The present invention relates to a method and a construction capable of detecting a molding defect in an elastic lance formed within a terminal receiving chamber of a connector when a terminal is inserted into the terminal receiving chamber, and more particularly to such method and construction for detecting a molding defect in the lance by hindering the insertion of the terminal.
Usually, a terminal inserted into a terminal receiving chamber in a connector housing is retained in a double manner so that the terminal can be positively retained against rearward withdrawal.
As shown in FIG. 4, an elastic lance 3 in the form of a retaining arm is provided within a terminal receiving chamber 1, and is integrally connected at its proximal end to a connector housing, a distal end of the lance 3 being free. The distal end portion of the lance 3 projects into the terminal receiving chamber 1, and a projection or beak 5 is formed on the distal end of the lance 3, and projects into the terminal receiving chamber 1. The beak 5 serves as retaining means for retaining a terminal 9 in the terminal receiving chamber 1.
A pair of side beaks 7 are formed on opposite side surfaces of the lance 3, respectively, and each side beak 7 has a front vertical abutment surface 7a, and a gently-slanting surface 7b at a lower side thereof.
The terminal 9 to be inserted into the terminal receiving chamber 1 includes a plate-like or pin-like electrical contact portion 11 at its front end, and a tubular base portion 13 provided rearwardly of the electrical contact portion 11. A retaining hole 15 is formed in that portion of the base portion 13 that can face the lance 3, and the beak 5 of the lance 3 is engageable in this retaining hole 15. A pair of retaining piece portions 17 are formed at opposite sides of the retaining hole 15, respectively. The retaining piece portions 17 are formed, for example, by raising stamped-out portions formed as a result of the formation of the retaining hole 15.
In such a terminal double-retaining construction, when the terminal 9 is inserted into the terminal receiving chamber 1, the electrical contact portion 11 advances in sliding contact with the beak 5 to urge or flex the beak 5 to thereby flex the lance 3 away from the bottom of the terminal receiving chamber 1. At this time, the side beaks 7 are also displaced away from the bottom of the terminal receiving chamber 1 beyond the retaining piece portion 17.
Then, when the retaining hole 15 in the terminal 9 reaches the beak 5, the lance 3 is elastically restored, so that the beak 5 is engaged in the retaining hole 15, and also the abutment surfaces 7a of the side beaks 7 are engaged with rear edges of the retaining piece portions 17, respectively, thus completing the double retaining of the terminal 9.
In the molding of the connector housing having the integral lance 3, if the filling of a molding material (synthetic resin) in a mold is affected for some reason, the synthetic resin fails to be fully filled up to an extremity of a mold cavity, so that the resultant molded product may be defective in that it lacks a distal end portion.
In such a case, the lance 3 does not have the beak 5 as shown in FIG. 6, and therefore upon insertion of the terminal 9, the electrical contact portion 11 can not contact the beak 5 of the lance 3, and hence the lance 3 can not be displaced.
In the conventional double-retaining terminal construction, however, even if the lance 3 has such molding defect, the terminal is retained in position within the terminal receiving chamber by the side beaks 7, as shown in FIG. 7. Thus, even without the beak 5 at the distal end of the lance 3, the retaining piece portions 17 of the inserted terminal 9 advance in sliding contact with the slanting surfaces 7b of the respective side beaks 7 to urge the side beaks 7 upward. As a result, the retaining piece portions 17 are retained by the side beaks 7 in a normal condition (see FIG. 5).
In such a retained condition in which the terminal is retained only by the side beaks 7, the retaining strength is much lower than in the double-retained (or completely-retained) condition. The result is that upon application of an external force to the terminal 9, the terminal 9 can be easily withdrawn.
However, it is very difficult to find such a defective connector, having the terminal held in a pseudo-retained condition, at a later stage.