|Title of Invention||
A METHOD AND A DEVICE FOR PRODUCING ORIENTED STRAND CHIPS FOR ORIENTED STRAND BOARDS.
|Abstract||THE INVENTION RELATES TO A METHOD FOR PROCESSING AN INTERMEDIATE PRODUCT AND A WOOD HIPPING DEVICE FOR PROCESSING AN INTERMEDIATE PRODUCT. THE INTERMEDIATE PRODUCT (20) IS SUBSTNTIALLYU ROD-SHAPED AND IS BETWEEN ONE AND TWO TIMESAS LONG AS ORIENTED STRAND (OS) CHIPS. THE INTERMEDIATE PRODUCT IS FED TO A WOOD-CHIPPING DEVICE COMPRISING A LARGE NUMBER OF BLADES (4), WHOSE CUTTING EDGES RUN AT LEAST APPROXIMATELY PARALLEL TO THE BVLADE RING AXIS (2) AND WHICH ENCOLOSE A WORKING CHAMBER. THE INTERMEDIATE PRODUCT IS ROTTED ABOUT THE BLADE RING AXIS AND ISALIGNED IN SUCH A WAY THAT IT LIES SUBSTANTRIALLY PARLLEL TO SAID RING AXIS AND IS PRESSED BY CENTRIFUGAL FORCE AGAINST THE CUTTING EDGES OF THE BLADES. (FIG.2)|
|Full Text||FIELD OF INVENTION
The invention relates to a method as well as a device for producing wood chips.
For this, there are basically two systems, which differ fundamentally from each
other and which, accordingly, also produce different products.
BACKGROUND OF THE INVENTION
A first system relates to so-called direct chippers. In it uncut round timber is fed
into a chute. Arranged parallel to the axis along which the wood is fed is a knife
ring, which is equipped along its circumference with a large number of knives.
The cutting edges of the knives run parallel to the knife ring. The knife ring can
move in such a way that it plunges into the body of the round timber and is able
to chip it. See, for example,
DE 2,947,199 Cl.
Another design of direct chippers which belongs to the first system mentioned,
has a disk that is mounted so that it can pivot. The disk carries chipping knives
on one of its side faces. The round timber or tree stumps are fed to this working
face in a direction parallel to the fibers. Because the circumferential speeds of
the individual face elements of the working face differ in magnitude depending
on whether the face element lies radially inward or radially outward, the chipping
result also differs and this is detrimental to the quality.
The machines mentioned, which belong to the first system, serve above all, to
produce so-called oriented strand (OS) chips. The first of these chips are
oriented along the lengthwise direction of the chip. The chip is extremely thin. It
serves to produce boards of the same name, so-called oriented strand boards
(OSB). These are regarded as being of high quality. They have great strength, so
that they can be used as construction elements for the construction of
prefabricated houses, for example.
The second system mentioned uses so-called knife chippers. These consist of a
ring or collar that is made up of knives, whose cutting edges run, at least largely,
parallel to the ring axis. The knife encloses a working chamber in which the
chippers are introduced into a radially inner region through a filling shaft. A rotor
spins the chippings radially outward against the inner face of the knife and thus
against the cutting edges of the knives, where chipping takes place.
The intermediate product that is fed to the chipper consists of appreciably
smaller particles, namely, chippings, that were produced beforehand in a
chopping process. In quite generalized terms, they have , at least to an
approximation, the size of a match box.
The chips that can be produced by a knife ring chipper differ quite fundamentally
from the OS chips produced by the first-mentioned category of machines, which
operate according to the first-mentioned system. They are essentially pin-shaped
and are reminiscent of thin matches. These chips can be processed only into
chipboards or particle boards. However particle boards are of only limited
strength and, in particular, they have no special flexural strength. Thus, they
cannot be used as construction elements, but instead find application in the
The advantages and drawbacks of machines of the first-mentioned system -
direct chippers for producing OS chips - and of the second-mentioned system
with the preceding stage for producing chippings and the final result of chips for
particle boards can be summarized as follows:
Direct chippers require, in general, fresh wood, that is, tree trunks of, for
example one meter. Although they are capable of producing high-quality OS
chips, they have comparatively large dimensions on account of the large
dimensions of the intermediate product. Accordingly, it is extremely expensive to
purchase them. The investment costs lie between one and three million DM.
Accordingly, they also have relatively little flexibility in use.
Chippers, by contrast, are smaller, more flexible, and more advantageous in cost
to purchase. However, they are not capable of producing OSB chips, but only the
lower-quality matchlike chips for particle boards.
US A-2 874909 (LUDWIG PALLMANN) discloses a process for producing oriented
strand towards comprising the steps of : producing an initial product from
recycled wood, said initial product is substantially rod-shaped and fed to a
chipper comprising a large number of knives disposed on a knife disc which have
cutting edges extending parallel to the disc axis and surround a working area;
said initial product is rotated about the knife disc axis and is aligned so that it is
substantially parallel to the disc axis and presses with centrifugal force against
the cutting edges of the knives; the operating parameters are selected so as to
produce a particle thickness; the initial product is subjected to a draw cut and
the chips are processed to from oriented strand boards.
OBJECT OF INVENTION
The object of the invention is to present a method and a device that allows so-
called fresh wood as well as recycled wood to be used as intermediate product,
has appreciably less construction volume than the known direct chippers,
therefore requires lower investment costs, and is flexible in use and that is also
fundamentally suitable for producing OSB chips.
SUMMARY OF THE INVENTION
The inventor has thus freed himself of a widely held prejudice. He has resorted
to the basic features of the knife ring chipper, but has fundamentally changed
the conditions surrounding it. This relates, in particular, to the choice of the
dimensions of the intermediate product. The later has a greater first dimension
than the dimension perpendicular to it, so that the intermediate product could be
referred to as rod-shaped.
With a method is accordance with the invention and a corresponding device, it is
now possible to use highly differing intermediate products, namely, both fresh
wood of excellent quality and fresh wood of less good quality, such as dwarf
timber and branches, as well as recycled wood. Coming into consideration here
as recycled wood is, for example, wood packaging, which is very common.
The method and device in accordance with the invention can-as mentioned -
produce high-quality OSB chips, but, at the same time, also chips of lesser
quality. If different categories of chips are produced, these can be classified by a
subsequent classification step.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention is explained in more detail on the basis of the accompanying
drawings. Represented therein individually are the following:
Fig. 1 shows a chipper in a front view, that is, in a view on that side on which
the casing cover together with the spout for the intermediate product is situated.
Fig. 2 shows on an enlarged scale, an axial section of the chipper in accordance
with Fig. 1.
Fig. 3 shows in an enlarged representation, a section taken from Fig. 2. namely,
a knife set.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
As seen from Figures 1 and 2 individually, the chipper consists of a rotor, which
is driven by a shaft 2. The rotor 1 contains a collar of blades 3, which are parallel
to the axis. A knife box with knives 4, which are likewise arranged parallel to the
axis, surrounds the rotor 1. Rotor 1 and the knife box are, in turn, arranged in a
casing 5 and jointly enclosed by it. Casing 5 has an inlet 6 for the chipping that
are to be fed in as well as a discharge for the finished chips.
Figure 2 illustrates a rod-shaped intermediate product 20 at two sites. In the
present case, this is delivered as a block in the shape of a regular rectangle.
Instead, however, this intermediate product could be of a different shape - for
example, it could have irregular peripheral surfaces. It is essential only that this
intermediate product 20 be more or less rod-shaped that is, it has a lengthwise
dimension that is greater than the crosswise dimensions in planes running
perpendicular to it.
The intermediate product 20 is fed into the shaft-shaped inlet 6 - see arrow. It
then arrives at the inner chamber that is enclosed by the rotor 1. In doing so,
the intermediate product 20 comes to lie - either automatically or by means of a
corresponding orienting device - in such a way that it is oriented mainly along
the lengthwise axis of the rotor shaft 2 and thus more or less parallel to the
knives 4. The intermediate product is of substantial length in comparison with
the chipping that re fed to the knife ring chippers that have been commonly used
up to now.
In figures 3 and 4, two knife sets are represented in a section perpendicular to
the axis. These two knife sets are each a component of the knife ring of the
Each knife set is constructed as follows: A supporting bedplate 10 bears cutting
knife 11, which is attached to the supporting bedplate 10 by means of a
clamping plate 12 and a screw 13.
Each supporting bedplate 10 has a wear surface 10.1. It is crucial that these
wear surfaces 10.1, which face the machine axis, are nearly flat and thus not
concentric, as in the prior art.
In the case of the figure here, the wear surface 10.1 is made up of a plate 10.2,
which in turn, is attached to the remaining supporting bedplate 10. In the case
of Figure 4, the wear surface 10.1 is made up of a wear layer that is produced by
application of a wear layer, preferably by build-up welding or spraying and
subsequent smooth grinding.
In the embodiment in accordance with Figure 3, a knife with M teeth 14, is
provided, which is attached to the side of the supporting bedplate 10 lying
opposite to the cutting knife 11 and which works together with the cutting knife
of the neighboring knife set. The embodiment in accordance with Figure 4 is an
embodiment without knives with M teeth.
1. Method for producing oriented strand (OS) chips for manufacture of OS
boards with the following steps:
an intermediate product (20) is produced from fresh wood or recycled
wood, the intermediate product (20) is substantially rod-shaped, the
intermediate product (20) is fed into a chipping machine comprising a
large number of blades (4), which are arranged on a blade ring, the
cutting edges of which run at least approximately parallel to the ring axis
and which enclose a working chamber, the intermediate product (20) is
rotated around the blade ring axis and is aligned in such a way that it lies
essentially parallel to the ring axis and is pressed centrifugal force against
the cutting edges of the blades (4), the intermediate product (20) has a
length of 80 to 150 mm, the intermediate product (20) has a width of in
the order of at least 20 mm, the operating parameters such as the blade
design, the blade angle are selected so that OS chips are produced with a
chip thickness of 0.2 to 0.6 m, preferably from 0.2 to 0.4 mm, a sifter
stage is arranged upstream of the chipping in order only to allow through
intermediate products with specific dimensions, a classifying stage is
arranged after the chipping stage in order to classify stage is arranged
after the chipping stage in order to classify the chips according the criteria
of their design or dimensions or their weight.
2. A device for performing the method as claimed in claim 1, comprising a
housing (5) having an inlet (6) for the introduction of the preliminary
product (20), a rotor (1) enclosed by the housing (5), and a ring of knives
(4) whose blades face inwardly, the rotor (1) being provided with scoops (3)
which are inclined relative to the rotor axis (2), characterized in that the
scoops (3) of the rotor (1) are movable in a limited manner in the
3. The device as claimed in claim 2, wherein the scoops (3) of the rotor (1) are
suspended in a pendulum fashion at a radially inward position.
4. The device as claimed in one of the claims 2 to 3, wherein the rotor scoops
(3) are curved or bent off.
5. The device as claimed in one of the claims 2 to 4, wherein the parameters
of the knife (4) such as knife angle, clearance angle and the angle of
attack are selected in such a way that a peeling processing of the
preliminary product is obtained.
6. The device as claimed in one of the claims 2 to 5, wherein the
circumferential dimension between two mutually adjacent rotor scoops (3)
is two to three times the length of the preliminary product.
7. The device as claimed in one of the claims 2 to 6, wherein the axial
dimension of the knife ring (4) of the cutter is one to three times the
length of the preliminary product (20).
8. The device as claimed in one of the claims 2 to 7, wherein the working
spaced is provided upstream with an orientation device in order to supply
the preliminary product (20) at least substantially parallel to the ring axis.
The invention relates to a method for processing an intermediate product and a
wood-chipping device for processing an intermediate product. The intermediate
product (20) is substantially rod-shaped and is between one and two times as
long as oriented strand (OS) chips. The Intermediate product is fed to a wood-
chipping device comprising a large number of blades (4), whose cutting edges
run at least approximately parallel to the blade ring axis (2) and which enclose a
working chamber. The intermediate product is rotated about the blade ring axis
and is aligned in such a way that it lies substantially parallel to said ring axis and
is pressed by centrifugal force against the cutting edges of the blades.
|Indian Patent Application Number||588/KOLNP/2003|
|PG Journal Number||04/2008|
|Date of Filing||07-May-2003|
|Name of Patentee||B. MAIER ZERKLEINERUNGSTECHNIK GMBH,.|
|Applicant Address||POSTFACH 14 06 40,33625 BIELEFELD GERMANY|
|PCT International Classification Number||B27L 11/02|
|PCT International Application Number||PCT/EP01/12460|
|PCT International Filing date||2001-10-27|