US20120198902A1

US20120198902A1 - Method and device for complex forming a metal sheet by means of bodies of revolution

Info

Publication number: US20120198902A1
Application number: US13/501,391
Authority: US
Inventors: Guenter Eilers
Original assignee: Ostseestaal GmbH and Co KG
Current assignee: Ostseestaal GmbH and Co KG
Priority date: 2009-10-13
Filing date: 2010-10-11
Publication date: 2012-08-09
Also published as: DE102009049297B3; WO2011045261A1; EP2488315A1

Abstract

A metal sheet is formed by passing it between a pair of closely spaced shaped bodies fixedly mounted on driving shafts by intermediate pieces which limit the angular portion of the circumferences of the shaped bodies with which the sheet comes into contact. The configuration of the surfaces of the shaped bodies define the respective top and bottom surface configurations imparted to the sheet by being passed between the rotating shaped bodies with pressure, and, optionally, heat. The direction of rotation of the shaped bodies is reversed, without the application of pressure to the sheet, to bring the sheet back to a starting position for each repeated pass of the sheet through the shaped bodies thereby to progressively change thickness and/or shape of the sheet.

Description

BACKGROUND OF THE INVENTION

The invention relates to a method for forming a metal sheet, in particular a plate, using bodies of revolution in which the end products can have both variable material thicknesses and multi-axial curvatures. At the same time, the invention relates to a device by means of which the method can be carried out.
In the metal processing industry efforts are being made to shape component parts proportionate to the loads acting upon them. Then, the thickness of material and shape are the most important parameters aside from the quality of material.
Thus, there are various shaping manufacturing processes. Component parts, in particular for wind turbine generator systems or shipbuilding, often have to pass through many such processes until the end product is finished.
First of all, die forging can be mentioned by means of which compact component parts having restricted dimensions are formed, such as stub axles, connecting rods or crankshafts. The invention according to DE 70 05 237 U is an example of a plurality of die forgings.
The restricted component dimensions resulting from the forming forces to be applied when die forging are disadvantageous. In addition, considerable forces have to be applied in order to achieve forming the workpieces.
Workpieces are allowed to be brought into a curved shape by means of bending presses. However, bending presses are well known in the metal processing industry long since. Document DE 60 2004 002 860 T2 can be mentioned as an example.
Disadvantageously, only curved metal sheets can be fabricated with bending pressing. However, a change of the component thickness is not possible.
In addition, rolling is well known. It serves to fabricate even semi-finished products having a constant or variable metal sheet thickness. Thus, e.g. document DE 101 03 487 A1 shows a method of fabrication of a large-area structure on motor vehicles as well as the large-area structure itself. According to the invention, a workpiece is provided with defined, locally limited variable material cross-sections arranged any way through rolling. Thus, the surface of the rolls is configured such that certain portions of the workpiece will be submitted to deformation in a differently strong manner.
As a result, deformations in the longitudinal and transverse directions of the plate can be sequentially carried out, and an associated change of the material thickness can separately take place. If a workpiece is to be deformed both in the longitudinal and transverse directions of the plate, these operations have to be carried out sequentially which is disadvantageous. Moreover, the invention according to DE 101 03 487 A1 is restricted to the thin panels used in automotive engineering, which are particularly easy to process.
In document DE 101 13 610 A1 a method of forming thick profiled, integral panels is disclosed. It is characterized in that forming is being performed in areas, and a three dimensional thickness profile arbitrarily both in the longitudinal and transverse directions is being formed by defined superposition of the forming areas.
To cause a workpiece processed according to DE 101 13 610 A1 to additionally undergo a deformation it has to be fed into a further processing operation in which undesired changes in properties of the material cannot be excluded. The extra cost incurred in this connection from the manpower and additional space required for the second device and time required for the conveying of the workpiece into this device are also of disadvantage.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method by means of which a metal sheet can undergo complex forming in a single processing operation wherein bodies of revolution are used. Forming according to the invention results in an end product which has different material thicknesses over its length and width and which can be characterized by uni-axial or multi-axial curvatures running in the same or different directions.
Another object of the invention is to provide a device by means of which the aforementioned method can be carried out.
To achieve the object a method is provided wherein at least two bodies of revolution bring a workpiece, with application pressure and, if necessary, additionally with heat, into the desired shape.
The method is characterized in that two shaped bodies are initially provided wherein the top surface of an end product which is to be created from the semi-finished product to be worked is imaged on the one shaped body, and correspondingly the bottom surface of this end product is imaged on the other shaped body. The surface structure of these shaped bodies can be formed in an extremely complex manner. The surface structure may reflect, for example, continuous transitions between areas of different material thicknesses of the end product, but sudden discontinuities of material thickness can be given in the form of sharp edges as well. Moreover, along the circumference across the width of the shaped body it is possible to apply a contour which imparts the desired curvature to the semi-finished product in a direction transverse to the working direction. The circumference of the shaped body is longer than the end product by the width of a constructional intermediate piece. Thus, it is ensured that the end product does not undergo unintentional shaping.
The shaped bodies being formed as described will now be aligned in a given neutral position on top of each other. Depending on the structurally predetermined material thickness of the end product the forming process is started. The forming process itself is divided up into forming phases. These are defined either by a fixed angle or an area of equal material thickness being predetermined by the end product. The forming phases again are divided into one or several rotational roll passes which prevent unwanted material movements during the forming process and which are admitted by a previously defined working direction of the forming pressure. If this pressure upon the semi-finished product does not result in the desired forming objective of this forming phase so the operation of rotational roll pass will be repeated n times until the forming objective is achieved. Only then the forming operation will be repeated in the following forming phases. If the product is finished, it can be removed from the device. However, it is also possible further steps to occur on the end product as desired. Thus, e.g., side-trimming or undercut can immediately take place.
Forming depending on the temperature during cold forming, medium-temperature forming or warm forming takes place in a manner as needed by the requirements on the end product as well. Thus, particular material properties can be influenced by thermal head.
This solution of the objective according to the invention is advantageous in that the workpieces cannot only be submitted to a multi-axial curvature but also to a complex distribution of material thickness.
With this type of forming it is of advantage that the forming process has a finished end product of complex shape made in one working procedure from an even sheet having a constant thickness. Thus, several processing operations can be avoided up to the finished end product, which reduces the production time.
With respect to the device the object is achieved by the combination of two or more bodies of revolution which reproduce the accurate shape of the end product on their surfaces. By means of a synchronous drive system it is ensured that propulsion of the workpiece and rotary motion of the bodies of revolution are already coordinated like that, and thus the end product can be produced with high accuracy. The device can be supplemented by further devices for side-trimming or undercut.
The invention will be described in more detail according to an embodiment. In the associated drawings

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an oblique view of the device according to the invention;

FIG. 2 shows a side view of the device according to the invention in the working direction;

FIG. 3 shows a side view transversely to the working direction of the device according to the invention;

FIG. 4 shows a plan view upon the device according to the invention;

FIG. 5 shows an oblique view of the device according to the invention having means for side-trimming the workpiece;

FIG. 6 shows a plan view upon a shaped body with sectional data;

FIG. 7 shows a side view of a workpiece worked with the device including sectional data;

FIG. 8 shows views of the sections from FIG. 6;

FIG. 9 shows a plan view upon a workpiece worked with the device and having a varying workpiece thickness including sectional data;

FIG. 10 shows a sectional view taken along line A-A from FIG. 7;

FIG. 11 shows a sectional view taken along line B-B from FIG. 7;

FIG. 12 shows an oblique view of the workpiece worked with the device.

DETAILED DESCRIPTION OF THE INVENTION

It is common to FIG. 1 to FIG. 6 that the shaped bodies (1) and (2) are shown with a highly simplified shaping surface. However, it is conceivable that shoulders are present in the shaping surface of the shaped bodies (1) and (2) such that discontinuities in the material thickness of the workpiece can be achieved. Moreover, non axialsymmetric shaped bodies may be disposed on the receiving shafts (3) and (4) instead of the simplifiedly illustrated shaped bodies (1) and (2). It is merely required that the two shaped bodies (1) and (2) are adjusted to each other such that the intended shape of the workpiece (5) will be obtained after the end of the forming process.
FIG. 1 shows an oblique view upon the device according to the invention. The main constituents of the device are bodies of revolution which primarily comprise shaped bodies (1) and (2), being supported on receiving shafts (3) and (4), respectively. The first receiving shaft (3) and the second receiving shaft (4) are movable to each other such that between the first shaped body (1) being fixed on the first receiving shaft (3), and the second shaped body (2) being fixed on the second receiving shaft (4), a gap is developed through which the workpiece (5) can be inserted into the device. The first shaped body (1) is configured in its shaping surface (17) such that, starting from the front end of the constructional intermediate piece (6) around the shaped body (1) up to the end of the constructional intermediate piece (6), the surface (17) of this first shaped body (1) unrolled into a plane exactly corresponds to the desired top surface of the end product which is to be made from the workpiece (5). Likewise, the surface (17) of the second shaped body (2) unrolled into the plane, starting from the front end of the second constructional intermediate piece (7) around the second shaped body (2) up to the end of the constructional intermediate piece (7), is to exactly correspond to the desired bottom surface of the end product. Respective pieces (6) and (7) fasten respective shaped bodies (1) and (2) to respective shafts (3) and (4)
In a starting position, before the forming process, the constructional intermediate pieces (6) and (7) exactly face each other. During forming the workpiece (5) is brought to the proper thickness and shape through the shaped bodies (8) being rotatable around the axes of rotation (8) together with pressure and/or heating, the workpiece (5) being provided with a curvature in at least one direction. Under certain circumstances an end product of the proper thickness can be produced from the workpiece (5) in one working step. Generally, the workpiece is gradually brought to the desired thickness. To avoid displacement of metal of the sheet parallel to the axes (8) pressure is applied on the workpiece (5) only when driving takes place in the working direction (16). The bodies of revolution must have synchronized drive systems (not illustrated herein). If additional passes (13), (14) between the rotating shaped bodies (1), (2) are required within a forming phase (12), then resetting the workpiece into the starting position of the workpiece at the shaped bodies is carried out without applying pressure on the workpiece (5). This likewise applies to further passes (15) of the workpiece (5) between the shaped bodies (1), (2).
FIG. 2 shows the device according to the invention in a side view facing the working direction (16). The receiving shafts (3) and (4), respectively, rotating around the axes of rotation support the shaped bodies (1) and (2), respectively. The shaping surfaces (17) located on the shaped bodies (1) and (2) are configured such that the workpiece (5) inserted into the device obtains the desired shape. The circumference of the shaped bodies (1) and (2), respectively, is longer by the width of the respective constructional intermediate pieces (6) and (7), respectively, than the end product.
FIG. 3 also shows a side view though illustrating the device according to the invention from a direction transverse to the working direction (16). The second shaped body (2) is behind the first shaped body (1). Between the two shaped bodies (1) and (2) the workpiece (5) is inserted into the device according to the invention.
In FIG. 4 the device according to the invention is further illustrated. Two shaped bodies (1) and (2) each having a different surface but cooperating with each other are coupled with receiving shafts (3) and (4). A workpiece (5) inserted in the working direction (16) leaves the device with desired forming, thus with different thicknesses and with a required curvature. The plastic surfaces (17) are configured such that, if unrolled, they result in the desired top surface and bottom surface, respectively, of the end product fabricated from the workpiece (5). Constructional intermediate pieces (6) and (7), respectively, are inserted into the shaped bodies to define by their one extremity the starting position prior to processing, and, likewise, the end of the processing operation by their opposite extremity. During the rotation of the receiving shafts (3) and (4) by means of drive systems the shaped bodies (1) and (2), respectively, which are disposed on the receiving shafts (3) and (4), respectively, have to be moved with a high precision to ensure that the desired top surface and the desired bottom surface of the end product correspond with each other. As a result, synchronized drive systems have to be used, particularly as with several rotational roll passes, repeated resetting to a starting point is required without applying pressure to the workpiece (5).
FIG. 5 shows a view which is almost identical with FIG. 1 apart from the side-trimming devices (18) being additionally shown herein.
In FIG. 6 a shaped body can be seen. The sections indicated here correspond to FIG. 7 and FIG. 8. The workpiece (5) in FIG. 7 has a thickness increasing over its length and is curved both in the longitudinal and transverse directions as can be inferred from FIG. 8.
On the other hand, in FIG. 9 a workpiece (5) can be seen which has been processed to produce more than a single change of thickness. As can also be seen in the views of FIG. 10 and FIG. 11, showing the sections indicated in FIG. 9, there is a wavy thickening (9) in the working direction as well as a wavy thickening (10) transverse to the working direction and centrally arranged on the workpiece. Moreover, several discontinuities of material thickness in the form of edges (11) are worked into the workpiece transversely to the working direction.
From FIG. 12 it is seen that the workpiece (5) shown in FIG. 9 also comprises curvatures in the longitudinal direction. The shaped bodies used for processing this workpiece (5) thus have approximately an s-shaped shaping surface (17) which comprises respective depressions and elevations to form the thickenings (9) and (10), respectively, and edges (11).

Claims

1.-13. (canceled)

14. A method for complex forming a metal sheet, comprising

in a first phase, providing two mutually spaced receiving shafts with respective shaped bodies, surfaces of the respective shaped bodies being configured to replicate a desired end product, and positioning said shaped bodies relative to each other to receive therebetween a metal sheet as a workpiece;

in a second phase, aligning said shaped bodies so that they face each other in a predetermined neutral position and inserting a leading edge of said workpiece between the shaped bodies in said neutral position;

in a third phase, effecting a first stage of forming by feeding the workpiece in a feeding direction between the shaped bodies under pressure while rotating the shaped bodies thereby to change at least one of thickness and contour of the workpiece, removing the workpiece by releasing the pressure and rotating the rolls in a direction which moves the workpiece in a direction opposite the feed direction; and

optionally, in a fourth phase effecting at least one further forming stage by repeating the first stage so that the shape and/or contour of the workpiece is changed progressively.

15. The method according to claim 14, further comprising

effecting a pre-forming stage before the first forming stage or a post-forming stage after an otherwise last forming stage with substitution of at least one of said shaped bodies with a differently configured shaped body.

16. The method according to claim 14, further comprising

trimming at least one side edge of the workpiece.

17. The method according to claim 16, further comprising

forming at least one undercut on the workpiece.

18. The method according to claim 14, further comprising

heating said workpiece while subjecting said workpiece to pressure.

19. The method according to claim 14, further comprising

in each forming stage, contacting the workpiece with a same portion of the circumference of each of the bodies.

20. Apparatus for complex forming a metal sheet, comprising

a pair of shaped bodies fixed onto respective rotationally driven shafts by respective intermediate pieces fixedly connecting the shaped bodies to the respective shafts, surfaces of the respective bodies extending circumferentially between but not including the intermediate pieces and the surfaces being contoured to conform to the configuration of respective top and bottom surfaces of a metal sheet to be formed by the shaped bodies, the shaped bodies facing each other with the respective axis of rotation of each parallel to the axis of rotation of the other to receive the sheet therebetween while the shafts and, therewith the shaped bodies, are rotated in a direction to feed the sheet between the shaped bodies while pressure is applied to the sheet by the shaped bodies to contour and/or change thickness of the sheet by means of the contoured surfaces of the bodies, the shaped bodies having a neutral position in which the intermediate pieces are in registry with each other, thereby assuring that each pass of a sheet through the apparatus will match each preceding throughpass.

21. The apparatus according to claim 20,

further comprising at least one device for trimming a side edge of the sheet.

22. The apparatus according to claim 20, wherein

a surface of at least one of the bodies is configured to form an undercut on the sheet.