Method and apparatus for coating vehicle bodies

June 7, 1966 h. r. j. knight etal 3,255,037

METHOD AND APPARATUS FOR COATING VEHICLE BODIES

Filed March 8, 1962 5 Sheets-Sheet 1

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Attorneys

June 7, 1966 h. r. J· knight etal 3,255,037

METHOD AND APPARATUS FOR COATING VEHICLE BODIES , _ ₁₍₅m 3 Sheets-Sheet 2

Filed March 8, 19o2

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Attorneys

June 7, 1966 h. r. j. knight et al 3,255,037

METHOD AND APPARATUS FOR COATING VEHICLE BODIES

Filed March 8, 1962 3 Sheets-Sheet 3

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Inventors

HOWARD RJ. KNIGHT

ALEXANDER A.BUCKEy

By /wiu cux.o(

Attorneys

United States Patent Office _p ,, ³’^255,037

Patented June 7, 1966

3,255,037

METHOD AND APPARATUS FOR COATING VEHICLE BODIES

Howard Richard James Knight, Leamington Spa, and Alexander Alfred Buckey, London, England, assignors, 5 by mesne assignments, to Howard Vincent Schweitzer, Cleveland, Ohio

Filed Mar. 8,1962, Ser. No. 178,364 Claims priority, application Great Britain, Mar. 10,1961, 8,934/61

Claims. (CI. 117—105.3) 10

The present invention relates to the coating of surfaces of a succession of similarly shaped objects of different forms which are connected in spaced relation by conveying means actuated at a substantially constant rate, 15 for example the spray coating of vehicle bodies.

In the mass production of automobiles, the automobile bodies are normally connected in spaced relation on a floor conveyor and are coated by passing them in succession through a spraying apparatus including spray 20 guns suitably mounted to direct paint sprays onto the sides and tops of the bodies. The guns are mounted so that, as the bodies are moved through the apparatus, the guns traverse the bodies transversely to the direction of travel of the bodies. Also means are provided 25 to tilt the guns to ensure that coating material is sprayed uniformly over the body surfaces even though the surfaces are curved. Moreover the body surfaces may have sudden changes as for example in a saloon body at the rear of the bonnet where the top surface of the body lifts 30 to the front of the roof.

In the known automobile body spraying apparatus the guns are in some cases supported on carriages which are reciprocated on tracks arranged transversely of the path of travel of the bodies, the tracks having associated cam 35 tracks following the body surfaces facing them so that the guns as they are reciprocated follow the contours of the bodies.

Such known paint spraying apparatus has the disadvantage that it must be set up with the appropriate gun 40 carriages and cams for the form of the bodies being coated, and are not therefore capable of painting bodies of different forms, that is different shapes and sizes without being set up anew.

Automobile bodies are often made in a number of 45 different shapes for each type of chassis, for example, there are often saloon, coupe and van derivatives of the same model. Further, there may be different sizes of each derivative so that the known apparatus cannot be used for different body shapes and sizes in a continuous 50 operation but each batch passed through the spray coating apparatus must in substance be all of the same type and size, and the apparatus must be reset for each different body form.

It is a main object of the present invention to provide 55 a method and apparatus for automatically spray coating similarly shaped objects of different forms in which the objects can be loaded indiscriminately to a conveyor, a particular object of the invention being the automatic spray coating of automobile bodies of different sizes and 60 shapes which are loaded indiscriminately on to a conveyor.

According to the invention there is provided a method of coating surfaces of a succession of similarly shaped objects of different forms connected in spaced relation by conveying means actuated at a substantially constant rate, by traversing side sprays simultaneously up and down over the sides of each object as it is advanced, and traversing a downwardly directed top spray to and fro over the top of the object, wherein the form of each ⁷⁸object is detected as it is advanced, and a predetermined programme of movement and operation of the sprays is automatically selected appropriate to the detected form of the object, the sprays being maintained at a substantially constant intensity over the surfaces of the object to be coated, thereby to effect uniform coating of said surfaces.

Further according to the invention there is provided a method of coating surfaces of a succession of vehicle bodies of different sizes and shapes connected in spaced relation by conveying means actuated at a substantially constant rate by reciprocating side sprays simultaneously up and down over the sides of each body as it is advanced and traversing a downwardly directed top spray to and fro over the top of the body, wherein the size and shape of each body is detected as it is advanced, a predetermined programme of movement and operation of the side sprays is automatically selected to spray uniformly the side surfaces of the vehicle body, and a predetermined programme of movement and operation of the top spray is selected to spray uniformly, as appropriate the bonnet top, roof and boot lid of. the body, the sprays being maintained at a substantially constant intensity over the surface to be coated.

Preferably the bodies are supported on the conveying means with their roofs all at substantially the same level and the size of each body is detected as it is advanced by detecting its length. The detection of a large body size causes the side sprays to move apart to accommodate the width of the body.

For coating according to the invention surfaces of saloon, coupe and van derivatives of the same vehicle body size, the presence of a van derivative is detected by detecting the presence of extended surfaces to be coated above the level of the top of the bonnet, and a programme of movement and operation of the side sprays is selected to cause said sprays to effect long painting strokes over the sides of the van body.

Further according to the invention the top spray is retracted at a predetermined time after top spraying of the bonnet has commenced. When coating a saloon or van body the presence of the saloon or van body may be detected by detecting the front edge of the roof of the body, and the top spray is retracted as soon as the front edge of a roof is detected.

The bonnet of a coupe body is usually longer than the bonnet of a saloon or van body of the same model, and said predetermined time may be preset according to the length of the coupe bonnet, so that the windscreen pillars of coupe bodies are protected from damage by the top spray gun.

The invention also comprehends apparatus for coating surfaces of a succession of similarly shaped objects of different forms connected in spaced relation by conveying means actuated at a substantially constant rate, comprising side spray guns mounted for reciprocation along vertically disposed supports spaced apart on either side of the path of travel of the objects, a downwardly directed top spray gun mounted for reciprocation along a horizontally disposed support above the path of travel of the objects, means for detecting the form of each object as it is advanced towards the spray guns, and control means for the spray guns connected to the detecting means and operable to control according to a predetermined programme selected by the detecting means, movement of the spray guns so that they are maintained at a substantially constant distance from object surfaces to be coated as the guns are reciprocated, and operation of the spray guns so that spraying is effected only on to said surfaces to be coated.

Further the invention comprehends apparatus for coating surfaces of a succession of vehicle bodies of different

3,255,037 sizes and shapes connected in spaced relation by conveying means actuated at a substantially constant rate, comprising side spray guns mounted for reciprocation along vertically disposed supports spaced apart on either side of the path of travel of the bodies, a downwardly 5 directed top spray gun mounted for reciprocation along a horizontally disposed support above the path of travel of the bodies, adjustable supporting means connecting the top spray gun to the horizontal support so that the top spray gun can be raised and lowered to follow as appro- jq priate the shape of the bonnet, roof and boot of the vehicle bodies, means for detecting the form of each body as it is advanced towards the spray guns, and control means for the spray guns connected to the detecting means and operable to control, according to a predeter- 15 mined programme selected by the detecting . means, movement of the spray guns so that they are maintained at a substantially constant distance from, vehicle body surfaces to be coated as the guns are reciprocated, and operation of the spray guns so that spraying is effected ₂0 only on to said surfaces to be coated.

In a preferred embodiment of the invention the detecting means includes a first and a second photoelectric device, each with an associated light source mounted on opposite sides of the path of travel of the articles at a height 25 such that light beams from the light, source are broken by the bonnet of a vehicle body, said first and second photoelectric devices being spaced apart in front of the spray guns by a distance greater than the length of a small vehicle body but less than the length of a large 30 vehicle body and the first photoelectric device being mounted just in front of the side spray guns so that when the light beams of the first photoelectric device is broken the control means is operable to initiate movement and operation of the side spray guns and when said, light 35 beams are broken simultaneously the photoelectric devices signal to the control means an indication of the approach of a large body.

The control means may be operable on receipt of signals indicative of an approach of a large body, to move 40 apart said vertically disposed supports and to select the appropriate predetermined spraying programme of the top and side guns for a large body.

For detecting the presence of a van body, the detecting means may include a third photoelectric device and as- ₄sociated light source mounted above the first photoelectric device and at a height between the top and bottom of the windscreen of bodies to be coated, said third photoelectric device being so positioned that its light beam is broken when a van body is advanced towards the ₅₀spray guns so that the third photoelectric device indicates to the control means the presence of a van body and the control means selects the appropriate spraying programme of the side guns for coating the sides of the superstructure of the van body. 55

For effecting control of the top spray gun in the preferred embodiment of the invention the detecting means includes a fourth photoelectric device and associated light source mounted on opposite sides of the path of travel of the bodies at the same height as the first and 60 second photoelectric devices and between the first photoelectric device and the top spray gun, the fourth photoelectric device being arranged so that the breaking of its light beam by a bonnet of a vehicle body initiates movement and operation of the top spray gun according to a predetermined programme determined by the indications of the body size and shape signalled from the first and second photoelectric devices to the control means. γθ

Further according to the invention the detecting means includes a fifth photoelectric device and associated light source mounted just in front of the top spray gun and so positioned that the light beam is broken by the roof of connected to the control means to control the raising of the top gun as soon as the bonnet has been sprayed.

The invention also comprehends a vehicle body coated by the above described method.

In order that the invention may be more clearly understood a preferred embodiment thereof for the coating of automobile bodies will now be described, by. way of example, with reference to the accompanying diagrammatic drawings in which:

FIGURE 1 is a side view of different automobile body shapes and showing the position of spray coating apparatus, as well as the position of the body form detecting devices,

FIGURE 2 is an end view of a small van in the apparatus of FIGURE 1,

FIGURE 3 is an end view with a large saloon body in the apparatus (in full lines) and an end view of a small body in the apparatus (in dotted lines),

FIGURE 4 is a line diagram of pneumatic control apparatus for effecting the method of operation of the painting apparatus described with reference to FIGURES 1 to 3, and

FIGURE 5 is a diagram of an electric circuit for controlling the apparatus shown in FIGURE 4.

In the drawings like reference numbers indicate the same or similar parts.

Referring to FIGURES 1 to 3 of the drawings, coating apparatus according to the invention is adaptable for spray coating a succession of similarly shaped automobile bodies of different forms connected in spaced relation on a floor conveyor, not shown, which is actuated at a substantially constant rate. The bodies fall into two size groups and are of different shapes within each size group.

The size groups comprise small bodies such as that shown in dotted lines 1 in FIGURE 3, and large bodies such as that shown in full lines 2 in FIGURE 3.

Appropriate supporting frames are provided for connecting each body to the conveyor, so that the roofs of the bodies on the conveyor are all at substantially the same level regardless of the size and shape of the body. When in position on the conveyor the waist window levels of the bodies of both size groups are at substantially the same level as indicated at 3 in FIGURE 3.

In each of the size groups the bodies may have different shapes, the apparatus herein described being for coating saloon, coupe and van derivatives of small bodies, and saloon and coupe derivatives of large bodies. This is illustrated in FIGURE 1 in which the body represented in full outline 4 is a small saloon, the body shown in unshaded dotted outline 5 is a large saloon, and the shaded-in dotted outline 6 represents a small van. A large coupe model which has a longer bonnet than the large saloon model 5 is indicated by the full line 7.

The spraying apparatus for spray coating the bodies as they are advanced along the conveyor includes vertically disposed supports 8 spaced apart on either side of the path of travel of the bodies. Each of the vertically disposed supports 8 includes a track along which a carriage is reciprocated by a chain drive in well known manner, and a gun arm linkage mounted on each carriage carries a side spray gun 9, the side spray guns 9 being shown in FIGURES 1 to 3 at the bottom of their traverse.

The gun arm linkages for the side guns 9 are of the kind described in United Kingdom specification No. 787,019, and by means of cams fixed to the tracks, and cam followers on the linkage, the guns are tilted as they are reciprocated so that the sprays from the guns remain substantially normal to the body surfaces to be coated to effect uniform coating of the body surfaces.

A horizontally disposed support 10 for a downwardly directed top spray gun 11 is mounted above the path of travel of the bodies and, as shown in FIGURE 1, is spaced from the side spray gun supports 8 in the direction of travel of the bodies.

a saloon or van body, said fifth photoelectric device being

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The top spray gun 11 is mounted by a gun arm linkage on a carriage which is reciprocated along a track on the support 10 in the well known manner referred to above, and the top spray gun 11 can be moved vertically towards and away from the top of a body passing underneath to 5 follow the shape of the roof of the bonnet, roof and boot of the body in the manner hereinafter described.

The side gun supports can be moved towards and away from the sides of the bodies by pneumatically operated cylinders 12 to accommodate large and small bodies. .

Saloon and van bodies in any one size group differ in shape within prescribed dimensions and because all bodies on the conveyor are presented to the coating apparatus with their bonnet roof level at substantially the same height no adjustment of the top spray gun support 10 is 15 . necessary.

Each of the side spray guns 9 and the top spray gun 11 traverse along almost the whole length of their respective supports 8 and 10 as they are reciprocated. The length of the traverse of the side spray guns 9 is indicated in FIG- 20 URE 1 by a slot 13 in the casing of the vertical support 8, through which the side spray gun 9 projects.

The reciprocating movement of the spray guns is thus sufficient to traverse completely over the sides and roof of any of the small or large bodies on the conveyor, but 25 the spray guns are only operated when the sprays which they project impinge on body surfaces to be coated. Thus a short painting stroke of the side spray guns 9 is indicated at 14 in FIGURE 3, this stroke being for painting the sides of a small saloon or coupe. A medium painting 30 stroke for painting the sides of a large saloon or coupe is indicated at 15 in FIGURE 3. A long painting stroke for painting the sides of a small van is indicated at 16 in FIGURE 2.

Similarly the top spray gun 11 has a short painting 35 stroke indicated at 17 in FIGURE 2 for the top painting of small bodies, and a large painting stroke indicated at 18 in FIGURE 3 for the top painting of large bodies.

The lengths of the painting strokes are controlled by switching control air on to the spray guns at the appropri- 40 ate times during their traverse along their supports. The control air operates a valve in the gun to release paint and atomizing air so that spraying commences as soon as control air is switched on to a gun, and stops when control air is switched off. 45

Thus for each body size and shape there is a predetermined programme of movement and operation of the spray guns, and these predetermined programmes are controlled by control means hereinafter described, which is connected to means for detecting the form, that is the 50 shape and size, of each body as it is advanced towards the coating apparatus.

Referring to FIGURE 1, the detecting means includes a first photoelectric device 19 with an associated light source, not shown, which device and source are mounted 55 on opposite sides of the path of travel of the articles at a height such that the light beam falling on the device 19 is broken by the bonnet of a body approaching the side spray guns. A second photoelectric device 20 and associated light source are spaced from the first device 19, at the 60 same height as the device 19, but in the opposite direction to the direction of movement of the bodies, by a distance greater than the length of a small body but less than the length of a large body. That is, the light beams falling on both the photoelectric devices 19 and 20 are broken 65 simultaneously by a large body.

A third photoelectric device 21 and its associated light source are mounted on opposite sides of the path of travel of the articles, directly above the first photoelectric device 19, and at a height between the top and bottom of the 70 windscreens of the bodies. This third photoelectric device 21 is so positioned that its light beam is broken by a van body when the end of the bonnet of that body is approaching the side spray guns 9.

Breaking of the light beam which falls on the first 75 photoelectric device 19 initiates movement and operation of the side spray guns 9, and movement and operation of the top spray gun 11 is initiated when a light beam falling on a fourth photoelectric device 22 is broken. As shown in FIGURE 1 the device 22 is positioned at the same height as the devices 19 and 20, but just behind the vertical supports 8 so that its light beam is broken by the front of the bonnet of a body after side spraying has commenced and the bonnet is just approaching its position in which top spraying is commenced.

A fifth photoelectric device 23 and its associated light source control the raising and lowering of the top spray gun 11 and cause the top gun 11 to be held up so long as the beam falling on the device 23 is broken, for example by the roof of a saloon or van.

Each of the photoelectric devices 19, 10, 21, 22 and 23 is connected in an electric control circuit hereinafter described with reference to FIGURE 5 and which actuates to cause operation of pneumatic control apparatus shown diagrammatically in more detail in FIGURE 4.

Referring to FIGURES 4 and 5 the centre line of the conveyor on which the bodies to be spray coated are mounted is indicated at 24 in FIGURE 4, and the photoelectric devices 19, 20, 21, 22 and 23 are respectively connected by lines 25, 26, 27, 28 and 29 to control amplifiers 30, 31, 32, 33 and 34 which are mounted in a main control panel 35. Each of the amplifiers 30 to 34 includes a relay operating a two way switch. These relay operated switches are illustrated in FIGURE 5 and they control the pneumatic circuit of FIGURE 4 and reciprocation of the spray guns along their support.

Initially consider that there is no body in the coating apparatus, a master control switch is operated so that master holding contacts 36 are closed, and a latched relay 37 is in the tripped position from the previous operation of the machine so that contacts 38 of the relay 37 are closed.

The contacts 38 are in series with the master contacts 36 and with a coil 39 of a solenoid valve 40. The contacts 36 and 38 and the coil 39 are connected in series between current supply lines 41 and 42.

The solenoid valve 40 is associated with the second photoelectric device 20 through the control amplifier 31, as indicated diagrammatically in FIGURE 4, and has an inlet connected to a compressed air supply line 43, and two outlets respectively on air lines 44 and 45 which are connected to the cylinders 12 which control the positions of the vertically disposed supports 8 for the side spray guns 9. Each of the cylinders 12 is a double acting cylinder and has a piston 46 slidable in it. The connection of the pistons 46 to the vertical supports for the side spray guns is indicated at 47.

When the coil 39 is energised air is switched by the solenoid valve 40 on to line 45 so that the pistons 46 are moved to. their innermost positions in the cylinders 12 and the side spray guns 9 are in position for spraying a small body. Initially contacts 48 on latched relay 37 are also closed, the relay 37 being initially in its tripped position so that a circuit is prepared to a coil 49 of a further mechanically latched relay 50. Contacts 51 also on relay 37 are open at this time.

The relay-operated switches in the control amplifiers 30 to 34 are shown in FIGURE 5 as a two position switch 52 in amplifier 30, a two position switch 53 in amplifier 33, a two position switch 54 in amplifier 34, a two position switch 55 in amplifier 31, and a two position switch 56 in amplifier 32. With no body in the apparatus the light beams falling on the photoelectric devices 19, 20, and 22 are not interrupted and the switches 52, 55 and 53, which each have contacts a, b and c are in the ab position. A circuit is thus made from line 41 through contacts Slab, a line 57 and a coil 58 of a latched relay 59 to the line 42. The energisation of the coil 58 holds the latched relay 59 in tripped position and contacts 60 of the relay 59 are closed.

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The closing of contacts 53ab energises coil 49 of relay 50 through the closed contacts 48 of relay 37 and relay 50 will also be tripped. As a result contacts 61 on relay 50 are closed and coil 62 of a solenoid valve 63 is energised. The solenoid valve 63 is associated with the top gun 11 and has an inlet connected to the air supply lines 43 and two outlets on lines 64 and 65 which lines are connected to a double-acting spool valve 66 which controls the supply of control air to the top spray gun 11. When the coil 62 is energised the solenoid valve 63 is operated so that air is passing along line 65. This operates the spool valve 66 to select control of the top gun for a short painting stroke 17 (see FIGURE 2) for painting the top of a small body.

Assume that the first body on the conveyor to be coated is a small body. As the body is advanced by the conveyor the light beam failing on device 20 is broken first, but the length of the small body is such that it will have passed the device 20 before it passes the photoelectric device 19 so that the beam of light falling on the device 20 will be remade before the beam falling on the device 19 is broken. When the beam of light falling on device 20 is broken a signal is transmitted on line 26 to the amplifier 31 and the switch 55 changes from the ab position to the ac position. The switch 55 changes back to the ab position when the body has passed the device 20. The operation of the switch 55 will, however, have no effect because it is in series with the contacts S2ac through contacts 60, and the switch 52 which is in the amplifier 30 connected to the photoelectric device 19 is held in the ab position because its light beam is unbroken so that the operation of the switch 55 has no effect on the circuit.

As soon as the light beam falling on device 19 is broken a signal is transmitted on line 25 to the amplifier 30 and switch 52 changes to the ac position as indicated in FIGURE 5. A circuit is thus made from line 41 through contacts 52ac, 60 and 55ab to trip coil 67 of the latched relay 37. The relay 37 was initially tripped, but energisation of the coil 67 ensures that the latched relay 37 is tripped. Contacts 38 on the relay 37 thus remain closed and the solenoid valve 40 remains in its former position switching air to line 45 so that the side spray gun mountings 8 are kept in position for spraying the small body.

Because of the energisation of coil 67 in relay 37 contacts 48 remain closed and contacts 51, connected in series with a coil 49α of the relay 50, remain open. Coil 49 of relay 50 thus remains energised becaused the switch 53 in amplifier 33 remains in the ab position as the light beam of device 22 is unbroken. Relay 50 thus remains tripped and contacts 61 remain closed so that the coil 62 of solenoid valve 63 continues to switch compressed air on to line 65 to select the short painting stroke 17 for the top spray gun 11.

When the light beam falling on photoelectric device 19 is broken and switch 52 is switched to the ac position a relay coil 68 of a time delay relay is energised. After a short time delay contacts 69 on the relay coil 68 close to energise a relay coil 70 of a side machine control relay. The relay coil 70 has contacts 71 and 72, shown in FIGURE 5 and these contacts 71 and 72 are closed by the relay coil 70 to energise a solenoid valve 73 connected to contacts 71, and contactors, connected to contacts 72, for the motor which drives the side guns 9 in their reciprocating motion up and down the vertical supports 8. The operation of the time delay relay coil 68 permits appropriate selection of the electrical and pneumatic circuits to be effected before spraying commences. The control of operation of the spray guns will be described hereinafter with reference to FIGURE 4.

At the same time contacts 74 on relay coil 70 close to energise a further coil 75 of the latched relay 59 which then operates to open contacts 60.

⁸

The function of the contacts 60 of relay 59 is as follows:

While a body is passing through the coating apparatus the beam normally falling on device 19 is broken, and 5 the next body to be coated is moving up on the conveyor and will break the light beam falling on device 20, so that switch 55 is in the ac position. However, because the contacts 60 are open the switch 55 has no effect in the circuit so that the state of the latched relay 37 10 remains unchanged despite the operation of the switch 55 and the selection system remains unaltered. This is thus a safeguard against any response of the electrical and pneumatic systems when two bodies are breaking light beams at the same time.

When the light beam to device 19 is remade after the tail of a body has passed the switch 52 changes back to the ab position, coils 68 and 70 are de-energised so that contacts 71 and 72 open and the side machines are stopped when the tall end of the body has just passed the side guns 9. At the same time the coil 58 is energised to trip relay 59 so that contacts 60 reclose to prepare the circuit for the next body on the conveyor.

In a similar manner for operation of the top gun 11 when the light beam falling on the photoelectric de25 vice 22 is broken the switch 53 is operated to the ac position and a relay coil 76 is energised to close contacts 77 which initiate the reciprocation of the top spray gun 11 at a time when the top spray just reaches the front edge of the top of the bonnet, and to close con³⁰ tacts 78 which energise the coil of a top gun solenoid valve 79.

The control of the top spraying stroke will be described with reference to FIGURE 4, and at the end of the top spraying cycle when the light beam to the 35 device 22 is remade switch 53 changes back to the ab position so that the circuits of the latched relay 50 are connected into circuit to prepare for the selection of the top gun stroke for the next body.

Selection by the new body cannot take place until ⁴θ spraying of the top of the previous body has been completed. If the next body to be coated is also a small body the selection of the predetermined programme of movement and operation of the gun 11 for spraying the next body will remain unaltered.

If, however, the next body to be coated is a large body the light beams to devices 19 and 20 will be broken at the same time so that switches 52 and 55 will each be in the ac position at the same time. As contacts 60 were closed on completion of the coating of the pre50 vious body, the closing coil 80 of relay 37 is energised and contacts 38 open to de-energise the coil 39 of the solenoid valve 40 so that air is switched to line 44 and the pistons 46 in the cylinders 12 move the side spray guns 9 apart to prepare for the large body. Contacts 55 48 open and contacts 51 close but these contacts have no effect until the spraying of the top of the previous body has been completed, that is until switch 53 is in the ab position to complete the circuit to the closing coil 49α of relay 50. When this coil 49α is energised 60 contacts 61 open to de-energise the coil 62 of the solenoid valve 63 so that air is switched on to line 64 to operate the spool valve 66 to select the long painting stroke 18 for the top gun.

The circuits continue to operate in the same way as θ5 described above for spraying of a small body and contacts 60 again open when the operation of the side guns starts to ensure that no further selection can be effected until the spraying of the body has been completed.

₇θ · If the next succeeding body is again a large body the relays 37 and 50 will again be energised in turn and the . setting of the electrical circuit will remain unaltered.

• If the next succeeding body after the large body is a small body the trip coils 67 of relay 37 and 49 of relay 75 50 will be energised in turn thus re-energising solenoid

3,355,037 valve coils 39 and 62 to change over the solenoid valves 40 and 63 for small body operation.

If the apparatus is switched off the master contacts 36 open and similarly if there is a failure in the electric supply on lines 41 and 42 the coils 39 and 62 are deenergised and the supports 8 for the side machine move out into position for spraying a large body, this being the safe position. It will be noted that because of the use of latched relays the contacts will not move when the supply is switched off and when the supply is restored the original selection of the machine is still in position.

• If the body being coated is a small van the presence of the superstructure of the van body is detected by the third photoelectric device 21 as the end of the bonnet approaches the side spray guns. When the light beam falling on the photoelectric device 21 is broken a signal on line 27 is transmitted to the amplifier 32 and switch 56 in the amplifier 32 changes over to the ac position. As contacts 81 of relay 70 are closed, coil 82 of a van selection solenoid valve 83 is energised. The solenoid valve 83 has an inlet connected to air supply line 43 and two outlets on lines 84 and 85 which are connected to spool valves 86, the operation of which will be described below. The spool valves 86 control the operation of the side spray guns 9 so that they change over from the short painting stroke 14 for the van bonnet sides to the long painting stroke for the sides of the superstructure of the van body.

Should there be on the production line a coupe type of body where windscreen pillars stick upwards from the waist level 3, as indicated by the outline 7 in FIGURE 1, then this could cause an accident to the top spray gun 11 as the absence of a roof to the body, which roof breaks the light beam to the device 23 to control operation of the apparatus for raising the top spray gun when the end of the bonnet is reached, could cause the top gun to collide with the windscreen pillars if it failed to rise. The beam of light is directed on to this photoelectric device at an angle such that the light beam is broken by the roof ⁴⁰of a saloon or van body as it passes along the conveyor. When the light beam falling on the device 23 is broken a signal on line 29 is passed to amplifier 34 and switch 54 is changed from its ab position to its ac position.

Top spraying is initiated when the beam falling on 45 device 22 is broken by the front of the bonnet, and a circuit is made through contacts 53ac and normally closed contacts 87 of a relay 88 to energise the control clutch coils 89 and 90 of timers 91 and 92. Both the timers 91 and 92 start running at the same time and timer 92 is set 50 for a longer time period than timer 91. Operation of the top spray gun commences in the normal way with the spray gun held down· over' the bonnet of the vehicle when relay 76 is energised to start top spraying.

Just before the windscreen pillars are reached the top 55 gun is still down over the top of the bonnet because light beam 23 is not broken by a body roof, and timer 91 then operates opening contacts 93 and closing contacts 94. The opening of contacts 93 causes de-energisation of coil 95 of a cylinder solenoid valve 96 which has an θο inlet connected to air supply line 43 and two outlets connected by lines 97 and 98 to a double-acting cylinder 99 in which a piston 100 slides to raise and lower the top spray gun 11. The solenoid valve 96 normally maintains pressure on line 98 so that the top spray gun 55 is in its lowered position ready to begin spraying the top of a bonnet. When the coil 95 is de-energised air is switched by the valve 96 on to line 97 and the top spray gun 11 is retracted before it is reached by the windscreen pillars of the coupe body. At the same time the closing of 70 contacts 94 completes a circuit to a relay coil 101, so that contacts 102 open to de-energise the coil 76 which stops the top gun from spraying while the well of the coupe body passes under the spray gun. The timer 92 is set so that it operates when the back end of the inside 75 or well, of the body is just passing under the spray gun, and contacts 102α then close to re-energise the coil 95 so that solenoid valve 96 switches air back to line 98 to lower the top gun 11 ready for spraying the top, of the 5 boot. At the same time contacts 103 open to de-energise relay 101, so that contacts 102 reclose to re-energise relay coil 76 so that top spraying starts again over the boot.

The timers 91 and 92 are reset when the light beam 70 falling on photoelectric device 22 is remade as the tail of a body passes under the top gun 11.

When a saloon or van body is being sprayed the top gun 11 has to be raised at the approach of the windscreen but spraying must not be stopped as the top gun 15 has to spray the roof of the body. The timers 91 and 92 are started as before by operation of the switch 53 when the beam falling on device 22 is broken, but if the saloon or van bonnet is shorter than that of the coupe model the light beam on device 23 will be broken before 20 the timer 91 has operated. When the beam on device 23 is broken switch 54 changes to the ac position and as relay coil 76 is already energised contacts 104 on relay 76 are closed to complete the circuit to relay coil 88. Contacts 87 on relay 88 open to de-energise the 25 timer control clutch coils 89 and 90 and the timers will be reset. The solenoid valve coil 95 will also be deenergised and as the relay 101 cannot operate the spray gun 11 rises to its top position for spraying the roof and spraying of the roof continues.

³θ The light beam on device 23 is remade when the end of the roof passes the device 23 and switch 54 changes back to the ab position so that coil 95 of valve 96 is reenergised and the spray gun 11 is lowered for spraying the top of the boot. Relay coil 88 remains energised, however, through contacts 105 on relay 88 and the timers therefore remain inoperative. The circuit of the timers is returned to normal ready for the next body as soon as spraying is completed as determined by the remaking of the light beam falling on the device 22, which causes deenergisation of relay 76 whereon contacts 104 on relay 76 open, the relay 88 is de-energised and contacts 87 are closed.

If the bonnet of the saloon or van body is longer than that of the coupe the timer 91 will operator to retract the top spray gun 11, and spraying stops until the beam falling on device 23 is broken by the roof of the saloon or van, when conditions for spraying the roof revert to normal. In this case some hand touching-up of the rear end of the bonnet may be necessary.

Each of the spray guns 9 and 11 is supplied with paint and atomising air for atomising the paint, the atomising air being fed through a-valve in the gun which is controlled by control air supplied to the gun. As the guns are reciprocated across the path of the bodies, control air is switched to the guns at the appropriate times to control the painting strokes. This switching of control air is effected under the control of cam-operated valves which are selected to control the appropriate spraying programme for the body which has been detected.

There are three cam-operated valves to switch control air to the side guns, respectively to determine-short, medium and long painting strokes of the side guns, and there are two cam-operated valves to switch control air to the top gun to determine long and short painting strokes.

The cams which operate the valves for the side guns are mounted on a common shaft driven from the drive which causes the side guns to reciprocate, the cam shaft being geared to the drive so that the cams rotate once for each traverse of the side guns up or down their supports. During each revolution each cam controls the “cut-on” and “cut-off” of control air to the side guns, and the cams are adjustable so that they can be accurately set for each painting stroke.

3,255,037

Similarly the two cams which operate the valves for the top gun are mounted on a common shaft geared to the drive for the top gun carriage so that the cams rotate once for each traverse of the top gun to or fro across the top of the body being coated.

Referring to FIGURE 4, control air is fed on a line 106 from the solenoid valve 73, through a cock 107 to control air spool valves 108 for the side guns 9. The valves 108 are opened and closed together, at times determined by the selected side gun cam-operated valves, to control the supply of control air to the side guns.

Lubricated air is fed on a line 109 to the three camoperated valves 110, 111 and 112 for the side guns. There is a set of three valves 110', 111 and 112 for each gun 9 as shown in FIGURE 4. Lubricated air on line 109 is also fed to the cock 107.

The valve 110 controls the medium’ painting stroke 15, FIGURE 3, and is connected by a line 113 to one inlet of a body selection spool valve 114 whose outlet is connected by a line 115 to the control inlet of the control air spool valve 108.

The valve 111 controls the long painting stroke 16, FIGURE 2, for painting the sides of a small van, and is connected by a line 116 to one inlet of the van selection spool valve 86. The valve 112 controls the short painting stroke 14, FIGURE 3, and is connected by a line 117 to the other inlet of the spool valve 86, whose outlet is connected by a line 118 to the second inlet of the body selection spool valve 114.

Lubricating air on line 109 is also connected to the two cam-operated valves 119 and 120 for the top gun 11, and control air for the top gun is fed on a line 121 connected to one outlet of the top gun solenoid valve 79. The line 121 is connected through a cock 122, to which line 109 is also connected, to a top gun control air spool valve 123.

The cam-operated valve 119 controls the long painting stroke 18, FIGURE 3, and is connected by a line 124 to one inlet of the body selection spool valve 66. The valve 120 controls the short painting stroke 17, FIGURE 2, and is connected by a line 125 to the other inlet of the spool valve 66, whose outlet is connected by a line 126 to the control inlet of the control air spool valve 123.

When the light beam falling on the photoelectric device 19 is broken by an advancing body, relay 70 operates and initiates operation of the drive of the side spray gun carriages.

Simultaneously solenoid valve 73 changes over, allowing control air to pass from line 43 on to line 106, that is control air is switched on to the whole of the control air circuit of the apparatus.

If the body is a large saloon or coupe body the light beam falling on the device 20 is broken at the same time as the beam of device 19 and the solenoid valve 40 changes over and air passes along line 44 to the cylinders 12 under each side gun support 8, moving them both out relative to the conveyor to suit the width of the large body. Air on line 44 also operates the body selection spool valves 114 which then connect cam-operated valve 110 to the control air spool valves 108 to open the side guns and effect a medium painting stroke of the side guns.

The breaking of the light beam of device 20 also prepares the electric circuits controlling the top gun so that on completion of spraying of the preceding body, and when the light beam to device 22 is broken again, solenoid valve 63 for the top gun changes over and control air is switched from line 43 onto line 64 to operate the spool valve 66 so that valve 119 is connected to the control air spool valve 123.

Next the breaking of the light beam of device 22 causes the solenoid valve 79 to change over and control air passes along a circuit 121 to the top gun control air spool valve 123, and the energisation of relay 76 at this time switches on the drive for the top gun 11 which opens and begins its long painting stroke controlled by valve

119 at the same time as the front of the top of the bonnet is just presented to the top spray.

When the light beam falling on the photoelectric device 23 is broken, solenoid valve 96 operates and control air passes along line 97 to the bottom of cylinder 99 and the top gun is retracted.

If a small body is identified on the conveyor by the photoelectric devices 19 and 20, solenoid valve 40 operates to feed air on line 45 to change over the spool valve 114 so that the control air spool valve 108 is connected to the outlet line 118 of the van selection spool valve 86. The circuits for the top gun are also prepared so that when the beam on device 22 is broken solenoid valve 63 operates to feed air on line 65 to the spool valve 66 of the top gun, which then connects the camoperated valve 120 to the control air spool valve 123 so that the top gun is controlled to effect a short painting stroke.

If the small body is a saloon or coupe body the solenoid valve 83 directs air on to line 84 and the spool valve 86 connects the cam-operated valve 112 to the line 118 so that the spray guns 9 are controlled to effect a short side painting stroke. If the small body is a van body, then a signal on line 27 from the photoelectric device 21 causes the valve 83 to change over so that air is fed on line 85 to change over the spool valve 86, and cam-operated valve 111 is connected to line 118 so that the spray guns 9 are controlled to effect a long painting stroke to cover the sides of the van body.

It will be understood that an additional van selection feature may be provided in the circuit of FIGURE 4 for the coating of large van bodies, an extra cam-operated valve and spool valve being associated with the line 113. Also if there are no van bodies to be coated, the van selection feature can be omitted from the circuit.

The cocks 107 and 122 are provided in the air lines 106 and 121 so that if the automatic control of the coating apparatus should fail, the apparatus can be operated on hand control by turning the cocks 107 and 122 to a position in which lubricated control air on line 109 is fed through the cocks directly on to lines 106 to 121.

It will be understood that in the electrical circuit described herein with reference to FIGURE 5, whilst the selection of a predetermined programme of operation and movement of the spray guns is effected by detection of the form of the body which is about to pass between the side gun supports 8, the change over to small or large body operation is instantaneous for the side guns, but it should be understood that this does not apply to the top gun as the top gun circuits do not change over until •after the top gun has finished painting the preceding body which is still passing underneath the top gun as the form of the next body is detected.

Moreover once a small or large body has been identified the gun mountings will stay locked in their appropriate positions for that size of body until the next size of body is identified, that is there is no return to a datum after each body.

Further, as a safety factor, should there be any electrical failure in the circuits the gun mountings will fail safe, i.e. the side gun mountings will open out and the top gun will be retracted, in order to pass the largest body. This also happens when an emergency stop button in the electric circuit is pressed to break the electrical supply to the circuit.

Should there be on the production line from time to time a coupe body as indicated by 7 in FIGURE 1 the absence of a roof to break the light beam falling on device 23 means that the top gun 11 would fail to rise after painting the bonnet and would collide with the windscreen pillars.

To avoid this happening the breaking of the light beam falling on device 22 causes the timer 91 to run as already described with reference to FIGURE 5, at the end of which run solenoid valve 96 changes over and raises the

3,255,037 ¹³ top gun 11. Simultaneously, the solenoid valve 79 is also cut oS so that top gun stops spraying.

The second timer 92 starts at the same time as the first timer 91 and continues to run, the presetting of the timer 92 being such that it brings the gun 11 down over the boot lid for normal spraying to take place.

As described with reference to FIGURE 5, when a saloon or van body is detected the breaking of the light beam of cell 23 over-rides the protective device just described, in those instances where bonnet lengths of the saloon or van are approximately equal to or shorter than the coupe. For those bodies whose bonnet length is longer than the coupe, then the top gun 11 will rise under control of the timer 91 at the same time as it would in the case of a coupe bonnet, and the spray will cut off and will not come on again until the light beam of device 23 is broken. This avoids overspray from the gun at high level onto the bonnet.

The coating apparatus described herein is operable to spray vehicle bodies which fall into two size groups as indicated in FIGURES 1 to 3, and it will be apparent that the dimensions of the bodies in each group may vary as long as the dimensions are not so different from those for which the painting strokes are determined, that either objectional overspraying of the bodies occurs, or the edges of the body surfaces to be coated are not adequately coated.

It will also be understood that although detection of body size has been described as being effected by detecting the length of each body on the conveyor as it advances towards the coating apparatus, detection of the width of each body, by means of a suitable arrangement of photoelectric devices and light sources, may be employed for determining body size.

Further, although in the embodiment described herein the spray guns are pneumatically operated spray guns, it will be apparent that the spray guns may be electrostatic spray heads, the pneumatic control circuit described herein being replaced by the appropriate electrical control circuit.