US2982480A

US2982480A - Metal spray gun

Info

Publication number: US2982480A
Application number: US840551A
Authority: US
Inventors: Harry J Gilliland; Donald W Jones
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1959-09-17
Filing date: 1959-09-17
Publication date: 1961-05-02
Anticipated expiration: 1978-05-02

Description

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H. J. GILLILAND ETI'AL METAL SPRAY GUN May 2, 1961 Filed Sept. 17. 1959 "iii: V

May 2, 1961 H. J. GILLILAND ET AL 2,932,480

METAL SPRAY GUN Filed Sept. 17, 1959 2 Sheets-Sheet 2 United States Patent METAL SPRAY GUN Harry J. Gilliland, Birmingham, and Donald W. Jones, Mount Clemens, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept. 17, 1959, Ser. No. 840,551

2 Claims. (Cl. 239-84) This invention relates to improvements in metal spray ns. Metal spray guns of the wire feeding, gas blast type are devices in which a metal rod or wire is continuously fed into a combustion zone in which the metal is melted and thereafter expelled from the gun in finely divided form by means of a blast of air or other suitable gas. A mixture of combustible and combustion supporting gases such as acetylene and air or oxygen, respectively, are fed into the melting zone through suitable jets or passages surrounding the feeding path of the metal rod or wire. When the combustible mixture is ignited, it melts the wire or rod fed into the melting chamber. A stream of or other gas is forcibly directed against the molten metal at the tip of the metal rod or wire in a manner such that it impinges sharply against the tip to thereby blast the molten metal into fine particles. Metal powder spray guns are similar in construction and operation and differ essentially in that a metal is delivered to the melting zone in the form of a gas propelled powder.

The nozzle construction of metal spray guns of this type usually includes a burner tip which is provided with a wire feeding orifice centrally thereof and a plurality of burner jets substantially surrounding the longitudinal axis of the wire feeding orifice and passing therethrough. It further includes an air cap enveloping the burner tip forming a combustion chamber between its inner walls and the burner tip and an air blast passage. The materials to be sprayed may be fed into the melting zone either in the form of a rod or wire or in the form of a gas propelled powder as above indicated.

Heretofore in so far as it is known, metal spray guns of this type were capable of directing the sprayed material in a generally single fixed direction so that when used for spray coating of the inner surfaces of a tubular member such as, for example, an engine cylinder, it was necessary to rotate the spray gun. Since the spray gun requires a number of gas supplying conduits and a metal feeding means, the rotation of the spray gun involved diflicult manipulative problems.

It is the basic object of the present invention to provide a metal spray gun of the type described above which includes an air cap tip constructed so as to direct the molten metal at an angle to the metal feeding orifice which is rotatable with respect to the molten metal feeding orifice and the burner jets whereby in operation of the spray gun the air cap tip is continuously rotated to direct the blast of molten metal continuously in a 360 are about the spray gun axis while holding the spray' gun in a fixed position. It is a further object of the invention to provide a spray gun which includes means for rotating the air caps of a plurality of spray guns simultaneously whereby the interior surfaces of a plurality of cylindrical surfaces such as the cylinders of an ,engine block may be simultaneously spray coated.

Further objects and advantages of the invention will be apparent from the following description, reference Patented May 2, 1961 being bad to the accompanying drawings wherein a preferred embodiment of the invention is shown.

In the drawings: Figure 1 is a top view of spray gun apparatus including three spray guns arranged abreast one another and operated by common drive shafts to simultaneously spray I coat the walls of three cylinders of an engine block in accordance with the present invention;

Figure 2 is a cross-sectional view with parts broken away taken along line 2-2 of Figure 5;

Figure 3 is a cross-sectional view taken along line 3-3 of Figure 5;

Figure 4 is a cross-sectional view with parts broken away taken along line 44 of Figure 6;

Figure 5 is a cross-sectional view taken along line 55 of Figure l;

Figure 6 is an enlarged fragmentary cross-sectional view of the nozzle portion of the spray gun shown in Figure 5 Figure 7 is an enlarged fragmentary cross-sectional view of the gas feed portion of the spray gun shown in Figure 5.

In general as may be seen most clearly in Figure 5, the preferred embodiment of the spray gun of the present invention involves a stationary burner tip 10, conduit means 12 for feeding a wire to the burner tip, conduit means 14 for feeding oxygen or air to the burner tip, conduit means 16 for feeding acetylene to the burner tip, and an air tip 18 disposed forwardly of the burner tip and enveloping the burner tip to form the combustion chamber 20 and adapted to direct the molten metal spray at an angle with respect to the longitudinal axis of the spray gun. A basic feature of the present invention is the provision of a rotatable sleeve 22 which supports the air tip 18, envelops the burner tip 10 and forms an air passage to the combustion chamber 20 between it and the burner tip'10. The sleeve 22 is rotatably mounted within the housing 24 by means of ball bearings 26 and 28 and has keyed thereto a gear 30 which is power driven by means of the pinion 32. As will be seen moreclearly hereinafter, the pinion 32 is preferably connected to the pinions of a plurality of spray guns whereby these pinions may be driven simultaneously through a common drive shaft.

The sleeve 22 preferably consists of a hollow shaft portion 34 carried by the bearings 26 and 28 press-fitted to the housing and rotatably sealed with respect to the housing by a resilient annular seal 36. The shaft portion 34 is retained within the housing by the nut 38 threaded to the sleeve and engaging the bearing 26 through a washer. An extension 40, threaded to the shaft portion 34, carries the air cap 18 pressfitted therein.

Passing through the shaft portion 34 of the sleeve 22 are the wire feeding conduit 12, the acetylene conduit 16 and the oxygen conduit 14 which are attached on opposite ends to cylindrical adapters 42 and 44. As shown more clearly in Figure 7, the adapter 44 is held in the housing by means of the externally threaded nut 46 engaging the flange portion 48 of the adapter. The adapter is provided with an acetylene passage 50 in communication with the acetylene conduit 16,.which leads to the circumferentially disposed groove 52 sealed with. respect to the housing by the elastomeric seals 54 and 60. Acetygroove 64, sealed with respect to the housing by the elastomeric seals 60 and 66, to which oxygen is supplied through the fitting 68.

the wire feeding conduit 12. As is shown in Figure 5,

'the apparatus includes a wire feeding mechanism includ- The adapter also includes a V centrally disposed passage 70 in communication with ing a drive roller 72 and a pressure roller 74. The pressure roller 74 is supported on an adjustable housing portion 76 which in turn is supported for vertical move ment by the stud 78 and held in a horizontally aligned position by a spring 80. The wire supply carried by the reel 82 as shown in Figure 1 is fed through the spray gun by means of the rollers 72 and 74 in an obvious manner. The degree of pressure between the rollers is controlled by a vertical adjustment of the pressure roller carrying member 76.

The adapter 42 which is spaced from the sleeve 22 to form a passage therebetween includes an acetylene passage 84 in communication with the acetylene conduit 16 leading to an annular groove 86 in the endface of the adapter 42. Similarly, the adapter includes a passage 88 in communication with the oxygen conduit 14 leading to the annular groove 86. Adjacent the groove 86 is disposed an annular metering plate 90 which includes an annular groove 92 in the face thereof. The plate 90 is fixed to a bushing 94 which is held in a counterbore of the wire feeding passage 96 of the adapter. As shown in Figure 4, a plurality of openings 98 are provided through the metering plate 90 which communicate between the grooves 86 and 92.

The burner tip includes a centrally disposed wire feeding passage 100 and a plurality of combustible gas feeding passages '102 disposed thereabout which converge about the passage 100 at the burner tip. The burner tip is disposed against the metering plate 90 so that the combustible gas feeding passages 102 are in alignment with the groove 92 of the metering plate. As shown in Figure 4, the openings 98 through the metering plate are out of alignment with the combustible gas feeding passages 102 of the burner tip to insure proper metering and mixing of the gases. The metering plate 90 and the burner tip 10 are secured in position by a retainer 104 threaded to the adapter 42. Preferably the metering plate 90 is provided with a dowel (not shown) to insure that on assembly of the parts, the openings 98 and passages 102 are not aligned.

The air tip 18 is provided with conical interior walls spaced from the burner tip to provide the conical combustion chamber and an air passage 106 between the burner tip and the air cap. A portion of the air cap is cut away as indicated by the numeral 107 and the inner surfaces 108 of the air cap 18 opposite the cut away portion 107 are curved inwardly so as to direct the sprayed molten metal at an angle of approximately 45 with respect to the longitudinal axis of the spray gun. The air cap 18 further includes an air passage 110 through which air is passed to cool the air cap and an annular flange 112 which extends between a shoulder 1-14 or" the burner tip and the retainer 104. The retainer 104 also includes a plurality of openings 116 therethrough in advance of the flange 112 of the air cap.

It will thus be seen that rotatable sleeve 22 supports the air cap 18 and forms air passages in combination with other internal elements of the spray gun mechanism. This air passage consists of the air pressure fitting 1 18 which leads to an annular space 47 between the nut 46 and shaft portion 34 of the rotatable sleeve 22. The annular space 47 leads to the space 120 between the sleeve 22 and the conduits 12, 14 and 16 and adapter 42 which in turn leads to an enlarged annular space 122 in the region of the burner tip 10. An air conduit 124 leading to the wire feeding conduit 96 is provided to equalize the pressure in the wire feeding tube.

In operation of the spray gun, the wire is fed through the burner tip 10 by means of the rollers 72 and 74. Acetylene, oxygen and air under pressure are admitted to the spray gun through the fittings 58, 68 and 118, respectively. The oxygen and acetylene are mixed in the groove 86 and metered as they pass through the metering plate 90 and are passed through the burner tip 10 so as to converge at a predetermined .point forward of the burner tip. The compressed air passes through the annular space 47, the space and into the annular space 122. From thence a portion of the air stream, guided by the air cap flange 112, is directed through the air cap passage 110. A major portion of the air passes inwardly of the flange 112 through the openings 116 of the retainer 104 through the annular passage between the flange 112 and the burner tip shoulder 114, and through the conical passage 106 into the combustion chamber 20 wherein it is operative to atomize and propel the metal melted by the burning gases out of the spray gun. The curved portion 108 causes the molten metal spray to be propelled at an angle of approximately 45 to the longitudinal axis of the spray gun. Meanwhile the sleeve 22 has been caused to rotate by application of power to the pinion 32 whereby the gun is caused to spray through a 360 are at a rate depending on the speed at which the sleeve 22 is rotated.

Although the air cap 18 has been described in terms of a structure which causes the molten metal to be directed at an angle of approximately 45 with respect to the longitudinal axis of the spray gun. It is obvious that for the purposes of the present invention, it is essential only that the spray be directed at a sufiicient acute angle from the longitudinal axis of the spray gun so that on rotating the air cap, it will satisfactorily spray coat cylindrical walls disposed parallel to the longitudinal axis of the gun.

As shown in Figure l, a plurality of spray guns are mounted abreast one another for the purpose of spray coating a plurality of cylinder surfaces of a cylinder block 1'25. The pinions 32 of each spray gun are interconnected and the wire drive gears 72 of each spray gun are similarly interconnected. Preferably the spray guns are slidably mounted on rods 126 and reciprocably moved by hydraulic pistons 128 whereby they may be moved simultaneously within cylinder bores at a predetermined rate while in operation to spray coat the cylinder bore surfaces in an obvious manner.

While the embodiment of the present invention as disclosed herein constitutes a preferred form, it is to be understood that other forms may be adopted without departing from the spirit of the invention.

We claim:

1. A spray gun assembly for use in simultaneously metal spraying the bores of a plurality of cylinders posi tioned in a plane, said assembly comprising a carrier means adapted for reciprocable movement in said plane, a plurality of spray guns mounted abreast of one another upon said carrier means whereby a reciprocating movement of said carrier means is operative to move said spray guns reciprocably within said bores, each of said spray guns comprising a burner tip provided with a metal feeding orifice and a multiple number of burner jets substantially surrounding the axis of said orifice, a housing, metal feeding conduit means attached to said housing in communication with said burner tip orifice, combustible gas conduit means secured to said housing and in communication with said burner jets, an air cap surronndmg said burner tip forming a gas blast passage therebetween and adapted to direct a blast of gas between the molten metal formed at said burner tip, said air cap being adapted to direct the molten metal spray at an acute angle w1th respect to the longitudinal axis of said spray gun, a sleeve surrounding said conduits supporting said air cap and rotatably mounted on said housing, said sleeve being spaced from said conduits and rotatably sealed with respect to said housing to provide a gas passage therebetween in communication with said gas blast passage, a ring gear fixed to said sleeve, a pinion operatively mounted within said housing connected to said ring gear, means for supplying a compressed gas through said housing to said gas passage, rotatable drive means for feeding a Wire through said metal feeding .conduit, means interconnecting the said pinions of each wire feeding means are adapted to be simultaneously driven by a single drive means.

2. A spray gun assembly for use in simultaneously metal spraying the bores of a plurality of cylinders positioned in a plane, said assembly comprising a carrier means adapted for reciprocable movement in said plane, a plurality of spray guns mounted abreast of one another upon said carrier means whereby a reciprocating movement of said carrier means is operative to move said spray guns reciprocably within said bores, each of said spray guns comprising a burner tip provided with a metal feeding orifice and a multiple number of burner jets substantially surrounding the axis of said orifice, a housing, metal feeding conduit means attached to said housing in communication with said burner tip orifice, combustible gas conduit means secured to said housing and in comrespect to the longitudinal axis of said spray gun, a sleeve surrounding said conduits supporting said air cap and rotatably mounted on said housing, said sleeve being spaced from said conduits and rotatably sealed with respect to said housing to provide a gas passage therebetween in communication with said gas blast passage, a ring gear fixed to said sleeve, a pinion rotatably mounted within said housing operatively connected to said ring gear, means for supplying a compressed gas through said housing to said gas passage, means for feeding a metal through said metal feeding conduit, means interconnecting the said pinions of each of said spray guns in an aligned relation whereby each of said pinions are adapted to be driven simultaneously by a single drive means and means for simultaneously operating each of said metal feeding means.

References Cited in the file of this patent UNITED STATES PATENTS Sweden Nov. 20, 1923