EP1688224B1 - Knife with bolster obtained by upset forging - Google Patents

Description

The present invention relates to a knife with a knife drop and a method for producing such a knife.

Knives of the aforementioned type and corresponding manufacturing methods are already known. In the classical method of production, the knife, consisting of knife edge, knife drop and knife blade, forged in one piece. Since the knife edge, knife drop and knife blade have considerable differences in their cross-sectional area, the largest cross-sectional area, ie usually that of the crop, is decisive for the choice of the blank cross-sectional area in the classical production method. This blank section must then be rejuvenated to produce knife blade and Messererl by forging (drop forging), which has proven to be very expensive, since, for example, the cross-sectional areas of crop and cutting edge are very different.

The U.S. Patent 689,046 and the FR-PS 694 520 describe a knife and its manufacture, wherein knife edge, Knife drip and Messererl separated from each other, possibly made of different materials, forged and then welded together. Compared to the classical production method described above, the production costs are reduced. Due to process-related imprecise production of individual components, however, considerable reworking is also required here, especially at the joining surfaces for the welding process.

The EP-A-0429035 describes a knife and its manufacture, in which the knife edge, knife drip and Messererl also produced individually and then welded together. Here, however, the knife drop is not forged but sintered, whereby a more precise production of the crop and thus an improvement in the surface quality of the joining surfaces required for the subsequent welding process is possible. Post-processing is usually not necessary here. However, the individual components must be welded together after their preparation, whereby the number of steps is very high. Furthermore, the sintering of the knife drop is quite expensive and takes a comparatively long time.

The document GB-A-692,042 describes a knife with an upset forged knife drip and its manufacture.

It is an object of the present invention to provide a knife with Knife drip that can be produced in a simple manner, in as few steps as possible and inexpensive from alternative material.

This object is achieved according to the present invention by a meter according to claim 1 and by a method according to claim. 13

The knife according to the invention comprises a compression-forged knife drip. In compression forging, the cross-section of the blank in the machined area is not reduced but rather increased, so that no longer the largest cross-sectional area, ie the cross-sectional area of the crop, is decisive for the choice of the blank cross-section. According to the invention, a substantially flat blank can be used, the cross-sectional area of which corresponds to that of the knife edge and / or the knife edge. This blank is then compressed in the region of the knife drop to be produced, so that the blank folds up there until the desired larger cross-sectional area for the crop is created. A significant advantage is that when forging the blank only the Knife drip must be processed, but not knife edge and Messererl. This has the advantage that the material thickness of Erl and cutting edge and thus the original steel quality is maintained. Also, the center axis of the blank and its initial thickness are only slightly influenced by the forging process, so that the processing result is much more precise. The dimensional variations of a lot and the component tolerances are compared to conventional forging much lower. The precision-made forging blank also has a positive influence on the precision and quality of all following processing steps. The shape of knife edge and Messererl can be punched out simply following the forging process, for example, since the blank used already has the required cross-sectional area for knife edge and Messererl. Another advantage is that the knife consisting of knife edge, Knife handle and Messererl can be formed from a one-piece blank, but the production is more precise and less expensive compared to the classical production method. The preparation of a one-piece blank is compared to the production of several blanks to the effect that a joining of knife edge, Knife handle and Messererl is not required. Correspondingly, both work steps and the requirements for the joining surfaces required for welding are eliminated.

As already mentioned above, the knife edge, knife drop and knife blade are preferably integrally formed for the reasons mentioned.

The blank used advantageously comprises a plurality of layers of material, wherein at least one layer of material has a high hardness, preferably between 54 and 70 HRC, better still in the range of 66 HRC. This at least one material layer with high hardness forms the cutting surface of the finished knife. The material used is preferably steel, whose carbon content depends on its hardenability. The carbon content should not fall below 0.5 wt .-%, on the other hand, 2 wt .-% not exceed, otherwise the steel is too brittle and is therefore prone to breakage. The steel may further comprise other alloying elements such as manganese, chromium, molybdenum, vanadium or tungsten. Manganese makes the steel stronger and better forgeable. Chromium also increases the strength of the steel, making it more resistant to abrasion through the formation of chromium carbides and increasing its corrosion resistance. From a chromium content of approx. 12%, a steel is considered to be rust-free or rust-resistant. Molybdenum increases the cutting and durability of the steel, especially in conjunction with vanadium. Tungsten finally increases the strength, increases the hardness and edge retention significantly. By choosing the alloying elements and their proportions special properties of the steel can be adjusted. Hardness, cutting strength However, they are in the foreground because of the fact that this material layer should form the cutting surface.

The at least one material layer with high hardness is preferably arranged in the core region of the blank and thus of the later produced cutler, so that the cutting surface of the knife to be produced is arranged centrally. This hard material layer can also be arranged out-of-center, should this be desired. The core area advantageously comprises at least 50% of the total knife edge thickness or the Gesamtmesserschneidenquerschnittsfläche so that, for example, when grinding or regrinding the finished knives actually the cutting surface is ground. In order that the core region is arranged as centrally as possible, the number of material layers is advantageously odd.

The remaining layers of material, which preferably surround the hard core region, preferably have a lower hardness than the core region and are essentially free of rust. The latter has the advantage that the carbonaceous steel of the core region, which tends to rust very much, is protected from the atmosphere by the surrounding stainless material layers.

The visible material layer transitions, for example on the back of the knife, on the knife drop or on the knife edge, are preferably etched in order to make visible the pattern resulting from the multiple layering. This has essentially optical reasons. In particular, the upset forged knife drop has due to the folding of the multi-layer blank on an individual pattern reminiscent of Damascus steel.

In accordance with the method according to the invention, the knife edge, knife drop and knife edge are preferably formed from a one-piece blank. In this way can be dispensed with after the forging on any joining operations. By the formation of the crop by compression forging is ensured even with one-piece blank that the production is precise and not too expensive.

The blank is preferably punched out of a multilayer sheet metal, heated by means of resistance heating and compressed or folded in the compression forging step in the region of the crop to be produced.

The compression forging step or the result of the compression forging step depends essentially on the compression path, the compression speed and the temperature control. The temperature is preferably 1050 ° C, the temperature is material dependent.

The compression forging step is preferably followed by a precision forging step, in particular in order to work out individual contours of the knife drop exactly. The result of the precision forging step depends essentially on the travel speed of the upper tool, the pressing force, the travel, the contact time and the coolant used. Preferably, the precision forging of the crop comprises only one stroke.

Finally, the knife contour is preferably trimmed or punched out.

The method described above allows a very precise and inexpensive production, the method comprises little process steps and manages without any joining steps. Power consumption, steel use, area and noise are significantly reduced.

The blank used for the method described above comprises, as described above, several layers, preferably with a centrally arranged steel layer with high hardness, which is ultimately to form the cutting surface of the knife. In the production of the blank a plurality of sheet metal layers are plated and cold rolled, so that sheets are formed from which the blanks can be punched out.

Hereinafter, the present invention will be described in detail with reference to the drawings. Put in it Fig. 1 to Fig. 5 individual results of successive process steps according to a preferred embodiment of the method according to the invention.

Fig. 1

eine Draufsicht eines gemäß einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens verwendeten Rohlings;

Fig. 2

eine Draufsicht des in Fig. 1 dargestellten Rohlings nach Durchführung des erfindungsgemäßen Stauchschmiedeschrittes;

Fig. 3

eine Draufsicht des in Fig. 2 dargestellten Rohlings nach Durchführung eines Präzisionsschmiedeschrittes;

Fig. 4

eine Draufsicht des in Fig. 3 dargestellten Rohlings nach Durchführung eines Abgratschrittes;

Fig. 5

eine Draufsicht des durch den Abgratschritt erzeugten Abfallteils, das als Stahlschrott der Verwertung zugeführt wird und

Fig. 6

eine vergrößerte Querschnittsansicht des gestauchten, mehrlagigen Messerkropfes.

In detail shows:

Fig. 1

a plan view of a blank used in accordance with a preferred embodiment of the method according to the invention;

Fig. 2

a top view of the in Fig. 1 shown blank after performing the compression forging step according to the invention;

Fig. 3

a top view of the in Fig. 2 shown blank after performing a precision forging step;

Fig. 4

a top view of the in Fig. 3 shown blank after performing a trimming step;

Fig. 5

a top view of the waste produced by the trimming step, which is supplied as steel scrap for recycling and

Fig. 6

an enlarged cross-sectional view of the compressed, multi-layer knife drop.

Fig. 1 shows a blank 10, which is used for carrying out a preferred embodiment of the method according to the invention. The blank 10 is a strip of multi-layer steel, for example, 3-ply up to Damascus steel-like Clad composites, z. B. 33-ply. The blank 10 has, in the middle of its cross-sectional area, a layer of high hardness steel, here 66 HRC. This material layer occupies about 50% of the total knife cutting thickness or Gesamtmesserschneidenquerschnittsfläche and forms the cutting surface of the knife to be generated.

The in Fig. 1 shown blank 10 was punched out of a large, cold-rolled multi-layer steel sheet having the desired cross-sectional area of knife edge and Messererl. Accordingly, the blank 10 has the corresponding cross-sectional area.

Fig. 2 shows the in Fig. 1 shown blank 10 after performing the compression forging step according to the invention. As can be seen, the material in the region 12 at which the knife drop to be produced is to be formed has been folded in such a way that the cross-sectional area in the region 12 has been increased in accordance with the desired cross-sectional area of the knife drop. The areas 14 and 16, from which later knife edge and Messererl are generated, were not changed by the compression step substantially. The upsetting is done by resistance heating. At this point it should be clear that the heating can also be done in other ways.

Fig. 3 shows the in Fig. 2 shown blank 10 now after performing a precision forging step, with the shape of the knife drop 18 was formed in the area 12. Precision forging is performed by performing a single stroke. Furthermore, more than one stroke may be performed in the precision forging step, and it is of course preferred that the shape of the knife drop can be made sufficiently precise by a single stroke. As in Fig. 3 can be seen, remain the areas 14 and 16, from which the knife edge and knife ridge are produced, even during the performance of the precision forging step substantially unchanged.

Fig. 4 shows the finished part 20, which arises when the in Fig. 3 shown blank 10 is subjected to a trimming step. In this trimming step, the respective contour of the knife edge 22, the knife drop 18 and the knife edge 24 is punched out.

Fig. 5 shows the Abgratteil 26 correspondingly produced by the trimming step As can be seen, arises in the inventive method, only a small amount of waste.

Fig. 6 Finally, shows an enlarged cross-sectional view of the compressed, multi-layered knife drop 18. The substantially centered, ie in the core region arranged material layer 28 with high hardness extends meandering folded by the Knife Drip 18. It occupies about 50% of the cross-sectional area and is of other, much thinner and likewise folded material layers 30 surrounded in Fig. 6 however, are indicated only in certain areas. It should be clear that layers of material 30 extend through the entire crop 18 above and below the material layer 28 and run in accordance with the deformation of the crop 18. These material layers 30 are softer than the material layer 28 and are resistant to corrosion in order to protect the material layer 28 from negative influences of the atmosphere. Based Fig. 6 It can be seen that the individual patterning can be brought to light by a corresponding polished section and by etching the ground surface, which in particular can be optically desirable.

It should be understood that the preferred embodiment of the method of the invention described above, as well as the knife-cutter knife blade of the invention exemplified, are not limiting with respect to the scope of protection defined by the appended claims. Rather, modifications and changes are possible without departing from it.

LIST OF REFERENCE NUMBERS

10

blank

12

Area

14

Area

16

Area

18

bolster

20

precast

22

knife edge

24

tang

26

Abgratteil

28

central material layer

30

further material situation

Claims (28)

1. Knife with an upset forged bolster (18) characterized in that the knife comprises a plurality of material layers (28, 30).
2. Knife according to Claim 1, characterized in that the knife blade (22), bolster (18) and tang (24) are made in one piece.
3. Knife according to Claim 1, characterized in that the plurality of material layers (28, 30) consist of multilayer steel.
4. Knife according to Claim 1 or Claim 3, characterized in that at least one material layer (28) has high hardness.
5. Knife according to Claim 4, characterized in that the hardness of this at least one material layer (28) is 54 to 70 HRC and preferably lies in the region of 66 HRC.
6. Knife according to Claim 4 or Claim 5, characterized in that the material layer (28) of high hardness is hardened steel with a carbon content of between 0.5% and 2%.
7. Knife according to any one of Claims 4 to 6, characterized in that the at least one material layer (28) of high hardness is arranged substantially centrally in a core region.
8. Knife according to Claim 7, characterized in that the thickness of the core region is at least 50% of the total thickness of the knife blade.
9. Knife according to any one of Claims 1 and 3 to 8, characterized in that the number of material layers (28, 30) is odd.
10. Knife according to any one of Claims 4 to 9, characterized in that the other material layers (30) have lower hardness than the material layer (28) of high hardness.
11. Knife according to any one of Claims 4 to 10, characterized in that the other material layers (30) are substantially stainless.
12. Knife according to any one of Claims 1 and 3 to 11, characterized in that visible material-layer transitions are, at least partially, lightly etched.
13. Process for the manufacture of a knife with a bolster including an upset forging step to form the bolster (18), characterized in that the blank (10) used in the upset forging step comprises a plurality of material layers (28, 30).
14. Process according to Claim 13, characterized in that the blank (10) used in the upset forging step is preheated.
15. Process according to Claim 14, characterized in that the blank (10) is preheated by resistance heating.
16. Process according to any one of Claims 13 to 15, characterized in that the blank (10) used in the upset forging step is cold rolled.
17. Process according to any one of Claims 13 to 16, characterized in that the blank (10) used in the upset forging step comprises at least one material layer (28) of high hardness.
18. Process according to Claim 17, characterized in that this at least one material layer (28) has a hardness of 54 to 70 HRC, and better still, a hardness in the region of 66 HRC.
19. Process according to Claim 17 or Claim 18, characterized in that this at least one material layer (28) is hardened steel with a carbon content of between 0.5% and 2%.
20. Process according to any one of Claims 17 to 19, characterized in that this at least one material layer (28) is provided substantially centrally in the core region of the blank (10).
21. Process according to any one of Claims 17 to 20, characterized in that the other material layers (30) have lower hardness than the material layer (28) of high hardness.
22. Process according to any one of Claims 17 to 21, characterized in that the other material layers (30) are substantially stainless.
23. Process according to any one of Claims 13 to 22, characterized in that the blank (10) used in the upset forging step is punched out.
24. Process according to any one of Claims 13 to 23, characterized in that the knife blade (22), bolster (18) and tang (24) are made from a one-piece blank (10).
25. Process according to any one of Claims 13 to 24, characterized in that the forging step is followed by a precision forging step for the further shaping of the bolster (18).
26. Process according to Claim 25, characterized in that the precision forging step consists of a single stroke.
27. Process according to any one of Claims 13 to 26, characterized in that the contour of the knife with its bolster (18) is deburred.
28. Process according to any one of Claims 13 to 27, characterized in that visible material-layer transitions are, at least partially, lightly etched.

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