WO2017144407A1

WO2017144407A1 - Roller, in particular skin pass roller, and skin passed flat product

Info

Publication number: WO2017144407A1
Application number: PCT/EP2017/053779
Authority: WO
Inventors: Martin Bretschneider; Frank Klose; Tobias KLINKBERG; Thomas Routschek; Moritz Radszat; Björn HILDEBRANDT
Original assignee: Salzgitter Flachstahl Gmbh
Priority date: 2016-02-23
Filing date: 2017-02-20
Publication date: 2017-08-31

Abstract

The invention relates to a roller, in particular a skin pass roller, with a surface structure with stochastically distributed structure elements (3) of stochastic size, in particular for producing flat products from a metal material, in particular from a steel material, by way of which flat products with an improved oil retention capability and oil distribution can be skin passed, since the structure elements (3) have a height in the range from 20 to 300 µm, the structure elements (3) have a width in the range from 60 to 600 µm, and the structure elements (3) have a number of from 5 to 60 per mm². The invention also relates to a flat product made from a metal material, in particular skin passed by way of an above-mentioned roller (1), with a surface structure with stochastically distributed depressions (4) of stochastic size, in which method an improved oil retention capability and oil distribution are achieved by virtue of the fact that the depressions (4) have a depth in the range from 15 to 90 µm, the depressions (4) have a width in the range from 50 to 400 µm, the depressions (4) have a number of from 4 to 60 per mm², and the sum of the area of the depressions projected onto the flat product has an area proportion of 0.41 or greater.

Description

Roller, in particular tempering roller, and trained flat product

The invention relates to a roller, in particular temper rolling roller, with a stochastic surface structure with structural elements, in particular for

Production of flat products from a metal material, in particular from a steel material. Also, the invention relates to a flat product of a metal material, in particular trained with an aforementioned roller, with a stochastic surface structure with recesses. It is well known that sheet metal processors such as

Automotive manufacturers place high demands on steel sheets, which should be both good on the one hand and on the other hand to show a good Lackanmutung. Good formability is accompanied by avoidance of problems in deep drawing, such as tearing, which lead to rejects. Also, good formability allows even more complex components to be produced without changing the quality of the steel sheet. A further increase in complexity can also be achieved by improving the quality. The requirements for good

Formability and good appearance of lacquer can be contrary. Important for a good forming is a uniform and sufficient oiling of the steel sheet to be formed. Also, the oil is protected by the oiling during transport and storage from corrosion. This lubrication is often done by the sheet metal supplier, which must be sufficient as well as homogeneous over sheet width and sheet length. Also, it must be sufficient even after prolonged service life of a wound into a coil steel sheet. During service life, oil displacement effects may occur due to the mutual surface pressures of the coil turns, i. There is an oil redistribution in the direction of the sheet edge. Therefore, the steel sheet has to be produced with a surface fine structure, which on the one hand sufficiently satisfies a good appearance of lacquer and on the other hand holds the lubricant sufficiently locally.

To meet these requirements, are steel sheets

kaltnachgewalzt. This cold rolling is also referred to as skin-pass. By cold rolling, both the mechanical characteristics such as yield strength and the surface topography, for example, characterized by roughness, peak number and waviness of the steel sheet on a desired state set. For the Kaltnachwalzvorgang be

Tempering rollers used, which have a textured surface. The texturing of the surface - starting from a roll with a smooth

Ground surface - made by different texturing. By Kaltnachwalzvorgang with appropriate skin pass rollers then the surface of the steel sheet is textured. The same applies generally to steel sheets outside the area of the body panels.

In general, as ablative texturing processes for temper rolling rollers are known: SBT (Shot Blast) - spinning of angular blasting material on the surface of the temper rolling, EDT (Electro Discharge Texturing) - EDM, EBT (Electro Beam Texturing) - electron beam in vacuum shoots defined craters into the surface of the temper rolling rolls, Lasertex laser beam shoots defined craters into the surface of the temper rolling rolls.

Furthermore, from the company publication of Salzgitter AG entitled "PRETEX ^® " - as of September 2002 - a textured thin sheet for highest

Requirements in coachbuilding known. This sheet can be uncoated or surface-finished and is used by the automotive industry in body construction for interior and exterior skin parts with the highest demands on the forming behavior and paintability. The surface topography of the sheet metal significantly influences the forming behavior as well as the adhesive adhesion and the optical properties of the automotive coating. A defined, the customer requirements corresponding surface topography of the fine sheet is produced during cold rolling. The temper rolling rollers used for this purpose are produced in a positive process by applying a texture to a smooth roller, in contrast to the above-described erosive texturing. In particular, for this purpose a so-called single stage TOPOCROM ^® process with which the surface of a smooth roll is electrolytically structural and hard chrome plated suitable. For this purpose, the skin pass mill is coated in a reactor equipped with an anode cage and filled with a chromium electrolyte. The chromium ions of the electrolyte are reduced during the coating and on the surface of the

Tempering roll metal deposited. This coating process provides an absolutely uniform stochastic distribution of the differently sized hard chromium hemispheres deposited on the roll surface, which are in size and Number per unit area targeted and reproducible by the

process computer controlled coating parameters can be adjusted according to customer requirements. The hard chromium hemispheres of

Tailoring rolls are transferred to the thin sheet during the casting in the form of appropriate dome. The surface topography of the thin sheet also has the task to absorb the lubricant and a hydrostatic or

hydrodynamic lubrication to help reduce friction. A higher average roughness and isolated lubrication pockets, which as

Lubricant reservoir serve, improve the friction and lubrication conditions significantly.

From the German patent DE 195 29 429 C2, a method for surface structuring of a rolling mill roll is already known. With this rolling mill roller are thin sheets of steel or aluminum with stochastically deterministic

Roughness structure produced. The surface structuring of the rolling mill roll is carried out by a superposition of two methods. In a first method, a finely divided stochastic basic structure by vortex beam or

Spark erosion is generated on the surface of the rolling mill roll. This stochastic basic structure is intended to ensure a minimum wetting of the surface with lubricant via a fine-meshed network of microchannels. Also, this is supposed to be stochastic

Basic structure improve the aesthetic appearance of the sheet surface against a deterministic structure. Subsequently, in a second method, a deterministic cover structure with crater-like depressions is produced by laser or electron beam treatment. These depressions should ensure lubrication in the sense of closed hydrostatic lubrication pockets under deformation stresses. This stochastically deterministic roughness structure of the rolling mill roll is transferred to the thin sheet by rolling. Accordingly, in the surface of the thin sheet, the deterministic structures are interconnected via the stochastic structures. Thus, the stored lubricant in the lubrication pockets can be distributed through the microchannels and also drain.

Also, international patent application WO 01/71048 A1 discloses a method for the production of embossing rolls for fine rolling and texturing of sheet metal. For this purpose, the rollers are on their surface with carbide powder coated, the surface melted with a pulsed laser and then eroded the resulting areas of different hardness in a further process step by means of a beam processing. This results in deterministic microstructures on the surface of the embossing rollers, which lead to a surface structure of a stamped sheet with lubricating pockets in a defined geometrical grid. Each lubrication pocket consists of a crater-shaped recess and an arc-shaped peripheral edge protruding from the surface of the sheet. This edge seal should prevent lubricant from being pulled or pressed out of the lubrication pocket.

Likewise, European Patent Application EP 0 606 743 also discloses a roller for tempering steel sheets. The surface structuring of the roll is carried out by first applying a thin chromium layer on the roll surface, then a thicker insulating resin layer is applied and this is removed locally by means of high-energy laser radiation and evenly distributed. Then, the processed roll is immersed in a chromic acid bath and subjected to another chromium treatment. This results in supernatants of chromium, which remain after removal of the resin layer on the chromium-coated surface of the roller and leave by means of rolling on the steel belt depressions. These recesses have a diameter d of 50 to 500 μηη, a depth H of 2 to 40 μηη and an average distance from each other from 1 d to 4d.

The patent US 5,532,051 describes a steel sheet with improved oil storage properties for press forming. This is the steel sheet with a

Tempering roller processed, which is surface-structured by means of microlithography. The uniformly distributed depressions introduced into the steel sheet are round, have a diameter of 20 to 600 μm, a depth of 1 to 20 μm and a distance from one another of 10 to 1000 μm. Characteristic of these wells is their flat bottom, through which forms a lubricant reservoir. The depressions are evenly distributed over the steel sheet surface and extend to at least 30% of the steel sheet surface.

The invention is based on the object, a roller, in particular

Tempering roller, with a stochastic surface structure with

Structural elements and a product produced in particular with this roller flat product from a metal material, in particular from a steel material to create, which improve the oil retention and the distribution of oil on the trained flat product. The object is achieved by a roller, in particular temper rolling, with the features of claim 1 and a flat product made of a metal material having the features of claim 9. Advantageous embodiments of the invention are specified in the subclaims 2 to 8 and 10 to 18. According to the invention, a roller, in particular a skin pass mill, with a surface structure with stochastic distributed and stochastically large structural elements, in particular for the production of flat products of a metal material, in particular of a steel material, an improved

Troughing the flat products achieved in that the structural elements have a height in the range of 20 to 300 μηη, the structural elements have a width in the range of 60 to 600 μηη and the structural elements have a number of 5 to 60 per mm ² . The distribution of the structural elements and the size of the structural elements are each stochastic, but with a defined range in terms of number and dimensions. Only this makes it possible to produce a flat product with improved oil retention capacity and oil distribution capacity with such a temper rolling mill. This targeted with the surface structure targeted better

Oil retention and the more uniform distribution of oil remain even after prolonged storage of a coil of the flat product according to the invention. A subsequent forming at the customer is facilitated because no re-oiling is required. Overall, this leads to less rejects during forming and more complex forming operations are possible. Advantageously, it is achieved with the surface structure according to the invention that, even after several months of storage, a homogeneous, sufficiently thick oil film (viewed macroscopically) is retained on the belt windings of the flat product stored as a coil, ie no oil runs out of the coil. Thus, the corrosion of the sheet is avoided. As a result, after prolonged storage of several months, the processor has a homogeneous, sufficiently thick oil film on the sheet (viewed macroscopically) and thus constant good tribological conditions during the forming process. Even with an optimum band profile and / or optimum crowning of the flat product, the invention improves oil retention and optionally compensates Insufficiencies with worse band profile or worse crowning.

In a particular embodiment, it is provided that the structural elements on the roller have a height in the range of 25 to 100 μm. It is particularly preferred that the structural elements have a width in the range from 90 to 170 μm, that the structural elements have a number from 20 to 40 per mm ² , and / or whose surface structure has a roughness Ra from 4 to 14 μm, preferably from 6 to 8 μηη, has. It is advantageously provided that the surface structure of the roller has a peak number RPc of 5 to 50 l / cm, preferably 20 to 30 l / cm.

The surface structure of the roller according to the invention is preferably achieved by an electrolytic structure and hard chrome plating. Here, the desired surface structure is applied to a roller in the sense of a positive process, so that after reaching the period of use of the surface structure of the roller only by grinding the surface structure is removed and thus the

Jacket surface of the roller is largely retained, then on the electrolytic structure and hard chrome plating the surface structure new

is applied. In the case of abrasive surface structuring processes, the rolls lose their surface area and their useful life is thus limited. The surface structures applied to the lateral surface of the roller enable a good roughness transfer to the flat product compared with the inward surface structures resulting from the removal of surface structuring methods.

Preferably, the structural elements are dome-shaped.

According to the invention, for a flat product made of a metal material, which was dressed in particular with a roller according to the invention described above, having a surface structure with stochastically distributed and stochastically large

Wells an improvement in the oil holding capacity and the distribution of oil on the trained flat product achieved in that the wells have a depth in the range of 15 to 90 μηη, the wells have a width in the range of 50 to 400 μηη, the wells a number from 4 to 60 per mm ² and the sum of the area of the recesses (4) projects onto the flat product Surface area of 0.41 or greater. Such a surface structure, which is distinguished qualitatively by many large and mutually isolated depressions, significantly influences the oil retention capacity of the flat product. A production of forming critical parts is thus facilitated, since there a uniform presence of the applied lubricant is important.

The flat products produced in connection with the invention, in particular steel sheets, are preferably used in motor vehicles, domestic appliances - so-called white goods - and sheet steel furniture. Here, the flat products may be electrolytically coated or hot-dip coated. Also, the flat products can be formed into components by, for example, deep drawing and stretch drawing. Preferably, the flat products are intended for later painting and are used as painted visible parts. The flat products are particularly suitable for forming processes, in particular deep drawing.

The fact that both the distribution and the size of the structural elements is stochastic is advantageous, although the dimensional intervals restrict the geometry of the structural elements. With other procedures will be

Creating structuring elements that are deterministic in distribution and size. These uniform structures in the flat product can also cause an undesirable, quality-reducing paint appearance due to optical effects such as the moiré effect after painting.

The small structural elements have a significant positive influence on peak numbers, waviness, glossiness and general

Surface appearance of both unpainted and painted

Flat product.

In a particular embodiment it is provided that the depressions have a height in the range of 20 to 30 μηη. It is particularly preferred that the depressions have a width in the range of 60 to 120 μm and / or that the depressions have a number of 20 to 30 per mm ² .

Advantageously, it is provided that the surface structure of the flat product has a roughness Ra of 0.8 to 4 μm, preferably of 1 to 3 μm, and / or has one Peak number RPc of 5 to 50 l / cm, preferably 20 to 30 l / cm.

Preferably, the depressions are dome-shaped. In preferred use, the flat product has a thickness in the range of 0.35-6.0 mm. Preferably, the flat product is a steel sheet. Also, the flat product may be provided with coatings of zinc or tin or a zinc-aluminum alloy or a zinc-iron alloy or a zinc-aluminum-silicon alloy or an aluminum-silicon alloy or zinc-aluminum-magnesium alloy , The coatings can also be organic. The coating may also consist of a combination of the above-mentioned coatings. In the context of the present invention are flat products as sheets or

Sandwich panels, in particular thin sheets, of metal,

Metal alloys, especially steel, aluminum, magnesium, copper, zinc or tinplate can be produced.

The invention will be explained in more detail with reference to an embodiment and accompanying drawings. FIG. 1 shows a schematic plan view of a surface structure of a

roll according to the invention or an inventive

Flat product and

FIG. 2 shows two schematic lateral sectional views of FIG. 1.

In the figure 1 is a schematic plan view of a section of a

Surface structure of a roll 1 according to the invention, in particular one

Dressierarbeitswalze, or a flat product according to the invention 2, in particular a thin sheet, shown. It can be seen that, based at most on the entire surface of the roller 1 and a maximum of one

Surface of a flat product 2, which is characterized by a revolution of a roller 1, the arrangement of structural elements 3 on the roller 1 and

Recesses 4 in the flat product 2 is stochastic. The structural elements 3 or depressions 4 are predominantly separated from one another, may have smaller or larger dimensions or may become groups of a few Structure elements 3 and depressions 4 overlap. Overall, it can be seen that the structural elements 3 or depressions 4 and also their small groups are separated from each other and offer a closed and compared to the prior art larger Olspeichervolumen. Preferably, the structural elements 3 or depressions 4 are distributed in such a way that the edges of the structural elements do not intersect for the most part in order to obtain separate oil reservoirs.

FIG. 2 shows two schematic lateral sectional views of FIG. 1. The upper part of FIG. 2 relates to a near-surface section of a roller 1 and the lower part to a near-surface section of a flat product 2. It can be seen that the surface structure of the roller 1 has a multiplicity of

Having structural elements 3, which rise on the one hand from the remaining surface of the roller 1 and on the other hand have the shape of calotte. The

Structural elements 3 are applied to the surface of a flat, cylindrical roller with a hard chromium plating and are then referred to as

Hard chromium hemispheres formed with steep flanks. In particular, this is the TOPOCROM ^® method described above, which is one-stage and applies the structural elements on a roller and not achieved by removal. In connection with the present invention are under domes

Hemisphere segments understood in which preferably the height is less than the width. The height is measured starting from the surface of the roller 1 radially in the direction of a rotation axis of the roller 1 and the width at a right angle to the direction of the height. Overall, the calottes are thus rather flat. Also, the domes on the surface of the roll 1 have an ideal shape because the dome merges directly with the remainder of the surface of the roll 1, which extends substantially parallel to the axis of rotation of the roll 1. At the edge of the dome thus no annular depressions are present, which would then lead during rolling or conditioning of the flat product to an annular bead or throw. Such a bead can hinder penetration of the oil drop into the recesses 4.

The raised structural elements 3 on the roll 1 are introduced in the course of the temper rolling in the surface of the flat product 2 in the form of recesses 4. The wells 4 are therefore formed negative-calotte-shaped, so that the above explanations to the dome also apply to the wells 4.

In order to improve the oil retention capacity and the oil distribution on a dressed flat product 2, tests have shown that surface structures of the roll 1 and of the flat product 2 are described by means of the following parameters:

Structure element height in μηη, structure element width in μηη, number of

Structural elements per mm ² , depth of the recesses in μηη, width of the recesses in μηη, number of recesses per mm ² , roughness Ra in μηη and peak number RPc in cm-1 and in the value ranges given in Tables 1 and 2 give good results.

The dome width is measured at the base of the dome and thus at its widest point.

Table 2 - Properties of the wells on the surface of the flat product

Here, the width is a lateral extension from edge to edge of

Structural elements 3 and wells 4 viewed. In qualitative terms, this results in large depressions 4 in the flat product being more oil, especially corrosion protection oil or lubricating oil, record and hold. However, the volume and the depth of the recesses 4 must not be too large, since it can then happen that this oil is not available for the forming process.

It has been shown that not only these individual geometrical properties such as width and depth of the depressions and the number of depressions in the flat product 2, but also the combination of these properties has a significant influence on the useful properties. Only when the depressions in the flat product 2 in the plan view as shown in Figure 1 have a surface area greater than 0.41, the useful properties are sufficiently given and it is stored in the wells of the flat product 2 sufficient oil for the application. This can be achieved by different combinations of width and number of wells, some of which are exemplified in Table 3. The ">" sign in Table 3 states that even larger values for width and / or number make sense in the

Combinations is, so to speak, the lower limit of the combinations.

Table 3 - Exemplary combinations of geometric minimum properties Diameter (width) of the wells of the number of wells with the resulting minimum surface area = 0.41 LIST OF REFERENCE NUMBERS

1 roller

2 sheet metal

3 structural element

4 deepening

Claims

claims

1 . Roller, in particular skin-pass mill, having a surface structure with stochastic distributed and stochastically large structural elements (3),

in particular for the production of flat products from a metal material, in particular from a steel material, characterized in that the

Structural elements (3) have a height in the range of 20 to 300 μηη, the

Structural elements (3) have a width in the range of 60 to 600 μηη and the structural elements (3) have a number of 5 to 60 per mm ² .

2. Roller according to claim 1, characterized in that the structural elements (3) have a height in the range of 25 to 100 μηη.

3. Roller according to claim 1 or 2, characterized in that the

Structural elements (3) have a width in the range of 90 to 170 μηη.

4. Roll according to one of claims 1 to 3, characterized in that the structural elements (3) have a number of 20 to 40 per mm ² .

5. Roller according to one of claims 1 to 4, characterized in that the surface structure has a roughness Ra of 4 to 14 μηη, preferably from 6 to 8 μηη having.

6. Roller according to one of claims 1 to 5, characterized in that the surface structure has a peak number RPc of 5 to 50 1 / cm, preferably from 20 to 30 1 / cm.

7. Roller according to one of claims 1 to 6, characterized in that the surface structure is electrolytically structured and hard chromium plated.

8. Roller according to one of claims 1 to 7, characterized in that the structural elements (3) are dome-shaped.

9. Flat product of a metal material, in particular coated with a roller (1) according to one of claims 1 to 8, having a surface structure with stochastic distributed and stochastically large depressions (4), characterized in that the depressions (4) have a depth in the range of 15 to 90 μηη, the

Wells (4) have a width in the range of 50 to 400 μηη, the

Recesses (4) have a number of 4 to 60 per mm ² and the sum of the area of the recesses (4) projected on the flat product has a surface area of 0.41 or greater.

10. Flat product according to claim 9, characterized in that the recesses (4) have a height in the range of 20 to 30 μηη.

1 1. A flat product according to claim 9 or 10, characterized in that the recesses (4) have a width in the range of 60 to 120 μηη.

12. Flat product according to one of claims 9 to 1 1, characterized in that the recesses (4) have a number of 20 to 30 per mm ² .

13. Flat product according to one of claims 9 to 12, characterized in that its surface structure has a roughness Ra of 0.8 to 4 μηη, preferably from 1 to 3 μηι.

14. Flat product according to one of claims 9 to 13, characterized in that its surface structure has a peak number RPc of 5 to 50 1 / cm, preferably from 20 to 30 1 / cm.

15. Flat product according to one of claims 9 to 14, characterized in that the recesses (4) are dome-shaped.

16. Flat product according to one of claims 9 to 15, characterized in that the thickness of the flat product (2) is in the range of 0.35 - 6.0 mm.

17. Flat product according to claims 9 to 16, characterized in that it is a steel sheet.

18. A flat product according to any one of claims 9 to 17, characterized in that the flat product (2) with coatings of zinc or tin or a zinc-aluminum Alloy or a zinc-iron alloy or zinc-aluminum-magnesium alloy or an aluminum-silicon alloy or an aluminum-zinc alloy or from organic material or a combination thereof is provided.