EP4019216A1

EP4019216A1 - Method and installation for working a wooden surface

Info

Publication number: EP4019216A1
Application number: EP21217283.7A
Authority: EP
Inventors: Carl De Deurwaerder
Original assignee: Houthandel Leirman En Zonen bvba
Current assignee: Houthandel Leirman En Zonen bvba
Priority date: 2020-12-23
Filing date: 2021-12-23
Publication date: 2022-06-29
Also published as: BE1028944B1; BE1028944A1

Abstract

According to the method of the invention, a wooden workpiece (1) is moved along a cylindrical planing head (2) which rotates about its central axis and is provided with at least one plane blade (3) which extends along the outside of the planing head and in the longitudinal direction thereof, wherein the plane blade has a cutting edge (4) which forms the intersection line between a front cutting face (5) and a rear cutting face (6) of the blade, such as determined by the direction of rotation of the planing head, and wherein the workpiece (1) moves in in a direction opposite to the movement of the plane blade (3) during the interaction with the plane blade. According to the invention, the angle (α) between the front cutting face (5) and the surface (7) of the workpiece is an acute angle for the entire duration of the interaction between the plane blade and the surface (7). The invention also relates to a planing installation provided with a planing head (2) as described above when the planing head works a workpiece (1) in the installation. The specific angle between the front cutting face (5) and the surface to be worked (7) makes it possible to give the surface a weathered appearance. Preferably, this angle is combined with a cutting edge (4) provided with grooves (21).

Description

Field of the invention

The invention relates to working wooden workpieces, in particular the mechanical planing of wood for the purpose of modifying the appearance of the surface.

Prior art

The mechanical planing of wood can be effected in various ways, inter alia by using a rotating planing head. The latter has a cylindrical body to which one or more blades are fitted which project with respect to the outer wall of the cylindrical body. The head rotates about an axis and a wooden plank or beam is passed underneath the rotating head in a direction opposite to the direction of rotation of the planing head.
It is known to use mechanical planing techniques in order to give a wooden surface a specific appearance, for example to give a smooth planed plank the appearance of weathered or manually planed wood. Examples of these mechanical surface treatments are described in documents US2012/192996 and US4949768 . However, many of these techniques produce an artificial result or they require a complicated machine comprising several fixed (non-rotating) planing heads distributed across the width of the surface which is fed through or a combination of rotating and non-rotating heads, as is the case in document US2012/192996 . In US4949768 , rotating heads are used, but for a specific purpose, namely for producing local cavities in the surface of a wooden beam to give the impression as if the beam has been worked by hand.
However, no technique is known which can produce a rough and weathered appearance on a wooden surface quickly and efficiently using a relatively simple or standard installation.

Main aspects of the invention

The invention relates to a method and installation for working a wooden surface, as described in the attached claims. According to the method of the invention a wooden workpiece is moved along a cylindrical planing head which rotates about its central axis and is provided with at least one plane blade which extends along the outside of the planing head and in the longitudinal direction thereof, wherein the plane blade has a cutting edge which forms the intersection line between a front cutting face and a rear cutting face of the blade, as determined by the direction of rotation of the planing head, and wherein the workpiece moves in a direction opposite to the movement of the plane blade during the interacting with the plane blade. According to the invention, the angle between the front cutting face and the surface to be worked is an acute angle for the entire duration of the interaction between the plane blade and the surface. The angle in question is the angle between the outside of the front cutting face and the surface to be worked which extends in front of this cutting face as the cutting edge interacts with the surface. This angle is denoted as the angle 'α' in Figs. 2a and 2b. The invention also relates to a planing installation provided with a planing head as described above when the planing head works a workpiece in the installation.
The specific angle between the front cutting face and the surface to be worked makes it possible to give the surface a rough appearance. Preferably, this angle is combined with a cutting edge provided with grooves. The properties of a number of further embodiments are described in the claims.

Brief description of the figures

Fig. 1 shows a 3D image of the position of a planing head with respect to a workpiece, as utilized according to an embodiment of the invention.
Figs. 2a and 2b show in detail how the plane blade moves with respect to the workpiece according to an embodiment of the invention.
Figs. 3a and 3b show the angular positions for a conventional planing process for comparison with Figs. 2a/2b.
Fig. 4 shows a planing head with blades which are provided with grooves, as used in an embodiment of the method according to the invention.
Fig. 5 is an example of the appearance of a wooden plank worked according to the method of the invention.
Fig. 6 shows a few components of a planing installation according to an embodiment of the invention.

Detailed description of the invention

Fig. 1 shows a cylindrical planing head 2 and a wooden plank 1 which is moved along the rotating head when carrying out the method according to the invention. The direction of rotation of the head 2 and the feed direction of the plank 1 are indicated by arrows. A cylindrical planing head is known per se. It contains a central axis 10 which is mounted in a planing machine (not shown), in which the rotation of the head 2 about the geometric axis of rotation 20 is driven. The figure shows an example of the shape of the body of the planing head, comprising two diametrically opposite round side walls 15 and two diametrically opposite flat side walls 16, with two planing blades 3 being fitted in the corners between adjoining round and flat walls. However, the shape of the planing head 2, the number of planing blades 3 and the way in which the blades 3 are fitted may differ from that shown in the illustration and is therefore no limitation with regard to the scope of the invention.
What does define the invention is the position of the planing blades 3 with respect to the surface to be worked. Figs. 2a and 2b show one of the planing blades 3 as applied in the method according to the invention in more detail. Every blade 3 has a cutting edge 4 which forms the intersection line between a front cutting face 5 and a rear cutting face 6. Here, the terms 'front' and 'rear' are not used in relation to the movement of the blade 3 with respect to the workpiece 1, and therefore not in relation to the direction of rotation of the planing head 2: the front side 5 is situated in front of the rear side 6 viewed in the direction of movement of the blade 3.
During one rotation of the planing head 2, the blade interacts with the surface 7 of the workpiece. This is a flat surface which is moved along the rotating head in a rectilinear movement. The interaction between the blade 3 and the surface 7 occurs during an angular displacement of the planing head 2 which is determined by the dimensions of the head 2 and the blade 3. Fig. 2a shows the moment at which the interaction starts: the cutting edge 4 makes contact with the surface 7 to be worked. At that moment, the angle α between the front cutting face 5 and the surface 7 to be worked is an acute angle, i.e. an angle smaller than 90°. The adjacent angle β is an obtuse angle. Fig. 2b shows the end point of the interaction. The interaction between the blade 3 and the workpiece 1 has produced a worked zone 8, whose shape and depth depends on various factors, including the relative speed of the workpiece 1 with respect to the rotating plane blade 3. It can be seen that, at the end of the interaction, the angle α is still an acute angle is, and β is still an obtuse angle.
This configuration of the angles, in other words, the fact that the angle α is acute (and the angle β obtuse) for the entire duration of the interaction is characteristic of the method of the invention and differs from the conventional configuration, which is illustrated in Figs. 3a and 3b. In the latter, the position of the blade 3' and of the cutting edges 5' and 6' clearly differs from the situation in Figs. 2a and 2b. With the conventional process, α varies between an acute angle at the start of the interaction and an obtuse angle at the end (and β varies between obtuse and acute) as a result of which the blade 3' has a greater impact on the workpiece in the zone 8'. According to the method of the invention, this impact is reduced. The blade performs more of a rubbing action on the surface than a cutting action. This makes it possible to give the surface 7 a weathered appearance.
According to a preferred embodiment, the method of the invention is carried out using a planing head with a cutting edge provided with grooves 21, as is illustrated in Fig. 4. The grooves preferably form a regular profile of equally sized grooves 21, such as a sawtooth profile. The dimensions (height and width) of the grooves 21 is, for example, in the order of magnitude of half a millimetre. Preferably, the entire rear cutting edge 6 is provided with a regular profile of grooves which are perpendicular to the cutting edge 4 and extend as far as the cutting edge, as is illustrated in Fig. 4. These grooves 21 further contribute to giving the wood surface a weathered appearance. In particular, they produce a ribbed appearance, which is typical of so-called scaffolding wood. Fig. 5 shows the surface of a plank which has been worked according to the method of the invention and using a cutting edge 4 with a regular profile of grooves 21, as shown in Fig. 4. The ribs 22 produced by the grooves 21 can be seen, as well as the typical fraying 23 of the wood along the woodgrain. The latter effect is more likely to have been caused by the specific angular position of the planing blades 3 as described above.
As has already been mentioned before, the angles α and β are respectively acute and obtuse for the entire duration of the interaction between the blade 3 and the surface 7. If the planing head 2 comprises several blades 3, as is the case with the planing head illustrated in Figs. 1 and 4, this is also the case for each of the blades 3.
For the duration of the interaction between the blade 3 and the surface, the angle α is preferably between 75° and 88°. According to a more specific embodiment, the angle α is between 85° and 87° for the duration of the interaction. The limits of all ranges which are referred to in this description by 'between' comprise the limiting values of the ranges. The angle between the cutting faces 5 and 6 with respect to each other is preferably an acute angle.
In the method according to the invention, the rotational speed of the planing head 2 is preferably lower than in conventional planing processes. According to one embodiment, this speed is between 1000 rpm (revolutions per minute) and 4000 rpm. Still more preferably, the speed is between 2000 rpm and 2500 rpm. At speeds below 1000 rpm, the planing head may jam with certain types of wood when the blade moves along hard portions in the wood. At speeds of more than 4000 rpm, the surface of most types of wood becomes too smooth. These speeds are generally lower than with standard processes which are carried out using a planing head as shown in Figs. 3a and 3b, in which speeds of 10.000 rpm and higher are used.
The throughput speed of the wooden workpiece 1 along the rotating planing head 2 which is used with the method of the invention is preferably between 10 m/min and 25 m/min. For some types of wood, a speed of 15 m/min is ideal. These speeds are also lower than is the case with the conventional planing processes.
The method is preferably applied to the entire width of a workpiece, measured in the length direction of the planing blades 3. In other words: preferably only workpieces such as planks or beams which are narrower than the length of the planing blades are worked. As a result thereof, the weathered appearance is uniform across the entire surface of the plank or beam.
According to a preferred embodiment, the planing treatment according to the invention is followed by a brushing treatment which is known per se from the prior art and is preferably carried out by a rotating brush head similar to the planing head, but provided with brushes along its periphery. Brushing the surface results in a smoother appearance, where desired, as a result of the fact that it removes loose fibres. However, the brushing operation is optional and may be omitted, depending on the desired degree of roughness.
The invention also relates to an installation which is suitable for carrying out the method according to the invention according to one or more of the above-described embodiments. One example of such an installation is illustrated in Fig. 6. A pair of driven feed-through rollers 11 enables a plank 1 to be moved in its length direction. The planing head 2 with angular properties with respect to the plank as described above is arranged in a sleeve 24 and rotates about its geometric axis in the direction indicated. The installation in Fig. 6 furthermore comprises a brushing machine 12 which is known per se and in which a brush head 25 rotates about an axis running parallel to the axis of the planing head 2. The installation may contain various additional components which are known per se and are therefore not described in detail here, such as for example: sawing and/or conventional planing devices upstream of the planing head 2 for shaping a plank to a desired thickness and width or to provide the sides of the plank with tongue and groove profiles.

Claims

Method for giving a flat surface (7) of a wooden workpiece (1) a rough appearance, wherein the workpiece is moved along a cylindrical planing head (2) which rotates about its central axis (10) and is provided with at least one plane blade (3) which extends along the outside of the planing head and in the longitudinal direction thereof, with the plane blade having a cutting edge (4) which forms the intersection line between a front cutting face (5) and a rear cutting face (6) of the blade, as determined by the direction of rotation of the planing head (2), and wherein the workpiece moves in a direction opposite to the movement of the plane blade during the interaction with the plane blade, characterized in that the angle (a) between the front cutting face (5) and the surface (7) is an acute angle for the entire duration of the interaction between the plane blade (3) and the surface (7).
Method according to Claim 1, wherein the length of the cutting edge (4) is greater than or equal to the width of the surface to be treated, as measured in the length direction of the cutting edge (4) during the planing operation.
Method according to Claim 1 or 2, wherein the cutting edge (4) is provided with grooves (21).
Method according to Claim 3, wherein the entire length of the rear cutting face (6) is provided with a regular profile of grooves (21) which extends as far as the cutting edge (4).
Method according to one of the preceding claims, wherein said angle (a) is between 75° and 88° for the entire duration of the interaction between the plane blade (3) and the surface (7).
Method according to Claim 5, wherein said angle (a) is between 85° and 87° for the entire duration of the interaction between the plane blade (3) and the surface (7).
Method according to one of the preceding claims, wherein the rotational speed of the planing head (2) is between 1000 and 4000 revolutions per minute.
Method according to Claim 7, wherein the rotational speed is between 2000 and 2500 revolutions per minute.
Method according to one of the preceding claims, wherein the feed rate of the workpiece (1) with respect to the rotation axis (10) of the planing head (2) is between 10 and 25 metres per minute.
Method according to one of the preceding claims, wherein the planing operation is followed by a brushing operation of the surface.
Planing installation for giving a flat surface (7) of a wooden workpiece (1) a rough appearance, wherein the installation comprises the following components:
- at least one pair of throughput rollers (11) for moving a workpiece (1) at an adjustable speed,

- a cylindrical planing head (2) provided with at least one plane blade (3) which extends along the outside of the planing head and in the longitudinal direction thereof, wherein the plane blade has a cutting edge (4) which forms the intersection line between a front cutting face (5) and a rear cutting face (6), as determined by the direction of rotation of the planing head,
characterized in that the plane blade (3) is configured such that the angle (a) between the front cutting face (5) and the surface (7) is an acute angle for the entire duration of the interaction between the plane blade (3) and the surface (7).
Installation according to Claim 11, wherein the cutting edge (4) is provided with grooves (21).
Installation according to Claim 11 or 12, wherein said angle (a) is between 75° and 88° for the entire duration of the interaction between the plane blade and the surface.
Installation according to Claim 13, wherein said angle (a) is between 85° and 87° for the entire duration of the interaction between the plane blade and the surface.
Installation according to one of Claims 11 to 14 which furthermore comprises a machine (12) for brushing the workpiece immediately after the planing operation.