JPH0839416A - Wire for wire saw - Google Patents

Abstract

PURPOSE:To improve ' abrasion resistance as well as to make drag-in property of abrasives satisfactory in a wire for a wire saw made of high tensile strength steel wire material such as a hard steel wire material or a piano wire by forming a scale layer of a specific thickness of Fe3O4 as its main component on the base material surface of the wire. CONSTITUTION:As to the wire for a wire saw for cutting hard material such as an artifical crystal or a silicon ware, a scale layer of thickness of 2 to 5mum of Fe3O4 as its main component is formed on the base material surface of a wire made of a high tensile steel wire material such as a hard steel wire material or a piano wire material. This Fe3O4, which is so called the magnetite, is formed by passing it through an atmosphere containing gas such as H2, and O when the wire is heated in a wire furnace. The Fe3O4 scale surface has fine lengthwise and broadwise cracks caused by Fe3O4 crystals and drag-in property of abrasives 5 is improved by the abrasives biting into the cracks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire saw wire used for cutting hard materials such as synthetic quartz and silicon wafers.

[0002]

BACKGROUND OF THE INVENTION A wire saw is an abrasive grain for cutting a wire, generally a silicon carbide grain,
It is made to run while being pressed against an object to be cut together with abrasive particles such as diamond particles and cut.

Since the above-mentioned wire is required to have a strength capable of withstanding a large tension applied at the time of cutting, a high tensile strength steel wire rod, generally a hard steel wire rod, a piano wire rod and the like are used. However, since these steel wire rods have a hard surface and are smooth, they are inferior in bringing in abrasive grains to the object to be cut, cannot improve the cutting speed, and are inferior in cutting efficiency. Had.

In recent years, in view of the above problems, a copper or tin plating layer is provided on the surface of a high tensile strength steel wire rod, and the relatively soft plating layer holds the abrasive grains, whereby the abrasive grains on the object to be cut are removed. A wire for a wire saw has been proposed to improve the carry-on property (for example, Japanese Patent Laid-Open No. 54-21692).

As still another example, a wire for a wire saw, which is intended to improve cutting efficiency by applying abrasive grains to the surface of the wire in advance and running the wire while pressing the wire against an object to be cut, thereby improving the cutting efficiency. It is known.

In the wire saw wire represented by the latter, as shown in FIG. 3, abrasive grains 8 of grain sizes # 150 to # 1000 are bonded on the outer peripheral surface of a high-strength wire 7 having a substantially circular cross section by nickel plating, copper plating, or the like. The wire 9 is attached by the material 9 to form the wire saw wire 6.

When the hard material is cut using the former wire for the wire saw, the plating layer of the wire is naturally worn out. While the carry-in property of the abrasive grains is good while the plating layer remains, the carry-in property of the abrasive grains is deteriorated when the wear progresses and the plating base is exposed. Therefore, before such a phenomenon occurs, it is necessary to replace the wire for wire saw with a new wire.However, in the former wire for wire saw, the plating layer is soft and inferior in wear resistance, so the wear progresses quickly. , It is difficult to increase the cutting speed. Therefore, the life of the wire for the wire saw is shortened, and the cutting efficiency is poor.

The latter wire for a wire saw is excellent in the ability to bring the abrasive grains into the object to be cut, but the adhesive force of the abrasive grains, that is, the binding force between the abrasive grains, the binder and the wire. There is a problem of being inferior. Therefore, when the object to be cut is cut, the abrasive grains are dropped off early, and the cutting efficiency is lowered. And nickel as the binder,
The wear progresses quickly because a soft metal such as copper is used.
Therefore, the life of the wire for the wire saw becomes short.

Furthermore, both the former and latter wires for wire saws must be plated on their surfaces. Therefore, a series of plating processing lines are required, which is very disadvantageous in terms of installation space, equipment management such as plating solution management, and workability, and there is a problem that manufacturing cost becomes high.

The present invention has been made to solve various problems of the conventional wire for a wire saw.
An object of the present invention is to provide a wire for a wire saw, which has good abrasive grain carryability, excellent wear resistance, and low manufacturing cost.

[0011]

In order to achieve the above object, the inventor of the present invention conducted various researches on various surface treatment techniques applied to a wire through experiments. As a result, if the wire surface is smooth, wear resistance is inferior if the wire surface hardness is lowered to improve the carry-in property of the abrasive grains, and conversely, if the surface hardness is increased to increase wear resistance, the carry-in abrasive particles are brought in. We have come to the conclusion that the wire surface must be uneven because of poor performance.

[0012] Therefore, various studies have been made on a method of providing unevenness on the wire surface. First, in the wire final drawing step, a grooved roller die was used as the finishing die to form irregularities on the wire surface. However, this method is inferior in bringing in the abrasive grains because it is not possible to form minute unevenness such that the abrasive grains bite into.

Next, a method of making unevenness by scratching the surface of the wire with a polishing grindstone or the like was tried. This method was better in bringing in the abrasive grains than the method using the roller die. However, since the polishing grindstone causes clogging, it is necessary to frequently remove the clogging with a dresser, and contamination of the working environment by dust also poses a problem. Furthermore, since the pressing force of the polishing grindstone varies in the longitudinal direction and unevenness is generated, stable cutting cannot be expected when used in a wire saw. It is difficult to achieve the above-mentioned object by the mechanical surface treatment technique as described above.

Next, the present inventor examined various methods of chemically providing irregularities on the wire surface. The point to be noted here is that if the wire surface hardness after the surface treatment is much lower than the hardness of the base material, it is not practical because the wear resistance is poor.
That's what it means. Therefore, the method of providing the decarburized layer on the wire surface may cause the relatively soft decarburized layer to fall off at an early stage, and the purpose cannot be achieved.

From the above viewpoints, the present inventor has conducted further research. As a result, if a scale layer that causes large surface defects in a normal wire is intentionally provided, and if the type and thickness of the scale layer are properly controlled, the carry-in of abrasive grains is improved, wear resistance is improved, and manufacturing is performed. The inventors have found that the cost can be reduced, and have completed the present invention based on this finding.

That is, the wire for a wire saw of the present invention is
In a wire saw wire made of a high tensile strength steel wire rod such as a hard steel wire rod or a piano wire rod, on the surface of the base metal of the wire,
It is characterized in that a scale layer containing Fe ₃ O ₄ as a main component and having a thickness of 2 to 5 μm was formed.

[0017]

[Function] Fe ₃ O ₄ is called magnetite,
It can be generated on the wire surface by passing the wire through an atmosphere containing a gas such as H ₂ O or CO ₂ when the wire is heated in a wire-burning furnace. As shown in FIG. 2, the Fe ₃ O ₄ scale surface has minute cracks, so-called cracks, on the vertical and horizontal sides due to the Fe ₃ O ₄ crystal 4.
Moreover, the hardness of Fe ₃ O ₄ itself is considerably higher than that of the plated material (or binder) such as nickel and copper described above.

When the wire on which the Fe ₃ O ₄ scale is generated is run while being pressed against the object to be cut together with the abrasive grains, the abrasive particles 5 are hard to be cracked as shown in FIG. Bringing in abrasive grains is greatly improved.

The Fe ₃ O ₄ scale is generated by a chemical change between Fe ground on the wire surface and H ₂ O or CO _2, and the bonding force acting between the Fe ground and Fe ₃ O ₄ is produced. However, it is much larger than the bonding force acting between the abrasive grain, the bonding material and the wire in the conventional method. Therefore, even when used as a wire saw for a long time, the Fe ₃ O ₄ scale layer is less likely to fall off.

By the way, the scale generated on the wire surface
Is FeO (westite), Fe ₃ O_Four (Magnetie
G) and Fe₂ O₃ There are 3 types of (hematite)
Exist. The reaction formula for the generation is as shown in the following chemical formula 1.
It is Ri.

[0021]

Embedded image

The above scale is generated from the inside of the wire in the order of FeO, Fe ₃ O ₄ , which is the lowest valent oxide, and Fe ₂ O ₃ , which is the highest valence oxide, of which Fe ₂ O ₃ contacts the outside air and forms the outermost surface. Formed thin.

Further, FeO is used in high-temperature heating in the wire-burning furnace.
Fe by the eutectoid reaction shown in the following chemical formula 2 ₃ O_Four Be transformed into.

[0024]

Embedded image

As described above, the scale layer containing Fe ₃ O ₄ as a main component can be formed on the surface of the wire.

When the thickness of the scale layer is less than 2 μm,
It is inferior in the ability to bring in abrasive grains, and even if it exceeds 5 μm, there is no further increase in the ability to bring in abrasive grains, and the strength of the wire saw itself only decreases. Therefore, the thickness of the scale layer is 2
Limited to ~ 5 μm.

[0027]

Example A SWRS82A material (φ5.5) was subjected to patenting and cold drawing to finish a wire with a wire diameter of 1 mm. Next, the wire is heated in a wire-burning furnace (heating temperature 900
° C.) in _{H 2 O, CO 2, N} 2 , etc. of the gas is passed through the atmosphere by blending, followed by passing through a back oven (450 ° C.), the average thickness of 20μm on the surface of the wire
A wire having a scale layer mainly composed of Fe ₃ O ₄ was obtained.

Further, the above wires are wet-drawn by a wet drawing machine.
The wire was drawn to 0.16 mm to obtain a wire saw wire 1 having a schematic cross section shown in FIG. In FIG. 1, a scale layer 3 containing Fe ₃ O ₄ as a main component and having an average thickness of 3 μm is formed on the surface of a base material 2.

A conventional brass-plated wire saw wire was manufactured as a comparative material using the same SWRS82A material. The wire diameter at this time is the same as that of the material of the present invention.
It was finished to 16 mm and the plating thickness was 2 μm.

Next, in order to compare the machinability and wear resistance of the material of the present invention and the comparative material as a wire for a wire saw, a cutting test was conducted under the following conditions, and the results shown in Table 1 were obtained.

<Cutting conditions> -Sample to be cut φ75 silicon wafer-Wire linear velocity 200 m / min-Wire tension 2 kg-Abrasive grains used GC # 1000 (14.5-18μ)
m)

[0032]

[Table 1]

In Table 1, the cutting efficiency indicates the cutting amount per unit time, and is an index when the comparative material is 100, and the larger the cutting efficiency, the better. The degree of wire wear indicates the amount of wire wear per unit time and is an index when the comparative material is 100, and the smaller the value, the better.

From Table 1, the wire for the wire saw of the present invention has a cutting efficiency of 1.7 times that of the comparative material. This indicates that the carry-in property of the abrasive grains was greatly improved. Also,
The wire wear rate was reduced to about 1/3.

[0035]

Since the wire for a wire saw of the present invention has the above-mentioned structure, the carry-in property of abrasive grains to the object to be cut is greatly improved. Therefore, the cutting efficiency is greatly improved and the cutting cost of the object to be cut can be reduced.

Further, the wear resistance is far superior to the conventional one, and the life as a wire for a wire saw can be extended by 2 to 3 times. Therefore, it is possible to reduce the work of exchanging the wire for the wire saw during the cutting process of the object to be cut.

Further, since the plating process as in the conventional case is not required, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a wire for a wire saw of the present invention.

FIG. 2 is an explanatory view showing a surface state of the wire for a wire saw of the present invention.

FIG. 3 is a schematic cross-sectional view showing a conventional wire for a wire saw.

[Explanation of symbols]

1, 6 Wire for wire saw 2 Base material 3 Scale layer 4 Fe ₃ O ₄ crystal 5, 8 Abrasive grain 7 High tensile wire 9 Binder

Claims (1)

[Claims] 1. A wire saw wire made of a high tensile strength steel wire rod such as a hard steel wire rod or a piano wire rod, and a scale layer containing Fe ₃ O ₄ as a main component having a thickness of 2 to 5 μm on the surface of the base metal of the wire. A wire for a wire saw, which is formed.