DE102012217887A1 - Method for reshaping and punching metal sheet material i.e. workpiece, involves marking sheet material in hole region during punching process, and forming local recess relative to sheet region, where punch is penetrated into hole - Google Patents

Abstract

The method involves carrying out a punching process with a lengthwise-movable punch (130) that is moved for punching a metal sheet material (200) in a pointed gumption angle. The metal sheet material is marked in a hole region during punching process. A ball-cap shaped stamped recess (210) is formed relative to an adjacent metal sheet region, where the punch is penetrated into the hole during the punching process. The stamped recess is provided with a concave contour. The stamped recess is generated by a spherical or hemispherical shape stamp. An independent claim is also included for a device for reshaping and punching a metal sheet material.

Description

The invention relates to a method for forming and punching a sheet material, wherein the punching is carried out with a longitudinally movable punch, which is moved for punching or hole cutting at an acute cutting angle to the sheet material.

The invention also relates to two devices for carrying out the method in question.

Due to a limited number of work sequences in the press shop and / or for design reasons, it is sometimes necessary that a punch for inserting a hole at an acute cutting angle to the sheet material must be moved (i.e., not perpendicular to the sheet material or sheet surface). In an oblique placement of the punch on the sheet material of the punch is pushed due to the transverse forces occurring in a lateral direction, which unclean hole cuts or poor cutting edges, increased wear and especially an increased risk of damage to the punch (up to the breakage of the punch) or the corresponding cutting die has resulted. Depending on the cutting angle applies: the smaller the hole geometries and the thinner the punches, the higher the Abdrängneigung.

From the DE 10 2008 004 901 A1 a punch with a longitudinally movable punch is known, wherein the punch for punching or hole cutting at an acute cutting angle (ie not perpendicular) is moved to the sheet material or the sheet surface. The punch is longitudinally movably guided in a tool bridge and a scraper, whereby a pressing off can be prevented conditionally. For reasons of space such stamp guides are not everywhere possible.

The object of the invention is to provide a method and devices of the type mentioned, which do not have the disadvantages associated with the prior art, or at least only to a reduced extent.

This object is achieved by an inventive method with the features of claim 1. This object is further achieved by two devices according to the invention with the features of the independent claims. Advantageous and preferred developments and refinements emerge analogously for all subjects according to the invention both from the dependent claims and the following explanations.

The inventive method for forming and punching a sheet material is characterized in that the sheet material is embossed or pre-punched before punching or hole cutting in the region of the hole to be introduced or at the cutting location and hereafter a local depression (or impression, bead or dent ) against the adjacent sheet metal area, in the following, the punch penetrates or penetrate (or engage or retract) for the purpose of punching or hole cutting.

Under a depression (or an embossed or embossed depression) is understood only at the cutting location locally introduced plastic deformation of the sheet material, which stands out clearly due to their shape to the adjacent sheet metal area and makes a difference. By local we understood that the depression is confined spatially around the cutting location. The introduced at the cutting location before punching local depression prevents the punch during hole cutting due to occurring lateral forces can be pushed in a lateral direction or at least can only be pushed by a relatively small distance, eg. By mechanical locking or blocking. In particular, it is provided that the depression is adapted to the punch such that the occurrence of a resulting transverse force is prevented at all.

The forming process for forming a local pit is also referred to herein as embossing. The embossing for producing a depression takes place in particular with a forming punch designated as such, wherein such a forming punch may be formed as a separate longitudinally movable tool part or as part of a shaping tool geometry (a forming and / or cutting tool or pressing tool).

An acute cutting angle is understood to mean a cutting angle which is less than 90 ° and preferably greater than 70 °, particularly preferably greater than 75 °, in particular greater than 80 ° and particularly preferably greater than 84 °. The cutting angle is the included angle between the axis of movement of the punch and the sheet plane at the cutting location.

A sheet material is understood to mean a flat semi-finished product made of a metal material, which in particular has a substantially flat starting state. A pipe is not a sheet material according to the invention. The sheet metal material is in particular a steel sheet or an aluminum sheet. The sheet thickness is preferably in a range of 0.7 mm to 3.0 mm (thin sheet).

It is particularly preferred that the sheet metal material is first formed from its initial state and then punched, at least one hole or through hole is cut or punched into the sheet material by means of at least one translational or longitudinally movable punch, including the punch at the cutting site in a acute cutting angle to the sheet material or the sheet surface is moved. The punching or hole cutting takes place in particular with a closed cutting line. The forming and punching can take place in one or more press-bound and correspondingly formed forming and / or cutting tools (or pressing tools). Several forming and / or cutting tools may be connected to a transfer device or the like for transferring the sheet material or workpiece.

The invention enables the production of clean hole cuts with high quality cut edges. In particular, ideally round or symmetrical or ideally parallel cutting edges are made possible. Due to the resulting reduction or avoidance of resulting shear forces, friction and wear and possible damage to the punch and / or a corresponding cutting die are minimized. The noise development is reduced. Furthermore, relatively large cutting angles and thus hole directions are made possible, which have not been feasible so far, whereby fewer work sequences in the press shop and thus less forming and / or cutting tools are required. By the punching or hole cutting preceding local embossing or pre-embossing of the sheet material, the sheet material at the cutting location may also have a higher strength, which may have an advantageous effect on the hole or hole cutting process.

The shape or geometry of the depression to be impressed is adapted in particular to the hole geometry of the hole to be subsequently introduced, preferably in such a way that as little stamping as possible of the sheet material takes place outside the especially closed cut edge. For example. In the case of an elliptical hole geometry, the geometry of the depression would also be elliptical (with respect to a plan view of the cutting location). Ie. the forming punch is formed equivalent to the hole geometry.

It is preferably provided that the indentation embossed on the cutting location during embossing has an edge-free and, in particular, concave contour in cross-section (that is to say lying in the plane of the sheet). Particularly preferably, an arcuate or circular segment-shaped contour is provided.

In particular, it is provided that the impressed embossing at the cutting location recess is spherical cap or spherical segment. A spherical cap or a spherical segment is a dome-like spherical segment. A spherical cap-shaped recess or imprint has an optimal area-space ratio. Minimal embossing thus achieves an optimum effect in the sense of the invention. A spherical cap-shaped depression is also advantageous in particular with regard to the perforation of circular cross sections. Preferably, the spherical cap-shaped depression (with respect to the plan view) should be just so large and deep that the punch or its cutting end side finds room in it. Ie. A minimal embossing is usually sufficient.

Furthermore, it is preferably provided that the spherical cap-shaped recess is produced by a spherical or spherical cap-shaped forming punch (or the like), wherein the center of the ball or spherical cap of the punch is moved during embossing along the later axis of movement of the punch. This will be explained in more detail below with reference to FIGS.

In general, a minimal embossing of the sheet material at the cutting location is sufficient. Therefore, the punching or hole cutting preliminary local embossing of the sheet material for introducing the recess can be carried out substantially without sheet thinning, which is advantageous in several respects.

The punch can be designed to produce a wide variety of hole geometries (such as, for example, polygonal holes, oblong holes, elliptical or oval holes and the like). It is preferably provided that the punch is a circular punch for generating (or punching or cutting) of circular holes. It is particularly preferred that the circular holes producible with the circular punch in the sheet material have a diameter of 3 mm to 20 mm, preferably of 4 mm to 14 mm and in particular of 5 mm to 10 mm. The stamp surfaces or hole surfaces resulting therefrom preferably apply equally to other stamp cross-sections or hole geometries. The cutting punches provided for producing such relatively small holes would be particularly susceptible to squeezing when placed on the sheet material due to their relatively small diameter without the inventive local deepening or pre-embossing of the sheet material at the cutting location.

The claimed with the first independent claim apparatus for performing the method according to the invention comprises at least one press-bound forming and / or cutting tool, in which both the embossing of the sheet material and the subsequent punching of the sheet material.

It is preferably provided that this forming and / or cutting tool has a first tool part and a second tool part (eg upper and lower tool) that are relatively movable relative to one another, and that this forming and / or cutting tool also has at least one cutting device which at least one in particular longitudinally movable punch, which can produce or cut a hole at an acute cutting angle to the sheet material comprises. It is further provided that this forming and / or cutting tool has a molding device with which the sheet material is embossed before punching such that this (in the cutting area or at the cutting location) has a local depression relative to the adjacent sheet metal area, in the following Punch can penetrate. The molding device in particular comprises at least one molding die.

The device claimed in the second independent claim comprises a first press-bonded forming and / or cutting tool for (previously) local embossing of the sheet material (at the cutting location) and at least one second press-bound forming and / or cutting tool for subsequent punching of the sheet material (in the above deepening produced). The forming and / or cutting tools are connected to each other in particular by a workpiece transfer device.

The invention will be explained in more detail below with reference to the schematic and not to scale figures in principle. The features shown in the figures and / or explained below may, regardless of specific feature combinations, be general features of the invention.

1 FIG. 16 illustrates in a side view the punching of a sheet material at an acute cutting angle according to the prior art. FIG.

2 Figure 2 illustrates in two side views the invention with a pre-punching local stamping of the sheet material.

3 illustrates in an enlarged plan view of the cutting location according to the punch on punching according to 2 acting shear forces.

1 shows a punch 130 and a corresponding punching or cutting die 140 , At the punch 130 For example, it is a circular hole punch for generating or introducing small circular holes in a between the punch 130 and the cutting die 140 arranged sheet metal or workpiece 200 , The punch 130 and the corresponding cutting die 140 form a cutting device, which can be arranged, for example. In a forming tool and / or cutting tool, not shown, wherein the cutting punch 130 eg in the upper part of the tool and the cutting die 140 can be arranged in the tool base. In such a forming and / or cutting tool more cutting devices can be arranged.

For punching or hole cutting is the punch 130 along the straight movement axis L in the direction of the cutting die 140 moved and applied with force, which is illustrated by the arrow B. This is the punch 130 in an acute cutting angle W to the sheet material 200 emotional. The cutting angle W is the angle between the axis of movement L of the punch 130 and the sheet plane E at the cutting location, as in 1 illustrated. When obliquely placing the punch 130 on the sheet metal material 200 this is forced in a lateral direction due to a resulting transverse force F and, for example, elastically bent, which is illustrated by the arrow F. To push this off the punch 130 To avoid is inventively proposed in the sheet material 200 before punching or hole cutting at the cutting place to introduce a depression, as described below with reference to 2 explained in more detail.

According to the invention it is provided that the sheet material 200 before punching by means of the punch 130 is stamped on the cutting location and hereafter has a local depression opposite the adjacent sheet metal area. This is in 2a illustrated. The embossing of the sheet metal material 200 done with a spherical shape stamp 110 (Ball stamp) and a corresponding molding die 120 , The shape stamp 110 and the molding die 120 form a shaping device, which can also be arranged in a forming tool and / or cutting tool analogous to the above explanations regarding the cutting device. The shape stamp 110 can also be designed differently and, for example, have a spherical cap-shaped mold section. Furthermore, the forming punch 110 Be part of a forming tool geometry of a forming and / or cutting tool.

For embossing the sheet metal material 200 at the cutting location, the center M of the spherical forming punch 110 along the movement axis L of the punch 130 (please refer 2 B ) and applied with force, which is illustrated by the arrow A. Ie. the axes of movement L of the punch 110 and the punch 130 are essentially and in particular exactly identical. This is in the sheet material 200 at the cutting a kugelkalottenförmige recess 210 imprinted or molded, such that the buckling direction in the cutting direction or in the direction of movement of the punch 130 when punching points (ie, as shown below).

The subsequent punching by means of the punch 130 takes place in the kugelkalottenförmignign recess 210 , where the punch 130 along the same axis of motion L as previously the spherical forming punch 110 is moved. The depression previously created at the cutting location 210 is just so big and deep that the punch 130 or whose front side has room for punching, as in 2 B illustrated. The cutting die 140 is trained accordingly.

When punching in the spherical cap depression 210 passes the entire cutting edge, the punch 130 edged on the front side (wherein other cutting edge formations are possible), substantially at one time or simultaneously in contact with the sheet material 200 , The here on the punch 130 acting transverse forces f are due to the spherical cap-shaped depression 210 directed toward each other and cancel each other (due to the symmetrical force) substantially mutually, as in 3 illustrated. As a result, the occurrence of a resulting transverse force is prevented and a displacement or deflection of the punch 130 prevented. Even with smaller cutting angles W is an ideal round hole in the sheet material 200 generated.

Embossing or pre-embossing of the sheet material 200 at the cutting site for generating or molding a recess 210 and the punching of the sheet material 200 in the previously produced embossment or depression 210 can be done in one and the same forming and / or cutting tool or in different forming and / or cutting tools. The related design and construction of the tools and tooling facilities is within the skill and knowledge of the art.

LIST OF REFERENCE NUMBERS

110

forming punch

120

forming die

130

punch

140

cutting die

200

Sheet material (workpiece)

210

Deepening, imprint

A

movement direction

B

movement direction

e

Sheet plane (at the cutting site)

f

transverse forces

F

resulting lateral force

L

motion axis

M

Dome or ball center

W

cutting angle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008004901 A1 [0004]

Claims (10)

Method for forming and punching a sheet metal material ( 200 ), wherein the punching with a longitudinally movable punch ( 130 ), which is for punching at an acute cutting angle (W) to the sheet material ( 200 ), characterized in that the sheet material ( 200 ) before punching in the area of the hole to be introduced and thereafter a local depression ( 210 ) relative to the adjacent sheet metal area, in the following the punch ( 130 ) can penetrate to punching. A method according to claim 1, characterized in that the embossed depression ( 210 ) has a concave contour in cross-section. A method according to claim 1 or 2, characterized in that the embossed depression ( 210 ) is spherical cap-shaped. A method according to claim 3, characterized in that the spherical cap-shaped recess ( 210 ) by a spherical or spherical cap shaped punch ( 110 ), wherein the center of the ball or spherical cap of the punch ( 110 ) when embossing along the later axis of motion ( 1 ) of the punch ( 130 ) is moved. Method according to one of the preceding claims, characterized in that the embossing of the sheet metal material preceding the punching ( 200 ) takes place substantially without sheet thinning. Method according to one of the preceding claims, characterized in that the punch ( 130 ) is a circular hole stamp. A method according to claim 6, characterized in that the with the circular punch ( 210 ) can have a diameter of 3 mm to 20 mm, preferably from 4 mm to 14 mm and in particular from 5 mm to 10 mm. Method according to one of the preceding claims, characterized in that sheet material ( 200 ) is a steel sheet or an aluminum sheet. Apparatus for carrying out a method according to one of the preceding claims 1 to 8, comprising at least one press-bonded forming and / or cutting tool, in which both the embossing of the sheet material ( 200 ) as well as the subsequent punching of the sheet material ( 200 ) he follows. Apparatus for carrying out a method according to one of the preceding claims 1 to 8, comprising at least one first press-bonded forming and / or cutting tool for embossing the sheet metal material ( 200 ) and at least one second press-bound forming and / or cutting tool for subsequent punching of the sheet material ( 200 ).

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