U.S. patent number 3,800,889 [Application Number 05/258,596] was granted by the patent office on 1974-04-02 for vibrator device for earth boring or compacting.
Invention is credited to Karlheinz Bauer.
United States Patent |
3,800,889 |
Bauer |
April 2, 1974 |
VIBRATOR DEVICE FOR EARTH BORING OR COMPACTING
Abstract
A vibrator is mounted on a universal joint at the bottom of a
hollow shaft which is lowered into the earth for boring or
compacting. The vibrator is horizontally vibrated by an electric or
pneumatic drive mounted in the vibrator body. For boring service
the bottom of the vibrator body comes to a point. To avoid
dissipation of vibratory energy communicated to the shaft by the
universal joint, the latter is placed at a vibration node and a
narrower extension of the vibrator body bearing counterweights
extends upward of the universal joint coupling into the hollow
shaft.
Inventors: |
Bauer; Karlheinz
(Schrobenhausen Obb, DT) |
Family
ID: |
5812830 |
Appl.
No.: |
05/258,596 |
Filed: |
June 1, 1972 |
Foreign Application Priority Data
Current U.S.
Class: |
175/19; 175/56;
175/55 |
Current CPC
Class: |
E21B
7/26 (20130101); E21B 7/24 (20130101); E02D
3/054 (20130101) |
Current International
Class: |
E21B
7/24 (20060101); E21B 7/26 (20060101); E02D
3/054 (20060101); E02D 3/00 (20060101); E21B
7/00 (20060101); E21b 011/02 () |
Field of
Search: |
;175/55,56,19,106
;61/53.5,36 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sutherland; Henry C.
Assistant Examiner: Favreau; Richard E.
Claims
What is claimed is:
1. A vibrator adapted for mounting on a hollow shaft for boring
into the earth or for vibratory earth compacting comprising, in
combination,
a. an elongated body having a cavity therein, having a work surface
at one extremity adapted to be lowered on to the work and having an
extension of reduced girth at the other extremity;
b. a vibration generator in said cavity near one extremity of said
body adapted to excite said body into transverse vibrations;
c. driving means for actuating said vibration generation;
d. a non-elastic, mechanical coupling adapted to hang said
elongated body on a hollow shaft in such a way that said extension
projects into said shaft and that the attachment of said coupling
to said body is in a location where a vibration node is found when
said body is excited into transverse vibrations by said generator;
and
e. counterweight means mounted on said reduced girth extension of
the elongated body to shift the vibration node to the coupling
location.
2. A vibrator as defined in claim 1 in which said vibration
generator is positioned with its actuating elements near said lower
extremity of said elongated body.
3. A vibrator as defined in claim 1 in which said coupling is a
universal joint.
4. A vibrator as defined in claim 1 in which said driving means in
an electric motor.
5. A vibrator as defined in claim 1 in which said body is
essentially cylindrical in shape, said work surface is the surface
of a tough conical point and said generator is adapted to excite
said vibrations at a location near said work surface.
6. A device for vibratory boring into the earth or vibratory earth
compacting which comprises, in combination:
a. an elongated body having an elongated cavity therein, having a
work surface at its lower extremity and having an extension of
reduced girth providing its other extremity;
b. a vibration generator in said cavity near one extremity of said
body adapted to excite said body into vibration such that said work
surface is caused to move transversely with respect to the
longitudinal axis of said body;
c. driving means in said body for said vibration generator;
d. a supporting shaft for said body which shaft is hollow at least
at and near its lower end, said shaft having a girth approximately
equal to or slightly smaller than that of said elongated body and
having hollow space sufficiently larger than said extension of said
body to permit said extension to vibrate without impinging on said
shaft;
e. a non-elastic, mechanical coupling connecting a node of said
vibrations of said body to the lower end of said shaft, so that
said extension protrudes into the hollow of said shaft and so that
said body is securely mounted on said shaft with little or no
restraint of said vibrations; and
f. counterweight means mounted on said reduced girth extension of
the elongated body to shift the node of said vibrations to the
coupling location.
7. A device as defined in claim 6 in which said vibration generator
is positioned close to said lower extremity of said body.
8. A device as defined in claim 6 in which said coupling is a
universal joint.
9. A device as defined in claim 8 in which said driving means is an
electric motor, said body and said shaft are essentially
cylindrical in shape and said work surface is the surface of a
tough conical point.
Description
This invention concerns a vibrator for compacting soil and other
solids and for boring into the earth. The vibrator, like other such
devices already known, comprises a vibrator body with a vibration
generator and its drive and also a coupling for hanging the
vibrator body on a shaft.
Devices are known for compacting soil or for boring holes that
utilize a vibrator body containing a vibration generator adapted to
drive the vibrator body in horizontal vibrations which then impinge
on the surrounding soil or other solids to be compacted or
bored.
When such a vibration body is hung on a rigid shaft, usually a
hollow shaft, and lowered into the material to be compacted, the
shaft above the coupling usually vibrates also. Thus, part of the
vibration energy, which particularly in the drilling of well bores
should be concentrated in the vibrator, is lost to the boring
process. Apart from this undesired energy loss such an arrangement
has the further disadvantage that under certain conditions the
coupling between the vibrator and the shaft, or the shaft itself,
breaks.
To counteract this disadvantage it has heretofore been proposed,
for example in German Pat. No. 1,021,264, to provide an elastic
coupling between the shaft and the vibrator body in order to reduce
or avoid the transmission of vibrations to the shaft. Such elastic
couplings have the disadvantage, however, that they are not suited
for the mechanical connection between the vibrator and the shaft.
On account of the high horizontal vibration load of the coupling,
it is impossible to prevent a coupling of elastic construction from
soon being damaged and ultimately breaking or tearing.
The object of the invention is to devise a vibrator equipment in
which the coupling, so far as possible, is not subject to any
horizontal vibration and hence does not need to be made elastic.
The solution of this problem is found by the present invention in a
vibrator with a body relatively long in vertical dimension in which
the vibration generator is arranged in the region of one end of the
vibrator body and in which the coupling to the shaft is located at
a vibration node of the vibrator body. On the upper end of the
body, which may generally take the form of a tapered extension
penetrating the interior of the shaft, weights serve to place the
node at a convenient point for coupling, which is to say they make
possible the use of a relatively short upper extension.
When an elongated body is vibrated, there is generally a location
where the imposed vibrations may be regarded as concentrated, and
then there is generally also a mathematically calculable point
inside or outside the body where vibrations in the opposite sense
may be regarded as concentrated. Between those two vibration
centers there is a point of the body which is not brought into any
vibrational motion whatever. In the case of an elongated body with
uniform distribution of mass and uniform density, for example a rod
or a tube, when the application of vibratory force is made at right
angles to the longitudinal axis of the body at one of its ends, the
vibration node lies in the other half of the body. If on the other
hand the application of vibratory force occurs in the middle of the
body, the node for the vibration lies at infinity. In order to
avoid setting the coupling between a vibrator body and a supporting
vertical shaft into horizontal vibrations and transmitting such
horizontal vibrations to the shaft when the vibrator is
horizontally excited, it is accordingly necessary to place the
vibration generator near one end of an elongated vibrator body, so
that a vibration node will appear at some level of that body and to
provide the coupling to the supporting shaft in the neighborhood of
the vibration node.
When a vibrator is used for downward boring operation, there is
advantage in placing the point of greatest horizontal vibration as
far down as possible in the vibrator body and it is accordingly
advantageous to locate the vibration generator in the lowest
portion of the vibrator body as directly as possible over its
working extremity which, at least in the case of boring equipment,
is usually pointed and hard.
A general angular rotation linkage, for example a universal joint
or a ball and socket joint, is preferably used for the coupling.
Besides, other known linkages that can transfer compression and
tension forces can be used, however.
For the compacting of soil down to relatively great depths and for
the boring of deep holes with a vibrator, it is effective to use a
hollow mounting shaft with the same external diameter as the
vibrator body or a diameter only a little smaller than that of the
vibrator body. In order to prevent the upper end of the vibrator
body from hitting against the inner wall of the hollow shaft above
the location of the coupling during horizontal vibration, it is
desirable to taper the upper portion of the vibrator body above the
vibration node. The universal joint indeed is not subject to
horizontal vibration, but the upper part of the body, which may
have the form of an extension of reduced diameter, executes
horizontal vibrations of an amplitude that increases proportionally
with the distance from the vibration node.
It appears that the location of the vibration node of a body, when
the effective center of vibrations is in the neighborhood of one
end of it, depends not only on the length of the body but
importantly on the distribution of mass along the length. It is
therefore advantageous to reduce the length of the portion of the
vibrator body extending into the hollow shaft by the provision of
counterweights which increase the vibrating mass in this part of
the vibrator body compared with that in the remaining portion,
producing the desired angular moment with a smaller distance from
node to end.
For the further explanation of the invention reference is made to
the illustrative embodiment of the invention shown in the annexed
drawing, in which:
FIG. 1 is a partial longitudinal section through the vibrator body
which is suspended on a hollow shaft, and
FIG. 2 is a cross-section of the coupling.
The vibrator body 1 is a hollow structure having a pointed bit 2 at
one end and at the other end an extension 3 of smaller diameter
than that of the hollow body 1.
In the bottom portion of vibrator body 1 immediately above the bit
2 a vibration generator 4 of known type is provided which is driven
by a drive motor 5 located above the vibrating element 4. For the
drive an electric or hydraulic motor can be used in a known
way.
The extension 3 of the vibrator body 1 projects into the end of the
hollow shaft 6 the outer diameter of which is about the same as
that of the vibrator body 1 or only slightly smaller. The shaft 6
may be the end of a string of pipe to which addition is made at the
top in the usual way as boring progresses. The vibrator body is
connected to the end of the hollow shaft 6 by a universal joint 7
surrounding the extension 3. The universal joint 7 is located at
the vibration node of the vibrator body 1. Above the universal
joint 7 counterweights 8 are provided on the periphery of the
extension 3. The position of the node can be approximated by
calculation or experiment and if coupling at the position first
determined is found still to transmit some vibration when the
vibrator is loaded by its work, a small shift of the axial position
of the counterweights will shift the node to the coupling
location.
* * * * *