EP0747132A2 - Device for applying a pasty fluid - Google Patents

Abstract

The applicator has a material storage chamber (4), which is located between feed connection (2) and ejector nozzle (6), in material flow direction. The chamber has an associated volume adjuster. When the pressure in the incoming material rises, the chamber volume is increased, and decreased, when the pressure drops, to compensate for pressure variations in the material. The volume adjuster has a displacement body. This forms part of an inner chamber wall, and is maintained in a central position by a pretension unit, when the material is at normal pressure. The body is a needle (22), which engages on a seat (24) near the chamber intake.

Description

The invention relates to a device for applying pasty media with a feed connection for the medium to be applied, which is supplied under pressure, and with a storage space from which the medium exits the device from an outlet nozzle.

The pasty media to be applied can be, for example, adhesives which are applied, for example, in the form of strip-shaped coatings in the production of motor vehicles and are used for fastening or attaching components, such as windshields. The paste-like medium to be applied is supplied from a storage container, the pressure which brings about the transport being generated by a pump.

In order to prevent pressure differences occurring due to the pulsation of the pump from becoming noticeable on the pasty medium emerging from the outlet nozzle, which can have the consequence, for example, that the coating to be produced is uneven, it is from the publication DE-GM 86 33 673.8 It is known that the pasty medium brought in by the pump is first fed to a storage space, from which the medium is conducted to the outlet nozzle at a largely constant pressure. The storage space of the known device has a single opening, which is used in succession first as a feed connection for filling the storage space and then subsequently for the medium to exit through an outlet nozzle. The pasty medium is supplied to the storage room in an amount that corresponds to the requirements of a specific order work cycle. Only after the storage room has been filled, the pasty medium can be applied by opening the outlet nozzle. The known device thus operates discontinuously and is complicated in terms of control technology and is therefore complex and expensive.

The invention has for its object to improve a device of the type mentioned in that it works continuously and has a simple structure.

To achieve this object, it is provided according to the invention that the storage space - seen in the material flow direction - is arranged between the feed connection and the outlet nozzle, and the storage space is associated with a volume change device designed in such a way that when the pressure in the medium brought up increases in volume and in the case of a pressure drop in the medium introduced is a volume reduction of the storage space in a pressure fluctuations in the medium introduced compensating manner.

In the invention, the storage space is thus flowed through by the medium, the storage space thus always containing a defined amount of the pasty medium. The device works continuously. When the pressure of the pasty medium fed continuously via the feed connection is increased, the volume of the storage space is increased in such a way that the pressure rise is compensated for, so that the medium emerges from the outlet nozzle with constant pressure regardless of the pressure rise on the feed side of the storage space. If, on the other hand, the pressure of the supplied medium decreases, the volume of the storage space is reduced by the action of the volume changing device, so that the pressure drop in the pasty medium in the region of the outlet nozzle is also compensated.

As a result of the continuous mode of operation of the device according to the invention, there are no negative cycle time influences so that a pasty medium can be applied evenly and in a controlled manner. The device according to the invention can be implemented in a simple manner, which leads to low production costs. Another advantage of the invention is that the pasty medium to be applied always flows through the storage space, ie that no material can settle, which is particularly important in the case of reactive materials. The device according to the invention can be heated according to the properties of the pasty medium or for reasons related to the application / operation. For this purpose, holes for receiving one or more heating cartridges and for receiving a temperature sensor can be provided at certain points of the device.

In an expedient embodiment of the invention, it can be provided that the volume change device has a displacement body which forms an inner wall region of the storage space and is held in a central position under the action of a pretensioning device at normal pressure of the medium. In a preferred embodiment of the invention, the displacement body itself can be designed as a needle which projects into the storage space and is connected to a piston which is movably arranged in a cylinder. The needle itself can in turn be designed to bear against a needle seat arranged in the entrance area of the storage space, so that there is the possibility of being able to close the storage space on the input side by means of the displacement body.

The preload on the displacement body can preferably be applied by a preload spring. The characteristic curve of the spring and a possible adjustability of the preload of the spring are individually matched to possible different material characteristics of the pasty medium (viscosity, flow behavior, thixotropy, compressibility or the like).

In a further embodiment of the invention, it is possible to support the spring preload by means of a pressure applied via a hydraulic medium or a pneumatic medium. A proportional valve is then provided in the supply line of the hydraulic and pneumatic medium on the side of the displacement body facing away from the storage space. However, the additional use of a proportional valve is not fundamentally necessary, but depends on the material data of the pasty medium to be applied. The use of a proportional valve can therefore also be seen as an extension of the spring characteristic of the preload spring.

Fig. 1

eine Ansicht einer Vorrichtung zum Aufbringen pastöser Massen von der Austrittsdüse her gesehen;

Fig. 2

eine Längsschnittdarstellung der Vorrichtung gemäß Fig. 1, wobei der obere und der untere Bereich von Fig. 2 einen Schnitt längs der Linie II-II in Fig. 1, und der hiervon durch die strichpunktierten Linien A und B getrennte Mittelbereich von Fig. 2 einen Schnitt längs der Linie X-X in Fig. 1 zeigt.

The invention is explained in more detail below with reference to the exemplary embodiment shown schematically in the drawing. Show it:

Fig. 1

a view of a device for applying pasty masses seen from the outlet nozzle;

Fig. 2

2, a section along the line II-II in FIG. 1, and the central area of FIG. 2 separated by the dash-dotted lines A and B of FIG. 2, one Section along the line XX in Fig. 1 shows.

The device for applying pasty media has an application head, designated overall by 1. The application head 1 is fed pasty medium to be applied from the direction of arrow C via a feed connection designated 2. The medium then enters through a channel 3 into a storage space 4 and is then fed to a material space 5 which opens into an outlet nozzle denoted by 6, from which the pasty medium can exit in the direction of arrow D when the outlet nozzle is open. The outlet nozzle is controlled by means of a needle 7, which in each case is halved in FIG. 2 in an open position and in a closed position is drawn. In the open position the needle bears the reference number 7 and in the closed position the reference number 7 '. The needle axis is designated 8. Furthermore, a cylinder 9 is provided in the application head 1, in which a piston 10 is displaceably guided. The piston 10 carries the needle 7 on its lower side, as shown in the drawing. The position of the piston when the outlet valve 6 is open is denoted by 10, and the position of the piston when the outlet valve is closed is denoted by 10 '. The piston side opposite the needle 7 is supported by a biasing spring 11, which in its position corresponding to the closed position of the exhaust valve is designated 11 '. The spring 11 can be adjusted in its pretension by means of a schematically represented and designated 12 adjusting screw. A pneumatic or hydraulic medium can be supplied to the piston chambers 13 and 14 lying on both sides of the end faces of the piston 10 via supply or outlet openings 15 and 16. The supply or discharge of the hydraulic or pneumatic medium takes place via lines 17 and 18, which lead to a control valve designated 19. A proportional valve bears the reference number 20. As can be seen, by acting on either the piston chamber 13 or the piston chamber 14, a movement of the piston 10 can take place and thus an opening or closing of the outlet valve 6 can be effected.

A volume change device, designated overall by 21, is assigned to the storage space 4. The volume change device has a displacement body designed as a needle 22, which projects into the displacement space 4 with its end region shown on the right in the drawing. The needle 22 is shown divided, 22 being a central position of the needle and 22 'a position in which an end region 23 bears against a needle seat 24 provided at the left end of the channel 3. In its end region facing away from the storage space 4, the needle 22 is attached to a piston 25, which in turn is divided is shown. In the position 22 'of the needle which closes the channel 3, the piston bears the reference number 25' in its corresponding position. The piston 25 is biased by a spring designated by 26, which bears the reference number 26 'in its position corresponding to the position 22' of the needle. The spring 26 is adjustable in its pretension via an adjusting screw 27. A pneumatic or hydraulic medium can be fed to a piston chamber 28 via a feed opening 29. The medium can also be drained through the same opening. The opening 29 is connected to the line 18 via a line 30 and to the line 17 via a line 31. A proportional valve, designated 32, is provided in line 30. The piston chamber 33 opposite the piston chamber 28 communicates with the atmosphere via a bore 34.

The device works as follows:
In the rest position, the needle forming the displacement body bears against the needle seat 24 in its position 22 ', as a result of which the storage space 4 is blocked off from a material inflow from the direction of the arrow C. The needle is held in its position 22 'by the action of a pneumatic or hydraulic medium (gas, air, liquid) which is fed to the piston chamber 28 through the opening 29.

In the rest position, the other piston also presses in its position 10 'via the associated needle in its position 7' onto the needle seat of the outlet nozzle 6, designated 35, and thus closes the outlet. This piston is also held in position 10 'by a pneumatic or hydraulic locking energy (gas, air, liquid) which enters the piston chamber 9 through the opening 15.

In the closed state described above, the pressure prevailing in the supply connection 2 of the pasty medium supplied via a pressure pump (= dynamic pressure) is considerable greater than the pressure of the pasty medium located in the area between the supply connection and the outlet nozzle 6.

At the beginning of the application process of the pasty medium, the piston chamber 28 is emptied via the connection 29. Since the piston chamber 33 is connected to the atmosphere via the bore 34, ambient air can flow into the piston chamber 23 when the piston 25 moves to the left in accordance with the drawing. Simultaneously with this or, depending on the material, with a time delay, the needle 7 is brought into the open position by emptying the chamber 13 via the connection 15 and venting the chamber 14 via the connection 16. The connections 15 and 16 can be actuated via the proportional valve 20 or via a four-way valve, an adjustment being possible by actuating the adjusting screw 12 and / or by adjusting an orifice 36 in the area of the outlet nozzle 6.

The device can also be used to produce different cross-sections of the medium to be applied or even identical or intentionally different cross-sections of the medium to be applied with different movement speeds of the outlet nozzle above the corresponding object with uniform movement. Information about the speed of movement of the object relative to the device (or vice versa) can be supplied to the device via analog inputs, for example.

Due to the effect of the dynamic pressure in the area of the feed opening 2, the needle 22 is shifted from its position 22 'to the left, as shown in the drawing, counter to the pressure of the spring 26. This increases the volume of the storage space 4, which reduces the pressure in the pantry 4 has the consequence. In this way, excess material resulting from the dynamic pressure discharge in the storage chamber 4 is compensated.

During the application of pasty media through the outlet nozzle 6, new pasty medium is continuously fed to the feed connection 2 via a pump (not shown). Pressure fluctuations caused by the pulsation of the pump are compensated for in the device according to the invention by the fact that the volume change device, designated overall by 21, which assumes a central position at "normal pressure" of the pasty medium, which corresponds approximately to the position shown in FIG. 2 a pressure increase of the pasty medium brought in from the direction of arrow C is moved to the left against the biasing force of the spring 26, which results in an increase in volume of the storage space 4 and thus a corresponding pressure drop. In a corresponding manner, the needle 22 moves to the right when the pressure is reduced, which leads to a reduction in the volume of the storage space 4 and a corresponding increase in pressure. In this way, the application process of the pasty medium is brought into a "dynamic balance". The process of increasing or decreasing the volume is basically comparable to opening the outlet valve 6, but the pressure difference is much smaller in each case.

In the exemplary embodiment shown, the “middle position” set at normal pressure of the supplied medium is determined by the biasing force of the spring 26. In addition to this, this pretensioning force can be increased by a hydraulic or pneumatic medium, which can be supplied to the piston chamber 28 via the connection 26 and whose pretensioning force can be set via the proportional valve 32. As already mentioned, the additional use of a proportional valve is not absolutely necessary.

The application process of pasty medium is ended in that the control valve 19 moves the piston 10 into the position labeled 10 'and the piston 25 into the position labeled 25' Position are moved. The movement can take place simultaneously or with a time delay. As a result, the needles 7 and 22 are pressed against their needle seats 36 and 24, respectively.

Claims (8)

Device for applying pasty media with a feed connection for the medium to be applied, which is supplied under pressure, and with a storage space from which the medium exits the device through an outlet nozzle, characterized in that the storage space (4) - viewed in the direction of material flow - between the Supply port (2) and the outlet nozzle (6) is arranged, and the storage space (4) is associated with a volume change device (21) designed in such a way that when the pressure in the supplied medium increases, the volume increases and when the pressure decreases in the supplied medium, the volume decreases Storage space in a pressure fluctuations in the medium introduced compensating manner. Apparatus according to claim 1, characterized in that the volume changing device (21) has a displacement body which forms an inner wall region of the storage space (4) and is held in a central position under the action of a pretensioning device at normal pressure of the medium. Apparatus according to claim 2, characterized in that the displacement body is designed as a needle (22) which is connected to a piston (25) which is movably arranged in a cylinder and projects into the storage space (4). Apparatus according to claim 3, characterized in that the needle (22) is designed to bear against a needle seat (24) arranged in the entrance area of the storage space (4). Device according to one of claims 2 to 4, characterized in that the bias is applied by a biasing spring (26). Device according to one of claims 2 to 5, characterized in that the bias is applied by a hydraulic medium. Device according to one of claims 2 to 5, characterized in that the pretension is applied by a pneumatic medium. Apparatus according to claim 6 or 7, characterized in that a proportional valve (32) is provided in the feed line (30) for the hydraulic medium or for the pneumatic medium for supply to the side of the displacement body facing away from the storage space (4).

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