DD221557A1 - PROCESS FOR DEFECTOSCOPY, PREFERABLY TO WOOD - Google Patents

Abstract

The invention relates to a method for device-based detection of errors and for obtaining corresponding computer control signals in solid wood, wood-analogous materials and other materials with organically grown structure using their thermal properties. The invention aims at the objectification of error detection in wood as a prerequisite for continuous automation of the cutting process and a higher degree of material utilization. The invention has for its object to develop a Defektoskopieverfahren, which corresponds to the specific thermal properties of solid wood and analogous materials and checked by means of which solid wood in a continuous process for errors and the resulting characteristics are processed as signals for a computer. According to the invention, this is achieved by heating the material to be tested in a continuous process by means of different heat radiation sources and, after a short duration, by measuring the heat radiation.

Description

Title of the invention

Method for defectoscopy, preferably on wood

Field of application of the invention

The invention relates to a method for device-based detection of errors and for obtaining corresponding computer control signals in solid wood, wood-analogous materials and other materials with organically grown structure using their thermal properties.

Characteristic of the known technical solutions

As a rule, errors in wood and analogous materials are subjectively determined by a worker and marked manually.

Recently, a quality sorting plant for sawn timber was developed by the BRD company Gre Con and presented at the trade fair "Constructa '82", Hanover, in which, among other things, branches should also be locatable by using gamma radiation. The same company also uses ultrasound transmission to determine defects in chipboard.

In DE-AS 23 11 325, the application of heat radiation for material defect detection is described, but the temperature of the heat radiation source, which from a

Shielding is continuously adjusted to the average temperature of the solid to be tested. With wood and analogous materials, this method does not result in any characteristic values that can be clearly evaluated with regard to error determination.

Object of the invention

The invention aims at the objectification of error detection in wood and analog materials as a prerequisite for a continuous automation of the cutting process, a higher degree of material utilization and a significant increase in labor productivity.

Explanation of the essence of the invention

The invention has for its object to develop a Defektoskopieverfahren, which corresponds to the specific thermal properties of solid wood and analogous materials and by means of which solid wood and analogous materials in a continuous process for errors tested and the resulting characteristics are processed as signals for a computer. According to the invention, this object is achieved in that the material to be tested is heated by heat radiation sources arranged at a certain distance in a through-air method, and thereafter the heat radiation is preferably measured pyrometrically. The distance is regulatable and determined according to:

the power and geometric design of the or the radiator

the structural structure, the material thickness and possibly deformation of the wood or analogous material (condition)

the feed rate of the material to be tested.

The Aufheiζtemperatür is significantly above the average ambient temperature. The measurement is predominantly done

perpendicular to the material surface. From the measured temperature differences, conclusions are drawn about the structure of the material and thus about errors.

Ausfüharungsbeisplel

At some distance from the broad sides of a board heat radiation sources (Β Β · infrared radiators) are arranged perpendicular to the material surface and heated in a short time and in a continuous process. The distance between the respective broad side of the board and the heat radiation source is adjustable and moves in the range of about 0.01 m to 1.0 m, depending on the aforementioned factors. The heating takes place significantly above the ambient temperature, it is between about 10 ⁰ C and 80 ⁰ G above the average room temperature. After passing through a distance with room temperature or with short-term cooling of the board in the air stream, the heat radiation measurement is carried out by means of pyrometers, which are also arranged perpendicular to the material surface.

In this case, areas with material defects show a different heat radiation behavior than their environment with normal structure, wherein the cooling of the boards after heating results in a greater differentiation of the measured values.

It should also be noted that the heat radiation process is time-dependent, i. H. for example, that material defects as a function of the time after heating can have a different, with respect to the normal structure even opposing temperature level, which must be taken into account in the choice of the measurement time. To the pyrometer recording units can be connected, which z. B. provide computer analyzable temperature diagrams.

The method also allows the detection of defects and defects that lie below the material surface in comparison to known methods.

Claims (4)

invention claim 1 · Method for defectoscopy, preferably on wood and analogous materials using their thermal properties, characterized in that the material to be tested is heated in a continuous process by means of different heat radiation sources and after a short period of heat radiation measurement preferably by means of pyrometers, wherein the temperature differences determined a measure for the structural structure and the faults of the wood or the analogous materials » 2. The method according to item 1, characterized in that the heat radiation sources and the devices for heat radiation measurement, preferably pyrometers, are usually arranged perpendicular to both material broad sides · Method according to points 1 and 2, characterized in that the distance between the respective broad side of the material and the heat radiation source can be regulated, depending on the type and nature of the test material, the type and power of the heat radiation source and on the feed speed of the test material · 4 »method according to item 1 to 3, characterized in that the heating takes place significantly above the average ambient temperature, wherein heating temperature to be selected heat radiation source and device type for heat radiation measurement, z., Preferably the pyrometer type, to be closely considered and set are.