US2860783A

US2860783A - Vibrating apparatus for handling loose material

Info

Publication number: US2860783A
Application number: US579836A
Authority: US
Inventors: Louis W Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-04-23
Filing date: 1956-04-23
Publication date: 1958-11-18
Anticipated expiration: 1975-11-18

Description

Nov. 18, 1958 L. w. JOHNSON VIBRATING APPARATUS FOR HANDLING LOOSE MATERIAL 2 Sheets-Sheet 1 Filed April 25, 1956 INVENTQR. LOUIS W. JOHNSON A T TOIPNE Y5 Nov. 18, 1958 L. w. JOHNSON I VIBRATING APPARATUS FOR HANDLING LOOSE MATERIAL Filed Anril 25, 1956 2 Sheds-Sheet 2 mm T mm mm J w s m 0 LY B O G 5 .l W F w \s EW v\ W K 2m A TTORNEYS United States Patent VIBRATING APPARATUS FOR HANDLING LOOSE MATERIAL Louis W. Johnson, Eugene, Oreg.

Application April 23, 1956, Serial No. 579,836

8 Claims. (Cl. 209-3665) This invention relates to vibrating apparatus for handling loose articles andparticularly to screening apparatus especially adapted for use in screening crushed rock and the like.

Prior screening apparatus for use with crushed rock have been essentially of two types, the two bearing type and the four bearing type. The two bearing type includes a screening box which is resiliently mounted or suspended, usually on a base frame, and further includes a transverse shaft which is journaled on the box in two spaced bearings and carries at each end an eccentric weight. The shaft is rotated to cause the screening box to vibrate. The four bearing apparatus isessentially similar, except that the shaft is also journaled in an additional set of bearings on the base frame, the two sets of bearings being eccentric to each other.

Both types of apparatus have operational disadvantages, including the fact that the weights, being of constant mass, cannot compensate for variations in the effective mass of the box, which is caused by different loadings of the box and also other factors, such as the adherence of sticky material to the screens. Thus, load variations cause variations in the amplitude of vibration of a box, resulting in inadequate screening.

In four bearing screening apparatus, the weights are arranged in counterbalancing relation with respect to the box, so that under ideal conditions there is little vibration of the base frame. However, ideal conditions rarely exist because of the different loadings of the box and other factors, and hence there is considerable tendency for the'four bearing apparatus operating under ordinary conditions to vibrate the base frame and thus result in severe wear on the bearings connecting the box to the base frame.

With two bearing screening apparatus, the box is not mounted on the frame by bearings and hence no restraints are placed on vibrating movement of the box.

Thus the box is subjected to objectionable violent shaking andvibration during starting and stopping. Also, the heavy weights hang downwardly when at rest and it requires excessive power to start the two bearing apparatus because of the necessity of lifting the weights up and over center without the counterbalancing aid of the box as is the case in the four bearing apparatus. .This has required the use of larger motors for two bearing machines than for four bearing machines.

It is a main object of the present invention to pro vide a screening apparatus having a vibration producing means so constructed that it automatically adjusts to the mass of the screening box, within the limits of the apparatus, thus to obtain uniform amplitude of vibration despite variations in the effective mass of the screening X box. t

It is a further object of the present invention to provide a screening apparatus in which the vibrating producing means 'is in a balanced condition 'when starting and stopping the machine so thatless vibration is experienced I Patented Nov. 18, 1958 ice at such time and also less horespower is required to 0p erate the apparatus at such times.

. The apparatus of the present invention is characterized by including a screening. box having a transverse shaft extending therethrough and journaled thereon. On each end of the shaft a weight means is rotatably mounted about an axis offset or eccentric to that portion of the shaft on which the box is journaled. Each weight means includes at least two weights which are so freely journaled for rotary movement as to be operable automatically to assume positions to obtain uniform amplitude of vibration.

Various other objects of the present invention will be apparent from the following description taken in con nection with accompanying drawings wherein:

Fig. l is a side View of a two bearing machine embodying the concepts of the present invention;

Fig. 2 is an end view looking in the direction of the arrows 2.2 in Fig. 1;

Fig. 3 is an enlarged sectional view taken along line 3-3 of Fig. 2, showing more fully details of construction;

Fig. 4 is a plan view taken in the direction of the arrows 4.4 of Fig. 3;

Fig. 5 is an enlarged sectional view of a weight means taken along line 55 of Fig. 1;

Fig. 6 is a vertical sectional view taken along line 66 of Fig. 5, showing the weights in their rest positions;

Fig. 7 is a view similar to Fig. 6 but showing the weights in operative positions;

Fig. 8 is a schematic view illustrating the mode of operation of a weight;

Fig. 9 is a side view of a four bearing machine;

Fig. 10 is an enlarged sectional view taken along line 1010 of Fig. 9, showing the construction of a weight means, and

Fig. 11 is a sectional view taken along line 1111 of Fig. 10. I

Referring to the accompanying drawings, Figs, 1 through 6 show a two bearing machine embodying the concepts of the present invention. The machine includes an open rectangular base frame 11 on which a screening box 13 is resiliently mounted. The right-hand end of the box, as the parts are disclosed in Fig. l, is its loading end and its left-hand end is its delivery end.

The manner of supporting the box is as follows. There are four similar mounts, each including a coiled com pressing spring 15 (Fig; 3) seated on a base member 17 and bearing against a head block clamp 19, in which the free ends of a cable 21 are secured. The lower por tion of the cable extends around and is secured. to a stub shaft 23 which is in turn secured to the side of the screening box 13. Each delivery end mount has the base mem-: ber 17 thereof fixed to the frame 11, whereas the base member of eachloading end mount is fixed. on a pillar 29 secured to the frame 11. Thus the loading endof the box is disposed at a higher elevation than the delivery end of the box. i

The screening box 13 is provided with one or more appropriate screens or courses 31, Fig. 1, which extends longitudinally of the box and from side to side thereof. Three screens are shown, the upper screen being the coarsest, theintermediate screen being somewhatfiner, and the lower screen being the finest. The bottom of the screeningbox is open so that material passing throughthe bottom screen drops into a pile or on a suitable conveyor beneath the box. Suitable conveyors may also be provided at the delivery end of the box to receive loose material which has been graded.

The screening box is equipped with a transverse shaft housing 33, Fig. 5, which is fixed to the sides of the box. Extending through the housing is a shaft 35, each end of which has a first reduced portion 37 and a second reduced portion 39. The shaft is mounted in the housing 33 by bearings 36 which fit on reduced portions 37, suitable bearing retainers 43 and seals 45 being provided for the bearings. Portions 39 are eccentrically disposed relative to portions 37 but concentrically disposed relative to the central portion of the shaft and also the extreme end portions of the shaft. The shaft is driven by means of a motor .47 which is mounted on the frame 11 and connected to the shaft by a flexible belt drive 49 which includes a pulley 50 fixed to an end of the shaft.

Fixed concentrically on each of the shaft portion-s 39 is aweight means including a hollow disc shaped casing51 which has a hub 53 keyed at 55 to the shaft portion 39.. A nut 56 retains each casing on the shaft 35.

,Within each casing 51 is a pair of fan shaped

weights

57 and 59, Fig. 6, which are of equal mass and are rotatably mounted by means of bearings 61 on the hub 53 of the casing. Each casing is provided with a pair of

stops

71 and 73 for its

weight

57, and 75 and 77 for its weight 59. Thus each weight may revolve freely an arcuate distance between the limits of the associated stops, but the stops maintain the weight generally in opposed relation and on opposite sides of a line through the taxes of

shaft portions

39 and 37 Pivotally mounted on the weight 59 of each casing is a pawl 81 which is adapted to engage ratchet teeth 83 formed on the hub portion of the associated weight 57. A biasing means, such as a preloaded spring 85, is mounted on the weight 59 and urges the pawl into engagement with the ratchet teeth. The biasing means are so constructed that before the machine is up to rated speed, centrifugal force Will cause the pawl to disengage from the ratchet teeth and thus provide for rotary movement of the weights relative to the casing. The casing may be filled or partially filled with a quantity of oil which serves as a lubricant and dampens movement of the weights relative to the casing.

The operation of the machine is as follows. Initially, the

weights

57 and 59 are locked in positions approximately 180 degrees from each other against the

stops

71 and 75 by the pawl 81, Fig. 6. In fact, the weights are arranged with their upper edges slightly closer together than their lower edges so that the center of gravity of said weights and easing coincides with the axis of shaft portions 37. This provides for absolute balance of the machine when starting. Thus the box 13 will remain stationary while the weight means are being rotated up to speed .and a low horsepower motor can turn over the weight means since they are in a balanced condition.

Just before the box gets up to rated speed, the pawls 81 are forced outwardly under the influence of centrifugal force to release the

weights

57 and 59 which automatically leave the

stops

71 and 75 and swing to positions similar to those in Fig. 7 to cause vibration of the box about the axis of shaft portions 39 as a center, for reasons presently to be explained. If the mass of the screens of the screening box increases because of the adherence of clay and the like, or for other reasons, the weights will move further toward one another to maintain a uniform amplitude of vibration. I

While the machine is being stopped, the weights will return to their Fig. 6 positions because the pawl will move back intoengagement with teeth 83 and allow relative movement of the weights, under the influence of gravity, onlyin a direction separating the weights from one another.

The theory of operation of the weights is as follows. Referring to Fig. 8, if weights A are mounted for rotation about an axis 'B and axis B is rotated in an orbit about axis C, the weights under the influence of centrifugal force will tend to move to positions where their centers of gnavity are aligned with the axes B and C, as shown in dotted .lines. If the axis C is located on a floating or resiliently mounted box, movement of the weights A from their rest positions toward the dotted line position will be accompanied by increased vibration of the box in an orbital movement and cause a shift in the center of motion from axis C to axis B as a center, at which time the mass of the weights multiplied by the distance between the centers of gravity of the weights and axis B equals the effective mass of the box multiplied by the distance between axes B and C. Under these conditions, there is no longer any centrifugal force urging continued movement of the Weights A toward their aligned positions, so that such movement ceases and leaves the weights at intermittent positions, for instance the dot-dash positions shown. In fact, centrifugal force-will maintain the weights at such intermittent positions.

It the effective mass of the box should increase, such as might be caused by the adherence of clay to the screens thereof, or for any other reason, the center of motion will shift slightly from axis B and thus the axis B will move through a small orbit. Thus centrifugal force will cause further movement of the weights A toward their aligned positions, thus automatically to compensate for the change in the effective mass of the box and thus maintain a uniform amplitude of vibration of the box.

The

weights

57 and 59 of the machine of Figs. 1 through 7 operate in the above described manner with axis By being the axis of shaft portions 39 and axis C being the axis of shaft portions 37. A requirement for obtaining the desired results is that the weights be heavy enough to cause the box to vibrate about the axis of shaft portions 37 at a time when the weights are disposed at intermediate positions between their inactive rest positions and their aligned conditions. If the weights did not meet this requirement, they would assume aligned positions during operation of the machine without causing the center of motion to move to the axis of shaft portions 39, and thus the weights could not counteract decreasingamplitude of vibration which would be caused by an increase in the effective mass of the box.

It is pointed out that since there is a pair of weights at each side of the machine, the machine will vibrate at a uniform amplitude even though one side of the machine is heavier than the other.

Fig. 9 shows a modified form of the invention incorporated in a four bearing type screening apparatus. This appanatus includes a base frame 91 and a screening box 93 similar to screening box 13. In this construction, the screening box is resiliently mounted on the base frame 91 in part by resilient mounts 95 in the same manner as box 13 is mounted by mounts 15 on frame 11, or in equivalent fashion to permit vibrating movement of the box. The box is also mounted on the frame 91 by means of a transverse shaft 97, having at each end a reduced shaft portion 98 mounted by a bearing 101, a housing 102, a rubber bushing 103 and a pillow block 104 on the frame 91. The central portion of the shaft is journaled on box 93 by .a pair of bearings 105, one of which is shown in Fig. 10. The shaft is driven by a motor and belt drive unit 106.

A weight means is rotatably mounted on a shaft portion 107 adjacent each end of the shaft and each of these weight means includes a pair of freely rotatable weights 111 and 113, Fig. 11, which are similar to

weights

57 and 59 of the previously described form of the invention.

Shaft portions

98 and 107 are concentric relative to one another but eccentric relative to the central portions of shaft 97. The weights are so located circumferentially of the shaft as to be disposed in positions to counterbalance the vibrating effect of the box on the frame 91.

A lock 115 extends through guides 117 on the casing and engages teeth 119 on the weights. The lock is spring loaded by springs 121 bearing against a base 123, the parts being constructed so that the lock will disengage just before the machine gets up to rated speed under the influence of centrifugal force and to re-engage just after the machine speed falls below rated speed. Thus, this maintains the weights at approximately their running positions when the machineis starting or stopping so that the box does not vibrate the frame 91. However, the weights may adjust to variations in the effective mass of the box when the machine is operating at rated speed.

Although the concepts of the invention have been shown as having been incorporated in a screening apparatus, they could also be incorporated in apparatus for handling other loose articles or material. Among the important advantages obtained by the present invention is prolonged bearing life because of the balanced operating conditions of the machines.

Having described the invention in what is considered to be the preferred embodiment thereof, it is desired that it be understood that the invention is not to be limited other than by the provisions of the following claims.

I claim: r

1. A screen vibrating apparatus for imparting constant amplitude of vibration to a screen member whose effective mass varies in accordance with loading and other conditions, comprising means mounting said member for vibrating movement, a pair of weightsmounted on said member for swinging movement about a first axis and for rotary movement about a second axis parallel to said first axis but offset therefrom so that swinging movement of said weights about said first axis changes the distance between the center of gravity of each weight and said second axis, means for rotating said weights about said second axis to cause said weights to move about said first axis toward positions at which said dis tance is a maximum, said weights having sufficient mass to cause said member to vibrate about said first axis before said weights reach such positions so that upon an increase in the effective mass of said member said weights will swing toward such positions to compensate for such increase and will swing away from such positions to compensate for a decrease in the effective mass of said member thus to maintain said member vibrating about said first axis to maintain a uniform amplitude of vibration.

2. A screen vibrating apparatus for imparting constant amplitude of vibration to a screen member whose effective mass varies in accordance with loading and other conditions, comprising means mounting said member for vibrating movement, weight means mounted on said member for turning movement about a first axis and for rotary movement about a second axis parallel to said first axis but ofiset therefrom so that turning movement of said weight means about said first axis changes the distance between the center of gravity of said weight means and said second axis, means for rotating said weight means about said second axis to cause said weight means to move about said first axis toward a position at which said distance is a maximum, said weight means having sufiicient mass to cause said member to vibrate about said first axis before said weight means reaches such position so that upon an increase in the effective mass of said member said weight means will swing toward such position to compensate for such increase and will swing away from such position to compensate for a decrease in the effective mass of said member thus to maintain said member vibrating about said first axis to maintain a uniform amplitude of vibration.

3. A screen vibrating apparatus for imparting constant amplitude of vibration to a screen member whose effective mass varies in accordance with loading and other conditions, comprising means mounting said member for vibrating movement, a pair of weights mounted on said member for swinging movement about a first axis and for rotary movement about a second axis parallel to said first axis but offset therefrom so that swinging movement of said weights about said first axis changes the distance between the center of gravity of each weight and said second axis, means for rotating said weights about said second axis to cause said weights to move about said first axis toward positions at which said distanceflis a maximum, said weights having sufiicient mass to cause said member to vibrate about said first axis before said weights reach such positions so that upon an increase in the effective mass of said member said weights will swing toward such positions to compensate for such increase and will swing away from such positions to compensate for a decrease in the effective mass ofsaid member thus to maintain said member vibrating about said first axis to maintain a uniform amplitude of vibration and means operable when said machine has ceased operating at normal speeds for disposing said weights in places at which their centers of gravity are generally on opposite sides of said first axis so that said machine may start or stop without excessive vibration.

4. A screen vibrating apparatus for imparting constant amplitude of vibration to a screen member whose effective mass varies in accordance with loading and other conditions, comprising means mounting said member for vibrating movement, weight means mounted on said member for turning movement about a first axis and for rotary movement about a second axis parallel to said first axis but offset therefrom so that turning movement of said weight means about said first axis changes the distancebetween the center of gravity of said weight means and said second axis, means for rotating said weight means about said second axis to cause said weight means to move about said first axis toward a position at which said distance is a maximum, said weight means having sufficient mass to cause said member to vibrate about said first axis before said weight means reaches such position so that upon an increase in the eifective mass of said member said Weight means will swing toward such position to compensate for such increase and will swing away from such position to compensate for a decrease in the effective mass of said member thus to maintain said member vibrating about said first axis to maintain a uniform amplitude of vibration and means operable when said machine has ceased operating at normal speeds for disposing said weight means at a place at which its center of gravity is near said first axis so that said machine may start or stop without excessive vibration.

5. A vibrating apparatus for imparting constant amplitude of vibration to a member whose effective mass varies in accordance with loading and other conditions, comprising means mounting said member for vibrating movement, a pair of weights mounted on said member for swinging movement about a first axis and for rotary movement about a second axis parallel to said first axis but offset therefrom so that swinging movement of said weights about said first axis changes the distance between the center of gravity of each weight and said second axis, means for rotating said weights about said second axis to cause said weights to move about said first axis toward positions at which said distance is a maximum, said weights having sufiicient mass to cause said member to vibrate about said first axis before said weights reach such positions so that upon an increase in the effective mass of said member said weights will swing toward such positions to compensate for such increase and will swing away from such positions to compensate for a decrease in the effective mass of said member thus to maintain said member vibrating about said first axis to maintain a uniform amplitude of vibration.

6. A screen vibrating apparatus for imparting constant amplitude of vibration to a screen member whose effective mass varies in accordance with loading and other conditions, comprising means mounting said member for vibrating movement, a pair of weights mounted on said member for swinging movement about a first axis and for rotary movement about a second axis parallel to said first axis but offset therefrom so that swinging movement of said weights about said first axis changes the distance between the center of gravity of each weight and said second axis, means for rotating said weights about said second axisto cause said weights to move about said first axistoward ositions at which said distance is a rnaximum, said weights having sufficient mass to cause said member to vibrate about said first axis before said weights reach such positions so that upon an increase in the effective mass of said member said weights will swing toward such positions to compensate for such increase and will swing away from such positions to compensate for a decrease in the effective mass o'fsaid member thus to maintain said member vibrating about said first axis to maintain a uniform amplitude of vibration, said weights being freely movable within limits without restraint so that the centrifugal force on said weights determines their posi' tions during normal operation of said machine.

7, A screen vibratingrapparatus for imparting constant amplitude of vibration to a screen member whose effective mass varies in accordance with loading and other conditions, comprising means mounting said member for vibrating movement, a pair of weights mounted on each side of said member for swinging movement about-a first axis and for rotary movement about a second axis parallel to said first axis but offset therefrom so. that swinging movement of said weights about said first axis changes the distance between the center of gravity of each weight and said second axis, means for rotating said about said first axis to maintain a uniformamplitude 0f vibration.

8. "A screen vibrating apparatus for imparting constant amplitude of vibration to a screen member whose etfec tive mass varies in accordance with loading andother conditions, comprising means mounting said member-for vibrating movement, a shaft journaled on sai'dumember and having an eccentric portion, a pair of weights mounted on said portion for swinging movement about the axis thereof and for rotary movement about the axis of said shaft so that movement of said weights about the first-mentioned axis changes the distance between the center of gravity of each weight and the second-mentioned axis, means for rotating said weights about said secondmentioned axis to cause said weights to move about said first-mentioned axis toward positions at which said distance is a maximum, said weights having sufficient mass to cause said member to vibrate about said first-mentioned axis before said weights reach suchyposition so that upon an'increase in the effective mass of said member said weights will swing toward such positions to compensate for such increase and will swing away from such positions to compensate for a decrease in the effective mass of saidimember thus to maintain said member vibrating about said first-mentioned axis to maintain a uniform amplitude of vibration.

References Citedin the file of this patent UNITED STATES PATENTS 2,063,509 Lacy Dec. 8, 1936 2,144,382 Lincoln et al. Jan. 17, 1939 2,208,596 Parks July 23, 1940 2,528,620 Stroud Nov. 7, 1950 FOREIGN PATENTS 645,064 Great Britain Oct. 25, 1950 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,860,783 November 18, 1958 Louis W. Johnson It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 3'7, for "a sectional" read no a vertical sectional column 8, line 19, for "position" read w positions m Signed and sealed this 7th day of April 1959.,

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Aime-ting OHLper Commissipner of Eatcnts