US2532415A

US2532415A - Rotary screening drum

Info

Publication number: US2532415A
Application number: US663393A
Authority: US
Inventors: Lindblad Karl Roland
Original assignee: Svenska Cellulosa AB
Current assignee: Svenska Cellulosa AB
Priority date: 1945-04-25
Filing date: 1946-04-19
Publication date: 1950-12-05
Anticipated expiration: 1967-12-05

Description

Dec. 5, '1950 K. R. LINDBLAD ROTARY SCREENING DRUM 2 Sheets-Sheet 1 Filed April 19, 1946 Dec. 5, 1950 K. R. LINDBLAD ROTARY SCREENING DRUM 2 Sheets-Sheet 2 Filed April 19, 1946 Patented Dec. 5, 1950 ROTARY SCREENING DRUM Karl Roland Lindblad, Sundsbruk, Sweden, as-

signor to Svenska Cellulosa Aktiebolaget, Stockholm, Sweden, a joint-stock company of Sweden Application April 19, 1946, Serial No. 663,393 In Sweden April 25, 1945 4 Claims. (Cl. 92-36) The present invention relates to a screening device for screening suspensions, particularly fibrous suspensions, in the form of a rotary cylindric vibratory screening drum which is elastically suspended and consists of a cylindric shell and a central pipe carrying the same, a

drive shaft provided with eccentric weights being rotatably mounted in said pipe.

Rapid eccentric movements (preferably about 1200 a minute) are imparted to the screening drum by the eccentric weights located on the drive shafts. The object of the invention is to provide a screening device with vibratory parts of small weight in order that bearings and other vibratory parts shall be subjected to as small stresses as possible and to obtain a construction which is so stable that natural oscillations and thus the risk of ruptures in the material are prevented.

The screening drum according to the invention may be arranged in a trough to which the suspension to be screened is delivered and the material that has passed through the shell of the drum may leave the drum through openings in the end walls of the drum. Spraying pipes may be inserted through the end walls for spraying away the coarse material collecting on the outer surface of the shell to a conveying channel situated above the drum. The drum with the central pipe may be mounted in journal bearings which are carried by compression springs. The central pipe of the drum preferably arranged to carry the shell of the drum by the intermediary of a staying device, connecting the middle portion of the shell with the central pipe. Said staying device may consist of two wall surfaces issuing from a point on the middle portion of the shell and converging conically towards each end wall.

An embodiment of the screening device according to the invention is illustrated in the accompanying drawings.

Fig. 1 is a longitudinal section of a screening device according to the invention. Fig. 2 is a cross section on line II-II in Fig. 1.

By reference to the drawings the reference character I designates a trough, into which the fibrous suspension flows through a channel 2 and is screened through the perforated shell 3 of the screening drum immersed in the fibrous suspension. The screened fibrous suspension flows out through openings in the end walls of the screening drum and is led off through the pipes 4. The coarse fibres which do not pass through the perforated shell 3, accompanying the drum and are by means of water from the spraying pipes 5 which are inserted through the end openings and do not participate in the rotation of the drum, flushed from the drum shell off to a conveying channel located above the drum. The screen shell is carried by the pipe I within which the shaft 9 which is provided with eccentric weights 8, is mounted. On the pipe 1 there are two hoppershaped walls In facing one another and carrying the stay pipes I I on which the perforated shell 3 is fixed. The end walls l2 are provided with outlet openings and are fixed to the ends of said stay pipes. Packing rings l3 are provided between the screening drum and the trough I. The screening drum is carried by the bearings I l which rest on the compression springs I5. The screening drum may be rotated by the gear l6 which is driven by the motor I! via the flexible coupling l8. The shaft 9 with the eccentric weights is connected to a motor l9 by means of the flexible coupling 20.

When the motors l1 and [9 are set in rotation the screening drum, due to the eccentric weights 8, begins to vibrate rapidly, being at the same time slowly rotated by the motor IT. The rapid vibrations imparted to the screening drum subject the material of the drum to heavy stresses due to the resistance of the liquid and the weight of the vibratory parts. Therefore, the above described device in which the screening shell 3 is supported in the middle by means of the walls "I ensures a stable and durable construction.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Apparatus for screening liquid suspensions such as a fibrous suspension comprising a trough for receiving the suspension, a screening drum in said trough adapted to be at least partly immersed in the suspension and being provided with an outlet for screened material in at least one end wall thereof, a hollow shaft arranged coaxially with and extending through and supporting said drum, elastic journals at opposite sides of said drum mounting said shaft, said journals being axially aligned with the common axis of said shaft and drum means for rotating said shaft, a second shaft arranged coaxially within said hollow shaft, said second shaft being loaded eccentrically with respect to its axis, bearing means carried by said hollow shaft for journalling said eccentrically loaded shaft, and means for rotating the latter to thereby impart vibratory motion to said hollow shaft and drum through said bearing means.

2. Apparatus for screening liquid suspensions 3 as defined in claim 1 wherein said hollow shaft is provided with substantially radially extending supporting means, said supporting means being connected to said drum at the middle portion of the latter and constituting the sole support be tween said shaft and drum.

3. Apparatus for screening liquid suspensions as defined in claim 2 wherein said supporting means is constituted by a pair of wall surfaces issuing jointly from a line at the mid-plane of said drum, each of which surfaces converges conically toward said end walls.

4. Apparatus for screening liquid suspensions such as a fibrous suspension comprising a trough for receiving the suspension, a screening drum in said trough adapted to be at least partly immersed in the suspension and being provided with an outlet for screened material in at least one end wall thereof, hollow shaft means arranged coaxially with and supporting said drum, elastic journals at opposite sides of said drum mounting said shaft means, said journals being axially aligned with the common axis of said shaft means and drum, a second shaft arranged coaxially within said hollow shaft means, said second shaft being loaded eccentrically with respect to its axis, bearing means within said hollow shaft means journalling said second shaft, and means for rotating said second shaft thereby to impart vibratory motion to said hollow shaft means and drum through said bearing means.

KARL ROLAND LINDBLAD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS