EP1153664A2 - Device for spraying workpieces with liquids - Google Patents

Abstract

An air shaping nozzle component (156) is installed around the atomiser and is connected to an air source. The air shaping nozzle component creates a shaped air flow which is orientated so that it meets with the droplet stream produced through the nozzle body (122) and atomiser and which has a conical outer contour. The air shaping nozzle component has two air shaping channels which lie opposite each other in relation to the axis of the metering hole (128).

Description

The invention relates to a device for spraying with liquids according to the preamble of Claim 1.

Atomizing heads for liquids can be found in different Way as atomizing heads in the market spray guns.

Such atomizing heads generally produce one rotationally symmetrical droplet cone with a given Opening angle. Would you like with such atomizing heads Workpieces within a precisely specified Edge contour, which is often rectangular or polygonal, with spray a liquid, so you have to open the angle of the droplet cone small and with a moving one Drive the atomizing head over the area to be sprayed, which is time consuming and high in automation Effort for a coordinate drive of the atomizing head and makes it necessary to control it. You work with a larger number according to the surface area to be covered distributed atomizing heads, this means given the cost of an atomizing head and the associated installation, in turn, a considerable one Expenditure. In addition, the conversion of a corresponding one Arrangement of fixed atomizing heads from one surface geometry to be sprayed onto another with many mechanical changes and a lot of time.

A device for spraying workpieces, as in Oberbegirff of claim 1 is indicated by the Invention be further developed so that the switching on and off of the atomizing heads depending on the position of the workpiece with respect to the atomizing head arrangement he follows.

According to the invention, this object is achieved by a device with the features specified in claim 1.

Advantageous developments of the invention are the subject of subclaims.

With a device according to claim 2 you get on in a simple manner, only partially in the desired manner Spraying the workpiece surfaces.

With the development of the invention according to claim 3 ensures that the pro on the workpiece surface Area unit applied amount of liquid independently of which is the speed at which the workpiece on the Atomizing head assembly moves past becomes.

It is automatic in a device according to claim 4 taking into account that the atomizing heads dispensed droplet cone a certain period of time need to reach the workpiece surface.

The development of the invention according to claim 5 is suitable especially for spraying workpiece surfaces with highly viscous liquids. It is guaranteed that the viscosity of these liquids does not change Cooling in the leading to the atomizing heads Feed lines increased.

In a device according to claim 6, you can also Width of the output from the atomizing heads Droplet cone depending on the position of the workpiece to control the atomizing head assembly.

The development of the invention according to claim 7 is also with regard to uniform spraying of a workpiece surface with a highly viscous liquid from Advantage.

Figur 1:

ein schematisches Blockschaltbild einer Straße zum Tiefziehen von Blechtafeln, welche mit einer Einrichtung zum Besprühen ausgewählter Oberflächenabschnitte der Blechtafeln versehen ist;

Figur 2:

eine schematische Darstellung einer Zerstäubungskopfanordnung der in Figur 1 gezeigten Einrichtung zum Besprühen von Teilbereichen der Blechplatten sowie einer zugeordneten Steuer- und Versorgungseinheit;

Figur 3:

einen axialen Schnitt durch einen der Zerstäubungsköpfe, die in Figur 2 nur schematisch wiedergegeben sind;

Figur 4:

einen axialen Schnitt durch den in Figur 3 gezeigten Zerstäubungskopf in einer zur Zeichenebene von Figur 3 senkrechten Schnittebene;

Figur 5:

eine axiale Aufsicht auf das freie Ende eines Formluft-Düsenkörpers des in den Figuren 3 und 4 gezeigten Zerstäubungskopfes;

Figur 6:

einen axialen Schnitt durch den in Figur 5 gezeigten Formluft-Düsenkörper längs der dortigen Schnittlinie VI - VI;

Figur 7:

eine seitliche Ansicht des Formluft-Düsenkörpers in Figur 6 von links gesehen;

Figur 8:

eine seitliche Ansicht eines Zerstäubungsluft-Düsenkörpers des in den Figuren 2 und 4 gezeigten Zerstäubungskopfes;

Figur 9:

eine schematische Darstellung eines abgewandelten Zerstäubungskopfes; und

Figur 10:

das Schaltbild eines Steuerkreises zum selektiven Aktivieren von Zerstäubungsköpfen in Abhängigkeit von der Stellung eines Werkstückes.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawing. In this show:

Figure 1:

a schematic block diagram of a street for deep drawing of metal sheets, which is provided with a device for spraying selected surface sections of the metal sheets;

Figure 2:

a schematic representation of an atomizing head arrangement of the device shown in FIG. 1 for spraying partial areas of the sheet metal plates and an associated control and supply unit;

Figure 3:

an axial section through one of the atomizing heads, which are shown only schematically in Figure 2;

Figure 4:

an axial section through the atomization head shown in Figure 3 in a section plane perpendicular to the plane of Figure 3;

Figure 5:

an axial view of the free end of a shaped air nozzle body of the atomizing head shown in Figures 3 and 4;

Figure 6:

an axial section through the molded air nozzle body shown in Figure 5 along the section line VI - VI;

Figure 7:

a side view of the molded air nozzle body in Figure 6 seen from the left;

Figure 8:

a side view of an atomizing air nozzle body of the atomizing head shown in Figures 2 and 4;

Figure 9:

a schematic representation of a modified atomizing head; and

Figure 10:

the circuit diagram of a control circuit for the selective activation of atomizing heads depending on the position of a workpiece.

In FIG. 1 there is 10 a stack of individual metal sheets Designated 12. The metal sheets 12 are through a first transport system indicated only schematically 14 brought into a waiting position. The one in the waiting position lying sheet metal is transported by another transport system 16 to a lower mold 18 of a deep-drawing tool placed. An upper mold 20 of the deep-drawing tool is also indicated only schematically by one Press drive 22 moves.

When deep drawing the metal sheets 12 between the lower mold 18 and upper form 20 are the different areas the sheet 12 is stressed differently. In the side walls of the trough-shaped recess 24 the lower mold 18 or the complementary stamp section 26 of the top mold needs the most deformation work be performed. In these areas is supposed to Lubrication with a high viscosity lubricant the friction between the sheet metal surfaces and the surfaces of lower mold 18 and upper mold 20 are reduced. To specifically deform this badly To coat panel areas with the lubricant, are above and below the track on which the metal sheets 12 through the second transport system 16 are moved, atomizing heads 28 perpendicular to Drawing plane arranged one behind the other. This each give off a droplet cone 30, which consists of small Droplets of the highly viscous lubricant exist. The latter is via a common lubricant feed line 32 fed. The latter comes from an overall with 24 designated control / supply unit. The different Atomizing heads 28 also have individual ones Activation lines 36, which with associated output terminals the control / supply unit 34 connected are.

The atomizing heads 28 are also common Atomizing compressed air line 38 and a common one Beam shape compressed air line 40 connected. Furthermore are the different atomizing heads 28 to a common one Heating current line 42 connected.

A first works with the second transport system 16 Path encoder 44 together, which is shown as a resolver. From its output signal, the control / supply unit 34 on the one hand recognize where there is a spray to be sprayed Sheet 12 with respect to the atomizing head assembly currently located, and also recognize which one Speed actuated the sheet 12 at the moment becomes.

A second travel encoder works with the press drive 22 46 together, whose output signal from the control / supply unit 34 is used to recognize when the transport systems 14 and 16 are started must also be from the control / supply unit 34 can be controlled.

In Figure 2 are parts of the device for spraying of the sheet metal plates referenced above Figure 1 have already been explained, again with the same Provide reference numerals.

Each of the activation lines 36 operates on one the atomizing head 28 considered solenoid valve 50, through which the atomizing air inside of the atomizing head. The atomizing air compressed air line 38 is via a pressure regulator 52 and a 2/2 solenoid valve 54 with the output of a cleaning unit 56 connected, the input via another, a 2/2 solenoid valve representing the main air valve 58 connected to a compressed air supply line 60 is.

The jet shape compressed air line 38 is via a second one Pressure regulator 62 and another 2/2 solenoid valve 64 with connected to the output of the cleaning unit 56. The exit the cleaning unit 56 is finally one another pressure regulator 66 with an air motor 68 connected, which works on a diaphragm pump 70.

The outlet of the diaphragm pump 70 is via a pressure regulator 72 connected to the lubricant feed line 32. In a suction line 74 of the diaphragm pump 70, which too leads to a reservoir 76 for the lubricant, an electric heater 78 is inserted.

The lubricant in the reservoir 76 is a drilling fluid-like emulsion with high viscosity. It has an approximately gel-like consistency at room temperature (0.85 Pa s). At the outlet of heater 78 is the lubricant heated to about 50 ° C and still has a viscosity of 0.4 Pa s).

The parts of the supply of the described above Atomizing heads with atomizing air, jet air and lubricant together form the one labeled 80 Supply part of the control / supply unit 34. The designated with 82 control part of the control / supply unit 34 is used to feed the atomizing heads assigned heating elements, for selective activation of the various atomizing heads 28, for actuation of the different solenoid valves of the supply part 80 and to coordinate the time window of the Pollination heads 28 and the amounts of liquid dispensed by them depending on the current situation the respectively sprayed sheet 12 for atomizing head arrangement as well as depending on the speed the metal sheet 12, both of which are from the output signal of the encoder 44 can be derived. Based on the The control part can output signals from the displacement sensor 46 82 count the press cycles. If desired, can only every second, third, etc. sheet of metal with lubricant be sprayed when the deformation of the metal sheet is only slight, so that from a previous one Sheet of lubricant left in the mold is sufficient for one, two or more subsequent metal sheets.

Similarly, you can set the first for each press cycle Always spray areas of a metal sheet with lubricant, while less deformed surface sections the sheet of metal only every second, third, fourth, etc. metal sheet are sprayed with lubricant.

In Figures 3 and 4 is a housing of an atomizing head 28 labeled 84 in total. It has a main body 86, which is closed at the top by a cover 88 is.

The housing main part 86 has an annular shoulder at the upper end 90, on which a holding plate 92 is seated, via which the atomizing head 28 on a load-bearing Structure (not shown) is attached. The holding plate 92 is sandwiched between the lid 88 and that Main housing part 8.6 clamped and against the interior of the housing sealed by an O-ring 94.

A cylinder bore 96 is provided in the main housing part 86, in which a piston 98 runs. This is firmly connected to a long dispensing needle 100, the has a pointed conical control section 102.

The piston 98 is followed by a spring 104 in Figure 3 preloaded below, which in a sleeve-shaped spring chamber 106 takes place, which can be screwed from the lid 88 is worn. The lower end face of the sleeve-shaped Spring chamber 106 also forms a stop surface, which adjustable the top dead center of the piston 98 pretends. To fix the spring chamber 106 in the selected one axial position is a threaded one Circlip 108 provided on the external thread the spring chamber 106 runs and with the top of the Lid 88 works together. One by screws 110 damper plate connected to the bottom of the cylinder bore 96 112 prevents the piston from hitting hard 98 at the bottom of the cylinder bore 96.

The one between the piston 98 and the cylinder bore 96 limited working space 114 has an axial bore 116 of the housing main part 86 with an atomizing air connection channel 118 related. Bore 116 extends beyond the connection channel 118 and ends in a counter bore 120, which in the bottom of the housing main part 86 is incorporated. Of the counter bore 120 is followed by a threaded bore above, which is coaxial with the cylinder bore 96 and into which an atomizing nozzle body 122 is screwed in. The The upper end of this threaded hole is with a lubricant connection channel 124 in connection.

The nozzle body 122 has a central bore 126 which surrounds the dispensing needle 100 at a distance. In the conical is the lower end portion of the nozzle body 122 a conical metering opening 128 is provided which has the same cone opening angle as the control section 102 the dispensing needle 100. In the transition area between its shaft section and the control section 102, the metering needle 100 carries an O-ring 130 which a reduced diameter end portion 131 of bore 126 engages before the end portion 102 strikes at the metering opening 128 to the To be able to completely close metering opening 128, without a high surface pressure between each other opposite surfaces of control section 102 and metering opening 128 would be necessary.

As can be seen from Figure 8, are in the outside Circumferential surface of the nozzle body 122 two diametrically opposite one another opposing nozzle grooves 132 are provided, which have a slope of approximately 45 ° and the counterbore 120 connect with a space 134 that between the conical lower face of the nozzle body 122 and a cylindrical / tapered counterbore 136 that is limited in a jet-shape nozzle body 138 is provided coaxially with the atomizing nozzle body 122.

The room 134 stands over a central opening-140 the bottom wall of the nozzle body 138 with the environment in Connection. Through the opening 140 extends below radial clearance, an end portion 142 of the nozzle body 122.

The nozzle body 138 is inside a mounting ring 144 arranged on a lower threaded End portion 146 of the main housing part 86 is screwed on and against it via an O-ring 148 is sealed.

The mounting ring 144 delimits with the nozzle body 138 in turn, a space 150, which via an axial channel 152 (cf. FIG. 4) with a shaped air connection opening 154 communicates.

As can be seen from Figures 3-7, the nozzle body 138 a conical lower end face, the Opening angle of this conical surface is approximately 120 °. In the conical surface are two diametrically opposite one another Form air nozzle grooves 156 inserted. Of the Front face of the nozzle body 138 protruding teeth 158 serve a predetermined angular position of the nozzle grooves 156 with respect to the substantially square cross section having housing 84 adjust.

The atomizing head described above works as follows:
The piston 98 normally assumes its lower end position under the force of the spring 104, in which the metering opening 128 is closed by the O-ring 130 carried by the metering needle 100.

With pressure applied to the connecting duct 118 Activation of the associated solenoid valve 50 is the Piston 98 upward against the force of the spring 104 moved, so that in the connecting channel 124 under pressure Lubricant present arrives at the metering opening 128. At the same time, 132 is compressed air via the nozzle grooves led into space 134 and through opening 140 given which the discharge end of the nozzle opening 128 surrounds. A total of one thus emerges from the opening 140 Droplet cone, at the viscosity described above of the lubricant has an opening angle of approximately 28 °.

At the same time passes through the connection opening 154 and the nozzle grooves 156 additional compressed air to the end face of the nozzle body 138. The two opposite one another Compressed air jets emerging from the nozzle groove 156 engage opposite side sections of the droplet cone emerging from the opening 140 on. This will flatten the cone and receives the cross-section instead of the circular cross-section a flat rectangle with rounded narrow sides. The opening angle of the flattened droplet cone is in the direction of the major axis of the cross section measured about 50 °, in the direction of the small one Axis measured less according to the cross-sectional rearrangement, namely about 15 °.

By the deformed generated by the atomizing head Droplet cones are obtained on a stationary workpiece an approximately bar-shaped pattern of lubricant. When moving the workpiece, you get an approximately rectangular one Lubricant samples on the workpiece surface.

As indicated by dashed lines in Figure 4, one can also for the shaped air connection openings 154 provide solenoid valves 160, so that you can see the different atomizing heads regarding the cross-sectional shape of the dispensed droplet cone can control differently.

To the amount of lubricant dispensed regardless of to keep the conveying speed of the sheet metal plates 12, you can press the pressure regulator 72 according to a metal sheet speed signal by the control part 82 with respect the control pressure, the sheet speed signal by differentiating the Output signals of the encoder 44 is obtained.

Alternatively, the atomizing heads 28 keep the amount of liquid dispensed constant and for varying the lubricant application on the workpiece surfaces the conveying speed of the transport system 16 vary.

To block the lubricant lines due to cold to prevent becoming lubricant, one can maintain a constant basic flow of heated lubricant, by moving the lubricant inlet as shown in Figure 9 the atomizing heads each via a pressure relief valve 162 connects to a return line 164.

Instead you can at the lubricant inlet of the atomizing heads also provide a 3/2 solenoid valve each which in push-pull to the solenoid valve 50 of the atomizing head is reversed to with the metering opening closed 128 lubricant to return line 164, with open metering opening but to feed the metering opening 128.

In FIG. 9 there is also a trace heating 166 and one associated with the housing of the atomizing head Heater element 168 shown.

Figure 10 shows a control circuit for activating the Atomizing heads 28 depending on the position of the to be sprayed onto the atomizing heads.

The output of the displacement sensor 44 is one with the input Analog / digital converter 170 connected. Its output signal we rounded up by a digital rounding circle 172. This receives one of the desired rounding via a line 174 corresponding digital signal, which is a measure of is the flattening of the droplet cone 30 and e.g. from the Output signal of a pressurized air pressure Pressure sensor (not shown) is derived.

The rounded path signal is converted into a summing circuit 176 a speed-dependent lead signal is added. The corrected path signal thus obtained is used for addressing a memory 178 in whose cells signal words are stored, the number of bits of which is to be controlled Atomizing heads are equivalent (or larger). On Bit "1" stands for an atomizing head to be activated, a bit that is not set indicates that the assigned Atomizing head currently not used to create the lubricant pattern is needed.

It can be seen that this is for example in the memory 178 registered bit patterns of a coating of the edge a sheet of metal with emphasis on the corner areas and one weaker coating of the middle panel areas corresponds.

To generate the lead signal, the output of the A / D converter 170 additionally to a digital differentiating circuit 180 connected. The board speed signal thus obtained is in a computing circuit 182 in implemented the lead signals, the computing circuit 182 receives a further signal via a line 184, which the Corresponds to the velocity of the droplets in the droplet cone. This further signal can e.g. of the output signal one Pressure sensor (not shown), which is subjected to the pressure of the atomizing air.

The summing circuit 176 thus effectively forms a controllable one Phase shifter or a controllable timer for Synchronization of the working heads on the movement of the Metal sheets.

The one selected by the output signal of the summing circuit Word of memory 178 is transferred to register 186 its individual memory elements via amplifier 188 work on the activation lines 36.

The atomizing heads described above stood the shaped air nozzle grooves 156 both with the annular Room 150 communicating so that the droplet cone is symmetrical is flattened. Instead, you can use the two Air nozzle slots also with separate housing connections connect and connect to separate air sources. An asymmetrical cone flattening is then obtained. The shaped air nozzle grooves can also be used asymmetrically Distribute around the axis of the opening 140.

By increasing the number of shaped air nozzle grooves you can flatten the droplet cone several times, e.g. to essentially square cross-sectional shape.

With the atomizing heads described above the setting of the atomization rate manually by screwing the spring chamber 106. Instead you can under Omission of the circlip 108 through the spring chamber screw a self-locking gear actuator, as indicated by dashed lines in FIG. 4 at 190.

Claims (7)

Device for spraying workpieces with a liquid, with a plurality of atomizing heads (28), with a storage container (76) for the liquid to be atomized, with a pump (70) for conveying the liquid to be atomized from the storage container (76) to the Atomizing heads (28), and with an atomizing air control valve arrangement (50), which is connected between an atomizing air source (38) and atomizing air connections (118) of the atomizing heads (28), characterized in that the control valve arrangement (50) by a control unit ( 82) is activated as a function of the output signal of a displacement sensor (44) which works together with the workpiece (12) to be sprayed, which is moved past the atomizing heads (28) by a transport device (16). Device according to Claim 1, characterized in that the control unit (82) has a memory (178) which is addressed in accordance with the output signal of the displacement sensor (44) and in the memory cells of which the respective position of the workpiece (12) with respect to the atomizing heads is found (28) to be controlled the pollination heads (28) are stored. Device according to claim 2, characterized in that the control unit (82) controls a pressure adjusting valve (72) as a function of the conveying speed of the workpiece (12) in order to keep the amount of liquid applied to the workpiece per unit area constant. Device according to claim 2 or 3, characterized in that the control unit (82) controls the atomizing heads (28) via a controllable phase element (176), the phase of which is set in proportion to the speed of the workpiece (12). Device according to one of claims 1-4, characterized by a heating device (78) acting on the supplied liquid and by 2/2 bypass valves or pressure relief valves (162) which are each assigned to the atomizing heads (28) and via which the non-atomized liquid quantities in a return line (164) are guided. Device according to one of claims 1-5, characterized in that a shaped air source (40) is connected to shaped air connections (152) of the atomizing heads (28) and preferably the control unit (82) a shaped air pressure regulator (62) depending on the output signal controls the encoder (44). Device according to one of claims 1-6, characterized by a trace heating for the liquid feed lines (32) leading to the atomizing heads (28).

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