Key words: Diamond|Wiredrawing|Stainless steel|Electric cable

Abstract: The diamond wiredrawing mold is the stainless steel wire rod and the electric cable profession production important tool, especially applies in the fine lace and the micro silk aspect extremely widely. But because its price is very expensive, the production cost is high, how enhances the diamond wiredrawing mold's service life is effectively the wire rod produces the profession a big important topic.

The diamond wiredrawing mold is the stainless steel wire rod and the electric cable profession production important tool, especially applies in the fine lace and the micro silk aspect extremely widely. But because its price is very expensive, the production cost is high, how enhances the diamond wiredrawing mold's service life is effectively the wire rod produces the profession a big important topic.

1 diamond wiredrawing mold synopsis

The diamond wiredrawing mold has two kinds, one kind is the rough diamond mold, the rough diamond has degree of hardness to be high, the wear resistant good characteristic, the drawing wire rod surface smooth finish is very high, because the rough diamond has the aeolotropy in the structure, causes its degree of hardness also to assume the aeolotropy, causes the nib the attrition to be non-uniform, product not round entire, the price is in addition expensive, is scarce, generally serves as the surface quality to request the high fine lace back guy mold or the end product back guy mold; Another kind is the man-made crystal combination diamond mold, the man-made crystal combination diamond is the astatic polycrystal. It has degree of hardness to be high, the resistance to wear is good, anti-impact ability strong merit. Does not have the aeolotropy in degree of hardness, wears evenly, the mold service life is long, is suitable for draws high speed. Because the domestically produced crystal combination mold semifinished product existence crystal grain is thick, quality questions and so on polishing performance difference, the domestic factory multi-use crystal combination mold makes the transition mold at present, but does not serve as the end product mold. But along with the crystal combination mold intrinsic quality and the processing level's enhancement, has the tendency which the substitution expensive natural Jin'gang stonemason's workshop end product mold uses.

2 diamond wiredrawing mold's attrition reason analysis

2.1 wiredrawing mold own processing qualitative factors causes the mold attrition

(1) diamond mold semifinished product and the mold steel bushing crustification is asymmetrical, the agglutination hard alloy steel bushing distributes non-uniform or has the crevice, easy to cause to draw in the wire rod process to have the U shape fissure;

(2) diamond mold semifinished product in the laser drilling process, the agglutination trace cleaning up unclean or will be heated non-uniform will cause in the Jin'gang riddlings the metal catalyst, the cement and so on to gather a pile, such easy to cause in the drawing process the mold to present the pit;

(3) mold roll pass design is unreasonable, the entrance lubrication area opens the mouth, the stereotypia area to be excessively long too small, will cause the lubrication to be impeded, causes the mold to wear even disrupts.

in 2.2 drawing processes does not use, when the factor causes the mold attrition

(1) wiredrawing area reduction rate is oversized, causes the mold to have the fissure or stave. The fissure or breaks the crack major part is the internal stress release produces. In any material structure, the existence internal stress is inevitably, draws when the wire rod produces the internal stress may strengthen the diamond micro-crystallic structure originally, but when the wiredrawing area reduction rate oversized, is unable to lubricate promptly, thus temperature rise Gao Jiuhui has caused the diamond mold to indicate that the partial materials move away, the micro-crystallic structure withstands the stress greatly increases, causes it easier to have the fissure or stave.

(2) wire rod's stretch spool thread and the nib middle line is asymmetrical, causes has the stress to the wire rod and the back guy mold to affect non-uniform, but the mechanical vibrations produce the impact also becomes the very high stress peak value to the wire rod and the back guy model, both will accelerate mold's attrition.

(3) the wire rod degree of hardness which non-uniform creates because of the annealing non-uniform and so on factors easy to cause the diamond wiredrawing mold premature to have the fatigue damage, forms the ring-like trench, the aggravating nib attrition.

(4) wire rod surface roughness, the superficial adherency oxide layer, the sandy soil or other impurities and so on will cause the mold excessively quickly attrition. When wire rod through nib, hard, the crisp oxide layer and other adherency impurity will look like the grinding compound to create the back guy mold nib very quick attrition and the abrasion wire rod surface equally.

(5) lubrication impeded or the lubricating oil includes the metal detritus impurity to cause the mold attrition. Lubricates impeded will cause when the wiredrawing the diamond nib surface temperature to elevate excessively quickly, the diamond crystal grain will fall off, causes the mold damage. When the lubricating oil is impure, when the metal detritus which especially includes draws when falls off, extremely easy to scratch the mold and the wire rod surface.

3 enhance the diamond wiredrawing mold's service life method effectively

3.1 select the advanced mold process technology production as far as possible the high quality diamond wiredrawing mold

At present, the overseas back guy mold's attrition craft uses the high speed mechanical grinder generally, as well as the surface plates the diamond the metal to rub the needle, this equipment movement is steady, rubs needle's specification and the use standardization causes the product precision to be higher. Mold's pass size examines using the outline recording instrument and the aperture measuring instrument, and inspects the superficially attractive fineness with the inspection back guy mold special-purpose microscope. But the domestic many factories are also using the backward equipment, the use manual operation grinds the pass, therefore, has the following problem: The pass parameter fluctuation is big, processes the straight work awl with difficulty; Decides the diameter area and the work area interface point easy to grind the transition angle, causes the wire rod to decide in the diameter area to have two compressions, outside increases the friction force, lessened has decided the diameter area length, reduced mold's service life; The attrition rubs the needle repair frequency to be different from person to person, uses not standard, causes the pass the uniformity to be bad. The examination method also falls behind, can only depend upon the range estimate or the magnifying glass, the microscope and so on simple tool examination, what moreover pays great attention is the mold internal surface smooth finish, cannot examine effectively to the pass size, was far from controls.

3.2 choice good roll pass design diamond wiredrawing mold

The wiredrawing nib divides into the curve generally (i.e. the R series) and the straight line (i.e. conical series). Like the chart shows:

Attempts the back guy nib type

From the wire rod in the back guy mold internal strain even angle analysis, as if the curve compares the straight line to be good, this kind of pass is in “the smooth transition” under the theory instruction designs, its pass structure may divide into “the population area” according to the job category, “the lubrication area”, “the work area”, “to decide the diameter area”, “the date area” five parts, each intersection point request “the chamfer”, the smooth transition, ground the entire pass, to have in a big way the different curvature orphaned surface this kind of pass mold under the drawing speed condition then, might be suitable. To the late-1970s to the early 80s, along with the back guy speed's enhancement, the back guy mold's service life has become the prominent question. In order to adapt the high speed back guy request, US's T.Maxwall and E.G.Kennth proposed “the straight line” the theory. This theory had considered emphatically draws in the process lubrication and wears the factor, points out the straight line back guy nib should have the following several characteristics after the improvement:

(1) pass various part of lengthwise section line must be straight, the straight work conical surface pulling capacity is smallest;

(2) mold various spots' connection part must be obvious, like this various part may play the respective role fully, avoided the transition angle to deciding the diameter area virtual length reduction;

(3) extension entrance region and the work area altitude, causes the wire rod to enter the nib work awl's compartment, forms the wedge-shaped area using the entrance cone angle and the work cone angle first half part, the establishment “the wedge-shaped effect”, forms a more compact reliable lubricant film in the wire rod surface, reduces wears, suits in draws high speed;

(4) decides the diameter area to straight, and the length is reasonable. Decides the diameter area to be excessively long, the back guy friction force increases, after the wire rod pulls out the nib, easy to cause the reducing or the broken line, decides the diameter area to be excessively short, obtains the shape to be stable with difficulty, the size is precise and the surface quality good wire rod, simultaneously the nib also very will quickly wear the out-of-tolerance.

After the practice application, uses the straight line theoretical design back guy mold, its service life enhances above 3-5 times compared to the R back guy mold.

3.3 drawing machine equipment install the use to be reasonable

(1) drawing machine installs the foundation to be very stable, avoids vibrating the phenomenon;

(2) installs when must make the wire rod through the debugging the stretch spool thread and the nib middle line is symmetrical, causes the wire rod and the back guy mold stress function is even;

in (3) back guy process avoids starting frequently stops, because draws the friction which time the start tensile stress creates the normal drawing time friction to be much bigger than, this will increase mold's attrition inevitably.

3.4 use in the wire rod which draws being probable to undergo the pretreatment

(1) superficial pretreatment: Regarding the superficial sully, the adherency many impurity's wire rods, must first after the clean, drying carries on again draws; Has the many oxide skin wire rods regarding the surface, must pass through the peracid to be thin first, after the drying, carries on again draws; Regarding superficial phenomenon and so on existence sand buckle, pit, heavy skin wire rods, but must carry on the sharpening after the polishing engine carries on again draws;

(2) heat treatment: Regarding degree of hardness oversized or degree of hardness non-uniform wire rod, must first reduces degree of hardness through the annealing or the tempering, and causes the wire rod maintains the good degree of hardness homogeneity carries on again draws.

3.5 maintain being suitable draws the area reduction rate

The diamond wiredrawing mold itself has, the crisp characteristic hardly, if uses in the big area reduction rate reducing drawing, very easy to cause the mold to be able to withstand the stress to disrupt the abandonment, must therefore act according to the wire rod mechanical property the difference, chooses the appropriate area reduction rate to carry on draws. Draws the stainless steel wire with the diamond mold, generally the single channel area reduction rate does not surpass 20%.

3.6 use lubricity good lubricant

In stretch process, lubricant quality and lubricant supplies whether sufficient to be affecting the back guy mold's service life. Therefore the request lubricant oil base is stable, the oxidation resistance is good, has the fine lubricating ability, cooling and the clean, maintains the best lubrication condition throughout in the entire production process, with the aim of forming one to be able to withstand the high pressure, but is not destroyed the thin film, reduces the work area the friction force, enhances the mold service life.

Uses in the process, must observe the lubricating oil unceasingly the condition, if discovered that in the serious color deterioration or the lubricating oil the metal powder increases, must carry on the replacement or the filtration promptly, avoids the lubricating oil because of oxidizing the lubricity to reduce, simultaneously avoids the tiny metal pellet damage mold which draws in the process to fall off.

3.7 periodic maintenance sharpening diamond wiredrawing mold

The back guy mold in the long-term use process, the mold wall receives the metal wire rod intense friction and the washing out effect, inevitable will have the attrition phenomenon, what will be most common will be presents the ring-like ditch water transport in the work area wire rod entrance (dent). The back guy mold cingulum's appearance, intensified the nib attrition, because on the cingulum because of becomes less crowded the mold core material finely ground particles which flakes to lead by Jin Shuxian the nib work area and decides the diameter area, is playing the grinding compound role, but enters the nib the wire rod likely to rub the needle same aggravating nib the attrition. If is not prompt exchanges carries on the repair, then the cingulum will continue to accelerate to expand, makes the repair to increase the difficulty, even has the possibility to compare the deep place in the ring-like trench to present the crack, causes the mold complete disintegration abandonment.

Knew from the experience that formulates set of standard standards, strengthens the current maintenance, carries on the overhaul to the mold is the very economical worthwhile matter frequently. Once the mold presented any slight attrition, carries on polishing promptly, then makes the mold to restore spends the time to the primitive polishing condition to be short, moreover mold's pass size changes not obviously.

4 subtotals

In summary, for the extension back guy mold's service life, except the choice appropriate mold material quality, the rational design the pass size, raises the back guy mold's manufacture level, enables the nib surface smooth finish to achieve outside the technological requirement, but must determine the reasonable while going along compression ratio, improvement back guy mold's exploitation conditions. Pays attention to mold's current maintenance in the use process, should wash industriously frequently changes, and guarantees in the stretch process to have the good lubrication effect.