WO2013075703A1

WO2013075703A1 - Method for applying powder by means of a powder spray gun and powder spray gun for carrying out the method

Info

Publication number: WO2013075703A1
Application number: PCT/DE2012/100301
Authority: WO
Inventors: Joachim Pingel
Original assignee: P+S Pulverbeschichtungs- Und Staubfilteranlagen Gmbh
Priority date: 2011-11-23
Filing date: 2012-09-27
Publication date: 2013-05-30
Also published as: EP2782680A1; DE112012004885A5; DE102011055660A1; DE102011055660B4

Abstract

The aim of the invention is to provide a method for applying powder with a powder spray gun and a powder spray gun, in order to achieve a uniform distribution of the powder in the airflow at low flow speed of the powder-air mixture. A uniform powder coating with a high penetration capability even into recesses in the workpiece to be treated shall be rendered possible thereby. Finally, a high degree of separation of the powder shall be achieved. The strand delivery of a powder-air mixture (16) is homogenised in a mixing chamber (4) inside a nozzle body (1) and converted into an airborne delivery. A nozzle cone (5) and distributer cone (13) lead to a further expansion of the powder-air mixture (16). Jet-shaping arrangements (19) on a displaceable sleeve (18) shape the powder-air mixture (16) following exit from the nozzle limiting edge (6). Displacement of the sleeve (18) allows an infinitely variable adjustment of the shape of the powder-air mixture (16), e.g. between a round jet and a flat jet. Conveying air (17), which is supplied via an annular nozzle (7), increases the projection range of the powder-air mixture (16).

Description

The invention relates to a process for applying powder and to a powder spray gun for carrying out the process in powder coating plants.

Nozzles for dispensing a powder-air mixture are known in different designs.

From DE 3546231 AI is a powder - spray member for

Coating of objects known in the electric field. In the region of 30-300 mm in front of the outlet mouth, the flow channel has a constriction in the form of a Venturi nozzle. From 2 to 20 mm in front of the Venturi nozzle, a blowing nozzle is arranged which directs an additional gas flow to the Venturi nozzle. This should be the powder distribution in the air stream

be improved.

According to DE 3412694 AI in addition to the conveying gas and / or the control air in a separate channel introduced a controllable gas flow, ionized before leaving and introduced in approximately radial direction in the region of reduced flow velocity of the expanded conveying gas - mixed powder flow in this.

In EP 1475159B1 a spray device is proposed which, in addition to a spray outlet for spraying the

Coating materials form a shaping air outlet having a plurality of holes for shaping the spray jet and an ambient air passage. Of the

Ambient air passageway is located radially between the spray outlet and the holes for shaping the spray jet, and serves to draw ambient air through them

Flow - suction effect of the spray jet and / or the

Shaping air flow.

The object of the invention is to provide a method for applying powder with a powder spray gun and a powder spray gun to a uniform distribution of the powder in the air stream at low

Flow velocity of the powder - air - mixture too

achieve. This is a uniform powder application with high penetration even in wells on

be treated workpiece. Ultimately, a high degree of separation of the powder should be achieved. Furthermore, the application of the powder - air - mixture on the

Workpiece geometry can be adjusted by a continuous adjustment between round and flat jet geometries. The

The nozzle according to the invention should be usable for different spray guns and inexpensive to produce.

The inventive method provides that the powder - air mixture from the spray gun first flows into the mixing chamber of a nozzle body. In the mixing chamber, the turbulent flow distributes the powder evenly in the air flow, thus homogenizing the powder - air mixture. Subsequently, the powder-air mixture expands in the nozzle cone of the nozzle body and the powder-air- Mixture is machined by a jet forming section assembly of a slidable and rotatable sleeve. All expansion points preferably have sharp edge cross-sections.

According to one embodiment of the method according to claim 2 takes place after the expansion of a shaping of the powder-air mixture by a plugged onto the nozzle body, rotatable and displaceable sleeve with a

Beam shaping section arrangement influencing the

Homogenized Powder - Air - Mixture.

By moving the sleeve with integrated

Beamformabschnittsanordnung changes the shape of the powder - air mixture steplessly from the omnidirectional jet to a flat jet geometry according to the arrangement and

Execution of the beam shaping sections.

According to one embodiment of the method according to claim 3 is carried out after the expansion, a shaping of the powder-air mixture by an attachable to the nozzle sleeve with flow-shaping device influencing the

Homogenized powder - air - mixture by means of an annularly supplied to the nozzle guide air flow. The invention task is further by the provision of a powder spray gun in particular one on the

Powder spray gun attachable nozzle / nozzle body to

Implementation of the method solved.

Within the nozzle body, the inlet channel widens to a mixing chamber via a sharp-edged one Flow separation edge. The cross - sectional widening leads to turbulence, which in turn results in a good mixing and thus a homogenization of the powder - air flow and a

Effecting flight promotion. Subsequently, the powder-air stream enters a nozzle cone with a Ver divider cone.

The homogenization of the powder - air - flow in the

Mixing chamber also reduces the flow rate through the simultaneous expansion, which is beneficial

uniform distribution and precipitation of the powder on the workpiece, especially in wells, affects.

The transition from the material supply to the mixing chamber takes place via a first, sharp-edged flow separation edge. It is similar with the conically expanding deflection collar. At the

Transition from Umlenkbund to a round rod, a second stall edge is provided.

Due to the powder - air mixture flowing over the sharp edges, the turbulences become comparable

Dead water effect on a weir, reinforced. This will be the

Increased homogeneity of the powder - air mixture and improved the quality of the powder application. With an increase in the diameter of the United divider shaft after the Umlenkbund the turbulence can be further enhanced and the expansion can be improved. The conveying air content of the powder - air - mixture can be reduced in this training, without the

Homogenization worsen.

According to one embodiment according to claim 8 of the invention, the trailing edge of Ver divider cone is 1 to 5 mm behind the Nozzle boundary edge back. It has been found that the flow velocity reaches a minimum in this range of distances with high homogeneity of the powder - air mixture.

The slidable sleeve with jet-forming section arrangements on the nozzle body allows regulation of the width of the powder-air mixture. By moving the sleeve away from the spray gun, the powder - air flow can be narrowed and thus the powder application for narrow workpieces can be targeted. The displacement of the sleeve in the opposite direction allows a larger jet angle of the powder - air mixture. The sleeve allows only the change of a round jet. In the case of a sleeve with jet shaping sections, the supernatant by constriction influences the shape of the powder / air mixture. Depending on the arrangement of

Beam shaping sections, the shape of the powder - air mixture is changed. If the sleeve with the jet shaping sections pushed without projection on the nozzle, it produces a

Omnidirectional. If the sleeve is pulled out, the round steel changes steplessly to one, by the arrangement of the

Beam shaping sections, given shape. This one can

Flat jet, a crossing flat jet or other forms achievable by jet necking.

The sleeve may at the exit side according to claim 11 z. B. have a circular arc-shaped cutting profile. By this design of the sleeve, the powder - air - mixture can be applied as a flat jet. The further from the

Spray gun remote beam forming sections of the sleeve cause a narrowing of the spray. By the

Displacement of the sleeve can be done adjusting the beam angle of the flat jet. This makes it possible to coat both narrow workpieces and large areas well.

Of course, sleeves can be different

formed outlet side are attached to the nozzle. Thus, the flat jet can be varied as desired.

According to a further embodiment according to claim 6, an annular nozzle is arranged between the nozzle and the displaceable sleeve, can be supplied through the guide air.

With the guide air, the powder - air mixture formed by the nozzle can be further transported accordingly. This allows a workpiece to be coated with powder at a greater distance. Also for automatically guided

Spray guns have advantages, since the powder-air mixture depth can be controlled by changing the supply air. An embodiment according to claim 10 has a scale graduation on the nozzle body in order to adjust the displaceable sleeve with beam shaping section reproducible.

A rubber ring between the nozzle body and sleeve seals according to claim 7 both units advantageous against currents in the direction of operating personnel.

The nozzle can also be plugged onto the spray gun as a separate component. Thus the nozzles, if necessary with adapter, are Universal together with different spray guns

can be used.

Several embodiments of the invention are in the

Drawings and are described in more detail below.

Show it:

Fig. 1 is a nozzle in longitudinal section with a deferred sleeve with Strahlformabschnittsanordnung, Fig. 2 is a nozzle in longitudinal section with

deferred sleeve with jet forming section arrangement and guiding air inlet,

3 shows a nozzle in side view with deferred sleeve with jet forming section arrangement with extended position for generating a flat jet and on the nozzle body applied setting scale,

3a shows a plan view of the sleeve according to FIG. 3 with a beam shaping section arrangement for producing a medium flat jet, FIG.

4 a nozzle in side view with deferred sleeve with Strahlformabschnittsanordnung in the middle position to produce a flattened round jet and on the

Nozzle body applied setting scale,

4a is a plan view of the sleeve of FIG. 4 with a beam shaping section arrangement for generating a

Flat jet with large jet angle,

5 shows a nozzle in side view with deferred sleeve with Strahlformabschnittsanordnung in the retracted position to produce an omnidirectional and on the nozzle body applied adjustment scale and 5a shows a plan view of the sleeve according to FIG. 5 with a beam shaping section arrangement for producing a crossing flat jet with a large beam angle. The nozzle shown in Fig. 1 in longitudinal section is broken off with a broken on the right side

Nozzle body 1 shown. The nozzle body 1 is designed so that it can be plugged onto the remaining spray gun, not shown.

The nozzle is outward through a hollow cylindrical

Nozzle body 1 completed. Inside the powder - air mixture 16 from the spray gun enters the material supply 2 of the nozzle body 1. The cross section of the inlet channel 2 widens to a mixing chamber 4. In the mixing chamber 4, there is a deflection of the powder - air - mixture 16 and thus to a greater turbulence, mixing and expansion of the powder - air - mixture 16. This results in a

Homogenization of the powder - air - mixture 16 and a

Modification of the conveying mechanism from the strands promotion to flight promotion, i. the color powder is even in the

Distributed air flow and the flow rate of the powder - air - mixture 16 is reduced.

After the mixing chamber 4, a widening closes to

Nozzle cone 5 on. Inside the material supply 2 and the nozzle cone 5 is the United divisional schaff 10 with the

Ver divider cone 13 and the ionizing central electrode 14. It has been found that, as shown in Fig. 1 and Fig. 2, the trailing edge of Ver divider cone 13 one to five millimeters behind the Düsenbegrenzungskante. 6 should stand back for optimal

To achieve powder coating cloud.

In conventional powder nozzles is a high

Flow rate of the powder - air mixture 16 at the nozzle outlet necessary to a good atomization

to reach. As a result, the powder emerges from the nozzle as a jet and not as a cloud. This results in a less good, uneven deposition of the powder on the workpiece and a high loss due to overspray. Due to the lower flow rate is found with the solution found even on heavily structured areas

uniform powder separation with low losses

possible. A nozzle body 1 with improved mixing chamber 4 is, as shown, by a first flow separation edge 3 in

Area of transition from the material supply 2 to

Mixing room 4 reached. The stall 3 causes a Stromungsabr iss and thus leads to stronger

Turbulence. The mixing of the powder-air mixture 16 is thus improved.

Preferably, the flow separation edges 3 is in the cross-sectional widening of the mixing chamber 4. In addition, the deflection collar 11 in conjunction with a second

Stall edge 12 the mixing, the

Homogenization and reduce the flow reduction of the powder-air mixture 16 considerably. The powder - air - mixture 16 can by

Beam shaping section arrangements 19 of the aufsteckkbar s, slidable and rotatable sleeve 18 are narrowed when the sleeve 18 is displaced in the flow direction. Depending on the position of the sleeve 18, a different, stepless shape and widening of the powder-air mixture 16 is possible, for example from the flat jet to the round steel. The

Displacement is easily possible and can also be adapted during the coating process according to the requirements.

One of Fig. 1 outgoing development is in the

Fig. 2 shown. It consists in a sleeve 18 which is longitudinally displaceable on the cylindrical nozzle body 1

Beam shaping section arrangement 19 and with guide air 17th

working. The longitudinally displaceable sleeve 18 with

Beam shaping section 19 makes it possible to vary the shape and expansion of the powder-air mixture 16 emerging from the nozzle body 1. In addition, the supply of guide air 17 is shown. For this purpose, between the nozzle body 1 and sleeve 18, an annular nozzle with a ring 7 is arranged through which additional guide air 17 is supplied. The guide air 17 is supplied via the guide airver partial space 8 of the annular nozzle with Rädelung 7. The additional guide air 17 makes it possible to transport the powder-air mixture 16 on. This allows better coating of removed workpiece parts. This results in advantages in the coating with automatic

Powder guns, usually working on linear

Movement machines are attached. Here is the shape of the Powder - air - mixture 16 to the required

Coating depth adjusted by changing the lead 17. With the help of the guide air 17, the powder - air - mixture 16 can be varied in its expansion or constriction.

The jet-forming section arrangement 19 consists of at least two opposing protrusions with intermediate rectangular or semicircular recesses.

FIG. 3 shows a sleeve 18 with a circular-arc-shaped sleeve ^limiting edge 20 cut from it. As a result, the sleeve 18 becomes a sleeve with beam-shaping section arrangements 19

Beam forming sections, shown in Fig. 3a top and bottom, the outlet side of the sleeve 18 further from the

Nozzle boundary edge 6 of the nozzle body 1 removes and thus narrows the powder - air mixture 16. The two

lateral jet shaping sections of the outlet side of the sleeve 18 are located closer to the nozzle boundary edge 6, which leads to a widening of the powder-air mixture 16. In this way, a powder-air mixture 16 can be produced as a flat jet with the nozzle 1. With a flat jet larger surfaces can be coated very well.

The width of the flat jet can be changed up to the round jet when fully pushing the sleeve 18 on the nozzle. By turning the sleeve 18 can be generated by the straight sleeve termination in its width variable omnidirectional. Thus, the sleeve 18 is universally applicable. Thus, there is the possibility of adjusting the spray to different workpiece geometries.

4 and Fig. 4a show a nozzle 1 and a sleeve 18 with a rectangular cut out sleeve boundary edge 20 in the middle position. For exact adjustment of the

Sleeve displacement is a scale 21 applied to the nozzle body 1. The rectangular section of the

Sleeve limiting edge 20 allows a particularly wide fan-flat jet. The middle sleeve setting causes a wide-spread flattened round jet.

5 and 5a show a nozzle body 1 and a sleeve 18 with quadrangular cutouts

Sleeve limiting edge 20 in fully deferred

Position (no protrusion of the sleeve boundary edge). For exact adjustment of the sleeve displacement, a scale 21 is applied to the nozzle body 1. The quadruple rectangular section of the sleeve boundary edge 20 produces a crossed flat jet. The fully deferred

Sleeve position causes a round jet.

With the nozzle body 1 shown in Figures 1 and 2, a spray process is realized in which the powder-air mixture 16 when entering the nozzle body 1 first passes into a mixing chamber 4 to be homogenized there by a turbulent flow and subsequently in Area of the outlet cone 5 of the nozzle 2 to expand.

The advantage of the method is that the

Homogenization no longer after leaving the Nozzle body 1, but takes place within the nozzle body 1, whereby the flow velocity can be reduced. In conventional powder nozzles is a high

Flow rate of the powder - air mixture 16 necessary to achieve a good distribution of the powder in the powder - air - mixture 16 at the exit from the nozzle. However, this high flow velocity has the consequence that the powder is not uniformly deposited well and, above all, with structured material surfaces in the recessed sections less well. From protruding edges, the powder is blown off. In depressions an air accumulation forms. This results in an unevenly coated workpiece. These disadvantages are avoided due to the lower flow rate of the solution found. This allows workpieces of different geometries

evenly coated with color powder.

An advancement of the procedure becomes by a

Beam forming achieved directly at the exit from the nozzle body 1. A longitudinally displaceable sleeve 18 permits constriction of the powder - air mixture 16. By means of differently arranged jet - forming section arrangements 19 on the exit side of the sleeve 18, the powder - air mixture 16 can e.g. to a flat jet or two intersecting

Flat jets are formed.

The transport of the powder-air mixture 16 can be improved by a nozzle body 1 and sleeve 18 annularly supplied guide air flow 17 while maintaining the mixing of the powder - air - mixture 16. The manifold possibilities of influencing the

Spray jet by varying the speed of the powder - air - mixture 16, speed of the guide air 17 and the beam shape by means of sleeve 18 with

Beam forming section arrangements 19 make it possible to use the invention for various powder guns, powder types, pulverulent powder / air mixture powder proportions, material geometries, jet shapes and coating speeds with the advantages described. It has proven to be advantageous that the speed of the powder-air mixture 16 should be set as low as possible. This minimizes powder losses. By increasing the guide airflow 17, the conveying length of the powder-air mixture 16 can be adapted to a greater distance between the workpiece and the gun.

Compilation of the reference numerals

1 - nozzle body

2 - material feed, entry channel

3 - stall edge 1

4 - mixed

5 - Nozzle cone

6 - Nozzle boundary

7 - Ring nozzle with ringing

8 - Leading air distribution room

9 - rubber ing

10 - Verifiable

11 - deflection collar

12 - stall edge 2

13 - Divider cone

14 - central electrode

15 - Verging edge

16 - powder - air - mixture

17 - Guide air

18 - sleeve

19 - beam shaping section arrangement

20 - sleeve boundary edge

21 - scale

Claims

claims

1. A method for applying powder by means of a

Powder spray gun,

characterized,

a powder / air mixture (16) in a nozzle body (1) first enters a mixing space (4) via a material feed (2), there by a turbulent flow

homogenized and subsequently in the area of

Exit cone (5) of the nozzle body (1) expands.

2. Method for applying powder by means of a

Powder spray gun according to claim 1,

characterized,

in that the powder-air mixture (16), after emerging from the nozzle body (1), is formed by a jet shaping section arrangement (19) of a displaceable and rotatable sleeve (18).

3. Method for applying powder by means of a

Powder spray gun according to one of the preceding claims, characterized in that

that the jet of the powder - air - mixture (16) after

Expansion with a jet forming section arrangement (19) of a displaceable and rotatable sleeve (18) is formed and by means of an outer annular guide air flow (17) is influenced.

4. powder spray gun for carrying out the method according to claim 1,

characterized,

that the nozzle body (1) has a centrally arranged

Material supply (2) has, in turn, in turn, a Ver divider schaff (10) is arranged, the material supply (2) at the end of the United divider shaft (10) in a

Mixing room (4) widens and the transition from the

Material supply (2) to the mixing chamber (4) a first,

has sharp-edged stall edge (3) and the

Ver dividers create (10) conically as a deflection collar (11) widens and the transition from Umlenkbund (11) to a round rod forms a second flow separation edge (12), the round rod into the region of a nozzle cone (5) with a

Nozzle boundary edge (6) extends and then into one

Ver divider cone (13) passes, which ends with its United divider edge (15) in front of the nozzle boundary edge (6) and in the middle towards the outlet opening of the nozzle body (1) a

Central electrode (14) has

5. powder spray gun for carrying out the method according to claim 2,

characterized,

the powder spray gun according to claim 4 on the outer circumference of the nozzle body (1) an attachable, displaceable and rotatable sleeve (18) with a

Beamformabschnittsanordnung (19) has, wherein the

Beam forming section arrangement (19) at the free end of the sleeve

(18) that is in the region of the outlet side of the sleeve (18).

6. powder spray gun for carrying out the method according to claim 3,

characterized,

that between the nozzle body (1) and the sliding and

rotatable sleeve (18) is arranged a guide luftver divider space (8) with an air supply and the guide luftver divider space (8) towards the outlet opening of the nozzle body (1) has a narrow outlet opening between the nozzle body (1) and sleeve (18) for the guide air ( 17).

7. powder spray gun according to claim 5 and 6,

characterized,

that between the nozzle body (1) and the sleeve (18) a

Rubber ring (9) is arranged.

8. powder spray gun according to at least one of claims 5 to 7,

characterized,

in that the divider edge (15) of the divider cone (13) is set back 1 to 5 mm behind the nozzle boundary edge (6).

9. Powder spray gun according to one of claims 5 to 8, d a d e r c h e c e n e c e n e,

that between the displaceable sleeve (18) and the nozzle body (1) an annular nozzle with ringing (7) is arranged, through the guide air (7) can be fed.

10. Powder spray gun according to one of the preceding

Claims 5 to 9,

characterized,

that the nozzle body (1) on its outer side a

annular scale (21).

11. Powder spray gun according to one of the preceding

Claims 5 to 10,

characterized,

in that the beam-shaping section arrangement (19) consists of at least two opposing protrusions with rectangular or semicircular recesses therebetween.