WO2022113001A1

WO2022113001A1 - Painting gun provided with an improved adjustment system

Info

Publication number: WO2022113001A1
Application number: PCT/IB2021/060989
Authority: WO
Inventors: Alessandro GAMBOGI; Roberto GROSSI
Original assignee: Aircom Srl; Barnini S.R.L.
Priority date: 2020-11-25
Filing date: 2021-11-25
Publication date: 2022-06-02
Also published as: IT202000028433A1; KR20230129059A; CN116801988A; EP4251330A1

Abstract

A painting gun (3) for painting an article comprising an adjustment system (9) comprising a wheel (10) configured to rotate around an axis (A) to vary the free section of an opening (7) of the gun (3) through which a painting fluid can flow depending on the rotation in one direction or the other around the axis (A), the adjustment system (9) comprising actuator means configured to rotate the wheel (10).

Description

"PAINTING GUN PROVIDED WITH AN IMPROVED ADJUSTMENT SYSTEM"

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 102020000028433 filed on November 25, 2020, the entire disclosure of which is incorporated herein by reference.

TECHNICAL SECTOR

This invention relates to a painting gun, in particular an airbrush gun, equipped with an adjustment system for the painting fluid flow.

PRIOR ART

The known painting systems usually comprise at least one painting gun configured to spray a painting fluid on an object to be painted.

This gun, airbrush, thus comprises an opening that enables this painting fluid, usually pressurised, to flow out in the direction of the object to be painted.

In the prior art, the adjustment of the flow of fluid in painting circuits where airbrush guns are used may occur in the following ways:

• By adjusting the pressure of the centralised paint feeding pump placed upstream of the circuit;

• By manually adjusting the adjustment wheel present on every gun; or • By using servopneumatic throttle devices to be placed between the paint feeding tube and the gun;

Clearly, a centralised control where the adjustment of the painting fluid flow is performed upstream of the gun feeding tubes is imprecise, since the same fluid flow is provided to all the guns because every gun would be fed with a flow designed to meet the needs of that with the greatest need for fluid. A dedicated adjustment for each gun, at the hydraulic level, would, instead, by extremely complex, bulky, and costly.

A manual adjustment, on the other hand, substantially impacts the maintenance time for the painting systems, having to manually adjust each gun in order to modify the amount of paint to deliver. Finally, the use of intermediate adjustment devices to be inserted in line on the painting circuit does not enable a precise adjustment when small amounts of product are required to be delivered. They increase the time needed for managing the system since more time is needed for maintenance and they may be subject to blockages due to the narrow internal passages where the paint flows.

There is, thus, a need to provide painting guns that may be adjusted in an automatic, compact, precise, and economical way. There is, also, the need to limit the maintenance times and without needing to add other devices that act on the paint feeding circuit.

The purpose of this invention is to meet the requirements mentioned above. SUMMARY OF THE INVENTION

The above-mentioned purpose is achieved with a painting gun and a painting system as claimed in the attached independent claims.

Additional, preferred embodiments of the invention are constructed according to the dependent claims or those connected to the independent claims mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

To better understand this invention a preferred embodiment is described below, by way of non-limiting example and with reference to the attached drawings, in which:

• Figure 1 is a longitudinal cross-section view of a painting system comprising a painting gun according to the invention;

• Figure 2 is a cross-section view along the line II-II of the adjustment system in Figure 1;

• Figures 3 and 4 are longitudinal cross-section views, enlarged and only partial, of different operational phases of the adjustment system for the painting gun in Figure 1;

• Figures 5A to 5F are longitudinal cross-section views of different operational steps of the adjustment system for the painting gun of the system in Figure 1; and • Figure 6 is a perspective, partially exploded view, of the painting gun of the system in Figure 1. DETAILED DESCRIPTION OF THE INVENTION

In Figure 1, a portion of a painting system 1 is illustrated comprising at least one painting assembly 2 each equipped with a painting gun 3. In the figure illustrated, there is a single painting assembly 2, for simplicity. In particular, the painting gun 3 extends along a longitudinal axis A and is supported by a support 4 that can be fixed to a body (not illustrated) fixed to the painting system 1.

Advantageously, the support 4 comprises a fixing portion 4a configured to fix the support 4 to the body of the painting system 1.

The support 4 defines, in addition, a first and a second lateral relief 5 extending longitudinally parallel to the axis A and overhanging the fixing portion 4a. The support 4 is preferably made of material that remains unaltered and stable over time, such as stainless steel.

The first and the second lateral relief 5 transversely delimit between them a seat designed to partially house the painting gun 3.

The painting gun 3 defines a casing 3a, preferably cylindrical in shape and configured to delimit an internal space 3b designed to house a flow adjustment system 6 for the painting gun as described below.

As known, the flow adjustment system 6 comprises a rod 6a configured to open or close the free section of an opening 7, preferably defined as a nozzle outlet section. The opening

7 is fluidically connected to a known source 8 of painting fluid.

In particular, the rod 6a is connected to adjustment means 9 configured to adjust the maximum vertical stroke position along the axis A of this rod 6a as described below.

As is known, the movement of the rod 6a along the axis A is actuated using a pneumatic system 6b. In particular, the pneumatic system 6b comprises a piston 6c actuated via the entry of air from the duct 6d' and returned to the neutral position, i.e., against the elastic means 6f closure when the air is made to flow from the duct 6d'.

The piston 6c is connected to a second piston 6g that is integral thereto and configured to enable the passage of compressed air coming from a duct 6d' that may then flow towards the opening 7. In particular, the air flows in ducts that are fluidically separate to the opening 7 and communicating with the outside via orifices 3b made around the opening 7.

Since the components of the flow adjustment system 6 are known, they will not be described in any more detail for the sake of brevity.

The rod 6a is carried by the cylinder 6c and follows the movements thereof between a first end position, lower, wherein the opening 7 is closed by the rod 6a, and a second end position, higher and the maximum stroke of which is delimited by the adjustment means 9, wherein, between the rod 6a and the opening 7, a section for the passage of painting fluid coming from the source 8 is free.

These adjustment means 9 essentially comprise a wheel 10 configured to rotate about the axis A and actuator means 11 configured to adjust this rotation of the wheel 10.

Advantageously, these actuator means 11 are pneumatic actuator means.

According to the advantageous embodiment described, the adjustment means 9 comprise first actuator means 11' configured to enable the rotation of the wheel 10 clockwise around the axis A and according to actuator means 11 configured to enable the rotation of the wheel 10 anticlockwise around the axis A. Clearly, the actuator means 11', 11 work alternatively, the one in relation to the other.

The clockwise or anticlockwise rotation of the wheel 10 enables, respectively, the reduction or increase of the second end portion, i.e., the upper stop of the rod 6a, thus changing the maximum passage section between rod 6a and opening 7.

According to an embodiment illustrated in Figure 2 and following, each of the actuator means 11 comprises a tip 12 housed freely in relation to the translation in a support element 13 and configured to cooperate in contact with respective seats 14 made on the wheel 10 to control the rotation thereof.

The seats 14 are preferably equally angularly spaced apart circumferentially so that between one seat 14 and the other, there is the same angular pitch. In the case described, there are twenty seats 14 equally spaced apart by 18° around the axis A.

In particular, the support element 13 is configured to be fixed to the support 4 in such a position so as to be able to laterally wind, at least partially, the wheel 10 of the painting gun 3. In particular, when fixed to the support 4, the fixing element extends so that it overhangs the fixing portion 4a of the support 4, preferably perpendicularly to it. The support element 13 preferably comprises, thus, a fixing portion configured to fix the same to the support 4 and an end portion configured to wind, at least in part, the wheel 10 of the painting gun 3.

This end portion preferably defines an arched portion facing the wheel 10 and, more preferably, concentric to it. The support element 13 is, advantageously, hollow, i.e., it defines a through opening 15 configured to house, within, the tip 12 and to enable the translation thereof along an axis C, preferably parallel to the axes A and B.

In particular, the through opening 15 comprises a first portion 15', an intermediate portion 15'', and a second portion 15''', that are opposite along the axis C in relation to the first portion 15'. Advantageously, all the portions 15', 15'', and 15''' are advantageously axially symmetrical, preferably cylindrical, and the first portion 15' has transverse dimensions in relation to the axis C that are greater compared to the intermediate portion 15'' that, in turn, has transverse dimensions in relation to the axis C that are greater compared to the second portion 15'''. According to the embodiment illustrated, the diameter of the first portion 15' is greater than the diameter of the intermediate portion 15'' that, in turn, is greater than the diameter of the second portion 15'''.

The second portion 15''' is sized so that the tip 12 cooperates in contact with the internal walls radially delimiting the second portion 15'''.

In particular, the tip 12 comprises a first end portion 12a configured to mechanically cooperate with the wheel 10 and partially slidable in the second portion 15''' of the opening 15 and a second end portion 12b, opposite the first end portion 12a, and configured to slide inside the first portion 15' of the fluid-tight opening 15. The first and the second end portions are connected to each other by means of an intermediate portion 12c. The second end portion 12b basically defines a piston that thus divides the first portion 15' in a first portion 15' fluidically in contact with a pressurised fluid source F and a second portion 15'b fluidically separated from the first portion 15'a. The pressurised fluid source F, not illustrated, is advantageously a pneumatic source configured to selectively provide a pressurised air flow F inside the second portion 15'b so as to exert a force on the second end portion 12b, thus on the tip 12. The tip 12 is configured to be moved along the axis C between a first (rest) operating position (Figure 3) wherein the first end portion 12a does not cooperate with the wheel 10 and a second (actuation) operating position (Figure 4) wherein the first end portion 12a cooperates in contact with the wheel 10.

In particular, the actuator means 11 comprise elastic means 17 configured to maintain the tip 12 in the first operating condition. These elastic means are preferably operationally placed between the second end portion 12b and the support element 11', more preferably within the opening 15.

According to the embodiment described, the elastic means 17 are housed inside the second and third portion 15', 15'' of the opening 15.

In particular, the elastic means 17 comprise a helical spring 18 housed around the intermediate portion 12c of the tip 12, preferably coaxial to it, and comprising a first end in contact with the shoulder defined by the narrowing between the second and third portion 15'', 15''' of the opening 15 and a second end in contact with the second end portion 12b of the tip 12.

The tip 12 advantageously comprises a pawl 20 movably carried by the first end portion 12a of the tip 12 and configured to cooperate in contact with the wheel 10.

In particular, the pawl 20 is advantageously L-shaped, i.e., comprising a first arm 20' and a second arm 20'' connected via a hinge connection 21 to the first end portion 12a of the tip 12. Advantageously, the first and the second arm 20', 20'' consist of a single piece. The hinge 21 enables the rotation of the pawl 20 around an axis parallel to the axis A between a first and a second limit value.

In particular, the first arm 20' is sized so as to cooperate with the seats 14 of the wheel 10 to control the movement of the latter when in one of the rotation limit conditions of the pawl 20. The actuator means 11 advantageously comprise thrust means 23 configured to exert a direct force against the tip 12 during its stroke along the corresponding axis C. In particular, the thrust means 23 comprise a sphere positioner 25 comprising a sphere 24 designed to enter into a corresponding seat 25 under the action of a predetermined force provided by the tip 12.

In particular, the wheel 10 comprises a mobile portion 10' defining the above-mentioned seats 14 and with which the adjustment system 9, described above, cooperates and a fixed portion 10 borne by the casing 3a and on which the mobile portion 10' is borne rotationally free.

In particular, the mobile portion 10' is integral with a threaded pin 230, for example planted, inside a through opening 31 in the mobile portion 10'. The threaded pin 30 cooperates by threading with a threaded shaft 32 in turn connected, via threading made on the radial internal surface of a through opening 33 made within the fixed portion 10''.

The integral rotation between threaded pin 30 carries with it the rotation of the threaded pin 31 that, thus, makes the threaded shaft 32 move along the axis A. The threaded shaft 31 acts as a stop for the rod 6a so that the maximum opening H of the opening changes in relation to the shaft 31 and, thus, as a consequence, the maximum opening of the space between the rod 6a and the opening 7 of the nozzle. The adjustment system 9 comprises, in addition, angular timing means 35 configured to adjust the relative starting position of the adjustment system 9, i.e., between the movable 10' and the fixed 10 part of the wheel 10.

In particular, the angular timing means 35 comprise a positioner 36, for example similar to the positioner 23, configured to cooperate with multiple internal seats made radially corresponding to the seats 14. In addition, the timing means 35 comprise a reference dowel 37 made on the outside surface of the body 3a.

The timing means 35 also comprise an additional reference dowel 38 made on the body 3a of the gun 3.

The operation of the adjustment system 9 for a painting gun 3 described above is the following, referring to Figures 5A-5F and to the left actuator 11'.

In Figure 5A, a rest condition is illustrated where the tip 12 is in the first operating condition. In this condition, there is no pressurised air in the chamber 15'b so as to overpower the force exerted by the elastic means 17 that, thus, maintain the second end portion 12b in a predefined rest point. In this condition, the pawl 20 does not cooperate in contact with the seat 14.

In Figure 5B, a stroke start condition of the tip 12 under the action of pressurised air entering the chamber 15 is illustrated. In particular, the pressurised air exerts a force that overcomes that exerted by the elastic means 17 that tend to compress. Thus, the second end portion 12b tends to enter inside the opening 15. Consequently, the first end portion 12a moves, borne by the second end portion 12b, until the first arm 20' touches one of the walls of the seat 14 of the wheel 10. During this step, the thrust means 23 impede the rotation of the pawl 20 so that the first arm 20' is "hooked" in the corresponding seat 14, i.e., the sphere 24 exerts pressure against the second arm 20''. In Figure 5C, a rest condition is illustrated where the tip 12 is in the second operating condition. In this condition, the pressurised air in the chamber 15' is such that it completely overwhelms the force exerted by the elastic means 17 and, thus, the second end portion 12b is in contact with the shoulder between the portions 15' and 15' .

In this condition, the tip 12, since the pawl 20 is hooked into the seat 14, has dragged the wheel 10 in its movement, so that the latter rotates around the axis A.

Once the second operating condition, in Figure 5C, is reached, the pressurised air is made to flow from the chamber 15. As a consequence, the elastic means 17 tend to overwhelm the force exerted by the pressurised air in the chamber 15 and to push the second portion 12b towards the position assumed in the first operating condition in Figure 5A. During this movement, the arm 20' is unhooked from the corresponding seat 14.

During steps 5B, 5C, the thrust means 23 provide a force configured to maintain contact between the tip 12 and the pawl 10.

Continuing its movement towards the condition in Figure 5A, the thrust means 23 come into contact with the single pawl 20 (Figure 5E) that is pushed by the sphere 24 that tends to leave the seat 25 exerting a force on the second arm 20''. In this way (Figure 5F), the pawl 20 will be rotated so as to turn in its original position so that it can, again, restart an actuation cycle of the wheel 10.

The operation of the right actuator 11’’ is the same as the left actuator 11' described above; it is simply a mirror image and, thus, actuates the wheel 10 so that it rotates anticlockwise .

As a function of what is described above, the anticlockwise rotation of the wheel 10 enables the rotation of the threaded shaft 32 and increases the maximum opening H between the end-stop defined by the latter and the rod 6a. In this way, it is possible to increase the flow of painting fluid that can flow between the rod 6a and the opening 7 of the nozzle. In contrast, a clockwise rotation of the wheel 10 reduces the maximum opening H, potentially reducing this flow of painting fluid to zero.

The correct assembly of the wheel 10 is ensured by the angular timing means 35. The positioner 36 fulfils the function of maintaining the seats 14 in their correct angular position in relation to the tip 12. In contrast, the set of references given by the dowel 37 and by the position of the positioner 36 itself makes it possible to assemble the wheel 10 so as to maintain a prefixed distance between the rod 6a and the opening 7 of the nozzle.

Clearly, the actuator means 11 can be controlled at the electric-pneumatic level thanks to a control unit, not described, that processes the necessary data for painting an object by means of the painting gun 2 and that adjusts, as a result, their activation to provide a correct flow of painting fluid.

From the above, the advantages of the painting gun and the painting system according to the invention are clear.

Thanks to the gun proposed, it is possible to autonomously adjust the flow of liquid through the opening or closing of the adjustment wheel, enabling a fine, singular, and quick adjustment of each, individual gun of a painting system.

The use of pneumatic actuators enables an automatic adjustment and no longer a manual one of the wheel 10, with significant economic advantages given the reduced maintenance time that, in the prior art, was used to manually adjust the guns. In addition, this invention makes it possible to simply and quickly adjust the flow of liquid delivered by each airbrush device, without the need to interpose additional components subject to maintenance between the paint feeding circuit and the gun. The presence of two actuators per direction of rotation simplifies this pneumatic-mechanical adjustment .

The presence of seats at fixed distances makes it possible adjust in a constant, and therefore calculable way, the opening of the wheel.

The presence of the thrust means facilitates the coupling between pawl and seat and, thus, makes it possible to repeat the operation at high speeds.

Similarly, the presence of the elastic means enables a quick return of the tip to the rest position, enabling a repeated operation at high speeds.

Clearly, the adjustment mechanism proposed for the wheel 10 enables extremely fine adjustment of the passage between rod 6a and opening 7 of the nozzle that depends on the number of seats 14 made on the wheel and the pitch of the threading of the shaft 32. In the example illustrated, comprising, for example, 20 seats 14 and a threading of one millimetre, it is possible to adjust a vertical distance of the rod of 0.05 mm from the wheel 10, thus enabling extreme precision. Thanks to the angular timing means 35, it is also possible to correctly assemble and reassemble the wheel 10 without losing the correct calibration of the opening between rod 6a and opening 7 of the nozzle. Finally, it is clear that changes may be made to the painting gun and to the painting system, and variations produced thereto, according to this invention that, in any case, do not depart from the scope of protection defined by the claims. For example, the type of elastic means and thrust means may vary, just like the shape of the support element, of the pawl or of the tip and of their construction materials.

Equally, the actuator means could be electro-mechanic or hydraulic.

Claims

1. - A painting gun (3) configured to paint an article, said painting gun (3) defining a housing (3a) extending along a longitudinal axis (A), said housing (3a) configured to house flow regulation means (6) suitable for regulating the passage of painting fluid coming from a source (8) of painting fluid, said painting gun (3) comprising an adjustment system (9) for controlling the maximum quantity of painting fluid that can be adjusted by said flow adjustment means (6) said flow regulating means (6) comprising a rod (6a) and an opening (7) defined by a portion of said gun (3), said rod (6a) being controlled to move with respect to said opening (7) and selectively cooperating in contact to close said opening (7) or to allow the passage of said painting fluid between said opening (7a) and said rod (6a), said adjustment system (9) comprising a wheel (10) configured to rotate around an axis (A) to vary the maximum stroke (H) of said rod (6a) with respect to said opening (7), said adjustment system (9) comprising actuator means configured to act alternatively on said wheel (10) to rotate it in a first rotation direction around said axis (A) and in a second rotation direction around said axis (A), opposite to the first.

2. - The gun according to Claim 1, wherein said adjustment system (9) comprises first actuator means (11') configured to move said wheel (10) in a direction of rotation around said axis (A) and second actuator means (11'') configured to move said wheel (10) in an opposite direction to that of said first actuator means (11''), said first and second actuator means (11', 11'') acting alternatively on said wheel (10).

3. - The gun according to Claim 1 or Claim 2, in which said actuator means (11) are pneumatic actuators.

4. - The gun according to one of the preceding claims, in which the actuator means (11) comprise:

- a support element (13) configured to be fixed to a support (4); - a tip (12) carried freely to the translation along an axis (C) by said support element (13); said tip (12) comprising a first end portion (12a) configured to cooperate in contact with said wheel (10) and a second end portion (12b) fluidically connected to a source (F) of pressurized fluid.

5. - The gun according to Claim 4, wherein said tip (12) is housed mobile and slidable inside an opening (15) made in said support element (13), said second end portion (12b) defining a sliding piston sealed in said opening (15) under the action of said source (F) of pressurized fluid.

6. - The gun according to one of Claims 4 or 5, wherein said wheel (10) comprises a plurality of seats (14) circumferentially arranged on said wheel (10), said first end portion (12a) being configured to cooperate selectively in contact with one of said seats (14) to exert a force on said wheel (10).

7. - The gun according to Claim 6, wherein said first end portion (12a) comprises a pawl (20) carried hinged on said first end portion (12a) and sized to cooperate in contact with one of said seats ( 14).

8. - The gun according to Claim 7, comprising thrust means (23) configured to exert a force against said pawl (20) so that said pawl, in use, engages in said seat (14).

9. - The gun according to one of Claims 4 to 8, comprising elastic means (17) configured to exert a force on said tip (12) contrary to that supplied by said source (F) of pressurized fluid.

10. - The gun according to one of the preceding claims, in which said wheel (10) comprises a fixed portion (10'') with respect to said body (3a) and a mobile portion (10^f) around said axis (A), said portion mobile (10^f) carrying a threaded shaft (32) cooperating by threading with said fixed portion (10^f '), said threaded shaft (32) moving along an axis (A), when said mobile portion (10^f) is rotated around to said axis (A), by varying said maximum stroke (H) of said rod (6a).

11. - The gun according to Claim 10, comprising angular adjustment means (35) configured to allow the assembly of said mobile portion (10') and said fixed portion (10'') of said wheel (10) in a relative angular portion fixed.

12. - A painting system (1) for painting an article, said painting system (1) comprising at least one painting assembly (2) equipped with a source (8) of painting fluid and a painting gun (3), said gun painting (3) being made according to any one of the preceding claims.