US 3181336 A
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Description (OCR text may contain errors)
y 4, 1965 H. P. SCHOFIELD 3,181,336
METHOD OF PRODUCING THE POINTED END OF A HYPODERMIC NEEDLE Filed NOV. 15, 1961 -F/G.6.- v, F/G.7.-'
23 2 22 I5 INVENTOR:
Huoe'm' P ScnaE'n-D United States Patent C) 3,131,336 METHGD @F FRQDUOING THE PQlNTED END @F A HYFODERMHE Hubert Percival Schoiield, Langdale, Hatchet Laue, Windsor Forest, England Filed Nov. 15, 196i, Ser. No. 152,558 2 Claims. (Cl. 72-34=dl The present invention relates generally to the manufactors of hypodermic needles, and more particularly of the pointed ends thereof.
An object of this invention is to provide a method consisting of inexpensive and easily practiced steps by which, starting from hollow tubing, hypodermic needles may be cheaply mass produced so as to each have a pointed end portion having at least one narrow slit opening laterally from the axial bore of the tube or needle at the pointed end portion thereof.
Since the passage for emitting liquid from the hypodermic needle is restricted to a narrow slit opening lateral- 1y from the bore of the tube at the tapering or pointed end portion thereof, there is no possibility of the cutting of a disk or other shaped small piece of skin by the needle during penetration of the latter through the skin, and such penetration is effected by a piercing and spreading action, as distinct from a cutting action.
In accordance with an aspect of this invention, the pointed end of a hypodermic needle is formed by flattening an end portion of an axially bored hollow tube of deformable material to give such end portion a tapering configuration leading to a point with at least one ear-like projection extending laterally therefrom and having two thicknesses of the material, and then trimming cit the projection so as to provide at least one narrow slit opening laterally from the axial bore of the tube at the tapering end portion of the latter.
In a preferred embodiment of the invention, the ear-like projection extending laterally from one side of the tapering end portion of the tube is spaced along such end portion from the point of the latter so that, after trimming off of the projection, the resulting slit is spaced from the point which is solid.
A further feature of the present invention resides in providing during manufacture of the needle a variable width of discharge orifice so as to cater for factors of injection such as viscosity of the liquid to be injected, homogenisation, turbulence and resistance to liquid how.
The invention is more particularly described with reference to the accompanying drawings which illustrate several forms of construction by way of example and in which:
FIGURE 1 is a longitudinal View of one end of a tubular element of one embodiment in an intermediate stage of manufacture thereof.
FIGURE 2 is a similar longitudinal view but in a plane at right angles to that of FIGURE 1 of the finished needle thereof.
FIGURE 3 is a section on the line EFL-ill of FIG- URE 1.
FIGURE 4 is a corresponding end view of the finished product.
FIGURE 5 is a longitudinal view of one end of a tubular element in an intermediate stage of manufacture of a modification.
FlGURE 6 is a longitudinal view in a plane normal to that of FIGURE 5 of the corresponding end of the finished needle.
FIGURE 7 is a section on the line VllVll of FIG- URE 5, and 7 FIGURE 8 is a corresponding end view of the finished needle shown in FIGURE 6.
fidhl iidfi Fatented May 4, 1 .965
In the embodiment shown in FIGURES 13, the element to be made into a tubular hypodermic needle is a tube 15 which may be of metal or again of plastic and may be made by boring a solid wire in the case of a metal or by extrusion in the case of a plastic. That end of the hollow tube 15 which is to constitute the pointed end of the needle is first flattened to form cars 16, 1'7 and to take the form of a spear whereupon it is trimmed to a point and ground to a shape concentric about its axis of symmetry as shown in FIGURE 2 so that the ears disappear and the opposite faces of the tube are separated to form leaves l8, 19 which taper to what is virtually a sharp point 2% leaving an extremely narrow slit 21 between them through which liquid is forced during use of the needle; in the case of a small needle this slit which extends longitudinally of the needle may be as small as a few thousandths of an inch in width, so much so that it cannot function in the cutting or severing of skin, with the result that a piercing as distinct from a cutting operation is performed on passage of the neeedle point through the skin.
In other words it is impossible during use of the needle for any part of the skin to be wholly severed at the site of puncture and for the solution being injected to drag with it any foreign matter into an opening of the skin made by the pointed end of the needle 15.
It will be appreciated that, by virtue of the substantially angular cross-sectional shape of the ears l6, 17 as shown in FIGURE 3, the width of each slit will depend on the extent of the final grinding operation in completing the removal of the ears 7.6, 17, that is to say the greater the depth of grind the wider the slits and vice versa, so as to cater for factors of liquid viscosity, resistance to liquid flow, homogenisation and turbulence and the like at the needle orifice during injection.
The two leaves l8, 19 may take any desired shape, that is to say they may be substantially flat, or again they may be slightly convex or concave in form to impart strength for resisting any tendency for them to spread open during the entry of the tip Zll into flesh or muscle. it will be appreciated, however, that this embodiment could be formed with three, four or even more leaves.
In the construction illustrated in FIGURES 58 a single car 22 is formed on one side only of the tube and is cut oil either in the same or a subsequent operation to leave a narrow longitudinal slit 23 on one side only of the tubular needle. In this form of construction, as with that of FIGURES 1-4, the final step in the manufacture of the tube is the act of grinding it to its finished concentric form and the pointed end is indeed solid as shown at 2d. The same remarks apply to thewidth of the slit 23 as with that of each slit 21 in the construction according to FIGURES 14.
Any of the many known techniques utilised in the manufacture of pointed articles such as needles may be employed in producing any of the embodiments or their alternatives.
As regards the opposite end of the needle, in one form of construction the needle may be produced complete with connector or ferrule, i.e. with the whole formed or assembled in one piece of metal, if necessary using known techniques not previously considered for this application.
In another form that end of the needle remote from the point or tip may be spread, upset, or dimpled to provide a suitable key for fixing in a plastic ferrule or socket, which may be injection moulded direct on to the needle. Nylon, Rilsan, or the like plastic is suitable for use where the needle is to undergo heat sterilization, but when cold sterilization is required, cheaper plastics such as polystyrene or polythene may be used.
Apart from overcoming the disadvantages of the conventional hypodermic needle both as regards manufacture and use, needlesof the present invention may be manufactured and sold at a much cheaper price, thereby enabling each to be economically disposable after one use; in this respect it is my experience that once a needle has been used, the bore can never be satisfactorily cleaned, and although it can be sterilised thedanger always exists of injecting sterile foreignmatter from one patient to another. This applies to the syringe to which it may be fitted.
In the foregoing the invention has been described with reference to specific illustrative devices. It will be evident, howeyer, that variations and modifications may be made without departing from the broader scope and spirit of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.
1.. A method of producing the pointed end of a hypodermic needle comprising flattening an end portion of an axially bored hollow tube. of deformable material to give said end portion a tapering configuration leading to a solid point with one ear-like projection extending laterally from one side of said tapering end portion and having two thicknesses of said material, and trimming-01f said projection so as to provide one narrow slit opening lateral- 2 1y from the axial bore of the tube at the tapering end portion of the tube inback of said solid point.
4 2. The method as in claim 1; wherein the two thicknesses of material of said ear-lik projection diverge slightly toward the axis of said tube so that the width of said slit is dependent upon the extent to which said ear-like projection is trimmed-ofit.
creases Cited by the Examiner UNITED STATES PATENTS 1,731,867 10/29 Rice 29-543 X 2,032,991 3/36 Lange 29539 X 2,130,173 9/38 Barnes. 2,133,092 10/38 Gettig 29537 2,213,098 8/40 Smith 113-32 X 2,511,858 6/50 Lampton 113-52 X 2,634,726 4/53 Hanson 128--221 2,737,948 3/56 Brown 128-221X 2,746,455 5/56 Abel 128221 2,954,768 10/60 Hamilton 128--221 2,989,053 6/61 Hamilton 128-22l FOREZGN PATENTS 1,196,601 11/59 France.
630,377 10/49 Great Britain.
WHITMORE A. WILTZ,-Primary Examiner.
RICHARD J. HOFFMAN, Examiner.