WO2008138152A1

WO2008138152A1 - Forming method

Info

Publication number: WO2008138152A1
Application number: PCT/CH2008/000189
Authority: WO
Inventors: Rudolf Lüthi; Andreas Delis; Hans Jöhr
Original assignee: Adval Tech Holding Ag
Priority date: 2007-05-09
Filing date: 2008-04-25
Publication date: 2008-11-20
Also published as: EP2142320A1; EP2142320B1; ATE544538T1

Abstract

A description is given of a method for producing an offset (7) in a metal sheet (2) in a forming process, wherein the sheet (2) is formed in at least one step between a female die (1) with a recess of a predetermined contour (4) and a male die (3) with a peripheral form given essentially by the same contour (4) in a way that guides the contours (4) essentially congruently one on the other. The method is first characterized in that the depth of penetration of the male die (3) into the sheet (2) in a first direction (R1) is set in said first forming process in such a way that a first height (H1), which corresponds essentially to the target height of the offset (7), is reached in the decisive peripheral zones of the offset (7), while the raised surface (8) of the remaining offset (7) reaches a greater height (H). The method is also characterized in that, in a further forming process, the offset (7) is reversed with a resetting die (5), which covers at least said contour (4), in a second direction (R2) counter to the first direction (R1) in such a way that essentially the entire raised surface (8) of the offset (7) is arranged at a second height (H2).

Description

DESCRIPTION

TITLE forming process

TECHNICAL FIELD The present invention relates to a method for producing a dislocation in a sheet in a forming process. This involves a method in which a sheet is formed in at least one step between a die with a recess having a predetermined contour and a punch with a substantially given by the same contour edge shape in the contours substantially congruent leading together manner. Furthermore, the present invention relates to an offset, as can be prepared by such a method or is prepared.

PRIOR ART If displacements with a specific geometry have to be produced in a sheet by non-cutting forming technology, it is decisive what material properties the material has (soft sheet / hard sheet, etc.), how thick the sheet is, how high the offset must be, and which contour geometry must have the offset. In the production of the offset with the aid of a punch and a die, a so-called indentation arises in the edge zone (similar to the punching recess during cutting).

If, for example, a rotationally symmetric offset is produced, the feeder points over the entire circumference of the contour substantially the same geometry.

With different contours of the offset to be produced thereby different indents are generated, which often leads to problems, since just the often decisive for the final function edge region of the displacement is exposed to these indentations.

Insofar as such indentation is not permitted by the component requirements, this indentation can be eliminated or minimized by bulk forming.

In the case of massive forming, the material is plasticized in a die until the die is completely or partially filled. In the case of massive forming, however, such high forces arise in the dies that there is a risk of tool breakage or premature wear.

It may also be that the geometry part (for example, a sharp tooth) can not be filled at all.

Experiments and FEM simulations have shown that e.g. a tooth shape of about 45 ° can only be approximately filled with extremely high pressing forces.

However, these pressing forces are very likely to lead to tool damage in serial production.

In addition, lateral shifts occur in the material which alter the surrounding geometry zones. How high the pressing forces are and how far an offset can be produced depends primarily on the material thickness in relation to the geometry and the offset height.

PRESENTATION OF THE INVENTION

The invention is therefore inter alia based on the object of providing an improved forming process for producing dislocations.

It is in particular to the improvement of a method for producing a dislocation in a sheet in a forming process, wherein the sheet in at least a step between a die with a recess having a predetermined contour and a punch with a normally given by the same contour edge shape in the contours substantially congruent leading one another manner is transformed. An unexpectedly efficient control of the edge regions of the offset, in particular a prevention of indentations is made possible according to the invention in that in this first forming process, the stamp is actually guided too far into the sheet, if one considers the entire raised surface of the offset. However, the punch is guided so far into the sheet that just in the critical edge zones, the indents formed have a height above the sheet, which correspond to the final and actually desired height of the offset. In other words, the penetration depth of the punch is set in the sheet in a first direction in said first forming process such that in the decisive edge zones of the displacement (where said indentations usually occur most strongly), a first height Hl is achieved which substantially Target height of the displacement corresponds, while the raised surface of the remaining displacement can reach a greater height H. In a subsequent forming process, the somewhat too large displacement in the regions which are different from the edge zones is now, as it were, undone. This is achieved in that in a further, the first forming process downstream forming process, the displacement with a reset punch, which covers at least the said contour, in a first direction opposite to the second direction is returned such that substantially the entire raised surface of the offset is arranged at a second height H2. According to a first preferred embodiment, the first height H1 is substantially the same as the second height H2, and thus corresponds substantially to the target height of the offset.

Particularly problematic are the indents mentioned in those areas where the contour over a short edge length makes a strong change of direction (low radii of curvature). Exactly in these areas are usually the indents and the distortions in the peripheral areas. According to a further preferred embodiment of the invention, at least one of the decisive edge zones of the offset is accordingly an area in which the contour has a corner with an angle of <120 °, preferably of <90 °. Particularly critical is the creation of contours with tooth shape. Accordingly, according to a further preferred embodiment, at least one of the decisive edge zones of the offset is at least one tooth form with an angle in the range of 20-70 °, preferably in the range of 30-60 °, particularly preferably in the range of 45 °. A further preferred embodiment of the invention is characterized in that in the first forming process, the die is arranged on a second side of the sheet and substantially adjacent thereto and the punch from a second side of the sheet on this and this in the formation of the offset on the second side is guided, and that in the further forming process on the first side a flat, at least the contour on all sides substantially superior covering flat support is arranged and the reset punch is supplied from the second side of the sheet on the displacement of these transforming.

Typically, the reset punch has substantially the same contour as the offset and is guided substantially congruent thereto. But it is also possible that the reset punch is designed to be much larger and dominates the contour in all directions. Typically, the reset punch is then a flat support.

In order to be able to ensure optimum shaping in the edge region of the offset, it can prove advantageous to define the shaping in the edge region of the offset by a delimitation in the further forming process to a certain extent. This limitation or control form can to a certain extent be a reset die, which has a recess in which the reset punch is guided and whose contour corresponds to the contour of the offset. This reset die is then arranged in the further forming process, the displacement enclosing in contact with the surface of the sheet and the reset punch moves in the recess of the reset die the further forming process.

As a result, in particular in the critical edge regions with large indentations after the first forming process, the material displaced in the further forming process is guided through the reset die into the defined shape.

In other words, it is preferred according to a further embodiment, when the reset punch in the further forming process together with a relative to the reset punch displaceable and during the further forming process in contact with the second side of the sheet substantially not moved with respect to the sheet, and Contour of the displacement is used in substantially enclosing reset die.

This reset die can be the die used in the first forming process. This first die then has the said recess with the contour defining the offset, and in this recess the reset punch is guided. In the first forming process, the reset punch is pushed out of the sheet metal away from this recess so far that essentially no contact can take place between the reset punch and the offset in the first forming process. After the first forming process, the die is then left in place, the punch from the first forming process replaced by a flat support, and the reset punch in the recess of the die for the second forming process led to the offset. Thus, critical tip areas can be "filled" even better by the second forming process.

Normally, therefore, the stamp is preferably introduced in the first forming process with a penetration depth into the sheet, which is greater than the target height of the offset. Preferably, the penetration depth, based on the thickness of the sheet (sheet thickness = 100%), is in a range of 20-70% (this usually involves the risk of punching through). Based on the target height of the offset (target height of the offset above the sheet plane = 100%), the penetration depth is preferably set in a range of 110-400%, more preferably 150-300%, particularly preferably 180-220%. For a target amount of the transfer of 0.5 mm above the sheet plane, for example, the punch in the first forming process in the particular preferred range (180 - 220%) is performed between 0.9 - 1.1 mm deep in the sheet.

Preferably, the proposed method surprisingly allows the contour to have different regions with different and in particular partially low radii of curvature. In this case, the penetration depth of the punch is preferably adjusted so that the first height Hl at the acute-angled point (lowest radius of curvature) of the contour is ensured.

Typically, a sheet which can be subjected to such a process has a thickness in the range of 0.2 - 20 mm, preferably in the range of

0.5 - 5 mm, particularly preferably in the range of 1 - 4 mm. The offset can generally have a target height or a first height H 1 or a second height H 2 in the range from 0.1 to 10 mm, respectively, preferably in the range from 0.2 to 3 mm, or in particular preferably in the range from 0.5 to 2 mm. Typically, for a sheet of 2-4 mm thickness, the first height is 1.5mm, and this first height is then reduced to about half in the second forming process, that is, about 0.7mm.

Furthermore, the present invention relates to an offset preparable or produced by a method as described above. For example, the present invention further relates to a sheet having at least one offset with a row of teeth on at least one side (it is also possible to arrange two such displacements with teeth facing each other), this row of teeth a variety of linear or curved, elliptical or in a circle (to some extent gear) arranged side by side teeth with angles in the region of the tip of <90 °, preferably in the range of 45 °. Such linear or curved rows of teeth can to a certain extent be used as toothed racks for elements to be adjusted relative to one another (for example furniture parts etc., relative adjustment in height or in angle), if, for example, a corresponding stamped sheet metal with teeth on the outer edge or edges another sheet with a corresponding displacement is carried out with teeth. In connection with such devices, for example, a sheet of a thickness in the range of 2-4 mm proves to be advantageous in combination with a final height of the offset in the range of 0.5-1.5 mm. This, for example, for normal loads, such as those exercised by the human or man-operated furnishings, for example, on furniture.

BRIEF EXPLANATION OF THE FIGURES

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it:

1 shows a section through a currently undergoing a forming process sheet; FIG. 2 shows a plan view of a matrix with different contour line areas; FIG.

3 shows detailed sections through the regions A-D indicated in FIG. 2 in a direction parallel to the movement of the forming tool; and FIG. 4 shows the tool guide in a downstream forming step for producing the final shape.

WAYS FOR CARRYING OUT THE INVENTION

As mentioned in the introduction, the so-called indentations in the edge zones in the production of dislocations using forming technology are therefore serious problems.

If, for example, a rectangular offset produced, the indentation in the corners over the straight section is much more pronounced, because the resistance to produce the offset in the material in the corners is greater than the straight sections. If, for example, an offset is now produced with a contour geometry in which individual geometric elements have a smaller angle than 90 ° (for example, a tooth form with an angle of approximately 45 °), the indentation becomes even larger. This is illustrated by way of example in a sectional view perpendicular to the plane of a sheet 2 in FIG. Here it can be seen how a sheet 2, which is subjected to a forming process between a die 1 and a punch 3 to produce a displacement 7 in this sheet 2, forms different shapes in the marginal areas of the displacement, depending on how the contour of Die 1 resp. Stamp 3 is formed.

The illustration of FIG. 1 shows a section which is guided along a line AD in a contour according to FIG. 2 (compare discussion below), that is to say in which a rounded region A is cut on the left side and on the right Side by a pointed tooth area D. Accordingly, on the left side of the formation of the feeder is much less pronounced than on the right side.

In general, in such a method, in principle, a sheet 2 is arranged flush with the die 1 arranged on a second side 10 of the sheet and subsequently from a second side 9 of the sheet, the punch 3 in a direction as indicated by the arrow Rl, fed to the recess of the die 1. The leadership of die 1 and 3 stamp is analogous, as if a hole with this contour should be made in the sheet, the punch 3 is simply not quite as deep in the sheet 2 (penetration depth of the punch 3 less than sheet thickness). In general, such a sheet is, for example, a steel sheet having a thickness in the range of 2 to 5 mm.

Typically, the recess formed in the die 1 has a contour which is identical to the outer contour of the stamp 3. The height H of the offset achieved after the forming operation is not homogeneous over the entire areal extent of the offset. In Fig. 1, the resulting height differences are shown somewhat exaggerated. Thus, there is a raised surface 8, which has the desired height H only in the central central regions, and curvatures or bevels form in the edge regions; these are just the indentations which, depending on the shape of the contour, can have different shapes. So it forms at the most acute angle, which is on the right side is shown, the largest indentation, and accordingly in the edge region at this point, the height Hl is less than the central height H.

This will be explained in detail with reference to Figures 2 and 3.

Figure 2 shows a plan view of an exemplary contour, which is to be produced as an offset in such a forming process. The contour 4 has areas with different edge shapes, so over a circular area, which is denoted by A, over a straight area, which is denoted by B, via a corner

C, in which the outer line is guided with a small radius of curvature substantially at a right angle and further a tooth shape is shown, this is denoted by D, and in this case, the contour with a small

Radius of curvature at an angle of in the range of less than or in the range of 45 ° out.

The different characteristics of the resulting indents will be illustrated with reference to FIG. The lowest indentations are normally generated in the straight areas as represented by B. The present height X of the feeder is small, and the raised surface 8 of the offset 7 is slightly sloping over a substantial range at the desired height and only in a small edge region, and also there only over a small height X. In the round areas A, the height of the indent X becomes somewhat larger during the forming process, while the extent of the indentation in the plane of the sheet still moves in reasonable ranges and is substantially the same as in the straight portions B.

The indentations in the areas with a small radius of curvature are now pronounced. For example, in the area of the corner C, it can be seen how the height X of the indentation begins to make a significant percentage of the actual height of the offset, and also extends substantially into the raised surface 8 of the offset. The height Hl is much smaller than the height H. The sharper the angle of a contour line, the higher the height of the indent X and the farther this indentation also extends into the internal raised surface 8 of the offset, this will be apparent from the situation at D.

This pronounced formation of indentations can now be prevented according to the invention by carrying out the forming process in two steps. A first step is essentially carried out as shown in FIG. 1, but the height H is to some extent carried out excessively, whereby it is taken into account that in the critical edge zones in this first forming process a height H1 is to be achieved, that of the final one desired level of the total displacement, while in all other areas initially a much too high height H of the transfer is accepted.

This displacement, which in principle is much too high, is now to some extent corrected in a subsequent step, the further forming process, as shown in FIG. With the aid of a reset ram 5, the offset 7 is to some extent pressed down again in a corrective manner by the second side 10 of the sheet metal. On the first side of the sheet 9 while a flat support 6 is arranged, which projects beyond the region of the displacement substantially in all directions.

In order to support optimum contour formation, in particular in the region of pointed teeth, it is possible, to a certain extent, to support or limit the offset along the contour formed in the first forming process with a lateral surface in this further forming process. This is possible, for example, by leaving the die 1 used in the first forming process in the position after the forming process, as shown in FIG. 1, and then guiding the reset punch 5 through the recess in this die 1 to the offset. Thus, such a tip (for example, point D) can to a certain extent be very controlled in the further forming process and filled with material.

In other words, the knowledge that the material in sharp corners is very difficult to displace due to the deformation resistance and thus a large indentation, tried, the displacement in a first operation higher training is necessary, but so high that in a top section the offset height approximately corresponds to the demands.

In a second step, the offset is then pressed back to the required height. Since the material in the tip section can not be readily reset by the greater resistance to deformation and, moreover, there is no contact with the return punch 5 in the pull-in section, the tip section remains at the offset height of the first operation.

With this method, the forming forces are reduced by a factor of 4 or higher.

As possible fields of application for the proposed production process, the following products or assemblies are given by way of example:

Positioning of two individual parts (for example, sheet metal) in the form of round cones in which the dislocation must be as sharp as possible and the

Forming forces must not be too high (furniture fittings);

- Mutual teeth for locking a seat adjustment in the office area;

- Dynamically operated as offset trained gears, tooth sets, etc. on larger sheets;

- Mutual teeth for locking a desk height adjustment;

- Mutual toothing for locking a shelf;

- Gears for the locking of steering column adjustments;

- locking of adjustments for lighting elements, such as construction site headlights;

Locking of gears of a height adjustment for lawnmowers and similar construction resp. Garden tools; Locking a height adjustment for trailer auxiliary wheels; Locking a setting for planing machines.

LIST OF REFERENCE NUMBERS

1 die, contour corresponds to the desired geometry

2 umzuformendes, that is to be offset, sheet metal

3 stamp, contour corresponds to the desired geometry 4 contour of the desired geometry

5 reset punch, contour corresponds to the desired geometry

6 flat support

7 displacement

8 raised surface of the offset 9 first side of the sheet

10 second side of the sheet

A round area

B straight area C corner area

D peak area

H Height of the offset after the first forming operation in the area of the raised surface

Hl Amount of displacement after the first forming operation in the area of a critical location

H2 Height of the offset after the second forming operation X Height of the feed in the different areas A-D

Claims

1. A method for producing an offset (7) in a sheet (2) in a forming process, wherein the sheet (2) in at least one step between a die (1) with a recess having a predetermined contour (4) and a punch ( 3) is formed with a substantially by the same contour (4) given edge shape in the contours (4) substantially congruent leading one another manner, characterized in that the penetration depth of the punch (3) in the sheet (2) in a first Direction (Rl) is set in said forming process such that in the decisive edge zones of the displacement (7) a first height (Hl) is achieved, which substantially corresponds to the target height of the offset (7), while the raised surface (8) of remaining displacement (7) reaches a greater height (H), and that in a further forming process, the displacement (7) with a

Reset punch (5), which covers at least said contour (4), in a first direction (Rl) opposite the second direction (R2) is returned such that substantially the entire raised surface (8) of the offset (7) a second height (H2) is arranged.

2. The method according to claim 1, characterized in that the first height (Hl) is substantially equal to the second height (H2).

3. The method according to any one of the preceding claims, characterized in that it is at least one of the decisive edge zones of the offset

(7) is a region in which the contour (4) has a corner with an angle of <120 °, preferably of <90 °.

4. The method according to any one of the preceding claims, characterized in that it is at least one of the decisive edge zones of the offset (7) by at least one tooth form with an angle in the range of 20-70 °, preferably in the range of 30-60 °, more preferably in the range of 45 °.

5. The method according to any one of the preceding claims, characterized in that in the first forming process, the die (1) on a second side (10) of the sheet (2) and disposed substantially adjacent thereto and the punch from a first side (9 ) of the sheet (2) on this and in this

Forming the offset (7) on the second side (10) is guided, and that in the further forming process on the first side (9) a flat, at least the contour (4) on all sides substantially superior covering flat support (6) is arranged and the Resetting punch (5) from the second side (10) of the sheet (2) on the offset (7) is supplied to this transforming.

6. The method according to any one of the preceding claims, characterized in that the reset ram (5) has substantially the same contour (4) as the offset (7) and is guided substantially congruent thereto, wherein the reset ram (5) in the preferred another forming process together with a relative to the reset punch (5) slidably mounted and during the further forming process in contact with the second side (10) of the sheet (2) located, with respect to the sheet (2) substantially not moving, and the contour of the offset (7) essentially enclosing reset die is used, this reset die can be used in the first forming process die (1).

7. The method according to any one of the preceding claims, characterized in that the punch (3) is introduced in the first forming process with a penetration depth in the sheet (2) which is greater than the target height of the offset (7), wherein preferably the penetration depth 110th - 400%, more preferably 150 - 300%, particularly preferably 180 - 220% of the target height of the displacement

(7).

8. The method according to any one of the preceding claims, characterized in that the contour (4) has different areas (AD), and that the penetration depth of the punch is adjusted so that the first height at the acute-angled point (D) of the contour is ensured ,

9. The method according to any one of the preceding claims, characterized in that the sheet (2) has a thickness in the range of 0.2 - 20 mm, preferably in the range of 0.5 - 5 mm, particularly preferably in the range of 1 - 3 mm, and that the offset (7) has a target height or a first height (Hl) or a second height (H2) in the range of 0.1-10 mm, and preferably in the range of 0.2-3 mm, and particularly preferably in the range of 0.5-2 mm ,

10. Verification (7) preparable or produced by a method according to any one of the preceding claims.