JP2024007388A - Tilling tine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tilling tine even when a vertical blade adjacent to a horizontal blade comes into contact with soil and is worn due to a difference in form and shape of a rotary tine shaft to be attached to an agricultural machine, causing a blade edge spanning the horizontal blade and the vertical blade to wear while retaining a smooth curved shape, being hardly broken and having excellent durability.

SOLUTION: A tilling tine is configured by integrally connecting a vertical blade 1 that includes fixing means 11 fixed to a rotary tine shaft and extends in a flat plate shape, and a horizontal blade 2 that extends from the vertical blade 1 while curving, using a curving start part 6 as a boundary. The tilling tine includes a recessed part 3 continuously formed on one surfaces of the vertical blade 1 and the horizontal blade 2 along an extension direction of the horizontal blade 2 to a part of an area of the vertical blade 1, and a hardened layer 4 composed of a hard alloy and continuously layered up to a middle of the part of the area of the vertical blade 1 along the extension direction of the horizontal blade 2 so as to cover from the recessed part 3 to one edge L in a lateral direction of the vertical blade 1 and the horizontal blade 2.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to tillage claws for tilling soil.

Conventionally, the surfaces of tiller blades that come into contact with soil such as dirt and stones are prone to wear, so in order to improve wear resistance, a hard alloy that is harder than the blade tip is welded to the surface of the blade that comes into contact with the soil. There are some types that have a hardened layer.

For example, Patent Document 1 discloses a vertical blade portion that has a fixing means fixed to a rotary claw shaft and extends mainly in the vertical direction while remaining flat, and a vertical blade portion that extends from the vertical blade portion with a curve starting portion as a boundary while being curved. A tilling claw configured by integrally connecting a horizontal blade portion that extends mainly in the horizontal direction, and a recessed portion formed on one surface of the horizontal blade portion along the extending direction of the horizontal blade portion; A tilling claw is disclosed in which a hardened layer made of a hard alloy is layered along the extending direction of the horizontal blade so as to cover from the recess to the lower edge of the horizontal blade.

JP2006-345828A

However, in the tilling claw disclosed in Patent Document 1, the recessed part in which the hardened layer made of hard alloy is provided is provided only in the side blade part, so the rotary claw shaft for attachment to an agricultural machine cannot be used. If the styles and shapes of the blades are different, or the depth of plowing or the speed of the tractor is different, even if wear on the horizontal blades can be suppressed, the side of the vertical blades adjacent to the horizontal blades may be damaged. Due to further wear, a difference in wear occurs between the horizontal and vertical blades, and as shown in Figure 5, the blade edge spanning the horizontal and vertical blades transforms into a distorted curved shape. However, there was a problem in that the stress applied to the edge of the blade when it came into contact with the soil was locally concentrated, making it more likely to break. In addition, grass and straw become entangled with the blade edge, leading to vibrations, increased power requirements for the tractor, and deterioration of tillage conditions.

Therefore, in the present invention, the style and shape of the rotary claw shaft to be attached to the agricultural machine are different, the depth of plowing and the speed of the tractor are different, etc., so that the vertical blade part side adjacent to the horizontal blade part To provide a tilling claw that is hard to break and has excellent durability by wearing so that the blade edge extending over the horizontal blade part and the vertical blade part becomes a smooth curved shape even when the blade is worn due to contact with the soil. With the goal.

In order to solve the above problems, the present invention employs the following means [1] to [5].

[1] That is, the present invention provides a vertical blade portion (1) that has a fixing means (11) fixed to a rotary claw shaft and extends in a flat plate shape, and a curve starting portion from the vertical blade portion (1). A tilling claw is formed by integrally connecting a horizontal blade part (2) that extends while being curved with the border of the vertical blade part (1) and one of the horizontal blade parts (2). a recessed portion (3) formed continuously along the stretching direction of the horizontal blade portion (2) up to a part of the region of the vertical blade portion (1), and a recessed portion (3) formed on the surface of the horizontal blade portion (2); The vertical blade part ( a hardened layer (4) made of a hard alloy that is continuously layered to the middle of a part of the region 1), and the recess (3) is formed from the maximum recess depth (3M) to the This tilling claw is characterized by having a downwardly inclined surface (31) which is inclined so as to become shallower toward the edge (L) of the tiller.

[2] And the length (D) at the one edge from the curve start part (6) where the hardened layer (4) is layered to the vertical blade part (1) is 10 to 100 mm. , the radius of curvature (r) of the horizontal blade portion (2) is 30 to 200 mm.

[3] Then, at the side tip (22) that is the end in the stretching direction of the horizontal blade portion (2), the hardened layer (4) forms the curve starting portion (6) at the recessed portion (3). The tilling claw according to [1] or [2], characterized in that it has a thin portion (4α) that is thinner than the thickness of the tiller.

[4] In the above [1] or [2], wherein the surface of the hardened layer (4) is provided with a concave portion (41) along the concave portion (3). This is the tilling claw described.

[5] The surface of the hardened layer (4) is formed substantially parallel to one surface of the horizontal blade portion (2), as described in [1] or [2] above. It is the tilling claw of.

[6] And, on the other surface opposite to the one surface of the horizontal blade portion (2), an enlarged portion (23) is provided that bulges along the recessed portion (3). The tilling claw described in [1] or [2] above.

By having the tilling claw of the present invention configured as described above, the style and shape of the rotary claw shaft for attachment to the agricultural machine may be different, the depth of tilling and the speed of the tractor may be different, etc. Even if the vertical blade side adjacent to the horizontal blade part is also worn due to contact with the soil, the blade edge spanning the horizontal blade part and the vertical blade part will wear into a smooth curved shape and will not break. It is hard and has excellent durability. In addition, the tilling claw of the present invention wears the blade edge between the horizontal blade part and the vertical blade part into a smooth curved shape, which makes it difficult for grass and straw to get tangled, which reduces the deterioration of tillage performance. It is possible to suppress both vibration and vibration.

FIG. 1 is a plan view and a front view of a first embodiment of the tilling claw of the present invention. (a) It is an end view taken along the line AA of the tilling claw in FIG. 1. (b) In another embodiment, it is an end view corresponding to the AA line end view of the tilling claw in FIG. 1. (a) In another embodiment, it is an end view corresponding to the AA line end view of the tilling claw in FIG. 1. (b) In another embodiment, it is an end view corresponding to the AA line end view of the tilling claw in FIG. 1. (a) It is a front view of the first embodiment of the tilling claw of the present invention before use. (b) It is a front view of the first embodiment of the tilling claw of the present invention after use. (a) It is a front view of the tilling claw disclosed in Patent Document 1 before use. (b) It is a front view of the tilling claw disclosed in Patent Document 1 after use. It is a top view and a front view of modification 1 of the first embodiment of the tilling claw of the present invention. FIG. 7 is a plan view and a front view of a second embodiment of the tilling claw of the present invention. FIG. 8 is an end view taken along line BB of the tilling claw in FIG. 7; It is a top view and a front view of the third embodiment of the tilling claw of the present invention. 10 is an end view taken along line CC of the tilling claw in FIG. 9. FIG. It is a top view and a front view of the fourth embodiment of the tilling claw of the present invention. FIG. 12 is an end view taken along line DD of the tilling claw in FIG. 11. It is a top view and a front view of the fifth embodiment of the tilling claw of the present invention. (a) It is an end view taken along the line EE of the tilling claw in FIG. 13. (b) is an end view taken along line FF of the tilling claw in FIG. 13; It is a top view and a front view of the sixth embodiment of the tilling claw of the present invention. FIG. 16 is an end view taken along line GG of the tilling claw in FIG. 15; It is a top view and a front view of the seventh embodiment of the tilling claw of the present invention. (a) is an end view taken along line HH of the tilling claw in FIG. 17; (b) In another embodiment, it is an end view corresponding to the HH line end view of the tilling claw in FIG. 17. It is a top view and a front view of the eighth embodiment of the tilling claw of the present invention. 20 is an end view taken along line II of the tilling claw in FIG. 19. FIG. FIG. 2 is an end view corresponding to the AA line end view of the tilling claw in FIG. 1 in a second modified form of the first embodiment of the tilling claw of the present invention. FIG. 3 is an end view corresponding to the end view taken along line AA of the tilling claw in FIG. 1 in a third modification of the first embodiment of the tilling claw of the present invention. FIG. 3 is an end view corresponding to the AA line end view of the tilling claw in FIG. 1 in a fourth modified form of the first embodiment of the tilling claw of the present invention. FIG. 3 is an end view corresponding to the end view taken along line AA of the tilling claw in FIG. 1 in a further modification 5 of the first embodiment of the tilling claw of the present invention. FIG. 3 is an end view corresponding to the AA line end view of the tilling claw in FIG. 1 in a ninth embodiment of the tilling claw of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the embodiment regarding the tilling claw based on this invention will be described in detail based on an attached drawing. Note that the embodiments described below are specific examples preferable for carrying out the present invention, and therefore various technical limitations are made, but the present invention is not particularly limited in the following description. Unless otherwise specified, it is not limited to this form. Furthermore, in numerical ranges expressed using the symbol "~", the upper and lower numerical limits are included within the range.

In the drawings and the following description of each embodiment, the surface directly facing the rotation orbit of the rotating claw shaft, that is, the surface normal to the rotating claw axis of the rotating claw shaft, and the side blade portion 2 is on the left side when facing. The side on which it extends is the front surface, which is the surface that comes into contact with soil such as soil or stones. 1, FIG. 6, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 15, FIG. 17, and FIG. A front view of the configuration is shown. In these front views, the tips of the tilling claws are curved toward the front. The rotation direction of the rotary claw shaft in the first embodiment is counterclockwise around the rotation center O, and is also counterclockwise in the modified embodiments of the first embodiment and the second to eighth embodiments. .

(Overall configuration of tilling claw)
The tilling claw of the present invention basically has a fixing means 11 to the rotary claw shaft, a vertical blade part 1 extending from the fixing means 11 mainly in the horizontal direction when viewed from the front, and a curve starting part from the vertical blade part 1. A horizontal blade part 2 which is curved with 6 as a boundary and extends mainly diagonally upward in a front view is integrally connected to the horizontal blade part 2. The vertical blade part 1 consists of a flat plate, and the horizontal blade part 2 mainly consists of a curved plate.

Of both ends in the extending direction of the entire tilling claw, the vertical blade part 1, and the horizontal blade part 2, the end on the side of the fixing means to the rotary claw shaft is the proximal end, and the opposite end thereof is the distal end. In the entire tilling claw, the most proximal end is the proximal end 12 that faces one side when viewed from the front, and the most distal end is the side tip 22 that faces the other side when seen from the front.

At least one surface of the vertical blade part 1 and the horizontal blade part 2 is provided with a recessed part 3 that is continuously formed along the extending direction of the horizontal blade part 2 to a part of the area of the vertical blade part 1. do. Further, the area of the vertical blade part 1 is extended along the extending direction of the horizontal blade part 2 so as to cover the area from the recessed part 3 to the lower edge L which is one edge in the transverse direction of the vertical blade part 1 and the horizontal blade part 2. A hardened layer 4 made of a hard alloy is provided continuously up to the middle of a part of the hardened layer 4. Furthermore, a blade surface 5 that is inclined along the lower edge L of the horizontal blade portion 2 is formed on one surface of the horizontal blade portion 2 . Each configuration of each embodiment will be explained below.

Note that the present invention is applicable to any size and application as long as it is a tilling claw that is fixed to a rotary claw shaft and rotates at high speed, but it is particularly applicable to large tractors, and from the viewpoint of wear resistance and strength. Therefore, it is preferable to apply the present invention to tilling claws with a maximum rotation radius of 245 mm or more from the rotary claw shaft, and more preferably to tilling claws with a maximum rotation radius of about 250 to 290 mm.

[First embodiment]
(Front view blade edge shape)
The front view blade edge shape of the tilling claw of the first embodiment extends from the base end 12 of the vertical blade part 1 to one side, and extends to the side tip 22 of the horizontal blade part 2 to the other side (in FIG. It is formed while curving to the left (as viewed from the left side). Both side edges of the lower edge L, which is one edge in the short direction, and the upper edge U, which is the other edge, are made of continuous smooth curves that are not circular arcs as a whole and have continuously changed curvature. Note that this curve may be made up of a plurality of circular arc curves as long as the curve is continuous and smooth as a non-circular curve as a whole. In addition, in the front view of FIG. 1, the state before the horizontal blade part 2 is curved toward the front side in the paper is shown by the imaginary line.

(Vertical blade part 1)
The vertical blade part 1 is made of a flat plate within one reference plane, extends from the base end 12 mainly to the left, and refers to the area up to the curve starting part 6. In the front view of FIG. 1, a blade surface 5 is formed on the lower side of the side edges of the vertical blade part 1 and the horizontal blade part 2 on the back side, which is the back side of the page. As shown in FIG. 1, the vertical blade section 1 has a front view shape that extends mainly to the left from the base end 12 side, and also curves smoothly with a similar width in a region close to the curve start section 6.

The vertical blade portion 1 is fixed to the rotary claw shaft by a fixing means 11, which will be described below, and rotates at high speed counterclockwise with respect to the rotation center O. In the first embodiment, the modified form of the first embodiment, and the second embodiment, as described later, the recessed portion 3 and the hardened layer 4 are formed in an inwardly curved surface, so that the horizontal blade portion The hardened layer 4 will be located on the upper surface side of No. 2 driven into the soil.

(Fixing means 11)
A fixing means 11 to the rotary claw shaft is provided near the base end 12 in the extending direction of the vertical blade portion 1 . In the first embodiment, the fixing means 11 is a mounting hole that is fastened with a bolt in accordance with the fixing hole of the rotary claw shaft. In the first embodiment, two mounting holes are provided as the fixing means 11, but in other embodiments, there may be one or three or more mounting holes.

(Proximal end 12)
The base end 12 is one end on the base end side of the tilling claw facing rightward. In the first embodiment, the base end 12 is a flat surface.

(Horizontal blade part 2)
The horizontal blade part 2 refers to the entire area from the curve starting part 6 to the tip, and consists of a fully curved plate that is continuously fully curved in one direction (downward in the plan view of FIG. 1) in plan view. . Also, when viewed from the front, it has a planar curved shape that curves smoothly to one side (left side in FIG. 1) toward the tip. That is, it is continuous with the vertical blade part 1 with the curve starting part 6 as a boundary, and extends while mainly bending in the horizontal direction when viewed from the front. The lower side of the extending sides constitutes a lower edge L, and a blade surface 5 is formed along the lower edge L of the vertical blade part 1 from the horizontal blade part 2. The blade surface 5 extends from one lower side of the vertical blade part 1 to the side tip 22 of the horizontal blade part 2. Note that the lateral tips 22 are the tips of tilling claws that face laterally.

(curved)
The curved shape of the horizontal blade portion 2 is formed by combining one or more curve radii with the curve starting portion 6 as a boundary. In the first embodiment, it is formed curved with a predetermined radius of curvature r. In addition, in the horizontal blade part 2, the radius of curvature on the proximal end side and the radius of curvature on the distal end (side distal end 22) side are different in size and are adjacent to each other, so that both curves are smoothly connected in plan view. You can also. In other embodiments, the curved shape of the horizontal blade portion 2 can also be a shape in which one curved radius and a straight line are combined.

(Lower edge circumferential surface 21)
Furthermore, it is preferable that the horizontal blade part 2 has a lower edge circumferential surface 21 on the lower edge L thereof that extends along the entire length of the lower edge of the horizontal blade part 2. This lower edge circumferential surface 21 forms three sides without being sharp in cross-sectional view. This makes it possible to ensure the base material thickness of the cutting edge (thickness t of the lower edge of the horizontal cutting part 2), resulting in excellent toughness and preventing breakage due to use.

(cross-sectional shape in the width direction)
As shown in FIG. 2(a), the horizontal blade portion 2 has a thickness that gradually decreases from the upper edge U to the lower edge L due to the recessed portion 3 formed in the middle in a cross-sectional view in the width direction. After that, it gradually becomes thicker by the lower inclined surface 31 of the recessed part 3 through the center maximum recessed depth part 3M of the recessed part 3, and then gradually becomes thinner due to the inclination by the blade surface 5, and the lower edge has a lower edge thickness t. It reaches the peripheral surface 21.

Moreover, in FIG. 2(b) which is another embodiment, similarly to the first embodiment, the horizontal blade part 2 extends from the upper edge U to the lower edge L on the outside in the direction in which the horizontal blade part 2 bends. 3(a) and 3(b), which are flat except for the blade surface 5, but in a further embodiment shown in FIGS. It has a swollen ampulla 23. The enlarged portion 23 suppresses bending of the vertical blade portion 1 on the base end 12 side, and suppresses cracks occurring in the vertical direction between the lower edge L and the upper edge U in the hardened layer 4. The strength of the tilling claws can be improved, and the strength of the tilling claws can be improved while maintaining wear resistance on the side tip 22 side.

(Concave part 3)
The recessed part 3 is formed on one surface of the vertical blade part 1 and the horizontal blade part 2, and continues along the extending direction of the horizontal blade part 2 to a part of the area of the vertical blade part 1, and has a predetermined recess width of 3W. It is formed in a concave manner. Further, the tip of the recessed portion 3 in the extending direction reaches the side tip 22 of the horizontal blade portion 2, and the base end of the recessed portion 3 in the extending direction extends beyond the curve starting portion 6 to near the middle of the vertical blade portion 1. reach. In the first embodiment, the recess width 3W is constant over the extending direction of the vertical blade part 1 and the horizontal blade part 2, but in other embodiments, the recess width 3W is constant on the vertical blade part 1 side with the curve starting part 6 as a border. The recess width 3W can also be formed to be narrower or wider from the side of the horizontal blade portion 2.

Here, among the upper and lower ends of the recessed portion 3, the recessed lower end 3L is provided at a predetermined height from the lower edge L in the first embodiment, but in other embodiments, the recessed lower end 3L is provided in contact with the lower edge L. You can leave it there.

The recessed portion 3 and the hardened layer 4 described below can be formed on at least one of an internally curved surface and an externally curved surface, but in the first embodiment, they are formed on an internally curved surface. This provides the cured layer 4 with excellent fixing properties and strength (prevention of cracking).

(Lower inclined surface 31, upper inclined surface 32, bottom surface 34)
As shown in FIG. 2(a), the recess 3 is specifically configured to have at least a lower inclined surface 31 and an upper inclined surface 32, respectively, below and above the bottom surface 34, which is the maximum recess depth 3M. be done. The lower inclined surface 31 is a surface inclined at a predetermined inclination angle so as to become shallower downward from the bottom surface 34, which is the maximum depression depth 3M, in a cross-sectional view in the width direction. The upper inclined surface 32 is a surface inclined at a predetermined inclination angle so as to become shallower upward from the bottom surface 34, which is the maximum depression depth 3M, in a cross-sectional view in the width direction. Note that since the depth from the front surface of the horizontal blade portion 2 to the bottom surface 34 is constant, the maximum depth of the depression is 3M at any location on the bottom surface 34.

As shown in FIG. 2(a), the lower sloped surface 31 and the upper sloped surface 32 are such that the upper and lower edges of the recessed portion 3 in the cross-sectional view in the width direction gradually become shallower (i.e., the upper and lower edges become shallower at the maximum The respective inclination angles from the bottom surface 34, which is the deep part 3M of the depression, that is, the inclination angle θ between the bottom surface 34 and the upper inclined surface 32 and the inclination angle φ between the bottom surface 34 and the lower inclined surface 31 are smaller than 90°. ) is preferred. By covering the entire recessed portion 3 with the hardened layer 4, the hardened layer 4 is well fixed to the side blade portion 2. Further, by reducing the inclination angles θ and φ of the lower inclined surface 31 and the upper inclined surface 32, it is possible to suppress changes in strength due to progress of wear or the influence on wear resistance. In this embodiment, the lower inclined surface 31 and the upper inclined surface 32 are linear as shown in FIG. 2(a), but in other embodiments, they may be curved or a combination of a straight line and a curved line. .

In the first embodiment, as shown in FIG. 2(a), the lower inclined surface 31 is formed at an angle φ smaller than 90° with the bottom surface 34, and the tilling claws are formed through the lower end 3L of the recess. Although it is continuous with the flat surface toward the lower edge L, as shown in FIG. 21, in the second modification of the first embodiment, the lower inclined surface 31 is smaller than the inclination angle φ with the bottom surface 34. It is inclined at an angle, and the lower inclined surface 31 reaches the lower edge L. At this time, the lower inclined surface 31 is formed to reach the lower edge L over the vertical blade part 1 and the horizontal blade part 2 where the recessed part 3 is formed, and the recess width 3W of the recessed part 3 is the lower edge. The width is up to L. By forming the downward inclined surface 31 of the recessed portion 3 in this way, the hardened layer 4 on the lower edge L side can be made thicker than in the first embodiment shown in FIG. A tilling claw with excellent wear resistance can be obtained.

(Shallow recessed part 33)
The recessed portion 3 is a shallow recessed portion that gradually becomes shallower in the direction of the proximal end 12 of the vertical blade portion 1 in a part of the region of the vertical blade portion 1 beyond the curve starting portion 6 at the base end. 33. The shallow recess 33 is a part of the bottom surface 34. The proximal end side of the shallow recessed portion 33 of the first embodiment is flush with one surface of the vertical blade portion 1 and is assimilated therewith.

The shallow recessed portion 33 of the first embodiment shown in FIG. 1 has approximately the same width, and has a rectangular inclination that inclines at a predetermined minute inclination angle after passing the curve starting portion 6 toward the vertical blade portion 1 side when viewed from the front. It has a surface. As a result, the area beyond the curve starting part 6 toward the vertical blade part 1 side is also worn in the same way as the horizontal blade part 2, so the tilling claw has a smooth curved edge that spans the horizontal blade part and the vertical blade part. By maintaining this, it becomes resistant to wear and breakage, making it highly durable.

(thickness ratio)
At any position in the width direction near the lower edge L of the tilling claw or near the center of the recessed part 3, the thickness of the hardened layer 4 is always thinner than or approximately the same as that of the horizontal blade part 2. Specifically, at each width direction position near the lower edge L of the tilling claw and near the center of the recessed part 3, the ratio of the thickness of the hardened layer 4 to the horizontal blade part 2 is as follows: hardened layer 4: horizontal blade part 2=1 : Preferably 1 to 3. This makes it possible to always maintain a predetermined thickness of the hardened layer 4 (more specifically, the ratio of the predetermined thickness to the side blade portion 2, in other words, the ratio of the thickness to the total thickness). Uniform wear resistance can be obtained regardless of the degree of progression.

(Hardened layer 4)
The hardened layer 4 is a layer formed by hardening an alloy and has higher hardness than the side blade portion 2. Continuously extending from the side tip 22 side of the horizontal blade part 2 to the middle of a part of the region of the vertical blade part 1 beyond the curve starting part 6 along the extending direction of the horizontal blade part 2 where the recessed part 3 is formed. It is covered. In the first embodiment, the hardened layer 4 covers from the recess 3 to the lower edge L of the vertical blade part 1 and the horizontal blade part 2. That is, the lower edge of the hardened layer is at least common to the lower edge L. By forming the hardened layer 4 in this way, the area beyond the curve starting part 6 toward the vertical blade part 1 is also worn in the same way as the horizontal blade part 2, so that the tilling claws are The blade edge that spans the blade portion maintains a smooth curved shape as it wears, making it less likely to break and having excellent durability.

The upper edge 4U of the hardened layer is formed into a straight line, an arc, or a composite shape thereof when viewed from the front, and this shape extends in the direction of extension from the lower edge L on the vertical blade part 1 side to the lateral tip 22 of the horizontal blade part 2. It is inclined toward the upper edge U side which is above the surface (in FIG. 1, it is inclined upward to the left). That is, the width of the hardened layer 4 covers the entire width of the recessed part 3 near the side tip 22 of the horizontal blade part 2, and the width in the lateral direction becomes smaller toward the base end 12 of the vertical blade part 1. As a result, the tilling claws are similarly worn in the distance between the rotary claw axis and the blade edge, and in the middle of the area of the horizontal blade part 2 and vertical blade part 1 that are driven into the soil. The blade edge between the horizontal and vertical blades maintains a smooth curved shape as it wears, making it less likely to break and having excellent durability.

In the first embodiment, the hardened layer 4 covers part of the area of the horizontal blade part 2 and the vertical blade part 1 halfway, and the upper corner 33U of the shallow recessed part 33 of the recessed part 3 is exposed. In other embodiments, it may be completely covered in order to provide further durability.

The span length D at the lower edge L, which is one edge from the curve starting part 6 on which the hardened layer 4 is layered to the vertical blade part 1, is preferably 10 to 100 mm, and preferably 30 to 90 mm. More preferred. The radius of curvature r of the horizontal blade portion 2 is preferably 30 to 200 mm, more preferably 35 to 160 mm. Furthermore, it is preferable that when the radius of curvature r and the length D are relatively large, the other is small, or when one is small, the other is large. When the radius of curvature r and the length D are within the above range, the horizontal blade part 2 and the vertical blade part 1 are driven into the soil, and a part of the area of the horizontal blade part 2 and the vertical blade part 1 is driven into the soil. Since the tilling claw wears in the same way up to the middle of the blade, the blade edge between the horizontal and vertical blades wears while maintaining a smooth curved shape, making it difficult to break and has excellent durability. Become. Specifically, in the first embodiment, the radius of curvature r is 128 mm, and the length D is 64.6 mm.

The thickness of the hardened layer 4 at any stretching position (thickness of the hardened layer 4 that can be confirmed in the cross section in the width direction) gradually or suddenly changes from thick to thin from near the center of the recess 3 to near the lower edge L. Become something. Furthermore, the thickness of the hardened layer 4 near the center of the recessed part 3 is thicker than the thickness of the hardened layer 4 near the downward slope 31 of the recessed part 3, and is thicker than the thickness of the hardened layer 4 near the lower edge L. It is also preferable that it is thick.

The hard alloy constituting the hardened layer 4 is layered by heating and welding metal powder that is harder than the vertical blade portions 1 and the horizontal blade portions 2 using various methods. After the hardened layer 4 is formed, the hardened layer 4 is curved to have an internally curved surface, thereby making it possible to obtain a hardened layer 4 with good fixing properties and high density. Further, as a method other than welding, the hardened layer 4 may be provided by welding, thermal spraying, plasma, laser cladding, or the like.

In the first embodiment, as shown in FIG. It is formed approximately parallel to one side of the plane. Moreover, in FIG. 3(a) which is another embodiment, the surface of the hardened layer 4 is formed substantially parallel to one surface of the horizontal blade part 2, as in the first embodiment, but In the embodiment shown in FIGS. 2(b) and 3(b), a recess 41 is provided which is curved and recessed along a region corresponding to the central maximum depth 3M of the recess 3. The concave portion 41 reduces the contact resistance with tilled soil, thereby reducing the load on the tractor engine.

Further, in the first embodiment, the hardened layer 4 is provided so as to continuously cover from the side tip 22 of the horizontal blade part 2 to the middle of a part of the region of the vertical blade part 1 beyond the curve starting part 6. However, as shown in FIG. 6, in the first modification of the first embodiment, the thickness of the hardened layer 4 at the side tip 22 of the side blade part 2 is much larger than that at the curve starting part 6 in the recessed part 3. It has a thin part 4α provided thinly. At this time, the hardened layer 4 increases in thickness continuously or discontinuously from the end of the thin part 4α on the side tip 22 side, and extends beyond the curve starting part 6 to a part of the region of the vertical blade part 1. It is formed so as to cover part of the way continuously. By forming the hardened layer 4 with the thin part 4α at the side tip 22 in this way, when the tilling claw is attached to an agricultural machine and used, the hardened layer at the side tip 22 of the side blade portion 2 will be damaged due to wear. Since the thin part 4α of the hardened layer 4 is also worn out, when the thin part 4α of the hardened layer 4 disappears due to wear, it functions as an indicator of when to replace the tiller claw.

In the first embodiment, the hardened layer 4 made of one type of alloy is provided over a part of the vertical blade part 1 and the inner curved surface of the horizontal blade part 2, and the upper edge of the recessed part 3. Although provided so as to cover the U side and the lower edge L side, as shown in FIG. 4a, and a second hardened layer 4b which is provided so as to cover the surface of the first hardened layer 4a and the upper edge U side and the lower edge L side of the recessed part 3 and has a hardness different from that of the first hardened layer 4a. It is formed by laminating alloys of. Note that it goes without saying that the first hardened layer 4a and the second hardened layer 4b have higher hardness than the side blade portion 2. By laminating the first hardened layer 4a and the second hardened layer 4b in the hardened layer 4, the strength of the hardened layer 4 can be maintained and wear resistance can be improved. Specifically, for example, it is preferable that the hardness of the hardened layer 4a is higher than the hardness of the hardened layer 4b, and in this case, the hardened layer 4a with high hardness is formed in the recessed part 3, and generally If an alloy with high hardness is used to improve wear resistance, it tends to become brittle, but the second hardened layer 4b maintains its strength by suppressing cracking or chipping due to impact from stones, etc. during tilling. At the same time, since the first hardened layer 4a covered with the second hardened layer 4b makes it difficult to wear, the wear resistance of the tilling claw as a whole can be improved.

Furthermore, in the first embodiment, the hardened layer 4 is provided on a part of the vertical blade part 1 and on the inner curved surface of the horizontal blade part 2, but as shown in FIG. In this case, there are two hardened layers 4, a first hardened layer 4a and a second hardened layer 4b. Specifically, as in the first embodiment, the first hardened layer 4a includes a recess 3 provided over a part of the vertical blade part 1 and the inner curved surface of the horizontal blade part 2, and an upper edge U of the recess 3. Unlike the first embodiment, the second hardened layer 4b covers a part of the vertical blade part 1 and the external curved surface of the horizontal blade part 2, and covers the lower edge of the external curved surface. It is formed on the blade surface 5 provided on the L side and the outer curved surface side. Note that it goes without saying that the first hardened layer 4a and the second hardened layer 4b have higher hardness than the side blade portion 2. Moreover, the first hardened layer 4a and the second hardened layer 4b may be made of the same hard alloy, or may be made of different hard alloys having different hardnesses. Depending on the combination of field and work conditions and the shape of the tilling claws, wear may progress from the internally curved surface or from the externally curved surface. By providing the first hardened layer 4a on the internally curved surface of the horizontal blade part 2 and the second hardened layer 4b on the externally curved surface of a part of the vertical blade part 1 and the horizontal blade part 2, it can be resistant to various cases. Can exhibit abrasion resistance.

Further, in the first embodiment, the hardened layer 4 is provided on a part of the vertical blade part 1 and on the inner curved surface of the horizontal blade part 2, but as shown in FIG. In this case, there are two hardened layers 4, a first hardened layer 4a and a second hardened layer 4b. Specifically, as in the first embodiment, the first hardened layer 4a includes a recess 3 provided over a part of the vertical blade part 1 and the inner curved surface of the horizontal blade part 2, and an upper edge U of the recess 3. Unlike the first embodiment, the second hardened layer 4b is provided on the outer curved surface side over a part of the vertical blade portion 1 and the outer curved surface of the horizontal blade portion 2. It is formed on the curved blade surface 5. Note that it goes without saying that the first hardened layer 4a and the second hardened layer 4b have higher hardness than the side blade portion 2. Moreover, the first hardened layer 4a and the second hardened layer 4b may be made of the same hard alloy, or may be made of different hard alloys having different hardnesses. Depending on the combination of field and work conditions and the shape of the tilling claws, wear may progress from the internally curved surface or from the externally curved surface. By providing the first hardened layer 4a on the internally curved surface of the horizontal blade part 2 and the second hardened layer 4b on the externally curved surface of a part of the vertical blade part 1 and the horizontal blade part 2, it can be resistant to various cases. Can exhibit abrasion resistance. Note that, compared to the fourth modification of the first embodiment described above, the second hardened layer 4b is provided only on the blade surface 5 provided on the externally curved surface side, while exhibiting wear resistance from the initial stage of wear. Because there is no need to worry about costs, it is possible to reduce costs.

(Blade surface 5)
The blade surface 5 is an inclined surface provided along the lower edge L of the vertical blade part 1 and the horizontal blade part 2 so as to make the lower edge L thinner. At least a part of the region of the vertical blade portion 1 and the entire horizontal blade portion 2 are formed with a substantially constant width. Although it may be formed on an internally curved surface, an externally curved surface, or both of these surfaces, it is preferable to form it on one surface opposite to the surface on which the recessed portion 3 and the hardened layer 4 are formed. In the first embodiment, it is formed on an externally curved surface that is opposite to the surface on which the recessed portion 3 and the hardened layer 4 are formed. Further, for strength and workability, it is desirable to form a straight line when viewed in cross section in the width direction.

(About progress of wear)
The tilling claws wear out due to repeated contact with the soil during tilling work, but this wear does not wear uniformly across the vertical blade part 1 and the horizontal blade part 2, but between the vertical blade part 1 and the horizontal blade part 2. The curved portion of the blade portion 2 wears unevenly, and the wear progresses from this side curved portion. Specifically, as shown in FIG. 5, the tilling claw disclosed in Patent Document 1 is shown before and after use. In FIG. 5(a), since the blade is in a state before use, the blade edge extending between the horizontal blade portion and the vertical blade portion has a smooth curved shape. However, Fig. 5(b) shows the state after use, and since the blade edge spanning the horizontal and vertical blades has a distorted curved shape, stress concentration occurs during use at the point where the degree of wear changes rapidly. The lifespan was shorter than originally expected, and the durability was poor, as there were cases where the tilling claws broke.

On the other hand, in the present embodiment, on one surface of the vertical blade part 1 and the horizontal blade part 2, a continuous blade is formed along the extending direction of the horizontal blade part 2 up to a part of the area of the vertical blade part 1. A vertical blade part is formed along the extending direction of the horizontal blade part 2 so as to cover the recessed part 3 and the lower edge L which is one edge in the transverse direction of the vertical blade part 1 and the horizontal blade part 2 from the recessed part 3. A hardened layer 4 made of a hard alloy is provided, which is continuously layered up to the middle of a part of the region 1. By providing such a hardened layer 4, as shown in FIG. 4, the state before use as shown in FIG. In comparison with the worn state after use in 4(b), the vertical blade part 1 and the horizontal blade part 2 are worn while maintaining a smooth curved shape at the lower edge L, and stress concentration does not occur during use. Moreover, it is hard to break and has excellent durability. In addition, by wearing the blade edge between the horizontal and vertical blades into a smooth curved shape, it becomes difficult for grass and straw to get tangled, which prevents deterioration in tillage performance and also suppresses vibration. be able to.

[Second embodiment]
The second embodiment is roughly the same as the first embodiment, but differs in the shape of the base end 12 of the vertical blade part 1 and the lateral tip 22 of the horizontal blade part 2. That is, as shown in FIG. 7, the base end 12 faces upward, and is fitted into the fixing protrusion of the rotating shaft pawl to fix one mounting hole, which is the fixing means 11, with a bolt. In this embodiment, the side tip 22 has a substantially right-angled protrusion on the upper edge U side, but in other embodiments, it may have an acutely pointed protrusion or a protrusion with a curved tip. good. In addition, in the second embodiment, similarly to the first embodiment, the recessed part 3 continues beyond the curve start part 6 to a part of the area of the vertical blade part 1 along the extending direction of the horizontal blade part 2. The hardened layer 4 is made of a hard alloy and covers from the recessed part 3 to the lower edge L which is one edge in the transverse direction of the vertical blade part 1 and the horizontal blade part 2. It is continuously layered along the extending direction of the horizontal blade part 2 up to the middle of a part of the region of the vertical blade part 1 . Furthermore, most of the shallow recessed portion 33 of the second embodiment is exposed without being covered with the hardened layer 4.

[Third embodiment]
The third embodiment is roughly the same as the first embodiment, but differs in the configuration in which a plurality of recesses 3 are formed substantially in parallel. That is, as shown in FIGS. 9 and 10, the recessed part 3 consists of two substantially parallel first recessed parts 3A and second recessed parts 3B, and the first recessed parts 3A and the second recessed parts 3B are A recess is formed on one surface of the vertical blade part 1 and the horizontal blade part 2 so as to continue to a part of the area of the vertical blade part 1 along the extending direction of the horizontal blade part 2 and have a predetermined recess width of 3W. has been done. As a result, the thickness of the hardened layer 4, which is harder and more brittle than the material of the horizontal blade part 2 and the vertical blade part 1, is made more variable, and the area where the hardened layer 4 contacts the horizontal blade part 2 and the vertical blade part 1 is increased. By increasing the number, the hardened layer 4 becomes difficult to peel off from the horizontal blade portion 2 and the vertical blade portion 1. For this reason, when the tilling claw collides with a stone or the like during tilling, the hardened layer 4 is less likely to chip, and even if it does chip, it will be a small piece rather than a large piece, so the life of the tilling claw can be extended. It is possible to suppress the lower edge L of the tilling claw from becoming jagged. Note that in this embodiment, the recess 3 is formed from two recesses, but in other embodiments, it may be formed from a plurality of recesses, such as three or four recesses. The widths and depths of the plurality of depressions may be the same or different, and the height of the mountain formed between the plurality of parallel depressions is determined by the height of the front surface of the horizontal blade portion 2. The depth from the bottom surface 34 to the bottom surface 34 may be the same or different.

[Fourth embodiment]
The fourth embodiment is roughly the same as the first embodiment, but differs in that the thickness t1 of the horizontal blade part 2 in the recessed part 3 on the tip side of the horizontal blade part 2 is equal to or less than the thickness t2 of the hardened layer 4. do. That is, as shown in FIGS. 11 and 12, on the tip side of the tilling claw, the thickness t1 of the side blade portion 2 at the recess 3, more specifically, the maximum recess depth 3M, is the same as the thickness t2 of the hardened layer 4. or less. Furthermore, in the recessed part 3 of the tilling claw, the ratio between the thickness t1 of the horizontal blade part 2 and the thickness t2 of the hardened layer 4 at the maximum recess depth 3M is: thickness t1 of the horizontal blade part 2:thickness t2 of the hardened layer 4:= The ratio is preferably 1:1 to 2. Depending on conditions such as the rotation of the rotating claw shaft and the speed of the tractor during tilling, only the tip side of the tilling claws may wear out quickly, and a gap may form between the opposing tilling claws attached to the rotating claw shaft. However, by making the thickness t1 of the horizontal blade part 2 in the recessed part 3 equal to or less than the thickness t2 of the hardened layer 4, it is possible to reduce tillage performance, especially on the tip side of the tilling claw. By balancing wear and improving wear resistance, it is possible to suppress deterioration in tillage performance.

[Fifth embodiment]
In the fifth embodiment, which is approximately the same as the first embodiment, in the horizontal blade portion 2, the thickness tA between the surface contacting the soil on the tip side and the maximum depression depth 3M, which is the bottom surface 34, is larger than the curve starting portion. 6, the thickness TA of the horizontal blade part 2 at the tip side is smaller than the thickness TB of the horizontal blade part 2 at the curve starting part 6, and the thickness TA of the horizontal blade part 2 at the tip side is smaller than the thickness tB between the surface that contacts the soil at The ratio of the thickness tA between the surface that contacts the soil on the tip side and the maximum depression depth 3M to the thickness TA of the horizontal blade part 2, and the ratio of the soil at the curve start part 6 to the thickness TB of the horizontal blade part 2 at the curve start part 6. The difference is that the ratio of the thickness tB between the abutting surface and the maximum recess depth 3M is substantially the same. That is, as shown in FIGS. 13 and 14, first, in the horizontal blade portion 2, the thickness tA between the front surface, which is the surface that contacts the soil on the tip side, and the maximum depression depth 3M is the same as the soil at the curve starting portion 6. It is smaller than the thickness tB between the front surface which is the abutting surface and the maximum recess depth 3M. The thickness TA of the horizontal blade portion 2 at the tip end side is smaller than the thickness TB of the horizontal blade portion 2 at the curve starting portion 6. Furthermore, the ratio of the thickness tA between the front surface which is the surface that contacts the soil on the tip side and the maximum depression depth 3M to the thickness TA of the horizontal blade part 2 on the tip side, and the thickness TB of the horizontal blade part 2 at the curve starting part 6. The ratio of the thickness tB between the front surface, which is the surface in contact with the soil at the curve starting portion 6, and the maximum depression depth 3M is approximately the same. It is preferable that the ratios be the same, but when one ratio is 1, the other ratio may be within the range of 0.9 to 1.1. In other words, the feature of this embodiment is that in the side blade part 2, the recessed part 3 gradually becomes shallower from the curve starting part 6 toward the tip side while maintaining almost the thickness ratio with the side blade part 2. There is. This improves the wear resistance in the vicinity of the curve starting part 6, and prevents the blade edge between the horizontal blade part and the vertical blade part from forming a distorted curved shape after use, as shown in FIG. 5(b). This allows stress concentration to occur during use, making it less likely to break and improving durability.

[Sixth embodiment]
The sixth embodiment is roughly the same as the first embodiment, but differs in the configuration in which the recesses 3 are formed in multiple stages. That is, as shown in FIGS. 15 and 16, in the recessed portion 3, the upper edge U side is depressed one step through the first upper inclined surface 32 to reach the first bottom surface 34, and then the other upper inclined surface 32' It is further depressed one step further to reach another bottom surface 34' which is the maximum depth 3M of the depression, thereby forming a two-step depression. As a result, the thickness of the hardened layer 4, which is harder and more brittle than the material of the horizontal blade part 2 and the vertical blade part 1, is made more variable, and the area where the hardened layer 4 contacts the horizontal blade part 2 and the vertical blade part 1 is increased. By increasing the number, the hardened layer 4 becomes difficult to peel off from the horizontal blade portion 2 and the vertical blade portion 1. In addition, by forming the recessed portion 3 in two stages on the upper edge U side, the base material (in this example, a material with high springiness) that constitutes the horizontal blade portion 2 and the vertical blade portion 1 is The SUP6) can be left thick, resulting in improved strength of the tilling claws and prevention of breakage. In this embodiment, the recessed portion 3 is formed in two stages only on the upper edge U side, but in other embodiments, it can be formed in two stages also on the lower edge L side, and , a plurality of stages, such as three or four stages, may be formed on at least one of the upper edge U side or the lower edge L side.

[Seventh embodiment]
The seventh embodiment is approximately the same as the first embodiment, but differs in that the recessed portion 3 is inclined to become deeper or shallower toward the lower edge L side on the bottom surface 34 thereof. That is, as shown in FIGS. 17 and 18(a), similarly to the first embodiment, the recessed portion 3 has a lower inclined surface 31 and an upper inclined surface 32, respectively, below and above the bottom surface 34. However, the bottom surface 34 is inclined at a predetermined angle so as to become deeper toward the lower edge L side in a cross-sectional view in the width direction, and reaches the maximum recess depth 3M. The lower inclined surface 31 is positioned so as to become shallower from the maximum depth 3M toward the lower edge L. Further, as still another embodiment, as shown in FIG. 18(b), the recessed portion 3 has a lower inclined surface 31 and an upper inclined surface 32, respectively, downward and upward from the bottom surface 34, as in the first embodiment. However, in the cross-sectional view in the width direction, the upper inclined surface 32 slopes and reaches the maximum depth 3M of the depression, and the bottom surface 34 becomes shallower from the maximum depth 3M toward the lower edge L side. The lower inclined surface 31 is located so as to be inclined at a predetermined angle so that it becomes shallower toward the lower edge L. Depending on conditions such as the rotation of the rotary claw shaft and the speed of the tractor during tilling, the width of the tilling claws may become narrower and wear may progress such that the thickness of the horizontal blade portion 2 becomes thinner. On the side, the horizontal blade part 2 disappears due to wear and the hardened layer 4 is partially exposed, and the exposed hardened layer 4 is likely to chip when it collides with stones etc. contained in the soil. The thickness of the hardened layer 4 increases by sloping the bottom surface 34 to become deeper toward the lower edge L side, or by sloping the bottom surface 34 of the recessed portion 3 to become shallower toward the lower edge L side. This increases the thickness of the side blade portion 2 and balances the thicknesses of the side blade portion 2 and the hardened layer 4, making it possible to prevent premature wear and irregular wear due to chipping of the hardened layer 4.

[Eighth embodiment]
The eighth embodiment is approximately the same as the first embodiment, but is different in that the outer shape of the horizontal blade portion 2 is different from the first embodiment. That is, as shown in FIGS. 19 and 20, the lateral tip 22 of the horizontal blade part 2 is linear, and furthermore, it is continuous with the vertical blade part 1 with the curve starting part 6 as a boundary, and is mainly curved when viewed from the front. When extending while bending in the lateral direction, the degree of bending toward the upper edge U side is smaller than in the first embodiment. Further, in this embodiment, the shape of the side tip 22 of the side blade portion 2 is a straight line, but in other embodiments, it may have a protrusion shape or a curved shape that is pointed at an acute or obtuse angle. This embodiment also has the same effects as the first embodiment.

[Ninth embodiment]
In the ninth embodiment, the basic configuration of the vertical blade part 1 and the horizontal blade part 2 is the same as that of the first embodiment, but the recessed part 3 and the hardened layer 4 are different. That is, as shown in FIG. 25, first, the recessed part 3 is formed in a part of the area of the vertical blade part 1 along the extending direction of the horizontal blade part 2 on the outer curved surface of the vertical blade part 1 and the horizontal blade part 2. It is formed so as to be continuously recessed with a predetermined recess width 3W. There are two hardened layers 4, a first hardened layer 4a and a second hardened layer 4b. Specifically, a part of the vertical blade part 1 and the horizontal blade part 4a are embedded in a part of the vertical blade part 1 and a recessed part 3 provided over the outer curved surface of the horizontal blade part 2. The second hardened layer 4b is provided on a part of the vertical blade part 1 and the internal curved surface of the horizontal blade part 2 from the upper edge U side to the lower edge L. There is. In addition, it goes without saying that the first hardened layer 4a and the second hardened layer 4b have higher hardness than the side blade portion 2. Moreover, the first hardened layer 4a and the second hardened layer 4b may be made of the same hard alloy, or may be made of different hard alloys having different hardnesses. Depending on the combination of field and work conditions and the shape of the tilling claws, wear may progress from the internally curved surface or from the externally curved surface. By providing the first hardened layer 4a on the externally curved surface of the horizontal blade part 2 and the second hardened layer 4b on the internally curved surface of a part of the vertical blade part 1 and the horizontal blade part 2, it can be resistant to various cases. Can exhibit abrasion resistance. Note that, compared to the fourth modification of the first embodiment described above, the thickness of the tilling claws is made thinner so that the first hardened layer 4a does not bulge out from the outer curved surface of a part of the vertical blade part 1 and the horizontal blade part 2. Therefore, although the resistance during tilling is similar to that of the first embodiment, it is possible to exhibit wear resistance.

1... Vertical blade part 11... Fixing means 12... Base end 2... Horizontal blade part 21... Lower edge circumferential surface 22... Side tip 23... Ampulla 3... - Recessed portion 31...Lower inclined surface 32...Upper inclined surface 33...Shallow recessed portion 34...Bottom surface 33U...Upper corner 3M...Maximum recess depth 3W...Recess width 3L ... Lower end of depression 4 ... Hardened layer 41 ... Recessed part 4U ... Upper edge of hardened layer 4α ... Thin part 4a ... First hardened layer 4b ... Second hardened layer 5 ... Blade surface 6...Curved start part L...Lower edge (first edge)
U...upper edge (other edge)
O...Center of rotation t...Thickness of the lower edge of the horizontal blade part 2

Claims (6)

A vertical blade part (1) having a fixing means (11) fixed to a rotary claw shaft and extending in a flat plate shape; A tilling claw configured by integrally connecting an extending horizontal blade part (2),
On one surface of the vertical blade part (1) and the horizontal blade part (2), a continuous blade is provided along the extending direction of the horizontal blade part (2) up to a part of the area of the vertical blade part (1). A recessed portion (3) formed;
In the extending direction of the horizontal blade part (2) so as to cover from the recessed part (3) to one edge (L) in the short direction of the vertical blade part (1) and the horizontal blade part (2). a hardened layer (4) made of a hard alloy that is continuously layered along the vertical blade part (1) halfway up a part of the region;
A tilling claw characterized in that the recess (3) has a downwardly inclined surface (31) that is inclined to become shallower from the maximum recess depth (3M) toward the first edge (L). The length (D) at the one edge from the curved start part (6) where the hardened layer (4) is layered to the vertical blade part (1) is 10 to 100 mm, and the horizontal blade part The tilling claw according to claim 1, wherein the radius of curvature (r) of (2) is 30 to 200 mm. At the side tip (22) which is the end in the stretching direction of the horizontal blade part (2), the hardened layer (4) is provided to be thinner than the thickness at the curve start part (6) at the recessed part (3). The tilling claw according to claim 1 or 2, characterized in that the tiller has a thin portion (4α). The tilling claw according to claim 1 or 2, characterized in that the surface of the hardened layer (4) includes a recessed portion (41) along the recessed portion (3). The tilling claw according to claim 1 or 2, characterized in that the surface of the hardened layer (4) is formed substantially parallel to one surface of the horizontal blade portion (2). Claim 1 or claim 1, characterized in that the other surface of the horizontal blade portion (2) opposite to the one surface is provided with an enlarged portion (23) that bulges along the recessed portion (3). The tilling claw according to item 2.