WO2010071446A1

WO2010071446A1 - Paint grater

Info

Publication number: WO2010071446A1
Application number: PCT/NO2009/000437
Authority: WO
Inventors: Reidar Otto Olsen
Original assignee: Safety Tools Allmet As
Priority date: 2008-12-19
Filing date: 2009-12-17
Publication date: 2010-06-24
Also published as: EP2382099B1; NO329823B1; EP2382099A1; NO20085335L; EP2382099A4

Abstract

A paint grater (10) for use in environments susceptible to explosions, (EX), is described, comprising a housing (12) partially open in the bottom with an outlet (18) for sucking up material which comes loose during the process. The paint grater- comprises a rotating file (14) for low temperature grating off of paint from an adjoining foundation, in which the file (14) and said suction unit are driven by an air motor (16), as said suction unit is arranged to provide an underpressure in the housing (12) to force the rotating file (14) against the foundation.

Description

Paint grater.

The present invention relates to a paint grater for use in environments susceptible to explosions, comprising a housing at least open in part at the bottom with an outlet for suction of material which comes loose during the process .

In connection with renovation and rebuilding of constructions offshore, old paint must often be removed. Removal of paint is often carried out in environments susceptible to explosion (EX) , where stringent demands are made about the working temperature of the equipment that is used and how it affects the environment. Use of open flames and grinding tools that can lead to sparks and high temperatures are not allowed in such environments.

A work process to remove paint in such environments must leave the surface of the underlying metal free of residual paint and the process must not lead to temperatures above 60 ⁰C. Furthermore, it must be possible for only one person to operate the process without being a strain on the environment with regard to smell, dust and noise. The process must also be able to be carried out in an offshore environment where the rules for danger of explosion must be followed.

From prior art, attention is given to GB 910399' A, US 2,997,730 Al, GB 821742 A and JP 2007159816 A.

GB 821742 A is regarded to be a technology that comes closest to the present invention, and relates to a device for removal of paint with a partially open housing with a rotating brush for removal of paint without providing additional heat. The brush is driven by an engine and the device has a suction unit connected to an outlet in the housing for sucking up of paint which comes loose during the process.

Said GB 821742 A shows a standard, known solution to rub away paint from a foundation with the help of a rapidly rotating brush which is driven by an electric motor, and where paint dust is sucked out of the housing. Such a device can not be used in an EX environment, where stringent demands are made with respect to. fire safety, as the rapidly rotating brush will generate far too much heat, and will neither not give the necessary surface cleanliness that is required.

With the present solution, paint is not rubbed off the surface, but the paint is grated in such a way that a surface cleanliness of, for example, between 75 - 100 micron, can be provided. Furthermore, it is carried out at a very low temperature.

Consequently, it is an object of the present invention to provide a solution that satisfies all, or most of, the above mentioned requirements.

A person skilled in the arts that is faced with the problem of providing a solution for an EX environment, where a rotating file is pressed against the foundation will therefore not look to any of the documents described.

This object is achieved with a paint grater as described in the independent claim 1, in that the paint grater comprises a rotating file for low temperature grating of paint on an adjoining surface, in which the file and said suction unit are driven by an air motor, as said suction unit is arranged to provide an underpressure in the housing to force the rotating file against the foundation. Alternative embodiments are given in the dependent claims 2 - 10.

The housing comprises preferably a number of valves and is equipped with elastic sealing strips against the foundation, whereby said valves are arranged to regulate the underpressure in the housing and the force of the rotating file against the foundation. Said valves can be spring loaded.

The air motor can be arranged to drive the file via a belt drive .

Said file can be formed in a circular-cylindrical form and be manufactured, in the main, from tungsten carbide.

Furthermore, the sealing strips can be arranged to be compressed to even out irregularities in the foundation, and the valves can be arranged to keep the underpressure in the housing constant.

In a further embodiment, the housing can be equipped with one or more magnetic rollers for propulsion of the paint grater along the foundation, where the magnetic roller and the rotating file can be driven by the air motor via a common belt drive. The magnetic roller can be connected to a reduction gear, arranged to adjust the propulsion speed across the foundation.

The invention shall now be explained with help of the enclosed figures, in which two example embodiments of the present invention are shown.

Figure 1 shows a first embodiment of the present invention. Figure 2 shows a second embodiment of the present invention.

Other and further embodiments are also possible within the frame of the invention.

Figure 1 shows a paint grater 10 for use in environments that are susceptible to explosion. The paint grater 10 comprises a housing 12 at least partially open in the bottom, with a rotating file 14 for low temperature grating of paint on an adjoining surface (not shown) . The housing 12 is closed to the environment at the top. The rotating file 14 is preferably driven by an air motor 16, but other drive means can also be used. Furthermore, a vacuum is formed inside the housing in that a suction unit is connected to an outlet 18 in the housing, as said suction unit is arranged to provide an underpressure in the housing to force the rotating file 14 against the foundation and to suck out material that comes loose during the process.

In the embodiment shown, the driving of the rotating file is provided via one or more belts, chains or the like 20, connected between a shaft of the file and a shaft of the air motor 16. Furthermore, the file 14 can be mounted in the housing 12 with sealed bearings which partially protect the bearings against paint dust and which ensure the underpressure in the housing.

Furthermore, the housing 12 comprises a number of valves 22, which, for example, can be spring loaded and the housing 12 is equipped with elastic sealing strips 24 against the foundation, for example, rubber strips. This implies that said valves 22 are arranged to regulate the underpressure in the housing and the 'force of the rotating file against the foundation. If required, the paint grater 10 can thereby be held against the foundation with constant force if this is required, by the regulation of the valves 22 and due to the compression of the elastic sealing strips 24.

The rotating file 14 grates or cuts the paint off the surface of the foundation and can be manufactured in a circular-cylindrical form of, for example, more than 95% tungsten carbide. And also a special alloy that provides additional strength against wear and thereby extends the lifetime of the tool. The "teeth" of the file are cut in a special process and thus ensures that the file removes paint when it has contact with the foundation in such a way that the tool neither slides nor rubs against the foundation and thereby does not generate unnecessary heat. With the expression "low temperature" is meant temperatures in the main below 70 ⁰C, and preferably in this context below 60 ⁰C.

With background in the special rotating file, the speed of rotation can also be held low, for example, between 800 - 3000 rpm, which also leads to less heat generation.

Figure 2 shows a further embodiment of the solution shown in figure 1 and is, in the main, shaped in the same way. Similar parts are therefore given the same reference numbers .

As can be seen, the solution in figure 2 is additionally equipped with one or more magnetic rollers 26 for propulsion of the paint grater 10 along the foundation. The magnetic roller 26 can be mounted in the same way as the file 14. The magnetic roller 26 and the rotating file 14 are initially intended to be driven by the air motor 16 via a common belt drive 20,20' . As the magnetic roller 26 and the file 14 shall be able to rotate at different speeds, the magnetic roller 26 can be connected to a reduction gear, arranged to adjust the speed of propulsion of the paint grater 10 across the foundation.

Claims

1. Paint grater (10) for use in environments susceptible to explosions (EX), comprising a housing (12) at least in part open at the bottom with an outlet (18) for suction of material which has come loose in the process, c h a r a c t e r i s e d i n that the paint grater comprises a rotating file (14) for low temperature grating of paint on an adjoining foundation, in which the file (14) and said suction are driven by an air motor (16)., as said suction is arranged to provide an underpressure in the housing (12) to force the rotating file (14) against the foundation.

2. Paint grater according to claim 1, c h a r a c t e r i s e d i n that the housing (12) comprises a number of valves (22) and is equipped with elastic sealing strips (24) against the foundation, whereby said valves (22) are arranged to regulate the underpressure in the housing (12) and force the rotating file against the foundation.

3. Paint grater according to claim 2, c h a r a c t e r i s e d i n that said valves (22) are , spring loaded.

4. Paint grater according to claim 1, c h a r a c t e r i s e d i n that the air motor (16) is arranged to drive the file (14) via a belt drive (20) .

5. Paint grater according to claim 1, c h a r a c t e r i s e d i n that said file (14) is manufactured in a circular-cylindrical shape and made, in the main, from tungsten carbide.

6. Paint grater according to claim 1, c h a r a c t e r i s e d i n that the housing (12) is equipped with one or more magnetic rollers (26) for propulsion of the paint grater along the foundation.

7. Paint grater according to claim 6, c h a r a c t e r i s e d i n that the magnetic roller (26) and the rotating file (14) are driven by the air motor (16) via a common belt drive (20,20') .

8. Paint grater according to claim 7, c h a r a c t e r i s e d i n that the magnetic roller (26) is connected to a reduction gear arranged to adjust the speed of propulsion across the foundation.

9. Paint grater according to one or more of the preceding claims, c h a r a c t e r i s e d i n that the sealing strips (24) are arranged to be compressed to cancel out any irregularities in the foundation.

10. Paint grater according to one or more of the preceding claims, c h a r a c t e r i s e d i n that the valves (22) are arranged to keep the underpressure in the housing (12) constant.