FR2643095A1 - METHOD AND DEVICE FOR SPREADING A COATING, IN PARTICULAR A ROAD COATING OF BITUMEN - Google Patents

Abstract

In this process, the coating is spread in several successive passes respectively forming several adjacent parallel bands 20, 20 'contiguous with the coating by means of a spreading ramp 110, the transverse offset of which can be varied with respect to a central position. According to the invention, the following steps are carried out: (a) materialization of a first reference plot 10, (b) simultaneously:. forming a coating strip 20 by performing a spreading pass with control of the transverse position of the spreading boom on the first reference plot; and. materialization of a second reference plot 10 'following the transverse movements of the spreading boom; and (c) repeating step (b) as many times as the coating has adjacent bands, the transverse position of the spreading boom being each time slaved to the reference line 10 'materialized during the previous pass with, simultaneously, materialization of a new 10 "reference line for the next pass.

Description

The present invention relates to a method and a device for spreading a

coating, including a

bitumen road surface.

  It applies to the case where, by means of a spreading boom, this coating is spread in several passes, each time forming a strip of the coating ("band" means the portion of the coating formed by the ramp of spreading at each pass, the entire coating consisting of several adjacent parallel strips

  jointives formed in several successive passes).

  it is clear that the method and the device according to the present invention are not limited to the use of a spreading boom, a term traditionally used

  to designate a device for spreading super-sized coatings

ficiels.

  In fact, the present invention extends to the use of any other coating spreading member, for example a sled used for the application of cold-cast asphalt or a paver table used for

implementation of hot mixes.

  As a result, throughout the text of the description

  and claims, the term "spreading boom" will extend

  to all coating spreaders, the placement of which requires at least two joined strips of material

coating.

  -2 - When producing such coatings, the realization of joints between adjacent strips is always delicate, if not random. The quality of these joints is conditioned by an overlap of the bands respecting the rule called "three-thirds", illustrated schematically in Figure 1; In this figure 1, there is shown in elevation (view A) the different jets 1 of bitumen sprayed by the nozzles of the spreading boom. These jets have the shape of flat fans whose plane is slightly inclined with respect to the direction of the ramp (as can be seen in B, which is a plan view corresponding to the view A) so that they do not have

do not disturb each other.

  Depending on the opening angle of the fans, the height of the nozzles is adjusted so that each point of the roadway receives the bitumen sprayed by three adjacent nozzles; the flow of the nozzles is thus adjusted so that

  each projects one-third of the amount needed.

  However, at the edge of the pavement, the marginal zone will receive only the jet of a single nozzle, and the zone

  immediately adjacent will receive only the jet of two nozzles.

  This is illustrated in 2 and 3 on view C, which shows schematically the thickness of the coating spread by the nozzle system configured as illustrated in A and B. The other areas (4 and 5 on view C) will have received bitumen from three different nozzles, and

  will present the desired coating thickness.

  When making the next strip, the spreading will form a coating having the profile shown in the view D: the areas 5 'and 4' corresponding to the covering of three jets will have the desired thickness, while the marginal areas 3 'and 2' will have a thickness of only two-thirds and one-third respectively.

the desired thickness.

  To make a joint of uniform thickness, we see that it will be necessary that the zone 2 'is formed exactly to the right of the zone 3 formed during the previous pass, and that the zone 3' is formed exactly to the right of the zone 2, so

  to respect the "three-thirds" rule.

  it is therefore necessary to guide the spreading ramp transversely so as to follow the edge of the coating strip formed during the previous pass, or following any reference line previously drawn. Until now, this guidance was done manually by an operator visually observing the profile of the strip and remotely controlling the transverse position of the ramp

  in order to best follow this band.

  In practice, this manual control hardly allowed a better tracking accuracy than 100 mm, value of the same order of magnitude as the width x corresponding to the pitch between successive jets and which is typically of the order of

mm also.

  Thus, the joint produced was rarely satisfactory and most often had thicknesses or thickness defects. The quality of the seal obtained was also highly dependent on the skill of the operator, especially in the case of a non-rectilinear course

(turn, etc.).

  The invention proposes a method and a device that overcomes these drawbacks, which makes it possible to overcome inaccuracies and hazards due to the operator, and which makes it possible to reduce the deviation in a very significant manner.

met by manual flying.

  It will thus be seen that the system according to the invention allows a control accuracy of the order of 10 to 20 mm, much greater than the value of 100 mm which is the value

  generally encountered in manual flying.

  For this purpose, the invention proposes a method comprising the following successive steps: (a) materialization of a first reference trace (with eventual simultaneous formation of the first strip of the coating); (b) simultaneously, formation of a coating strip by executing a spreading pass with slaving of the transverse position of the spreading ramp on the first reference trace and materialization of a second reference trace according to the transverse displacements of the spreading ramp; and repetition of step (b) as many times as the coating comprises ajacent bands, the transverse position of the spreading ramp being each time enslaved on the reference pattern materialized during the previous pass with simultaneously materialization a

  new reference path for the next pass.

  Preferably, the coating is formed by successive passes all made in the same direction of longitudinal displacement, the reference pattern materialized in a pass being located on the opposite side of the spreading ramp relative to that of the reference trace read. then

of this same pass.

  The invention also relates to a spreading device for implementing the aforementioned method. This device comprises, in a manner itself known, a spreading ramp for forming a continuous strip of the coating, and means for moving transversely in translation this spreading ramp; this device furthermore comprises, in a characteristic manner of the invention, means for reading a reference trace, means for controlling the means for transverse displacement of the spreading ramp, operating in response to the reading means of a reference plot so as to enslave the position thereof on the reference plot read, and means for materializing another reference plot

Z643095

  -5- spaced transversely relative to the first of a distance equal to the width of a coating strip, these means being integral in translation of the ramp in its

transverse displacement.

  Preferably, the reading means of a reference trace are integral in translation of the ramp in its transverse displacement and deliver to the control means a differential error signal representative of the deviation from the centerline of the trace of

reference.

  Advantageously, the reading means of a reference plot are optical means and the means of materializing a reference plot are means

  printing a narrow luminescent paint ribbon.

  We will now describe an exemplary embodiment of

  the invention, with reference to the appended figures. -

  Figure 1, above, explains the manner in which a coating is made and the difficulties associated with the

formation of a correct seal.

  FIG. 2 is a plan view illustrating the setting

of the process of the invention.

  FIG. 3 is an elevational view of the device of the invention, adapted to a spreading ramp of a type in

himself known.

  FIG. 2 diagrammatically illustrates the formation of two successive adjacent strips 20 and 20 '

a road surface.

  This coating is carried out by a vehicle 100 provided with a spreading ramp 110. This ramp is provided with a series of nozzles configured in the manner described above with respect to FIG. 1, which thus forms a coating strip of which the central region has the desired thickness - 6 (zones 4 and 5 of FIG. 1C) and whose marginal zones 21 and 22 have a lower thickness, in the form of steps (each of this marginal zone

  21 and 22 corresponding to zones 2 and 3 of FIG. 1C).

  At the second passage (lower half of FIG. 2), the vehicle 100 will form in the same way a strip 20 'whose left marginal zone 21' must exactly overlap the right marginal zone 22 of the adjacent strip

  formed during the previous pass.

  In order to ensure the desired accuracy and the automatic control of the transverse position of the ramp 110, the invention provides for adding to the ramp, on one side thereof, a reading system 120 making it possible to follow a path 10 or 10 'materialized during a previous pass and, on the opposite side, a system 130 for materializing a new trace 10' or 10 "intended to allow the piloting of

the ramp during the next pass.

  These reading means 120 and tracing 130 are integral with the ramp. The reading means 120 are means making it possible to enslave the transverse displacement of

  the ramp so as to follow the path 10 continuously.

  Because they are integral with the ramp in its transverse movements, the tracing means 30 will ensure that the trace 10 will follow exactly the profile of the strip 20, regardless of the movements of the vehicle 20,

especially in turns.

  At the next pass (lower half of Figure 2) the reading means 120 will follow the pattern 10 'previously formed, so that the overlap of the marginal areas of the two strips 20 and 20' will be done with all the precision desired. At the same time, a new line 10 "can be formed if another strip is to be spread to the right of the strip." With regard to the first reference pattern 10, this may be done by the vehicle which carries out a first pass exclusively marking, without spreading,

  independently realized by other means.

  7- - It is also conceivable that, for the first pass, the position of the spreading ramp is not enslaved automatically, the driver of the vehicle merely following a border or a line with a mechanical guide such as a guide with chains of known type. Furthermore, it will be noted that, as illustrated in FIG. 2, the reading means 120 are slightly offset inwards in the transverse direction of the ramp, so as to be able to cover the path formed on the ground during the application of FIG. the liner strip thus leaving it

  remain no trace of this marking.

  Conversely, the marking means 130 are deported

  outwards in the transverse direction of the ramp.

  This makes it possible, on the one hand, to compensate for the offset towards the inside of the read head 120 and, on the other hand, to prevent the marking intended for the next pass from being covered by the coating strip being formed or by possible projections of bitumen from

and other of this band.

  Figure 3 shows a detailed realization of the

device of the invention. -

  This is adapted to the control of a ramp 110, itself known, comprising a series of nozzles 111 close together and supplied with bitumen pipes 112 and 113. The ramp 110 is mounted on a telescopic assembly 114, 115 provided means (not shown) for adjusting the height of the ramp position to adjust the rate of recovery of the jets produced by the

different nozzles.

  There is also provided means 140 (for example a pneumatic or hydraulic jack) for transversely displacing the ramp relative to its median position by means of a suitable mechanical system (not shown), for example a sliding assembly or

articulated parallelogram.

  The lateral displacement of the ramp is for example of the order of 150 mm on either side of its central position. According to the invention, one of the ends of the ramp (in the drawing, the left end) is placed with means 120 of

  reading a reference plot 10.

  Advantageously, the reference trace is a narrow luminescent paint ribbon (width of the order of 10 to mm) and the reading means comprise an intense light source 121 and two luminescence detectors 122, 122 configured in differential mounting. These two detectors provide an amplifier 123 with a differential error signal representative of the deviation of the trace 10 from the median position of the reading system; this error signal, which gives the direction of the deviation,

  is in use with a control assembly 150.

  At the other end of the ramp (in the drawing, the right-hand end) are arranged marking means, for example consisting of a spray gun 131

  can project on the ground a narrow 10 'paint ribbon.

  The control unit 150 controls the cylinder 140 so as to slave the transverse offset of the ramp on the marking '0. The correct operation of the servo is assigned to the driver by a witness 151, while another witness 152 indicates an incorrect servo operation, which may be due either to a luminescent paint interrupt, or gap: transversal between the paint tape and the reading system 120 which exceeds the possibilities of the servo.

Claims (7)

  A method for spreading a coating, in particular a bitumen road surface, in several successive passes respectively forming a plurality of adjacent contiguous adjacent strips (20, 20 ') of the coating by means of a spreading ramp (110) which can be varied the transverse offset with respect to a median position, characterized by the following successive steps (a) materialization of a first reference trace (10), (b) simultaneously: * formation of a coating strip (20) by execution of a spreading pass with servocontrol of the transverse position of the spreading ramp on the first reference run, and * materialization of a second reference run (10 ') according to the transverse displacements of the spreading ramp, and (c) repeating step (b) as many times as the coating has adjoining strips, the transverse position of the spreading ramp being each time slaved to the reference pattern ence (10 ') materialized during the previous pass with, at the same time, materialization of a new   reference (10 ") for the next pass.   2. The method of claim 1, wherein in step (a) the first form is simultaneously formed. coating tape.   3. The method of claim 1 or 2, wherein the coating is formed by successive passes all made in the same direction of longitudinal displacement, the reference pattern (10 ") materialized during a pass being located on the opposite side of the spreading ramp compared to that of the reference trace (10 ') read during this same pass. - 10 -   4. A spreading device for the implementation of the   method according to one of the preceding claims,   comprising: - a spreading ramp (110) making it possible to form a continuous strip of the coating, and - means (140) for displacing this spreading ramp transversely, characterized in that it further comprises: means (120) for reading a reference trace (10)   means (150) for controlling the transverse displacement means of the spreading ramp, operating in response to the means for reading a reference pattern so as to control its position on the reference pattern Lu, and means (130) for materializing another reference pattern (10 ') spaced transversely with respect to the first (10) by a distance equal to the width of a coating strip (20), these means being in solidarity   translation of the ramp in its transverse displacement.   5. The device of claim 4, wherein the means (120) for reading a reference trace are integral in translation of the ramp in its transversal displacement and deliver to the control means a differential error signal representative of the difference from   the center line of the reference plot.   The device of claim 4 or 5, wherein the means (120) for reading a reference trace are optical means.   7. The device of claim 6, wherein the means (130) for materializing a reference pattern are means for printing a narrow luminescent paint ribbon.