Forming process, as well as a suitable forming tool and target contour

Abstract

Forming process for producing a target contour (200) with a large through-hole height, comprising at least the following steps: A. Preforming a volume contour (1) from a sheet blank (2), B. forming approximation to the target contour (200) with a vertical axis (H), wherein a vertically formed side wall (3) of the target contour (200) is still inclined relative to the vertical axis (H) and a horizontal overhang (4) of the sheet blank (2) is present, characterized in that in step C. the target contour (200) is finished by means of a plurality of forming slides (10) performing a horizontal stroke (r), so that the still inclined and / or still curved side wall (3) is aligned parallel to the vertical axis (H), wherein the target contour (200) has an open bottom (5) surrounded by the side wall (3) with a horizontal edge (6) inclined and / or curved towards the center, and in step C.a bottom stamp (11) is placed on a section (7) of the open bottom (5) to be formed, performing a vertical stroke (z), the bottom stamp (11) coming into contact with the section (7) which is still inclined to the horizontal, before the forming slide (10) comes into contact with the side wall (3), and only after completion of the horizontal stroke (r) does the forming slide (10) complete the vertical stroke (z).

Description

[0001] The invention relates to a forming method according to the preamble of claim 1 for producing a desired contour with a large through-hole height. The invention further relates to a forming tool according to the preamble of claim 6 for producing a desired contour with a large through-hole height and a cylindrical desired contour, wherein the cylindrical desired contour has a vertical axis and a maximum cylinder diameter, and the ratio of vertical axis to cylinder diameter is greater than 0.37. Technical field

[0002] The invention relates to a new forming process, which in the broadest sense can be classified as deep drawing. In conventional deep drawing, a sheet metal blank, often referred to as a blank, is placed on a drawing die, and a (pouring) die plunges into the die, thus creating the desired shape or contour in the remaining gap between the die and the die. The sheet metal blank is held in place by a blank holder by means of an overhang on the outer circumference of the die. This prevents the formation of wrinkles.

[0003] A disadvantage of this very simple process is that the drawing height is limited because the forming is achieved through radial tensile stresses (relative to the initially flat sheet metal blank and the overhang). The material thins, and if the drawing height is too great, cracks can form. Therefore, with conventional deep drawing, ratios of height to diameter of a maximum of approximately 2 / 10 can be produced crack-free for a cylindrical target contour; for example, 11 mm height with a diameter of 56 mm.

[0004] This problem can be solved with a forming tool featuring a negative draw gap, for example, a drawing die, where the wall opens conically towards the die relative to the vertical wall of the corresponding die. However, this approach has disadvantages in achieving precise target contours with a desired, e.g., consistent, wall thickness. Furthermore, the height-to-diameter ratio is only increased to a maximum of 0.3%. State of the art

[0005] From DE 100 20 176 A1, a method for manufacturing a disc with a thickened hub by deep drawing is known. It describes how a cylindrical component with a wall thickness increased compared to the sheet metal blank can be produced by multiple forming steps. A similar process is disclosed in DE 103 44 885 B3, which deals with a method for manufacturing a workpiece with a hub using a press and a sheet metal workpiece. Fig. One of the two cited documents shows the first seven steps (DE 100 20 176 A1, references 7a to 7g) or the first five steps (DE 103 44 885 B3, references 7a to 7e) before the forming steps for increasing the wall thickness are initiated. These steps are not explained in detail. These documents are referenced with regard to the respective Fig. 1 It can therefore be deduced that up to six forming steps, i.e. up to six tools, are necessary to achieve the desired ratio of vertical axis to diameter in order to reach a desired diameter. Object of the invention

[0006] The invention is based on the objective of reducing the number of steps and tools required to produce a desired contour with a large draft height in a forming process of the type mentioned above. A further objective is to achieve draft heights that were previously unattainable by deep drawing. Solution to the task

[0007] This problem is solved by the features specified in claim 1, namely by forming the desired contour by means of a plurality of form slides performing a horizontal stroke, so that a still inclined and / or still curved side wall is aligned parallel to the vertical axis.

[0008] Furthermore, the problem is solved by the features specified in claim 6, namely by providing a forming tool with at least the following components: - a hold-down surface for placing a volume contour approximating the target contour with a horizontal overhang of a sheet metal blank; - a plurality, preferably four, of form slides for performing a horizontal stroke, wherein the overhang between the hold-down surface and the form slides is held and the form slides are arranged to slide over the overhang.

[0009] Furthermore, the problem is solved with a target contour of the type mentioned above, which is produced by means of the aforementioned forming process, and preferably by means of the aforementioned forming tool.

[0010] Advantageous embodiments of the invention are characterized in the dependent claims.

[0011] These measures ensure that a forming process can be carried out cost-effectively in just three steps, i.e. with three forming tools, and with a very high throughput height, such that the probability of cracking is 0%. Description of the invention

[0012] According to a first embodiment of the invention, a forming method for producing a desired contour with a large through-hole height is proposed, which comprises at least the following steps: A. Preforming a volume contour from a sheet metal blank, B. forming approach to the target contour with a vertical axis, wherein a vertically formed side wall of the target contour is still inclined relative to the vertical axis and a horizontal overhang of the sheet metal blank is present.

[0013] The forming process is characterized by a subsequent step C, in which the desired contour is finished by means of a plurality of forming slides performing a horizontal stroke, so that the still inclined and / or still curved side wall is aligned parallel to the vertical axis.

[0014] In steps A and B of the forming process proposed here, a volume contour is first pre-formed in two passes, i.e., using only two tools, for example a hood shape as known from DE 100 20 176 A1 (compare Fig. 1, Form 7a). In the second step, i.e., step B, the desired contour is approximated, whereby a side wall to be formed vertically, for example the cylinder wall in the case of a cylindrical shape, is left inclined. The more steeply the side wall is inclined after step B, the more material is available for the final drawing height. However, this potential cannot be exploited in conventional deep-drawing processes because the forming forces can only be applied vertically, i.e., parallel to the vertical axis.

[0015] It is proposed here to employ multiple forming slides that execute a horizontal stroke, i.e., a stroke perpendicular to the vertical axis of the final target contour. When fully compressed, the forming slides form the shape corresponding to the drawing die in conventional deep drawing. Preferably, a punch die, corresponding to the punch in conventional deep drawing, is located at the center of the target contour. However, in this case, the forming slides are moved relative to the target contour, while the preferably provided punch die remains stationary relative to the target contour. The sheet metal blank fills the gap formed between the forming slide and the die punch, resulting in a precise, wrinkle-free forming process. Due to the initially inclined side wall, more sheet metal blank is present, consequently increasing the throughput potential.This potential can be fully exploited by means of the horizontally moving forming slides due to the horizontally introduced forming forces.

[0016] According to an advantageous embodiment of the forming process, the desired contour is aligned with the vertical axis ( H ) and a maximum cylinder diameter ( D ) cylindrically shaped and it is a ratio ( H / D ) of vertical axis ( H ) to cylinder diameter ( D A value greater than 0.37 is achievable. With conventional multi-stage drawing, a maximum value of 0.32 is achievable.

[0017] For example, a desired contour is a cylindrical shape with a vertical axis ( H ) of 22 mm and a cylinder diameter ( D ) of only 56 mm is achievable. According to current findings, even a ratio ( H / D A value of 0.39 is achievable. This process therefore surpasses conventional deep-drawing processes.

[0018] According to an advantageous embodiment of the forming process, four forming slides are provided, which are guided diametrically towards each other.

[0019] In this preferred embodiment, four forming slides are pushed towards each other in the manner of a chuck jaw, so that they come into lateral contact with each other at the maximum of the horizontal stroke. It was surprisingly found that no creases or ridges form in the initial gaps between the forming slides.

[0020] According to an advantageous embodiment of the forming process, the desired contour has an open bottom surrounded by the side wall with a horizontal edge inclined and / or curved towards the center, and in step C, a bottom punch is placed on the section of the open bottom to be formed, performing a vertical stroke, forming the horizontal edge.

[0021] In this particular embodiment of the forming process, the desired contour has an open bottom, meaning it does not form a closed cup. However, it does have a horizontal bottom portion that extends radially from the side wall to the center of the desired contour. This flange, oriented radially to the center, is referred to here as the (horizontal) rim. The bottom die described here serves a function that corresponds to a hybrid of a blank holder and a stamping die. Preferably, the diameter of the bottom die is smaller than the diameter of the desired contour, and the radius between the rim and the side wall is formed by the forming slides. Preferably, the entire radius is defined by the forming slides, and the bottom die is limited to the central, for example, flat, area.

[0022] In a preferred embodiment, the bottom stamp comes into contact with the section which is still inclined to the horizontal, before the forming slide comes into contact with the side wall.

[0023] If the bottom die is brought into contact with the section to be formed at the edge before the forming slides are applied radially from the outside to the still inclined and / or curved side wall, deflection of the sheet metal blank towards the center is reduced or prevented. This makes more sheet metal available for the required forming height.

[0024] In a particularly preferred embodiment, the bottom punch only completes its vertical stroke after the horizontal stroke of the form slide has been completed.

[0025] The bottom die is only fully lowered onto the section that will form the edge after the horizontal stroke is completed by the forming slide. The edge therefore only reaches its final shape after the side wall has reached its final shape. This means that more material from this section is available for achieving the required throughput height and thus greater throughput potential.

[0026] According to an advantageous embodiment of the forming process, the forming slides rest frictionally on the horizontal overhang of the sheet metal blank during the horizontal stroke.

[0027] In this advantageous embodiment, in addition to the potential of the still inclined and / or curved side wall, further potential is added from the horizontal overhang of the sheet metal blank. While in conventional deep drawing the material of the overhang can only be supplied by tensile stresses from the area of ​​the blank holder, the forming process proposed here can be set up such that additional shear stresses or neutral stresses, or at least reduced tensile stresses, are present in the material of the overhang when, as a result of the frictional shear by means of the forming slides, a portion of the overhang is supplied to the vertical portion of the target contour. This allows the horizontal elongation potential of the sheet metal blank to be utilized to a very high degree.

[0028] According to a further aspect of the invention, a forming tool for producing a desired contour with a large through-hole height is proposed, wherein the forming tool comprises at least the following components: - a hold-down surface for placing a volume contour approximating the target contour with a horizontal overhang of sheet metal blank; - a plurality, preferably four, of form slides for performing a horizontal stroke, wherein the overhang between the hold-down surface and the form slides is held and the form slides are arranged to slide over the overhang.

[0029] Using the forming tool, step C of the forming process described above can be carried out. The volume contour obtained after step B, which approximates the target contour, is placed onto the blanking plate surface.

[0030] The blank holder surface functions like half of a conventional blank holder, which is designed to clamp the overhang. Here, however, this function is performed by the blank holder surface and the corresponding surfaces of the forming slides. The blank holder surface remains stationary relative to the overhang unless the overhang is partially stretched during the forming process or completely entrained by friction on the forming slides. Preferably, the blank holder surface is part of a rigid and stationary component of the forming tool.

[0031] In their fully retracted state, the forming slides, together with their forming surfaces oriented towards the (later) vertical portion of the sheet metal blank, form the forming half that corresponds to the drawing die in a conventional deep-drawing process. Similarly, the surfaces mentioned in the previous paragraph, corresponding to the blank holder surface, also form the corresponding counter-surface of the blank holder in a conventional deep-drawing process when fully retracted. Preferably, these surfaces are formed entirely by the forming slides without any additional surfaces. Unlike a drawing die and the counter-surface of the blank holder, the forming slides are moved horizontally and slide over the overhang of the sheet metal blank. In a preferred embodiment, three, four, or more forming slides are provided, which are moved diametrically towards each other along their respective horizontal strokes.Preferably, the forming surfaces of the forming slides correspond exactly to the desired target contour. They therefore exhibit no tendency for a negative drawing gap.

[0032] According to an advantageous embodiment of the forming tool, the forming tool further comprises a punch die, preferably as an integral part of the hold-down surface.

[0033] In this preferred embodiment, the die forms a counter surface corresponding to the forming surfaces of the forming slides. The shape corresponds to the embossing die of a conventional deep-drawing process. In contrast to an embossing die, however, the die remains stationary relative to the sheet metal blank, unless the blank is partially stretched or frictionally driven by the forming slides. Preferably, the die is part of a rigid and stationary component of the forming tool, and particularly preferably an integral part of the component that forms the blanking surface. Preferably, no negative drawing gap is provided between the die and the forming surfaces of the forming slides; that is, the counter surface of the die is formed correspondingly, for example, parallel to, the forming surface of the forming slides.

[0034] According to an advantageous embodiment of the forming tool, the forming tool further or alternatively comprises a bottom punch, wherein the bottom punch is movable vertically towards the hold-down surface.

[0035] In this preferred embodiment, the forming slides do not form the entire surface of a conventional drawing die. Rather, at least a portion of the base is formed by a base punch, which is movable along a vertical stroke on the sheet metal blank. Preferably, the base punch is configured to correspond to a die according to the preceding description.

[0036] According to a further aspect of the invention, a cylindrical target contour is produced by means of a forming process according to an embodiment as described above, wherein the cylindrical target contour has a vertical axis ( H ) and a maximum cylinder diameter ( D) exhibits and the ratio ( H / D ) of vertical axis ( H ) to cylinder diameter ( D ) greater than 0.37.

[0037] The resulting cylindrical contour is preferably a rotationally symmetric cylinder, but can also have an oval or polygonal base. Preferably, the height of the side wall, i.e., the cylinder wall in the case of a rotationally symmetric cylinder, is the same over the entire circumference, but can also vary. The cylindrical contour has a closed or open base, and the base is either flat, i.e., parallel to the horizontal, or has a freeform shape, for example, one or more bulges.

[0038] Preferably, the desired contour is produced by means of a forming tool according to an embodiment as described above. List of characters

[0039] Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. The drawing shows Fig. 1 in a schematic view the initial state of a forming tool with clamped volume contour, Fig. 2 in a schematic view an intermediate state of the forming tool, Fig. 3 in a schematic view a final state of the mold in which the target contour is present, Fig. 4 a perspective view of a schematically represented forming tool, and Fig. 5 a target contour with overhang. Best way to implement the invention

[0040] In Fig. 1 is, purely schematically, a forming tool. 100 shown, in which a volume contour 1 The volume contour is clamped and has been created by (preferably a maximum of two) preceding forming steps. 1is thereby via their sheet metal cutting 2 formed overgrowth 4 between the form slides 10 and clamped to the hold-down surface 13. Centrally within the volume contour 1 There is a stamp die inside. 12 . A floor stamp is shown in the illustration above. 11 along the vertical lifting axis ( z ) lowerable. The volume contour 1 It has a side wall that is still inclined and still curved. 3 on. This volume contour 1 has an open bottom 5 up. At the open ground 5 A further inclined and arched section 7 is provided, which later becomes a horizontal edge. 6 (compare Fig. 3) is reshaped. The form slides 10 are now along the radial or horizontal lifting axes ( r ) towards each other or towards the stamp die 12procedure. The form sliders slide during this process. 10 over the overhang 4 of the sheet metal cutting 2 .

[0041] Fig. 2 shows the forming tool 100 in an intermediate state, in which the sheet metal cutting 2 an intermediate contour 8 exhibits a shape that has already reached approximately 75% of its final contour. The bottom stamp 11 is not yet in contact with section 7 and section 7 is therefore still inclined and curved.

[0042] In Fig. 3 shows the final state, in which the volume contour 1 (compare Fig. 1 and Fig. 2) into the shape of the desired contour 200 has been moved. Both the form slides 10 as well as the floor stamp 11 are maximal, i.e., completely, along the horizontal stroke axis ( r ) or the vertical lifting axis ( z) procedure. With suitable process control, the remaining gap is completely removed from the sheet metal blank. 2 filled, which in this area defines the target contour 200 trains. Here, the use of the floor stamp is also possible. 11 the horizontal edge 6 from section 7 (compare Fig. 1 and Fig. 2) formed.

[0043] In Fig. Figure 4 is a perspective view of a schematically represented forming tool. 100 shown which four form slides 10 exhibits each of which is located along the horizontal stroke axis oriented radially to the center ( r ) are movable towards each other. A volume contour is located in the center. 1 arranged. The volume contour 1 is made from a sheet metal blank 2 pre-shaped and has an open bottom 5 and an overhang 4 up. By means of the overhang 4 is the volume contour 1between the hold-down surface 13 and the form slides 10 clamped down.

[0044] In Fig. 5 is an example of a target contour 200 shown which is cylindrical and has a vertical axis ( H ) as well as a cylinder diameter ( D ). Furthermore, the target contour exhibits 200 an open floor 5 and a horizontal border 6 up. The side wall 3 is vertical here, i.e. parallel to the vertical axis ( H ) aligned. The target contour 200 is here with an overhang 4 This is shown. For some applications, this protrusion 4 for example, it is separated by punching. In one main application, this excess material forms the basis for subsequent forming or other shaping processes. The ratio ( H / D ) between the length of the vertical axis ( H ) and the length of the diameter ( D) is approximately 0.375 in this example. Reference symbol list 100 forming tools 200 target contour 1 Volume contour 2 Sheet metal cut 3 side wall 4 overhang 5 open floor 6 Rand Section 7 8 Intermediate contour 10 form slides 11 floor stamps 12 Stamp die 13 Hold-down area r horizontal lifting axis z vertical lifting axis H vertical axis D cylinder diameter QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10020176 A1 [0005, 0014] DE 10344885 B3

[0005]

Claims

[1] Forming process for producing a target contour (200) with a large draft height, comprising at least the following steps: A. Preforming a volume contour (1) from a sheet metal blank (2), B. forming approach to the target contour (100) with a vertical axis (H), wherein a vertically formed side wall (3) of the target contour (200) is still inclined relative to the vertical axis (H) and a horizontal overhang (4) of the sheet blank (2) is present, characterized by , that in step C. the target contour (100) is formed by means of a plurality of form slides (10) performing a horizontal stroke (r), so that the still inclined and / or still curved side wall (3) is aligned parallel to the vertical axis (H). [2] Forming method according to claim 1, wherein the desired contour (200) is cylindrically shaped with the vertical axis (H) and a maximum cylinder diameter (D) and a ratio (H / D) of vertical axis (H) to cylinder diameter (D) greater than 0.37 can be achieved. [3] Forming method according to claim 1 or 2, wherein four forming slides (10) are provided which are guided diametrically towards each other. [4] Forming method according to one of the preceding claims, wherein the desired contour (200) has an open bottom (5) surrounded by the side wall (3) with a horizontal edge (6) inclined and / or curved towards the center, and in step C. a bottom punch (11) is placed on the section (7) of the open bottom (5) to be formed, performing a vertical stroke (z), wherein preferably the bottom punch (11) comes into contact with the section (7) which is still inclined to the horizontal before the forming slide (10) comes into contact with the side wall (3), and particularly preferably only after completion of the horizontal stroke (r) the forming slide (10) completes the vertical stroke (z). [5] Forming method according to one of the preceding claims, wherein the forming slides (10) rest frictionally on the horizontal projection (4) of the sheet blank during the horizontal stroke (r). [6] Forming tool (100) for producing a target contour (200) with a large through-hole height, comprising at least the following components: - a hold-down surface (13) for placing a volume contour (1) approximating the target contour (200) with a horizontal overhang (4) of a sheet metal blank (2); - a plurality, preferably four, form slides (10) for performing a horizontal stroke (r), wherein the projection (4) is held between the hold-down surface (13) and the form slides (10) and the form slides (10) are arranged to slide over the projection (4). [7] Forming tool (100) according to claim 6, wherein the forming tool (100) further comprises a punch die (12), preferably as an integral part of the hold-down surface (13). [8] Forming tool (100) according to claim 6 or 7, wherein the forming tool (100) further comprises a bottom die (11), wherein the bottom die (11) is movable vertically towards the hold-down surface (13). [9] Cylindrical target contour (100) produced by a forming process according to one of claims 1 to 5, preferably by a forming tool according to one of claims 6 to 8, wherein the cylindrical target contour (100) has a vertical axis (H) and a maximum cylinder diameter (D) and the ratio (H / D) of vertical axis (H) to cylinder diameter (D) is greater than 0.37.

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