DE102014007523A1 - Methods and devices for coating surfaces with colors - Google Patents

Abstract

The invention relates to a method for the contactless coating of surfaces with ink using a hand-held inking device 1 with a plurality of ink outlets 11 arranged in at least one row, characterized in that ink is introduced through at least one metering unit 2 of the plurality of ink outlets 11 via an ink feed 13 is continuously supplied, and that the transport of the color outlets 11 exiting paint is supported to the surface by means of an air flow.

Description

The invention relates to the field of coating surfaces in general, primarily in the construction sector, with coating materials, especially with paints and varnishes, hereinafter referred to only as "paints". The coating is used for preservation and color decoration of the surfaces.

The coating of these surfaces is done today by manual methods such as painting with brushes, rolling or spraying. These methods require to varying degrees Abklebearbeiten (masking), covering or Vorstreicharbeiten, otherwise accurate contouring of the coated areas is not possible and contamination of the work area can not be prevented. In particular, during spraying i. d. Usually a single nozzle is used, the application of which is expanded by atomization to a wide range, the width of which depends on the distance to the surface due to the spray angle. Thus, a precise coating of corners and edges without prior masking this is not possible. The application is modifiable only to a small extent, since otherwise the spray pattern changes significantly, so that it is impossible to move a spray gun slowly and accurately to obtain a precisely contoured paint application.

For the field of decorative design of areas with graphics was in US7,981,462 presented a printing method with a hand-held system, which can also serve as a means of coating the aforementioned areas in the case of a monochrome graphic. Such a coating method employs a plurality of individually controlled drop-on-demand color printing nozzles in a row, which is constantly moved across the surface by means of rollers and allows a precisely contoured printing of color. Due to the position measurement and the individually controlled printing nozzles, however, the printing process is quite complicated for a single-color ink application.

In US8,556,373 introduces a printhead designed for the printing of paints and varnishes, and is particularly suitable for use in a hand-held inking unit through its miniaturized technique. Coating by the drop-on-demand method produces a layer of a plurality of pressure points or spray points. The miniaturized and thus high-transient technology in US8,556,373 enables a highly accurate dosing of the individual drops of color and provides maximum flexibility in the control, for example, when circular movements are to be performed with a small radius. In the event that this is not required, now devices and methods are presented, which are equipped with a much simplified technology and not necessarily based on a drop-on-demand method.

Thus, it is an object of the invention to provide simple methods and inexpensive devices for primarily hand-held, uniform coating of surfaces with a device that applies paint to surfaces by means of a plurality of nozzles arranged in at least one row.

The invention is solved according to the features of the independent claims.

Accordingly, see 2 , contains a paint applicator 1 medium 6 for the continuous measurement or provision of the variable traveled distance or the relative speed of the inking device 1 to the surface, a control 5 or other device for controlling a color dosing unit 2 , a color supply 13 to the nozzles 4 with channels and / or hoses. A nozzle 4 Coats only a small area of the area with a width in the order of millimeters to a maximum of a few centimeters. The use of many nozzles 4 with a small spray pattern at a small working distance allows a much sharper contoured surface coating on color finishes, corners and edges than in known spray methods with only one nozzle and a long working distance. Groups of nozzles 4 are connected on the input side with a fluid distribution cavity, which is part of the ink supply 13 is. Thus, in contrast to classic airless spraying, paint is not applied from a single nozzle with a large opening angle and a large distance to the surface, but through a series of nozzles 4 each with a low output, which are each arranged to the surface at a small distance from the surface. Depending on the mode of operation, these only produce one injection point or a narrow color strip on the surface when viewed individually. The spray patterns of adjacent spray nozzles overlap so that a homogeneous coating results. The small distance of the spray nozzles to the surface is by rolling or Gleitelemnte 8th defined on the underside of the paint applicator in the case of a hand-held device. Due to the small distance of the nozzles 4 To the surface, accurate coating of color boundaries, corners and edges is possible without requiring prior masking or pre-painting of the surfaces.

A controller 5 causes the delivery amount of paint through a spray nozzle 4 or through all atomizer nozzles always proportional to the speed of the paint applicator 1 is, the main direction of movement 9 the preferred direction of movement is perpendicular to the Series of atomizer nozzles 4 is directed. The regulation of the color promotion by the dosing unit is carried out so that a predetermined wet layer thickness results. Thus, by the controller 5 a uniformly thick paint application both at high working speed and at very slow movement possible.

The color output through the atomizer nozzles 4 can be done discontinuously by ejecting the ink in the nozzles by pressure pulses, as shown in FIG US8,556,373 is described. The pressure pulses can be generated by very fast valves or by pulsating diaphragm or piston displacer, ie by pulsating pumps. Color dots or color spray dots are applied and this is called drop-on-demand (DOD). This method requires a sufficiently high momentum of the ink on exit from the nozzles, since a drop break must occur at the end of a pressure pulse. Thus, the pressure pulses must be highly transient.

It is proposed, one or more groups of spray nozzles arranged in a row by at least one continuous color promotion in the form of a color dosing unit 2 to supply. Because at low relative speed of the applicator 1 To the surface, the exit velocity of the ink from the nozzles must be very small in order to obtain a constant layer thickness of the ink on the substrate, the paint would not detach from the nozzles without further action, but the nozzles contaminate. For this reason, the color separation according to the invention is not accomplished by means of the pulse of the exiting color, but by means of an additional air flow, henceforth atomizing air, accomplished. Thus, each spray nozzle has a paint outlet 11 that with an air gap 12 interacts like that out of the paint outlet 11 leaking paint is seized and entrained by the atomizing air. Below a critical air mass flow, there is only a removal of the paint from the paint outlet 11 instead, an atomization of the color takes place over it. If the paint application is interrupted, the atomizing air is likewise activated by actuation of a pneumatic valve 19 interrupted.

Therefore, according to the invention, it is proposed not only in connection with the continuous promotion of the color, at each nozzle the color by means of an atomizing air at the respective paint outlets 11 to dissolve, especially to atomize. It should be noted that the sputtering methods described herein are also applicable to discontinuous operation as set forth above. For this purpose, for example, the PEN (pnematic extension nozzle) method ( 3 ) or the CPN (Circular Pneumatic Nebulizer, Ring Atomizer) method ( 4 ) suitable. Other sputtering methods are expressly excluded. Thus, an inking device according to the invention contains 1 a series of PEN or CPN atomizer nozzles 4 , which color depending on the relative speed of the paint applicator 1 is supplied.

3 demonstrates a construction and arrangement of atomizing nozzles 4 according to the PEN procedure: A group of paint outlets 11 is arranged in at least one row. From the paint outlets 11 will paint in the openings of a second air nozzle plate 18 with openings, the PEN outlet openings 15 injected. The paint outlets 11 are located inside an air-filled chamber, which is part of the atomizing air supply and is acted upon by the pneumatic pressure of the atomizing air. The paint outlets 11 be from a common ink supply 13 supplied with paint. Atomizing air is pressurized by the atomizing air supply 14 the nozzles 4 fed and flows with high speed through each of the openings 15 outwards against the surface to be coated. Gives a color outlet 11 an amount of color continuously or pulsating, so this is with the opening 15 escaping atomizing air entrained and due to the high shear forces and the sudden pressure drop in the opening 15 atomized. On the surface to be coated forms under each nozzle 4 a spray point in the case of a pressure pulse. The distance of the paint outlets 11 to the openings 15 is dimensioned so that the escaping atomizing air flow also entrains and atomizes only slowly emerging color from the paint outlets.

4 demonstrates a construction and arrangement of atomizing nozzles 4 according to the CPN sputtering method. The difference to the above-mentioned PEN method is that the color outlets 11 partly or completely through the openings 15 protrude, whereby an annular gap is formed at each nozzle in which forms a, the color strongly flowing atomizing air-ring flow. At the edge of the respective paint outlets 11 strong shearing forces form, so that the paint is atomized.

The PEN spraying method allows as a variant the simultaneous atomization of two or more colors or liquids, see 5A , A first set of paint outlets 11A is doing by a common ink supply 13A supplied with paint. A second set of paint outlets 11B is from a common color feeder 13B supplied with paint. Corresponding color outlets 11A and 11B are on a common PEN outlet opening 15 directed through the atomizing air flows out at great speed. At the same time supplied color paint outlet 11A and from 11B becomes efficient when passing through opening 15 mixed. If, therefore, both colors are controlled synchronously, also pulsierened, so arise on the surface to be coated spray points of a mixed color. It should be noted here that this provides an efficient way of applying 2-component, high-reactive coating materials to surfaces by mixing them at the time and place of application. Integrated in a hand-held, speed-controlled inking unit 1 Thus, there is a handy device that allows for the first time to coat surfaces with a 2-component coating material by hand. It should be noted that a mixing atomization system for each component has its own color dosing unit 2 and own ink supply channels 13 requires. It also 1: 1 different mixing ratios of the two components by means of the respective Farbdosiereinheiten 2 be set.

Is the PEN mixing principle combined with a valve-based drop-on-demand printing process, such as in US8,556,373 mixed inks can be printed with intensive mixing: in this case, the color outlets are per channel 11 the drop-on-demand drop generators of, for example, 2 to 6 primary colors in a manner similar to 5A shown and described above on a common PEN outlet 15 directed so that out of the paint outlets 11 emitted color drops of the respective primary colors in the direction of the common PEN output 15 fly there and be vortexed together by the shear forces of the exiting at great speed atomizing air and atomized. As a result, each channel creates a spray point with a mixed color on a substrate or surface. A printhead thus equipped has a plurality of channels, each of which emits spray dots of a color mixture of the primary colors. The color mixing tones of each channel can be set independently by changing the valve opening times of the metering valves of the primary colors. Print heads of this type can be used in many ways in the field of graphic printing.

The atomization according to the sputtering methods described can be further improved by a meaningful flow control near the outlets 15 or 16 , which favor a rotating flow, see 5B , Above all, measures include tangential openings 15 or 16 opening air guiding structures 35 one that provides tangential introduction of the atomizing air at multiple angles into the outlets 15 or 16 favor.

In a preferred arrangement, the nozzles have 4 with each other a distance of a few millimeters and 2 to 10 times their distance as a distance from the surface. In a further arrangement, the nozzles have a distance of a few centimeters and a distance from the surface of the same order of magnitude. Here are the spray patterns of adjacent atomizer nozzles 4 so that the paint jobs of adjacent atomizer nozzles overlap.

In another arrangement, within the row of atomizing nozzles, every other nozzle is offset in the main moving direction by a distance of the order of atomizer nozzle spacing, so that a better overlap of the pressure areas of the individual nozzles is achieved. This arrangement is equivalent to an arrangement in which two laterally offset rows of atomizing nozzles are used, the lateral offset corresponding to half the spacing of the atomizing nozzles.

For example, at low ink applicator speeds below 10 mm / s, only a small amount of ink needs to be delivered through each nozzle. Thus, the resulting pressures of the ink at the location of the respective nozzles are also small and the hydraulic pressure differences or inhomogeneities of the color properties of the ink in the inlet area of the atomizing nozzles can affect the amount of ink discharged by each atomizing nozzle. According to the invention, this problem is met by controlling technology, in that only from a minimum speed, that is, from a minimum discharge quantity, ink is conveyed or metered. This measure is not on atomized spray nozzles 4 but can also be applied to the cases where color is discontinuously ejected by ink nozzles with or without atomization, and the pressure pulses do not have a constant duration and height, as is the case with the use of a motor-driven piston or diaphragm pump.

An inventive color applicator 1 is preferably designed as a hand-held implement, see 1 which by a handle 10 is moved by an operator and preferably on rollers 8th or sliding on the surface moves. The roles 8th are preferably coupled to means for measuring the rotational speed of the rollers, which is an odometric signal for the speed of the applicator 1 deliver. Optical motion sensors, so-called mouse sensors, are also suitable for measuring the speed to the ground. The paint applicator 1 also contains means for interaction 7 with the operator, such as displays, indicator lights, input elements, pressure, rocker or slide switches for Enable or disable single atomizer nozzles 4 and more particularly a switch for activating the coating process. The at least one row of atomizer nozzles 4 is in mainstream direction 9 behind the wheels 8th appropriate. The handle can be designed so that the ink supply is passed through this hindruch and the color in its interior through a removable filter cartridge (gun filter).

The paint applicator according to the invention 1 further includes the possibility of individual or groups of atomizing nozzles 4 for deactivating the color output, see 6 ,

This can be done by means of simple mechanically operated fluid valves, which in the paint feeds for each color outlets 11 or for groups of paint outlets 11 are installed. For example, a fluid valve for a single atomizing nozzle may consist of a closing element acting as a slide or needle valve 30 sealing on the inside of a paint outlet 11 or an upstream fluid passage by means of an actuator 31 is moved to the fluid supply to one or more paint outlets 11 to interrupt. To improve the tightness at low flow rates, a force-assisted sealing function should be used. A group of paint outlets 11 For example, by a group of vorgennanten actuators 31 , which protrude through a plastic housing and manually, for example, on the outside of the housing by means of slide 32 with guide contours 33 be operated, be switched. The construction described is given only as an example and representative of the many possibilities for realizing mechanical valves with mechanical actuation. Instead of a slider mechanism 32 For example, pressure or rocker mechanisms are also conceivable. In this case, for example, subgroups of fluid outlets 11 together by means of a slider 32 be actuated by a manual operating mechanism, such as a slider 32 , a variety of actuators 31 operated or by actuating a valve mechanism which actuates a group of paint outlets.

According to the invention, it is further proposed that the atomizing air supply 14 for deactivated atomizer nozzles 4 and deactivating the coating function of the paint applicator 1 is also interrupted by valves.

Becomes a group of n nozzles 4 from a color dosing unit 2 When ink is dispensed, when k nozzles are deactivated, the quantity of ink to be dispensed is proportional to the total number of nozzles in the group, ie by k / n.

A color dosing unit 2 for continuous ink delivery through nozzles 4 can work according to various known methods and will only be briefly discussed below: 7 shows a paint dosing unit 2 based on a dosing pump 23 what color from a reservoir 3 in the fluid supply 13 to the paint outlets 11 promotes. The fluid supply 13 Also includes cavities and lines for distributing the paint to all or groups of paint outlets 11 , As metering pumps 2 Pumps or pump assemblies come with low resulting pulsation into consideration, for example using gear pumps, peristaltic pumps or multi-pass diaphragm pumps that promote out of phase. Suitable motors 24 are preferably stepper motors or servomotors. A simple control of a stepper motor could be, for example, that the movement of the Auftragvorrichtng 1 is measured by means of a displacement sensor, a speed sensor or an odometer with incremental encoder output, which delivers a measuring pulse after a distance traveled in the sub-millimeter range. The measuring pulses can be supplied with an appropriate design directly or after multiplication by a factor of the stepper motor, amplified by a power amplifier. Also, mechanical translations between the motor axis and Dosierpumpenachse be interposed.

8th shows a paint dosing unit 2 based on a syringe pump 23 what color from a reservoir 3 in the fluid supply 13 to the paint outlets 11 promotes. The syringe pump has a piston 20 , an inlet valve 22 and exhaust valve 21 and is driven by a linear drive. This is preferably by a motor 24 and implemented a spindle drive.

A paint dosing may also be by pressurized paint and a proportional valve acting as a dosing valve 25 works, be realized, see 9 , This is done at a measuring point 27 the actual flow of the paint is measured and in a closed loop by means of a regulator 26 regulated in proportion to the speed v.

It depends on several factors where there is color dosing unit 2 and reservoir 3 are located. In a first case, both are in the handset, the paint applicator 1 This is useful when the reservoir is small and the paint dosing unit is light. In a second case, the color dosing unit 2 in the paint application device 1 and the color reservoir 3 which passes through a suction hose with the paint dosing unit 2 be worn on the operator's body, for example in a backpack or at waist level in a waist-pack or on a belt. In a third case, the color dosing unit is located 2 in the paint application device 1 and the color reservoir 3 such as a paint bucket, on the floor. In a fourth and fifth case, from a paint bucket by means of the metering device 2 , which is directly on the paint bucket or on the body of the operator, sucked paint.

Especially in the case of a paint dosing by means of metering valve 25 it is beneficial to paint from a bucket at constant pressure by means of a paint circulation system to the inking device 1 to promote, in which the dosing valve 25 and the flowmeter 27 located. The color is doing with high pressure from the paint reservoir 3 , For example, the paint bucket, to a pressure control valve in the applicator 1 one part of which is routed again via a return line to the paint reservoir.

In addition to US8,556,373 and in the light of the problem posed here, it is proposed to operate a fluid actuator according to the displacement principle, such as a diaphragm or piston pump, which is used for the generation of pressure pulses in the ink, not directly with an eccentric of an engine, but by means of a plunger 40 accelerated to a defined speed and at that speed to the diaphragm of a diaphragm pump or to the piston of a piston pump, directly or via a force transmission element 42 , meets. He gives his kinetic energy via the membrane / the piston to the color, so that a reproducible pressure pulse is produced in the color. The pulse delivered to the color is proportional to the mass of the plunger 40 and its velocity in the collision, reduced by the pulse delivered to diaphragm / piston and power transmission elements. The pressure pulse may then be in the color within the cavities of the ink supply / the color distributor to the one or more color outlets 11 spread. From these he causes a discrete, discontinuous drop delivery. Conveniently, a device which provides a plunger periodically, optionally with the speed of the paint applicator 1 proportional frequency, accelerated to a defined speed and then catapulted to a fluid actuator according to the displacement principle, can be realized in various ways:
An embodiment, see 10A , has a spring-mass system consisting of at least one spring 51 which is connected at its first end to a housing and at its second end with a predominantly linear moving plunger 50 defined mass is connected. The plunger is movably mounted in the direction of the spring deflection, for example by a linear guide as in 10A or by leaf springs 47 , as in 10B shown in two examples. The acceleration of the plunger in the direction of fluid displacer takes place in the examples in each case by spring 41 , In this case, in a first step spring 41 curious; excited. In a second step, the spring 41 released, leaving the ram 40 is accelerated by spring force. The elastic energy of the spring 41 is doing in kinetic energy of the plunger 40 implemented. tappet 40 and Pumpmenbrane or piston are arranged so that the recoiling plunger these directly or via a power transmission element 43 and finally transmits its mechanical impulse to the color as described. The spring-mass system is dimensioned to a resonance frequency of at least the highest pulse frequency. An increase in the resonant frequency theoretically causes a reduction in droplet ejection time. However, this effect may be due to a compliance in the system of ink supply 13 Thus, a system inherent or discretely inserted buffer can be reduced. The operation of the spring-mass system, for example, with an eccentrically connected to a drive shaft driver 44 take place, which within a certain angle of rotation range in a correspondingly arranged contact surface 49 of the plunger 40 engages: In the course of the rotational movement of the drive shaft 39 becomes the pestle 40 deflected within a first angular range to a defined angular position of the drive shaft and the spring tensioned. In a second rotation angle range of the drive shaft 39 leaves the driver 44 the engagement with the contact surface 49 so that the now stretched spring 41 the pestle 40 accelerated in the direction of the pumping mechanism. The drive of the drive shaft 48 can be through motors or through the rollers 8th , done directly or via a power transmission in the form of a belt drive, chain drive or gear drive. Will the drive shaft over the rollers 8th driven, a speed-proportional control of the color output is implicit given that the rotational speed of a roll, as long as no slip to the surface occurs, directly the moving speed of the inking device 1 represents. However, slippage can, as in 1B already shown, are largely avoided when the rollers have the tips or teeth described on the circumference.

It should be mentioned here that to enable the suction cycle, or the provision of the pump piston or the pump diaphragm known measures of the prior art, such as a return spring 42 , must be present.

The principle of the generation of the pressure pulse in the color by a force pulse on a displacer can also be applied to a plurality of displacer: For example, as the drive shaft is an elongated shaft 48 with several or a plurality of carriers 44 for example, a gear or belt drive 46 driven. The belt drive 46 or the wave 48 even by a motor or again by the rollers 8th self-propelled, which is a purely mechanical operation of the hand-held paint application device 1 implied. The drivers 44 each drive in the manner described a group of plungers 40 which drive in the manner described a group of actuators according to the displacement principle. Each actuator, so each diaphragm or piston pump generates pressure pulses in associated ink supply units 13 that with one or more paint outlets 11 are connected.

In 10B , left, be in place of a spring 44 one or more leaf springs 47 used to cause the acceleration of the plunger. These can, as shown in the picture at the same time as a linear guide, or as an elastic bearing for the plunger 40 serve.

In another embodiment, spring 41 be deflected with an electromagnet of sufficient strength. It makes sense to manufacture the plunger from a magnetic material and to design the electromagnet so that plunger 40 is anchor at the same time.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7981462 [0003]
• US 8556373 [0004, 0009, 0015, 0030]

Claims (10)

Method for contactless coating of surfaces with paint with a hand-held paint applicator 1 with a variety of paint outlets 11 , which are arranged in at least one row, characterized in that color by at least one metering unit 2 the variety of paint outlets 11 via an ink supply 13 is fed continuously, and that the transport of the paint outlets 11 escaping paint is supported to the surface by means of an airflow. A method according to claim 1, characterized in that the dosing unit 2 is controlled so that the conveyed amount of ink proportional to the distance traveled per unit time path of the paint application device 1 relative to the area. Method according to one of the preceding claims, characterized in that an atomization of the color of the fluid outlets 11 by an atomizer arrangement according to the CPN principle or PEN principle. Method according to one of the preceding claims, characterized in that the spray images of adjacent fluid outlets 11 overlap. Method according to one of the preceding claims, characterized in that color on the way the fluid supply 13 a filter cartridge flows through. Method according to one of the preceding claims, characterized in that the nozzles 4 have a distance of a few millimeters between them and 2 to 10 times their distance as a distance from the surface. Method according to one of the preceding claims, characterized in that the nozzles 4 have a distance of a few centimeters and a distance from the surface of the same order of magnitude. Method according to one of the preceding claims, characterized in that individual or groups of atomizer nozzles 4 be deactivated by means of fluid valves for a color output. Method according to one of the preceding claims, characterized in that the atomizing air supply 14 for deactivated atomizer nozzles 4 and deactivating the coating function of the paint applicator 1 is interrupted by valves. Hand-held paint applicator 1 for contactless coating of surfaces with paint with one with a variety of paint outlets 11 arranged in at least one row, characterized by a continuous ink supply to the plurality of paint outlets 11 by means of at least one metering unit 2 , and means for generating an airflow at the paint outlets 11 to support the transport of the paint to the surface.

Images