1.Why does titanium rebound more when cold stamping or cold bending? What are the influencing factors?
The rebound of titanium is larger in cold stamping or cold bending because the ratio of yield limit to elastic modulus of titanium is larger.
Cold stamping or cold bending forming is a combination of plastic and elastic deformation process, when the stamped or bent workpiece unloading, the elastic deformation part of the attempt to make the workpiece back to its original state and rebound.
Elastic rebound of the workpiece volume, openness and radius, etc. have changed, affecting the accuracy of the workpiece.
There are many factors affecting springback, the most important of which are as follows.
Precautions for manufacturing titanium packaging
a. The harder the material, the greater the amount of rebound; b. The lower the modulus of elasticity, the greater the amount of rebound.
b. The lower the modulus of elasticity and the higher the yield limit, the greater the springback.
c. The thicker the part, the greater the stress at the outer edge, and the greater the plastic deformation for a given value of bending angle, the lower the springback; d. The greater the degree of deformation, the higher the springback; e. The higher the bending angle, the higher the plastic deformation.
d. The greater the deformation, the greater the springback.
e. The springback is greater in unidirectional bending than in multiple-kok bending; f. The springback is greater in free bending than in multiple-kok bending.
f. The rebound in free bending is three times greater than that in stamping with a die.
g. The higher the degree of cold hardening of the metal, the higher the springback; and
h. The amount of springback decreases as the temperature of the workpiece is increased during stamping or bending.
2.What should I pay attention to when cutting and machining titanium?
The following characteristics of titanium should be noted when cutting and machining titanium.
(1) Titanium has a high coefficient of friction, which makes it easy to generate high temperatures in the cutting process and accelerates tool wear.
(2) The thermal conductivity of titanium is small, the chips are tough and do not curl, and the heat generated by friction with the tip of the tool is almost entirely concentrated on the cutting edge and the forward tilting surface of the tool, which results in burns on the cutting edge. Therefore, the amount of feed should not be too small, and the cutting speed should not be too high, or else it will be easy to stick to the knife and the fine titanium chips will burn and cause accidents; (3) Due to the elasticity of titanium, it is easy to generate high temperature during the cutting process.
(3) Due to the small modulus of elasticity of titanium, deep cutting of fine workpieces are prone to deflection, the workpiece is easy to leave the tool, so in the processing of the need to install anti-vibration frame; (4) Titanium has a high temperature activity, so that the cutting edge is burned.
(4) Titanium has high-temperature activity, which may lead to surface contamination of the workpiece during machining.
(5) Because titanium contains high hardness oxides, nitrides and carbides, so in the cutting process is easy to lead to the cutting edge of the tool soon wear;
(6) when cutting titanium, the cutting edge of the tool is easy to leave the tool, so it is necessary to install a vibration isolator.
(7) cutting titanium, cutting force is small, cutting processing is not easy to produce cutter marks, so it can be higher surface finish processing.
