GB2075925A

GB2075925A - Automobile panel assembly

Info

Publication number: GB2075925A
Application number: GB8107516A
Authority: GB
Original assignee: Nissan Motor Co Ltd; Nippon Zeon Co Ltd
Current assignee: Zeon Corp; Nissan Motor Co Ltd
Priority date: 1980-03-12
Filing date: 1981-03-10
Publication date: 1981-11-25
Also published as: GB2075925B; JPS6149150B2; DE3109520A1; JPS56128279A; FR2478008A1

Abstract

A panel assembling method is disclosed-which includes atomizing separately first and second portions of a two-component, solventless, thermosetting rust preventive, mixing the first and second portions to form the rust preventive, and spraying the rust preventive on the connection area of a first panel which is to be fixed to the connection area of a second panel. The connection area of the first and second panels are brought together to form a vehicle component. After the vehicle component is installed to a vehicle body, the vehicle body is heated to set the rust preventive. Apparatus for spraying the two component rust preventive is also disclosed. The apparatus has two atomizing chambers which are opened to a mixing chamber for a predetermined period of time after the spray components are fully pressurized in their respective atomizing chambers.

Description

SPECIFICATION Panel assembling method and apparatus 1. Fieldofthe invention This invention relates to a method of assembling automobile panels and, more particularly, to such a panel assembling method employing a two-component, solventless, rust preventive.

2. Description ofthe prior art In cold regions where salt sprinking is required in order to avoid road freezing, corrosion resistance for automobile panel components such as hoods, doors, and the like has become of increasing concern. Such automobile panel components are susceptible to corrosion in the presence of water and salt, particularly at their peripheral portions at which inner and outer panels are folded over together and from which electrodeposited paint is apt to come off.

It has been proposed in an effort to prevent occurrence of corrosion on automobile panel components by coating a rust preventive on and about the peripheral connection area of the panels before folding over them together. However, conventional methods have been found insufficient in some respects.

The present invention provides an improved automobile panel assembling method employing a two-c-omponent rust preventive which is formed in a short time by mixing the main ingredient and hardner.

Summary ofthe invention The present invention provides a method of assembling automobile panels, which comprises atomizing separately first and second portions to form a two-component, solventless, thermosetting rust preventive i.e. main ingredient and hardner; mixing the first and second portions; and forming the rust preventive.

Immediately after the formation of the rust preventive, it is sprayed on the connection area of a first panel which is to be fixed to the connection area of a second panel. The connection areas of the first and second panels are brought together to form a vehicle component. The vehicle component is installed to a vehicle body and then the vehicle body is heated to set the rust preventive. Since the present invention employs a two-component, solventless, thermosetting rust preventive, it assurs operator's health and security, and facilitates rust-preventive handling in production lines.The rust preventive is sprayed on the panel. This permits rapid rust-preventive coating in an even thickness.

The first and second portions of the rust preventive may be atomized by applying pressure to the first portion enclosed in a first chamber and also to the second portion enclosed in a second chamber, and then opening the first and second chambers.

The present invention also provides an apparatus for spraying a two-component, solventless, rust preventive comprised of main ingredient and hardner, which comprises: a mixing chamber communicated through a nozzle to atmosphere; first and second atomizing chambers opening to the mixing chamber; valve means for selectively connecting and disconnecting the first and second atomizing chambers from the mixing chamber, the valve means normally disconnecting the first and second atomizing chambers from the mixing chamber; a main ingredient source for charging the main ingredient to the first atomizing chamber; a hardner source for charging the hardnerto the second atomizing chamber; metering means for metering the main ingredient and the hardner to -be supplied therethrough to the first and second atomizing chambers to maintain a predetermined ratio of the main ingredient and the hardner; pressurizing means for applying pressure to the main ingredient and the hardner charged in the first and second atomizing chambers when actuated; and control means for actuating the pressurizing means after charging of the main ingredient and the hardner to the first and second atomizing chambers is completed, and causing the valve means to connect the first and second atomizing chambers to the mixing chamber for a predetermined period of time after the main ingredient and the hardner are fully pressurized.

In another form, the apparatus comprises a spray gun including a mixing chamber communicated through a nozzle to atmosphere, first and second atomizi-ng-chambers opening to the mixing chamber, valve means for selectively connecting and disconnecting the first and second atomizing chambers from the mixing chamber, the valve means normally disconnecting the first and second atomizing chambers from the mixing chamber; a main ingredient source for supplying the main ingredient to the first atomizing chamber; a hardner source for supplying the hardner to the second atomizing chamber; a first metering chamber interposed between the main ingredient source and the first.atomizing chamber for metering the main ingredient passing therethrough to a predetermined amount, a second metering chamber interposed between the hardner source and the second atomizing chamber for metering the hardner passing therethrough to a predetermined value; a first normally closed valve interposed between the main ingredient source and the first metering chamber; à second normally closed valve interposed between the hardner source and the second metering chamber; pressurizing means for applying pressure to the main ingredient charged in the first metering chamber and also the hardner charged in the second metering chamber when actuated; and control means for opening the first and second valves to permit the supply of the main ingredient and the hardner to the first and second atomizing chamber for a predetermined period of time, actuating the pressurizing means for a predetermined period of time after the opening of the first and second valves, and causing the valve means to connect the first and second atomizing chambers to the mixing chamber for a predetermined period of time after the main ingredient and the hardner are fully pressurized.

Brief description ofthe drawings The present invention will be described in greater detail by reference to the following description taken in connection with the accompanying drawings, in which: Figure 1 is a diagrammatic illustration of a production line through which an outer and an inner panel are assembled into a vehicle door; Figure2 is a perspective view showing an automatic spraying apparatus through which a two-component, solventless, thermosetting rust preventive is sprayed on a connection area of an outer panel; Figure 3 is an enlarged sectional view showing a spray gun used in the apparatus of Figure 2-; Figure 4 is a schematic diagram showing a supply unit through which a main ingredient and a hardner are supplied to the spray gun of Figure 3; and Figure 5 (including figures 5a to 5g) is a timing chart used in explaining the operation of various parts in the supply unit and the spray gun of Figure 4.

Description of the preferred embodiments Referring now to Figure 1, there is illustrated in diagrammatic form part of a panel assembling line which includes a number of processing stations on which an inner panel and an outer panel are assembled to form a vehicle door. While the present invention will be described in connection with formation of a vehicle door, it is understood that it could readily be applied to form other vehicle components such as vehicle hoods or the like.

An outer panel is put into the line automatically or by an operator from an outer panel input station 1, and is moved to a dedoner coating station 2 where dedoner is coated on a desired area of the outer panel. The outer panel passes a rust-preventive coating station 3 which includes an automatic rust-preventive spraying apparatus 10 to be described later for spraying a two-component, solventless, thermosetting rust-preventive on the area of the outer panel to be folded over.

Further, an inner panel to which a sash has been attached temporarily, is put into the line automatically or by an operator from an inner panel input station 5, and is moved to welding stations 6 and 7 where brackets for the door lock and hinge are welded to it. Then, the inner and outer panels are mated with each other in a marriage station 8 and then the edges of the mated panels are folded over together in a folding station 9.

Subsequently, the folded-together panels are discharged out of the line such as by a conveyer.

Referring to Figure 2, the automatic rust-preventive spraying apparatus 10 is shown as including three sprayers 20 supported by respective support frames 11 arranged to define three sides of a rectangular frame.

The sprayers 20 are substantially similar in structure. Each of the sprayers 20 comprises a spray gun 30 carried on a slider 21. The slider 21 is slidably supported on a guide rod 22 which extends over the length of the corresponding support frame 11. A piston-cylinder unit 23 is secured on the support frame 11 for moving the slider 21 along the guide rod 22 through a chain 24 guided by pulleys 25 and 26. The spray gun 30 is connected through a main-ingredient hose 27 and also through a hardner hose 28 to a rust-preventive supply unit 40 which will be described later in more detail. The spray gun 30 and the rust-preventive supply unit 40 are also connected through a detergent hose 29.

When the vehicle-door outer panel 100 is carried on shuttle bars 12 to the automatic rust-preventive spraying apparatus 10, a lift cylinder 13 is actuated to lift an underframe 14 having locator members 15 secured thereto, so as to set the vehicle-door outer panel 100 in a suitable position. Thereafter, the rust preventive is sprayed from the spray guns 30 on the outer panel 100, while the piston-cylinder units 23 move the respective sliders 21 to permit the spray guns 30 to spray the rust preventive over the connection area of the outer panel 100 to be folded over to bit the associated inner panel. Although the spray guns 30 move only in a plane in the illustrated embodiment, this is satisfactory since the outer panel of a vehicle component such as a vehicle hood, door or the like is not greatly curved.

The two-component, solventless, thermosetting rust preventive used in the present invention is a mixture of (A) a first portion (main ingredient) essentially including liquid epoxy resin and liquid polycarboxylic acid anhydride and amenable to spray application techniques, and (B) a second portion (hardner) essentially including liquid primary or secondary amino compound and hardening catalyzer and amenable to spray application techniques. The first and/or second portions essentially include nonreactive epoxy resin diluent of 300 to 4000 molecular weight and conductive powder. The viscosity of the first and second portions, measured at 5000, 10 rotations with a B-type viscometer, should be more than 20 times their viscosity measured at 50"C, 50 rotations.

The following examples are provided to illustrate the two-component, solventless, thermosetting rust preventives employed in the present invention, wherein the parts are by weight.

EXAMPLE E First portion Epoxy resin 100 Methyl tetrahydrophthalic an hydride ' 60 Diluent 60 Carbon black 2 Talc 50 Silicone oil 1 Second portion Polyamide amine 40 Octanoic acid tin 3 Diluent 150 Carbon black 4 Graphite 5 Silicone oil 1 Viscosity (poise/250C, 10 rotations) First portion 212 Second portion 350 Thixotropy index First portion 3.1 Second portion 2.3 The number of acide anhydride radical 0.65 per one epoxy radical The number of amino radical active 1.18 hydrogen per one epoxy radical Storage stability Is there less than 30% viscosity change at 60"C during a week storage? First portion 0 Second portion 0 Shower resistance Good Hardened film thickness (Il) 155 Flexibility (10mum+) 0 Adhesion (grid) O Impact strength (1/2" x 5009 x 20cm) 0 Corrosion resistance 0 (with salt sprayed for 1500 hours) EXAMPLE 2 First portion Epoxy resin 100 Methyl tetrahydrophthalic anhydride 70 Diluent 50 Carbon black 2 Talc 50 Silicone oil 1 Second portion Polyamide amine 60 Octanoic acid tin 3 Diluent 130 Carbon black 4 Graphite 5 Silicone oil 1 Viscosity (poise/25"C, 10 rotations) First portion 184 Second portion 373 Thixotropy index First portion 3.0 Second portion 2.4 The number of acide anhydride radical 0.76 per one epoxy radical The number of amino radical active 1.73 hydrogen per one epoxy radical Storage stability Is there less than 30% viscosity change at 60"C during a week storage? First portion 0 Second portion 0 Shower resistance Good Hardened film thickness (z) 140 Flexibility (10mum) O Adhesion (grid) O Impact strength (1/2" x 500g x 20cm) 0 Corrosion resistance 0 (with salt sprayed for 1500 hours) EXAMPLE 3 First portion Epoxy resin 100 Methyl tetrahydrophthalic anhydride 60 Diluent 100 Carbon black 3 Talc 60 Silicone oil 1 Second portion Polyamide amine 60 Dimethyl benzylamine Diluent 190 Carbon black 3 Talc 70 Silicone oil 1 Viscosity (poise/25"C, 10 rotations) First portion 312 Second portion 140 Thixotropy index First portion 2.6 Second portion 2.2 The number of acide anhydride radical 0.65 per one epoxy radical The number of amino radical active 1.73 hydrogen per one epoxy radical Storage stability Is there less than 30% viscosity change at 60"C during a week storage? First portion 0 Second portion 0 Shower resistance Good Hardened film thickness (F) 175 Flexibility (10mum) 0 Adhesion (grid) O Impact strength (1/2" x 500g x 20cm) 0 Corrosion resistance 0 (with salt sprayed for 1000 hours) EXAMPLE 4 First portion Epoxy resin 100 Methyl tetrahydrophthalic anhydride 60 Diluent 60 Carbon black 5 Talc 40 Silicone oil 1 Second portion Polyamide amine 60 Dimethyl benzylamine 1 Diluent 150 Carbon black 5 Talc 50 Silicone oil 1 Viscosity (poise/25 C, 10 rotations) First portion 340 Second portion 185 Thixotropy index First portion 2.9 Second portion 2.5 The number of acide anhydride radical 0.65 per one epoxy radical The number of amino radical active 1.73 hydrogen per one epoxy radical Storage stability Is there less than 30% viscosity change at 60"C during a week storage? First portion 0 Second portion O Shower resistance Good Hardened film thickness (p) 190 Flexibility (1 Omm) O Adhesion (grid) O Impact strength (1/2" x 5009 x 20cm) 0 Corrosion resistance 0 (with salt sprayed for 1000 hours) where circle, 0, indicates good or fairly good.

Referring to Figures 3 and 4, the spray gun 30 hasa cylinder 301 within which a piston 302 is adapted to reciprocate to define upper and lower chambers 303 and 304. The upper and lower chambers are connected through respective lines 305 and 306 to a first solenoid valve 307 and hence to a pressurasource 308. When energized, the first solenoid valve 307 shifts to a position as designated by 307a to connect the cylinder upper chamber 303 to the atmosphere and the cylinder lower chamber 304 to the pressure source 308, causing upward movement of the piston 302 to the upper position as shown in Figure 3.When deenergized, the first solenoid valve 307 shifts to another position as designated by 307b to connect the cylinder upper chamber 303 to the pressure source 308 and the cylinder lower chamber 304 to the atmosphere, causing downward movement of the-piston 302 to the lower position as shown in Figure 4.

The cylinder 301 is connected to an elongated cylinder 311 within which a plunger 312 is placed for reciprocating movemerit. The plunger 312 is secured at its upper end to the piston 302 for movement therewith and terminates at its lower end in a round tip portion 313. The elongated cylinder 311 has therein a mixing chamber 314 defined by the cylinder inner wall and the plunger tip portion 313. The mixing chamber has at its lower end a tapered portion 315 conforming to the round tip portion 313 of the plunger 312 and apassage 316 connecting the tapered portion 313 to the atmosphere. The elongated cylinder 311 is connected at its lower end with a nozzle tip 317 which is attached thereto by a cap 318. The passage 316is connected through a detergentport 319to the detergent hose 29.

Connected to the mixing chamber 314 are first and second atomizing chambers 321 and 322 having therein thermo-sensitive switches 323 and 324, respectively. The first and second atomizing chambers 321 and 322 are opened into the mixing chamber 314 in the direction perpendicular to the axis of the plunger 312 and facing each other.

Referring to Figure 4, the rust-preventive supply unit 40 comprises a metering gun generally designated as at 400. The metering gun 400 includes a cylinder 401 within which a piston 402 is adapted to reciprocate to defihe upper and lower chambers 403 and 404. The upper and lower chambers are connected-through respective lines 405 and 406 to a second solenoid valve-407 and hence to a pressure source 4Q8.When energized,the second solenoid valve 407 shifts to a position as designated by 407a to connect the cylinder upper chamber 403 to the atmosphere and the cylinder lower chamber 404 to the pressure source 408, causing upward movement of the piston 402 to the upper position. Wherltdeenergized, the first solenoid valve 407 shifts to another position as designated by 407b to connect the cylinder upper chamber 403 to the pressure source 408 and the cylinder lower chamber 404 to the atmosphere, causing downward movement of the piston 402 to the lower position as shown in Figure4.

Secured centrally on the lower surface of the piston 402 is forked plunger 411 1 which is bifurcated at its free end into two finger portions, one being inserted into a first metering chamber 414 and the other being inserted into a second metering chamber 415 so as to vary the volumes of the first and second metering chambers 414 and 415 as the piston 402 moves. A limit switch 416 is provided which is turned on when the forked plunger 411 moves to its lowermost position. When the position of the limit switch 416 changes from its OFF position on its ON position, the first solenoid valve 307 is deenergized.

A first motor 421 is provided for driving a first pump 422 which draws a main ingredient from a main ingredient tank 423 and discharges it through a line 424 to a first heat exchanger 425. The heat exchanger 425 is connected through a line 426 to a third solenoid valve 427 and hence through a line 428 to the first metering chamber 414. The third solenoid valve427 shifts to a position as designated by 427a to connect the lines 426 and 428 when energized, and it shifts to another position as designated by 427b to disconnect the line 426 from the line 428 when deenergized.

A second motor 431 is provided for driving a second pump 432 which draws a hardner from a hardnertank 433 and discharges it through a line 434 to a second heat exchanger 435. The heat exchanger 435 is connected through a line 436 to a fourth solenoid valve 437 and hence through a line 438 to the second metering chamber 415. The fourth solenoid valve 437 shifts to a.position as designated by 437a to connect the lines 436 and 438 when energized, and it shifts to another position as designated by 437b--to disconnect- the line 436 from the line 438 when~deenergized.

The first metering chamber 414 is connected through the line 27 to the first atomizing chamber 321* The second metering chamber 415 is connected-through the line 28 to the second atomizing chamber 322. The metering gun 400 determines the main-inredient-to-hardner ratio of a rust-preventive mixture sprayed through the spray gun 30 by varying the volumes of the first and second metering chambers 414 and 415.

Although a single cylinder-piston unit is used in the illustrated embodiment for controlling the volumes of the first and second metering chambers 414 and 415, it is to be noted that two separate cylinder-piston units may be used for the first and-second metering charnbers,-respectively.

The main ingredient and the hardner discharged from the first and second. atomizing chambers 321 and 322 come into collision with each other to form a proper rust-preventive mixture within the mixing chamber 314. In order to wash theresidual rust-preventive-mixture, either one of the main ingredient andthahardner is supplied into the mixing chamber 314;:in the illustrated~ernbodiment, the detergent port 319 is connected to the second pump 432 through the detergent hose 29 which has therein a fifth solenoid valve 441 and a check valve 442 adapted to avoid-counter flow of the rust-preventive mixture to the line 29. The fifth solenoid valve 441 shifts to a position as designated by 441a to connect the detergent port 319 to the second pump 432 when energized, and it shifts to another position as designated by 441 b to disconnect the detergent port 319 from the second pump 432 when- deenergized.

Heating means such as heating tape 450 is applied around the-lines 426,428,436,438, the hoses 27,28, the atomizing chambers 321,322, and the mixing chamber 314for maintaining them in a predetermined temperature range, for example, from 30"C to 50"C by the aid of the thermosensitive switches 323 and 324.

This is effective to maintain the main ingredient and the hardner at low viscosity, permitting their complete atomization in the respective atomizing chambers 321 and 322.

The first and second atomizing chambers 321 and 322 are located as near the mixing chamber 314 as possible. The mixing chamber 314 should be designed such that the distance between the point at which the main ingredient and the hardner are mixed and the point at which the mixed rust-preventive is discharged is within a suitable range. If it is shorter than the range, the main ingredient and the hardner can not be mixed fully. If it is longer than the range, the mixed rust-preventive can partially be set although the main ingredient and the hardner can be mixed fully. Preferably, the length of the passage 316 between the tapered portion 315 and the nozzle tip 317 is as short as possible.

Figure 5 is a timing chart showing the operation of various parts in the two-component, rust-preventive spraying apparatus 10 during its one rust-preventive spraying cycle.

It is first assumed that the previous rust-preventive spraying cycle has been finished and the rust-preventive spraying apparatus is in a state as shown in Figure 4. In this state, the third and fourth solenoid valves 427 and 437 are OFF, as shown in Figure 5a, to shut off the supply of the main ingredient and the hardner to the first and second metering chambers 414 and 415, respectively. The second solenoid valve 407 isOFF, as shown in Figure 5b, to place the forked plunger 411 in its lowermost position. Thus, the limit switch 416 is ON, as shown in Figure 5d. The first solenoid valve 307 is OFF, as shown in Figure 5c, to place the plunger 312 in its lowermost position, thereby disconnecting the first and second atomizing chambers 321 and 322 from the mixing chamber 314.

When a command is produced to start the rust-preventive spraying operation, the third and fourth solenoid valves 427 and 437 are turned ON, as shown in Figure 5a, to allow the supply of the main ingredient and the hardnerto the first and second metering chambers 414 and 415, respectively. Simultaneously, the second solenoid valve 407 is turned ON, as shown in Figure 5b, to move the foked plunger 411 upward. As a result, the limit switch 416 is turned OFF, as shown in Figure 5d.

After a necessary amount of the main ingredient and the hardner is supplied to the first and second metering chambers 414 and 415, the third and fourth solenoid valves 427 and 437 are turned OFF, as shown in Figure 5a, to disconnect the line 428 from the line 426 and the line 438 from the line 436. A predetermined time after the deenergization of the third and fourth solenoid valves 427 and 437, the second solenoid valve 407 is turned OFF, as shown in Figure 5b, to move the forked plunger 411 downward, thereby pressurizing the main ingredient charged in the first metering chamber 414 to force into the line 428, the hose 27, and the first atomizing chamber 321, and also the hardner charged in the second metering chamber 415 to force into the line 438, the hose 28, and the second atomizing chamber 322.

During the time required for the pressures of the main ingredient and the hardner to become stationary after the deenergization of the second solenoid valve 407, the first solenoid valve 307 is turned ON, as shown in Figure 5c, to move the plunger 312 upward so as to connect the first and second atomizing chambers 321 and 322 to the mixing chamber 314. As a result, main-ingredient turbulent flow occurs to fully atomize the main ingredient in the first atomizing chamber 321, and hardner turbulent flow occurs to fully atomize the hardner in the second atomizing chamber 322.The main-ingredient turbulent flow enters the mixing chamber 314, as shown in Figure 5f, and the hardner turbulent flow enters the mixing chamber 314, as shown in Figure 5g, so that they can fully admix therein to form a rust-preventive which is sprayed through the nozzle tip 317.

When the forked plunger 411 reaches its iowermost position, the limit switch 416 is turned ON, as shown in Figure 5d, and the first solenoid valve 307 is deenergized, as shown in Figure 5c, to move the plunger 312 downward to its lowermost position where the round tip portion 313 seats on the tapered portion 315, thereby disconnecting the first and second atomizing chambers 321 and 322 from the mixing chamber 314.

As a result, the flows of the main ingredient and the hardner to the mixing chamber 314 are shut off, as shown in Figures 5f and 5g.

When the plunger 312 disconnects the first and second atomizing chambers 321 and 322 from the mixing chamber 314, the fifth solenoid valve 441 is turned ON, as shown in Figure 5e, to allow the supply of the hardner through the detergent port 319 into the passage 316 so as to wash the remaining rust-preventive.

Although the hardner remains in the passage 316 and the nozzle tip 317, there is no trouble for the following rust-preventive spraying cycle since the hardner cannot set in the absence of main ingredient. It is understood that the fifth solenoid valve 441 may be held deenergized for detergent saving during continuous spraying cycles if the production tack is too fast to set the rust preventive in the spray gun.

The vehicle door assembled in the manner as described hereinbefore is installed to a vehicle body. The rust-preventive coated on the door outer panel is set to provide a desired rust proofing effect during baking after undercoating. If desired, the outer and inner panels may spot-welded after they are folded over together.

The above described panel assembling method provides the following distinct advantages: First, it can fully mix the main ingredient and hardner of a two-component, solventless, thermosetting, rust preventive and achieve an improved rust-proofing effect by atomizing them just before their mixing. Second, it requires a simple spraying apparatus without the need for a mixer. The main ingredient and hardner are mixed in a cylindrical mixing chamber forming part of a spray gun. Third, it uses a two-component rust preventive easy in maintenance.

Claims

1. A method of assembling automobile panels, which comprises: (a) atomizing separately first and second portions of a two-component, solventless, thermosetting rust preventive; (b) mixing the first and second portions to form the rust'preventive; (c) spraying the resulting rust preventive on the panel; (d) making a vehicle component from the panel; (e) installing the vehicle component to a vehicle body; and (f) heating the vehicle body to set the rust preventive.

2. A panel assembling method as set forth in claim 1, wherein the first and second portions are atomized by applying pressure to the first portion enclosed in a first chamber and also to the second portion enclosed in a second chamber, and then opening the first and second chambers.

3. A panel assembling method as set forth in claim 2, wherein the first and second chambers are opened in facing relation into a third chamber within which a plunger is adapted to reciprocate for connecting and disconnecting the first and second chambers from the third chamber.

4. An apparatus for spraying a two-component solventless, rust preventive comprised of main ingredient and hardner, which comprises: (a) a mixing chamber communicated through a nozzle to atmosphere; (b) first and second atomizing chambers opening to the mixing chamber; (c) valve means for selectively connecting and disconnecting the first and second atomizing chambers from the mixing chamber, the valve means normally disconnecting the first and second atomizing chambers from the mixing chamber; (d) a main ingredient source for charging the main ingredient to the first atomizing chamber; (e) a hardner source for charging the hardnerto the second atomizing chamber;; (f) metering means for metering the main ingredient and the hardner to be supplied therethrough to the first and second atomizing chambers to maintain a predetermined ratio of the main ingredient and the hardner; (g) pressurizing means for applying pressure to the main ingredient and the hardner charged in the first and second atomizing chambers when actuated; and (h) control means for actuating the pressurizing means after charging of the main ingredient and the hardner to the first and second atomizing chambers is completed, and causing the valve means to connect the first and second atomizing chambers to the mixing chamber for a predetermined period of time after the main ingredient and the hardner are fully pressurized.

5. An apparatus as set forth in calim 4, wherein the first and second atomizing chambers open to the mixing chamber in aligned relationship to each other.

6. An apparatus as set forth in claim 5, wherein the valve means comprises a plunger placed in the mixing chamber for reciprocating movement so as to selectively connecting and disconnecting the first and second atomizing chambers from the mixing chamber.

7. An apparatus as set forth in calim 4, wherein the nozzle has a port communicated through a valve with a ddetergent source for supplying a detergent into the nozzle, the valve adapted to open for a predetermined period of time when the valve means disconnects the first and second atomizing chambers from the mixing chamber.

8. An apparatus as set forth in calim 7, wherein the detergent source is the hardner source.

9. An apparatus as set forth in claim 7, wherein the detergent source is the main ingredient source.

10. An apparatus for spraying a two-component, solventless, rust preventive comprised of main ingredient and hardner, which comprises: (a) a spray gun including: a mixing chamber communicated through a nozzle to atmosphere; first and second atomizing chambers opening to the mixing chamber; valve means for selectively connecting and disconnecting the first and second atomizing chambers from the mixing chamber, the valve means normally disconnecting the first and second atomizing chambers from the mixing chamber; (b) a main ingredient source for supplying the main ingredient to the first atomizing chamber; (c) a hardner source for supplying the hardnerto the second atomizing chamber;; (d) a first metering chamber interposed between the main ingredient source and the first atomizing chamber for metering the main ingredient passing therethrough to a predetermined amount; (e) a second metering chamber interposed between the hardner source and the second atomizing chamber for metering the hardner passing therethrough to a predetermined value; (f) a first normally closed valve interposed between the main ingredient source and the first metering chamber; (g) a second normally closed valve interposed between the hardner source and the second metering chamber; (h) pressurizing means for applying pressure to the main ingredient charged in the first metering chamber and also the hardner charged in the second metering chamber when actuated; and (i) control means for opening the first and second valves to permit the supply of the main ingredient and the hardnerto the first and second atomizing chamber for a predetermined period of time, actuating the pressurizing means for a predetermined period of time after the opening of the first and second valves, and causing the valve means to connect the first and second atomizing chambers to the mixing chamber for a predetermined period of time after the main ingredient and the hardner are fully pressurized.

11. An apparatus as set forth in claim 10, wherein the pressurizing means comprises a forked plunger having two fingers inserted in the first and second metering chambers, respectively, the forked plunger adapted to move in the direction reducing the volume of the first and second metering chambers when the pressurizing means is actuated.

12. An apparatus as set forth in claim 10, wherein the first and second atomizing chambers open to the mixing chamber in aligned relationship to each other.

13. An apparatus as set forth in claim 12, wherein the valve means comprises a plunger placed in the mixing chamber for reciprocating movement so as to selectively connecting and disconnecting the first and second atomizing chambers from the mixing chamber.

14. An apparatus as set forth in claim 10, wherein the nozzle has a port communicated through a valve with a detergent source for supplying a detergent into the nozzle, the valve adapted to open for a predetermined period of time when the valve means disconnects the first and second atomizing chambers from the mixing chamber.

15. An apparatus as set forth in claim 14, wherein the detergent source is the hardner source.

16. An apparatus as set forth in claim 14, wherein the detergent source is the main ingredient source.