US Patent No. 10,987,721

METHOD OF MANUFACTURING COIL SPRING AND COIL SPRING MANUFACTURING APPARATUS


Patent No. 10,987,721
Issue Date April 27, 2021
Title Method Of Manufacturing Coil Spring And Coil Spring Manufacturing Apparatus
Inventorship Takehito Takahashi, Kanagawa (JP)
Assignee

Claim of US Patent No. 10,987,721

18. A cold-forming coil spring manufacturing apparatus comprising: a rotating body having an outer circumferential surface against which a wire rod being fed straight out is serially pressed for forming into a coil shape, the rotating body being connected to a rotary drive source such that the rotating body is rotated around an axis of the rotating body, the rotary drive source rotationally driving the rotating body as the wire rod is fed straight out, the rotary drive source being set in relation to the rotary drive of the rotating body such that a portion pressed against the wire rod on the outer circumferential surface of the rotating body moves toward the same side as the advancing side of the wire rod, the coil spring manufacturing apparatus comprising a shaft-shaped pitch processing tool pressed against the wire rod to displace the wire rod in an axial direction of the coil spring to be formed for performing pitch processing when the wire rod is formed into a coil shape, the pitch processing tool being connected to a pitch processing tool rotary drive source such that the pitch processing tool is rotated around an axis of the pitch processing tool, the pitch processing tool rotary drive source rotationally driving the pitch processing tool as the wire rod is fed out, the pitch processing tool rotary drive source being set in relation to the rotary drive of the pitch processing tool such that a portion pressed against the wire rod on an outer circumferential surface of the pitch processing tool moves toward the same side as the advancing side of the wire rod, wherein the pitch processing tool rotary drive source is adjusted to set a circumferential speed of the outer circumferential surface of the pitch processing tool to about a feed speed of the wire rod by using the feed speed of the wire rod as a target value, wherein the rotating body is a single rotating body, wherein a wire rod guide having a body including a guide hole straightly feeds out the wire rod, and stationary winding tool disposed adjacent to the wire rod guide winds a wire rod fed out from the wire rod guide into the coil shape, and wherein the wire rod is curved only by the stationary winding tool and the single rotating body between a first point (P1) corresponding to an exit of the wire rod guide and a second point (P2) corresponding to a closest point between the winding tool and the rotating body.