US2479799A - Eccentric rotor for vibrating devices - Google Patents

Description

Aug. 23, R wiLDE 2,479,799

ECCENTRIC ROTOR FOR VIBRATING DEVICES Filed Aug. 11, 1948 37 ET Y j? I T5 36 IN VEN TOR. Aoazer L. M405.

A TTORNE Y.

Patented Aug. 23, 1949 ECCENTRIC ROTOR FOR VIBRATING DEVICES Robert L. Wilde, Englcwood, 0010.

Application August 11, 1948, Serial No. 43,686

7 Claims.

3 This invention relates to improvements in vibrators of the type employed for vibrating cement grout.

It has been recognized for a considerable length of time, that in order to get the best results from a Portland cement concrete, it is necessary to subject the concrete grout while in unsettled state to a high frequency vibration and for this purpose various specific types of vibrators have been invented and are in use.

In order to get the best results, the rate of vibration must be very high and it is nearly always effected by rotating an eccentric rotor at a very high speed within a cylindrical housing.

The very high speed of rotation uses up the lubricating film very quickly and it has therefore been found that the ordinary type of cement vibrator will wear out very rapidly, if used for any considerable length of time, without subjecting it to lubrication.

I my copending app ication, Serial No. 720,- 455. filed January 6. 1947, a vibrator has been illustrated and described which is provided at one end w th an oil reservoir that communicates with the rotor chamber through an axial opening in the corres onding end of the same. By the means de cribed in that application, the rotor beari gs are thoroughly lubricated every time the rotor is laid down.

The rotors emplo ed to provide vibrat ons in cement vibrat ng devices are eccentr c, that is, the center of ma s is ositioned on one side of the axis of r tation. When such vibra or rotates at a hi h s eed. the eccentr city produces a centrifugal force that urges t e trunnions of the rotor a ainst t e bear n s with gh pres ure and since t e center of mass of adjacent transverse layers are all in a line naral el to the axis of rotation. t e centrifu al force is all concentrated in one d rection w ich ac s uniformly at both ends of the rotor'which therefore is subiected merely to a vibrat ng force acting in a plane perpendicular to the axis.

7 It is the ob ect of this invention to produce a vibrating device of such construction that in add tion to the radially acting centrifugal forces that are all in a diametrical plane, other forces are produced that act in angularly related directions, thereby subjecting the rotor and the rotor housing to forces that tend to produce a gyratory movement.

Another object of the invention is to produce a rotor for the purpose indicated, that shall be provided on its outer surface with helical threadlike grooves and projections that give to the rotor end with a trunnion, the two trunnions being Figure 1 by reference numeral 22. trunnion is tubular, the opening therein having the properties of a screw pump which facilitates the movement of oiland assures satisfactory lubri'catlon of the parts at all times during operation.

The above and other objects that may become apparent as this description proceeds and to which reference may hereinafter be made are attained by means of a construction and the relationship of parts that will now be described in detail and'for this purpose reference will be had to the accompanying drawing in which the invention has been illustrated, and'in which:

Figure 1 is a diametrical longitudinal section taken on lines l-I, Figures? to '7, inclusive;

Figure 2 is a section taken on line 2--2, Figure '1.

Referring now to the drawing, reference numeral l5 designates a cylindr cal housin that s provided at one end with a plug 15 that is preferably sweated in place so as to provide a joint that permits the plug to be removed when the parts are heated above th temperature of the solder employed to make the joint at H. This plug is also provided with a remov ble threaded plug I8. It may be mentioned at th s point that p11 1g [6 is normally at the lower end of the vibrator when the same is in use, but has been shown at the top of the drawing for the pur ose of convenience. The inner surface of the housing is provided near its lower end with a sh ulder l8 that forms an abutment for the antifric ion bearings 20 of which three have been shown. Positioned jvithin the housing is an elongated rotor that has been designated in its entirety by reference numeral 2| The rotor is provided at each in axial alignment, the one at the lower end of the drawing has been designated by reference numeral 2| and the one at the upper end of The latter been designated by reference numeral 23 and this is in communication with the interior of the housing at 24. 'I'runnion 22 is positioned in the inner ball races of antifriction bearing 25. Bearings 3 26 are held in place by means of a tubular mem ber 26 that is thicker than the wall of housing I 5, whereby a shoulder 21 is formed that engages the lowermost ball race and serves to hold the ball races in engagement with shoulder 59. Sleeves 23 and 29 are sweated to the outer sur face of member 26 and to the abutting end of housing I and serves to hold the parts in assembled relation, but'permits them to be separated by raising the temperature above the'melting point of the solder employed. A ball bearing 30 is positioned in sleeve 26 and forms a bearing for the inner end of a flexible shaft3l thatiterminates in a hexagonal plug 32.

opening of the proper size to receive plug 32 which therefor forms a coupling that prevents relative rotation, while permitting slightly longitudinal movement. A flexible shaft is' rotated by a suitable motor which has not been shown.

The partstl'iat have just been described are shown in the application aboveidentifi'ed. The invention to which this application relateshas reference to the specific construction of the rotor which will now be described in detail; Therotor is formed from; a cylindrical steel bar of the proper diameter and machined ina lathe so as to providethe' two trunnionsfland 22; The outer surface is then provided with threads 34 which maybe double pitch square threads, or

threads of any other shape which, however,

should preferably be quite coarse; A helical strip is now removed'from' the rotor; Thesurface of the rotor that isleft afterthe striphasbeen removed'has been designated byreference-numeral 35. Surface 35 is arcuate and is formed by a point rotating around a center. positioned: on the outside of the rotor the center moving longitudinally'in a helicafpath. In Figure-3-Ithe center point has been designated by reference numeral 3'6 and isv positioned: in: the outer surface of the thread-ed section. The radius of surface 35 has been; designated: byR- and: the; completed circle has been indicated by broken lines in Figure 3'. In the embodiment illustrated in 'the drawing center 36 is shown in Figure 3 asbeing on-the-diameter Atsectionpoint 4-4, the center has moved so that: it now-lies on adiameter indicated by force line P. In-Figure 5, the center has'movedsothat lineOP makes a=greater angle with thediametrical plane l--l-, while atsection 6--6= the center point 36 has moved upwardly to its maximum point, The helical strip thus removed is twisted in. a; helical direction the amount of angle wshown in-.Figure-6.

It is to be understood that the helical displacement of the center can be" reater than. that shown in: the drawing. which is merely illustrativ-e; It may at times be preferable toincrease angle 20 to ninetydegrees instead of as shown. The actual value of anglewis-not criticaland can be selected as determined by practical experience and operation. That pastor the rotor that has been designated by reference numeral 3'!- is of smaller diameter than the threaded portion and serves as a flange: and an abutment.

The part between the upper ball bearing 25 and the inner surface of plug l6'isan oil reservoir and: this has been designated by reference numeral 38. When the deviceisin use plug lfi is at the lower end and the, oilwill naturally flow into this part of the housing. It has been found that when the rotor is turning at a high speed in the direction of the arrow, there is a pumping action. taking place that tends to move. the oil Trunnion '25" has secured thereto a cup 33 having ahexagonal.

upwardly from reservoir 38 and bring some of it into engagement with the bearing 20 so as to produce a continuous lubrication.

Referring now more particularly to Figures 3 to 6', inclusive, it will be seen that the centrifugal force P of each longitudinal section extends radially and it..will also be evident that at each differential layer the centrifugal forces will operate i'n-a. slightly differentradial; direction. This is apparent from the four sectionsillustrated on the drawing. It is therefore evident that the centrifugal force nearest the trunnions will be directed in angular different directions and will therefore set up forces tending to produce a gyratory. movement of the housing when it is positioned in the cement grout. This gyratory movement, in addition to the regular transverse vibration, produces a greater effect on the grout for producing a settling of the particles therein than that which can be obtained by the simple vibration due toa straight unbalanced part of the rotor such ashas beenv formerly employed and which is shown, for example, inthe applicationabove identified.

Let us-now assume that the vibator isin use androtating. at a high speed, sometimes as high as tenthousand R. .P. M. The-vibration: and the yratory action willchange-the upper: surface intoa depression indicatedbybroken line. 39- and oil will move upwardly-throughbearings 25. The helical threads whose tops lie. close to the inner surface of the: housing will act as a screw pump-and move the oil-upwardly alongthe inner surfaceofthe housing. The path of the upward.- l-y moving. oilhas been; shown by arrows 40. When the oilreaches bearings. 30 it will lubricats them and turn inwardly because seal 4| stops further upward. movement of theoil.

TheI high speed at which the. rotor turns leaves a low pressure area in the center of the housing through which the oil returns along the path indicated. by arrows 12.v The oil returns to sump-38through opening 24'.- in trunnion. 22.

In the drawing arrows 40.- and. 42 have been shownstralght, as theyare. intendedto. show the general direction of movement; as a. matter of fact the'path of the oil is a helix of small pitch being the resultant of the longitudinal. and the rotary forces to which it is subjected.

The. specific construction of the housing can be selected to obtain. the desired results and the oneshown in the drawing isillustrative only.

It is evident that the screw pump action due to threads 34 is. independent of the pitch angle of the unbalanced portion and, will produce the desired pumping action with, a. rotor where the centers of mass: of the. eccentric portion all lie in the same diametrical plane.

Having described the invention what is claimed asncwis:

1.. Anelongated rotor for use in concrete vibrators having an elongated cylindrical housing in which the rotor is rotatahly mounted, said rotorhaving axial end trunnions, whereby the instantaneous centrifugal forces will be angularly distributedv between. the trunnions.

2. A rotor in accordance with. claim 1 in which the outer surface of the rotor is provided with coarse threads adapted to pump lubricant axial 1y of. the rotor.

3. In a vibrator mechanism having an elongated cylindrical housing adapted to be immersed in a. mass of material to be vibrated, an elongated rotor mounted for rotation in the housing, said rotor having each and provided with an axial trunnion for mounting a bearing, that portion of the rotor between the trunnions being eccentric with respect to the axis of rotation, the centers of mass of adjacent transverse layers being in a helical line whereby the instantaneous centrifugal forces adjacent each trunnion will act in angularly displaced radial directions, thereby imparting to the housing a vibratory motion due to the eccentricity of the rotor and a helical gyratory motion due to the angularly displaced centrifugal forces.

4. A rotor in accordance with claim 3 in which the outer surface of the rotor is provided with coarse deep helical threads adapted to pump lubricant axially of the rotor.

5. An elongated unbalanced rotor for use in vibrating concrete and which is adapted to be rotatably mounted in an elongated cylindrical housing having longitudinally spaced bearings,

the rotor having its ends provided with coaxial trunnions and an intersecting surface generated by a curved line turning about a center moving in a helical path concentric with the axis of the rotor, the radius of the helix being greater than one-half of the diameter of the rotor.

6. A rotor for use in a cement vibrator comprising an elongated rotor element having its ends provided with coaxial trunnions, that portion between the trunnions being eccentric with respect to the axis of rotation, the centers of mass of adjacent transverse layers lying in a helical line whereby the angularly directed centrifugal forces will impart to the rotor a tendency to gyrate.

7. An elongated unbalanced rotor for use in vibrating a plastic mass and which is mounted for rotation about its longitudinal axis in a housing having a cylindrical opening of a diameter slightly greater than twice the maximum radius of the rotor, comprising an elongated member provided with coaxial end trunnions, that portion of the rotor between the trunnions having its center of mass on one side of its longitudinal axis, the outer surface of the eccentric portion being concentric with the trunnions and provided with helical threads for moving oil longitudinally in the housing.

ROBERT L. WILDE.

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

UNITED STATES PATENTS Number Name Date 1,459,841 Mitchell June 26, 1923 1,806,620 Flam May 26, 1931 FOREIGN PATENTS Number Country Date 767,356 France July 17, 1934 Certificate! of Correction Patent No. 2,479,799 August 23, 1949 ROBERT L. WILDE It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

- Column 4, line 64, after the word and comma trunnions, insert that portion of the rotor between the trunnions being eccentric with respect to the axis of rotation, the centers of mass of ad acent transverse layers being in a helical line;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. Signed and sealed this 24th day of January, A. D. 1950.

THOMAS F. MURPHY,

Assistant Oommiasioner of Patents.

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