Adjustment aid for mounting chopper knives on a chopper drum of a forage harvester, forage harvester equipped therewith and associated method

Abstract

Adjustment aid (78) for mounting chopper knives (68) on a chopper drum (22) of a forage harvester (10), wherein: the chopping drum (22) is rotatably mounted and is equipped with knife holders (66) distributed around its circumference, to each of which at least one chopping knife (68) can be fastened by screws (70) and, when the screws (70) are loosened, can be displaced relative to the associated knife holder (66), the chopping knives (68) when mounted on the chopping drum (22) interact with a stationary counter-blade (62) to cut the crop, and an adjustment aid (78) is provided which facilitates positioning of the chopping knives (68) in a desired position relative to the counter-blade (62), wherein the adjustment aid (78) is detachably fixable on the counter-blade (62) and comprises a body (80) with a first surface which can be brought into contact with the surface (90) of the counter-blade (62) facing the crop flow fed to the chopper drum (22) and a second surface which can be brought into contact with the surface (92) of the counter-blade (62) adjacent to the chopper drum (22), as well as a clamping element (86) which, when mounted on the counter-blade (62), encloses the counter-blade (62) between itself and the second surface (84).

Description

[0001] The invention relates to an adjustment aid for mounting chopper knives on a chopper drum of a forage harvester, a forage harvester equipped therewith and an associated method. State of the art

[0002] Forage harvesters are used in agriculture to harvest whole plants or parts of them (especially fruit clusters). The plants (or parts) are chopped and loaded onto a transport vehicle, usually for use as animal feed or in biogas plants.

[0003] The crops harvested by a harvesting header, which can be designed, for example, as a pick-up for grass harvesting or as a mowing header for harvesting whole corn plants, are conveyed through a rear opening of the harvesting header into the feeder housing of the forage harvester. In the feeder housing, the crop is pre-compacted by fixed, lower pre-compression rollers and interacting upper pre-compression rollers, which are pre-tensioned downwards by spring and / or hydraulic forces. The pre-compression rollers are then fed to a chopper drum. Distributed around the circumference of the drum are chopping knives that chop the crop in conjunction with a fixed counter-blade. The chopper knives are usually attached by screws to knife holders, which in turn are welded to the drum shell of the chopper drum (see DE 199 18 553 A1 or DE 101 26 280 A1).The chopping knives can be ground by a grinding device and the counter blade is radially adjustable relative to the enveloping circle of the chopping drum described by the cutting edges of the chopping knives, for which purpose automatically operating adjustment drives are provided.

[0004] If the chopping knives are damaged or worn, they must be replaced with new ones. To do this, loosen and remove the screws, remove the old chopping knives, position the new chopping knives, and then reattach and tighten the screws. It can also be useful to loosen worn chopping knives, pull them out further, and then screw them back on to improve the airflow effect of the chopping knives. When doing these operations, care must be taken to ensure that all chopping knives are correctly positioned relative to the counterblade. If one or more chopping knives protrude further outwards than others, they will be ground down more during the subsequent grinding process than the other chopping knives that protrude less far outwards, leading to unnecessary wear on the chopping knives that initially protrude further outwards. Aligning and screwing on the chopping knives is therefore a time-consuming process.

[0005] In the state of the art, some measures have been proposed to facilitate the positioning of the chopping knives when attaching them to the chopping drum: It was proposed to attach adjustable adjusting screws to the chopping drum, which serve as a radially inner stop for the chopping knives (DE 1 279 415 A, DE 70 38 523 U).

[0006] Furthermore, it was proposed to adjust the knife holder relative to the chopping drum by means of screws (DE 1 840 674 U, DE 33 29 914 A1) or to align the chopping knives parallel to the counter-blade using eccentric tools and finally to screw them tight (DE 22 09 672 A1, DE 20 2010 006 714 U1, DE 10 2013 011 088 A1).

[0007] Finally, it has been proposed to use so-called setting gauges to facilitate the correct positioning of the chopping knives. The setting gauge is attached to the lower edge of the knife holder and serves to align the chopping knife relative to the knife holder (DE 1 582 639 A1), or the grindstone (US 3 370 628 A) or setting screws attached to the housing of the chopping drum (US 3 452 796 A, DE 22 20 826 A) can be used as a setting gauge for the chopping knives. The introduction to the description of DE 22 20 826 A also mentions that the prior art uses a gauge between the edge of the counterblade and the respective knife to ensure precise insertion of the knives. This gauge is obviously a so-called feeler gauge, i.e. a simple metal strip of known thickness.DE 30 10 416 A1 uses an induction proximity sensor attached to the underside of the counter blade to measure the distance between the counter blade and the chopping knives. Task

[0008] Adjusting the blades relative to the chopping drum using adjusting screws according to DE 1 279 415 A and DE 70 38 523 U has the disadvantage that the blade holder serves as a reference point for positioning the chopping blades. However, since blade holders are typically attached to the chopping drum with certain tolerances, this does not allow for the precise adjustment of the chopping blades relative to the counterblade that would actually be sensible and necessary. The chopping knives, which can be adjusted by means of screws or eccentrics, in accordance with DE 1 840 674 U, DE 33 29 914 A1, DE 22 09 672 A1, DE 20 2010 006 714 U1 and DE 10 2013 011 088 A1, do make it easier to position the knives, but this requires a certain amount of effort and, in addition, the knife must be precisely aligned with the counter-blade, which is relatively difficult with a freely rotating chopping drum.The setting gauge according to DE 1 582 639 A1 only allows the adjustment of the chopping knives relative to the knife holder, which entails the disadvantage mentioned above with regard to DE 1 279 415 A and DE 70 38 523 U. The procedures according to US 3 370 628 A, US 3 452 796 A, and DE 22 20 826 A require chopping knives extending across the entire width of the chopping drum. Finally, the feeler gauge described in DE 22 20 826 A as prior art and considered generic is also quite cumbersome to handle. The measuring sensor according to DE 30 10 416 A1 only responds when a predetermined distance is exceeded and is therefore not suitable for manually adjusting the precise position of the chopping knives.

[0009] The problem underlying the invention is seen in providing an adjustment aid for mounting chopper knives on a chopper drum of a forage harvester, a forage harvester equipped therewith and an associated method which does not have the disadvantages mentioned or has them to a reduced extent, ie enables an accurate, simple and quick positioning and fastening of the chopper knives on a chopper drum with little effort. Solution

[0010] The present invention is defined by the claims.

[0011] A setting aid for mounting chopper knives on a chopper drum of a forage harvester is proposed. The chopper drum is rotatably mounted and equipped with knife holders distributed around its circumference, to each of which at least one chopper knife can be secured by screws and, when loosened, can be moved relative to the corresponding knife holder. When mounted on the chopper drum, the chopper knives interact with a stationary counterblade to chop the crop. An adjustment aid that can be removably attached to the counterblade facilitates positioning the chopper knives in a desired position relative to the counterblade.

[0012] In other words, an adjustment aid is attached to the counterblade while the chopping knives are being attached and screwed tight to the knife holders of the chopping drum. The adjustment aid has markings, notches, recesses, stops, inclined surfaces, or other shapes or means that enable correct positioning of the chopping knives. The chopping knives are then positioned opposite the adjustment aid and correctly aligned, and finally screwed tight to the knife holder. Because the adjustment aid is temporarily attached to the counterblade, the installer does not have to hold the adjustment aid by hand (as is the case with the feeler gauge of the prior art according to DE 22 20 826 A), but has both hands free to align the chopping knife and tighten the screws. This allows for correct positioning and securing of the chopping knives to the chopping drum with minimal effort.

[0013] The adjustment aid comprises a body with a first surface which can be brought into contact with the (upper) surface of the counter-blade facing the crop flow fed to the chopper drum and with a second (rear) surface which can be brought into contact with the surface of the counter-blade adjacent to the chopper drum, as well as a clamping element which, when mounted on the counter-blade, bears against a front surface of the counter-blade and encloses the counter-blade between itself and the second surface.

[0014] The adjustment aid can have an inner contact surface for the chopping knife and / or an outer contact surface for the chopping knife, between which a leading cutting edge of the chopping knife can be inserted. The inner contact surface of the adjustment aid then comes into contact with a radially inner surface of the chopping knife adjacent to the cutting edge of the chopping knife, and the outer contact surface of the adjustment aid comes into contact with a radially outer surface of the chopping knife adjacent to the cutting edge of the chopping knife. The outer contact surface of the adjustment aid is preferably curved according to the desired enveloping circle radius of the cutting edges of the chopping knives.

[0015] The inner contact surface may be spaced axially (i.e. in the longitudinal direction of the counter-blade and the axis of rotation of the chopping drum) from the outer contact surface.

[0016] The axial dimension of the adjustment aid can at least approximately correspond to the axial dimension of a chopper blade. However, it can also be shorter or longer than the width of the chopper blade, and can, for example, extend across the width of several adjacent chopper blades or across the entire width of the chopper drum.

[0017] The adjustment aid can comprise a leading surface with an upper corner, with the outer contact surface adjoining the corner downstream in the direction of rotation of the chopping blades, so that chopping blades projecting radially outward further than a desired target enveloping circle abut against the leading surface with their cutting edge. The leading surface can be inclined in the direction of rotation of the chopping blades in order to press chopping blades abutting against the leading surface radially inward. The cutting edge of the chopping blade can also be angled, and the leading surface of the adjustment aid can be inclined to the side according to the inclination of the chopping blade. Embodiment

[0018] The drawings show three exemplary embodiments described in more detail below, whereby the reference numerals are not intended to limit the interpretation of the claims. It shows: Fig. 1 a side view of a forage harvester with a chopper drum and a counter blade, Fig. 2 a perspective view of a first embodiment of an adjustment aid, Fig. 3 a side view of the adjustment aid attached to the counter blade of the Fig. 2 with a chopping knife attached to it, Fig. 4 an enlarged view of the Fig. 3, Fig. 5 a perspective view of a second embodiment of an adjustment aid, Fig. 6 a side view of the adjustment aid attached to the counter blade of the Fig. 5 with a chopping knife attached to it, Fig. 7 a perspective view of a third embodiment of an adjustment aid, Fig. 8 a perspective view of a leg of the adjustment aid of the Fig. 7, Fig. 9 a perspective view of the adjustment aid attached to the counter blade of the Fig. 7 with a chopping knife attached to it during assembly, and Fig. 10 a side view of the adjustment aid attached to the counter blade of the Fig. 7 with a chopping knife attached to it.

[0019] In the Fig. 1 shows a self-propelled forage harvester 10. The forage harvester 10 is mounted on a frame 12 supported by front driven wheels 14 and steerable rear wheels 16. The forage harvester 10 is operated from a driver's cab 18, from which a harvesting attachment 20 is visible. Crops picked up from the ground by the harvesting attachment 20, e.g., grass or the like, are fed via an intake conveyor with pre-compression rollers 42, which are arranged within an intake housing 50 removably supporting the harvesting attachment 20 on the front side of the forage harvester 10, to a chopper drum 22. The chopper drum 22, in cooperation with a counter-blade 62, chops the crop into small pieces and feeds it to a conveyor device 24. The material leaves the forage harvester 10 to a trailer traveling alongside via a discharge chute 26 that can rotate about an approximately vertical axis and is adjustable in inclination.Between the chopping drum 22 and the conveying device 24 there is a secondary shredding device 28 with two grain processor rollers, through which the material to be conveyed is fed tangentially to the conveying device 24.

[0020] The harvesting header 20 is designed as a so-called pick-up. The harvesting header 20 is mounted on a frame 32 and rests on the ground via support wheels 38 mounted on either side, each of which is fastened to the frame 32 via a carrier 46. The task of the harvesting header 20 is to pick up crops scattered on the ground of a field or deposited in a swath 49 and to feed them to the harvesting machine 10 for further processing. For this purpose, the harvesting header 20 is moved across the field during harvesting at a short distance or with a defined (i.e., controlled) contact force of the support wheels 38 to the ground. For transport on a road or path, it is raised by means of an actuator 48 in the form of a hydraulic cylinder, which pivots the intake housing 50 and the harvesting header 20 attached to it about the rotation axis 58 of the chopper drum 22.The actuator 48 also serves to adjust the height of the crop pickup 20 above the ground, or to adjust the contact pressure of the support wheels 38 on the ground. The harvesting header 20 includes a cross auger conveyor 36, which conveys the collected crop from the sides of the harvesting header 20 to a central discharge opening (not shown), behind which the intake housing 50 follows. The harvesting header 20 also has a crop pickup 54 (like the cross auger conveyor 36) that is rotationally driven. The crop pickup 54 is arranged below the discharge conveyor 36 and, with its tines 51, lifts the crop from the ground to transfer it to the discharge conveyor 36. In addition, a hold-down device 40 in the form of a metal plate arranged above the crop pickup 34 is attached to the frame 32.

[0021] In the following, directions such as sideways, down and up refer to the forward movement direction V of the harvesting header 20 and the harvesting machine 10, which runs to the left in the figures.

[0022] The chopping drum 22 comprises, as shown in the Fig. 3 is shown enlarged, a drum shell 64 on which a number of hump-like knife holders 66 are distributed circumferentially and laterally across the width of the chopping drum 22. The knife holders 66 are welded to the drum shell 64 in a manner known per se, although in another embodiment of the chopping drum 22 they could also be screwed to the drum shell 64 or screwed or welded to radially extending support disks. The chopping knives 68 are fastened to the knife holders 66 by two, three or more screws 70 which extend through bores in an outer pressure plate 72, elongated holes in the chopping knife 68 and bores in the knife holder 66 and are screwed into the thread of a holding plate 74 arranged below the knife holder 66. The elongated holes in the chopping knife 68 (cf. DE 10 2013 011 088 A1) make it possible to move the chopping knives 68 along the knife holder 66 (iein the . Fig. 3 diagonally downwards to the left) and to fix it again in a desired position in which the outer cutting edges 76 have a certain radial distance from the axis of rotation of the chopping drum 22.

[0023] Since the freehand finding of the correct position of the chopping knives 68 is difficult, time-consuming and error-prone, the present invention proposes an adjustment aid 78, of which Fig. 2 a first embodiment is shown in a perspective view. The adjustment aid 78 comprises a rectangular (L-shaped) body 80, which comprises two lower webs 82, which can be brought into contact with the (upper) surface 90 of the counter-blade 62 facing the crop flow fed to the chopper drum 22, and a front, downwardly extending leg 84, which can be brought into contact with the surface 92 of the counter-blade 62 adjacent to the chopper drum 22, as well as a clamping element 86, which, when mounted on the counter-blade 62, is fixed to the front, in Fig. 3, the clamping element 86 rests against the surface 94 of the counter-blade 62 shown on the left. The clamping element 86 is fastened to the body 80 by a screw 88. In other words, the body 80 and the clamping element 86 form an inverted U, which rests on the counter-blade 62 from above and is clamped to it by the screw 88. After loosening the screw 88, the adjustment aid 78 can be removed from the counter-blade 62.

[0024] The adjustment aid 78 has an inner contact surface 96 for the chopping blade 68 and two outer contact surfaces 98 for the chopping blade 68. The outer contact surfaces 98 are formed by lateral sections of the rear walls of the body 80 and the legs 84 (provided only in the two outer end regions of the body 80 with respect to the axial direction of the chopping drum 22), between which a central cutout 100 is formed. The legs 84 are connected below the cutout 100 by a web 102, which in turn carries the central, inner contact surface 96. If the contact surfaces 96, 98 are viewed from the side, as in the Fig. 3 and Fig. 4, they form an approximately V-shaped notch into which the leading cutting edge 76 of the chopping knife 68 can be inserted, as shown there. The inner contact surface 96 of the adjustment aid 78 engages a radially inner surface 104 of the chopping knife 68 adjacent to the cutting edge 76 of the chopping knife 68, and the outer contact surface 98 of the adjustment aid 78 engages a radially outer surface 106 of the chopping knife 68 adjacent to the cutting edge 76 of the chopping knife 68.

[0025] Since the cutting edge 76 of the chopping blade 68 is not arranged exactly parallel to the axis of rotation of the chopping drum 22, but (in order to achieve a pulling cut) at an angle inclined to the side (to the left or right), the inner contact surface 96 comprises two adjacent surfaces which are inclined to the left or right according to the two possible inclinations of the cutting edge 76, as shown in the Fig. 2, is therefore designed as a prism. If the cutting edge 76 (to achieve a chopping cut) runs parallel to the rotational axis of the chopping drum 22, the inner contact surface 96 could be designed to be flat overall.

[0026] The Fig. Figure 4 illustrates the operation of the adjustment aid 78. When the screw(s) 70 are tightened, the chopping blade 68 rests with its radially inner surface 104 on a support point 108 located at the upper end of the inner contact surface 96. The outer contact surface 98 forms an ideal cylindrical surface, i.e. it is not flat, but curved according to the desired enveloping circle radius of the cutting edges 76 of the chopping blades 68, and when the screw(s) 70 are tightened, a force is generated along the arrow 110, which presses the cutting edge 76 into the lower tip of the notch formed by the contact surfaces 96, 98. The chopping blade 68 thus tends to slide into the lower tip and, when the screws 70 are tightened, is fixed in the desired position in which the cutting edge 76 is located on the desired enveloping circle radius. The chopping drum 22 can rotate freely.To continue rotating the chopper drum 22 after securing a chopper blade 68, the adjustment aid 78 can be moved or removed along the counter-blade 62 after loosening the screw 88, the chopper drum 22 can be rotated, and the adjustment aid 78 can be repositioned. Generally, all chopper blades 68 in one row (i.e., in the circumferential direction) are replaced first, and then the next row is replaced. Once all chopper blades 68 of the chopper drum 22 have been correctly positioned using the adjustment aid 78 and tightened using the screws 70, the adjustment aid 78 is removed from the counter-blade 62 and stowed in a suitable location on the forage harvester 10, e.g., in the cab 18 or a toolbox.

[0027] The Fig. 5 and Fig. 6 show a second embodiment of an adjustment aid 78. Elements identical to the first embodiment are identified by the same reference numerals. A significant difference can be seen in the fact that the inner contact surface 96 is attached to a movable element 112, which is displaceable parallel to the upper side of the counter-blade 62 by an outer handle 114. The handle 114 is connected to the element 112 by a screw 116. This makes it possible to remove the element 112 from the position shown in the Fig. 5 and Fig. 6, in which a chopping knife 68 can be brought into contact with the inner contact surface 96, in particular against the force of a spring (not shown), into a position retracted into the body 80, in which a rear stop 118 of the element 112 rests against the body 80 and the chopping drum 22 can be rotated freely (without collision with the adjustment aid 78) in order to replace the chopping knife 68 following in the circumferential direction, whereas in the first embodiment of the adjustment aid 78, this must be removed after loosening the screw 88 or moved along the counter-blade 62. In the second embodiment, the inner contact surface 96 is conical in shape, but could, as in the first embodiment, also be shaped as a prism or plane.

[0028] The Fig. 7 to 10 show a third embodiment of an adjustment aid 78. It is similar to that according to the Fig. 2 to 4, so that reference can be made to the corresponding description, however, the inner contact surface 96 and the web 102 are omitted. In addition, at the upper end of the outer contact surface 98, which is formed in the lower area by the legs 84 positioned at the outer ends of the adjustment aid 78 and in the upper area by rearwardly extending, outer areas of the body 80, leading, inclined (prismatic) surfaces 120 are provided, which are inclined (sloping) outwards both rearwardly (in the direction of the chopper drum 22) and in the lateral direction (= axial direction of the chopper drum 22) as shown in the Fig. 8 and Fig. 9. The inclined surfaces 120 may each be flat or have a slight curvature.

[0029] The procedure for using the adjustment aid 78 according to Fig. 7 to 10 is as follows: First, the chopping knives 68 are installed as shown in the Fig. 9. The screws 70 are only tightened so that a displacement of the chopping blades 68 along the slots is still possible, ie in the Fig. 9 to the top right, in the plane of the chopping knives 68. If the fitter now rotates the chopping drum 22 (in particular jerkily) in the direction of the adjustment aid 78, the outer cutting edge 76 of the chopping knife 68 to be attached strikes the (preferably hardened or provided with a hard coating) leading upper side of the body 80 and the inclined surfaces 120 arranged there, which are preferably also hardened or provided with a hard coating.

[0030] In the case of chopping knives 68 with an angled cutting edge 76, the leading edge of the chopping knife 68 first strikes the upper side of the body 80 and the inclined surface 120. Due to the impact and the inclination of the surface 120, the chopping knife 68 receives a shock which displaces it inwards relative to the knife holder 66 until the cutting edge 76 slides past the rear, upper corner of the adjustment aid 78 and comes to rest on the outer contact surface 98. This process has Fig. 9 on the left side of the chopping knife 68 has already taken place, so that its cutting edge 76 rests against the outer contact surface 98. On the other hand, in the Fig. 9, the chopping knife 68 with its right-hand end of the cutting edge 76 still rests on the surfaces 120 from above and, if the chopping knife 68 is pressed against the surfaces 120 by a sudden rotation of the chopping drum 22, would also receive the described impact and slide around the upper corner of the body 80. Finally, the chopping knife 68 has reached its desired position and the screws 70 can be tightened. For inspection, the chopping knife 68 can be Fig. 10, before and / or after tightening the screws 70, along the outer contact surface 98, the radius of which corresponds to the desired enveloping circle radius of the chopping knives 68.

[0031] After tightening the screws 70, the described process is repeated on another chopping blade 68 until finally all chopping blades 68 of the chopping drum 22 are in the correct positions. Finally, the adjustment aid 78 is removed, and the counterblade 62 is adjusted to the position suitable for harvesting.

[0032] In the third embodiment, two inclined surfaces 120 are provided at both ends of the adjustment aid 78. Two of the surfaces 120 are required for chopping knives 68 inclined to the left with angled cutting edges 76, and the other two surfaces 120 for chopping knives 68 inclined to the right. Different adjustment aids 78 could also be used for the chopping knives 68 inclined in different directions, each having only one (equally) inclined surface 120 at both ends. In the case of chopping drums 22 with chopping knives 68 whose cutting edges 76 are precisely axially aligned, the surfaces could also be inclined only in the direction towards the chopping drum 22 (i.e., not to the side) in order to press the chopping knives 68 around the rear, upper corner of the body 80 upon impact.

Claims

[1] Adjustment aid (78) for mounting chopper knives (68) on a chopper drum (22) of a forage harvester (10), wherein: the chopping drum (22) is rotatably mounted and is equipped with knife holders (66) distributed around its circumference, to each of which at least one chopping knife (68) can be fastened by screws (70) and can be displaced relative to the associated knife holder (66) when the screws (70) are loosened, the chopping knives (68) when mounted on the chopping drum (22) interact with a stationary counter-blade (62) to cut the crop, and an adjustment aid (78) is provided which facilitates positioning of the chopping knives (68) in a desired position relative to the counter-blade (62), wherein the adjustment aid (78) is detachably fixable on the counter-blade (62) and comprises a body (80) with a first surface which can be brought into contact with the surface (90) of the counter-blade (62) facing the crop flow fed to the chopper drum (22) and a second surface which can be brought into contact with the surface (92) of the counter-blade (62) adjacent to the chopper drum (22), as well as a clamping element (86) which, when mounted on the counter-blade (62), encloses the counter-blade (62) between itself and the second surface (84). [2] Adjustment aid (78) according to claim 1, wherein the adjustment aid (78) has an outer contact surface (98) for the chopping knife (68), wherein the outer contact surface (98) of the adjustment aid (78) can be brought into contact with the cutting edge (76) and / or a radially outer surface (106) of the chopping knife (68) adjacent to the cutting edge (76) of the chopping knife (68) and is curved in accordance with the desired enveloping circle radius of the cutting edges (76) of the chopping knives (68). [3] Adjustment aid according to claim 1 or 2, wherein the adjustment aid (78) has an inner contact surface (96) for the chopping knife (68), wherein the inner contact surface (96) of the adjustment aid (78) can be brought into contact with a radially inner surface (104) of the chopping knife (68) adjacent to the cutting edge (76) of the chopping knife (68). [4] Adjustment aid (78) according to one of claims 2 or 3, wherein the adjustment aid (78) comprises a leading surface (120) with an upper corner, wherein the outer contact surface (98) adjoins the corner downstream of the corner in the direction of rotation of the chopping knives (68), so that chopping knives (68) projecting radially outwards further than a desired target enveloping circle abut with their cutting edge (76) against the leading surface (120). [5] Adjustment aid (78) according to claim 4, wherein the leading surface (120) is inclined in the direction of rotation of the chopping knives (68) in order to press chopping knives (68) abutting against the leading surface (120) radially inward. [6] Adjustment aid (78) according to claim 5, wherein the cutting edge (76) of the chopping knife (68) is angled and the leading surface (120) of the adjustment aid is inclined to the side in accordance with the inclination of the chopping knife (68). [7] Forage harvester (10), comprising: a rotatably mounted chopping drum (22) which is equipped with knife holders (66) distributed around its circumference, to each of which at least one chopping knife (68) can be fastened by screws (70) and can be displaced relative to the associated knife holder (66) when the screws (70) are loosened, a stationary counter-blade (62) with which the chopping knives (68) cooperate when mounted on the chopping drum (22) to cut the crop, and an adjustment aid (78) according to one of the preceding claims, which facilitates positioning of the chopping knives (68) in a desired position relative to the counter-blade (62). [8] Method for mounting chopper knives (68) on a chopper drum (22) of a forage harvester (10), wherein: the chopping drum (22) is rotatably mounted and is equipped with knife holders (66) distributed around its circumference, to each of which at least one chopping knife (68) can be fastened by screws (70) and can be displaced relative to the associated knife holder (66) when the screws (70) are loosened, the chopping knives (68) when mounted on the chopping drum (22) interact with a stationary counter-blade (62) to cut the crop, and an adjustment aid (78) is provided which facilitates positioning of the chopping knives (68) in a desired position relative to the counter-blade (62), wherein the adjustment aid (78) is detachably fixed to the counter-blade (62), the chopping knives (68) are successively brought into contact with the adjustment aid (78) and are aligned with respect to the associated knife holder (66) and screwed thereto, and the adjustment aid (78) is removed again from the counter-blade (62).

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