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Publication numberUS3827926 A
Publication typeGrant
Publication dateAug 6, 1974
Filing dateFeb 9, 1973
Priority dateMar 22, 1971
Publication numberUS 3827926 A, US 3827926A, US-A-3827926, US3827926 A, US3827926A
InventorsHavstad H
Original AssigneeHudson Oxygen Therapy Sales Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for molding a nasal cannula
US 3827926 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Aug. 6, 1974 H. R. HAVSTAD 3,327,926

mmaon FOR momma A NASAL cmmuu Original Filed March 22, 1971 FIG. 4

mm :MEIHODFOR MOLbINGA NASAL CANNULA arold R,;Havstad,=Lakewqod,1Calif., assignor to apy Sales Co.

Ser. No. 126,452, now H nil, this application Feb.

1 Claim G en of application Ser. No. 126,452, a'r Z Z, 19 51, Pat. 3,731,900.

BAOKGROUND OF -r- THE" "INVENTION m tly l eannula devices have become very important a a iiiefanjs'of administering oxygen to patients. Such devices are known to incorporate a flexible plastic tube h' h ced he upati'ent ',upper lip and main- A y an elastic strap or other rendingar oundthe patients head and s fjfith. plasticf tube. Such a device pai'r of extensions, usually referred to as nasa l tips which are hollow and join the plastic tube.

tips extend the patientfs nares or nasal pasa fibeflowsinto the main tube of patients nasal cavity andpharynx;

' Jen: incorporated into the canto improve their efliciency as ample's of improved design tips c rved to conform to the ed fsurface' and/ or ends which p" r lip and cheek respectively. patient comfort and mainthe at'ient so that the nasal g therapeutic gases intro nited States Patent Oflice 3,827,926 Patented Aug. 6, 1974 patient is unconscious or otherwise disabled to the extent of not being able to again insert the nasal tips into his nostrils, where a constant or necessary oxygen supply to the patient is absent, further injury could insue.

In order to eliminate cannula rotation caused by twisting of the oxygen supply tube, certain cannula devices have been improved by incorporating hollow angled inlet tube which joins and extends from the main cannula tube and to which inlet tube an oxygen supply tube is attached. Such a feature is illustrated in US. Pat. No. 2,868,199. The use of an angled inlet tube, greatly reduces any rotational movement of the cannula device otherwise caused by the twisting of the oxygen supply tube. This feature will be appreciated since any rotation or twisting of the oxygen supply tube will only tend to rotate the angled inlet tube but will not be passed on to the main tube of the cannula which does not lie along the axis of either the oxygen supply tube or the angled inlet tube. Thus, the force of a twisted oxygen supply tube substantially terminates at the angled inlet tube portion of the cannula.

In molding a nasal cannula of the type described above,

it has been the practice to use a plurality of forming means the" nasalfftips and directly into the 5 referred to as cores at least one of which is retractable. Thus, separate cores are used in forming the tubular body portion of the cannula and the tube-like hollow nasal tips. Again, these cores are maintained in spacial relationship to the mold cavity within the closed mold while a thermoplastic material is injected into the cavity and around the cores. Thereafter, as the mold is opened, the cores around which the tubular body portion or the hollow nasal tips are formed are retracted leaving the cannula remaining on the unretracted core. The mold operator thenpeels the cannula from the core.

In producing a cannula having a tubular main body about which the tubular main body is formed is referred to as a transverse core. The cores used to form the hollow nasal tips are nipple cores. In the mold apparatus the transverse and nipple cores are brought together in an attempt to simulate a unitary or integral core at the phase during the molding process in which the material is injected into the mold cavity and around the cores. Thus, the nipple cores comprising two spaced rods will meet and contact the transverse core so that when the injected material flows around these cores the hollow nasal extensions and hollow main tube will join.

It will be appreciated that in attempting to produce a cannula in which the interior passageways for the flow of oxygen or other gases is to be unobstructed, i.e., flow along the main tube and through the nasal tips, the respective cores must be carefully machined so that no spaces are present between the nipple core and transverse core at the junction area. However, as the mold is used these cores become worn at the interfaces and common points of contact. This wear due to friction and abrasion, results in small spacial areas being formed which in turn, allows for the injected material to flow in thesesrhallspaces.'This material which remains on the finished molded device is referred toas 'fiash. Further, small diametercores are sometimes deflected by theflowing thermoplastic produc- .1

ing" a deformed product, uneven interior and exterior surfaces and.flash... a, a e

Qnth e exterior o f-t'he cannula flash canbe trimmed to improve theappearancepf the product; On, the other hand,

wherefiash 0 rs on thetinterior-l ofthe cannula andespev cia l ly= inthe tubular orhollow -passageways ,'-cannula pen.

formancgcan be significantly. altered. Especially troublesome is flash located at the areas Wherethenasal tipsjoin the main: tube. It will be appreciated that significant amounts of flash at those areas will causerestriction in the interior gas passageway and may greatly reduce;the

. 3 amount of gas passing into either or both of the nasal tips and possibly shut them off altogether. Accordingly, the avoidance of flash at the interior joinder areas of the hollow nasal tips and main cannula tube will be appreciated as will the disadvantages of using separate nipple and transverse cores.

In a well known and extensively used cannula device prepared by an injection molding process, an angled inlet tube is present adjacent one end of main cannula tube with the hollow interiors of cannula body portions communicating as previously described. In producing such a device four separate cores are used: two nipple cores for forming the two hollow nasal tips, a transverse core for forming the hollow main tube and an angle core for forming the angled inlet tube. Thus, a further problem of flash on the interior of the cannula device is caused where the angled inlet tube communicates with the main cannula tube,

thereby presenting the same problems of possible stoppage-v or interruption of gaseous flow from the angled inlet tube into the main cannula tube as above noted for the nasal tips. Further, since the transverse core used is substantially a straight rod, the main tube of the cannula has an open end when initially formed which must be plugged so that only the nasal tips and angled inlet tube are opened to the exterior of the cannula device. The plugging of this opening is usually accomplished by hand and obviously requires additional time and effort to complete the device which concomitantly increases production costs.

SUMMARY OF THE INVENTION In the cannula molding process of the present invention a unitary core is utilized having an angle core portion, an axial transverse core portion and a nipple core portion each of which portions are integral with and a part of the single unitary forming core. In the injection molding process the unitary core is maintained in spacial relationship with the mold cavity, material is injected into the cavity around the core, the mold is opened and the cannula device is removed from the core. Since the core is unitary in construction, no separate cores are used thereby eliminating flash on the interior of the molded cannula device. The device is removed from the core and a lipped slot formed at the bridge where the core is attached to a core support is closed by a radio frequency welding process. The unique forming means or core described herein, in addition to eliminating interior flash, produces a cannula having hollow nasal tips, a hollow main tube and a hollow angled inlet tube. The device has no other tube openings which must be plugged as previously described except for the lipped slot which is sealed and the lips removed. A further embodiment of the invention utilizing multiple cores will be more fully described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a cannula forming core of the present DETAILED? DESCRIPTION OF THE INYENTION' Referring to FIG. 1, a forming core shown generally as 10 has an upper-portion 12, an angle portion 18 and nipple portions 14 and'15. These portions are integral thus COlIl-f' prising the unitary forming core 10. The nipple portions 14 and 15 are separated rod-like extensions, one located'at' upper portion 12, and the or near the upper end 17 of the other somewhat lower.

The nipple portions 14 and 15 extend substantially perpendicular from the axis of "the upper portion 12. These nipple core portions 14 and 15in are spaced apart and I cooperation with the mold cavity form the nasal tips of: the cannula during the molding process. Accordingly, the distance between nasal tips desired for the cannula to be produced are dependent on the distance between the portions 14 and 15. The nipple core portions 14 and 15 may be substantially straight or curved where curved nasal tips are desired. The length ofthese nipple portions 14 and 15 may also be varied depending ontheintended length of the nasal tips of the cannula, I

The angle portion 18"extends'directlyffromi the upper portion 12 at the joinder area 19 of the upper portiori 12 opposite the end 17. The angle at which the angle-portion v 18 extends from the upper portion 12 may be varied depending on the angle desired'forthfangledinlet tube of the cannula produced. Generally, angles between about 20 and about are suitable with those betweenabout 30 and about 45 preferred. The length ofthe angleportiona. 18 will also depend on the desiredlength of the angledinlet tube. V I 1 The core 10 is attached to a core support, not shown, by bridge member 54 which is preferably;,-flat ,and extends along a side of the upper portion 12."1'he,location,of the 1 bridge member 54 is shown as extending from the end 17 w of the upper portion to somewhat belowqthe lower nipple. core portion 14, and opposite the nipple core portions 14 and 15. The length of the bridge 54 is important since if it does not extend beyond the lower nasal core portion 14".; the cannula cannot be easily removed from the core, as will be more fully explained hereinafter.

The location of the bridge"54"along the upper core portion 12 and relative to the nipple 'core portions 14 and 15 may be varied somewhat depending on the mold cavity and the length of the nipple core portions 14 and 15. Again, as shown, the bridge 54 is preferably opposite the nipple core portions 14 and 15. In that location, as the cannula is removed from the forming core 10, the nipple core portions 14 and 15 can directly exit through a lipped slot of the cannula formed by the bridge 54. However, the bridge 54 may join the upper portion 12 closer to the joinder area as of the nipple cores 1,4 and 15 with the upper portion 12 other "than as shown in H therefrom, separate transverse core 20,1 nipple core' 's 24 and 25 and angle core 22' are shown. The nipple cores 24 and 25 comprise rod-like extensions around Jwhich hollow nasal tips of a cannula'are formed ina previously I used mold apparatus. The transversecore 20 forms the hollow main tube portions of a" cannula while the angle,

core 22 forms the hollow a ng 1ed inlet tube of the cannula. In a cannula molding process using a state of the art core assembly as shown in FIG, 2, the individual coresff 22 and 26 are maintained in spacial relationship within" a hollow cannula mold as thermoplastic material, is in.

jected into the mold cavity. Just prior to material injection, the end of the angle core 22 is brought into contact with the side of the transverse core 29. Similarly, the rod,- like nipple core extensions 24 and 25 contact the side of the transversejpore 20, Bash: iof the'l cores '20, '22, 24 and 25 are attached to separate eore supports and corej'f slides, not shown. When the cores 'a're brou ght into, poi, sition, the fluid thermoplastic isinjected intoijthe "mold cavity and around the separate coresQThe thermoplastic is cured and the mold is opened. lluririglthe mold'ppe n' ing stroke, the transve" fromthe parting plane or part line of the mold lialve's'i we i et s j n tf." cylinder or other retracting niea'ns'jlthe angle core -2 2 'is" then'retracte'd, and the nipple cores are brought forward The cannula which is attached to the nipple cores is then peeled off.

The core of the present invention shown in FIG. 1 eliminates the requirement of separate forming cores shown in FIG. 2 thereby simplifying the molding apparatus since only a single unitary core is used. However, even more important is the elimination of internal flash in a cannula produced by the core of the invention as previously explained. Thus, by eliminating the assembly of separate cores 20, 22, 24 and 25 which must contact in order to form the hollow interior of a cannula, flash occurring around the areas of contact of the individual cores is avoided, thereby producing a superior cannula.

A cannula prepared by the use of the forming core of the invention is illustrated in FIG. 3. The cannula includes a hollow main tube portion 32, hollow angled inlet tube 36 joining and extending at an angle from the main tube 32, and hollow nasal tips 34 and extending substantially perpendicular from the axis of the main tube 32. The hollow interior of the main tube 32 communicates with the hollow interior of tips 34 and 35 and angled inlet tube 36.

An elongated portion 40, also part of the cannula body, terminates in a flattened end 39 while a similar flattened end 38 joins the exterior wall of angled inlet tube 36 where the latter joins the main tube 32. It will be noted that the elongated portion and flattened ends 38 and 39 lie generally along the axis of main tube 32. Each of these flattened ends 38 and 39 are for the purpose of maintaining the cannula in a fixed and comfortable position on a patient with the aid of an adjustable elastic strap, not shown, secured through openings 44 and on the respective flattened ends.

Referring to both FIGS. 3 and 4 the unitary forming core 10 (FIG. 4) is attached to a core support 52 by a bridge 54, which bridge in cooperation with the mold cavity forms a lipped slot 48 having a lip 42. This slot 48 is simply an elongated opening which enables the removal of the cannula from the forming core. When the mold halves are separated leaving the cannula formed on the unitary core, the cannula 30 is peeled from the core 10 by pulling the cannula in the area of the nasal tips 34 and 35 away from nipple core portions 14 and 15. Accordingly, the nipple core portions 14 and 15 are pulled through the slot 43 and parting lip 42. Once the nipple core portions 14 and 15 clear the lip 42 the cannula is pulled downward off of core portions 12 and 18 respectively. Thereafter, the lip 42 of the cannula is removed by sealing means which both cuts the lip 42 from the cannula body and seals the slot along seam 43 shown in FIG. 3. If necessary, any exterior flash may be trimmed from the cannula body. A strap is threaded through openings 44 and 45 of the flattened ends 38 and 39 and the cannula is ready for use.

It will be evident that the length of bridge 54 and in turn the lipped slot 48 should be suflicient to permit easy removal of the cannula from the core without exceeding the elastic limits of the thermoplastic material. In other words, the lipped slot 48 should permit withdrawal of the nipple core portions 14 and 15 therethrough without unduly stretching the cannula.

FIG. 4 illustrates a further embodiment of the invention utilizing a plurality of forming cores 10 shown in FIG. 1. The individual unitary forming cores 10 are attached to a removable rack device 50. The rack 50 comprises a primary rod 56 along which extend substantially evenly spaced core support rods 52. Attached along one side of each core support rod 52 is a bridge 54 to which is attached the forming core 10. Such a bridge is preferably flat, and relatively thin. It is the presence of the bridge 54 which causes formation of the lipped slot 48 on the cannula as shown in FIG. 3 and previously described. Pins 58 fit into recesses on a mold apparatus and hold the rack 50 in proper position or alignment until the mold is closed prior to injection of thermoplastic material.

The rack 50 is itself of unitary construction. Its advantage is not only to enable the simultaneous formation of a plurality of molded cannula devices but generally permits improved efliciency in a mold operation. For example, such a rack is removable from the cannula mold by simply disengaging the pins 58 from cooperating mold recesses. This may be done by hand or automatically during the phase when mold halves are opened or opening. Thus, an operator may then peel oil? the cannulae outside of the mold apparatus which is advantageous from both a convenience standpoint as well as for safety. Where two of such racks are used, a single operator can remove and inspect cannulae while the other rack is engaged in the molding operation. Thus, speed is also facilitated in such an operation.

Although the rack of FIG. 4 engages vfour forming cores any number may be used depending on the construction of the mold apparatus and the capacity of the machine used in the molding operation. Thus, the invention is not limited to the specific device shown but may incorporate fewer or more forming cores. Similarly, the rack may incorporate equivalent features other than those specifically shown to achieve substantially the same results.

A variety of thermoplastic materials may be used in forming a cannula according to the invention although polyvinyl chloride and polyvinyl acetate are usually preferred. These as well as alternative embodiments within the purview of the invention will be evidentto those skilled in the art.

I claim:

1. In a process for injection molding a nasal cannula having an elongated hollow tubular body and a pair of hollow nasal tips extending therefrom utilizing a mold cavity and forming means within said cavity, the improvement comprising the steps:

(a) forming the cannula on a unitary core having (1) an elongated portion terminating at an upper and lower end for forming the tubular body and having the shape of the nasal cannula body interior,

(2) a pair of relatively short rods spaced along the length of the elongated portion and extending therefrom, one of the rods being adjacent said upper end, for forming the nasal tips, and

(3) a bridge for securing said core to a core support means said bridge extending from approximately the upper end of said elongated portion to below the rods and forming a slot for removal of the cannula from said unitary mold core;

(b) stripping the formed cannula from the core bypulling the nasal tips from said short rods and 'removing the cannula. from said core through a lipped slot formed on said bridge and extending along a portion of said tubular body; and

(c) sealing the lipped slot.

References Cited CHARLES E. VAN HORN, Primary Examiner C. WESTON, Assistant Examiner US. Cl. X.R. l28206, 348*; 156-245; 249-63; 264-318, 328, 334

Shockey 264-318 l j

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4332264 *Mar 3, 1980Jun 1, 1982United Healthcare AssociationAutomated cleaning system for dialyzers
US4444596 *May 3, 1982Apr 24, 1984Norman GortzAutomated cleaning method for dialyzers
US4444597 *Apr 30, 1982Apr 24, 1984Norman GortzAutomated cleaning method for dialyzers
US5225215 *Aug 3, 1992Jul 6, 1993Syvrud Daniel JPlastic molding apparatus
U.S. Classification156/242, 249/63, 264/334, 156/245, 264/318
International ClassificationA61M16/06, B29C33/76, B29C45/26, B29C37/00
Cooperative ClassificationB29C33/76, B29C45/26, A61M2210/0618, B29C37/0014, A61M16/0666
European ClassificationB29C33/76, B29C45/26, A61M16/06L, B29C37/00B3
Legal Events
Jun 8, 1993ASAssignment
Effective date: 19920914
May 9, 1990ASAssignment
Owner name: HOMEFED BANK, F.S.B.
Effective date: 19900509
Mar 28, 1990ASAssignment
Effective date: 19900209