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(11) | EP 3 318 338 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | CONTAINER FOR SIEVING PAINTING POWDER |
| (57) Container (1) for sieving painting powder for a powder coating plant, comprising: - a sieving chamber (2) to sieve painting powder to be sieved, - a collection chamber (3) for the sieved painting powder, - at least one sieve (4) arranged next to at least one of the outer surfaces (2b, 2c, 2d) of said sieving chamber (2), wherein said sieving chamber (2) is arranged at least partially, and preferably completely, inside said collection chamber (3) and comprises at least one opening (2a) for the entry/exit of powder. |
[0001] The present invention applies to the field of the powder coating, and particularly to the field of the sieving of painting powder.
[0002] As known, in a plant for powder coating, the painting powder is withdrawn from a source and directed, typically by means of a gun and mixed with air, against the objects to be painted. The powder adheres to the objects by electrostatic effect. Next, the objects are heated so that to melt the painting powder that subsequently forms a colored layer adhering to the object itself.
[0003] Before being directed to the gun, the painting powder is sieved to remove impurities. In particular, the painting powder is directed towards a container having, at its top, a sieve driven by vibration. The powder is dropped by gravity against the sieve. The painting powder passes through the sieve that instead holds the impurities.
[0006] Finally, the color changing operations are particularly uncomfortable. In fact, when the color of the painting powder to be applied to an object to be colored must be changed in the plant, the plant must be cleaned thoroughly. In particular, residues of the painting powder of the previous color must be removed.
[0008] Thus, such operations cause a considerable loss of time and money, because during the cleaning operations, the objects cannot be painted.
[0010] In particular, object of the present invention is to provide a container for sieving painting powder that is simple and cost-effective to produce.
[0011] It is a further object of the present invention to provide a container for sieving painting powder that allows effective sieving of the painting powder.
[0012] It is a further object of the present invention to provide a container for sieving painting powder that is simple and quick to clean.
[0013] These and other objects are achieved by a container according to claim 1 and by a cleaning process according to claim 7.
[0015] According to an aspect of the present invention, a container for sieving painting powder for a powder coating plant comprises:
- a sieving chamber for sieving painting powder to be sieved,
- a collection chamber for the sieved painting powder,
- at least one sieve arranged at at least one of the outer surfaces of the sieving chamber. The sieving chamber is arranged at least partially, and preferably completely, inside the collection chamber, and comprises at least one opening for the entry and/or exit of powder.
[0016] Thanks to the present solution, the management and cleaning of the container are simple. In particular, among other things, the present solution allows directly accessing the collection chamber without removing the sieve from the container. Furthermore, the shape and position of the sieving chamber allows particular effectiveness in the powder sieving operations.
[0017] According to an aspect of the present invention, the sieving chamber has at least one base surface and one side surface, and at least one sieve is arranged on at least part of the side surface and/or at least part of the base surface. Typically, the sieving chamber is substantially cylinder-shaped.
[0018] Such a solution is easy to produce and is consistent with the typically cylindrical shape of the container. However, it is not excluded the possibility to have other shapes, for example prismatic, conical, pyramid shapes, etc. Furthermore, it is not excluded the possibility to make a spherical sieving chamber.
[0019] In general, it is preferred that the sieving chamber forms a closed and distinct space from the collection chamber, in order to avoid the contamination between the two rooms, i.e. to avoid the non-sieved painting powder may end up in the collection chamber.
[0020] The side surface of the sieving chamber is spaced from the internal wall of the container. Thus, between the sieving chamber and the container a passage is formed, that is open on top and bottom (at least when the container is opened on top).
[0021] At least part of the upper surface of the collection chamber is placed outside the sieving chamber.
[0022] According to an aspect of the present invention, the sieving chamber has at least one recess, typically arranged at the side surface of the sieving chamber, to allow the passage of a cleaning device inside the collection chamber through the sieving chamber.
[0023] This allows to further simplify the cleaning operations and to make them more effective at the same time.
[0024] According to a further aspect of the present invention, the container comprises means to make the sieving chamber vibrate. Thanks to this, the sieving operations are particularly effective.
[0025] According to an aspect of the present invention, the container comprises a support, preferably a vibrating support, for the sieving chamber. The sieving chamber is constrained to the support.
[0026] An aspect of the present invention further concerns a cleaning process of a container of painting powder according to one or more of the previous aspects, by means of a cleaning device comprising at least one movable arm equipped with a plurality of nozzles. In particular such a process comprises the steps of:
- (a) inserting the at least one movable arm inside the container;
- (b) moving the movable arm inside the container;
- (c) during said step, emitting a fluid from said nozzles of said movable arm,
[0027] According to an aspect of the present invention, the process comprises the step of inserting a suction element inside the sieving chamber.
[0028] During step (a) of inserting the movable arm, the latter passes through the side passage placed between the sieving chamber and the container, so that to reach the portions of the collection chamber placed under (i.e. beyond) the sieving chamber. With reference to the attached figures, embodiments exemplary and non-limiting the present invention are now discussed, wherein:
- figure 1 is a sectional perspective view of a container according to an embodiment of the present invention;
- figure 2 is a perspective view of the sieving chamber of the container of figure 1, with the sieve partially removed;
- figure 3 is an exploded perspective view of the container of figure 1;
- figure 4 is a sectional perspective view of the container of figure 1, with a cleaning device inserted therein;
- figure 5 is a perspective view of the cleaning device used in figure 4.
[0029] A container 1 for sieving painting powder comprises a sieving chamber 2 and a collection chamber 3.
[0030] The container 1 is typically shaped as basin, that is typically cylinder-shaped. Generally, the container 1 is open at a base.
[0031] Typically, the collection chamber 3 is at least partially defined by the side walls of the container 1. In the showed embodiment, the collection chamber 3 has a bottom 3a inserted inside the container 1, that defines the lower surface of the collection chamber 3, whereas the side surfaces (or the side surface in the present case) of the collection chamber are defined, as mentioned above, by the side walls (or by the side wall in the present case) of the container 1. Preferably the bottom 3a is made by a porous septum allowing for the passage of air, but impeding the passage of the powder. An entry of air 3b can be arranged under the bottom of the collection chamber, so that air passes through the porous septum in order to fluidify the sieved powder contained inside the collection chamber 3.
[0032] However, it is not excluded the possibility to have a collection chamber 3 completely contained inside the container 1, i.e. completely distinct and separate with respect to the walls of the container 1. The collection chamber 3 is typically, but not necessarily, open on top, so that to allow appropriate means (not shown in the figures) to withdraw the sieved powder from the container 1.
[0033] The sieving chamber 2 can have different shapes. The sieving chamber preferably defines a substantially closed room (with the exception of the entry/exit or entries/exits for the painting powder) and separate from the collection chamber 3. Furthermore, the sieving chamber 2 typically has at least one outer surface 2b, 2c, 2d, adapted to define a space or room within which the powder to be sieved can be inserted and within which impurities, or the elements that have not passed through the sieve 4 (better discussed below), can be kept. As previously discussed, such a space or room defined by the sieving chamber 2 is preferably substantially closed (with the exception of the means of entry/exit of the painting powder), i.e. it is separated from the room defined by the collection chamber, so that to prevent the powder to be sieved contained in the sieving chamber 2 from entering in the collection chamber 3 without passing through the sieve 4.
[0034] In this regard, a solution is possible, but less preferred, wherein the sieving chamber is partially open, provided that the contact between the powder to be sieved and the powder already sieved is avoided. For example the sieving chamber 2 could be shaped similarly to the collection chamber, i.e. cylinder-shaped with the upper base open.
[0035] Preferably, the sieving chamber has at least one base surface 2b, 2c and at least one side surface 2d. In the shown embodiment, in particular, the sieving chamber 2 is cylinder-shaped, and thus it is provided with two base surfaces 2b, 2c and one side surface 2d.
[0036] The sieving chamber 2 is further provided with at least one sieve 4 placed at at least part of an outer surface 2b, 2c, 2d.
[0037] Preferably the sieve 4 is arranged on at least 50% of the outer surfaces of the sieving chamber, more preferably at least 75%. It is preferred that the sieve 4 covers the highest percentage possible of the outer surfaces of the sieving chamber 2. In the shown embodiment, according to a preferred solution, the sieve 4 substantially covers completely the outer surfaces (or the outer surface) 2b, 2c, 2d. In particular, note that the sieve 4 is explicitly depicted in figure 2 only, and only on half of the sieving chamber 2, in order to allow a simpler visualization of the other half of the chamber itself. However it is meant that, in the shown embodiment, the sieve 4 is substantially arranged around the whole sieving chamber 2.
[0038] Preferably, the sieving chamber is formed by a frame 2f on which the sieve 4 is assembled; thus, the outer surfaces 2b, 2c, 2d may at least in part consist exclusively of the sieve 4.
[0039] The sieve 4 typically comprises a wire mesh preferably having a "net light", i.e. an average distance between wires next to each other of the mesh, equal or lower than 400 microns.
[0040] The sieve is typically constrained to the sieving chamber by means of an anti-vibration support 5.
[0041] The sieving chamber 2 has at least one opening 2a to allow the entry/exit of powder. In particular, in the shown embodiment, the sieving chamber has an opening 2a that, in the conditions of normal use, is used to allow the entry of the powder to be sieved inside the chamber itself. On the contrary, during the cleaning operations of the container 1, the opening 2a is used to suction the residues kept inside the sieving chamber 2 at the end of the sieving operations (for example too big powder granules, impurities, etc.).
[0042] However it is possible to make use of more openings, for example openings exclusively dedicated to the entry of powder, and openings exclusively dedicated to the exit of powder and/or impurities.
[0043] According to a particular aspect, the sieving chamber 2 has one or more recesses 2e (two recesses 2e in the particular shown embodiment) to allow the passage of a cleaning device inside the container 1, and particularly inside the collection chamber 3. Such recesses 2e are typically provided on the side surface 2d of the sieving chamber 2.
[0044] The sieving chamber 2 is arranged at least partially inside the collection chamber 3 and, preferably, it is arranged completely inside it. Thus, preferably the sieving chamber is internal and distinct from the collection chamber 3. As mentioned above, the sieving chamber 2 and the collection chamber have preferably similar shape. Thus, according to an aspect, the side surface 2d (or the side surfaces in case of polyhedral shape) of the sieving chamber 2 faces the side surface (internal) of the container 1 delimiting the collection chamber 3.
[0045] Thus, the side surface 2d is preferably placed at distance from the side surface (internal) of the container 1. The collection chamber 3, i.e. the chamber intended to collect the powder sieved by the sieve 4, is thus extending under and aside (and typically also over) the sieving chamber 2. In this sense, the sieving chamber 2 is placed internally the collection chamber and is distinct from it. Thus a space exists, that is open on top and the bottom, between the side surface 2d of the sieving chamber and the internal wall of the container 13. In other words, at least one side passage P (from now on also "passage P") is formed between the sieving chamber 2 and the internal wall of the container 1, such that the powder can pass from an area placed above the upper surface 2c of the sieving chamber 2 to an area placed below the lower surface 2b (and internal to the collection chamber 3 in the container 1) of the sieving chamber 2 through such a passage P. Similarly, the powder contained on the bottom of the collection chamber can be extracted from the container 1 without passing through the sieve 4, i.e. by passing aside the sieving chamber 2 through the passage P.
[0046] The passage P, at least when the container 1 is open, is thus open both at the bottom and on top, i.e. it is a through opening (typically having a section with the shape of a circular crown) arranged between the sieving chamber 2 and the container 1. In general, in use, the upper opening of the container 1 is covered by a specific lid (not shown). In some embodiments, such a lid could close the upper opening of the passage P, in the event the upper surface 2c of the sieving chamber 2 is placed at the same level of the upper opening of the container 1. Also in such an embodiment, in any case, when the container 1 is opened, the passage P is open both on top and the bottom, so that to allow an object to be inserted inside the container 1 so that this could arrive down to the lower portion of the collection chamber 3, inside the container 1, without removing the sieving chamber 2 from the container 1 itself. Actually, such a passage P, as it is better explained below, is not mainly intended for the passage of powder, but is particularly useful during the cleaning operations of the container 1. In fact, during such operations, it is possible to keep the sieving chamber 2 inside the collection chamber 3, i.e. inside the container 1. A specific cleaning device 10 (for example that one discussed below with reference to the figures 4 and 5) can be inserted inside the collection chamber 3, through the upper opening of the container 1. The cleaning device 10, once inserted into the container 1, can continue its stroke, pass through the passage P so that to go beyond the sieving chamber 2, until it reaches the areas of the collection chamber 3 placed under the sieving chamber 2. Thus, both the collection chamber 3 and the sieving chamber 2 can be cleaned by the cleaning device 10, without the need to remove the sieving chamber from the collection chamber.
[0047] Specific recesses 2e can be provided on the sieving chamber, so that to locally increase the size of the passage P and to allow bigger cleaning devices 10 to be used. Preferably, the passage P spans 360 degrees around the sieving chamber, i.e. it surrounds substantially completely the sieving chamber 2.
[0048] In general, thanks to the above described configuration, the container is kept compact, and it is simpler to keep the powder sieved by the sieve 4 inside the collection chamber 3.
[0049] Furthermore, removing the sieving chamber 2 from the collection chamber 3 is particularly simple.
[0050] The container 1 typically has a support 5 on which the sieving chamber 2 is assembled. The support 5 can have different shapes suitable to support the collection chamber 3. In the shown embodiment the support 5 has a truncated cylinder shape. Screws 6, or similar threaded elements, can be used to constrain the sieving chamber 2, and particularly the lower surface 2c of the sieving chamber 2, to the relative support 5.
[0051] According to a possible embodiment as shown in the figures, the container 1 has means 7 to make the sieving chamber 2, or at least the sieve 4, vibrate. Such means 7 can be generic means known in the art and adapted for the purpose.
[0052] In particular in the shown embodiment, there are vibrating elements 71, 72. Such vibrating elements 71, 72 are preferably arranged in combination with anti-vibration supports 70 allowing the vibration to be transferred to the sieve 4, and dampening the vibration transmitted to the container 1. Different number, arrangement and types of vibrating elements can be used with respect to what has been shown (for example a single vibrating element placed in direct or indirect communication with the sieve 4). With reference to the figures, the element 71 is an ultrasound-vibrating element, whereas the element 72 is a pneumatic-vibrating element. An air entry 73 is preferably placed on the container 1 so that to provide air to the pneumatic-vibrating element 72 for its optimal functioning.
[0053] In use, some powder to be sieved is put inside the sieving chamber 2 through the opening 2a (typically by means of tubing linked to a source of powder to be sieved, not shown).
[0054] Thus, the powder to be sieved meets the sieve 4 arranged at one or more of the outer surfaces 2b, 2c, 2d of the sieving chamber 2.
[0055] During such operations the sieving chamber 2 can be vibrated by the specific means 7. It has to be noted how the painting powder to be sieved is generally sent inside the sieving chamber by means of a fluidic conduct, by means of an air jet which fluidifies and carries the powder itself. Such an action leads to a turbulence inside the sieving chamber, so that to favor the sieving not only through the lower base surface 2b (by the action of gravity), but also through the upper base surface 2c and through the side surface 2d. Thanks to this, the powder is sieved not only in the direction parallel to the gravity, but also along a tilted direction (typically perpendicular direction) and/or opposite to the gravity, thus speeding up the sieving operations and avoiding accumulation of the powder.
[0056] The sieved powder is thus deposited (or otherwise sent) to the collection chamber 3, whereas impurities or the coarse powder are retained inside the collection chamber 3. The sieved powder, retained in the collection chamber, is withdrawn therefrom by means of the specific means known in the art and not shown, for example suction means.
[0057] The container 1 can be cleaned in different ways, also according to ones known in the art. An aspect of the present invention relates to a particular and effective cleaning method of the container 1.
[0059] The cleaning device 10 comprises preferably at least one movable arm 10a. According to a possible embodiment, the movable arm 10a comprises a body 101a typically with elongated shape, and a head 102a protruding laterally with respect to the body 101a. The movable arm further has a plurality of nozzles 10b adapted to emit a fluid to clean the container. Typically such a fluid is air. In such a case, the cleaning device 10 comprises or can be connected to an air source (known in the art and not shown in the figures), for example a compressor.
[0060] Preferably, the nozzles 10b are arranged so that to emit the fluid in more than one direction. In more detail, each nozzle typically has a main direction of fluid emission. Such a direction can be different between different nozzles. In such a way it is possible, for example, to effectively clean different elements of the container, or also different surfaces of the same container.
[0061] In general, the movable arm 10a is hollow inside to ease the passage of the air or fluid used for cleaning the container 1.
[0062] The arm 10a can be moved in various directions, depending on the needs. In an embodiment shown in the figures, the movable arm 10a can rotate. In particular, the cleaning device 10 has a longitudinal axis A that in use typically coincides with the longitudinal axis of the container, and the movable arm 10a can rotate around such an axis A. According to a possible solution, the movable arm 10a has an L-shaped body 101a, with a first portion substantially orthogonal to the axis A, and a second portion substantially parallel to the axis A.
[0063] Specific motorized means can be provided for moving the movable arm 10a. However, preferably, as in the shown embodiment, the arrangement of the nozzles 10b is such that, when the cleaning fluid is emitted from the same, the movable arm is naturally rotated.
[0064] In other words, the fluid emission from the nozzles 10b causes the formation of a torque on the movable arm 10a, that the latter is rotated.
[0065] Furthermore, an actuator 103 can be provided, for example an electric or pneumatic actuator, in order to arrange the arm 10a (or the arms 10a) in such a position to allow the extraction of the device 10 from the container 1, for example in a position in which the arm 10a is placed next to the recesses 2e.
[0066] More than one movable arm 10a can be provided on the cleaning device 10. In the shown embodiment, the movable device has two movable arms 10a both of which can be rotated, preferably in a synchronous way.
[0067] Moreover, the cleaning device 10 preferably has a suction element 10c that can be inserted inside the sieving chamber 2, typically through the opening 2a. In general, as in the shown embodiment, such a suction element 10c is in the form of tubing linked in a known way to a suction element known in the art, that can alternatively be part of the device 10 or else an external element specifically connected to it.
[0068] The shape of the cleaning device 10 and the container 1 is preferably such to enable the former to be inserted in the latter. As already mentioned above, for example, the sieving chamber 2 preferably has recesses 2e to allow the cleaning device 10 to be inserted inside the container 1. With reference to the shown embodiment, the recesses 2e are shaped complementarily to the heads 102a of the movable arms 10a, so that to allow the heads to pass through the sieving chamber 2, i.e. to go beyond the sieving chamber when the cleaning device 10 is moved to be inserted inside the container 1.
[0070] During such a step the movable arm 10a passes through the passage P between the sieving chamber 2 and the container 1, preferably passing through the recesses 2e of the sieving chamber 2.
[0071] Afterwards, the movable arm (or the movable arms) 10a is moved, and particularly rotated in the shown embodiment. In the meantime a fluid, in general air, is emitted by the nozzles 10b of the movable arm 10a. As mentioned above, the nozzles are preferably arranged so that to conveniently direct the fluid against the various elements of the container. With reference also to the figure 4, air is directed against the internal walls of the container, the bottom 3a, against the external walls of the sieving chamber.
[0072] The suction element 10c is further inserted inside the sieving chamber, so that to allow internal cleaning of the sieving chamber.
[0073] During these operations the sieving chamber is kept inside the collection chamber 3, so that both elements are cleaned by the cleaning device 10 at the same time.
[0074] At the end of the cleaning operations, the device 10 is removed from the container. During these operations, the movable arm 10 is typically arranged next to the recesses of the sieving chamber, so that to avoid the interference between the two elements, for example by means of the actuator 103 described above.
1. Container (1) for sieving painting powder for a powder coating plant, comprising:
- a sieving chamber (2) to sieve painting powder to be sieved,
- a collection chamber (3) for the sieved painting powder,
- at least one sieve (4) arranged at at least one of the outer surfaces (2b, 2c, 2d) of said sieving chamber (2), wherein said sieving chamber (2) is arranged at least partially, and preferably completely, inside said collection chamber (3) and comprises at least one opening (2a) for the entry/exit of powder.
2. Container (1) according to claim 1, wherein said sieving chamber (2) has at least
one base surface (2b, 2c) and one side surface (2d), and at least one sieve (4) is
arranged on at least part of said side surface (2d) and/or on at least part of said
base surface (2b, 2c).
3. Container (1) according to claim 1 or 2, wherein said sieving chamber (2) is substantially
cylinder-shaped.
4. Container (1) according to one of the preceding claims, wherein said sieving chamber
(2) has at least one recess (2e) to allow a cleaning device (10) to pass inside said
collection chamber (1) through said sieving chamber (2).
5. Container (1) according to one of the preceding claims, comprising means (7) to vibrate
said sieving chamber.
6. Container (1) according to one of the preceding claims, comprising a support (5) for
said sieving chamber (2), wherein said sieving chamber (2) is constrained to said
support (5).
7. Process for cleaning a container (1) of painting powder according to one of the preceding
claims, by means of a cleaning device (10) comprising at least one movable arm (10a)
provided with a plurality of nozzles (10b), comprising the steps of:
(a) inserting said at least one movable arm (10a) in said container (1);
(b) moving said movable arm (10a) inside said container (1);
(c) during said step (b), emitting a fluid from said nozzles (10b) of said movable arm (10a), so that at least said collection chamber (3) and said sieving chamber (2) are cleaned.
8. Process according to claim 7, wherein said fluid is air.
9. Process according to claim 7 or 8, comprising the step of inserting a suction element
(10c) into said sieving chamber (2).