The invention relates to a scraper bar for the scraper blade of a road milling machine.
Road milling machines are used in road construction. Their purpose is to remove existing road pavements. The road milling machine possesses, for that purpose, a milling drum that is accommodated in a milling drum housing. The milling drum is populated on its surface with a plurality of milling bits. The milling bits are usually installed in upper parts of quick-change bit holder systems. The quick-change bit holder systems possess a lower part that is mounted on the surface of the milling drum. The upper part is joined replaceably to the lower part. The milling bit is mounted in a receptacle of the upper part.
A rotational motion can be imparted to the milling drum in the milling drum housing. When the drum is set onto the roadway surface, the milling bits mill off the roadway pavement. The milled-off material must be transported out of the milling drum housing. An extraction belt is attached for that purpose to the milling drum housing. The milled material is delivered from the milling drum to this extraction belt. The milling drum housing is usually shielded on the side in order to prevent milled material from getting into the surrounding area. Side panels, which extend in the travel direction of the milling drum and are adjustable in height, are usually used for this. The milling drum housing is closed off at the front by a front panel. The scraper blade recited initially is arranged in the region of the rear side of the milling drum housing. The scraper blade is usually embodied in the form of a panel element, and possesses an underside facing toward the roadway surface. One or several scraper bars are arranged in the region of that underside. The scraper blade is adjustable in height via a drive system. The correlation with the roadway surface can thereby be set exactly. As already mentioned above, the milling bits mill off the roadway pavement during milling operation. The result of this is usually a milled pattern in which mutually parallel grooves extending in the travel direction are cut into the roadway surface. Adjacently to the milling drum, the scraper blade having the scraper bars is set onto the surface of the roadway, such that the scraper bars sit on the milled structure. As a result of the advance motion of the road milling machine, the scraper blade is moved along with the road milling machine, and the scraper blade with its scraper bars slides over the milled structure.
The purpose of the scraper blade is on the one hand to prevent milled material from being ejected from the rear side of the milling drum housing. A further purpose is to smooth out any irregularities in the milled structure using the scraper blade, thus producing a milled plane that is as uniform as possible. For example, it is conceivable for a milling bit of the milling drum to sustain damage, in particular to break, during milling operation. This produces a gap in the region of the milling drum. Roadway pavement is then not removed at that gap, so that the desired milled channel in the roadway pavement is not produced but instead an elevation remains in the milled structure. The scraper blade is then capable of breaking up that elevation in order to rework the desired flat milled structure.
Scraper bars are known in the existing art. A cuboidal carrier is usually used for this purpose. The carrier possesses a front working surface and a rearward installation surface. Metal carbide plates are mounted in the region of the lower edge, facing toward the roadway surface, of the working surface. The metal carbide plates are serially arranged and form a lower cutting edge. The scraper bar can be set with the cutting edge onto the roadway surface.
The object of the invention is to furnish a scraper bar of the kind recited initially with which an improved working result can be achieved.
This object is achieved with a scraper bar that comprises a carrier having a front side and a rearward installation surface. The carrier possesses a cutting-element receptacle on or in which cutting elements are held, serially arranged along a longitudinal axis extending in a width direction of the carrier. The cutting elements comprise a cutting edge that transitions indirectly or directly into a rake surface. At least for some of the cutting elements, according to the present invention the cutting edge is set at an angle, at least locally not parallel to the longitudinal axis.
As previously, the scraper bar can be securely braced with its rearward installation surface against the scraper blade. The scraper bar is then moved during milling operation in an advance direction together with the scraper blade, the advance direction extending transversely to the longitudinal axis. The cutting edges are then consequently also set transversely to the advance direction. If an irregularity in the milled structure then occurs, the cutting edge encounters it obliquely, leading to a better cutting result. In particular, the cutting edge then transfers to the irregularity a force component that is at an angle to the advance direction which corresponds to the setting angle of the cutting edge. What therefore results is a force component acting on the irregularity not only in the advance direction but also transversely to the advance direction. The result is that, in conjunction with the advance motion of the road milling machine, less cutting force is necessary, since the irregularity structures (usually extending in a longitudinal direction) are broken away to the side. This not only reduces the required tractive force but also acts to reduce stress on the cutting elements, thereby extending their service life. The cutting elements are preferably made of a hard material, for example of metal carbide or a ceramic material. They can in particular be joined intermaterially to the carrier; particularly preferably, it is conceivable to use cutting elements made of metal carbide which are soldered to the carrier.
According to a preferred variant embodiment of the invention, provision can be made that at least some of the cutting elements have two cutting edges that are at an angle to one another and are set respectively at an angle to the longitudinal axis. A zigzag-shaped cutting edge can thus be implemented on the scraper bar using cutting elements of simple configuration. Provision can be made in this context in particular that the cutting element comprises two limbs that are at an angle to one another; and that each of the limbs comprises a respective cutting edge. The limbs set with respect to one another can be braced at their rear side on carrier surfaces that are at an angle to one another which corresponds to the setting angle of the limbs. It is thereby possible to position the cutting elements on the carrier in simple and accurately fitting fashion. This has advantages in the context of automated production of the scraper bar.
According to a conceivable inventive alternative, provision can be made that at least some of the cutting elements comprise a secondary cutting edge that extends transversely to the cutting edge or edges of the cutting element. Irregularities that have a comparatively larger extent transversely to the advance direction of the road milling machine can thereby, in particular, be effectively detached from the roadway surface.
A variant of the invention can be such that at least some of the cutting elements comprise abutment surfaces, the cutting elements being serially arranged in the region of their abutment surfaces; and that the cutting edge of the cutting elements extends in the region between the abutment surfaces and preferably is guided at the ends of the cutting edges as far as the abutment surfaces. By way of the abutment surfaces, the cutting elements can be serially arranged in accurately fitting fashion in consideration of production-related tolerances or with interposition of an intermaterial joining layer, for example a solder join. Exact alignment of the cutting elements with respect to the carrier thereby becomes easily possible. If the cutting edges are guided as far as the abutment surfaces it is then possible to configure, in a longitudinal direction, an uninterrupted or approximately uninterrupted continuous cutting edge on the scraper bar.
A further variant of the invention can be characterized in that at least some of the cutting elements comprise two rake surfaces that adjoin one another indirectly or directly at a respective cutting edge; and that the rake surfaces are at a roof-shaped angle to one another. This feature, too, results in an improved cutting effect for the scraper bar. The material that is removed can be discharged on both sides via the two rake surfaces.
According to the present invention, the cutting elements can be serially arranged in the cutting-element receptacle in such a way that the cutting edges and/or the rake surfaces form a wave-shaped, zigzag-shaped, or sawtooth-shaped structure. Wave-shaped and zigzag-shaped structures result in a cutting edge having a wear-optimized configuration. A sawtooth-shaped structure forms a breakage-resistant cutting edge.
It has been found that particularly good cutting results can be achieved according to the present invention when provision is made that the cutting edges are set in the angle range between 2° and 28°. Particularly good results when processing road pavements made of concrete can be achieved when the edges are set with respect to the longitudinal axis in the angle range between 10° and 20°.
A further improvement in wear behavior for the scraper bar can be achieved by the fact that the carrier comprises at the bottom, adjacently to the cutting elements (30), an adjoining surface that extends in set-back fashion with respect to the cutting edges in order to form a flank surface; and that one or more skid runners made of a hard material are arranged in the region of the adjoining surface. In the interest of simple manufacture, provision can be made in this context in particular that one or several receptacles, in which the skid runner is/are at least partly received, is/are recessed into the adjoining surface. It is then furthermore also possible, for example, to configure the receptacles in such a way that the skid runners are braced in positively engaging fashion oppositely to the advance direction so that a strength-optimized conformation can be achieved.
One conceivable variant of the invention is such that the cutting-element receptacle of the carrier comprises several elevations that engage into depressions of the cutting elements; or that the cutting-element receptacle of the carrier comprises several depressions that engage into elevations of the cutting elements. The cutting element can be positioned and aligned at the elevation or depression for installation purposes. Provision can be made here in particular that the cutting-element receptacle is assembled at least locally from sub-receptacles; and that each sub-receptacle comprises at least one elevation or depression. For example, one cutting element can be inserted in accurately fitting fashion in each sub-receptacle. In addition, a positively engaging join can be produced, by way of the elevations or depressions, between the cutting element and the carrier transversely to the longitudinal axis or transversely to the advance direction of the road milling machine; this results in improved bracing. Alternatively, however, it is also conceivable for the cutting-element receptacle to comprise a flat placement surface that extends along the longitudinal axis; and for the cutting elements to be braced on that placement surface through the intermediary of a joining material, in particular a solder material.
In order to allow the scraper bar to be aligned precisely on the scraper blade in simple fashion, provision can be made that the carrier comprises an extension that projects rearward beyond the rear-side installation surface, such that the installation surface and a support surface of the extension enclose an angle. The scraper bar can be positioned and aligned, with its support surface and the rearward installation surface, on corresponding counterpart surfaces of the scraper blade. The rearward extension furthermore offers the possibility of receiving wear protection elements. For example, the aforementioned skid runners can be used here, and have sufficient room. It is also conceivable for other wear protection elements made of hard material to be integrated or inserted into the underside, facing toward the roadway pavement, of the rearward extension.
The invention will be explained in further detail below with reference to exemplifying embodiments depicted in the drawings, in which:
The configuration of milling unit 60 is depicted in more detail in
Milling drum housing 64 preferably surrounds milling drum 61 on all sides with the exception of its lower side. Milling unit 60 accordingly possesses two side panels 65 that are arranged in the region of the longitudinal ends of milling drum 61. These side panels 65 extend in the travel direction of road milling machine 50, which corresponds to the advance direction indicated in the drawings. Side panels 65 can be displaced as to height, i.e. vertically, separately from one another via a respective displacement mechanism 67. Side panels 65 comprise runners 66 at the bottom. Side panels 65 are set, with these runners 66, on the surface of the roadway during milling operation.
Arranged in front of milling drum 61 in the travel direction is a front panel of milling drum housing 64, which panel comprises a passage. A physical connection between receiving belt 56 and milling drum 61 is created via the passage. Milling drum housing 64 is closed off at the top by a top panel. A rear panel is arranged at the rear. A scraper blade 68 is arranged at the lower end of the rear panel. Scraper blade 68 comprises a lower horizontal edge that proceeds, in
During milling operation, milling drum 61 is set onto the surface of the roadway that is to be worked. This is done by displacing lifting columns 54; milling drum 61 then rests with its lower side on the roadway surface. When a rotational motion is then imparted to milling drum 61, it mills off the surface of the roadway using milling bits 63. Quick-change bit holder systems 62 are positioned in the form of clearing and loading helices on the surface of milling drum 61. The milled material is transported by these clearing and loading helices to a predetermined location on milling drum 61, for example to the center of the milling drum, where ejectors of milling drum 61 are arranged. These throw the milled material onto receiving belt 56 so that it can be transported out of the working region. Scraper blade 68 does not, however, sit directly with its lower edge 68.1 on the roadway surface; instead, scraper bars 20—different variants of which are shown in
Scraper bars 20 have a carrier 10. The latter can be constituted, for example, from a steel material. Carrier 10 can be embodied, for example, as a forged part as shown in
As also shown in
Be it noted at this juncture that the configuration features of carrier 10 explained above with reference to
Cutting elements 30 can be mounted on cutting-element receptacle 13. Cutting elements 30 are depicted in more detail in
Cutting elements 30 can be mounted on sub-receptacles 13.1 of cutting-element receptacle 13 through the intermediary of an intermaterial join, for example solder material or adhesive material. For that purpose, cutting elements 30 are placed with their limbs 33 onto support surfaces 13.2, 13.3 of cutting-element receptacle 13. Those sides of cutting element 30 which are located opposite flank surfaces 31 are pushed against wall 14. Exact positioning and alignment of cutting elements 30 is thereby achieved. Flank surface 31 preferably transitions flush into adjoining surface 16. Cutting elements 30 are serially arranged along longitudinal axis L, and abutment surfaces 34 of the adjacent cutting elements 30 abut against one another. Abutment surfaces 34 do not need to meet one another directly. It is instead preferably also conceivable for intermaterial joins, for example a solder join or an adhesive join, to be arranged between abutment surfaces 34. A corner cutting element 40 can be inserted into corner receptacle 15. Corner cutting element 40 is shown in
With the variant embodiment according to
As
Skid runners 70 that are inserted into the underside of carrier 10 are also used in the exemplifying embodiment according to
Scraper bars 20 described above can be installed on lower edge 68.1 of a scraper blade 68, as has been described above. Several scraper bars 20 are installed next to one another in order to populate lower edge 68.1 at least in part. It is conceivable for physically identical scraper bars 20 always to be installed next to one another on scraper blade 68. It is also possible for scraper bars 20 having corner cutting elements 40 to be installed at the longitudinal ends of scraper blade 68.
Number | Date | Country | Kind |
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10 2017 116 757 | Jul 2017 | DE | national |
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Number | Date | Country |
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Entry |
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English language machine translation of Betek, German Patent Publication No. DE 202010008045 U1, published Jan. 5, 2012 (7 pages) (Year: 2012). |
Office action dated Mar. 9, 2018 in corresponding German patent application Serial No. 10 2017 116 757.9, 8 pages (not prior art). |
Number | Date | Country | |
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20190055701 A1 | Feb 2019 | US |