DE102022209741A1 - CUTTING BLADE AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

The present invention relates to a cutting blade and a method for producing the same. The cutting blade has a metallic substrate with a first cutting surface and a second cutting surface, which enclose a cutting edge, at least one DLC hard material layer being deposited on the substrate and at least one cover layer applied using a wet process being deposited on the DLC hard material layer on the side facing away from the substrate and wherein the one cover layer directly on the cutting edge has no cover layer or a cover layer with a reduced layer thickness compared to the remaining cover layer. The present invention further relates to a method for producing such cutting blades.

Description

The present invention relates to a cutting blade and a method for producing the same. The cutting blade has a metallic substrate with a first cutting surface and a second cutting surface, which enclose a cutting edge, at least one DLC hard material layer being deposited on the substrate and at least one cover layer applied using a wet process being deposited on the DLC hard material layer on the side facing away from the substrate and wherein the one cover layer directly on the cutting edge has no cover layer or a cover layer with a reduced layer thickness compared to the remaining cover layer. The present invention further relates to a method for producing such cutting blades.

According to the state of the art, there are numerous inventions which aim to optimize the cutting performance of knives, cutters, scissors or similar tools through coatings. However, all of the property rights listed below do not apply or only apply to a limited extent to household blades made of conventional stainless steel DIN EN 10020 (July 2000) applicable.

That's how it describes EP2495081B1 a cutting tool with a coating of fine crystalline diamond. This is applied using a hot wire CVD process at typical substrate temperatures between 600°C and 900°C. The substrate consists of temperature-resistant materials such as titanium, nickel, niobium, tungsten, hard metals or ceramics. These temperatures are significantly above the tempering temperature of stainless steels. Changing the material to one of the above would also lead to a significant increase in the cost of household knives.

The US 6,289,593 B1 describes a razor blade with a DLC layer and an edge rounding of less than 1200 Angstroms (corresponds to 0.12µm) and a layer thickness of at least 400 to 2000 Angstroms (corresponds to 0.04µm to 0.2µm). However, such small edge roundings and low layer thicknesses are not sufficient to significantly increase the edge retention of a household knife. This is due to the harsher operating conditions and handling of a household knife compared to a razor blade.

In DE 10 2019 200 681 A1 describes a multi-layer cutting tool in which the middle layer consists of hybridized carbon, which forms the cutting edge. Since the thickness of such layers is in the micrometer range, a cost-effective implementation is not possible from a manufacturing technology perspective. The cutting edge would have to be ground down to micrometer precision, which means a lot of effort. When applying larger layer thicknesses via thermal spraying, the disadvantage is the reduction in the corrosion resistance of typical stainless steel knife materials. In addition, the production of such a described multi-layer structure for consumer goods and in particular for knives with complex geometries is not economically possible.

The EP 3 683 332 A1 also describes a coating made of hybridized carbon on a carrier substrate, but in contrast to DE102019200681A1 has a three-dimensional structure. This structuring can be achieved by masking, but this is very complex. In addition to the additional effort, subsequent laser processing has the disadvantage that the corrosion resistance of a stainless steel substrate would be reduced due to the thermal energy input.

In DE 10 2004 052 068 B4 describes a cutting tool with a carrier layer made of metal and a second layer made of diamond-like carbon. Only the maximum edge rounding is defined here, but not the layer thickness. However, both parameters are essential for good initial sharpness as well as for maintaining cutting performance for as long as possible.

In EP 2 714 964B1 is a woodworking tool with a defined layer thickness and cutting edge rounding. However, if the sliding layer mentioned in claim 1 were to be omitted, which is essential for a cost-effective solution, this would result in different layer thicknesses and edge rounding. This should avoid a cost-intensive multi-layer system consisting of a sliding layer and a functional layer, which is coated in a two-stage process. Furthermore, the patent describes a base body made of hard metal, HSS, ceramic or a cermet, which is not a suitable material for household knives.

Another problem associated with the coating of consumer goods is increasing roughness caused by the DLC layer application. This effect increases as the layer thickness increases. The cause is layer growth errors - so-called droplets. A solution would be to use another coating process, for example HiPIMS or high-energy pulse magnetron sputtering, as in DE 10 2008 021 912 C5 or EP 2 017 366 B1 described. But this would be high cause costs and merely reduce the problem.

In general, carbon layers tend to be less cleanable when dirty. This problem is exacerbated by increased roughness, to the point that adequate cleaning using standard household means is no longer possible.

DE 10 2015 101 782 B4 describes a sliding layer applied to a DLC layer. A DLC or PLC layer is described here, which does not lead to a reduction in roughness or does not eliminate the increased roughness of the DLC base layer. Furthermore, the affinity of foods for carbon-containing layers makes them difficult to clean. In addition, a further PVD or CVD process would cause high costs and would probably lead to increasing cutting edge rounding and thus reduced sharpness.

EP 1 915 472 B1 also describes a multi-layer structure consisting of a hard tetrahedral carbon intermediate layer and a softer amorphous carbon top layer. The disadvantages with regard to the layer application as well as the layer material itself correspond to the patent cited above.

Based on this, it was the object of the present invention to eliminate the disadvantages of the prior art and to provide a cutting blade that is both sharp when delivered and also maintains the sharpness or cutting performance for as long as possible under increasing load. In addition, the cutting blade should be easy to clean using standard household products. In addition, the cutting blades should be able to be produced using cost-effective processes.

This object is achieved by the method for producing a cutting blade with the features of claim 1 and the cutting blade with the features of claim 9. The further dependent claims describe preferred embodiments.

1. a) auf einem Substrat mit einer ersten Schneidfläche und einer zweiten Schneidfläche, die eine Schneidkante einschließen, mittels physikalischer Dampfphasenabscheidung (PVD) eine DLC-Hartstoffschicht abgeschieden wird,
2. b) eine Beschichtungslösung mittels Tauch- und/oder Sprühverfahren auf der DLC-Hartstoffschicht appliziert wird, wobei die Beschichtungslösung eine Oberflächenspannung von 18 bis 40 mJ/m² aufweist, und
3. c) die Beschichtungslösung unter Ausbildung der Deckschicht getrocknet wird, wobei sich die Beschichtungslösung aufgrund ihrer Oberflächenspannung von der Schneidkante zurückzieht, so dass unmittelbar an der Schneidkante keine Deckschicht oder eine Deckschicht mit einer im Vergleich zur restlichen Deckschicht reduzierten Schichtdicke vorliegt.

According to the invention, a method for producing a cutting blade is provided, in which

1. a) a DLC hard material layer is deposited on a substrate with a first cutting surface and a second cutting surface, which include a cutting edge, by means of physical vapor phase deposition (PVD),
2. b) a coating solution is applied to the DLC hard material layer using dipping and/or spraying methods, the coating solution having a surface tension of 18 to 40 mJ/m ² , and
3. c) the coating solution is dried to form the top layer, the coating solution withdrawing from the cutting edge due to its surface tension, so that there is no top layer or a top layer with a reduced layer thickness compared to the remaining top layer directly on the cutting edge.

It is preferred that the at least one DLC hard material layer contains or consists of amorphous carbon, in particular tetrahedral amorphous carbon. The advantage of a layer made of tetrahedral amorphous carbon is its outstanding hardness and thus its wear resistance. In addition, other hard material layers are also conceivable, which can be applied using PVD, PECVD, CVD processes or thermal spraying.

In contrast to solutions known from the prior art, the cutting blade according to the present invention has the advantage that both good initial sharpness is ensured and long-lasting cutting durability is ensured.

A preferred embodiment provides that at least one DLC hard material layer with a thickness in the range from 1 to 5 μm, particularly preferably from 2 to 4 μm and more preferably from 2.5 to 3.5 μm, is deposited on the substrate.

A further preferred embodiment provides that in step c) a cover layer is formed directly on the cutting edge with a layer thickness reduced by a factor of 3, preferably by a factor of 5, particularly preferably by a factor of 10, compared to the remaining cover layer.

It is preferred that the at least one cover layer is deposited on the DLC hard material layer with a thickness in the range from 0.2 to 3 μm, preferably from 0.5 to 2.5 μm and particularly preferably from 1 to 2 μm. It is important to ensure that the layer thicknesses remain within a defined process window. A certain layer thickness is necessary to level out the micro-roughness. In addition, a certain layer thickness should not be exceeded for cost and layer liability reasons.

Furthermore, it is preferred that the coating solution has a surface tension in the range from 20 to 30 mJ/m ² , particularly preferably from 22 to 26 mJ/m ² .

The application of the coating or the complete coating process should preferably take place below 250°C, preferably below 220°C, particularly preferably below 200°C.

The coating solution preferably contains or consists of a polysilazane. No costly vacuum process is necessary. This can be applied by spraying or dipping after appropriate pre-cleaning with solvents. No costly vacuum process is necessary. In addition, the polysilazane layer is stable in the pH range from 3 to 12.

In addition to polysilazane layers, glass or glass-like layers or hybrid layers, layers based on ceramics or other anti-fingerprint coatings as well as polymer resin or fluoropolymer layers can preferably also be used.

It is preferred that the material of the metallic substrate is selected from the group consisting of steel, ceramic, hard metal and combinations thereof, in particular stainless steel. A preferred substrate is stainless steels with at least 10.5% chromium and at most 1.2% carbon, preferably more than 12% chromium and less than 0.8% carbon, particularly preferably more than 14% chromium and 0.4-0, 6% carbon. A stainless steel with the steel key 1.4116, 1.4125, 1.4031, 1.4028, 1.4021, 1.4034, 1.4122 or 1.4006 is particularly preferred. Further suitable steel keys can be found at www.edelstahl-rostfrei.de/fileadmin/user upload/ISER/images /publikationen/Dok Martensite final.pdf.

According to the invention, a cutting blade is also provided which contains a metallic substrate with a first cutting surface and a second cutting surface which include a cutting edge, with at least one DLC hard material layer on the substrate and at least one on the DLC hard material layer on the side facing away from the substrate a top layer applied in the wet process is deposited and wherein the one top layer has no top layer directly on the cutting edge or a top layer with a reduced layer thickness compared to the remaining top layer.

It is preferred that the at least one DLC hard material layer contains or consists of amorphous carbon, in particular tetrahedral amorphous carbon. A tetrahedral amorphous carbon layer is particularly suitable due to its outstanding hardness and thus its wear resistance.

A preferred embodiment provides that the at least one DLC hard material layer preferably has a hardness of at least 30 GPa, particularly preferably at least 34 GPa and very particularly preferably from 38 GPa to 45 GPA.

Preferably, the at least one DLC hard material layer has a thickness in the range from 1 to 5 μm, preferably from 2 to 4 μm and particularly preferably from 2.5 to 3.5 μm.

The cover layer preferably contains or consists of polysilazane, since polysilazane is stable in the pH range from 3 to 12. The top layer made of polysilazane has good chemical and mechanical resistance. The covalent bond to the substrate or the underlying DLC layer supports this.

The top layer should have good adhesion to the substrate or to the underlying DLC layer. The cover layer preferably has cross-cut characteristics of 0 to 2, particularly preferably 0 to 1, particularly preferably 0, determined in accordance with DIN EN ISO 2409.

In addition to polysilazane layers, glass or glass-like layers or hybrid layers, layers based on ceramics or other anti-fingerprint coatings as well as polymer resin or fluoropolymer layers can preferably also be used.

It is preferred that, directly on the cutting edge, the cover layer has a layer thickness reduced by a factor of 3, preferably by a factor of 5, particularly preferably by a factor of 10, compared to the remaining cover layer.

It is further preferred that the cover layer has a thickness in the range from 0.2 to 3 μm, preferably from 0.5 to 2.5 μm and particularly preferably from 1 to 2 μm.

The cover layer preferably has a surface roughness Ra of 0.05 to 0.22 µm, particularly preferably 0.08 to 0.20 µm.

The cover layer preferably has a surface tension of 10 to 30 mJ/m ² , particularly preferably of 15 to 25 mJ/m ² . This ensures easy cleaning when dirty.

It is preferred that the material of the metallic substrate is selected from the group consisting of steel, ceramic, hard metal and combinations thereof, in particular stainless steel. A preferred substrate is nonros tending stainless steels with at least 10.5% chromium and at most 1.2% carbon, preferably more than 12% chromium and less than 0.8% carbon, particularly preferably more than 14% chromium and 0.4-0.6% carbon. Stainless steel with steel key 1.4116 is particularly preferred.

It is preferred that the angle between the first cutting surface and the second cutting surface is in the range from 15° to 40°, preferably from 20° to 35° and particularly preferably from 25° to 32°.

To achieve good initial sharpness, the rounding radius of the cutting edge is preferably in the range of 1 to 6 μm, particularly preferably in the range of 1.5 to 5 and very particularly preferably in the range of 2 to 4 μm.

The subject matter according to the invention will be explained in more detail using the following figures and the example, without wishing to limit it to the specific embodiments shown here.

• 1 eine Schnittdarstellung der erfindungsgemäßen Schneidklinge
• 2 eine erste mikroskopische Aufnahme der Schneidkante der erfindungsgemäßen Schneidklinge
• 3 eine weitere mikroskopische Aufnahme der Schneidkante der erfindungsgemäßen Schneidklinge aus 2 in höherer Auflösung
• 4 eine weitere mikroskopische Aufnahme der erfindungsgemäßen Schneidklinge hinsichtlich des Aufbaus der Beschichtung
• 5 ein Diagramm zur Schneidleistung der erfindungsgemäßen Schneidklinge im Vergleich zu einer unbeschichteten Schneidklinge des Standes der Technik

Show it

• 1 a sectional view of the cutting blade according to the invention
• 2 a first microscopic photograph of the cutting edge of the cutting blade according to the invention
• 3 a further microscopic photograph of the cutting edge of the cutting blade according to the invention 2 in higher resolution
• 4 another microscopic photograph of the cutting blade according to the invention with regard to the structure of the coating
• 5 a diagram of the cutting performance of the cutting blade according to the invention in comparison to an uncoated cutting blade of the prior art

In 1 a cutting blade 1 according to the invention is shown. The cutting blade 1 consists of a substrate 2, with the first cutting surface 3 and the second cutting surface 4 having a coating made of a DLC hard material layer 6. The DLC hard material layer is in turn provided with a cover layer 7 made of polysilazane. From the illustration in 1 It can be seen that on the cutting edge 5 the cover layer 7 has a layer thickness that decreases towards the cutting edge 5, which is due to the edge alignment.

In 2 a microscopic photograph of the cutting blade 1 according to the invention is shown in the area of the cutting edge 5. The cutting edge 5 is surrounded by the first cutting surface 3 (top) and the second cutting surface 4 (bottom).

3 shows analogously to 2 a cutting blade 1 according to the invention in the area of the cutting edge 5, but in higher resolution.

4 shows a microscopic photograph of a cutting blade 1 according to the invention in a sectional view, which illustrates the structure of the coating. The substrate 2 is here coated with a DLC hard material layer 6. The DLC hard material layer has a layer thickness of 2.58 µm. The DLC hard material layer 6 is coated with a top layer of polysilazane 7, with an interface 8 between the two coatings being visible. The top layer has a layer thickness of 1.51 µm. In 4 It can be seen that in areas 9, 10, in which the DLC hard material layer 6 has a higher or lower layer thickness due to an inhomogeneous coating, the cover layer 7 can compensate for these deviations and has a smoothing effect, so that the surface of the cover layer 7 has a very low surface roughness, making the surface very easy to clean.

In 5 The cutting performance of a cutting blade according to the invention is shown in comparison to an uncoated steel knife using a diagram. It can be seen from this that in the case of an uncoated steel knife according to the prior art, the cutting depth decreases rapidly after just a few cutting cycles, while the cutting depth in the cutting blade according to the invention remains virtually constant even after 60 cutting cycles.

Example

First, the raw blade is made from the selected material. Due to the manufacturing process, this can be done by cutting a strip steel knife (by laser, punching, etc.) or by cutting and forging a forged blade. The blade material preferably consists of a martensitic corrosion-resistant steel, such as the material 1.4116 or X50CrMoV15, which offers a good combination of hardness and corrosion resistance. In addition, other steel alloys are also suitable in principle.

The next process step is tempering the blade. The blade is hardened in a hardening process and then tempered once or several times. This two-stage process serves to increase wear resistance and subsequently optimize toughness. Processes like this are widespread in industry. In order to achieve a uniform and fine grain size, normalizing may be necessary beforehand.

The hardened raw blade is then ground or polished in a usually multi-stage process. This achieves the final contour in terms of dimensional accuracy, creates an attractive appearance and improves corrosion resistance.

One of the last steps is attaching or grinding the cutting edge. The cutting angle is typically on the order of 15° to 40°, preferably from 20° to 35°, particularly preferably from 25° to 32°. The rounding of the cutting edges is also crucial for the initial sharpness. This should have a rounding radius of less than 6µm, preferably less than 5µm, particularly preferably less than 4µm.

The DLC layer application follows. As a rule, pre-cleaning (wet chemical, ultrasound, etc.) is required, as well as, if necessary, fine plasma cleaning in the PVD system to activate the surface before the actual DLC layer application in the same system. It is preferable to choose a tetrahedral amorphous layer which has outstanding wear resistance. The hardness of this layer should be at least 30GPa, preferably at least 34GPa, particularly preferably at least 38GPa. To improve adhesion, an adhesion promoter layer may be required which consists of or contains chromium or titanium.

The layer thickness should be applied in the order of 1 to 5 μm, preferably from 2 to 4 μm, particularly preferably from 2.5 to 3.5 μm. Good layer adhesion to the substrate or cutting edge is also very important. The layer adhesion should be between HF1 and HF3, preferably between HF1 and HF2, particularly preferably HF1 - tested according to DIN 4856.

The last coating step is to apply the top layer, which is preferably a polysilazane layer. In addition to polysilazane layers, glass or glass-like layers or hybrid layers, layers based on ceramics or other anti-fingerprint coatings as well as polymer resin or fluoropolymer layers can preferably also be used. The layer application ensures a reduction in roughness and also ensures that the knife can be cleaned using standard household products.

The knife is usually cleaned before applying the coat. The polysilazane layer can be applied by dipping or spraying and is then dried or baked in an oven. The dried coating has a surface tension in the range from 20 to 30 mJ/m ² , particularly preferably from 22 to 26 mJ/m ² . This essentially improves cleanability. The layer thickness is in the range from 0.2 to 3 μm, preferably from 0.5 to 2.5 μm and particularly preferably from 1 to 2 μm. The top layer should have good adhesion to the substrate or to the underlying DLC layer. The cover layer preferably has cross-cut characteristics of 0 to 2, particularly preferably 0 to 1, particularly preferably 0, determined in accordance with DIN EN ISO 2409.

When drying, the effect of edge alignment also means that the top layer has a reduced layer thickness when dried compared to the remaining top layer. The reduction in the layer thickness from the side surface to the cutting edge is in the order of a factor of 3, preferably a factor of 5, particularly preferably a factor of 10. This means that rounding of the cutting edge is reduced to the lowest possible level and thus a measurable reduction in sharpness is avoided.

If this has not already been done in a previous operation, the handle is attached.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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

• EP 2495081 B1 [0003]
• US 6289593 B1 [0004]
• DE 102019200681 A1 [0005, 0006]
• EP 3683332 A1 [0006]
• DE 102004052068 B4 [0007]
• EP 2714964 B1 [0008]
• DE 102008021912 C5 [0009]
• EP 2017366 B1 [0009]
• DE 102015101782 B4 [0011]
• EP 1915472 B1 [0012]

Non-patent literature cited

• DIN EN 10020 [0002]

Claims (20)

Method for producing a cutting blade (1), in which a) a DLC is carried out on a substrate (2) with a first cutting surface (3) and a second cutting surface (4), which enclose a cutting edge (5), by means of physical vapor phase deposition (PVD). -Hard material layer (6) is deposited, b) a coating solution is applied to the DLC hard material layer (6) by dipping and/or spraying methods, the coating solution having a surface tension of 18 to 40 mJ/m ² , and c) the coating solution is dried to form the cover layer (7), the coating solution withdrawing from the cutting edge (5) due to its surface tension, so that directly on the cutting edge (5) there is no cover layer (7) or a cover layer (7) with a compared to remaining cover layer (7) has a reduced layer thickness. Procedure according to Claim 1 , characterized in that the at least one DLC hard material layer (6) contains or consists of amorphous carbon, in particular tetrahedral amorphous carbon. Procedure according to one of the Claims 1 or 2 , characterized in that the at least one DLC hard material layer (6) is deposited on the substrate (2) with a thickness in the range from 1 to 5 µm, preferably from 2 to 4 µm and particularly preferably from 2.5 to 3.5 µm becomes. Procedure according to one of the Claims 1 until 3 , characterized in that in step c) directly on the cutting edge (5) a cover layer (7) with a layer thickness reduced by a factor of 3, preferably by a factor of 5, particularly preferably by a factor of 10, compared to the remaining cover layer (7). , is formed. Procedure according to one of the Claims 1 until 4 , characterized in that the at least one cover layer (7) with a thickness in the range from 0.2 to 3 µm, preferably from 0.5 to 2.5 µm and particularly preferably from 1 to 2 µm on the DLC hard material layer (6 ) is deposited. Procedure according to one of the Claims 1 until 5 , characterized in that the coating solution has a surface tension in the range from 20 to 30 mJ/m ² , particularly preferably from 22 to 26 mJ/m ² . Procedure according to one of the Claims 1 until 6 , characterized in that the coating solution contains a polysilazane. Procedure according to one of the Claims 1 until 7 , characterized in that the material of the metallic substrate is selected from the group consisting of steel, ceramic, hard metal and combinations thereof, in particular a stainless steel, preferably a stainless steel with the steel key 1.4116, 1.4125, 1.4031, 1.4028, 1.4021, 1.4034, 1.4122 or 1.4006 . Cutting blade (1) containing a metallic substrate (2) with a first cutting surface (3) and a second cutting surface (4), which include a cutting edge (5), wherein on the substrate (2) at least one DLC hard material layer (6) and At least one top layer (7) applied using the wet process is deposited on the DLC hard material layer (6) on the side facing away from the substrate (2), and the one top layer (7) directly on the cutting edge (5) does not have a top layer (7) or one Cover layer (7) has a reduced layer thickness compared to the remaining cover layer (7). cutting blade Claim 9 , characterized in that the at least one DLC hard material layer (6) contains or consists of amorphous carbon, in particular tetrahedral amorphous carbon. Cutting blade according to one of the Claims 9 or 10 , characterized in that the at least one DLC hard material layer (6) has a hardness of at least 30 GPa, preferably at least 34 GPa, particularly preferably from 38 GPa to 45 GPa. Cutting blade according to one of the Claims 9 until 11 , characterized in that the at least one DLC hard material layer (6) has a thickness in the range from 1 to 5 µm, preferably from 2 to 4 µm and particularly preferably from 2.5 to 3.5 µm. Cutting blade according to one of the Claims 9 until 12 , characterized in that the cover layer contains polysilazane or consists of polysilazane. Cutting blade according to one of the Claims 9 until 13 , characterized in that directly on the cutting edge (5), the cover layer (7) has a layer thickness reduced by a factor of 3, preferably by a factor of 5, particularly preferably by a factor of 10, compared to the remaining cover layer (7). Cutting blade according to one of the Claims 9 until 14 , characterized in that the cover layer (7) has a thickness in the range of 0.2 to 3 µm, preferably from 0.5 to 2.5 µm and particularly preferably from 1 to 2 µm. Cutting blade according to one of the Claims 9 until 15 , characterized in that the cover layer has a surface roughness Ra of 0.05 to 0.22 µm, preferably 0.08 to 0.20 µm. Cutting blade according to one of the Claims 9 until 16 , characterized in that the material of the metallic substrate is selected from the group consisting of steel, ceramic, hard metal and combinations thereof, in particular a stainless steel, preferably a stainless steel with the steel key 1.4116. Cutting blade according to one of the Claims 9 until 17 , characterized in that the angle between the first cutting surface (3) and the second cutting surface (4) is in the range from 15° to 40°, preferably from 20° to 35° and particularly preferably from 25° to 32°. Cutting blade according to one of the Claims 9 until 18 , characterized in that the cutting edge (5) has a rounding radius of 1 to 6 µm, preferably 1.5 to 5 and particularly preferably 2 to 4 µm. Cutting blade according to one of the Claims 9 until 19 and can be produced by the process according to one of the Claims 1 until 8th .

Images