WO2021239865A1

WO2021239865A1 - Device and method for treating, in particular finishing, surfaces

Info

Publication number: WO2021239865A1
Application number: PCT/EP2021/064170
Authority: WO
Inventors: Max FEIDIKER
Original assignee: Homag Bohrsysteme Gmbh
Priority date: 2020-05-29
Filing date: 2021-05-27
Publication date: 2021-12-02
Also published as: DE102020114477A1

Abstract

The invention relates to a device and a method for finishing, in particular smoothing, a face of a workpiece by removing or reducing protrusions, such as for example protruding fiber ends, by means of laser radiation.

Description

DEVICE AND METHOD FOR PROCESSING, IN PARTICULAR FOR FINISHING, OF SURFACES

Technical area

The invention relates to a device and a method for processing, in particular for finishing, a surface of a workpiece.

State of the art

The pre- or post-processing of a surface of a workpiece, in particular its smoothing, is usually carried out by mechanical processing methods such as planing, grinding or polishing. Such cutting or abrasive processes have been known for a long time and have proven themselves for a large number of applications.

Nevertheless, these methods are also associated with disadvantages that hinder or even prevent their applicability for technical or economic reasons. A disadvantage can be a relatively high tool wear, which leads to the processing quality deteriorating over time and the processing tool (e.g. the plane iron) having to be replaced or re-sharpened at regular intervals. Another disadvantage of mechanical processes is the development of chips or dust, which can lead to further problems, for example complex measures to remove the chips. In addition, the mentioned methods, especially in automated form, are often unsuitable for smoothing surfaces in areas that are difficult to access or more complex geometries due to the size of the corresponding processing tools (planes, brushes, sandpaper, PoH sponges, etc.).

Another disadvantage lies in the manipulation of the workpiece surface, since it cannot be avoided in any of the methods mentioned that at least a thin layer of the workpiece surface is removed together with the protruding unevenness, so that the

This changes the workpiece geometry at least slightly. In addition, the surface properties can change in an undesirable way, e.g. by sealing the surface with grinding dust or polishing paste.

In addition to mechanical processing methods, there are non-contact processing methods for remuneration of

Surfaces, for example by carbonizing or laser engraving. During carbonization, workpieces based on organic materials, especially wood, are usually briefly exposed to high temperatures by scarfing, so that the top layer of the surface is carbonized, while with laser engraving a three-dimensional relief is "burned" into the workpiece surface.

Presentation of the invention

The invention aims to provide a device and a method to reduce the roughness of a surface of a workpiece without impairing the workpiece surface itself.

The invention provides a corresponding device. Further embodiments are listed in the dependent claims. The invention also relates to a method. Features of the method and other embodiments thereof can be used in the context of the device. The same applies to features of the device and its preferred development, which can be used in the context of the method.

The device according to the invention is particularly suitable for machining a surface of a fibrous or fiber-containing workpiece. The workpiece preferably consists at least partially of an organic material, such as wood, or can be composed of different materials. Furthermore, the device can be used for machining workpieces which have plastic at least in sections. By means of the device according to the invention, the workpiece can be further refined or prepared for subsequent processing.

The device comprises a workpiece receiving unit for receiving (at least) one workpiece, a processing area in which the workpiece is processed, an energy source for generating laser radiation, an energy line for forwarding the laser radiation to the processing area, (at least) one drive unit for bringing about it a relative movement between the focus of the laser radiation and the workpiece receiving unit, as well as a control unit for controlling the relative movement. Further it is provided that the control unit is set up to direct the laser radiation onto the processing area in such a way that it essentially only acts on protrusions, such as protruding fibers, impurities and / or (other) (undesired) elevations that emerge from the surface of a ( in the processing area) of the workpiece protrude, in particular by setting the focus and the amount of energy of the laser radiation introduced per unit of area and time in a suitable manner.

It should be noted that several lasers can also be used, that the energy string can comprise several separate optical elements, such as mirrors and / or lenses, that the energy source and the energy string can be present separately and combined in one unit, that the focus the laser radiation can be punctiform or linear and the relative movement between the focus and the workpiece receiving unit can take place by moving the focus, moving the workpiece receiving unit, or by a combination of both movements.

In a preferred embodiment, the focus can be moved in all three dimensions with the aid of one or more movable mirrors and / or lenses. In particular, the drive unit is set up to move the at least one mirror and / or the at least one lens.

The workpiece receiving unit can include a conveying device with the aid of which the workpiece can be moved in the horizontal direction. By slightly tilting the mirror around the X or Y axis, the focus can be moved essentially horizontally. In contrast to a transverse movement, it should be noted with this type of movement that the distance between the focus and the workpiece surface and the angle of incidence of the laser radiation on the workpiece surface depend on the horizontal The position of the focus changes slightly and has to be compensated if necessary.

The invention has the particular advantage that surfaces of workpieces can be freed of unevenness in a precise and efficient manner, with the workpiece surfaces themselves remaining virtually untouched. This is made possible by the fact that the laser radiation acts essentially, or essentially only, on protruding bumps, protruding fibers, or the like, as a result of which these are removed from the workpiece surface or at least reduced or shortened.

In contrast to mechanical smoothing processes such as planing, grinding or polishing, which also have a cutting or abrasive effect on the surface of the workpiece, in the process according to the invention there is no chip or dust formation and tool wear is negligible. The first-mentioned advantage also applies compared to other non-contact surface finishing processes, such as carbonizing or laser engraving, in which the surfaces of the workpieces in question are significantly changed. Due to the comparatively low energy input required per unit area, the machining can also be carried out with lower laser power and / or higher speed, whereby the productivity of the machining process can be increased overall. The laser power is preferably in the range between 0.03 and 5 kW and the processing speed in the range between 250 and 20,000 mm / s.

Further advantages are the ease with which the machining process can be automated as well as the possibility of efficiently and with high precision, even workpieces with complex geometries that do not allow smoothing in a known manner, e.g. by planing, grinding or polishing, or only with great effort to smooth. In addition, the method according to the invention can be combined with other processing methods, in particular with laser-based methods such as cutting or engraving and with machining methods such as milling or drilling, to name just a few examples. For this purpose, the device according to the invention can either be set up separately next to a second processing machine or (at least partially) integrated into it.

Brief description of the drawings

Further features and advantages of a device, a use and / or a method emerge from the following description of embodiments with reference to the accompanying drawings. From these drawings shows:

Fig. 1 is a schematic representation of an apparatus according to a first embodiment of the invention.

Fig. 2 is a schematic representation of an apparatus according to a second embodiment of the invention.

Fig. 3 is a schematic representation of an apparatus according to a third embodiment of the invention.

4 is a schematic representation of an apparatus according to a fourth embodiment of the invention.

FIG. 5 is a schematic illustration of the processing area for explaining a use of a device according to one of the aforementioned embodiments.

Fig. 6 is a schematic representation of the processing area to explain an alternative use of a device according to one of the aforementioned execution forms. 7 is a schematic representation of the integration of the method according to a first to third embodiment of the invention in a two-stage machining process.

8 is a schematic illustration of the integration of the method according to a first to third embodiment of the invention in a two-stage machining process.

Description of embodiments

The same reference symbols, which are listed in different figures, designate identical, corresponding, or functionally similar elements.

Preferred embodiments of a device according to the invention are described with reference to the accompanying figures. Modifications of individual features mentioned in this context can each be combined individually in order to form further embodiments of the invention. Although the device described below and the corresponding method are to be understood as purely exemplary and not restrictive, features of the embodiment described can also be used to further characterize the device and the method mentioned in the claims.

In FIG. 1, a device according to a first embodiment is shown schematically, with which a surface of a workpiece, in particular a fibrous or fiber-containing workpiece, can be smoothed by laser radiation. For example, it concerns workpieces which at least partially consist of wood, wood-based materials or composite materials, in particular of chipboard, MDF boards or the like. The device 12a comprises a workpiece receiving unit 2 (for example a machine table) which can receive a workpiece 1 which lies there and / or is held by a corresponding device (not shown). In an energy source 4, laser radiation 5 is generated with a certain intensity, which is conducted via an energy string 6 to the processing area 3, where the focus 8 of the laser radiation strikes the workpiece 1.

A first drive unit 7a moves the energy string 6 and thus the focus 8 of the laser radiation essentially in a horizontal X / Y plane (possibly also in the Z direction) relative to the workpiece 1 Laser radiation 5 striking workpiece 1, in particular by means of movable mirrors in energy string 6. A second drive unit 7b moves the workpiece receiving unit 2 and thus the workpiece 1 in the vertical Z direction (possibly also in the horizontal Y direction) relative to the focus 8 of the laser radiation. The focus 8 can also be fine-tuned using the energy string 6. Both drive units 7a, 7b and the power of the energy source 4 are controlled by a control unit 9 in order to set the desired relative movement or laser power.

Figure 2 shows schematically a device 12b according to a second embodiment, which differs from the first embodiment in that the focus 8 of the laser radiation can be moved through the energy strand 6 in all three directions (X / Y / Z), whereas the workpiece Recording unit 2 is immobile. Therefore, only one drive unit 7a is required in this embodiment. With regard to further features of the device according to the second embodiment, reference is made to the explanations relating to the first embodiment. FIG. 3 schematically shows a device 12c according to a third embodiment, which differs from the first embodiment in that the focus 8 of the laser radiation is immobile, whereas the workpiece receiving unit 2 can be moved in all three directions (X / Y / Z) . Therefore, only one drive unit 7b is required in this embodiment as well. With regard to further features of the device according to the third embodiment, reference is made to the explanations relating to the first and / or second embodiment.

FIG. 4 schematically shows a device 12 according to a fourth embodiment, in which the device 12 is integrated into a machine 14 and is combined with other devices 13, in particular for machining. Depending on the design of the machine 14, the device 12 can also be only partially integrated, e.g. by positioning the energy source 4 outside the machine 14 or by using the already existing workpiece holding unit of the machine. With regard to further features of the device according to the fourth embodiment, reference is made to the explanations of the previous embodiments.

FIG. 5 schematically shows an enlargement of the processing area 3 to explain a use of a device according to one of the aforementioned embodiments. The laser radiation 5 strikes the workpiece surface 11 at an angle f, preferably at an approximately right angle, from which individual protrusions 10, in particular fiber ends, protrude. The focus 8 of the laser radiation is set in such a way that it moves over the workpiece surface 11 at a defined distance d in the X / Y plane, the distance d preferably being smaller than the maximum height h of the protrusions 10. Depending on the material, processing speed and intensity of the laser radiation, the latter are completely or partially burned, vaporized and / or fused so that the workpiece surface 11 passes through Removal or reduction of protruding bumps is smoothed. Since the focus 8 is always at a distance d from the workpiece surface 11, the latter is not or hardly influenced by the incident laser radiation 5.

FIG. 6 schematically shows an enlargement of the processing area 3 to explain an alternative use of a device according to one of the aforementioned embodiments, the laser radiation 5 striking the protrusions 10 essentially parallel to the workpiece surface 11. One advantage of this embodiment is that the undesired effect of the laser radiation on the workpiece surface 11 can thus be further reduced. In a corresponding device (not shown), the workpiece is preferably held rotated by 90 °. In addition, the angle of incidence f can in principle assume any value between 0 ° and 180 °, preferably between 30 ° and 150 °. The distance d between the focus 8 and the workpiece surface 11 is preferably between 1.0 μm and 1.0 mm.

FIGS. 7 and 8 schematically show two alternatives for integrating the device 12 according to the invention and the method according to the invention in a machining process, with a separate device 13 performing a previous or subsequent machining, in particular machining. In contrast to the fourth embodiment, the respective processing steps take place separately in terms of time and space.

It is evident to the person skilled in the art that individual features, each described in different embodiments, can also be implemented in a single embodiment, provided that they are not structurally incompatible. Likewise, various features that are described in the context of a single embodiment can also be provided in several embodiments individually or in any suitable sub-combination.

Claims

235 637 pl / lfr CLAIMS

1. A device for processing at least one area of a surface of a workpiece by means of laser radiation, comprising: a workpiece receiving unit (2) which is set up to receive a workpiece (1), an energy source (4) which is set up, laser radiation (5 ) to generate an energy string (6) which is set up to guide the laser radiation (5) from the energy source (4) to a processing area (3), at least one drive unit (7a, 7b) which is set up to move a relative movement between a focus (8) of the laser radiation and the workpiece receiving unit (2), a control unit (9) which is set up to control the relative movement between the focus (8) of the laser radiation and the workpiece receiving unit (2), characterized that the control unit (9) is set up to direct the laser radiation (5) onto the processing area (3) in such a way that the laser radiation essentially only hits the protrusions (10) of the The workpiece.

2. Device according to claim 1, wherein the control unit (9) is set up to adjust the focus (8) of the laser radiation (5) in such a way that the focus (8) is at a distance (d) from the surface (11) a workpiece (1) located in the machining area (3).

3. Device according to claim 2, wherein the distance (d) is smaller than the maximum height (h), preferably smaller than half the maximum height (h), of the protruding protrusions (10).

4. Apparatus according to claim 2 or 3, wherein the distance (d) is greater than 1pm and less than 1mm.

5. Device according to one of claims 1 to 4, wherein the device is set up that the

Laser radiation (5) essentially perpendicular to the

Surface (11) of a workpiece (1) located in the machining area (3) onto a workpiece (1) protruding therefrom

Protrusions (10) meets.

6. Device according to one of claims 1 to 4, wherein the device is arranged that the

Laser radiation (5) at an angle (f) between 30 ° and 150 ° to the surface (11) of a workpiece (1) located in the machining area (3) on protruding parts

Protrusions (10) meets.

7. Device according to one of the preceding claims, wherein the workpiece receiving unit (2) comprises a conveyor device which is set up to move the workpiece (1) horizontally.

8. Device according to one of the preceding claims, wherein the energy strand (6) comprises at least one movable mirror which is set up to move the focus (8) of the laser radiation essentially horizontally.

9. Device according to one of the preceding claims, wherein the device comprises at least one second energy source and at least one second energy string.

10. Processing machine (14), comprising a device according to one of the preceding claims and at least one further processing unit (13), in particular for machining.

11. A method for processing at least one area of a surface of a workpiece by means of laser radiation, comprising:

Guiding laser radiation (5) to a workpiece (1), bringing about a relative movement between the focus (8) of the laser radiation and the workpiece (1), characterized in that the laser radiation (5) is directed onto the processing area (3) in such a way that that the laser radiation (5) essentially only acts on protrusions (10) which protrude from the surface (11) of the workpiece (1).

12. The method according to claim 11, further comprising setting the intensity of the laser radiation (5), in particular as a function of the material, the surface properties and / or the geometry of the workpiece (1).

13. The method according to claim 11 or 12, further comprising the setting of the distance (d) between the focus (8) of the laser radiation (5) and the surface (11) of the workpiece (1), in particular as a function of the material

Surface quality and / or the geometry of the workpiece (1).

14. The method according to any one of claims 11 to 13, further comprising setting the angle of incidence (f) of the laser radiation (5), in particular as a function of the material, the surface properties and / or the geometry of the workpiece (1).

15. The method according to any one of claims 11 to 14, further comprising a previous or subsequent processing by at least one further, in particular cutting, processing method (13).

16. The method according to any one of claims 11 to 15, wherein the protrusions (10) are formed by protruding portions of fibers, impurities and / or elevations.