FR2698291A1 - Pneumatic fluid spray gun nozzle - has two angled pressurised gas jets impinging and defining axial fluid jet in metal turned piece retained by plastics nut - Google Patents

Abstract

The spray gun (1) nozzle (8) has an axial ejector orifice (9) for fluid spray and lateral orifices (11) for pressurised gas, defining the fluid jet shape. A plastics captive nut (14) retains a one-piece component (13), comprising both axial and lateral orifices, on the spray gun front. The one-piece component may be a brass or aluminium turning, with the fluid jet coaxial. Front projections (13B) contain the two diametrically-opposed gas jets, ahead of the fluid jet face (13E). A rear annular rim (13C) engages the captive nut. USE/ADVANTAGE - Paint or varnish spray, etc. Simple and quick to produce, low cost, effective in use, with little gas loss.

Description

The present invention relates to a nozzle for a pneumatic fluid spraying apparatus, as well as to a method for producing said nozzle.

These devices, commonly called spray guns, are more particularly intended, although not exclusively, for spraying paints, lacquers and other similar products.

Generally, this type of device comprises a nozzle through which the fluid to be sprayed is capable of leaving, and a nozzle, linked to the device and provided with an axial orifice which surrounds the nozzle, so as to form with it a space annular through which can escape the propellant, such as pressurized air, which mixes with the fluid to be sprayed. Also, in order to be able to modify the section of the jet of spraying fluid, then circular, in order to obtain a substantially flat jet thus allowing large areas to be covered quickly, said nozzle is provided with two lateral air ejection orifices, arranged so diametrically opposite from each other and converging towards the axis of the nozzle. By controlling the passage of pressurized air in these lateral orifices, the section of the spray is modified as desired according to the work to be done. carry out.

Structurally, the nozzles of this type then consist of a cylindrical cap, provided with said axial orifice and surrounding the fluid ejection nozzle by providing said annular space, with an external ring, surrounding the front part of the cap and provided two protrusions called horns and in which the lateral orifices are formed, and a clamping nut, surrounding an external rim provided in the rear part of the cap, said nut being intended to hold the end piece on the body of the device .

Also, to avoid leakage of pressurized gas, the cap and the ring are welded together, so that the nut must be mounted, prior to final assembly by welding, around the cap. The nut is then trapped between the protuberances of the ring and an external rim of the cap, which is applied against the body of the device under the action of the screwing of the nut, causing the external rim, on the body of the device.

From the above, it appears that the nozzles of this type are mechanically complex to produce and require numerous machining operations, in particular turning, and assembly, in particular by welding (cap-ring), which greatly enhances their cost. In addition, risks of leakage between the cap and the outer ring, welded together, may nevertheless appear.

The present invention aims to remedy these drawbacks and relates to a nozzle for a pneumatic fluid spraying device, the design of which is technically simple and rapid, while guaranteeing reliable operation in use.

To this end, the nozzle for a pneumatic fluid spraying device, of the type comprising an axial orifice for ejecting the sprayed fluid and lateral orifices for ejecting a gas under pressure to conform the jet of the sprayed fluid leaving said outlet. axial orifice, and a captive nut intended to be mounted on said apparatus, is remarkable, according to the invention, in that it comprises a monolithic part in which are provided said axial orifice and said lateral orifices, and in that said nut prisoner, linked to said part, is made of an elastically deformable material.

Thus, thanks to the invention, by making the nut of said end piece in an elastically deformable material, it is possible to design a monolithic part which combines both the cap and the ring initially used. Indeed, the mounting of the nut is then effected by elastic deformation of its wall, within the allowable elastic limit, which engages around the monolithic part while being held captive there and which spontaneously returns to its initial state .

Consequently, as the end piece only comprises two elements (monolithic part and nut) instead of the three initially provided (cap, ring and nut), its production is considerably simplified and also eliminates the welding operation and sealing problems that may have resulted before. In this way, the tip of the invention has increased operating reliability and its production cost is greatly reduced.

In a preferred embodiment, said monolithic part has a shape of revolution inside which said axial orifice is coaxially arranged, and it comprises two lateral protuberances, diametrically opposite from each other and provided respectively with said lateral orifices , and an external annular rim terminating the rear face of said piece, opposite its front face through which emerges said fluid jet, said nut being engaged and held captive between said lateral protuberances and said external annular rim. This monolithic part is for example made of a metallic material, such as brass or aluminum, because of their resistance to the pressures used and the paints and lacquers to be sprayed.

Furthermore, said nut can advantageously be provided with an axial through passage, the internal surface of its cylindrical wall of which comprises a thread, opening into the rear face of said nut facing towards said device, an internal annular rim extending the front face of said nut. and engaged around said monolithic part, and a recess located between the internal thread and the annular rim.

Thus, the nut is held captive by means of its internal rim between the lateral protuberances and the external rim of the monolithic part, said nut, although captive, being free in rotation and in translation.

For this, the outer diameter of the outer annular rim of said monolithic part is greater than the inner diameter of the inner annular rim of said nut when the latter is not elastically deformed, and less than this inner diameter, when said nut is elastically deformed for s 'Engage behind said external annular rim of the monolithic part.

In addition, an annular internal shoulder is formed in the wall of said passage, between said internal annular rim and said recess, the external rim of said monolithic part then being arranged in said shoulder when said nut is screwed onto the device.

Advantageously, said nut is made of a synthetic material, which is elastically deformable, which also makes it possible to reduce the mass of the endpiece.

Furthermore, the invention also relates to a method of producing such a nozzle for a pneumatic fluid spraying apparatus.

To this end, the method is remarkable in that - a monolithic part is produced having a shape of revolution and intended to allow the ejection, in the form of a jet, of the sprayed fluid and of a gas under pressure to conform the section of the fluid jet leaving the front face of said part - a nut is made of an elastically deformable material; and - said nut is forcibly assembled with said part, by elastic deformation of said nut so that it is mounted captive around said part, said nut being subsequently associated with the device.

More particularly, said assembly is carried out by engaging an internal annular rim provided in the axial passage of said nut, at its front face, between an external annular rim, provided on the rear face of the monolithic part, facing the front face of the nut, and lateral protuberances provided on said part.

 Advantageously, said assembly is carried out by the internal diary of a press, the fixed and movable parts of which receive said nut and said monolithic part, respectively, and a cylindrical member disposed between said nut and said part and having a frustoconical part. which is capable of engaging, under the action of the movable part of the press, in the internal rim of said nut by deforming it elastically and behind which said monolithic part is arranged, said frustoconical part having a small diameter at most equal to internal diameter of the internal rim of the nut, and a large diameter at least equal to the external diameter of the external rim of the part.

The figures of the appended drawing will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

Figure 1 is a partial sectional view of a spraying apparatus on which is mounted the spray nozzle according to the invention.

FIG. 2 represents an enlarged view in longitudinal section of said endpiece illustrated in FIG. 1.

Figures 3, 4 and 5 are schematic views showing the main phases of the process for assembling the monolithic part to the clamping nut, and thus form said nozzle.

The pneumatic spraying apparatus 1, shown in FIG. 1 and usually having the shape of a gun, is intended to be connected via a connector 2 to the fluid to be sprayed, such as paint, and a connection 3 to a source of pressurized gas, such as compressed air.

A fluid ejection nozzle 4 is mounted at the end of the body 5 of the device and it is in communication with the connector 2, screwed to the body and connected to the fluid. The ejection of the fluid through the nozzle 4 is carried out by a trigger 6 articulated to the body and capable of acting on an adjustable control mechanism 7 with a rod of the fluid to be sprayed, known per se.

The device 1 is also equipped with a nozzle 8, fixed to the body 5 by screwing and provided with an axial orifice 9 which surrounds the outlet orifice 4A of the nozzle 4, forming between it and the wall delimiting the axial orifice 9 an annular space 10. The compressed air, coming from the source and passing through the connector 3, can thus in a known manner escape towards the outside through this space 10 to spray the fluid leaving the nozzle and thus formed the jet of sprayed fluid. In addition, the nozzle 8 is provided with two lateral orifices 11 arranged symmetrically with the axis common to the nozzle and to the nozzle and converging towards the latter.

The orifices 11 are capable of being supplied with pressurized air via, here too, an adjustable control mechanism 12 with rod, provided in the body 5 of the device.

This nozzle 10, provided at the distal end of the body of said device, therefore allows the distribution of pressurized air to spray, via the axial orifice 9, the fluid leaving the nozzle 4 and to allow, via the orifices side 11, the variation of the section of the sprayed paint spray. If the lateral orifices 11 are closed, the jet of sprayed fluid has a circular section, while, when the lateral orifices 11 are opened, by the mechanism 12, the sprayed jet has a flattened section.

According to the invention and as shown in Figure 2, the tip 8 advantageously consists of a monolithic part 13 and a nut 14, mounted captive around the part 13 and made of an elastically deformable material.

More particularly, the monolithic part 13 has a shape of revolution, in which the axial orifice 9 is then provided, then stepped and intended, during the mounting of the end piece 8 on the body 5 of the device, to surround the nozzle 4 in providing, between the latter and the internal surface 1 3A delimiting the axial orifice 9, the abovementioned annular space 10. In addition, the monolithic part 13 is provided with two identical protuberances or lateral horns 13B, projecting from the part, diametrically opposite from each other.

In these horns 13B are respectively provided the lateral orifices 11 which are, in this embodiment, bent and whose outlet axes 11A converge towards the axis 9A of the axial orifice 9 of the monolithic part 13.

Furthermore, the latter comprises an external annular rim 13C terminating the rear face 13D of the part, facing the device and opposite its front face 13E through which the jet of fluid sprayed is likely to exit via the axial orifice 9. The nut 14 is then engaged behind the external rim 13C of the part while being held captive between this rim 13C and the horns 13B.

This nut 14 has an axial passage opening 14A and the internal surface 14B of its cylindrical wall 14C, which delimits the passage, comprises in this embodiment an internal thread 14D, a recess 14E and an internal annular rim 14F, in which a 14G shoulder. More particularly, the internal thread 14D opens into the rear transverse face 14H of said nut 14 and it is intended to cooperate with a corresponding thread provided at the distal end 5A of the body 5 of the device. The front transverse face 14I of said nut is extended, perpendicular to the axis of said passage 14A, by the internal annular rim 14F and, between the internal rim 14F and the internal thread 14D is formed the recess 14E. Also, the shoulder 14G is formed on the rear side of the internal annular rim 14F, while being adjacent to the recess 14E.

Thus, it can be seen in FIG. 2 that the internal annular flange 14F of the elastically deformable nut 14 is engaged between the external annular flange 13C and the horns 13B of the monolithic part 13, so that the nut 14, although free to turn around the part and to translate between the rim 13C and the horns 13B, is held captive around the monolithic part.

When the end piece 10 is mounted by screwing the nut 14 onto the body 5, the external annular rim 13C of the part engages in the internal annular shoulder 14G of the nut, the rear face 13D of said part being pressed between a deflector ring 15 usually provided at the distal end of the device and surrounding the nozzle 4 which holds it against the body.

Such assembly of the nut 14 to the part 13 is made possible by the elastically deformable material constituting the nut, which makes it possible to design a part 13 advantageously monolithic. In this way, the nozzle 8 no longer comprises only two elements (part 13 and nut 14) instead of the three usually used.

Also, the nut 14 can be made of a synthetic material, for example Delrin (registered trademark), which further reduces the weight of the nozzle. As for the monolithic part 13, it is preferably made of a metallic material such as brass or aluminum, although it may possibly be designed in a synthetic material, for example identical to that of said nut.

 Obviously, the diameter of the internal annular flange 14F of said nut 14 is such that, when the nut is not deformed, it is less than the diameter of the external annular flange 13C of part 13, and when the nut is deformed to engage around the part, its diameter is greater than that of the outer rim 13C. The deformation of the nut when it is assembled to the part always remains below the allowable elastic limit.

A particular example of an assembly process between the nut 14 and the monolithic part 13 is schematically illustrated with reference to FIGS. 3 to 5. In this exemplary embodiment, the assembly is effected by force using a press 17 and a suitable cylindrical member 18 for deforming the nut.

First of all, it is specified that the monolithic part 13 is advantageously obtained by forging, then turning operations allow the front faces 13E and rear 13D to be finished, as well as the stepped axial orifice 9. The lateral orifices 11, not shown in these figures, can be made later by drilling. The nut 13 is obtained from a hollow bar made of a suitable synthetic material, elastically deformable, and turning operations make it possible to execute the internal surface 14B of the axial passage 14A and the rear and front faces 14H, 14I.

As shown in Figure 3, the monolithic part 13 is arranged in the movable part 17A of the press while being held there, its external annular rim 13C being turned outwards, while the nut 14 is housed in a corresponding recess 17C practiced in the fixed part 17B of the press.

Furthermore, the cylindrical member 18 is disposed between the part 13 and the nut 14. More particularly, this member 18 has a circular part 18A which engages in order to be guided in a corresponding hole 17D provided, coaxially with the shoulder 17C, in the fixed part 17B, and a frustoconical part 18B, the small diameter of which is at least less than the internal diameter of the flange 14F of said nut and the large diameter of which is at least equal to the external diameter of the flange 13C of said monolithic part. The circular cylindrical part 18A is then introduced into the bore 17D until the frustoconical part 18B rests by one of its generatrices, close to the small diameter, against the edge 14J of said flange 14F. The flange 13C of the part is arranged in a corresponding annular recess 18C provided in the large transverse face 18D terminating the frustoconical part.

When the movable part 17A of the press is controlled, it pushes, according to the arrow F shown in FIG. 5, the assembly consisting of the member 18 and the part 13 in the direction of the nut 14 secured to the fixed part 17B.

During its movement, the frustoconical part 18B of the member gradually and elastically deforms the rim 14F, as well as the wall part 14C located at the recess 14E. It is therefore understood that the latter facilitates the elastic deformation because the thickness of the wall 14C of said nut is at its reduced level.

The deformation of the nut 14, in its plane, of course remains within the elastic limit inherent in the synthetic material.

 When the large face 18D of the frustoconical part 18B of the member, and the external rim 13C of the part have crossed the internal rim 14F of said nut, the natural elasticity of the material constituting it spontaneously returns, to its initial state, the internal annular rim 14F and the wall part 14C of said nut. At this time, as shown in FIG. 5, the internal annular rim 14F of said nut is trapped in the space of the monolithic part 13 comprised between the lateral horns 13B and the external annular rim 13C. The end piece 8 thus assembled is then removed from the press 17.

Thereafter, various finishing operations are carried out (drilling of the lateral orifices, deburring, nickel plating of the monolithic part, etc.) and of checking said end piece thus formed.

Claims (10)

1 - Nozzle for pneumatic fluid spraying device, of the type comprising an axial orifice (9) for ejecting the sprayed fluid and lateral orifices (11) for ejecting a gas under pressure to conform the jet of the sprayed fluid in outlet of said axial orifice, and a captive nut (14) intended to be mounted on said apparatus, characterized in that it comprises a monolithic part (13), in which said axial orifice (9) and said lateral orifices (11) are provided ), and in that said captive nut (14), linked to said part, is made of an elastically deformable material. 2 - End piece according to claim 1, characterized in that said monolithic part (13) has a shape of revolution inside which is coaxially formed said axial orifice (9), and in that it comprises two lateral protuberances ( 13B), diametrically opposite from each other and provided respectively with said lateral orifices, and an external annular rim (13C) terminating the rear face (13D) of said part, opposite its front face (13E) through which said outlet fluid jet, said nut (14) being engaged and held captive between said lateral protuberances and said external annular flange. 3 - End piece according to one of claims 1 or 2, characterized in that said monolithic part (13) is made of a metallic material, such as brass or aluminum. 4 - End piece according to one of the preceding claims 1 to 3, characterized in that said nut (14) is provided with an axial through passage (14A), the internal surface (14B) of its cylindrical wall (14C) comprises a internal thread (14D), opening into the rear face (14H) of said nut facing towards said device, an internal annular rim (14F) extending the front face (14I) of said nut and engaged around said monolithic part, and a recess (14E) located between the internal thread and the internal annular rim. 5 - End fitting according to claims 2 and 4, characterized in that the outside diameter of the external annular rim (13C) of said monolithic part (13) is greater than the inside diameter of the internal annular rim (14F) of said nut (14) when this the latter is not elastically deformed, and less than this internal diameter, when said nut is elastically deformed to engage behind said external annular rim of the monolithic part. 6 - End piece according to claim 4, characterized in that an annular internal shoulder (14G) is formed in the wall of said passage, between said internal annular rim (14F) and said recess (14E), the external rim (13C) of said monolithic part being arranged in said shoulder when said nut is screwed onto the device. 7 - End piece according to one of the preceding claims 1 to 6, characterized in that said nut (14) is made of a synthetic material, elastically deformable. 8 - Method for producing a nozzle for a pneumatic fluid spraying device, as specified in any one of the preceding claims, characterized in that - a monolithic part (13) is produced having a shape of revolution and intended for allow the ejection, in the form of a jet, of the sprayed fluid and of a gas under pressure to conform the section of the jet of fluid leaving the front face of said part - a nut (14) is made of an elastically deformable material ; and - said nut is forcibly assembled with said part, by elastic deformation of said nut so that it is mounted captive around said part, said nut being subsequently associated with the device. 9 - Method according to claim 8, characterized in that said assembly is carried out by the engagement of an internal annular flange (14F) provided in the axial passage of said nut (14), at its front face, between an annular flange external (13C), provided on the rear face of the monolithic part (13), facing the front face of the nut, and lateral protuberances (13B) provided on said part.  10 - Method according to claim 9, characterized in that said assembly is carried out by means of a press (17), whose fixed (17A) and movable (17B) parts respectively receive said nut (14) and said monolithic part (13), and of a cylindrical member (18), disposed between said nut and said part and having a frustoconical part (18B) which is capable of engaging, under the action of the movable part of the press , in the internal rim of said nut by deforming it elastically and behind which said monolithic part is arranged, said frustoconical part (18B) having a small diameter at most equal to the internal diameter of the internal rim (14F) of the nut, and a large diameter at least equal to the outside diameter of the external rim (13C) of the part.