CN1100650C - Method and arrangement for the continuous manufacture of profiled lignocellulose-containing board of strip-like products - Google Patents

Abstract

In a method and an arrangement for continuously producing profiled, lignocellulose-containing board or strip-like products the fibre material is disintegrated into particle and/or fibre form, which are then dried, glue-coated and formed into a fibre mat (3). This is pressed into a board or strip-like product (4) while injecting steam. Prior to pressing, the fibre mat (3) is given a surface profile, which is maintained during the steam injection process, whereupon the surface of the board of strip-like product is compressed with this profile.

Description

Method and apparatus for the continuous manufacture of shaped lignocellulose-containing board or strip products

technical field

The present invention relates to a method and a device for the continuous manufacture of shaped lignocellulose-containing board or strip products according to the preamble of claim 1 and also to a method according to the preamble of claim 7 of the present invention , A device for implementing the method.

Background technique

A common method of manufacturing such shaped structural parts as skirting boards, cornices, window liners, frames or furniture parts is to plan or mill the desired shape. The incompatibility of milling such a product from MDF using such a technique is evident. Firstly, it will involve many costly intermediate steps and operating production and transport chains and will mean that the shaped product will have different densities along the cross-section and will absorb different amounts of paint or varnish at various locations. Milling operations will also cause a high degree of material loss. For example, more than 50% of the original material will be lost when grinding a product to a significant depth of formation.

A standard example of such a production chain could be the case where dried and glued fibers are produced in an MDF (medium density fibreboard) factory and this fiber is formed into mats, such mats are pressed into boards, such that The boards are then trimmed and ground. Dust caused by burrs on the edge of the trimming plate and grinding operations cause wear and tear. The next link in the production chain consists of transporting the board to a production unit to be made into shaped products. In this third stage, the MDF is sawn into strips, these strips form the raw blanks required for the shaped product, these raw blanks are milled and ground, and painted with multiple layers of paint or varnish , or coat some kind of film on it for primer or decoration purposes.

Contents of the invention

The object of the present invention is to avoid in an economical manner the disadvantages associated with the above-mentioned production process and instead to provide a continuous process up to the finished shaped product with as little material loss as possible. This object is achieved according to the invention having the characteristics set forth in the following claims.

Description of drawings

The invention will be described in more detail with reference to the accompanying drawing, which shows an apparatus of the invention in schematic longitudinal section, with four separate cross-sectional views on an enlarged scale.

Detailed ways

The apparatus shown is based on that shown in Swedish patent SE 502272 which describes a continuous steam injection process. The pulverized, dried and glued lignocellulosic material is fed to a forming station 1 where a fibrous mat 3 is formed which is fed to a steam jet press 2 . The fiber mat is pressed in a press to form a board product 4 which is hardened or cured to such an extent that the board is solid and has a given mechanical strength. Its surfaces are further densified on a surface densifying unit 5 . This process results in a panel with a solid outer surface.

According to the invention, the plant is used to produce shaped plate or strip products in a one-step and identical two-step process. For this purpose, a milling or cutting roll 6 is arranged between the forming station 1 and the steam injection press 2 . The cutting rollers 6 are used to give the lignocellulosic sized raw material a shaped surface structure in the form of a fibrous mat 3 having a density of 20-200 kg/m ³ . For this purpose, the diameter of the cutting roller 6 varies over its width. The shape given to the cross-section of the mat substantially conforms to the cross-section of the finished product. This shaped mat 3 , which can be precompressed, is conveyed continuously into the steam injection press 2 . This press includes a forming steam roll 7 which has the same profile as the cutting roll 6 . By injecting saturated or superheated steam into the mat 3, the mat is compressed and hardened there to form a plate or strip 4 of the desired cross-section. In a second step, the surface layers are further compressed by passing the plate or strip 4 through a surface densification unit 5 comprising one or more pairs of thermocompressing roll-pairs 8, which The geometry of the roller is the same as that of the steam roller 7, but its cross-sectional area is smaller to obtain the desired surface compression. The surface temperature of the roller pairs 8 may be 100-350°C, preferably 150-250°C.

The figure shows a cross-section 9 of a fiber mat 3 formed before the mat is shaped. A cross-section 10 downstream of the cutting roller 6 illustrates the profile of the upper surface. Downstream of the injection press 2 , the plate 4 passing in this press has a cross-section 11 , in a cross-section 12 downstream of the surface densification unit 5 the surface flakes have a higher density but the same shape.

The lower side of the panel can be formed using the same technique. In this respect, a cutting roller 6 is also arranged on the other side of the fiber mat 3 and two lower rollers 7 and 8 are arranged in some parts of the profile in the previous injection press 2 . This is achieved by deviating the contours on the two rollers 7 and 8 from the contour on the cutting roller 6 at these points.

In another alternative embodiment, the plate or strip produced in the first step, i.e. in the jet press, can be subdivided into several narrower strips in a continuous process, and these narrower strips are then made The sliver passes through one or more heated counterrolls 8 in the surface densification unit 5 . The board or strip can be divided into a plurality of narrower strips, for example by sawing.

The present invention makes it possible to manufacture shaped lignocellulose-containing products in the form of plates and strips having a uniform density throughout their cross-section and having a dense surface which An equal amount of paint is absorbed over the entire product. In addition, this is achieved without loss of raw material, apart from the minor losses that occur when sawing boards or strips.

Claims (8)

1. A method for the continuous manufacture of shaped lignocellulose-containing board or strip products, wherein the lignocellulosic material is comminuted into granules and/or fibers, and the granules or fibers are dried, glued, and formed is a fibrous mat which is pressed in a steam jet press to produce a plate or strip product (4), characterized in that the fibrous mat (3) has a surface profile before being pressed, and This surface profile is maintained during the process, when the surface of the plate or strip product is compressed. 2. A method according to claim 1, characterized in that the fiber mat is formed from a bulk having a density of 20-200 kg/ ^m3 . 3. A method according to claim 1 or 2, characterized in that the fiber mat is pre-compressed. 4. A method according to any one of claims 1-3, characterized in that the steam injection plate or strip product is subdivided successively into a plurality of narrower strips before said surface compression. 5. A method according to any one of claims 1-4, characterized in that the density of the plate or strip-shaped product is varied over the entire said surface. 6. A method according to any one of claims 1-5, characterized in that a surface profile is formed simultaneously on the top side and the bottom side of the product. 7. A device for applying the method according to any one of claims 1-6, comprising a forming station (1), one for compressing a fiber mat coming from the forming station (1) into A plate or strip-shaped product (4) and, a surface-densifying unit (5) for further processing of this product, characterized in that between the forming station (1) and the preceding injection press (2) there is at least one milling or cutting roll (6) to provide a surface profile for the fiber mat; and, each of the steam jet press (2) and the surface densification unit (5) is provided with at least one roll (7 and 8 respectively) , the roll is shaped over its entire width. 8. The device according to claim 7, characterized in that the profile of the steam roll (7) in the steam injection press (2) is the same as that of the milling or cutting roll (6), while the surface is dense The press roll (8) in the unit has a profile whose diameter is greater than the diameter of the profile of the vapor roll (7) at certain extreme points.