U.S. patent number 3,633,580 [Application Number 04/870,884] was granted by the patent office on 1972-01-11 for hypodermic needle.
This patent grant is currently assigned to Knox Laboratories, Inc.. Invention is credited to James J. Knox.
United States Patent |
3,633,580 |
Knox |
January 11, 1972 |
HYPODERMIC NEEDLE
Abstract
Hypodermic needlepoints are manufactured from tubular members by
deforming top and bottom wall portions from opposite sides of the
tubular member by gradually and progressively pressing generally
inwardly against the top and bottom wall portions with dies os as
to cause the top and bottom wall portions to gradually slop
together and meet in an area where they intimately contact each
other, and removing some of the opposite sidewall portions to
create side surfaces which slope together from the unsloped portion
of the tubular member to where they intersect in a cutting point in
the area where the top and bottom wall portions are in intimate
contact. The needlepoint consists of a regular quadrilateral
pyramid having substantially identical triangular faces. Two
opposing faces have substantially elliptical or pear-shaped
openings therethrough providing communication between the hollow
interior of the needle and the exterior of the needle adjacent to
the apex of the pyramid.
Inventors: |
Knox; James J. (Avenel,
NJ) |
Assignee: |
Knox Laboratories, Inc.
(Rahway, NJ)
|
Family
ID: |
27086201 |
Appl.
No.: |
04/870,884 |
Filed: |
September 29, 1969 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
610152 |
Jan 18, 1967 |
3540112 |
Jan 17, 1970 |
|
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Current U.S.
Class: |
604/274;
72/470 |
Current CPC
Class: |
A61M
5/3286 (20130101); A61M 2205/195 (20130101) |
Current International
Class: |
A61M
5/32 (20060101); A61m 005/00 () |
Field of
Search: |
;128/221,218N,218NV,347
;12/470 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Reich; Joseph S.
Parent Case Text
This application is a division of copending application Ser. No.
610,152 filed Jan. 18, 1967 now U.S. Pat. No. 3,540,112 issued Nov.
17, 1970.
Claims
I claim:
1. A needle for a hypodermic syringe including a hollow elongated
member having one end adapted for connection to said syringe, said
one end being open for communication with said syringe, said needle
having its other end terminating in a portion having four
substantially planar surfaces arranged in he form of a pyramid, the
apex thereof being pointed, closed and forming said other end, two
opposing faces of said pyramid having confronting apertures
therethrough providing communication with he hollow interior of the
needle and the exterior thereof adjacent said other end.
2. The article of claim 1 in which
a. the base portion of said pyramid is substantially square and
b. said pyramid is substantially equilateral.
3. The article of claim 2 in which
a. the needle including a substantially cylindrical shaft, and in
which
b. there is a cutting edge at the intersection of each of the
planar surfaces, which surfaces intersect at generally right
angles, and in which
c. said cutting edges extend from a front cutting point at said
other end of the needle backwardly and radially outwardly toward
the shaft, said edges being adapted to move apart flesh, muscle,
etc., toward and over the full diameter of the shaft by reason of
their being formed by and between flat side surfaces meeting at
generally more than acute angles.
4. The article of claim 1 in which each aperture is substantially
completely surrounded by a flat wedging and supporting surface that
evenly and uniformly displaces skin, flesh, etc., outwardly and
over the full body of its related portion of the needle and past a
heel portion of the aperture, which heel portion is contained in
the plane of the wedging and supporting surface.
5. An improved hypodermic syringe needle comprising
a. hollow tubular portion and a point, said point
i. having four inclined substantially planar surfaces disposed at
substantially right angles one to another,
ii. each of said surfaces extending generally from the outer
circumference of the hollow tubular portion inward on an incline to
the axis of the tubular portion,
iii. each of said surfaces meeting those adjacent to it along a
sharp line of contact,
iv. each of at least one pair of said surfaces, the pair being any
two surfaces opposite to one another, having an aperture
therethrough communicating with the hollow bore of the hollow
tubular portion.
Description
This invention relates to the manufacture of hypodermic needles,
and more particularly to a hypodermic needlepoint which may be
produced on a mass production scale at low cost.
The hypodermic needle which is today in general use throughout the
country by hospitals, clinics, and private medical doctors is known
to have serious disadvantages and even defects. Nevertheless, it
remains in widespread use because the various constructions which
have been suggested to eliminate the problems have either failed or
had serious disadvantages of their own or, what is perhaps more
important, the few past suggestions which have held out some
theoretical promise of solving the past problems have simply not
been practical; no one has been able to manufacture them on a large
or economical scale so as to make feasible their general use.
There are many situations in which it is preferred to use a needle
only once and then discard it to prevent any risk of
cross-infection, and the problem of providing a suitable economical
needle for this market is particularly difficult.
The conventional needle-not the theoretical best known needle (some
of which are discussed hereinafter), but the best practical needle
design and thus the one in general use-and also the improvements
achieved by the present invention are described with reference to
the following figures in which:
FIGS. 1-3 show a conventional needle in top, side and end sectional
views respectively.
FIG. 4 illustrates the veering which may be experienced by needles
with conventional points, and FIG. 5 diagrammatically shows the
forces which cause veering.
FIG. 6 shows a tube for manufacture into a syringe needle according
to the present invention.
FIGS. 7-12 show side sectional views of the progressive forming
according to the present invention.
FIG. 13 depicts the dies being used to final shape the tube
throughout the area in which the point will subsequently be
formed.
FIG. 14 shows a top view of the tube after being shaped by the
dies, the side flair being exaggerated for clarity.
FIG. 15 shows the shaped tube after being cut to a single needle
length, and showing the portions marked for grinding.
FIG. 16 shows a side view of the needlepoint after side and top
grinding.
FIG. 17 shows an end section through the point of FIG. 16.
FIG. 18 shows a vertical longitudinal section through the
point.
FIG. 19 is a top partial sectional view depicting the improved
needle being inserted in flesh.
FIG. 20 is an end sectional view taken on line 20-20 of FIG.
19.
FIG. 21 is a side partial sectional view depicting the improved
needle being inserted in flesh.
FIG. 22 shows the "cut" made by a conventional needle passed
vertically into skin and flesh with the core not completely cut
off.
FIG. 23 shows the cut made by the improved needle of the present
invention.
FIG. 24 shows a partial perspective view of a vibrating long die
apparatus for forming needle tubing according to the present
invention.
FIG. 25 shows a partial cross-sectional view through the long dies
of FIG. 24.
Conventional needles are formed by taking a hollow tube 1 and
cutting or grinding one end at an angle oblique to the longitudinal
axis of the tube as shown in FIGS. 1 and 2. The point 2 thus formed
may then be finished by grinding and polishing. This results in an
elliptical opening in the plane of the cut as shown at 3, and a
circular opening as viewed and or as shown in FIG. 3. It is through
this opening that the fluid passes into the body.
The needle formed in this way can be manufactured in quantity but
it has many defects. Some of the more important defects may be
designated coring, tearing, veering, and dispersion, which are
discussed below. The overall problem, of course, is to eliminate or
minimize all these problems with a needle that can be manufactured
in quantity at reasonable cost.
CORING
First, the conventional needle tends to "core." That is, when the
tubular needle is pushed endwise through human flesh, see the end
partial sectional view 3, the edges 4, 5 of the tube 1 tend to cut
out a core of flesh and this is particularly true of the following
edge of heel portion 5 of the opening 3 of the needlepoint, which
heel will catch, scrape, and tear the skin in its path. An example
of coring is shown in FIG. 22, with the cut 41 stopped before the
core 42 is completely cut. It should be understood that coring is
not inevitable, and that depending on the variables of insertion,
e.g., the condition of the flesh, speed and angle of insertion,
sharpness of the heel of the needle, and the exact shape of its
opening, the core may not be completely cut but may instead be
stretched and torn about the needle heel. The skin and flesh are
either cored, on the one hand, or pulled and torn on the other, for
if the cutting edge of the conventional needle is completely
sharpened to cut all around so as to permit the full needle
diameter to pass without stretching and tearing, then a core is
cut, and if the heel of the edge is left dull, then there is
tearing. It should be further understood that coring is not only
painful, but dangerous since the core may inadvertently be injected
into the vein along with the medication.
The coring problem is also present when the tubular needle is
pushed endwise through the soft sealing stopper of a bottle of
medicine in order to fill the syringe to which the needle is
attached. Because of coring or the scraping of the heel edge of the
needle, a portion of the rubber or synthetic stopper is sometimes
cut off and may fall into the bottle thus contaminating the rest of
the contents or, perhaps even worse, may be withdrawn up through
the needle and into the syringe where, if it is unnoticed, it will
then be injected into the patient, along with the medicine.
Considerable effort has been expended to devise methods of grinding
of surfaces on the conventional syringe needle that will alleviate
the coring problem, see for example, the patent to G. W. Jacoby,
Jr. U.S. Pat. No. 2,711,733. The difficulty with grinding surfaces
such as taught by Jacoby, is that, first, while it may somewhat
alleviate the coring (and tearing) problem as compared to the use
of a needle without such grinding of surfaces, it does not change
the basic widespread cutting surfaces surrounding the opening of
the tubular needle which are primarily responsible for the problem.
Second, the grinding procedure is relatively complicated, the
needle being rotated during the grinding and it being a requirement
that the needle be accurately positioned if the ground surfaces are
to be properly located. While such grinding is possible in
manufacture, it is not always done precisely as will be appreciated
when it is understood that the surfaces being ground on the end of
the syringe needle are very small and, for the common sizes, barely
visible to the naked eye. Moreover, it is virtually impossible for
such needles as are reused to be resharpened with the facilities
and personnel available in doctors' offices and the typical
hospital. This results in the use of dull needles with considerable
tearing of flesh, and pain.
R. L. Huber, U.S. Pat. No. 2,409,979 attempted to solve the problem
by taking a conventional oblique-faced needle and bending it at the
point where the open face ended so that the opening would lie on a
plane parallel to the longitudinal axis of the tube even with the
body of the tube. Thus there would be no exposed heel for the skin
to catch on and thus no coring. Advantages of the construction are
described in Column 3, lines 34-58. But the bending of the point
made the directional qualities of the needle poorer than a
conventional needle. The inventor himself recognized this and in R.
L. Huber, U.S. Pat. Nos. 2,717,599 and 2,717,600 admitted the
problem see especially column 1, and tried to remedy it by
providing for a lesser bending of the tip. But the resultant
improvement in directional qualities from this change resulted in
an increase in coring and necessitated the extra manufacturing step
of rounding the top edge 18 of the recess to lessen the coring. The
end result was a poor compromise between directional qualities and
coring with increased difficulty and cost of manufacture.
An extreme solution has been an attempt to remove the opening
completely during penetration and thus eliminate coring. This is
taught by J. C. Bamford, Jr. et al., U.S. Pat. No. 2,623,520.
Bamford in column 1, lines 13-19, refers to the practice of
eliminating coring by placing a solid rod through the bore of a
conventional needle, and grinding the end of the rod so it just
fills and is flush with the opening of the bore of the needle as it
opens at the point. This rod or stylet is placed in the needle and
it and the needle are inserted together. When the needle is in
place, the stylet is removed and the injection may take place. As a
practical matter the ordinarily used needles are too small to be
conveniently fitted with stylets and, even with larger sizes, the
stylet procedure is obviously cumbersome, the stylet having to be
removed and the syringe then connected to the needle while it is in
the flesh. Bamford achieved a centrally disposed point only by
having a centrally disposed stylet with a point thereon and, among
other disadvantages, this procedure keeps and requires the
bothersome stylet procedure and, in addition, the lack of any
cutting surfaces along the needle results in the tearing of the
flesh when it is inserted.
Various complex needle constructions have also been suggested to
solve the problem, see for example, D. A. Hamilton, U.S. Pat. No.
2,989,053, C. B. Dolge, U.S. Pat. No. 648,858, and R. D. Hanson,
U.S. Pat. No. 2,634,726. These constructions, however, pose
sufficiently difficult and expensive problems in manufacture that
they are not practical for general hypodermic syringe needle use
and, in addition, are not as desirable as the needle taught
herein.
TEARING
The conventional syringe needle also tends to tear the flesh upon
insertion rather than cutting it evenly which would be desirable
since a clean cutting point renders the syringe needle easier to
insert and thus easier to control, it causes less pain to the
patient, and causes a minimum of bruising and damage to the flesh
so that the wound heals faster.
The conventional needlepoint tears partly because of the
wide-spaced edges whose surfaces must be shaped primarily in a
effort to reduce coring and only secondarily shaped to cut.
Conventional needles also tear because the edges are formed by
grinding curved surfaces on the very small point, and it is
difficult to hold to the precise standards which are desirable in
mass production, and almost impossible for such surfaces to be
sharpened under field conditions.
Parenthetically, work has been undertaken to devise a needlepoint
which can be more easily ground and sharpened and which has
sufficient inherent sharpness to the cutting edge so that even if
the edges should be slightly dulled, the overall shape of the
surface adjacent the edge would tend to cut rather than tear the
flesh, see B. E. Baldwin et al., U.S. Pat. No. 3,090,384. Such
needles as have been suggested, however, even though their cross
sections are triangular rather than elliptical, are still formed by
an oblique cut leaving the standard oblique face exposed with its
inherent coring, directional and dispersion problems.
It should further be understood that in the conventional syringe
needlepoint, there are only two cutting edges, and that it is
difficult to grind these for their full length without unduly
weakening the needlepoint and/or contributing to a sharp heel
surface that would increase coring. In fact, it is a frequent
practice to grind and sharpen only about the first half of the
conventional needlepoint, i.e., beginning at the point and
extending back but not past the area where the opening begins to
close inward again, although the diameter and cross section of the
needle itself are not yet full size at this location and upon
insertion the needle is still expanding in its passage through skin
and flesh and although cutting relief would obviously help. But as
already mentioned, this cutting relief can simply not be feasibly
provided for needles of conventional design.
VEERING
A third problem is to insure that the needle hits the desired
target within the body. The face of the conventional needlepoint of
FIG. 1 is an oblique plane which culminates in a tip 6 located at
the side of the needle tube 1 rather than in the center. As the tip
is pushed through flesh, the needle tends to follow a path parallel
to the oblique surface rather than in the direction at which it
started its entry. In other words, the surfaces about the opening
at the point are like inclined planes and these planes deflect the
needles, especially relatively long and slender needles, as they
are shoved through the flesh and muscle. The deflection is
generally illustrated in FIG. 4 described hereinafter, with the
dotted line showing the position of the needle as it appears to the
physician and the solid line showing the actual position of the
needle in the flesh. FIG. 5 shows in detail the approximate
deflection for flexible needles in firm flesh. The line 8
represents the plane of the oblique surface of the point which
surrounds the opening of the tubular needle 1. The line 9 indicates
the plan of the tubular needle itself, and the apparent direction
of the needle to a physician guiding its insertion. The line 10
indicates the approximate path which the needlepoint will tend to
follow except as it is restrained by the rigidity of the needle
body. The veering experienced by longer needles causes pain and
tissue damage as the flesh is caused to bend the needle. It may
also cause the point of the needle to miss the spot to which the
physician wishes to apply medication, as for example, when the
longer needles are caused to administer cortisone to arthritic
patients. Even where the mislocation of the point is detected by
the skilled physician, he must retract the needle and reinsert it
with the consequent further tissue damage of a second or even third
try. If the mislocation of the needlepoint is not detected, the
medication is consequently misdirected.
Attempts to improve the directional properties of a needle by
eliminating the oblique plane has resulted in points of complex
construction and of other difficulties, see for example, R. L.
Huber, U.S. Pat. Nos. 2,717,599 and 2,717,600, J. C. Bamford, Jr.
et al., U.S. Pat. No. 2,623,520, and D. A. Hamilton, U.S. Pat. No.
2,989,053.
Recent work has suggested that the conventional point may be used
without excessive veering if specially shaped tubing or
hollow-channel member is used to forcibly restrain the needle from
bending. For example, S. J. Everett, U.S. Pat. No. 2,830,587,
teaches in FIGS. 12 and 13 the use of an elliptical tube for the
needle and it is explained in column 1, lines 64-71 that the shaft
is more resistant to bending in plane of the tip than in the plane
containing the minor axis.
DISPERSION
A further difficulty with the conventional syringe needle is that
the medication may be injected through only one opening and thus in
only one direction. Moreover, the single opening may be partially
obstructed, as if it should by happenstance lie adjacent a vein
wall. In many applications, the medication should be injected
through two or more openings on at least two sides of the needle,
either to provide a broader area for the diffusion of the
medication into the vein, muscle, etc., or to maximize the chance
that at least one side will be free of any obstructions, and in
both cases to thereby reduce the back pressure and pain. Past
attempts to provide such openings have been either complex or
otherwise impractical. For example, T. H. Gewecke, U.S. Pat. No.
2,862,495 attempted to reduce the extra manufacturing operations
usually associated with additional openings by using a swaging
process. However, this necessitates use of a softer metal with
resultant loss of strength and sharpness attainable, and his needle
further lacks any cutting edges.
THE PRESENT INVENTION
According to the present invention needles are manufactured from
conventional tubular stock 10 such as is illustrated in FIG. 6; for
example, full hard stainless-type 304 austenitic chromium-nickel
stainless steel tubing, or almost full hard tubing, that is, tubing
cold worked a little less than is typical for full hard syringe
needle tubing. It should be understood that it would be possible to
use fully annealed tubing, and indeed the forming of the
needlepoint would be rendered easier thereby. But by the present
invention it is possible to use even full hard tubing and this is
preferable for rigidity and strength, for retaining the sharpness
of the ground point, and to facilitate the initial grinding of the
point with a minimum burr.
The first step is to shape the stock 1 as shown generally in FIGS.
7-10.
The shaping of full hard syringe tubing should be performed with
care lest the tubing crack. It has been found that the particular
orientation of the tubing about its longitudinal axis with respect
to the dies may have an effect on the likelihood of cracking, and
this is now though to be because when a hardened syringe tubing is
formed of flat sheet, there is a seam formed. In subsequent
operations and drawing this seam becomes invisible to the unaided
eye, but its varying orientation with respect to forming dies used
as taught herein causes a varying tolerance to cracking. Since it
is not convenient to detect and control the orientation of the
"seam," the forming taught herein is designed to work the tubing
without cracking regardless of its orientation.
The presently preferred procedure is to first collapse or deform
the tubing 10 with two hard round dies 35 of about 1/4 inch in
diameter aligned opposite to one another on opposite sides of the
tubing as shown in FIG. 7; to then further collapse the tubing 10
with two dies 36 of about 5/16 inch in diameter as shown in FIG. 8;
to then further collapse the tubing 10 with two dies 37 of about
5/8 inch in diameter as shown in FIG. 9; to then further collapse
the tubing 10 with two dies 38 of about 1-1/8 inch in diameter as
shown in FIG. 10; to then further collapse the tubing 10 with two
dies 39 of about 1-3/4 inch in diameter as shown in FIG. 11, and to
then further collapse the tubing 10 with two dies 40 of about 2-1/4
inch in diameter as shown in FIG. 12. It is to be understood that
as used herein, the terms "collapse" or "deforming" shall both be
intended to mean to alter the shape of a material by applying a
stress thereon.
Alternatively, the tubing may be shaped by vibrating dies to flow
the material into the collapsed shape, and this may be by small
dies reciprocated over and under the tubing to gradually shape it
or even the final dies, while vibrating, could be gradually closed
upon the tubing. See pages 13-14, infra.
This shaping may be made in the center of a piece of stock long
enough so that two finished needles will be produced therefrom as
illustrated and presently preferred or the shaping may be performed
at the end of a piece of stock for one needle.
The final shaping of the tubing is preferably accomplished by dies
44. These dies may be shaped as shown in FIG. 13.
The flat angular dies 44 should be provided with press means (not
shown) so that opposite sides, for convenience of reference "top"
45 and "bottom" 46 sides, of the tubing 10 are pressed into
intimate interrelation. While the other pairs of dies must also be
provided with means for forcing the members of a pair toward each
other to collapse the tubing, it has been found best to only just
collapse the tubing, with their dies, and to then force the sides
together with substantial pressure by the final flat angular dies.
The intimate interrelation of the flattened sides promotes, among
other things, a weld over the full area of the point and not just
in one spot. Also, this flat area of intimate relationship may, for
example, extend along the axis of the hollow member a distance of
about 10 to 30 percent of the distance of the finished sloping
portion of the needle, after it has been ground to a cutting edge
or point.
In particular and according to an alternative further teaching of
the invention, the syringe needle tubing may be shaped by the
following method and technique. By this method, the tubing may be
continuously formed by being passed through and between oscillating
or vibrating long dies. This is in place of a step-by-step
progressive forming of the tubing.
Referring to FIGS. 24 and 25, the two long dies are positioned one
above the other. They are spaced-apart on one end by an amount
sufficient to receive and guide a transversely disposed length of
needle tubing for movement through and between them. The working
faces of the two dies gradually slope together so that at the rear
or exit end they are separated by a distance corresponding to the
thickness of fully collapsed tubing or even by a slightly lesser
distance so as to insure that the tubing will be fully collapsed
and the opposite tubing wall portions pressed into intimate
interrelation contact with each other. It should be understood that
for the opposed die faces which re curved across the width of the
dies, the spacing distances just mentioned refer to the spacing
between the closest portions of the opposite dies at any given
location along their lengths.
In one embodiment the opposed working surfaces of the long dies are
curved generally as the working surfaces on the successively used
hard round dies are curved; the opposed portions of the long dies
having the same curvatures. In this embodiment, the dies are
oscillated about an axis which may e generally parallel to the
working surface on the dies or to the path of the tubing between
the dies. It is presently thought desirable for the radius of
oscillation or vibration to be equal to or longer than the radius
of curvature for the working face. The metal of the tubing walls is
flowed from its initial round configuration when inserted at the
front opening of the dies to a collapsed configuration when it
leaves the dies, much like that achieved by the step-by-step
forming discussed above. If the wiping action of the oscillating
dies is not sufficient to create a sufficient flat area throughout
which the opposite wall portions are in contact, the tubing may be
moved slightly back and forth endwise while it is being passed
through the dies so as to subject some small length of the tubing
may be moved slightly back and forth endwise while it is being
passed through the dies so as to subject some small length of the
tubing to the action of the dies in the area of their least
separation. The tubing may be moved through the dies by hand, or by
traveling belt or other conventional methods and the dies may be
reciprocated or vibrated by electromechanical or ultrasonic
apparatus as will be apparent to those skilled in these arts in
view of this disclosure.
FIG. 24 schematically shows long dies 60, spaced apart at a forward
end 61 and gradually sloping together at an exit or rear end 62.
Lengths of tubing 10 are shown being passed through and between the
dies.
FIG. 25 shows a cross-sectional view of the dies with a partially
formed length of tubing 10 therebetween. The mounts and powering
apparatus for the dies are not shown.
In another specific embodiment, the long dies are positioned and
spaced as described just above but they are adapted for
reciprocation to and from each other. In this embodiment the
working faces of the dies at the front end desirably are shaped to
correspond to the working surfaces on the hard round dies 35
described above, and thereupon the shaping of the working surfaces
continues so that at the rear portion of the long dies the working
surfaces have taken on the general configuration of the dies 44
described above. By moving syringe needle tubing through these dies
they will experience a continuous progressive shaping from an
original round configuration progressive shaping from an original
round configuration to the configuration indicated in FIG. 14. The
position of the long dies according to this embodiment will be
readily apparent in view of this discussion and the preceding
discussion and drawings.
According to a preferred practice, the collapsed sides 45, 46 of
the hollow member 10 are "spot" welded to each other in the area of
their contact, as is schematically shown in one general example as
the area within the line 47 in FIGS. 8, 13 and 15. This area may be
resistance welded using, for example, a 1/8 inch diameter electrode
(class 2 copper) at 100 lbs. pressure and 80 watt-seconds of
current from a capacitor discharge power supply. Alternatively, the
metal may be joined by other welding processes, Tig, Heliarc Spot,
Plasma Needle Arc, or resistance-welding using an AC-timed power
supply with up-and-down slope heat control. In addition, the top
and bottom needle surfaces may be adhered by epoxy or resins, such
as Sulfone Resin 47 adhesive. It is also considered possible to
cold-weld these surfaces together either by electric hammer or
ultrasonics.
If the invention is practiced to shape two points at once in the
center of a double length of tubing as illustrated, the double
length is then cut or ground to form two single length needle
blanks 48 as shown in FIG. 15.
The single-length pieces 48 as shown in FIG. 15 have top 45 and
bottom connected by a weld within the area enclosed by line 47. The
tip portion 49 is twice the wall thickness of the original tube and
twice the thickness of any part of a conventional needlepoint
formed of the same size tubing, since it has been formed by
pressing the two walls together and it is accordingly strong enough
to serve as a long and sharpenable needlepoint without requiring
addition of extra material.
The next step according to the present invention is to grind or cut
the sides of the needle blank to remove material 51 and 52 and
leave cutting edges 53 on top and bottom of both sides of the
point. If the removal of material 51 and 52 is initially
accomplished by cutting, it is desirable to finish the cut by
grinding. Each of the cutting edges 53 extends from the point to
substantially the full diameter of the shaft of the needle tube.
The edges are straight, to give a constant cutting angle of attack
as they are moved through the flesh. It should be understood that
the edges 53 are produced by grinding on flat planes, an operation
which is easy in manufacture and which can be duplicated for
sharpening in the field.
Removal of the material 51 and 52 provides opposite openings 23, 24
from the bore. These openings will be contained within the flat
planes produced by the side-grinding or cutting, and the flat
smooth surfaces of these planes surrounding the openings do not cut
into the flesh (which is cut and relieved by the side edges 53) but
support and guide the flesh so that the heel area 55 is
protected.
As a further step, and one which may be omitted but which
preferably is not, the top and bottom flattened portions 45 and 46
of the needle are ground so that the cutting edges 53 formed on one
side by grinding the sides of the needlepoint are also ground on
their other sides; in other words, both surfaces forming each of
the four cutting edges is preferably ground. The surfaces forming
each edge are virtually at right angles to each other. As shown in
FIGS. 17 and 20, none of the four edges form obtuse angles.
Any grinding and cutting operation produces certain burrs which
should be removed if the smoothest surface is desired. This can be
accomplished by using a conventional abrasive slurry gas or
liquid-honing technique wherein small abrasive particles are
carried in a rapidly moving gas or liquid stream so that the
particles are blown through the openings thereby removing any burrs
that might remain.
The needle may be adapted for and attached to a syringe by any
conventional method it is the needle and the point thereof that are
the subjects of the present invention.
The needle disclosed above by text and drawing, includes a pointed
end in the form of a quadrilateral pyramid having substantially
identical substantially triangular faces and having a base portion
that is substantially square. The needle of the present invention
can be produced by the above methods or by any other method, such
as for example by molding, casting, or by other fabrication,
possesses distinct advantages over the needles taught by the prior
art. Advantages are realized with small standard needles and for
example those that may be made from tubing having a 0.050 inch OD
with a 0.0085-inch wall thickness, and the advantages increase with
the size of the needle.
First, coring is reduced to the point of being eliminated since the
openings are contained completely within the planes of the cutting
edges, which cutting edges extend all the way back to the body of
the tube so as to cut a clean passageway for the needle virtually
to its full diameter and cross-sectional area. The angle of attack
is small, the initial cuts are started by the solid portion of the
needle tip and the openings to the bore of the tube are relatively
narrow in consequence of the original shaping operation. As the
point is inserted, flesh will be stretched over the edges and cut,
and the flesh will be guided and moved away and over the body of
the tube by the flat surfaces surrounding the openings rather than
being pushed into the openings.
Secondly, being that the point is comprised of four sharp edges,
there will be no tearing. Rather the flesh will be cut cleanly
promoting easy entry and quick healing. The cuts are short and
straight as illustrated by lines 59 in FIG. 23 in marked contrast
to the single long curved core-cutting operation of the
conventional needlepoint as illustrated in FIG. 22. The needle
taught herein produces less tissue damage, and more easily healed
cuts than the conventional needle, which is particularly important
for multiple injections, as for example, needed by diabetics or
persons fed intravenously.
Thirdly, the tip lies on the centerline of the tube so that when
the needle is inserted it will follow the point straight in,
without veering or deflection, even in the case of long, thin,
flexible needles.
Fourthly, there are two openings on opposite sides of the point.
This allows even dispersion of medication in the desired area.
Further, the openings extend for a major length of the point on
opposite sides so as to provide two areas for the passage of fluid
into the patient, either of which can be blocked without preventing
the passage of fluid into or out of the needle.
* * * * *