EP0609005A1 - Aircap for spray guns - Google Patents

Aircap for spray guns Download PDF

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Publication number
EP0609005A1
EP0609005A1 EP94300352A EP94300352A EP0609005A1 EP 0609005 A1 EP0609005 A1 EP 0609005A1 EP 94300352 A EP94300352 A EP 94300352A EP 94300352 A EP94300352 A EP 94300352A EP 0609005 A1 EP0609005 A1 EP 0609005A1
Authority
EP
European Patent Office
Prior art keywords
aircap
aperture
spray
fluid
holes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94300352A
Other languages
German (de)
English (en)
French (fr)
Inventor
Neville Thomas Merrie Moles Pettit
Rowland Charles Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ITW Ltd
Original Assignee
ITW Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB939301572A external-priority patent/GB9301572D0/en
Priority claimed from GB939315812A external-priority patent/GB9315812D0/en
Application filed by ITW Ltd filed Critical ITW Ltd
Publication of EP0609005A1 publication Critical patent/EP0609005A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/0081—Apparatus supplied with low pressure gas, e.g. "hvlp"-guns; air supplied by a fan
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
    • B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
    • B05B7/0815—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets with at least one gas jet intersecting a jet constituted by a liquid or a mixture containing a liquid for controlling the shape of the latter

Definitions

  • This invention relates to an improved aircap for spray guns. More particularly the invention provides for a suction or gravity feeding of the fluid, e.g. paint, to be sprayed which produces an even controlled deposition of the paint.
  • the fluid e.g. paint
  • Existing HVLP and high pressure spray guns have a spray nozzle for the fluid to be sprayed encircled by an aircap with horns which supply air at low pressure e.g. 10 lbs. per. sq. inch (0.7 kilograms per square centimetre) to carry the fluid to the article to be sprayed and to disperse it in a controlled spray pattern.
  • An aim of the present invention is to provide a suction aircap which controls the flow of air to the nozzle outlet and overcomes the above disadvantage.
  • Another aim of the present invention is to provide an aircap for spray guns which overcomes the above disadvantage and which facilitates an even paint distribution across the major axis of the pattern, which tapers at the ends to avoid lines being produced on the finished painted surface.
  • an aircap for spray guns having a central aperture through which a nozzle for a fluid to be sprayed projects, an annular part surrounding the aperture, two horns projecting forwardly from the aircap on opposite sides of the aperture, the horns having a pair of spray holes for the supply of air to shape the fluid spray pattern and aligned angular holes at opposite sides of the aperture passing through the aircap to form a secondary shaping of the spray pattern, characterised in that secondary axial holes are drilled through the aircap at opposite sides of the central aperture perpendicular to the axis of the horn holes to modify the even distribution of the fluid across the deposited layer of fluid.
  • the aircap is used on HVLP spray guns which operate on a suction or gravity feeding of the fluid to be sprayed.
  • a single secondary axial hole is drilled at opposite sides of the central aperture.
  • the secondary holes are 1.15 mm in diameter.
  • a suction aircap comprising a wall having a central circular aperture encircling a fluid spray nozzle, wherein the rear of the wall is chamfered at 45° and the width of the chamfer from the rear wall surface to the forward edge of the chamfer is between 0.0015 inch and 0.005 inch (0.038 mm and 0.127 mm).
  • the width is between 0.002 inch and 0.003 inch (0.051 mm and 0.076 mm).
  • an HVLP spray gun having a suction aircap as set forth in the preceding paragraph.
  • the aircap 1 is an annular member having a central aperture 2 and two forwardly extending horns 3 at opposite sides of the aperture 2, with pairs of horn holes 4.
  • a fluid nozzle 5 e.g. for spraying paint is formed to a parallel diameter and projects through the central aperture 2 forming an annulus around the nozzle to form a relatively long parallel bore with a sharp entrance and exit.
  • a pair of holes 6 drilled through the part surrounding the central aperture 2 in a sloping recess 7.
  • the holes 6 are at an angle to the longitudinal axis of the central aperture 2 and effect a secondary shaping of the paint spray pattern.
  • the air jets from the holes 6 impinge on the air jets from the horn holes 4 to improve the straightness of the sides of the pattern and to prevent paint being deposited on the horn faces.
  • Secondary holes 8 measuring 1.15mm in diameter are drilled one at each side of the central aperture 2, perpendicular to the axis of the horn holes 4. These two holes 8 provide jets of air to modify the ends of the spray pattern to create a more even distribution of the paint across the finally deposited layer of paint.
  • the suction aircap 1 is an annular member having a central circular aperture 2 and two forwardly extending horns 3 at opposite sides of the aperture 2, with pairs of horn holes 4.
  • a fluid nozzle 5, e.g. for spraying paint, is formed with a parallel diameter and projects through the central aperture 2 forming an annulus around the nozzle 5 to form a relatively long parallel bore with a sharp entrance and exit.
  • the suction cap 1 has a wall 9 containing the aperture 2.
  • the rear of the wall has a chamfer 10 at 45°, the width of which is between 0.0015 inch to 0.005 inch (0.038 mm and 0.127 mm) and preferably between 0.002 inch and 0.003 inch (0.051 mm and 0.076 mm) as shown by the dimensions.
  • Figure 6 illustrates an elliptically shaped pattern produced by conventional HVLP spray guns which, as a result of its shape, produces an uneven distribution of the deposited paints over the spray area. This becomes more pronounced when the spray gun is turned through 90° to spray vertically downwards as a result of changes in the gravitational forces acting on the paint in a paint container (not shown) attached to the spray gun. The paint flow increases by up to 30% causing changes in the deposited pattern which can result in a banded finish visible on the finished painted article.
  • Figure 7 shows a spray pattern achieved for an HVLP spray gun using the improved suction aircap of the present invention.
  • a spray pattern shown in Fig. 7 can be acheived having both straight sides and even deposition of paint in all orientations of spraying where the changes in gravitational forces result in changes of paint flow.
  • the improvement in the pattern shape is also accompanied by an improved fluid distribution within the deposited pattern which compensates for the increase in fluid flow when the spray gun is spraying in a vertical position, thus preventing banding without the need for the operator to modify the spray gun settings.

Landscapes

  • Nozzles (AREA)
EP94300352A 1993-01-27 1994-01-18 Aircap for spray guns Withdrawn EP0609005A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB9301572 1993-01-27
GB939301572A GB9301572D0 (en) 1993-01-27 1993-01-27 An improved aircap for spray guns
GB939315812A GB9315812D0 (en) 1993-07-30 1993-07-30 Suction aircaps for spray guns
GB9315812 1993-07-30

Publications (1)

Publication Number Publication Date
EP0609005A1 true EP0609005A1 (en) 1994-08-03

Family

ID=26302345

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94300352A Withdrawn EP0609005A1 (en) 1993-01-27 1994-01-18 Aircap for spray guns

Country Status (5)

Country Link
EP (1) EP0609005A1 (no)
JP (1) JPH06238203A (no)
CA (1) CA2113881A1 (no)
FI (1) FI940410A (no)
NO (1) NO940273L (no)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0650766A2 (en) * 1993-10-28 1995-05-03 Ransburg Corporation Suction feed nozzle assembly for HVLP spray gun
EP1166884A1 (en) * 2000-06-28 2002-01-02 Illinois Tool Works Inc. Spray gun air cap

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3656773B2 (ja) * 1996-02-16 2005-06-08 アネスト岩田株式会社 エアスプレーガンの空気キャップ

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB445764A (en) * 1934-12-15 1936-04-17 Devilbiss Co Improvements relating to spray heads
GB623269A (en) * 1941-05-15 1949-05-16 Donald James Peeps Spray nozzle
GB701280A (en) * 1950-10-19 1953-12-23 Vilbiss Co Spray nozzle
EP0456523A2 (en) * 1990-05-11 1991-11-13 Iwata Air Compressor Mfg. Co.,Ltd. Low-pressure paint atomizer-air spray gun

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB445764A (en) * 1934-12-15 1936-04-17 Devilbiss Co Improvements relating to spray heads
GB623269A (en) * 1941-05-15 1949-05-16 Donald James Peeps Spray nozzle
GB701280A (en) * 1950-10-19 1953-12-23 Vilbiss Co Spray nozzle
EP0456523A2 (en) * 1990-05-11 1991-11-13 Iwata Air Compressor Mfg. Co.,Ltd. Low-pressure paint atomizer-air spray gun

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0650766A2 (en) * 1993-10-28 1995-05-03 Ransburg Corporation Suction feed nozzle assembly for HVLP spray gun
EP0650766A3 (en) * 1993-10-28 1995-09-20 Ransburg Corp Suction-fed nozzle for low pressure spray guns.
EP1166884A1 (en) * 2000-06-28 2002-01-02 Illinois Tool Works Inc. Spray gun air cap

Also Published As

Publication number Publication date
FI940410A0 (fi) 1994-01-27
FI940410A (fi) 1994-07-28
CA2113881A1 (en) 1994-07-28
NO940273L (no) 1994-07-28
JPH06238203A (ja) 1994-08-30
NO940273D0 (no) 1994-01-26

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LI LU NL PT SE

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Effective date: 19941215

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Effective date: 19951221

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Effective date: 19960501