U.S. patent application number 14/566940 was filed with the patent office on 2016-06-16 for projectile with amorphous polymer tip.
This patent application is currently assigned to HORNADY MANUFACTURING COMPANY. The applicant listed for this patent is Hornady Manufacturing Company. Invention is credited to Ryan Michael Damon, David E. Emary.
Application Number | 20160169645 14/566940 |
Document ID | / |
Family ID | 56110850 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160169645 |
Kind Code |
A1 |
Emary; David E. ; et
al. |
June 16, 2016 |
PROJECTILE WITH AMORPHOUS POLYMER TIP
Abstract
Projectiles with amorphous polymer tips have an elongated body,
the body having a forward end, the body having a rear end opposite
the forward end, the body having an intermediate cylindrical
portion between the rear and forward ends, the front end of the
body defining a cavity, a nose element, at least a portion of which
is received in the cavity, wherein the nose element is an elongated
body having opposed ends, and wherein the nose element is polymer
resin having a glass transition point temperature greater than or
equal to 185.degree. C. The nose element may be a polymer resin
that does not have a discrete melting point. The nose element may
be a polymer resin having a glass transition point temperature less
than or equal to 225.degree. C. The nose element may be a polymer
resin having a molding temperature melt point greater than or equal
to 330.degree. C.
Inventors: |
Emary; David E.; (St. Paul,
NE) ; Damon; Ryan Michael; (Grand Island,
NE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hornady Manufacturing Company |
Grand Island |
NE |
US |
|
|
Assignee: |
HORNADY MANUFACTURING
COMPANY
Grand Island
NE
|
Family ID: |
56110850 |
Appl. No.: |
14/566940 |
Filed: |
December 11, 2014 |
Current U.S.
Class: |
102/439 |
Current CPC
Class: |
F42B 12/34 20130101;
F42B 30/02 20130101; F42B 12/74 20130101 |
International
Class: |
F42B 12/74 20060101
F42B012/74 |
Claims
1. A bullet for a centerfire cartridge comprising: a unitary body
formed of a lead alloy surrounded by a copper jacket; the body
having a forward end; the body having a rear end opposite the
forward end; the body having an intermediate cylindrical portion
between the rear and forward ends; the front end of the body
defining a cavity; a nose element, at least a portion of which is
received in the cavity wherein the nose element is an elongated
body having opposed ends; and wherein the nose element is polymer
resin having a glass transition point temperature greater than or
equal to 210.degree. C.
2. The bullet for a centerfire cartridge of claim 1 wherein the
nose element is a polymer resin that does not have a discrete
melting point.
3. (canceled)
4. The bullet for a centerfire cartridge of claim 1 wherein the
nose element is Polyetherimide (PEI).
5. The bullet for a centerfire cartridge of claim 1 wherein the
nose element is Polyphenylsulphone (PPSU).
6. The bullet for a centerfire cartridge of claim 1 wherein the
nose element is a polymer resin having a glass transition point
temperature less than or equal to 225.degree. C.
7. (canceled)
8. The bullet for a centerfire cartridge of claim 1 wherein the
nose element is a polymer resin having a glass transition point
temperature greater than or equal to 225.degree. C.
9. The bullet for a centerfire cartridge of claim 1 wherein the
nose element is a polymer resin having a molding temperature melt
point greater than or equal to 330.degree. C.
10. The bullet for a centerfire cartridge of claim 1 wherein one
end of the nose element has a pointed tip.
11. The bullet for a centerfire cartridge of claim 1 wherein one
end of the nose element is tapered.
12. The bullet for a centerfire cartridge of claim 1 wherein the
portion of the nose element received in the cavity is
cylindrical.
13. The bullet for a centerfire cartridge of claim 1 wherein the
forward end of the body has a tapered surface portion, and wherein
the nose element has an external surface portion extending smoothly
from the tapered surface portion.
14. The bullet for a centerfire cartridge of claim 13 wherein the
tapered surface portion of the body and the external surface
portion of the nose element have a common ogive radius.
15. A bullet for a centerfire cartridge comprising: a unitary body
formed of a lead alloy surrounded by a copper jacket; the body
having a forward end; the body having a rear end opposite the
forward end; the body having an intermediate cylindrical portion
between the rear and forward ends; the front end of the body
defining a cavity; a resilient pointed nose element having a first
portion received in the cavity and a second portion extending from
the forward end of the body; and wherein the nose element is
selected from the group consisting of Polyetherimide (PEI) and
Polyphenylsulphone (PPSU).
16. The bullet for a centerfire cartridge of claim 15 wherein the
second portion of the nose element is tapered.
17. The bullet for a centerfire cartridge of claim 15 wherein the
first portion of the nose element is cylindrical.
18. The bullet for a centerfire cartridge of claim 15 wherein the
cavity is a cylindrical bore.
19. The bullet for a centerfire cartridge of claim 15 wherein the
forward end of the body has a tapered surface portion, and wherein
the second portion of the nose element has an external surface
portion extending smoothly from the tapered surface portion.
20. The bullet for a centerfire cartridge of claim 19 wherein the
tapered surface portion of the body and the external surface
portion of the nose element have a common ogive radius.
21. The bullet for a centerfire cartridge of claim 1 wherein the
body has a diameter of 0.3 inch.
22. The bullet for a centerfire cartridge of claim 1 wherein the
body has a length greater than the nose element.
23. The bullet for a centerfire cartridge of claim 1 wherein the
portion of the nose element which is received in the cavity has a
cylindrical profile.
24. The bullet for a centerfire cartridge of claim 1 wherein the
cavity has a smooth cylindrical profile.
25. The bullet for a centerfire cartridge of claim 1 wherein the
portion of the nose element which is received in the cavity is
entirely encompassed by the body.
26. The bullet for a centerfire cartridge of claim 1 wherein the
nose element is polymer resin having a glass transition point
temperature greater than or equal to 220.degree. C.
Description
FIELD OF THE INVENTION
[0001] This invention relates to firearms ammunition, and more
particularly to projectiles with expanding characteristics.
BACKGROUND OF THE INVENTION
[0002] For long-distance shooting, there is a trade-off between
designing for aerodynamic performance, accuracy and terminal
ballistics. Projectiles that are the most aerodynamic and accurate
tend to be poor terminal performers when hunting game, and
projectiles that expand effectively (especially at slower speeds
after having traveled a great distance) typically lack the
aerodynamic performance desired for hunting game at long
ranges.
[0003] Good aerodynamics, and accuracy are provided by boat-tail
hollow point (BTHP) projectiles that are popular among match
competitors. However, these do not humanely dispatch game animals
in long-range hunting situations. Many hunting projectiles employ
hollow points filled with pointed plastic tips that help to
facilitate expansion and purportedly improve aerodynamics.
[0004] Other types of projectile tips have been employed, such as
inserts formed of metals like aluminum or bronze (as contrasted
with tips formed of the projectile's copper jacket or lead core),
which either fail to effectively expand or not provide adequate
aerodynamics as needed for long range hunting or target shooting.
Furthermore, metal tips suffer substantial economic disadvantages
compared to injection molded polymer tips. Metal tips also require
machining to form a suitable shape to achieve acceptable
aerodynamics, and thus add unacceptably to the cost of a tipped
projectile. Other materials serving as alternatives to polymers are
also prohibitively expensive. These may include ceramics and cast
resins.
[0005] For decades, widespread use of polymer tip projectiles has
been considered optimal and effective technology, with no notable
disadvantages. Polymer tip projectiles offer the advantage of
maintaining the shape of the tip in the magazine box under recoil
and purportedly provide improved downrange ballistics because the
points do not flatten in the magazine like exposed lead tip
projectiles. Typical polymers employed are crystalline polymers
such as Delrin.RTM. and nylon. These polymers have very discrete
melting points of approximately 200.degree. C. and a low glass
transition point of approximately 50.degree. C. The glass
transition point is the temperature at which the polymer
transitions from a hard solid material to a soft rubbery type
material.
[0006] When these crystalline polymers are exposed to temperatures
that are greater than or equal to their glass transition point,
they begin to soften and deform. They continue to soften and deform
as their temperature increases until the temperature reaches their
melt point, where the polymers essentially become liquid and
completely lose their shape. Because of the very low glass
transition point of the crystalline polymers, coupled with their
low melt points, they are unable to withstand high temperatures and
anything but modest velocities in ballistic applications without
losing their shape. However, the melting points of these
crystalline polymers are considered ideal for injection molding, as
the material flows readily into conventional molds that do not
require unusual pre-heating.
[0007] It has been unexpectedly discovered that these conventional
crystalline polymers are impairing long-range effectiveness of
polymer tipped projectiles because they are melting and deforming
because of heating associated with the supersonic airflow around
the projectile. The supersonic airflow heats the projectile's
crystalline polymer tip to a sufficiently elevated temperature that
causes the tip to melt and deform in response to the pressure of
the airflow. Because of the very low glass transition point of the
currently used Delrin.RTM. and nylon polymers, and their
corresponding low melting points, these plastics can only be used
at low velocities without deforming and losing their shape.
[0008] This was initially discovered by measuring the speed of
projectiles over long distances using Doppler radar. Doppler radar
measures the projectile's velocity at all points along the
projectile's path, which in target or hunting applications can be
greater than or equal to 1,000 yards. This research unexpectedly
revealed that the ballistic coefficient, which is calculated from
the radar data, decreased steadily as the projectile travelled
downrange until the velocity dropped below approximately 2,200 fps.
The decrease in ballistic coefficient indicates an increase in drag
for a portion of the projectile's flight. The measurements showed
the ballistic coefficient was degrading after a short amount of
flight time, which depended on the projectile's initial velocity
and drag characteristics. This phenomenon is caused by the
crystalline polymer tip melting or softening, and subsequently
deforming. Instead of a pointed tip, the tip is melting and
ablating in the high temperature supersonic airflow and flattening,
thereby increasing its frontal area as it travels downrange and
causing increased drag. Carefully controlled Doppler radar tests
were done with boat tail hollow point projectiles with precisely
machined noses of increasing meplat or point diameter. All
projectiles were of identical shape other than their nose diameter
and were all fired at the same velocity. Results show that with a
.08 caliber increase in nose diameter, the ballistic coefficient of
the bullet drops 6%. For a .30 caliber bullet, this is
approximately a 0.025'' increase in the nose diameter.
[0009] Current designs of crystalline polymer tips suffer from the
tips melting and flattening above velocities of 2,400 fps because
of aerodynamic heating. The aerodynamic stagnation temperature on
the point of a projectile at 2,400 fps is approximately 300.degree.
C. 2,400 fps is a rather mundane velocity by today's standards and
would be associated with older cartridge designs intended for lever
action rifles. Modern hunting and target rifle cartridge designs
produce velocities, depending on specific cartridge and projectile
weights, of approximately 2,800 to 3,200 fps. Varmint cartridge
designs can produce velocities upwards of 4,000 fps. At 3,000 fps,
the aerodynamic stagnation temperature on the tip of the projectile
is approximately 450.degree. C. By today's standards, the vast
majority of projectile velocities would fall within the 2,800 to
3,200 fps range. In this velocity range, the peak stagnation
temperature is two to two and one-half times the melting point of
currently used crystalline polymers for projectile tips.
[0010] Radar testing has shown that it takes approximately 0.05 to
0.20 seconds, depending on the initial projectile velocity and the
projectile's drag for enough heat transfer to take place to cause
the crystalline polymer tips to begin to melt and deform. This
corresponds to distances downrange of approximately 50 to 200
yards. The melting of the tips causes the tip diameter, or meplat
diameter, to become larger, which increases the aerodynamic drag on
the projectile. The tip deformation is manifested in the radar data
as an increase in the drag coefficient of the projectile at high
velocities, which is then maintained for the remainder of the
projectile's drag curve.
[0011] The crystalline polymer tip distortion begins to occur at
flight distances of 50-200 yards because of the time required for
heat to transfer to the tip. Data shows this distortion of the tip
continues for up to 500-600 yards, depending on the projectile's
aerodynamic properties. Typically, small arms have used chronograph
screens at the muzzle and at most two other points downrange,
typically 100 and 200 yards, to measure the approximate drag
characteristics of a projectile. This limited data at short ranges
has masked the issue of melting crystalline polymer tipped
projectiles because it is within the window of time/distance for
the effect to begin to become significant and suffer from the
limitations of only two data points versus hundreds obtained via
Doppler radar. The use of only three chronograph screens does not
provide the resolution necessary to see the problem, and uses a
very large average, which further masks the problem. The challenges
of measuring downrange performance at great distances (shooting
through a chronograph target) have further concealed the phenomenon
of crystalline polymer tip melting and deformation. This phenomenon
has been hypothesized, but no definitive work has ever been done
previously to establish the heat transfer rate/times that occur in
order to establish that crystalline polymer tip melting and
deformation has a significant effect on long range projectile
performance.
[0012] The crystalline polymer tip melting effect has been further
evidenced by use of thermal imaging systems that show projectiles
beginning to "glow" in infrared wavelengths after flying increasing
distances, showing the heating effects. Verification has further
been provided by firing crystalline polymer tipped projectiles into
gelatin at long ranges (600 yards), revealing polymer tips that are
distorted and exhibit evidence of heating by changes in color,
material properties and shape.
[0013] With the revelation of crystalline polymer tip melting
provided by research and analysis, a need exists for a new and
improved projectile tip that withstands the sustained high
temperatures that occur over long-range projectile flight at high
speeds. In this regard, the various embodiments of the present
invention substantially fulfill at least most of these needs. In
this respect, the projectile with amorphous polymer tip according
to the present invention substantially departs from the
conventional concepts and designs of the prior art, and in doing so
provides an apparatus primarily developed for the purpose of
providing a projectile with a tip that maintains a consistently
higher ballistic coefficient/lower drag, during long-range
projectile flight at high speeds than projectiles with conventional
crystalline polymer tips.
SUMMARY OF THE INVENTION
[0014] The present invention provides an improved cartridge and
bullet with amorphous polymer tip, and overcomes the
above-mentioned disadvantages and drawbacks of the prior art. As
such, the general purpose of the present invention, which will be
described subsequently in greater detail, is to provide an improved
projectile with amorphous polymer tip that has all the advantages
of the prior art mentioned above with significantly improved long
range aerodynamic drag with resulting superior long range
ballistics.
[0015] To attain this, the preferred embodiment of the present
invention essentially comprises the use of amorphous polymers, such
as Polysulphone (PSF), Polyetherimide (PEI), and Polyphenylsulphone
(PPSU), which are very high temperature, very high glass transition
point and no discrete melt point polymers as the tip material for
polymer tipped projectiles for both hunting and target shooting
applications. The preferred embodiment of the present invention
also essentially comprises an elongated body, the body having a
forward end, the body having a rear end opposite the forward end,
the body having an intermediate cylindrical portion between the
rear and forward ends, the front end of the body defining a cavity,
a nose element, at least a portion of which is received in the
cavity, wherein the nose element is an elongated body having
opposed ends, and wherein the nose element is polymer resin having
a glass transition point temperature greater than or equal to
185.degree. C. The nose element may be a polymer resin that does
not have a discrete melting point. The nose element may be a
polymer resin having a glass transition point temperature less than
or equal to 225.degree. C. The nose element may be a polymer resin
having a molding temperature melt point greater than or equal to
330.degree. C. There are, of course, additional features of the
invention that will be described hereinafter and which will form
the subject matter of the claims attached.
[0016] There has thus been outlined, rather broadly, the more
important features of the invention in order that the detailed
description thereof that follows may be better understood and in
order that the present contribution to the art may be better
appreciated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a sectional side view of a projectile according to
a preferred embodiment of the invention. This is the general design
and construction for a copper jacketed, lead core, polymer tipped
projectile. This projectile is a .30 caliber 208 grain projectile
used for long range target shooting.
[0018] FIG. 2 is a graph illustrating the results of Doppler radar
tests utilizing identical projectiles with increasing nose/meplat
diameters and the effect on the G1 Ballistic coefficient. Results
are displayed in dimensionless bullet calibers (diameter).
[0019] FIG. 3 is a graph illustrating the drag coefficient versus
Mach number, as determined from Doppler radar, for the projectile
of FIG. 1 with a crystalline polymer tip of Delrin.RTM. and an
amorphous polymer tip of Polyetherimide (PEI). Both projectiles
were identical and fired at the same velocity, under the same
atmospheric conditions, the only difference being the material the
tips are made from. As can be seen from the graph, the two
projectiles start with virtually identical drag coefficients, but
the projectile with the Delrin.RTM. tip rapidly climbs above the
drag of the projectile with the PEI tip, and maintains higher drag
throughout the entire velocity range.
[0020] FIG. 4 is a graph illustrating the drag coefficient versus
Mach number, as determined from Doppler radar, of a .30 caliber 180
grain projectile, commonly used as a long range hunting bullet,
with a crystalline polymer tip of Delrin.RTM. and an amorphous
polymer tip of Polyetherimide (PEI). Both projectiles were
identical and fired at the same velocity, under the same
atmospheric conditions, the only difference being the material the
tips are made from. As can be seen from the graph, the two
projectiles start with virtually identical drag coefficients, but
the projectile with the Delrin.RTM. tip rapidly climbs above the
drag of the projectile with the PEI tip, and maintains higher drag
throughout the entire velocity range.
[0021] FIG. 5 is a graph illustrating the drag coefficient versus
Mach number, as determined from Doppler radar, of a .30 caliber 155
grain projectile, commonly used for 1,000 yard target competition,
with a crystalline polymer tip of Delrin.RTM. and an amorphous
polymer tip of Polyetherimide (PEI). Both projectiles were
identical and fired at the same velocity, under the same
atmospheric conditions, the only difference being the material the
tips are made from. As can be seen from the graph, the two
projectiles start with virtually identical drag coefficients, but
the projectile with the Delrin.RTM. tip rapidly climbs above the
drag of the projectile with the PEI tip, and maintains higher drag
throughout the entire velocity range.
[0022] The same reference numerals refer to the same parts
throughout the various figures.
DESCRIPTION OF THE CURRENT EMBODIMENT
[0023] An embodiment of the projectile with amorphous plastic tip
of the present invention is shown and generally designated by the
reference numeral 10.
[0024] FIG. 1 illustrates the improved projectile 10 of the present
invention. More particularly, the projectile is a generally
cylindrical body, symmetrical in rotation about an axis 12, with a
rear end 40 and a forward tip 16. The projectile has an exterior
surface shaped as follows: a rear portion 18 has a tapered
frustoconical "boat tail" surface; a cylindrical intermediate
portion 20 continues forward from the rear portion with a straight
cylindrical side wall. Continuing, a forward ogive surface portion
22 has a gentle curve toward a meplat portion 24 at the tip. The
meplat is a small diameter spherical portion. The ogive has a
larger radius (as taken in a plane including the bullet's axis, as
illustrated) than the intermediate section's diameter (taken in
section across the axis), and also a much larger radius than that
of the meplat, as will be quantified below.
[0025] The projectile 10 is formed of a copper jacket 26 having a
base portion 28, with side walls 30 extending forward to a rim 32
at a forward position on the ogive section, spaced apart from the
meplat. The jacket closely surrounds a lead core 34 that defines a
cylindrical cavity 36 in a forward face 38 of the core. The forward
face is rearward of the jacket edge 32 in this particular
embodiment, and the cavity is concentric with the axis 36.
[0026] The projectile tip is formed by a nose element 40 having a
first shank portion 42 and a second tapered portion 44 formed as a
unitary body of the same material. The shank portion is a
cylindrical portion having a diameter equal to the diameter of the
jacket rim, and which is closely received in the cavity of the
core. The second portion has a larger diameter than the shank at
its base adjacent to the shank. The base of the second portion
forms a shoulder 46, and tapers to form the tip. The jacket rim
tightly grips the base of the shank at the shoulder, to secure the
nose into the projectile body.
[0027] The nose element is formed of suitable amorphous plastic
resins, such as Polysulphone (PSF), Polyetherimide (PEI), and
Polyphenylsulphone (PPSU), which exhibit high glass transition
point temperatures greater than or equal to 185.degree. C., and
high molding temperature melt points, above 330.degree. C.
Specifically, PSF has a glass transition point of 185.degree. C.,
and PEI and PPSU are progressively higher, and therefore even more
suitable for use in the current invention, with glass transition
points of 220.degree. C. and 225.degree. C., respectively. In
comparison, the best performing crystalline polymer used in
conventional nose elements is nylon 6-6, which has a glass
transition point of only 50.degree. C. With these amorphous
polymers, the velocities at which tip aerodynamic heating
deformation takes place for a polymer tipped projectile can be
extended from 2,400 fps associated with conventional crystalline
polymer tips up into the 3,100 to 3,200 fps range of velocities.
Amorphous polymers are ideal to solve this problem because of their
combination of a high glass transition temperature along with the
absence of a discrete melt point. Amorphous polymers typically
begin to melt at temperatures between 350 to 425.degree. C.,
depending on the polymer and the conditions. These polymers will
withstand very high temperatures compared to conventional
crystalline polymers, and only soften without melting and
completely losing their shape.
[0028] Up to this point, these types of high temperature amorphous
polymers have not been used for small arms projectile tips because
they are a considerably more expensive polymer resin, require more
handling and preparation prior to molding, and require considerably
more effort to mold. As a result, parts produced from these types
of polymer resins are more expensive than conventional crystalline
polymer projectile tips. High temperature amorphous polymers
require drying prior to molding, which the currently used
crystalline polymers do not. Amorphous polymers also require
specially designed molds that require heated plastic runner systems
to preheat the resin prior to molding. These "hot runner" systems
run at temperatures of up to 200.degree. C. The "hot runner"
systems are not required to mold crystalline polymer resins.
[0029] Despite these higher temperature and more complex equipment
and procedural requirements for fabrication, use of high
temperature amorphous polymers is by far a superior solution to the
problem of crystalline polymer projectile tips melting during
long-range projectile flight at high speeds. The use of metal tips
has been largely replaced by polymers because of the very high
level of manufacturing difficulty and cost associated with small
metal tips. In addition, metal tips cannot be formed into the
shapes required for mass production of small arms projectiles
without the cost becoming so high that the tip is more expensive
than the rest of the projectile.
TABLE-US-00001 TABLE 1 Hornady .RTM. 30 Caliber 155 Amax Velocity
vs. Distance 30 155 Amax - Retained velocity PEI Delrin .RTM. Range
(yds.) Velocity (fps) Velocity (fps) 0 2895 2895 100 2723 2711 200
2543 2527 300 2367 2346 400 2196 2168 500 2030 1996 600 1868 1830
700 1712 1669 800 1561 1515 900 1413 1369 1000 1272 1228 Wind drift
8.8 9.3 @ 1000 yds. (minute of angle) Elevation @ 31.1 32.1 1000
yds. (minute of angle)
[0030] Table 1 shows the results of experimentation providing the
retained velocity vs. distance for Hornady.RTM. 30 caliber 155 Amax
bullets with different tip material compositions. Table 1
illustrates the downrange ballistic differences for the .30 caliber
155 grain projectiles used to generate the drag coefficient data in
FIG. 4. Velocity distance data is taken directly from Doppler
radar, and the wind drift and elevation values are calculated using
the FIG. 4 Doppler radar drag data. The amorphous polymer-tipped
bullet of the current invention exits the muzzle of the rifle with
identical retained velocity as the conventional Delrin.RTM.
polymer-tipped bullet. However, at a range of 100 yards, the
amorphous polymer-tipped bullet of the current invention already
shows a higher retained velocity of 12 fps relative to Delrin.RTM..
As the range increases, the retained velocity of the amorphous
polymer-tipped bullet of the current invention increases compared
to the retained velocity of Delrin.RTM.. At 800 yards, the
amorphous polymer-tipped bullet of the current invention has a
retained velocity of 46 fps compared to Delrin.RTM.. The retained
velocity of the amorphous polymer-tipped bullet of the current
invention continues to compare favorably to the retained velocity
of the Delrin.RTM.-tipped bullet at 900 and 1,000 yards, with a
difference of 44 fps.
[0031] While a current embodiment of a projectile with amorphous
plastic tip has been described in detail, it should be apparent
that modifications and variations thereto are possible, all of
which fall within the true spirit and scope of the invention. With
respect to the above description then, it is to be realized that
the optimum dimensional relationships for the parts of the
invention, to include variations in size, materials, shape, form,
function and manner of operation, assembly and use, are deemed
readily apparent and obvious to one skilled in the art, and all
equivalent relationships to those illustrated in the drawings and
described in the specification are intended to be encompassed by
the present invention.
[0032] Therefore, the foregoing is considered as illustrative only
of the principles of the invention. Further, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and operation shown and described, and accordingly,
all suitable modifications and equivalents may be resorted to,
falling within the scope of the invention.
* * * * *