DE102021207714A1 - Forming tool and method for forming a workpiece - Google Patents

Abstract

The invention relates to a forming tool (10) for forming a workpiece (17), comprising an upper tool (11) and a lower tool (13). In a holding area (19) for holding the workpiece (17), at least one capillary structure (30) comprising at least one capillary channel (31) is formed in at least part of a surface (18) of the upper tool (11) and/or the lower tool (13). .

Description

The invention relates to a forming tool for forming a workpiece and a method according to the independent claims.

Forming tools are basically known from the prior art, but failure in the form of cracks and lacing can occur during forming, which leads to higher costs due to the increased effort and consumption of resources. To avoid this, the additional oiling of the workpiece can be increased, for example. However, the forming tools are then very oily, which in turn leads to contamination of the workpiece with the result of additional effort due to subsequent oil removal.

The present invention is therefore based on the object of improving a forming tool in such a way that the use of lubricant is reduced, while at the same time greater manufacturing accuracy and process stability are ensured.

The aforementioned task is solved by a forming tool for forming a workpiece.

The workpiece can in particular be a metal sheet, especially a circuit board. The forming tool preferably has an upper tool and a lower tool.

According to the invention, at least one capillary structure comprising at least one capillary channel is formed in a holding area, which is designed to hold the workpiece, in at least part of a surface of the upper tool and/or on a surface of the lower tool, with the capillary structure preferably being designed to provide lubricant against a to let the drawing direction of the workpiece flow.

For example, the lower tool can include a drawing die and at least one blank holder. The holding area is in particular a sheet metal holder of the forming tool. A capillary structure is thus formed on the surface of the blank holder, at least in part. In the case of the upper tool, a sheet metal holder can be formed opposite the sheet metal holder of the lower tool, in which a capillary structure is also formed in at least part of the surface.

The capillary structure is primarily a structuring of the surface, which means that in at least the part in which the capillary structure is formed, the surface cannot be flat. In this case, however, the surface is not fundamentally roughened but is smooth, apart from the areas in which capillary channels are formed. The capillary structure is designed in such a way that it achieves a capillary effect with regard to a lubricant. A capillary effect is to be understood as meaning the property that the lubricant can spread in the at least one relatively narrow capillary channel, specifically counter to the drawing direction.

The lubricant is in particular a drawing oil, in particular a basic oiling and/or an additional oiling of the workpiece. The capillary structure is preferably designed in such a way that it stimulates the lubricant to flow in a direction opposite to a drawing direction of the workpiece and stops a flow movement in the drawing direction.

The drawing direction results in particular from the infeed of the workpiece. This avoids contamination with the lubricant, since the lubricant is not transported out of the forming tool. Overall, therefore, less lubricating oil can be used. The effect of the lubricant is also improved since an even, homogeneous distribution within the capillary channels of the capillary structure on the surface is brought about. There is therefore no risk of dry running in the holding areas that are heavily subjected to surface pressure. A hydrodynamic system is created that allows a reduction in the use of lubricant and increased manufacturing accuracy and process stability.

The at least one capillary channel tapers in its longitudinal direction from a first longitudinal end to a second longitudinal end. In other words, the capillary channel extends from a first longitudinal end to a second longitudinal end, with its diameter decreasing in the direction of the second longitudinal end.

A reservoir for collecting lubricant is preferably arranged at the first longitudinal end. The reservoir is in particular an area in which lubricant can collect. Above all, the capillary channel can open into the reservoir. In particular, the capillary channel has a preferably round recess at the first longitudinal end, which serves as a reservoir. The reservoir can also be trough-shaped.

The lubricant used, in particular the basic oiling and/or also the additional oiling, thus remains in the reservoirs of the capillary channels on the surface in the holding area chen. The reservoirs serve to store the lubricant, which contributes to the formation of the hydrodynamic system.

The at least one capillary channel has an angle to the drawing direction of between 3° and 90°. In particular, the angle is between 5° and 80°, in particular between 10° and 60°.

In a cross section, the base of the at least one capillary channel is rounded. The at least one capillary channel can have a length of 100 μm to 50,000 μm, preferably 3,000 μm to 20,000 μm. The width of the capillary channel can be between 1 µm and 150 µm, most preferably between 50 µm and 100 µm.

The at least one capillary channel can also be rounded in a cross section in a transition area to the surface of the upper tool and/or the lower tool. In other words, the channel cross-section is rounded and merges steadily into the surface.

The capillary structure can have more than one capillary channel, which can preferably be designed as described above. In particular, the capillary structure is not introduced into the surface by mechanical processing, for example milling or scratching, but by means of a laser ablation process, which can then be followed by a heat treatment.

In particular, the capillary channels can be connected to one another. The capillary channels can merge into one another and thus be fluidically connected so that lubricant can flow from one capillary channel into another capillary channel. In particular, two capillary channels can be connected to one another on at least one reservoir, which means that at least two capillary channels can open into a reservoir.

The part of the surface on which the capillary structure is formed can be a maximum of 30% of the surface, preferably a maximum of 20% of the surface. The surface is in particular the surface of a sheet metal holder that comes into contact with a workpiece during forming.

In a further aspect, the invention relates to a method for forming a tool using a forming tool which is preferably designed as described above.

The method preferably includes the forming of a workpiece, which includes the further steps of drawing the tool in a drawing direction. A capillary effect within the capillary structure prevents the lubricant from moving in the drawing direction. In particular, a surface contact is created between the holding areas of the upper tool and those of the lower tool with the workpiece, with the surface pressure being between 2 MPa and 50 MPa.

• 1: eine Schnittdarstellung eines erfindungsgemäßen Umformwerkzeuges;
• 2: einen Querschnitt zweier Kapillarkanäle einer Kapillarstruktur der 1;
• 3: eine Draufsicht auf einen Kapillarkanal; und
• 4: eine Draufsicht auf eine Oberfläche mit einer Kapillarstruktur umfassend mehrere Kapillarkanäle.

It show in a purely schematic representation

• 1 : a sectional view of a forming tool according to the invention;
• 2 : a cross section of two capillary channels of a capillary structure 1 ;
• 3 : a plan view of a capillary channel; and
• 4 : a plan view of a surface with a capillary structure comprising a plurality of capillary channels.

1 shows a sectional view of a forming tool 10 according to the invention. The forming tool 10 includes an upper tool 11 and a lower tool 13. The upper tool 11 includes a blank holder 12 with in 1 shown two projections. The lower tool 13 comprises a drawing punch 15 and a sheet metal holder 14 comprising the two 1 arms shown, the sheet metal holder 14 of the lower tool 13 of the sheet metal holder 12 of the upper tool 11 are arranged opposite one another. A workpiece 17, in particular a circuit board, is drawn in the drawing direction 16. There are two holding areas 19, specifically formed between the sheet metal holders.

The sheet metal holder 12 of the upper tool and the sheet metal holder 14 of the lower tool 13 each have a surface 18 in which a capillary structure 30 is formed at least in part.

2 shows a cross section of two capillary channels 31 of a capillary structure 30 in a surface 18 on a holding area 19 after 1 are introduced. In the cross section it can be seen that the capillary channels 31 are each rounded at their base 21 and in a transition area 20 to the surface.

3 Figure 12 shows a plan view of a capillary channel 31 in a surface 18 extending from a first longitudinal end 31a to a second longitudinal end 31b. It tapers from the first longitudinal constriction 31a to the second longitudinal end 31b. A reservoir 32 for collecting the lubricant is formed at the first longitudinal end 31a, into which the capillary channel 31 opens. The capillary channel 31 may have an angle 33 with the pulling direction 16 .

In 4 A top view of a surface 18 with a capillary structure 30 comprising a plurality of capillary channels 31 with reservoirs 32 can be seen. The capillary channels 31 are connected to one another, in particular at reservoirs 32. In other words, they open into a common reservoir 32.

Reference List

10

forming tool

11

upper tool

12

sheet metal holder

13

lower tool

14

sheet metal holder

15

drawing stamp

16

drag direction

17

workpiece

18

surface

19

holding area

20

transition area

21

reason

30

capillary structure

31

capillary channel

31a

first longitudinal end

31b

second longitudinal end

32

reservoir

33

angle

Claims (10)

Forming tool (10) for forming a workpiece (17), comprising an upper tool (11) and a lower tool (13), characterized in that in a holding area (19) for holding the workpiece (17) in at least part of a surface (18 ) of the upper tool (11) and/or the lower tool (13) at least one capillary structure (30) comprising at least one capillary channel (31) is formed. Forming tool (10) after claim 1 , characterized in that the capillary structure (31) is designed to allow lubricant to flow counter to a drawing direction of the workpiece (17). Forming tool (10) after claim 1 or 2 , characterized in that the at least one capillary channel (30) tapers from a first longitudinal end (31a) to a second longitudinal end (32b) in its longitudinal direction or has a constant width from the first longitudinal end (31a) to the second longitudinal end (32b). . Forming tool (10) after claim 3 , characterized in that a reservoir (32) for collecting lubricant is arranged at the first longitudinal end (31a). Forming tool (10) according to one of the preceding claims, characterized in that the at least one capillary channel (31) encloses an angle (33) to the drawing direction (16) of between 3° and 90°. Forming tool (10) according to one of the preceding claims, characterized in that the at least one capillary channel (31) is rounded in a cross-section at its base (21). Forming tool (10) according to one of the preceding claims, characterized in that the at least one capillary channel (31) is rounded in a transition region (20) to the surface (18) of the upper tool (11) and/or lower tool (13). Forming tool (10) according to one of the preceding claims, characterized in that the capillary structure (30) comprises more than one capillary channel (31), the capillary channels (31) being connected to one another. Forming tool (10) according to one of the preceding claims, characterized in that the capillary structure (30) is formed on a maximum of 30 percent of the surface (18). Method for forming a workpiece using a forming tool according to one of Claims 1 until 9 .

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