Device for application of a fluid material

Abstract

 The invention refers to a device for application of a fluid material comprising a housing (34) wherein the material is extruded through an orifice being located at the base part (24) of the housing (34) and being controlled by a valve connected to a feed channel (43) through which the fluid material is being supplied, where the orifice is formed by at least one nozzle piece (26), said nozzle piece (24) is located in the base part (24) of the housing (34) and designed to be used as a valve seat (42) of the material valve and that the valve is positioned directly at the inner side of the nozzle plate (24).

Description

[0001] The invention relates to a device for application of a fluid material comprising a housing wherein the material is extruded through an orifice being located at the base part of the housing and being controlled by a valve connected to a feed channel through which the fluid material is being supplied.

[0002] From EP 1113931 a method and apparatus for applying a viscous or paste material onto a substrate is known which is particularly suitable for applying solder paste onto a board for producing a printed circuit board or for applying an adhesive or other bonding agent to a substrate.

[0003] In DE 4000405 A1 a device for applying a fluid to a moving carrier belt has been described which consists of a tubular distributor and a number of individual flow channels, which together form a multi-jet nozzle. The individual flow channels in the form of capillary tubes are arranged along a generating line parallel to the distributor axis and at a right angle to the distributor axis and are at an equal distance from one another. The individual flow channels project into the inside of the tubular distributor, the two external individual flow channels projecting further into the inside of the distributor than the other individual flow channels.

[0004] From EP 1137492 A1 a device and a method for spray extrusion, more particularly for application of a surface coating "under-up" onto car bodies has been known. The surface coating may be a PVC abrasion protection material, a joint sealant or the like, and is generally a low-viscosity material. The device comprises a source of coating material connected to a nozzle for spraying the material onto an object. Accordingly, the nozzle has a discharge aperture in the form of a pattern of holes, preferably a row of holes.

[0005] As can be seen from the state off the art different techniques for applying liquid for protection of coated surfaces or for masking have been tried since many years back. But so far there has not been found a satisfactory solution. The main problem has been to avoid material droplets outside the coated surface.

[0006] The technique according to EP 1137492 A1 for spray extrusion uses a multi holes nozzle fixed in a separate holder with material channels and a connection to some kind of material valve ex. a normal spray gun. The main problem with this design is that there is a big material volume between the material valve and the fluid nozzle.

[0007] This volume creates a problem with dropping of fluid material when the material valve is closed. The distance between the valve and the nozzle makes it also impossible to achieve the desired distinct stop of material flow when closing the valve.

[0008] Hence it is a main object of the present invention to find a reliable solution which avoids the aforesaid disadvantages with the state of the art and satisfies the requirements mentioned before.

[0009] Further objects may be provisions for preventing the fluid material from clogging and that single droplets created when the material flow is switched off will not hit the surface outside the sprayed area.

[0010] In order to solve the aforementioned problems the invention is characterized in that the orifice is formed by at least one nozzle piece, said nozzle piece is located in the base part of the housing and designed to be used as a valve seat of the material valve and that the valve is positioned directly at the inner side of the nozzle piece.

[0011] According to a preferred embodiment of the invention two nozzle pieces are comprised each operated in the same manner as illustrated in the following.

[0012] In order to have a controlled influx of the fluid material a shut-off member is provided in the material valve which is formed by a counterpiece moving within a valve chamber of the material valve between two final positions in which the material valve is either open or closed.

[0013] Preferably the counterpiece is charged by a spring and controlled by a solenoid valve for opening where the counterpiece is joint to a piston rod which is fixed to a pneumatically operated piston.

[0014] Another embodiment of the invention is characterized in that the nozzle piece is provided with multiple holes being aligned side by side through which the fluid material is extruded.

[0015] According to a preferred embodiment the multiple holes in the nozzle piece are arranged with an interspace of 2.5 mm or less and where each hole in the nozzle piece has a diameter of 1.5 mm or less.

[0016] Advantageously for a controlled inflow of the fluid material the valve chamber is connected to a first channel for supply with fluid material from a reservoir and to a second return channel for spare fluid material hence the material supply channels for supply and return of material allow to circulate the material up to the nozzle piece.

[0017] Furthermore the return channel preferably is controlled by a valve which is positioned within the housing and closes the material return flow when spraying.

[0018] In order to secure a satisfying application of the fluid material in closed position the counterpiece is pressed against the nozzle piece completely overlapping the holes therein and by this action the fluid material directly is prevented from leaking at the nozzle piece when the material valve is closed.

[0019] According to preferred embodiment of the invention the counterpiece is made from a non metallic material, particularly silicon or the like, and shaped as a U-profile in order to improve leak tightness when closing the material valve.

[0020] According to another embodiment of the invention it is equipped with flushing function that allows the nozzle piece to be flushed when the material valve is closed. For this purpose the valve chamber is joint to a first conduit for supply of flushing media.

[0021] A preferred embodiment of the invention is characterized in that a valve for the flushing media is integrated in a piston rod operating the material valve and the means charging the valve for flushing media is formed by a piston being integrated in the same cylinder as the piston for the material valve.

[0022] Besides that a further valve is being provided for compressed air which is likewise integrated in the piston rod operating the material valve and being integrated in the same cylinder as the piston for the material valve.

[0023] It is also important that single droplets created when the material flow is switched off will not hit the surface outside the sprayed area. Hence preferably the conduits for the cleansing or flushing fluid and/or for the compressed air are guided through the counterpiece so that the ends of each of these conduits are directly in front of the nozzle piece.

[0024] A preferred embodiment of the invention is characterized in that a valve for the flushing media is integrated in a piston rod operating the material valve and the means charging the valve for flushing media is formed by a piston being integrated in the same cylinder as the piston for the material valve.

[0025] Besides that a further valve is being provided for compressed air which is likewise integrated in the piston rod operating the material valve and being integrated in the same cylinder as the piston for the material valve.

[0026] In order to exclude residues of fluid material accumulating on the base plate it is equipped with a ventilation bar. This ventilation bar is located outside the base plate and in particular provided for removing fluid drops from the base plate by air flow, where the ventilation bar especially is supplied with compressed air.

[0027] According to another embodiment of the invention at least one, preferably two opposite directed air nozzles for each material nozzle are provided where the air nozzles generate an air flow that blows the droplets being formed when the material valve is closed back to the applied bead.

[0028] In order to control the flow volume and pressure of the air flow the air nozzles are each controlled by a needle valve for the adjustment of the airflow.

[0029] For controlled operation each of the valves for material and flushing agent and each of the air nozzles as well as the return flow valve is operated by a separate solenoid valve that is integrated in the housing.

[0030] The characteristic of the applied material require a precise temperature control, hence it is necessary to circulate the material close to the application nozzle. For this purpose according to another embodiment of the invention a temperature sensor for temperature control and supervision is integrated close to the application nozzles.

[0031] Furthermore in order to be able to control the material flow and to have an automatic supervision of the application process it is also preferred to have a pressure sensor that continuously measures the material pressure as close to the application nozzle as possible. For this purpose according to another embodiment of the invention a pressure sensor for pressure control and supervision is integrated close to the material valve.

[0032] Furthermore according to another embodiment of the invention the size of the applicator for fluid material is limited in order to achieve the channels for supply and return of the fluid material being as short as possible since the material used for the application is fast air drying which requires frequent flushing of the application nozzle between the application cycles to avoid clogging.

[0033] These and further features, improvements, and advantages of the claimed invention are contained in the dependent claims referring to one or more preceding claims.

[0034] In the following description of an example of preferred embodiment essential features, improvements, and advantages of the claimed invention will be illustrated with regard to the figures.

[0035] It is shown in

Fig. 1

a side view from above of a preferred applicator
and

Fig. 2

a side elevation of the dispenser housing of the applicator.

[0036] In Fig. 1 the body of an advanced applicator 10 according to the invention is shown in a side view from above in order to get utmost complete information about the subject matter of the invention. The applicator comprises a mounting flange 12, which is fastened to a support member 18. The support member 18 passes at the other end opposite to the mounting flange 12 into a dispenser 22 which is provided for the application of fluid material. The support member 18 and the dispenser are covered by an enclosure 20.

[0037] The applicator 10 is provided for being mounted to the wrist of the arm of a robot (not shown) and receives a couple of supply lines for fluid material, flushing fluid, and compressed air (all not shown).

[0038] Accordingly the applicator 10 is furnished with a mounting flange 12, a connecting plate 14 provided with junctions 16 for supply of fluid material to be coated, flushing media, compressed air, return flow for excess fluid material, and for lines for supply of the applicator 10 respectively its installed equipment with electric current as well as for the control of it.

[0039] Further the applicator 10 comprises a support member 18 which is covered by an enclosure 20 which extends to the dispenser 22 which comprises the most important parts of the applicator 10.

[0040] Opposite to the enclosure 20 the dispenser 22 is provided with a base plate 24 which is directed to the surface to be coated. In this base plate 24 the outlet for the fluid material is located.

[0041] In Fig. 2 the dispenser 22 is shown in side elevation. It consists essentially of two parts, a lower part comprising the base plate 24 and a valve chamber 32 and an upper part comprising as well means for control of the dispenser 22 as actuators for the valves which control the inflow of fluid material and components for cleansing and drying the dispenser 22.

[0042] The outlet for the fluid material is made from two nozzle pieces 26 of same or different size which are established in the base plate 24 and comprise each at least one row 28 of a couple of holes 30 through which the fluid material is flowing when the applicator is in operation.

[0043] The holes 30 are arranged in a straight manner with a distance between adjacent holes 30 of about 1,5 mm and having a width of about 0,5 mm.

[0044] The lower part of the dispenser 22 comprises the dispenser housing 34 which is formed by the base plate 24, side walls 36 and a closure part 38 and surrounds a valve chamber 40 which is located inside the lower part of the dispenser 22.

[0045] Within the valve chamber 32 for each nozzle piece 26 a counterpiece 40 is being provided which acts as shut-off member for the fluid material supplied to the valve chamber 32. The counterpiece 40 is each adapted to the respective nozzle piece 26 and bordered by a valve seat 42.

[0046] The preferred length of the nozzle piece is about 20 mm to 100 mm. Accordingly the number of holes 30 is provided therein where depending on the kind of fluid material the holes 30 are arranged in one row or more.

[0047] The counterpiece 40 which operates as shut-off member in the valve for fluid material supplied through a supply channel 43 is preferably made from non metallic material with a u-profile shape. In particular each counterpiece is formed as a rectangular bar which is provided on its bottom or closure side with lips a circumferential bead which forms a sealing lip.

[0048] When the counterpiece 40 is pressed towards the nozzle piece 26 the circumferential sealing lip prevents any fluid material from passing through and so drops on the outer surface of the base plate 24 which may be sprayed to the surface to be coated are avoided.

[0049] The counterpieces 40 are actuated each by a hollow piston rod 44 fastened to a piston 46 which is guided in a cylinder 48 that passes through the closure part 38 up to the upper part of the dispenser 22. The upper part of the dispenser 22 contains a first drive 50 for operating the counterpiece 40 by means of the piston 46 and the piston rod 44.

[0050] In the hollow piston rod 46 which is joint to the counterpiece 40 a needle 41 is inserted which is part of a flushing valve 51. This valve provides access of flushing media to the nozzle piece 26 when the piston 52 operating the flushing valve is opened by compressed air from a solenoid valve. The valve for flushing media is closed by the same spring that closes the material valve.

[0051] The flushing media is supplied to both valves trough channel 54.

[0052] Finally outside the bottom of the nozzle pieces 26 formed in the base plate at least on one side a ventilation bar 60 being connected to the air supply is disposed to the base plate. This ventilation bar 60 is equipped with ventilation holes. The air flow passing through these holes takes rests of fluid material e.g. droplets along in order to prevent them from touching the surface to be coated.

[0053] The ventilation holes are arranged in close distance of about 2 mm and have a width of about 1 mm.

Reference Numerals List

10	applicator	43	supply channel for fluid material
12	mounting flange	44	piston
14	connecting plate	46	piston rod
16	junctions	48	cylinder
18	support member	50	first drive
20	enclosure	51	flushing valve
22	dispenser	52	piston for flushing valve
24	base plate	54	flushing media channel
26	nozzle piece	56	needle
28	row	58	third drive
30	hole	60	ventilation bar
32	valve chamber	62	ventilation holes
34	dispenser housing
36	side walls
38	closure part
40	counterpiece
41	needle (of flushing valve 51)
42	valve seat

Claims

1. Device for application of a fluid material comprising a housing wherein the material is extruded through an orifice being located at the base part of the housing and being controlled by a valve connected to a feed channel through which the fluid material is being supplied,
characterized in that
the orifice is formed by at least one nozzle piece, said nozzle piece is located in the base part of the housing and designed to be used as a valve seat of the material valve and that the valve is positioned directly at the inner side of the nozzle plate.

2. Device according to claim 1 characterized in that the shut-off member of the material valve is formed by a counterpiece moving within a valve chamber of the material valve between two final positions in which the material valve is either open or closed.

3. Device according to claim 1 or 2 characterized in that the counterpiece is charged by a spring controlled by a magnetic drive for opening.

4. Device according to claim 3 characterized in that the counterpiece is joint to a piston rod acting as an armature of the magnetic drive

5. Device according to one of the preceding claims characterized in that the nozzle piece is provided with multiple holes being aligned side by side through which the fluid material is extruded.

6. Device according to one of the preceding claims characterized in that in closed position the counterpiece is pressed against the nozzle piece completely overlapping the holes therein.

7. Device according to claim 6 characterized in that the counterpiece pressed directly on the nozzle piece prevents the fluid material from leaking when the material valve is closed.

8. Device according to one of the preceding claims characterized in that the multiple holes in the nozzle piece are arranged with an interspace of 2.5 mm or less and that each hole has a width of 1.5 mm or less.

9. Device according to one of the preceding claims characterized in that the valve chamber is connected to a first channel for supply with fluid material and to a second channel through which spare fluid material is returned.

10. Device according to one of the preceding claims characterized in that a return flow valve is provided within the housing which closes the material return flow when spraying.

11. Device according to one of the preceding claims characterized in that the counterpiece is made from a non metallic material.

12. Device according to one of the preceding claims characterized in that the counterpiece is shaped as a U-profile in order to improve leak tightness when closing the material valve.

13. Device according to one of the preceding claims characterized in that the valve chamber is joint to a first conduit for supply of flushing media that allows the nozzle piece to be flushed when the material valve is closed.

14. Device according to one of the preceding claims characterized in that the valve chamber is joint to a second conduit for supply of pressurized air.

15. Device according to one of the preceding claims characterized in that a valve for the flushing media is integrated in a piston rod operating the material valve and that the piston charging the valve for flushing media is integrated in the same cylinder as the piston for the material valve.

16. Device according to one of the preceding claims characterized in that the base plate is equipped with a ventilation bar supplied with compressed air which bar is located outside the base plate and provided for removing fluid drops from the base plate by air flow.

17. Device according to one of the preceding claims characterized in that at least one, preferably two opposite directed air nozzles for each material nozzle are provided.

18. Device according to one of the preceding claims characterized in that the air nozzles generate an air flow that blows the droplets being formed when the material valve is closed back to the applied bead.

19. Device according to one of the preceding claims characterized in that the air nozzles are each controlled by an needle valve for the adjustment of the airflow.

20. Device according to one of the preceding claims characterized in that each of the valves for material and flushing agent and each of the air nozzles as well as the return flow valve is operated by a separate solenoid valve that is integrated in the housing.

21. Device according to one of the preceding claims characterized in that a temperature sensor for temperature control and supervision is integrated close to the application nozzles.

22. Device according to one of the preceding claims characterized in that a pressure sensor for pressure control and supervision can be integrated close to the material valve.

Drawing