DEVICE AND METHOD FOR SHAPING A WOODEN OBJECT

Description

technical field

[0001] The present invention relates to a pressing device, according to the preamble of claim 1, and a method of forming a wooden object by pressing, comprising a die and a device as described in claims 1 to 11. Such a pressing device and consequently its use are known from document FR 2 487 252 A1. State of the art

[0002] The manufacturing of wooden objects by compressing a piece of wood in a mold is well known. It generally involves placing a piece of wood, pre-machined or not, in a die possessing a given force, and then applying a compressive force to the piece of wood using a press in order to imprint it with the shape of the die.

[0003] To facilitate the compression of the piece of wood, heat treatments or impregnations (water, resin, etc.) can be carried out.

[0004] The known methods all share the common feature of applying pressure in a direction that is transverse, or even perpendicular, to the wood fibers. The direction of pressure relative to the wood fibers significantly influences the intensity of the force required to compress the wood. Indeed, the force needed to compress wood transversely to the fibers is considerably less than that required for compression parallel to the fibers.

[0005] Document JP2005205676A describes a method for forming wooden objects, particularly wooden cases for electronic devices, by compressing a piece of wood in a mold. The pressing direction is transverse to the wood fibers.

[0006] Document US20050194283A1 also describes a method for forming wooden objects by compressing a piece of wood transversely to the wood fibers in a mold. In this document, the wood requires treatment in a high-temperature, high-pressure steam bath prior to compression.

[0007] The document JP2007118583A also describes a method of forming wooden objects by compressing transversely to the wood fibers in a mold of a piece of wood.

[0008] All these processes involve shaping an object by compressing the wood, that is, by reducing, at least partially, the thickness of the initial piece of wood. Brief summary of the invention

[0009] One object of the present invention is to provide a device and a method for forming a wooden object free from the limitations known in devices and methods of the prior art.

[0010] Another aim of the invention is to provide a device and a method for forming a wooden object without compressing or crushing the wood.

[0011] Another aim of the invention is to provide a device and a method for forming a functional wooden object without heat treatment or special impregnation.

[0012] According to the invention, these goals are achieved in particular by means of a pressing device adapted for shaping a wooden object from a wooden blank, comprising: a die configured to support the blank, the die comprising a lower structure including a counterform; and a press enabling the blank to be pressed in a pressing direction when placed in the die, the press comprising an upper structure; characterized in that the die comprises at least one lower movable portion capable of moving relative to the lower structure along the pressing direction between a first initial position when the press is not actuated and a first final position when the press is actuated, the lower movable portion being configured to partially enclose a lower surface of the blank during its pressing by the press; and in that the press comprises at least one upper movable portion capable of moving relative to the upper structure along the pressing direction between a second initial position when the press is not actuated and a second final position when the press is actuated, the upper movable portion being configured to partially enclose an upper surface of the blank during its pressing by the press, the lower moving portion and the upper moving portion being arranged so as to allow a displacement of a portion of the blank in the counter-form by shearing the blank along the pressing direction when the press is operated.

[0013] According to one embodiment, the lower moving portion and / or the upper moving portion is supported by an elastic element, in particular a spring, capable of being compressed when the press is operated.

[0014] According to an alternative or complementary embodiment, the lower moving portion and / or the upper moving portion is supported by at least one hydraulic or pneumatic cylinder.

[0015] A surface of the press in contact with the upper surface of the blank during pressing can be textured so as to increase the friction between the upper surface of the blank and the surface of the press during pressing.

[0016] A surface of the die in contact with the lower surface of the blank during pressing can be textured so as to increase the friction between the lower surface of the blank and the surface of the die during pressing.

[0017] The matrix may include at least one lower stop to interrupt the relative movement of the lower moving portion with respect to the lower structure.

[0018] The press may include at least one upper stop allowing the relative movement of the upper moving portion to be stopped with respect to the upper structure 111.

[0019] According to one embodiment, the lower moving portion and the upper moving portion allow a clamping force to be exerted on the blank of between 0.5N / mm2 and 10N / mm2.

[0020] According to one embodiment, the die comprises a plurality of lower movable portions, each lower movable portion enabling an individual clamping force to be exerted, different from the others or not, on the blank.

[0021] According to one embodiment, the press comprises a plurality of upper movable portions, each upper movable portion enabling an individual clamping force to be exerted on the blank.

[0022] A surface of the press in contact with the blank during pressing may include a prominence extending in the direction of pressing so as to allow the blank to be marked when the press is operated.

[0023] These goals are also achieved by means of a process of forming a wooden object by pressing it from a wooden blank using a pressing device comprising a die provided with a counter-form and a press, in particular a device such as described above, comprising the steps of: place the blank in a die of the pressing device so that fibers of the blank extend parallel to a pressing direction of the press; press the blank along the pressing direction by means of the press, so as to completely offset by shear a portion of the blank along the pressing direction relative to the rest of the blank in the counterform.

[0024] According to one method of execution, the thickness of the portion of the blank is unchanged before and after the pressing step.

[0025] The process may further include a step of: clamping the blank by exerting a clamping force parallel to the direction of pressing so as to avoid lateral displacement and / or bending of the blank during pressing.

[0026] The pressing step can be repeated using different presses so as to successively shift several portions of the blank relative to each other.

[0027] The process may further include a step of: marking said portion of the blank, marking being effected by notching the portion of the blank by means of a protrusion of the press before the pressing step.

[0028] According to one embodiment, the force exerted by the press during the pressing step is less than 20N / mm², preferably less than 15N / mm². Brief description of the figures

[0029] Examples of implementation of the invention are given in the description illustrated by the accompanying figures, in which: There figure 1 illustrates a pressing device in which a wooden blank is clamped between three moving parts of the device before pressing. figure 2 illustrates the device of the figure 1 in which the wooden blank was formed by offsetting a central portion from the rest of the blank using a press. figure 3 illustrates a pressing forming device similar to that of the figure 1 in which a wooden blank is clamped before being pressed between seven moving parts of the device. figure 4 illustrates the device of the figure 3 in which the wooden blank was formed by offsetting three median portions from the rest of the blank using a press. figure 5This schematically illustrates a clamping step of a blank prior to a pressing step. figure 6 This schematically illustrates a pressing step during which a central portion of the blank is displaced by shearing relative to the rest of the blank while being clamped.2 figure 7 This schematically illustrates a marking step on a blank before pressing using a press. figure 8 schematically illustrates a pressing step during which a central portion of the blank is displaced by shearing relative to the rest of the blank. Example(s) of an embodiment of the invention

[0030] According to one aspect, the present invention relates to a pressing device 1 adapted for shaping a wooden object from a wooden blank 2.

[0031] As illustrated on the figure 1The device includes a die 10 intended to support the blank 2 before and during its pressing, and a press 11 allowing a pressure force to be exerted on the blank in order to give it the desired shape.

[0032] In the context of the present invention, terms such as "lower" and "upper" refer to the relative orientation of a forming press. The portion of the device 1 comprising the die 10 shall be designated as the lower portion, while the portion comprising the press 11 shall correspond to the upper portion. The pressing direction z corresponds to the direction of movement of the press when it is actuated. Thus, the pressing direction corresponds to an axis extending from the upper portion to the lower portion. Typically, if the device is positioned on the ground or on a surface parallel to the ground, the pressing direction corresponds to the vertical direction. However, it is possible that the device may be used in other orientations, or that the press may be actuated in a direction other than the vertical direction, according to the embodiments.

[0033] The die 10 includes a lower structure 101 that at least partially supports the blank 2 when the latter is placed in the pressing position within the die. The lower structure 101 is typically stationary relative to the blank 2 during pressing, at least with respect to the portion of the blank that is not deformed during pressing.

[0034] The lower structure 101 includes a counterform, that is, a relief (positive and / or negative) on a portion of the surface supporting the blank. The counterform determines the shape, that is, the geometry, of the final wooden object, since the blank is deformed, at least partially, by pressing it into the counterform. Thus, the dimensions and profile of the counterform significantly influence the final shape of the wooden object. The counterform may include a portion that is convex or concave relative to the surface of the lower structure in contact with the blank during pressing, so that the blank can be deformed in the direction of pressing or in the opposite direction.

[0035] In the embodiment illustrated on the figure 1 , the counterform is constituted by a hollow central portion of the lower structure 101.

[0036] As illustrated on the figure 1The press 11 includes an upper structure 111 that exerts a pressure force on the workpiece in order to deform it. When the press is actuated, the upper structure 111 moves along the pressing direction z and exerts pressure on a portion of the upper surface 21 of the workpiece 2.

[0037] Forming an object using device 1 involves shearing off a portion of the blank 2. For this to work, it is essential that the blank be positioned in the die 10 so that the wood fibers are parallel to the pressing direction z. Indeed, by applying sufficient pressure, the fibers under pressure are sheared from the rest of the blank and can be displaced without undergoing compression, that is, without altering the thickness of the displaced portion. This type of forming is thus distinct from forming in which the blank is compressed in a mold.

[0038] Pressing with press 11 thus allows a portion of the blank, on which pressure is applied, to be offset from the rest of the blank. By repeating this pressing step several times, possibly with presses of varying geometries, it is possible to obtain complex shapes.

[0039] Surprisingly and advantageously, the die 10 and the press 11 of device 1 include movable portions that allow certain parts of the workpiece to be clamped when the press is actuated, particularly near shear zones. The pressure exerted can induce deflection of the workpiece at the interface between the pressed and unpressed areas, potentially creating irreversible cracks. Clamping the workpiece thus prevents this deflection, thereby limiting the risk of cracking and resulting in sharper contours of the shear zones.

[0040] More specifically, the die 10 includes at least one lower movable portion 102 capable of moving relative to the lower structure 101 along the pressing direction z between a first initial position when the press is not actuated and a first final position when the press is actuated. This lower movable portion 102 is configured to partially enclose a lower surface 20 of the blank 2 during pressing, in particular to limit the risk of cracking during shearing.

[0041] The press 11 also includes at least one upper movable portion 112 capable of moving relative to the upper structure 111 along the pressing direction z between a second initial position when the press is not actuated and a second final position when the press is actuated. This upper movable portion 112 is configured to partially enclose an upper surface 21 of the workpiece 2 during pressing, in particular to limit the risk of cracking during shearing.

[0042] When the blank 2 is placed in the die 10 and the press 11 is actuated, but does not yet exert sufficient pressure on the blank to shear it, the blank is held clamped, on the one hand by the lower and upper moving structures 101, 111, and on the other hand by the lower and upper moving portions 102, 112, as illustrated in the figure 5on which the arrows indicate that pressure is exerted against the corresponding surface.

[0043] Next, if the press action is maintained, the portion(s) of the blank supported by the lower structure 101 are held stationary relative to the press, while the portions of the blank supported by the lower movable portions 102 are fully displaced by shear along the pressing direction in the counterform of the die. The term "fully" here means that the portion is displaced as a single unit and uniformly in the pressing direction. figure 6illustrates the shearing action of displacement. The right arrow indicates that the press exerts sufficient pressure to displace a portion of the blank supported by a lower movable portion 102. The arrows pointing to the surfaces of the blank indicate that a clamping force is exerted by the lower structure and the upper and lower movable portions on the blank.

[0044] This step is also illustrated on the figure 2in which a central portion of the blank 2 has been displaced along the pressing direction in the counterform under the pressure exerted by the press 11, particularly by the upper structure 111, but not necessarily. The lower movable portion 120 has also been displaced within the counterform while maintaining the clamping force against the lower surface 20. The upper movable portions 112, for their part, have been displaced relative to the upper structure 111 while maintaining the clamping force against the upper surface 21 of the blank. Thus, the blank is advantageously held under clamping during pressing on both its lower and upper faces.

[0045] When the press is operated, the lower and upper moving portions are typically moved a distance of between 0.1mm-50mm, preferably 0.1mm-25mm, while maintaining pressure on the blank.

[0046] The number of lower and upper moving parts varies depending on the application. Generally, a large number of moving parts allows for complex shapes while limiting the number of presses required.

[0047] Based on an illustrated implementation method shown on the figures 3 and 4 The die and the press comprise several movable portions. The die 10 comprises four lower movable portions 102 and the press comprises three upper movable portions 112. The counterform of the die is here arranged laterally around a central element of the lower structure 101.

[0048] On the figure 3 , the blank 2 is held clamped and all the moving parts are aligned because the pressure exerted by the press is not sufficient.

[0049] On the figure 4, the central part of the draft supported on the lower structure 101 remained in its initial position while two adjacent parts were shifted by a first height and two lateral parts were shifted by a second height.

[0050] The arrangement of the lower and upper moving portions, according to the invention, as well as the adaptation of the clamping forces exerted on the blank by the different moving portions, thus makes it possible to maintain a clamping force on all the different portions of the blank throughout the pressing in order to avoid breaks or cracks in the shear zones.

[0051] According to one embodiment, the lower moving portion and / or the upper moving portion is supported by an elastic element that can be compressed on itself in the direction of pressing when the press is operated so as to allow movement of the moving portions in the direction of pressing.

[0052] As illustrated on the figures 1 to 4 , these elastic elements can be made up of springs whose return constant is adapted so that the springs exert the required clamping force against the blank during pressing.

[0053] Thus, when the die and / or press include several lower and upper moving portions, the spring return constants can differ from each other in such a way as to allow clamping of the different portions of the blank.

[0054] Alternatively or additionally, the lower moving portion and / or the upper moving portion is supported by at least one hydraulic or pneumatic cylinder. Such cylinders are particularly suitable when the pressures exerted by the various press components are significant and could damage springs.

[0055] In one embodiment, certain surfaces of the die 10 and the press 11 can be textured to limit movement of the blank during pressing. Indeed, during pressing, unwanted movement of the blank can increase the risk of cracking, particularly near shear zones. Thus, a surface of the press 11 in contact with the upper surface 21 of the blank during pressing can be textured to increase friction between these two surfaces. Similarly, a surface of the die 10 in contact with the lower surface 20 during pressing can also be textured to increase friction between these two surfaces. The term "textured" typically refers to, but is not limited to, an increase in the grain size of the press or die surface, raised concentric circles on these surfaces, small bumps, etc.

[0056] In order to determine the offset height of the portion of the blank displaced during pressing, or to protect certain elements such as springs, cylinders, lower and upper moving portions, etc., the die and / or the press may include stops. These stops allow the relative movement of a lower moving portion 102 with respect to the lower structure 101 and / or of an upper moving portion 112 with respect to the upper structure 111 to be interrupted. Stops thus determine, in particular, the amplitude of a possible displacement of a moving portion along the pressing direction z.

[0057] According to one embodiment, the clamping force of the blank exerted by each lower and / or upper moving portion is between 0.5 N / mm² and 10 N / mm². As mentioned above, the forces exerted by different moving portions can be identical or vary, particularly depending on the desired offsets of the blank and / or the intensity of the clamping force on certain portions of the blank.

[0058] In one embodiment, a surface of the press 11 in contact with the blank 2 during pressing includes a protrusion extending along the pressing direction z. This protrusion allows the blank to be marked using the press by notching its upper surface 21. Such marking reduces the pressure force required to displace a portion of the blank during pressing. The protrusion typically includes a tooth, a rib, or a cutting edge.

[0059] According to another aspect, the present invention also relates to a method of forming by pressing a wooden object from a wooden blank 2 by means of a pressing device 1 comprising a die 10 provided with a counter-form and a press 11.

[0060] This process includes a first step of placing the blank 2 in the die 10 so that the fibers of the blank are parallel to the pressing direction of the press. This orientation of the wood fibers allows for the offset of a portion of the blank relative to the rest of the blank by pressing without the need for prior treatment of the wood (for example, heat treatment or impregnation).

[0061] In a second step of the process, the blank 2 is pressed along the pressing direction z using the press 11, so as to completely offset by shear a portion of the blank along the pressing direction relative to the rest of the blank in the counterform of the die 10.

[0062] It should be noted that the pressing device described above is a preferred option for carrying out this process, but other pressing devices may be used.

[0063] According to one embodiment, the thickness—that is, the dimension measured along the pressing direction—of the portion of the blank is essentially the same before and after the pressing step. In other words, the shear offset does not compress the offset portion of the blank along its thickness.

[0064] According to a preferred embodiment, the process further includes a step of clamping the blank 2 by applying a clamping force parallel to the blank fibers to prevent lateral displacement of the blank and / or bending of the blank around the shear zones during pressing. This step can typically be carried out using the pressing device described above or other suitable devices.

[0065] In order to allow the creation of objects with a more complex profile, one or more steps of the process can be repeated successively so as to offset several portions relative to each other or the same portion several times.

[0066] In one embodiment, the process may also include a marking step on a surface of the blank in contact with the press, using the same press, specifically a protrusion of the press. This marking may involve making a notch in the blank. This marking reduces the force required by the press to move the portion of the blank. It also reduces the stresses in the shear zones of the blank, thereby limiting the risk of cracking.

[0067] According to one embodiment, this marking typically allows the formation of the desired object by applying a pressing force with the press of less than 20N / mm², preferably less than 15N / mm². This reduction in the pressure exerted can limit the clamping force required for the blank.

[0068] As illustrated on the figure 5 The marking can be carried out on the blank 2 using the press 11. figure 6 then illustrates the pressing step, by shifting a median portion of the blank into the counterform of the die 10. Since a marking of the blank has been carried out, the blank does not necessarily need to be clamped during pressing. Reference numbers used in the figures

[0069] 1 Pressing device 10 Die 101 Lower structure 102 Lower moving portion 11 Press 111 Upper structure 112 Upper moving portion 120 Elastic element 2 Blank 20 Lower surface 21 Upper surface Pressing direction

Claims

1. A pressing device (1) adapted for forming a wooden object by shearing a wooden blank (2), comprising: a die (10) configured to support the blank, the die comprising a lower structure (101) including a counterform; and a press (11) for pressing the blank in a pressing direction (z) when it is placed in the die, the press comprising an upper structure (111); such that the press (11) comprises at least one upper movable portion (112) capable of moving relative to the upper structure (111) in the pressing direction (z) between a second initial position when the press is not activated and a second final position when the press is activated, the upper movable portion (112) being configured to partially clamp an upper surface (21) of the blank (2) when it is pressed by the press, characterised in that: the die (10) comprises at least one lower movable portion (102) capable of moving relative to the lower structure (101) along the pressing direction (z) between a first initial position when the press is not activated and a first final position when the press is activated, the lower movable portion (102) being configured to partially clamp a lower surface (20) of the blank (2) when it is pressed by the press; and in that the lower movable portion and the upper movable portion being arranged so as to allow a portion of the blank to be shifted in the counterform entirely by shearing of the blank in the pressing direction (z) when the press is activated, and to maintain a clamping force on all the different portions of the blank throughout the pressing process on both the lower and upper faces in order to prevent breaks or cracks in the shear zones .

2. Device according to claim 1, the lower movable portion (102) and / or the upper movable portion (112) being supported by an elastic element (120), in particular a spring, capable of being compressed when the press (11) is activated.

3. Device according to claim 1, wherein the lower movable portion (102) and / or the upper movable portion (112) is supported by at least one hydraulic or pneumatic cylinder.

4. Device according to one of claims 1 to 3, wherein a surface of the press (11) in contact with the upper surface (21) of the blank during pressing is textured so as to increase the friction between the upper surface of the blank and the surface of the press during pressing.

5. Device according to one of claims 1 to 4, wherein a surface of the die (10) in contact with the lower surface (20) of the blank during pressing is textured so as to increase friction between the lower surface of the blank and the surface of the die during pressing.

6. Device according to one of claims 1 to 5, the die comprising at least one lower stop for interrupting the relative movement of the lower movable portion with respect to the lower structure (101).

7. Device according to one of claims 1 to 6, the press comprising at least one upper stop for interrupting the relative movement of the upper movable portion with respect to the upper structure (111).

8. Device according to one of claims 1 to 7, wherein the lower movable portion and the upper movable portion enable a clamping force to be exerted on the blank of between 0.5 N / mm2 and 10 N / mm2.

9. Device according to one of claims 1 to 8, the die comprising a plurality of lower movable portions, each lower movable portion allowing an individual clamping force to be exerted on the blank, which may or may not be different from the others.

10. Device according to one of claims 1 to 9, the press comprising a plurality of upper movable portions, each upper movable portion allowing an individual clamping force to be exerted on the blank.

11. Device according to one of claims 1 to 10, wherein a surface of the press in contact with the blank during pressing comprises a protrusion extending in the direction of pressing, enabling the blank to be marked, in particular notched, when the press is activated.

12. Method for forming a wooden object by pressing a wooden blank using a pressing device comprising a die provided with a counterform and a press, in particular a device as described in claims 1 to 11, comprising the steps of: placing the blank in a die of the pressing device so that the fibres of the blank extend parallel to a pressing direction of the press; pressing the blank in the pressing direction by means of the press, so as to shift a portion of the blank integrally by shearing in the pressing direction relative to the rest of the blank in the counterform.

13. Method according to claim 12, wherein a thickness of the portion of the blank is unchanged before and after the pressing step.

14. Method according to one of claims 12 to 13, further comprising a step of: clamp the blank by applying a clamping force parallel to the pressing direction so as to prevent lateral displacement and / or bending of the blank during pressing.

15. Method according to one of claims 12 to 14, the pressing step being repeated using different presses so as to successively shift several portions of the blank relative to each other.