Making profile-edge construction board

Abstract

Construction board is made by first hot-pressing particles in a continuous belt press to form a longitudinally extending, continuous and hot composite strand that is conveyed downstream from the press. Before substantial cooling of the boards and while it is at a predetermined temperature above ambient temperature, an edge of the strand is profiled into a nonsquare profiled contour. Then the strand is transversely severed to form a succession of boards.

Claims

1. A method for making construction boards, the method comprising the steps of: hot-pressing particles in a continuous belt press to form a longitudinally extending, continuous and hot composite strand having an edge of square contour; before substantial cooling of the boards and while same is at a predetermined temperature below a temperature at which the strand leaves the press, and above a temperature midway between the temperature at which the strand leaves the press and ambient temperature, trimming and thereby truing the edge of the strand to planarity and thereafter profiling the trimmed edge of the strand into a nonsquare profiled contour; and transversely severing the strand to form a succession of boards.

2. The board-making method according to claim 1, wherein the edge profiling is carried out downstream of an outlet of the press and upstream of a device that transversely severs the strand.

3. The board-making method according to claim 1, wherein the edge profiling entails rounding a longitudinal side edge of the strand.

4. The board-making method according to claim 1, further comprising the step after the edge profiling and before the transverse severing of: coating at least an upper or lower face of the strand.

5. The board-making method according to claim 1, further comprising the step after the edge profiling and before the transverse severing of: coating an upper face and a lower face of the strand.

6. The board-making method according to claim 5, wherein the coating consists of adhering a paper sheet or synthetic-resin film to at least one face of the strand.

7. The board-making method according to claim 1, wherein the transverse severing is effected by a saw after the profiling.

8. The board-making method according to claim 1, wherein the profiling is a rounding of the edge.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

(2) FIG. 1 is a small-scale schematic top view of a system for making construction board according to the invention, the straight transport path for the board being shown in two parallel sections;

(3) FIG. 2 is a side view of a portion of the system of FIG. 1;

(4) FIG. 3 is a section through an edge of a coated and profiled board; and

(5) FIG. 4 is a section through the continuous strand at a location where it will be longitudinally subdivided.

SPECIFIC DESCRIPTION OF THE INVENTION

(6) As seen in FIG. 1 a system 1 for making a construction board has a continuous belt press 2 such as marketed by applicant under the trade name ContiRoll®. This press 2 has upper and lower heated driven belts that compress a mass formed by a mixture of particles (e.g. wood chips) and a binder into a flat longitudinally extending composite mat or strand shown in broken lines at S and moving continuously in a longitudinal and normally horizontal travel direction D. The particles are lignocellulosic fibers or wood chips, but the invention is not limited to this. The mat or strand S is compact and coherent as it leaves a downstream outlet end 2a of the press at a fairly high temperature T2. A roller-type conveyor 3 moves it downstream to a trimmer 4 where a pair of tools 5 true up longitudinally extending outer edges of the composite strand S. This gives the web S a rectangular cross section formed by the two planar and normally vertical and parallel longitudinal edges and the planar and normally horizontal and parallel top and bottom faces.

(7) A profiling device 6 downstream of the trimmer 4 in the direction D shapes the longitudinal outer edges of the strand to the desired nonsquare contour as shown at 17 in FIG. 3, for instance by milling with a part-round milling bit 7. This profiling takes place according to the invention while the composite strand is still at or close to the high temperature T2 that is well above ambient temperature T1. The distance between the press outlet 2a and the profiling device 6 is less than 20 m. During the longitudinal-edge profiling, the composite strand S is so hot that it is between the temperature T2 at the outlet 2a of the continuous press 2a and the ambient temperature T1.

(8) The profiled composite strand is fed in a straight line from the profiling device 6 by a bridging conveyor 8 to a coating device 9. FIG. 2 shows that this coater 9 has upper and lower supply rolls 12a and 12b for respectively applying coating sheets or films 18a and 18b to the upper and lower faces of the strand S. An exchange or replacement roll 15 that also can be used on the fly is shown.

(9) Films or resin-soaked paper may be used as the sheets 18a and 18b. FIGS. 1 and 2 show an upper paper coating 18a and a lower paper coating material 18b, each pulled through an adhesive applicator 13 so as to be coated with adhesive and finally pressed by possibly heatable rollers 14 for adhering to the upper and lower faces of the composite strand S.

(10) This is followed by a finishing facility 10 for the coating where an edge portion 20 of a wide upper coating web 18a is wrapped around the profiled edge 17 and overlapped on the lower face of the strand with the lower coating layer 18b. This type of treatment is used on an office desk where the front edge is profiled and coated this way. According to the invention, however, this is done on the continuous strand before it is cut into individual boards.

(11) Downstream in the direction D from the coater 9 is a diagonal saw 11 whose angle is matched to the travel speed of the workpiece to allow it to perpendicularly sever the strand S, producing boards with square leading and trailing edges that extend perpendicular to the direction D.

(12) FIG. 3 shows a typical embodiment of a gypboard in section, showing the shape of the profiled edge 17 and the glued-on upper and lower coating sheets 18a and 18b.

(13) The profiling must, however as shown in FIG. 4 not necessarily be made only at the edge. With a curved v-shaped cutout 19 extending transversely across the composite strand 16 one creates two sections, for example with leading and trailing transverse profiled edges that 17.