JP4633082B2 - Resin bond wire saw - Google Patents

Description

  The present invention relates to a resin bond wire saw that increases the flexibility of a core wire, is excellent in bending fatigue strength and twisting strength, and has a reduced amount of change in the wire diameter of the core wire.

  As for the fixed abrasive wire saw, a thin wire and a thick wire are used properly depending on the application. For example, in multi-slice processing, there are many demands for thinning in order to reduce the cutting allowance, and conversely, when used for groove processing, it is necessary to determine the diameter of the core wire according to the required groove width Also, thickening is necessary. In addition, when emphasizing the processing efficiency, it is required to cut under a high tension condition, so that thickening is required.

  However, when the core wire is thickened, the tensile strength is increased, but the fatigue strength against repeated bending and the twisting strength against twisting are lowered. For this reason, the disconnection rate of a wire becomes high and a lifetime is also shortened. As a method for solving this problem, firstly, there is a method for increasing the bending curvature of the wire by increasing the work roller diameter, guide pulley diameter, and bobbin diameter of the machine to which the wire saw is attached as much as possible. However, according to this method, the machine size must be increased, and it is necessary to replace the rollers and pulleys in accordance with the diameter of the core wire, which reduces productivity.

  Secondly, there is a method of using a highly flexible core wire such as a fiber wire, a stainless steel wire, or a copper wire as a material for the core wire. However, according to this method, although the flexibility of the core wire is increased, the tensile strength is low, and a stainless steel wire or a copper wire is liable to be damaged by plastic deformation, so that there is a problem that the cutting accuracy is deteriorated.

Patent Documents 1 and 2 describe a wire saw in which a core wire is formed by twisting a plurality of strands for the purpose of maintaining the flexibility of the core wire. Certainly, maintaining the flexibility of the core wire can be achieved to some extent by making the core wire a stranded wire, but even when a stranded wire is used, the grinding performance of the wire saw is affected by the method of fixing the abrasive grains. For example, when the abrasive grains are fixed by the electrodeposition plating method, the bending fatigue strength and the twisting strength are lowered, and it is difficult to obtain the effect due to the stranded wire.
Also, in the cutting process with a wire saw, the wire is normally reciprocated at a high linear velocity to cut the workpiece while reciprocating, so the wire repeats forward and reverse rotations when moving forward and backward. . In the case of a stranded wire, there is no particular problem when rotating in the same direction as the twist direction, but when rotating in the opposite direction, the strands loosen and spread, so the wire wire diameter changes and machining accuracy is improved. descend.

Japanese Patent Laid-Open No. 11-277398 JP 2001-30178 A

  The present invention was made in order to solve the above-mentioned problems, can maintain the flexibility of the core wire, has excellent bending fatigue strength and twisting strength, and reduces the amount of change in the core wire diameter. An object of the present invention is to provide a resin bond wire saw capable of improving processing accuracy.

In order to solve the above problems, the resin bond wire saw of the present invention has a resin layer made of a first resin so as to surround a core wire formed by twisting a plurality of strands, and is formed on the surface of the resin layer. A resin-bonded wire saw in which abrasive grains are fixed with a second resin, wherein a diameter of a circumscribed circle of a plurality of strand cross sections is 0.20 mm or more and 0.40 mm or less. the cross-sectional area of a region surrounded by the circumscribed circle, Ri 30% or more 55% der less of the cross-sectional area of the circumscribed circle of the strand cross-section, a 20mm or less der Rukoto twisting pitch is 5mm or more of the strands Features.

  Since the resin layer is formed so as to surround the core wire formed by twisting a plurality of strands, even if the strands loosen and spread, the flexible resin layer absorbs the looseness of the strands. Since the wires function so as to be in close contact with each other, the looseness of the core wire can be reduced. Therefore, even if the core wire is formed by twisting the strands, the amount of change in the core wire diameter is reduced, and the processing accuracy can be improved while maintaining the flexibility by twisting the strands. Moreover, since it is a resin bond wire saw, it is excellent in bending fatigue strength and twisting strength as compared with an electrodeposited wire saw.

In the case of using a single core wire instead of a stranded wire, if the core wire diameter is 0.20 mm or more, the flexibility of the core wire is lowered, the bending fatigue strength and the twisting strength are lowered, and it cannot be used. When a core wire is formed by twisting a plurality of strands, even if the diameter of the circumscribed circle of the plurality of strand cross-sections is 0.20 mm or more, the flexibility of the core wire does not decrease, and bending fatigue strength and twist strength Can be secured. If the diameter of the circumscribed circle of the cross section of the plurality of strands is less than 0.20 mm, the advantage of using a stranded wire is reduced because it is the same in terms of flexibility as when a single core wire is used.
Further, when the diameter of the circumscribed circle of the cross section of the plurality of strands exceeds 0.40 mm, it is necessary to use a strand exceeding 0.20 mm, which is not preferable because flexibility is lowered.

When the cross-sectional area of the region surrounded by the outline of the wire cross section and the circumscribed circle of the wire cross section is 30% or more and 55% or less of the cross-sectional area of the circumscribed circle of the wire cross section, grinding to the cutting point The liquid supply amount and the discharge amount of chips can be improved, and the life and processing efficiency of the wire saw are improved.
Grinding fluid supply due to the fact that the cross-sectional area of the region surrounded by the outline of the strand cross-section and the circumscribed circle of the strand cross-section is less than 30% of the cross-sectional area of the circumscribed circle of the strand cross-section The effect of improving the amount and the discharge of chips becomes low and the same as in the case of a single wire, and if it exceeds 55%, the strands are twisted in an unstable state, which is not preferable. This mechanism will be described in detail later with reference to the drawings.

In the present invention, the first resin constituting the resin layer is preferably a thermosetting resin. Since the thermosetting resin has a large shrinkage at the time of curing, it has a great effect of entering the gap between the strands at the time of shrinkage and bringing the strands into close contact with each other. Moreover, it becomes easy to form a resin layer along the surface of a stranded wire by shrinking | contracting.
Moreover, it is preferable that the elasticity modulus of a resin layer is 500 MPa or more and 2000 MPa or less, and the thickness of the said resin layer is 2 micrometers or more and 10 micrometers or less.
Since the elastic modulus of the resin layer is 500 MPa or more and 2000 MPa or less, a highly flexible resin can absorb the looseness of the strands appropriately, and the amount of change in the core wire diameter can be reduced, thus improving the processing accuracy. can do. Moreover, since the resin having an elastic modulus in this range also has an effect of mitigating impact during processing, the thickness of the work-affected layer on the chipping or workpiece cutting surface can be reduced. Here, the work-affected layer thickness is a deteriorated layer generated on the cut surface due to the impact of abrasive grains biting into the workpiece during processing, and this deteriorated layer is removed by lapping and polishing in the subsequent process. It is. Therefore, the yield of the material can be improved by reducing the thickness of the work-affected layer, and the processing time of the subsequent process can be shortened.
If the elastic modulus of the resin layer is less than 500 MPa, the effect of adhering the strands to each other is small, and since the abrasive grains sink into the resin layer during processing, the sharpness is lowered, which is not preferable. On the other hand, if it exceeds 2000 MPa, the flexibility is low, hard and brittle, and therefore the resin is peeled off from the core wire due to load and vibration during processing.

  Moreover, when the thickness of the resin layer is 2 μm or more and 10 μm or less, it is possible to prevent a decrease in tensile strength due to heat due to an increase in the curing time of the resin layer. If the thickness of the resin layer is less than 2 μm, the effect of adhering the strands to each other is small, and it is not preferable because the looseness of the strands cannot be absorbed. If it exceeds 10 μm, the heating time for curing the resin is not preferable. This is not preferable because it becomes longer and the strength of the strands is reduced by heating.

In the present invention, twist pitch of strands Ru der least 20mm below 5 mm.
If the twist pitch of the strands is less than 5 mm, the number of twists increases and the strength of the strands decreases. This is not preferable, and if it exceeds 20 mm, the looseness of the strands increases and the wire diameter changes. As a result, the processing accuracy decreases.

In the present invention, the second resin for fixing the abrasive grains is preferably a photocurable resin.
Since the photocurable resin does not need to be heated at the time of curing, the tensile strength does not decrease under the influence of heat unlike the thermosetting resin. As the photocurable resin, for example, an ultraviolet curable resin, an electron beam curable resin, or a visible light curable resin can be used.

  According to the present invention, the resin bond can maintain the flexibility of the core wire, has excellent bending fatigue strength and twisting strength, and can reduce the amount of change in the core wire diameter to improve the processing accuracy. A wire saw can be realized.

Below, the resin bond wire saw of this invention is demonstrated based on the embodiment.
1 and 2 show the configuration of a resin bond wire saw according to an embodiment of the present invention. FIG. 1 is a diagram showing an example of the structure of a wire saw when viewed in the longitudinal direction, and FIG. 2 (a) shows a cut surface when cut in a direction perpendicular to the longitudinal direction of the resin bond wire saw. Show.

  The resin bond wire saw 1 is formed by forming a resin layer 3 made of a thermosetting resin so as to surround the outer periphery of the core wire 2, and abrasive grains 4 are fixed to the surface of the resin layer 3 by a photocurable resin 5. . The core wire 2 is formed by twisting a plurality of strands 6 together. The twist pitch in the longitudinal direction of the strand 6 is set to 5 mm or more and 20 mm or less.

  As shown in FIG. 2 (b), the circumscribed circle 7 of the cross section of the element wire 6 can be drawn by contacting a plurality of the strands 6 with each other. The diameter of the circumscribed circle 7 of the cross section is 0.20 mm or more. 0.40 mm or less. In addition, the area of a region A (region shown by hatching) A surrounded by the contour line 8 of the cross section of the strand 6 and the circumscribed circle 7 of the cross section of the strand 6 is the breakage of the circumscribed circle 7 of the cross section of the strand 6. The area is set to be 30% or more and 55% or less of the area. The thickness T of the resin layer 3 shown in FIG. 2C is 2 μm or more and 10 μm or less.

The ratio of the area of the region A described above varies depending on the number of strands. The reason why the grinding performance of the resin bond wire saw changes when the number of strands to be twisted is changed will be described with reference to FIG.
FIG. 3 (a) shows a state of grinding a wire saw in which the core wire is formed by one strand 6, that is, a single wire, and FIG. 3 (b) shows a wire saw in which a core wire is formed by twisting two strands 6 together. The state of grinding is shown, and FIG. 3C shows the state of grinding a wire saw in which a core wire is formed by twisting seven strands 6.
As shown in FIG. 3, the grinding process by the wire saw rotates while making a groove in the work material 10, but the grinding fluid is supplied and the chips are discharged in a space surrounded by the work material 10 and the wire saw. Is made. The size of this space differs depending on how the core wire is formed. In the case of using a single wire shown in FIG. 3 (a), the space surrounded by the work material 10 and the wire saw is small, whereas the two wires shown in FIG. 3 (b) are twisted together. , A large space can be secured. However, in the case where the seven strands shown in FIG. 3C are twisted together, the cross-sectional shape is close to that using a single wire, and the space surrounded by the work material 10 and the wire saw is small. When a core wire is formed by twisting a plurality of strands, the space surrounded by the work material 10 and the wire saw described above varies depending on the number of strands to be twisted, and is described based on FIG. It is determined by the ratio of the area ratio of the region A surrounded by the contour line 8 of the cross section of the line 6 and the circumscribed circle 7 of the cross section of the strand 6. The larger the area ratio, the larger the space, and the greater the effect of supplying the grinding fluid and discharging chips. Details regarding this will be described later based on the test results.

In the resin bond wire saw of the present invention, the resin layer 3 is formed so as to surround the outer periphery of the core wire 2. The function of the resin layer 3 will be described with reference to FIG.
FIG. 4A shows a situation in which a plurality of strands 6 twisted together are in contact with each other, and the strands 6 may loosen while grinding progresses. FIG. 4B shows a situation in which the strands 6 are loosened and the spacing between the strands 6 is widened. In the resin bond wire saw of the present invention, the outer periphery of the plurality of strands 6 is surrounded. Since the resin layer 3 is formed and the resin layer 3 has flexibility, the resin layer 3 functions to absorb the looseness of the strand 6 and maintain the shape as the core wire 2. In order for the resin layer 3 to have such a function, the elastic modulus of the resin layer 3 is preferably 500 MPa or more and 2000 MPa or less, and the thickness of the resin layer 3 is preferably 2 μm or more and 10 μm or less. In addition, when there is no resin layer 3, as shown in FIG.4 (c), since the looseness of a strand becomes large and the photocurable resin which has fixed the abrasive grain will peel, sharpness and processing The accuracy is significantly reduced.

The test results are shown below.
A wire bending fatigue test was performed using the apparatus shown in FIG. In this test, when the wire reel repeats normal rotation and reverse rotation, the mounted wire reciprocates through a φ40 pulley, and the bending fatigue strength of the wire is measured. The evaluation was performed by adding a reciprocating motion for 2 hours and determining whether or not the wire was disconnected. When the wire was disconnected, the time until the wire was disconnected was measured. The test results are shown in Table 1.

  According to the test results, by making a stranded wire, it becomes difficult to break even if the wire diameter is increased, but if the diameter of the circumscribed circle of the cross section of the plurality of strands exceeds 0.40 mm, the flexibility decreases. It becomes easy to break.

6A to 6E, the cross-sectional area of the region surrounded by the outline of the cross section of the strand 6 and the circumscribed circle 7 of the cross section of the strand 6, and the cross-sectional area of the circumscribed circle 7 of the cross section of the strand A sample in which a core wire is formed by changing the ratio of (1) and (area ratio in FIG. 6) is shown. A cutting test was performed on this sample, and the results are shown in FIG.
The test method is as follows.
Cutting silicon with multi-wire cutting machine Line speed: 1000m / min
Abrasive grain size: # 400/500
Cutting speed: 1.0 mm / min
Workpiece: 150 mm square The evaluation method was performed by calculating the processing efficiency from the amount actually cut when cutting 100 mm and the processing time. Moreover, the waviness of the cut surface was measured.

  As shown in FIG. 7, when the cross-sectional area of the region surrounded by the outline of the strand cross section and the circumscribed circle of the strand cross section is 30% or more and 55% or less of the cross-sectional area of the circumscribed circle of the strand cross section The sharpness is good and the swell is maintained at a low level. On the other hand, when the area ratio is less than 30%, the sharpness is lowered by the mechanism described with reference to FIG. Further, when the area ratio exceeds 55%, the strands are twisted together in an unstable state as shown in FIG. 6E, so that the sharpness and the processing accuracy are lowered.

Next, a cutting test was performed by changing the elastic modulus of the thermosetting resin constituting the resin layer, and the result is shown in FIG.
The test method is the same as the above cutting test.
As shown in FIG. 8, when the elastic modulus of the thermosetting resin constituting the resin layer is 500 MPa or more and 2000 MPa or less, the sharpness is good and the swell is maintained at a low level. When the elastic modulus of the thermosetting resin is less than 500 MPa, the resin layer is too soft and the abrasive grains are buried in the resin layer, resulting in reduced sharpness and processing accuracy. On the other hand, when the elastic modulus of the thermosetting resin exceeds 2000 MPa, the resin layer becomes too hard and brittle, and thus the resin is peeled off, resulting in a decrease in sharpness and processing accuracy.

  Next, with respect to the core wire formed by twisting three strands having a diameter of 0.18 mm, the torsion test and the tensile test were performed while changing the thickness of the resin layer, and the results are shown in FIG. The torsion test is performed by fixing one side of the core wire on which the resin layer is formed and twisting the opposite side, and the evaluation is performed by twisting in the direction opposite to the twist direction and measuring the number of twists when the strands are detached. This was used as a measure of the wire adhesion strength. The tensile test was performed by a method of pulling the core wire on which the resin layer was formed, and the load at the time of breaking was measured.

  When the thickness of the resin layer is less than 2 μm, since the resin layer is thin, the wire adhesion strength is lowered and the torsional characteristics are lowered. On the other hand, when the thickness of the resin layer exceeds 10 μm, since the resin layer is thick, it takes a long curing time and the wire strength is lowered. Therefore, the thickness of the resin layer is preferably 2 μm or more and 10 μm or less.

Next, the core wire formed by twisting three strands having a diameter of 0.18 mm was subjected to a tensile test and a cutting test while changing the strand twist pitch, and the results are shown in FIG. The tensile test was performed by pulling the core wire on which the resin layer was formed, and the load at the time of breaking was measured. Moreover, the conditions of the cutting test were the same as those described above, and the waviness of the cut surface was measured.
When the strand pitch of the strand is less than 5 mm, the strand strength is reduced because the number of twists is large. On the other hand, when the twisting pitch of the strand exceeds 20 mm, the number of twists is reduced, so that the strand is loosened and the accuracy is lowered. Therefore, it is preferable that the strand pitch of the strand is 5 mm or more and 20 mm or less.

  The present invention is a resin bond wire saw that can maintain the flexibility of the core wire, has excellent bending fatigue strength and twisting strength, and can reduce the amount of change in the core wire diameter and improve the processing accuracy. Can be used as

It is a figure which shows the structure of the resin bond wire saw of this invention. It is a figure which shows the cut surface of the resin bond wire saw of this invention. It is a figure explaining that the grinding performance of a resin bond wire saw changes when the number of strands twisted is changed. It is a figure explaining the effect by having a resin layer formed. It is a figure which shows the test method of a bending fatigue test. It is a figure which shows the sample which formed the core wire by changing the ratio of the cross-sectional area of the area | region enclosed by the outline of the strand cross section and the circumscribed circle of a strand cross section, and the cross-sectional area of the circumscribed circle of a strand cross section. It is a figure which shows the result of the cutting test about the sample shown in FIG. It is a figure which shows the result of having performed the cutting test by changing the elasticity modulus of the thermosetting resin which comprises a resin layer. It is a figure which shows the result of having changed the thickness of the resin layer, and having performed the torsion test and the tension test. It is a figure which shows the result of having performed the tension test and the cutting test by changing the twist pitch of a strand.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin bond wire saw 2 Core wire 3 Resin layer 4 Abrasive grain 5 Photocurable resin 6 Elementary wire 7 circumscribed circle 8 Contour line 10 Work material A area | region

Claims (3)

A resin bond wire saw in which a resin layer made of a first resin is formed so as to surround a core wire formed by twisting a plurality of strands, and abrasive grains are fixed to the resin layer surface with a second resin. The diameter of the circumscribed circle of the plurality of strand cross sections is 0.20 mm or more and 0.40 mm or less, and the cross-sectional area of the region surrounded by the outline of the strand cross section and the circumscribed circle of the strand cross section is the strand cross section 55% der less than 30% of the cross-sectional area of the circumscribed circle of is, resin bond wire saw twisting pitch of the strands is characterized der Rukoto least 20mm below 5 mm.   The first resin constituting the resin layer is a thermosetting resin, the elastic modulus is 500 MPa or more and 2000 MPa or less, and the thickness of the resin layer is 2 µm or more and 10 µm or less. Resin bond wire saw. 3. The resin bond wire saw according to claim 1, wherein the second resin is a photocurable resin.

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