阅读说明：本技术 工件切断方法及线锯 (Workpiece cutting method and wire saw ) 是由 北川幸司 丰田史朗 于 2018-11-26 设计创作，主要内容包括：本发明提供一种工件切断方法,其通过线锯进行,通过将表面固着有磨粒的固定磨粒金属线卷绕至多个带沟滚轮而形成金属线列,通过一边使所述固定磨粒金属线在轴向上往复移动,一边将工件向所述金属线列切入进给,从而将所述工件在轴向排列的多个位置同时切断,其特征在于,在通过所述固定磨粒金属线进行工件切断过程中,将工件切断用冷却剂供给至所述金属线列上,当切断所述工件后从所述金属线列拉出所述工件时,将工件拉出用冷却剂供给至所述金属线列上,其中,所述工件拉出用冷却剂与所述工件切断用冷却剂不同且与所述工件切断用冷却剂相比黏度更高。由此,提供一种工件切断方法及线锯,其在从金属线列拉出切断后的工件时,抑制金属线卡住工件而产生锯痕或发生金属线断线的情况。(The present invention provides a workpiece cutting method performed by a wire saw, wherein a wire array is formed by winding a fixed abrasive wire having abrasive grains fixed on the surface thereof around a plurality of grooved rollers, and the workpiece is simultaneously cut at a plurality of positions arranged in an axial direction by cutting and feeding the workpiece into the wire array while reciprocating the fixed abrasive wire in the axial direction, wherein a coolant for workpiece cutting is supplied to the wire array during the process of cutting the workpiece by the fixed abrasive wire, and when the workpiece is pulled out from the wire array after cutting the workpiece, a coolant for workpiece pulling out is supplied to the wire array, wherein the coolant for workpiece pulling out is different from the coolant for workpiece cutting and has a higher viscosity than the coolant for workpiece cutting. Thus, a workpiece cutting method and a wire saw are provided, which can prevent the metal wire from clamping the workpiece to generate saw marks or generate wire breakage when the cut workpiece is pulled out from the metal wire row.)

1. A method of cutting a workpiece by a wire saw, in which a wire array is formed by winding a fixed-abrasive wire having abrasive grains fixed to a surface thereof around a plurality of grooved rollers, and the workpiece is cut at a plurality of positions arranged in an axial direction simultaneously by cutting and feeding the workpiece into the wire array while reciprocating the fixed-abrasive wire in the axial direction,

in the process of cutting the workpiece by the fixed abrasive wire, a coolant for workpiece cutting is supplied to the wire array, and when the workpiece is pulled out from the wire array after cutting the workpiece, a coolant for workpiece pulling out is supplied to the wire array, wherein the coolant for workpiece pulling out is different from the coolant for workpiece cutting and has a higher viscosity than the coolant for workpiece cutting.

2. The method according to claim 1, characterized in that a coolant having a viscosity of 5mPas or less at 25 ℃ is used as the coolant for cutting the workpiece, and a coolant having a viscosity of 15mPas or more at 25 ℃ is used as the coolant for pulling out the workpiece.

3. The workpiece cutting method according to claim 1 or 2, characterized in that a coolant having a moisture content of 99 mass% or more is used as the workpiece cutting coolant, and a coolant having a moisture content of 90 mass% or less is used as the workpiece drawing coolant.

4. A workpiece cutting method according to any one of claims 1 to 3, characterized in that as the workpiece, a workpiece having a diameter of 300mm or more is cut.

5. A wire saw is provided with: a wire array formed by winding a fixed abrasive wire having abrasive grains fixed to the surface thereof around a plurality of grooved rollers; a workpiece feeding mechanism for holding the workpiece and pushing the workpiece to the metal wire array; and a coolant supply mechanism that supplies a coolant to the wire array, supplies the coolant from the coolant supply mechanism to the wire array while reciprocating the fixed abrasive wire in the axial direction, and cuts the workpiece at a plurality of positions arranged in the axial direction simultaneously by performing cutting feed on the workpiece by the workpiece feed mechanism,

the coolant supply mechanism supplies a coolant for workpiece cutting to the wire array during cutting of the workpiece by the fixed abrasive wire, and supplies a coolant for workpiece drawing to the wire array when the workpiece is drawn from the wire array after cutting of the workpiece, wherein the coolant for workpiece drawing is different from the coolant for workpiece cutting and has a higher viscosity than the coolant for workpiece cutting.

Technical Field

The present invention relates to a workpiece cutting method and a wire saw.

Background

Wire saws are known as apparatuses for slicing wafers from a workpiece such as a silicon ingot or a compound semiconductor ingot. In this wire saw, a plurality of cutting wires are wound around a plurality of rollers to form a wire array, and the cutting wires are driven at high speed in the axial direction, and a workpiece is cut into the wire array while being fed with a slurry or a coolant as appropriate, so that the workpiece is cut at each wire position at the same time (see, for example, patent document 1).

Here, fig. 3 shows an outline of an example of a conventional general wire saw.

As shown in fig. 3, wire saw 101 is mainly composed of: a wire 102 (high tension wire) for cutting the workpiece W, a wire array 104 formed by winding the wire 102 around a plurality of grooved rollers 103 and 103 ', a mechanism 105 and 105' for applying tension to the wire 102, a workpiece feeding mechanism 106 for feeding the cut workpiece W downward, and a mechanism 107 for supplying slurry in which GC (silicon carbide) abrasive grains and the like are dispersed in liquid at the time of cutting.

The wire 102 is fed from a wire reel 108, passes through a tension applying mechanism 105, and enters the grooved roller 103. The wire 102 is wound around the grooved roller 103 about 300 to 400 times and then wound around the wire reel 108 'via another tension applying mechanism 105'.

The grooved rollers 103 are rollers in which a urethane resin is pressed into the periphery of a steel drum and grooves are cut at regular intervals on the surface thereof, and the wound wire 102 can be driven in the reciprocating direction at a predetermined cycle by the driving motor 110.

Further, when the workpiece W is cut, the workpiece W is held by the workpiece feeding mechanism 106, pushed down, and sent out to the wire 102 wound around the grooved rollers 103. With such a wire saw 101, an appropriate tension is applied to the wire 102 by the wire tension applying mechanism 105, and while the wire 102 is moved in the reciprocating direction by the drive motor 110, slurry is supplied through the nozzle 109, and the workpiece is cut into pieces by the workpiece feed mechanism 106, thereby cutting the workpiece.

On the other hand, a method of cutting a workpiece by using a fixed abrasive wire in which diamond abrasive grains or the like are fixed to the surface of a wire instead of using a slurry containing abrasive grains is also known, and has been put into practical use in a part of cutting a small-diameter ingot having a diameter of about 150mm or less.

In the slicing by the fixed abrasive wire, the fixed abrasive wire is provided instead of the steel wire of the wire saw shown in fig. 3, and the slurry is replaced with a coolant containing no abrasive, so that the wire saw can be used as it is.

Disclosure of Invention

Technical problem to be solved

Cutting with a fixed abrasive wire has many advantages over machining with a wire saw using free abrasive particles, such as less industrial waste and a high machining speed in terms of environmental issues because free abrasive particles are not used. However, in the wire saw, as shown in fig. 3, since the workpiece W is pressed against one wire 102 wound around the grooved roller 103 and cut, the workpiece W is positioned below the wire 102 at the time of cutting, and in order to take out the workpiece W, it is necessary to pull out the cut workpiece W by moving the workpiece W upward so that the wire 102 is relatively pulled out downward through a gap formed in a wafer shape by the cut workpiece W.

When the cut workpiece W is pulled out, as shown in fig. 4 (a), in the case of a wire saw using free abrasive grains, a gap (clearance) is generated between the wire 102 and the workpiece W by the width of only the free abrasive grains G, and further, the frictional resistance is reduced by the rotation of the free abrasive grains contained in the slurry remaining on the workpiece surface, so that the wire 102 is relatively easily pulled out. However, as shown in fig. 4 (b), in the case of a wire saw using fixed abrasive grains, since the clearance between the fixed abrasive grain wire 202 and the workpiece W is narrower than that of a wire saw using free abrasive grains, and there is no rotating free abrasive grain, the fixed abrasive grain wire 202 is difficult to pull out, the fixed abrasive grain wire 202 catches the workpiece W and floats, and when the fixed abrasive grain wire 202 is pulled out in this state, the cut surface of the workpiece is damaged and so-called saw marks are likely to be generated on the cut surface, and therefore, not only is the Warp deteriorated to deteriorate the quality, but also, in the case where the floating of the wire is increased, the wire may be broken. When the wire is broken, the fixed abrasive wire needs to be rewound around the grooved roller, and the fixed abrasive wire needs to be rewound by an extra amount, which results in a large loss.

The present invention has been made in view of the above problems, and an object thereof is to provide a workpiece cutting method and a wire saw that suppress the occurrence of saw marks or wire breakage due to the wire catching a workpiece when the cut workpiece is pulled out from a wire row made of fixed abrasive wire.

(II) technical scheme

In order to achieve the above object, the present invention provides a method for slicing a workpiece by a wire saw, the metal wire array is formed by winding the metal wire with fixed abrasive particles fixed on the surface to a plurality of grooved rollers, cutting the workpiece at a plurality of positions arranged in the axial direction simultaneously by cutting the workpiece into the wire row while reciprocating the fixed abrasive wire in the axial direction, characterized in that a coolant for cutting a workpiece is supplied to the wire array in cutting the workpiece by the fixed abrasive wire, supplying a coolant for drawing a workpiece to the wire array when the workpiece is drawn from the wire array after cutting the workpiece, wherein the coolant for drawing out the workpiece is different from the coolant for cutting the workpiece and has a higher viscosity than the coolant for cutting the workpiece.

With this method, when the cut workpiece is pulled out from the wire row formed of the fixed abrasive wire, the occurrence of saw marks or wire breakage due to the wire sticking to the workpiece can be suppressed.

In this case, it is preferable to use a coolant having a viscosity of 5mPas or less at 25 ℃ as the coolant for cutting the workpiece, and a coolant having a viscosity of 15mPas or more at 25 ℃ as the coolant for pulling out the workpiece.

In this way, if the coolant for cutting a workpiece having the viscosity is used for cutting the workpiece and the coolant for drawing the workpiece having the viscosity is used for drawing the workpiece, the quality of the cut piece, particularly Warp, is not deteriorated and the generation of saw marks or wire breakage can be more reliably suppressed.

In this case, it is preferable to use a coolant having a moisture content of 99 mass% or more as the coolant for cutting the workpiece, and a coolant having a moisture content of 90 mass% or less as the coolant for pulling out the workpiece.

The coolant having such a moisture content is suitable as a coolant for cutting a workpiece and a coolant for pulling out a workpiece used in the present invention.

In this case, a workpiece having a diameter of 300mm or more is cut.

The workpiece cutting method of the present invention is particularly effective in cutting a large-diameter workpiece.

Further, the present invention provides a wire saw including: a wire array formed by winding a fixed abrasive wire having abrasive grains fixed to the surface thereof around a plurality of grooved rollers; a workpiece feeding mechanism for holding the workpiece and pushing the workpiece to the metal wire array; and a coolant supply mechanism for supplying a coolant to the wire array and supplying the coolant from the coolant supply mechanism to the wire array while reciprocating the fixed abrasive wire in an axial direction, and the workpiece is cut at a plurality of positions arranged in the axial direction simultaneously by performing cutting feed on the workpiece by the workpiece feed mechanism, wherein the coolant supply mechanism supplies coolant for cutting the workpiece to the wire array in cutting the workpiece by the fixed abrasive wire, supplying a coolant for drawing a workpiece to the wire array when the workpiece is drawn from the wire array after cutting the workpiece, wherein the coolant for drawing out the workpiece is different from the coolant for cutting the workpiece and has a higher viscosity than the coolant for cutting the workpiece.

When the workpiece is pulled out from the wire array after cutting the workpiece, the wire saw of the present invention supplies a coolant for workpiece pulling out, which is different from the coolant for workpiece cutting and has a higher viscosity than the coolant for workpiece cutting, to the wire array. Therefore, the metal wire clamps the cut workpiece to prevent saw marks or broken metal wires.

Effects of the invention

In this way, in the workpiece cutting method and the wire saw according to the present invention, in the wire saw using the fixed abrasive wire, when the workpiece is pulled out after the workpiece is cut, the coolant for workpiece pulling out having a higher viscosity than the coolant for workpiece cutting is supplied, whereby the occurrence of saw marks or wire breakage due to the wire sticking to the cut workpiece can be suppressed.

Drawings

Fig. 1 is a schematic view showing an example of a wire saw according to the present invention.

Fig. 2 (a) is a diagram showing a positional relationship between the workpiece and the fixed abrasive wire at the end of cutting the workpiece, (b) is a diagram showing a state between the workpiece and the fixed abrasive wire when the wire is stuck, and (c) is a diagram showing a positional relationship between the workpiece and the fixed abrasive wire at the end of pulling out the workpiece.

Fig. 3 is a schematic view showing an example of a conventional general wire saw.

Fig. 4 (a) is a diagram showing a state of a wire in a gap of a workpiece in the free abrasive mode, and (b) is a diagram showing a state of a fixed abrasive wire in a gap of a workpiece in the fixed abrasive mode.

Detailed Description

As described above, in the case of cutting a workpiece using a fixed abrasive wire, if the cut workpiece is pulled out from the wire row after the end of cutting the workpiece, the wire catches the cut workpiece, and there is a problem that a saw cut or a wire breakage occurs in a cut surface.

Therefore, the present inventors have conducted active studies to solve the above problems. As a result, it was found that: when the cut workpiece is pulled out from the wire array after cutting the workpiece, if a coolant for workpiece pulling out having a higher viscosity than the coolant for workpiece cutting is supplied to the wire array, the lubricity of the cut surface of the workpiece when the workpiece is pulled out is improved, and therefore, the occurrence of saw marks or wire breakage due to the wire sticking to the cut workpiece can be suppressed, and the present invention has been completed.

The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

Fig. 1 is a schematic view showing an example of a wire saw 1 according to the present invention. As shown in fig. 1, a wire saw 1 of the present invention is mainly composed of: a fixed abrasive wire 2 for cutting the workpiece W, a plurality of grooved rollers 3 and grooved rollers 3 ' around which the fixed abrasive wire 2 is wound, a wire array 4 formed by winding the fixed abrasive wire 2 around the grooved rollers 3 and grooved rollers 3 ', a tension applying mechanism 5 and a tension applying mechanism 5 ' for applying tension to the fixed abrasive wire 2, a workpiece feeding mechanism 6 for feeding the cut workpiece W downward, and a coolant supply mechanism 7 for supplying coolant at the time of cutting and at the time of pulling out the workpiece.

Here, the feeding and winding of the fixed abrasive wire will be described in more detail. The fixed abrasive wire 2 is fed from one wire reel 8, passes through a tension applying mechanism 5 including a magnetic particle clutch (low torque motor 10), a tension roller (dead weight) (not shown) and the like via a crossbar (japanese: トラバーサ)9, and enters the grooved roller 3. Furthermore, the abrasive grain-fixed wire 2 is wound around the grooved roller 3 and the grooved roller 3' about 400 to 500 times to form a wire row 4. Further, the fixed abrasive wire 2 is wound up to the wire reel 8 ' via the arm 9 ' via another tension applying mechanism 5 ' including a magnetic particle clutch (low torque motor 10) or a tension roller (dead weight) (not shown).

In the wire saw 1, while the fixed abrasive wire 2 is reciprocated in the axial direction, the coolant is supplied from the coolant supply mechanism 7 to the wire array 4, and the workpiece W is cut and fed by the workpiece feed mechanism 6, whereby the workpiece W is cut at a plurality of positions arranged in the axial direction at the same time. The reciprocating movement of the fixed abrasive wire 2 is performed by advancing the fixed abrasive wire 2 wound between the grooved rollers 3 and 3' in one direction by a predetermined length, then retreating the fixed abrasive wire in the other direction by a length shorter than the aforementioned advance amount, and by repeating this cycle as one feeding cycle, the fixed abrasive wire 2 is fed in one direction. The grooved roller 3' can drive the fixed abrasive wire 2 wound thereon in the reciprocating direction at a predetermined cycle by the driving motor 11.

Fig. 2 (a) and (c) are views showing the positional relationship between the workpiece W and the fixed abrasive wire 202 at the end of cutting and pulling out the workpiece. As shown in fig. 2 (a), at the end of cutting, the workpiece W is positioned below the wire array. Therefore, in order to pull out the workpiece W, it is necessary to move the workpiece W upward so that the fixed abrasive wire 202 passes through the gap between the wafers of the workpiece W cut into a wafer shape, and pull out the fixed abrasive wire 202 relatively downward ((c) of fig. 2).

However, in the case of the conventional wire saw using the fixed abrasive particles, since the clearance between the fixed abrasive particle wire 202 and the workpiece W is small (see fig. 4 (b)), the fixed abrasive particle wire 202 catches the workpiece W, and floats up as shown in fig. 2 (b), thereby generating a saw cut on the cut surface of the workpiece W or generating a wire breakage.

For example, the clearance between the wire and the workpiece W is about 25 μm or more in the free abrasive grain method, and about 6 μm or less in the fixed abrasive grain method.

In order to prevent generation of saw marks or wire breakage, the wire saw 1 of the present invention includes a coolant supply mechanism 7, wherein the coolant supply mechanism 7 supplies a coolant for workpiece cutting to the wire array 4 during cutting of the workpiece by the fixed abrasive wire 2, and supplies a coolant for workpiece drawing to the wire array 4 when the workpiece W is drawn from the wire array 4 after cutting of the workpiece W, the coolant for workpiece drawing being different from the coolant for workpiece cutting and having a higher viscosity than the coolant for workpiece cutting.

As described above, in the wire saw 1 of the present invention, when the workpiece after cutting the workpiece is pulled out, the lubricity of the cut surface of the workpiece is improved by supplying the workpiece-pulling coolant having a higher viscosity than the workpiece-cutting coolant, and therefore, the occurrence of saw marks or wire breakage due to the wire sticking to the workpiece can be suppressed. In particular, when the workpiece after cutting is pulled out, in order to avoid the saw marks generated when the wire contacts the workpiece cutting surface, it is preferable to set the moving speed of the wire to a lower speed than 1/100 or 1/100 or less than the speed when the workpiece is cut, and therefore, when the same coolant as that for cutting the workpiece is supplied to the wire row, the amount of the coolant supplied to the workpiece cutting surface is reduced by setting the wire to the lower speed, and the lubricity of the workpiece cutting surface is remarkably reduced. However, the wire saw 1 of the present invention supplies the coolant for workpiece drawing having a higher viscosity than the coolant for workpiece cutting when drawing the workpiece, and thus can prevent this.

Next, a method for cutting a workpiece according to the present invention will be described by taking a case where the wire saw of the present invention is used as an example.

First, as shown in fig. 1, the wire row 4 is formed by winding the wire 2 having fixed abrasive grains fixed to the surface thereof around a plurality of grooved rollers 3 and 3'. Next, the fixed abrasive wire 2 is reciprocated in the axial direction of the fixed abrasive wire 2 by the driving motor 11. Then, the workpiece feed mechanism 6 cuts and feeds the columnar workpiece W into the wire array 4, thereby cutting the workpiece W at a plurality of positions arranged in parallel in the axial direction.

In the workpiece cutting method of the present invention, in cutting the workpiece by the fixed abrasive wire 2, the coolant for workpiece cutting is supplied to the wire array 4, and when the workpiece W is pulled out from the wire array 4 after cutting the workpiece, the coolant for workpiece pulling out, which is different from the coolant for workpiece cutting and has a higher viscosity than the coolant for workpiece cutting, is supplied to the wire array 4.

This can prevent the wire from catching the cut workpiece and generating saw marks or wire breakage at the cross-section when the workpiece W is pulled out.

The viscosity of the coolant for cutting a workpiece is preferably 5mPas or less at 25 ℃. The lower limit of the viscosity at 25 ℃ of the coolant for cutting a workpiece is not particularly limited, but the coolant for cutting a workpiece contains 99 mass% or more of water as described later, and therefore has a viscosity higher than 0.89 mPas. The viscosity of the coolant for drawing a workpiece is preferably 10mPas or more, more preferably 15mPas or more, and further preferably 20mPas or more at 25 ℃. However, since too high a viscosity makes handling difficult, it is preferably 500mPas or less.

The content of moisture contained in the coolant for cutting the workpiece is preferably 99 mass% or more, and the content of moisture contained in the coolant for drawing the workpiece is preferably 90 mass% or less. The lower limit of the content of moisture contained in the coolant for drawing a workpiece is not particularly limited, and may be set to 70 mass% or more.

Although the cooling effect of the cutting portion is improved and a good Warp quality is easily obtained as the amount of moisture contained in the coolant (coolant for cutting a workpiece) supplied when cutting a workpiece is increased, it is generally preferable that the coolant liquid-receiving portion of the wire saw device contains a component for preventing occurrence of corrosion, that is, a so-called rust inhibitor, because the material of the coolant liquid-receiving portion is made of an alloy mainly containing iron such as carbon steel or indium material. Therefore, the content of moisture contained in the coolant for cutting a workpiece is preferably less than 100 mass%. Further, since there is a possibility that chips generated by cutting the workpiece may be mixed into the coolant for cutting the workpiece, it is preferable to add a dispersant for preventing the chips from sticking to the coolant supply path, and it is preferable to add a pH adjuster for preventing silicon of the chips from reacting with water to generate hydrogen. In addition, an antifoaming agent is preferably added in order to prevent the generation of foam in the tank in which the coolant is circulated and supplied. The total amount of the additives is preferably about 1 mass% or less.

When cutting a workpiece, the above-described coolant for cutting a workpiece having the most suitable physical properties (viscosity) for cutting a workpiece is provided, and the risk of an increase in cutting resistance in a cutting portion and an accompanying increase in temperature of the workpiece caused by the use of a high-viscosity coolant for cutting a workpiece can be eliminated, thereby obtaining good quality of cut pieces, particularly good quality of Warp without deterioration of Warp.

On the other hand, the viscosity of the coolant (coolant for workpiece drawing) supplied when the workpiece is drawn is preferably 10mPas or more, more preferably 15mPas or more, and further preferably 20mPas or more at 25 ℃. By using the coolant for drawing out the work having the above viscosity, the lubricity of the cut surface of the work can be improved. In order to obtain such a viscosity, the amount of water contained in the coolant for drawing a workpiece is set to 90 mass% or less, and a component having a thickening action may be added as the remaining component of 10 mass% or more.

Further, as the workpiece, it is preferable to cut a workpiece having a diameter of 300mm or more. The cutting method of the present application is particularly effective because the length of the fixed abrasive wire adjacent to the workpiece and the distance from the workpiece to be pulled out are longer as the size of the workpiece is larger, and the fixed abrasive wire is more likely to be caught.