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Wiredrawing mold's structure

　　Domestic has introduced the industrially advanced country manufacture wiredrawing mold and the corresponding nib instrumentation one after another. Through to the overseas wiredrawing nib's analysis, makes us to understand the modern wiredrawing nib the design concept, to raise our country wiredrawing mold's design level to provide has used for reference.

　　1. In wiredrawing mold hole structure

　　The silk mold core's structure may divide into “the entrance region, the lubrication area, the work area according to the job category, to decide the diameter area, the outlet area” five sectors. The wiredrawing mold's inside diameter outline is very important, it was deciding reduces pulling force which the wire rod needs, after and affects draws, in the wire rod residual stress. The mold core various areas' function respectively is: The entrance region, facilitates threads and prevents the steel wire to abrade the wiredrawing mold from the entrance direction; The lubrication area, causes the steel wire easy through it to lead the lubricant; The work area, is the nib main part, the steel wire distortion process carries on here, is soon primitive the section size which the section reduces requests. When draws the circular conical surface metal, in the work area the metal volume occupies the space is a frustum, this space is called the deformation range. In the work area circular cone half-angle Alpha (is called nib half-angle) mainly to use in determining the pulling capacity the size; Decides the diameter area the function to lie in obtains is drawn the steel wire accurate size; The outlet area is uses in preventing the steel wire export not steadily, but abrasion steel wire surface.

　　2 straight line and arc mold's discussion

　　The widow crawls the silk speed enhancement, the wiredrawing mold's service life becomes the prominent question. American T Maxwall and E G Kennth advanced the adaptation high speed wiredrawing new wiredrawing nib theory, namely “straight line” theory. Has the following characteristic according to this theory manufacture's wiredrawing mold:

　　Yan Wosui, the lubrication area combine, have cause the tendency which the lubrication angle reduces, before causing the lubricant to enter the work area, to receive certain pressure, thus has the better lubrication effect.

　　Shen Wosui and the work area lengthen, establishes the good lubrication pressure, its angle carries on separately according to the wiredrawing material quality and each while going along compression ratio optimal.

    Disputed what was big was the work area shape and the work area with decides the diameter area intersection point the shape. Many people are right “the straight line” the mold to hold the affirmative attitude. But the author thought that two types the wiredrawing molds have the situation which the respective characteristic and is suitable, does not analyze draws the conclusion, end exempts has loses biased.
Cause the metal to be more winding in deformation range flowing, causes the attachment detrusion and unnecessary work of deformation enlargement, subsequently will cause the drawing stress to increase (compares “straight line” mold to increase 10~30% generally). But “the straight line” on the mold work area contour line each spot slope is the same, when like this we had determined when best work area circular cone half-angle Alpha, then may draw the metal under the smallest stress condition; But “arc” mold, because on its contour line each spot curvature is different, therefore is unable to cause the entire work area to have this kind of best work area circular cone half-angle Alpha. From is advantageous and reduces the drawing stress in the metal flowing angle embarking, at present overseas when the while going along compression ratio is 10~35% (majority tinsel's distortions within this scope) and draw, the thick specification tinsel, generally uses “the straight line” the work area.

   The metal in the hole distortion may increase along with its work hardening degree reduces gradually, on the opening wall pressure distribution and the attrition are quite even, therefore “the arc” the work area resistance to wear is good. Specially covers the road the second rolling coefficient of contraction is small when (is smaller than 10%), the use “the arc” the work area, may obtain the enough long deformation range in the work area circular cone half-angle Alpha small situation. Adds it “the arc” the work area to have the adaptiveness strong characteristic, therefore when the while going along compression ratio is big (is bigger than 35%) or small (is smaller than 10%) and draws the steel wire, should use “the arc” the mold.