Grinding equipment for a Jordan refiner

Grinding equipment for a Jordan refiner for grinding paper pulp having a rotating part in form of a truncated cone and a stationary part in the form of a hollow truncated cone, on which bar-shaped knives are arranged at predetermined angles with respect to the conical shell generating lines. To improve the grinding equipment of the refiner, a pre-grinding zone is arranged upstream of one or more fine grinding zones whose configuration and arrangement are adapted to the state and desired development of the fibers in the grinding stock flowing through the grinding equipment.

The invention relates to grinding equipment for a Jordan refiner for 
grinding paper pulp, comprising: 
a rotating part in the form of a truncated cone on the outer shell surface 
of which bar-shaped knives are arranged at predetermined angles with 
respect to the conical shell generating lines, and 
a stationary part in the form of a hollow truncated cone on the inner shell 
surface of which bar-shaped knives are arranged at predetermined angles 
with respect to the conical shell generating lines. 
In known embodiments of such Jordan refiner equipment, the knives are 
arranged in the rotating as well as the stationary part over the entire 
grinding surface, i.e. from the inlet to the outlet, formed of the same 
material, and, at least substantially, with the same arrangement. 
From U.S. Pat. No. 2,776,800, a disk refiner comprising an additional 
suction chamber and air vanes became known in which several grinding zones 
are provided, although the knives in the pre-grinding zone are not 
arranged at an angle to the radia and the knives in the further zones are 
not arranged consecutively at an angle to the radia, but at various 
positive and negative angles to the radia. 
U.S. Pat. No. 2,694,344 shows an extremely steep Jordan refiner comprising 
an inlet pre-grinding zone and a main grinding zone. In the inlet 
pre-grinding zone bar-shaped knives are welded or cast in place, namely 
parallel to the conical shell generating lines or at an angle to these in 
the stationary part, and with a bend at an angle to the conical shell 
generating lines as well as parallel to these in the rotating part. In the 
main grinding zone, the knives are arranged in a fish-bone like manner 
with the resulting longitudinal axes of the knives approximately parallel 
to the conical shell generating lines in the stationary part, and are 
inserted parallel to the conical shell generating lines in the rotating 
part. 
The paper pulp in the form of a fiber suspension of, for example, 5% by 
weight fibers dissolved in 95% by weight water is fed into the refiner 
equipment by means of a pump and is processed between the knife edges and 
the knife surfaces. In the inlet region of the equipment, the knives must 
be robust and arranged with a relatively wide distance therebetween. The 
danger of clogging of the equipment can only be safely prevented with such 
an open inlet. 
However, the wide spaces between the knives result in that the cutting edge 
length per second of the equipment achieves low values, whereby the 
attainable grinding effect is reduced in an undesirable manner. In 
previous embodiments of cone-shaped equipment, the parameters required for 
this inlet zone substantially determine the design of the entire remaining 
grinding surface. 
It is an object of the invention to provide grinding equipment of the type 
initially described, in particular with regard to the knife arrangement of 
the refiner, which is substantially independent of the inlet parameters. 
This object is solved in accordance with the invention in that a 
pregrinding zone is arranged upstream of one or more fine grinding zones 
whose configuration or arrangement are adapted to the respective state and 
desired development of the fibers in the grinding stock flowing through 
the grinding equipment, 
that a pre-grinding zone is arranged upstream of one or more fine grinding 
zones whose configuration and arrangement are adapted to the respective 
state and desired development of the fibers of the grinding stock flowing 
through the grinding equipment, 
that the bar-shaped knives in the respective zones extend linearly in a 
planar layout, 
and that at least in the stationary part, the average angles of the knives 
to the conical shell lines in the pre-grinding zone amount to at least 
approximately 10% and in the fine grinding zone to at least approximately 
20%. 
With this, the transferal of the grinding energy to the fibers can be 
controlled exactly by means of practically unlimited possibilities of 
variation of the configurations. 
The fine grinding zones differ considerably from the pre-grinding zone, 
namely with regard to the geometry--width of the knives, width and 
thickness of the channels between the knives, knife angles with respect to 
the conical shell generating lines--and also with regard to the knife 
materials used. 
The considerably finer knife structure in the fine grinding zone in 
comparison to the pre-grinding zone leads on the one hand to a relatively 
gentle treatment of the grinding stock in the fine grinding zone and on 
the other hand to a high cutting edge length per second, on account of 
which the grinding performance increases considerably. 
Advantageously, the stationary part has an inner, conical ring-shaped 
pre-grinding zone and one or more downstream find grinding zones in which 
the configuration and arrangement of the bar-shaped knives in the 
pre-grinding zone and the bar-shaped knives or corresponding edge-shaped 
formations in the fine grinding zone substantially differ from one 
another. 
The configuration and arrangement of the bar-shaped knives substantially 
depends on the material to be ground. Advantageously, the surface 
component of the bar-shaped knives of the stationary part in the 
pre-grinding zone amounts to at most 25 to 30% and in the fine grinding 
zone to approximately 50%, the depth of the channels between the 
bar-shaped knives in the pre-grinding zone usefully being substantially 
greater than the depth of the channels between the bar-shaped knives in 
the fine grinding zone, these for example, amounting to approximately 20 
mm in the pre-grinding zone and approximately 12 mm in the fine grinding 
zone. In the stationary part, the average angle of the knives with respect 
to the conical shell generating lines in the pre-grinding zone 
advantageously amounts to approximately 12.degree. and in the fine 
grinding zone to approximately 30.degree.. 
Usefully, the stationary part is formed as a casting with welded on steel 
knives in the pre-grinding zone and inserted hard grinding segments in the 
fine grinding zone. The pre-grinding zone is provided with relatively soft 
and cheap knives, the fine grinding zone on the other hand having 
relatively hard, high-quality knives. 
Advantageously, the rotating part has a continuous grinding zone. 
The surface component of the bar-shaped knives of the rotating part in the 
grinding zone amounts to approximately 40%, the depth of the channels 
between the bar-shaped knives of the rotating part being approximately 20 
mm. 
Advantageously, the average knife angle of the knives of the rotating part 
with respect to the conical shell generating lines in the region of the 
pre-grinding zone of the stationary part amounts to approximately 
8.degree., and in the region of the fine grinding zone of the stationary 
part to approximately 10.degree.. 
Thus, with the appropriate knife angle as revealed above of the knives of 
the stationary part of the grinding equipment in the pre-grinding zone, an 
average cutting angle between the knives of the stationary and the 
rotating part of approximately 20.degree. results and of approximately 
40.degree. in the fine grinding zone results. The smaller cutting angle 
causes more cutting, the greater cutting angle more friction in the 
grinding stock. 
The rotating part is also usefully formed with welded-on steel knives. 
A further development of the invention consists in that the rotating part 
has an inner, conical ring-shaped pre-grinding zone and one or more fine 
grinding zones arranged downstream in which the configuration and the 
arrangement of the knives in the pre-grinding zone and the bar-shaped 
knives or corresponding edge-shaped formations in the fine grinding zone 
differ from one another substantially. 
With such a configuration, a further increase in the grinding performance 
can be achieved. 
The configuration and arrangement of the bar-shaped knives of the rotating 
part in the pre-grinding zone corresponds usefully to that of a rotating 
part with a continuous grinding zone as previously described. 
Advantageously, the rotating part comprising the pre-grinding zone and the 
fine grinding zone is formed as a casting, with steel knives welded on in 
the pre-grinding zone and inserted, hard grinding segments in the fine 
grinding zone. 
Generally, the average angle between the knives of the stationary and 
rotating parts usefully amounts to approximately 20.degree. in the 
pre-grinding zone and approximately 40.degree. in the fine grinding zone. 
The conical opening angle preferably amounts to approximately 60.degree..

The inventive grinding equipment of a Jordan refiner consists of a 
stationary part 1 formed as a hollow truncated cone and a driven, rotating 
part 2 formed as a truncated cone arranged within this, as depicted in the 
drawings. 
The stationary part shown schematically in FIG. 1 and 2 has an inner 
conical, ring-shaped pre-grinding zone 3 and an outer conical, ring-shaped 
fine grinding zone 4. 
Bar-shaped knives 5 are provided in the pre-grinding zone 3 in conical ring 
segments arranged parallel to one another. The knives 5 are preferably 
steel knives and welded onto a casting 6. The surface component or area of 
the bar-shaped knives in the pre-grinding zone 3 amounts to at most 25 to 
30%, so that 70 to 75% of the surface remains for the open areas between 
the knives 5. One knife 5 per conical ring segment is led entirely to the 
inside. 
The depth of the channels between the bar-shaped knives 5 in the 
pre-grinding zone 3 preferably amounts to approximately 20 mm. The average 
knife angle of the knives 5 with respect to the conical shell generating 
lines amounts to approximately 12.degree. in the pre-grinding zone 3. 
Equally, the fine grinding zone 4 joining with the pre-grinding zone 3 of 
the stationary part 1 has bar-shaped knives 7 arranged parallel to one 
another. These knives 7 are preferably formed on inserted hard, 
high-quality grinding segments in the fine grinding zone 4. The surface 
component or area of the knives 7 in the fine grinding zone 4 amounts to 
approximately 50%. 
The depth of the channels between the bar-shaped knives 7 of the fine 
grinding zone 4 amounts to approximately 12 mm. The average knife angle of 
the knives 7 with respect to the conical shell generating lines amounts to 
approximately 30.degree. in the fine grinding zone 4. 
The relatively small knife angle in the pre-grinding zone 3 results in the 
material being cut more at this point and lumps being knocked open. The 
relatively larger knife angle in the fine grinding zone 4 results in the 
grinding stock being rubbed more and treated more gently. The largest 
applied pressure in the rotating part 2 inserted in the stationary part 1 
arises in the region of the relatively gentle pre-grinding zone 3. Behind 
the pre-grinding zone 3 and the fine grinding zone 4, one or more 
additional fine grinding zones with a further, different configuration and 
arrangement of the appropriate bar-shaped knives not shown can also be 
provided. 
In FIGS. 3 and 4, a first exemplified embodiment of the rotating part 2 of 
the inventive grinding equipment is schematically depicted. The rotating 
part 2 has a single continuous grinding zone 8. 
Bar-shaped knives 9 arranged parallel to one another on conical ring 
segments are provided in the grinding zone 8. These knives 9 are 
preferably formed as steel knives welded onto a casting 10. The surface 
component or area of the bar-shaped knives 9 in the grinding zone 8 of the 
rotating part 2 amounts to approximately 40% so that an open area of 
approximately 60% remains. 
The depth of the channels between the bar-shaped knives 9 of the rotating 
part 2 preferably amounts to approximately 20 mm. The average knife angle 
of the knives 9 of the rotating part 2 with respect to the conical shell 
generating lines amounts to approximately 8.degree. in the region of the 
pre-grinding zone 3 of the stationary part and to approximately 10.degree. 
in the region of the fine grinding zone 4 of the stationary part. The 
reason for the average knife angle being somewhat larger in the fine 
grinding zone 4 of the stationary part 1 lies in that several additional 
small knives 9 are provided on the outside. 
In this arrangement of the grinding zone 8 of the rotating part 2, an 
average angle of approximately 20.degree. results between the knives 5 of 
the stationary part 1 in the pre-grinding zone 3 and the knives 9 of the 
rotating part 2, while the average angle between the knives 7 of the 
stationary part 1 in the fine grinding zone 4 and the knives 9 of the 
rotating part 2 amounts to approximately 40.degree.. 
A further exemplified embodiment of the rotating part 2 of the inventive 
grinding equipment is schematically depicted in FIGS. 5 and 6. Here, the 
truncated cone-shaped rotating part 2 has an inner conical, ring-shaped 
pre-grinding zone 11 and an outer conical, ring-shaped fine grinding zone 
12 in which the configuration and the arrangement of bar-shaped knives 13 
in the pre-grinding zone 11 and bar-shaped knives 14 in the fine grinding 
zone 12 differ from one another. The knives 13 of the pre-grinding zone 11 
of the rotating part 2 are again arranged parallel to one another in 
conical ring segments. Preferably, the knives 13 of the pre-grinding zone 
11 of the rotating part 2 are formed as steel knives welded onto a casting 
15. 
The configuration and arrangement of the bar-shaped knives 13 in the 
pre-grinding zone 11 of the rotating part 2 corresponds to the 
configuration and arrangement of the bar-shaped knives 9 in the single 
grinding zone 8 of the rotating part 2 as described in connection with 
FIGS. 3 and 4. 
The bar-shaped knives 14 of the fine grinding zone 12 of the rotating part 
2 are preferably also formed here on hardened grinding segments inserted 
in the fine grinding zone 12 of the rotating part 2. 
The conical opening angle of the stationary part 1 and the rotating part 2 
amounts to approximately 60.degree..