US3402713A - Hypodermic syringe with improved retaining means - Google Patents

Description

T. s. SENKOWSKI ETAL 3,402,713

Sept. 24, 1968 HYPODERMIC SYRI NGE WITH IMPROVED RETAINING MEANS 2 Sheets-Sheet 1 Filed May 13, 1965 INVENTOR 7794400505 5. .SFNKOWJK/ ATTORNEYE p 1968 T. s. SENKOWSKI ETAL 3,402,713

HYPODERMIC SYRINGE WITH IMPROVED RETAINING MEANS Filed May 15, 1965 V 2 Sheets-Sheet 2 24 J j awai- K v/f M ATTORN EY5 United States Patent C) "ice 3,402,713 HYPODERMIC SYRINGE WITH IMPROVED RETAINING MEANS Thaddeus S. Senkowski, Cedar Grove, and Joseph T.

Welch, Maywood, N..I., assignors to Becton, Dickinson and Company, East Rutherford, N.J., a corporation of New Jersey Filed May 13, 1965, Ser. No. 455,548 7 Claims. '(Cl. 128-221) ABSTRACT OF THE DISCLOSURE A one piece molded plastic hypodermic unit for use with a needle of the type comprising a cannula supported in a hub provided with radially outwardly extending flanges. The hypodermic unit includes a relatively flexible internally threaded retaining collar projecting forwardly from one end for receiving and retaining the hub. The collar threads have a forward sidew-all substantially perpendicular to the longitudinal axis of the collar for guiding the hub into a locking position and a rear sidewall forming an. acute angle with the longitudinal axis for cooperating with the internal surfaces of the collar to retain the hub in place.

This invention relates to an improved hypodermic unit mount for detachably connecting a cannula and hub assembly to the hypodermic unit embodying an all plastic disposable construction and to an improved method of manufacturing the same. The present application will be devoted primarily to a hypodermic unit encompassing an integral one piece syringe barrel construction. It should be understood, however, that the present invention contemplates the application of our improved mount to other types of hypodermic units to which a detachable needle and hub assembly may be applied, including other hypodermic syringes, blood donor assemblies, cartridge holders, ampoules and the like.

In many instances, it is necessary that a hypodermic unit be provided with a detachable cannula. With reusable, resterilizable glass syringe assemblies the prob-- lem of providing for a detachably retained cannula has been solved in a superior fashion with the Luer-Lok type mount. The provision of such a mount heretofore to an all plastic disposable hypodermic unit has not been economically feasible or practical for a number of reasons which would render the cost of the unit exorbitantly high.

It is therefore an object of our invention to provide an improved low cost disposable all plastic hypodermic unit having formed integrally therewith a Luer-Lok type needle mount.

Another object of our invention is to provide a hypodermic unit having a mount of this type capable of receiving a detachably retained hub and needle assembly so as to form a circumferential line sealing contact between the needle and hub assembly and nozzle of the needle mount.

Our invention contemplates the provision of an all plastic hypodermic unit made in one piece having a so porting portion at one end thereof, and a bored nozzle projecting forwardly from the supporting portion providing a Luer taper and being adapted to be sealingly engaged by the internally tapered hub of a hypodermic needle assembly. A retaining collar also projects forwardly from the supporting portion in concentric relationship with the tip and is spaced radially therefrom a distance large enough toaccommodate the extended flange portions of the hub. The retaining collar is provided with a selected degree of flexibility and elasticity to permit internal threads formed thereon to be readily stripped 3,402,713 Patented Sept. 24, 1968 from the mold faces during the molding cycle. In facilitating this stripping, the configuration of the side surfaces (the surfaces of the threads on the side of the barrel supporting portion) of the threads is selected to form camming surfaces which are adapted to be readily disengaged by longitudinally shifting these surfaces permitted by the flexibility and elasticity of the collar.

With these and other objects in mind, reference is had to the attached sheets of drawing illustrating practical embodiments of the invention and in which:

FIG. 1 is a side elevation of a hypodermic syringe assembly embodying our invention;

FIG. 2 is a fragmentary detailed view on an enlarged scale of the needle mount portion of the assembly;

FIG. 3 is a horizontal cross-sectional view of the needle mount in the direction of the arrows on line 33 of FIG. 2;

FIG. 4 is an end view of the hypodermic syringe with the needle assembly detached showing the open end of the needle mount;

FIG. 5 is a view similar to FIG. 4 showing the needle hub in position to be applied to the needle mount;

FIG. 6 is a fragmentary sectional view in the direction of the arrows on line 66 of FIG. 5;

FIG. 7 is a view in cross section showing the needle mount and supporting portion of the hypodermic unit and the corresponding portions of the mold in which it may be made and showing a typical thread configuration whereby the needle mount may be stripped from the mold;

FIG. 8 is a view similar to FIG. 7 showing the initial phase of removing or stripping the syringe assembly from the mold without the necessity of unscrewing the threads;

FIG. 9 is a view similar to FIG. 7 showing the removal procedure in an advanced stage after the stripping operation has been completed;

FIG. 10 is a view similar to FIG. 7 showing the removal of the hypodermic unit from the mold;

FIG. 11 is a Side elevation partly in section showing an embodiment wherein circumferential line contact between the hub and tip is made in one position; and

FIG. 12 is a view similar to FIG. 11 showing the preferred circumferential line contact position between the hub and tip.

Our improved mount for detachably connecting a cannula and hub assembly to a hypodermic unit has applications to all types of plastic hypodermic units to which a detachable needle and hub assembly may be applied. As indicated hereinbefore, we have shown for purposes of illustration the use of our mounting in a hypodermic syringe 10.

The syringe comprises a barrel 12 having a bore 14 of relatively uniform diameter and may be made of any suitable plastic material that is relatively flexible and inert and impervious to the liquids, such as medication and blood with which it may come in contact. Polyethylene, polytetrafluoroethylene, polychlorotrifluoroethylene, polypropylene, polymers and copolymers of vinyl chloride are all suitable materials. We prefer to use polypropylene. The barrel is preferably transparent or translucent so that materials therein can be readily observed. The barrel is open at its outer end 16 and may be generally tapered as shown in FIGS. 2 and 3 at its inner end 18. Integrally connected to the outer end of the barrel is a finger engaging flange 20. A plunger 22 is provided for the bore of the barrel to permit aspiration and expulsion of medicaments.

The hypodermic needle assembly 24 is of conventional configuration. It comprises a cannula 26 suitably mounted as by epoxy resin in a hub 28. The cannula may be made 3 of any suitable metal such as steel, particularly stainless steel which is inert to the materials with which it may come in contact, such as blood or medication. The hub 28 is made of a relatively rigid thermoplastic material also inert to and impervious to the materials with which it may come in contact. Suitable plastic materials are acetal resin, polypropylene, polystyrene, polyamide, cellulose acetate or the polymers or copolymers of vinyl chloride. The hub is generally of a tubular configuration and is provided with a tapered bore 30 of generally larger diameter at the open outer end 32 of the hub than at the needle end thereof. Projecting laterally from the open outer end of the hub are diametrically opposed flange portions 34A and 34B. The hub assembly may be readily applied to the mount and readily removed from the mount but when in position thereon, it is effectively free from leakage at the point of connection between the hub assembly and needle mount and remains firmly in position when the hypodermic syringe is in use.

Our improved mounting for a hypodermic unit com prises a supporting portion formed at the inner end 18 of the barrel 12. The supporting portion is inwardly tapered and a nozzle 36 projects therefrom. An interior bore 38 is in communication with the barrel at the inner end 18 and is opened at its opposite end. The nozzle has a conical or tapered exterior profile and is of a size such that i twill have a sealing engagement with the inner bore surface of the hub 28 when the latter is mounted. A retaining collar 40 projects forwardly from the supporting portion 15 of the barrel in spaced concentric relationship with the nozzle 36. The collar portion is spaced from the nozzle a distance sufficient to accommodate the diametrically opposed flange portions 34a and 34b extending later-ally from the open outer end of the hub 28 of the hub and needle assembly.

Our invention provides for the inclusion of a plurality of diametrically opposed helical threads 42a and 42b (as shown most clearly in FIG. 2) extending around the inner surface of the retaining collar acting as cams for frictional engagement with the diametrically opposed flange portions 34a and 34b of the hub 28. The outer side walls 44a and 44b of the threads 42a and 42b, namely those surfaces facing away from the supporting portions serve as guiding surfaces for the flanged portions of the hub and needle assembly as said assembly is inserted into the needle mount as seen most clearly in FIG. 6. The opposite walls 46a and 46b facing towards the supporting portion serves to assist in retaining the hub and needle assembly in position by retaining the flange portions 34a and 34b thereof in a frictionally compressed relationship with the collar and nozzle of the barrel. Side walls 44a and 44b will be hereinafter referred to as the guiding surfaces and side walls 460! and 46b will be hereinafter referred to as the retaining surfaces.

While, as generally hereinabove discussed, any workable number of threads may be used, we prefer a thread arrangement of the double thread type which includes two separate or single threads starting at diametrically opposite points or at points 180 apart. The threads should have a root (the distance measured at the groove or bottom surface 48 joining the sides of two adjacent threads) suflicient to accommodate the opposed flange portions of the hub, and to permit movement therein. In addition, we prefer to provide the lead-in of the needle mount represented by the numeral 50 as shown in FIG. 7 with a diameter larger than that of the rest of the needle mount, to facilitate the entry of the needle and hub assembly. The threads are of a truncated type and accordingly do not reach an apex. This cooperates in facilitating the stripping of the mount.

We have found that if certain thread configurations are maintained, it is possible to economically strip the barrel from the mold. These configurations have particular reference to the angles formed by the respective side walls 44A and 44B, 46A and 46B of the threads relative to the longitudinal axis of the needle mount.

In this respect, we have found that the needle mount can be satisfactorily stripped from the mold by means of a camming action, and thereafter assured adequate retaining support for the detachable needle assembly, if the retaining surface forms an angle to the longitudinal axis of the needle mount of between 25 and 70. However, for the indicated material, we prefer to maintain the angle of the retaining surface at a camming angle of approximately 45 to the longitudinal axis of the needle mount.

As to the angle formed by the guiding surface to the longitudinal axis, we have found that satisfactory results are achieved if the angle is substantially perpendicular to the longitudinal axis so that an adequate guiding surface is provided for the extended flange portions of the hub and the danger of cross-threading is minimized.

For standardized hub and needle assemblies of the type herein described having an open outer ended hub with diametrically opposed flanges projecting therefrom, we have found that the needle mount can be satisfactorily stripped from the mold if the height of the threads is maintained at about between .004. and .012 inch. If the height is maintained within the range, the threads will provide adequate guiding and retaining surfaces for the hub and needle assembly. However, for the indicated material we prefer to maintain the height of the thread at about .009 inch.

When plastic materials are molded, certain minute crevices appear in the surfaces thereof. Therefore, unless the parts of the plastic material are sufficiently related and compressed so that the materials deform, these crevices can be the cause of leakage of material between the parts. We have found that when circumferential line contact is made between the parts, rather than entire surface-tosurface contact, maximum stress between the parts is had so that the parts are deformed to in effect iron the waves, crevices and scratches normally present. Thus, while for normal use, sufficient compression may be had between the parts of an all plastic syringe assembly when the hydrostatic pressure is increased, as when heavy fluids are used which require'greater forces to expel, contact such as that previously described, namely, circumferential line contact, is necessary to maintain the parts in their relationship to each other so that leakage will not occur. Thus, while the utilization of a thread-like arrangement as hereinbefore described, achieves satisfactory results, we have found that an even superior mount can be provided if a high stress circumferential line contact is made between the nozzle 36 of the needle mount and the inner bore surface 30 of the hub 28. This is shown diagrammatically in FIGS. 11 and 12. The preferred form of contact is shown in FIG. 11. In both instances, we achieve a circumferentially extending line contact between the parts. The stress concentrated along the circumferential line is considerably greater than it would be if distributed over the entire surface area of the nozzle to bring about a substantial increase in the sealing pressure.

As can be seen in FIG. 11, the circumferential line contact is made between the forward end of the nozzle 36 and the inner end of the bore surface 30 of the hub to provide minimum circumferential line contact. It will be noted that surface contact in an arrangement such as this is not had between the entire length of the nozzle and'the inner bore surface. The same principles are applied and shown in FIG. 12, only in this situation line cont-act is made between the rear end of the nozzle and the open end of the hub and needle assembly. While stresses are less in this arrangement than in that described in relation to FIG. 11, the results are still superior to the complete snrface-to-surface contact of the prior art devices. Circumferential line contact may be achieved by varying the external tapered profile of the nozzle 36 of the barrel or the internal taper of the hub with respect to each other so as to provide circumferential line contact at the desired point.

Accordingly, the hub and needle assembly are placed intothe lead of the needle mount and screwed into position. The diametrically opposed flange portions of the hub are guided by the outer thread side wall in their movement into position within the needle mount and final rotation of the hub and needle assembly creates the desired line contact and accordingly, the necessary stability. The hub and needle assembly is retained in position in the needle mount by cooperation of frictional forces exerted between it and the nozzle and collar portions of the mount. The diametrically opposed flange portions of the hub are compressed when in position by the inner surface of the collar portion, thus creating additional tension and stress on the parts and are also retained in position by the inner side walls of the threads appearing on the inner surface of the collar portion.

An important contribution of invention is the provision of means for stripping the unit from a mold in accordance with the disclosed and somewhat preferred embodiment. A three-part mold, as indicated in FIGS. 7, 8 and 9, is utilized wherein the first part is an outer cavity insert 60, the second part being the internal diameter core pin 62 and the third part is the threaded core pin 64. The cavity insert '60 is formed so as to have a barrel portion 66 complementary in configuration with the outer surface of the barrel 12 and a collar portion 68 conforming in size and complementary in configuration with the exterior surface of the collar 40. The second part, or internal diameter core pin 62, is assembled and is arranged so as to conform to the internal configuration of the bore of the barrel and nozzle thereof and is assembled with the mold in spaced relationship from the barrel portion 66 of the cavity to provide the desired thickness for the barrel. Finally, a threaded core pin 64 is provided which has an inner surface conforming in dimensions and complementary in configuration with the exterior surface of the nozzle 36 and an outer surface conforming in dimensions and complementary in configuration with the desired inner surface of the collar, said outer surface of the threaded core being formed with radially outwardly projecting threads 70. The threads conform in dimension and are complementary in configuration with the desired threads to be formed on the inner surface of the collar and have one side surface facing away from the support portion of the cavity disposed at an angle presenting a camming surface and an opposite side surface disposed at a relatively steep angle to the longitudinal axis of the core. The threaded core pin 64 is placed into position within the mold in spaced relationship from the collar portion of the cavity 60.

In a typical molding cycle, the mold is entirely closed in the manner as indicated in FIG. 7 wherein the parts including the cavity 60, the internal diameter core pin 62 and the threaded core pin 64, are arranged as shown to define a cavity into which the selected molten plastic material may be injected. A cooling part of the cycle follows in which the plastic material is allowed to set up and become solidified so as to form the barrel 12. The parts are then shifted into the position depicted in FIG. 8. At this point, the cavity insert is moved in the direction of the arrows as indicated in FIG. 8 so that the collar portion 68 of the cavity insert 60 is retracted relative to the collar 40. Suflicient clearance is now prm vided as indicated by the reference numeral 72, for the collar 40 to flex and yield outwardly as it is stripped from and over the threaded portions 70 of the threaded core pin 64. Thereupon, the threaded core pin is shifted longitudinally as shown in FIG. 9 away from the barrel so as to strip the collar 40 from the threaded core pin without unscrewing due to the temporary radial expansion of the collar incident to the camming action. The insert 60 is retracted simultaneously with the threaded core pin 64 whereupon both will provide sufficient clearance to permit removal of the barrel 12 from the core pin 62. Means for removing the unit from the core pin 62 may be provided as indicated in FIG. 10 in the form of a strip plate 74. Thus, the barrel may be conveniently removed by moving said strip plate in the direction of the arrows as indicated in FIG. 10.

As mentioned heretofore, hypodermic units other than those of the barrel type, may be utilized with our improved needle mount. These hypodermic units include hypodermic syringes, blood donor assemblies, ampoules and the like.

It will thus be seen that we have provided an all plastic hypodermic unit having an improved mount for detachably connecting a cannula and hub assembly of the Luer-Lok type and an improved molding method of making the assembly wherein the assembly can be made easily and economically without impairing the desired performance of the unit. In this connection, the unit may be automatically stripped from a mold without the necessity of unscrewing according to the teachings of our invention.

Thus, among others, the several objects of the invention as specifically aforementioned, are achieved. Obviously, numerous changes in construction and rearrangement of parts might be resorted to without departing from the spirit of the invention as defined by the claims.

We claim:

1. A hypodermic assembly comprising in combination: a replaceable needle assembly of the type having a cannula together with hub having a bore forming an outwardly tapered surface leading to an open outer end and diametrically opposed flange portions extending radially from said outer end and having a diameter which is at least equal to the hereinafter defined root diameter; and a one-piece integrally molded plastic hypodermic unit having a supporting portion formed thereon, a nozzle having an internal bore and an exterior tapered surface, said surfaces interacting to form approximately a circumferential line sealing contact when the supporting hub is mounted on the nozzle thereby providing sealing engagement between the same and assisting in stabilizing the hub on said nozzle, and a retaining collar projecting forwardly from the supporting portion in concentric relation ship with the nozzle and spaced therefrom a distance substantially large enough to accommodate the extended radial flange portions of the hub and cooperate in retaining said flange portions by frictionally and compressively engaging therewith, said retaining collar having a wall thickness which in and of itself with the hereinafter defined thread retaining surface is sufiicient to provide said retaining forces on said hub thereby to retain the same between the collar and nozzle, yet having suflicient lateral flexibility to allow the hypodermic unit and integral collar to be ejected from the mold, a plurality of helical threads having a height from approximately 0.004 to 0.012 extending around the inner surface of said retaining collar, said threads having a root diameter to accommodate the diametrically opposed flange portions of the hub therein in said compressive relationship and said threads having a first side wall providing a retaining surface, for engaging and cooperating with the internal surfaces of said collar in retaining and further stabilizing the flange portions, facing toward the supporting portions and a second side wall providing a guiding surface facing away from the supporting portion, the retaining surface forming an angle to the longitudinal axis of between 25 and 70 and the guiding surface being substantially perpendicular to the longitudinal axis, said needle assembly being mounted on said hypodermic unit so that said hub and nozzle taper form said approximate circumferential line sealing contact and said hub flanges are compressively retained by said threaded collar.

2. A hypodermic unit as set forth in claim 1, in which the taper of said nozzle differs in profile from the internal 3. A hypodermic unit as set forth in claim 1, in which I the tapered profile of said nozzle is greater than the tapered internal profile of said supporting hub to form said approximate circumferential line sealing contact so that the sealing zone is adjacent the inner end of said tubular nozzle.

4. A hypodermic unit as set forth in claim 1, in which the tapered profile of said nozzle is less than the tapered internal profile of said supporting hub to form said approximate circumferential line sealing contact with the supporting hub so that the sealing zone is adjacent the outer end of said tubular nozzle.

5. The hypodermic assembly as defined in claim 1 wherein the helical threads extending around the inner surface of said retaining collar are substantially truncated in side elevation.

8 6. The hypodermic assembly as defined in claim 5 wherein the angle of said side is substantially 45.

7. The hypodermicassembly of claim 1 wherein the height of said threads is substantially 0.009.

References Cited UNITED STATES PATENTS V 1,916,692 7/1933 Scribner 264.318 2,677,374 5/1954 Burnside- -128+218 2,868,201 1/1959 Gabriel 128-221 3,055,363 9/1962 Eckhart -128-,218 3,301,256 1/1967 "Cowley 2 128218 881,060 3/1908 -Cook 285 334 2,843,508 7/1958 Sheft l28-218 RICHARD A. GAUDET, Primary Examiner.

W. E. KAMM, Assistant Examiner.

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