JPH0624696B2 - Surface maintenance method of titanium or titanium alloy intermediate material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides surface care for intermediate products such as slabs as titanium intermediate materials such as titanium or titanium alloys (hereinafter, these are simply referred to as titanium materials in the present invention). According to the grinding method.

[Prior Art] Generally, as a method for producing a titanium material slab, titanium ingot that is melted in a vacuum melting furnace is first made into a slab with a round cross section, which is first formed into a slab by forging, and then slab rolling. There is known a method in which a slab having a predetermined size is finish-formed and then supplied to a rolling mill for thick plates and hot rolling. (JP-A-57
The surface of a semi-finished titanium product obtained through these manufacturing processes is affected by O ₂ during heating during forging or slabbing. Hardened layer (30-50μ from the surface
m), oxide scale, and flaws (wrinkle flaws) during processing, which are harmful when rolling the product, and therefore need to be removed as a semi-finished product.

Generally, a cutting method has been the mainstream as a method for adjusting titanium semi-finished products, but a grinding method using a grinder has recently been attempted in order to improve efficiency and yield. However, it has been confirmed that such a grinding method has the following problems when targeting a semi-finished titanium product. That is, 1. Since titanium has an extremely high affinity with O ₂ , the heat of oxidative combustion due to friction during grinding is much higher than that of iron. On the other hand, since the thermal conductivity of titanium is 1/3 that of iron, the grinding product is hard to cool. During the grinding, the grinding wheel receives a heat load more than the cooling capacity due to the rotation due to the influence of the grinding heat of titanium and the grinding products attached to the grinding wheel, so that the temperature rises rapidly in a short time grinding.

2. For this reason, since the temperature is higher than the service temperature of the bond holding the abrasive grains, the abrasive grains come off, resulting in (a) abnormal wear of the grindstone (b) deterioration of the roughness of the surface to be ground. If the grinding is further continued, the carbonization phenomenon of the grindstone is caused and cracks occur, resulting in damage.

3. On the other hand, high-temperature grinding products adhere to the material to be ground (welding of the grinding slag), which makes it impossible to detect surface defects after grinding and requires long-term hand-liner maintenance to remove the adhered grinding products. You

And so on.

As a countermeasure against these problems, a method of extremely reducing the pressure of the grindstone against the material to be ground, or an intermittent grinding method of interrupting the grinding and air-cooling the grindstone is proposed. However, in reality, it is difficult to reduce the grinding efficiency and the basic unit of the grindstone.

[Problems to be Solved by the Invention] As a result of various investigations, the present invention is to solve the phenomenon associated with the grinding of titanium material, and as a result, the semi-finished titanium product is stored in a water receiving box, and the surface to be ground is placed below the water surface. This is solved by positioning it.

It is common knowledge in precision grinding to perform water injection during grinding, but actual cases have not been reported in grinding intermediate materials such as slabs. As a special example, there is a method for caring for a high carbon steel piece disclosed in JP-A-58-82667. However, the purpose of this method is to prevent surface cracking of a steel piece when a high carbon steel piece having a carbon equivalent of 1.14 or more is ground with a grindstone, and as in the present invention, peculiar wrinkle defects are generated when a titanium material is ground, It does not prevent welding of the grinding wheel or abnormal wear of the grindstone.

[Means for Solving Problems] In grinding the surface of titanium or a titanium alloy material with a grinding grinder, the present invention stores a slab of titanium or a titanium alloy in a water receiving box and uses it as a work material and / or a grindstone. The method is characterized in that a certain amount or more of water is supplied and the material is retained so that a water film is formed on the surface of the titanium or titanium alloy material, for example, in the case of a slab, it is ground and ground. As will be described later, underwater grinding in which the surface to be ground is positioned below the water surface is effective for forming this water film. Therefore, in the present invention, the surface to be ground is positioned below the water surface.

[Operation] Hereinafter, the present invention will be specifically described based on the embodiments shown in the drawings.

FIG. 1 shows a mode of titanium material grinding in the present invention, and 1 is a titanium material. Titanium material 1 is drainage hose 2
It is placed in the water receiving box 3 having the. The surface of the titanium material 1 is ground by a conventional method with a grinding grinder arranged and moving in a predetermined direction.

A water supply hose 5 is connected to the grinding grinder, and the tip of the water supply hose 5 is oriented in the direction of the grindstone 4 or the grindstone 4 and the titanium material 1, and further the titanium material 1, and a water film is inevitably present on the grinding surface. It is like this.

As a result, the grindstone and the surface of the titanium material in contact with the grindstone are cooled, and the water film on the surface of the titanium material prevents the temperature of the grindstone from rising abnormally and prevents the welding of the grinding slag on the surface of the titanium material.

As a result, it is possible to ensure that the basic unit of the grindstone of the grinder is improved, the grinding efficiency is improved, the grinding roughness of the surface of the titanium material is improved, and the re-care by the adhered matter is avoided. A certain amount of water is required (12 / min or more), and it is effective to form a water film so that the injected water exists on the titanium material surface and perform underwater grinding on a horizontal surface. And

On the other hand, the grindstone of the grinder undergoes rapid heating and quenching due to the hardness of the titanium material and the grinding in water as described above, so it is necessary to select a material that is strong against mechanical shock and strong against thermal shock. Examples of the abrasive grains include high-purity alumina sintered abrasive grains and zirconia abrasive grains.

Further, it is preferable to select a grindstone having a binder containing a large amount of special filler, which has more heat resistance and suppresses the growth of heat cracks.

Example 1 The first example of the present invention will be described.

(1) Grinding condition As shown in Fig. 3, when the water is supplied toward the grinding point with the upper surface of the water in the water receiving box 3 slightly higher than the surface of the titanium material 1, and a water film is formed on the titanium material surface for grinding ( Wet (water film))
In order to make a comparison between the case where only water was supplied without using a water receiving box (wet type) and the case where dry grinding was performed, grinding was performed under the following conditions.

(2) Grinding results When each item in the case of conventional dry grinding is set to 1, a remarkable effect is obtained as shown in the following table.

Grinding wear is greater in wet grinding than in dry grinding It will decrease and the welding of the grinding slag will decrease sharply and the surface roughness will be improved, but if grinding is performed so that a water film is further formed on the titanium material surface, the welding of the grinding slag will be completely eliminated and the surface roughness will be improved. This eliminates the need for hand grinder maintenance after grinding.

Example 2 Next, an example of the effect of the water film of the present invention will be described.

(1) Water supply conditions (2) Grinding conditions Water was supplied to the surface of the titanium material under the conditions of (1), a water film was formed on the surface of the titanium material, and the surface of the titanium material was kept horizontal to perform grinding under the following conditions.

(3) Grinding results When each item in the conventional dry grinding is set to 1, a remarkable effect is obtained as shown in the following table.

In dry grinding, it was observed from the EPMA analysis results and SEM photographs that the titanium material adhered to the surface of the grindstone after grinding as a grinding slag and also penetrated inside the grindstone. It is well understood that the above problems are inhibited, but these drawbacks are not recognized in wet (water film) grinding.

A comparison of the temperature rise of the grindstone during grinding is shown in FIG.

By adopting the grinding method of covering the surface to be ground with the water film according to the present invention, the temperature does not rise after the constant temperature rise. On the other hand, according to the conventional method, the temperature rises to 250 ° C. in about 5 minutes. It is necessary to stop grinding and wait for cooling (broken line).

[Effects of the Invention] As described above, according to the present invention, a titanium material can be efficiently and economically ground by an extremely simple method, and the grinding roughness can be significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a grinding state of a titanium material according to the present invention, FIG. 2 is a diagram showing a rising state of a grindstone temperature in the present invention and a conventional method, and FIG. 3 is an apparatus used for a test of the present invention. Show an overview. 1: Titanium material, 2: Drainage hose, 3: Water receiving box,
4: grindstone, 5: water supply hose, 6: grinder, arrow: grinding direction, rotation arrow: grindstone rotation direction.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hitoshi Sakagami Hitoshi Sakagami 1-1-1 Edamitsu, Yawatahigashi-ku, Kitakyushu City, Fukuoka Prefecture Inside the Yawata Works, Nippon Steel Corporation (72) Inventor Seisaburo Komatsu Hachiman, Kitakyushu City, Fukuoka Prefecture 1-1-1 Emitsu, Higashi-ku, Nippon Steel Co., Ltd., Yawata Works (72) Inventor, Yasuaki Sakai, Noritake Company Limited 3-36 Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi (56) References Actual Public Sho 61-3575 (JP, Y2) Actual Public Sho 59-3996 (JP, Y2)

Claims (1)

[Claims] 1. In a work for removing scratches and grinding a surface of an intermediate product such as a slab of titanium or a titanium alloy with a grindstone, the intermediate product is stored in a water receiving box and the surface to be ground is positioned below the water surface. A method for cleaning the surface of titanium or titanium alloy intermediate material, characterized in that the surface to be ground is covered with a water film, and a grindstone is ground in that state.