JPH0245921B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a cold rolling method for cold rolling titanium plates, which has excellent lubricity and prevents titanium from building up (transferring) onto the rolling rolls. [Prior art] Cold rolling of titanium plates is usually carried out in stainless steel plate rolling equipment, that is, small-diameter multi-roll mills, and the rolling lubricant is mineral oil, natural oil, synthetic ester, or a mixture of these oils. Neat products are used in which oiliness improvers, extreme pressure additives, etc. are added. Stainless steel plate rolling equipment is used for:
This is because the processing characteristics of titanium sheet, especially the rolling load, are relatively similar to those of stainless steel, but the conditions are considerably harsher than that of stainless steel sheet, so both the rolling reduction and rolling speed are set lower than that of stainless steel sheet. . Therefore, even if the various rolling lubricating oils mentioned above were used, rolling was extremely difficult and it was not possible to manufacture thin gauge products. Even with thick gauges, the rolling reduction
Since the rolling speed had to be kept low, productivity was very low, and the surface quality of the finished product was also not good. In recent years, the excellent properties of titanium, such as excellent chlorine resistance and the highest specific strength (tensile strength/specific gravity), have been reconsidered, and along with its high added value, productivity has rapidly increased. It shows an increasing trend. Previously, only thick gauges were available, but
Since titanium is very expensive, there has been a trend towards thinner titanium, and there has been a need for thinner gauge rolling. In order to efficiently roll to a thin gauge, it is necessary to increase the rolling reduction ratio in each pass, but when the rolling reduction ratio is increased, there is a tendency for the friction coefficient to increase rapidly. The friction coefficient increases because titanium builds up from the titanium plate onto the rolling roll, and this build-up could not be prevented using any conventional rolling lubricant. In the case of titanium plates, build-up begins to occur when the coefficient of friction reaches 0.05 or higher, and it rapidly develops thereafter, but this phenomenon is not observed when the coefficient of friction is at the same level as that of ordinary steel plates or stainless steel plates. Generally, in the case of cold rolling, a mixture of fluid lubrication and boundary lubrication is used, but in the case of ordinary steel sheets and stainless steel sheets, oiliness improvers and extreme pressure additives are effective in the boundary lubrication region. On the other hand, in the case of a titanium plate, it is thought to have little effect and build up. When it builds up on the rolling rolls, its high coefficient of friction makes further rolling impossible, and at the same time it significantly impairs the surface quality of the rolled plate. Therefore, a high-quality product with the desired thickness cannot be obtained. In order to deal with these problems, we have developed a method of cold rolling titanium using rolling oil with a saponification value of 170 or more (Japanese Patent Application Laid-open No. 154349/1982) and forming an oxide film of about 2000 Å on the surface of titanium before rolling. Since then, a method of cold rolling using rolling oil (Japanese Unexamined Patent Publication No. 54-88858) has been developed, which has made it possible to prevent titanium from building up on the rolling rolls and reduce the rolling pressure. Attempts have been made to increase the rolling reduction ratio, but in both of the above inventions, seizure cannot be completely prevented by thin gauge cold rolling and high speed cold rolling of titanium plates, so it is difficult to obtain a high quality surface shape. Therefore, it is not possible to obtain a titanium plate having the following properties. [Object of the Invention] The object of the present invention is to lower the coefficient of friction in cold rolling of titanium sheets to enable high reduction rate rolling, and to prevent build-up of titanium on the rolling rolls to achieve excellent surface quality. The present invention aims to provide a method for cold rolling titanium plates to obtain thin gauge products. [Structure of the invention] The present invention has been made to achieve the above object,
A titanium fluoride film with a basis weight of 0.1 to 10 g/m ² is formed on the surface of the titanium plate by contacting it with a treatment solution containing a fluorine compound in advance, and then rolling in the presence of rolling oil or water-soluble rolling fluid. The present invention provides a method for cold rolling a titanium plate, which is characterized by performing the following steps. As a chemical used to adjust the processing solution,
First, fluorine compounds include hydrofluoric acid, sodium fluoride, potassium fluoride,
Examples include acidic sodium fluoride, acidic potassium fluoride, silicofluoric acid, sodium silicofluoride, and potassium silicofluoride. 1 of these
A species or a combination of two or more species dissolved in water is used. Next, as additives Zn, Ni, Co,
The basis weight of the film produced by arbitrarily selecting heavy metal ions such as Mn and inorganic acid ions such as nitrate ions, sulfate ions, and phosphoric acid from those ranges is preferably 0.1 to 10 g/m ² . More preferably, it is 1 to 8 g/m ² . Next, the process of forming a film will be explained. After hot-rolled steel sheets are descaled by pickling, shot blasting, or liquid honing, they are immediately subjected to chemical conversion treatment. In the case of liquid honing, descaling and chemical conversion treatment can be performed at the same time by blending the above-mentioned composition into the bath solution. For the chemical conversion treatment, a method normally used for steel sheet products, ie, a dipping method, a spray method, or a combination of these methods, is used. The rolling oil used is mineral oil, natural fat, synthetic ester, or a mixture thereof, and if necessary, oiliness improvers, extreme pressure additives, antioxidants, oil stain inhibitors, etc. are added. Rolling oil is generally used neat, but may also be used as an emulsion to increase the cooling effect. A direct method or a recirculation method is applied to supply rolling oil. It is also possible to roll with a water-soluble rolling fluid using a water-soluble lubricant without using oils and fats. [Function] The rolling method of the present invention is based on forming a film on the surface of the titanium plate, and the main component of the film is titanium fluoride formed by reacting with a fluorine compound in the treatment liquid. When rolling with rolling oil or water-soluble rolling fluid with this film applied, the film prevents metal-to-metal contact between the titanium plate and the rolling roll, and prevents titanium from building up on the rolling roll surface. The rolling oil or water-soluble rolling fluid plays the role of lubrication. The titanium fluoride film is relatively soft and firmly adheres to the surface of the titanium plate, so even when the titanium plate increases in surface area as it is rolled, it fully follows the increase in surface area and provides isolation between the rolling roll and the titanium plate. I can maintain it. Also, due to its softness, the shear resistance at the interface between the rolling roll and the titanium plate is reduced, lowering the coefficient of friction. Since titanium fluoride coatings are relatively porous,
Excellent retention of rolling oil and water-soluble rolling fluid used as lubricating oil. The basis weight of the titanium fluoride film needs to be at least 0.1 g/m ² in order to keep up with the increase in surface area of the titanium plate that occurs during thin gauge rolling, but if it exceeds 10 g/m ² there will be an economic loss. At the same time, as a pre-process to cold rolling, chemical conversion treatment takes too much time and tends to be unreasonable in terms of process. Also, a part of it may build up on the rolling roll. Therefore 0.1
~10g/ ^m2 is preferred, more preferably 1-8
g/. After rolling, the titanium fluoride film can be easily removed by a conventional electrolytic cleaning process. For example, a titanium fluoride film of 5 g/m ² is formed on a titanium original plate (thickness 3.2 mm) before rolling, and then it is rolled for 10 passes to a thickness of 0.4 mm.
When rolled to mm, the surface of the titanium plate after rolling
A titanium fluoride film of 0.15 g/m ² remained, but
When this titanium plate was passed through an alkaline electrolytic cleaning line, most of the titanium fluoride film was removed from the surface of the plate. Examples of the present invention are shown below along with comparative examples. [Example] Rolling tests were conducted on plates with and without a titanium fluoride film, and the coefficient of friction during rolling, the build-up amount of titanium on the rolling roll, and the surface roughness of the plate after rolling were measured. . (1) Treatment bath (aqueous solution) Acidic sodium fluoride 2.1g/Manganese sulfate 3g/Sodium sulfate 1g/Temperature 70-75°C Immersion treatment The treatment time was as shown in the table below to adjust the basis weight. (2) Coating weight

[Table] (3) Rolled beef fat octyl stearate No. 2 spindle oil TCP 20% 30% 48% 2% neat oil used at 40℃ (4) Rolling conditions ・Material to be rolled: Pure titanium (JIS class 2) hot rolled Plate 3.0mm
t×3.0mmω×200mm ・Work roll diameter: 70mmφ ・Work roll surface: Bright (Rmax0.8μ
m) ・Rolling speed: 20m/min ・Number of passes and rolling reduction rate: 7 passes, 25% for each pass ・Lubrication method: Spray lubrication to upper and lower rolls, flow rate
1.5/min (5) Evaluation method Friction coefficient Calculate the advance rate for each pass and use the Bland & Ford formula h ₂ : Thickness of plate after rolling (mm) R′: Radius of flat roll (mm) r: Reduction ratio φ: Advance ratio Amount of titanium build-up on the rolling roll Weight of plate before rolling and plate after 7-pass rolling Express the difference in g/m ² (converted to original plate area) and use it as the build-up amount. However, the weight of both the front and rear boards was measured without any film or oil on them. Surface roughness of rolled plate The surface of the plate after 7-pass rolling was measured in the C direction using a stylus roughness meter, and expressed as Rmax (μm). The test results are shown in the table below.

【table】

[Table] In Examples 1 to 3, the friction coefficient is lower than that of the comparative example, the increase in each pass is very small, and the build-up amount is also very small at about 1/10. Therefore, it can be seen that the surface roughness after rolling is maintained approximately equal to the roughness of the rolling roll, and the surface quality is significantly improved. [Effects of the Invention] As explained above, the method for cold rolling a titanium plate of the present invention involves contacting the titanium plate in advance with a treatment solution containing a fluorine compound, heavy metal ions, and inorganic acid ions to form a titanium fluoride coating on the surface. is formed and then rolled in the presence of rolling oil or water-soluble rolling fluid to reduce the friction coefficient and prevent titanium from building up on the rolling rolls, resulting in a titanium plate with excellent surface quality. It has an excellent effect of obtaining the product. This has made it possible to roll thin gauge titanium plates that were previously impossible to roll.

Claims (1)

[Scope of Claims] 1. A titanium fluoride film having a basis weight of 0.1 to 10 g/m ² is formed on the surface of a titanium plate by contacting it with a treatment solution containing a fluorine compound in advance, and then rolling with rolling oil or water-soluble rolling. A cold rolling method for titanium sheets characterized by rolling in the presence of a liquid. 2 The treatment liquid used to form the titanium fluoride film is an aqueous solution containing a fluorine compound with heavy metal ions and inorganic acid ions added as additives, and the titanium plate is brought into contact with this treatment liquid. 2. The method for cold rolling a titanium plate according to item 1 above, wherein a titanium fluoride film is formed by rolling the titanium plate. 3. The cold rolling method according to item 1 above, wherein the method of bringing the titanium plate into contact with the treatment liquid in forming the titanium fluoride film is immersion. 4. The first method in which the method of bringing the titanium plate into contact with the treatment liquid in forming the titanium fluoride film is spraying.
Cold rolling method described in section.