RU2834948C1 - Reloader of asphalt concrete mixture - Google Patents

Abstract

FIELD: road construction.

SUBSTANCE: invention relates to the field of road construction and in particular to the design of the hot asphalt mix transfer loader. In the reloader of hot asphalt concrete mixture, comprising a chassis on rolling bearings, on which there are power units and a process unit for thermal and fractional desegregation of the hot asphalt concrete mixture, process unit is made in the form of a dump truck body, open at both ends and connected to the chassis by means of at least one hydraulic cylinder and a hinge, which provides the possibility of the body turning in the vertical direction under the influence of the first one. Body is equipped with a detachable cover, under which mixing blades are mounted on the body bottom.

EFFECT: simplified design of a reloader.

2 cl, 4 dwg

Description

The invention relates to the field of road construction and, in particular, to the design of a hot asphalt concrete mix transfer machine.

The technology of continuous paving of the road surface using reloaders appeared about thirty years ago in the USA. In Russia, reloaders began to be used in the early 2000s. Currently, the new technology is being actively implemented by Rosavtodor. The requirements set out in the appendix to the order of the Federal Road Agency dated May 29, 2013 No. 717-r came into force, according to which, when carrying out work on laying the upper layers of asphalt concrete pavement, it is necessary to ensure the indicators of uniformity of temperature behind the asphalt paver, namely: the difference in temperatures of the transverse profile of the laid asphalt concrete pavement, measured at a distance of 0.3-1.0 meters from the asphalt paver's screed plate, should not exceed 10 ° C. Considering that new mixtures have become more rigid, the use of reloaders should become a mandatory condition.

Uneven temperatures during delivery of asphalt concrete mix are caused by the fact that a dump truck loaded with this mix usually takes a long time to get from the mixing plant to the place where the asphalt concrete is laid, covering considerable distances, either pushing through traffic jams or getting stuck in muddy conditions. The longer this lasts, the more the asphalt concrete mix cools, and it cools unevenly: faster near the walls of the dump truck body and on top, and slower in the depths of the mix. This results in uneven temperature of the mix, or so-called segregation. The danger is that the mix, segregated by temperature, gets into the receiving bin of the asphalt paver and its cold parts are not laid tightly enough, unlike the hot ones. As a result of subsequent laying, loose zones are formed on the finished surface, into which water penetrates during further use of the roadway, which leads to the formation of areas of rapid destruction in these places rather quickly.

In addition to temperature segregation, during the movement of the dump truck, there is a redistribution of large and small fractions of stone material in the volume of asphalt concrete mixture - in this case, fractional segregation occurs. Smaller fragments leak through larger ones and move downwards. Thus, the mixture that is unloaded into the asphalt paver bin is completely different from the one that was thoroughly mixed in the asphalt concrete plant before loading into the dump truck. Such segregation must be combated by repeated mechanical mixing of the mixture directly in the reloader. This is most effectively accomplished by heavy reloaders equipped with a large storage bin with a powerful auger.

Any reloader, as an intermediate link between a dump truck and an asphalt paver, provides 100% protection against the so-called transverse shift of the coating, since it eliminates contact between the latter. Indeed, as soon as the dump truck approaches the asphalt paver and unloads the mixture into the receiving bin, this process is accompanied by an impact load. The impact is transmitted to the asphalt paver plate, as a result of which a transverse shift is formed on the formed coating. In this zone with a changed density, a transverse crack will appear during subsequent use of the roadway.

Another significant advantage of any material handler is the continuity of paving. Every time the asphalt paver stops, a transverse shift also occurs in the pavement with the same consequences of crack initiation in the asphalt concrete. It is necessary to stop, for example, when the mixture runs out, and the dump truck for some reason has not delivered a new portion. At this time, the material handler loaded by the dump truck continues to move at the same speed as the asphalt paver, but at a safe distance from it. At the same time, the paver's hopper continues to be filled with asphalt concrete mixture. In this case, dump trucks can drive up to the material handler at any time and load it with asphalt concrete mixture into the storage hopper with a reserve. By the way, the larger the storage hopper, the better the conditions for continuous paving. Continuity automatically means higher laying speed - the time is reduced by exactly the same amount of downtime as when, according to the traditional scheme, a dump truck is unloaded into the paver's hopper.

The design of the reloader described in US 5035534 was chosen as the closest technical predecessor (prototype). References to the positions of individual units and mechanisms are used from the description of the prototype patent. It should be noted that the layout diagram of the reloader 10 includes the main functional devices that are mandatory and, thus, create a classic image of the reloader, preserved to this day, as if "for all time". Such main devices include a chassis 20, a loading bucket (hopper, container) 33, the cavity of which is connected to the cavity of the storage bin 23 by means of a loading scraper conveyor 86. In the bottom part of the bin 23, a mixing auger 60 is mounted, which carries out double desegregation, which interacts with the second unloading scraper conveyor 47, in turn, reloading the mixture onto a belt conveyor 65, intended for filling the bin of the asphalt paver. Thus, in the design of the prototype loader, three main functional units can be distinguished: firstly, the loading unit, including the loading bucket 33 and the scraper conveyor 86, the technological unit, represented by the storage bin 23, the mixing screw 60 and, finally, the unloading unit, including two continuous transport means in the form of the scraper conveyor 47 and the belt conveyor 65.

The main problem of the prototype loader is the complexity of its design, which is a consequence of its saturation with separate transport devices, in particular, two scraper and one belt conveyors. The latter require significant material and labor costs for their production. Moreover, each of them requires considerable energy costs during operation, as well as costs associated with operation and repair. The presence of a number of functionally independent devices, mechanisms, units in any machine leads to a decrease in its operational reliability, and this fully applies to the design of the prototype loader.

Thus, the solution to the problem is directly related to the simplification of the design and, as a consequence, the improvement of economic indicators during its production and operation, as well as increasing reliability in operation.

The indicated problem is solved due to the fact that in a hot asphalt concrete mix transfer machine, containing a chassis on rolling supports, on which power units and a process unit are placed, intended for implementing temperature and fractional desegregation of hot asphalt concrete mix, the process unit is made in the form of a dump truck body open at both ends and connected to the chassis by means of at least one hydraulic cylinder and a hinge, which provides, under the influence of the former, the ability to rotate the body in the vertical direction, wherein the latter is equipped with a removable cover, under which passive and/or active mixing blades are mounted on the bottom of the body, intended for implementing turbulent diffusion of the mixture during its movement from the body during the transfer process.

The technical result of the invention is a significant simplification of the design of the reloader due to the exclusion of continuous transport means in the form of three conveyors, the main purpose of using which was to overcome the gravity of the mass of the asphalt concrete mixture when moving the latter in the process of its temperature and fractional desegregation. Such simplification of the design of the reloader became possible as a result of using a dump truck body open at both ends as a means of transporting the mixture, in which the driving force is the component of the gravity of the mass of the mixture directed along the body, which is created by tilting it in the vertical direction.

The drawings attached to the description provide the following schematic representations:

- Fig. 1 - general view of the reloader from the side;

- Fig. 2 - view of the body with the lid open, option 1;

- Fig. 3 - view of the body with the lid open, option 2;

- Fig. 4 - view of the body with the lid open, option 3.

The design of the transfer machine according to the proposed invention is based on a method of moving the asphalt concrete mixture, different from that of the prototype, starting from loading the transfer machine to unloading it into the asphalt paver hopper. If in the prototype the mixture is moved in the process of constantly overcoming the gravity forces of its mass, i.e. fighting this force by transferring the mixture from one conveyor to another, then in the proposed design the law of transformation of the potential energy of the raised mass of the asphalt concrete mixture into the kinetic energy of its movement along the inclined surface of the body from the loading point to the unloading point, known from physics, is used. To organize such movement of the mass of the mixture, it is sufficient to raise the latter during loading to a pre-calculated height, taking into account the fluidity of the mixture or, in other words, its viscosity at temperatures of 150-160 °C, as well as the degree of slipperiness of the contact surface of the body, which will ensure the inclination of the latter at a minimum angle, which will be at least equal to the angle of natural repose for a pair, in this case, of interacting materials, is used. Minimization of the body tilt angle, while ensuring reliable movement of the mixture along it, is a condition for creating a compact design of the reloader. Ultimately, the entire transport system for moving the mixture within the reloader is reduced to the design of the body, kinematically connected with the power tool, i.e. the hydraulic cylinder mounted on the chassis.

The design of the material handler includes a chassis 1 formed by a frame 2 on rolling supports 3, which are pneumatic wheels. The latter can be driven, i.e. connected to engines, of which hydraulic ones are preferred. Frame 2 is two longitudinal beams connected to each other by means of transverse beams, not shown in the drawing. At the end of frame 2, closest to the asphalt paver being loaded, a U-shaped portal 4 is installed, which, in order to increase the overall rigidity of the supporting structure of the material handler, is connected by means of struts 5 to frame 2. Under portal 4 on frame 2, a horizontal hinge 6 is fixed, connected also to body 7, providing it with rotation in the vertical direction by means of hydraulic cylinder 8, having a rod of a telescopic design similar to the rod of the hydraulic cylinder for lifting the body of a dump truck. The hydraulic cylinder 8 is connected with the body 7 by its rod through the eye 9. The number of hydraulic cylinders can be limited to two, which are located symmetrically on both sides of the body 7. The latter is made open at both its ends and the end opposite to the hinge 6 is made in the form of a bucket 10 for receiving asphalt concrete mixture from a dump truck equipped with side walls 11, increasing its capacity. Under the bucket, or, more precisely, under its end, 10, a rolling support 12 is installed. The rest of the body is covered with a removable cover 13. On the outside, the entire body 7 is covered with a heat-insulating material, and its inner surface is covered with a material with low sliding friction (anti-friction), for example, Teflon. Mixing blades are installed on the bottom of the body 7, which can be passive and / or active, they are designed to implement turbulent diffusion of the mixture when it moves from the body during the transfer process. The mixing blades, like the inner surface of the body, are covered with an antifriction material. The passive blades 14 are flat plates mounted on the bottom of the body 7 in a certain order (Fig. 2), providing the effect of maximum turbulence of the hot asphalt concrete mixture during its unloading, which can be established during subsequent scientific experiments. The order of the arrangement of the blades 14 in Fig. 2 is one of the possible ones. The active blades are shown in Fig. 3 by a pair of mixers 15 installed at the outlet of the body 7, each of which is connected to a drive for its rotation (not shown in the drawing), a hydraulic motor is preferable. A variant of the drive with one motor connected by a transmission to both mixers 15 is possible. Fig. 4 shows a design variant of the transfer machine, in the body 7 of which a combination of passive and active blades is located. In Fig. 1 under position 16 is shown the asphalt paver hopper, and - 17 is the cabin with the control system and power plant.

The loader of the proposed design operates as follows.

The hot mixture is unloaded by a dump truck from an asphalt concrete plant into the bucket 10 of the body 7, which is tilted at the time of loading, resting on the rolling support 12. Before the process of unloading the mixture into the hopper 16 of the asphalt paver, the body 7 is tilted in the opposite direction under the action of the hydraulic cylinder 8, setting its right end above the hopper 16 (Fig. 1, position A). The asphalt concrete mixture, under the action of the component of the gravity force of the mixture, directed along the bottom of the body 7, will begin to slide in the direction of the hopper 16, interacting with the passive blades 14, as shown in Fig. 2 and Fig. 4, undergoing turbulent diffusion or, in other words, mixing. The described process can be qualitatively enhanced by additional use of active mixer blades 15, as shown in Fig. 4. An option (Fig. 3) is possible using only active blades. In any of the described mixing cases, temperature and fractional desegregation of the hot asphalt concrete mixture will be achieved to one degree or another.

Claims (2)

1. A transfer machine for asphalt concrete mixture into an asphalt paver, comprising a chassis on rolling supports, on which power units and a process unit are placed, intended for carrying out temperature and fractional desegregation of hot asphalt concrete mixture, characterized in that the process unit is made in the form of a dump truck body, open at both ends and connected to the chassis by means of at least one hydraulic cylinder and a hinge, which provides, under the action of the former, the ability to rotate the body in a vertical direction, wherein the latter is equipped with a removable cover, under which active mixing blades are mounted on the bottom of the body. 2. A transfer machine according to item 1, characterized in that the internal surfaces of the body and mixing blades are coated with an antifriction material, such as Teflon.

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