The present invention relates to spring forming apparatus for producing coil springs having concurrently formed end loops and, more particularly, to spring forming apparatus equipped with an auxiliary digital feed assembly for supplementing the mechanical feed assembly.
A spring forming machine similar to that described in U.S. Pat. No. 3,025,889 is currently available from and being produced by The U.S. Baird Corporation, Stratford, Conn., under the trademark SprinGenerator.RTM. as their Model No. 1. The basic advantages of this machine is that a complete spring, including the two end loops and the central coil body portion, can be manufactured in a single cycle or operation. The machine utilizes a mechanical feeding operation to feed wire and control the wire forming tooling. The operation incorporates cam followers cooperating with adjustable cams to control the plurality of wire forming tools to produce the coiled springs with end loops. The tools are movable into and out of operative position in front of an orifice provided in a wire guide through which the wire is fed. In their operative positions, the tools are positioned to deflect the wire in different directiors to form the desired spring configuration. The completed spring is severed from the wire stock by a cutoff tool and the operation is performed on the succeeding length of wire. The mechanical drive mechanism to produce these movements is similar to the mechanisms described in U.S. Pat. Nos. 3,025,890 and 3,025,891.
The prior art machine adequately produces the same spring at a very rapid rate (720-6400 pieces per hour) and once properly set up can be run continuously making such springs. The machine is excellent for large production runs of the same spring; however, to change the number of coils or to add lengths of the wire to the end loops requires repositioning of all the cams and changing the feeding setup for the wire length by changing the feed-gearing ratio. This is a somewhat time-consuming process which must be undertaken with a considerable amount of skill and dexterity.
It would be highly desirable to overcome this setup limitation of the prior art machine by permitting the interruption of the mechanical feed for the tooling and wire feed described above and using an auxiliary feeding drive to feed additional wire at appropriate points during the production of the individual springs. This would enable the operator to produce a family of springs having variations in the number of coils and the length of the loop extensions.
It is an object of the present invention to provide a novel spring forming machine which allows a selected amount of wire to be added to a spring in several places during the spring forming process once the machine is initially set up to produce a basic spring.
It is also an object to provide such a machine which reduces changeover time to produce a family of springs having a wide variety of coil body and end loop portions.
Still another object is to provide a machine which runs as a conventional spring forming machine or as a digitally controlled machine, thereby significantly increasing the versatility of the machine.
A further object is to provide such a digital feeding accessory which can be installed as original equipment or readily applied to existing spring forming machines.
An additional object is to provide an accessory which may be fabricated readily and relatively economically and which will enjoy a long life in operation.