Pick to: this paper discusses the mould, casting rods, extrusion process three factors "burr" and "mark" and the solution. When continuously to high-end products, requires the close involvement of every working procedure and operator, total experience, constantly improve the operating level. To improve product quality, reduce cost.

 

 

Keywords: because of all kinds of flaws of the casting rod body with bad casting rod matrix solder, die elastic deformation and the dead zone, extrusion process, the metal flow discontinuity, form "aluminium deposition conditions, thus forming" "burr" or "mark".

 

 

preface

 

 

Shock "burr" and "mark" is the common defects in the aluminum extrusion production. "Burr" not intuitive, not careful observation or hand touch more difficult to find. "Mark" is particles on the surface of the opposite concentration profiles. The harm is: in the process of oxidation, electrophoresis, spraying material production, it's hard to get rid of the effect the beauty of the profile of surface and cause of waste. General manufacturer of surface treatment for the powder (paint) profile all after sandblasting, then powder (paint), the effect is better. But is very difficult to smooth electrophoresis oxidation material processing, has greatly, extrusion process, therefore, to view constantly in practice production analysis, the summary, take corresponding measures, in order to reduce or eliminate the occurrence of such defects is very important.

 

 

The difference between "burr" and "mark". In fact, the "burr" and "shock mark" professional term called "adsorbed particles". "Burr" irregular distribution on the surface profile, under a variety of reasons, the formation of before and after the work with viscose aluminum, are constantly "burr" be profile extrusion production out; "Burr" with the wind or wipe, most can be removed. The "mark", due to the glued aluminum mold empty tool, in profile vibrate or die moment rebound when the moment is pulled out, these particles almost on the same section or deep or shallow set on the profile, so use to wipe method is difficult to eliminate.

 

 

"Burr" for the conventional color, the impact is not big, but now new color number are introduced, especially the specular surface treatment material is becoming more and more and more and more high quality requirements, whether electrophoresis profiles, fluorine carbon spraying, spraying profile profiles, profiles of the surface treatment is the highlight is greatly influenced. "Burr" touch can feel with the hand in the profile on the surface of sliding. But one part due to electrostatic adsorption in profiles on the surface, after aging treatment, the more closely adhere to the "burr" on the surface profile. In the material surface pretreatment process, due to the limited by the scope of bath concentration regulation, some of them can get rid of, or remove form convex points out. The problem often appear in the surface treatment workshop production.

 

 

Seismic and "mark" in material surface pretreatment process, because of "burr" set on the profile, the formation of a surface is rough, even a sting hand feeling. Very few to get rid of, the formation of pits. Can't get rid of bumps is formed, because of the "burr" intensive, and almost in the same section. Such as surface treatment for oxidation, usually for the trash. Such as surface treatment for spray (powder), can be repaired by the method of sand paper to grind.

 

 

Shock "burr" and "mark" causes, and solutions. Mold design is reasonable and proper extrusion parameter selection, casting defects, is likely to be formed in the mold cavity stick aluminium conditions, eventually forming the appearance of "burr" and "mark".

 

 

A. The mold

 

 

1. The elastic deformation of mold caused. Mould manufacturing in its work with parallel to the extrusion direction, but the actual extrusion production, mold is under the condition of high temperature and high pressure under pressure, and deformation become a trumpet-shaped, work just work with the blade part of the contact adhesive aluminium profile form, and form a similar tool, the formation process of viscose aluminum, there have been "tool tumor" brought out by profiles, adhesion in the profile on the surface, forming a "burr" or "mark".

 

2. Such as mould empty tool too shallow, will cause the viscose aluminum increase gradually. Viscosity aluminum profiles gradually out of the formation of "burr", cannot be profile out, and the mold instantly glued aluminum does not fall off when the springback, will form the bright zone, coarse, even 劏 mould and so on.

 

 

3. The mould of metal flow dead zone. Most aluminium factory casting rod is generally not peel, casting rod surface and inner metal impurities in the mould flow dead zone, along with the increase in the number of squeeze casting rods, impurities and dead area is constantly changing, there are part of the normal flow of metal belt, and deformation after piling up in work space. Have been profile out, form a "burr" or "mark". Other impurities with the normal flow of metal friction each other, causing material surface bright, coarse, and other defects.

 

 

Solution:

 

 

1. Choose the appropriate number of holes and models. According to the profile of the inscribed circle diameter, wall thickness, single weight, and the size of the extrusion ratio, the existing models and choose the best mold specifications, reduce the forming conditions of viscose aluminum, reduce the formation of "burr" or "mark" probability;

 

 

2. Improve the strength of the mold. In actual production, the die elastic deformation, the greater the formation of "burr" or "mark" the greater the chance. Porous model (figure 1), such as tap hole and more close, the strength of the lower mold; And as long cantilever mould, etc. When designing the mould, as far as possible to improve mould stiffness, strength, to reduce the mold in the production of elastic deformation. To choose the best parameter values in determining the length of the work zone, mould neck, weld forms of chamber, air knife peatlands, tap hole size, etc., have to consider.

 

 

Before and the thickness of the mat, and inner hole, in the form of mould must be an effective support are also important, in the practical production proved that mat before doing a type (figure 2) is superior to the two type (figure 3). Achieve the goal of reducing die elastic deformation, to reduce "burr" shock "mark" effect is quite obvious!

 

3. Reduce the dead zone mold. Mold in the manufacturing process, requirements of die cavity surface and the excessive, R to avoid sharp corners, such as the excessive; Friction surface requirements of metal flow smooth, etc.

 

 

4. Mold surface roughness, working with the parallelism, working with surface hardness and so on, also can form the conditions of viscose aluminum. Mould must be within the mold cavity before nitriding, the smoothness of work, work with, such as parallelism to check and adjust, then for sanding, polishing, etc., to improve the smoothness of the mold. After nitriding, improve surface hardness, will further improve the smoothness of the mold.

 

 

5. The mold before, after the mold polishing, and in the mold parts of mating surface, welded room spray anti-rust agent.

 

 

6. Pretend, must will bolt locking.

 

 

Ii. The influence of extrusion process

 

 

1. If the temperature is high, the metal flow too fast, the extent of the mould deformation increase, easy to form adhesive aluminium phenomenon; Relative increased at the same time, the deformation resistance of the metal, metal in the mould cavity dead zone increases relatively, improve the forming conditions of viscose aluminum; Other if cast bar temperature, mold temperature, sheng ingot barrel temperature difference is too big, also easy to stick aluminium problem.

 

 

2. Before the mold production, must choose the specified die cushion, cushion. Also pay special attention to die cushion, cushion, cooperate if there is a gap between die, whether to have impact a cloak, cracks, and annealing to produce dent, etc. Which could one workpiece end face, during extrusion production leave space for die elastic deformation.

 

 

Solution:

 

 

1. The extrusion machine export under the white light, in order to observe the "burr" in real time.

 

 

2. According to the problem of "burr" real-time situation, according to the compression coefficient, section situation, mould, equipment, etc., of selecting the best extrusion temperature, casting bar heating temperature, mold temperature and extrusion speed, and in the process of production, and constantly adjust these parameters.

 

 

3. Limit the number of a computer production casting rods. Production rods as the increase of the number of, and work with temperature rising, aluminium and working with friction intensified, resulting in a decline in work with hardness, surface roughness, aluminum product more and more, "burr" is more and more.

 

 

4. Tractor driver should be checked before production die cushion, cushion, whether cooperate closely between the mould. If there are gaps, can adopt the method of smooth solution. If the amount of wear off is larger, the die cushion, cushion can be after heating, then put into production.

 

 

5. Squeeze the center who is. Mould center is not straight, good skin easily into the mold; Extrusion rod is not straight, press cake (sheng ingot cylinder) are compared.in addition, impurities will be supposed to go back into the mold, forming "aluminium deposition conditions.

 

 

6. In the extrusion production, should as far as possible to avoid shaking profiles. If the discharging mouth profiles, will air knife "aluminum product" instant out, form a "mark". So often in the tractor had just saw profile, in discharging mouth profile immediately to create a "mark".

 

 

The influence of three casting rods quality

 

 

Because of all kinds of flaws of the casting rod body with casting rod matrix solder is not good, caused the discontinuity of metal flow and forming "aluminium deposition conditions. To form a "" burr" or "mark".

 

 

Segregation is on the surface of the casting bar fusible precipitates, tumor, also called segregation is fusible component leakage after condensation in the casting bar surface, and in the extrusion production, gathered in the mold of metal flow dead zone, pull the extrusion or the flow profile, form a "burr" or "mark".

 

 

2. Osteoporosis is in the grain boundary and dendritic network appears the dispersivity of the macroscopic and microscopic, shrinkage cavity, triangular hole between the dendrite, fractograph not dense, may often accompanied by porosity, slag, etc., it is difficult to and metal welded in the extrusion production, thus to form aluminum phenomenon.

 

 

3. The slag is mixed with casting rods of slag, scale and other impurities, also called inclusions. Sag in the matrix, and will destroy the continuity of casting rods. In the process of extrusion, slag through working with mold, adhesion at the entrance to the end, the formation of aluminum.

 

 

4. The coarse grains is when the melt metal overheating or casting temperature too high. Liable to occur in the casting bar thick grain structure, accompanied by intergranular crack, make metal discontinuity in the extrusion production, also easy to produce viscose aluminum problem;

 

 

Solution:

 

 

1. In the process of casting rod casting, using fine grains process, to take effective technical measures to reduce casting rods of slag, osteoporosis, coarse grains and other defects, homogenization processing of casting rod.

 

 

2. In addition, to strengthen the macrostructure analysis of casting rods, quality monitoring, reduce defective casting rod put into use.

 

 

3. Use a dedicated high-end products casting rod, can improve yield and reduce computer mould number.

 

 

conclusion

 

 

Visible, mould, casting rods, extrusion process three factors "burr" and "mark", at the same time response of each operator experience and level. High-end products with high surface quality requirement and closely cooperate with each process and the process also pay great efforts.

 

 

To solve the problem, depend on each post personnel on the basis of practice, to analysis and summary, in order to improve the yield and production efficiency.