Presses – With drain means for expressed liquid – Drainage through or along pressure surface
Patent
1995-01-04
1996-05-14
Gerrity, Stephen F.
Presses
With drain means for expressed liquid
Drainage through or along pressure surface
100117, 100127, 100148, B30B 918
Patent
active
055157769
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a worm press for separating liquids from solids-liquid mixtures, in particular fibrous suspensions, more particularly under pressure, including a worm rotating inside a jacket comprising liquid passages, wherein the shaft of the worm which is preferably of hollow construction, comprises in the axial conveying direction following onto the region which comprises at least one worm rib, a smooth terminal region in which the worm shaft is designed as a jacket shaft, provided with a cavity between a shaft jacket and a preferably hollow shaft core, and that this shaft jacket comprises liquid passages, for example bores, leading into the aforementioned cavity, this cavity being in communication with at least one liquid drainage means.
A worm press of the aforesaid type is already known from U.S. Pat. No. 3,394,649 (Kemper et al). This worm press serves for the dewatering of sludges or cellulose pulp suspensions and comprises a hollow worm shaft having apertures at the end of the pressure zone. Through these bores still further liquid can be drained into the hollow shaft, this liquid draining inside the shaft in a direction opposite to the conveyance direction. However, such a worm press suffers from the disadvantage that only small amounts of liquid can be drained through the bores into the cavity of the shaft. Furthermore, these shafts, when employed for dewatering fibrous suspensions are very susceptible to being blocked by fibres.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a worm press which is of comparatively simple construction, can be operated at higher (squeezing) pressure which moreover permits a drainage of larger amounts of liquid into the cavity of the shaft and where appropriate also reduces the tendency towards blockages by fibres.
This is attained in accordance with the invention in that the cavity in the terminal region of the worm shaft is formed between a shaft core tapering in the axial conveyance direction and which more particularly is hollow and the shaft jacket fitted on the former and provided with liquid passages. Due to this tapering terminal region of the worm shaft a cross-section which is as large as possible is provided for the drainage of the liquid. Due to the tapering of the terminal region of the shaft, the liquid discharge in the axial conveyance direction is made possible whereby the liquid pathways can be kept short.
In accordance with a preferred embodiment of the invention, a conveyed matter retention means, preferably adapted to be regulated is provided in the terminal region of the worm shaft for the purpose of building up pressure in the conveyed material present between the worm and the worm press jacket surrounding it, outside of the shaft jacket, in particular a pivotable retention flap. Due to the pressure build-up, respectively the additional conveyed matter retention means installed in a stationary manner, the material at the end of the worm press is dammed up, thereby being subjected to an increased pressure in that region, and liquid still present in the material being pressed out and discharged through liquid passages in the jacket of the worm shaft into a cavity.
An advantageous embodiment of the invention is characterised in that the shaft core in the terminal region of the worm shaft conically tapers in the axial conveyance direction. In that manner the manufacture and the liquid discharge are facilitated.
According to an advantageous embodiment of the invention the liquid passages in the terminal region of the shaft jacket of the worm shaft are provided in the region of the conveyed material retention means. In that manner the liquid discharge can be readily controlled.
Preferably, according to the invention, the liquid passages in the terminal region of the shaft jacket of the worm shaft have a cross-section which increases towards the cavity between the shaft jacket and the shaft core, i.e. in the direction of discharge of the liquid. The liquid discharge
REFERENCES:
patent: 1152857 (1915-09-01), Stehlin
patent: 1781250 (1930-11-01), Schwarz
patent: 1835789 (1931-12-01), Lang
patent: 1851191 (1932-03-01), Lang
patent: 3394649 (1968-07-01), Kemper et al.
patent: 3982483 (1976-09-01), Bird et al.
patent: 4915830 (1990-04-01), Mackay et al.
Heindler Gerhard
Mraz Peter
Paier Gerhard
Scheucher Peter
Schinninger Walter
Andritz-Patentverwaltungs-Gesellschaft m.b.H.
Gerrity Stephen F.
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