EP1588786B1 - Straw chopper blade and counter-blade for a straw chopper and method of manufacturing thereof - Google Patents

Description

The invention relates to a method for producing knives made of steel according to the preamble of claim 1 and a knife according to the preamble of claim 15.

Background of the invention

Such knives are used in choppers - generally in devices for chopping straw and the like. Such devices can be found, for example, on combine harvesters. They are provided with a rotating roller or drum on which a plurality of chopping knives are fixed or oscillating, distributed both over the drum length and over the drum circumference. These devices chop the supplied cutting material between the moving blades and the fixed counter knives small. The shredded material is forwarded by appropriate Leiteinrichtungen.

From the DE-PS 36 26 456 are knives with rectangular cross-sections are known, having on their longitudinal sides ground cutting edges, which extend over about three quarters of the length or even over the entire length of a knife.

From the EP 0 538 599 and the DE-U-94 16 851 , for example, correspond to the preamble of claims 1 and 15, knives are known at the cutting edges serrations are ground. The fact that the cutting edges are produced by grinding, resulting in loading of the knife unfavorable for a possible deformation of the cutting tools voltage curve, since the tapered surfaces are produced by a material-separating machining, which not only grooves on the surface of the inclined surfaces arise favor a notch effect, but also the fiber or texture course of the knife usually made of strip material is interrupted.

The service life and stability of such knives essentially determine the reliable function of chopping devices which, inter alia, only work without vibration when the rotating drums are equipped with cutting tools of the same size. Must z. For example, if a broken knife is to be replaced, the knife placed on the opposite side of the drum must also be replaced to restore balance.

The invention

The object of the invention is therefore to propose a chopper blade and a production method thereof for Häckselvorrichtungen, by which the cutting resistance and resistance to bending, twisting and breaking are significantly improved. Chopping blades also need to be manufactured in extremely tight weight limits become. The production must be process-reliable. According to the invention, this object is solved by the features of claims 1 and 15.

Knife for chopping devices need not have particularly sharp, but durable as possible resistant cutting. In order to achieve this result, in the past the blade's longitudinal edges have been ground like a prism and then the entire knife has been hardened. It has been found that a beveling step for the entire knife can be omitted if the prismatic cutting edges are produced by a rolling process by way of material forming, resulting in a slightly rounded, sufficiently sharp but resistant cutting edge. In such cutting edges cracks and resulting fractures, as they were favored in material-removing processing by grinding or the like.

According to the invention, a strip material, ie a flat steel, is used to produce the cutting tools. The lateral edges (longitudinal edges) of the strip material receive one-sided or two-sided oblique surfaces, in particular by cold rolling, that is by a forming process. The chamfers can be arranged in different ways, so that arise trapezoidal, parallelogram or double wedge-like cross-sections of the knife. But other cross-sectional training are possible, the z. B. caused by uneven chamfers or combinations of different profiles.

In an advantageous development of the invention, the cutting edge is provided with a radius of <0.3 mm. By virtue of this design, such a cutting edge is less susceptible to foreign body damage than a sharply ground edge. Furthermore, the service life of such an edge is increased. The rounding of a previously sharp edge results anyway after a short operating time. In addition, the impact force distributed to a knife edge of the type described above much better than on a sanded-off edge when the drum of the chopper comes to a standstill and advance the swinging blades by their centrifugal force, and impinge with their cutting edges on the drum cylinder.

If, as is preferred, the forming of the longitudinal edges of the flat steel by rolling along the entire flat steel length, this step is not only particularly economical, but the knife receives over its entire length increased by the deformation-induced rolling texture edge strength.

For chopper knives, extremely tight weight limits of the order of +/- 1 gram per knife must be observed. This task, which in itself was very difficult, could in the past be maintained with some difficulty by the grinding process in producing prism-shaped cutting edges. It has been shown that it is extremely difficult to ensure the narrow weight limits in the inventive rolling of the cutting edges until sufficient sharpness, so the prevention of Anwalzens. According to one embodiment of the invention, therefore, various steps - even individually or in combination with each other - proposed: If the longitudinal edges of a rectangular in cross-section starting material are machined by rollers before forming into prism-shaped cutting edges, thereby not only advantageous for the subsequent rolling Smoothing of the cutting edges are achieved, but also a cross-sectional correction of the starting material, which is advantageous for the subsequent weight stability. This is especially true if the starting material is produced from a so-called broadband flat steel by longitudinal gaps. A machining step on the longitudinal edges can therefore be used for edge cleaning and / or adjustment of the cross-sectional volume.

In order to obtain prism-shaped cutting edges of high quality formed by rolling to cutting edges until they are sufficiently sharp, it is particularly advantageous if the longitudinal edges of a starting material which is rectangular in cross-section are formed by edge rolling be smoothed out first. As a result, the microstructure of the cutting edge is significantly improved.

In order to maintain the weight stability, in particular the cross-sectional volume in the required for rotating chopper narrow limits, it is particularly advantageous if rolls are used for width calibration between successive pairs of profile rolls for forming the longitudinal edges to prism-shaped cutting by rolling to sufficient sharpness. As a result, the flow of material between successive pairs of profile rollers is controlled in a manner which promotes the formation of high quality rounded cutting edges.

The wear behavior of chopping blades according to the invention can be further improved by inserting at least one cemented carbide piece into the cutting edge. Such trained chopping blades are of independent inventive importance. The cemented carbide may - but does not necessarily have to - actively participate in the chopping process due to its own cutting edges. If such a cemented carbide insert is arranged in the vicinity of the free end of the chopper blade, thereby the wear of the entire cutting edge is significantly counteracted, because at this point the burden of foreign objects of greater hardness, such as small stones, is greatest. Such carbide inserts usually have a greater width than the cutting edge and are therefore particularly well able to throw away foreign objects. Due to their width, such hard metal inserts also have an advantageous effect on the degree of destruction of the surface of the shredded material.

If, according to another embodiment of the invention, a plurality of cutting blades are combined to form a cutting blade package, results in an overall thicker cutting blade, with a plurality of approximately mutually parallel cutting edges. Such an arrangement, which is advantageously used, not only leads to a greater crushing of the shredded material, but also to a better destruction or at least violation of the outer skin layers or cell structures of the shredded material, whereby z. B. the rotting behavior of the shredded material is improved.

Any embossing step for cross-section profiling of the knife for stiffening in the longitudinal direction is preferably carried out after the production of the prism-shaped cutting edges by the rolling process. Longitudinal edge deflections which occur approximately as a result of the embossing step thus do not adversely affect the rolling step.

Particularly economical is the production by the method according to the invention, when a steel strip along its one or preferably its two longitudinal edges continuously provided with prism-shaped cutting edges by appropriately profiled rollers and the chopping blades are made by separating sections of suitable length and subsequent processing.

Overall, therefore, the invention achieves sufficient sharpness of the chopper blade along both longitudinal edges along the full length and avoids an energy-consuming and time-consuming grinding operation as well as damage to the texture caused by grinding.

The above-described invention is not only suitable for the chopping blades moving on rotating drums, but also for the counter blades engaging in the axial spacing gaps between these moving chopping knives.

Overall, the invention overcomes difficulties that are triggered by conflicting requirements. By roll forming to sufficient sharpness cutting edge grinding is avoided the associated structural damage in the cutting edge region. However, chaff in very tight weight tolerances can be achieved without the well-known in the prior art correction option by the cutting edge grinding when calibrating rolling steps are made at the longitudinal edges.

The abovementioned and the claimed components to be used according to the invention described in the exemplary embodiments are not subject to any special exceptional conditions in terms of their size, shape design, material selection and technical design, so that the selection criteria known in the field of application can be used without restriction.

Further details, features and advantages of the subject matter of the invention will become apparent from the dependent claims and from the following description of the accompanying drawings, Fig. 3 to Fig. 11 B, in which - exemplary - preferred embodiments of inventive chopping blades are shown. In the drawing show:

Brief Description

Fig. 1

a chopper knife according to the prior art with two ground cutting edges in a perspective view;

Fig. 2

the section A'-B 'through the knife shown in Figure 1;

Fig. 3

a chopper blade according to the invention with two cutting edges produced by cold forming in a perspective view;

FIGS. 4A to 4F

six cross sections through chopping blades with bevels produced by cold or hot forming;

Fig. 5 A

a double wedge-like cross-section through a chopper blade with bevels produced by cold or hot working and rounded cutting edges without embossing;

Fig. 5B

another chopping knife in a perspective view with embossing;

Fig. 5C

another chopping knife with different carbide cutting inserts;

Fig. 6

a cross-sectional view (polished section) of a prism-shaped blade according to the invention formed by rolling to sufficient sharpness with a slightly rounded cutting edge with a cutting edge radius of about 0.25 mm;

Fig. 7

a chopping knife 2 consisting of two chopping knives 2A, 2B in perspective view (a), in plan view (b) and in front view (c);

Fig. 8

another from two knives 2A, 2B existing chopping knife 2 in plan view (a), in side view in gap-free assembly (b) or spaced Zusammenfügung (c) and in front view (d) without spacing and (e) at a distance;

Fig. 9

a section of a chopping device with standing and moving knives in the form of chopper packages in front view;

Fig. 10A / B

a double-edged chopper knife in U-shape in plan view of the cutting edges (Fig. 10A) and in perspective (Fig. 10B) and

Fig. 11A / B

two more chopping blades in plan view with undercut-like front edge

Detailed description of the embodiments

The chopping blades 1 and 2 shown in a perspective view in FIGS. 1 and 3 have a circular opening 3, which serves for the swinging attachment. If the knife is not pivotally mounted but fixedly secured, a further circular opening 4 (Figure 3) is provided.

The prior art knife 1 shown in FIG. 1 has two cutting edges 5 and 6 which extend over approximately three quarters of the total knife length. These cutting edges are formed by the oblique poles 7 and 8 or 9 and 10 (FIGS. 1 and 2).

The knife according to the invention shown in Fig. 3 has formed by cold or hot working inclined surfaces 11 and 12 or 13 and 14, which form the cutting edges 15 and 16 respectively. The inclined surfaces 11 and 12 or 13 and 14 extend over the entire blade length. The cutting edges 15 and 16 (FIG. 5 A) each have a rounding R. The knife cross-sections a to f shown in FIG. 4 also have curves at their cutting edges 17 to 28 which, because of their small size, can not be seen in FIGS. 4A to 4F.

A chopper knife with a stiffening longitudinal embossing is shown in Fig. 5 B can be seen. The prism-shaped blades are superimposed in the front area with ground saw teeth.

5C shows a chopper blade with carbide pieces 30 inserted. By way of example, a single carbide cutting edge 30A and a twin carbide cutting edge 30B, 30C are shown in the tip region. The latter can replace double-blade chopping knives as shown below in Fig. 7 or Fig. 8.

In the embodiment according to FIG. 7, the chopper blade 2 consists of two chopping knives 2A and 2B designed according to the invention, which are still shown at a distance from one another in the exploded view (a) and (c). The identical blades are z. B. joined together by riveting in tight support. The end area near the hole 3 for knife attachment is rounded semicircular. In contrast, the chopper blade of Fig. 8 is rounded lenticular in this area, wherein the embodiment of paragraph (c) or (e) via spacers 32 have an increased width.

Finally, FIG. 9 shows an arrangement of chopping knives 2 in a device in which a fixed counter knife 2 'engages in the spacing gap A of the moving chopping blades 2. The chopping knives 2 consist of packages of 3 chopping knives 2A, 2B, 2C, while the fixed counter knives consist of a package of two knives 2'A, 2'B. Each of these chopper and counter knife has a plurality of laterally spaced cutting, which are conducive to greater crushing or breaking of the shredded material and improved destruction of the surface structure of the shredded material.

The further chopper blade according to FIGS. 10A / B is a twin chopper knife, which is formed in one piece from a correspondingly long section by bending into a U-shape and is provided at its fastening end with mutually aligned fastening openings 3. Such a chopper blade is characterized by special torsional stiffness. As shown and insofar preferred, the U-shaped bridge region 2D between the two straight stretched chopper blade regions 2A and 2B is likewise provided with a cutting edge 15 ', 16' which supplement the longitudinal cutting edges 15 and 16. It can be seen that twin chopping knives connected with a bridging portion at their free ends, which are arranged parallel to one another at a lateral distance, can also be connected in the bridge region in a manner different from that shown in FIG. 10A, such as by a spacer which is adhesively bonded, Welding, or the like connected to the Häckselmesserenden can be. - Such twin chopping blades are without the features of claim 1 of independent inventive importance.

The exemplary embodiments according to FIGS. 11A / B show, on the one hand, that in order to avoid cutting waste, the blade end faces can be shaped complementarily (separation edges 34A and 34B). In this way, chaff knives can be obtained from a flat belt without waste. The material savings can be up to about 8%. Furthermore, it can be seen that the knife end faces can have free surfaces 33. That is to say that the free ends of the cutting edges 15 and 16 describe a knife circle X, while the other end face areas spring back. In the area of the inclined surfaces 11 to 14, the free surfaces 33 may be provided as a straight undercut whose angle to the cutting edge is less than 90 ° degrees. Such open spaces are known from Zerspanungswerkzeugen. In the middle blade area, the undercut may also be concave, as shown in FIG. 11A or stepped, as in FIG. 11B.

LIST OF REFERENCE NUMBERS

2

chopping blades

2A, 2B, 2C

chopping blades

2D

bridge area

2 '

against knife

2'A

against knife

2 B

against knife

3

Circular opening

11

sloping surface

12

sloping surface

13

sloping surface

14

sloping surface

15

cutting edge

15 '

cutting edge

16

cutting edge

16 '

cutting edge

17-28

cutting edges

30

Carbide cutting

30A

Carbide cutting

30B, 30C

Twin carbide cutting edge

32

spacers

33

front edge

34A

tear-off

34B

tear-off

R

curve

A

clearance gap

X

Cutting circle

Claims (30)

1. Method for producing knives made of steel for devices to cut straw and the like which are equipped with rotating drums on which the blades are arranged so as to be fixed or oscillate, characterised in that a flat steel in the form of a strip is reshaped by rolling at least one of its longitudinal edges to form a prismatic blade with a slightly rounded cutting edge with sufficient sharpness.
2. Method according to claim 1, characterised in that reshaping takes place by way of cold rolling.
3. Method according to claim 1 or 2, characterised in that reshaping takes place over the entire length of the flat steel.
4. Method according to any one of claims 1 to 3, characterised in that the longitudinal edges of the starting material, which is preferably rectangular in cross-section, are machined by way of metal removal before rolling.
5. Method according to any one of claims 1 to 4, characterised in that the required cross-sectional volume of the flat steel is adjusted by metal-removing machining of the longitudinal edges.
6. Method according to any one of claims 1 to 5, characterised in that the longitudinal edges of the starting material are smoothed by rolling edges.
7. Method according to any one of claims 1 to 6, characterised in that edge-machining rolls for width calibration are inserted between successive pairs of profiling rolls for rolling into prismatic blades.
8. Method according to any one of claims 1 to 7, characterised in that after the rolling process the cutting edges have a cutting edge radius of 0.3 mm at most.
9. Method according to any one of claims 1 to 8, characterised by a stamping step for cross-sectional profiling of the knife.
10. Method according to any one of claims 1 to 9, characterised in that after producing the prismatic cutting edges serrations are introduced into at least one partial length of the prismatic cutting edge, in particular by grinding.
11. Method according to any one of claims 1 to 10, characterised by a zone-hardening step along at least one partial length of the prismatic cutting edge region, in particular by inductive zone heating.
12. Method according to any one of claims 1 to 11, characterised in that a flat steel band is provided with the rolled cutting edges over a relatively long length and is subsequently divided by cross-cutting into sections that can be processed into chopping knives.
13. Method according to any one of claims 1 to 12, characterised in that at least one cutting or non-cutting hard metal piece for reducing wear is inserted into the prismatic blade.
14. Method according to any one of claims 1 to 13, characterised in that a plurality of knives are combined to give a correspondingly thicker knife package.
15. Knife made of steel for devices for cutting straw and the like which are equipped with rotating drums on which knives are arranged so as to be fixed or oscillate, comprising a portion of a flat steel with a fastening zone, such as a perforation, and a prismatic cutting edge provided at least on the longitudinal edge and optionally provided with serrations, characterised in that the at least one prismatic cutting edge comprises a rolled texture, extending over at least a partial length of the longitudinal edge, with prismatic arrangement of the rolled surface zone.
16. Knife according to claim 15, characterised in that the rolled texture extends over the entire length of the knife at the two longitudinal edges.
17. Knife according to claim 15 or 16, characterised in that the rolled texture is superimposed by tooth-like cutting edges in the region of the prismatic blades.
18. Knife according to any one of claims 15 to 17, characterised in that the longitudinal edges/rolled texture is superimposed by a hardening structure.
19. Knife according to any one of claims 15 to 18, characterised by a longitudinal profile, in particular a longitudinal stamping of the chopping knife.
20. Knife according to any one of claims 15 to 19, characterised by at least one hard metal insert in the cutting edge.
21. Knife according to any one of claims 15 to 20, characterised in that the knife is made of a plurality of knives that are combined to form a packet.
22. Knife according to any one of claims 15 to 21, characterised in that the knife end faces are provided with an undercut.
23. Knife according to claim 22, characterised in that the undercut has at least one flank (33).
24. Knife according to claim 22 or 23, characterised in that the undercut has a concave or stepped region.
25. Knife according to any one of claims 15 to 24, characterised in that the chopping knife end faces are shaped so as to be complementary.
26. Knife, in particular according to any one of claims 15 to 25,
    characterised by two chopping knives arranged at a lateral spacing from each other with a bridge region that connects the free chopping knife ends.
27. Knife according to claim 26, characterised in that the bridge region is U-shaped and connects the two chopping knives to each other in one piece.
28. Knife according to claim 26 or 27, characterised in that the bridge region is provided with at least one cutting edge.
29. Knife according to any one of claims 15 to 28, characterised in that it is a chopping knife.
30. Knife according to any one of claims 15 to 28, characterised in that it is a counter-knife.

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