US2597503A - Shaking screen - Google Patents

Description

May 20, 1952 J. A. LARSSON 2,597,503

SHAKING SCREEN Filed Feb. 10, 1948 2 SHEETS-SHEET 1 May 20, 1952 J. L. A. LARssoN 2,597,503

SHAKING SCREEN Filed Feb. 10, 1948 2 SHEETS-SHEET z Patented May 20, 1952 OFFICE SHAKING SCREEN John Lars Arvid Larsson, Nockeby, near Stockholm, Sweden Application February 10, 1948, Serial No. 7,355 I In Sweden August 5, 1944 Section 1, Public Law 690, August 8, 194i: Patent expires August 5, 1964 2 Claims.

The present invention relates to shaking screens, particularly to such screens of the kind in which the screen at both ends is connected to eccentric driving means rotating synchronously and in phase and imparting a vibratory movement to the screen during which the entire screen surface remains substantially parallel to itself. 1

In such screens one hashitherto constructed the screen with a closed rectangular frame to which the screen member proper, such as a wire gauze member is clamped.

In investigations as made I have found that considerable advantages may be obtained by departing from the customary construction comprising a closed supporting frame for such screens and instead mounting the screen on two beams freely mounted in which eccentric driving shafts with associated counterweights are journallled. Hereby not only a reduction .of the weight of the entire screen is obtained in that the longitudinal parts of the supporting frame previously used are eliminated but in addition also the operation becomes safer in that the hitherto most common cause for interruptions of operation, namely frame breakage is entirely eliminated. If the beams used according to invention with their associated eccentric shafts and counterweights are subjected to breakage then these beams and their associated shafts and counterweights may be removed individually as a unit and be replaced by a corresponding new unit. Another advantage of the invention is that a perfect balancing of the screen can be obtained by using the separate supporting beams rigidly connected to the screen.

The invention relates also to some improvements in the supporting beams in question particularly set forth hereinbelow.

On the accompanying drawings there are illustrated some embodiments of the invention.

Fig. 1 shows a side elevation of the present shaking screen, partly in section along line I-I in Fig. 2.

Fig. 2 shows a section along line II-II in Fig. 1.

Fig. 3 shows a top plane View of the screen.

Fig. 4 shows a section along line IV--IV in Fig. 3.

Fig. 5 shows a detail for illustrating the mode of journalling the eccentric shafts in the box or drum shaped supporting beams.

Fig. 6 shows a chain tensioner to prevent phase shifting between the two eccentric shafts.

The screen is carried by a base I by means of longitudinal beams 2 and plummer blocks 8 in distance) by means of a box beam 1 adjacent each end of the screen 6.

The shafts 4 may be journalled in these box beams as shown in Fig. 5 by ball bearings 8 at each end of the box beam 1 which ball bearings are mounted in housings 9.

The box beams 1 proper may be constructed as shown in section in Fig. 4 in which each box beam 1 comprises a body of four longitudinal angle irons l0 surrounded by sheet metal ll.

Fig. 4 shows also the arrangement of the counterweights I2 on the shafts 4 within the box beams 'l.

The bars 6 rest at top of the two beams l and are rigidly connected thereto, preferably by bolt connections, not shown, whereby 'a complete balancing of the entire screen by suitable proportioning and mounting of the counterweights I2 is enabled.

As may be seen from Fig. 3 the two eccentric shafts 4-5 are connected to each other by a chain l4 passing over chain wheels l3 but any other device which secures that the two shafts 4-5 rotate synchronously and in phase may obviously be used within the scope of the invention.

As may be seen from the foregoing each box beam 1 with its associated shaft 4-5 and counterweight l2 forms an assembly or unit. Should for some reason during the operation of the screen such a unit (4-5--l-l 2) fail then it may be dcmounted as a unit for repair and be substituted by a corresponding spare unit. Similarly a bar 6, if broken, may very easily be dcmounted by loosening the bolt connections in question. The absence of a continuous rectangular supporting frame for the bars l6 thus eliminates effectivel the serious drawbacks in breakage of the frame in screens hitherto used. Moreover, the bars 6 in addition to filling their function as screen members between which in operation the finer parts of the material to be screened leave the screen downwards whereas the coarse parts leave the screen atthe bottom end thereof, also fill a function as connection members between the box beams I.

In screening finer material one can on the bars 6 attach a piece of wire gauze or perforated sheet metal which then serves as the screen member proper.

upper box beam 1 in Fig. 3, if the chain It is. subjected to rupture and then only the shaft 4-5 driven by motor I is rotated, due to the lateral pulses of vibration, suitable means are provided for securing a certain flexibility at this box beam. According to Fig. 1 this canbe. obtained by uniting each of the left-hand plummer blocks, 3 in this. figure to. the supporting beams. 2 by two, brackets i8 and I9.- one of which is, secured to. the bottom side of the respective.

plummer block 3 while the other bracket is secured to the top face of the respective support-v ing beam 2, a pivot pin 20 extending through said two brackets.

In interconnecting the eccentric driving shafts by a chain a special chain tensioning de.-. vice. is preferably used according to the. inven-. tion as illustrated in Fig. 6. Said device. con: sists of two smaller sprocket wheels 22 mounted for rotation at each end of the lever 23 which intermediate itsends is united to a lever 24 piv oted at 26. and. operated by a spring 25 or some other loading device. The chain i4 is initially so adjusted. that its upper and lower runs com prise an equal number of links and parts thereof whereby the two shafts 4-5 will be rotated exactly inphase. If, however, the chain. 14 slack-v ensduring operation the driving runs (the lower one in. Fig. 6). tends to. become shorter than the. upper runs. whereby the. chain 14- will. operate by jerks. tensioner 22-45 shown which automatically secures. that the lower and upper runs of the chain also in case the chain l4 slackens automatically are maintained at. equal length.

What I claim is:

1 In. shakingscreens, a fixed supporting structure, bearings supported on said structure spaced in apart relation, rotatable transverse shatts supported and mounted by said bearings only,

This is avoided by the chain at their opposite ends, said shafts being provided with eccentric weight means, means interconnecting said shafts to control their rotation to cause the eccentric weight means to rotate synchronously and in phase, box beams encasing said shafts and eccentric. weight means and being connected to said shafts by means of bearings located inwardly from the ends of the shafts so as to form self contained units, a plurality ofindividual screening bars, and means for detachably connecting said bars individually to eachbox beam.

2-. In shaking screens, a fixed supporting structure, bearings supported on said structure spaced ,7 in apart relation, rotatable transverse shafts supported and mounted by said bearings only at their opposite ends, said shafts being provided with eccentric weight means, means interconnecting said shafts to control their rotation to cause the eccentric weight means to rotate synchronously. and in phase, bogg beams encasing ai af s. an eccentric w ht mean an; e.- ing connected to, saidshafts by means of bear;-

ing s located inwardlyfrom the endsof the shafts, so as. to fq m s l ontained u it a, s immy of individual screening bars, means; for detach b on g. ai a nd dua y to .4 1 box beam and a screening member attached; so, as to overlie said bars.

QHN was A Y Q. masses REFERENCES CITED.

The following referencesv are. of record in the file of this. patent:

UNITED STATES PATENTS Number Name Date 976,115 Bard Nov. 15,1910 1,605,962. Lovejoy Nov. 9,1926 1,787,852 Behnke et 1. Jan. 6-, 1931 2,321,675 Hauge June 15,: 1943 2,374,663. Carrier May 1, 1945 2,386,579 Wheeler Oct. 9, 1945 23 .9 Kranz FOREIGN; PATENTS Number Country Date 26,065 Great Britain Nov. 25, 1901 280,412 Great Britain Nov. 17, 1927 285,638 Great Britain Feb. 23, 1928 366,886 Great Britain Feb, 11, 1932 31, 33, Sweden Oct. 9, 1934 680,827 Germany Sept. 1 1, 1939

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