US3841777A - Paving vibratory finishing machine having a device for constant compaction of the deposited layer - Google Patents

Abstract

A road surfacing machine of the full floating type applies road surfacing material and then levels the same. In order to make sure that the density of the surfacing material is uniform despite irregularities in the contour, the machine detects the pressure between a pressor member and the surfacing material. When the pressure decreases, thereby indicating less density, then a screed or the like is raised to increase the quantity of deposited material in that region; and when the pressure increases, the screed or the like is lowered to decrease the quantity of material.

Description

iltiiied States Patent 1 1 Domenighetti 1451 Oct. 15, 1974 PAVING VIBRATORY FINISHING MACHINE HAVING A DEVICE FOR CONSTANT COMPACTION OF THE DEPOSITED LAYER [76] Inventor: Domenico Domenighetti, via Nosetto 6, Bellinzona, Switzerland [22] Filed: May 3, 1972 [21] Appl. No.: 250,063

[30] Foreign Application Priority Data May 5, 1971 Switzerland 6673/71 52 us. c1. 404/84, 404/114 [51] Int. Cl. E01c 19/00 [58] Field oi Search 404/84, 105, 118, 114, 404/106, 117; 172/45 [56] References Cited UNITED STATES PATENTS 2,346,379 4/1944 Jackson 404/114 X 2,351,592 6/1944 Barber... 404/114 2,393,954 2/1946 Baker 404/105 2,491,275 12/1949 Millikin 404/84 2,591,502 4/1952 Bohannan 404/84 2,757,588 8/1956 Pollitz 404/114 2,796,811 6/1957 Barber 404/84 2,922,345 1/1960 Memes 404/84 3,029,715 4/1962 Bowen 404/84 3,053,157 9/1962 Martin 404/1 17 3,111,070 11/1963 Pollitz 404/84 3,142,915 8/1964 Curlctt 172/4.5 3,453,939 7/1969 Pollitz 404/84 3,599,543 8/1971 Kerridgc 404/117 3,678,817 7/1972 Martenson 404/84 X Primary Examiner-Nile C. Byers, Jr. Attorney, Agent, or FirmYoung and Thompson [57] ABSTRACT A road surfacing machine of the full floating type applies road surfacing material and then levels the same. In order to make sure that the density of the surfacing material is uniform despite irregularities in the contour, the machine detects the pressure between a pressor member and the surfacing material. When the pressure decreases, thereby indicating less density, then a screed or the like is raised to increase the quantity of deposited material in that region; and when the pressure increases, the screed or the like is lowered to decrease the quantityof material.

' 4 Claims, 6 Drawing Figures PATENTEDBBT 1 51924 srwanrs PAVING VIBRATORY FINISHING MACHINE HAVING A DEVICE FOR CONSTANT COMPACTION OF THE DEPOSITED LAYER So-called finishing machines are usually used for laying layers of materials for paving roads, airports, etc.

The materials to be laid (generally bituminous, cement conglomerates, or mixed with other binders, stabilized earths or the like) must be finished off to form a quite levelled and possibly quite compacted layer.

To attain the latter object, the finishing machines are provided with vibrating and/or beating members and therefor are referred to as vibratory finishing machines. Depending on the principle by which such vibratory finishing machines provide for removing or minimizing any unevennesses (corrugations) preexistent in the surface on which the material is being laid, such machines can be divided into two general classes, namely machines provided with a semi-floating levelling-compacting member and machines provided with a full floating levelling-compacting member. It will be readily understood that a constant compaction by both systems could not be hitherto assured in connection with a corrugation pre-existent in the bearing surface of the layer and this even when the final surface of the finished layer was perfectly levelled after the passage of the vibratory finishing machine.

In fact in already known vibratory finishing machines the compacting action developed by the machine is not automatically varied as a function of the thickness which, moment by moment, is assumed by the laid layer according to the depressions or humps which the machine encounters during its forward motion, and this because the manual adjustments are only carried out from time to time in order to adapt the compacting action of the machine to its speed of advancement, or to the designed thickness of the layer to be laid down. These adjustments do not however take into account pre-existing undulations (depressions and/or humps) on the road surface underneath the spread layer.

It is thus evident that with the traditional types of finishers it is possible to obtain a perfectly level layer, but that this layers compactness is not homogeneous, that is constant, either longitudinally or transversely.

This lack of homogeneity of compactness means that in practice the finisher leaves behind a perfectly level layer but there are areas where the material is still relatively soft, and other areas, instead, in which the material is hardened and compacted because of greater thickening.

This irregular distribution of the compactness is very undesirable when one considers that immediately after the passage of a vibratory finishing machine, rollers, or other compactor means must be used, and that these cause subsidings or sinkings of the soft areas which are less compact, the consequence of this being the forming of new undulations, thus often making illusive and useless the work of levelling, no matter how perfectly the work of depositing the layer has been carried out by the vibratory finishing machine.

The present invention relates to a vibratory finishing machine for the laying of a level layer of material, having devices for the regulation of the compacting energy to be exerted upon the laid material, characterized in that in said machinee are included sensor elements which, moment by moment, perceive the difference of thicknesses of the layer during the laying, which elements transform these measurements into control impulses to the feeding elements of the material and to the compacting elements, in order to regulate their action in proportion to the quantity of material needed, moment by moment, in order to be able to form a layer which is not only level but also uniformly compact in accordance with plan or project.

The vibratory finishing machine which will now be described and represented comprises a movable lower frame carried by feeding means (such as tracks, tired wheels, etc.), and a top floating frame carried by said underlying movable frame by means of actuating mechanisms controlled by an automatic levelling system, holding said floating frame at an attitude parallel to the ultimate design surface. Such an automatic levelling vibratory finishing machine is characterized in that said floating frame is rearwards extended to connect through actuating mechanisms with the underlying operating elements, such as the distributor elements for the material to be laid,'skimmer elements for the layer of laid material and vibratory compactor elements, so as to adjust the position of said operating elements relative to the underlying ground and the operating pressure on the material to be finish off, connecting means (such as mechanical, electromechanical, oleostatic, hydraulic, direct or indirect means) being provided for adjusting the level or height of the several operating elements (such as distributor, skimmer elements and vibratory compactors) relative to the theorical levelling plane and thus for providing the desired correct ulti? mate level and, concurrently constantly maintaining within predetermined values the forces being exerted by said elements (particularly said vibratory compactor element).

In a preferred embodiment, the connection between the distributor, vibratory compactor, skimmer elements and adjustment actuating mechanisms is carried out through shock-isolating mountings and members sensitive to strains, capable of converting the amount of forces being exerted by said elements on the material to be laid into signals causing the operation of the adjustment control on said actuating mechanisms, this adjustment having the purpose of changing the mutual position of said operating elements (distributor, skimmer, vibratory compactor elements) in order to maintain said forces as close as possible to the predetermined exact value.

The appended drawings show fragmentary diagrammatic side views of a full-floating type of vibratory finishing machine, having applied thereto a device for constant compaction of the deposited layer according to the invention. More particularly:

FIG. 1 is a diagrammatic vertical sectional view of a vibratory finishing machine showing the distributor, skimmer and vibratory compactor elements;

FIG. 2 is also a diagrammatic vertical sectional view of a vibratory finishing machine for a constant compaction, comprising a variant in the members sensitive to level changes;

FIG. 3 is again a diagrammatic vertical sectional view showing a further exemplification for the members sensitive to level changes;

FIG. 4 is a vertical sectional view showing a first variant for the adjusting devices;

FIG. 5 is a second variant having a mechanical sensor member; and

FIG. 6 is an enlarged partly cross-sectional view of a fragment of the embodiment of FIG. 5.

Full floating machines of this type, as heretofore known, are exemplified by US. Pats. Nos. 3,142,915, 2,346,379 and 2,393,954.

The vibratory finishing machine, as shown in FIG. 1, comprises a movable frame 1 having a track 2 (which of course could be replaced by a set of tired wheels) mounted thereon and carrying by pistons 3 the floating frame 4 which can be maintained parallel to the final levelling plane by a known automatic levelling apparatus continuously acting on said pistons 3. Said frame 4 is rearwardly extended at 4 and has mounted thereon so as to be vertically (or almost vertically) movable the screws 5 for cross distribution of the material to be finished off, the skimmer element 6 and the vibratory compactor element 7. The relative position of these elements to one another and to the ground is adjustable by actuating mechanisms 8, such as pistons, which are mounted at one end on frame 4' and at the other end on the elements 5, 6 and 7, respectively. Elongation and shortening of said actuators 8 are controlled by a hydraulic system, either manually or automatically.

Instead of a hydraulic piston system and associated oleostatic control system, other actuators can be used, such as mechanical, electrical, pneumatic means and the like, allowing one at any time to select the relative position ofeach of said elements 5, 6 and 7 with respect to frame 4-4.

the vibratory compactor element 7 is vibrated by a vibration energizer 9 and at the bottom has a surface ll) for contacting the material ii to be finished off, this surface being kept at a suitably inclined position by supports or bearings 12 which on one side are anchored to the vibratory compactor element 7 and on the other side to known shock-isolating mountings l3.

The non-vibrating portion of said bearings or mountings 13 is connected to piston 8 with the interposition of a strain sensitive member 14, signalling at any time the force amplitude being transmitted by the vibratory compactor element 7 to frame 4' and vice versa.

Through the oleostatic system, these sensitive members 14, are connected to pistons 8 (actuators) and condition the elongation and shortening thereof, according to whether the forces passing therethrough are higher or lower than certain desirable values.

There are several possible interlocking systems, as well as the automation degree.

A particularly simple embodiment consists of causing said sensitive members 14 to control some variously coloured lamps lighting on the finishing machine drivers dashboard. Should the force passing through the sensitive members 114 be higher than a predetermined value, this would mean that the pressure being exerted by the surface w on material II is too high: thus, the skimmer element 6 (and in the case said screws 5) should be lowered to reduce the amount of material appearing before the vibratory compactor element 7, and vice versa. By this extremely simple and semiautomatic device the operators manual operation is used.

On the other hand, to provide an automatic device, a connection, such as an electric connection, is provided, allowing one to lower or to raise said elements 5 and 6 as soon as the sensitive members 14 signal that a change in the forces passing therethrough has occurred.

A further simplified automatic levelling and constant compaction device according to the present invention is shown, in FIG. 2, where the piston and the front sensitive member of the vibratory element 7 have been omitted, and where the back sensitive member 14 automatically directly controls the raising or lowering of elements 5 and 6.

A third simplified system according to the present invention is that as shown in FIG. 3, wherein the skimmer element 6 has been combined with the vibratory compactor element 7 and therefore, in such a case the signal from the sensitive member 14 is used to raise or to lower the front portion of the vibratory compactor element 7 (in addition to element 5).

A further approach of a rather mechanical character is shown in FIG. 4, wherein the connection between the compactor element 9, 10 and the skimmer element 6 is carried out by means of a vertical chain 15 stretched out between two stationary pulleys l6, 16 mounted on frame 4. This chain 15 vertically slides between the control member 17 of said skimmer element 6 and the control member 18 of said vibratory compactor element 9, so that when member 17 is raised, member 18 is lowered, and vice versa, whereby said skimmer element 6 and vibratory compactor element 9, l0 cooperate according to a predetermined relationship to bring the layer of finished off material 11 to the predetermined level.

A further example of mechanical device enabling one to adjust the layer of material being deposited on the ground is that shown in FIGS. 5 and 6, wherein the frame 4 carrying the support 19 of a roller sensor 19 that projects downward until it contacts the preexistent foundation on which the layer will be laid as formed of the material which is regularly conveyed by the conveyor belt 20 and poured against the screw 5 evenly distributing it on the road surface. The roller sensor 19 follows the profile of the pre-existent surface, on which the layer 11'' is to be laid, which surface in the drawing has depressions and projections. These level differentials are transmitted to the actuator members 8, taking into account the advance with which the roller of said sensor contacts the ground relative to the location where the skimmer and vibratory compactor elements are operating, so that the amount of material being deposited in the depressions (for example 21) is larger than that on the projections (for example 22), and therefore not only a quite horizontal layer as desired is provided, but also a constant compaction of said layer, independently of the corrugations in the original underlying layer 11. The position of the sensor 119 is selected as close as possible to that of the skimmer and vibratory compactor elements 5, 6 and 7 to' minimize the spacing between the level'location of the road foundation and the location where skimming and .vibrocompacting operations occur.

To provide for this, the material is supplied to screw 5 by means of a known conveyor belt 20, conveying it above said screw and leaving a free space below for positioning said sensor 19.

FIG. 6 shows the arrangement of FIG. 5 in greater detail, in which the support 19 is illustrated in section to show therein the electrical winding 19" having an extension of the stem 19" of sensor 19 sliding therein. The quantity of current in the winding 19is accordingly proportional to the length of the extension which is disposed in the winding at any given time and hence for any given contourof the ground and so a signal is transmitted by conventional means (not shown) to actuate the other members as described above.

What is claimed is:

1. An automatic finishing machine for depositing on a substrate a layer having a smooth surface and substantially uniform density throughout the layer, comprising a vehicle, means operatively related to the vehicle for applying a said layer of material to said substrate, said applying means comprising distributing means for said material and strike-off means for levelling the distributed material, means operatively related to the vehicle for applying compacting force to said layer to smooth said layer, and means operatively related to the vehicle and to said compacting means responsive to variations in the pressure between said layer and said compacting means to vary the quantity of material deposited on said substrate inversely as said pressure.

2. A machine as claimed in claim 1, said strike-off means and said means for applying compacting force being integral with'each other.

3. A machine as claimed in claim 1, and a shock absorbing member operatively related to the vehicle between one portion of said compacting means and said vehicle, said strike-off means comprising a screed interconnected with said compacting means by said link means thereby simultaneously to move said compact ing means and screed means in opposite vertical directions.

4. A machine as claimed in claim 1, and a vertical chain extending between two stationary pulleys on said vehicle, said strike-off means comprising screed means connected to one side of said chain for levelling the distributed material, an end of said compacting means being connected to the other side of said chain for opposite vertical movement of said screed means and compacting means relative to each other.

Claims (4)

1. An automatic finishing machine for depositing on a substrate a layer having a smooth surface and substantially uniform density throughout the layer, comprising a vehicle, means operatively related to the vehicle for applying a said layer of material to said substrate, said applying means comprising distributing means for said material and strike-off means for levelling the distributed material, means operatively related to the vehicle for applying compacting force to said layer to smooth said layer, and means operatively related to the vehicle and to said compacting means responsive to variations in the pressure between said layer and said compacting means to vary the quantity of material deposited on said substrate inversely as said pressure.

2. A machine as claimed in claim 1, said strike-off means and said means for applying compacting force being integral with each other.

3. A machine as claimed in claim 1, and a shock absorbing member operatively related to the vehicle between one portion of said compacting means and said vehicle, said strike-off means comprising a screed interconnected with said compacting means by said link means thereby simultaneously to move said compacting means and screed means in opposite vertical directions.

4. A machine as claimed in claim 1, and a vertical chain extending between two stationary pulleys on said vehicle, said strike-off means comprising screed means connected to one side of said chain for levelling the distributed material, an end of said compacting means being connected to the other side of said chain for opposite vertical movement of said screed means and compacting means relative to each other.

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