EP1990206B1 - Method and device for embossing a component with two mutually inclined surface areas by means of a digital printing process - Google Patents

Abstract

The method involves controlling a pressure medium left from a printhead (22) in such a manner that a part of a transition region (18) is only printed. The transition region is strongly inclined to a direction of two relative movements, where the medium has low gradient to the respective movements. Respective distances of the movements of injected fluid amount are gradually reduced to zero during printing of the part of the region, so that the part is partially printed. An independent claim is also included for a device for printing a component by an inkjet printing method.

Description

The invention relates to a method and a device for printing a component by means of a digital printing method, which component has a first and a second surface area.

In practice, in a wide variety of applications, the task of printing components with two surface areas, which are inclined at an angle to each other and connected to each other via a transition region. Such components may be, for example, plates or strips with at an angle of, for example, 90 ° to each other arranged side surfaces which are connected to each other via an edge formed with a radius or a transition region. Such components are printed after mechanical finishing, for example, with an ink jet process, so that their entire visible surface to the outside receives a pleasing appearance, for example, provided with a homogeneous ink layer or with a pattern that runs steadily over the entire surface. It is known to move a print head and a component to be printed during the printing relative to each other such that the print head is constantly directed as possible while keeping its distance constant perpendicular to the surface to be printed. This requires both a high mechanical complexity of the respective device as well as a high cost of data processing for controlling the device.

In the US 2003218663 A1 , is based on the preamble of claim 1, a printing method for printing a component having two mutually perpendicular surface areas is described, which merge into one another via an inclined surface 116. For printing each surface area is a printhead 60. The inclined surface is printed so that the printheads are each moved beyond the associated surface area, so that at least one part of the inclined surface is printed. Advantageously, a middle region of the inclined surface is printed by both printheads.

The US 2001019340 A1 describes a printing method and a device for its implementation, in which or when printing three-dimensional surfaces on a printhead trained printing nozzles are each controlled such that only those printing nozzles are activated, the distance from the surface to be printed is within a predetermined value ,

In the DE 100 31 030 A1 In general, a method for producing flat components with a predetermined surface appearance is described, in which method the components are printed by means of a programmable printing method. It is also possible to print components with mutually inclined surfaces. Regarding the printing of a transition region between the inclined surfaces, there are no indications.

The EP 1 479 524 A1 also generally describes a method of manufacturing a component having a surface of predetermined appearance, wherein adjacent surface areas disposed at an angle to each other are patterned such that the pattern smoothly transitions from one surface area to the other surface area. There are no indications regarding the printing of a transition area between the surfaces.

The invention has for its object to provide a method and an apparatus with which it is possible to easily print a transition region formed between two surface regions forming an angle with one another in such a way that a homogeneous printing of the transition region takes place.

The directed to the method part of the invention task is solved with the features of claim 1.

The dependent claims back to claim 1 are directed to advantageous embodiments and developments of the method according to the invention.

The claim 8 is directed to an apparatus for solving the relevant part of the invention task.

In the present application, a digital printing method is understood to mean printing methods in which a liquid in the form of individual liquid droplets is sprayed onto individual surface elements of a surface to be printed by means of at least one digital data set from at least one spray nozzle in order to produce a predetermined pattern on the surface. which can also have the appearance of a homogeneous coloring. Different colors can be produced by different color liquids, which are sprayed in the form of droplets on a surface element or immediately adjacent surface elements. Different color intensities can be produced by the number of droplets reaching a surface element or immediately adjacent surface elements and / or, more recently, by different volumes of the liquid droplets. A typical example of a digital printing process is the so-called inkjet printing process in which ink or dye liquid droplets are ejected from a printhead having a plurality of spray nozzles. The droplets are generated by thermal evaporation (bubblejet) or by means of piezoelectric elements and sprayed.

The invention is explained below with reference to schematic drawings, by way of example and with further details, wherein the digital printing method is carried out like an ink-jet printing method.

Fig. 1

eine Querschnittsansicht eines zu bedruckenden Bauteils mit Erläuterungen zur Durchführung eines erfindungsgemäßen Verfahrens,

Fig. 2 bis 5

Querschnitte durch unterschiedliche, zu bedruckende Bauteile,

Fig. 6

eine Aufsicht auf die abgewickelte Oberfläche eines Bauteils,

Fig. 7 bis 9

Darstellungen zur Erläuterung von unterschiedlichen Ausführungsformen des erfindungsgemäßen Verfahrens,

Fig. 10

eine der Fig. 1 ähnliche Ansicht zur Erläuterung einer weiteren Durchführungsform des erfindungsgemäßen Verfahrens und

Fig. 11

eine schematische Ansicht einer Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens.

In the figures represent:

Fig. 1

a cross-sectional view of a component to be printed with explanations for carrying out a method according to the invention,

Fig. 2 to 5

Cross sections through different components to be printed,

Fig. 6

a view of the unwound surface of a component,

Fig. 7 to 9

Representations for explaining different embodiments of the method according to the invention,

Fig. 10

one of the Fig. 1 Similar view for explaining a further embodiment of the method according to the invention and

Fig. 11

a schematic view of an apparatus for performing the method according to the invention.

According to Fig. 1 has a component to be printed 10, in the example shown a edge strip, a non-printing base 12, a likewise not to be printed lateral side 14, a first flat surface area to be printed 16, a to be printed curved transition area 18 in a flat to be printed second Surface area 20 on. The surface regions 16 and 20 are perpendicular to one another and in each case continuously transition into the transition region 18, which extends over an angular range of 90 degrees and has a radius of curvature r.

At 22, a print head of a per se known ink jet printing device is described, which is formed for example as a pressure bar and over the entire in Fig. 1 extends perpendicular to the plane of the drawing length of the component 10. Such a pressure bar contains, for example, a plurality of printheads arranged in mutual overlap along its length, so that each surface element can be covered with liquid droplets. By means of electronic control of the relative position between the spray nozzle (s) and the surface to be printed and the type and amount of liquid reaching a surface element, predetermined digitally stored patterns can be precisely produced on the surface to be printed.

The printing of the component 10 takes place in the illustrated example such that initially under relative movement between the component 10 and the print head 20 in a direction perpendicular to the plane perpendicular to the paper plane extension direction of the component 10 and parallel to the surface region 16 (x-direction) of the first Surface region 16 and a part of the transition region 18 is printed. The control data stored in an EDP system are distorted with respect to the curved transition region 18 in the x-direction compared to a template, which shows the pattern to be generated on the curved surface of the transition region, so that depending on the angle α, the x-direction with the respective tangent to the surface of the transition region forms, the pattern is stretched. Furthermore, in order to keep the pattern intensity constant over the transition area, the amount of liquid sprayed off is changed as a function of x.

With x ₀ is in Fig. 1 denotes the beginning of the transition region. For x-values according to Fig. 1 To the left of x ₀ , the quantity of liquid to be sprayed off per relative movement unit in the x-direction is constant relative to the color intensity to be achieved. As soon as the point x ₀ is reached, relative to a certain relative movement between the print head 22 and component 10 in the x direction to be printed area of the transition region to. The intensity of the printing, ie the amount of liquid to be emitted per unit of relative movement in the x direction for the generation of a predetermined color intensity, remains over a distance x ₁ , starting from x ₀ Fig. 1 is initially constant to the right and then decreases between x ₁ and x ₂ , for example, linearly, and is set to zero when reaching the point x ₂ , so that the according to Fig. 1 lowest part of the transition region 18, which is very strongly inclined to the x-direction, is not printed in this printing step.

In summary, the pressure intensity of A (beginning of the first surface area 16) to the point x ₁ (α = 45 °) is constant 100% in the described printing process, and then decreases between α = 45 ° and for example α = 60 ° to 0% , The region in which the inclination between the transition region 18 and the first surface region 16 is greater than 60 degrees, is not printed in the described printing step, since at such strong angles of inclination due to the rebound of droplets are no defined conditions.

At the described printing step I is followed by a further printing step II, in which the second surface area 20 is printed and the in Fig. 1 is shown as y-direction. First, again with an intensity of 100% from the point B to the point y ₁ printed by the surface of the transition region 18 is inclined to the y-direction by 45 degrees. Subsequently, the intensity in the range between y ₁ and y ₂ (inclination by 60 degrees) decreases to zero, so that the region of the transition region 18 which is inclined more than 60 degrees to the y direction is not printed in this method step.

Overall, with the described printing method achieved in a simple manner that the transition region in well-defined way (exact formation of the pattern due to sufficiently large angle of incidence of the droplet direction on the surface (between 90 degrees and 30 degrees)) is printed with good pattern quality, the intensity remains constant in that in the transition region, is printed on in both printing steps (x and y), the pressure intensity of the one printing step decreases and that of the other printing step increases, so that the sum intensity is approximately constant.

The two printing steps I, II can be carried out, for example, by first performing the printing step x such that the component 12 is moved from right to left under the print head 22, then the component 12 corresponding to the angle of inclination of the first surface area 16 and the first surface area 16 second surface area 20 to each other in the illustrated example by 90 degrees) and is then moved from left to right under the print head 22, wherein the printing operation begins when the point B is located under the print head and the printing ends when the location y _{2 is located} under the printhead.

The described method, according to which a curved surface can be printed without a print head or the component to be printed being pivoted during the printing process, can be used for a wide variety of components.

Fig. 2 shows a cross section through a component in which two relief-like surface regions 16 and 20 are interconnected via a transition region 18, wherein the angle γ, the surface regions 16 and 20 together form, about 60 degrees. In a first printing step I, the surface region 20 is printed with a first part of the transition region 18. After a relative pivoting between the print head 22 and the component 10 by the angle γ, the surface region 16 is printed with a part of the transition region 18 in a second printing step II, wherein the parts of the transition region which are printed in the printing step I and in the printing step II overlap , The pressure intensity, ie the amount of pressure fluid delivered per unit of relative movement, can already be modulated during the printing of the relief-like surface areas 16 and 20 depending on the respective angle of inclination between the surface area and the direction of movement.

Fig. 3 shows a component 10 with three mutually perpendicular to each other forming planar surface areas which are interconnected via curved transition areas, wherein the radii of curvature of the transition regions may be the same or different. The surface to be printed on the component 10 is printed in three printing steps I, II and III, in which the component 10 is pivoted to the print head 22 in each case by 90 degrees. The transition areas are, as based on the Fig. 1 portrayed, printed.

Fig. 4 shows a component 10 whose surface is to be completely printed; In this case, the steps I, II and III correspond to the embodiment according to FIG Fig. 3 , In step IV, in which the underside of the component 10 is to be printed, the print head 22 and the component 10 are pivoted to each other such that the relative movement between the print head 22 and component 10 is parallel to the bottom.

When printing the acute-angled edge 24, no special control measures need to be taken because, for example, the side area is shaded when printing on the underside and, conversely, the underside is shaded when printing the side area. When printing the obtuse-angled edge 28, on the other hand, in order to avoid over-intensities, the respective pressure intensity must be reduced within a short distance before reaching the edge or the boundary of the respective surface.

Fig. 5 shows a circular bar, which is advantageously printed in four printing steps I to IV, wherein in each of the printing operations to both end regions toward control operations are performed, as shown in the Fig. 1 for the transitional area between Fig. 5 the printing steps II and III have been explained. In the example of Fig. 5 For example, the pressure intensity is reduced in each case when the inclination angle α is greater than 30 ° and is zero at α = 45 °.

Fig. 6 provides a plan view of a developed surface, for example, of the component 10 according to Fig. 3 with the same length formation of the side regions 20 and 20 '. The meanings of x ₁ , x ₂ and y ₁ , y ₂ respectively correspond to those of FIG Fig. 1 , With the x ₁ and y ₁ , those surface parts are designated, which are printed in the respective printing process x and y (there are two mutually rotated by 180 degrees printing operations y) with an intensity of 100%, that is, all the colors of which, for example a decor is composed, based on the relative movement in the direction of x or y is 100% delivered. In the difference range between x ₁ and x ₂ as well as y ₁ and y ₂ , the respective ink application is reduced from 100% to 0%, whereby this reduction can be directly proportional decreasing with respect to the inclination angle or the linear relative movement distance.

Fig. 7 to 9 show examples according to which the printing steps I and II according to Fig. 1 can be controlled.

Fig. 7 shows an example in which the surface part which is printed with decreasing intensity in step I completely overlaps that surface part which is printed in full intensity in step II and vice versa, the surface part which is printed with decreasing intensity in step II, overlaps the part printed in step I with full intensity.

Fig. 8 Fig. 14 shows a case where the respective surface portions printed with decreasing intensity overlap but are not congruent.

Fig. 9 shows the case in which the surface parts, which are each printed with decreasing intensity, are congruent.

The figures according to Fig. 7 to 9 are for the surface of the component according to Fig. 6 each to be presented twice, ie to the respective Fig. 7 to 9 joins the Fig. 6 to the left mirror the same figure again.

It is advantageous if with increasing circumferential angle over which the transition region 18 extends, the overlap in the sense of Fig. 9 to Fig. 7 increases.

Based on Fig. 10 is below under a similar consideration as in Fig. 1 explains how to achieve a print intensity on the transition region 18 in the printing steps I (relative movement between the print head and the first surface region 16 in the x direction) and the printing step II (relative movement between the print head and the second surface region 20 in the y direction) , which leads to a constant pressure intensity over the entire transition region 18.

The geometry of the pattern to be created in the transition region 18 can be transformed in a manner known per se by distorting the pattern data used for the control according to the angle α such that the pattern is printed undistorted in spite of the linear relative movement.

vergrößert ist. Damit die Druckintensität, die nur durch den Druckvorgang I auf dem Übergangsbereich 18 erzeugt wird, konstant bleibt, gilt also: $$I\left(\alpha \right)=\frac{I_0}{\cos \alpha },$$

wobei I₀ die auf dem ersten Oberflächenbereich 16 zu erzielende Druckintensität ist, und α der der jeweiligen Stelle des Übergangsbereiches zugehörende Winkel α ist. α kann in einfacher Weise in x umgerechnet werden, da gilt: $$x=r\cdot \sin \alpha \mathrm{.}$$

For the printing operation I, when the angle α is the angle between the perpendicular through the center line P of the surface of the transition portion 18 and the connecting line between the center line and the foot-point line into which a vertical intersects the transition region 18 by the print head 22 located at the position x, that a surface area f of the transition region relative to a surface area f ₀ in the relative movement plane of the print head 22 by the amount $\frac{1}{\cos \alpha }$

is enlarged. Thus, the pressure intensity, which is only generated by the printing process I on the transition region 18, remains constant, then applies: $$I\left(\alpha \right)=\frac{I_0}{\cos \alpha }.$$

where I _{0 is} the pressure intensity to be achieved on the first surface area 16, and α is the angle α associated with the respective location of the transition area. α can be converted into x in a simple way, since the following applies: $$x=r\cdot \sin \alpha \mathrm{,}$$

In order to produce a constant pressure intensity on the transition region 18 in the angular range from α = 0 to α ₁ , the intensity I (α) must therefore increase in accordance with the above-mentioned relationship.

wobei die vorgenannte Beziehung für α₁ < α₂ gilt und f(α) eine Funktion ist, die bei α₁ den Wert 1 und bei α₂ den Wert Null hat.If the part of the transition region 18 which is printed in the printing process I and in the printing process II lies between the angles α ₁ and α ₂ , the pressure intensity between α ₁ and α ₂ must decrease to zero, that is to say: $$I\left(\alpha \right)=f\left(\alpha \right)\cdot \frac{I_0}{\cos \alpha }.$$

wherein the aforementioned relationship for α ₁ <α ₂ and applies f (α) is a function having the value 1 and α ₂ is set to zero at α. ₁

wobei $$f_1\left(\alpha 1\right)=f_2\left(\alpha 2\right)=1,$$

$$f_1\left(\alpha 1\right)=f_2\left(\alpha 2\right)=0.$$

Mit der vorstehenden Beziehung wird erreicht, dass die Druckintensität von α = 0 nach α = 1 (von x₀ zu x₁) im Druckschritt 1 zunächst proportional zu $\frac{1}{\cos \alpha }$

zunimmt und dann von x₁ zu x₂ (α₁ zu α₂) auf Null abnimmt und umgekehrt die Druckintensität im Schritt II zunächst von 90 Grad zu α₂ umgekehrt proportional zu sin α zunimmt, um dann von α₂ nach α₁ auf Null abzunehmen, wobei die Summenintensität, mit der jedes Flächenelement des Übergangsbereiches 18 resultierend aus beiden Druckvorgängen bedruckt wird, konstant gleich I₀ ist.In the pressure step II, the aforementioned relationships apply in the same way, wherein 90 ° -α is to be set for the value α, ie, the cosine must be replaced by the sine. In order to In the range α ₁ and α _2, the pressure intensity remains constant when superimposing the pressure steps I and II, then the following relationship must apply: $$f_1\left(\alpha \right)\cdot \frac{I_0}{\cos \alpha }+f_2\left(\alpha \right)\cdot \frac{I_0}{\sin \alpha }={\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="imgf0001.png"\; state="\{\{state\}\}">I</figure-callout>}}_0.$$

in which $$f_1\left(\alpha 1\right)=f_2\left(\alpha 2\right)=1.$$

$$f_1\left(\alpha 1\right)=f_2\left(\alpha 2\right)=\mathrm{0th}$$

With the above relationship, it is achieved that the pressure intensity from α = 0 to α = 1 (from x ₀ to x ₁ ) in the pressure step 1 is initially proportional to $\frac{1}{\cos \alpha }$

increases and then decreases from x ₁ to x ₂ (α ₁ to α ₂ ) to zero and vice versa, the pressure intensity in step II first of 90 degrees to α ₂ inversely proportional to sin α increases, then from α ₂ to α ₁ to zero The sum intensity with which each surface element of the transition region 18 is printed as a result of both printing operations is constantly equal to I ₀ .

With a control according to the above relationships, a constant pressure intensity over the curved transition region can be achieved. With a control according to the particular Fig. 7 to 9 the intensity is almost constant.

Fig. 11 shows the basic structure in an apparatus for performing the method according to the invention.

The printhead 22, which is designed, for example, as a bar, is attached to a drive device 30 with which the print head 22 can be moved in the direction of the vertical double arrow W. Opposite the print head is the component 10 to be printed, which is held by a drive device 32, by means of which it is movable in the direction of the horizontal double arrow Z and in the direction of the double arrow R about an axis perpendicular to the paper plane axis.

The position of the component 10 relative to a stationary reference point can be detected by means of a sensor device 34.

To control the drive means 30, 32 and the ink nozzles of the print head 22, an electronic control device 36 with a control panel 38 and a screen 40 is provided. The electronic control device 36 includes a microprocessor with program and data storage and is known per se in construction and will therefore not be explained in detail.

If the print head 22 does not extend over the entire width of the component 10 to be printed, it can advantageously also be moved in a direction perpendicular to the plane of the paper by means of the drive device 30. The drive device 32, by means of which the component 10 can be pivoted, can also be designed such that the component 10 can be pivoted about three mutually perpendicular spatial axes. The drive devices 30 and 32 can be designed in many different ways, wherein it must be ensured that the relative movements necessary for carrying out the method according to the invention are possible between the print head 22 and the component 10.

LIST OF REFERENCE NUMBERS

10

component

12

bottom

14

page

16

first surface area

18

Transition area

20

second surface area

22

printhead

24

edge

26

edge

28

edge

30

driving means

32

driving means

34

sensor device

36

electronic control device

38

Control panel

40

screen

Claims (8)

1. A method of printing a component (10) using an ink-jet printing process, which component has a first and a second surface region (16,20), which are inclined at an angle to one another and are joined together via a transition region (18), comprising the following steps:

   I) Printing the first surface region (16) and at least one part of the transition region (18) adjoining the first surface region, but not the second surface region (20), during a first linear relative movement between the first surface region and a print head (22) approximately parallel to the first surface region, wherein the print head sprays colouring fluid in a direction approximately perpendicular to an extension direction of the first surface region and perpendicular to the direction of the relative movement,

   II) Printing the second surface region (20) and also at least one part of the transition region (18) adjoining the second surface region, but not the first surface region (16), during a second linear relative movement between the second surface region and a print head (22) approximately parallel to the second surface region, wherein the print head sprays colouring fluid in a direction approximately perpendicular to an extension direction of the second surface region and perpendicular to the direction of the relative movement,

   characterised in that
   the printing fluid emerging from the print head (22) is controlled so that at least the part of the transition region (18), which is inclined to the greatest extent in relation to the direction of the first or second relative movement, is printed only during the step in which it has the smaller inclination in relation to the respective relative movement, and
   the quantity of fluid sprayed per section of the respective relative movement gradually decreases to nil in each one of the steps I) and II) during the printing of one part of the transition region (18), which part is also printed at least partly in the respective other one of the steps I) and II).
2. A method according to Claim 1, wherein the part of the transition region (18), in which the printing during step I) gradually decreases to nil, is situated outside the part of the transition region in which the printing in step II) gradually decreases to nil.
3. A method according to Claim 1, wherein the part of the transition region (18), in which the printing during step I) gradually decreases to nil, overlaps the part of the transition region in which the printing in step II) gradually decreases to nil.
4. A method according to Claim 3, wherein the part of the transition region (18), in which the printing during step I) gradually decreases to nil, coincides with the part of the transition region in which the printing in step II) gradually decreases to nil.
5. A method according to any one of Claims 1 to 4, wherein the printing is controlled in such a way that the first and the second surface regions (16,20) and also the transition region (18) are printed at equal intensity.
6. A method according to any one of Claims 1 to 5, wherein the surface regions (16,20) are planar and are directed approximately perpendicularly to one another, and the transition region (18) is a cylinder segment with an angle at circumference of approximately 90 degrees and continuously adjoins the surface regions (16,20).
7. A method according to any one of Claims 1 to 6, wherein the printing is controlled in such a way that a geometry of patterns printed on the transition region (18) during the steps I) and II) is the same.
8. An apparatus for printing a component with an ink-jet printing process, which component has a first and a second surface region (16,20), which are inclined at an angle □ to one another and are joined together via a transition region (18), which apparatus comprises:

   at least one print head (22),

   a retaining device (32) for retaining the component (10),

   a conveying device (30,32) for generating a linear relative movement between the component and the print head,

   a device (34 for detecting the angle between the direction of the relative movement and the surface of the transition region (18) and

   a control device (36) which controls the conveying device (30,32), the pivoting device (32) and the print head (22),

   characterised in that the apparatus additionally comprises a pivoting device (32) for pivoting the component relative to the print head about an axis perpendicular to the direction of the relative movement, and in that the control device (36) controls the conveying device (30,32), the pivoting device (36) [sic] and the print head (22) in such a way that the following steps are executed:

   I) Printing the first surface region (16) and at least one part of the transition region (18) adjoining the first surface region, but not the second surface region (20), during a first linear relative movement between the first surface region and a print head (22) approximately parallel to the first surface region, wherein the print head sprays colouring fluid in a direction approximately perpendicular to an extension direction of the first surface region and perpendicular to the direction of the relative movement,

   II) Printing the second surface region (20) and also at least one part of the transition region (18) adjoining the second surface region, but not the first surface region (16), during a second linear relative movement between the second surface region and a print head (22) approximately parallel to the second surface region, wherein the print head sprays colouring fluid in a direction approximately perpendicular to an extension direction of the second surface region and perpendicular to the direction of the relative movement, wherein

   the printing fluid emerging from the print head (22) is controlled so that at least the part of the transition region (18), which is inclined to the greatest extent in relation to the direction of the first or

   second relative movement, is printed only during the step in which it has the smaller inclination in relation to the respective relative movement, and

   the quantity of fluid sprayed per section of the respective relative movement gradually decreases to nil in each one of the steps I) and II) during the printing of one part of the transition region (18), which part is also printed at least partly in the respective other one of the steps I) and II).

Images