Note: Descriptions are shown in the official language in which they were submitted.
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INTEGRAL SOLID FRONT GAUGE CASE FOR A PRESSURE GAUGE
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Background of the Invention
1. The field of art to which the invention pertains
includes the art of measuring and testing as directed to
fluid pressure gauges.
2. Gauge instruments and particularly pressure gauges
or the like have been widely used and are commercially avail-
able from a variety of manufacturing sources. Being that
such pressure gauges enjoy very extensive commercial and
industrial use, they are supplied by a plurality of menu-
lecturers and are regarded as high production items. Because
they are sold in very price conscious competition, each menu-
lecturer instinctively strives to reduce product costs by
improvements, however marginal, which reduce labor and/or
materials that can contribute to cost savings in the end
product.
A common form of case construction for a pressure gauge
comprises the "solid front" type in which an intermediate
wall separates the case into front and rear compartments.
In the usual arrangement, the front compartment contains the
indicating mechanism, whereas the pressurized element is
contained in the rear compartment such that should the
element incur failure from overpricer or whatever, relief
is afforded rearward rather than forward of the case. Con-
struction of the solid front gauge case is largely governed
by the American National Standard Institute (ANSI) Standard
B40.1-1974, Section 3.1.1.2.
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Typical prior art solid front gauge case constructions
as shown by the patent literature include those in which
the solid front wall is separately fabricated and then
joined to the peripheral case wall of another construction
as, for example, disclosed in US. patents 4,154,166 and
4,175,444. There are also those in which the solid front
wall is cast or molded integral with the peripheral wall as
disclosed, for example, in US. patents 2,215,013 and
2,752,787. Whereas it has long been recognized that the
aforementioned solid front gauge constructions have been
comparatively costly to manufacture, it has not heretofore
been known how to significantly reduce such costs.
Statement of Invention
According to the present invention there is provided a
solid front gauge case for a pressured gauge including an
integral sheet metal construction of an annular outer
wall, a solid front wall positioned integrally toward the
front of the other wall in the diametral plan thereof with
means to receive a closure in the rear able to afford
relief of pressure from within. According to another
aspect of the invention there is provided a method of
forming a solid front gauge case for a pressure gauge which
includes the steps of cutting a sheet metal blank of
predetermined size, deforming the cutting into a cup-like
configuration having an annular wall defining an internal
cavity closed at one end with a wall and opened at the
other end, and laterally deforming the end wall to a
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displaced location internally toward the front of the
annular wall and in the diametral plan thereof.
It can be seen, therefore, that the present invention
relates to a novel solid front case construction therefore
less costly to fabricate than similar type case
constructions of the prior art. More specifically, this is
achieved in accordance with the invention by means of a
case formed of a cutout from a sheet metal stamping. After
forming the cutout, it is deep drawn to a shape
constituting an annular enclosure defining an internal
cavity therein open at one end and closed by an end wall at
the other end. By means of a reshaped die subsequently
applied laterally against the exterior face of the end wall
in a direction inward of the cavity, the wall is deformed
to a predetermined reentrant recess inward of the enclosure
to constitute the "solid front" of the case. On
subsequently punching the necessary apertures for receipt
of the operating mechanism and supplying a suitable rear
enclosure, the case is completed and ready for use. By
this relatively simple fabrication procedure a solid front
gauge case is formed with all the attributes of more costly
prior art constructions but at significantly less cost
It is therefore an object of the invention to effect a
novel solid front gauge case for a pressure gauge less
costly to fabricate than heretofore.
It is a further object of the invention to provide a
novel method for producing the gauge case of the previous
object.
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of:
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It is a still further object of the invention to
manufacture a pressure gauge with the case of the previous
objects.
Brief Description of the Drawings
Figs. 1 and 2 are sequential sectional views of a solid
front gauge case formed in accordance with the invention;
Fig. 3 is a sectional elevation through a pressure gauge
utilizing the gauge case hereof; and
Fig. 4 is an alternative construction for the encircled
portion of Fig. 3.
Referring now to Figs. 1 and 2 of the drawings, the
gauge case hereof designated 10 is initially formed into the
cup shaped arrangement of Fig. 1 by stamping and deep drawing
a cutout from sheet metal to form an annular periphery 12
of dimension A and width D. Internally, there is defined a
cavity 14 open at one end 16 and closed at the other end by
an integral wall formation 18. With or without annealing, a
force 20 from a die of predetermined shape is subsequently
applied laterally against the outside face of wall 18 until
a reentrant recess of dimension C and diameter B is formed
as illustrated in Fig. 2, while concomitantly forming an
annular rim 21 about the periphery. Preferably, dimension C
provides for a reentrant recess over about 85 Jo 97% of the
internal diameter of peripheral wall 8. After punching
openings 22 end 24 through walls 12 and 18, respectively,
the case is in a completed condition with wall 18 defining
a rear compartment 27 and a front compartment 34. The case
is now ready to receive the operating mechanism and rear
closure as will be described with respect to Fig. 3.
As illustrated in Fig. 3, case 10 houses a gauge
mechanism 25 that includes a Bourbon tube 26 in the rear
compartment 27 for connection to a socket 28 through which
pressure to be measured is introduced as represented by
arrow 29. In response to changing values of pressure 29,
the Bourbon tube functions to drive a pointer 30 on a pointer
shaft 32 opposite dial plate 38 in front compartment 34.
operating mechanism 25 may, for example, be of a type more
completely disclosed in US. patent 4,237,738. A bushing 36
may optionally be provided secured in a press fit within
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center offset 37 of wall 18 for support of the pointer shaft
32 and dial plate 38 in alignment with aperture 24. For
effecting a tight enclosure, aperture flange 32 is welded
at 33 to socket 28.
An annular grooved gasket 40 supporting window 42 is
frictionally inserted in a force fit into compartment 34
about rip 21 to effect the enclosure therefore A suitable
rear closure assembly 44 affording relief in the event of
overpricer within compartment 27 is provided at the rear
of case 10 and may, for example, be of a type disclosed in
co-pending kidney p~tsn' aprlicatioII 449,172~ filed March 8,
19 84 . and entitled "Temperature Compensator for Liquid Filled
Pressure Gauge". As illustrated in Fig. 4, gasket 40 is
further secured by a mechanical force afforded by metallic
trim ring 46.
By the above description there is disclosed a novel
solid front case construction for a pressure gauge having
a front wall fabricated of sheet metal integral with the
annular sidewall. Typical sheet-metal constructions suitable
for these purposes would be of thickness on the order of about
1/2-2 millimeters, and could comprise by way of example
stainless steel, galvanized steel, brass, aluminum, etc.
Being formed in this manner, case fabrication represents the
height of simplicity for forming a solid front gauge case,
and from which it can be appreciated that considerable cost
savings are realized as compared to similar purpose construe-
lions of the prior art.
Since many changes could be made in the above construe-
lion, and many apparently widely different embodiments of
this invention could be made without departing from the scope
thereof, it is intended that all matter contained in the
drawings and specification shall be interpreted as illustra-
live and not in a limiting sense.
