AU2010227706A1

AU2010227706A1 - Ejector or ejector unit for a road milling machine or the like

Info

Publication number: AU2010227706A1
Application number: AU2010227706A
Authority: AU
Inventors: Stefan Abresch; Cyrus Barimani; Karsten Buhr; Guenter Haehn; Thomas Lehnert
Original assignee: Wirtgen GmbH
Current assignee: Wirtgen GmbH
Priority date: 2009-03-25
Filing date: 2010-02-23
Publication date: 2011-09-08
Anticipated expiration: 2030-02-23
Also published as: JP2015014191A; DE102009014730B3; AU2010227706B2; WO2010108743A3; CN104074124B; KR20120000096A; BRPI1013408A2; JP6124857B2; EP2411581A2; BRPI1013408B1; CN104074124A; RU2491383C2; RU2011142980A; JP2012521501A; PL2411581T3; CN201901837U; JP5631966B2; TW201043751A; WO2010108743A2; EP2411581B1

Abstract

The invention relates to an ejector (20), in particular for a road milling machine, with which the maintenance effort is considerably simplified.

Description

EJECTOR OR EJECTOR UNIT FOR A ROAD MILLING MACHINE OR THE LIKE The invention relates to an ejector, in particular for the milling drum of a road milling machine or a surface miner, etc. Road milling machines usually comprise a milling tube on whose surface are mounted a plurality of bit holders. The bit holders are usually part of a bit holder changing system that also encompasses a base part. The base part is welded onto the surface of the milling tube, and replaceably receives the bit holders. The bit holder serves for mounting of a cutting bit, usually a round-shaft cutting bit, as known e.g. from P 37 01 905 Al. The bit holders are arranged on the surface of the milling tube so as to yield spiral shaped helices. The helices proceed from the edge region of the milling tube and rotate toward the center of the milling tube. The respective helices that proceed from the oppositely located edge regions therefore meet at the center of the milling tube. One or more ejectors are also then arranged in this region. The helices convey to the ejectors the material removed by the cutting bits. The ejectors then transport it out of the working region of the milling tube. The ejectors are subject to severe abrasive attack, and must therefore be regularly checked and replaced. For this, the ejector welded onto the milling tube must be detached and a new one welded on. Attention must be paid to the exact positioning and alignment of the ejector in order to achieve ideal discharge performance. This replacement work in the confined working area of the milling tube is laborious. It is an object of the invention to make available an improved ejector that enables simple machine maintenance. This object is achieved with an ejector according to Claim 1. The ejector comprises a mounting side, facing away from its conveying surface, having a support surface. With DE 10 2009 014 730.6 this mounting side, the ejector can be placed onto a component mounted on the milling tube, for example onto a carrying part welded thereon. By way of the support surface of the carrying part, the loads occurring during tool use are reliably dissipated at least in part. The ejector is equipped with a mounting receptacle or mounting extension, so that it is replaceably mountable. In this fashion it can easily be changed in the event of damage or wear. According to a preferred variant embodiment of the invention, provision can be made that the conveying surface of the ejector is arranged transversely to the feed direction of the ejector unit, and is at least locally embodied in concave fashion or is assembled, in the hollowed region, from line segments and/or curve segments. The concave or hollowed conformation enables a scoop-like geometry that improves the discharge rate. If provision is made that one or more depressions are introduced into the conveying surface, material removed during tool use can become deposited in the depressions. A "natural" wear protection layer forms there. According a variant of the invention, provision can be made that at least one screw receptacle is used as a mounting receptacle, and that the screw receptacle opens, toward the front side of the ejector, into a screw head receptacle in which a screw head of a mounting screw is at least locally nonrotatably receivable. Rapid and problem-free ejector replacement is possible with the screw connections. Countersunk or partly countersunk reception of the screw head prevents abrasive attack on the countersunk head region. In addition, loosening of the screw at this point is prevented. To allow the ejector to be reliably braced on a carrying part, provision can be made that at least one protruding securing extension, or a recessed securing receptacle, is arranged on the side facing away from the conveying surface. Transverse forces that occur can then be transferred, in particular, in positively engaged fashion from the ejector into the carrying part. This is possible in particular when provision is made that DE 10 2009 014 730.6 2 by means of the at least one securing extension or the at least one securing receptacle, any displacement of the ejector in a plane transverse to the feed direction can be limited in positively engaged fashion. If the conformation of the ejector is such that one or more shaped-on stiffening ribs are arranged on the rear side facing away from the conveying surface, a sufficiently rigid ejector can then be designed with little material outlay. Provision can be made according to the present invention that the screw receptacle is guided through the securing extension or securing receptacle. The carrying part is then utilized for a sufficient clamping length of the mounting screw. A preferred configuration of the invention is such that the mounting side is embodied in such a way that the ejector is installable in different operating positions. The ejector can, in particular, be embodied in mirror-symmetrical fashion, or can be embodied in the region of a mounting side in such a way that it enables installation reversibly in two different operating positions. Also conceivable is an ejector that enables three or four different operating positions. This is based on the recognition that the ejector becomes worn substantially on its region facing away from the milling tube. Once the worn state is achieved there, the ejector is removed and put back on having been rotated, for example, 180 degrees. A preferred configuration of the invention is such that the mounting side comprises a convex or crowned or spherical mounting portion for contact against a concave or hollowed receiving portion of a carrier. This connection creates a large connecting surface that ensures good energy transfer even when the conveying surface is asymmetrically loaded. A further improvement in service life is achieved by the fact that at least one wear protection element, made of a material more wear-resistant than the conveying surface, is arranged in the region of the conveying surface. In this context, DE 102009014730.6 3 provision can be made in particular that the wear protection element is constituted by a hard-material element, for example carbide or ceramic, or by an applied coating, for example a hardfacing. The invention will be further explained below with reference to exemplifying embodiments depicted in the drawings, in which: FIG. 1 is a front view of a milling drum of a road milling machine; FIG. 2 is a side view of the milling drum according to FIG. 1; FIG. 3 shows the view according to FIG. 2, enlarged and with a slightly modified depiction; FIG. 4 is a perspective front view of an ejector unit; FIG. 5 is a perspective rear view of the ejector unit according to FIG. 4; FIG. 6 is a perspective rear view of a carrier of the ejector unit according to FIG. 5; FIG. 7 is a perspective view of the carrier according to FIG. 6; FIG. 8 is a perspective front view of an ejector of the ejector unit according to FIG. 6; FIG. 9 is a perspective rear view of the carrier according to FIG. 8; FIG. 10 is a perspective rear view of a second embodiment of an ejector unit having an ejector and a carrier; and FIG. 11 is a perspective front view of the arrangement according to FIG. 10. DE 102009014730.6 4 FIG. 1 shows a milling drum having a cylindrical milling tube 10 onto whose drum surface 10.1 are welded a plurality of base parts 11 of bit holder changing systems. Base parts 11 carry replaceable bit holders 12. A cutting bit 13, specifically a round shaft cutting bit, is replaceably received in each bit holder 12. Base parts 11 are arranged with respect to one another so that they form a helix, specifically a transport helix. The helix rotates, proceeding from the side of milling tube 10 on drum surface 10.1, toward the milling tube center formed between the two sides. For better clarity, only some of the bit holder changing systems are depicted in FIGS. 1 and 2. Dashed lines that represent the center longitudinal axis of cutting bits 13 are shown as substitutes for the bit holder changing systems (not shown). As is evident from these lines, multiple transport helices are located on either side of the milling tube center. The transport helices meet in pairs in the region of the milling tube center. As is evident from FIG. 1, at least one respective ejector unit is arranged there. FIG. 3, as compared with the depiction in FIG. 2, does not show the bit holder changing systems, redirecting attention to the ejector unit. As is evident from this depiction, the ejector unit is constituted by a carrying part 30 and an ejector 20. FIGS. 4 and 5 show the ejector unit in isolation. Firstly the design of carrying part 30 will be explained with reference to FIGS. 6 and 7. Said part comprises a mounting foot 31 that forms on its underside a mounting surface 33. With this, carrying part 30 can be placed onto drum surface 10.1 and welded at the sides. Shaped onto mounting foot 31 is an upwardly projecting support part 35 that forms a rear side 36. Mounting foot 31 is widened by means of an extension 32 over rear side 36, so that it forms a wide mounting surface 33 having a large support spacing. The widened cross section produced by extension 32 furthermore brings about a reinforcement of the highly stressed transition region between mounting foot 31 and carrying part 35. A further widening of mounting surface 33 is achieved with a front-side DE 10 2009 014 730.6 5 protrusion 34 that, like extension 32, extends over the entire width of carrying part 30. Carrying part 30 comprises on the front side a support surface 37 that extends over the front side of carrying part 35 and also over part of mounting foot 31. This embodiment of support surface 37 enables strength-optimized bracing of ejector 20. Two receptacles 37.1, 37.2 are inset into support surface 37. The two receptacles 37.1, 37.2 are recessed into support surface 37 so that they form trough-like hollows. Ejector 20 will be explained below with reference to FIGS. 8 and 9. It is embodied in plate-shaped fashion as a drop forged part, and is therefore particularly rigid. Ejector 20 comprises a front-side conveying surface 21. Said surface is equipped with recesses 21.1, 22. Located between recesses 21.1 are ribs that are at an angle to the vertical and are thus inclined toward the center of the ejector. The recesses receive removed material during operational use, thus forming a "natural" wear protector. A particularly good conveying rate is furthermore achieved by the fact that conveying surface 21 is embodied in concave, and thus scoop-shaped, fashion. Recess 22 comprises two oblique surfaces 22.1 that are at an angle to conveying surface 21 and assist the conveying action. Located between the two recesses 22 is a thickened extension 23 that receives two screw receptacles 29 embodied as through holes. Screw receptacles 29 transition on the front side into hexagonal screw head receptacles 29.1. FIG. 9 shows the rear side of ejector 20. As is evident from this depiction, rib-like securing extensions 26.1, 26.2 project from ejector 20 on the rear side. Securing extensions 26.1 and 26.2 are adapted, in terms of their arrangement and dimensioning, to the arrangement and shape of receptacles 37.1 and 37.2 of carrier 30. Screw receptacles 29 are guided through securing extension 26.1. DE 10 2009 014 730.6 6 As is further evident from FIG. 9, stiffening ribs 27 are arranged in the rear-side corner regions of ejector 20. Said ribs are connected to the horizontal securing extension 26, thus yielding optimum energy dissipation. In order to mount ejector 20, it is placed with its rear side onto support surface 37 of carrier 30. Securing extensions 26.1, 26.2 then engage into the corresponding receptacles 37.1, 37.2. This results in a crosswise splining that prevents any displacement of ejector 20 with respect to carrier 30 in the axial and radial direction of milling tube 10. By way of this splined connection, large portions of the forces occurring during tool use can be dissipated. Screw receptacles 29, 36.1 of ejector 20 and of carrier 30 are in alignment, so that mounting screws 24 (see FIGS. 4 and 5) can be inserted through them. The screw head of mounting screws 24 is accommodated in screw head receptacle 29.1, where it is held nonrotatably. Preferably self-locking nuts 28 can be screwed onto mounting screws 24, and ejector 20 can thus be secured on carrier 30. It is chiefly the radially projecting region of ejector 20 that wears during tool use. As is evident from FIGS. 8 and 9, ejector 20 is embodied symmetrically with respect to the center transverse plane. When the wear limit is reached, it can therefore be removed and put back on having been rotated 180 degrees. FIGS. 10 and 11 show a further variant embodiment of an ejector unit according to the present invention. Said unit once again encompasses an ejector 20 and a carrier 30. Ejector 20 again possesses a hollowed conveying surface 21 that faces in the processing direction, the hollow being recessed concavely in a direction opposite to the processing direction. Facing away from conveying surface 21, ejector 20 comprises on its rear-side mounting side 25 a mounting extension 20.1. The latter protrudes in block fashion oppositely to the processing direction. It possesses two screw receptacles that can be arranged in alignment with screw receptacles of carrier 30. DE 10 2009 014 730.6 7 Mounting screws 24 can be passed through the screw receptacles, and nuts 28 can be threaded onto their threaded studs. Ejector 20 is thereby fixedly clamped, in particular braced, against a support surface 37 of carrier 30. As is evident from the drawings, ejector 20 is equipped in the region of mounting side 25 with cutouts 20.2. Upper cutout 20.2 receives the heads of mounting screws 24 and thus protects them, behind conveying surface 21, from the abrasive attack of the removed material. Lower cutout 20.2 extends in skirt fashion over carrier 30 and protects it there. Ejector 20 is symmetrical with respect to the central transverse axis, and can therefore be mounted reversibly in two operating positions, rotated 180 degrees, on carrier 30. DE 10 2009 014 730.6 8

Claims

1. An ejector (20), in particular for road milling machines, comprising: - a conveying surface (21) directed in a feed direction (V); - a rear side facing away from the conveying surface (21), the rear side forming a mounting side (25) having at least one support surface; - a mounting receptacle, in particular a screw receptacle and/or a mounting extension.

2. The ejector according to Claim 1, wherein the conveying surface (21) of the ejector (20) is arranged substantially transversely to the feed direction (V) of the ejector unit, and is at least locally hollowed in a direction opposite to the tool feed direction, in particular is embodied in recessed fashion in scoop-like fashion.

3. The ejector according to Claim 1, wherein the conveying surface (21) is at least locally embodied in concave fashion or is assembled, in the hollowed region, from line segments and/or curve segments.

4. The ejector according to one of Claims 1 to 3, wherein one or more depressions (21.1, 22) are introduced into the conveying surface (21).

5. The ejector according to one of Claims 1 to 4, wherein at least one screw receptacle (29) is used as a mounting receptacle; and the screw receptacle (29) opens, toward the front side of the ejector (20), into a screw head receptacle (29.1) in which a screw head of a mounting screw (24) is at least locally nonrotatably receivable.

6. The ejector according to one of Claims 1 to 5, wherein DE 10 2009 014 730.6 9 at least one protruding securing extension (26.1, 26.2), or a recessed securing receptacle, is arranged on the side facing away from the conveying surface (21).

7. The ejector according to Claim 6, wherein by means of the at least one securing extension (26.1, 26.2) or the at least one securing receptacle (29), any displacement of the ejector in a plane transverse to the feed direction (V) can be limited in positively engaged fashion.

8. The ejector according to one of Claims 1 to 7, wherein one or more shaped-on stiffening ribs (27) are arranged on the rear side facing away from the conveying surface (21).

9. The ejector according to one of Claims 6 to 8, wherein the screw receptacle (29) is guided through the securing extension (26.2) or securing receptacle.

10. The ejector according to one of Claims 1 to 9, wherein the mounting side (25) is embodied in such a way that the ejector is installable in different operating positions.

11. The ejector according to one of Claims 1 to 10, wherein the securing extension (26.2) or securing receptacle is embodied in mirror symmetrical fashion.

12. The ejector according to one of Claims 1 to 11, wherein the mounting side (25) comprises a convex or crowned, for example spherical, mounting portion for contact against a concave or hollowed receiving portion of a carrier (30).

13. The ejector according to one of Claims 1 to 12, wherein DE 10 2009 014 730.6 10 at least one wear protection element, made of a material more wear-resistant than the conveying surface (21), is arranged in the region of the conveying surface (21).

14. The ejector according to one of Claims 1 to 13, wherein the wear protection element is constituted by a hard-material element or a hardfacing. DE 102009014730.6