US2722407A

US2722407A - Vibrating apparatus for concrete

Info

Publication number: US2722407A
Application number: US345486A
Authority: US
Inventors: Bakker Johannes
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-03-30
Filing date: 1953-03-30
Publication date: 1955-11-01
Anticipated expiration: 1972-11-01

Description

Nov. 1, 1955 J. BAKKER VIBRATING APPARA'I JTL IS FOR CONCRETE Filed March 50, 1953 FIG United States Patent VIBRATING APPARATUS FOR CONCRETE Johannes Bakker, Lange Ruige Weide, Netherlands Application March 30, 1953, Serial No. 345,486

2 Claims. (Cl. 259-72) The invention relates to a vibrating apparatus, more particularly a vibrating table, for vibrating concrete or like plastic hardening material, in which the vibrating surface is resiliently connected to a supporting frame and the oscillations are generated by means of rotatable eccentric masses.

Such apparatus are known. They have a single vibrating surface in the form of a table-leaf or a vibrating frame composed of longitudinal and transverse girders, which vibrating surface at the bottom side carries a spindle extending over a. part of the length in the middle thereof and provided with mutually in phase eccentric masses, which spindle is driven by a motor. Though in this way the drawback of vibrating apparatus with a relatively large vibrating surface which is brought to vibration by a single eccentric mass, that the intensity of the vibrations decreases with the distance from the source of oscillations, can be met, these known constructions have the drawback, that the long spindle and the bearings are very unfavourably loaded, as well as the motor. For meeting this drawback it is also known to arrange the eccentric masses each on a short spindle supported in hearings on both sides, which spindles are mutually connected by flexible couplings, so that all eccentric masses can be driven in common and mutually in phase. In this way, indeed, in mechanical respect an improvement is obtained, but the unfavourable load remains and is even still more unfavourable than with vibrating apparatus with a single source of oscillations as the more uniform distribution of the intensity of vibration over the area of the vibrating surface is obtained by a considerable increase of the total excentric mass. With all these vibrating apparatus, furthermore, the number of oscillations generally does not surpass about 3000 oscillations/ min. Indeed, vibrating apparatus are known in which very fast running motors are used, which attain up to 8000-9000 oscillations/min, but these latter apparatus can only be made for limited small powers. It is, however, known that for vibrating concrete for several reasons higher numbers of oscillations would be very desirable.

The invention now aims at providing a vibrating apparatus with which very high numbers of oscillations of selected powers and very favorable distribution of the intensity of vibration over the vibrating surface can be obtained.

According to the invention this is achieved by that the vibrating surface is composed of a number of separate parts lying beside one another, which parts can each be brought to oscillation by a rotatable excentric mass, the excentric masses being mutually coupled out of phase in such a manner that they jointly transmit a multiple of the frequency of oscillation of each of the masses to the material to be vibrated. In this way a vibrating apparatus is obtained, in which, as the separate parts can be made as narrow rigid beams or girders, a very favourable distribution of the intensity of oscillation over these parts is obtained, while at the same time with normal 2,722,407 Patented Nov. 1, 1955 numbers of revolutions of the driving of the excentric masses of about 3000 revolutions/min., by arranging an adequate number of parts beside one another, easily frequencies of oscillation can be obtained of 12000-24000 oscillations/min. and higher, while, by that the number of revolutions of the driving does not need to be correspondingly higher but is a normal number of revolutions of a motor of about 3000 revolutions/min, each desired power can be applied. A particular advantage of the vibrating apparatus according to the invention further is, that the number of oscillations of the whole apparatus is no longer dependent of the dimensions of the vibrating surface, as was the case e. g. with the vibrating tables hitherto known, or any way is influenced by it to a considerably smaller degree, as according to the invention no longer a whole surface is brought to oscillation in which eventually stationery waves can arise so that no uniform oscillation is obtained-but the vibrating surface is composed of separate oscillating parts.

Appropriately in practice the rotatable excentric masses are mutually adjustable with respect of their phase relation and are unrotatably coupled by flexible connections and driven in common. Such a construction is at the same time favourable for the driving motor as the excentricities, which are mutually coupled out of phase, act less as an excentric load as the number of excentricities increases.

The invention will now be further elucidated with reference to an example of performance shown in the drawing. In the drawing:

Fig. 1 shows an end elevation, partially a cross-section of four vibrating surface parts resiliently supported beside one another on a supporting frame of a vibrating table according to the invention,

Fig. 2 shows a cross-section, of Fig. 1, and

Fig. 3 shows a partial side elevation of a vibrating surface part with resilient supporting means and excentric mass connected to it.

In the drawing the

reference numerals

1, 2, 3, 4 indicate four'vibrating surface parts of a vibrating table arranged at regular small mutual distances beside one another. These parts consist of I-girders which are connected to the supporting frame 8 in a vertically displaceable manner with the aid of bolts 5 and upper springs 6 and under springs 7. At one or both ends the I-girders 14 each carry an excentric mass 11 rotatably fixed on a spindle 10 which is journalled in a closed housing 9. These excentric masses are secured to the Igirders with the aid of strips 12 connected to the housing 9 and bolts 13. The spindles 10 of the excentric masses are mutu ally connected by flexible couplings 14. The excentric masses are fixed to the driven spindles 10 in out of phase relation and are combined to one or more groups of e. g. four to eight in such a manner that they jointly give, when driven at a speed of about 3000 revolutions/min, a frequency of oscillation of the vibrating surface of 12,000-24,000 oscillations/min. or higher. With a subdivision of the vibrating surface parts in groups of four I-girders, this e. g. can be obtained by adjusting the excentric masses of the girders 1 and 3 mutually 180 out of phase, and likewise the excentric masses of the girders 2 and 4, but taking care thereof that these latter lie out of phase with respect of the excentric masses of the girders 1 and 3. The excentric masses then all lie mutually 90 out of phase. Thus it is also possible to compose groups of five vibrating surface parts with a mutual phase difference of 72, etc. The groups are naturally coupled with one another in such a manner that they lie mutually in phase.

An apparatus according to the invention can also be executed as a mould vibrator and as an immersion vipartially a top elevation alsobe'fixe'd in the middle at the "bottom side of the I-girders. A like arrangement of the oscillating masses canalsotbeapplied with other vibrators if .desired.

Having .now 7 particularlydescribed and ascertained .the naturetofmytsaid'invention an'd'in What manner the ,same is to belperforme'dll declare that whatlclaim isz 1. ,A vibrating device for vibrating concrete and like plastic hardening material 4 comprising, .in combination, @a supporting 'frame, ,a plurality of spaced, .but closely .adjacent, supporting members providing a supporting surfacerfor the material to'be vibrated, :said members being resiliently connected to said supporting frame, .and an eccentric mass rotatably mounted in each ofsaid ,members, the eccentric rotatable masses of .said members being mutuallycoupled out of phase in such manner .that theyjointly transmit to the materialcarriediby said members a multiplesof the frequency of oscillationof-reachof the masses.

2. A vibrating apparatus as defined in claim 1, wherein each "rotatable eccentric mass is adjustable 'tovaryits phase relation with the other eccentric masses and the eccentric masses are coupled by flexible connections and driven simultaneously from a common power source.

References Cited in the file of this patent UNITED STATES PATENTS 1,806,620 Flam May 26, 1931 1,943,076 Jackson Jan. 9, 1 934 2,204,007 Baily June 11, 1940 2,610,040 Emmons :Sept.*9, 1952 (FOREIGN EPAEEENTrS 819,492 France Oct. 19, 1937