At present, foreign industrial developed countries generally adopt the "linear" drawing die proposed by American T.Maxwall and E.C.Kennth in the early 80, from the measurement of this kind of drawing die produced abroad, the characteristics of its pore type mainly have the following 4 aspects
(1) Cancel the lubrication area, increase the working area, and classify the function of establishing the lubrication film into the inlet area and the working area.
Extend the height of the inlet area and the working area so that the silk material enters the middle section of the working area, and use the wedge angle formed in the inlet area and the upper part of the working area to establish a "wedge-shaped effect" to form a more dense and firm lubrication film on the surface of the silk material to improve the lubrication effect
(2) The longitudinal profile line of each part of the hole type must be straight, and the handover between the regions is obvious, especially between the working area and the fixed diameter area should not have the transition angle.
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Because the arc type drawing die has a large die angle at the entrance of the mold, the compressive stress on the die wall increases, so it is easier to form a darker annular groove than the linear drawing die.
(3) The fixed diameter area must be straight and reasonable in length. The straight fixed diameter area can avoid the external friction caused by two compression deformation, which increases the wear. The length of the fixed diameter area also has an effect on the life of the mold.
Although the length of the fixed diameter area can improve the heat dissipation efficiency and service life of the drawing die, it will increase the tensile stress of the friction force and cause shrinkage or broken wire.
And the fixed diameter area is too short, the size accuracy and surface quality of silk material is difficult to protect
The mold hole will also soon wear out the variance.
(4) Increase the angle of the inlet area beta prevents lubricant, metal chips, dirt and so on from accumulating at the junction of the inlet area and the work area due to the small angle of the inlet area, forming a wedge-shaped plugging cold, resulting in a deterioration of the lubrication conditions.
However, if the angle of the inlet area is too large, it will affect the overall strength of the diamond drawing die.
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