Method for orientation of wood particles

FIELD: wood-working industry, applicable in production of wood particle boards.

SUBSTANCE: the method consists in operations of displacement of the guide member at a speed depending on the length of the orientated particles, parameters of the orientating device and the thickness of the formed chip mat, due to which the particles rotated by the guide member are placed in a chip mat in the process of fall with a minimum angle of orientation.

EFFECT: enhanced quality of orientation of chip particles due to minimization of the angle of orientation, which enhanced the strength of the produced wood particle boards.

1 dwg, 2 dwg, 2 ex

 

The invention relates to woodworking industry and can be used in the production of chipboard.

A known method of mechanical orientation of wood particles, including the filing of a cutting guide body made in the form of plates or chains, adjacent branches which move in opposite directions with a constant velocity [Schwartzman G.M., Generously D.A. Manufacture of chipboard. 4th ed., Rev. and supplementary): genre differences. prom the terrain, 1987. - 320 S., str].

The known method the orientation of the wood particles, including the filing of a cutting guide body made in the form of endless filaments, and moving the adjacent branches of the guide body in opposite directions with a constant velocity [Patent Switzerland No. 469558, MCL529 J 5/00. Verfahren für die Herstellung von Hoizspanplatten sowic Vorrichtung zur Ausfuhrung des Verfahrens. 1969].

The known method orientation implemented in the device for orientation pitched lignocellulosic particles by way of orientation, including the filing of a cutting guide body made in the form of an endless flexible belt, and moving the adjacent branches of the guide body in opposite directions with a constant speed of [the Federal Republic of Germany Patent No. 2730403, MCL529J 5/04. Vorrichtung zum Ausrichten von mit einem Bindemittet versehencn lignozellulosehaltigen Teilchen. 1980].

In the known methods of wood cha is the tics receive torque from the guide body and begin to fall from the corner α begrelative to the direction of orientation. During the fall prior to forming conveyor particles takes place on the corner αpand placed in a bonded carpet at an angle α and (orientation angle). The orientation angle is determined from the expression.

With decreasing angle α the strength of the finished plates decreases, approaching the strength of the original wood [Potashev PU, Lapshin YG Mechanics of wood-based panels. - M.: Genre Differences. prom the terrain, 1982. - 112 S., p.52]. In the ideal case, the angle α must be zero. The disadvantage of this method is that at the constant speed travel guide body with a change in the length of the oriented particles corner αbegchanged, and the angle αpremains constant. For example, when switching to the manufacture of plates of the longer shavings initial angle of descent of the particles with the guide body αnach(see drawing) decreases and becomes more of an angle αpand in the manufacture of slabs of shorter chips starting angle αnachincreases and becomes less of an angle αp, resulting in the orientation angle α increases the quality of the orientation will be reduced, and the durability of the finished chipboard will be a maximum.

There is also known a method of targeting implemented in in the trojstva for orientation of wood particles, including supply of chips on the guide body, made in the form of an endless flexible belt, and moving the adjacent branches of the guide body in opposite directions with a constant velocity [A.S. USSR №1449344, MCL627N 3/14. Device for orienting wood particles, 1989, BI No. 1].

The disadvantage of this method is that the constant speed travel guide body optimal only for a certain length of oriented particles, in which the strength of the manufactured plate maximum. In the manufacture of slabs of particles of a different size, the orientation angle α increases, which leads to loss of strength of manufactured boards.

The invention solves the problem of improving the quality orientation of the wood particles.

The technical result from the use of the invention is to improve the quality orientation by minimizing the angle of orientation of the wood particles, which increases the strength of manufactured chipboard.

This is achieved in that in the method the orientation of the wood particles, comprising a supply tank on the guide body and the movement of the adjacent branches of the guide body in opposite directions with a constant speed, according to the invention, the movement of the guide body exercise with speed (m/s)defined by the formula

where h is the distance between adjacent branches of the guide body, m;

H0- the height of the guide body over a forming conveyor, m;

Htothe thickness of the formed strand of carpet;

l is the length of the oriented particles, m

The inventive method the orientation of the wood particles is moving the guide body with a rate depending on the length of the oriented particles and settings orienting device, through which particles obtained the rotation of the guide body in the process of falling are placed in a bonded carpet with a minimum angle of orientation.

The drawing shows a simplified diagram of the orientation.

The formula for the speed of movement of the guide body, in which there is the most complete orientation of the particles, derived by the author for the first time.

The initial angle at which the escape of particles from the guide body, depends on the length of the particles and the distance between adjacent branches of the guide body

where h is the distance between adjacent branches of the guide body (step orientation), m;

l is the length of the oriented particles, m

At the time of separation of the particles have a speed

For the fall time t of the particles takes place on the corner αp:

Particles incident on a forming conveyor first, go the distance H0. Particles fit into bonded carpet thickness Htolast, pass the distance (H0-Nto). The average distance traveled by a wood particle is (N0-0,5·Nto).

The average time of fall of the particles

where g is the acceleration of gravity, m/s2.

Taking into account (2) and (4) the expression (3) is

For maximum orientation of the particles, in which the orientation angle α=0, must satisfy the condition: αbegpi.e. equating (1) and (5), we obtain the optimal speed of movement of the guide body (m/s)

Considering g=9,81 m/s2get

0,0193 - coefficient, m1/2·-1

Formula (7)linking step orientation, the height of the guide body, the thickness of the formed strand of carpet and the length of the oriented particles, derived by the author for the first time.

Air resistance practically does not change the coefficient 0,0193 in the expression (7). Taking into account the air resistance oriented particle falls to laying in the carpet a little longer, i.e. must be deployed at a greater angle α. However, the resistance is a group of air will prevent the spread of the particles. Thus, increasing the angle α due to a longer drop is compensated by the decrease of this angle due to the smaller spread.

The method is as follows.

The guide body moves with velocity V (m/s), and other branches of the guide body move in opposite directions. Wood particles serves to guide the body, which gives the particle rotation. The particles are expanded until they are laying in bonded carpet. When moving the guide body with optimal speed determined from the expression (7), the particles have a minimum angle of orientation.

An example of the method.

Wood chips from the supply conveyor serves to guide the body, which move at a speed determined by the formula (7). Of oriented so chips on the forming conveyor to form a single layer of bonded carpet, which is divided into briquettes and pressed.

Example 1

Was made the party a single layer of chipboard with thickness of 10 mm from pine shavings, having an average length of 40 mm (0.04 m). The height of placement of the guide body over a forming conveyor was 0.3 m, the step orientation is 0.025 m, the Thickness of the formed Mat was 0,042 m

The optimum speed of movement of the guide body of raschityvat the signing by the formula (7):

Chips in the party focused guiding body, which is moved with the velocity V=0,020 m/s with a 0.035 m/s and 0,050 m/S.

Measurement of the angles of deflection of the particle relative to the direction (axis) orientation was conducted for all the fully-visible particles on the upper and lower surfaces of the plates on arbitrary parts of the plates with an area of 200·200 mm when using the protractor. The measurement error was 0.5%.

Average results of 10 measurements are presented in table 1.

The average orientation angle αcfwas determined as the sum of the average inclination angles αithe fraction of particles γiat site

For example, for V=0.02 m/s:

Particle deviation from the axis orientation by more than 50 degrees (unoriented particles), on the face side of the plate was not observed.

0-9
Table 1

The deviation of the particles for l=0.04 m
The limits of deviation of the particle from the axis orientation, deg.The average angle of deviation αithe hail.The fraction of particles at the site γi, %
V=0,020 m/sV=0,035 m/sV=0,050 m/s
4,5165914
10-1914,5522149
20-2924,5191423
30-3934,5738
40-5045536
The average orientation angle αcfthe hail.
17,611,518,8

Example 2

Was made the party a single layer of chipboard with thickness of 10 mm from pine shavings, having an average length of 60 mm (0.06 m). The height of placement of the guide body over a forming conveyor was 0.3 m, the step orientation is 0.025 m, the Thickness of the formed Mat was 0,044 m

The optimum speed of movement of the guide body was calculated by the formula (7)

Chips in the party focused guiding body, which is moved with the velocity V=0,020 m/s with a 0.035 m/s and 0,050 m/S.

Measured the e average of the angles of deflection of the particle α iand the calculation of the average orientation angles αcfproduced by the same method as in example 1.

Average results of 10 measurements are presented in table 2.

Table 2

The deviation of the particles at l=0,06 m
The limits of deviation of the particle from the axis orientation, deg.The average angle of deviation αithe hail.The fraction of particles at the site γi, %
V=0,020 m/sV=0,035 m/sV=0,050 m/s
0-94,567138
10-1914,5166112
20-2924,5121338
30-3934,53812
40-504552510
The average orientation angle αcfthe hail.
7,25 17,626,9

The experimental results show that the smallest average angle of orientation of the particles have a plate formed in the speed guide body, close to the calculated by the formula proposed by the author.

The invention improves the quality of the orientation of wood particles and increase the strength of chipboards from oriented chips of different lengths.

The way the orientation of the wood particles, comprising a supply tank on the guide body and the movement of the adjacent branches of the guide body in opposite directions with a constant speed, characterized in that the movement of the guide body exercise with speed (m/s)defined by the formula

where 0,0193 - coefficient, m1/2·-1;

h - the distance between adjacent branches of the guide body, m;

H0- the height of the guide body over a forming conveyor, m;

Htothe thickness of the formed strand Mat, m;

l is the length of the oriented particles, m



 

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