FURNITURE TOP AND METHOD FOR MANUFACTURING THIS TOP

Abstract: A method serving for manufacturing a core stock (1) which, along an edge area (2), is provided with a cavetto list (3; 4) shaped on the inside with a longitudinal cavetto surface (5). Free starting lists (19; 20) having a rectangular profile enclosing the future cavetto surface (5) are used in this method. The starting lists (19; 20) are fixed in the edge area (2) of the core stock (1) whereupon the cavetto surface (5) is uncovered by successively removing material from the starting list (19; 20). By means of the method, core stocks (1) can quickly and easily be manufactured that have cavetto lists (3; 4) with cavetto surfaces (5) which pass into the top side (7) of the core stock (1) completely evenly and smoothly at the same time as the cavetto surfaces (5) in a corner pass into each other along a surface of double curvature.

Description: FURNITURE TOP AND METHOD FOR MANUFACTURING THIS TOP The invention relates to a method for manufacturing a core stock, such as a tabletop, which, along an edge area, is provided with at least one cavetto list shaped with a longitudinal cavetto surface on the inside. Cavetto lists are used for forming, with regard to a design point of view, an attractive transition between e.g. a tabletop on a kitchen table and the adjacent walls. At the same time, the cavetto list serves a hygienic purpose as they are bridging across the sharp, inwardly directed corners between the top side of the tabletop and the wall so that the transition avoids becoming a collecting place for dirt and impurities and is easily cleaned. Conventionally, such a tabletop is manufactured by shaping the cavetto in advance on separate lists which then as finished cavetto lists are manually fixed along the edge area. However, it is extremely difficult and time-consuming to make such lists fit properly on the tabletop and in most cases, the finished result is not satisfactory. At the transition, a list can thus project a little above the tabletop in some places, and in others, lie a little below. Thereby, unevennesses in the form of e.g. narrow slits will be made that function as pockets for dirt and impurities, and that are almost impossible to clean. The unevennesses furthermore disfigure an otherwise attractive design. In the conventional method, cavetto lists are cut to mitre at a corner and assembled with a sharp transition that mean that the corner suffers the same hygienic and appearance-wise defects as mentioned above. The object of the invention is to provide a method of the kind mentioned in the opening paragraph, whereby a core stock can be manufactured quickly and easily with cavetto lists, the cavetto surfaces of which have a transition to the top side of the core stock that is more even and smoother than known so far, and which pass into each other in a corner along a surface of double curvature . The novel and unique features according to the invention, whereby this is achieved, is the fact that on the edge area is fixed at least one starting list which completely or partly encloses an inherent cavetto surface in the list, and that the cavetto list is uncovered by successively removing material from the at least one starting list with e.g. a milling cutter. Thereby, the laborious and expensive adjustment work of the conventional method is dropped and at the same time, a completely even and smooth transition between the cavetto surfaces and the top side of the core stock and the cavetto surfaces of double curvature in the corners is obtained. Thereby, the core stock is able to live up to the required hygienic standard, and it is quickly and easily cleaned. Furthermore, the design is no longer spoiled by disfiguring unevennesses between the top side of the cavetto lists and the core stock. When the cavetto list is made by milling, a computer operated milling machine can be used, for example an NC machine, which is programmed to guide the milling cutter along the three axes of the room x, y, z where the z-axis is perpendicular to the core stock. The guiding along the z-axis can advantageously take place by means of a detector which continuously registers the position of the z-axis of the milling cutter and gives signals representing the measured value to the computer. The detector can e.g. function by means of a laser beam, ultrasound or similar means for ensuring an accurate measurement result and consequently precise milling work. The milling cutter can also be positioned along the z-axis by means of a spacer which has a sliding foot and is placed on the milling head of the milling cutter. The spacer automatically sees to it that the lowest area of the milling cutter follows the top side of the core stock closely. This method is simple and at the same time very reliable as the foot itself, during the passage of the top side of the tabletop, pushes chips aside which could cause a misregistration of the distance to the core stock. In order to avoid impeding friction between the core stock and the spacer, the foot of this can advantageously be arranged to slide on an air cushion which at the same time serves - for blowing chips away from the foot . The invention also relates to a core stock, such as a tabletop, with an edge area which is provided with cavetto lists with cavetto surfaces which pass into the top side of the core stock evenly and smoothly, at the same time as the cavetto surfaces on two lists joining in a corner pass into each other evenly and smoothly via a surface of double curvature. Thereby, the core stock will be hygienic to use and clean, and it is given an attractive design. The invention will be explained in greater detail below, describing only exemplary embodiments and giving additional advantageous characteristics and effects with reference to the drawing, in which Fig. 1 is a perspective view obliquely from above of a fragment of a core stock according to the invention, Fig. 2 is a side view partly in section of a first process step of manufacture of the core stock in fig. 1, Fig. 3 is a side view partly in section of a second process step of manufacture of the core stock in fig. 1, Fig. 4 is a side view partly in section of a third process step of manufacture of the core stock in fig. 1 where a cavetto list is milled by means of a milling cutter, Fig. 5 shows on a smaller scale a block diagram schematically illustrating an electronic control of the z-axis position of the milling cutter, Fig. 6 shows on a larger scale a mechanical control of the z- axis position of the milling cutter, Fig. 7 is a top view of the milling cutter during milling of the first cavetto list, Fig. 8 is a top view of the milling cutter during milling of a cavetto surface of double curvature in a corner where the first cavetto list joins the second, Fig. 9 is a top view of the milling cutter during milling of the second cavetto list. The core stock according to the invention is in fig. 1 designated in general by the reference numeral 1. A table top 8 is along an edge area 2 provided with a first and a second cavetto list 3, 4 each having a longitudinal cavetto surface 5 passing evenly and smoothly into the top side 7 of the table top. Where the two lists 3, 4 join in the shown corner, they pass into each other evenly and smoothly via a cavetto surface 6 of double curvature. In the case shown, the table top is coated with laminate 22 on both sides. Fig. 2 illustrates a first process step of manufacture of the core stock in fig. 1. A starting list 9 encloses with a rectangular profile the future cavetto surface 5 indicated by a dotted line. In the figure, the free starting list 9 is led in the direction of the arrow towards the edge area 2 of the table top 8. In fig. 3, the list 9 is made to abut against the table top 8, and in fig. 4 with a possible intermediate adhesive layer (not shown) nailed to the table top with nails 18. A milling cutter 10 has then milled off so much of the starting list 9 that the cavetto surface 5 has been uncovered. It is to be noted that the list can be fixed on the table top in any other suitable way, e.g. with screws or only by means of bonding . The process step in fig. 4 is illustrated in more detail in fig. 5 where the milling cutter 10 is mounted in a milling head 23 in a milling machine (not shown) which is provided with a computer 15. The guiding of the milling cutter along the z-axis takes place by means of a detector 17 which follows the milling head 23 of the milling cutter 10 and during this continuously registers the immediate distance of this from the top side of the tabletop. During this, the detector gives a signal representing the registered distance, to the computer 15 which then compares the value with a reference value from a reference unit 16. In the case of deviations, the computer sends via an amplifier 24 a signal to a manoeuvring organ 25 to regulate the z-axis position of the milling cutter so that the value of the distance of the milling cutter from the top side of the tabletop will be the same as the reference value. As the bottom area of the milling cutter is thereby made to follow the top side of the tabletop closely, the wanted completely even and smooth transition is formed between this and the cavetto surface 5. Fig. β shows a second possibility of adjusting the z-axis position of the milling cutter 10. In this case, use is made of a spacer 11 which is mounted on the manoeuvring organ 25 and which has a foot 12 for slidingly supporting on the top side 7 of the tabletop 8. The underside of the sliding foot 12 is on the same level as the underside of the milling cutter 10, and the milling head 23 is placed freely displaceable in axial direction on the milling cutter 10. During milling, the spacer 11 thereby always keeps the underside of the milling cutter on the same level as the top side of the tabletop so that a completely even and smooth transition between the cavetto surface 5 and the top side 7 of the tabletop is also obtained in this case. This method is simple and furthermore very reliable as the foot 12 itself pushes hampering chips aside. Fig. 7, 8, and 9 illustrate the successive milling of the cavetto surfaces in a first and a second starting list 19; 20 which are fixed along an edge area 2 on a tabletop 8. As shown, the lists overlap each other in the corner 21. In fig. 7, the milling cutter is, during milling of a cavetto surface 5 in the first starting list 19, led in the direction of the arrow towards the corner 21. In fig. 8, the milling cutter has reached the corner 21 where it mills a surface of double curvature having a shape that is complementary to the exterior of the milling cutter and is further defined by the intersection curve between the surface of double curvature and a plane comprising the axis of the surface of revolution being congruent with the intersection curve between the longitudinal cavetto surface and a plane which is perpendicular to this. In fig. 9, the milling cutter is, during milling of a cavetto surface 5 in the second starting list 20, led in the direction of the arrow away from the corner 21.

Claims: CLAIMS 1. A method for manufacturing a core stock (1), such as a tabletop (8) which, along an edge area (2), is provided with at least one cavetto list (3; 4) shaped with a longitudinal cavetto surface (5) on the inside, characterised in that on the edge area (2) , at least one starting list (19; 20) is fixed that completely or partly encloses an inherent cavetto surface (5) in the list, and the cavetto surface (5) is uncovered by successively removing material from the starting list. 2. A method according to claim 1, characterised in that the material is removed by means of a milling cutter (10) . 3. A method according to claim 1 or 2 , and where the edge area (2) comprises a corner (21) where two edges join, characterised in that on each of the two edges is placed a starting list (19; 20) that in the corner encloses an inherent cavetto surface of double curvature (6), and that this cavetto surface is uncovered by successively removing material from the starting lists (19;20). 4. A method according to claim 1, 2, or 3, characterised in that the material is removed with a milling cutter (10) in a milling machine with a computer (15) programmed to guide the milling cutter along the three axes of the room x, y, z, where the z-axis is mainly perpendicular to the core stock (1) . 5. A method according to claim 4, characterised in that the guiding of the milling cutter (10) along the z-axis takes place by, with a detector (17) which follows the milling cutter, continuously registering its immediate distance from the top side (7) of the tabletop (8) and giving a signal representing this distance to the computer (15) which then compares the value with a reference value and transmit a signal to a manoeuvring organ (25) belonging to the milling machine to regulate the z-axis position of the milling cutter (10) so that the value of the distance of the milling cutter from the top side (7) of the tabletop (8) will be the same as the reference value. 6. A method according to claim 4 or 5 , characterised in that the z-axis position of the milling cutter (10) is established by a spacer (11) which follows the milling cutter and has a foot (12) for supporting on the top side (7) of the core stock (1) . 7. A method according to claim 6, characterised in that the foot (12) of the spacer (11) is supporting on the top side (7) of the core stock (1) via an air cushion. 8. A core stock (1), such as a tabletop (8) which, along an edge area (2), is provided with at least one list (3;4) which has a longitudinal cavetto surface (5), characterised in that the cavetto surface (5) passes into the top side (7) of the core stock (1) evenly and smoothly. 9. A core stock (1) according to claim 8, characterised in that the longitudinal cavetto surfaces (5) on each of two lists (3,-4) joining in a corner (21) pass into each other evenly and smoothly via a cavetto surface of double curvature ( 6 ) . 10. A core stock (1) according to claim 9, characterised in that the cavetto surface of double curvature (6) lies in a surface of revolution, and that the intersection curve between this cavetto surface of double curvature and a plane comprising the axis of the surface of revolution is congruent with the intersection curve between the longitudinal cavetto surface (5) and a plane which is perpendicular to this surface.

Inventors: JOERGENSEN JESPER MADVIG, JOERGENSEN, JESPER, MADVIG
Applicants: JOERGENSEN JESPER MADVIG, JOERGENSEN, JESPER, MADVIG
Application year: 1998
Main classification: A47B13
IPC codes: A47B77