JP2012071392A - Fixed abrasive grain saw wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixed abrasive grain saw wire, as a tool for cutting and working a hard material, having a structure for keeping stable adhesion of abrasive grains without generating cracks in an abrasive grain adhesion layer during cutting working.SOLUTION: The fixed abrasive grain saw wire includes an adhesion layer fixing abrasive grains on a surface layer of a hard steel wire, wherein fibers are mixed in the adhesion layer.

Description

The present invention relates to a saw wire that is a tool for cutting a hard material, and relates to a fixed abrasive saw wire in which abrasive grains are fixed on a wire surface.

A saw machine is known as a machine for cutting a silicon ingot used for a solar cell or the like. FIG. 4 is a schematic view of a saw machine. The saw wire is prepared in the saw machine as follows. The wire wound around the supply reel 102 is supplied to the saw machine. The saw wire is guided to a plurality of guide rollers (not shown) and guided to the main roller 104. The saw wire is wound around the main roller 104 generally composed of two to four. Several tens to several hundreds of wire groups are stretched between the main rollers 104. Thereafter, the saw wire is guided to the plurality of guide rollers and wound around the discharge reel 106 in the same manner as in the supply.

Run the wire after the wire is set. In this state, the ingot 108 for processing the wire group stretched between the main rollers is pressed. Then, the ingot 108 is cut by the wire group, and a wafer having a thickness corresponding to the wire pitch is obtained.

There are two types of saw wires. One is a method of cutting while spraying slurry containing abrasive grains. The other is a method in which cutting is performed using a wire in which abrasive grains are fixed in advance. In general, the former is called a free abrasive type, and the latter is called a fixed abrasive type.

In most of the fixed abrasive grains, the abrasive grains are uniformly fixed to the outer periphery of a wire having a round cross section. Patent Document 1 describes a typical fixed abrasive saw wire (hereinafter simply referred to as a wire). Since the abrasive grains are fixed to the wire in advance, the ingot is cut by being continuously scratched by the abrasive grains as the wire travels. In the fixed abrasive type, a processing speed several times that of the free abrasive type is realized.

Generally, there are two types of media for fixing abrasive grains. One is resin-based and the other is metal-based. Recently, metal-based ones are desired because of the high adhesive strength of abrasive grains. Furthermore, Ni is widely used as disclosed in Patent Document 1 because of its price and handleability among metal systems.

In the fixed abrasive saw wire, dropping off of the abrasive grains is fatal. As shown in FIG. 4, the wire is wound around the main roller several times. At the same time, the wire contacts the ingot many times. At this time, if the abrasive grains fall off at an early stage, the ability to cut the wire after the dropping is extremely reduced. Therefore, it is very important that the abrasive grains are firmly fixed to the wire. For the above reasons, Ni is preferably used in order to realize strong adhesion of abrasive grains.

JP-A-9-150314

As described above, in use in a saw machine, the wire is guided from the supply reel to the main roller, and is further wound between the main rollers. At this time, the wire is “twisted”. That is, a stress in the “twist” direction is applied to the wire and the abrasive fixed layer. The abrasive fixed layer located in the outer layer is most easily affected, and when stress is excessively applied, cracks 12 enter the abrasive fixed layer 6 made of, for example, Ni as shown in FIG. Further, when the twist is excessively applied or the ingot is cut in this state, the crack progresses and reaches the core surface. Furthermore, when this crack occurs in a plurality of locations, the abrasive fixed layer is likely to be peeled off. In the worst case, peeling with the abrasive grains 10, that is, the abrasive grains fall off. Therefore, the wire cutting performance is reduced.

Therefore, as described above, it has been a conventional problem to provide a fixed-abrasive saw wire having a structure that maintains a stable adhesion of abrasive grains without causing cracks in the abrasive-bonding layer when using a saw machine. It was.

The saw wire of the present invention that solves the above problems is a fixed abrasive saw wire having a fixed layer for fixing abrasive grains to the surface layer of a hard steel wire, and is a fixed abrasive saw wire in which fibers are mixed in the fixed layer. is there.

Specifically, the fiber is glass fiber, carbon fiber, or metal fiber.

In the saw wire of the present invention, it is possible to prevent the abrasive grains from falling off during use. In other words, even when the wire is twisted particularly when used in a multi-saw machine, and even when contact with the workpiece repeatedly occurs, it is possible to prevent the abrasive grains from falling off.

Sectional view of a representative wire of the present invention Schematic diagram when using conventional wire Schematic showing the effect when using the present invention Schematic diagram of the saw machine

The effect of the fibers in the wire of the present invention will be described with reference to FIG. It is assumed that the abrasive fixed layer is cracked during use of the wire in the saw machine. In the case of a conventional wire, as described above with reference to FIG. 2, a crack occurs in the depth direction of the wire along the crack, and the abrasive fixed layer peels off due to the cracks at a plurality of locations. However, even if a crack is generated in the abrasive fixed layer, it is possible to keep the crack from progressing by mixing fibers in the abrasive fixed layer.

The fiber must be strong. For example, there are carbon fiber, glass fiber, metal fiber, and the like. In addition, it is good to select suitably the fiber which is not restricted to these fibers and can be reinforced.

The fiber diameter is preferably 15 μm or less. When the thickness is 15 μm or more, the thickness of the fixing layer increases, the wire diameter of the fixed abrasive saw wire increases, and the loss of the cut product during cutting becomes larger than necessary.

Even if it is the same component as an abrasive fixed layer as a metal fiber, it is effective. For example, when a wire obtained by drawing a metal wire is used as a fiber, it is changed to a tough structure by drawing. By mixing such a structure, an abrasive fixed layer resistant to twisting can be formed.

As a method for producing the present invention, for example, in the case of metal plating as an abrasive fixed layer, fibers may be suspended in a plating solution. Fiber can be taken in when a metal deposits on the wire which is an electrode.

Moreover, as an adhesion amount of a fiber, what is necessary is just about 5 to 30% as a volume ratio in the total amount of an abrasive grain fixed layer and a fiber amount. For example, if the volume of Ni plating and the volume of attached fibers is 100, the amount of attached fibers may be about 5-30. If it is less than 5%, the effect of the fiber cannot be exhibited sufficiently. On the other hand, when the amount is more than 30%, the material constituting the abrasive grain fixing layer, for example, the amount of Ni plating decreases, and on the contrary, it is brittle and cracks are likely to occur in various places.

As a method for controlling the amount to be taken in, for example, when the abrasive fixed layer is formed by metal plating, it can be adjusted by changing the current density at the time of plating. If the current density is set low, the abrasive fixed layer can be grown slowly. This increases the probability that the fiber contacts the surface of the wire to be plated and increases the amount of results captured. Conversely, if the current density is set high, the growth of the abrasive fixed layer is accelerated. That is, it is possible to reduce the amount taken in by reducing the chance that the fiber and the wire come into contact with each other until the abrasive fixed layer is completely formed.

Moreover, it is good to cover the abrasive grain fixed layer by performing electroplating which does not contain a fiber at the end. A part of the fiber web taken in is exposed from the surface of the abrasive fixed layer formed by the above method. The fibers in this state not only do not contribute to prevention of cracking of the abrasive fixed layer, but also induce cracks and cracks in the abrasive fixed layer. Therefore, it is preferable to pass through the second electrolytic plating process performed with the same kind or different kind of metal as when the fibers are taken in with a thickness that can cover the exposed fibers.

In addition, as a method of forming the abrasive fixed layer while taking in the fibers, or covering the exposed fibers as the final step, any method that achieves the purpose may be used, and the method is not limited to plating. .

The fixed abrasive saw wire manufactured by the above manufacturing method was compared with a conventional wire. A wire diameter of 0.15 mm was used as the core material, and a glass fiber having a filament diameter of 10 μm and an average fiber length of 3 mm was used as the fiber. 0.4 g / l of the glass fiber was suspended in a plating bath of an electrolytic plating tank, and electrolytic plating was performed to fix the fiber and abrasive grains. Thereafter, plating was performed so that the surface was covered with the second electrolytic plating covering the exposed fibers to form an abrasive fixed layer.

As a conventional comparison, a wire core material having the same diameter was used, and the plating thickness, that is, the abrasive fixed layer, was manufactured to be approximately the same as the wire manufactured above.

An actual cutting experiment was performed using the manufactured fixed abrasive saw wire of the present invention and the fixed abrasive saw wire manufactured by a conventional manufacturing method. As a cutting machine, a multi-saw machine (model MWS-44NS) manufactured by Takatori Co., Ltd. was used. A SiC ingot having a width of 50 mm and a thickness of 20 mm was prepared as a cut workpiece. The pressure for pressing the SiC ingot was cut at a constant pressure, and the state of the wire after use was confirmed.

As a confirmation method of the wire state, the number of abrasive grains fixed in advance on the wire surface is counted. The number of abrasive grains at a wire length of 1 m was counted, the same count was performed at other locations, and confirmation was performed at five locations. This average is defined as the “abrasive grain adhesion amount” of the saw wire. Thereafter, the ingot was cut, and after use, the wire wound on the discharge reel was unwound and the same count was performed to confirm the change in the “abrasive grain adhesion amount”. In addition, the relative evaluation which set the abrasive grain adhesion amount before use of the conventional saw wire to 1 was performed.
The cutting speed was evaluated relative to the time required for cutting. The results are shown in Table 1.

In the conventional fixed abrasive saw wire, 13% of the abrasive grains were dropped. On the other hand, the fixed-abrasive saw wire of the present invention has an abrasive dropout of 3%, which is a significant improvement over conventional saw wires. Along with this, the cutting speed was also good. The actual time required for cutting was reduced by about 6%.

If the present invention is applied, for example, it can be applied to strengthening a surface layer coating on a steel sheet.

2... Fixed abrasive type saw wire 4... Core material 6... Abrasive layer 8. Fiber 10... Abrasive grain 12. ... Supply reel 104 ... Main roller 106 ... Discharge reel 108 ... Ingot

Claims (2)

A fixed abrasive saw wire having a fixed layer for fixing abrasive grains to a surface layer of a hard steel wire, wherein fibers are mixed in the fixed layer. 2. The fixed abrasive saw wire according to claim 1, wherein the fibers are glass fibers, carbon fibers, or metal fibers.