DE3525889C1 - Method and device for droplet- or jet-like discharge of a liquid medium - Google Patents

Description

The invention relates to a method for the droplet-shaped or jet-shaped discharge of a liquid medium, in particular an adhesive through a nozzle arrangement, which the medium under a substantially constant pressure is supplied.

It causes considerable difficulty in certain media, either after a certain period of time or change their consistency under the influence of external influences, for example become tough or even solidify, discharged through a nozzle arrangement. This is particularly the case with many adhesives. That has As a result, if there is an interruption due to maintenance measures or production-related interruptions of the discharge block the nozzle passages or movable control elements used to control the discharge and glue valve members. Either the discharge process must not be interrupted in such cases or cumbersome precautions must be taken in the event of an interruption to prevent the discharge device from sticking up.

A method of the type mentioned and a

The distance of the overflow opening (126) from the antechamber device to its implementation is for example merbodenist. from DE-OS 32 22 992 known. In the case of this

The device described in the document is a hot melt adhesive in a gear pump with a gas mixed. The mixture is discharged through a spray gun, with that contained in the hot melt adhesive Pressurized gas foams the adhesive. If the valve on the spray gun is closed, it is possible to that the adhesive material flows back to the pump. The disadvantages described above

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6. Device according to one of claims 3 to 5, characterized in that the passage cross section and / or the geometric shape of the overflow opening (160) is adjustable.

7. Apparatus according to claim 3, characterized in that the overflow opening (42) through at least an elastic membrane (28) which at least partially delimits the antechamber (40) can be shut off is, whose side facing away from the outlet chamber (38) is connected to the compressed gas inlet (58).

8. Device according to one of claims 3 to 7, characterized in that the antechamber (40; cannot be eliminated with this, however, since the nozzle passages located downstream of the valve on the spray gun can stick and clog at least if the discharge process is interrupted for a longer period of time.

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nen. Avoid pouring media into the outlet chamber.

The invention is based on the object of providing a method to enable precise control of the amount

drive of the type mentioned at the beginning, with the chen, which during the lower follow-up pressure of

a blocking of the discharge device in the case of one of the antechambers should pass into the outlet chamber,

The interruption of the discharge process is reliably prevented, if the overflow opening is at least

can be avoided. at least partially have a tear-off edge from one

This object is achieved according to the invention in that the edge is delimited, the tear-off edge of two

that the medium of an antechamber of the nozzle arrangement adjoin one another at an acute angle

voltage is supplied that one can be formed in the flow direction flanks of the edge. This training

The outlet chamber following the antechamber ensures, in particular, that the media are somewhat viscous

mer a pressurized gas is supplied and that the pressure of the for that the liquid flow immediately when increasing

Compressed gas tears off between a crossing of the gas pressure and thus the crossing

medium from the antechamber into the outlet chamber can be precisely determined. The exact shape of the

possible wake pressure and an overflow edge profile depends on the consistency of the medium

of the medium preventing and the medium from the 15 dependent. If necessary, it can also be expedient

Outlet chamber through the nozzle expelling ar-, instead of a sharp tear-off edge a rounded

pressure is changed to provide the one opposite the edge profile or a step. It must

After-run pressure has a higher value. In any case, the medium can be prevented from being due

With the method according to the invention, the medium of the suction effect of the compressed gas jet can be controlled in an uncontrolled manner.

medium without mechanically moving parts from the nozzle anther way from the antechamber into the outlet chamber

Order to be carried out. At the same time you can pull.

the outlet chamber and the outlet chamber through the pressurized gas outlet opening or the outlet channel of the nozzle arrangement different media can be provided that the voltage are constantly blown free, both the passage cross-section of the overflow opening while adjusting the "cycle pauses" in which a is periodic. The embodiment described above see pressure change caused periodic discharge, works with a suitable arrangement of fore chamais also during other interruptions of the exit and exit chambers, even if the carry-over. In the case of a medium that is constantly open, for example when the flow opens. If there is another air inlet sets or solidifies, a pressure gas guide of the invention can be provided that inert protective gas can be used, which through the permanent 30 the overflow opening through at least one of the Vormanente Outflow from the outlet chamber and the chamber at least partially delimiting elastic Nozzle opening the entry of air into the nozzle assembly membrane can be shut off, the outlet chamber of which prevention prevented. A pressurized gas column is connected to the pressurized gas inlet on a simple opposite side Way and with a periodic change of gas is. If the compressed gas is at the holding pressure, then pressure can also be controlled at high frequencies. The membrane closes the inlet of the outlet chamber of the consistency of the medium to be discharged. If, on the other hand, the pressure of the compressed gas can be decreased in this way the shape of the discharge between lowers, the membrane lifts due to its inherent elasticity individual droplets and a practically continuous and due to the medium pressure from the inlet of the Beam can be varied almost at will. The length of time the exit chamber decreases so that medium enters the exit while which the gas pressure can transfer to the follow-up pressure from the chamber. By increasing the pressure is lowered, determines the amount of from the antechamber, the membrane is back against the inlet of the Ausmer medium passing into the outlet chamber. step chamber pressed so that it is closed. During the subsequent pressure increase, the membrane does not have the task of a delivery pressure peak be generated, which is in the exit element, but the task of a locking chamber located medium through the outlet channel 45 Mentes, whereby it is only due to pressure fluctuations the nozzle arrangement is thrown out before the and is not adjusted by mechanically moving parts Pressure drops to a holding pressure that is sufficient to become.

the passage of the medium from the antechamber into the The nozzle arrangement expediently comprises a

To prevent exit chamber. NEN having the outlet channel and thus detachable

The invention also relates to a device for 50 exchangeably arranged nozzle body, so that for

Implementation of the method described above - different media, differently designed nozzle

rens, comprising a housing with at least one nozzle can be used or the nozzles lighter

sensor arrangement and one with the outlet channel that can be cleaned if this is necessary

Nozzle arrangement connectable medium inlet. should be. Depending on the type of medium to be discharged

According to the invention, the device is thereby

indicates that areas in the flow path between the sea with a difficult to wet

To coat the medium inlet and the outlet channel of the nozzle arrangement, in order to prevent the attachment of

tion to avoid at least one antechamber and at least one residue.

Outlet chambers are arranged, which by a min- Further features and advantages of the invention earthed a wall 60 having an overflow opening can be derived from the remaining subclaims and the following from one another are separated, and that the exit-coming description, which is used in connection with the mer with a pressurized gas inlet of the housing in connec- tion drawings the invention is based on Ausführungsdung, which explains with a pressurized gas source with periodic examples. It shows

variable gas pressure is connectable. It can F i g. 1 is a plan view of a first embodiment

several antechambers parallel to one another of an embodiment of the device according to the invention,

be assigned to the chamber of steps. However, F i g. 2 shows a section along line H-II in FIG. 1,

several antechambers one behind the other in the direction of flow. 3 one of the F i g. 2 corresponding section through

be arranged differently in order to avoid the uncontrolled trailing - a second embodiment of the invention,

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F i g. 4 shows a section along line IV-IV in FIG. 3, ben flows out.

F i g. 5 is a plan view of a third embodiment. The device described so far operates as follows of the device according to the invention, to the extent that the diagram in FIG. 7th

F i g. 6 shows a section along line VI-VI in FIG. Reference is made to 5 and, in which on the abscissa the time

F i g. 7 is a pressure-time diagram to illustrate the 5 t and the pressure P of the compressed gas is plotted on the ordinate, the pressure curve of the compressed gas during discharge. After connecting the inflow medium with the device according to the invention. device for the medium to be discharged and the compressed gas in FIGS. 1 and 2 can be seen a generally with 10 line to the inlets 44 and 58 is initially pressure-denoted cuboid housing, which is supplied from a gas with a pressure Po. The compressed gas lower part 12 and an upper part 14 consists. Both parts reach both through the bores 60, 62 into the recesses 12 and 14 are connected to one another by screws 16 below the membrane 28 and through the, with bores 66, 68 being a seal between the parts 12 and 14 , the annular channel 70 and the bore 72 18 is clamped. into the outlet chamber 38. Since the pressurized gas from the

In the lower part 12 an outlet chamber 38 open to the upper part 14 through the outlet channel 36 is formed with a cylindrical recess 20. In this protrudes 15 can chen, on this side of the membrane 28 is a tubular extension 22, the lower pressure from the lower part than in the recess 64, so that the 12 facing side of the upper part 14 protrudes and membrane 28 upwards against the the outlet chamber is formed in one piece with this and its axial 38 surrounding annular surface 74 of the nozzle body 32 ge length is dimensioned such that it is pressed when clamping and thereby separates the outlet chamber 38 from the prechamber 40 of the lower part 12 and upper part 14 between the bottom 20. Now, through the bores 24 of the recess 20 and the axial end surface 26 of the 46, 48, 50, 52, 54 and 56, the medium to be discharged is filled into the tubular extension 22 of an elastic prechamber 40 under pressure, the material being a disk-shaped membrane 28 a supply pressure of the medium compared to the pressure Po which can be tensioned between the circumferential wall of the Ausspa- compressed gas is selected so that no medium between tion 20 and the outer circumferential wall of the tubular 25 of the membrane 28 through into the outlet chamber 38 extension 22 is an annular space 30 formed that can be pressed on. Will now by means of a geeignenahme a heater, for example an electron-th control device of the gas pressure from the time t \ Irish heating coil can be used when it returns lowered to fe to a value P \, so should be the Memerforderlich, the medium to be discharged on bran 28 at least partially in the in the F i g. 2 to maintain a certain processing temperature. 30 set back position so that medium protrudes from the front into the tubular extension 22, a cylindrical chamber 40 can reach the outlet chamber 38. Nozzle body 32 into it, which is coaxial with the tubular. At time h , the pressure of the compressed gas is increased suddenly to a value P _{2 in a threaded hole 34 of the upper part} Po lies. As a result, on the one hand, the membrane 28 is extended in the vicinity of the membrane 28. The nozzle body 35 abruptly against the surface 74 of the nozzle body 32 by 32 has an outlet channel 36 and an outlet chamber 38 that is pressed and thus interrupted the connection between the preceding chamber 40 and the outlet chamber 38 in the direction of the membrane in a funnel-shaped manner . At the same time, the outlet chamber located in the outlet chamber 38 can be completely ejected by the pressurized gas through the media and the quantities to be discharged in adaptation to the amount of medium to be discharged. Be there. The outer diameter of the nozzle body 32 is not only blown free of the outlet chamber 38 and the outlet is smaller than the inner diameter of the tubular outlet channel 36, but there is an extension 22, so that between these two parts one also prevents itself from reaching the outlet opening of the annular antechamber 40 is formed, which can collect with the discharge nozzle body 32 residues of the discharged medium at the inlet chamber 38 through an annular gap 42 in 45. Then the pressure on the connection drops. Value Pz back to the holding pressure Po. This

In the lower part 12 is a first inlet 44 for the connection process can be repeated periodically. If a decision is made to create a supply line for media (not shown), it is not necessary to set the pressure det, through which the medium to be discharged is supplied, at time t ₂ above the value of the holding pressure P ₀ . A different elevation extends from the inlet 44. A simple rectangular control is sufficient for the bores 46, 48, 50 in the lower part 12 and the pressure between the values Po and Pi. Bores 52, 54 and 56 in the upper part 14 are present

Inflow channel, which explained from the upper part 14 into the ringför- device according to the invention, which without eimige Antechamber 40 opens. work ne membrane. In the embodiment according to

In the lower part 12 there is also a second inlet 58 55 F i g. 3 consists of the housing generally designated 76 Connection of a pressurized gas line (not shown) made up of a tubular jacket 78 and three of the rivets formed, of which two bores 60 and 62 to sem enclosed disc-shaped parts, namely a shallow recess 64 in the bottom surface 24 of a bottom part 80, a middle part 82 and a Lead recess 20. The recess 64 is from the cover part 84. In the bottom part 80 are an inlet 86 for The prechamber 40 is separated by the membrane 28. A 60 connection of a supply line for the medium and a further bore 66 in the lower part 12 and a Boh inlet 88 for connecting a compressed gas line 68 in the upper part 14 form a further pressure form. An axially parallel boh gas duct leads from the inlet 86, the one in a formation 90 in the nozzle body 32 in the lower part and one in alignment with it te annular groove 70 opens. This forms a bore 92 in the central part 82 which is coaxial with the axially parallel to an in Outlet channel 36 lying annular channel, of 65 the central part 82 formed annular antechamber at least one axially parallel bore 72 in the tube 94, which with the bore 92 through an overflow body 32 goes out, which is connected to the outlet chamber 38 opening 96. near the end facing the membrane 28 of the same- From the inlet 88 lead a bore 98 in the

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Lower part 80, with its aligned axially parallel holes is functional.

100,102 in the middle part 82 or the upper part 84, a case in which in FIGS. 5 and 6 shown execution radial bore 104 and an axially parallel bore 106 approximately example consists of the generally designated 142 in the upper part 84 to the upper cover surface of the antechamber housing from a plate-shaped upper part 144 and mer94. 5 a plate-shaped lower part 146, which through the antechamber 94 is open towards the upper part 84 and screw bolts 148 are connected to one another. In the surrounds an upper part 144 extending from the bottom of the antechamber 94, an inlet 150 is formed, into which the extension 108, which consists of a first larger-diameter connection piece 152 of a compressed gas hose and an axially larger section 110, is screwed. From the inlet 150 there extends a smaller diameter section 112, io coaxial bore 154 to the lower part 146, which extends from one of the bore 156 aligned with the bore 154 in a recess 114 of the upper part 84. In an axial threaded hole 116, which is set on. In the end section remote from the upper part 144, its inner end in a hemispherical outlet of the bore 156, a nozzle body 158 is inserted,
Chamber 118 passes, a cylindrical nozzle body is next to the bores 154 and 156 is a 120 screwed with an outlet channel 122. The lower edge of the annular surface 124, ie the edge of the annular surface 124 remote from the upper part 144, are the inlet openings 126 from axis transfer opening 160 has a tear-off edge 164, parallel channels 128 are formed which extend down to the bottom of one of the bore 162 obliquely to the tear-off side of the central part 82 and from there through 20 edge 164 rising flank 166 and the wall of the radial connecting channels 130 with an inlet opening bore 156 is formed. In the upper section of the opening 132 of the outlet chamber 118 are connected (see bore 162, an end piece 168 is displaceable he also Fig. 4). The annular prechamber 94 can be adjusted from a further direction and surrounds a closure tongue 172 annular chamber 134 which has a heating element for receiving a heating element. By adjusting the end piece winding (or cooling device) for tempering 168, the height of the gap between the tear-off edge can be used to dispense the medium. With a heater te 164 and the closing tongue 172, the pressure flowing through the bore 100 can also be preheated. The closing tongue 172 has a gas on its underside. On the outer circumferential surface of the impact surface 174, the inclination and shape of which corresponds to the central part 82, an annular insulating layer is also arranged depending on the amount and consistency of the layer 136 to be conveyed for thermal insulation. Medium can vary.

The device described so far works as follows- The lower end of the bore 162 forms a front dimension, again on the pressure-time chamber 176, which has bores 178, 180 and 182 with diagram of FIG. 7 is referred to. an inlet 184 formed in the upper part 144 for The surface of the medium to be discharged is connected to a feed line for the medium to be discharged det is connected to the medium reproduced by the dashed line.

as long as the holding pressure Po prevails. The in Figs. 5 and 6 shown device ar-

At this pressure, compressed gas prevents further work in the same way as the execution

Subsequent flow of liquid from the bore 92 through the form according to FIGS. 2 and 3. As long as the holding pressure

the overflow opening 96 on the one hand and from the front 40 Po there is the surface of the to be discharged

chamber 94 in the inlet openings 124 on the other hand. lowing medium in the antechamber 176 at the level of the in

At the same time, the compressed gas flows through the bores in FIG. 6 shown dashed line. Will the

128 and 130 as well as the outlet chamber 118 and the gas pressure lowered at time ii, so the flows

Outlet channel 122 to the outside. At time ii, medium is now taken from the antechamber 176 over the tear-off edge

If the pressure is reduced to the value Pi, the 45 164 flows into a space 186 which forms the outlet chamber

medium to be discharged from the bore 92 through the above the nozzle arrangement 158 and is

Passage opening 96 into the antechamber 94 and from the closing pressure rise from the pressurized gas

this is expelled through the inlets 126, the channels 128 and 130 into the outlet channel 188 of the nozzle, wherein

the outlet chamber 118, whereby the overflowing at the same time the flow of the medium from the pre

Quantity by the length of the period h - t \ be 50 chamber 176 is interrupted. This arrangement is in

is true. At time £ 2, the pressure is primarily used for the discharge of medium on a

Pressurized gas increased to the value P2. This thinks of the area below the nozzle.

Transfer of the medium from the channel 92 into the front All three embodiments have this in common

chamber 94 and from this in the exit chamber 118 feature that the dosage and discharge of the

stopped abruptly. At the same time, the between 55 medium is solely through a periodic change in the

the inlet openings 126 and the outlet channel 122 pressure of the compressed gas takes place and that the respective

located medium expelled by the pressurized gas. Outlet chamber and the respective outlet channel of the

The pressure then falls back to the nozzle holding pressure through which the compressed gas is always blown free.

Po back. The dosing of the medium is thereby

facilitated by the fact that both at the transfer opening 60 which very easily form a skin or when air is admitted

96 as well as the inlet openings 126 each harden an immediately, the possibility of the discharge of the

tear edge 138 or 140 is formed, which ensures that the medium is interrupted without subsequently affecting the

that the flow of the medium is cut off or sensor arrangement because of blocked passage channels

rips off. The embodiment according to FIGS. 3 and 4 must be replaced or cleaned.

is primarily intended to process material from below to 65

to be discharged from the top of the nozzle. However, this includes 4 sheets of drawings

not from the fact that the device described also with

a certain inclination to the horizontal

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Claims (1)

Patent claims: 1. A method for the droplet-shaped or jet-shaped discharge of a liquid medium, in particular one Glue, through a nozzle arrangement, which the medium under a substantially constant Pressure is supplied, characterized in that the medium is an antechamber of the Nozzle arrangement is supplied that one adjoins the antechamber in the direction of flow A pressurized gas is supplied to the outlet chamber and that the pressure of the pressurized gas is between a a transfer of the medium from the antechamber into the outlet chamber enabling post pressure and one preventing the passage of the medium and the medium from the outlet chamber is changed by the nozzle expelling working pressure, the one compared to the follow-up pressure has higher value. 2. The method according to claim 1, characterized in that in the breaks in which no medium is discharged, the nozzle arrangement is blown free with the compressed gas. 3. Device for performing the method according to PA 1, comprising a housing with at least a nozzle arrangement and a medium inlet connectable to the outlet channel of the nozzle arrangement, characterized in that in the flow path between the medium inlet (44; 86; 184) and the outlet channel (36; 122; 188) of the nozzle arrangement (32; 120; 158) at least one antechamber (40; 94; 176) and at least one outlet chamber (38; 118; 186) are arranged, which through an at least an overflow opening (42; 126; 160) having wall are separated from one another, and that the Exit chamber (38; 118; 186) with a pressurized gas inlet (58; 88; 150) of the housing (10; 76,; 142) is in communication with a source of pressurized gas periodically variable gas pressure can be connected. 4. Apparatus according to claim 3, characterized in that the overflow opening (126; 160) at least is partially delimited by an edge having a tear-off edge (140; 164), the tear-off edge (140; 164) of two flanks of the edge adjoining one another at an acute angle is formed. 5. Apparatus according to claim 3 or 4, characterized in that the antechamber (94) with the medium inlet (86) connecting the inflow channel (92) above the antechamber floor via a Crossing threshold (138) opens into the antechamber (94), the distance between the crossing threshold (138) from the antechamber floor at least equal to that 94) is designed as an annular space, one of which is the nozzle arrangement (32; 120) and the outlet chamber (38; 118) containing approach (108) surrounds. 9. Apparatus according to claim 8, characterized in that the extension (108) has one on the antechamber bottom attaching first section (110) and a smaller diameter compared to this, the Comprises a second section (112) remote from the prechamber bottom, the overflow opening (126) in one the transition surface connecting the two sections (110, 112) to one another is formed. 10. Apparatus according to claim 8, characterized in that the approach from the ceiling of the The prechamber (40) extends as far as the vicinity of the prechamber base and at its that The surface facing the prechamber bottom has the inlet for the outlet chamber (38), the bottom the antechamber (40) is at least partially formed by the elastic membrane (28). 11. Device according to one of claims 3 to 10, characterized in that the nozzle arrangement has a detachably arranged, the outlet channel (36; 122; 188) having nozzle body (32; 120; 158). 12. Device according to one of claims 3 to 11, characterized in that in the housing (10; 76) one heating device for heating at least the antechamber (40; 94) is arranged.