WO1993000174A1

WO1993000174A1 - Method and apparatus for drying an article

Info

Publication number: WO1993000174A1
Application number: PCT/AU1992/000318
Authority: WO
Inventors: Frank Anthony Matich; Paul Charles Wong
Original assignee: Frank Anthony Matich
Priority date: 1991-06-27
Filing date: 1992-06-26
Publication date: 1993-01-07

Abstract

Drying apparatus (12) includes a plurality of horizontally extending axles (11) protruding from both sides of a frame (16). An associated electric motor is actuated for rotating axles (11) and consequently helmet shells (1). Following placement of coated helmet shells (1) on apparatus (12), the coating contains a substantial proportion of water and as such is able to move under the influence of gravity. The rotation of helmets shell (1) about a substantially horizontal axis causes the epoxy to move across the surface of the helmet while still being held in contact therewith during drying. The coating will oscillate across the surface of the helmet allowing intimate bonding thereto. Apparatus (35) for both applying and drying helmets (1) includes a generally triangular body (36) supported by three legs (37) for maintaining the helmets at approximately waist height. Body (36) includes a form ply top (38) and an adjacent peripherally extending frame (39). The shafts (40) associated with respective supports (43) are sequentially linked by a continuous chain which is circulated by an appropriate motor to progress supports (43) about the periphery of body (35). Frame (70) located adjacent side (60) supports three uniquely directed spray applicators (71, 72, 73) which selectively expel predetermined quantities of the water based epoxy onto helmets (1) as they progress along side (60). The rate of rotation of helmets (1) along side (60) is increased such that the entire helmet surface is satisfactorily covered with the coating. This increase is achieved by drive means (74) which include an endless belt driven by the continuous chain via a suitable gear train.

Description

Title: "METHOD AND APPARATUS FOR DRYING AN ARTICLE"

TECHNICAL FIELD

The present invention relates to drying an article and in particular to a method and apparatus for drying an article having a coating including a carrier.

This invention has been developed primarily for use with water based coatings applied to helmets or the like, and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use and is also suitable for oil or organic based coatings either applied to helmets or other articles. BACKGROUND ART

Prior helmet coatings have been required to be highly viscous such that when applied to a helmet or other article they will form a thick protective layer. Consequently, the coating will be less likely to intimately bond to the surface of the article resulting in increased likelihood of cracking and chipping.

An operator applying a highly viscous coating will be required to ensure that the coating is uniformly distributed over the whole article as such coatings will not generally sufficiently redistribute themselves. Furthermore, effort will be required to ensure the finish is suitably smooth and appealing.

The application of a number of thinner less viscous coatings is possible, but time consuming. Moreover, the bonding between adjacent layers may not be sufficient to produce a helmet of the desired strength.

If less viscous coatings are applied in such quantities so as to provide a thick coating they will run off the article. Again, problems are associated with obtaining an even distribution of coating over the whole surface, and the quality of the coatings finish. DISCLOSURE OF THE INVENTION

It is an object of the present invention, at least in the preferred embodiment, to overcome or substantially ameliorate at least one of the disadvantages of the prior art.

According to one aspect of the present invention there is provided a method for drying an article having a coating including a carrier, said method including the steps of: (a) applying the coating to the article;

(b) mounting the article for rotation; and,

(c) rotating the article such that the coating oscillates across at least a portion of the article as the carrier is being removed from the coating.

Preferably, air or other gases are passed over the applied coating to facilitate removal of the carrier. More preferably, the air or gas are heated above atmospheric temperature, and more preferable maintain the coating above 25°C.

Preferably also, the article is rotated at a varied rate as the carrier is removed to compensate for changes in viscosity of the coating.

According to a second aspect of the invention there is provided an apparatus for drying an article having a coating including a carrier, the apparatus including: a body for supporting at least one article having the coating applied thereto; retention means projecting from the body for receiving the article for rotation with respect to the body; and drive means for rotating the retention means whereby the coating oscillates across at least a portion of the article as the carrier is being removed from the coating.

Preferably, the body includes a plurality of retention means which are rotated at a variable rate as the carrier is being removed to compensate for changes in viscosity of the coating.

Preferably also, the body also rotatably supports the article during application of the coating. In a preferred form the rate of rotation during the application is greater than the rate of rotation during the subsequent drying.

It is also preferred that the axis of rotation of the retention means is substantially horizontal.

In a preferred embodiment the apparatus includes a plurality of elongate spaced apart cylindrical retention means extending outwardly from and in substantially the same plane as a generally horizontal body. The retention means are interlinked and progress about an endless loop while being axially rotated. Along one portion of the body the coating is applied to the articles, with the speed of rotation of the article during that application being increased so as to minimise the application time.

Preferably, the body is elongate such that an operator is able to remove or place further articles on the retention means while not being exposed to any vapours produced during the application of the coating. According to a third aspect of the invention there is provided a method for applying to an article a coating including a carrier, the method including the steps of: mounting the article for rotation; applying the coating while rotating the article; and rotating the article following the application of the coating such that the coating oscillates across at least a portion of the article as the carrier is being removed from the coating.

Preferably, during and following the application of the coating, the article is rotated at a first and a second rate respectively, where the first rate is greater than the second rate.

More preferably, the article is rotated about a substantially horizontal axis.

In a preferred form, following the application of the coating the article is rotated until sufficient carrier has been removed to effect an intimate bond between the article and coating.

According to a fourth aspect of the invention there is provided apparatus for applying to an article a coating including a carrier, the apparatus including: a body for supporting at least one article; retention means projecting from the body for receiving the article; applicator means for applying the coating to the article; and drive means for rotating the retention means with respect to the body during the application of the coating to the article, wherein following that application the retention means is rotated such that the coating oscillates across at least a portion of the article as the carrier is being removed from the coating. Preferably, the article is rotated at a first and a second rate during and following the application of the coating respectively, wherein the first rate is greater than the second rate. BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a helmet shell;

Figure 2 is a support for the helmet of Figure 1; Figure 3 is one embodiment of an apparatus for rotating a plurality of helmets of Figure 1;

Figure 4 is a schematic perspective view of a second embodiment of an apparatus for rotating a plurality of helmets of Figure 1; and

Figure 5 is a cross section through one of the pogo supports of Figure 4. MODES FOR CARRYING OUT THE INVENTION

Referring to Figure 1 a polystyrene helmet shell 1 to be coated with a water based epoxy includes an inside 2, an outside 3 and an opening 4 for receiving a wearer's head.

Helmet shell 1 is mounted on a support 5, as best shown in Figure 2, such that plate 6 engages the inside 2 of the helmet at or adjacent opening 4. Plate 6 is fixed to inside 2 by adhesive tape or other similar means. Support 5 is hereinafter referred to as a pogo stick.

A coating of water based epoxy is applied to helmet shell 1 in one of many known methods such that outside 3 is completely coated and inside 2 is coated up to the periphery of plate 6. It if preferred that the epoxy is applied by spraying the rotating shell with the epoxy as described hereunder, however, other methods are also suitable.

Following the application of the coating, a shaft 10 extending from plate 6 is inserted into and retained by hollow axle 11 of drying apparatus 12 (as illustrated in Figure 3). Shaft 10 includes pins 15 which releasably engage complementary slots in axle 11. In other embodiments the epoxy is applied following insertion of shaft 10 into axle 11.

Drying apparatus 12 includes a plurality of horizontally extending axles 11 protruding from both sides of a frame 16. An associated electric motor is actuated for rotating axles 11 and consequently helmet shells 1.

Apparatus 12 includes a base 17 and a plurality of heating elements 18 to allow temperature adjustment of the air moving past apparatus 12.

A heat shield 21 prevents unnecessary heating of base 17 and includes a polystyrene insulating section 22 and an overlying aluminium sheet 23. Shield 21 is L-shaped in cross-section to prevent inadvertent contact with heating elements 18.

It is preferred that base 17 is mounted on wheels or is otherwise easily transportable.

Following placement of coated helmet shells 1 on apparatus 12, the coating contains a substantial proportion of water and as such is able to move under the influence of gravity. The rotation of helmet shell 1 about a substantially horizontal axis causes the epoxy to move across the surface of the helmet while still being held in contact therewith during drying.

A coating on any of the helmets in the position shown in Figure 3 will be moving from the front 30 to the back 31 of the helmet. On a rotation of 180° occurring the coating will then tend to move from the back 31 to the front 30. Subsequently, the coating will oscillate across the surface of the helmet allowing intimate bonding thereto. Such oscillation is advantageous especially when a less viscous epoxy is used. That is, the epoxy will be able to progressively fill in any voids in the surface, and closely conform to the surface texture. Furthermore, the coating will substantially uniformly distribute itself over the helmet and provide a smooth finish.

Rotating the helmets rapidly will tend to cause localised build up of the coating around the helmet, while rotating to slowly will allow the coating to drip or fall off the helmet shell. A rate of rotation which avoids the above problems is dependent upon the coating used, and the temperature at which it is applied, as well as the ambient temperature. For the water based epoxies used a rate of rotation of 2 to 7 revolutions per minute was found to be suitable for a drying time of 7 to 15 hours at room temperature.

After a sufficient amount of the carrier has been evaporated from the coating a lacquer is similarly applied and dried. A rate of rotation of 2 to 6 revolutions per minute was found to be suitable as the lacquers available are generally more viscous than the epoxy coating. At room temperature the lacquer takes in the order of two hours to dry sufficiently and is rotated throughout this period.

If required heated air is circulated past apparatus 12 to facilitate the removal of the carrier from the coating. Other preferred embodiments, however, include axles 11 configured to slowly progress around the frame so that respective helmets are in the vicinity of heating elements 18 for a substantially equal time.

A less satisfactory -method for drying would include a reciprocating motion whereby the rotation of the helmets is reversed following the transversal of a predetermined angle. Preferably this angle is greater than 90 ° .

Referring to Figure 4 and Figure 5 there is illustrated an apparatus 35 for applying a coating to a plurality of helmets 1 according to a fourth aspect of the invention. Apparatus 35 includes a generally triangular body 36 supported by three legs 37 for maintaining the helmets at approximately waist height. Body 36 includes a form ply top 38 and an adjacent peripherally extending frame 39.

Referring in particular to Figure 5, a shaft 40 extends from drive means to support at its free end 41 a self lubricating bearing tube 42. An outwardly extending pogo support 43 is mounted for rotation in tube 42 and disposed intermediate top 38 and frame 39. Support 43 includes an axle 45 fixedly engaged at one end 47, by way of a pin 48, with a wheel 49. The periphery of wheel 49 supports a rubber tyre 50 which in turn peripherally abuts the bottom surface 51 of top 38. The second end 52 of axle 45 is held in a fixed relationship with a slotted hollow cylindrical retainer 53 way of a pin 54. Retainer 53 is formed to accept shaft 10 and pins 15 of a pogo stick. If required an elastic band 55 or similar is used to releasably secure shaft 10 within retainer -53.

The upper edge 56 of frame 39 includes a wear strip 57 for preventing any undue frictional contact between tube 42 and frame 39 during relative movement therebetween.

The shafts 40 associated with respective supports 43 are sequentially linked with a continuous chain or belt which is circulated by an appropriate variable speed AC motor or the like to linearly progress supports 43 about the periphery of body 36 in the direction indicated by arrows 80. The abutment between tyre 50 and surface 51 results in the subsequent rotation of retainer 53 in a direction indicated by arrows 81.

The AC motor is selectively actuated by depressing button 82 of control box 83. A wide range of speeds are available such that the rate of progression of supports 43 is able to be easily varied.

The chain linking shafts 40 is inwardly disposed from frame 39 to prevent accidental or inadvertent contact with clothing or limbs of operators. Furthermore, top 38 also functions as a shield against contact with the underlying mechanisms.

Top 38 includes two sides 60 and 61 extending at right angles to each other, and a third side 63 defining a hypotenuse. The length of sides 60, 61 and 62 are approximately 1 metre, 4.05 metres and 4.2 metres respectively. The separate supports 43 are spaced apart such that apparatus 35 will accommodate eighteen such ' holders. However, suitable variation of the dimensions is possible to produce an apparatus which is able to accommodate more or less holders than illustrated. As supports 43 progress along the length of sides 60, 61 and 62 the abutment of tyres 50 a surface 51 causes retainers 53 to rotate. The weight of the pogo stick and associated helmet produce an upward force on wheel 49 and as such improve traction between tyre 50 and surface 51. If, for example, supports 43 are driven linearly along the length of sides 60 to 62 at 22.5mm per second, and tyre 50 has a diameter of 50mm, then retainers 53 will have a rotational speed of 8.6 revolutions per minute. The speed of the AC motor is variable and as such the rotational speed is able to be selected in accordance with the viscosity of the epoxy or other coating being applied to helmets 1. The diameter of wheel 49 and tyre 50 are also able to be selected to achieve a desired rate of rotation.

A frame 70 located adjacent side 60 supports three uniquely directed spray applicators 71, 72 and 73 which selectively expel predetermined quantities of the water based epoxy onto helmets 1 as they progress along side 60. The rate of rotation of helmets 1 along side 60 is increased such that the entire helmet surface is satisfactorily covered with the coating. This increase is achieved by drive means 74 which includes an endless belt driven by the continuous chain via a suitable gear train. However, drive means 74 is alternatively powered by a separate electric motor or the like.

As tyre 50 engages the belt associated with drive means 74, the rotation of support 43 and subsequently helmet 1 is varied accordingly. If required for special applications the rate of rotation during application of the coating is able to be decreased.

In this particular embodiment the rate of rotation along side 60 is variable by either adjusting the speed of progression of supports 43 around body 35 or selecting a different gear ratio.

Frame 70 is ideally separate from apparatus 35 and is generally wall or roof mounted. Applicators 71, 72 and 73, are adjustably mounted to frame 70 for allowing the selective spraying of the epoxy coating in substantially any direction. Frame 70 is linked to a controller 75 and a supply of epoxy 76 via conduits 77 and 78 respectively.

In use, the helmet cores to be coated are presented into engagement with respective pogo sticks, which are in turn inserted into respective supports 43 progressing along side 62. A number of pogo sticks are able to be simultaneously inserted into respective supports, or alternatively, the operation is performed sequentially by a single operator as each support 43 reaches a predetermined point on side 62.

Once a support 43 progresses to side 60, its presence is detected by a sensor which is preferably a pneumatic sensor. The sensor will trigger applicators 71, 72 and 73 to spray the epoxy coating in the desired direction for a predetermined time. Simultaneously, the helmet being sprayed will be rotated at approximately 20 rpm, although this will vary in accordance with the coating being applied.

The rate of rotation of the helmets along side 60 is such that as much epoxy coating as required is applied uniformly on the entire surface area to be coated. However, the rate must be such that the coating will not be removed from the helmet core due to centripetal forces. Furthermore, increasing the rate of rotation allows the required amount of epoxy to be applied in a minimum time as well as reducing the wastage due to overspray.

Once the coating has been applied, helmet 1 is rotated at a decreased rate as it progresses along side 61. At this rate of rotation the coating will move under the influence of gravity and oscillate across a portion of the helmet surface as that portion alternately moves in an upward and downward direction. Given that the length of side 61 is 4.05 metres and the linear rate of travel of supports 43 is 22.5mm per second, three minutes will elapse from the completion of the application of the coating to when the helmet reaches the intersection of sides 61 and 62. It is intended that at this point the pogo sticks will be removed from respective supports 43 and replaced with further pogo sticks supporting helmet cores to be coated. Preferably, both operations are able to be • performed by a single operator.

A substantial amount of carrier is removed during the passage of the coated helmets along side 61. Additional heating means such as heating elements 18 are able to be positioned below and/or above the helmets progressing along this side to facilitate carrier removal.

After the pogo sticks are removed from respective supports 43, they are mounted on apparatus 12 for further drying if necessary. That is, the coating is adequately adhered to the helmet and forms a sufficiently thick semi-liquid covering. The further rotation of the helmet on apparatus 12 ensures that this thickened covering fills any voids on the helmet surface to provide a coating which is intimately engaged with that surface.

Although only one frame 70 is illustrated, for multicoating or multicolour applications two or three such frames having respective applicators and presence sensors are appropriately disposed along side 60 to effect a complete coating of the helmet core in a single pass.

In the described embodiment the control of applicators 71, 72 and 73 is achieved by a single pneumatic timer, which when triggered by the sensor, will cause all three applicators to spray the epoxy solution for a predetermined interval. This configuration is intrinsically safe and offers acceptable accuracy for most applications. The spray intensity and spread patterns of individual applicators is adjustable to enable a more versatile control of the spray. A slightly more sophisticated alternative is for each applicator to include a respective pneumatic timer such that the period of application is able to be separately adjusted.

If even more sophisticated control is necessary an electronic controller is used to provide the timing for the applicators. Delays are able to be included along with one or more spraying intervals. Moreover, electronic control is also able to be implemented using a computer for maximum versatility.

The majority of moving parts associated with apparatus 35 are located under top 38 and inwardly of frame 39 to prevent any overspray from building up and interfering with the normal operation. To further this effect, applicators 70, 71 and 72 are directed at least to some extent outwardly from body 36. Preferably, the end of apparatus 35 adjacent side 60 is located in a suitable booth for providing a capture region for any over spray or vapours.

The elongate nature of apparatus 35 also contributes to the overall safety of the coating operation. That is, the operator inserting and removing pogo sticks from respective supports 43 need not be any closer than approximately four metres from the point of application. Moreover, it is preferred that any electric motors are located near the junction of sides 61 and 62 to maximise their distance from side 60. Such measures are especially relevant where flammable coatings or carriers are being used.

Apparatus 35 has been described only with reference to the continuous rotation of the helmets along side 61. Other embodiments include an alternative rotational mechanism which rotates the helmets through a predetermined angle in an oscillatory motion. That is, rocks the helmets back and forth. Consequently, both the effects of gravity and the inertia of the coating itself will be effective in causing the movement of the coating back and forth across a portion of the helmet.

In large volume applications it is possible to arrange a second apparatus 35 on the first. In this configuration, both apparatus are able to share a single heating unit and supply of epoxy.

Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

CLAIMS : -

1. A method for drying an article having a coating including a carrier, said method including the steps of:

(a) applying the coating to the article;

(b) mounting the article for rotation; and

2. A method according to claim 1 wherein said article is rotated at a varied rate as the carrier is removed to compensate for changes in the viscosity of the coating.

3. A method according to claim 1 wherein air or other gases are passed over the applied coating to facilitate removal of the carrier.

4. A method according to claim 3 wherein said air or gas are heated.

5. A method according to claim 1 wherein said article is rotated about a substantially horizontal axis.

6. A method according to claim 1 wherein said coating oscillates under the influence of gravity.

7. A method according to claim 1 wherein said rotation includes an oscillatory rotation of said article.

8. A method according to claim 7 wherein said coating oscillates under the influence of gravity and its own inertia.

9. An apparatus for drying an article having a coating including a carrier, the apparatus including: a body for supporting at least one article having the coating applied thereto; retention means projecting from the body for receiving the article for rotation with respect to the body; and drive means for rotating the retention means such that the coating oscillates across at least a portion of the article as the carrier is being removed from the coating.

10. Apparatus according to claim 9 including a plurality of retention means.

11. Apparatus according to claim 9 wherein said retention means are rotated at a variable rate as the carrier is being removed.

12. Apparatus according to claim 9 wherein said body includes a substantially vertically extending frame from each side of which project a plurality of retention means.

13. Apparatus according to claim 12 including heating means for facilitating the removal of the carrier.

14. Apparatus according to claim 13 wherein said retention means are progressed about said frame such that respective articles are adjacent said heating means for substantially equal time intervals.

15. Apparatus according to claim 9 wherein the body rotatably supports the article during application of the coating.

16. Apparatus according to claim 15 wherein the rate of rotation during the application is greater than the rate of rotation during the subsequent drying.

17. Apparatus according to claim 9 wherein the axis of rotation of the retention means is substantially horizontal.

18. Apparatus according to claim 9 including a generally horizontal body and a plurality of elongate spaced apart cylindrical retention means extending outwardly from and in substantially the same plane as the body.

19. Apparatus according to claim 18 wherein said retention means are interlinked and progress about an endless loop while being axially rotated.

20. Apparatus according to claim 18 wherein said body is elongate and the coating is applied to the article at one end of said body.

21. A method for applying to an article a coating including a carrier, the method including the steps of: mounting the article for rotation; applying the coating while rotating the article; and rotating the article following the application of the coating such that the coating oscillates across at least a portion of the article as the carrier is being removed from the coating.

22. A method according to claim 21 wherein during and following the application of the coating the article is rotated at a first and a second rate respectively, where the first rate is greater than the second rate.

23. A method according to claim 21 wherein the article is rotated about a substantially horizontal axis.

24. A method according to claim 21 wherein following the application of the coating the article is rotated until sufficient carrier has been removed to effect an intimate bond between the article and coating.

25. A method according to claim 21 wherein said coating oscillates under the influence of gravity.

26. Apparatus for applying to an article a coating including a carrier, the apparatus including: a body for supporting at least one article; retention means projecting from the body for receiving the article; applicator means for applying the coating to the article; and drive means for rotating the retention means with respect to the body during the application of the coating wherein following that application the retention means is rotated such that the coating oscillates across at least a portion of the article as the carrier is being removed from the coating.

27. Apparatus according to claim 26 wherein the article is rotated at a first and a second rate during and following the application of the coating respectively, wherein the first rate is greater than the second rate.

28. Apparatus according to claim 27 wherein said article is rotated about a substantially horizontal axis.

29. Apparatus according to claim 27 including an elongate generally horizontal body about which said retention means progress while being axially rotated.

30. Apparatus according to claim 29 wherein said applicator means is disposed at a first end of said body for applying said coating as said articles progress past that end.

31. Apparatus according to claim 30 wherein articles are removed from and presented into engagement with said retention means at a location spaced apart from said first end by substantially the length of said body.