Solid material comminution or disintegration – Apparatus – With automatic control
Patent
1979-12-28
1982-07-13
Rosenbaum, Mark
Solid material comminution or disintegration
Apparatus
With automatic control
241251, 2412592, 2412601, 241261, 425204, B02C 1816
Patent
active
043390846
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to pulp refining apparatus of the type in which two intermeshing rotary screws are driven synchronously within a housing provided with a material inlet and a material outlet, the treated material, in the first place cellulosic material such as pulp, passing from the inlet to the outlet while being compressively treated at a high dry-matter concentration of at least 12.5% and preferably at least 25% between the intermeshing screw threads.
BACKGROUND
Apparatuses of a similar kind form the object of British Pat. No. 1 229 894 and Swedish Pat. No. 314 288. While in the refiner construction according to British Pat. No. 1 229 894 the discharge outlet for the treated material is positioned around the ends of the screw shafts remote from the inlet, the construction according to Swedish Pat. No. 314 288 provides for adjustability of the discharge opening between a stationary outlet end-wall of the housing and a longitudinally shiftable housing portion. The present invention is in the first place but not exclusively intended to be used in connection with constructions in which the outlet is not associated with the end-wall of the housing remote from the inlet but is disposed laterally in the stationary housing.
SUMMARY OF THE INVENTION
The known type of such an intermeshing screw refiner with a stationary housing has been widely and successfully used in practice. Still it has some disadvantages inherent in its construction.
(1) Due to the fact that the two screw shafts are mounted in firm mutual positions without the possibility of a resilient displacement of the screws away from each other expensive break-downs are caused when for example over-sized screws and nuts happen to be introduced into the interspace between intermeshing screw threads together with the treated material.
If lumps of particularly high dry-matter content are introduced between the screw threads, momentous radial forces acting on the screw shafts in some cases have been the cause of breaking of such shafts. The unyielding construction also restricts the use of the machine to a more limited concentration range of the treated material.
As there is no adjustment possibility in case the screws in the initial assemblage of the machine touch each other, the requirements as far as manufacturing tolerances are concerned are unduly high.
(2) Another negative aspect of the conventional unyielding screw construction resides in the fact that the compression in the treating gap cannot be directly controlled. It is not either possible to adjust the width of the refining gap between the intermeshing screws. Such an adjustment possibility, however, is particularly desirable in order to permit such positive control of the gap width as may be required to compensate for wear of the screws during extended use.
The unyielding support of the shafts also renders the machine unsuitable for "in-line"-use.
(3) When the screw thread portions of the screws are to be exchanged (with the shafts proper left in the machine) simultaneous axial removal and insertion of both thread portions is required due to the intermesh between the screws. In addition, exchange of the screw-thread portions requires removal of parts of the housing and dismounting of the inlet connections.
All these disadvantages are avoided by the present invention which resides in providing a pulp refining apparatus of the type defined above with a construction as defined in the attached claims, the salient feature of which is an arrangement permitting pivotal swinging movement of at least one of the two intermeshing screws in the common central axis plane of both screws.
1. Due to the fact that the shafts can be separated from each other when the pressure between the screws increases, destruction of the machine is avoided when hard foreign bodies such as screws and nuts accidentally are introduced into the treating gap between the screws.
Also such lumps of pulp which during an interruption of the operation of the machine have been left within the
REFERENCES:
patent: 2713460 (1955-07-01), Atkinson
patent: 4154408 (1979-05-01), Boling, Jr.
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