Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INYENTION
In foundry operation, molten metal is poured into
sand molds which have been pre-shaped to a desired contour to
which the metal, when cooled, will conform. After cooling,
it is desirable to remove the sand from the castings in order
that they may be further processed, and it is of course also
desirable to recover as much of the foundry sand as possible
for reuse. The cost of foundry sand is more than an inconse-
quential portion of the entire process, and thus it is highly
desirable that as much sand as possible be recovered for reuse.
It has been~the custom in the past to use a vibrating
shakeout screen to remove the sand from the castings. However,
inasmuch as many castings to be dealt with are of substantial
weight, a number of problems have arisen. Over and above the
normal wear on the bed of the vibrating shakeout screen caused
by the heaving castings, is the fact that the castlngs are,
in effect, "bouncea on the screen and thus fall back on the
screen with considerable impact. If the motors imparting
vibration to the screen are attached directly thereto, the
shock of the cast:ings falling back on the screen can be likened
to a hammer blow and thus where the motors, for example electric
motors, are attached to the screen, heavy loads are imposed on
the bearings of the motors requiring not only the use of heavy
duty bearings, but also causing substantial shortening of the
life of the bearings and thus necessitating frequent replacement.
SUMMARY OF THE INVENTION
The present invention provides an apparatus which --
overcomes the problems set forth above. The present invention
provides a natural frequency system where the bed is vibrated
through a novel spring system connecting the bed to the exciter
and thus the motor involved in producing the vibration need
not be as powerful as would otherwise be required, and the
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hammer blows mentioned above are absorbed by the spring system.
Thus, the bearings of the motors which provide the vibrating
force are not sub]ect to the strain and wear as has been the
case heretofore.
Thus, broadly, the invention contemplates a vibratory
apparatus which comprises a generally horizontally arranged bed,
a plurality of isolation springs supporting the bed for
vibratory movement, an exciter member, and a multiplicity of
exciter springs connected at one end around the periphery of
the bed and connected at their other ends to the exciter to
support the exciter from the bed. A pair of parallel shafts
are rotatably mounted on the exciter member on either side of
and equally spaced from the center of the exciter member, and
an eccentric weight is carried by each shaft, together with
means for rotating the shafts to vibrate the exciter.
BRIEF DESCRIPTION OF THE DRAWINGS
.
Fig. 1 is a side elevation partly broken away
showing a shakeout screen embodying the present invention;
Fig. 2 is a staggered horizontal section along line
2-2 of Fig. l;
Fig. 3 is a staggered vertical section along line
3-3 of Fig. l;
Fig. 4 is a vertical section taken along line 4-4
of Fig. l; and
Fig. 5 is a vertical section taken along line 5-5
of Fig. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, there is shown a shake-
out screen in the form of a bed 10. The bed itself is formed
of a generally rectangular horizontally arranged plate 11
with the plate possessing sufficient thickness to withstand
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the loads to be imposed thereon. Thus, it may be as much as
an inch or more in thickness, depending upon the size of the
castings which are to be handled on the bed. The plate 11 is
provided with a plurality of apertures 12. A pair of end
channel members 13 and 14 are secured to the ends of the plate
while side channel members 15 and 16 are secured to the sides
of the plate. A portion of the channel members extends above
the upper surface of the plate 11 as shown, in order to act as
retaining means to retain castings on the bed. It wlll be noted
from the drawings that the side channel members 15 and 16 are
longer than the plate 11 with their ends extending over base
members 17 which support the apparatus during use. Isolation
springs 18 at each of the four corners extend between the
base members and the side channel members, with the isola-
tion springs permitting vibration of the bed and serving to
isolate the vibrations from the building or other structure
to which the base members 17 are secured.
Welded to the upper face of the plate 11 and extend-
ing between the rows of apertures 12 are a plurality of short
wear bars 20 and long wear bars 21. The short and long wear
bars are upstanding from the plate 11 in alternate rows as
shown in Figs. 2 and 4. ~--
- The bed 10 is reinforced with a number of cross
channels 22 secured to the underside thereof as well as with
a plurality of stiffeners 23 arranged vertically and welded
to the face of the channel members.
Beneath the bed 10 is an exciter member 25. The
exciter member is rectangular in shape and made up of pairs
of I-beams 26 and 27, welded or otherwise secured to end channels
28. The side channels and I-beams just mentioned are arranged to
; form a generally rectangular exciter member having generally the
same size and shape as the plate 11. A number of stiffeners 30
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are used to strengthen the channels and I-beams making up the
exciter member.
The exciter member 25 is supported by and secured
to the bed 10 by a number of coil springs, each secured at
its upper end to the underside of the periphery of the bed 10
and at its lower end to the periphery of the exciter member 25.
Thus, as shown in detail in Fig. 5, each spring 32 is connected
at its upper end to a side channel member 15 and at its lower
end to a complementary side channel member of the exciter 25.
Attached to the underside of the channel members making
up the exciter are electric motors 33 and 34, each carrying a
shaft 35, 36, with the shafts being parallel to each other. At
each end of the shaft on each motor there is provided an eccentric
weight, such as the weights 37, 38 shown in the drawings. When
the motors 33 and 34 are energized, the shafts will rotate in
opposite directions as indicated by the arrows in Fig. 1, and
will, in accordance with a well known phenomenon, synchronize
their rotation so that the eccentric weights will simultaneous-
ly reach the bottom or lowest portion of their orbit of rotation
as shown in Fig. 1, and simultaneously reach the 3 o'clock and
9 o'clock positions (left and right as seen in Fig. 1) as the
motors are operating. Such rotation of the eccentric weights,
of course, causes the exciter member 25 to vibrate vertically
and such vibration will be imparted to the bed 10 through the
medium of the exciter springs 32. The path of vibration will
be vertical and its frequency and amplitude will be in ac-
cordance with the natural frequency of the exciter - exciter
spring - bed system.
In order to collect the sand displaced from the
castings by vibration of the device, there is secured to the
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underside of the bed 10 a pair of end guide plates 39 and 40
and a pair of side guide plates, one of which is shown and
indicated as 41. The guide plates are below the apertures 12
in the plate 11 and serve to direct sand falling through the
apertures into a sand receiver 44 secured to t~e base 17 by means
of the braces 45 and 46. Sand passing into the sand receiver
may be directed thereby onto some form of conveyor for further
treatment before reuse.
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