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TECHNICAL FIELD

The present invention relates to a system designed for performing maintenance inside the confined spaces of metal constructions employing ^λ ηο man entry' or robot technology, that is, maintenance technology which does not require the presence of a human operator inside the metal construction.

The robot according to the present invention is used during the normal maintenance activities on tanks, cisterns and fixed or mobile metal containers. These activities are performed on a daily basis by skilled personnel who are subject to high risk levels. The accident hazards derive from the confined spaces which limit operator movements inside the container and the low levels of oxygen very often found in these containers. The equipment and products used for this type of maintenance can also generate or emit toxic dusts and chemical substances.

The purpose of the present invention is to dispense with the need for the presence of human operators inside confined spaces. It can be used in the activities listed below and has the added advantage that it improves the efficiency and efficacy of the final result of the operations listed:

• Jet sandblasting;

Cleaning (using water jetting and wet sandblasting) ;

• Painting (using powder, airbrush, airless and other systems ) ;

• Measurement and sampling operations (including ultrasonic thickness testing, monitoring in environments which cannot be accessed by operators, radiometric measurements inside structures which screen or attenuate the intensity of radionuclide activity) ; Visual inspections (including surveys and measurements of plant condition) ;

Maintenance (using plasma cutting technology, very high-pressure water cutting and shot blasting, recovery of process materials) .

BACKGROUND ART

It is known that the following operations inside the confined spaces of metal structures such as tanks, cisterns and fixed or mobile metal containers,. are currently performed by specially trained personnel equipped with the appropriate personal protective equipment (PPE): jet sandblasting; cleaning (using wet jetting or wet sandblasting); painting (with powder or airless systems); measurement and sampling (ultrasonic thickness testing, monitoring in environments which cannot be accessed by operators, radiometric measurements inside structures which screen or attenuate the intensity of radionuclide activity) ; visual inspections (survey and measurement of plant condition) ; maintenance (using plasma cutting technology, very high-pressure water cutting and shot blasting, recovery of process materials) .

For example, jet sandblasting inside metal structures is performed by an operator who must wear a cumbersome protective sandblasting suit equipped with a face mask connected to a breathing air cylinder backpack or to external breathing apparatus systems.

This type of activity is very hazardous because it involves the projection of abrasive material with a high kinetic energy. This can cause personal injury or trigger combustion in explosive atmospheres. Jet sandblasting is also accompanied by the production of considerable amounts of dust with the result that the operator can see little or nothing of the surroundings or the surface being treated. This makes it difficult to judge the quality of the work in progress .

These shortcomings also considerably increase work times because they make it necessary to repeat operations several times on the same surface in order to obtain the degree of sanding required.

Conditions inside confined spaces being sandblasted can be considerably improved by employing the simultaneous recovery of abrasive material. However, the conventional technologies in use today will produce less uniform results in comparison with automated systems. This is because muscular fatigue and poor posture (when working on the ceiling of the tank) make it difficult for the operator to maintain a constant speed and distance from the surface for the duration of the activity.

Similar conditions apply to manual cleaning activities using water jets (water jetting) and the painting of metal surfaces (with internal and external coatings) with the result that the problems are the same.

The same applies to physical measurement and sampling activities. Ultrasonic thickness testing, remote measurement and visual inspection are less demanding physically but they do involve all the risks associated with working in confined spaces. Consequently they have a lower degree of repeatability and provide fewer measurements in comparison with automated methods. It is known that some of the activities indicated above are performed using mechanical or automated systems which obviate the need for a human operator to enter into any confined spaces. However, these devices have a fixed configuration designed for a specific, individual operation only. For example, they can be used for cleaning only or for testing only. This means that they are not very versatile and can be used for only one step of the work cycle which usually consists of a series of steps. (For example, the coating of the inside of a tank involves the following work cycle: cleaning; thickness testing; sandblasting; spraying with a coating) .

Document WO 2012/150541 discloses a device for movement and action in explosive environments including a control centre located outside the explosive environment and a movable vehicle driven hydraulically, whereby a high pressure supply unit is located outside the explosive environment and is connected to the vehicle by means of a flexible hose, whereas the vehicle is controlled by the control centre. The vehicle has at least one jetting nozzle to activate sediments or sludge and at least one hose for carrying out a suction operation on the said sediments or sludge .

Document US-A-5561883 discloses an apparatus for cleaning storage containers used in petrochemical or oil refineries. A remotely controllable dual tracked robotic vehicle is placed in a container to be cleaned. A cleaning fluid diluent material is directed against waste material in the container causing a portion of to form a slurry which is vacuumed out by a nozzle and hose carried by the vehicle .

It should be noted that the vehicles described in the documents quoted above have a configuration whereby there is a fixed and invariable distance between the wheels and where, in particular the distance between the front and rear axles of the vehicle remains fixed and invariable. In this case any geometric irregularities or defects in the surfaces over which the vehicle moves will necessarily cause the detachment of one or more wheels from the surface. This condition can cause the vehicle to slip or in the worst case to detach completely from the walls and fall to the ground or bottom of the container.

DESCRIPTION OF THE INVENTION

The present invention provides a system designed for performing maintenance in the confined spaces of metal structures without the need to employ human operators who would otherwise be subject to the accident hazards described above and thereby eliminates or at least drastically reduces the drawbacks described above.

The system according to the present invention makes it possible to dispense with the presence of human operators inside the confined spaces of tanks, cisterns and fixed or mobile metal containers. The system can be used in the activities listed above and has the added advantage that it improves the efficiency and efficacy of the final result of the operation listed.

This is achieved by a multifunction robot, designed for the maintenance inside the confined spaces of metal constructions such as tanks, cisterns and fixed or mobile metal containers, having the features described in the main claim.

The dependent claims describe advantageous embodiments of the invention. The proposed aims are achieved, according to the invention, by a multifunction robot designed for the maintenance inside the confined spaces of metal constructions such as tanks, cisterns and fixed or mobile metal containers where the robot is controlled from a remote control panel and is designed specifically for carrying into the inside of confined spaces at least one item of equipment designed for a preset function and in particular for the following operations:

• High-pressure water nozzles for cleaning tank surfaces (water jetting and wet sandblasting) ;

• A sandblasting head with equipment for recovering the abrasive material;

• A head fitted with a nozzle for spraying resin or protective paint onto surfaces;

A thickness testing probe;

• An ionising camera for performing radiometric measurements ;

• An environment monitoring system for measuring concentrations of toxic, noxious or radioactive substances ;

• One or more video cameras for performing precision visual inspections;

• A cutting head connected to a plasma technology system for cutting metallic objects;

• A cutting head connected to a very high pressure water jet cutting system for cutting sheet metal and suitable for use in explosive atmospheres;

• Devices for recovering components.

The efficacy of each of the activities performed using the tools indicated above is ensured by the combined effect of the following elements: • The secure and solid adherence of the magnetic wheels to the metallic surfaces combined with the adaptive structure ensure that the robot continuously follows the profile to be treated and also ensures that the tool maintains a constant working distance from the metallic surfaces during the entire operating cycle.

• From the operator panel it is possible to set a suitable travel speed for the robot and fine adjust and stabilize this speed by means of control devices on the compressed air motors so as to ensure uniformity in the treatment in progress.

Both of these factors make it possible to maximise the operational efficacy and efficiency of the robot and thus ensure that the quality of the final result is uniform and repeatable .

In brief, the multifunction robot according to the present invention transfers the operating standards characteristic of automated, robotized production into the inside of very confined spaces.

DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will become clear on reading the description given below of one embodiment, provided as a non-binding example, with the help of the accompanying drawings, in which:

Figure 1 is an overall diagram of a multifunction robot according to the present invention for use inside a tank with a horizontal axis;

Figure 2 is an overall diagram of a multifunction robot according to the present invention without the front tool;

Figure 3 is an overall diagram of a multifunction robot according to the present invention fitted with a front tool for high-pressure water jetting;

Figure 4 shows another embodiment of a multifunction robot according to the present invention in this case fitted with a front tool for ultrasonic thickness testing;

Figure 5 shows another embodiment of a multifunction robot according to the present invention in this case fitted with a front tool for sandblasting with the recovery of abrasive;

Figures 6, 7, 8 and 9 show various geometric work configurations of a multifunction robot according to the present invention in this case with a front tool for sandblasting with the recovery of abrasive;

Figure 10 is a perspective view from below of a multifunction robot according to the present invention.

DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

The present invention provides a system designed for performing maintenance in the confined spaces of metal constructions such as tanks, cisterns and fixed or mobile metal containers, using a multifunction robot 10, shown in Figure 1 inside a horizontal-axis metallic tank 11.

The multifunction robot 10 is controlled from a remote control panel 12 and is designed for carrying into the inside of confined spaces at least one item of equipment designed for a preset function and in particular for the following operations:

• High-pressure water nozzles for cleaning tank surfaces (water jetting and wet sandblasting) ;

• A sandblasting head with equipment for recovering the abrasive;

• A head fitted with a nozzle for spraying resins or protective paints onto surfaces;

• A thickness testing probe;

• An ionising camera for performing radiometric measurements ;

• An environment monitoring system for measuring concentrations of toxic, noxious or radioactive substances;

• One or more video cameras for performing precision visual inspections;

• A cutting head connected to a plasma technology system for cutting metallic objects;

• A cutting head connected to a very high pressure water jet cutting system for cutting sheet metal and suitable for use in explosive atmospheres;

• Devices for recovering components.

In the embodiment described, the commands are transmitted through a series of pipes and cables 13 which connect any motors, pistons and sensors used to a control panel .

Figure 2 shows further details of the invention.

The robot 10 according to the invention comprises an adaptive structure fitted with six highly magnetic wheels 14 powered by compressed air motors 15 which enable the robot 10 to move forward inside the tank while remaining firmly attached to the metal surfaces thanks to the magnetism of the wheels.

These wheels 14 are mounted in pairs forming a pair of front wheels 14, a pair of central wheels 14 and a pair of rear wheels 14.

According to a characteristic of the invention, the structure of the robot 10 comprises two frames 17, 18 hinged to each other at the axle 16 of the two central wheels. The front frame 17 and the rear frame 18 are each fitted with a further axle 19 fitted with magnetic wheels 14. Thanks to this configuration with six wheels 14 and two frames 17, 18, the freedom of movement existing between the two halves of the structure enable the wheels to adhere to the metal bands even in the case of surfaces with awkward curvature and geometry. This structural configuration constitutes an important distinctive element distinguishing the invention from the technically known systems operating with magnetic wheels where the wheels of the robot are positioned at a fixed distance from each other.

Motive power is transmitted from the motors 15 to the magnetic wheels 14 by a chain drive transmission 34.

One compressed air motor 15 drives the three wheels 14 positioned on one side of the robot 10 leaving the other motor 15 to drive the three wheels 14 positioned on the other side of the robot 10. This configuration enables the robot 10:

to travel forwards or backwards inside the confined space by operating the compressed air motors 15 simultaneously with the same direction of rotation; to slightly modify the direction of travel by inverting the direction of rotation of one motor 15 in relation to the other;

to rotate on itself through 360° and to proceed with complete changes in the direction of travel. This movement is made possible by raising the front half portion 17 and the rear half portion 18 of the robot by actuating the pistons 35 (see Fig. 10) so that the front and rear wheels 15 detach from the metal surface, and by actuating the compressed air motors 15 in the inverse direction of rotation. The detaching movement is necessary because the strong magnetic attraction of the wheels 15 would not otherwise allow the wheels to slide and the robot 10 to steer.

A pair of pistons 20, suitably operated, configures the twin frame robot structure to the geometry required and gives it the necessary rigidity by forming a—frame with a triangular shape.

Hinged on the front frame 17 there is a tool holder support 21 fitted with a support plate 22 which thanks to two pistons 23 can be inclined at any angle required with respect to the travel plane of the robot.

Figures 3, 4 and 5 show three example configurations which demonstrate the versatility of the invention and illustrate the mounting onto the robot and in particular onto the support plate 22 of the tools and equipment required for the current operation.

• Figure 3 shows a configuration where a high-pressure washing device is mounted. The high-pressure nozzles 24 can be fixed to brackets 25 made on the front plate 22.

• Figure 4 shows a configuration where a ultrasonic thickness tester 26 is mounted. The ultrasonic thickness tester probe is inserted in a special pad 27 and is fixed to the plate 22 by means of a bracket 28.

• Figure 5 shows a configuration where a sandblasting device 29 with means for recovering the abrasive is mounted. In this case the sandblasting head 30 is fixed to the plate 22 with brackets 31.

The front plate 22 if required can traverse sideways on guides 32 with an alternating movement at a speed set as required thereby increasing the operational capability and productivity of the tool being used.

In one embodiment of the invention, —magnetic wheels 14 have a sandwich construction comprising two outside discs made from carbon steel suitably hardened and knurled on the external circumference and a ring-shaped magnetic core.

Thanks to the high magnetic force, these components securely adhere to the sheet metal of the construction even in extreme operating conditions such as on vertical walls and the ceilings of tanks.

When they receive a command, the frame configuration pistons 20 rotate the front part 17 of the frame backwards so that tool support plate 22 is parallel to the robot travel plane and will thereby enable the robot to climb up vertical walls (see Figures 6 and 7) .

For example, during sandblasting, the brush 30 which sands and recovers the abrasive is kept pressed against the surface to be treated by the angle adjustment pistons 23.

The support plate 22 on which the sanding head is mounted can be made to transverse cyclically on the guides 32 (see Fig. 2) to extend the area to be sandblasted. When the robot travels forwards, the traversing support enables the sanding of an area which is wider than that covered by the brush and thereby reduces the operating times and ensures a uniform degree of sanding.

In high-pressure water jetting applications, the nozzles are fixed to the support plate 22 at the optimum washing distance.

One of the distinctive characteristics of this invention is that this distance will remain constant during movement of the robot and thus ensure uniform, efficient cleaning. The fittings of the robot can include a vision system 33 (Figure 2) comprising an on-board video camera with a wide-angle lens and a high luminosity LED lighting unit. This configuration makes it possible to film the inside of the tanks and display the images on, for example, a PC monitor. The images displayed can be used to facilitate control of the device, to check results during the work cycle and to perform a visual inspection inside the confined space.

The invention is described above with reference to a preferred embodiment. It is nevertheless clear that the invention is susceptible to numerous variations which lie within the scope of its disclosure, in the framework of technical equivalents.