US3900968A

US3900968A - Mobile cleaning and polishing device

Info

Publication number: US3900968A
Application number: US519185A
Authority: US
Inventors: Genshichi Shigyo
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-12-10
Filing date: 1974-10-30
Publication date: 1975-08-26
Anticipated expiration: 1992-08-26

Abstract

A mobile cleaning and polishing apparatus is readily movable from work site to work site to effect surface cleaning and polishing of large metallic structures such as ship hulls and storage tanks. The apparatus is suspended from a crane or hoist and comprises a mobile frame assembly having mounted thereon a centrifugal projector for impelling abrasive particles against a surface to be cleaned and a collection system for collecting the abrasive particles scattered off the surface along with the removed paint, scale and other waste matter thereby preventing any contaminants from being introduced into the atmosphere. A set of magnets are resiliently mounted on the frame assembly and magnetically attract the apparatus towards the metallic structure being worked on to effectively position and maintain the apparatus in close proximity to the surface to be cleaned during its operation. A series of rollers are connected to the apparatus to enable same to roll along the surface and the rollers maintain a slight clearance between the magnets and the surface thereby preventing the magnets from physically contacting and adhering to the surface. The rollers may be positively driven by a drive system incorporated in the apparatus to advance it along the surface or the crane or hoist which suspends the apparatus may be used to effect advancement of the apparatus.

Description

1 1 Aug. 26, 1975 [541 MOBILE CLEANING AND POLISHING DEVICE [76] Inventor: Genshichi Shigyo, 353 Minami Tanakamachi, Nerima-ku, Tokyo, Japan [22] Filed: Oct. 30, 1974 21 App1.No.:519,185

Related US. Application Data [63] Continuation-impart of Scr. No. 285,634, Sept. 1,

1972, abandoned.

[30] Foreign Application Priority Data Dec. 10, 1971 Japan 46-99906 [52] US. Cl. 51/5 R; 51/9 M 51 lm. C1. B24c 3/06 [58] Field of Search 51/5 R, 4, 8 R, 9 R, 9 M;

Primary Examiner-Donald G. Kelly Azrorncy, Agent, or Firm-Robert E. Burns; Emmanuel .1. Lobato; Bruce L. Adams 5 7 ABSTRACT A mobile cleaning and polishing apparatus is readily movable from work site to work site to effect surface cleaning and polishing of large metallic structures such as ship hulls and storage tanks. The apparatus is suspended from a crane or hoist and comprises a mobile frame assembly having mounted thereon a centrifugal projector for impelling abrasive particles against a surface to be cleaned and a collection system for collecting the abrasive particles scattered off the surface along with the removed paint, scale and other waste matter thereby preventing any contaminants from being introduced into the atmosphere. A set of magnets are resiliently mounted on the frame assembly and magnetically attract the apparatus towards the metallic structure being worked on to effectively position and maintain the apparatus in close proximity to the surface to be cleaned during its operation. A series of rollers are connected to the apparatus to enable same to roll along the surface and the rollers maintain a slight clearance between the magnets and the sur face thereby preventing the magnets from physically contacting and adhering to the surface. The rollers may be positively driven by a drive system incorporated in the apparatus to advance it along the surface or the crane or hoist which suspends the apparatus may be used to effect advancement of the apparatus.-

27 Claims, 10 Drawing Figures MOBILE CLEANING AND POLISHING DEVICE This is a continuation-in-part of the patent application, Ser. No. 285,634 filed Sept. 1, 1972 and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning and polishing apparatus and more particularly, to a mobile cleaning and polishing apparatus for abrasively cleaning and polishing metallic surfaces of ship hulls, storage tanks and other large structures.

2. Description of the Prior Art There are many industries which employ large steel structures. For example, the shipping industry employs large vertical surfaces of bulls of ships and the oil industry employs large vertical surfaces of storage tanks. The large surfaces of the ship hulls and the oil storage tanks must be periodically painted and otherwise treated to maintain them in a good working condition. That is, the exterior and interior surfaces of these structures must be systematically cleaned or pre-treated before the painting operation in order to remove scale, rust, old coats of paint, and other foreign matter.

Conventionally, these vertical surfaces has been manually cleaned and polished by wire'brushing, scraping method or by means of a disk sander. However, much time and money are involved in carrying-out the wire-brushing and scraping step in order to keep these vertical surfaces in satisfactory operating condition or to treat these surfaces such as finish coating or painting.

These conventional cleaning and polishing techniques are normally performed by crews of workmen and requires to build a line of scaffolds along the surface of the structure to be cleaned. Apparently, these techniques need disadvantageously a time-consuming and dangerous tasks. In addition, the crews of workmen must work dangerously at high elevations and consequently the labor cost is quite high.

Recently, sandblasting technique has been employed to clean and polish the surfaces and now the sandblasting technique is the most widely used since it provides the best finish in the shortest time. But, the sandblashing technique has been accompanied by many disadvantages.

According to one of the disadvantages of the sandblasting technique, each workman is required to wear a dust-proof suit and respirator to protect him from inhaling the dust created during the sandblasting. If the workman does not wear the dustproof respirator, they will inhale considerable amounts of dust and it is quite common in such situations for the unprotected workmen to suffer silicosis due to their long exposure to excessive amount of dust particles. In fact, the dust given off during the sandblasting operation is so voluminous that the sandblasting technique causes the surroundings of the operation to be dirty and accordingly it is usually carried on in the restricted area on at night so that it will not interfare with the progress of other working operations carried out adjoining place.

In addition, the area in which the sandblasting operation is carried out becomes filled with large quantities of sand and therefore much labor must be expended in cleaning up the area.

The cleaning and polishing apparatus of the present invention was especially designed to overcome the aforementioned disadvantages of the prior art and to effect cleaning and polishing the structure to be treated in a rapid and efficient manner without discharging any dust particles into the surrounding atmosphere. According to the present invention, the apparatus satisfactorily cleans and polishes very large surfaces of a structure at an operation speed approximately fifteen to twenty times faster than that heretofore possible by conventional manual techniques. Therefore, the cost of polishing and cleaning operation is must reduced and the amount of dust particles discharged during the operation is made excellently small.

Since the air of atmosphere surrounding the workmen does not polluted by the dust particles discharged during a sandblasting operation and the workmen can work in a clean environment, an effciency of labor is greatly raised.

According to the present invention, it is provided that a novel cleaning and polishing apparatus which is depended by means of hoisting apparatus such as a jib crane or an overhead crane so as to be moved up and down along the wall of structures to be cleaned and polished. The apparatus of the present invention advantageously employs an automatic and remote controlling system consisting of a remote-switching device and long electric wire connecting the motive power installed in the frame of the polishing and cleaning apparatus of the present invention with the electric switching device remotely placed on an operators seat in the crane. The scale, old paint, cips and other foreign matter removed from a surface of the structure to be treated and the abrasive particles used to abrasively clean and polish the structural surface are collected and separated from each other in order to use the collected abrasive particles many times and to dump the removed scale, old paint etc, as a refuse thereby preventing dust and other contaminants from polluting the surrounding atmosphere, the apparatus itself and the operator.

According to a first embodiment of the present invention, the cleaning and polishing apparatus employs generally a needle or wire-bundle descaling device, a shot blasting device for throwing abrasive particles on a surface desired to. be cleaned, and a separator for separating the used abrasive particles from the refuse. As stated above, the cleaning and polishing apparatus constructed according to the first embodiment of the present invention comprises the needle descaling device in addition to the shot blasting device thereby the apparatus is advantageously used to the surface having heavy scale or thick old paint coats.

According to a second embodiment of the present invention, the cleaning and polishing apparatus does not employ the needle descaling device and the cleaning and polishing operation is carried out generally by the shot blasting device. Therefore, the apparatus of the second embodiment is made compact and light in weight.

SUMMARY OF THE INVENTION It is, therefore, a primary object of the present invention to provide a cleaning and polishing apparatus which effectively cleans a surface of structure by abra sive particles and collects them along with with scale,

old paint, cips and other foreign matter removed from the surface.

Another object of the present invention is to provide a mobile cleaning and polishing apparatus which is remotely controlled and easily movable along the surface to be treated by means of a hoisting apparatus.

Still another object of the present invention is to provide a cleaning and polishing apparatus which abrasively cleans large structural surfaces so as to prevent dust and other containants from polluting the surrounding environment of working.

A further object of the present invention is to provide a cleaning and polishing apparatus which is continuously operative to clean a structural surface and remotely controlled by an operator seated in a hoisting crane.

Still further object of the present invention is to provide a heavy duty cleaning and polishing apparatus which is coninuously operative to descale with needles, abrasively clean a surface of structure, collect the used abrasive particles and recycle them in order to project onto the surface to be treated.

Still another object is to provide a compacted cleaning and polishing apparatus which is continuously operative to abrasively clean a structure and collect the used abrasive particles along with the waste material removed from the a surface of the structure in order to separate the reuseable abrasive particles and to continuously recycle them for further use.

Still another object of the present invention is to provide a novel heavy duty cleaning and polishing apparatus including a needle descaler for removing rusts, scales and old paint coats, a centrifugal projector for projecting abrasive particles against the surface to be treated after the surface has been descaled and a circular conveyor for transporting the used abrasive particles to the centrifugal projector.

Still another object of the present invention is to provide a compacted cleaning and polishing apparatus comprising a centrifugal projector for projecting abrasive particles against the surface to be treated and a conveyer system for transporting the used abrasive particles to the centrifugal projector.

A still further object of the present invention is to provide a cleaning and polishing apparatus which is magnetically attracted to the metallic surface being cleaned and is maintained keeping a slight distance between the apparatus and the surface so that the apparatus may advance along the surface and effectively skip over weld beads and other surface irregularities and which is capable of cleaning and polishing inclined surface having an angle of inclination up to approximately 12.

The above and other objects of the present invention are carried out by a cleaning and polishing apparatus comprising a mobile frame assembly movable into and out of a working position with a small distance from the surface of a structure to be cleaned abrasive projecting means mounted on the main frame for impelling abrasive particles against a section of the surface in order to effect abrasive cleaning of the surface by removing therefrom scale and other waste particles, collecting means mounted on the main frame for collecting the abrasive particles scattered off the surface along with removed scale and other waste particles, and positioning means coacting with the main frame for positioning and maintaining a frame assembly in its working position during operation of the cleaning and collecting apparatus. The mobile apparatus is easily movable from work site to work site and is suspended from a hoist or crane effecting movement of the apparatus along the surface of the operation of the apparatus is remotely controlled by a single workman who is stationed a safe distance away from the work site.

The apparatus of the present invention will be described in detail hereafter with reference to a ship hull and it is understood that the mobile cleaning and polishing apparatus is equally applicable for the cleaning of large storage tanks or any other large structures.

Other objects, features and advantages of the present invention will become apparent by reading the following detailed description when taken in conjunction with the accompanying drawings/ BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory schematic view of the mobile cleaning and polishing apparatus of the present invention showing one technique for suspending the apparatus;

FIG. 2 is an explanatory schematic view similar to FIG. 1 and showing another technique for suspending the apparatus;

FIG. 3 is a front plan view, partly in section, of an embodiment of the mobile cleaning and polishing apparatus;

FIG. 4 is an elevated side view in cross section of the mobile cleaning and polishing apparatus shown in FIG.

FIG. 5 is a rear plan view, partly in section, of the mobile cleaning and polishing apparatus shown in FIGS. 3 and 4;

FIG. 6 is a front view of another embodiment of the mobile cleaning and polishing apparatus;

FIG. 7 is an elevated side view in cross section of the apparatus shown in FIG. 6;

FIG. 8 shows partly a rear view of the apparatus shown in FIGS. 6 and 7;

FIG. 9 is a top view of the second embodiment of the mobile cleaning and polishing apparatus; and

FIG. 10 is a front view of Trapo Roll.

DETAILED EXPLANATION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show the two different installations for suspending and moving the mobile cleaning and polishing apparatus M of the present invention. In FIG. 1, the apparatus M is being used to clean and polish the exterior surface of a hull C of a ship housed within a dry dock B. In the treating technique shown in FIG. 1, a crawler crane A is employed to suspend and move the apparatus M along the hull surface and the operator of the crane A controls both the movement of the apparatus along the surface and the function of the cleaning and polishing apparatus'M.

According to the treating technique shown in FIG. 2, the cleaning and polishing apparatus M is suspended by a trolley E which is movable along rails removably attached to the hull C by a linkage system D. The control of the trolley E as well as the control of the components of the cleaning and polishing apparatus M are effected by a single operator situated at the bottom of the dry dock B. The workman actuates a series of push-button on a remotecontrol board to control the movement of the trolley E and the function of operation of the cleaning and polishing apparatus M of the present invention. The remot-control board and the operator could be postioned atop the deck B if desired.

The details or components of the mobile cleaning and polishing apparatus M will now be described with reference to FIGS. 3-5. The apparatus comprises as apparent from FIG. 3 a frame assembly 40 having a generally cuboidal configuration and being composed of a series of interconnected angle irons. A pair of hooks 41 are connected to the frame assembly and cooperate with a cable 42 to connect the apparatus of the present invention to a crawler crane, trolley, hoist, or other suitable device which suspends it and effects movement of the apparatus along a surface to be treated.

The mobile cleaning and polishing apparatus includes abrasive cleaning means for impelling abrasive cleaning particles against the surface to be cleaned and polished, and collecting means for collecting the abrasive particles scattered off the surface being cleaned along with the removed scale and the othe waste particles. The abrasive cleaning means will be described first with reference to FIGS. 4 and 5.

The abrasive cleaning means of the apparatus comprises a powerful centrifugal projector 1 connected to the frame assembly 40 for centrifugally projecting abrasive particles towards the surface with a velocity on the order of 70 meters per second. The abrasive particles preferably comprise shot, grit, or sand particles which are suitable sized to exfoliate scales and coats of paint from the surface and leave the surface with a polished finish.

The centrifugal projector 1 comprises a spiral casing 2 and a rotary impeller 4 mounted for rotation with the casing 2. A plurality of hollow and radially extending tubes 3 are connected to the impeller 4 and function to centrifuge the abrasive particles radially outwardly in response to rotation of the impeller. The rotational movement of the tubes 3 coact with the shape of the spiral casing 2 to impel the abrasive particles in the direction of the arrows shown in FIG. 4, whereupon the particles are forcibly flung against the surface to be cleaned.

The impeller 4 is connected to a drive shaft 6 which is rotatably mounted within a housing 5. One end of the drive shaft 6 is connected by means of pulley belts to the output shaft of a drive motor 7. The drive motor 7 coacts with the pulley belts to rotationally'drive the impeller 4 is approximately 2000 to 3300 revolutions per minute thus causing the abrasive particles to be projected towards the surface to be cleaned at a rate of 130 to 170 kilograms per second. This high rate is effective to clean and polish the hull surface.

A hopper 8 is positioned upstream from the impeller 4 and functions to supply the abrasive particles to the center of the impeller 4 through a flexible chute 9. As clearly seen in FIG. 4, the center portion of the impeller 4 is provided with a receiving chamber connected to the base of the chute 9 whereupon the abrasive particles flow downwardly into the receiving chamber and are flung radially outwardly by centrifugal force through openings in the recei ing chamber into and through the tubes 3. A transition section is provided with an outlet opening 12 and such defines the outlet of the centrifugal projector. By such a construction, abrasive particles are continuously fed into the centrifugal projector 1 during operation of the apparatus.

In accordance with the present invention, collecting means is connected to the frame assembly for collecting the abrasive particles randomly scattered off the hull surface along with the removed paint, scale, waste particles and other foreign matter thereby preventing these particles from being distributed about the work area. The collecting means comprises a collection chamber composed of

interconnected passages

13, 16, l7 l8 surrounding the outlet opening 12 for receiving and collecting therein the scattered abrasive particles along with the waste particles. The general configuration of the collection chamber is best seen in FIG. 3 and the interior of the collection chamber is divided by partitions into

additional passages

14 and 15. The

recovery passages

14 and 15 receive the scattered abrasive particles along the heavier waste particles whereas the

passages

13, 16, 17 and 18 primarily recieve the lighter waste particles including the dust generated during the cleaning operation,

Sealing means is provided for'fluid-tightly sealing the space between the collection chamber and the hull surface thereby ensuring that all of the dust and other foreign material is routed into the collection chamber. The sealing means comprises a plurality of flexible sealing members 19 composed of material such as rubber which is capable of flexing against the hull surface to provide an hermetic seal. The interior of both of the spiral casing 2 and the transition section 11 are each lined with an abrasion-resistant material 20 thereby prolonging their useful life.

A chute 21 is connected to the collection chamber for guiding the collected particles from the collection chamber to a conveying means. The conveying means comprises an endless conveyor having a circular conveyor housing 22 affixed to a frame portion 24 of the frame assembly 40 by means of a pair of plates 23. A circular conveyor runner 25 is rotatably mounted within the conveyor housing 22 as best seen in FIG. 5. The conveyor runner 25 revolves within the conveyor housing 22 and four guide rollers 26 are symetrically positioned about the conveyor runner 25 and engage therewith to guide the runner along its cirular path of travel.

As seen in FIG. 5, the outer wall portion of the conveyor housing 22 is provided with suitable openings which accommodate therein the guide rollers 26 whereupon the guide rollers frictionally engage with the outer periphery of the conveyor runner 25. A drive motor 27 is connected to one of the guide rollers 26 to rotationally drive same at a speed of from 5 to 10 meters per minute and the driven guide roller thus frictionally and rotationally drives the conveyor runner 25.

A pluraltiy of partitioning blades 28 are connected to the conveyor runner 25 in circumferentially spacedapart relationship around the entire inner periphery of the runner. The partitioning blades are each inclined in a forward direction relative to the direction of rotation of the conveyor runner 25 and as seen in FIG. 5, the conveyor runner 25 is rotationally driven in a clockwise direction as depicted by the arrow F. The partitioning blades 28 partition and divide the conveyor runner into a series of circumferentially spaced-apart conveying chambers each of which successively moves beneath the outlet of the chute 21 during operation of the device to receive therefrom the used abrasive particles. The blades 28 are positioned every 15 to 20 centimeters apart and have a forward inclination chosen in dependence upon the speed of the conveyor runner as well as the opening angle of the hopper 8 so that the abrasive particles collected in the individual openedend conveying chambers may spill by gravity into the hopper 8 during rotation of the conveyor runner 25. In this manner, abrasive particles are continuously fed into the centrifugal projector 1 and impelled against the hull surface to perform a cleaning and polishing action and then the spent abrasive particles are collected and recycled back into the hopper for subsequent use. A bucket conveyor, screw conveyor, or the like may be used in practicing the present invention but the conveyor disclosed in FIGS. 3-5 has proven to be very effective and is the preferred type.

In accordance with the present invention, Separating means is connected to the main frame or frame assembly 40 for separating the reusable abrasive particles from the nonreusable abrasive particles and other waste particles. As seen in FIGS. 4 and 5, the separating means comprises a suction pump 29, preferably comprising a rotary air blower, and the suction pump has an input side connected to a duct and an output side connected to a cyclone separator 31. The duct 30 communicates at two locations with the collection chamber through the chute 21 and during operation of the suction pump, a negative pressure or suction is developed in the duct 30 and is transmitted through the chute 21 to the outlet end of the collection chamber. Thus the abrasive particles flowing downwardly through the

passages

14 and 15 as well as the scales, paint, dust and other waste particles flowing into the

collection chamber

13, 16, l7, 18 all flow downwardly through the chute 21 and past the suction zone established by the suction pump 29 and the duct 30. The suction pump 29 has a capacity of approximately cubic meters per minute and therefore sufficient suction is created to suck the light-weight scales, paint chips and dust and the like into the duct 30 and through the suction pump 29 to the cyclone separator 31 while the heavier abrasive particles flow downwardly through the chute 21 into the conveying chambers on the conveyor runner 25.

The cyclone separator 31 includes a cyclone-shaped housing 32 containing therein wire mesh which effectively separates the scales, paint chips, dust, and other small exfoliated particles and the separated particles fall downwardly by gravity into a dust container 33. The exhaust air exhausting from the cyclone separator 31 is discharged through an exhaust duct 34. A bag filter may be interchangeably used for the wire mesh within the cyclone separator 31. A drive motor 35 is coaxially mounted with the suction pump 29 and rotationally drives the suction pump during operation of the device.

Also mounted on the frame assembly is rustremoving means 36 for removing rust and other oxides from the hull surface. The rust-removing means comprises a subframe assembly composed of L-shaped

section

37, 38 connected to the main frame assembly in back-to-back relationship as shown in FIG. 4. A set of needle descaling tool 39 are affixed to the subframe assembly and are positioned in staggered or zig-zag relationship along two rows. Each row of needle descaling tool or devices preferably extends at least a distance equal to the width of the opening 12 so that the area treated by the rust-removing means is approximately equal to the area subjected to the abrasive cleaning action. Each needle descaling device 30 is connected to an air hose so that compressed air is delivered to the hull surface adjacent the needle descalers to effectively flow away removed dust. The individual air hoses are connected to a common supply hose which is connected to a source of compressed air installed exteriorly of the mobile cleaning and polishing apparatus. The constructional details of the needle descaling devices 39 do not constitute part of the present invention and therefore they will not be further described and it is understood that any conventional needle descaling devices may be employed, such as the mechanicallyreciprocated type, the pneumatically-driven type, etc.

Another feature of the present invention is the positioning means for positioning and maintaining the apparatus in close proximity to the surface to be cleaned while enabling the device to be moved relative to the surface so that the entire surface may be cleaned. For the purposes of illustration, two different types of positioning means are disclosed for effecting these results and one type is employed at the upper section of the device and the other type is employed at the lower section of the apparatus.

According to the first embodiment of the present invention the positioning means employed at the upper section of the apparatus comprises a horizontally extending subframe 43 connected to the main frame or frame assembly 40. A pair of sprocket wheels 44 are rotatably mounted on each end of the subframe and a set of endless roller chains 45 are wound around the sprocket wheels as shown in FIGS. 3 and 4. The roller chains 45 are each composed of two lines of rollers which frictionally engage with the hull surface during use of the apparatus and such will be described in more detail hereinafter. I

The endless roller chains 45 of the apparatus revolve around the sprocket wheels 44 and to ensure that the endless chains do not slacken, a guide frame 46 is connected to the subframe 43 to guide the path of travel of the roller chains intermediate the sets of sprocket wheel 44. The guide frame 46 comprises a pair of opposed spaced-apart channel beams and a series of guide bars 47 slidably extend through the flanges of each channel beam. Each guide bar 47 is provided with a collar at a location intermediate the flange of the channel beam and a compression spring 49 is positioned around the guide bar 47 in between the collar and one of the channel flanges and functions to bias the guide bar in a leftward direction as viewed in FIG. 4. A splined roller 59 is connected to the leftmost end of each guide bar 47 and a common plate member 48 is connected to the guide bars 47 in such a manner that the guide bars may both rotate and transiate relative to the plate member 48.

Each endless roller chain 45 is composed of a series of rollers 57 connected together in end-to-end relationship as seen in FIG. 3. Each roller 57 is mounted on frame member 58 for rotational movement about its longitudinal axis and the frame member 58 is provided with a row of parallel splines which engage with the splines on the roller 59 during advancement of the endless chains 45. One pair of sprocket wheels 44 is connected to a shaft 54 and a chain drive including a drive sprocket 55 and a drive motor 56 is employed to rotationally drive the shaft 54. By such a construction, rotational movement of the shaft 54 effects movement of the endless roller chains 45 around the sprocket wheels 44 and during movement of the endless roller chains, the parallel splines on the frame member 58 engage with and rotate the splined roller 59.

The positioning means further includes a set of plate members 52 each connected in opposed spaced-apart relationship to the plate member 48 by means of guide pins 50 and compression springs 51. The compression springs are disposed around the guide pins 50 and resiliently mount the plate members 52 upon the frame member 58. A set of magnets 53 are affixed respectively to the outside face of the plate members 52 in the first embodiment shown, five plate members 52 and five magnets 53 are employed. Each plate memberand-magnet combination is independently mounted upon the plate member 48 and may move towards and away from the plate member 48 due to the resiliency of the compression springs 51.

In accordance with the present invention, the magnets 53 are always maintained a slight distance away from the hull surface and this clearance is provided by the direct abutment of the rollers 57 with the hull surface. As seen in FIG. 4, the rollers 57 abut against the hull surface and are maintained thereagainst by the biasing springs 49 and while the rollers are in this position, the magnets 53 are maintained approximately two millimeters away from the hull surface.

The magnets 53 comprises magnet field generating means and generate a magnetic filed which coacts with the metallic hull to maintain and position the mobile device in its working position. The magnetic force of attraction between the magnets 53 and the hull is sufficiently strong to prevent the frame assembly 40 from moving away from the hull surface during operation of the centrifugal projector 1. The positioning means also possesses sufficient resiliency to absorb the vibrations imparted to the apparatus during operation of the centrifugal projector.

During operation of the positioning means, the drive motor 56 is energized to effect rotation of the endless roller chains 45 at a linear speed of approximately 4 meters per minute and due to the frictional engagement of the individual rollers 57 with the hull surface, the entire mobile apparatus is driven in a horizontal direction along the hull surface. As the apparatus advances along the hull surface, any irregularities or curved portions in the hull surface do not detrimentally affect the operation of the apparatus since the frame members 58 may move towards and away from the hull surface due to their splined connection. The plate member 48 is maintained against the face of the splined roller 59 due to the attractive force between the magnets 53 and the hull surface. Thus in this embodiment, the mobile device itself contains the source of motive power to advance the apparatus horizontally along the hull and due to the rotatable mounting of the rollers 57, the rollers may roll vertically along the hull thereby enabling the apparatus to be displaced vertically as well by an external source of motive power, such as by a crawler crane or a trolley as shown in FIGS. 1 and 2.

The first embodiment of the positioning means employed at the lower section of the apparatus comprises a base plate member 60 connected to the frame assembly 40 and a set of plate members 63 individually con nected to the base plate member 60 by means of guide pins 61 and compression springs 62. Each plate member 63 is independently and resiliently mounted upon the base plate member 60 and each plate member 63 may move relative to the base plate member independently of the other plate members. Magnetic field generating means is connected to the plate members 63 and as shown in FIGS. 3 and 4, the magnetic field generating means comprises a set of magnets 64.

Also connected to each plate member 63 is a set of ball casters and the ball casters are of conventional construction and include a rotatable ball member which makes rolling contact with the hull surface when the device is placed in its working position. The ball casters 65 also function to maintain the magnets 64 spaced apart a slight distance from the hull surface thereby preventing the magnets from directly contacting and adhering to the hull surface. In this embodiment, of the positioning means, the ball casters 65 permit the mobile device to roll along the hull surface in any direction and some external means such as a crawler crane or trolley must be employed to advance the apparatus.

The device also includes a set of fluid reciprocatory motor comprising pneumatic or hydraulic cylinders 66 connected in a symmetrical arrangement to the frame assembly 40 and each cylinder includes a piston reciprocally mounted therein. Each piston has a piston rod extending out of the cylinder and a cushioning member 67 is affixed to the end of each piston rod. The pistons are actuatable to alternately extend and retract their piston rods relative to their cylinders. The cushioning members are composed of elastic material such as rubber and function to absorb any shocks or impulsive forces occuring during operation of the device. The cushioning members 67 effectively stablize the device in its working position and prevent it from swinging outwardly and bumping into the hull surface thereby preventing damage to the apparatus.

Now, the second embodiment of the present invention will be described hereinafter.

As illustrated in FIG. 6, the main frame including two attraction travelling means, which frame is almost square in shape looking from a front is preferably sized about 2160 X 1830 m/m. It will be understood that the main frame including the attraction travelling means is not limited to the above-mentioned dimension but suitable changes in mechanical design may be carried out.

At a center position of a main frame 40 of the second embodiment, is placed a centrifugal projector l for impelling abrasive particles such as shots, grits or the like at high speed. This projector is constructed in such a manner that power of an electric motor 7 is transmitted to a main shaft supported by a bearing base 69 through a belt driving mechanism 68 so as to carry out a high speed polishing and cleaning operation on the surface to be cleaned.

In front of the centrifugal projector 1, almost completely air-tightly sealed casing 2 is disposed. In this casing 2, at an end of an extended line along which abrasive materials are projected, a projecting opening 12 is disposed which tightly contacts a surface of a metal plate C subjected to a cleaning and polishing operation. Direct below of the projecting opening 12, there is provided a recovery opening 70 for collecting all abrasive materials, rust, old paint or other waste matter which are descaled off the surface of the metal plate.

On a lower end portion of a duct 71 extending obliquely downward from the recovery opening 70, two

horizontal screw conveyors

72, 74 are located. This screw conveyor 72 is connected with a lower end of vertically positioned bucket conveyor 73. An upper outlet opening of the bucket conveyor 73 is connected with a second screw conveyor 74. In this manner, the abrasive particles used are adapted to effectively return to a hopper 75 disposed over the centrifugal projector l. The bucket conveyor 73 and the screw conveyor 74 are synchronously driven by means of the motor 79. Both the screw conveyor 72 and the bucket conveyor 73 are synchronously driven by directly connecting rotating shafts of the screw conveyor with the bucket conveyor.

The paint, rust, scale and other dusts mixed in the abrasive particles recovered from the recovery opening 70 passes through a screen situated on the way of their falling. They falls through the screen provided in a recovery duct 71 and absorbed to a bag filter 77 through a duct 76 and finally they are separated from each other. In the drawing, a reference numeral 78 is a blower for the bag filter.

Next, an attraction travelling means will be described hereinbelow. A mobile cleaning and polishing apparatus suspended from a crane must be closely contacted to an object or surface C subjected to the abrasive operation. Especially, the projecting opening 12 and the recovery opening 70 are to be tightly contacted to the surface of the metal plate so as to carry out a foundation treatment operation or cleaning and polishing at high speed and extremely efficiently, while said cleaning and polishing apparatus must be quickly moved from a working position to other position on the surface to be cleaned.

For the above said purposes, the adsorption travelling mechanism 80 is placed at both sides of the projecting opening 12 and the recovery opening 70.

According to the second embodiment of the presesnt invention, the mechanism uses a permanent magnet having considerable strength and arranged so as to make the apparatus to enable the apparatus to approach to the surface of the metal leaving a clearance of about 6 mm which is effective for magnetic force. Said magnetic force of the permanent magnet provided in the apparatus of the present invention is adapted to develop an attractive force which is sufficient to firmly attract and hold the apparatus in its working position. The adsorption travelling apparatus 80 further comprises a rotating roller 83 for enabling the apparatus of the present invention to laterally move along the surface to be treated by developing a friction force between the surface of the metal plate and the mechanism.

As best shown in FIG. 10, a roller assembly 83 is constructed in such a manner that multi-rollers 87 consisting of a plurality of roller elements are mounted on a circular frame 85 rotating around a main shaft 84. The rollers 87 respectively mounted on a sub-shafts 86 extending tangentially to said frame 85. The aforementioned roller assembly 83 is what is called a wholedirection roller. Accordingly, the apparatus of the present invention using the whole-direction rollers can be freely moved vertically and laterally on the surface of the structure.

To the

upper roller assemblies

83, 83, driving power of a motor 88 is transmitted so as to rotate them effectively. So that, the roller assemblies can be selftravelled in order to easily move the cleaning and polishing apparatus of the present invention laterally on the surface of the structure.

According to the second embodiment of the present invention, the motor 7 for impelling the abrasive materials such as shots against the surface being treated and the motor 79 for operating the screw conveyors and the bucket conveyor are preferably adapted to be remotely controllable as explained with reference to the first embodiment of the present invention.

It is of course understood that the cleaning and polishing apparatus of the present invention may include the same type of positioning means at both the upper and lower sections. If the embodiment used at the upper section is also used at the lower section, the apparatus has excellent horizontal mobility and may be easily horizontally moved without requiring an external source of power. If on the other hand, the apparatus employs the embodiment of the positioning means used at the lower section at both the upper and lower sections, then the apparatus has excellent mobility in any direction and may be advanced angularly as well as horizontally and vertically. It is also understood that electromagnets may be used in place of the permanent magnets shown in the drawings.

The invention has been described in conjunction with two particular embodiments and it is to be understood that obvious modifications and changes may be made without departing from the spirit and scope of the pres ent invention as defined in the appended claims.

What is claimed is:

l. A mobile cleaning and polishing apparatus comprising, a mobile main frame movable into a working position wherein same confronts and is spaced-apart from the surface of a structure to be cleaned, abrasive cleaning means mounted on said main frame including means defining an outlet for impelling abrasive particles through said outlet opening against a section of the surface to be cleaned to effect abrasive cleaning of the surface, collecting means mounted on said frame assembly and including means defining a collecting passage surrounding said outlet opening for collecting the abrasive particles scattered off the surface along with the removed scale and other waste particles, positioning means coacting with said main frame for positioning and maintaining said main frame in said working position during operation of both said abrasive cleaning means and said collecting means, said positioning means comprising magnetic field generating means connected to said main frame for generating during use of the apparatus of magnetic field coacting with the structure to be cleaned when same is composed of magnetic material to develop a magnetic force of attraction therebetween having sufficient strength to maintain said main frame in its working position during operation of said cleaning and collecting means, and a motive power for effecting movement of said main frame along the surface to be cleaned while maintaining same in confronting spaced-apart relationship therefrom by said magnetic field generating means during operation of said abrasive cleaning and collecting means.

2. A mobile cleaning and polishing apparatus according to claim 1, further comprising a needle descaling tool having a plurality of needles arranged to strike and remove scale and rust from the surface to be treated before an abrasive cleaning operation of the abrasive cleaning means is carried out on the particular section of the surface. a

3. A mobile cleaning and polishing apparatus according to claim 1, wherein said abrasive cleaning means includes a projector having a opening through which a blast of shot can be ejected to impinge on and clean the surface and blasting means for causing said blast to impinge on the surface.

4. A mobile cleaning and polishing apparatus according to claim 1, further comprising recovery means for recovering shot which has impinged on the surface and returning it to an inlet of said blast means, and defining means defining a recovery passage surrounding said outlet opening, said opening is in the form of two collection passages arranged beneath it.

5. A mobile cleaning and polishing apparatus according to claim 1, wherein said outlet opening is defined by resilient seals connected to the edges of the passages and the opening.

6. A mobile cleaning and polishing apparatus according to claim 1, wherein said positioning means includes a set of fluid reciprocatory motors mounted on said frame assembly and actuatable to extended state in order to make a spaced-apart relationship between the structure to be treated and the frame, and cushioning members affixed to respective ones of said fluid reciprocatory motors and cooperative therewith when in the extended state to engage with the structure to absorb impulsive forces transmitted during operation of the apparatus thereby holding and stabilizing said frame assembly in its working position.

7. A mobile cleaning and polishing apparatus according to claim 3, wherein said projector comprises a multi-bladed impeller to which shots can be fed and impelled towards said outlet opening.

8. A mobile cleaning and polishing apparatus as claimed in claim 7, wherein said impeller is carried on one end of a shaft joumalled in a main bearing, and a motor connected to drive the other end of said shaft.

9. A mobile cleaning and polishing apparatus as claimed in claim 7, further including a supply hopper disposed above said impeller and having a bottom discharge outlet through which shot can be fed to said impeller by gravityv 10. A mobile cleaning and polishing apparatus as claimed in claim 4, wherein said recovery means includes a conveyor system which collects shot and transfers it to said hopper. v

11. A mobile cleaning and polishing apparatus as claimed in claim 10, wherein said conveyor system comprises an annulus bucket conveyor of U-section, said annulus conveyor has a plurality of baffles arranged thereinside, the annulus being arranged so that it extends below the outlet opening and above said hopper, and the baffles being arranged at such an angle so that as said annulus is rotated, shot resting thereon between said baffles is carried to said hopper and discharged thereinto.

12. A mobile cleaning and polishing apparatus as claimed in claim 11, wherein said annulus is mounted in a similar shaped casting having gaps therein, and a roller disposed at each gap in driving engagement with said annulus.

13. A mobile cleaning and polishing apparatus as claimed in claim 12, further including a motor con nected to rotationally drive one of said rollers.

14. A mobile cleaning and polishing apparatus as claimed in claim 10, wherein said conveyor system includes two horizontal screws conveyors respectively situated above said hopper and below the outlet opening, and a bucket conveyor is vertically arranged so that it connects said screw conveyors to each other.

15. A mobile cleaning and polishing apparatus as claimed in claim 4, wherein said recovery means includes a suction system for separating broken shots and removed waste particles from whole shots.

16. A mobile cleaning and polishing apparatus as claimed in claim 15, wherein said suction system includes a blower having an input connected by suction lines to a part of said passage to create and upwardly flowing current of air during use of the apparatus allows whole shots to pass down said passages.

17. A mobile cleaning and polishing apparatus as claimed in claim 16, wherein said blowerhas an outlet connected to a filter whereby material entrained by the air is separated therefrom and passed to storage.

18. A mobile cleaning and polishing apparatus as claimed in claim 16, further including connecting means for connecting said blower inlet to said recovery passage.

19. A mobile cleaning and polishing apparatus as claimed in claim 1, wherein said positioning means includes a plurality of magnets mounted on the main frame and enabling the apparatus to be magnetically held in close contact with a steel or other magnetic surface.

20. A mobile cleaning and polishing apparatus as claimed in claim 19, wherein each magnet is individually mounted resiliently mounted on the frame of the apparatus.

21. A mobile cleaning and polishing apparatus as claimed in claim 20, further including carriages having rollers carrying a guide frame slidable relative to the main frame of the apparatus and means mounting each magnet on a backing plate urged resiliently outwards by spring bearing on said guide frame.

22. A mobile cleaning and polishing apparatus as claimed in claim 21, wherein each backing plate carries a plurality of rollers arranged so that its magnet is always spaced a short distance from the surface to be cleaned.

23. A mobile cleaning and polishing apparatus as claimed in claim 22, wherein each backing plate is attached to the main frame of the apparatus and spring loaded outwardly thereof.

24. A mobile cleaning and polishing apparatus as claimed in claim 23, wherein each spring surrounds a pin which carries a ball caster on its end remote from the main frame, the ball casters being arranged so that the magnet is always supported and maintained a small distance from the surface being cleaned.

25. A mobile cleaning and polishing apparatus as claimed in claim 1, further including a set of shock absorbers of resilient material mounted on said main frame and movable into contact with the surface to be cleaned.

26. A mobile cleaning and polishing apparatus as claimed in claim 1, further including a multi-roller means having a plurality of rollers arranged to facilitate movement of the apparatus up and down along the surface to be cleaned.

27. A mobile cleaning and polishing apparatus as claimed in claim 1, further including means on the main frame for attaching to a suspension cable or the like to suspend the apparatus adjacent the surface to be cleaned.

Claims

1. A mobile cleaning and polishing apparatus comprising, a mobile main frame movable into a working position wherein same confronts and is spaced-apart from the surface of a structure to be cleaned, abrasive cleaning means mounted on said main frame including means defining an outlet for impelling abrasive particles through said outlet opening against a section of the surface to be cleaned to effect abrasive cleaning of the surface, collecting means mounted on said frame assembly and including means defining a collecting passage surrounding said outlet opening for collecting the abrasive particles scattered off the surface along with the removed scale and other waste particles, positioning means coacting with said main frame for positioning and maintaining said main frame in said working position during operation of both said abrasive cleaning means and said collecting means, said positioning means comprising magnetic field generating means connected to said main frame for generating during use of the apparatus of magnetic field coacting with the structure to be cleaned when same is composed of magnetic material to develop a magnetic force of attraction therebetween having sufficient strength to maintain said main frame in its working position during operation of said cleaning and collecting means, and a motive power for effecting movement of said main frame along the surface to be cleaned while maintaining same in confronting spaced-apart relationship therefrom by said magnetic field generating means during operation of said abrasive cleaning and collecting means.

2. A mobile cleaning and polishing apparatus according to claim 1, further comprising a needle descaling tool having a plurality of needles arranged to strike and remove scale and rust from the surface to be treated before an abrasive cleaning operation of the abrasive cleaning means is carried out on the particular section of the surface.

8. A mobile cleaning and polishing apparatus as claimed in claim 7, wherein said impeller is carried on one end of a shaft journalled in a main bearing, and a motor connected to drive the other end of said shaft.

9. A mobile cleaning and polishing apparatus as claimed in claim 7, further including a supply hopper disposed above said impeller and having a bottom discharge outlet through which shot can be fed to said impeller by gravity.

10. A mobile cleaning and polishing apparatus as claimed in claim 4, wherein said recovery means includes a conveyor system which collects shot and transfers it to said hopper.

13. A mobile cleaning and polishing apparatus as claimed in claim 12, further including a motor connected to rotationally drive one of said rollers.

17. A mobile cleaning and polishing apparatus as claimed in claim 16, wherein said blower has an outlet connected to a filter whereby material entrained by the air is separated therefrom and passed to storage.