Milling shaft for a snow blower, especially a rear-mounted milling head of a snow groomer

Description

[0001] The invention relates to a tiller shaft for a snow blower, in particular a rear tiller of a snow groomer, according to the preamble of claim 1. The invention also relates to a rear tiller for a snow groomer with such a tiller shaft and to a snow groomer with such a rear tiller.

[0002] A cutting shaft for a snow blower is known from US 5581914 A. The cutting shaft has a plurality of cutting teeth distributed over the circumference of a shaft casing of the cutting shaft. Each cutting tooth is provided with two tooth cusps spaced apart from each other in the direction of rotation of the cutting shaft. Each tooth cusp has a cutting tip, with the two cutting tips of each cutting tooth being offset from each other in the direction of rotation by a circumferential angle ranging between 20° and 40°.

[0003] Another auger shaft for a rear tiller of a snow groomer is known from DE 10 2013 204 723 A1. The known auger shaft is rotatably mounted in a rear tiller of the snow groomer and has a shaft casing on which a plurality of auger teeth are arranged, distributed over its circumference and length. Each auger tooth is provided with two tooth cusps, each of which forms part of a tooth tip. Each tooth tip is supported on the shaft casing of the auger shaft by two support webs. The two support webs are arranged axially offset from one another in the longitudinal direction of the auger shaft and have front flanks, each of which has a cutting function.

[0004] The object of the invention is to create a tiller shaft, a rear tiller and a snow groomer of the type mentioned above, which enable the achievement of a fine-grained processed snow surface.

[0005] This object is achieved for the auger shaft by the features of claim 1. When used in a snow blower, the auger shaft according to the invention enables particularly fine-grained comminution of snow and ice chunks. The auger shaft according to the invention is preferably used in a rear tiller of a snow groomer. This makes it possible to achieve a fine-grained, treated snow surface when the rear tiller is operated as a rear-mounted device on a snow groomer. Due to the height difference according to the invention between the front and rear cutting tips of each auger tooth, the milling work is evenly distributed between the two cutting tips of each auger tooth when the auger shaft is in operation. The height difference between the front and rear cutting tips is preferably between 5 mm and 10 mm. A particularly advantageous auger tooth geometry provides for a height difference of 7.5 mm.According to the invention, the two cutting tips of each milling tooth are also spaced apart from one another in the circumferential direction, i.e. in the direction of rotation of the milling shaft, by a relatively large circumferential angle selected from a range between 20° and 40°. Particularly advantageously, the circumferential angle, i.e. the angle of rotation between two radials to the axis of rotation of the milling shaft, each of which is tangent to a front tip of the respective cutting tip, is 30°. The relatively large distance in the direction of rotation between the two cutting tips of the two tooth cusps of each milling tooth means that the rear cutting tip of the rear tooth cusp has already covered a sufficient circumferential path during one rotation of the milling shaft before it encounters a chunk of snow or ice that has already been processed by the respective front cutting tip.This results in the snow or ice chunks already processed by the front cutting tip being further broken down by the rear cutting tip of each cutting tooth. The preferred height difference of at least 5 mm between the lower front cutting tip and the higher rear cutting tip of each cutting tooth is based on a typical processing depth of approximately 20 mm for a cutter shaft on a snow groomer's rear tiller. This ensures at least a largely even distribution of the cutting work across each front and rear cutting tip of each cutting tooth. The combination of the described features thus results in a dual cutting or separating function for each cutting tooth for corresponding snow or ice chunks.

[0006] The provision of cutting edges in the area of ​​the cutting tips enables cutting and separating functions at a greater radial distance from the shaft casing than with the previously described prior art. The auger shaft therefore enables effective snow surface processing even at a shallower processing depth than with the prior art, which features cutting edges in the area of ​​the support webs below the tooth cusps.

[0007] In a refinement of the invention, both cutting tips each have a front cutting edge, each of which is inclined forward in the direction of rotation by an angle of at least 20° relative to a radial intersecting the axis of rotation of the milling shaft. This refinement provides both the front cutting tip and the rear cutting tip with a cutting edge that is at the front in the direction of rotation, each of which is inclined forward in the direction of rotation relative to a corresponding radial. This results in a steep angle of the cutting edges in the direction of rotation, resulting in a true, knife-like cutting effect for each cutting edge of each of the two cutting tips of each milling tooth.This is an advantage over the prior art, in which the front tooth tip of each cutting tooth has a substantially radially aligned front cutting edge, so that when it encounters snow or ice lumps, it essentially creates an impact function, which can lead to chipping and large chunks of snow in hard snow and ice conditions. The design according to the invention avoids such disadvantages.

[0008] In a further embodiment of the invention, the front cutting edge of the front cutting tip is inclined forward at a smaller angle relative to the radial intersecting the rotation axis than the front cutting edge of the rear cutting tip relative to the corresponding radial. Preferably, a front cutting edge of the cutting tip of the rear tooth cusp is oriented more steeply than the front cutting edge of the cutting tip of the front tooth cusp.

[0009] In a further embodiment of the invention, both cutting tips of each milling tooth are supported by a common tooth base that is firmly connected to the shaft shell. The tooth base has a continuous support web on the shaft shell over the entire length of the milling tooth - viewed in the direction of rotation. The fact that the milling tooth is firmly connected to the shaft shell by a material bond or other means over the entire length of a lower edge of the tooth base, which forms the continuous support web, results in a particularly stable connection of the respective milling tooth to the shaft shell. The milling teeth are preferably made of a steel alloy and welded to a surface of the shaft shell.Both the tooth base and the two tooth cusps with their cutting tips are aligned in one plane to each other, so that a plate-shaped component is produced for each milling tooth, which is preferably produced by punching and subsequent grinding of the cutting edges.

[0010] In a further embodiment of the invention, the tooth base has at least one recess positioned radially above the support web. This recess serves to reduce weight. Since this recess is formed radially above the continuous lower edge of the tooth base, i.e., the continuous support web, in the respective milling tooth, the stability of the connection between the milling tooth and the shaft casing is not compromised by this recess. The recess is preferably achieved by a suitable punching in the plate-shaped component of the milling tooth.

[0011] For the rear tiller for a snow groomer, the object underlying the invention is achieved by the features of claim 7.

[0012] For the snow groomer with such a rear tiller, the object underlying the invention is achieved by the features of claim 8.

[0013] Further advantages and features of the invention emerge from the claims and from the following description of a preferred embodiment of the invention, which is illustrated with reference to the drawings. Fig. 1 schematically shows an embodiment of a snow groomer according to the invention with a rear-mounted embodiment of a rear tiller according to the invention, Fig. 2 the rear tiller for the snow groomer according to Fig. 1 , Fig. 3 schematically shows an enlarged cross section through an embodiment of a milling shaft according to the invention for the rear milling machine according to the Fig. 1 and 2and Fig. 4 in a further enlarged and detailed representation a milling tooth for the milling shaft according to Fig. 3 .

[0014] A snowcat P according to Fig. 1 is intended for the maintenance and shaping of snowy terrain, particularly in a ski area. The snow groomer P is equipped with a rear implement carrier at the rear, on which a rear tiller HF is detachably mounted and is otherwise hydraulically connected to the working hydraulics of the snow groomer P. The rear tiller HF is provided with at least one tiller shaft 1, on the cylindrical shaft casing of which a plurality of tiller teeth 3 are arranged, distributed in the direction of rotation and in the longitudinal direction of the tiller shaft 1. The tiller teeth 3 are firmly connected to a surface of the shaft casing 2 of the tiller shaft 1. In the illustrated embodiment, the tiller teeth 3 are made of a steel alloy and are integrally welded to the surface of the shaft casing 2. All tiller teeth 3 are identical to one another as plate-shaped and one-piece bodies that are aligned parallel to one another in radial planes to a rotation axis D of the tiller shaft 1.Each milling tooth 3 has - viewed in the direction of rotation R - a front tooth cusp 5 and a rear tooth cusp 6 spaced apart in the direction of rotation. Fig. 3 The direction of rotation R is shown relative to a direction of travel F of the snow groomer P, which corresponds to a towing direction of the rear tiller HF. The two tooth cusps 5 and 6 are supported by a tooth base 4, which, together with the tooth cusps 5 and 6, forms a one-piece, plate-shaped body and is provided with a support web 7 toward the shaft shell 2.

[0015] Based on the Fig. 3 and 4It can be seen that both the front tooth cusp 5 and the rear tooth cusp 6 are each provided with a cutting tip which is curved forward in the direction of rotation R. The front cutting tip of the front tooth cusp 5 is positioned at a smaller radial distance to a surface of the shaft shell 2 of the milling shaft 1 than the cutting tip of the rear tooth cusp 6. Corresponding pitch circle lines T 1 and T 2 , which are applied to the front cutting tip and the rear cutting tip, respectively, reveal a corresponding height difference A ( Fig. 4 ). This height difference A is 7.5 mm in the illustrated example. Fig. 3 , a snow surface S is indicated and a processing depth of each cutting tooth 3 is shown with the rear tiller HF in milling mode. It is clearly visible that the front cutting tip of the front tooth cusp 5 already penetrates the snow surface S beyond the pitch circle line T 1. It can also be seen that the rear cutting tip of the rear tooth cusp 6, which penetrates 7.5 mm deeper, creates an additional pitch circle line T 2 that penetrates deeper into the snow surface S.

[0016] As in Fig. 4 As can be seen, a front tip of the cutting tip of the front tooth cusp 5 is offset by an angle α in the direction of rotation to a front tip of the cutting tip of the rear tooth cusp 6. This circumferential angle α is 30° in the illustrated embodiment. In other embodiments of the invention, this circumferential angle α is between 20° and 40°. The circumferential angle α is illustrated by a first radial Rd 1 , which is applied to the front tip of the cutting tip of the front tooth cusp 5 and intersects the axis of rotation D of the milling shaft 1, and by a further radial Rd 2 , which also intersects the axis of rotation D and is applied to the front tip of the rear cutting tip of the rear tooth cusp 6.

[0017] In addition, Fig. 4 It can be clearly seen that both cutting tips of the front tooth cusp 5 and the rear tooth cusp 6 are curved forward in the direction of rotation. Both cutting tips each have a front cutting edge 9, 10. A front cutting edge 9 of the cutting tip of the front tooth cusp 5 is aligned at an angle β to a radial Rd 3, which is formed as an acute angle of at least 20° and a maximum of 40°. Fig. 4 In the illustrated embodiment, the angle β is 23°. The rear cutting tip of the rear tooth cusp 6 also has a front cutting edge 10, which is aligned at an acute angle γ to a radial Rd 4. The front cutting edge 10 of the rear tooth cusp 6 is aligned somewhat steeper than the front cutting edge 9 of the front tooth cusp 5. In the illustrated embodiment, the angle γ is 25° and thus also lies in the advantageous range between 20° and 40°.

[0018] As shown by the Fig. 3 and 4 As can be seen, the milling tooth 3 has a lower edge which is continuous over the entire length of the milling tooth 3 in the direction of rotation and which forms a support web 7. This support web 7 rests with its entire, circularly curved underside flat on the surface of the shaft shell 2 of the milling shaft 1 and is materially connected to the surface of the shaft shell 2. Finally, the milling tooth 3 is provided with a recess 8 which begins at a radial distance above the support web 7 and is essentially triangular in shape, approximately parallel to an outer contour of the front tooth cusp 5. The recess 8 is formed as a passage in the form of a punched-out portion and serves to reduce the weight of the milling tooth 3.

Claims

1. A tilling shaft (1) for a snow tiller, in particular for a rear-mounted tiller (HF) of a snow groomer (P), with a plurality of tiller teeth (3) arranged spread over a circumference of a shaft jacket (2) of the tilling shaft (1), wherein each tiller tooth (3) is provided with two cusps (5, 6) at a distance to one another in the rotation direction of the tilling shaft (1), wherein each cusp (5, 6) is provided with a cutting tip, wherein the two cutting tips of each tiller tooth (3) are arranged offset to one another in the direction of rotation (R) by a circumferential angle (α) in a range between 20° and 40°, relative to a rotary axis (D) of the tilling shaft (1), characterized in that a cutting tip, at the front in the direction of rotation (R) when viewed radially, has a distance to the shaft jacket (2) at least 5 mm less than that of the rear cutting tip of each tiller tooth (3).

2. The tilling shaft (1) according to claim 1, characterized in that the circumferential angle (α) is 30°.

3. The tilling shaft (1) according to claim 1 or 2, characterized in that each cutting tip has a front cutting edge (9, 10) respectively which is inclined forwards in the direction of rotation (R) at an angle of at least 20° relative to a radial (Rd1, Rd2) intersecting the rotary axis (D) of the tilling shaft (1).

4. The tilling shaft (1) according to claim 3, characterized in that the front cutting edge (9) of the front cutting tip is inclined forwards at a lower angle, relative to the radial (Rd1) intersecting the rotary axis (D), than the front cutting edge (10) of the rear cutting tip relative to the corresponding radial (Rd2).

5. The tilling shaft (1) according to any of claims 1 to 4, characterized in that both cutting tips of each tiller tooth (3) are supported by a common tooth base (4) which is permanently connected to the shaft jacket (2), wherein the tooth base (4) has a contact edge (7) continuous over an entire length of the tiller tooth (3) - when viewed in the direction of rotation (R) - on the shaft jacket (2).

6. The tilling shaft (1) according to claim 5, characterized in that the tooth base (4) has at least one cutout (8) positioned radially above the contact edge (7).

7. A rear-mounted tiller (HF) for a snow groomer (P) with at least one tilling shaft (1) according to any of the preceding claims.

8. A snow groomer (P) with a rear-mounted tiller (HF) according to claim 7.