GB2193447A - Electrostatic spray coating apparatus - Google Patents

Abstract

A portable apparatus for electrostatically spray coating the surface of an object 200 to be coated with an atomised liquid, comprises an atomising cup 50 for emitting atomised liquid into a high electric field created between the cap and object. The liquid is fed to an inlet 24 and fed to the interior of the cup via a line 27 under the control of a trigger-actuated valve 28. Gas is fed centrally, at 6, to the cup, and also serves to rotate the cup by means of a turbine wheel 43. <IMAGE>

Description

SPECIFICATION Portable apparatus for electrostatically spray coating This invention relates to a portable apparatus for electrostatically spray coating the surface of an object to be coated with an atomised liquid.

Conventionally, an electrostatic paint spray apparatus is installed in a predetermined place for use. Depending upon the object to be coated, some minute portions thereof must be coated. However, a conventional paint spray apparatus cannot perform coating efficiently on such minute portions.

The object of this invention is to provide a portable electrostatic coating or paint spray apparatus which is capable of performing an efficient coating operation even on minute portions of the object to be coated and with which the user can perform coating while holding the spray apparatus.

According to this invention, there is provided apparatus for electrostatically spray coating the surface of an object to be coated with an atomised liquid, including a body part to be held, a head portion on the body part, an atomising device for atomising coating liquid mounted on the head portion, means by which liquid can be supplied to such atomising device and means by which, in use, the device can be connected to a means to create an electric field, such that an electric field is created between the device and-an object to be coated.

A preferred embodiment of an electrostatic paint spray apparatus according to this invention wili now be described with reference to the drawings.

Figure 1 is a schematic perspective view of an electrostatic paint spray apparatus according to this invention; Figure 2 is a schematic cross-sectional view of a electrostatic paint spray apparatus according to this invention; Figure 3 is a perspective view of an embodiment of an electrostatic paint spray apparatus according to this invention.

Figure 4 is a front view of the embodiment of Fig. 3; Figure 5 is a right side view of the embodiment of Fig. 3; Figure 6 is a rear tiew of the embodiment of Fig. 3; Figure 7 is a left side view of the embodiment of Fig. 3; Figure 8 is a plan view of the embodiment of Fig. 3; Figure 9 is a bottom view of the embodiment of Fig. 3.

Figure 10 is an end view of a cup to be attached to the head portion of the apparatus shown in Figs. 1 and 2; Figure 11 is a cross sectional view of the cup of Fig. 10, showing also an extension of the coating supply pipe; and Figure 12 is a view similar to Fig. 2 but with the cup shown in place and the relation between the apparatus and an object to be coated illustrated.

Referring to Figs. 1 and 2, an electrostatic paint spray gun apparatus 1 includes a hold portion 2 that the user holds and a head portion 3 for mounting thereon a spray gun device which atomizes and emits paint as a coating liquid. The hold portion 2 has an internal passageway 5 extending longitudinally therethrough, one opening 7 of which is supplied externally with gas 6, for example, air, under a predetermined pressure. The gas is discharged from the other opening 8 through internal passageway 5. A trigger member 9 is mounted pivotably at one end 11 thereof to a part 10 of hold portion 2. Rod members 12 and 13 are fixedly connected to the trigger member 9. Said rod members 12 and 13 extend in opposite directions respectively. Said rod member 12 is inserted into a sleeve 14 and fixed to sleeve 14. A chamber 16 is formed at a inner portion 15 of the hold portion 2.Said chamber 16 accommodates a coil spring 18 which pushes the rod member 13 resiliently in the direction of arrow 19. By swinging the trigger member 9 in the direction of arrows 20, the sleeve 14 is reciprocated in the direction of arrows 21.

The head 3 is fixedly inserted into a hole 23 provided in one end 22 of the hold portion 2. The head 3 includes a base 31 which in turn includes a paint receiving inlet 24 through which paint 26 is supplied externally at a predetermined pressure. A needle valve 25 is connected to the inlet 24. Said needle valve 25 is connected to the inlet 24. Said needle valve 25 controls a quantity of paint supplied by movements or reciprocation of a needle. 28 in the direction of arrows 21. Said needle 28 is fixed to the sleeve 14 and moves in accordance with the movement of the sleeve 14 in the direction of arrows 21. Paint 26, the supply quantity of which is controlled by the nee- dle valve 25, is supplied to a pipe 27 connected to an outlet 29 of the needle valve 25 to be emitted from an opening 30 of pipe 27.

Base 31 also has a penetrating hole 32 through which gas 6 passes. Said gas 6 is a carrier air supplied from internal passageway 5 in hold portion 2. Base 31 has also an internal chamber 33 in which a shaft 35 having a penetrating hole 34 is mounted so that it is rotatable around its axis 4 and that gas -6 having passed through penetrating hole 32 is discharged through penetrating hole 34 in the shaft 35. Said shaft 35 is supported by bearings 36 and 37 which are fixed to base 31 through a cylindrical member 38 fixed within chamber 33. Said shaft 35 is prevented from moving along axis 4 by a collar 40 provided at one end 39 thereof and by a ring member 42 provided at the other end 41 thereof. An impeller 43 is mounted integrally on the outer surface of the shaft 35 coaxially with the axis 4.Impeller 43 has a plurality of vanes disposed along its periphery against which gas 45 under a predetermined pressure is supplied through an opening 44 provided in the base 31 to thereby rotate the impeller and hence the shaft 35. The gas 45 supplied from the opening 44 is discharged outside via a discharge passageway 46 provided in the base 31. The base 31 has a bore 47 in which a known high voltage generator, not shown, is to be disposed which applies a high electric field to the shaft 35.

It is to be noted that the place where the impeller 43 is mounted is not limited to the aforementioned one. It may be mounted between said bearings 36 and 37 or otherwise between the bearing 37 and the collar 40.

Said hole portion 2 may be made of an insulating material, preferably, a synthetic resin material.

Figs. 10 and-li show a cup 50 to be attached to shaft 35 and effective in use to atomise and propel paint or other coating supplied through the pipe 27.

The cup 50 has a hollow shaft 104 threaded at 105 to be threadedly attached to shaft 35. On shaft 104 is mounted a disc shaped base member 108. This has a plurality of radial bores 112 communicating with the interior of the shaft 104. The bores lead to an annular space 113 between the outside of the disc 108, and generally axial extensions therefrom in both directions, and the inside of a cylindrical member 111 threadedly mounted on the rearward of such extensions and held in place by a screw 114. In use air passed through radial passages 112 (arrows 6) to space 11-3 progresses axially towards a circular outlet 115 between a sharp end 102 of the forward extension from the disc and the end of the cylindrical member 111.

Meanwhile, paint from pipe 27 outlets onto the inside surface 116 of the rearward extension of the disc. This diverges outwardly in the direction of flow. Thus the paint moves to the end 117 of surface 116.

In use, cup 50 is maintained- at high negative voltage. Thus the paint is atomised by electrostatic force and by the air discharged from the slit 115.

Fig. 12 shows the device as in Fig. 2 with the cup 50 in position on the shaft 35, so as to be rotated thereby and receive and discharge air through the passage 34. Pipe 27 is shown larger than in Fig. 2 and it extends into the open end of the rotating cup 50 as shown in Fig. 11. In Fig. 12 is also schematically shown an object 200 to be coated. A high voltage generator 201 is connected between the object and the head at 47, whereby the cup 50 is at negative potential, relative to the object 200. The electric field between cup 50 and object 200 assists in atomising the paint or other coating liquid.

A variety of cups 50 may be available for selective attachment, the selection depending upon the coating task to be performed. The cup 50 rotates with the shaft 35. In order to supply passageway 5 and opening 44 with gas 6 and 45 respectively, a gas pressure supply device installed externally, not shown, is set to its operating state. Said gas 6 then starts to pass to cup 50 from the penetrating hole 34. Said gas flow 45 hits the blades of impeller 43 through opening 44 to start to rotate impeller 43. Therefore, the shaft 35 integral with impeller 43 starts to rotate and, of course, cup 50 starts to rotate around axis 4.

The user then sets the high voltage generator, 201 to its operating state to cause a high electric field to be generated between head portion 3 and cup 50 and an object to be painted. The user also sets a device, not shown, which supplies paint 26 under a predetermined pressure, to its operating state.

However, the paint entrance, that is the inlet 24, is blocked by the needle valve 25, so that paint does not eject from opening 30 of pipe 27. Thus a preparation for painting is completed. Under this condition, in order to paint the object, the user holds the hold portion 2 by one hand, holds a grip 48 of hold portion 2 by the other hand and pulls trigger member 9 in the direction of arrow 49 against the action of the spring 16. The sleeve 14 and hence the needle 28 of the needle valve 25 are then moved also in the direction of arrow 49. As a result, paint 26 blocked at paint inlet 24 is allowed to enter the pipe 27 to thereby to be emitted outside through the opening 30 into the cup 50 so as to perform painting as discussed above.

Figs. 3-9 show an embodiment of an electrostatic paint spray gun apparatus according to this invention. The reference numerals used in Figs. 3-9 are the same as those used in Figs. 1 and 2 to identify similar members or parts. An electrostatic paint spray gun apparatus according to this invention is so sized that the user can carry it by hand to perform painting. Thus minute painting can be performed without difficulty. While various changes and modifications could be conceived by those skilled in the art in accordance with this invention, they are believed to fall in the scope of this invention. In Figs. 3 to 9 head 3 takes a different form, being longer and wider so as partly to surround and shieid cup 50.

Also, valve 24 is mounted on head 3 as shown, bu paint supply from there to the inside of cup 50 is inside head 3.

Claims (6)

1. Apparatus for electrostatically spray coating the surface of an object to be coated with an atomised liquid, including a body part to be held, a head portion on the body part, an atomising device for atomising coating liquid mounted on the head portion, means by which liquid can be supplied to such atomising device and means by which, in use, the device can be connected to a means to create an electric field, such that an electric field is created between the device and an object to be coated.

2. Apparatus according to claim 1 wherein the part of the head portion on which the atomising device is mounted is rotatable to rotate the atomising device.

3. Apparatus according to claim 1 or 2 wherein there is a gas supply path through the head portion to the atomising device.

4. Apparatus according to claim 3 wherein the atomising device has a circular outlet for gas supplied thereto.

5. Apparatus according to claim 1, 2 or 3 wherein the atomising device has an internal surface onto which liquid is applied and from which liquid is ejected in use in atomised form.

6. Spray coating apparatus constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.