DD277331A1 - METHOD FOR MEASURING THE TYPE OF WOOD TYPE - Google Patents

Abstract

The invention relates to a method for measuring the amount of wood species in a deciduous and Nadelhoelzern existing wood species mixture for the production of particleboard, fiberboard or pulp. The object according to the invention is achieved by measuring the extinction of a mixture sample in the mid-infrared range at a wavelength of approximately 5 754 nm or in the near infrared range at a wavelength of 2 358 nm. It was found that the extinction values measured in this way represent the mixing ratio of softwood / deciduous wood. At the specified wavelength, there is a significant dependency of the mixture ratio deciduous to coniferous wood of the height or surface of the extinction level. It is possible, in the mid-infrared measurement, to obtain the absorbance values on a neutral absorbance value measured on the same mixture sample with the same equipment, which is preferably determined at a wavelength of about 11 148 nm. This eliminates complex calibrations. No reference value is required for NIR spectroscopy. Due to the relationship between the mixture ratio and the extinction values based on the internal standard, the mixing ratio between deciduous and coniferous wood can be determined or predicted by means of regression analysis or also by classification methods.

Description

Field of application of the invention

The invention relates to a method for measuring the amount of wood species in a deciduous and coniferous wood species mixture for the production of particleboard, fiberboard or pulp.

Characteristic of the known state of the art

For the production of chipboard, fiberboard or pulp wood species mixtures of deciduous and coniferous wood, such as birch, hornbeam and pine are used. The properties of the products made from them are largely determined by the proportion of softwood in the wood garden mixture. An insufficient proportion leads to inadmissible quality reductions. Currently, plant personnel largely determine the amount of wood species visually. According to this subjective assessment, the material used is relatively coarse (eg shovel loader, occupancy of the conveyor line for round wood chipping). The safety of this method is low. The resulting greater variations in quality are counteracted by increasing the average gross density beyond what is objectively necessary. To ensure the minimum quality, the material usage is higher than required.

Object of the invention

The aim of the invention is the reduction of material costs in the production of particleboard, fiberboard or pulp.

Explanation of the essence of the invention

The object of the invention is to measure the proportion of wood species in wood species mixtures.

According to the invention, this object is achieved in that the extinction of a mixture sample in the mid-infrared region at a wavelength of about 5754 nm and in the near infrared region at a wavelength of 2358 nm is measured.

It was found that the extinction values measured in this way represent the mixing ratio softwood / hardwood.

At the indicated wavelengths there is a significant dependence of the mixing ratio deciduous to softwood in the height or area of the extinction level. It is possible, in the mid-infrared measurement, to obtain the absorbance values on a neutral absorbance value measured on the same mixture sample with the same instrument, which is preferably determined at a wavelength of about 11148 nm. This eliminates complex calibrations. No reference value is required for NIR spectroscopy.

Due to the dependency between the mixing ratio and the extinction values related to the internal standard, the regression analysis or c / irch classification methods (cluster analysis) can be used to determine the r. .Ischungsverhältnis between hardwood and softwoods are determined or predicted.

embodiment

Hardwood (50% oak, 50% beech) and softwood (pine) were mixed in various proportions, ground and pressed into tablets (material weight 5.5mg) using potassium bromide. Using an infrared spectrophotometer (Specord M 80 from the Kombinat VEB Carl Zeis JENA), the extinction values following in the table were measured at a wavelength of 57 nm.sup.4 nm. At a wavelength of 11148 nm, there is no influence of the mixing ratio on the absorbance value. Line 3 contains the relative values related to this inner standard.

Mixing ratio softwood / hardwood (% by mass) 100/0 75/25 50/50 33/66 0/100 Absorbance values at 5754nm. rel. values 0.16 2.00 0.21 2.67 0.27 3.38 0.30 3.80 0.36 4.50

Approximately equally good results are obtained for measurements in the NIR range at a wavelength of 2358 nm: mixing ratio Pine / Beech 100/0 75/25 50/50 33/66 0/100 absorbance,

relative, relative to

the first value 1.00 1.08 1.17 1.27 1.39

Claims (3)

Anspruch [en] A process for measuring the amount of wood species in a wood species mixture consisting of deciduous and coniferous woods for producing chipboards or fibreboards, characterized in that the extinction of a mixture sample is in the mid-infrared range at a wavelength of approximately 5754 nm or in the near infrared range at a wavelength of 2358nm is measured. 2. The method according to claim 1, characterized in that the values measured in the mid-infrared range are related to a neutral Absinktionswert which was determined for the same mixture sample with the infrared spectrophotometer. 3. The method according to claim 2, characterized in that the neutral Absinktionswert is determined at a wavelength of about 11148nm.