AU2014277833B2 - Ejector unit for a road milling machine or the like - Google Patents

Abstract

The invention relates to an ejector unit, in particular for a road milling machine, having an ejector that is replaceably mounted on a carrier. 6049744_1 (GHMatters) P87927.AU.1 ANDREAS 12 13 20 1 v313 3 )101 Fi.I 13______

Description

2014277833 01 Sep 2016

EJECTOR UNIT FOR A ROAD MILLING MACHINE OR THE LIKE

The invention relates to an ejector unit, in particular for a road milling machine, having an ejector that comprises a conveying surface.

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 A1. 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 would be advantageous if the present invention would provide an improved ejector that enables simple machine maintenance. 1 8154431_1 (GHMatters) P87927.AU.1 2014277833 01 Sep 2016

The present invention provides in a first aspect an ejector unit, such as for a road milling machine or the like, the ejector unit comprising an ejector that has a conveying surface, the ejector being arranged to be replaceably mountable on a carrier. .In accordance therewith, the ejector is replaceably mountable on a carrying part. This results in a tool system in which the ejector can be easily and quickly replaced in the event of damage or wear. Work is thereby considerably simplified, and machine downtimes can be considerably reduced.

According to a preferred variant embodiment of the invention, provision may be made that the ejector is mountable on the carrier in at least two different operating positions.

The ejectors may be used in one operating position until the wear limit is reached. The ejector is then brought into the next operating position and may then be used further. This results in a service life for the ejector that is considerably extended as compared with usual ejectors.

Provision may be made in this context that in order to change the operating positions, the ejector is installed having been rotated 180 degrees. What is exploited here is the recognition that the ejector wears substantially on its region facing away from the milling tube. Once the wear state has been reached there, the ejector is detached and is reinstalled having been rotated 180 degrees. The ejector service life can thereby be considerably extended, ideally in fact doubled. In order to lose as little time as possible when changing the operating positions of the ejector, and to make installation unequivocal, provision may be made that the ejector and the holder form a mechanical interface that enables reversible installation of the ejector.

Secure mounting of the ejector on the carrier part results from the fact that the ejector comprises a mounting receptacle and/or a mounting extension, and that the ejector is 2 8154431.1 (GHMallers) P87927.AU.1 2014277833 01 Sep 2016 connected indirectly or directly to the carrier by means of one or more mounting elements.

One conceivable inventive alternative is such that the ejector is braced in planar fashion on a support surface of the carrier by means of a mounting side, that the ejector comprises a securing extension and/or a securing receptacle, and that the securing extension engages into a securing receptacle of the carrier and/or a securing extension of the carrier engages into the securing receptacle of the ejector. The mutually interengaging connection of the securing extension and securing receptacle creates a positively engaged connection through which processing forces can be dissipated in load-optimized fashion. This becomes possible in particular when provision is made that the positively engaged connection impedes or blocks any offset of the ejector with respect to the carrier transversely to the feed direction.

In the context of the ejector unit according to an embodiment of the present invention, provision may be made that the carrier comprises a mounting foot onto which is shaped a support part, and that the mounting foot comprises a mounting surface extending substantially in the feed direction. By means of the mounting surface, the carrier may be positioned correctly on the milling tube and mounted thereon, in particular welded on.

The carrier may be produced in simple fashion as an economical component.

If provision is made that the mounting foot is widened with respect to the support part in or oppositely to the feed direction, a load-optimized geometry then results. The transition region between the support part and the mounting foot is exposed to large bending stresses in the tool insert. Widening decreases the material stresses at that point. 3 8154431_1 (GHMatters) P87927.AU.1 2014277833 01 Sep 2016

According to a preferred variant embodiment of the invention, provision may be made that the ejector comprises a conveying surface that is arranged substantially transversely to the feed direction of the ejector unit, and is embodied in hollowed fashion, in particular recessed in scoop-like fashion, at least locally in a direction opposite to the tool feed direction. This hollowed conformation enables a 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 may become deposited in the depressions. A "natural" wear protection layer forms there.

According a variant of the invention, provision may 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.

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 may then be designed with little material outlay. A preferred variant of the invention is such that the mounting side comprises a convex mounting portion for contact against a concave receiving portion of a carrier. This results in a surface connection between the carrier and the ejector through which processing forces may be reliably dissipated even in the event of asymmetrical force application to the conveying surface. 4 8154431_1 (GHMatters) P87927.AU.1 2014277833 01 Sep 2016

If provision is made that the carrier holds the ejector in such a way that the conveying surface extends with a slight inclination with respect to the feed direction, the discharge performance may then be optimized. It has been shown that particularly good performance is achieved with an inclination setting in an angle range of +/- 20 degrees. Surprisingly, an optimum is obtained at a negative inclination angle, specifically at an inclination of 5 to 15 degrees opposite to the feed direction.

An additional improvement in ejector 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; provision may be made in particular that the wear protection element is constituted by a hard-material element or by a hardfacing.

The present invention provides in a second aspect a unit of a road milling machine or the like comprising the ejector unit according to the first aspect of the present invention.

The invention will be further explained below with reference to an exemplifying embodiment 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; 5 8154431J (GHMatters) P87927.AU.1 2014277833 01 Sep 2016 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. 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. 6 8154431_1 (GHMallers) P87927.AU.1 2014277833 01 Sep 2016 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 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. 7 8154431_1 (GHMatters) P87927.AU.1 2014277833 01 Sep 2016

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.

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 δ 8154431_1 (GHMatters) P87927.AU.1 2014277833 01 Sep 2016 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.

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 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. 9 8154431.1 (GHMatters) P87927.AU.1

Claims (19)

1. An ejector unit for a surface miner or road milling machine or the like, the ejector unit comprising: an ejector that is arranged for mounting on a carrier on a milling drum of the surface miner or road milling machine or the like, the ejector comprising: a conveying surface; an ejector mounting surface facing in a direction substantially opposite to the conveying surface, the ejector mounting surface having at least one mounting extension being shaped such that, when the ejector is mounted on a complementary shaped carrier, the at least one mounting extension engages with the carrier whereby the ejector is supported against motion in a radial direction relative to an axis of the milling drum; wherein the ejector is arranged to be replaceably mountable on the carrier in at least two operating positions.

2. The ejector unit of claim 1 comprising the carrier.

3. The ejector unit of claim 1 or 2 wherein the at least one mounting extension extends across a portion of the ejector mounting surface.

4. The ejector unit of any one of the preceding claims wherein the at least one mounting extension is a first rib that extends in use along an axis of the milling drum.

5. The ejector unit of claim 4 wherein the ejector mounting surface has a further mounting extension, the further mounting extension being provided in the form of a further rib, the further rib being in use oriented in a direction that is non-parallel to the first rib such that the further rib crosses the rib that extends in use along the axis of the milling drum.

6. The ejector unit of any one of the preceding claims, wherein, in order to change the operating positions, the ejector is installable having been rotated by 180 degrees.

7. The ejector unit of any one of the preceding claims, wherein the ejector is arranged to form a mechanical interface with a support surface of the carrier such that reversible installation of the ejector is enabled.

8. The ejector unit of any one of the preceding claims, wherein the ejector is arranged for direct or indirect connection to the carrier by means of one or more mounting elements, such as a mounting screw on a mounting receptacle of the carrier.

9. The ejector unit according to any one of the preceding claims, wherein the ejector is in use braced in planar fashion on a support surface of the carrier by means of a mounting side; and wherein the ejector comprises at least one of a securing extension and a securing receptacle; and wherein the securing extension engages into at least one of: a securing receptacle of the carrier and the securing receptacle of the ejector.

10. The ejector unit of any one of the preceding claims, wherein the conveying surface of the ejector is arranged substantially transversely to the feed direction of the ejector unit, and is embodied in hollowed fashion, such as in a recessed in scoop-like fashion, at least locally in a direction opposite to the tool feed direction.

11. The ejector unit of Claim 10, wherein the conveying surface is at least locally embodied in concave fashion or is assembled, in the hollowed region, from at least one of: line segments and curve segments.

12. The ejector unit of any one of the preceding claims, wherein one or more depressions are introduced into the conveying surface.

13. The ejector unit according to any one of the preceding claims, wherein at least one screw receptacle is used as a mounting receptacle; and wherein the screw receptacle opens, toward the conveying surface of the ejector, into a screw head receptacle in which a screw head of a mounting screw is at least locally nonrotatably receivable.

14. The ejector unit of any one of the preceding claims, wherein the ejector mounting surface is convex and wherein the carrier has a corresponding mounting surface.

15. The ejector unit of any one of the preceding claims, wherein 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 of the ejector.

16. The ejector unit of claim 15, wherein the wear protection element is constituted by a hard-material element or by a hardfacing.

17. The ejector unit of any one of claim 2 or any one of claims 3 to 16 when dependent on claim 2, wherein in use the carrier holds the ejector in such a way that the conveying surface is inclined with respect to the processing direction, such as at an angle (a) of +/- 20 degrees about its radial orientation.

18. The ejector unit of claim 17, wherein the angle (a) extends negatively opposite to the processing direction in an angle range from -5 degrees to -20 degrees.

19. A unit for a road milling machine or the like comprising the ejector unit according to any one of the preceding claims.