US3549130A

US3549130A - Concrete vibrator

Info

Publication number: US3549130A
Application number: US726761A
Authority: US
Inventors: Eugene C Briggs
Original assignee: Koehring Co
Current assignee: ARROW MASTER INCORPORATED A CORP OF ILLINOIS; Koehring Co
Priority date: 1968-05-06
Filing date: 1968-05-06
Publication date: 1970-12-22
Anticipated expiration: 1987-12-22
Also published as: FR2007941A1; GB1253622A; DE1922764A1

Description

United States Patent [72] Inventor Eugene C. Briggs [56] References Cited Dayton, UNITED STATES PATENTS P 7265,61 2,167,987 8/1939 Mall 259/1 [22] Filed May 6,1968 [45] Patented Dec 22 1970 2,293,962 8/1942 Baily 259/1X [73] Assign xonhfirig Company 3, 042,386 7/1962 Wyzenbeek 259/] Milwaukee Wis. 3,236,502 2/1966 Eisenbeis 259/] a corporation of Wisconsin Primary ExaminerRobert W. Jenkins Attomey Marechal, Biebel, French & Bugg ABSTRACT: A concrete vibrator has an elongated extruded thin-walled housing which encloses a rotatably driven eccen- [54] CONCREIE fi g tric weight of circular cross section, and the outer surface of 9 Claims Draw 8 the housing is formed by a plurality of peripherally spaced and 259/1 longitudinally extending concaved faces which are effective to B0lfll/00 produce concentrated forces within the concrete adjacent [50] Field of Search 259/1 each face with minimum slippage between each face and the (Vib. Mech.), (Vib. Electra); 74/87 adjacent concrete.

1//v ri// PATENTED'UEBZZIIBYB E IN VE/V TOR EUGENE C. BRIGGS 2-2 ofFlG. 1;

CONCRETE VIBRATOR BACKGROUND OF THE INVENTION In a concrete vibrator as disclosed in Spitler US. Pat. No. 2,808,238 assigned to the same assignee as the present invention, it is desirable to minimize the slippage of the concrete relative to the outer surface of the vibrator housing when the vibrator is immersed and orbiting at a high speed in a mass of concrete so that maximum thrust or energy is imparted by the vibrator to the concrete for quickly filling any air voids or cavities within the concrete. Accordingly, the housing of the vibrators have been constructed with various external configurations other than the commonly used cylindrical configuration.

For example, a housing having a square shaped outer crosssectional configuration and a cylindrical housing having longitudinally-extending external ribs have been used since the flat sides of the housing or the ribs will impart somewhat greater thrust-to the concrete during the highspeed orbital movement of the housing than will a cylindrical housing.

,While each flat surface'of a polygonal shaped housing or of a "rib on a cylindrical housing will transfer additional thrust to S UMMARY OF THE- INVENTION The present invention is directed'to an improved concrete vibrator which incorporates a housinghavingan outer surface formed by a plurality of peripherally spaced and longitudinally extending concaved faces which cooperate to impart energy or thrust tothe adjacent concreteduring substantially the entire orbital path of travel of each face. That is, the high-speed orbital movement of each concaved face causes the adjacent portion of the concrete to travel in acorresponding orbital path with minimum slippage between the concrete and the face so that the voids or air pockets in the concrete are rapidly filled.

The concrete vibrator of the present invention also incorporates a novel extruding housing of relatively low mass thereby enabling a reduction in the mass of the rotor or eccentric weight required for orbiting the housing at a predetermined arnplitude. Furthermore, low mass needle bearings are used to support the rotor and as a result of the lower mass of the rotor, the bearings are subjected to'lower stresses thus extending the service life of the bearings. The relative low mass of the housing and other nonrotating parts also permits a correspondingly greater amplitude in orbital movement with the same rotor. and rotor speed, thus imparting a higher proportion of energy into the concrete.

The extruded housing may be formed of aluminum, titanium, steel or other suitable materials, and if formed of soft material such as aluminum, it is coatedwith a suitable hard coating. The extruded construction of the present invention permits a thin walled housing in regions where there is very little wear due to abrasion.

Other features and advantages of a concrete vibrator constructed in accordance with the invention will be apparent from the following description, the accompanying drawing and the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a concrete vibrator constructed in accordance with the invention and having a portion shown in axial section as taken on the line 14 of FIG. 2;

FIG. 2 is a transverse section taken generally along the line FIG. 3 is an enlarged fragmentary transverse section of the housing shown in FIGS. 1 and 2 and illustrating the converging forces exerted on the concrete adjacent each face of the housing; and FIG. 4 is a fragmentary section through a modified form of the vibrator housing.

DESCRIPTION or THE PREFEItltBD EMBODIMENT As illustrated in FIG. 2,.the housing 15 is formed as a thin wall steel extrusion. The housing 15 has an outer surface fonned by peripherally spaced and longitudinally extending concave faces each of which has a radius R corresponding generally to the diameter D of a circle inscribingthe housing. The uniformly spaced concaved faces '25 joiii I to form peripherally spaced, longitudinally extending noses 28 which are slightly rounded. The noses 28 have radii of curvature which are small compared to the radii of curvature of the concave faces 25.

A rotor 30 is rotatably supported within the housing 15 and includes a cylindrical eccentrically disposed weight portion 32 extending within the bore 16, and connecting

cylindrical journal portions

33 and 34 defining an axis of rotation offset or eccentric to the axis of the weight portion 32. A cap 35 is threaded into the end portion 19.of the housing 15 and includes a cylindrical portion 36 which seats on the cylindrical surface 17 and provides aninternal cylindrical bore 31 for retaining an antifriction needle bearing 40 mounted on the journal portion 33 of the rotor 30. A stud 41 is pressed-fitted into a hole 42 formed within the end of the journal portion 33 and has a hardened head 44 which engages a hardened steel ball thrust bearing 45 confined within a conical shaped cavity 46 formed within the cap 35. I

A tubular coupling 50 is threaded into the opposite end of the housing 15 and has a cylindricalpor'tion 51 which seats on the surface 18 and defines a cylindrical bore 52 for receiving another antifriction needle bearing 40 mounted on the journal portion 34 of the rotor 30. An annular resilient seal 55 is also positioned within the bore 52 adjacent a radial shoulder 56 and engages the journal portion 34 to confine a predetermined quantity of oil placed within the housing 15 during assembly portion 68 formed as an integral part of the rotor 30. A crosspin 70 rigidly connects the coupling 65 to the rotor drive portion 68 and thereby transmits the driving torque from the shaft assembly 59 to the rotor 30. An annular felt washer 71 surrounds the shaft coupling 65 and serves to prevent dirt and other foreign matter from coming in contact with the oil seal 55.

The operation of the invention may be understood by reference to FIG. 3, which shows the lines of force which are imparted by the housing 15 into the concrete material. Thus, when the housing is so immersed and the rotor 30 is rotated at high speed by the drive 60, such as for example at 13,000 rpm, the housing 15 moves in a correspondingly high-speed orbital path. Each concave outer surface 25 in turn produces the generally radially converging forces F on and within the adjacent concrete. The concave curvature of the faces 25 serve to prevent the escape of concrete, as compared to a head in which the surface is of cylindrical shape, ribbed cylindrical, or flat. In fact, the surfaces 25 operate somewhat in the manner of the curved blades of a Pelton-type' turbine wheel,

' concave faces 25, running from the bottom to the top of the vibrator, will oscillate at progressively less amplitude from the bottom to the top, since the vibrator is supported at or near the top. This causes the concrete material and the entrained air to flow generally vertically upwardly as directed by the channellike concave faces 25 and results in a pumping action which assists in the removal of the air and increases circulation withing the concrete mix. This pumping action is readily apparent when a vibrator made according to this invention is immersed in water. Separate jets will exude from the sides of the vibrator at each of the faces 25 and will extend upwardly and outwardly to a distance several feet away from the vibrator.

The thin steel extruded housing also provides several important advantages. The construction is one in which a relatively thin wall is formed, as indicated by the arrows 75, in the regions of minimum thickness centrally of each face 25. A thin wall is possible at 75 since abrasive ,wear tends to be concentrated at the noses 28 where the housing wall is the thickest. The wear is the least at 75 where the wall is the thinnest.

As an example, a "pencil" type vibrator housing, constructed according to this invention with seven faces 25 of equal size and uniform angular spacing, had a radius R of curvature of each face of l 1% inches, while the diameter D of an inscribing circle was 1 as inches. The minimum wall thickness as measured at 75 was 0.078 inches.

When the housing 15 is formed'of steel, the minimum wall thickness at 75 is preferably one-tenth inch or less. This is substantially less than the wall thickness of a conventional 1 A inches diameter cylindrical machined steel housing, which .may be approximately 0.15 inch. The minimum wall thickness, as defined above, does not necessarily increase with increases in the diameter of the vibrator housing. For example, in larger vibrators using housing of an inscribed circle diameter D of '2 3 4 inches or more, the minimum wall thickness 75 in the extruded steel housing would remain preferably one-tenth inch or less. When softer materials are used, such a aluminum, the wall thickness can be increased to provide sufficient strength without increasing the overall weight of the housing, since aluminum weighs approximately one third as much as steel.

Referring again to the specific sample given above, the

'housing 15 constructed according to this invention was 1 formed with an overall length of 9.6 inches and weighed 16 ounces. A corresponding conventional l A inches O.D. machined cylindrical steel vibrator housing weighed 25 ounces. In this example, the housing of the present invention represents a 36 percent reduction in housing weight over the corresponding conventional housing. Further reductions in i the overall weight may be realized by the fact that the support bearings 40 are of needle construction, which is possible since the loading on these bearings has been reduced in accordance l with reduction of housing weight. In addition, an increase in the life of the support bearings 40 is made possible due to the lower working stresses.

FIG. 4 shows a cross section through an extruded aluminum housing 15' which has been provided with an outer surface coating 80 of hard wear resistant material, such as nickel or =1 nickel-copper. Such coatings can provide a satisfactory hard and wear resistant surface, and may have a Rockwell hardness preferred due to the relatively lower cost of fabrication as compared to the steel extrusion of FIGS. 1 and 2 and to the possibility of further weight reduction. Alternatively, titanium may be used in place of aluminum in which event coating would not be necessary due to the toughness of that material.

The pencil-type" vibrator shown in FIG. 1 is particularly adapted for use between concrete forms, where the space due to the presence of reinforcing rods and the like may be limited. It is thus a mater matter of importance that the vibrator efficiently and thoroughly pack the concrete into the spaces available. The high energy output of the vibrator of the present invention is of particular. advantage, where space is limited and where it is not always possible to insertthe vibrator head into many different positions within the form.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

I claim:

1. An improved vibrator for compacting concrete material and the like, comprising an elongated tubular extrusion forming a housing having a uniform cross-sectional configuration substantially throughout its length, said housing further having an outer surface formed by at least seven peripherally spaced and longitudinally extending concave faces, an eccentric weight rotatably supported within said housing, closure means on one end of said housing, and drive means connected to said weight through the other end of said housing for imparting orbital movement to each said face and to effect uniformly concentrated converging forces from each said face to the adjacent material and to channel an upward flow of material adjacent each said face.

2. A vibrator as defined in claim 1 wherein each said face has a constant radius of curvature approximately equal to the diameter of a circle circumscribing said housing.

3. A vibrator as defined in claim 1 including a set of antifriction needle bearings positioned within said housing and rotatably supporting said weight.

4. The vibrator of claim 1 wherein said extrusion comprises steel.

5. A vibrator as defined in claim 1 wherein the adjacent said faces of said housing are joined by a longitudinally extending nose surface of small radius relative to the radius of each said face.

6. The vibrator of claim 5 in which the wall thickness of said housing is one-tenth inch or less in the region of said concave faces intermediate said noses.

7. The vibrator of claim 5 in which said extrusion comprises aluminum, and a hard surface coating on the exterior of said housing at said concave faces and said noses for preventing abrasive wear.

8. An improved vibrator for compacting concrete material and the like, comprising an elongated tubular housing, an eccentric weight member positioned within said housing, a set of antifriction cylindrical roller bearings supporting said weight member for rotation, closure means on one end of said housing, a hardened insert mounted within the end of said weight member adjacent said closure means, a thrust bearing mounted on said closure means and engaging said insert,said housing having a plurality of peripherally spaced and longitudinally extending smoothly curved concave faces formingits outer surface, and drive means connected to said weight through the other end of said housing for rotating said weight and imparting orbital movement to each said face to effect concentrated converging forces from each face to adjacent material and to channel an upward flow of material adjacent each said face.

9. A vibrator as defined in claim 8 wherein the adjacent said faces of said housing are joined by a longitudinally extending nose surface of small radius relative to the radius of each said face.