A wire saw and a method of manufacturing

Abstract

The application discloses a wire saw and a preparation method. The wire saw has a structure elongation L%, and the structure elongation L% satisfies: L%=(α*n*d) / D, wherein α is a material coefficient; n is a structure coefficient; d is a monofilament diameter of the wire saw, in mm; D is a diameter of the wire saw, in mm; and S is a twisting pitch of the wire saw, in mm. The structure elongation of the wire saw satisfies the limitation, the twisting quality of the parent wire can be improved, and the cutting effect of the wire saw is optimized.

Description

Technical Field

[0001] This application relates to a wire saw, specifically to a wire saw and its preparation method. Background Technology

[0002] Wire saws consist of abrasive particles of varying sizes bonded to the surface of metal wires of different diameters, electroplated with a metal layer of a certain thickness. Currently, they are used for cutting hard materials such as monocrystalline silicon, polycrystalline silicon, sapphire, gallium arsenide, magnetic materials, and crystal. However, single-strand wire saws currently have relatively small abrasive particles, limiting their capacity to hold abrasive chips and carry lubricant. Furthermore, the low impact toughness of a single wire saw leads to wire breakage, resulting in low production efficiency. Structural cutting wires and twisted wire saws exhibit longitudinal bending deformation, which allows for more space compared to single-wire diamond wire saws to hold abrasive chips and lubricant, improving heat dissipation and cutting efficiency. The helical deformation structure of the wire saw is more conducive to meeting the toughness requirements during cutting, increasing service life and reducing costs. Summary of the Invention

[0003] The purpose of this application is to provide a wire saw and a method for manufacturing it. The wire saw of this application can achieve an accurate elongation rate.

[0004] An embodiment of this application provides a wire saw having a structural elongation of L%, which satisfies:

[0005] Wherein, α is the material coefficient; n is the structural coefficient; d is the diameter of the single wire of the wire saw, in mm; D is the diameter of the wire saw, in mm; and S is the twist pitch of the wire saw, in mm.

[0006] In some embodiments, the structural elongation L% satisfies 0.003L2≤L≤0.1L2, and L2=L1-L, wherein L1 is the first elongation obtained by the wire saw through stress-strain curve testing.

[0007] In some embodiments, the material coefficient α satisfies: 0.08 < α < 0.24.

[0008] In some embodiments, when the number of single filaments in the wire saw is between one and three strands, the structural coefficient n satisfies: 0.5 ≤ n ≤ 1; when the number of single filaments in the wire saw is between three and seven strands, the structural coefficient n satisfies: 1 <n≤1.5。

[0009] In some embodiments, the diameter d of the single wire of the wire saw satisfies: 0.01mm ≤ d ≤ 0.12mm.

[0010] In some embodiments, the diameter D of the wire saw satisfies: 0.02mm ≤ D ≤ 0.5mm.

[0011] In some embodiments, the twist pitch S of the wire saw satisfies: 0.3mm ≤ S ≤ 5mm.

[0012] An embodiment of this application also provides a method for preparing a wire saw, comprising the following steps: rotating a core wire at one point to control the twisting of the rope; straightening, removing stress by reverse rotation, electroplating, and obtaining the wire saw; during the electroplating process, controlling the electroplating tension to 30% to 45% of the wire saw's breaking force.

[0013] In some embodiments, the wire saw is made of at least two identical core wires twisted together.

[0014] In some embodiments, the wire saw comprises 3 to 7 core wires.

[0015] The beneficial effects of this application are as follows: Compared with the prior art, this application provides a wire saw and a method for manufacturing it. The wire saw of this application has a structural elongation of L%, which satisfies the following: Where α is the material coefficient; n is the structural coefficient; d is the diameter of the single wire of the wire saw (in mm); D is the diameter of the wire saw (in mm); and S is the twist pitch of the wire saw (in mm). The structural elongation of the wire saw in this application meets the constraint. This constraint is obtained by experimentally obtaining a series of tensile data, combining them with cutting feedback data, and then using linear regression fitting to obtain the range of values ​​for the structural coefficient and the material coefficient. Finally, the expression for the structural elongation is obtained. The range of values ​​for the structural coefficient and the range of the calculated structural elongation are obtained by performing the above linear regression after screening the optimal cutting data. This can improve the quality of the main wire twisting and optimize the wire saw cutting effect. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the cross-sectional structure of the busbar in an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the cross-sectional structure of the wire saw in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the wire saw structure in an embodiment of this application;

[0020] Figure 4The figures show the tensile curves of the 4*0.025mm tungsten wire busbar in Embodiment 3 of this application, where Figure A is the tensile curve and Figure B is a partial view of the tensile curve.

[0021] Figure 5 Figure A shows the tensile curve of the 7*0.038mm steel wire busbar in Embodiment 5 of this application, where Figure A is the tensile curve and Figure B is a partial view of the tensile curve.

[0022] Figure 6 The tensile curves of the 3*0.038mm wire saw in Embodiment 7 of this application are shown, where Figure A is the tensile curve and Figure B is a partial view of the tensile curve.

[0023] Figure 7 Stress-strain curves were obtained for the 0.040mm, 0.081mm and 0.119mm steel wires in this application under tension. Figure A shows the tension curve of the 0.040mm steel wire, Figure B shows the tension curve of the 0.081mm steel wire, and Figure C shows the tension curve of the 0.119mm steel wire.

[0024] Figure 8 An optical microscope image of the busbar prepared by the 7*0.110mm tungsten wire in Example 1 of this application;

[0025] Figure 9 An optical microscope image of the busbar prepared by the 4*0.025mm tungsten wire in Example 3 of this application;

[0026] Figure 10 An optical microscope image of the busbar prepared from 7*0.038mm steel wire in Embodiment 5 of this application;

[0027] Figure 11 An optical microscope image of the wire saw made from 3*0.038mm steel wire in Example 7 of this application;

[0028] Figure 12 This is a scanning electron microscope image of the wire saw made from 3*0.025mm steel wire in Example 9 of this application;

[0029] Figure 13 An optical microscope image of a wire saw prepared using existing technology. Detailed Implementation

[0030] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are used only as illustrative marks and do not impose numerical requirements or establish an order. Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and conciseness and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. Additionally, whenever a numerical range is specified in this document, it means that any referenced number (fraction or integer) within the range is included.

[0031] Surface-twisted wire saws with two or more strands have a larger surface area than equivalent single-wire wire saws. These saws have more surface area to carry silicon material, coolant, and particles, effectively improving cutting force and efficiency. For example... Figure 1 As shown, taking diamond wire saws (diamond wire) as an example, the degree of deformation of each wire in the twisted wire saw and the structure of the diamond wire determine its performance; therefore, it is necessary to control the performance of the diamond wire. Based on the advancement of wire thinning, the strength of high-carbon steel diamond wire has reached 5200 MPa, and the wire diameter has been reduced to 30 μm; the strength of tungsten wire has reached 7000 MPa, and the wire diameter has been reduced to 20 μm. For example... Figure 2 As shown, diamond wire is formed by twisting two or more identical or different metal wires as single filaments to form a main wire. The twist direction is the direction of the twist helix, which can be divided into right-handed and left-handed (S or Z direction). The twist angle α is the angle between the twist and the center line. The metal wire has a roughly circular or polygonal cross-section, and its structure is as follows. Figure 1 and Figure 2 As shown, with such a fine wire diameter, it is necessary to increase the deformation of the single filament to improve the stability of the diamond wire, i.e., a smaller twist pitch S and a larger twist angle α. The deformation applied to the single filament can be divided into elastic deformation and plastic deformation. When the wire saw is in a relaxed state, i.e., no tension is applied, due to the helical structure of the single filament and the constraint of other single filaments, the elastic deformation disappears and springs back, resulting in gaps in the wire saw. This leads to inaccurate measurement of elongation, making it impossible to accurately obtain the elongation of the diamond wire and affecting the performance of the wire saw.

[0032] This application provides a wire saw with a structural elongation of L%, which satisfies the following: Where α is the material coefficient; n is the structural coefficient; d is the diameter of the single wire of the wire saw, in mm; D is the diameter of the wire saw, in mm; and S is the twist pitch of the wire saw, in mm.

[0033] This application uses an Instron tensile testing machine to stretch diamond wire ropes of different materials, wire diameters, and structures. Figure 5 The image shows the tensile curve of a wire saw made from 7*0.038mm steel wire. Figure 6 The tensile curve of a wire saw made from 3*0.038mm steel wire is shown. The applicant found that during tensile deformation, as the tension of a single wire gradually increases, the spiral fills the surrounding gaps. At this point, the strength and strain are not linearly related. With further increases in tension, the wire saw undergoes elastic deformation and then plastic deformation until it breaks. The process of the spiral filling the gaps represents a structural change; elastic deformation has not yet fully occurred at this stage. The change exhibited by the wire saw during this stage is the structural elongation, the length of which is the distance between the intersection of the extension line of the elastic deformation stage and the abscissa and the origin. Figure 7 Stress-strain curves were obtained by stretching steel wires of 0.040 mm, 0.081 mm, and 0.119 mm, respectively. The elastic deformation stage was extended to the x-axis, almost intersecting the origin, with no structural elongation. Figure 7 A single busbar exhibits a distinct plastic deformation stage, while Figure 5 and Figure 6 The absence of a plastic deformation stage indicates that the plasticity of the main wire is consumed during the twisting of multiple wires. This further indicates that the wire saw elongates due to springback under no-tension conditions after twisting. This application controls the elongation of the structure within the above range, which can improve the cutting performance of the wire saw.

[0034] The applicant discovered that the structural elongation L% of the wire saw satisfies: 0.003L2 ≤ L ≤ 0.1L2, L2 = L1 - L, where L1 is the first elongation obtained by the wire saw through stress-strain curve testing. Wire saws within this range exhibit superior cutting efficiency and quality. If the structural elongation L% exceeds this range, it will lead to higher single-wire stress, reduced adhesion between the main wire and the plating, increased susceptibility to plating delamination, and increased probability of wire breakage due to wire mesh instability. Conversely, if the structural elongation L% is below this range, the wire saw will deform less, increasing the grinding cycle of the effective cutting particles on the cutting material and thus increasing the probability of wire marks. In a specific application example, the ratio of the structural elongation to the actual elongation of the wire saw is controlled to be between 0.3% and 10%.

[0035] In some embodiments, the first elongation L1% is tested by stretching the wire saw to obtain a stress-strain curve, thereby obtaining the first elongation L1% of the wire saw.

[0036] In some embodiments, the wire saw of this application is made of multiple strands of single wire twisted together. This application can accurately characterize the elongation of the wire saw by correcting the first elongation rate L1% obtained by measurement and obtaining the second elongation rate L2%, and further control the structural elongation rate within the range of 0.003L2≤L≤0.1L2.

[0037] In some embodiments, the structural elongation can also be controlled by controlling the tension of the wire saw during the twisting process. Specifically, the gap between adjacent main strands in the twisted wire contributes to the structural elongation issue. Furthermore, the structural elongation is also closely related to the twisting process. Due to the increasing thinning of the wire, the breaking strength of a single main strand decreases as the diameter decreases. Therefore, the precision of controlling the tension of the main strands during production is becoming increasingly stringent, especially for wire saws with a large number of strands. Because of the differences in tension among multiple strands, the main strands may become loose (an abnormal decrease in the tension of a single main strand). Therefore, controlling the tension during the twisting process can control the structural elongation.

[0038] In some embodiments, the material coefficient α satisfies: 0.08 < α < 0.24. For example, if the monofilament is carbon steel wire, the material coefficient α satisfies: 0.12 < α < 0.24. If the monofilament is tungsten wire, the material coefficient α satisfies: 0.08 < α < 0.2.

[0039] In some embodiments, when the number of single wires in the wire saw is more than one strand and less than three strands, the structural coefficient n satisfies: 0.5≤n≤1.

[0040] In some embodiments, when the number of monofilaments in the wire saw is between three and seven, the structural coefficient n satisfies: 1 <n≤1.5。

[0041] In some embodiments, the diameter d of the wire saw wire satisfies: 0.01mm ≤ d ≤ 0.12mm, such that the diameter d of the wire wire can be any value or a range of any two values ​​from 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, and 0.12mm.

[0042] In some embodiments, the diameter D of the wire saw satisfies: 0.02mm≤D≤0.5mm, such that the diameter D of the wire saw takes any value or a range of any two values ​​from 0.02mm, 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm.

[0043] like Figure 2 As shown, the diameter Dmm of the wire saw is the sum of the diameter D1mm of the main wire, the thickness of the coating, and the size of the diamond particles. The sum of the diameter D1mm of the main wire and the thickness of the coating is D2mm.

[0044] In some embodiments, the twist pitch S of the wire saw satisfies: 0.3mm ≤ S ≤ 5mm, such that the twist pitch S of the wire saw takes any value or a range of any two values ​​from 0.3mm, 1mm, 2mm, 3mm, 4mm, and 5mm. This application controls the twist pitch S of the wire saw within this range to improve the quality of the wire saw. If the twist pitch S is too small, the breakage rate of the main wire will decrease, the coating will be easy to peel off, and the probability of wire breakage will increase; if the twist pitch S is too large, it will lead to uneven coating distribution, increase the grinding cycle of the effective cutting particles on the cutting material, and increase the probability of wire marks.

[0045] In some embodiments, the twist angle α1 of the wire saw is in the range of 0.3 to 25°, such as any value or a range of any two values ​​among 0.3°, 1°, 5°, 10°, 15°, 20°, and 25°.

[0046] In some embodiments, the tensile properties of the wire saw are tested by a tensile testing machine, such as by testing the plasticity of the wire saw or busbar.

[0047] Surface-twisted wire saws with two or more strands have a larger surface area than equivalent-sized single-wire wire saws. Surface-twisted wire saws have more surface area to carry silicon material, coolant, and particles, effectively improving cutting force and efficiency. Due to the gaps between adjacent wires, the volume of a surface-twisted wire saw is smaller than that of an equivalent-sized single-wire wire saw. Among the following four structures, seven-strand wires have the highest volume ratio, with closely packed single-wire wires accounting for 77.8% of the volume, exhibiting the highest stability. Three-strand wires are next, accounting for 64.5% of the volume. Two-strand and four-strand wires are lower, accounting for about half of the volume. The lower the volume ratio, the lower the corresponding breaking force. Although finer single wires can provide higher strength, it cannot compensate for the decrease in breaking force caused by the lack of volume. As shown in Table 1:

[0048] Table 1 Relationship between core wire and busbar

[0049]

[0050]

[0051] Based on the aforementioned relationship between the core wire and the busbar, it can be seen that the busbar of a wire saw is made of three or seven strands of metal wire of the same material and diameter twisted together. Three-strand or seven-strand wire saws offer higher structural stability. A wire saw refers to a structure where the outer circumference of the busbar has a coating and abrasive particles.

[0052] In some embodiments, the carbon content of the busbar is not less than 0.9%.

[0053] In some embodiments, the thickness of the wire saw coating is 2μm to 50μm, such as any value or a range of any two values ​​from 2μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, and 50μm. In some embodiments, the thickness of the wire saw coating is approximately 20% to 50% of the abrasive particle size. If the coating is too thin, the abrasive particles are buried too shallowly in the coating, making it easy for particles to fall off during the cutting process; if the coating is too thick, it is difficult to remove abrasive debris during the cutting process, and it may even block the wire and cause it to break.

[0054] In some embodiments, the wire saw's plating includes nickel.

[0055] In some embodiments, the abrasive microparticles are one or a mixture of several of the following: diamond particles, boron nitride particles, silicon nitride particles, boron carbide particles, silicon carbide particles, corundum particles, and tungsten carbide particles. In other embodiments, the particle size of the abrasive microparticles is 5 μm to 60 μm, such that the particle size of the abrasive microparticles is any value or a range of any two values ​​among 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, and 60 μm.

[0056] This application provides a method for preparing a wire saw, comprising the following steps: rotating the core wire at one point to control the twisting of the rope; straightening, removing stress by reverse rotation, electroplating, and obtaining the wire saw; during the electroplating process, controlling the electroplating tension to 30% to 45% of the wire saw's breaking force.

[0057] This application controls the tension during the electroplating process to 30%–45% of the wire saw's breaking force. Increasing the tension of the busbar during electroplating not only improves the dimensional stability of the wire saw but also causes slight elastic deformation of the busbar before electroplating. At this point, the stress in the plating layer is lower, the tension at the cutting end is reduced, and the probability of plating peeling decreases, thus improving the performance of the prepared wire pitch. In existing technologies, the wire saw tension is mostly set at 50%–55% during the cutting process, while the take-up tension during twisting and electroplating is mostly 10%–20% of the breaking force. However, lower tension may not completely eliminate loose wire, leading to uneven structure after electroplating, such as… Figure 13As shown, in the middle section of the wire saw, although the tension is controlled at around 20% during electroplating, uneven structure still occurs after electroplating. The breaking point of this section of the wire saw is 4.6N (the breaking point in the nearby area with a more uniform structure is 7.8N). During cutting, the tension applied to this specification of wire saw can reach 4N, thus the risk of wire breakage is high. This application can increase the tension to 30% to 45% of the breaking force during electroplating. If there are individual loose areas, the applied tension can convert the defects into structural elongation, which can disperse the point defects shown in the figure below. This allows the nearby busbars to share the structural changes caused by uneven tension during twisting, reducing the risk of wire breakage during cutting.

[0058] Examples 1-9:

[0059] Multiple core wires are rotated at one point to form a twisted rope. The rope is then straightened by a straightener, and stress is removed by reverse rotation. The rope is then subjected to alkaline washing, water washing, acid washing, water washing, sanding (bonding), pre-plating, electroplating, and the electroplating tension is controlled at 35% to 40% of the breaking force of the wire saw. The rope is then washed, dried, and wound up to obtain the busbar. The specific parameters and test results of the busbar are shown in Tables 2 and 3.

[0060] Performance testing

[0061] (1) Elongation test: Instron tensile testing machine was used to stretch diamond wire rods of different materials, wire diameters, and structures. The test results are as follows: Figures 4-7 As shown.

[0062] (2) Strength: The tensile test method of non-ferrous metal wire is adopted, and the national standard is GB / T 10573-2020.

[0063] (3) Wire breakage rate: Client data. The calculation method for the wire breakage rate is the number of wire breaks during the cutting process divided by the number of cuts.

[0064] (4) Line loss: Client data. The line loss is calculated as the average line loss per silicon wafer.

[0065] Table 2. Structural elongation, first elongation, and second elongation of diamond wire rods or wire saws of different materials, wire diameters, and structures.

[0066]

[0067]

[0068] Table 3 Test results of different busbar or wire saw strength, breakage rate, and wire loss

[0069]

[0070]

[0071] Results analysis:

[0072] As can be seen from the results of Examples 2-3 and Tables 2 and 3, the materials used in Examples 2-3 are all tungsten wires, but the structures are different. The obtained structural elongation L% is within the predicted range of the theoretical structural elongation, indicating that the structural elongation of the wire saw can be determined by the material properties. However, the breakage rate of the four-strand wire is significantly higher during the cutting process. This is attributed to the fact that the density of the main wire of the four-strand wire is lower than that of the three-strand wire during the cutting process, thus reducing the stability.

[0073] As can be seen from the results of Examples 7-9 and Tables 2 and 3, Examples 7-9 all used steel wire, and the structure was three-strand wire, only the wire diameter was different. The obtained structural elongation L% was within the predicted range of the theoretical structural elongation. The wire breakage rate did not show an obvious pattern. However, the wire consumption increased as the wire diameter decreased. This is attributed to the fact that the cutting force decreased as the wire diameter decreased (due to the difference in wire diameter, the outer surface area of ​​the wire saw was different. In order to compare the cutting effect under the same environment, the coating thickness and particle number were designed almost proportionally to the wire diameter distribution during the electroplating and sandblasting process).

[0074] As can be seen from the results of Examples 2, 5, and 7, as well as Tables 2 and 3, when the wire diameters are similar but the structures used are different, the outer diameter of the seven-strand wire increases, and the resulting structural elongation L% is within the predicted range of the theoretical structural elongation. The cutting performance of the seven-strand wire is slightly worse, which may be because the contact area between the surrounding six strands and the coating is smaller, making the coating easier to peel off, resulting in an increase in wire breakage.

[0075] As can be seen from the results in Table 2, the structural elongation of the wire saw in this application can be determined by the material properties. The obtained structural elongation L% is within the predicted range of the theoretical structural elongation, thus improving the cutting performance of the wire saw. This application corrects the elongation obtained through the tensile curve by subtracting the structural elongation L%, maintaining an error range of 0.007–0.063 with the tested elongation. Wire saws with structural elongation within this range can improve the lifespan of the wire saw during actual cutting.

[0076] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0077] The foregoing has provided a detailed description of a wire saw and its preparation method according to the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A wire saw, characterized in that, The wire saw has a structural elongation rate L%, which satisfies the following: ; Wherein, α is the material coefficient; n is the structural coefficient; d is the diameter of the single wire of the wire saw, in mm; D is the diameter of the wire saw, in mm; and S is the twist pitch of the wire saw, in mm. The structural elongation L% satisfies 0.003L2≤L≤0.1L2, and L2=L1-L, where L1 is the first elongation obtained by the wire saw through stress-strain curve testing.

2. The wire saw according to claim 1, characterized in that, The material coefficient α satisfies: 0.08 < α < 0.

24.

3. The wire saw according to claim 1, characterized in that, When the number of single wires in the wire saw is more than one strand and less than three strands, the structural coefficient n satisfies: 0.5≤n≤1; When the number of single wires in the wire saw is between three and seven, the structural coefficient n satisfies: 1 <n≤1.5。 4. The wire saw according to claim 1, characterized in that, The diameter d of the single wire of the wire saw satisfies: 0.01mm≤d≤0.12mm.

5. The wire saw according to claim 1, characterized in that, The diameter D of the wire saw satisfies: 0.02mm≤D≤0.5mm.

6. The wire saw according to claim 1, characterized in that, The twist pitch S of the wire saw satisfies: 0.3mm≤S≤5mm.

7. The wire saw according to claim 1, characterized in that, The wire saw includes a busbar and a coating, the thickness of which is 2μm to 50μm.

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