US3010197A - Method of making hypodermic needles and like articles - Google Patents

Description

Nov. 28, 196.1 .1. K. ROEHR 3,010,197

METHOD OF MAKING HYPODERMIC NEEDLES AND LIKE ARTICLES FiledJan. so, 1958 INVENTOR w/ ATTORNEYS United States Patent C 3,010,197 METHQD OF MAKING HYPODERMIC NEEDLES AND LIKE ARTICLES Jan Kanty Roehr, Waterbury, Conn., assignor to Roehr Engineering Company, Waterbury, Conn., a limited partnership Filed Jan. 30, 1958, Ser. No. 712,226 3 Claims. (Ci. 29-423) This invention relates to a method of making hypodermic needles and like articles having a tubular stem or cannula of small diameter formed of stainless steel or similar material.

In making cannulas for hypodermic needles, the present practice is to draw stainless steel tubing stepwise down to the required diameter which is achieved after a long tube has been cut into a plurality of shorter lengths. From a coil of tubular wire, lengths of, say, eight feet are cut and a mandrel in the form of a metal rod is inserted into the tubelength and then each length is drawn down upon and with the mandrel to reduce the diameter. Sometimes this drawing-of the mandrel-carrying tube was performed more than oncegand, at other times there was only one drawing which wasfollowed by further reduction of diameter without a mandrel, which operation is known as sinking. In connection with such operations the tube is annealed and the reduction is continued until a very fine hollow tube is produced having the diameter desired for the finished cannula. After the first drawing operation, the mandrel, over which the wire is drawn, must be removed for if this were done at a later stage with its incident length of wire there would be great difiiculty in removing the mandrel. Also the first drawing operation or operations will very greatly increase the length of the wire that was in the original coil, making it very difiicult to handle. For these reasons the operation of drawing the original wire down to cannula diameter has not been a continuous one.

One of the objects of the present invention is to provide a process by which the reduction of the initial tubing to the diameter of the finished product, such as a needle cannula or other fine tube, can be performed in a continuous process or substantially continuous process with the elimination of the need for shortening the wire length in preparation for a subsequent drawing step or steps.

A further object is to cheapen the process of making cannulas and like articles and to expedite the production of such articles from tubular material that can be obtained in coils of any desired length.

To these and other ends the invention consists in the process and the sequence of steps as hereinafter described and defined in the claims.

In the accompanying drawing:

FIG. 1 is an enlarged longitudinal section of a hypodermic needle;

FIG. 2 is an enlarged longitudinal section of a portion of a length of tubular wire encasing a tubular mandrel;

FIG. 3 is a section on line 33 of FIG. 2;

FIG. 4 is a view similar to FIG. 2 showing the mandrelsupported tube at a later stage in the process;

FIG. 5 is an enlarged longitudinal section of a further reduced mandrel-supported tube cut to the length of the finished article; and

FIG. 6 is a view similar to FIG. 5 showing one end portion in elevation.

In FIG. 1, a hypodermic needle is shown having a tubular stem or cannula 10 sharpened at one end and threaded at the other end for connection with the customary handling piece or hub 11. At its rear end the cannula is provided with threads 12 engaging internal threads for example several hundred feet, may be used as an outer' element to be drawn 'upon a mandrel, the mandrel being a wire of soft carbon steel and preferably a tubular wire of such steel. The mandrel-supported tube will be of sufiicient length for the manufacture of a multiplicity of small-diametered short tubes such as cannulas. FIG;

2 shows a portion of the original outer wire after it has been drawn down to an extent upon the tubular mandrel. In this view the outer tube is shown at 15 and the mandrel at 16. The outertube 15 may be formed of welded strip and the mandrel may be formed from welded strip. In FIG. 3 the welds of the tubes are indicated, but it may be pointed out here that so far as the mandrel is concerned, this may be in the form of a tubular strip having abutting edge portions and lacking a weld.

FIG. 4 shows the assembly of FIG. 2 after an additional drawing step has been performed, lengthening to an additional extent the tubular article. Between the drawing operations annealing may be effected in the usual-manner. The number of draws may be varied as required by the existing conditions but it may be assumed, for example, that following the first draw resulting in the article of FIG. 2, the second draw resulting in the article of FIG. 4, and a third draw reducing the article to the extent shown in FIG. 5 (which is another much enlarged view), there is no further drawing. There is, however, a straightening of the composite tube comprising the inner and outer members which may be done by means of straightening rollers in a manner well known in the art. The next step is to cut the tube to lengths corresponding to that of the finished cannula, this being done by a suitable cutting device. In practice the cannula may have a length somewhat in excess of one and one-half inches, for example, and FIG. 5 shows a considerable enlargement. At this stage the ends of the blank are honed so that after cutting the ends are smooth. The next step is to provide means for connecting the can nula to the hub, and for this purpose the threads 12 are 7 formed by rolling one end of the blank. The blank is then in the condition shown in FIG. 6. Instead of forming threads upon the outer tube (FIG. 6) parallel ribs may be rolled upon the blank so that at a later stage the hub of the needle may be forced over such ribs to hold the hub on the cannula. The cannula is preferably sharpened before the mandrel is removed.

The next step is to remove the mandrel or core from the article shown in FIG. 6 and this may be done by a mechanical means or by a chemical process. If this is done chemically, the article is subjected to the action of a strong acid which will dissolve the core without injuring the outer tube. A suitable acid for this purpose is nitric acid and the procedure preferred is the boiling of the article in a bath of nitric acid, for example, which will dissolve the core and remove it from the outer tube. It is then advisable to clean the outer tube to remove any discoloration which may have resulted from the bath. After this treatment the distal end of the cannula is sharpened in the usual or any preferred manner.

While in the foregoing description the outer tube carrying the mandrel is subjected to three drawing operations, the results of which are shown in FIGS. 2, 4 and 5, which operations take place upon the workpiece before cutting the workpiece to divide it into sections, the number of Patented Nov. 28, 1961 cannula assists in straightening the corresponding end of the tube.

The soft carbon steel wire used as a core or mandrel may be, in some cases, a solid wire rather than a tubular one. geous. The use of a solid Wire requires a rather heavy outer stainless steel tube (provided with a rather thick wall.) since the reduction in the wall thickness during each drawing pass is considerable. Where a tubular mandrel or core is used, as described above, made from carbon steel or any other suitable soft material, the resistance of the core is reduced and this permits less reduction of the outer wall during each drawing pass. Due to this, standard sizes of stainless steel tubing can be used as the initial material with considerable savings in time and expense. I

Among materials suitable for use in providing an inner core are plastic materials.

Instead of beginning the operation by drawing a mandrel-supported tube it may be begun with a small tape of stainless steel having the mandrel or core laid thereon. The tape may then be formed up around the mandrel and welded. This will be a preliminary step producing the same raw material with the core inside which Was mentioned above.

Various changes in the detailed procedure herein described may be made without departure from the principles of the invention and the Scope of the claims.

However, the use of a tube as a core is advanta What I claim is:

l. The method of making small tubular metal articles such as cannulas, which method comprises providing stainless steel tubing supported upon an interior tubular mandrel and of a length suitable for-the manufacture therefrom of a multiplicity of small tubes, said mandrel be ing of softer material than the outer tubing, drawing this assembly or composite workpiece a number of times to reduce its diameter progressively while the workpiece is continuous, then, after the outer tubing has been reduced to the diameter desired in the finished article, cutting the tubing and mandrel into sections corresponding substantially to the desired length of the finished article, then sharpening one end of each of said sections and rolling the other end of each of said sections to provide projections upon the outer tubing engageable with a needle hub, and then removing the mandrel portions from the cut-ott sections.

2. The method of claim 1 in which the mandrel portions are removed by chemical treatment.

3. The method of claim 1 in which the mandrel portions are removed by dissolving them in an acid solvent.

References Cited in the file of this patent UNITED STATES PATENTS 1,568,369 Everett Jan. 5, 1920 1,891,304 Everett Dec. 20, 1932 1,913,206 Littler June 6, 1933 2,022,234 Everett Nov. 26, 1935 2,047,555 Gardner July 14, 1936 2,800,942 Parker et al. July 30, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,010,197 November 28, .1961

Jan Kanty Roehr It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the grant, lines 2 and 3, for "assignor to Roehr Engineering Company, of Waterbury, Connecticut, a limited partnership," read assignor, by mesne assignments, to Brunswick Corporation, of Chicago, Illinois, a corporation of Delaware, line 12, for "Roehr Engineering Company, their heirs" read Brunswick Corporation, its successors in the heading to the printedspecification, lines 4 to 6, for "assignor to Roehr Engineering Company, Waterbury, Conn.,

a limited partnership" read assignor, by mesne assignments to Brunswick Corporation, Chicago, Ill. a corporation of Delaware,-.

Signed and sealed this 19th day of March 1963.

(SEAL) Attest:

ESTON G. JOHNSON DAVID L. LADD' Attesting Officer Commissioner of Patents

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