Vibratory finishing machine for road asphalting

Abstract: The finding realizes a self-propelled vibratory finishing machine (1) for asphalting road surfaces (5) comprising a frame (2) supporting storage means (4) and distribution of the bitumen aggregate (B) to be deposited on the surfaces (5), pressing means (6) the bitumen aggregate deposited (B) and flat elements (10) scraping along the surface (5) being asphalted, set on the sides of the machine (1), connected to said pressing means (6) and vertically mobile with respect to the pressing means (6). The machine (1) comprises means of detection (11) of the thickness (12) of bitumen aggregate (B) deposited.

Description: This invention relates to a vibratory finishing machine used for asphalting roads especially suited for maintaining a constant thickness of the layer of asphalt deposited and compacted by the machine itself. It is known that asphalting work on roads often uses self-propelled machines, called vibratory compactors, which fundamentally consist of a frame, shaped to provide a driver's cab and housing the machine's traction means. The frame also supports a mobile, walled bin containing the hot bitumen aggregate that, retrieved by a conveyor belt, is deposited on the surface being asphalted by the action of a pair of worm screws standing side by side, set crossways to the machine's direction of travel and made to rotate by a mechanical transmission unit. While the bitumen aggregate is still hot, it is uniformly distributed over the road coarse and then compacted by means of a device, called a "vibratory compactor", set behind the worm screws with respect to the machine's direction of travel. The vibratory compactor is connected to the end of a heavy-duty mechanical arm pivoted on the machine frame and hydraulic jacks on its other end suited to raising and lowering the vibratory compactor according to work needs. More precisely, the vibratory compactor comprises a plowshare element basically consisting of a heavy-duty plate bent to form an L-shape set crossways to the machine's direction of travel, with the longer wing nearly perpendicular to the road coarse and the shorter wing parallel to the actual coarse. The plowshare spreads the bitumen aggregate distributed by the worm screws preparing it for compacting by a vertically oscillating beam, which is also set crossways to the machine's direction of travel and made to vibrate by a device connected to it. Normally, vibratory finishing machines have, next to the two sides of the vibratory compactor device, vertically sliding flat elements that slide and/or scrape along the floor being asphalted and are used to retain the material deposited within the work area of the vibratory compactor. As is known, the thickness of the asphalt layer depends on the machine's travel speed and on the thickness of asphalt deposited that is controlled by adjusting the hydraulic jacks that raise/lower a rear heavy-duty arm that supports the plowshare-vibratory elements. However, it may arise for various reasons that the thickness of asphalt layer deposited and compacted undergoes variations during the travel of the vibratory finishing machine, causing unwanted waviness in the runway of the finished road coarse. To overcome this inconvenience, known technology has fitted the machine with special electronic type, automatic level indicators that, detecting these variations, controls the hydraulic jacks to restore the thickness to the set reference level. These automatic level indicators are however both complex and costly, and what's more they are also delicate, considering the harsh work conditions and the consequent risks of wear and tear they undergo during the asphalting process. EP 0 495 171 A1 discloses a paver in which the thickness of a laid bitumen aggregate is controlled via certain reference parameters, i.e. the height of the screed from the ground level of the road surface to be asphalted, to provide smooth surfaces in cases when the paver is stopped for a short interval or the work on the street is interrupted for a day. EP 0 495 171 A1 does not refer to any direct measurement of the thickness of the laid bitumen aggregate, but it teaches the preselection of one of the parameters influencing said thickness. US-A-5,344,254 is directed to a paving apparatus comprising an edger, said edger being joumaled on a screed by a hinge. The edger is not freely movable in a vertical direction with respect to the screed, but it is adjusted to a preset height. Further, a wear plate of the edger floats on the paving material so that the edger acts as an additional screed. Thus, the edger is not scraping on the road surface to be asphalted. US-A-3,638,540 discloses a paving machine having a tractor and a screed means. A photoelectric sensing means measures a vertical deviation from a reference plane and produces a signal that is amplified to actuate an electrically operated valve means actuating a power means that controls the grade of one side of the screed. A second photoelectric sensing means measures the vertical movement of the opposite side relative to the first side, and produces a signal that is amplified to control a second electrically operated valve means that controls a second power means and said opposite side of the screed, thereby maintaining the screed at a constant slope. The problem of monitoring the thickness of the laid bitumen aggregate is not addressed. The present device will remedy the aforesaid inconveniences. An object of the present invention is to produce a vibratory finishing machine that will detect the tendency to variation in thickness of the asphalt coarse deposited, with enough time to correct it. An additional object is to detect the tendency to have various thicknesses and to ensure that prompt corrective actions are made with means that have the benefits of being simple, inexpensive and resistant to the risks of wear and tear. The objectives are achieved by a self-propelled vibratory finishing machine for asphalting road surfaces as set forth in claim 1. Preferred embodiments of the present invention may be gathered from the dependent claims. The objectives described above shall be better explained during the description of a preferred form of execution of the invention, given as a guideline but not a limitation and illustrated in the attached diagrams. Fig. 1 is a side elevation view of the vibratory finishing machine of the present invention; Fig. 2 is a partial side elevation view showing a detail of the detection means of the vibratory finishing machine of Fig. 1; and Fig. 3 is a partial side elevation view showing a detail of the pressing means of a variant of the vibratory finishing machine of Fig. 1. The inventive self-propelled vibratory finishing machine for asphalting road surfaces is illustrated in Fig. 1, where it is generally indicated by number 1 and comprises a frame 2 housing traction means and being shaped to provide a driver's cab 3. The frame 2 also supports the storage means of bitumen aggregate B to be deposited, consisting of a mobile, walled bin 4. The aggregate B, by a suitable means of distribution, preferably consisting of a conveyor belt not illustrated, is deposited over the road surface 5 being asphalted. Pressing means, generally indicated by 6, consisting of a plowshare 7 and a vibrating beam 8 are set crossways to the direction of travel 9 of the machine 1 and allow the bitumen aggregate B previously deposited to be compacted. A pair of flat elements 10 having a primarily longitudinal construction scraping along the surface 5 being asphalted are each connected by the pressing means 6, in relation to which they are vertically mobile, to one side of the machine 1. The invention prescribes that the vibratory finishing machine 1 comprises means of detection 11, as can be seen in detail in Fig. 2 of the thickness 12 of bitumen aggregate B deposited, which comprise first means of reference 13 connected to the flat elements 10 working together with second means of reference preferably consisting of a calibrated rule 14, connected to the pressing means 6. In particular the flat elements 10 are connected to one end of chains 15 having their opposite ends connected to handwheels 16 that allow them to be shortened and lengthened. With regards to the calibrated rule 14, it is mounted on the top edge of the flat element 10 and works together with the first reference means such as a pointer 13 connected to the pressing means 6. According to a variant in execution illustrated in fig. 3, the pointer 13a is connected to the flat element 10 while the calibrated rule 14a is mechanically connected to the pressing means 6. The relative deviation between the first means of reference 13 and second means of reference 14 allow detection of variations in thickness 12 from a pre-set level of bitumen aggregate B deposited. With regards to the compacting elements 6, these are mounted at the ends of a pair of mechanical arms 17 pivoted on journals 18 located behind the frame 2. Each mechanical arm 17 also has a hydraulic jack 19 at the opposite end, as illustrated in detail in Fig. 1, suited to allow the actual pressing means 6 to be raised and lowered, thereby enabling adjustments in thickness 12 of the bitumen aggregate B deposited and compacted. It is also possible to connect proximity devices to the level signalling device or detection means 11 described above which, by an on/off type visual and/or acoustic signal, alert the operator of the tendency to vary the thickness from a set reference level. These devices are readily known and for this reason their detailed description has not been included herein. In practice, the bitumen aggregate B, fed from the bin 4, is deposited over the road course 5 and uniformly distributed on the surface being asphalted by means of a pair of worm screws 30 that can be seen in Fig. 1. The plowshare 7 and vibratory beam 8 then spread and compact the layer of material B previously distributed on the ground. The operator can adjust the handwheels 16 to set each flat element 10 so that the front section 10a is slightly raised from the road surface 5 and the back section 10b scrapes along the actual road surface 5. Variations in thickness of the compacted bitumen aggregate cause the pressing means 6 to rise/lower which draw the pointer 13 with them to thereby signal the variation in thickness on the calibrated rule 14. The operator, who continually follows the machine can thereby view the pointers 13, or be alerted by the acoustic signals. He can therefore promptly adjust the machine's controls to restore the thickness 12 to its required level.

Claims: A self-propelled vibratory machine (1) for asphalting road surfaces (5), comprising: a frame (2), said frame housing traction means and being shaped to provide a driver's cab (3), said frame supporting: storage means (4) which stores and distributes bitumen aggregate (B) to be deposited on said road surfaces (5); pressing means (6) for pressing the bitumen aggregate (B) deposited, said pressing means (6) being arranged transverse to the direction of travel (9) of said machine (1); flat elements (10) that scrape along the surface being asphalted, said flat elements (10) being arranged on the sides of said machine (1), said flat elements (10) being connected to said pressing means (6), and said flat elements (10) being vertically movable with respect to said pressing means (6); and means of detection (11) for detecting the thickness (12) of bitumen aggregate (B) deposited, said detection means (11) being mechanical and having first reference means (13) and second reference means (14), said first reference means (13) being connected to said flat elements (10) and said first reference means (13) mechanically cooperating in conjunction with said second reference means (14), said second reference means (14) being connected to said pressing means (6); wherein said thickness (12) of said bitumen (B) is measured by the relative deviation between said first reference means (13) and said second reference means (14). A vibratory finishing machine according to claim 1, wherein said first reference means is a pointer (13) and said second reference means is a calibrated rule (14). A vibratory finishing machine according to claim 1, wherein said first reference means is a calibrated rule (14) and said second reference means is a pointer (13). A vibratory finishing machine according to claim 1, wherein said means of detection (11) work together with visual signaling devices for signaling the variation in thickness (12) of the bitumen aggregate layer deposited, said visual devices being activated when the relative deviation of said reference means (13, 14) exceeds a pre-set limit. A vibratory finishing machine according to claim 4, wherein said visual signaling devices have light sources generating on/off type signals. A vibratory finishing machine according to claim 1, wherein said means of detection (11) work together with at least one acoustic device for signaling the thickness (12) of the bitumen aggregate layer deposited, said acoustic device being activated when the relative deviation of said reference means (13, 14) exceeds a pre-set limit. A vibratory finishing machine according to claim 6, wherein said acoustic device is a beeper. A vibratory finishing machine according to claim 1, wherein said flat elements (10) are connected to said pressing means (6) by a chain (15) that is connected at one end to a handwheel (16). A self-propelled vibratory machine according to any of the preceding claims, wherein said means of detection (11) are mechanical detection means (11) for detecting the thickness (12) of bitumen aggregate (B) deposited, said mechanical detection means (11) having first reference means (13) that is mechanical, and second reference means (14) that is mechanical, said first reference means (13) mechanically cooperating in conjunction with said second reference means (14), wherein at least one of said reference means (14) displays units of measurement and a portion of said other reference means (13) is located adjacent said units of measurement so as to indicate one of said units of measurement; wherein said thickness (12) of said bitumen aggregate (B) is determined by comparing a pre-set level of bitumen aggregate with the indicated unit of measurement.

Inventors: BITELLI ROMOLO, BITELLI, ROMOLO
Applicants: BITELLI SPA, BITELLI S.P.A.
Application year: 2000
Main classification: E01C19
IPC codes: E01C19