GB2236342A

GB2236342A - Bitumen slurry seal machine

Info

Publication number: GB2236342A
Application number: GB8921075A
Authority: GB
Inventors: David Nicholas Kilner; Steven John Mecrow
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1989-09-18
Filing date: 1989-09-18
Publication date: 1991-04-03
Also published as: GB8921075D0

Abstract

A bitumen slurry machine (1) for applying bituminous asphalt coatings on footways and cycle tracks comprises a self-propelled vehicle (2) having front (3) and back (4) ends and incorporating a hopper (5) for mineral aggregate, a band conveyor (6) mounted below the hopper and having an upper surface (7) forming at least part of the lower internal surface of the hopper, motor means for the band conveyor whereby in operation of the conveyor aggregate in the hopper is moved towards the front end of the vehicle, a tank (10) for bituminous emulsion mounted in the vehicle, a screw mixer (16) mounted below the band conveyor having front (18) and rear (19) ends and arranged to receive aggregate from the band conveyor and bituminous emulsion at or near the front end thereof for mixing of aggregate and emulsion and transport of the resulting mixed bituminous asphalt to the back end of the vehicle, and a surface distributor (21) mounted at the back end of the vehicle and positioned to be able to receive mixed bituminous asphalt from the screw mixer and distribute the mixed bituminous asphalt as a coating on the surface of a footway or cycle track whilst the vehicle is in forwards motion <IMAGE>

Description

APPARATUS FOR APPLYING COATINGS This invention relates to apparatus for applying coatings, in particular to bitumen slurry-seal machines.

Bitumen slurry seal machines are widely used for applying bituminous asphalt coatings on roads, car parks, parade grounds and airfields. Typically such a machine, e.g. as sold by Breining G.m.b.H & Co., Stuttgart, West Germany, comprises a self-propelled vehicle incorporating a hopper for mineral aggregate, a conveyor belt for the aggregate, a bin for cement and tanks for bituminous binder, water and liquid additive (e.g. retarder), and, mounted at the rear of the vehicle, behind the hopper and conveyor belt, a screw mixer for mixing and transporting asphalt to a surface distributor mounted on the rear of the vehicle. Since the hopper with its conveyor belt, and the screw mixer and the surface distributor are mounted in tandem, the known bitumen slurry seal machines are comparatively long, unwieldy machines.

Whilst this unwieldiness is not significant for machines intended for roads, car parks, parade grounds and airfields it presents a significant problem for a miniaturised version of such a machine which might be intended for applying bituminous asphalt coatings on footpaths or cycle tracks.

Foothpaths and cycle tracks frequently incorporate tight-radius bends, particularly when bordering crossroads or T-junctions in roadways.

The present invention now provides the solution to the problem of the long, unwieldy machine, by reversing the conventional direction of motion of the conveyor belt for the aggregate and mounting a screw mixer underneath the aggregate hopper, instead of in tandem therewith.

According to the present invention therefore there is provided a bitumen slurry seal machine for applying bituminous asphalt coatings on footways and cycle tracks comprising a self-propelled vehicle having front and back ends and incorporating a hopper for mineral aggregate, a band conveyor mounted below the hopper and having an upper surface forming at least part of the lower internal surface of the hopper, motor means for the band conveyor whereby in operation of the conveyor aggregate in the hopper is moved towards the front end of the vehicle, a tank for bituminous emulsion mounted in the vehicle and a screw mixer mounted below the band conveyor having front and rear ends and arranged to receive aggregate from the band conveyor and bituminous emulsion from the tank at or near the front end thereof for mixing of aggregate and emulsion and transport of the resulting mixed bituminous asphalt to the back end of the vehicle, and a surface distributor mounted at the back end of the vehicle and positioned to be able to receive mixed bituminous asphalt from the screw mixer and distribute the mixed bituminous asphalt as a coating on the surface of a footway or cycle track whilst the vehicle is in forwards motion.

Conveniently the vehicle may incorporate a cement silo, and one or more tanks for liquids additional to the bituminous emulsion, e.g. for water and for setting retarder.

Advantageously the screw mixer is a twin screw mixer, which may be provided with continuous worm blades or with discontinuous, paddle, blades.

In operation of the machine, aggregate (e.g.

stone particles, 0 to 6 mm) is transferred from the hopper by the band conveyor, and bituminous emulsion, together with any other ingredients, such as cement, water and setting retarder is passed, into the screw mixer. Mixed bituminous asphalt passes from the screw mixer into the surface distributor, which spreads the asphalt coating in essentially known manner.

As will be clear to the man in the art, the various ingredients of the asphalt can be metered in known manner to ensure that the resulting coating is of desired quality.

The invention will now be further understood from the following detailed description of a preferred embodiment thereof, which is made, by way of example, with reference to the accompanying schematic drawings, in which Figure 1 is a longitudinal sectional view of a bitumen slurry seal machine in accordance with the invention, and Figure 2 is a plan view of the surface distributor mounted at the back end of the vehicle in the bitumen slurry seal machine of Figure 1.

In the drawings, like integers are denote by like reference minerals.

Referring to Figure 1, the bitumen slurry seal machine (1) comprises a self-propelled vehicle (2) having front (3) and back (4) ends and conventional motive system, steering gear and brakes (not shown).

The vehicle (2) incorporates a hopper for mineral aggregate (5). A band conveyor (6) is mounted below the hopper (5). The band conveyor (6) has an upper surface (7) which forms the lower internal surface of the hopper (5).

The band conveyor (6) is provided with motor means (not shown) whereby in operation of the conveyor (6) aggregate in the hopper (5) is moved towards the front end (3) of the vehicle (2). A silo (8) for portland cement is mounted in the vehicle (2) ahead of the hopper (5). At the lower end of the silo (8) is an outlet (9).

The vehicle is also provided with three tanks (10, 11 and 12) respectively for polymer-modified bitumen emulsion, water and setting retarder (e.g.

"PERAL"(trade mark) ex Raschig), having respective outlets (13, 14 and 15).

A screw mixer (16) is mounted in the vehicle (2) below the band conveyor (6). The screw mixer is conveniently a twin screw mixer, having mixer blades (17) which may either be continuous worm blades, as shown, or may be discontinuous, paddle, blades. The screw mixer (16) has front (18) and rear (19) ends, and is arranged to receive aggregate from the band conveyor (6), cement from the outlet (9) of the silo (8), polymer-modified bitumen emulsion from the outlet (13) of the emulsion tank (10), water from the outlet (14) of the water tank (11) and setting retarder from the outlet (15) of the retarder tank (12), through one or more inlet openings at or near the front end (18) of the screw mixer (16).The screw mixer (16) is arranged so that in operation of the slurry seal machine, the aggregate (e.g. stone particles 0 to 6 mm), 'cement, emulsion, water and retarder are mixed together and transported towards the rear end (19) of the screw mixer (16) so that the resulting mixed bituminous asphalt is transported to the back end (4) of the vehicle (2), where it leaves the screw mixer (16) through one or more outlet apertures (20).

A surface distributor (21) is mounted at the back end (4) of the vehicle (2), conveniently via upper (22) and lower (23) struts. The upper struts (22) may be provided with motor means (not shown) to enable pivotal raising of the distributor (21) for convenience of manoeuvering of the vehicle (2) when it is not being used to apply bituminous asphalt coatings.

The surface distributor (21) comprises a main frame (24) which comprises front (25) and rear (26) plates and cross members (27). Slidably mounted on the main frame (24) are two U-shaped frame members (29). Hydraulic rams (29) link the U-shaped frame members (28) with the main frame (24) and enable independently variable positioning of the U-shaped frame members (28) relative to the main frame (24) to allow the width of the surface distributor (21) to be adjusted to conform with the width of the footway or cycle track which is to be surface coated.

The lower edge (30) of the front plate (25) and corresponding parts of the U-shaped frame members (28) is lower than the lower edge (31) of the rear plate (26) and corresponding parts of the U-shaped frame members (28) may be provided with height adjustable integers (not shown) in known manner, in order to allow for adjustment of the predetermined constant thickness of coating.

Conveniently the vehicle (2) is about 2 to 2.5 metres long and about 1 metre wide. The surface distributor (21) is conveniently adjustable in width from about 1 metre to about 1.8 metres, but if U-shaped frame members (28) are made in such a way as to allow overlap thereof (e.g. by having the legs of one U-shaped member mounted inside the front (25) and rear (26) plates) adjustment from 1 metre to 3 metres is possible.

Conveniently the various integers of the machine illustrated above are made of steel, but the lower edge (31) of the rear plate (26) and the lower edge (30) of the front plate (25) are preferably formed from renewable rubber strips mounted in suitable holders.

Operation of the machine of the above embodiment of the invention is as hereinbefore described. Any pumps and meters which are desired to be used for the aggregate, the cement, the bitumen emulsion, the water and/or the setting retarder may be known integers operated in known manner.

Claims

1. A bitumen slurry seal machine for applying bituminous asphalt coatings on footways and cycle tracks comprising a self-propelled vehicle having front and back ends and incorporating a hopper for mineral aggregate, a band conveyor mounted below the hopper and having an upper surface forming at least part of the lower internal surface of the hopper, motor means for the band conveyor whereby in operation of the conveyor aggregate in the hopper is moved towards the front end of the vehicle, a tank for bituminous emulsion mounted in the vehicle, and a screw mixer mounted below the band conveyor having front and rear ends and arranged to receive aggregate from the band conveyor and bituminous emulsion from the tank at or near the front end thereof for mixing of aggregate and emulsion and transport of the resulting mixed bituminous asphalt to the back end of the vehicle, and a surface distributor mounted at the back end of the vehicle and positioned to be able to receive mixed bituminous asphalt from the screw mixer and distribute the mixed bituminous asphalt as a coating on the surface of a footway or cycle track whilst the vehicle is in forwards motion.

2. A machine according to Claim 1 wherein the screw mixer is a twin screw mixer.

3. A machine according to Claim 1 substantially as hereinbefore described.

4. A machine according to Claim 1 substantially as hereinbefore described with reference to the accompanying drawings.