CA2027803A1 - Rotor cutter - Google Patents
Rotor cutterInfo
- Publication number
- CA2027803A1 CA2027803A1 CA 2027803 CA2027803A CA2027803A1 CA 2027803 A1 CA2027803 A1 CA 2027803A1 CA 2027803 CA2027803 CA 2027803 CA 2027803 A CA2027803 A CA 2027803A CA 2027803 A1 CA2027803 A1 CA 2027803A1
- Authority
- CA
- Canada
- Prior art keywords
- axis
- rotation
- cutting member
- knife
- shank
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Landscapes
- Harvester Elements (AREA)
Abstract
Abstract A rotor cutter comprises a cutting member (1) adapted to be driven into rotation about an axis of rotation (3). The cutting member comprises a knife holder (6) connected with a knife (12). The knife (12) comprises a blade, which during the rota-tion of the cutting member (1) rotates in a plane substantially perpendicular to the axis of rotation (3) of the cutting member (1). The knife (12) com-prises furthermore a shank (13) rotatably jour-nalled relative to the knife holder (6) about a swivel axis (11), said swivel axis forming an acute angle (.alpha.) with the axis of rotation (3) of the cutting member (1), the angle space of said angle facing upwards.
Description
A rotor cutter The invention relates to a rotor cutter comprising a cutting member adapted to be driven into rotation about an axis of rotation, where said cutting me~ber 5 comprises a knife holder connected with a knife having a shank extending downwards from said knife holder, and where the shank at its upper end is rotatably journalled about a swivel axi.s relative to the knife holder, said swivel axis forming an 10 acute angle with upward angle spaces with the axis of rotation of the cutting member, and where the knife is provided with a blade at the lower end of the shank, the rotation of the cutting member causing said blade to rotate in a plane substan-15 tially perpendicular to the axis of rotation ofsaid cutting member.
The expression "rotor cutter" includes all cutters comprising a rotating cutting member, such as rotary lawn movers, reapers,~topping machines etc.
, :::
20 GB-PS ~o. 1.220,353 discloses a rotor cutter of the above type, which comprises a cutting member arranged on a vertical rotary shaft. The cutting member comprises a knife holder mounted at the lower end of the shaft, a plurality of knives with a 25 shank extendi~ng downwards and outwards from said knife holder, and a blade formed integral with said shank and adapted to rotate in a plane perpen-dicular to the longitudinal axis of the rotary shaft. At the upper end the shank of the knife is 30 pivotally connected to the knife holder by means of a pin. The longitudinal axis of the pin forms an acute angle with the rotary shaft. By such a rotor cutter, the shank of the knife is subjected to a large moment especially at its upper end d~e to the centrifugal force caused by the rotation of 5 the cutting member. The shank of the knife must therefore be relatively thick in order to resist the above moment. On the other hand, the knife blade must be relatively thin in order to provide the best possible cutting result. An unfortunate 10 result of the above contradicting conditions is that such a knife is relatively expensive to manufacture.
The integral forming of the shank and the blade of the knife is furthermore encumbered with the draw-back that the entire knife must be replaced when the -15 blade is damaged, which in turn results in high operating expenses. The achievable cutting result suffers furthermore from the drawback that the entire knife swivels upwards and backwards when nothing but the blade hits an obstacle.
:
20 DE-PS No. 29 20 244 dlscloses a rotor cutter where the knife holder of the cutting member is a disk.
On the bottom side of the disk, knives are rotatably arranged about an axis parallel to the axis of rotation of the cutting member, said knives project-25 ing radially outwards from the disk when the cuttingmember is rotating. As a result the knives turn and clear possible obstacles such as a small stone or a stump. Experience has, however, shown that ~this type of cutting members involves a high risk ;30 of said cuttlng member and the driving mechanism causing said member to rotate being seriously damaged when the cutting member hits a large object such as a large stone or a large stump.
The object of the invention is to provide a rotor cutter of the above type, which at low operating costs reduces the risk of damages of the cutting member and the driving mechanism when the knife hits S obstacles while achieving an excellent cutting result.
The rotor cutter according to the invention is characterissd in that the blade is rotatably jour-nalled about an axis of rotation relative to the 10 shank. When the shank of the knife hits an obstacle, the entire knife swivels backwards and upwards about the swivel axis so as to clear said obstacle.
However, when the blade hits an obstacle, only the blade and not the entire knife is turned, which 15 presents an advantage for the achievement of a very uniform cutting result ~ecause then the blade returns faster to its cutting position than when the entire knife is turned. As the blade of the knife can be turned relative to the shank of the 20 knife, the moment arm is reduced such that the total risk of damage to the cutting member and its driving mechanism is simultaneously reduced when the knife hits an obstacle, said moment arm trans-i`erring the moment to the shank of the kniEe when 25 said knife hits an obstacle. Finally, the costs involved in replacing damaged blades are very low ; because the form of the blades is very simple with the result that the manufacture of said blades is very inexpensive.
30 According to the invention the axis of rotation may be substantially parallel to the axis oE rota-tion of the cutting member. As a result, the bladeof the knife remains in its cutting plane when it hits an obstacle, which presents an advantage for the achievement of an optimal cutting result. Thus 5 such an embodiment of the invention turned out in practice to render it possible to achieve a cutting result of the same quality as is obtained by means of lawn movers having cutting cylinders.
Moreover, the blade may according to the invention 10 be replaceably connected to the shank. Such an embodiment of the invention is considered particu-larly advantageous for achieving low operating costs.
Furthermore the angle formed by the swivel axis of 15 the knife and the axis of rotation of the cutting member may be in the range 30 to 60, and prefer-ably in the range 40 to 50, said ranges having proved to be particularly advantageous in practice.
Finally according to the invention the rotatable ~;~ 20 journalling of the kniie relative to the kniie holder may be situated a short distance from the axis of rotation of the cutting member said rotat-able journalling forming the swive~ axis . As a resuIt the knife holder can advantageously be shaped 25 such that transverse to the axis of rotation of the cutting member said holder is of a small dimen-sion which minimizes the ris~ of exactly this portion of the cutting member hitting an obstacle in the ground and of the cutting member andJor its 30 driving mechanism being damaged.
The invention is explained in greater detail below with reference to the accompanying drawing, in which the Figure is an axial, sectional view through an embodiment of a cutting member for a rotor cutter 5 accordlng to the invention.
The cutting member 1 of the Figure is fixedly con-nected to a substantially vertical shaft 2 adapted to cause the cutting member to rotate about a vertical axis of rotation 3 by means of a driving 10 mechanism not shown. The cutting member 1 comprises a hub 4 $ixedly connected to the shaft 2. A knife holder 6 is bolted onto the hub 4 by means of screws 5, said knife holder 6 comprising a disk 7. Two diametrically opposing notches 8 are shaped at the 15 periphery of the disk 7, only one notch appearing from the drawing. A bushing 9 is situated in each notch and is welded at 10 to the disk 7 in such a manner that the axis 11 of the bushing forms an angle ~ of about 45 with the axis of rotation 3 20 of the cutting member. The angle can, however, be arbitrarily chosen in the range of 0 to 90. The axis 11 of the bushing 9 is a swivel axis for a knife 12 comprising a shank 13 and a blade 14. The shank 13 is shaped like a two-legged fork and is 25 formed by two flat bars welded together at one end at 17 and forming the legs 15, 16 of the fork at the ;~ opposite end. The distance between the legs of the fork corresponds substantially to the length of the bushing 9. Each leg is at its free end provided 30 with an opening 18, 19, and a bolt 20 extends through each of these openings 18, 19 and through the bushing 9. A nut 21 is screwed onto the end of ~he bolt 20. Accordingly the bolt 20 forms the swivel axis 11 for the knife 12.
The opposite end of the fork-shaped shank 13 is provided with an opening 22 allowing passage of a bolt 23. The bolt 23 is secured by means of a nut 5 24 and comprises a shank portion 25 of a larger diameter than the opening 22. The blade 14 is situated on the shank portion 25 and comprises at one end an opening 26 of an inner diameter slightly larger than the outer diameter of the shank portion.
10 As a result the blade 14 is rotatably arranged about an axis of rotation 27 formed by the axis of the bolt 23 and being substantially parallel to the axis of rotation 3 of the cutting member 1.
When the cutting member 1 is rotating, the blade 15 14 sweeps a plane substantially perpendicular to the axis of rotation 3, and the shank 13 and the blade 14 of the knife 12 are in the position shown in the Figure where they project radially outwards from the axis of rotation 3 of said cutting member 20 1. When only the blade 14 hits an obstacle, said blade swivels backwards and clears said obstacle.
When also the shank 13 hits the obstacle, saia shank 13 and consequently also the blade 14 swivels backwards and upwards about the swivel axis 11 and 25 cIears the obstacle.
The invention may be modified in many ways without thereby deviating from the scope thereof. Thus the swivel axis 11 of the knife and the axis of rotation 3 of the cutting member may be skewly situated rela-30 tive to one another instead of being situated ina common plane, in case such a solution is advan-:
' ; ' ~ , tageous Furthermore the rotor cutter may be provid-ed with a plurality of cutting members.
: :
;: ~
:
The expression "rotor cutter" includes all cutters comprising a rotating cutting member, such as rotary lawn movers, reapers,~topping machines etc.
, :::
20 GB-PS ~o. 1.220,353 discloses a rotor cutter of the above type, which comprises a cutting member arranged on a vertical rotary shaft. The cutting member comprises a knife holder mounted at the lower end of the shaft, a plurality of knives with a 25 shank extendi~ng downwards and outwards from said knife holder, and a blade formed integral with said shank and adapted to rotate in a plane perpen-dicular to the longitudinal axis of the rotary shaft. At the upper end the shank of the knife is 30 pivotally connected to the knife holder by means of a pin. The longitudinal axis of the pin forms an acute angle with the rotary shaft. By such a rotor cutter, the shank of the knife is subjected to a large moment especially at its upper end d~e to the centrifugal force caused by the rotation of 5 the cutting member. The shank of the knife must therefore be relatively thick in order to resist the above moment. On the other hand, the knife blade must be relatively thin in order to provide the best possible cutting result. An unfortunate 10 result of the above contradicting conditions is that such a knife is relatively expensive to manufacture.
The integral forming of the shank and the blade of the knife is furthermore encumbered with the draw-back that the entire knife must be replaced when the -15 blade is damaged, which in turn results in high operating expenses. The achievable cutting result suffers furthermore from the drawback that the entire knife swivels upwards and backwards when nothing but the blade hits an obstacle.
:
20 DE-PS No. 29 20 244 dlscloses a rotor cutter where the knife holder of the cutting member is a disk.
On the bottom side of the disk, knives are rotatably arranged about an axis parallel to the axis of rotation of the cutting member, said knives project-25 ing radially outwards from the disk when the cuttingmember is rotating. As a result the knives turn and clear possible obstacles such as a small stone or a stump. Experience has, however, shown that ~this type of cutting members involves a high risk ;30 of said cuttlng member and the driving mechanism causing said member to rotate being seriously damaged when the cutting member hits a large object such as a large stone or a large stump.
The object of the invention is to provide a rotor cutter of the above type, which at low operating costs reduces the risk of damages of the cutting member and the driving mechanism when the knife hits S obstacles while achieving an excellent cutting result.
The rotor cutter according to the invention is characterissd in that the blade is rotatably jour-nalled about an axis of rotation relative to the 10 shank. When the shank of the knife hits an obstacle, the entire knife swivels backwards and upwards about the swivel axis so as to clear said obstacle.
However, when the blade hits an obstacle, only the blade and not the entire knife is turned, which 15 presents an advantage for the achievement of a very uniform cutting result ~ecause then the blade returns faster to its cutting position than when the entire knife is turned. As the blade of the knife can be turned relative to the shank of the 20 knife, the moment arm is reduced such that the total risk of damage to the cutting member and its driving mechanism is simultaneously reduced when the knife hits an obstacle, said moment arm trans-i`erring the moment to the shank of the kniEe when 25 said knife hits an obstacle. Finally, the costs involved in replacing damaged blades are very low ; because the form of the blades is very simple with the result that the manufacture of said blades is very inexpensive.
30 According to the invention the axis of rotation may be substantially parallel to the axis oE rota-tion of the cutting member. As a result, the bladeof the knife remains in its cutting plane when it hits an obstacle, which presents an advantage for the achievement of an optimal cutting result. Thus 5 such an embodiment of the invention turned out in practice to render it possible to achieve a cutting result of the same quality as is obtained by means of lawn movers having cutting cylinders.
Moreover, the blade may according to the invention 10 be replaceably connected to the shank. Such an embodiment of the invention is considered particu-larly advantageous for achieving low operating costs.
Furthermore the angle formed by the swivel axis of 15 the knife and the axis of rotation of the cutting member may be in the range 30 to 60, and prefer-ably in the range 40 to 50, said ranges having proved to be particularly advantageous in practice.
Finally according to the invention the rotatable ~;~ 20 journalling of the kniie relative to the kniie holder may be situated a short distance from the axis of rotation of the cutting member said rotat-able journalling forming the swive~ axis . As a resuIt the knife holder can advantageously be shaped 25 such that transverse to the axis of rotation of the cutting member said holder is of a small dimen-sion which minimizes the ris~ of exactly this portion of the cutting member hitting an obstacle in the ground and of the cutting member andJor its 30 driving mechanism being damaged.
The invention is explained in greater detail below with reference to the accompanying drawing, in which the Figure is an axial, sectional view through an embodiment of a cutting member for a rotor cutter 5 accordlng to the invention.
The cutting member 1 of the Figure is fixedly con-nected to a substantially vertical shaft 2 adapted to cause the cutting member to rotate about a vertical axis of rotation 3 by means of a driving 10 mechanism not shown. The cutting member 1 comprises a hub 4 $ixedly connected to the shaft 2. A knife holder 6 is bolted onto the hub 4 by means of screws 5, said knife holder 6 comprising a disk 7. Two diametrically opposing notches 8 are shaped at the 15 periphery of the disk 7, only one notch appearing from the drawing. A bushing 9 is situated in each notch and is welded at 10 to the disk 7 in such a manner that the axis 11 of the bushing forms an angle ~ of about 45 with the axis of rotation 3 20 of the cutting member. The angle can, however, be arbitrarily chosen in the range of 0 to 90. The axis 11 of the bushing 9 is a swivel axis for a knife 12 comprising a shank 13 and a blade 14. The shank 13 is shaped like a two-legged fork and is 25 formed by two flat bars welded together at one end at 17 and forming the legs 15, 16 of the fork at the ;~ opposite end. The distance between the legs of the fork corresponds substantially to the length of the bushing 9. Each leg is at its free end provided 30 with an opening 18, 19, and a bolt 20 extends through each of these openings 18, 19 and through the bushing 9. A nut 21 is screwed onto the end of ~he bolt 20. Accordingly the bolt 20 forms the swivel axis 11 for the knife 12.
The opposite end of the fork-shaped shank 13 is provided with an opening 22 allowing passage of a bolt 23. The bolt 23 is secured by means of a nut 5 24 and comprises a shank portion 25 of a larger diameter than the opening 22. The blade 14 is situated on the shank portion 25 and comprises at one end an opening 26 of an inner diameter slightly larger than the outer diameter of the shank portion.
10 As a result the blade 14 is rotatably arranged about an axis of rotation 27 formed by the axis of the bolt 23 and being substantially parallel to the axis of rotation 3 of the cutting member 1.
When the cutting member 1 is rotating, the blade 15 14 sweeps a plane substantially perpendicular to the axis of rotation 3, and the shank 13 and the blade 14 of the knife 12 are in the position shown in the Figure where they project radially outwards from the axis of rotation 3 of said cutting member 20 1. When only the blade 14 hits an obstacle, said blade swivels backwards and clears said obstacle.
When also the shank 13 hits the obstacle, saia shank 13 and consequently also the blade 14 swivels backwards and upwards about the swivel axis 11 and 25 cIears the obstacle.
The invention may be modified in many ways without thereby deviating from the scope thereof. Thus the swivel axis 11 of the knife and the axis of rotation 3 of the cutting member may be skewly situated rela-30 tive to one another instead of being situated ina common plane, in case such a solution is advan-:
' ; ' ~ , tageous Furthermore the rotor cutter may be provid-ed with a plurality of cutting members.
: :
;: ~
:
Claims (5)
1. A rotor cutter comprising a cutting member (1) adapted to be driven into rotation about an axis of rotation (3), where said cutting member comprises a knife holder (6) connected with a knife (12) having a shank (13) extending downwards from said knife holder (6), and where the shank at its upper end is rotatably journalled about a swivel axis (11) relative to the knife holder (6), said swivel axis forming an acute angle (.alpha.) with upward angle spaces with the axis of rotation (3) of the cutting member (1), and where the knife is provided with a blade (14) at the lower end of the shank (13), the rotation of the cutting member (1) causing said blade to rotate in a plane substantially perpendicular to the axis of rotation of said cutting member (1), characterised in that the blade (14) is rotatably journalled about an axis of rotation (27) relative to the shank (13).
2. A rotor cutter as claimed in claim 1, charac-terised in that the axis of rotation (27) extends substantially parallel to the axis of rotation (3) of the cutting member (1).
3. A rotor cutter as claimed in claim 1 or 2, characterised in that the blade (14) is replaceably connected to the shank (13).
4. A rotor cutter as claimed in claim 1, charac-terised in that the angle (.alpha.) formed by the swivel is (11) of the knife and the axis of rotation (3) of the cutting member is in the range 30 to 60°, and preferably 40 to 50°.
5. A rotor cutter as claimed in claim 1 or 4, chacterised in that the rotatable journalling of the knife (12) relative to the knife holder (6) is situated a short distance from the axis of rotation (3) of the cutting member, said rotatable journal-ling forming the swivel axis (11).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2027803 CA2027803A1 (en) | 1990-10-17 | 1990-10-17 | Rotor cutter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2027803 CA2027803A1 (en) | 1990-10-17 | 1990-10-17 | Rotor cutter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2027803A1 true CA2027803A1 (en) | 1992-04-18 |
Family
ID=4146175
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2027803 Abandoned CA2027803A1 (en) | 1990-10-17 | 1990-10-17 | Rotor cutter |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2027803A1 (en) |
-
1990
- 1990-10-17 CA CA 2027803 patent/CA2027803A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |