Releasable latch for plastic mold clamshell parts
Rotary latch for a clamshell housing with truncated circular upper and lower lugs, that can if desired, be made in a single plastic mold and rotatably attached to the housing without any rivets, pins or screws.
The upper lug has an arcuate extent of more than 180 degrees and the lower lug has an arcuate extent coaxial with the upper lug but less than 180 degrees. The latch is an annular plastic body that is deformed to snap over and rotatably mount on the upper lug, effected by an annular recess in the body that extends 360 degrees inside around the body so as the body rotates on the upper lug, it never loses contact over any portion thereof. The lower lug is axially offset from the upper lug and the latch body has a latch cup portion that scoops and aligns the lower lug with the upper lug in three orthogonal coordinates. The latch cup portion is also axially offset from the upper lug so it can pass behind the upper lug as the latch body is rotated from a latch position to a release position.
With the increasing popularity of selling products in packages that can be used after purchase to store and organize the product, there is an increasing need to develop fasteners for releasably holding the package in a closed position. Instead of referring to such devices as packages or packaging herein, they are in reality organizer housings, and the most common takes the form of a plastic housing made in mating halves, hinged at one side, and selectively fastened at the other; in short, a suitcase or brief case type assembly but at a lower cost, because the product housed, for example, may be a set of socket wrenches selling retail for $12.99 U.S., so a package for a product of this type cannot substantially increase the retail price of the housed assembly above the cost of the selling price of the sockets alone, or the customer will simply purchase the socket set without the releasable housing.
There have, in the past, been designed housings for this purpose, and one is a polyurethane clamshell housing for a socket set that includes lugs integrally molded with the housing halves, and linearly slidable clasps slidably mounted on one of the lugs which capture the other lug as it is shifted linearly.
This design is attractive from an economic standpoint because it requires a simple, one-piece plastic mold for the clip or clasp. But on the negative side, alignment of the lugs is very difficult and usually requires the manual bending of portions of the housing to align the lugs to a position where the lug can, in fact, be captured by the sliding clasps.
The present one-piece rotary latch seeks to over-come not simply the inadequacies in the one-piece sliding latch described above, but also the deficiencies in multiple piece rotary latches whose deficiencies are already evident by that description and others are present that will become apparent herein.
The prior art of rotary latches falls into two fairly well-defined categories; the first being the most conventionally styled latches that have a rotary pivot post or pin carried by the associated housing that serves as a support for the latch on the housing and also the rotary bearing between either the latch and the post or the post and the housing. These latches are usually somewhat unstabled because they are bearinged only at a very narrow central portion on the housing, and they are not suitable for low cost latches because they usually require the manufacture of three or more parts.
In the second category of latches, an upper lug is provided for rotatably mounting the latch. In these designs, a central fastener is required in addition to the upper lug because as the latch is rotated to the unlatched position, the latch loses contact with a large part of the upper lug.
In accordance with the present invention, an improved rotary latch is provided for a clamshell housing with truncated circular upper and lower lugs that can, if desired, be made in a single plastic mold and rotatably attach to the housing without any rivets, pins, screws or separate bearings. The upper lug is integrally molded with the housing and has an arcuate lip or rim that extends more than 180 degrees, and the lower lug has an arcuate extent and similar lip coaxial with the upper lug, but less than 180 degrees in extent.
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