Title:
Spray coating apparatus
United States Patent 2388517


Abstract:
This invention relates to automatic spray coating apparatus and particularly to such apparatus for coating the inside of hollow articles. An important object of the invention is the provision of coating apparatus in which the spray nozzle is moved into the hollow portion of the article to be...



Inventors:
Bailey, Frank A.
Miller, Godfrey A.
Application Number:
US47827643A
Publication Date:
11/06/1945
Filing Date:
03/06/1943
Assignee:
DEVILBISS CO
Primary Class:
Other Classes:
118/323, 118/DIG.3, 239/225.1, 239/227, 239/417.3
International Classes:
B05B13/06
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Description:

This invention relates to automatic spray coating apparatus and particularly to such apparatus for coating the inside of hollow articles. An important object of the invention is the provision of coating apparatus in which the spray nozzle is moved into the hollow portion of the article to be coated. Another object is the provision of such apparatus which includes a spraying nozzle designed to revolve while coating the hollow portion. Another object of the invention is the provision of an inexpensive and simple mechanism for revolving the nozzle and for moving it into and out of the cavity. It has been the general practice previously to revolve the article instead of 16 the nozzle. This invention is particularly advantageous when the article is heavy and cumbersome to handle.

Another object of the invention is the provision of a revolving nozzle in which the inner liq- i0 uid tube is stationary. This is desirable in view of the dificulty that is encountered in securing a leakproof seal at the joint between a revolving liquid tube and an adjoining stationary supply part. Another object of the invention is the provision of means for revolving the nozzle at a constant speed and having it revolve before the spray material is discharged.

Numerous other objects and advantages of the "0 jnvention will be apparent from a study of the following description which taken in connection with the accompanying drawings, discloses several preferred embodiments.

In the drawings: b Fig. 1 is a side elevation of a coating apparatus embodying the present invention; Fig. 2 Is an end view thereof from the left side of Fig. 1; FPig. 3 is a transverse vertical sectional view taken substantially along the lines 3'-3' of Fig. 2; Fig. 4 is a view mainly in section of a governing device for controlling the flow of air to an air motor driving the revolving nozzle; SFig. 5 is a side elevation with parts broken away of an apparatus embodying theĆ½ invention in which a different type of drive is used to revolve the nozzle; Fig. 6 is a left end view of the embodiment M shown in Fig. 5; Fig. 7 is a side elevation of an apparatus embodying the invention in which a third type of revolving mechanism is utilized with the forward end of the nozzle being broken away; - '5 Fig. 8 is a left end view of the embodiment shown in Fig. 7; Fig. 9 is a sectional view showing details of the nozzle of the spray device; and Fig. 10 is a plan view with parts broken away of an apparatus embodying the invention having two spray guns, nozzles of which are rotated by means of a single belt.

Referring particularly to Fig. 1, the article to be coated on the inside is a shell designated by the numeral I; a supporting means 2 may either be in a fixed position or it may be carried by or be a part of a conveyer. The apparatus itself includes a supporting base 3 and an upright supporting structure 4. Rigidly fastened to the structure Is platform 5 which has two parallel sections, one on either side with considerable space between them. Reciprocating table 6, upon which the spray device 7 is supported, is guided in channels 8 between the inside edges of the sections of platform 5 and gib members 9. The gibs are secured to the platform by studs 10.

On the base 3 is mounted an electric motor I1, which, through belt connection 12 and a gear transmission box 13, drives a chain 14 between a sprocket on a shaft of the transmission box and an idler sprocket mounted near the other end of the structure. Fastened to the chain 14 is a connecting rod 15 which has a connection through a stud 16 with the bottom of the table 6 whereby the table is given a reciprocating motion and the spray nozzle IT is moved in and out of the cavity of shell 1.

In the embodiment shown in Fig. 1, the nozzle SI is revolved by means of an air motor 18 through which the outer air tube 19 extends from spray gun 7 to the nozzle II.

The spray gun is an automatic type operated by an air piston, a gun design which is well known I in the art and for that reason is not shown here in greater detail. It has a hose 20 for supplying the liquid coating material and air hose 21 for supplying air for atomization. In the particular embodiment of this invention shown in Fig. 1, i part of the atomization air is utilized for driving the air motor 18. A third hose 22 supplies air for actuating the air piston which controls the liquid discharge valve. Details of the driving connection between the air motor and the nozzle I are shown in Fig. 3.

The body of the air motor is rigidly supported between upright members 23 which are fastened to the table 6 by studs 24. The air motor 18 has a cylindrical casing 25 which is held between the I end plates of the motor by bolts or studs which are not shown. Within the air motor is a revolving rotor 26 which has several radial slots around its periphery, in which ride vanes 27. The outer edges of these bear against the inside wall of cylinder 25 and air against the vanes drives the 6 rotor, as is well understood in the art. The rotor 26 is secured to air tube 19 of the nozzle and the latter therefore revolves with the rotor. Air is supplied to the air motor casing from the spray gun through connecting tube 28. This communicates with the air chamber 29 at the forward end of the gun body.

Through member 30 the gun is connected to the air motor and supported with it by upright members 23. The tube IS revolves in bearing 31. Lubricant filler openings are indicated at 32.

There is provided a dust cap 33 protecting the outer one of the bearings 31. It may be noted that the only rotating parts are the rotor 26 with its vanes 27, the air tube 19 with the inner sections of the bearings 31, and the discharge nozzle 17 carried by tube 19.

Between the inner end of the tube 19 and the surrounding part 30 is a seal 34. The spray liquid tube 35 is connected with the liquid passage of the spray gun through part 36.

The tube 35 carries a liquid discharge tip 38 at its forward end within the discharge nozzle 17 as shown in Fig. 9. The fluid needle valve 37, the movement of which is controlled by the air piston in the spray gun, when in its normal closed position seats in the liquid tip 38, preventing the flow therefrom of any of the liquid coating material. To keep the liquid tip 38 centered within the nozzle 17, a bearing 39 is located between the tubes 35 and 19 as close as possible to the discharge nozzle 17. The bearing must be ported laterally so as not to restrict the flow of air through the tube 19.

In Fig. 4 is illustrated a speed controlled air valve which may be used to govern the revolving speed of the nozzle. In this case an air supply independent of the spray gun is preferable.

As shown this may be supplied through tube 40.

A governor of standard design, indicated at 41, is mounted on and secured to the revolving tube 19 by a collar 41c. A second collar 42 is free to slide longitudinally upon the tube 19. This collar carries a valve, which when drawn to the left by an excessive speed of the tube 19, shuts off the air supply. After passing this valve, when it is in open position, the air goes through chamber 43 and connection 44 to operate the air motor 18.

By control of the piston air reaching the gun through hose 22, the discharge of the material from nozzle 17 may be synchronized with the movement of the nozzle into and from the cavity of shell I. It is found to be desirable to have the nozzle discharge during its withdrawal movement instead of while it is entering such a cavity.

For this work the spray device can have a nozzle that sprays either directly forwardly in a cone pattern, or one that has an angular discharge.

In either case the revolving movement results in a more uniform deposit of the coating upon the surface.

In Figs. 5 and 6 a modification is illustrated in which an electric motor is utilized to drive the revolving nozzle, instead of an air motor as shown in the previous figures. It is believed that less trouble would be encountered with such a drive. The same means for reciprocating the table is utilized. As shown the electric motor may be supported on an upright member 45 which would replace one of the members 23 utilized in the embodiment in Fig. 1.

Bearings for the tube 19 are held by members 23 and 45. In this case the spray gun I is connected to and supported by upright 45. A Vpulley 46 is mounted directly on the tube 19 and is driven by belt 47 from driving pulley 48 mounted on the shaft of the electric motor 49.

A preferred embodiment of the invention is illustrated in Figs. 7 and 8. This is simpler than the other forms in that the same electric motor reciprocates the table and also provides the power for revolving the nozzle. A gear box 50, somewhat similar to that utilized in the other embodiments, is driven by motor l5 through pulleys 52 and 53. Through a similar chain, sprocket, and connecting rod arrangement the table in this embodiment is reciprocated as in the other embodiments. Instead, however, of sliding on flat surfaces, this table 44 is supported on rollers 56 extending inwardly from the inner side edges of the platform sections 57. Side and upward thrust of the table is prevented by the guidance of V rollers 58 which are on bearings supported by blocks 59.

As in the embodiment shown in Fig. 5, pulley 46 is fastened directly to the tube 19. A belt 47 drives this pulley through its riding contact over the roller-like pulley 60 which is an extension of the V pulley 53. The other end of this pulley 60 is supported in bearing member 61 on the other end of the base 3. The nozzle revolving speed is so high compared to its reciprocating speed that it has been found that belt 47 will travel along pulley 60 following the reciprocation movement of the spray device without difficulty.

The lengthwise central opening in the platform 57 provides space for belt 47 to pass on either side of the chain 14.

An idler sprocket for the chain is not shown in this view. It could either be supported from the base as was done in the other embodiments or be supported by table 57. In either .case, of course, the support means must be located beyond the limit of the forward travel of belt 47 as otherwise it would be transverse the path of the belt.

The apparatus shown in Figure 10 has two revolving tubes 19 for coating the interior of two articles simultaneously. As indicated, these may be mounted side by side and on supports 23, and each have a driving pulley 46 mounted upon it as in the modification shown in Figs. 7 and 8. In this case, however, the belt 47 passes across both pulleys before returning to the driving pulley 6$.

Where a double arrangement like this is used, a wider reciprocating table 55 would have to be provided.

While this invention is designed primarily for treating articles that are brought to a fixed position, it also could be adapted for coating articles that are moving on a conveyer. In that case means would be provided for moving the spray device with the conveyer. This might be a platform on rollers which would follow the conveyer just long enough for the spray device to do its work and be moved back to start traveling again in synchronism with the conveyer for treatment of the succeeding article.

As many variations in the invention may suggest themselves to those skilled in the art, without departing from the spirit of the following claims, it should be understood that this Invention is not limited to any specific construction, arrangement or form of parts.

What is claimed is: 1. In an apparatus of the type described, a spray gun, a reciprocable mounting for the spray gun, actuating means for reciprocating the spray gun on the mounting, a rotatable nozzle on the spray gun, a pulley mounted on the nozzle, and a power driven belt running over the pulley acting to rotate the nozzle while the spray gun is being moved.

2. In an apparatus of the type described, a spray coating device, a slidable supporting table for the spray device, motivating means including a connecting rod for reciprocating the table, a rotatable nozzle on the spray device, and driving means traveling with the table for rotating the nozzle.

3. In a coating apparatus, a spray device, an extension nozzle therefor, a relatively stationary liquid tube within the extension nozzle, an outer rotatable air tube forming the principal outside portion of the extension nozzle, a spray discharge tip on the outer end of the air tube, a bearing between the liquid tube and the air tube near their outer ends, and rotating means for the air tube having driving connection with it near its inner end.

4. In a coating apparatus, a spray device, a reciprocable mounting therefor, a rotatable nozzle on the spray device, a pulley associated with the nozzle, a belt over the pulley for rotating the nozzle, and a driving pulley for the belt supported in a stationary position relative to the reciprocable mounting and having an elongated cylindrical belt contacting surface over which the belt may ride laterally in following the movement of the reciprocable mounting.

5. In a coating apparatus, a spray device, a reciprocable mounting therefor, associated sprockets positioned below the mounting, a motor-driven chain running over the sprockets, a connecting rod, the rod connecting the chain and the mounting to give the latter reciprocable motion, a rotatable nozzle on the spray device, a pulley associated with the nozzle, a belt over the pulley for rotating the nozzle, and a driving pulley for the belt supported in a stationary position relative to the reciprocable mounting and having an elongated cylindrical belt contacting surface over which the belt may ride laterally in following the movement of the reciprocable mounting, the diameter of one of the belt pulleys being sufficiently large to permit the belt to travel on either side of the chain.

6. In a coating apparatus, a spray device, a reciprocable mounting therefor, associated sprockets positioned below the mounting, a motordriven chain running over the sprockets, a connecting rod, the rod connecting the chain and the mounting to give the latter reciprocable motion, a rotatable nozzle on the spray device, a pulley associated with the nozzle, a belt over the pulley for rotating the nozzle, and a driving pulley for the belt supported in a stationary position relative to the reciprocable mounting and having an elongated cylindrical belt contacting surface over which the belt may ride laterally in following the movement of the reciprocable mounting, the total of the diameters of the belt pulleys being sufflciently larger than that of the sprockets to permit the belt to travel on either side of the chain.

FRANK A. BAILEY.

GODFREY A. MILER.