WO2003033165A2

WO2003033165A2 - Device for removing and sucking powders externally of one or more powder-drawing pipes

Info

Publication number: WO2003033165A2
Application number: PCT/IB2002/003597
Authority: WO
Inventors: Luigi Carlo Maria Volonte'
Original assignee: Volonte Luigi Carlo Maria
Priority date: 2001-10-16
Filing date: 2002-09-06
Publication date: 2003-04-24
Also published as: AU2002330686A1; WO2003033165A3; ITMI20012132A1; ITMI20012132A0; EP1469948A2; ATE393667T1; ES2305293T3; DE60226348D1; EP1469948B1; DE60226348T2

Abstract

Device for the removal and suction of powders from the outer surface of one or more powder drawing pipes in apparatus for powder painting/enamelling, in which said powder drawing pipes fluidically connect means to deliver the powders to one or more replaceablepowder containers and in which the pipes may be inserted into and extracted from the powder containers. The device comprises one or more scraper elements for the removal of powders deposited on said side surface and each of said scrapers is associated with the outer side surface of a single pipe so that each pipe and scraper element associated with it are mobile in relation to one another. The device also comprises means for suction of the removed powders from each scraper element.

Description

Title: "Device for removing and sucking powders externally of one or more powder-drawing pipes." Field of the invention The present invention relates to a device for the removal and suction of powders from the outer surface of pipes provided to draw these powders, in an apparatus for powder painting/enamelling. State of the art

These apparatuses for powder painting/enamelling usually comprises a spray booth, positioned inside which are suitable means to deliver the powders that coat the surface of the piece being coated, and a powder feed system including one or more replaceable powder containers and a pneumatic circuit to feed the powders from the containers to the nozzles of the delivery means. The coloured powders may therefore be fluidified and subsequently conveyed by suction from the replaceable containers to the delivery means. Apparatuses of this type are also normally equipped with one or more suction filtering systems which have the objective of disposing of the unused powders present in the booth during coating. More specifically, during use, one or more powder drawing pipes, of the aforesaid pneumatic circuit, are placed inside each replaceable container; the powders, possibly fluidified by a gas flow, are sucked up through these pipes to reach the delivery means. When the use of a specific powder or mixture of powders has terminated and therefore the container with the powders must be replaced, each powder drawing pipe is extracted from the corresponding container and the powders deposited inside and outside the pipe are removed before subsequent use of the apparatus.

Operations for' the removal and suction of the powders from the powder drawing pipes of the feed system are particularly. critical when it is necessary to replace the pigment or coating material. In fact, in this case these removal operations must be performed in an extremely accurate manner, to avoid undesirable contamination during subsequent coating, and therefore require the use of considerable resources and implementation times.

Therefore, in modern apparatuses for powder painting/enamelling, when the pigment or coating material requires to be changed by replacing the powder containers, an automatic device lifts the pipes from the containers so that, once extracted from the latter, the empty containers can be removed and the powder drawing pipes can be cleaned first removing the powders by means of a jet of pressurized air or other fluid and simultaneously sucking up the previously removed powders. In greater detail, to clean the insides of the powder drawing pipes in prior art nozzles are employed to distribute a flow of pressurized fluid which, positioned at the open ends of the pipes, send a jet of fluid inside the pipes to remove the powders deposited on the inner walls of the pipes. The removed powders may then be sucked up by the suction device of the spray booth. These operations are usually performed automatically by the painting/enamelling apparatus at the end of the coating operation.

Additionally, a compressed air gun is generally used to clean the outside of the pipes; this is operated manually by an operator who, by aiming the jet along the outer surface of the pipes, is able to remove the powder deposited on these surfaces. The removed powder, which tends to fall through gravity, is sucked up by a suitable filter system incorporated in the powder feed system.

This operation to clean the outside of the powder drawing pipes, in addition to being evidently time-consuming and requiring the use of resources, may also be somewhat ineffective as it is correlated to the ability and precision of the operator.

Moreover, the filter of the powder feed system, which to be efficient is usually of considerable size, requires the use of high powers to suck up the powders and frequent maintenance.

The considerable power required for suction is all the more reason why it does not seem to be practical to use a solution which simply employs the suction system incorporated in the spray booth of a suitable dimension to remove powders present on the outside of the powder drawing pipes.

Similarly, the use of nozzles in fixed position inside the powder feed system to send jets of fluid to the powder drawing pipes seems to be a structurally complicated solution, the efficacy of which is doubtful. Description of the invention The principal object of the present invention is to supply a device for the removal and suction of powders deposited on the outer surface of powder drawing pipes in a powder painting/enamelling apparatus which is efficacious and precise and which may be automated so that it is not excessively time consuming and does not require resources during utilization.

Another object of the present invention is to produce a device for the removal and suction of powders which is structurally simple and does not require additional suction devices to the suction device of the spray booth. Yet another object of the present invention is to provide a device, an apparatus comprising this device and a method for the removal and suction of powders which allow rapid replacement of empty powder containers when the pigment or coating substance require to be changed. These and other objects are attained by the present invention according to the claims in the first independent claim of the device, in claim 13 of the apparatus, in claims 14 and 16 of the method and in the other dependent claims. According to the present invention, the device for the removal and suction of powders from the outside of one or more powder drawing pipes in an apparatus for powder painting/enamelling, in which said powder drawing pipes fluidically connect suitable means to deliver powders to one or more replaceable powder containers and in which the pipes may be inserted into and extracted from the powder containers, comprises one or more scraper elements to remove the powders deposited on the side surfaces. Each of these scrapers is associated with the outer side surface of a single pipe so that each pipe and the scraper element associated with it are mobile relatively one to the other. The apparatus also comprises means for suction of the powders removed from each scraper element. The use of scraper elements acting on the outer side surface of the powder drawing pipes, thanks to relative sliding of the associated scraper - pipe, allows both highly efficient removal of the powders and the chance to automate the relative sliding of the scraper - pipe and hence the entire operation of removal and suction of the powders.

According to a preferred aspect of the present invention, the suction means of the device also comprise one or more inlet mouths for the fluid sucked up, each of which is associated with a single powder drawing pipe. In this way, the suction power required is reduced and it is possible to connect the inlet mouths of the fluid sucked up directly, or by means of ducts, to the suction system and to the filter of the spray booth. According to another aspect of the present invention, the device comprises a box-like support with a tubular shape equipped with through holes inside which the powder drawing pipes are inserted slidingly. The box-like element is fluidically connected to a suction device, so that the aforesaid through holes form the suction mouths associated individually with the powder drawing pipes. Moreover, the scraper elements are preferably annular and engage, at least partially, with the inner side surface of the through holes made in the box-like support. In this preferred embodiment of the invention, thanks to the simultaneous performance of the action for the removal of powders through scraping and of suction, obtained individually on each powder drawing pipe, considerable efficacy is obtained in the removal and suction of deposited powders without the need to use structurally complex contrivances or high suction powers.

According to a further aspect of the present invention, a method is obtained for the removal of powders, in an apparatus for powder painting/enamelling, from the outer surface of powder drawing pipes which can be respectively inserted into and extracted from the replaceable powder containers, comprising the subsequent phases:

- extracting the powder drawing pipes from their respective containers;

- scraping the outer surface of each pipe, to remove the powder deposited on said outer surface; - sucking the powder removed.

This method has proved to be particularly inexpensive and efficient. Brief description of the drawings

Described below, purely as a non-limiting example, are some preferred embodiments of a device for the removal and suction of powders according to the present invention, with the aid of the attached figures in which: figure 1 is a perspective view of a detail of a powder feed system presents in an apparatus for powder painting/enamelling; figure 2 is a detailed perspective view of a powder feed system provided with a device for the removal and suction of powders according to a particular aspect of the present invention; figure 3 is a sectional profiled schematic view of a detail of another powder feed system in an apparatus for powder painting/enamelling; figure 4 is a sectional front view of the detail in figure 2, showing a device for the removal and suction of powders according to a preferred aspect of the present invention; figure 5 is a perspective view of the terminal of a device for the removal and suction of powders according to another aspect of the present invention; figure 6 is a sectional perspective view of the terminal in figure 5; figure 7 is a perspective exploded view of the terminal in figures 5 and 6; and figure 8 is a sectional view of a through hole produced in the terminal of figures 5, 6 and 7. Description of the preferred embodiments

With reference to figures 1 and 2, these show a detail of a powder feed system part of an apparatus 1 for powder painting/enamelling of the type comprising two assemblies 3a, 3b of powder drawing pipes, or suction pipes, each of which is used to fluidically connect a powder container, drum or box, (not shown) to means 2 to deliver the powders for the surface coating of a piece being coated. Each assembly 3a and 3b of powder drawing pipes is designed to be inserted into a powder container during coating and extracted from this container at the end of coating.

Figure 1 also shows, one for each pipe, distribution nozzles 4 with the function of sending a jet of pressurized fluid inside the pipes of the assemblies 3a, 3b, in order to remove the powder deposited inside these pipes during the operation to clean the apparatus 1. Each assembly 3a, 3b, as shown in figure 1 b, comprises a plurality of powder drawing pipes 5a, 5b, 5c, 5d, 5e, 5f, each of which is inserted slidingly inside respective through holes produced in a cleaning terminal 9 with which the device for removal and suction of powders according to the present invention may be equipped. The terminal 9, as shall be described below, supports a plurality of scrapers of the outer surface of these pipes 5a-5f and is connected to means for suction of the removed powders. Figures 3 and 4 show a plurality of pipes 5' a, 5'b, 5'c of a system to feed powders in an apparatus for powder painting/enamelling inserted into a container 6 for powders 8. On the outside of the container 6, in correspondence with each powder drawing pipe 5' a, 5'b, 5'c, is a respective nozzle 7a, 7b and 7c for cleaning the inside of the pipes 5'a, 5'b, 5'c.

The pipes 5'a, 5'b, 5'c, during the phases to coat a piece, are fed with a suction flow capable of drawing the powders 8 from the container 6 and directing them towards special nozzles in the aforesaid means to deliver powders (totally analogous to those indicated with 2 in figure 1 ). These pipes 5'a, 5'b, 5'c may also be moved in the direction indicated by the arrow A in relation to the container 6 in order to allow the pipes 5'a, 5'b, 5'c to be inserted into and extracted from the container 6 when it is necessary to change the colour or coating material and it is hence necessary to replace these powder containers.

Moreover, as shown in figure 4, the powder drawing pipes 5'a, 5'b, 5'c are connected, according to a preferred aspect of the present invention and analogously to what is shown in figure 2, to a terminal 9' of a device for the removal and suction of the powders deposited on the outside of the pipes 5'a, 5'b, 5'c. The terminal 9', as shall be explained below, is preferably connected, by a duct 16, to a suction device not shown and may be moved, in the direction indicated by the arrow B, in relation to the pipes 5'a, 5'b, 5'c. Alternatively, the terminal 9' may remain fixed, while the pipes 5'a, 5'b, 5'c may move in relation to it in the direction indicated by the arrow B. The suction device to which the terminal 9' is fluidically connected may be the same one as the spray booth. A more detailed description shall now be given of a device for the removal and suction of powders from the outer surface of powder drawing pipes, according to a preferred aspect of the present invention, with reference to a terminal 9, shown in figures from 5 to 8 and analogous to the one shown in figure 2 and in figure 4, with which this device may be equipped. The device of the present invention for the removal and suction of powders from the outer surface of powder drawing pipes, comprises one or more scraper elements 12, each of which is associated, slidingly, with the outer side surface of a powder drawing pipe 5a, 5b, 5c, 5d or 5f. Relative movement of each scraper element 12 in relation to the associated powder drawing pipe, or vice versa, allows the removal of the powders that have deposited during coating on the outer surface of the powder drawing pipes 5a-5f. Advantageously, the scraper elements 12 (see figure 7 in particular) have an annular shape and are of a size to encircle, in contact, the associated powder drawing pipe 5a, 5b, 5c, 5d, 5e or 5f. These elements 12 may be made of flexible material, such as rubber, to prevent abnormal wear from occurring on the outer surface of the pipes 5a-5f and to guarantee an efficacious action of abrasion, or scraping, of the powders.

The device of the present invention is also equipped with means for suction of the powders removed which may be connected to prior art suction systems present in the spray booth. Nonetheless, the device of the present invention may be adapted to powder feed systems equipped with their own suction system, which is additional in relation to the one of the spray booth.

In the case in which the device of the present invention is installed on pre-existing painting/enamelling apparatus, and in the case in which this apparatus has the aforesaid additional suction systems of the feed system, the present invention provides only the scraper elements 12, fitted so that there is relative motion between the pipes 5a-5f and the scraper elements 12, for the removal of powders, while it exploits the pre-existing suction system for the suction of these powders. On the contrary, in the case in which the device of the present invention is equipped with its own suction means connectable to the suction device of the spray booth, as shown in the figures, the suction means comprise mouths 1 1 , 14 slidingly coupled to the powder drawing pipes 5a-5f and fluidically connected to this suction device (not shown). In greater detail, these inlet mouths of the sucked up fluid 1 1 , 14 are shaped to individually encircle the powder drawing pipes 5a-5f and engage with the outer surface of the latter so that each pipe 5a, 5b, 5c, 5d, 5e or 5f and each inlet mouth 1 1 , 14 is mobile in relation to one another. In a preferred embodiment of the present invention, this relative movement, which favours suction of the powders deposited on the outside of the powder drawing pipes 5a-5f, envisages that the powder drawing pipes are mobile, while the inlet mouths 1 1, 14 are fixed in relation to the surface on which the apparatus rests. The device for the removal and suction of powders also comprises a box-like element 10 designed to confine the powders removed by the action of the scrapers 12. This box-like element 10, tubular in shape, is associated with the powder drawing pipes 5a-5f so that relative motion is possible between the element 10 and the powder drawing pipes.

In the preferred embodiment of the present invention, shown in figures 5-8, the box-like element 10 has through holes 1 1 , 14 inside which the powder drawing pipes 5a-5f are inserted slidingly and an end opening 13 designed to be fluidically connected to a suction device (not shown) for example, by means of a pipe 16 (see figure 4). These through holes 1 1 , 14, thanks to the connection of the box-like element 10 to a suction device, form the inlet mouths of the sucked up fluid, each of which is associated with a powder drawing pipe 5a-5f. The inner surface of the top opening 1 1 of each of the through holes produced in the element 10 engages integrally with one of the annular scraper elements 12, as can be seen in figure 6, and each of the scrapers 12 is held in the relative seat 11 of the through holes in the box-like element 10 by a holding plate 15. Connection of the scrapers 12, the inlet mouths 1 1 , 14 of the sucked up fluid and the box-like element 10 to confine the powders, allows simultaneous operations to scrape the powders deposited on the outer side surface of the pipes, or suction pipes, 5a-5f, and to draw and suck up the removed powders. According to a preferred aspect of the present invention, as shown in figure 8, each of the through holes is formed of two openings 1 1 and 14 produced on opposite sides of the box-like element 10. The two openings 1 1 and 14, as described above, have a diameter that allows a powder drawing pipe 5a, 5b, 5c, 5d, 5e or 5f to be inserted slidingly and the top opening 11 is shaped to hold an annular scraper 12 in place.

Preferably, the two openings 1 1 , 14 have inner surfaces at least partially truncated-cone shaped, so that when connected to a pipe 5a, 5b, 5c, 5d, 5e or 5f a weak Venturi effect is created, capable of holding back the powders removed by the scrapers 12.

The use of the device illustrated in an apparatus for powder painting/enamelling when it is necessary to remove and suck up the powders deposited on the outside of the powder drawing pipes, in the phase to replace the powder containers to change colour or coating material, this use being the method for replacing the colouring pigment or coating material according to the present invention, is described below.

Upon termination of the phase of coating the surface of the piece, the powder drawing pipes 5a-5f or 5'a-5'c are extracted from the powder container 6 and the latter is removed. These powder drawing pipes 5a-5f or 5'a-5'c are then cleaned by removal and suction of the powders deposited both on their inner surface and their outer surface. Finally, the powder container is replaced with a new container and the pipes 5a-5f or 5'a-5'c are inserted into the container again to start a new coating operation.

According to prior art, the inside of the pipes 5a-5f or 5'a-5'c are cleaned by a jet of pressurized fluid, delivered by the nozzles 4 or Va¬

To clean the outside of the powder drawing pipes 5a-5f or 5'a-5'c, according to the method for removal and suction of the powders of the present invention, the following operations are performed:

- scraping of the outer side surface of the pipes 5a-5f or 5'a- 5'c, thanks to contact with interference between the scraper elements 12 and the outer side surface of the pipes 5a-5f or

5'a-5'c; and

- suction, preferably simultaneously to scraping, of the powder removed by the scrapers 12, through the inlet mouths 1 1, 14 of the sucked up fluid. In particular, the operations described above may be performed, with reference to figure 2, by moving the pipes 5a-5f downwards, in the direction indicated by the arrow C, and keeping the terminal 9 fixed, and applying a suction flow inside the box-like element 10. In this way, the powder removed by the mechanical action of abrasion (scraping) by the annular scraper elements 12 is confined by the box-like element 10 and simultaneously sucked up by the inlet mouths 11 , 14 to then be filtered by prior art means. This method for the removal and suction of powders from the outer surface of powder drawing pipes 5a-5f has proved to be extremely efficacious and inexpensive compared with the manual method used in prior art. In fact, the method established by the present invention may easily be automated and is therefore extremely fast and economically advantageous. Moreover, the operation of scraping and simultaneous suction of the powders prevents them from being dispersed in the environment after removal, which would make high suction power necessary. The device for removal and suction of powders according to the present invention, therefore, in addition to being structurally simple, may be easily operated automatically by suitable control means and does not require additional suction powers to those of the suction system of the spray booth.

Claims

CLAIMS 1. Device for the removal and suction of powders from the outside of one or more powder drawing pipes in an apparatus for powder painting/enamelling, in which said powder drawing pipes fluidically connect means to deliver powders to one or more replaceable containers of said powders, and said one or more pipes may be inserted into and extracted from said one or more containers, characterized in that it comprises one or more scraper elements, each of which is associated with the outer side surface of one of said one or more powder drawing pipes, for the removal of powders deposited on said side surface, and means for suction of the powders removed from each of said scraper elements, each pipe and the scraper element associated to it being mobile in relation to one another.

2. Device as claimed in claim 1, characterized in that said means for suction comprise one or more inlet mouths of the sucked up fluid, each of which is associated with a single powder drawing pipe.

3. Device as claimed in claim 2, characterized in that each of said one or more pipes is inserted into the inlet mouth of the sucked up fluid to which it is associated and that each mouth and each associated pipe are mobile in relation to one another.

4. Device as claimed in any one of the previous claims, characterized in that said scraper element is annular and encircles the side surface of the associated pipe.

5. Device as claimed in claim 3 and 4, characterized in that each of said one or more annular scrapers engages integrally with the inner surface of one of said one or more inlet mouths.

6. Device as claimed in claim 3, 4 or 5, characterized in that each of said one or more mouths and/or each of said one or more scraper elements have an inner surface engaging with the associated powder drawing pipe at least partially truncated-cone shaped.

7. Device as claimed in any one of the previous claims, characterized in that it comprises at least one box-like element with a tubular shape to confine the removed powders.

8. Device as claimed in claim 2 and 7, characterized in that said boxlike element comprises one or more through holes, inside each of which one of said one or more powder drawing pipes engages slidingly, said one or more through holes forming said suction mouths.

9. Device as claimed in claim 7 or 8, characterized in that said box-like element also comprises an opening for fluidically connecting with at least one suction device.

10. Device as claimed in claim 9, characterized in that said at least one box-like element is integral with one of the replaceable powder containers and that said powder drawing pipes are mobile in relation to said containers.

1 1. Device as claimed in any one of the previous claims, characterized in that it is operated, through relative motion in relation to said one or more powder drawing pipes, by automatically or manually controlled motor means.

12. Device as claimed in any one of the previous claims, in which said means to deliver the powders are confined in a spray booth equipped with a suction system, characterized in that said means for suction of the powders are placed in fluidic connection with said suction system of the spray booth.

13. Apparatus for powder painting/enamelling of the type comprising means to deliver the powders placed in fluidic connection with one or more powder drawing pipes, said one or more pipes which may be inserted into and extracted from respective one or more replaceable powder containers, characterized in that it comprises at least one device for the removal of powders from the outside of said one or more powder drawing pipes as claimed in any one of the previous claims.

14. Method for the removal of powders from the outside of powder drawing pipes for powders which may be inserted into and extracted from respective one or more replaceable containers of said powders, said pipes being part of an apparatus for powder painting/enamelling, the method comprising the subsequent phases:

- extracting said one or more powder drawing pipes from their respective containers;

- scraping the outer surface of each of said one or more pipes, to remove the powder deposited on said outer surface;

- sucking the removed powder.

15. Method as claimed in claim 14, in which said phase of sucking the removed powder is simultaneous to the phase of scraping the outer surface of each of said one or more pipes.

16. Method for replacing the colouring pigment or coating material in apparatus for powder painting/enamelling of the type comprising means to deliver powders fluidically connected with one or more powder drawing pipes of the powders, said one or more pipes which may be inserted into and extracted from one or more respective replaceable containers of said powders, characterized in that in comprises the subsequent phases: extracting said one or more powder drawing pipes from their respective containers; scraping the outer surface of each of said one or more pipes to remove the powder deposited on said outer surface; sucking the removed powder; sending a jet of pressurized fluid inside said one or more powder drawing pipes to remove the powders from the inside; sucking the removed powders from the inside of said one or more powder drawing pipes; replacing the used containers with new containers of powders with different pigment or different coating material; inserting said one or more powder drawing pipes inside the new containers.