Note: Descriptions are shown in the official language in which they were submitted.
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Frame construction for a pressure grinding machine
of press type
The present invention is concerned with a
~rame construction for a pressure ~rindin~ machine of
press type, which frame construction comprises a ~as-ti~ht,
pressure-proof ~rinding chamber, bearing housings for
a grinder member revolving in the ~rinding chamber, as
well as at least one press chamber for the
pulpwood and a press device limitin~ the press
chamber on one side.
Such a frame construction is used in a
pressure grindin~ machine in which groundwood is pre-
pared by pressing the pulpwood by means of the press
device against a revolving grindstone in a pressurized
grinding chamber.
From the Finnish Patent 58,359, a pressure
grindin~ machine is previously known in which a rotary
grinder member, commonly a ceramic grindstone, is
installed in a gas-tight, pressure-proo box-like frame.
The ~rame is designed so that is compris~s a press
chamber for the pulpwood, surrounded by the grinding
chamber, the said press chamber havin~ the same posi-
tive pressure as the grinding chamber itself, as well
as a space for the press device. The grindstone is
jo~rnalled in bearings placed outside the frame, the
said bearings being attached to the frame by the inter-
mediate of the base plate.
The press device comprises a shoe moving
linearly towards the grindstone, and an actua~ing
device moving the said shoe, usually a hydraulic
workin~ cylinder, which is attached to the end o~
the frame.
A pressure grinding machine intend~d for
laboratory use is also known which is provided with
a cylindrical frame whose longitudinal axi~ is parallel
to the axis o~ rotation of the grindstone and to which
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frame the bearin~s of -the grindstone as well as the
press chamber for the pulpwood to~ether with the press
device are attached.
In the pr.ior-art pressure ~rinding machines,
besides the uniform load caused by the positive pressure
prevailing in the grinding chamber, a tensile load is
also directed at the frame, resulting ~rom the pressing
of the pulpwood against the grindstone, the said tensile
load bein~ passed from the press device along the walls
of the frame to the bearings of the grindstone. Thereat,
the construction of the frame becomes heavy, and con-
sequently the cost of its manufacture becomes high.
The designing and dimensioning of the frame as a pres-
sure vessel is difficult, and the margins of safety
become high. The box-shaped frame used in a pressure
grinding machine of production scale, moreover, has a
highly disadvantageous shape in view of the pressure
loading. Since the tensile strains are received by
means of the side walls of the frame, large openings
should be avoided in those walls. This is wh~ the
feed-in opening for the pu:Lpwood must be placed at the
top face of the frame, which again increases the
construction height required in the grinding plant.
The object of the present invention is to
provide a frame construction which avoids the above
drawbacks and permits a more purposeful receiving of
the pressure loads and tensile loads acting upon the
frame construction. This objecti~e is achieved by
means of a frame construction in accordance with the
invention, which is charactexized in that the frame
construction consists of two separate parts, namelY
- a pressure ~rame r which constitutes the
said grinding chamber and press chamber and which s~lb-
stantially receives the pressure forces resulting from
the positive pressure prevailing in the grinding
chamber, and
- a power frame, which connects the press
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device and the bearing housings of the grindstone to
each other and which substantially receives the tensile
and circumferential forces resultin~ from the grinding
and from the pressing of the wood against the grindstone~
The invention is based on the idea that by
forming the frame construction out of two parts, it is
possible, in a more favourable way, to dimension and to
design one of the frames so as to stand pressure strains
and the other frame so as to stand tensile strains, and
thereby to achieve a frame construction that is of lower
weight and advantageous as a whole. Thereby the pres-
sure frame receives the internal pressure load, and the
power frame acts as a transmitter of tensile load
between the press device and the bearings of the grind-
stone.
It is preferable that the shape of the pres-
sure frame is cylindrical, which permits a minimation
of the material strength. The longitudinal axis of the
pressure frame is preferably perpendicular to the axis
of rotation of the grindstone, so that, inside the
pressure frame, a box-shaped press chamber can be
installed for the pulpwood" which press chamber,at the
same time, acts as a guide for the shoe of the press
device.
The main strain directed at the power frame
is the tensile load arising from the press force of
the press device, which permits the use of a system
of tensile beams as the power frame. To the tensile
beams are attached a rigid fastening member for the
press device as well as the bearings of the grindstone.
The tensile beams also carry the pressure frame.
The pressure frame and the power frame may
be connected to each other by means of a separate
rigid piece to which the bearings of the grindstone
are fixed.
The set of tensiLe beams acting as the
power frame is favourably designed such that the feecl-in
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opening of the pulpwood can be placed horizontally at
the side of the pressure frame, whereat the necessary
construction height in -the grinding plant is reduced.
The invention wiLl he described in more detail
below with reference to the attached drawings, ~herein
Figure 1 is a pa.rtly sectional side view of
a pressure grinding machine provided with a preferred
embodiment of the frame construction in accordanee with
the present invention,
Figure 2 is a hori20ntal sectional view of
the grinding machine along line II-II in Fig. 1,
Figure 3 is a vertical sectional view of the
grinding machine along line III-III in Fig~ 1,
Figure 4 illustrates the load diagram of the ~r
construction,
Figure 5 is a pexspective view of a pressure
grinding machine provided ~ith a frame construction in
accordanee with a second embodiment,
Figure 6 is a perspective view of ~ pressure
grinding machine provided with a frame construction in
aecordance with a third embodiment,
Figure 7 is a perspective view of a pressure
grindir~g machine provided with a frame construction in
accordance with a fourth embodiment, and
- 25 Figures 8 and ~ show a further embodiment of
the frame construction as a side view and as a section
along line IX-IX in Fig. 8, respeetively.
The pressure grinding maehine shown in
Figures 1 to ~ comprises a cylindrical, gas-tight and
pressure-proof pressure frame 1, at one of whose ends
a grinding chamber 2 is formed. In the c3rindincJ
chamber, a grinding member 3 is installed, whose a~is
of ro~ation ~ is positioned perpendicularl~ to the lon~i-
tudinal axis of the pressure frame and is supported by
outside bearings S. The pressure frame i5 providPd
with sealed passages 6 for the axis of rotation.
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Inside the pressure frame, a box-shaped ele-
ment 7 is installed which forms a press chamber 8 for
the pulpwood, open towards the grindstone. The press
chamber is, in one direction, limited by a shoe 9, which
is attached to the piston rod 11 of a hydraulic cylinder
10. For the purpose of guiding the shoe, the box-shaped
element is provided with inside guides 12. The element
7 is fixed by means of supports 14 to the pressure
frame and to outside supports 15. The hydraulic cylin-
der extends through the sealed passage 16 formed intothe pressure frame and is fixed to the outside support 17.
The frame construction additionally comprises
a power frame 18, which, in this example, consists of
two beams 19 placed outside the pres~ure fra~e and
extending along the sides of the pressure frame, being
parallel to the longitudinal axis of the pressure frame,
the bearings 5 of the grindstone and the supports 15 of
the pressure frame and the support 17 of the hydraulic
cylinder being attached to the said two beams 19.
The pressure frame supports a feed-in
pocket 20 for pulpwood, which pocket is placed above
the press chamber and can be closed pressure-proof.
The bottom of the pressure frame is provided with an
outlet opening for the discharge of the groundwood
pulp out of the pulp basin formed in the bottom part
of the pressure frame. The grinding machine additionally
comprises a motor, not shown, for rotating the grind-
stone.
The pressure frame 1 is dimensioned and designed
so as to stand the constant positive pressure maintained
in the grinding chamber. The power frame 18 is dimen-
sioned and desi~nedso as to stand the tensile orces
that are produced when the pulpwood is being pressed
by means of the hydraulic cylinder 10 against the
revolving grindstone for the purpose of grinding the
wood, as well as the circumferential ~orce that is
produced when the grindstone revolves against the
pulpwood. Fig. 4 illustrates the loading acting
upon the frame construction. It is noticed that the
power frame receives the said tensile and circum-
Eerential forces substantially alone and acts as a
ri~id -transmitter of the tensile forces between the
bearings of the grinclstone and the press device, whereat
the pressure frame becomes free from the load caused
by these forces.
The frame construction shown in Fig. 5 differs
from the above embodiment mainly in the respect that
the supports 15, by means of which the pressure frame 1
is, in Fig. 2, supported on the power frame 18, have
been m~de a separate rigid piece 25, which surrounds
the pressure frame. At opposite walls of the riqid
piece, bearings 5 have been installed for the axis of
rotation of the grindstone. The beams of the power
frame have been attached to the rigid piece.
The frame construction shown in Fi~. 6
differs from the embodiment of Fig~ 5 mainly in the
respect that the box~shaped element 7 described in
relation to Fig. 1 is here dimensioned and designed as
the power frame 28, which is placed inside the pressure
frame 1 and attached to the rigid piece 25.
The pressure grinding machine can also be
constructed as a machine comprising two press devices
and two prèss chambers, as is illustrated in Fig. 6.
In the frame construction shown in Fig. 7,
which substantially corresponds to that shown in Fig. 5,
the beams of the power frame 3~ are placed so that
a free space remains at the side of the pressure frame
or the feed-in pocket 30 for pulpwood.
Similarly to the embodiment shown in Fig~ 6,
the frame construction shown in Figures ~ and 9 is
based on the utilization of the box-shaped element 7
in the formation of the power frame. The box-shaped
element 7 located inside the pressure frame 1 is
dimensioned and desi~ned as a part of the power frame
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48, which part is attached by means of supports 14 -to
the supports 15 outside the pressure frame. The supports
15 are attached to the beams 19' placed at the sides of
the pressure frame, which beams support the bearings 5
of the grinding member.
The drawings and the related description are
just supposed to illustrate the idea of -the invention.
In its details, the frame construction in accordance with
the invention may show even considerable variation
within the scope of the patent claims.
