September 27, 2018
Maintenance and normal operation of internal cold drill
Alloy bit generally refers to carbide bit, integral type, welding type, indexable blade type and replaceable type. The main components of cemented carbides are tungsten carbide and cobalt, etc., which are generally higher in hardness than HRC90 degrees. They are suitable for batch processing and hard processing.
Generally speaking, the length of a common carbide drill bit can be about 320cm according to the value of diameter. If it is of high speed steel material according to diameter can be 500-500 cm, but this is typically used with HSS taper shank chip breaker bit, and this kind of bit for hole of steel structure processing is more, but rarely in high speed steel cold material, domestic currently seem to also have no, and materials out of the factory after the bit processing also need to heat treatment processing, for cold inside aperture influence very big! So, what is common in the market is the hard alloy internal cold drill, so today I would like to share with you the maintenance of the internal cold drill and the matters needing attention to drilling.
(1) after the use of the internal cold drill, it shall immediately check whether there is any damage or passivation, and if there is any bad condition, it shall be immediately ground and dressed;
(2) when stored, the internal cold drill should be seated, so that when it is taken later, it will be convenient to save time and save time to find the internal cold drill again;
(3) when the internal cold drill is used to drill through the hole, when the internal cold drill is about to drill through the hole, the torque is high, so it needs to enter the tool slowly under light pressure to avoid torsion of the internal cold drill due to excessive force.
(4) before drilling, the center point must be made by xu before drilling. The purpose of this point is to accommodate static, avoid contact with the bottom of static point of internal cold drill, and guide the internal cold drill in the correct drilling position.
(5) when drilling, make full use of cutting and pay attention to chip removal;
(6) when drilling cross hole, drill large diameter hole first and then small diameter hole;
(7) the phenomenon of breakage or sudden stop during the drilling of the internal cold drill may be the reason why the feed is too fast, the grinding is quick and hot when drilling;
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09:56 AM
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September 13, 2018
Carbide blade strength varies with different shapes
General circular turning is to process the outer surface of the part to obtain the required dimensional position precision and surface quality. Ordinary cylindrical turning tool according to the cutting tool Angle 95 , 90 , 75 , 60 , 45 , 90 , 95Angle of cutting tool cutting large axial force, radial force is small, suitable for turning a slender shaft parts, 75 , 60 , 45 Angle cutter for cutting short cylindrical parts, including 45 master Angle 45 chamfer cutter can be turning. Negative Anglecarbideblade cutting tool economy is better than the Angle of the blade cutting tool, and is sharp edge, the Angle of the blade tool cutting light, only is Angle of the blade size is generally small, only suitable for small back turning, feed processing, and negative Angle blade size can be made larger, can be used in the large amount of turning, feed processing, also is better than the Angle of the blade tip strength (same shape, size, arc blade tip). Different blade intensity, effective cutting blade length and number of available blade tip are different.
Face turning refers to the main cutting edge on the face of the workpiece cutting processing.
1. Matters needing attention when facing the car
(1) the tool tip of the turning tool should be aligned with the workpiece center to avoid leaving a convex platform at the end face center.
(2) the end face of the offset cutter, when the amount of the back knife is large, it is easy to tie the knife. Selection of the amount of back knife ap: ap=0.5 ~ 3mm for rough turning,
(3) the diameter of the end face changes from the outside to the center, and cutting speed also changes. When calculating cutting speed, it must be calculated according to the maximum diameter of the end face.
(4) for the end face with a larger diameter, if there is a concave core or convex belly, check the tool and square tool holder, and whether the big slide is locked. In order to make the cutting tool horizontal feed accurately, the middle sliding plate should be tightened on the bed body, with small tool holder adjust the amount of the back knife.
(5) when the quality of end face is high, the last knife should be cut outward from the center.
2. Quality analysis of car end face
(1) uneven end face, protruding and concave phenomenon or "small head" left in the center of end face; The reason is that the tool is not installed correctly, the tip of the tool is not aligned with the workpiece center, the amount of the back knife is too large, and the lathe has gap slide movement.
(2) surface roughness difference. The reason is that carbide cutting tool is not sharp, the manual moving blade is uneven or too fast, and the automatic feeding quantity is not selected properly.
(3) the turning characteristics of inner hole are: it is not convenient to observe the chip removal in the semi-closed state, which affects the processing quality. Deep hole cutting often causes the vibration of carbide blade, making the cutting edge wear fast. The length of the workpiece and the size of the selected tool bar will not affect the tool's overhang during the turning of the outer circle, so it can bear the cutting force generated during the processing. When boring and turning the inner hole, the depth of the hole determines the overhang.
Posted by: hannahgwendolyn at
09:37 AM
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September 07, 2018
Surface pretreatment of aluminum alloy products
With the increasingly fierce market competition, many aluminum alloy die-casting enterprises have expanded their business to the international market since China joined the WTO. There are many requirements in the international market, such as delivery time, quality, appearance and packaging, and whether it belongs to the environmental protection series. Here we are talking about environmental protection. Now our country is also advocating green action. The world is also paying attention to environmental improvement.
Now, as a large number of gas, mocha and toner products, they are also constantly required to meet the environmental system requirements. As exported products, they must comply with the eu RoHS directive, and the ability of products to resist corrosion is also a key factor. This step is inevitable. Then, as an aluminum alloy product, how can we do this step? This is the need to carry out surface treatment on our aluminum alloy product, that is, passivation.
Passivation is to make the surface of the metal into a state which is not easy to be oxidized, and to slow the corrosion rate of the metal. An active metal or alloy in which chemical activity is greatly reduced and becomes a phenomenon of noble metal state, called passivation.
If the corrosion product of metal due to the action of medium has a dense structure and forms a thin film (often invisible), which is closely covered on the surface of the metal, it changes the surface state of the metal, making the electrode potential of the metal jump in the positive direction and become a dull state of corrosion resistance. For example, when Fe goes to Fe++, the standard potential is -0.44v, after passivation, it jumps to + 0.5-1v, and this film shows the performance of precious metal that is corrosion-resistant. This film is called passivation film. Passivation of metals can also be a spontaneous process (such as creating a layer of insoluble compounds on the surface of a metal, known as an oxide film). In industry, passivating agent is used to passivate the metal to form a protective film.
Metals are protected from corrosion by being passivated.
First of all, it should be clear whether the passivation is caused by the metal phase and the solution phase or by the interface phenomenon. The effect of mechanical scraping on metals in a passive state has been studied. Experiments have shown that when metal surface is polished continuously during measurement, the electric potential of the metal moves violently in the negative direction, that is, dressing the metal surface can cause the activation of the metal in the passive state. That is to say, passivation is an interfacial phenomenon. It is changed on the interface between metal and medium under certain conditions. Electrochemical passivation is when anode polarization occurs, metal potential changes and metal oxides or salts are formed on the electrode surface. These substances are closely covered on the metal surface as passivating film, which leads to metal passivating. Chemical passivating is caused by the direct action of oxidants such as concentrated HNO3 on the metal and the formation of oxide film on the surface, or the addition of easily passivating metals such as Cr, Ni, etc. In chemical passivation, the concentration of the oxidant added should not be less than a critical value, otherwise, it will not cause a blunt state, but will cause faster dissolution of the metal. In chemical passivation we now advocate green passivation -- trivalent chromate passivation solution.
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09:48 AM
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