WO2004078357A2

WO2004078357A2 - A spray apparatus and method

Info

Publication number: WO2004078357A2
Application number: PCT/ZA2004/000021
Authority: WO
Inventors: Jacobus Gert Van Der Walt; Deon Johan De Beer; Ludrick Johannes Barnard
Original assignee: Jacobus Gert Van Der Walt; Deon Johan De Beer; Ludrick Johannes Barnard
Priority date: 2003-03-04
Filing date: 2004-03-04
Publication date: 2004-09-16
Also published as: WO2004078357A3

Abstract

The invention provides a spray apparatus (10) for applying molten metal material (12) to an object (30) as well as a method of applying a cover (130) to the object which spray apparatus includes a housing (14) which has a sealable spray cavity (16), a pneumatic atomizer (20) in the cavity, feeder means (22) connected to the atomizer to supply the material to the atomizer, which feeder means has a furnace vessel (50) wherein the material is produced and a conduit (58) connected to both the vessel and the atomizer through which the material is delivered to the atomizer, heating means (54, 60) engaged with the feeder means and connectable to a power supply (66), air supply means (66) connected to the atomizer and a filtration device (78, 86, 96) which is in communication with the cavity in order to remove any excess material from the cavity.

Description

A SPRAY APPARATUS AND METHOD

BACKGROUND OF THE INVENTION

[0001] This invention relates to a spray apparatus used for the spraying of molten metal material as well as a method of spraying molten metal material making use of the spray apparatus.

[0002] Skin cancer is treated by radiation with low energy x-rays (100-250kV) or electrons (4-6MeV). Low energy x-rays are produced by a kilovolt unit and electrons with a linear electron accelerator. The size of the electron field is determined by a square or rectangular applicator that attaches to the radiation unit.

[0003] Radiation of a cancerous growth often affects healthy skin between the cancerous growth and the edge of the radiation field. It is known to protect healthy skin from radiation by manufacturing a lead mask which is placed over a part of a patient's anatomy which is to be treated. A cut out, in the form of the cancerous growth, is made in the mask to limit radiation to the area of the cancerous growth.

[0004] The manufacture of the mask is an onerous, time consuming and costly operation. An impression of the affected area on the patient's anatomy is taken by means of plaster of Paris bandages and a female mould is made of the affected area. Once removed the female mould is filled with stone plaster in order to form a male mould of the affected area. The stone plaster is allowed to set and the female mould is removed. A lead sheet with an appropriate thickness, which depends on the intensity of the radiation to be applied, is beaten over the male mould in order for the lead sheet to take the shape of the affected area. The size, shape and location of the cancerous growth is marked on the lead sheet and a saw is used to cut a hole in the lead sheet which corresponds to the cancerous growth. The completed mask is coated with bee's wax to prevent metal to skin contact during radiation. During treatment the mask is placed over the affected area in order for radiation of healthy skin to be restricted.

[0005] The manufacture of the mask requires skill, effort and is time consuming especially where the lead sheet is thicker than 2mm. The cost of the stone plaster is significant and the mask can only be made once the stone plaster has set completely in order to prevent the disintegration of the male mould during the working of the lead sheet over the male mould.

[0006] As the shape and size of each mask are unique each mask must be custom made for the relevant patient. The recycling of used masks requires that the masks must be melted, the molten material rolled into sheets and that the sheets be cut into appropriate sizes. The recovery process of used masks is in itself a lengthy and costly exercise.

SUMMARY OF INVENTION

[0007] This invention aims to provide a spray apparatus with which molten metal material can be sprayed as well as a method of spraying molten metal material which may be used to manufacture a metal mask for use in the radiation of cancerous growths on the skin of a patient.

[0008] The invention provides a spray apparatus for applying molten metal material to an object which includes an atomizer, feeder means connected to the atomizer to supply the material to the atomizer, which feeder means has a furnace member wherein the material is produced and a conduit formation connected to both the furnace member and the atomizer through which the material is delivered to the atomizer, and heating means engaged with the feeder means and connectable to a power supply.

[0009] Preferably the atomizer includes a spray gun which pneumatically atomizes the material.

[0010] The heating means may include a first heating element engaged with the furnace member and a second heating element in the form of a coiled wire resistor which is engaged with the conduit formation.

[0011] The spray apparatus may include a third heating element which is engaged with the atomizer.

[0012] The spray apparatus may include a first heat sensor engaged with the atomizer, a second heat sensor engaged with the conduit formation and a third heat sensor engaged with the furnace member.

[0013] The spray apparatus may include a control circuit which is connected to the heating means and the first, second and third heat sensors.

[0014] Preferably the spray apparatus includes air supply means connected to the atomizer. The air supply means may include a compressor, an air tube which extends between the compressor and the atomizer, an air pressure regulator which is connected to the air tube and a valve connected to the air tube. [0015] The spray apparatus may include a fourth heating element engaged with the air supply means.

[0016] The spray apparatus may include a housing wherein the atomizer is located. The housing may include a sealable cavity formation. The cavity formation may include a drain and an air vent.

[0017] The housing preferably includes a transparent lid member and a switch which is actuated by the lid member.

[0018] The spray apparatus may include a filtration device which is in communication with the cavity formation.

[0019] The filtration device may include a vacuum pump and a boiler. A hose may be attached to the boiler and a circulation pump may be connected to the hose.

[0020] The spray apparatus may include a stand which is insertable into the cavity formation. The stand may include at least one rail with which a runner is movably engaged. The stand may include a rotation means. The rotation means may be a ball and cup joint, alternatively a bearing member.

[0021] The stand may include a holder which may include a platform or a cradle.

[0022] The invention also provides a method of applying a cover to an object which includes the steps of:

a. feeding molten metal material by way of a feeder means to a pneumatic atomizer, which feeder means includes a furnace member wherein the material is produced and a conduit formation connected to both the feeder means and the atomizer through which the material is delivered to the atomizer;

b. heating the material in the feeder means by way of a heating means;

c. atomizing the material by means of the atomizer; and

d. spraying the material onto the object.

[0023] The method may include the step of making a mould of an article and of covering at least part of the mould with the material to form the cover over the mould.

[0024] The method may include the step of allowing the material to solidify on the mould to form the cover. The cover may include a mask. Preferably a spray apparatus for applying molten metal material to an object of the aforementioned kind is used in the method.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention is further described by way of examples with reference to the accompanying drawings in which:

Figure 1 is a perspective top view of a spray apparatus according the invention;

Figure 2 is a schematic representation of the spray apparatus of Figure 1 ;

Figure 3 is a schematic cross-sectional side view of the spray apparatus of Figure 1; and Figures 4A and 4B are perspective views of two alternative stands used in the spray apparatus of Figure 1. DESCRIPTION OF PREFERRED EMBODIMENTS

[0026] Figures 1 , 2 and 3 illustrate a spray apparatus 10 for spraying molten metal material 12 which has a housing 14, an open ended cavity 16 in the housing 14, a transparent lid 18 which is hinged to the housing 14 and which lockingly seals the cavity 16, a pneumatic atomizer 20 in the form of a spray gun located in the cavity 16 and housing 14 and a feeder means or arrangement 22 which is connected to the spray gun 20 and which supplies the material 12 to the spray gun 20.

[0027] The housing 14 has two access openings 24A, B which extend into the cavity 16. A left hand glove 26A is attached to the opening 24A and a right hand glove 26B is attached to the opening 24B in order to allow a user (not shown) to extend his hands and arms at least partially into the cavity 16 through the gloves 26. The user can in this manner handle and manipulate the spray gun 20, a stand 28 and an object 30 inside the cavity 16.

[0028] A compartment 32 is formed in the housing 14 below the cavity 16, which compartment 32 is accessible by way of hinged doors 34. The housing 14 is made in a known manner from metal tubing and sheeting. The cavity 16 is made from galvanized steel and is in the form of a square shaped container with a sump plate 36 at its lower end. The sump plate 36 depends downwardly towards a drain hole 38.

[0029] The lid 18 has a metal frame 40 and a transparent Perspex™ sheet 42 is attached to the frame 40. The lid 18 seals the cavity 16 and is lockable to the housing 14 by way of clamp locks 41. [0030] An air inlet 44 with an air filter 46 is formed through side walls of the housing 14 and cavity 16 and allows airflow from an outside of the housing 14 into the cavity 16.

[0031] The feeder 22 has a furnace or melting vessel 48 which is attached to the housing 14. The vessel 48 has an outer cover 50 which is insulated from an internal holder 52. A first heating element 54 is located inside the holder 52 which is used to melt metal 56 placed in the holder 52. The molten metal material 12 is fed to the spray gun 20 through a flexible metal conduit 58 which extends between the vessel 48 and the spray gun 20. A second heating member 60 in the form of a nickel- chrome resistance wire is coiled around the conduit 58.

[0032] The spray gun 20 is of known construction and has a third heating element 62 to heat the material 12 in the spray gun 20.

[0033] The first, second and third heating elements 54, 60, 62 are connected to a control circuit 64 which is fed with electrical power from a power source 66. Sensors 68A, B, C are respectively attached to the spray gun 20, conduit 58 and vessel 48 and are also connected to the control circuit 64. The control circuit 64 measures the temperature of the material 12 in the vessel 48, conduit 58 and spray gun 20 and depending on requirements increases power supply to the first, second and third heating elements 56, 60, 62. This ensures that the material 12 reaches the spray gun 20 at the correct temperature.

[0034] An air supply arrangement 66 is connected to the spray gun 20. The air supply arrangement 66 consists of an air tube 68 and a compressor 70 which is connected to the air gun 20 by the tube 68. An air pressure regulator 72 of known construction is fitted to the tube 68. A solenoid valve 74 is connected to the tube 68 between the compressor 70 and the spray gun 20. The compressor 70 is connected to the power source 66 and generates compressed air in a known manner which is fed to the spray gun 20.

[0035] A drainage pipe 76 is fixed to the drain hole 38 and extends from the cavity 16 into the compartment 32. A particle trap and boiler 78 sits in the compartment 32 and the drain pipe 76 extends into the boiler 78. The boiler 78 has a cup-shaped body 80 which is sealingly closed by a removable cap 82. A horizontally extending buffer plate 84 extends at least partially across the interior of the body 80. A metal water trap 86 stands inside the body 80 below the buffer plate 84 and the drainage pipe 76 extends into the water trap 86. The body 80 is at least partially filled with an appropriate liquid 88 such as for example water. It is important to note that there is enough water 88 in the body 80 to allow the drainage pipe 76 to extend into the water 88 in the water trap 86. A fourth heating element 89 is attached to the cap 82 and extends into the water 88. The fourth heating element 89 is connected to the power source 66.

[0036] A hose 90 is attached to and extends from the body 80 through the cap 82 and into the cavity 16. A circulation pump 92 is connected to the hose 90 to pump heated water 88 from the body 80 into the cavity 16.

[0037] A ventilation pipe 94 extends from the cap 82 to a vacuum pump 96. The vacuum pump 96 is of conventional design and includes known wet and dry particle filters. The vacuum pump 96 is in communication with the boiler 78 and the cavity 16 and withdraws air from the boiler 78 and expels excess air to atmosphere through an outlet 98.

[0038] A contact switch 100 which is actuated by the lid 18 is attached to the housing 14. The switch 100 is connected to the power source 66 as well as the solenoid valve 74 and the vacuum pump 96. When the lid 18 is closed the switch 100 allows the activation of the vacuum pump 96 and the opening of the solenoid valve 74.

[0039] A stand 28A shown in Figure 4A is used when a small object is sprayed with the material 12 inside the cavity 16 and a stand 28B shown in Figure 4B is used in the cavity 16 when a large object is sprayed with the material 12. The stand 28A has a base 102A with two elongate parallel rails 104A. A runner 106A is movingly engaged with the rails 104A and a rotatable and pivotable holder in the form of a turntable 108 is attached to the runner 106A by way of a universal or ball and cup joint 110. The stand 28B has a base 102B with two elongate parallel rails 104B with which a runner 106B is movably engaged. A holder in the form of a cradle 112 is rotatably attached to the runner 106B by way of a bearing member 114. The cradle 112 has a beam 116 which is attached to the bearing member 114 and two spaced apart arms 118 which are movably connected to the beam 116.

[0040] In use the metal 56 which has a low melting point of between 70°C and 75°C is inserted into the vessel 48. Metal alloy materials such as those sold under the trade names MCP70™, WOOD'S ALLOY™ or FRY'S METAL™ can be used. Depending on the melting point of the metal 56 the control circuit 64 applies an appropriate power supply to the first heating element 54 to melt the metal 56. The sensors 68A, B, C measure the temperature of the material 12 and the measurements are relayed to the control circuit 64. By controlling the power supplied to the first, second and third heating elements 54, 60, 62 the temperature and liquidity of the material 12 are controlled.

[0041] The appropriate stand 28 is inserted into the cavity 16, the object 30 which is to be covered or sprayed with the material 12 is placed on the stand 28 and the lid 18 is closed, sealed and locked. As the lid 18 is closed the contact switch 100 causes the opening of the solenoid valve 74 and activates the vacuum pump 96. Compressed air 124 is supplied to the spray gun 20 from the compressor 70 by way of the tube 68. The pressure of the compressed air 124 is regulated by the regulator 72. In the event that the lid 18 is inadvertently opened the switch 100 causes the solenoid valve 74 to close and the supply of compressed air 124 to the spray gun 20 is interrupted.

[0042] The vacuum pump 96 withdraws air from the boiler 78 by way of the ventilation pipe 94. In order to fill the vacuum created in the boiler 78 air is drawn from the cavity 16 through the drain hole 38 and drain pipe 76 into the boiler 78. Air drawn from the cavity 16 is fed through the water 88 in the water trap 86. The buffer plate 84 prevents water 88 from splashing out of the body 80 into the ventilation pipe 94.

[0043] The vacuum created in the cavity 16 is filled by air which is drawn from atmosphere through the inlet 44 and filter 46 or fed through the spray gun 20 from the compressor 70. [0044] In order to operate the spray gun 20 a user grips the spray gun 20 by means of his hands which are inserted into the cavity 16 through the gloves 26A, B. The spray gun 20 is operated and the material 12 is atomized and sprayed onto the object 30. The number of layers of material 12 sprayed onto the object 30 depends on the required thickness of a metal cover 130 formed over the object 30. The second and third heating elements 60, 62 ensure that the material 12 atomized by the spray gun 20 is in the molten state. Once the material 12 is sprayed onto the object 30 the material 12 cools, solidifies and sets to form the cover 130 on the object 30.

[0045] Once the cover 130 has reached its desired thickness the spray gun 20 is deactivated and set aside and the compressor 70 is switched off. The user removes the object 30 and cover 130 from the holder 28 and activates the circulation pump 92. The fourth heating element 89 heats the water 86 to boiling point and the boiling water 88 is delivered to the cavity 16 by way of the hose 90. The user uses the hose 90 and water 88 to clean all contact surfaces inside the cavity 16. Any excess metal 56 in the cavity 16 is melted by the water 88 and washed away along the sump plate 36 and through the drain hole 38 and drain pipe 76 into the water trap 86. In this manner any material 56 which remains in the cavity 16 is removed, scrubbed and trapped in the water trap 86 and boiler 78. The wet and dry particle filters in the vacuum pump 96 remove any particles which might escape the water trap 86 and boiler 78. The waste metal 56 trapped in the water trap 86, boiler 78 and vacuum pump 96 is recovered for re-use. [0046] Once the cavity 16 is cleaned the lid 18 is opened in order to remove the object 30 and cover 130 from the cavity 16. The cover 130 is removed from the object 30 and processed as required.

[0047] In this example cold compressed air 124 is fed to the spray gun 20 from the compressor 70. It is however possible to attach a fifth heating element 132 in the form of a heat radiator to either the compressor 70 or inline on the tube 68. It is also possible to combine the compressor 70 and vacuum pump 96 in order to form a closed circuit for air movement through the spray apparatus 10.

[0048] An important application of the spray apparatus 10 is the manufacture of metal masks used in radiation treatment of cancerous skin growths. In order to manufacture such a mask a female mould (not shown) is taken of the relevant area of the patient's anatomy. This female mould is made from plaster of Paris bandages.

Once the female mould has set the mould is removed and a male mould made from plaster of Paris is cast inside the female mould. Once set, the male mould is removed and used as the object 30. The cover 130 applied to the male mould 30 is in the form of a metal mask. The mask 130 is removed from the male mould 30 and an appropriately sized and shaped aperture is burnt through the mask 130 through which the cancerous growth can be radiated. As a final step a clear lacquer is applied to the mask 130 to prevent metal to skin contact. The mask 130 is thereafter used in the conventional manner.

[0049] When the mask 130 is discarded the mask 130 is broken into appropriate sized pieces to provide a source of the metal 56 which is re-used. [0050] By limiting the use of hardened settable materials such as stone plaster which takes time to set, the manufacture of the male mould and the production time of the mask 130 are reduced. The use of softer materials for the male mould also results in cost savings. Recovery of the metal 56 from which the mask 130 is made is also improved.

[0051] The material 12 is sprayed onto the object 30 in the sealed cavity 16 in order to prevent accidental inhalation of the atomized material 12 by the user as this could be damaging to the user's health. For the same reason the air and excess material 12 in the cavity 16 are and withdrawn therefrom, and are washed, scrubbed and filtered.

Claims

1. A spray apparatus [10] for applying molten metal material [12] to an object [30] which includes an atomizer [20], feeder means [22] connected to the atomizer to supply the material to the atomizer, which feeder means has a furnace member [50] wherein the material is produced and a conduit formation [58] connected to both the furnace member and the atomizer through which the material is delivered to the atomizer, and heating means [54,60] engaged with the feeder means and connectable to a power supply [66].

2. A spray apparatus according to claim 1 characterised therein that the atomizer includes a spray gun [20].

3. A spray apparatus according to claim 1 or 2 characterised therein that the heating means includes a first heating element [54] engaged with the furnace member.

4. A spray apparatus according to claim 1 , 2 or 3 characterised therein that the heating means includes a second heating element [60] which is engaged with the conduit formation.

5. A spray apparatus according to claim 4 characterised therein that the second heating element includes a coiled wire resistor [60].

6. A spray apparatus according to any one of claims 1 to 5 characterised therein that it includes a third heating element [62] engaged with the atomizer.

7. A spray apparatus according to any one of claims 1 to 6 characterised therein that it includes a first heat sensor (68A) engaged with the atomizer.

8. A spray apparatus according to any one of claims 1 to 7 characterised therein that it includes a second heat sensor [68B] engaged with the conduit formation.

9. A spray apparatus according to any one of claims 1 to 8 characterised therein that it includes a third heat sensor [68C] engaged with the furnace member.

10. A spray apparatus according to any one of claims 1 to 9 characterised therein that it includes a control circuit [64] connected to the heating means.

11. A spray apparatus according to any one of claims 1 to 10 characterised therein that it includes air supply means [66] connected to the atomizer.

12. A spray apparatus according to claim 11 characterised therein that the air supply means includes a compressor [70].

13. A spray apparatus according to claim 12 characterised therein that the air supply means includes an air tube [68] which extends between the compressor and the atomizer.

14. A spray apparatus according to claim 13 characterised therein that the air supply means includes an air pressure regulator [72] which is fitted to the air tube.

15. A spray apparatus according to claim 13 or 14 characterised therein that the air supply means includes a valve [74] connected to the air tube.

16. A spray apparatus according to any one of claims 11 to 15 characterised therein that it includes a fourth heating element [132] engaged with the air supply means.

17. A spray apparatus according to any one of claims 1 to 16 characterised therein that it includes a housing [14] wherein the atomizer is located.

18. A spray apparatus according to claim 17 characterised therein that the housing includes a sealable cavity formation [16].

19. A spray apparatus according to claim 18 characterised therein that the cavity formation includes a drain [38].

20. A spray apparatus according to claim 18 or 19 characterised therein that the cavity formation includes an air vent [44].

21. A spray apparatus according to claim 17, 18 or 19 characterised therein that the housing includes a transparent lid member [18].

22. A spray apparatus according to claim 21 characterised therein that the housing includes a switch [100] which is actuated by the lid member.

23. A spray apparatus according to any one of claims 18 to 22 characterised therein that it includes a filtration device [78,86,96] in communication with the cavity formation.

24. A spray apparatus according to claim 23 characterised therein that the filtration device includes a vacuum pump [96].

25. A spray apparatus according to claim 23 or 24 characterised therein that filtration device includes a water trap [78,86].

26. A spray apparatus according to claim 23, 24 or 25 characterised therein that the filtration device includes a boiler [78].

27. A spray apparatus according to claim 26 characterised therein that it includes a hose [90] attached to the boiler and a circulation pump [92] connected to the hose.

28. A spray apparatus according to any one of claims 18 to 27 characterised therein that it includes a stand [28] which is insertable into the cavity formation.

29. A spray apparatus according to claim 28 characterised therein that the stand includes at least one rail [104] with which a runner [106] is movably engaged.

30. A spray apparatus according to claim 28 or 29 characterised therein that the stand includes a rotation means [110,114].

31. A spray apparatus according to claim 30 characterised therein that the rotation means includes a ball and cup joint [110].

32. A spray apparatus according to claim 30 characterised therein that the rotation means includes a bearing member [114].

33. A spray apparatus according to any one claims 28 to 32 characterised therein that the stand includes a holder [108,118].

34. A spray apparatus according to claim 33 characterised therein that the holder includes a platform [110].

35. A spray apparatus according to claim 33 characterised therein that the holder includes a cradle [118].

36. A method of applying a cover [130] to an object [30] which includes the steps of:

a. feeding molten metal material to a pneumatic atomizer [20] by way of a feeder means [22], which feeder means includes a furnace member [50] wherein the material is produced and a conduit formation [58] connected to both the feeder means and the atomizer through which the material is delivered to the atomizer;

b. heating the material in the feeder means by way of a heating means [54,60,62];

c. atomising the material by means of the atomizer; and

d. spraying the material over the object.

37. A method of applying a cover according to claim 36 characterised therein that it includes the step of making a mould [30] of an article.

38. A method of applying a cover according to claim 36 or 37 characterised therein that it includes the step of covering at least part of the mould with the material to form the cover over the mould.

39. A method of applying a cover according to claim 38 characterised therein that it includes the step of allowing the material to solidify on the mould to form the cover.

40. A method of applying a cover according to claim 38 or 39 characterised therein that the cover includes a mask [130].