U.S. patent number 3,902,673 [Application Number 05/412,464] was granted by the patent office on 1975-09-02 for refining machine.
This patent grant is currently assigned to AB Krima Maskinfabrik. Invention is credited to Torsten Lennart Berggren.
United States Patent |
3,902,673 |
Berggren |
September 2, 1975 |
Refining machine
Abstract
A refining machine for fragmented beating material comprises a
rotationally symmetric, annular infeed channel for the beating
material, the infeed channel being formed between a central body
and an outer part surrounding the central body. The annular infeed
channel has a gradually increasing inner and outer diameter in the
feed direction of the beating material, and the central body and
outer part are rotatably mounted relative to each other, each
supporting its own annular part of a beating means which is
arranged to be passed by the beating material after being fed
through the infeed channel. The infeed channel redirects the
movement of the beating material essentially radially outwardly in
relation to the center of rotation of the beating means.
Inventors: |
Berggren; Torsten Lennart
(Naasjo, SW) |
Assignee: |
AB Krima Maskinfabrik (Nassjo,
SW)
|
Family
ID: |
20299013 |
Appl.
No.: |
05/412,464 |
Filed: |
November 2, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Nov 7, 1972 [SW] |
|
|
14386/72 |
|
Current U.S.
Class: |
241/246;
241/257.1 |
Current CPC
Class: |
B02C
7/08 (20130101) |
Current International
Class: |
B02C
7/00 (20060101); B02C 7/08 (20060101); B02C
007/08 () |
Field of
Search: |
;241/162,245,246,248,251,257R,261.2,188A,275 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Custer, Jr.; Granville Y.
Assistant Examiner: Goldberg; Howard N.
Attorney, Agent or Firm: Flynn & Frishauf
Claims
What is claimed is:
1. A refining machine for fragmented beating material such as wood
chippings, shavings and the like as well as for paper pulp in
higher, non-pumpable concentrations, comprising:
a central body;
an outer part surrounding said central body, said central body and
said outer part being rotatable in relation to each other about an
axis of rotation, said central body and said outer part being
spaced from each other so that a rotationally symmetric, annular
infeed channel is formed between said central body and said outer
part, said infeed channel feeding beating material over at least a
portion thereof generally in the direction of said axis of rotation
and having, in the feed direction of said feeding material,
gradually increasing inner and outer diameters, respectively;
beating means including first and second annular parts which are
respectively supported on said central body and said outer part,
said beating means being arranged to be passed by the beating
material after said beating material is passed through said infeed
channel;
the improvement wherein:
said infeed channel is shaped to redirect movement of said beating
material from a generally axial movement to a movement essentially
radially outwards in relation to the axis of rotation of said
beating means;
the generatrices to the two opposing limiting surfaces of said
infeed channel have a uniform continuous curvature along their
entire length, and further have a successively decreasing
inclination out toward said beating means, said inclination being
in relation to said beating means;
said limiting surfaces of said infeed channel are shaped such that
the total flow area of said infeed channel increases continuously
in a direction out towards said beating means;
the limiting surfaces of said infeed channel stagelessly pass
outwardly into said beating means;
means is provided to divide said infeed channel into a plurality of
generally spiral-shaped flow channels, said dividing means
including spiral-shaped vanes mounted on one of said limiting
surfaces of said infeed channel which is arranged to rotate, said
spiral-shaped vanes protruding into said infeed channel and
extending substantially up to the opposite limiting surface,
thereby dividing said infeed channel into said spiral-shaped flow
channels; and
said beating means has a coarse and a fine beating zone and wherein
each of said vanes is terminated with a tongue protruding into said
coarse beating zone.
2. A refining machine according to claim 1 wherein said opposing
surfaces of said infeed channel converge in the direction out
towards said beating means.
3. A refining machine according to claim 1 wherein said central
body is rotatable about said axis of rotation and said outer part
surrounding said central body is stationary.
4. A refining machine according to claim 3 wherein said opposing
surfaces of said infeed channel converge in the direction out
towards said beating means.
Description
This invention relates to a refining machine for fragmented beating
material such as wood chippings, shavings and the like as well as
paper pulps in higher, non-pumpable concentrations, and more
specifically, the invention relates to the feed part of the
refining machine, in which the beating material is redirected from
an axial to an essentially radial movement.
In known refining machines of this kind the infeed channel is
usually constructed either as a channel arranged in line with the
axis of rotation (see e.g. Swedish Pat. No. 321,143 ), the beating
material being imparted a movement in the radial direction with the
aid of ejector vanes only after it has arrived largely right up to
the flat rotor disc, or else the infeed channel is constructed as
an axially extended, annular, successively narrowing infeed zone
(see e.g. Swedish Pat. No. 178,642), the limiting walls of the
infeed zone being provided with opposite bars for achievement of a
preliminary processing or rough grinding of the beating
material.
The first-mentioned known construction of the infeed channel has
the disadvantage that when the highly concentrated and/or
fragmented beating material is fed towards the ejector vanes,
blocking easily occurs in the final end of the cylindrical feed
pipe, the reason being that the transition from axial to radial
movement is all too sudden. In order to eliminate irregular or
uneven feed in this design it is usually necessary to add a certain
quantity of water to the beating material before it is fed in for
refining. This dilution of the beating material has a detrimental
effect on the refining result and raises the energy consumption
counted per ton of beating material. Moreover, it is usually
necessary to apply high power to the infeed means in order to
overcome continuous tendencies of blocking.
The disadvantage of the other alternative construction of the
infeed channel is that in pretreatment of the fed beating material
in the infeed zone an extremely marked limitation is obtained in
the capacity of the refining machine which is due to, among other
things, the limited diameter and thus limited peripheral speed of
the rotating part. Since the surface of the rotating part is here
normally given such a shape that the generatrices to it are
S-shaped, there is obtained from that part of the S-curve which has
a convex shape counted from the rotor shaft a strong counteraction
against the infeed of the beating material. This counteraction
arises in consequence of the fact that the rotating part has a
tendency to form a cavity in the fed plug of beating material,
which makes impossible continuous and uniform feeding, something
which is wholly decisive for the attainment of a good refining
result. For example, in refining of wood chippings with this type
of feed there is not obtained in the prebeating or rough-grinding
zone a wanted homogeneous fibrous material but instead a
heterogeneous material consisting of wood flour and splinters. If,
for example, in refining of chips, steam is generated in the
beating zone the feed will be pulsating and the quality of the
refined beating material will thus be irregular. The pretreatment
also involves rapid wear of the bars of both rotor and stator
which, since these parts are not replaceable, causes the running
costs for a machine of this type to be relatively high.
The main object of this invention is to achieve an improved
refining machine for fragmented beating material such as wood
chippings, shavings and the like as well as for paper pulp in
higher, non-pumpable concentrations, which gives a uniform and high
quality of refined material.
SUMMARY OF THE INVENTION
The invention is based on the realization that in order for a good
refining result to be obtained it is absolutely essential to
achieve a uniform and continuous flow of beating material to the
beating means. This implies that the infeed channel must not
contain any stages or have any constriction or protruding part
which leads to reoccurring tendencies to blockages or cavities in
the fed material, since this results in a pulsating flow of the
material to the beating means. It is also of the utmost importance
that no prebeating or precrushing of the beating material takes
place in the infeed channel, which otherwise would also give rise
to a varying flow. Such precrushing is unavoidably obtained if feed
vanes protruding into the infeed channel have a relatively small
height, which allows fragmented beating material to penetrate
between them and the opposite surface.
A refining machine according to the invention comprises a
rotationally symmetric, annular infeed channel for the beating
material formed between a central body and an outer part
surrounding the central body. The annular infeed channel in the
feed direction has increasing inner and outer diameters
respectively, and the central body and outer part are rotatable in
relation to each other, each supporting its own annular part of a
beating means which is arranged to be passed by the beating
material after being, in the infeed channel, redirected for
movement essentially radially outwards in relation to the centre of
rotation of the beating means. The particular distinguishing
feature of the refining machine is the combination that the
generatrices to the two opposing limiting surfaces of the infeed
channel have a uniform, continuous curvature along their entire
length and out towards the beating means a successively decreasing
inclination in relation thereto, that the said limiting surfaces
are of such a shape that the total flow area of the channel
increases continuously in a direction out towards the beating
means, that the limiting surfaces stagelessly pass into the said
beating means and that one of the limiting surfaces of the infeed
channel which is arranged to rotate is provided with coiled vanes
protruding into the said channel which extend largely right up to
the opposite limiting surface and have a shape adapted to the said
surface for division of the infeed channel into spiral-shaped flow
channels.
In a preferred embodiment of this arrangement, the central body is
elaborated as a rotor and the part surrounding it as a stator.
By avoiding, in accordance with the invention, treatment of the
beating material in the infeed channel and instead utilizing a
combined coarse and fine beating means and making the limiting
surfaces of the infeed channel with a uniform, continuous
curvature, at the same time as the total flow area of the channel
increases in the direction out towards the grinding means, the
resistance against feeding of the beating means is reduced to a
minimum and all tendencies towards blocking of the feed are
avoided. This results in a very uniform and high quality of refined
material.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail with
reference to the accompanying drawing, in which FIG. 1 shows a
preferred embodiment of the refining machine according to the
invention, partly in section and FIG. 2 is a top view of the vanes
and beating means with the housing removed.
DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS
In the drawing, reference numeral 10 designates a transport channel
for a beating material which can comprise, for instance, wood
chippings, shavings, paper pulp and the like. The material is fed
along the channel 10 by means of a feed screw 11. The transport
channel is connected by suitable means, for example via
interconnected flanges, to a refining machine comprising an annular
beating means 12, to which the beating material is fed via a
rotationally symmetric, annular infeed channel 13. The outer and
inner diameters of the infeed channel 13 increase continuously in
the direction from the transport channel 10 out towards the beating
means 12 in such a manner that the beating material in the said
channel is redirected from an essentially axial movement at the
transition to the infeed channel to an essentially radial movement
upon entering into the beating means.
The infeed channel 13 is bounded by a rotor 14 and a fixed outer
part 15 surrounding rotor 14. The rotor is driven via an axle 16 by
a drive motor (not shown). The surfaces of the rotor 14 and outer
part 15 respectively that limit the annular, rotationally symmetric
infeed channel 13 are so constructed that the generatrices to them
have a uniform, continuous curvature along their entire length and
change stagelessly into the key-shaped limiting surfaces of the
beating means 12. The shown form of the infeed channel 13 also
gives a continuously increased flow area from the transport channel
10 and out towards the beating means for the beating material
without any constriction.
The beating means 12 can comprise any known beating means which
includes two annular discs 17 and 18 which are rotatable in
relation to each other. The discs are provided with interacting
radial and/or lateral bars 22 and form a key-shaped prebeating or
rough grinding zone diminishing from the infeed channel and a
following final beating zone. For effective feeding and uniform
distribution of the beating material in the key-shaped prebeating
zone of the beating means the rotor 14 is equipped with coiled or
spiral-shaped twisted vanes 19. See FIG. 2. The feed vanes 19 are
terminated with a tongue 20 which protrudes into the rough-grinding
zone of the beating means 12. The tongues 20 can appropriately be
detachably mounted on the feed vanes, so that they can easily be
exchanged, and are preferably made with an edge surface coated with
an abrasion-resistant material. These tongues serve to effectuate
the pressing in of the beating material into the prebeating zone
and counteract any tendency of steam that may be generated in the
final beating zone to press back the beating material.
Mounted between the feed screw 11 fitted in the transport channel
10 and the infeed channel 13 is a propeller 21. The propeller 21 is
intended to divide and homogenise the beating material fed via the
screw and is suitably made with the working edges thereof coated
with abrasion-resistant material. In addition, the propeller 21
helps to impart to the beating material such a movement that the
entry thereof into the spiral-shaped pockets serves as flow
channels formed between the vanes 19 of the rotor 14. To facilitate
passage of the beating material through the infeed channel 13 the
surfaces which come into contact with the beating material are
appropriately coated with a wear-resistant material having a low
coefficient of friction against the envisaged beating material.
The described device is thus made to exercise the least possible
resistance against the infeed of the beating material. It is then
extremely important for the surfaces limiting the infeed channel 13
to have the shown uniform and continuous curvature and the
stageless transition into the limiting surfaces of the beating
means. The curve shape of the tow limiting surfaces appropriately
comprises arcs with different radii. No pretreatment of the beating
material takes place in the infeed channel which is so constructed
that its flow area increases continuously from the inlet side to
the discharge side, the total increase in area amounting
appropriately to 100-200%.
The embodiment of the invention described above can be varied in
several respects without departing from the inventive concept. For
example, the infeed of the beating material and the relative
rotation between the two discs of the beating means can be achieved
by providing the outer part 15 with high vanes and allowing it to
rotate around the central body 14. Alternatively, both the body 14
and the part 15 can be arranged to rotate with different speeds or
in different directions around a common rotational shaft. The shape
of the curve of the infeed channel's limiting surfaces can be
chosen as desired, as long as the demands that the generatrices of
the surfaces must have a uniform, continuous curvature with
decreasing inclination in relation to the beating means and that
the flow area of the channel must increase in the direction out
towards the beating means are satisfied.
* * * * *