US3782632A

US3782632A - Powder spray gun for spraying different color powders from a powder channel of a spray gun

Info

Publication number: US3782632A
Application number: US00277082A
Authority: US
Inventors: F Braun; P Ribnitz; W Huber
Original assignee: Gema AG
Current assignee: Gema AG Apparatebau; Gema Switzerland GmbH
Priority date: 1971-08-02
Filing date: 1972-08-01
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: JPS5547943B2; IT961775B; CA964242A; DE2237507B2; FR2149795A5; GB1395548A; JPS4826555A; CH539461A; DE2237507A1

Abstract

A powder spray gun for spraying different color powders from a powder dispensing channel of the spray gun, with a connection mechanism possessing a number of connections at which there can be connected infeed conduits for different powder-conveying airmixtures and flushing air and through the agency of which there can be delivered to the spray gun-powder dispensing channel a selected powder-conveying air-mixture for spray coating thereof and flushing air for cleaning of such spray gun. The connection mechanism comprises a connection element carrying the connections, this connection element containing for each connection a continuous substantially straight connection channel. The connection element and the pistol body member containing the powder dispensing channel can be adjusted relative to one another in such a manner that the connection channels of the connection element can be connected by means of their outlet openings with the inlet opening of the powder dispensing channel in a certain sequence and with a given distribution of the infeed conduits for the powder-conveying air-mixture and the flushing air at the connections of the connection element the spray gun powder dispensing channel is flushed with flushing air during each color change.

Description

United States Patent [191 Braun et al.

[111 3,782,632 11 Jan. 1,1974

Willi Huber, both of St. Gallen, all of Switzerland [73] Assignee: Gema AG Apparatebau, St. Gallen,

Switzerland 22 Filed: Aug. 1, 1972 211 Appl. No.: 277,082

Related US. Application Data [63] Continuation-impart of Ser. No. 198,816, Nov, 15,

1971, abandoned.

[30] Foreign Application Priority Data Aug. 2, 1971 Switzerland 1. 11345/71 Mar. 24, 1972 Switzerland 4417/72 [52] US. Cl. 239/112, 239/305, 239/397, 222/1445 [51 Int. Cl. B051) 7/02 [58] Field of Search 239/397, 394, 305, 239/390, 396, 450, 538, 540, 112; ZZZ/144.5; 137/6254], 605

FORElGN PATENTS OR APPLICATIONS 56,982 10/1952 France ..239/396 770,336 10/1934 France ..239/305 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-John J. Love Attorney-Karl W. Flocks- 57 ABSTRACT A powder spray gun for spraying different color powders from a powder dispensing channel of the spray gun, with a connection mechanism possessing a number of connections at which there can be connected infeed conduits for different powder-conveying airmixtures and flushing air and through the agency of which there can be delivered to the spray gun-powder dispensing channel a selected powder-conveying airmixture for spray coating thereof and flushing air for cleaning of such spray gun. The connection mechanism comprises a connection element carrying the connections, this connection element containing for each connection a continuous substantially straight connection channel. The connection element and the pistol body member containing the powder dispensing channel can be adjusted relative to one another in such a manner that the connection channels of the connection element can be connected by means of their outlet openings with the inlet opening of the powder dispensing channel in a certain sequence and with a given distribution of the infeed conduits for the powder-conveying air-mixture and, the flushing air at the connections of the connection element the spray gun powder dispensing channel is flushed with flushing air during each color change.

6 Claims, 11 Drawing Figures PATENTEU 1 1974 SHEET 2 BF 5 FIG. 3

FIG. 5

9 QP QQQO POWDER SPRAY GUN FOR SPRAYING DIFFERENT COLOR POWDERS FROM A POWDER CHANNEL OF A SPRAY GUN This is a continuation-in-part of copending parent application Ser. No. 198,816 filed Nov. 15, 1971, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to a new and improved powder spray gun or pistol for spraying or coating different color powders from a spray gun-powder dispensing channel and incorporating a connection mechanism possessing a number of connections, at which connection mechanism there can be connected infeed conduits for different powder-conveying air-mixtures and flushing air and through the agency of which there can be delivered to the spray gun-powder dispensing channel a selected powder-conveying air-mixture for spraying or coating purposes and flushing air for cleaning of such spray gun.

Now for the purpose of spraying different color liquid coating agents by means of a spray gun the prior art is acquainted with dye infeed devices which can be mounted upon a spray gun. With the heretofore known color or dye infeed devices a distributor provided with a continuous channel is generally arranged in a housing possessing inlet openings with connections for connecting infeed conduits for the different color coating agents and also having a common outlet channel. The distributor allows for the selective connection of each inlet opening with the outlet channel. In order to clean the distributor channel and the spray gun during each color change it was common practice to permit a new color to pass through the pistol for such time until the mixed color shade disappeared. To that end means were provided at an infeed mechanism for the purpose of opening a needle valve of the spray gun for the discharge of the color or dye when the atomization air was shut-off. Such infeed mechanisms are unsuitable for powder spray guns since the color powder tends to deposit at certain locations of the channel and the deposited powder can again loosen at some time during spraying of the new color powder, so that after the color change operation there is no longer ensured for spraying of a clean true color.

SUMMARY OF THE INVENTION Hence, from what has been explained above it should be apparent that this particular field of technology is still in need of powder spray guns for spraying different color powders in a manner not associated with the aforementioned drawbacks and limitations of the heretofore proposed constructions in the art. Thus, it is a primary object of the present invention to provide an improved construction of powder spray gun which effectively and reliably fullfils the existing need in the art and is not associated with the aforementioned drawbacks and limitations of the prior art proposals considered above.

Another and more specific object of the present invention relates to a new and improved construction of powder spray gun having a color change or switching mechanism by means of which as a practical matter there does not occur any color defects or flaws during switch-over from one color to another.

Yet a further significant object of the present invention relates to an improved spray gun for spraying dif' ferent color powders incorporating means for effectively switching the spray gun for operation from one powder color to another powder color without any deleterious interblending of the different powder colors.

Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the connection mechanism embodies a connection element carrying the connections, this connection element is provided with a continuous linear or straight channel for each connection. The connection element and a pistol body member containing a powder dispensing channel can be adjusted relative to one another in such a manner that the channels of the connection element can be connected by means of their outlet openings with the inlet opening of the powder dispensing channel in a certain sequence and for a corresponding distribution of the infeed conduits for the powder-conveying airmixture and the flushing air at the connections of the connection element the spray gun-powder dispensing channel is flushed with flushing air during each color change.

During a color change it is only necessary to adjust the infeed conduit conveying the new color and upon setting or adjustment of this infeed conduit the spray gun-powder dispensing channel is temporarily connected with the flushing air-infeed conduit and cleaned of the previously sprayed powder, the pressure of the flushing air not being sufficient to atomize the powder in a manner appropriate for coating purposes, so that there is always only atomized a pure color powder. The connection element and the pistol body member can possess oppositely situated or confronting surfaces into which open the connection channels and the powder dispensing channel. At the the of th connection element there are arranged in a row the outlet opening of all connection channels with a center point arranged along a line, the connection element and the pistol body member can be moved relative to one another along this line for adjusting the outlet openings of the connection channel with respect to the inlet opening of the powder dispensing channel and with an appropriate shape of the pistol body member and whenever an outlet opening is adjusted to the inlet: opening the surface of the pistol body member covers all of the remaining outlet openings. Such arrangement of the connection channels, wherein the outlet openings thereof are arranged in a row, renders possible a distribution of the infeed conduits feeding the powder-conveying airmixture and the flushing air with respect to the connections of the connection element in such a manner that between each two infeed conduits conveying the pow der there is arranged an infeed conduit conveying flushing air. As a result, during each color-change operation the powder dispensing channel of the pistol body member is automatically connected for flushing purposes with an infeed conduit for flushing air.

The confronting surfaces of the connection element and the pistol body member can be planar or flat and the outlet openings of the connection channels can be uniformly distributatively arranged along a circle or an are, so that the connection element can be designed as a circular disk or sector-shaped plate and rotatably mounted at an axis of rotation of the pistol body member. In order to be able to arrange a number of spray guns above one another, something which is oftentimes desired, the connection element is advantageously designed as a flat or planar slide wherein the outlet openings of the connection channels are located along a straight line. The pistol body member can also be designed in the form of a rod having an axial powder channel, wherein the end of the powder channel is outwardly curved, and wherein the inlet opening is located at a cylindrical jacket surface of the pistol body member at which there is rotatably mounted a connection element in the form of a hollow cylinder. The outlet openings of the connection channels are then located at a periphery or a portion thereof in a uniformly distributed manner at the inner jacket surface of the connection element.

In order to prevent any line grinding or rubbing of the powder between the pistol body member and the connection element and having such arrive as a defective color at the powder channel the inlet opening of the powder channel is surrounded by a sealing ring which protrudes past the surface of the pistol body member in order to only always seal-off the connection channel which has been momentarily set at the outlet opening and to further maintain a small gap between the surfaces of the connection element and the pistol body member through which leakage air can escape from the flushing air-infeed conduits for continuous flushing purposes. Such or similar type designs allow for a particularly economical construction of the spray gun or pistol. Since, however, a color powder-infeed conduit only can be connected at each second connection of the connection element there are required for the spraying of different colors a number of small and easy to use or a number of large and therefore difficult to handle devices. According to a preferred embodiment of the invention a connection element constructed for instance in the form of a truncated cone thus contains a central connection channel which can be connected at a flushing air-infeed conduit and a number of connection channels arranged about such connection channel which can be connected with the powder infeed conduits. The connection element is secured through the agency of a Cardan suspension or mounting to the pistol body member in such a manner that it can be pivoted out ofa starting position in which the central connection channel is located at the inner opening of the powder dispensing channel at the pistol body selectively into positions in which a respective outer connection channel can be connected with the powder dispensing channel. For adjusting the connection element there can be provided suitable adjustment means such as pneumatic cylinder means or lifting magnets wherein upon switching-in one of them it is possible to pivot the connection element from the starting position into an appropriate working position and upon switching-off the adjustment means such connection element can be again placed back into its starting position in which flushing of the spray gun occurs. The transfer and grinding of the powder in this case is extremely negligible since the surfaces which cover or overlap one another during the switching operation, and which come into contact with different powders, are small. The connection element is advantageously mounted by means of a Caradan joint at a casing or lining of the pistol body member. This casing renders possible dispensing with a cover for the connection channels conveying the individual powders, since any possibly present powder can be sucked-out of the inner compartment.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a schematic illustration of a spray installation containing a powder spray gun or pistol;

FIG. 2 is a longitudinal sectional view through an embodiment of powder spray gun for spraying different color powders and provided with a connection mechanism for switching colors;

FIG. 3 is a fragmentary sectional view of the spray gun depicted in FIG. 2, taken substantially along the line IIIIII thereof;

FIG. 4 is a schematic illustration of the connection element and gun illustrated in FIG. 2;

FIG. 5 is a schematic illustration of a sector-shaped connection element;

FIG. 6 is a schematic illustration ofa connection element which can be displaced relative to the spray gun;

FIG. 7 is a longitudinal sectional view of a further embodiment of spray gun and the therewith connected connection mechanism;

FIG. 8 is a longitudinal sectional view of still a further embodiment of spray gun and therewith connected connection mechanism;

FIG. 9 is an end view of the arrangement depicted in FIG. 8;

FIG. 10 is a longitudinal sectional view of a powder spray gun with color switching mechanism of a further exemplary embodiment; and

FIG. 11 is an end view of the connection element as viewed along the line XIXI of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, and turning attention initially to the exemplary illustrated embodiment of apparatus depicted in FIG. 1 serving for the powder coating of articles or the like, such will be seen to incorporate, for instance, six powder containers 1 containing six different color powders. At the lower end of each such funnel-shaped powder container 1 there is arranged a respective associated injector 2. Conveying air is delivered to each injector 2 by means of a'respective associated conveying line or conduit 4 provided with a respective suitable shut-off valve 3. An infeed conduit and line 5 leads from each injector 2 to a common connection mechanism 7. Additionally, there is also connected with this connection mechanism 7 a flushing air conduit or line 6.

A gun or pistol 8 of conventional design is directly mounted in operable association at the connection mechanism 7. Connection mechanism 7 can be adjusted into different positions, so that when assuming a first given position one of the powder infeed conduits 5 is placed in flow communication with the spray gun 8 and there is carried out a coating operation by means of the relevant color powder received from one of the associated containers 1. All of the other powder infeed conduits 5 and also the flushing air conduit 6 are sealed in this first position with respect to the spray gun 8, that is to say, do not flow communicate with the spray gun 8 in this first position of the connecting mechanism 7. During a color-change operation the connecting mechanism 7 is first of all adjusted so as to assume a position such that the flushing air-infeed conduit 6 is now connected with the spray gun 8. Consequently, spray gun 8 is flushed by clean air through the agency of the connection mechanism 7. Thereafter, this connection mechanism 7 can be adjusted into a position where coating with a different color can occur.

With the embodiment of spray gun 8 and connection mechanism 7 as depicted in the embodiment of FIGS. 2 and 3 there is provided a cover plate 10 at the stationary gun body member 9, of which only a portion has been shown. A bearing pin or journal 11 is fixedly seated at cover plate 10, and a substantially diskshaped connection element or portion 12 is rotatably mounted at such bearing pin 11. This closure element 12 possesses eight connections 13 constructed in the form of studs 13a for the connection of a like number of conduit hoses, such as the schematically illustrated conduit hose 50 of FIG. 2. Each connection 13 is provided with a continuous connection channel 18. The outlet or discharge openings 19 of these channels 18 are all located at an end surface or face of the connection element 12.

As best seen by referring to FIG. 4 a respective powder infeed conduit Ae and a flushing air-infeed conduit Sp are alternately connected with the connections 13. Upon rotating the connection element 12 the powder infeed conduits Ae and the flushing air-infeed conduits Sp are alternately brought into flow communication with the spray gun-powder dispensing channel 14.

When one of the powder infeed conduits Ae is placed into flow communication with the spray gun-powder dispensing channel 14 then it is possible to carry out a coating operation with a certain desired powder color. Upon rotating the connection element 12 and during a color-change operation always one of the flushing airinfeed conduits Sp moves past the spray gun-powder dispensing channel 14, so that the spray gun is always cleaned before beginning coating with a different powder color.

At the gun end surface or face 16 there is provided a sealing ring'l5 about the inlet opening 17 of the powder dispensing channel 14, and by means of which sealing ring 15 there is obtained good sealing of the momentarily set connection channel 18. The outlet openings 19 of the remaining connection channels 18 are covered by the closure plate 10, whereby however no sealing ring is provided between such cover plate 10 and the connection element 12, so that there is prevented escape of color powder from the corresponding connection channels, whereas leakage air departing from the flushing air-infeed conduits Ae continuously flushes the gap between the

components

10 and 12 and thus also brings about a certain rearward displacement of the color powder out of the associated connection channels. What has been discussed above is also analogously applicable for the embodiments of the invention to be described hereinafter. The cover plate 10 for the disk-shaped form of the connection element 12 depicted in FIGS. 2 and 4 is of the same size as the connection element 12, so that the space requirements for this arrangement are small. The flexible hoses 50 (only one of which has been shown in FIG. 2) connected with the connection element 12 permit rotation of such element.

FIG. 5 illustrates a substantially sector-shaped connection element 12 which is rotatably mounted about a bearing pin 11 and wherein the connections 13 and structed in the form of a slide, wherein the outlet openings 19 of the connection channels 18 are located in a linear row, and at the connections there are alternately connected powder infeed conduits Ae and flushing air delivery conduits Sp. The mode of operation in this case is the. same as the previously described embodiments, wherein only, however, the connection element 12 must be linearly displaced instead of rotated. The cover plate 10 at the pistol body member must be twice as long as the connection element 12, so that during its displacement all connections are covered. With this embodiment the hoses are not rotated and there is possible a so-called sandwich construction for a coating installation having a number of powder spray guns, wherein the guns are grouped together into an assembly or unit.

With the embodiment depicted in FIG. 7 the connection element 12 is arranged so as to be stationary and possesses connections 13 at which there can be alternately connected powder infeed conduits Ae and flushing air-delivery conduis Sp. The spray gun body member 9 is arranged in such a way that it resiliently presses against the stationary connection element 12 and thus brings about by means of blind plugs or stoppers 21 a good sealing of all of the connection channels 18. The gun body member 9 is detachable from the connection element 12 and can be rotated in its lifted-off position and the powder dispensing channel 14 extends arcuately from the outside towards the center from the region of the inlet opening 17 and such inlet opening during rotation of the gun body member 9 is alternately brought into connection or flow communication with the different connection channels 18. Owing to rotation of the gun body member 9 there is brought about a color-change operation, wherein during each changeover operation there occurs a cleaning of the spray gun with flushing air. In this case the hoses are not rotated. However a sandwich construction :is not here possible.

With the embodiment of FIGS. 8 and 9 a hollow, cylindrical stationary connection element 12 possesses connections 13 designed in the form of inclined connection studs, and at which connections 13 there can be alternately connected powder infeed conduits Ae and flushing air-delivery conduits Sp. The cylindrical spray gun body member 9 is rotatably mounted at the connection element 12. The gun body member 9 possesses an arcuate channel portion 22 extending from the periphery up to the center and is provided at its periphery at the region of the connection element 12 with two sealing rings 23. By rotating the gun body member 9 the powder dispensing channel 14 can alternately be placed into flow communication with one of the powder delivery conduits in order to be able to work with a desired color. During a color-change operation the channel inlet opening 17 always moves past an intermediately situated flushing air conduit and therefore is cleaned. By virtue of the sealing rings 23 there is formed an air cushion between the gun body member 9 and the connection element 12, preventing any rubbing or grinding of powder and thus binding of the gun body member 9. This arrangement requires very little space, the hoses are not rotated, and finally a sandwich construction is possible.

With the embodiment illustrated in FIGS. 10 and U the gun body member 9 is provided at the region of the inlet opening 17 of the powder dispensing channel 14 with a mouthpiece 24 and is mounted at a casing or lining 25. In this casing 25 there is mounted through the agency of a Cardan connection or joint 26 a connection element 12A in such a manner that it can pivot to all sides about its center. The connection element HA is provided with a central connection channel 18A at which there can be connected a stud-like connection 13 for a flushing air-delivery conduit. In the illustrated starting position of the connection element 12A the flushing air-delivery conduit is in flow communication via the connection channel 18A with the spray gunpowder dispensing channel 14. Six further connection channels 188 are formed at the connection element 12A about such central connection channel 18A, the respective center line of these connection channels 188, as apparent from the drawings, being located upon the surface of a truncated cone. Each of these connection channels 188 extends through a stud-like connection 13 at which there can be connected a powder delivery conduit for the delivery of a color powderconveying air-mixture. The connection element 12A is provided at the discharge side of the connection channels 18A, 188 with a segmented spherical-shaped sealing surface 27, the center of which is located at the point of rotation of the Cardan joint arrangement 26. This sealing surface 27 is bounded by an upstanding edge 28 which at the outside of the outer connection channels 188 extends in arcuate-shaped fashion and in a wedge-like manner between such connection channels, as best seen by referring to FlG. 11. Owing to the cooperative action of the edge 28 with the mouthpiece 24 the deflection or pivotal movement of the connection element 12A is limited in such a manner that in each pivoted position one of the outer connections 18B is in flow communication with the spray gun-powder dispensing channel 14. The deflection or pivoting of the connection element 12A occurs through the agency of pneumatic cylinders 36 which act upon a flange 29 of the connection element 12A and wherein a respective one of such pneumatic cylinders is associated with each outer connection channel 1188. Upon actuating one of the cylinders 30 the connection element 12A is pivoted in such a manner that the associated outer connection channel 188 is connected in flow communication with the powder dispensing channel 14. After switching-off the cylinder 30 connection element 12A returns back into its starting position under the action of any suitable and therefore not particularly illustrated return or restoring force producing means, such as a spring for instance, in which the flushing operation occurs and from which, upon actuating an appropriate cylinder, such can be again moved into a different deflected position.

Of course instead of using the pneumatic cylinders 30 there can be employed other actuating means, such as lifting magnets, for deflecting the connection element 12A. Moreover, instead of having a cylinder 30 which is axially directed and which cooperates with the flange 29 there could also be employed radially directed cylinders 30 for the deflection of the connection element 12A, as such has been illustrated in phantom lines in FIG. 10.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. ACCORD- INGLY,

What is claimed is:

l. A powder spray gun arrangement for spraying different color powders comprising a spray gun including a spray gun body member having a powder dispensing channel for spraying different color powders, a connection mechanism having a number of connections, infeed conduits for different powder-conveying airmixtures and flushing air connectable with said connection mechanism and through the agency of which there can be delivered through the spray gunpowder dispensing channel for spraying purposes a given selected powder-conveying air-mixture and for cleaning of the spray gun flushing air, said connection mechanism comprising a connection element carrying said connections, said connection element being provided with a respective substantially continuous straight connection channel for each connection, each said connection channel having an outlet opening and said powder dispensing channel having an inlet opening, means for mounting said connection element and said spray gun body member having said powder channel so as to be displaceable relative to one another such that said connection channels of the connection element can be selectively connected by means of their outlet openings with the inlet opening of the powder channel in a certain sequence, and with a predetermined distribution of the feed conduits for the powder-conveying air-mixture and the flushing air at the connections of the element the powder dispensing channel is flushed with flushing air during each color-changeover operation, said connection element and said gun body member possessing oppositely situated surfaces at which respectively open said connection channels and said powder channel, said outlet openings of all said connection channels being arranged in a row at the surface of said connection element with a center point located along a line, said connection element and said gun body member being able to be moved relative to one another along said line for adjusting said outlet openings with respect to said inlet opening of said powder channel, and wherein when any one of said outlet openings is adjusted with respect to said inlet opening so as to be in flow communication therewith said gun body member covers by means of its surface said outlet openings of all the remaining connection channels, said inlet opening of said powder dispensing channel being surrounded by a sealing ring by means of which that connection channel which is located in an operable position can be sealed at the region of its outlet opening, said connection element and said gun body member being arranged such that a gap is present between said connection element and said gun body member, leakage air entering from said connection channels into said gap and said gap being continuously flushed by such leakage air.

2. A powder spray gun arrangement for spraying different color powders comprising a spray gun including a spray gun body member having a powder dispensing channel for spraying different color powders, a connection mechanism having a number of connections, infeed conduits for different powder-conveying airmixtures and flushing air connectable with said connection mechanism and through the agency of which there can be delivered through the spray gunpowder dispensing channel for spraying purposes a given selected powder-conveying air-mixture and for cleaning of the spray gun flushing air, said connection mechanism comprising a connection element carrying said connections, said connection element being provided with a respective substantially continuous straight connection channel for each connection, each said connection channel having an outlet opening and said powder dispensing channel having an inlet opening, means for mounting said connection element and said spray gun body member having said powder channel so as to be displaceable relative to one another such that said connection channels of the connection element can be selectively connected by means of their outlet openings with the inlet opening of the powder channel in a certain sequence, and with a predetermined distribution of the infeed conduits for the powder-conveying air-mixture and the flushing air at the connections of the element the powder dispensing channel is flushed with flushing air during each color-changeover operation, one of said connection channels of said connection element defining a central connection channel which can be connected to a flushing air infeed conduit, the remaining connection channels being connectable with said powder infeed conduits and arranged about said central connection channel, Cardan-suspension means for suspending the connection element at the gun body member in such a manner that it can be selectively pivoted out of a starting position in, which said central connection channel is connected with said powder dispensing channel into predetermined positions wherein a given respective outer connection channel is connected with the powder channel.

3. The powder spray gun arrangement as defined in claim 2, wherein said gun body member possesses a casing, said Cardan-suspension :means embodying a Cardan joint arrangement for mounting the connection element at the casing of the gun body member.

4. The powder spray gun arrangement as defined in claim 2, wherein the outer connection channels are arranged at the connection element about the central connection channel in such a manner that each respective center line thereof is located at a surface of a truncated cone.

5. The powder spray gun arrangement as defined in claim 3, wherein said gun body member is provided with a mouthpiece, said connection element possessing at the outlet side of the connection channels a substantially segmented spherical-shaped sealing surface against which bears said mouthpiece of the gun body member, and wherein the center of said sealing surface is located at the point of rotation of the Cardan joint arrangement.

6. The powder spray gun arrangement as defined in claim 5, wherein said sealing surface is arranged about the outlet openings of the outer connection channels and is bounded by raised edge portions which in coop eration with the mouthpiece of the gun body member limit the pivotal movement of the connection element.

Claims

1. A powder spray gun arrangement for spraying different color powders comprising a spray gun including a spray gun body member having a powder dispensing channel for spraying different color powders, a connection mechanism having a number of connections, infeed conduits for different powder-conveying air-mixtures and flushing air connectable with said connection mechanism and through the agency of which there can be delivered through the spray gunpowder dispensing channel for spraying purposes a given selected powder-conveying air-mixture and for cleaning of the spray gun flushing air, said connection mechanism comprising a connection element carrying said connections, said connection element being provided with a respective substantially continuous straight connection channel for each connection, each said connection channel having an outlet opening and said powder dispensing channel having an inlet opening, means for mounting said connection element and said spray gun body member having said powder channel so as to be displaceable relative to one another such that said connection channels of the connection element can be selectively connected by means of their outlet openings with the inlet opening of the powder channel in a certain sequence, and with a predetermined distribution of the feed conduits for the powder-conveying air-mixture and the flushing air at the connections of the element the powder dispEnsing channel is flushed with flushing air during each color-changeover operation, said connection element and said gun body member possessing oppositely situated surfaces at which respectively open said connection channels and said powder channel, said outlet openings of all said connection channels being arranged in a row at the surface of said connection element with a center point located along a line, said connection element and said gun body member being able to be moved relative to one another along said line for adjusting said outlet openings with respect to said inlet opening of said powder channel, and wherein when any one of said outlet openings is adjusted with respect to said inlet opening so as to be in flow communication therewith said gun body member covers by means of its surface said outlet openings of all the remaining connection channels, said inlet opening of said powder dispensing channel being surrounded by a sealing ring by means of which that connection channel which is located in an operable position can be sealed at the region of its outlet opening, said connection element and said gun body member being arranged such that a gap is present between said connection element and said gun body member, leakage air entering from said connection channels into said gap and said gap being continuously flushed by such leakage air.

2. A powder spray gun arrangement for spraying different color powders comprising a spray gun including a spray gun body member having a powder dispensing channel for spraying different color powders, a connection mechanism having a number of connections, infeed conduits for different powder-conveying air-mixtures and flushing air connectable with said connection mechanism and through the agency of which there can be delivered through the spray gunpowder dispensing channel for spraying purposes a given selected powder-conveying air-mixture and for cleaning of the spray gun flushing air, said connection mechanism comprising a connection element carrying said connections, said connection element being provided with a respective substantially continuous straight connection channel for each connection, each said connection channel having an outlet opening and said powder dispensing channel having an inlet opening, means for mounting said connection element and said spray gun body member having said powder channel so as to be displaceable relative to one another such that said connection channels of the connection element can be selectively connected by means of their outlet openings with the inlet opening of the powder channel in a certain sequence, and with a predetermined distribution of the infeed conduits for the powder-conveying air-mixture and the flushing air at the connections of the element the powder dispensing channel is flushed with flushing air during each color-changeover operation, one of said connection channels of said connection element defining a central connection channel which can be connected to a flushing air infeed conduit, the remaining connection channels being connectable with said powder infeed conduits and arranged about said central connection channel, Cardan-suspension means for suspending the connection element at the gun body member in such a manner that it can be selectively pivoted out of a starting position in which said central connection channel is connected with said powder dispensing channel into predetermined positions wherein a given respective outer connection channel is connected with the powder channel.

3. The powder spray gun arrangement as defined in claim 2, wherein said gun body member possesses a casing, said Cardan-suspension means embodying a Cardan joint arrangement for mounting the connection element at the casing of the gun body member.

6. The powder spray gun arrangement as defined in claim 5, wherein said sealing surface is arranged about the outlet openings of the outer connection channels and is bounded by raised edge portions which in cooperation with the mouthpiece of the gun body member limit the pivotal movement of the connection element.