| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a cold drawn wire which is free of degradation in quality by providing another die for finishing wire drawing after a die for finishing drawing and an eddy current test equipment, and changing the reduction rate of area of the pre- and post-finishing drawing. SOLUTION: In the finishing wire drawing/eddy current test process, the finishing drawing by a die 2 for pre-finishing drawing for a coated wire 1 is set about 2-20% range of reduction of area, while the finishing drawing by a die 4 for post-finishing is about 1-10%. In addition, it is desirable to set the distribution of the reduction of area as 80 to 55% versus 20 to 45% between the pre- and post-finishing drawing. The probe 3 of the eddy current test is provided near the die 2 for pre-finishing drawing, with its distance to the post- finishing drawing provided such that the drawing machine stops by flaw detection and that a flaw removal measures can be taken. As a result, a lubricating coating is secured necessary for a cold processing, enabling such cold drawn wire for bearing to be obtained that is guaranteed for a flawless surface.</p> |
