CN110892113A

CN110892113A - Method for grinding test runways with bituminous surface

Info

Publication number: CN110892113A
Application number: CN201880046015.8A
Authority: CN
Inventors: P·科尔米耶; J·马埃; F·佩兰
Original assignee: Arteme Co; Compagnie Generale des Etablissements Michelin SCA
Current assignee: Arteme; Arteme Co; Compagnie Generale des Etablissements Michelin SCA
Priority date: 2017-07-10
Filing date: 2018-07-10
Publication date: 2020-03-17
Also published as: FR3068714A1; WO2019012419A1; US20200164479A1; FR3068714B1; EP3652381A1

Abstract

A method for abrading the surface condition of a test track of an asphalt surface of a vehicle, the method comprising the steps of: -providing a handler (1) comprising a rotating head (2) with at least one friction element (3) to modify the surface condition of the test track; -placing at least one rotating abrasive disc (4) on said processing machine (1); -performing the movement of the handler on the test runway to reduce the friction coefficient to achieve a friction level corresponding to the friction level of the ground runway.

Description

Method for grinding test runways with bituminous surface

Technical Field

The present invention relates to a method for running-in a vehicle to test the surface condition of a runway, said runway being made of asphalt, said method comprising providing a handler comprising a rotating head supporting at least one friction element for improving the surface condition of said test runway; placing at least one rotating abrasive disc on the processor; and treating the surface to be modified.

Background

In order to improve the quality of the road, manufacturers of road pavements are constantly developing new products. Generally, in order to obtain better vehicle grip performance, the aim is to improve the durability of the road surface and its mechanical quality. For this reason, the goal is most often to increase the coefficient of friction of the road surface.

For their parts, builders and suppliers of motor vehicle accessories must be able to test their vehicles and parts under the most realistic and repetitive conditions possible. Specifically, for tires, european union rules R117 and R228 specify in their annex 5 a method for measuring the wet grip coefficient of a tire. The method particularly provides for the average maximum coefficient of braking force of the test tire to be within a specified range of values. Thus, some standards provide the coefficient of friction values for the runway pavement under test.

Due to the improved quality of new road surfaces on the one hand and for the purpose of performing tests representative of road conditions on old road surfaces on the other hand, newly built test runways may not take into account specific requirements for the friction coefficient. Therefore, various ways have been tried to treat the surfaces of new roads of runways to make them quickly satisfactory at an acceptable cost. These known methods are based mainly on the following principles: the ground wear is obtained by rubbing with a rubber plate with or without abrasive particles.

Given the large surface to be treated, the method must be simple, efficient, and suitable for long runways. Currently, there is no truly available definitive method.

Polishing machines are also well known. For example, patent document US20070272223 describes a polishing machine comprising a rotating friction surface provided with bristles. The bristles can be covered with abrasive particles, such as silicon carbide. Machines of this type are used, for example, for polishing concrete floors.

Patent document WO2005113198 shows an example of a polishing brush comprising bristles wrapped with metal abrasive particles. These abrasive bristles are used, for example, to polish concrete floors.

There remains a need to establish a method to enable running-in of a new test runway whose coating has a coefficient of friction such that it cannot perform a representative test.

To alleviate these various disadvantages, the present invention provides various technical means.

Disclosure of Invention

The main object of the present invention consists in defining a surface treatment method capable of reducing the level of grip of the new test runway in order to bring it to a determined target, for example the one provided by the current regulations.

To this end, the invention provides a method of running-in an asphalt test runway surface condition for a vehicle, comprising the steps of:

-providing a handler for changing the surface condition of the test runway, comprising a rotating head supporting at least one friction element;

-placing at least one rotating abrasive disc on a processing machine;

-imposing a movement of the handler on the test runway to reduce the friction coefficient to achieve a friction level corresponding to the target value.

The method enables the friction characteristics of the runway to be modified to obtain predetermined characteristics, such as specific wet grip characteristics.

It should be noted that this method has no significant effect on the depth of the macrostructure (PMT according to standard EN 13036-1), and therefore does not affect the drainage characteristics. As described later herein, other tests performed all have a negative impact on this description.

According to an advantageous embodiment, the method comprises a preliminary step consisting in removing the bituminous binder from the surface of the aggregates by means of hydraulic stripping. This step enables advantageous results to be obtained after a short implementation delay.

According to an advantageous embodiment, the friction element is an abrasive disc with bristles having abrasive particles.

The height of the bristles is advantageously greater than 15 mm.

The form factor of the bristles is advantageously between 1/50 and 1/10, more preferably between 1/40 and 1/30.

For example, the height of the bristles is advantageously less than 60 mm. The diameter of the bristles is advantageously between 2mm and 4 mm.

Unexpectedly, this configuration can yield particularly advantageous results. The tools used are able to perform work over the entire perimeter of the aggregate, not just its top surface.

Advantageously, the abrasive particles of the bristles are of the silicon carbide (SiC), ceramic or tungsten carbide type.

These particles, which cover or embed the bristles or filaments, are able to interact optimally with the aggregates of the pavement.

According to an advantageous embodiment, the rotational speed of the rotating disc is between 1000 rpm and 1500 rpm, more preferably substantially 1200 rpm.

According to another advantageous embodiment, the speed of movement of the treatment machine is between 0.5m/min and 15 m/min, more preferably between 5m/min and 10 m/min.

The friction generated by the rotating disc can avoid causing directional wear.

The number of passes of the processor is preferably between 1 and 10, and more preferably between 2 and 6.

Advantageously, the average contact pressure of the bristles of the abrasive disc is between 1 and 5 bar, preferably between 2 and 4 bar.

According to an advantageous embodiment, the working load applied to the treatment machine is preferably between 200kg and 400kg, more preferably between 260kg and 300 kg.

According to another advantageous embodiment, the processor comprises a sensor giving an indication about the trend of the process, for example a pendulum sensor (such as a "british pendulum tester" sensor). This arrangement enables a simple control of the progress of the method.

The invention also provides a tire test runway surface treatment machine for carrying out the running-in method described above, comprising a rotating head supporting at least one friction element capable of modifying the surface condition of the test runway, wherein the friction element is an abrasive disc with bristles having abrasive grains, and the shape factor of the bristles is advantageously between 1/50 and 1/10, more preferably between 1/40 and 1/30.

Drawings

All the details of implementation are given in the following description, supplemented by figures 1 to 9, which are presented purely by way of non-limiting example, and in which:

figure 1 is a schematic profile view of an example of a surface treating machine;

fig. 2 is a bottom view of the surface treating machine shown in fig. 1, equipped with brushes with abrasive particles;

figure 3 is a schematic profile view of a brush with abrasive particles;

FIG. 4 is a schematic perspective view of a filament consisting of a brush with bristles of abrasive particles;

figure 5 is a bottom view of an example of an abrasive disc;

figure 6 is a schematic profile view of the load carriage in the polishing position and provided with a plate;

FIG. 7 is a graph showing the effects observed on a road surface for different types of polishing;

figure 8 is a chart summarizing the tyre types used for the comparative tests;

FIG. 9. mu. for each test performed_ASTMSummary of changes.

Detailed Description

As seen above, the level of grip required for a vehicle and/or a tire testing track is defined in, for example, standards.

The method needs to be able to cover 0.5<μ_ASTM-16pces<All numerical ranges of 0.9 and more preferably cover the numerical value 0.6<μ_ASTM-16pces<0.8。

Various polishing techniques were tested on a track specifically constructed for this study. Various results obtained show that: the running-in technique using a resurfacing machine equipped with a brush having a large height of sanding is to achieve mu_ASTMThe most efficient method of targeting required by the horizon. These analyses can constitute a double proof:

i) on the one hand, the technique enables a target grip in the range mentioned before;

ii) on the other hand, known tyre performance tests carried out on new runways treated with the method according to the invention are able to obtain tyre classification results comparable to those previously obtained on a given or other test runway.

Determining characteristic

-rate of advancement: 0.5 m/min;

-elapsed number of executions: not less than 4;

-rate of μ decrease: each time passing by 0.07pt mu_ASTM。

Runway for determining validity criteria

550m specially constructed in the area of lower mobility in the tire testing center²The runway of (1). It is made up of two different road surfaces (Sol1 and Sol2) taken from a wet skid. After preliminary work (consisting of removing the asphalt binder from the aggregate surface by hydraulic stripping and delineating the work area), the runway was handed over to a test polishing method.

The choice of road pavement is suitable for the following solutions:

-SOL 1: the microcosmic roughness is low, and the macro roughness is open and is beneficial to a water drainage runway; 5X 60m²A surface of (a);

-SOL 2: the runway has high micro roughness and closed macro roughness; 5X 50m²Of (2) is provided.

The tests carried out

From the two test groups, several different approaches were tested:

A1) plates with high load (high pressure);

A2) SiC plates with low loads (low pressure);

B1) a grinder having a tire tread;

B2) a grinder having an abrasive disc;

B3) a grinder having a rotary brush equipped with bristles having abrasive grains.

Plates with high load (high pressure)

A plate of larger dimensions comprising a bottom friction surface acting as a working surface, said bottom friction surface being provided with a plurality of tire treads arranged in parallel. To improve effectiveness, a load is placed on the plate. The panel forms a trailer without wheels, which is pulled by a tractor or other vehicle with high tractive power. Figure 6 schematically illustrates an example of a loaded plate.

The idea behind the HP plate technology is thus to create a device that enables the rubber to rub with a suitable pressure and for a sufficient length on the road surface to be run in.

The study began with the manufacture of a particular carriage. The carriage consists of a stable metal frame that can be handled by "standard" tractors (for lifting and transport) and rests on a rubber slab. The total weight of the carriage for the applied pressure was 2200 kg. The sliding rack is placed at 6.5 multiplied by 24.0cm²＝637cm ²4 pads of (2); the contact pressure was 3.4 bar.

The implementation of HP plates has caused a certain number of accidents. Improvements to the spray system are necessary to reduce the risk of damage caused by burning. The plate wears very quickly. Therefore, shims must be added to extend the life of the board. In addition to this, the operator has to spend his or her time observing behind him or her, with a rather uncomfortable working posture. As a result, productivity is very general. During the test, an average of eleven passes per day were completed.

This implementation enables rapid identification of two defects of the first batch of boards produced: delamination due to delamination; wear due to burning.

It is estimated that the required number of passes must be around 2000 to achieve asymptotes for different terrain. The number of passes may also depend on the floor being processed. It must be emphasized that the implementation of the HP plate technique presents a work situation that is particularly difficult for the operator, making this solution difficult to industrialize.

SiC plate with low load (low pressure)

This approach is comparable to the previous approach for the main support (i.e., plate). In use, however, no load is placed on the plate. Instead of a load, a medium material acting between the plate and the ground is used. The test therefore comprises the step of laying a layer of SiC on the ground before the passage is performed with the plate.

This technique works at a very low average contact pressure of P ═ 0.03 bar. The surface is approximately 4m²And the weight is about 250 kg.

The use of powders requires adherence to conventional polishing techniques. We start with the larger particle size and end with the fine particle size. For these tests, three particle sizes were achieved: 10 μm, 5 μm and 3 μm. After treatment, the treated areas are not easily cleaned.

From the point of view of the abrasives used in road surfaces, the length of slip is significantly greater than for the HP plate technology. For each pass, one aggregate underwent a slip length of 2 m.

It can be reported that this technique is not effective. From mu_ASTMThis technique gives no results from the point of view of the coefficient of friction, regardless of the ground observed. This may be related to the indentation phenomenon. The LP plate + SiC technique works primarily on the surface of the aggregate, while the tire, which is part of it, contacts the non-working areas. As a first approximation, it is believed that it may take about 5000 passes to try to bring the μ level to the desired target. The technology is very polluting. Once the polishing work is completed, it is quite difficult to remove SiC.

Grinding machine

The grinder is electric and requires a separate device to power it up to the runway.

In fig. 1 to 4, examples of a grinding wheel machine 1 and its different elements are schematically shown. In the example shown, the disposer 1 has a rotating head 2 and is mounted on wheels 8. The rotor head comprises three friction elements 3 (phi 220 mm). Each of the friction elements 3 rotates about its central axis. The speed was adjusted to a rotational speed of 1200rpm by a variable speed drive. The friction element 3 comprises a brush 4 provided with bristles 5. As shown in fig. 4, at least a portion of the bristles 5 are covered with abrasive particles 6. The set of three brushes 4 rotates (about 100rpm) about the central axis 7 of the grinder, thus producing a double rotational movement of the abrasive disc 4.

The abrasive particles 6 are advantageously composed of SiC, ceramic or tungsten carbide.

The handler used in the test had an automated travel system with adjustable speed. The processor is operated by an operator through radio communication. The operator must be located within a perimeter of 5m around the handler. Other operating parameters (unload weight and spray) are adjustable. As is known, the device is used for polishing or cleaning tasks. In these cases, the bristles do not include abrasive particles.

This implementation requires an available generator set. The time required to assemble the apparatus is relatively short, but a lifting device is required to transport the handler quickly. During use, constant spraying is required. To be able to eliminate deposits and to ensure cooling of the surface and the ground. To increase the effectiveness of the polishing, the processor can apply one or more loads 9 or weights.

The test was performed using a model 780RS polisher of "Blastrac".

Grinder with disc having tyre tread

For this test, the abrasive disc 4 consists of a part of the tread of the tire. The diameter of the disc used was 220 mm. The height of the tread is 8 mm.

The test is stopped quickly. The connection between the plate and the handler is not sufficiently secure, causing the disk to break away.

Grinder with granular abrasive disc

Figure 5 schematically shows an example of a particulate abrasive disc used in this test. The discs consist of a resin in which "particles" of tungsten carbide are integrated. Depending on the density and particle size of the particles, the degree of attrition is controlled.

Polishing machine using a brush including bristles coated with particles (SiC)

The apparatus used for these tests is shown in figures 2, 3 and 4 (described above).

The test was done using a fixed rate of about 0.5 m/min. Additional tests were performed at a speed of 10 m/min. Double rotation is advantageously utilized. The pressure lies between 0.2 bar and 0.3 bar.

This test configuration enables the target sought in terms of the μ level. Moreover, the results of comparative tests carried out on one of the treated areas using tyres of known relative grip performance levels are identical to those obtained on a "conventional" runway (figure 8).

From an effectiveness perspective, techniques based on brushes with very high abrasive bristles are aimed at reducing μ_ASTMIs most effective.

Main results

In creating prototypes, performing tests under good safety conditions, monitoring the results obtained, and comparing with previous results to guarantee the authenticity of the observed results, a number of technical difficulties need to be overcome, which indicate that developing a running-in method is a particularly complex and lengthy process, the results of which are totally unpredictable.

Figure 7 schematically shows the main effects on the road surface produced with the method tested. The first diagram shows the profile of the road surface before running-in. The aggregates or pebbles form a rough surface. The next two figures show the particularly limited effect of the plates (plate + SiC and HP plate). The final illustration shows the effect of an abrasive disc working only on the surface. Finally, the penultimate diagram shows the effect obtained with a brush whose filaments comprise abrasive grains in its body (SiC for the tests carried out). It has been observed that the bristles are able to reach all the bulges of the top and sides, which has a particularly decisive three-dimensional effect for achieving the targeted goal of reducing the coefficient of friction.

Fig. 9 shows the obtained friction coefficient values. The advantageous effects of the above-described extremely high abrasive bristles were confirmed.

The table can lead to a number of conclusions:

implementation of only one technique to achieve 0.7 μ_ASTMThe technique is: a brush having bristles, the bristles of which are coated with silicon carbide (SiC) particles;

from μ_ASTMLP carriage + SiC does not have any effect from the perspective of (1).

A 2000 grit grinder did not have any effect;

tests using brushes with very high abrasive bristles can achieve 0.6<μ_ASTM<A target of 0.8 (which demonstrates the robustness of the technique);

the reference diagram shows a μ of about 1_ASTM. The measurement dispersion was about 0.1 point;

HP plate presents a rather low polishing power, the trend developing in the right direction but still insufficient;

a 500 grit grinder is more efficient than a 2000 grit grinder, but reaches the asymptote at a considerable distance from the final target.

Reference numerals used in the drawings

1 surface treating machine

2 rotating head

3 Friction element

4 abrasive discs or brushes

5 bristles

6 abrasive grain

7 center of rotation

8 wheel

9 load

Claims

1. A method for running-in a vehicle to test the surface condition of a runway, the runway being made of asphalt, the method comprising the steps of:

-providing a handler (1) for changing the surface condition of the test runway, the handler (1) comprising a rotating head (2) supporting at least one friction element (3);

-placing at least one rotating abrasive disc (4) on the processing machine (1);

2. A method for running-in a test course's surface condition according to claim 1, comprising a preliminary step comprising removing asphalt binder on the aggregate surface by hydraulic stripping.

3. Method for running-in the surface condition of a test run-way according to any of claims 1 and 2, wherein the friction element is an abrasive disc (4) with bristles (5), the bristles (5) of which have abrasive particles (6).

4. A method for running-in the surface condition of a test run-way according to claim 3, wherein the height of the bristles (5) is greater than 15 mm.

5. Method for running-in the surface condition of a test run-way according to any of claims 3 and 4, wherein the shape factor of the bristles (5) is advantageously between 1/50 and 1/10, more preferably between 1/40 and 1/30.

6. Method for running-in the surface condition of a test run-way according to any of claims 3 to 5, wherein the abrasive particles (6) of the bristles (5) are of the silicon carbide (SiC), ceramic or tungsten carbide type.

7. A method for running-in a test run-track surface condition according to any one of the preceding claims, wherein the rotating disc rotates at a speed of between 1000 and 1500 rpm, more preferably substantially 1200 rpm.

8. Method for running-in the surface condition of a test run-way according to any one of the preceding claims, wherein the speed of movement of the handler (1) is between 0.5 and 12 meters/minute, more preferably between 1.5 and 5 meters/minute, even more preferably substantially 2 meters/minute.

9. A method for running-in a test run-track surface condition according to any one of the preceding claims, wherein the number of passes of the handler is preferably between 1 and 10, more preferably between 2 and 6.

10. Method for running-in the surface condition of a test run-way according to any of the preceding claims, wherein the working load (9) applied to the handler is preferably between 200kg and 400kg, more preferably between 260kg and 300 kg.

11. A tire test runway surface treatment machine for carrying out a running-in method according to any of claims 1 to 10 comprising a rotating head (2) supporting at least one friction element (3), the friction element (3) being capable of changing the surface condition of the test runway, wherein the friction element is an abrasive disc (4) with bristles (5), the bristles (5) of which have abrasive particles (6), and the shape factor of the bristles is advantageously between 1/50 and 1/10, and more preferably between 1/40 and 1/30.

12. The tire testing runway surface treatment machine according to claim 11, wherein the abrasive particles (6) of the bristles (5) are of the silicon carbide (SiC), ceramic or tungsten carbide type.

13. The tire testing runway surface treatment machine of any of claims 11 and 12, wherein the height of the bristles is greater than 15 mm.

14. The tire testing runway surface treatment machine according to any of claims 11, 12 or 13, wherein the average contact pressure of the bristles (5) of the abrasive disc (4) is between 1 and 5 bar, preferably between 2 and 4 bar.