the area of the sheet (1) that is being deformed.

The first tool (3) and / or the second tool (3 '), may comprise punches (3, 3'), optionally rotatable, mounted on corresponding heads (4, 4 ') that impact on both sides of the sheet

(1) causing point deformations followed by incremental displacements until the entire piece is formed.

Optionally, the possibility is contemplated that the first tool (3) and / or the second tool (3 ') are additionally provided with rotating movements θ, Φ around the X axis and / or the Y axis respectively.

It is also provided that the first tool (3) and / or the second tool (3 ') may comprise a drill, a mill, a laser head or a welding head.

Claims

1.- Machine for forming sheet metal comprising: • - fastening means (2) holding a sheet (1), substantially in its perimeter, - a first tool (3) arranged on a first side of the sheet 0). - a second tool (3 ') arranged on one side opposite the first side of the sheet, characterized in that the first tool (3) is provided with at least three degrees of freedom, corresponding to displacements along the axes X, Y, Z, and the second tool (3 ') is provided with at least two degrees of freedom, corresponding to displacements along the X and Y axes, there being a relative displacement along the Z axis between the second tool (3 ') and the clamping means (2). 2. Machine for forming sheet according to claim 1 characterized in that the second tool (3 ¹ ) is provided with a displacement along the Z axis, the fastening means (2) remaining fixed. 3. Machine for forming sheet according to claims 1 and 2, characterized in that at least one of the tools (3, 3 ') is rotatable. 4. Machine for forming sheet according to any of the preceding claims, characterized in that at least one of the tools (3, 3 ') is additionally provided with a rotating movement θ around the X axis. 5. Machine for forming sheet according to any of the preceding claims, characterized in that at least one of the tools (3, 3 ') is additionally provided with a rotating movement Φ about the Y axis. 6. Machine for forming sheet according to any of the preceding claims, characterized in that it incorporates a controller (7) that controls the trajectory, speed and movement of the first tool (3) and the second tool (3 '), as well as the clamping force of the clamping means (2) of the sheet (1). 7- Machine for forming sheet according to claims 1-6 characterized in that at least one of the tools (3, 3 ') comprises a punch. 8. Machine for forming sheet according to claims 1-6, characterized in that at least one of the tools (3, 3 ') comprises a drill. 9. Machine for forming sheet according to claims 1-6, characterized in that at least one of the tools (3, 3 ') comprises a milling cutter. 10. Machine for forming sheet according to claims 1-6 characterized in that at least one of the tools (3, 3 ') comprises a welding head. 11. Machine for forming sheet according to claims 1-6, characterized in that at least one of the tools (3, 3 ') comprises a laser head. 12.- Sheet forming process comprising the phases of: - mooring of the sheet (1), on its periphery, by means of fastening (2), leaving a working area free on the sheet (1), - positioning of a first tool (3) on a first side of the sheet (1), in correspondence with the aforementioned work area on the sheet (1), - positioning of a second tool (3 ') on a side opposite to the first side of the sheet (1), in correspondence with the said work area on the sheet (1), - definition of the path of the first and second tools (3, 3 ') through a CAD / CAM program, - displacement of the first tool (3), according to the X, Y, Z axes on one side of the sheet (1) and of the second tool (3 ') according to the X and Y axes, on the other side of the sheet ( 1), in accordance with the trajectories defined by the CAD / CAM program and relative displacement between the second tool (3 ') and the clamping means (2), according to the Z axis, to produce a punctual and incremental deformation of the sheet (one). 13.- Sheet forming method according to claim 12 characterized in that it comprises the displacement of the second tool (3 '), along the Z axis, the fixing means (2) remaining fixed. 14.- Sheet forming method according to claim 12 characterized in that it comprises the continuous detection of the tensions caused in the sheet (1) by the displacement of the first and second tools (3, 3 ') and the action on the fastening means (2) to vary the clamping force thereof, depending on the tensions detected.