JP4559929B2 - Saw wire manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a saw wire for a loose abrasive saw machine that cuts a material used for a semiconductor, a solar cell, or the like.

  As a method of obtaining a thin piece such as a silicon wafer or crystal used for semiconductors or solar cells, a thin wire A is used as shown in FIG. 1, and a large number of these are arranged in a plurality of grooved rollers R1, R2, R3. Wrapped in the shape and run in the longitudinal direction, while pouring a slurry-like processing liquid (abrasive liquid) containing abrasive grains between the wire and the object to be cut while pressing the wire row against the ingot-shaped object W, A wire saw machine method is widely used in which a plurality of thin layer pieces are cut by a grinding (lapping) action by abrasive grains.

What is important in this method is to increase the cutting efficiency. To achieve this, it is important that loose abrasive grains are constantly interposed between the contact surfaces of the ingot and the wire. As described above, a round wire having a diameter of about 0.16 to 0.25 mm obtained by drawing a steel wire and performing final heat treatment, followed by brass plating and final wet drawing was used.
However, in such a saw wire, the pulling of the free abrasive grains is relatively smooth in the front portion (region close to the surface in the thickness direction) F of the cut portion of the workpiece W as shown in FIG. However, in the central part M and the rear part B of the ingot, the contact pressure between the cutting part and the wire is high, and a phenomenon that the abrasive grains cannot be drawn (so-called liquid breakage or film breakage) is likely to occur. As described above, cutting with a wire saw is performed by the lapping effect of abrasive grains (usually about 20 microns of diamond powder), so when liquid or film breaks, the wire and ingot are directly rubbed. . For this reason, it has been inevitable that the cutting efficiency is greatly reduced.

As a countermeasure, Patent Document 2 proposes that a spiral groove is provided in the longitudinal direction of the wire, and the free abrasive grains are held in the groove to improve the cutting force.
However, in a saw machine, when a large tensile force is applied to a wire as a cutting blade, in the prior art, a groove is notched in the wire, so it is inevitable that the strength of the wire is reduced due to the notch action. Moreover, it is very difficult to process a groove having a uniform depth and width on a hard wire having a diameter of around 0.2 mm, and it is extremely difficult and often results in a non-uniform processing state. Easy to concentrate. Further, if the groove processing is performed after plating, the plating of the groove portion is cut off, so that corrosion tends to occur. For these reasons, breakage and breakage of the wire are likely to occur during use, and it takes a lot of labor and time to repair the wire.
JP-A-9-70747 Japanese Utility Model Publication No. 63-17755

The present invention has been made to solve the above-described problems, and the object of the present invention is to improve cutting efficiency without causing a decrease in strength and at the same time improve cutting accuracy. An object of the present invention is to provide a method that can mass-produce saw wires that can be manufactured at low cost.

In order to achieve the above object, the saw wire manufacturing method of the present invention applies a twist to a drawn wire having a perfect circular cross section, and locally moves the wire cross section by rolling means while moving the twisted wire in the longitudinal direction. Rolling, unwinding after rolling, then adding twist in the direction opposite to the first twist, and rolling the wire section locally by rolling means while moving the twisted wire in the longitudinal direction. It is characterized by returning twist after rolling.

When the saw wire manufacturing method of the present invention is used, an excellent effect is obtained that the next saw wire can be mass-produced at low cost simply by running the wire.
That saw wire of the present invention, all of the wire cross section is not circular, it has a flat surface on at least a part, since the gap is formed between the object to be cut which the wire is in contact with its flat surface, free abrasive Supply of the machining fluid containing grains is ensured appropriately. Moreover, since the gap is continuous in a spiral shape in the longitudinal direction of the wire, free abrasive grains are accurately supplied even in the central portion and the rear portion of the object to be cut, thereby preventing liquid breakage or film breakage. Therefore, efficient cutting can be performed.
In addition, the mechanism that forms a gap with the workpiece is realized by forming a flat surface by rolling rather than providing a groove in the cross section of the wire, so there is no reduction in strength, and the wire in use Can be avoided.

In addition, the wire has a non-uniform residual stress in the circumferential direction in terms of manufacturing, and the non-uniform residual stress in the circumferential direction continues in the longitudinal direction by wire drawing. As a result, the wire does not advance straightly during cutting with a saw machine, and it tends to be inclined at the center or rear area of the workpiece to cause partial cutting, but residual stress is increased by processing the flat surface into a spiral shape. Since it is distributed in a spiral shape in the longitudinal direction of the wire and the residual stress is made uniform in the circumferential direction, the straightness is improved and the cutting progress direction is stabilized. For this reason, the thickness of the thin layer piece to be cut can be made uniform.
In addition, the spiral of the flat surface is a mixture of clockwise and counterclockwise rotation, and the surface residual stress of the wire can be formed in a well-balanced manner, improving the linearity during running cutting and causing the wire to shake during cutting. It can move smoothly and the accuracy can be improved. Further, since the gap with the cutting portion is in a cross shape, the machining fluid containing the abrasive grains is sufficiently supplied in the clockwise direction and the counterclockwise direction through the cross-shaped gap, so that the cutting efficiency and accuracy are improved. be able to.

Two or more flat surfaces are equally spaced on the wire circumference, and the maximum distance between the flat surface and the wire basic cross-section circle is 10 to 100 μm.
According to this, since two or more flat surfaces are equidistant on the wire circumference, the shape balance is good, and the distribution of residual stress is made uniform in the circumferential direction, so that the wire shakes during cutting. In addition to smooth movement, the pitch of the flat surface becomes fine, so that it is possible to finely supply the cutting fluid containing abrasive grains to the cutting part. Moreover, since the maximum distance between the flat surface and the wire basic cross section is 10 to 100 μm, a gap with respect to the cut portion can be reliably created, and lapping can be performed with a sufficient amount of abrasive grains interposed.

As a manufacturing aspect, a twisting machine incorporating rolling means is used in two tandems, and a wire having a perfect circular cross section is twisted in the first twisting machine, and the wire in the twisted state is Rolled by rolling means arranged in the twisting machine, untwisted after rolling, then led to the second twisting machine to add a twist in the direction opposite to the twist, and the twisted wire was twisted in the twisting machine Rolling is performed by the rolling means arranged in, and twist is restored after rolling.
According to this, the spiral of the flat surface which mixes clockwise and counterclockwise can be processed efficiently in-line.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 9 exemplifies the manufacturing apparatus and manufacturing method of the S / Z direction mixed type flat surface-equipped saw wire according to the present invention, and FIG. 7 shows that the flat surface portion manufactured according to the present invention is a spiral 2 in the S direction (clockwise). , An embodiment of a saw wire combining a Z direction (counterclockwise) helix 2 'is shown.
3 to 5 show the flat surface portion 2 in the S direction of the saw wire according to the present invention.
No. 1 is basically a wire having a cross section of a perfect circle or close to it and having a diameter of 0.05 to 0.30 mm, for example, and is formed by drawing a high carbon steel having a carbon content of 0.70% or more. The surface is plated with brass, zinc or the like with a thickness of 0.10 to 1.2 μm, and the residual stress on the surface is ± 200 kgf / mm ² .

Reference numeral 2 denotes a belt-like flat surface portion formed by rolling on the surface of the wire 1. In this example, four flat portions are provided at equal intervals on the circumference, and a space between the flat surface portions 2 is an arc surface. The flat surface portion 2 is spirally continuous in the longitudinal direction of the wire at a required pitch, for example, 1 to 20 mm.
The flat surface portion 2 preferably has a maximum distance H from the wire outer circle of 10 to 100 μm as shown in FIG. 4 in order to exhibit a function of forming a gap in the cut portion of the workpiece during use. Since the created gap is small at 10 microns or less, the processing liquid containing abrasive grains cannot be smoothly fed into the cutting portion. A thickness of 100 μm or more is not preferable because the lapping effect is lowered. It selects suitably from the said range by the number which provides the flat surface part 2. FIG.
As an example, when four flat surface portions are provided in a wire having a wire diameter of 0.15 mm, the maximum distance H from the wire outer circle may be about 20 μm and the pitch may be 10 mm.

According to this embodiment, similarly to FIG. 1, a plurality of rollers with grooves are wound around in a row and run in the longitudinal direction, and the wire and the object to be cut are pressed while pressing the wire row against the ingot-like object W. A slurry-like processing fluid (abrasive fluid) S containing abrasive grains is poured between them and cut into a plurality of thin layer pieces by grinding (lapping) action with abrasive grains. Since the flat surface part 2 is not circular but has a part on the circumference, a gap is created between the cutting part w as shown in FIGS. S is interposed.
In addition, since the flat surface portion 2 has a spiral shape, the flat surface portion 2 corresponding to the helical pitch faces the cutting processing portion w one after another as the wire 1 travels, and the processing liquid S is supplied. If the working fluid S is poured onto the flat surface portion 2 from above or from the side of the cutting portion, it is guided along the spiral and cut by the lapping action.
Therefore, according to such a mechanism, liquid cutting and film cutting do not occur in the central part M and the rear part B as well as the front part F of the cutting part w of the workpiece W, so that the cutting efficiency can be increased. Further, it is possible to prevent the occurrence of unevenness due to direct rubbing between the wire and the object to be cut, and the surface accuracy is improved.

Further, since the flat surface portion 2 is formed by rolling and has a spiral shape, the surface residual stress at the time of wire drawing also becomes a spiral shape, whereby the surface residual stress is averaged in the circumferential direction. Turn into. For this reason, the linearity is improved and the vehicle travels straight. For this reason, inclined cutting is prevented, and a thin layer piece having a uniform thickness can be cut from one end to the other end.
In addition, since the flat surface portion is formed by rolling instead of processing the groove in the wire 1, the strength does not decrease, and the notch action as in the case of the groove type does not occur even when a strong tension is applied. There is no risk of cutting. Further, when the groove is cut, the plated layer is not a groove portion, but in the case of the present invention, since the plated layer is on the entire surface, the corrosion resistance is improved.

The flat surface part 2 in this invention is not limited to four places. FIG. 6 shows a few examples, and FIG. 6A shows two flat surface portions 2 formed. (B) forms three places. (C) shows an example of 5 places, and (d) shows an example of 6 places. More may be used, but since it is preferable to leave the original arc surface of the wire, it will normally be up to about 10 locations.

The spiral of the flat surface portion in the present invention is a combination of the spiral 2 in the S direction (clockwise) and the spiral 2 'in the Z direction (counterclockwise) as shown in FIG.
According to such a combination of spirals in two directions, the balance of the surface residual stress is improved, so that straightness is improved, and the number of flat surface portions on the circumference is substantially increased, so that the number of gaps is increased. Finely intervening abrasive grains can be realized. In addition, since the machining fluid can be guided from the cross portion to the front and back in the traveling direction, it is possible to accurately form a gap in the cut portion and interpose abrasive grains regardless of the direction of travel of the wire.

FIG. 8 illustrates a manufacturing apparatus and a manufacturing method of a saw wire with a flat surface in the S or Z direction applied to the present invention of FIG.
3 is a wire bobbin, 4 is a twisting machine, and 8 is a winding bobbin, which are arranged in series. A first guide roll 5a and a first turn roll 5b forming a pair with the first guide roll 5a are arranged on the upper side of the traveling line at the center of the twisting machine 4, and a second turn roll 5c and the first turn roll 5c are arranged in the downstream portion. A second guide roll 5d forming a set is arranged. The first guide roll 5a and the first turn roll 5b constitute a first twisted portion T1, and the second turn roll 5c and the second guide roll 5d constitute a second twisted T2 portion.

On the running line at the center of the twisting machine 4, at least one pair of rolling rolls 6 that form a pair orthogonal to the wire passing through the downstream guide roll 5d is arranged, and the wire is wound several times downstream thereof. Capstan 7 that can be used.
In this example, two sets of rolling rolls 6 whose phases are displaced are arranged at a predetermined interval. These rolling rolls are mounted on a fixed bearing stand or the like, and the amount of reduction is adjusted by a gap adjusting mechanism (not shown).

A third guide roll 5e is positioned downstream of the capstan 7, and a first twist-back portion is formed on the lower side of the traveling line at the center of the twisting machine 4 as a pair with the third guide roll 5e. A third turn roll 5f that constitutes TB1 is arranged, and a fourth guide that constitutes a second twist back portion TB2 in a group with the third turn roll 5f on a travel line downstream of the third turn roll 5f. A roll 5g is arranged, and a wire passing through the fourth guide roll 5i is guided to the winding bobbin 8.
The first and second twisted portions T1 and T2 and the first and second twisted-back portions TB1 and TB2 are rotated clockwise or counterclockwise about the traveling line of the twisting machine 4.

A material wire 1 ′ is wound around the bobbin 3. The material wire 1 'is a normal wire obtained by drawing a high carbon steel wire, heat-treating it, performing intermediate drawing, patenting, etc., performing brass diffusion plating, etc., and then final wet drawing.
If the material wire 1 'is guided to the winding bobbin 8 through the above-described path and the twisting machine 4 is operated, the material wire 1' is in the state shown in FIG. Twist is inserted in the longitudinal direction at the portions T1 and T2, and the state shown in FIG. 10B is obtained. The wire in a state where the second twist is applied is led from the downstream side of the twisting machine 4 to the traveling line.

Since the rolling roll 6 is located on this line, the twisting wire passes through the gap. When the wire is not twisted at all, when it passes through the rolling roll 6, a straight flat surface portion along the longitudinal direction is formed at a 180-degree symmetrical position in the cross section. Since the twist is twisted, the roll reduction position is shifted obliquely by the twist. For this reason, as shown in FIG. 10C, the flat surfaces 2 and 2 resulting from the reduction at the 180-degree symmetry position draw a spiral corresponding to the torsion.
And, when another set of rolling rolls 6 is 90 degrees out of phase downstream as in the embodiment, the flat surface that is 90 degrees out of phase with the previous roll is rolled here, and the flat surface is the same It becomes a spiral.

The wire thus rolled passes through the first and second untwisted portions TB1 and TB2 from the capstan 7 and is twisted twice during this time to give linearity, and is wound on the winding bobbin 8. Is done. Thus, the wire of the present invention as shown in FIG. 3 is continuously manufactured. In some cases, a roll that is normally used between the twisting machine 4 and the winding bobbin 8 may be applied to take a wrinkle.

When making what has the flat surface part of 2 places of Fig.6 (a), what is necessary is just to use 1 set of rolling parts 6, and when providing in 6 places like (d), 3 sets of rolling rolls May be arranged with a phase shift of 120 degrees. In the case of three places and five places, a set of three or five rolling rolls may be used.

FIG. 9 illustrates a manufacturing apparatus and a manufacturing method of the S / Z direction mixed type saw wire with a flat surface according to the present invention.
In this case, the first twisting machine 4A and the second twisting machine 4B having the configuration shown in FIG. 8 are arranged in tandem, and an intermediate bobbin or capstan 9 is interposed between them, and the first twisting machine 4B is arranged. Operation is performed with the rotation directions of the wire machine 4A and the second wire twisting machine 4B reversed. The rolling rolls 6 may have the same phase.
In this way, the wire 1 in which the spiral flat surface portions 2 and 2 are formed as described above is formed in the first twisting machine 4A, and the wire 1 is formed in the first and second twisting machines 4B. Two twists T1 and T2 are twisted twice in the longitudinal direction, and then rolled into a spiral flat surface in the opposite direction by the rolling roll 6, and from the capstan 7 to the first and second twist back parts TB1 and TB2 Is twisted twice while passing through the winding bobbin 8.
Thereby, a saw wire as shown in FIG. 7 can be manufactured continuously.

In addition, when forming the flat surface part 2 of only one place on a cross section, the receiving member which has a curvature concave surface about the half cross section of a wire in a twisting machine is used, and a wire is made to contact a curvature concave surface. It may be run and a rolling roll may be arranged perpendicularly to the longitudinal direction of the wire above the receiving member to perform local reduction.
Various types of wire saws can be used, and there is no limitation.

It is a front view which illustrates the cutting process state by a loose abrasive type wire saw. (A) The longitudinal cross-sectional view which shows typically the cutting state by the conventional saw wire, (b) is sectional drawing which follows the XX line of (a). (A) is an enlarged side view which shows the one side of the flat surface part of the saw wire by this invention, (b) is the enlarged view. It is an expanded sectional view of FIG. (A) is a longitudinal cross-sectional view which shows the use condition of this invention saw wire, (b) is a cross-sectional view. (A)-(d) is sectional drawing which shows the other example of this invention saw wire. It is a side view which shows the Example of this invention saw wire. It is a side view which shows the 1st step | level of the saw wire manufacturing method by this invention. It is a side view which shows the Example of the saw wire manufacturing method by this invention which also showed the state to which a flat surface part is attached. (A) is a side view of a material wire, (b) is a side view in a state where twist is applied, and (c) is a side view showing a rolled state for forming a flat surface portion.

DESCRIPTION OF SYMBOLS 1 Wire 2, 2 'Flat surface part 4 Twisting machine 4A 1st twisting machine 4B 2nd twisting machine 6 Roll roll T1 1st twisting part T2 2nd twisting part TB1 1st twisting part TB2 2nd twisting part

Claims (2)

A twist is applied to the drawn wire having a perfect circular cross section, the wire cross section is locally rolled by rolling means while moving the twisted wire in the longitudinal direction, the twist is restored after rolling, and then the first A method for producing a saw wire, characterized in that a twist in the direction opposite to the first twist is applied, the wire section is locally rolled by a rolling means while moving the twisted wire in the longitudinal direction, and the twist is returned after rolling. . The method for producing a saw wire according to claim 1, wherein the twisting machine incorporating the rolling means is used in two tandems.

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