System for producing spring coils with two reduced diameter end sections

Abstract

A coil spring forming system allows for forming reduced diameter ends at both ends of a coil spring in a single forming process. A rotating member supports one end of the coil spring and preferably includes a die portion that establishes a configuration of that end of the coil spring. A pitch controlling device guides the coil stock longitudinally along the axis of the spring as the rotating member rotates to establish the desired pitch of the coil spring. A moving mandrel member is guided along an axis of the coil spring so that the mandrel member and the pitch controlling member establish the desired diameter of the spring at the corresponding portion of the spring. The mandrel member preferably has a forming surface with a varying outside dimension so that, depending on the placement of the mandrel relative to the coil stock and the pitch controlling member, the diameter of the resulting coil spring can be varied along the length of the spring. A controller preferably coordinates movements of the rotating member, the pitch controlling member and the mandrel member to establish the desired coil spring configuration in a single forming process.

We claim:  
     
         1 . A device for making a coil spring, comprising: 
 a rotating member that is adapted to support one end of coil stock;    a pitch controlling member that is adapted to contact the coil stock such that the pitch controlling member establishes a pitch of the coil spring along an axis of the spring; and    a mandrel member having an outside dimension that varies along a length of the mandrel member and that is moveable parallel to the axis of the spring, the pitch controlling member cooperating with the mandrel member to establish a configuration of the coil spring.    
     
     
         2 . The device of  claim 1 , including a controller that controls movement of the mandrel member and the pitch controlling member such that the coil spring configuration is as desired.  
     
     
         3 . The device of  claim 2 , wherein the controller controls movement of the rotating member.  
     
     
         4 . The device of  claim 1 , including a finishing member that is adapted to keep an end of the coil stock opposite from the one end supported by the rotating member in conformance with a corresponding portion of the mandrel member to establish the configuration of the corresponding end of the coil, the finishing member being selectively moveable relative to the mandrel member.  
     
     
         5 . The device of  claim 1 , wherein the rotating member includes a die portion that has a shape that establishes the configuration of the coil spring at the end that is supported by the rotating member.  
     
     
         6 . The device of  claim 1 , wherein the mandrel member is at least partially conical having a first end and a second, larger end and wherein the first end is oriented toward the rotating member.  
     
     
         7 . The device of  claim 1 , wherein the pitch controlling member is moveable in at least two directions relative to the axis of the coil spring.  
     
     
         8 . The device of  claim 7 , wherein the pitch controlling member is independently moveable parallel to the coil spring axis and perpendicular to the coil spring axis.  
     
     
         9 . A method of forming a coil spring, comprising the steps of: 
 (A) rotating a piece of coil stock;    (B) guiding the coil stock axially along an axis of the coil such that a desired pitch is established along a length of the coil; and    (C) varying an outside dimension of the coil turns by moving a mandrel member that has a varying outside dimension axially relative to the coil stock and causing the coil stock to conform to a corresponding portion of the mandrel member.    
     
     
         10 . The method of  claim 9 , including providing a rotating member that supports one end of the coil stock, a pitch controlling member that guides the stock to establish the desired pitch and coordinating movements of the rotating member, the pitch controlling member and the mandrel member to achieve the desired coil configuration.  
     
     
         11 . The method of  claim 9 , including supporting one end of the coil stock on a rotating member and forming a first end of the coil using a die portion of the rotating member.  
     
     
         12 . The method of  claim 9 , including establishing a first reduced diameter near ends of the coil spring and establishing a second, larger diameter near a central portion of the coil spring.  
     
     
         13 . The method of  claim 12 , including forming the entire coil in one forming operation.  
     
     
         14 . The method of  claim 12  including heating the coil stock before performing steps (A) through (C) and cooling the coil spring immediately after performing step (C).