Needle with protector

An interfitting rib structure on a hypodermic needle and its protector which have beveled ends to rotationally shift the needle and protector into proper alignment during high speed assembly.

BACKGROUND 
It is known to mount hollow protectors on the hub of hypodermic needles as 
illustrated by U.S. Pat. Nos. 3,390,759; 3,333,682; and 2,677,373. These 
patents also describe an interfitting rib structure between the protector 
and needle hub forming a "wrench" effect to rotationally lock the needle 
to the protector. Thus, a nurse or physician can twistingly wedge the 
needle hub onto a syringe adapter by twisting the protector without 
manually touching the protector encased needle. 
When the protector is mounted on the needle hub, it must have a proper 
rotational orientation to the needle hub in order for the interfitting 
ribs to mesh. This is no problem with manual assembly because the operator 
can simply twist the protector until the protector ribs fall into place 
between ribs on the needle hub. 
In recent years disposable plastic syringes, which are used for a single 
injection and then discarded, have come into very wide use. In order to 
keep the cost of such syringes sufficiently low; i.e., only a few cents, 
very high speed assembly machines are required. Such machines have a 
certain degree of vibration that tends to help jostle the syringes and 
needles into proper alignment. However, sometimes end surfaces on the 
protector and needle ribs will come into an end to end abutting 
relationship preventing assembly. When this happens, the assembly machine 
jams, requiring the efforts of an operator to manually unjam the machine. 
Such jamming is costly in the manufacture of disposable hypodermic 
syringes. 
SUMMARY OF THE INVENTION 
The above problems of jamming in high speed production machinery have been 
overcome by including rotational shifting surfaces (such as beveled) at 
the ends of the ribs in the protectors and on the needle hub. Such bevels 
substantially reduce the area of the rib ends which could come into 
abutting relationship, making it extremely rare for such to occur during 
assembly. Additional structure of lead-in ramps to the beveled ends of the 
hub ribs help center the needle hub in the protector cavity during 
assembly.

DETAILED DESCRIPTION 
FIG. 1 shows a hollow needle protector 1 wedgingly mounted on a needle hub 
2, which is in turn wedgingly fitted on a tapered adapter 3 of a syringe 
4. As previously mentioned, an interconnecting wrenching structure between 
protector 1 and hub 2 permit the operator to grasp the protector 1 and 
twistingly assemble or disassemble the needle to tapered adapter 3. 
FIG. 2 shows the internal rear section of the protector which includes a 
series of ribs, such as 5, 6, and 7. This protector would have four ribs, 
but any number of ribs could be used. A rearward end portion, as shown in 
rib 6, includes beveled surfaces 8 and 9, causing a rearward most end of 
rib 6 to have a very narrow transverse area. At a forward end of a rib are 
bottoming shoulders, such as 11, which can abut the needle hub's ribs to 
limit how deep the hub can be inserted into the protector. For gas 
sterilization, a series of longitudinal vent ribs, such as 12 and 13, 
could be used. 
The hub 2 in FIG. 3 has a forward section 15 which is joined to a cannula 
16 by an epoxy 22. This forward section 15 of the hub has a series of 
upstanding longitudinal ribs 16a and 17. This hub could be separately 
formed and attached to a syringe barrel as shown, or could be an integral 
hub portion of the syringe barrel. A forward end of rib 17 includes 
beveled surfaces 18 and 19 forming a very narrow forward end 20 of rib 17. 
Thus, during assembly it is highly unlikely that narrow rearward end 10 of 
rib 6 in the protector would abuttingly engage the narrow forward end 20 
of hub rib 17 and cause the assembly machine to jam. 
A prospective view of rib 17 in FIG. 4 shows more detail of this structure. 
The needle hub also preferably includes a tapered lead-in ramp 21 to help 
center the hub and the protector. A forward section of lead-in ramp 21 
blends with a generally conical shaped epoxy bond 22. 
In the foregoing description, double beveled surfaces on the tip of the 
ribs have been described. It is also within the scope of the invention to 
use a single bevel in which a narrow tip is adjacent one side of the rib. 
Also, a generally semi-circular tip end of the ribs would substantially 
decrease their chance of end to end abutting contact. The important thing 
is to substantially reduce the transverse area of the rib at its tip from 
that of the rib body to minimize jamming during assembly, by automatic 
rotational shifting of the hub and protector during axial assembly. 
In the foregoing description, a specific example has been used to describe 
the invention. However, it is understood by those skilled in the art that 
certain modifications can be made to this example without departing from 
the spirit and scope of the invention.