Heave mould technology
As far as possible choose advanced mold processing technology in the production of high quality tungsten carbide drawing die
At present, foreign guy mold grinding process widely used high-speed mechanical polishing machine, hard alloy of metal plating and surface grinding needle, the equipment running smoothly, the specifications of the grinding needle and the use of standardized products precision is higher. The groove size of the mold using contour recorder and pore diameter measuring instrument to detect, with check drawing die dedicated microscope to check the surface finish. And many domestic manufacturers still adopt the backward equipment, use manual operation to grinding groove, therefore, there are the following problems: volatile pass parameters, work hard to work out straight cone; Sizing area and workspace junction grinding out transition Angle, make the wire in the sizing area produces secondary compression, increase the friction, shorten the sizing zone length, shorten the service life of mould; Wear of the grinding needle repair frequency varies from person to person, the use of non-standard, causing pass the consistency of the poor. Detection methods are backward, and can only rely on simple tools such as visual or a magnifying glass, microscope inspection, and pay attention to is a mould surface finish, the groove size cannot effectively detect, much less control.
2 choose good groove design of the cemented carbide drawing die
Wire drawing die pass generally divided into curve (i.e., R series) and linear (i.e., conical series).
From the Angle of the wire in the uniform deformation in pull mode analysis, appears to be type curve is linear, the pass is in the "rounding off" under the guidance of the theory of design, the groove structure according to the nature of work can be divided into "population area", "lubricating area", "work", "sizing area", "the day" area five parts, each border request "chamfering", smooth transition, the whole groove grinding into a large, solitary surface with different curvature the groove of the mold at the time of the drawing speed conditions, can still apply. By the late 1970 s to the early 80 s, with the increase of drawing speed, the service life of drawing die is a prominent problem. In order to meet the requirements of high speed wire, America's T.M axwall and E.G.K ennth "linear" theory is proposed. This theory focus on the lubrication and wear factors in the process of drawing, points out that the improved linear should pass the guy has the following features:
(1) all parts of the groove profile line must be straight, straight work cone drawing force minimum;
(2) the transition part of the mould parts must be clearly, so that each part can give full play to their role, to avoid the transition Angle of actual length of sizing area decreased;
(3) the extension of the entrance area and the height of the workspace, make the wire into the die working cone in the middle of the paragraph, using the inlet cone Angle and the upper part work cone Angle of the wedge area, establish a "wedge effect", in the wire rod surface form more dense solid lubricating film, reduce wear and tear, suitable for high speed drawing;
(4) sizing area must be flat and reasonable length. Sizing area is too long, pull the friction increase, pull wire die easy cause reducing or break line, after sizing area are too short, it is difficult to obtain good shape stability, size precision and surface quality of wire rod, die at the same time also will soon wear out-of-tolerance.
By practical application, using the theory of linear design of drawing die, its service life than R stay for 3 to 5 times more.
3 wire drawing machine equipment installation use is reasonable
(1) drawing machine should be installed base is solid, avoid vibration phenomenon;
(2) when installation to debug wire tensile axis and the die hole centerline is symmetrical, uniform stress; the wire rod and wire mould,
(3) in the process of the wire to avoid frequent start parking, because drawing started the friction caused by the tensile stress is bigger than normal drawing of friction, this will increase the mould wear and tear.
4 is used for drawing wire passes through pretreatment
(1) : surface pretreatment for wire rod surface dirt, adhesion is more impurities, first drawing again after cleaning, drying; For wire rod surface have more scale, should first after acid thin, drying and then to drawing; For surface peeling, pits, the phenomenon such as double skin wire, but also through the polishing machine for grinding after the drawing;
(2) heat treatment: the hardness is too large or uneven hardness wire, or tempering hardness by annealing, keep good hardness uniformity and wire drawing again.
5 maintain appropriate drawing surface shrinkage
Cemented carbide drawing die itself has the characteristics of hard and brittle, if used for bedding face of shrinkage reducing drawing, it is easy to cause mould can withstand stress and fracture scrap, so according to the different wire mechanical properties, select the appropriate surface shrinkage for drawing. With cemented carbide die drawing stainless steel wire, single channel surface shrinkage usually not exceeding 20%.
6 of lubricant with good lubricating property
In the drawing process, the quality of the lubricant and lubricant supply adequacy are affecting the service life of die. Therefore require oil-based lubricant is stable, good oxidation resistance, with excellent lubricity, cooling and cleaning, and always maintain the best in the whole process of lubrication state, so that can form a layer of thin film under high pressure without being destroyed, reduce the friction of work area, improve the service life of the mold.
Use process, to observe the condition of the lubricating oil, if it is found that serious discoloration or lubricating oil in metal powder increased, to be replaced in time or filter, avoid oil lubrication performance degradation due to oxidation, and to avoid drawing die off small metallic particles in the process of damage.
7 regular service grinding hard alloy wire drawing die
Drawing die in the process of long-term use, die wall by metal wire intense friction and scouring effect, inevitably produce wear phenomenon, the most common of which are at the entrance to the workspace wire ring groove cao (dent). Pull mode ring groove, exacerbating the die wear and tear, because the ring groove on the peeling off by loose small particles by metal wire core materials into the die workspace and sizing area, abrasive role, while the wire into the die like grinding needle die wear. If not timely repair switch, then the ring groove will continue to accelerate expansion, increase the repair is difficult, even in the depth of the annular groove is, the mould completely avalanche crushed scrap.
Learn from experience, develop a set of standards, strengthen the daily maintenance, often for maintenance of molds is very economical. When a mold is present any slight wear and tear, in a timely manner polishing, makes mold polishing to restore to the original state spent time is shorter, and the groove size has no obvious change in the mold