| 摘要 |
This invention relates to a coil spring-type connecting device which may be used to connect two pieces of material together, as an expansion bolt, for example, in masonry; as a quick-operating clutch; or a tube connector; or the like. Coil spring invention devices are known as are also the use of double coil springs. The present invention differs from the prior art in that the complete device comprises two coil springs formed of flattened wire. The two coils are identical, except that the long axis of the flattened wire is tilted at opposed angles to the perpendicular axis of the coil. That is, one coil formed of flattened wire has what might be called a "positive" angle (such as facing to the right in the various figures) to the axis of the cooperating bolt, while the second coil has a negative angle (such as facing to the left). Preferably, the pitch of both coils is identical, and in the preferred form the pitch is approximately twice the distance which a single coil occupies axially of the device. Usually a preferred angle for the two coils is approximately 60 DEG , as shown in FIGS. 2, 5, and 6, but it can be any other angle, such as approximately 30 DEG shown in FIG. 4. The coils can be made of flat strip as shown in FIG. 5 and the pitch can be larger than normal, so that the individual coils are spaced apart as shown in FIGS. 6 and 7; and in fact, a spacing or third coil may be placed between the angular coils and lying flat against the cooperating bolt. It is believed obvious that compression of the spring will twist the normal angle from that shown in FIG. 2 to that shown in FIG. 3, whereby the coil tightly engages the hole or cavity in which the connecting device is placed. If the coils are made of flat strip, as shown in FIG. 5, it is obvious that the edges of the coils will cut into one or the other or both of the cooperating members, i.e., the bolt or the cavity. When the connecting device is to be used for an expansion bolt in masonry, brickwork, or other material which has a tendency to crumble, it is preferred that the coils be spaced apart as shown in FIGS. 6 and 7, so that material displaced from the cavity wall by the expansion of the connecting device will have a place to rest without interfering with the actions of the coils.
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