POWDER SIEVING APPARATUS FOR POWDER COATING SYSTEM

Abstract

This invention relates to a powder sieving apparatus for a powder coating system and a powder suction system thereof. the present invention provides a powder sieving apparatus for a powder coating system having a powder spray gun, a powder suction pump assembly, and a powder container/hopper. As per the present invention, the said sieving apparatus comprises a housing having at least one outlet connected to a suction side of the powder suction pump and an inlet connected to a suction pipe dipped in the powder container, a cylindrical sieve having a sieve mesh adapted within the housing dividing the housing into an inner and outer compartments, a brush holder rotatably and/or oscillatingly adapted in the inner compartment of the housing for cleaning the cylindrical sieve. The present siveing apparatus provides freshly sieved powder free of large impurities and the powder particles and presented to the charging device such as a powder spray gun and the particles are thus charged better resulting in substantially and better transfer efficiency and this results in lower powder consumption.

Claims

1. A powder sieving apparatus for a powder coating system having a powder spray gun, a powder suction pump assembly, and a powder container/hopper, the said sieving apparatus comprising: a housing having at least one outlet connected to a suction side of the powder suction pump and an inlet connected to a suction pipe dipped in the powder container; a cylindrical sieve within the housing dividing the housing into two compartments, an inner compartment connected to the inlet of the housing and outer compartment connected to the outlet of the housing, said cylindrical sieve having a sieve mesh through which powder is sucked by the powder suction pump from inner compartment to the outer compartment; and a brush holder rotatably and/or oscillatingly adapted in the cylindrical sieve, said brush holder has a plurality of bristles or wipers for scrubbing inner surface of the sieve mesh to keep the sieve mesh unclogged and clean.

2. The powder sieving apparatus as claimed in claim 1, wherein the cylindrical sieve is held fixedly or rotatably within the housing.

3. The powder sieving apparatus as claimed in claim 2, wherein the cylindrical sieve is configured to rotate at differential speed in the rotational direction or opposite direction of the brush holder.

4. The powder sieving apparatus as claimed in claim 1, wherein the brush holder is hollow and comprises a plurality of nozzles or holes for spraying pressurised air over the surface of sieve mesh for skimming and washing the sieve mesh along with the bristles or wipers of the brush holder to prevent clogging and to ensure continuous flow of freshly sieved smooth flowing powder through the powder coating system.

5. The powder sieving apparatus as claimed in claim 4, wherein the brush holder comprises the plurality of rows of plurality of bristles or wipers and a plurality of rows of the nozzles or holes provided between the rows of the bristles or wipers, so the scrubbing and air wash takes place simultaneously.

6. The powder sieving apparatus as claimed in claim 4, wherein the brush holder includes the plurality of rows of the bristles or wipers, and the nozzles or holes are provided between the bristles or wipers, so the scrubbing and air wash takes place simultaneously.

7. The powder sieving apparatus as claimed in claim 1, wherein the brush holder is rotated and/or oscillated by a motor.

8. The powder sieving apparatus as claimed claim 1, wherein the apparatus is adapted vertically or angularly on the powder coating system for allowing falls back of non-sieved powder in the container.

9. The powder sieving apparatus as claimed in claim 8, wherein the apparatus is adapted at an angle preferably above 42 degrees.

10. The powder sieving apparatus as claimed in claim 1 wherein the housing comprises a plurality of outlets for adapting suction pump on each outlet.

11. The powder sieving apparatus as claimed in claim 1, wherein the said apparatus is connected removably to the suction side of the powder suction pump.

12. The powder sieving apparatus as claimed in claim 1, wherein the said apparatus is integrated with the powder suction pump or inbuilt in a powder suction pump(s) by combining housing of the powder sieving apparatus with the body of the powder suction pump(s) to form a single integrated unit.

13. A powder suction system comprising: a powder sieving apparatus as claimed in claim 1, said powder sieving apparatus having a plurality of outlets and a single inlet connected to a suction pipe dipped in the powder container; and a suction pump mounted removably or fixedly on each outlet of the powder sieving apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0023] FIG. 1A shows a conventional/prior powder suction pump assembly;

[0024] FIG. 1B shows a conventional/prior powder coating system;

[0025] FIG. 2 shows an assembled view of a powder sieving apparatus in accordance with an embodiment of the invention;

[0026] FIG. 3. shows an exploded view of components of the powder sieving apparatus as shown in FIG. 2;

[0027] FIG. 4 shows flow of air and powder through the powder sieving apparatus in accordance with the invention;

[0028] FIG. 5 shows a powder coating system incorporating the powder sieving apparatus in accordance with an embodiment of the invention; and

[0029] FIG. 6 shows a powder sieving apparatus according to an embodiment of the present invention having multiple outlets; and

[0030] FIG. 7 shows a powder coating system having a powder sieving apparatus of the present invention shown in FIG. 6.

DETAIL DESCRIPTION OF THE INVENTION

[0031] In general, the present invention provides a powder sieving apparatus for a powder coating system having a powder spray gun, a powder suction pump assembly, and a powder container/hopper. As per the present invention, the said sieving apparatus comprises a housing having at least one outlet connected to a suction side of the powder suction pump and an inlet connected to a suction pipe dipped in the powder container, a cylindrical sieve having a sieve mesh adapted within the housing dividing the housing into an inner and outer compartments, a brush holder rotatably and/or oscillatingly adapted in the inner compartment of the housing for cleaning the cylindrical sieve.

[0032] According to the present invention, the inner compartment of the housing formed by cylindrical sieve is connected to the inlet of the housing and the outer compartment of the housing connected to the outlet of the housing. The powder pump is connected to the outlet of the housing and the powder movement from the container takes place due to suction by the powder suction pump from the container to the inner compartment and out the outer compartment through the sieve mesh of the cylindrical sieve. According to an embodiment of the present invention, the cylindrical sieve may hold fixedly within the housing. According to another embodiment of the present invention, the cylindrical sieve may be adapted rotatably within the housing at a differential speed with the rotating brush holder.

[0033] According to the present invention, the said brush holder may have a plurality of bristles for scrubbing the inner surface of the sieve mesh to keep the sieve mesh unclog and clean. According to one another embodiment of the present invention, the brush holder may comprise a plurality of wipers instead of bristles wherein wipers are made of a different soft materials for scrub cleaning the inner surface of the mesh.

[0034] According to an embodiment of the present invention the brush holder includes at least one row of plurality of bristles for scrubbing the inner surface of the mesh.

[0035] According to another embodiment of the present invention, the brush holder may be hollow and may comprises plurality of nozzles/holes to permit pressurised air to flow over the sieve mesh surface to clean and keep the sieve mesh unclog as well as to provide the secondary or carrier air for transporting powder out smoothly through the gun.

[0036] According to an embodiment, the brush holder may include a plurality of rows of the bristles or wipers and a plurality of rows of the nozzles or holes provided between the rows of the bristles or wipers.

[0037] According to another embodiment, the brush holder may include a plurality of rows of the bristles or wipers and the nozzles or holes are provided between the bristles or wipers so the scrubbing and air wash action takes place almost simultaneously.

[0038] According to the present invention, the powder sieving apparatus can be adapted vertically or angularly for allowing the non-sieved material to fall back in the container. Preferably, the powder sieving apparatus may be adapted at an angle greater than 42 degrees with the horizontal axis for creating a slide for the non-sieved powder, and stray contaminants.

[0039] According to an embodiment of the present invention, the said apparatus may be connected removably to the suction side of the powder suction pump. As per another embodiment, the said apparatus may be integrated with the powder suction pump.

[0040] According to an embodiment of the invention, a powder suction pump(s) can be manufactured with an inbuilt powder sieving apparatus of the present invention by combining housing of the powder sieving apparatus with the body of the powder suction pump(s) to form a single integrated unit.

[0041] According to the present invention, the compressed air sprayed onto the sieve mesh along with scrubbing by the brush keeps sieve mesh de-clogged and also acts as secondary air that aids the smooth movement of the powder through the de-clogged sieve mesh, powder suction pump and hose and thus ensures that the powder is uniformly emitted out of the spray gun. Thus, this compressed air itself acts as the secondary air thereby eliminates the need for a separate compressed air inlet for the secondary air of the powder suction pump assembly, whilst keeping the sieve de-choked for smooth flow of powder continuously over long periods. The powder sieving apparatus cleans the sieve mesh physically and continuously with the brush along with carrier air, thereby the powder sieving apparatus of the present invention ensures continuous, smooth, and even flow of powder from even coagulated and impurity laden powder over long periods. There may be no need to stop work and clean the sieve or the apparatus during the working shift.

[0042] Referring FIG. 2 shows a powder sieving apparatus (100) for a powder coating system according to the preferred embodiment of the present invention and FIG. 3 shows an exploded view of the preferred embodiment of the powder sieving apparatus (100) shown in FIG. 2.

[0043] As shown in FIGS. 2 and 3, the powder sieving apparatus (100) comprises a housing (110A, 110B, 110 C), a cylindrical sieve (120) and a brush holder (130).

[0044] As shown in FIG. 3, the housing includes a top body (110A), a main body (110B), and bottom body (110C). The main body has one outlet (107), which acts as an outlet for powder and air and is connected to the powder suction pump (110) The bottom body (110C) of the housing has an inlet (102) for powder connected to the suction pipe thereby the powder sieving apparatus (100) establish connection between the powder pump and the suction pipe. The bottom body (110C) has one or more air inlets (104) for the secondary/carrier air to enter the brush holder (130) through the guide bush (132).

[0045] As shown in FIGS. 3 and 4, the cylindrical sieve (120) has a sieve mesh of a predetermined mesh size and a person skilled in the art can easily determine or select the mesh size of the sieve mesh based on the coating to be given on the subject. The cylindrical sieve (120) is adapted within the main body which divides the main body of the housing into two compartments namely inner compartment (103) and outer compartment (108). The inner compartment (103) is connected to the inlet (102) of the housing and the outer compartment (108) is connected to the outlet (107) of the housing. According to the present invention, the cylindrical sieve may be held fixedly or rotatably within the housing. When the cylindrical sieve is held rotatably within the housing, the cylindrical sieve is configured to rotate either at a differential speed in the rotational direction of the brush holder or in the opposite direction of the brush holder. A person skilled in the art can easily understand and make out the gear mechanism required to rotate the cylindrical sieve at the differential speed in the rotational direction of the brush holder or in the opposite direction of the brush holder, hence no need to explain in detail.

[0046] The brush holder (130) as shown in FIGS. 2-5 is adapted rotatably with the help of guiding bush (132) in the cylindrical sieve (120). The brush holder (130) as shown in FIGS. 2 and 3 comprises four rows of plurality of bristles (134) for scrubbing inner surface of the sieve mesh and four rows of nozzles or holes (136) for spraying pressurised carrier air over the surface of sieve mesh to keep the sieve mesh unclog and clean. Alternatively, the brush holder can be adapted moving up-down to clean the cylindrical sieve. Alternatively, brush holder may comprise a plurality of wipers for scrubbing inner surface of the sieve mesh.

[0047] As shown in FIGS. 2-5, the brush holder is rotated with the help of motor (105) adapted on the top body of the housing. Generally, the rotating speed of the brush holder is between 35 and 60 RPM depending on the application. It may be kept higher depending on stickiness and type of powders like powders with aluminum particles used to produce metallic finishes.

[0048] As shown in FIG. 4, the carrier air is guided through the guide bush (132) into the brush holder for spraying over the sieve mesh though the nozzles (136).

[0049] FIG. 5 shows that a powder coating system (300) comprising a powder suction pump integrated with the powder sieving apparatus (100) and the suction pipe (210) according to the present invention connected between a powder spray gun (310) and a powder container (310). According to the present invention, the powder suction pump may be integrated fixedly or removably.

[0050] According to further embodiment of the present invention, the housing of the powder sieving apparatus may have a single inlet for powder and a plurality of outlets for connecting with the plurality of the suction pumps. Referring FIG. 6 shows another embodiment of the present invention wherein a powder sieving apparatus (200) has one inlet (202) for connecting to a suction pipe dipped in the powder container and four outlets at a predetermined positions connected to the four suction pumps (212, 214, 216, 218) allowing to connect with four powder spray guns. Referring FIG. 7 shows the powder sieving apparatus (280) adapted in an automatic powder coating system (200). As shown in FIG. 7, the powder coating system (200) comprises the powder sieving apparatus having one suction pipe dipped in the powder container (276) and four suction air lines (272) are connected to four suction air pumps adapted to the four outlets of the powder sieving apparatus (276). The carrier air (274) is connected to the powder sieving apparatus (290) of the present invention which acts as a secondary air for each outlet along with skimming and washing the sieve mesh. Hence there is no need for a secondary or carrier air controller as a common air controller can supply sufficient secondary or carrier air to the nozzles on the brush holder. This saves on the use of multiple secondary or carrier air controllers. In a method of operation FIG. 4 shows flow of powder and air through the sieving apparatus of the present invention. The powder to be coated is kept in fluidized state in the container by compressed air through an air inlet (330) under a porous plate on which the powder rests. The powder is sucked through the suction pipe (210) with the help of the powder suction pump and passes though the sieving apparatus (100) of the present invention. The powder sucked by a suction force created by the primary air of the powder suction pump, is forced through the cylindrical sieve of the sieving apparatus. The brush holder rotates by the motor continuously to scrub the inner surface of the mesh sieve and the nozzles provided on the brush holder sprays the carrier air onto the sieve mesh thereby keeping the sieve mesh clean and de-clogged. Further, while it is known that the carrier air can be simply introduced in the powder path, however in the present invention as this carrier air is injected through the nozzles on the rotating brush holder, it helps to clean and de-clog the sieve mesh and also after cleaning the sieve mesh, aids in a smooth powder movement through powder hose and powder spray gun creating uniform even flow of the powder and air.

[0051] In all cases the powder filtered through the powder sieving apparatus of the present invention is free flowing powder which will be charged by the powder spray gun for coating onto a workpiece and the powder lumps and contaminants which does not pass through the sieve mesh falls back into the powder container.

[0052] The present sieving apparatus provides freshly sieved powder free of large impurities and the powder particles which are distinctly separated and presented to the charging device such as a powder spray gun and the particles are thus charged better resulting in substantially and better transfer efficiency and this results in lower powder consumption, and this is easily demonstrated during operation. The smaller mass of the individual powder particles versus the lumped powder particles makes them more tenable to easily accept an electrostatic charge. The distinctly separated powder particles of the sieved powder ensure a superior powder cloud emitted out of a spray gun and a more even and smooth powder flow with better uniformity and improved deposition efficiency. The present scrub clean and air-wash powder sieving apparatus is a non-vibrating sieving apparatus which eliminates wear and tear of the apparatus and ensures minimal maintenance with continuous flow in real time.

[0053] The sieving apparatus including parts such as housing, brush holder, guide bush and the like can be preferably made of plastic or metal. The carrier air can be of a different pressure or different air volume and numerous modifications and adaptations may be made thereto without departing from the spirit and scope of invention. The sieving apparatus of the present invention can be easily adapted to the presently available powder coating systems. Further, a powder suction pump or suction pipe can be manufactured with inbuilt powder sieving apparatus of the present invention by combining housing of the scrub clean and air-wash powder sieving apparatus with the body of the powder suction pump or body of suction pipe without departing from the spirit and scope of invention. Figures are merely representational and are not drawn to scale. Certain portions thereof may be exaggerated, while others may be minimized. Figures illustrate various embodiments of the invention that can be understood and appropriately carried out by those of ordinary skill in the art.

[0054] In the foregoing detailed description of embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure.

[0055] It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims.