| 摘要 |
A composite box end wrench has a non-metallic body including a handle portion and at least one head portion which defines a fastener-receiving opening therethrough. The wrench includes strengthening and/or retaining structure which strengthens the head portion and can change the failure mode to confine wrench parts in the event of failure. In one embodiment each head portion has a fastener-engaging member insert molded therein along with a reinforcing plate which encircles the member and preferably extends slightly into the handle portion. The reinforcing structure could alternatively be a band extending the length of the wrench and encircling the fastener-engaging member (or members in a double-ended wrench). In a ratcheting version of the wrench the non-metallic body may be split lengthwise into two parts, each of which has reinforcing structure embedded therein, the fastener-engaging member being a ratchet gear which, along with an associated pawl, is disposed between the body parts. The parts may either confine or expose a peripheral portion of the gear, and the reinforcing structure encircles hub portions of the pawl and gear to the hold them together. The body parts may be secured together by various means, including pinning, ultrasonic welding and snap-fitting. The wrench body may be provided with an outer non-metallic sheath, in addition to or in lieu of the reinforcing structure, which sheath covers at least the handle portion of the body.
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