HK1224248B - An automatic apparatus for pneumatic painting - Google Patents

Description

Automatic equipment for pneumatic painting

Technical Field

The present invention relates to rotary-bell air spray equipment of the type used in industrial painting facilities.

In particular, the device is applied in automatic painting systems using equipment for the continuous production of a carrier fluid, the carrier fluid being obtained starting from compressed ambient air.

Background Art

It is known in automated painting systems to use an automated arm that carries at its end an operating head for air spray painting, consisting of an air gun or a rotary bell device of the conventional or electrostatic type. In the first case, the system delivers to the gun a carrier fluid stream for atomizing the paint and a second carrier fluid stream for forming a paint fan or shaping air.

In case of a rotating bell, the system delivers to the painting head a central paint flow, a first pressurized fluid flow for the rotation of the bell, a second circumferential pressurized fluid flow for atomizing and mixing the paint and thus forming a paint cone or shaping air.

Currently, in automatic industrial systems for atomizing paint, compressed air with a pressure generally not lower than 3-6 barG is usually used as the propelling carrier fluid.

However, the control of the paint cone or paint fan (shaping air) by automated automatic painting systems of known type is not satisfactory and suffers from the phenomenon of overspray, ie the loss of paint which does not reach the substrate to be painted but is dispersed in the painting environment.

Another disadvantage is that relatively high pressures have to be used in order to compress the carrier fluid and achieve a sufficiently high velocity of the atomized paint impacting the substrate to be painted.

Purpose of the Invention

Therefore, a first object of the present invention is a device which does not have the aforementioned drawbacks of the known systems and which makes it possible to increase the density of the shaping air so as to atomize the paint more effectively, while at the same time reducing the pressure of the carrier fluid required for atomization.

Summary of the Invention

The above and further objects are achieved by a device according to one or more of the accompanying claims.

A first advantage of the present invention is that the density of the atomized paint is greater than that achieved with known systems, allowing the coating of the substrate to be significantly improved in terms of coverage, coating speed, and grip of the paint layer deposited on the substrate. Another advantage is that this system allows for increased efficiency in the transfer of the paint to the object being painted, significantly reducing overspray due to the reduced pressure and higher density. Another advantage is that, due to the higher density of the carrier, this system allows the bell to be brought closer to the object being painted to achieve greater thickness uniformity, thereby also reducing the overspray effect and, in the case of electrostatically rotating bells, reducing electrostatic forces.

Another advantage is that the number of spray applications is reduced and the same thickness is achieved in a single coat, thereby significantly reducing cycle times in automated systems such as those used for painting car bodies, vehicle components or other similar items.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages will be better understood by a person skilled in the art from the following description and the accompanying drawings, which are provided purely by way of non-limiting example, in which:

FIG1 is a schematic diagram of an apparatus according to the present invention.

FIG. 2 is a top view of the device in FIG. 1 .

Figure 3 shows an automatic painting arm carrying an atomising device.

Figure 4 shows an automatic painting arm carrying a rotating bell arrangement.

FIG. 5 shows an example of a rotary bell air painting device of known type.

DETAILED DESCRIPTION

With reference to the accompanying drawings, an automatic air painting installation of the type described is described, comprising a module 17 for producing a pressurized carrier fluid flow, which is obtained starting from a compressed air source 1 and conveyed to at least one automatic painting installation 2, which is equipped with an automated arm 3, which is provided with an operating head 30 for air painting, the operating head 30 having a first paint outlet 4 and at least one second outlet 5 for the pressurized fluid flow, the second outlet 5 being arranged around the first outlet to form a paint cone or paint fan.

The device 2 schematically shown in Figures 3 and 4 also comprises a pipe 6 for supplying a paint flow from a paint source to the first paint outlet 4, and a pipe 7 for supplying a pressurized fluid flow for atomizing said paint flow. The pipe 7 may or may not coincide with another pipe 8 for supplying a pressurized fluid flow conveyed to the second outlet 5.

According to the invention, the module 17 is a hollow fiber separation module supplied by a source of pressurized ambient air 1 for continuously producing a carrier fluid stream consisting of high-purity nitrogen, preferably of 98% to 99.9%, and comprises means 19, 25, 26 for regulating the pressure of the produced nitrogen at the outlet 38 for pressurized nitrogen, the pressure of which is regulated to between 0.5 and 4 bar, preferably between 0.5 and 1.5 bar, and the temperature of which can be adjusted to between 8°C and 80°C, preferably between 8°C and 22°C, as well as means 18, 9 for thermally regulating the nitrogen stream.

According to another advantageous characteristic of the invention, the device also comprises an adjustable heated pipe 29 for thermal stabilization of the nitrogen flow leaving the separation module 17 .

In operation, the module 17 is connected to a control unit 50 which manages the automatic operation of the device, in particular the movements and operating cycles of the device 2 and enables the setting of the parameters for the production of the carrier fluid (purity, temperature, pressure) and the painting parameters (speed, displacement, number of sprays).

Advantageously, by this solution, the density of the atomized paint is significantly increased, since nitrogen, due to its higher specific gravity, can be fed to the tube 7 at a relatively low pressure and at a temperature adjusted to the painting environment conditions and the type of substrate to be painted.

In a preferred embodiment, the device comprises an ionization unit 28, known per se, capable of ionizing a nitrogen stream with positive or negative charge or in a neutral plasma state.

FIG3 shows a painting device in which the operating head is a rotary bell device (of the type known per se according to FIG5 ), comprising a rotary bell 10 caused to rotate by a pneumatic motor driven by a pressurized fluid flow supplied by a pipe 14 , which may or may not be consistent with the fluid used as carrier fluid.

A bell-shaped element 10 is centrally located at one end 11 of the arm 3 and is provided with a first paint outlet 4 connected to the paint supply pipe 6, for centrifugally scattering the paint flow towards the edge of the bell. The operating head 30 also comprises a ring 12 upstream of the bell-shaped element, provided with a nitrogen outlet 5 directed towards the bell-shaped element in the coating direction X and connected to the pipe 7 supplying the nitrogen flow for atomization, which in this case also performs the function of forming the paint cone 13.

In the painting device shown in FIG4 , the operating head is an air paint spray gun comprising a first paint outlet 4 provided at the end 11 of an arm 3 and connected to a paint supply pipe 6 and a pipe 7 for supplying a nitrogen flow for atomization. In this case, the paint flow and the nitrogen flow for atomization converge at a point 31 upstream of the first paint outlet 4 in a manner known per se and not further described.

The operating head 30 also has at least two lateral nitrogen outlets 5 , which communicate with a pipe 8 that supplies a nitrogen flow for forming the paint fan 16 .

1 and 2 , a preferred embodiment of a module 17 for producing a carrier fluid is described, which envisages a first hollow fiber separation membrane 20 supplied by a compressed air source 1 provided with a filter 33 and connected at its outlet to a first container 21 storing nitrogen (or nitrogen-enriched modified air), the first container 21 in turn being connected at its outlet to a second hollow fiber separation membrane 22 which delivers high-purity nitrogen to a second container 23 storing pressurized nitrogen.

In the example described, the thermal regulation means comprise a cooling and/or heating assembly 18 which receives the nitrogen stream leaving the container 23 , preferably through an insulated pipe 32 , and is able to stabilize the temperature of the nitrogen stream at a value adjustable between 8° C. and 80° C.

The heat regulating device may further comprise a heater 26 arranged at the inlet to the first membrane 20, capable of heating the air to a temperature between 10°C and 60°C, and an external heater 9 for heating at least the membrane 20, which also functions within a temperature range between 10°C and 60°C.

Once again in the preferred example shown, the means for regulating pressure are a pressure regulator 19 arranged downstream of the compressed air source 1, a flow regulating valve 24 arranged immediately downstream of one or both of the membranes 20 and 22, and a back pressure regulating valve or back pressure regulator (BPR) 25 arranged immediately downstream of one or both of the containers 21 and 23.

Preferably, the compressed air from the supply source 1 passes successively through a pressure regulator 19, a solenoid valve 34, a progressive actuator 35 for splitting the flow, and a heater 26 before entering the membrane 20. Advantageously, with this solution, the feeding of the compressed air to the membrane also takes place at the beginning of operation under adjustable optimal conditions, thanks to the control of the pressure and temperature and the progressive actuator 35 which prevents the entire compressed air flow from being introduced into the membrane at once.

In some application examples, it was found that excellent painting results can be achieved with the parameters shown below.

Example 1

Painting plastics at 20°C

- Purity: 99.5%

- Pressure is 2 bar

- Temperature is 18°C

- Positive ionization

Example 2

Metal substrate

- 99% purity

- Pressure is 1.8 bar

- Temperature is 18°C

- Negative ionization

The invention has been described according to preferred embodiments, but equivalent variants are conceivable without thereby departing from the scope of protection of the invention.

Claims (12)

1. An automatic air spray painting device, comprising: At least one painting device (2), the painting device (2) being equipped with an automated arm (3), the automated arm (3) having a painting operation head (30), the painting operation head (30) comprising: First paint export (4); and At least one second outlet (5) for forming a fluid flow in a pressurized paint cone or paint fan; A paint supply pipe (6) supplies paint flow from the paint source to the first paint outlet (4); A pipe (7) for supplying a pressurized fluid flow for atomizing the paint stream; A pressure-controlled paint cone or paint fan forming fluid flow is supplied to the second outlet via a pipe (8) for forming the paint cone or paint fan; The device is characterized in that it comprises: Separation module (17), supplied by a pressurized ambient air source (1), is used to continuously produce a pressurized fluid stream consisting of 98%-99.9% high-purity nitrogen, the pressurized fluid stream being directed to the first paint outlet (4) to atomize the paint stream and the at least one second outlet (5) to form a paint cone or paint fan; Regulating devices (19, 24, 25) for adjusting the pressure of the nitrogen stream used for atomization; and Adjustable thermal conditioning devices (18, 9, 26) for atomizing nitrogen streams; The separation module includes: A first hollow fiber separation membrane (20) is supplied by the pressurized ambient air source (1) and is connected to a first nitrogen container (21) at its outlet. The second hollow fiber separation membrane (22) is connected to the first container (21) at its inlet and to the second container (23) of pressurized nitrogen at its outlet, which in turn is connected to the outlet (38) of pressurized nitrogen. The regulating devices (19, 24, 25) are used to regulate the pressure of the nitrogen flow at the outlet (38) of the pressurized nitrogen to a pressure between 0.5 and 4 bar; the adjustable thermal regulating devices (18, 9, 26) are used to cool or heat the nitrogen flow at the outlet (38) of the pressurized nitrogen to a temperature adjustable between 8°C and 80°C. 2. The device according to claim 1, wherein the regulating device (19, 24, 25) for regulating pressure is configured to maintain the pressure of the nitrogen flow between 0.5 and 1.5 bar. 3. The device according to claim 1, wherein the thermal regulation device (18, 9, 26) is configured to maintain the nitrogen flow at a temperature regulated between 8°C and 22°C. 4. The device according to claim 1, characterized in that the operating head is a rotating bell-shaped air coating device, the operating head comprising: A rotating bell-shaped member (10) is disposed at one end (11) of the arm (3), the rotating bell-shaped member (10) having a first paint outlet (4) communicating with the paint supply pipe (6) for performing centrifugal scattering of the paint flow toward the edge of the bell-shaped member (10); and A ring (12) is disposed upstream of the bell-shaped component, the ring (12) having a second outlet (5) for nitrogen, the second outlet (5) being directed toward the bell-shaped component (10) in the painting direction (X) and communicating with a pipe (7) for supplying nitrogen for atomization and for forming a paint cone (13). 5. The device according to claim 1, wherein the operating head is an air spray gun, and the operating head comprises: A first paint outlet (4) is provided at the end (11) of the arm (3), the first paint outlet (4) is connected to the paint supply pipe (6), and is also connected to the pipe (7) supplying nitrogen flow for atomization; and At least two second outlets (5) for nitrogen are connected to a pipe (8) for supplying nitrogen flow. The second outlets (5) are arranged side by side with the first paint outlet to form a paint fan (16). 6. The device according to claim 1, wherein the thermal regulation device includes components for cooling/heating the nitrogen stream exiting the separation module (17). 7. The device according to claim 1, wherein the regulating device for regulating pressure includes a pressure regulator (19) disposed downstream of the pressurized ambient air source (1). 8. The device according to claim 1, characterized in that it includes a flow regulating valve (24) and a back pressure regulating valve (25); The flow control valve (24) is immediately following the first hollow fiber separation membrane (20) and is located downstream of the first hollow fiber separation membrane (20); The back pressure regulator valve (25) is immediately following the first nitrogen container (21) and is located downstream of the first nitrogen container (21). 9. The device according to claim 1, wherein the heat regulation device comprises a heater (26) for heating the airflow leading to the inlet of the first hollow fiber separation membrane (20). 10. The device according to claim 1, wherein the thermal conditioning device comprises an external heater (9) for heating at least one membrane (20, 22). 11. The device according to claim 1, characterized in that the device includes an adjustable heating tube (29) for thermal stabilization of the nitrogen flow exiting the separation module (17). 12. The device according to claim 1, wherein the device comprises a component (28) for ionizing a nitrogen stream exiting the separation module (17), the component (28) being adjustable for producing positive ions, negative ions or plasma.