EP2735650A1 - Method for treating layers, and its auxiliary construction machine - Google Patents

Abstract

The method involves milling the layers in a predetermined cutting depth by a construction machine with milling-or mixing roller. The milling-or mixing roller is surrounded by a roller housing (7) which limits the mixing chamber of the milling-or mixing roller. The quantity of binder supplied per unit time is automatically mixed in proportion to the milled material quantity milled per unit time in continuous operation. The determination of the current supplied binder quantity to reach the predetermined cutting depth takes place depending on the current milled milling material quantity present in mixing chamber during the adding process. An independent claim is included for a construction machine, particularly stabilizer or recycler with a chassis.

Description

The invention relates to a method for treating layers, and to a construction machine or cultivation machine, in particular a soil stabilizer or recycler, according to the preamble of claim 1, 8 or 9.

Layers are understood to mean asphalt layers, such as the top layer or base layer of a traffic area, unbound rock layers and soils.

Such construction machines are used for material processing, namely z. As the stabilization of insufficiently viable soil, the pulverization of asphalt blankets to the recycling, or solidification of bound or unbound layers needed.

Known stabilizer or recycler have a roller housing in which a milling / mixing roller is arranged, as well as a unit for dispensing and dosing of soil stabilizer.

The circulating in a mixing chamber milling / mixing roller is arranged to adjust to the surface to be machined usually height and tilt adjustable.

In this mixing room, depending on the particular application, the necessary processes take place, e.g. Peeling and crushing the milled layers, adding binders, blending and homogenizing added materials, etc.

Such machines are often used for soil stabilization.

In order to improve or consolidate soils, it is known to incorporate pulverulent binders, for example lime or cement, water and / or additives into the soil, in order to increase its installation capacity and load-bearing capacity. Typical applications for soil stabilization are the construction of roads or railway tracks as well as industrial areas.

Cement can also be added as a suspension (dissolved in water) for dust-free addition. However, this method is only applicable if additional water is to be introduced into the soil. For soils with already too high water content, this method is not suitable. Furthermore, bitumen, bituminous solutions or additives are used to increase the load bearing capacity of soils.

For bonding loose soil layers it is therefore usual that these binders, e.g. bituminous solutions, foam bitumen or suspensions and / or additives and / or water are mixed in the stabilization process with the milled material.

The amount of binder to be mixed results from site-specific requirements and is usually given in percent by weight in relation to the milled material to be treated (for example, 1% admixture of binder corresponds to 10 kg of binder per t of milled material).

The metering of the binders takes place in the prior art via a metering device which adapts the actual amount of binder introduced to the current operating state of the machine. For this purpose, the amount of material being milled is recorded per unit of time during operation on the basis of the milling width, milling depth and feed rate. Based on this value can then be done the dosage of the binder.

Usually, a weight-dependent dosage of the binder takes place on the basis of a measurement of the volume flow and on the basis of the known density of the binder.

When processing several mutually parallel milling tracks, it is common that the milling tracks overlap. In this case, it is necessary that only the proportion of the milled material is considered, which was not yet mixed with binder in the course of already completed processing a parallel track.

For this purpose, the metering width is set for the binder and the determination of the milled Fräsgutmenge, which is to be mixed with binder, is not based on the milling width, but based on the set activated dosing.

During the continuous milling and mixing process, there is a substantially constant amount of milled material milled in the mixing chamber, so that only the mass flow (mass or volume flow) is considered with regard to the metering.

Therefore, it is sufficient according to the prior art, under the condition of a constant cutting depth and metering width to measure the feed rate. At constant feed rate of the flow in the mixing chamber remains constant within the roll housing.

A disadvantage of the prior art, however, is that for the piecing process of the milling / mixing roller at the beginning of processing no proportionally metered admixture of the binder can take place.

The pumps used in the prior art for the promotion of the binder are not adjustable from a value 0 to a desired flow rate. Therefore, as a rule, there can be no continuous increase in the delivery rate in the course of the piecing process.

If the injection begins at the beginning of the piecing process, then the amount of binder introduced is too high and the result of the work does not correspond to the specifications.

Begins the injection of the binder only when the milling drum has completely penetrated into the layer to be processed, or when the machine starts to feed, so there is the problem that already eroded material is already outside the engagement area of the milling / mixing roller and thus can not be mixed with the now-injected binder.

In practice, therefore, results at the beginning of a milling track a Ansetzbereich of several meters, in which the material is not mixed with sufficient binder, or is introduced in the excessive amount of binder in the material. This area must then be reworked by other means. Alternatively, it is possible to disable the automatic during the piecing process and manually control the introduction of the binder. However, this variant has the disadvantage that no dosage of the material is carried out according to the specifications, usually too much or too little binder is introduced into the soil and the quality of the machined area does not meet the requirements, because no uniform stability of the machined layer on the entire machined surface is achieved.

This is particularly disadvantageous because more than one piecing process is usually necessary for the processing of a surface and the reworking of the result is therefore necessary at different points. Failing a post-processing, the risk of damage increases, and a reduced durability of the traffic area is to be expected.

The object of the invention is therefore to provide a method for consolidating layers or a construction machine, which make it possible to avoid the need for post-processing of the work result.

To solve this problem serve the features of claim 1, 8 or 9.

The invention advantageously provides that, during the piecing process, the determination of at least the amount of binder currently to be fed is carried out until the predetermined milling depth has been reached, depending essentially on the amount of milled material currently being milled in the mixing chamber. This has the advantage that the predetermined mixing ratio between binder and milled material can be substantially maintained even in the preparation phase and a homogeneous soil consolidation in the entire machined area can be achieved.

The term binder is to be understood as meaning binders, as well as water and / or additives.

It can be provided that the amount of milled material currently in the mixing chamber is determined at least as a function of the current milling depth of the milling / mixing roller.

Preferably, the amount of material currently in the mixing chamber is determined at least as a function of the current penetration speed of the milling / mixing roller in the layer.

In the invention, the change in the cutting depth is measured, in order to conclude on the changing amount of milled material in the mixing chamber.

At the beginning of the milling and mixing process, it is to be assumed during the piecing process that, in the rarest of cases, a constant penetration rate for the Penetration of the milling / - and mixing roller is given in the material. This is due to the fact that, for example, different asphalt layers have different strengths, for example a cover layer in relation to a base layer.

In particular, it is provided that the determination of the amount of milled material located in the mixing chamber is determined by the measurement of the milling depth and in dependence on the radius and the width of the milling / mixing roller or dosing width.

The metering width of the milling / mixing roller is the part that is engaged with the not yet treated layer. A metering device, for example in the form of a metering strip with a plurality of injection nozzles arranged side by side, is switched on only in the area of the metering width.

The change in the milling depth can be used to calculate the change in the quantity of binders currently to be supplied.

For this purpose, when the milling drum penetrates into the layer, a calculation of the currently milled amount of milled material per unit of time takes place essentially via the detection of the change in the milling depth. This makes it possible, depending on the radius of the cutting circle and the milling width or the current metering width of the milling / mixing roller to determine the not yet mixed with binder amount of milled material. On the basis of the amount of material per unit of time currently present in the mixing space, the amount of binder injected into the mixing space is then controlled.

The change in the milling depth is due to the penetration rate. On the basis of the milling depth, the amount of milled material currently present in the mixing chamber is calculated. At any time, the integrated amount of binder added should be proportional to the integrated amount of milled material in the mixing chamber.

In one embodiment, it is provided that, when the amount of milled material exceeds a certain limit, the injection of binder is started, or that if a sufficient amount of milled material is present in the mixing space, a continuous injection with variable flow rate of binder is started.

Due to the penetration rate, the depth of cut can be determined at a specific time; This milling depth can, due to the given geometry of the milling drum, be assigned to the volume existing at the time in the mixing chamber.

Alternatively, the current milling depth can be measured directly.

After reaching the predetermined milling depth and the beginning of the feed, the control of the amount of binder can be carried out in a conventional manner depending on the milling width, the predetermined cutting depth and the current feed rate with the known from the prior art method.

To solve the problem, a construction machine is provided, in which the control device controls the currently supplied amount of binder before reaching the predetermined milling depth depending on the currently located in the mixing chamber amount of milled material.

Preferably, it is provided that the control device determines the amount of material currently in the mixing chamber at least as a function of the penetration rate of the milling / mixing roller in the soil layer and controls the dosage of the binder proportionally.

In a preferred embodiment, it is provided that the density values of different layers to be processed and the binder to be used are stored in a database of the controller or the control device.

In the following, the invention will be explained in more detail with reference to the figure.

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Baumaschine,

Fig. 2

der die Fräs- und Mischwalze umgebende Mischraum mit einer Dosiereinrichtung zum Eindüsen von Bindemittel,

Fig. 3a

sich aus dem Ansetzprozess ergebende Ansetzbereiche,

Fig. 3b

die Standfestigkeit der verfestigten Bodenschicht nach dem Stand der Technik,

Fig. 4a

eine schematische Darstellung der Berechnungsparameter zur Bestimmung der Bindemittelmenge,

Fig. 4b

die Fräsbreite der Fräs-/Mischwalze, und

Fig. 5

die Anpassung der Bindemitteldosierung während der Ansetzphase im Vergleich zum Stand der Technik.

Show it:

Fig. 1

a schematic representation of a construction machine according to the invention,

Fig. 2

the mixing chamber surrounding the milling and mixing roller with a metering device for injecting binder,

Fig. 3a

Ansetzbereiche resulting from the piecing process,

Fig. 3b

the stability of the solidified soil layer according to the prior art,

Fig. 4a

a schematic representation of the calculation parameters for determining the amount of binder,

Fig. 4b

the milling width of the milling / mixing roller, and

Fig. 5

the adaptation of the binder dosage during the Ansetzphase compared to the prior art.

Fig. 1 shows a schematic representation of the essential components of a self-propelled stabilizer or Recyclers. The construction machine has a machine frame 1, which is supported by a chassis. The chassis has two front wheels 4 in the working direction 9 and two rear wheels 3 in the working direction, which are attached to the front and rear lifting columns 6.5. The front and rear lifting columns 6.5, which can each be operated independently of each other, are in turn attached to the machine frame 1, so that the machine frame relative to the bottom layer 2 can be adjusted in height. Instead of wheels 3,4 and drives, such as track drives can be provided.

Fig. 1 shows the machine for working lanes with a chassis supported by a machine frame 1 and consisting of a cab 20 control station.

The trolleys have at the front and rear ends of the machine frame 1, two jointly or optionally individually steerable suspension axles, in which each wheel is provided with its own hydraulic drive in the form of a hydraulic motor and may optionally be controlled separately. Each wheel is provided with a height adjustment 5.6, so that the height of the machine frame 1 and, if necessary, whose inclination is set exactly at working or transport height. Below the driver's cab 20 to the machine center is offset a roller housing 7 is fixed, which limits a serving as a mixing chamber 10 working space of a rotating milling / mixing roller 8.

Fig. 2 schematically shows the milling / mixing roller 8 with the surrounding mixing chamber 10 under the roller housing 7. The milling / mixing roller 8 is in Fig. 2 shown in continuous operation in which the dosage of the binder by means of a metering device 16 is carried out in a conventional manner, namely as a function of the propelling speed. Shown is therefore the situation in which the milling drum 8 is already in the predetermined milling depth FT.

Fig. 3a shows a surface to be machined in plan view, in which the construction machine has machined the layer 2 in a plurality of parallel mutually parallel milling tracks, because the milling width FB of the milling / mixing roller 8 is less than the width of the surface to be machined. This results in both working direction 9 and transversely thereto several Ansetzbereiche 22 in which the milling / mixing roller 8 has been lowered from its rest position to the desired depth of cut FT.

If no control of the amount of binder in the attachment region 22, results in the prior art, differences in the stability S of the substrate, as in Fig. 3b depending on in Fig. 3a shown distance x are shown. These weak points on the Ansetzbereichen 22 can under load with high dynamic weights, z. As in a heavy traffic cause the solidified surface is damaged, or the durability is significantly reduced.

In the case of large-area machining, it is generally necessary, due to various basic conditions, to re-set the machine several times.

In addition to the fact that a multiple attachment due to the limited working width of the construction machine, z. As a stabilizer is required, it may be necessary to interrupt a milling track and edit adjacent adjacent areas to allow post-processing by graders and / or compressors.

This is mainly due to the fact that after the introduction of the binder only a limited period of time is available in which the material can be processed in the desired quality.

This is u. a. reasoning that the incorporated binders can evaporate or harden.

Fig. 4a shows the cutting circle 15 with the radius r of the milling / mixing roller 8 during the piecing process, in which the milling / mixing roller 8 is first lowered to the predetermined milling depth FT. During the piecing process, preferably no movement of the construction machine in the advancing direction 9 takes place.

However, there is the possibility to superimpose the lowering movement with a propulsion movement. In this case, the amount of material to be milled per unit of time must also be included in the calculation of the amount of material to be milled in the mixing space 10, which amount of material additionally enters the mixing space 10 due to the speed of advance.

During the Ansetzprozesses results in a complex issue, since now the calculation of the milled Fräsgutmenge must be made via a function that the Fräswalzenbreite FB (or a Dosierbreite FB ') and the cross-sectional area A of the layer 2, engaged part of the cutting circle 15 of the milling / mixing roller 8 taken into account.

A denotes the cross-sectional area of the circular section currently located in the layer 2, which is defined by the milling depth FT and the diameter of the milling / mixing roller 8, d. H. the radius r of the cutting circle 15 is predetermined.

With a change in the milling depth FT, there is thus simultaneously a change in the cross-sectional area A over time. The volume can be calculated from the product of milling width FB (or metering width FB ') and cross-sectional area A.

$$r=\frac{\mathit{FT}}{2}+\left(\frac{s^2}{8*\mathit{FT}}\right)$$

The following relationships apply: $$A=\frac{\mathit{<figure-callout\; id="6"\; label="FT"\; filenames="imgf0001.png"\; state="\{\{state\}\}">FT</figure-callout>}}{6s}*\left(3{\mathit{<figure-callout\; id="2"\; label="FT"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">FT</figure-callout>}}^2+4s^2\right)$$

$$r=\frac{\mathit{<figure-callout\; id="2"\; label="FT"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">FT</figure-callout>}}{2}+\left(\frac{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">s</figure-callout>}}^2}{\mathrm{8th}*\mathit{FT}}\right)$$

By solving the lower relation for s we get: $$s=\sqrt{\mathrm{8th}*\mathit{FT}*r-4*{\mathit{<figure-callout\; id="2"\; label="FT"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">FT</figure-callout>}}^2}$$

Substituting s into the upper relationship yields for the current cross-sectional area A: $$A=\frac{32*{\mathit{<figure-callout\; id="2"\; label="FT"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">FT</figure-callout>}}^2*r-13<figure-callout\; id="3"\; label="*\; FT"\; filenames="imgf0001.png"\; state="\{\{state\}\}">*\; </figure-callout>{\mathit{FT}}^{}{\mathit{}}^3}{6*\sqrt{\mathrm{8th}*\mathit{FT}*r-4*{\mathit{<figure-callout\; id="2"\; label="FT"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">FT</figure-callout>}}^2}}$$

It is understood that the formulas given represent only one realizable embodiment which does not limit the scope of protection, and that also modifications of the formulas, e.g. in the form of correction factors or additional parameters or simplifications.

By changing the cross-sectional area A, at a constant or not constant lowering speed of the milling / mixing roller 8 thus results in a continuous Change of the volume or the mass of the milled material to be milled per time unit.

It follows that even with a constant penetration rate of the milling / mixing roller into the material, the binder dosage is not constant and must be constantly adjusted depending on the milling depth.

A simplified example of a variable binder dosage B = f (t) during the piecing process is shown Fig. 5 in comparison with a prior art metering in which in one case (a) the injection already takes place at the beginning, or in the other case (b) at the end of the piecing process.

wobei V/t das aufgefräste Volumen je Zeiteinheit und D die Dichte des Fräsgutes angibt.The calculation of the mass of binder to be added per time unit takes place as a function of the mass M of the amount of material to be milled per unit of time via the following relationship: $$\left(\mathrm{M}/\mathrm{t}\right)=\left(\mathrm{V}/\mathrm{t}\right)*\mathrm{D}.$$

where V / t is the milled volume per unit time and D is the density of the milled material.

After reaching the predetermined milling depth FT, the volume per unit time V / t of the milled Fräsgutmenge resulting from the cross-sectional area of the milling / mixing roller 8, which is in engagement with the material layer 2 and the distance traveled / time (feed rate v) from the following relationship the state of the art: $$\left(\mathrm{V}/\mathrm{t}\right)=\mathrm{FT}*\mathrm{FB}*\mathrm{v}\mathrm{,}$$

The metering device 16, with the aid of which the binder is supplied, is controlled by a control device 14. The control device 14 may be part of a machine control 12, with which the travel drive of the construction machine and the drive of the milling / mixing roller 8 is controlled.

The density values D of different layers 2 to be processed and the binders to be used are preferably stored in a database 18 of the controller 12 or the controller 14.

How out Fig. 4b As can be seen, it may happen that the milling / mixing roller 8 overlaps with an already milled milling track, so that the milling / mixing roller 8 is only partially engaged with a not yet treated layer 2. In this case, not all of the injection nozzles 24 of the metering device 16 are activated, but only those injection nozzles 24 which are located within the active metering width FB 'of the milling / mixing roller 8. The consideration of the active metering width FB 'allows a correct metering of the binder, even in the case of overlapping milling tracks.

The milling width FB in the formulas can be replaced by the effective metering width FB 'to correctly calculate the amount of binder.

In the simplest embodiment, it is only necessary to measure the milling depth FT during the piecing process and to determine the volume and thus the mass of the milled material on the basis of the depth of cut. If a certain amount of milled material is reached, then a corresponding injection of binder takes place.

In order to ensure operation of the pumps used for conveying the binder in accordance with the pump-specific operating parameters, it may also be necessary for this purpose to introduce the binder not continuously but in a clocked manner into the mixing chamber 10. For this purpose, there is a continuous monitoring of existing in the milling drum housing 7 amount of milled material to determine when a renewed introduction of binder is required.

Example:

An admixture of 10% by weight of binder is needed. When activated, the pump has a minimum delivery of binder of a volume equal to 20 kg.

As soon as the amount of milled material (determined via milling depth) corresponds to a mass of 200 kg, a first injection of the minimum quantity of binder takes place. As soon as If the amount of material to be milled corresponds to a milled mass of 400 kg, a second injection of the minimum quantity of binder, etc. takes place. This procedure can accompany the entire piecing process without having to record the penetration rate.

Once a sufficient flow of material is achieved to ensure operation of the pumps above the minimum flow rate, continuous injection of variable flow rate binders can begin.

If the machine starts to feed, the continuous introduction of the binder can be effected as a function of the feed rate v according to the method known from the prior art.

Instead of a self-propelled stabilizer also cultivation stabilizers can use the described method. These are not self-propelled attachments that are moved by a tractor, for example. An example of such an attachment stabilizer is the Wirtgen WS 250 machine.

In other applications, the dosage of the binder, such as a suspension, not by the stabilizer itself, but z. B. by an anticipated suspension mixing plant, as it is known for example as Wirtgen suspension mixing plant WM 1000.

For example, in this embodiment, it is possible to perform the control of the delivered amount of binder on another machine based on the operating parameters of the soil stabilizer or the cultivation machine, wherein the binder is supplied to the mixing chamber 10.

Claims (15)

Method for treating layers (2) by milling the layers (2) and by introducing binders into the milled volume of the layer (2) to be treated, with a construction machine having a milling / mixing roller (8) with which the layer ( 2) in a predetermined milling depth (FT) is milled, wherein the milling / mixing roller (8) by a roller housing (7) is surrounded, which limits the mixing space (10) of the milling / mixing roller (8) and wherein in continuous operation the amount of binders fed per unit time is automatically mixed in proportion to the amount of milled material per unit of time,
characterized in that
During the piecing process, the determination of at least the amount of binder currently to be supplied is carried out until the predetermined milling depth (FT) is reached as a function of the milled material quantity currently being milled in the mixing chamber (10). A method according to claim 1, characterized in that the currently in the mixing chamber (10) befindliches amount of milled material is determined at least in dependence on the current milling depth (FT) of the milling / mixing roller (8). A method according to claim 1, characterized in that the currently in the mixing chamber (10) befindliches amount of milled material is determined at least in dependence on the penetration rate of the milling / mixing roller (8) in the layer to be treated (2). A method according to claim 2 or 3, characterized in that in the mixing chamber (10) located milled Fräsgutmenge by integration of the milled per unit time Fräsgutmenge by measuring the current milling depth (FT) or the penetration rate of the milling / mixing roller (8) in the layer ( 2) and depending on the diameter (r) and the milling width (FB) or metering width (FB ') of the milling / mixing roller (8) is determined. Method according to one of claims 1 to 4, characterized in that after reaching the predetermined cutting depth, the control in a conventional manner depending on the milling width FB or metering width FB ', the predetermined depth of cut FT and the current feed rate v is performed. Method according to one of claims 1 to 5, characterized in that the dosage of the amount of binder takes place by weight. Method according to one of claims 1 to 6, characterized in that the dosage of the amount of binder is controlled intermittently. Construction machine, in particular stabilizer or recycler, with a chassis carrying a machine frame (1) which has front wheels (4) or drives in the working direction and rear wheels (3) or drives in the working direction (9), - A on the machine frame (1) between the front and rear wheels (4,3) or drives arranged roller housing (7) in which a milling / mixing roller (8) is rotatably mounted, wherein the roller housing (7) the mixing space (10 ) of the milling / mixing roller (8), - At least one metering device (16) for metering at least one binder, and a control device (14) for the at least one metering device (16) which controls the amount per unit time of binder automatically in relation to the amount of milled material per unit of time,
characterized in that
the control device (14) controls the currently supplied amount of binder before reaching the predetermined milling depth as a function of the milled material currently located in the mixing chamber (10). Cultivation machine for treating layers by milling the layers and by introducing binders, with a machine frame (1), - One on the machine frame (1) arranged roller housing (7) in which a milling cut the milling / mixing roller (8) is rotatably mounted, wherein the roller housing (7) limits the mixing space (10) of the milling / mixing roller (8) . - At least one metering device (16) for metering at least one binder, and a control device (14) for the at least one metering device (16) which automatically controls the amount per unit time of binder and / or water and / or additives in relation to the amount of milled material per unit of time,
characterized in that
the control device (14) controls the currently supplied amount of binder before reaching the predetermined milling depth as a function of the milled material currently located in the mixing chamber (10). Apparatus according to claim 8 or 9, characterized in that the control device (14) currently in the mixing chamber (10) befindliches amount of milled at least as a function of the current milling depth of the milling / mixing roller (8) determines and proportionally controls the dosage of the binder. Apparatus according to claim 8 or 9, characterized in that the control device (14) currently located in the mixing chamber (10) amount of milled material determines at least depending on the penetration rate of the milling / mixing roller (8) in the soil layer (2) and the dosage of the binder proportionally controls. Device according to one of claims 8 to 11, characterized in that the controller (12) on reaching the predetermined milling depth (FT) the currently supplied amount of binder as a function of the milling width (FB) or the metering width (FB '), the predetermined milling depth (FT ) and the currently measured feed rate (v). Device according to one of claims 8 to 12, characterized in that the control device (14) doses the amount of binder based on weight. Device according to one of claims 8 to 13, characterized in that the density values (D) of different soil layers (2) to be processed and the binder to be used are stored in a database (18). Device according to one of claims 8 to 14, characterized in that the at least one metering device (16) can be controlled intermittently.

Images