A self-rotating beaded necklace and a method of making and using the same

Abstract

The present application relates to cemented carbide bead stringing technical field, specifically, a kind of self-rotating bead and its preparation method and application.The center of the base body of the bead is provided with through hole, and the through hole is in the shape of Laval nozzle;Hard alloy particles are welded on the outer surface of the base body, and the brazing filler layer is arranged on the outer surface of the base body, and a part of the hard alloy particles is embedded in the brazing filler layer;The hard alloy particles have first cutting face and second cutting face, and the intersection line of the first cutting face and the second cutting face is cutting edge, and the cutting edge is perpendicular to the central axis of the base body, and the hard alloy particles are arranged according to the same cutting direction;The edge of the first cutting face away from the cutting edge is in contact with the outer surface of the base body, and the included angle α of the first cutting face and the second cutting face is 30°-50°;The included angle β of the second cutting face and the central axis of the base body is 10°-20°.The bead can be self-rotated under the action of tension.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide bead technology, and more specifically, to a self-rotating bead, its preparation method, and its application. Background Technology

[0002] Carbide beads are made by creating carbide blocks on the surface of a steel substrate, which serve as a wear-resistant and cutting working layer. Carbide beads, steel wire rope, and fixing sleeves together form a carbide wire saw, which is mainly used for cutting underwater reinforced concrete, steel cables, and shipwrecks.

[0003] A wire saw is made by stringing together individual carbide beads. When sawing a steel plate under reciprocating tension, the beads only move slightly and rarely rotate. This results in the carbide particles on the side of the steel plate that are always in contact with the plate, while the carbide particles on the side away from the plate rarely have the opportunity to contact the plate and make a cut. As a result, the utilization efficiency of the carbide beads is extremely low, and the cutting life is short.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The first objective of this invention is to provide a self-rotating bead and a method for preparing the same, wherein the bead is capable of self-rotation under tension.

[0006] The second objective of this invention is to provide a wire saw in which half of the beads on the wire saw are used for milling the object, thereby enhancing cutting efficiency.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: One aspect of the present invention relates to a self-rotating bead, comprising: a substrate, a solder layer, and a plurality of cemented carbide particles; The substrate has a through hole at its center, which is shaped like a Laval nozzle; the cemented carbide particles are welded to the outer surface of the substrate through a brazing filler layer, and a portion of the cemented carbide particles are embedded in the brazing filler layer; The cemented carbide particles have a first cutting face and a second cutting face, the intersection of the first cutting face and the second cutting face is a cutting edge, the cutting edge is perpendicular to the central axis of the matrix, and the cemented carbide particles are arranged in the same cutting direction; The edge of the first cutting face away from the cutting edge contacts the outer surface of the substrate, and the included angle α between the first cutting face and the second cutting face is 30°~50°; the included angle β between the second cutting face and the central axis of the substrate is 10°~20°.

[0008] The beads can rotate under tension.

[0009] Another aspect of the present invention relates to a method for preparing the aforementioned self-rotating beads, comprising the following steps: (a) Hard alloy particles are spot-welded onto the outer surface of the substrate, and a brazing filler layer and flux paste are sequentially coated onto the outer surface of the substrate and then dried to obtain a bead blank; (b) A matching refractory jacket is fitted over the outside of the bead blank, and a graphite rod of matching shape is inserted into the through hole of the substrate to seal the bottom of the bead blank, thus obtaining the bead precursor. (c) Resistance welding is performed on the bead precursor.

[0010] Compared with traditional flame brazing, the method for preparing self-rotating beads described above has better forming quality and higher welding efficiency.

[0011] Another aspect of the present invention relates to a wire saw comprising the aforementioned self-rotating beads or beads prepared by the method for preparing the aforementioned self-rotating beads; Preferably, the beads are installed alternately in opposite directions on the wire rope.

[0012] The wire saw described has a long service life and high cutting efficiency.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The self-rotating bead provided by the present invention is subjected to a tensile force F on the second cutting surface of the cemented carbide particles on the surface of the bead. The tensile force F can be decomposed into a component force Q along the inclined plane and a component force N perpendicular to the inclined plane. The component force Q causes the cemented carbide to cut the steel plate. When the component force N (circumferential force) reaches a certain level, the cemented carbide bead will rotate, thereby achieving uniform wear of the cemented carbide particles and extending the service life of the bead. The through hole in the center of the base is designed as a Laval nozzle shape, which can increase the reciprocating sawing tension, which helps to achieve the self-rotation of the bead, while reducing the wear damage between the cemented carbide bead and the steel wire rope.

[0014] (2) The method for preparing self-rotating beads provided by the present invention uses a resistance welding machine to weld hard alloy beads. Compared with traditional flame brazing, it has better forming quality and higher welding efficiency. A matching refractory jacket is fitted over the bead blank. The refractory jacket has the function of solidification and heat preservation. When brazing, the brazing filler melts into liquid. Under the covering effect of the refractory jacket, the brazing filler melt can be prevented from flowing everywhere. A uniform brazing filler metallurgical layer is formed on the surface of the bead steel substrate. At the same time, the refractory jacket also has the function of heat preservation, which can prevent the loss of heat emitted by the graphite rod.

[0015] (3) The wire saw provided by the present invention has beads installed alternately in opposite directions on a wire rope. When pulled in the forward direction, all the forward beads cut the steel plate, and when pulled back in the reverse direction, all the reverse beads cut the steel plate. All the forward and reverse beads can rotate under the action of N force, which can realize uniform wear of cemented carbide particles, improve the utilization efficiency of cemented carbide particles and the cutting life of the beads. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the structure and force analysis of a self-rotating beaded string; Figure 2 This is a schematic diagram of a method for preparing self-rotating beads; Figure 3 This is a schematic diagram of the particle structure of cemented carbide. Figure 4 This is a schematic diagram showing the included angle of cemented carbide particles; Figure 5 This is a schematic diagram of another cemented carbide particle structure. Figure 6 This is a schematic diagram of the included angle of another cemented carbide particle.

[0018] Figure label: 1-Upper electrode, 2-Upper electrode graphite block, 3-Graphite rod, 4-Substrate, 5-Brain filler layer, 6-Hard alloy particles, 7-Refractory jacket, 8-High temperature resistant material, 9-Lower electrode graphite block, 10-Lower electrode, 11-First cutting face, 12-Second cutting face. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0020] One aspect of the present invention relates to a self-rotating bead, comprising: a substrate 4, a solder layer 5, and a plurality of cemented carbide particles 6; The substrate 4 has a through hole at its center, which is in the shape of a Laval nozzle; the cemented carbide particles 6 are welded to the outer surface of the substrate 4 through a brazing filler layer 5, and a portion of the cemented carbide particles 6 is embedded in the brazing filler layer 5. The cemented carbide particles 6 have a first cutting face 11 and a second cutting face 12. The intersection of the first cutting face 11 and the second cutting face 12 is a cutting edge. The cutting edge is perpendicular to the central axis of the substrate 4. The cemented carbide particles 6 are arranged in the same cutting direction. The edge of the first cutting edge 11 away from the cutting edge is in contact with the outer surface of the base 4. The included angle α between the first cutting edge 11 and the second cutting edge 12 is 30°~50° (e.g., 30°, 34°, 38°, 42°, 46° or 50°). The included angle β between the second cutting edge 12 and the central axis of the base 4 is 10°~20° (e.g., 10°, 12°, 14°, 16°, 18° or 20°).

[0021] In this invention, the beads are self-rotating. A tensile force F is applied to the second cutting surface 12 of the carbide particles 6 on the surface of the beads. This tensile force F can be decomposed into a component force Q along the inclined plane and a component force N perpendicular to the inclined plane. Component force Q causes the carbide to cut the steel plate, and component force N (circumferential force) reaches a certain level, causing the carbide beads to self-rotate (e.g., ...). Figure 1 (As shown).

[0022] The through hole in the center of the base 4 is designed as a Laval nozzle. When the beads are pulled back and forth, the airflow in the through hole is amplified through the inner hole of the Laval nozzle, which increases the speed and forms an airflow thrust. The direction is consistent with the direction of the tension, which can reduce the cutting power of the wire saw. In addition, the through hole of the Laval nozzle shape can reduce the frictional damage of the wire rope at both ends of the beads and improve the life of the beads.

[0023] Preferably, the height of the cemented carbide particles 6 is 6-8 mm (e.g., 6 mm, 7 mm or 8 mm).

[0024] Preferably, the spacing between two adjacent cemented carbide particles 6 is 0.5 to 1 times the height of the cemented carbide particle.

[0025] Preferably, the thickness of the solder layer 5 is 3 / 10 to 8 / 10 of the height of the cemented carbide particles.

[0026] Another aspect of the present invention also relates to a method for preparing the aforementioned self-rotating beads, such as... Figure 2 As shown, it includes the following steps: (a) The cemented carbide particles 6 are spot welded onto the outer surface of the substrate 4. After the outer surface of the substrate 4 is coated with a brazing filler layer and a flux paste in sequence, it is dried to obtain a beaded blank. (b) A matching refractory jacket 7 is fitted over the outside of the bead blank. The refractory jacket 7 is a cylindrical sleeve made of refractory brick. A graphite rod 3 with a matching shape is inserted into the through hole of the base 4 to seal the bottom of the bead blank and obtain the bead precursor. (c) Resistance welding is performed on the bead precursor.

[0027] The method for preparing the beads uses resistance welding, which, compared with traditional flame brazing, results in better forming quality and higher welding efficiency.

[0028] Preferably, the power of the resistance welding is 60~120kW (e.g., 60kW, 70kW, 80kW, 90kW, 100kW, 110kW or 120kW).

[0029] Preferably, the resistance welding time is 40 to 80 minutes (e.g., 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes or 80 minutes).

[0030] Preferably, the thickness of the solder coating is 3 / 10 to 8 / 10 of the height of the cemented carbide particles.

[0031] Preferably, the thickness of the flux paste is 2 / 5 to 3 / 5 of the height of the cemented carbide particles.

[0032] Preferably, the solder layer comprises: copper-based solder paste; the solder layer comprises, by weight, 80-85 parts Cu and 15-20 parts Sn.

[0033] Preferably, the flux paste includes QJ308, which, by mass, comprises 65-70 parts of borax, 25-30 parts of boric acid, and 5-8 parts of potassium fluoride.

[0034] Preferably, the drying temperature is 100~150℃ (e.g., 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃ or 150℃).

[0035] Another aspect of the present invention relates to a wire saw comprising the aforementioned beads or beads prepared by the aforementioned method of preparing the beads; Preferably, the beads are installed alternately in opposite directions on the wire rope.

[0036] The beads are installed alternately in opposite directions on the wire rope. When pulled in the forward direction, all the forward beads cut the steel plate; when pulled back in the reverse direction, all the reverse beads cut the steel plate. All the forward and reverse beads can rotate under the action of N force, which can achieve uniform wear of the cemented carbide particles 6, improve the utilization efficiency of the cemented carbide particles 6 and the cutting life of the beads.

[0037] The embodiments of the present invention will now be described in detail with reference to specific examples and comparative examples.

[0038] Example 1 The hard alloy particle 6 structure provided in this embodiment is as follows: Figure 3 and Figure 4 As shown. The cemented carbide particle 6 consists of an upper inclined surface ABCD, a lower horizontal surface EFGH, a left inclined surface ABFE, a right vertical surface DCGH, a front vertical surface BCGF, and a rear vertical surface AEHD. Among them, inclined surface ABCD is the first cutting face 11, and inclined surface ABFE is the second cutting face 12. The angle α between the first cutting face 11 and the second cutting face 12 is 30°; the angle β between the second cutting face 12 and the central axis of the base is 10°. The intersection line AB of the first cutting face 11 and the second cutting face 12 is the cutting edge. The angle between inclined surface ABCD and the upper horizontal base surface ABC'D' is a positive rake angle. The design of the positive rake angle can make the cutting debris easier to remove and reduce resistance. Surface DCGH is spot welded to the base 4. The size of the cemented carbide particle 6 refers to the length of the longest side BC. Surface ABJI is the cutting base surface in contact with the cutting edge AB.

[0039] Example 2 The only difference between this and the cemented carbide particle 6 in Example 1 is that the included angle α between the first cutting face 11 and the second cutting face 12 is 35°; and the included angle between the second cutting face 12 and the central axis of the substrate is 12°.

[0040] Example 3 The hard alloy particle 6 structure provided in this embodiment is as follows: Figure 5 and Figure 6 As shown. The cemented carbide particle 6 is composed of an upper horizontal surface KLMN, a lower horizontal surface ROPQ, a left inclined surface KLOR, a right vertical surface MPQN, a front vertical surface LOPM, and a rear vertical surface KRQN. Among them, surface KLMN is the first cutting face 11, inclined surface KLOR is the second cutting face 12, and the included angle α between the first cutting face 11 and the second cutting face 12 is 40°; the included angle β between the second cutting face 12 and the central axis of the substrate is 15°, and the intersection line KL of the first cutting face 11 and the second cutting face 12 is the cutting edge. Surface MPQN is spot-welded to the substrate 4. The size of the cemented carbide particle 6 refers to the length of the longest side LM.

[0041] Example 4 The only difference between this and the cemented carbide particle 6 in Example 3 is that the included angle α between the first cutting face 11 and the second cutting face 12 is 50°; and the included angle β between the second cutting face 12 and the central axis of the substrate is 20°.

[0042] Example 5 The self-rotating beads provided in this embodiment include: a substrate 4, a solder layer 5, and several cemented carbide particles 6 from Embodiment 1; The substrate 4 has a through hole at its center, which is in the shape of a Laval nozzle; the cemented carbide particles 6 are welded to the outer surface of the substrate 4, and the brazing filler layer 5 is disposed on the outer surface of the substrate 4, with a portion of the cemented carbide particles 6 embedded in the brazing filler layer 5; The cemented carbide particles 6 have a first cutting face 11 and a second cutting face 12. The intersection of the first cutting face 11 and the second cutting face 12 is a cutting edge. The cutting edge is perpendicular to the central axis of the substrate 4. The cemented carbide particles 6 are arranged in the same cutting direction. The height of the cemented carbide particles 6 is 6 mm; the spacing between two adjacent cemented carbide particles 6 is 4 mm; and the thickness of the brazing filler layer 5 is 3.5 mm.

[0043] The method for preparing self-rotating beads provided in this embodiment includes the following steps: Step 1: Machining the inner hole of the cylindrical base 4 into the required Laval tube-shaped through hole; Step 2: Fix the inner hole of the base 4 onto the rotating bracket, and spot weld the cemented carbide particles 6 in an evenly spaced circular ring shape onto the surface of the base 4 to form a multi-bladed planer with a unidirectional cutting edge. Step 3: Fix the substrate 4 from Step 2, and coat the surface with a layer of brazing filler metal and flux paste in sequence to form a beaded blank, while ensuring that all the cemented carbide particles 6 are exposed on the unidirectional cutting edge. Step 4: After the beaded blank from Step 3 is dried at low temperature and free of moisture, a matching refractory brick cylindrical outer sleeve is fitted on the outside, a matching graphite rod 3 is fitted into the inner hole of the base 4, and the bottom is sealed with high-temperature resistant material 8. Step 5: Place the beaded blank from Step 4 onto the resistance welding machine, so that the two ends of the graphite rod 3 in the inner hole of the substrate 4 are in close contact with the upper electrode graphite block 2 and the upper electrode 1, the lower electrode graphite block 9 and the lower electrode 10. Step 6: Turn on the resistance welding power supply, perform resistance welding at a certain power, maintain for a certain time, and the brazing is completed. Turn off the power to obtain cemented carbide brazed beads.

[0044] In step two, the spacing between the rings is 4mm; In step four, the drying temperature is 100℃. The cylindrical sleeve of the refractory brick has a hole for accommodating the cutting edge of the hard alloy particles 6. The high-temperature resistant material 8 is a material for the furnace body. In step six, the resistance welding machine has a power of 60kW, and the specified time is 80 minutes.

[0045] Example 6 The self-rotating beads provided in this embodiment differ from those in Embodiment 5 in that they use the cemented carbide particles 6 of Embodiment 2, the height of which is 7mm; the spacing between two adjacent cemented carbide particles 6 is 5mm; and the thickness of the solder layer 5 is 4.2mm.

[0046] The method for preparing the self-rotating beads provided in this embodiment differs from that in Embodiment 5 in that the ring spacing is 5mm in step two; the drying temperature is 110℃ in step four; the resistance welding machine power is 70kW in step six; and the specified time is 70min.

[0047] Example 7 The self-rotating beads provided in this embodiment differ from those in Embodiment 5 in that they use the cemented carbide particles 6 of Embodiment 3, the height of which is 8mm; the spacing between two adjacent cemented carbide particles 6 is 6mm; and the thickness of the solder layer 5 is 6.4mm.

[0048] The method for preparing the self-rotating beads provided in this embodiment differs from that in Embodiment 5 in that the ring spacing is 6mm in step two; the drying temperature is 120℃ in step four; the resistance welding machine power is 80kW in step six; and the specified time is 60min.

[0049] Example 8 The self-rotating beads provided in this embodiment differ from those in embodiment 5 in that they use the cemented carbide particles 6 of embodiment 4, with a spacing of 7 mm between two adjacent cemented carbide particles 6; and the thickness of the solder layer 5 is 3.5 mm.

[0050] The method for preparing the self-rotating beads provided in this embodiment differs from that in Embodiment 5 in that the ring spacing is 7mm in step two; the drying temperature is 130℃ in step four; the resistance welding machine power is 100kW in step six; and the specified time is 50min.

[0051] Example 9 The self-rotating beads provided in this embodiment differ from those in Embodiment 5 in that the height of the cemented carbide particles 6 is 8mm; the spacing between two adjacent cemented carbide particles 6 is 8mm; and the thickness of the solder layer 5 is 2.4mm.

[0052] The method for preparing the self-rotating beads provided in this embodiment differs from that in Embodiment 5 in that the ring spacing is 8mm in step two; the drying temperature is 150℃ in step four; the resistance welding machine power is 120kW in step six; and the specified time is 40min.

[0053] Comparative Example 1 Traditional flame-brazed beads. Similar to Example 5, but with three differences: First, the structure of the cemented carbide particles on the surface of the beads is different; the cemented carbide particles are irregularly shaped and cannot form the unidirectional cutting edge with a positive rake angle as shown in Example 5. Second, the inner hole of the beads is a cylindrical hole. Third, the cutting edge height of the cemented carbide particles on the surface of the beads is inconsistent.

[0054] Comparative Example 2 The difference between this and the cemented carbide particle 6 in Example 1 is that the included angle α between the first cutting face 11 and the second cutting face 12 is 60°; and the included angle β between the second cutting face 12 and the central axis of the substrate is 8°.

[0055] The comparative example of beads and their preparation method are the same as in Example 5.

[0056] Experimental Example 1 To investigate the underwater brazing efficiency of the cemented carbide beads in Example 1 of this invention and the existing beads in Comparative Example 1, cemented carbide beads were prepared using the resistance brazing method of this invention and the conventional flame brazing method, respectively. It was verified that flame brazing of cemented carbide beads requires about 2 hours by 2 workers, while resistance brazing of a bead of the same specification requires about 1 hour, which increases the efficiency by 1 time.

[0057] Flame brazing takes a long time, resulting in blackening and oxidation of the bead surface, poor surface forming quality, and uneven solder flow. In contrast, resistance brazing of cemented carbide beads results in less severe oxidation of the surface, better solder flow performance, and higher forming quality.

[0058] Experiment Example 2 To investigate the self-rotation of the cemented carbide beads, the beads from Example 1 were threaded into a steel wire rope and repeatedly sawed a Q235 steel plate (sawed surface 80*25mm). It was found that during the sawing process, the beads could rotate and change position, the cemented carbide particles 6 on the surface of the beads were evenly worn on both sides, and they could be cut for 3 hours and still continue to be cut.

[0059] Subsequently, the existing conventional flame-brazed beads from Comparative Example 1 were threaded into a steel wire rope and repeatedly sawed Q235 steel plates of the same specifications. It was found that the beads could not be rotated and repositioned, and the wear of the cemented carbide particles 6 was uneven. After 1.2 hours of cutting, the steel plate could no longer be sawed, and the wear of the cemented carbide particles 6 on one side was severe.

[0060] When the beads from Comparative Example 2 were threaded into a steel wire rope and repeatedly sawed through a Q235 steel plate, it was found that the beads could not rotate and reposition well, and the steel plate debris cut by the carbide particles 6 was difficult to remove, resulting in high cutting resistance. After 1.8 hours of cutting, the particles were severely worn and could not be cut further.

[0061] Verification has shown that, compared with traditional flame-brazed cemented carbide beads, the cemented carbide beads of this invention can rotate on their own, have high utilization efficiency of cemented carbide particles 6 on the entire surface of the beads, and have a long cutting life.

[0062] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A self-rotating beaded string, characterized in that, include: The matrix, the solder layer, and several cemented carbide particles; The substrate has a through hole at its center, which is shaped like a Laval nozzle; the cemented carbide particles are welded to the outer surface of the substrate through the brazing filler layer, and a portion of the cemented carbide particles are embedded in the brazing filler layer; The cemented carbide particles have a first cutting face and a second cutting face, the intersection of the first cutting face and the second cutting face is a cutting edge, the cutting edge is perpendicular to the central axis of the matrix, and the cemented carbide particles are arranged in the same cutting direction; The edge of the first cutting face away from the cutting edge contacts the outer surface of the substrate, and the included angle α between the first cutting face and the second cutting face is 30°~50°; the included angle β between the second cutting face and the central axis of the substrate is 10°~20°. The height of the cemented carbide particles is 6~8mm; The distance between two adjacent cemented carbide particles is 0.5 to 1 times the height of the cemented carbide particle.

2. The self-rotating beaded string according to claim 1, characterized in that, The thickness of the solder layer is 3 / 10 to 8 / 10 of the height of the cemented carbide particles.

3. A method for preparing self-rotating beads as described in claim 1 or 2, characterized in that, Includes the following steps: (a) Hard alloy particles are spot-welded onto the outer surface of the substrate, and then the outer surface of the substrate is coated with a brazing filler layer and a flux paste in sequence and dried to obtain a bead blank; (b) A matching refractory jacket is fitted over the outside of the bead blank, and a graphite rod of matching shape is inserted into the through hole of the substrate to seal the bottom of the bead blank, thus obtaining the bead precursor. (c) Resistance welding is performed on the bead precursor.

4. The method for preparing self-rotating beads according to claim 3, characterized in that, The power of the resistance welding is 60~120kW; The resistance welding time is 40~80 minutes.

5. The method for preparing self-rotating beads according to claim 3, characterized in that, The thickness of the flux paste is 2 / 5 to 3 / 5 of the height of the cemented carbide particles.

6. The method for preparing self-rotating beads according to claim 3, characterized in that, The solder layer includes: copper-based solder paste; The flux paste includes: QJ308; by weight, QJ308 includes: 65-70 parts of borax, 25-30 parts of boric acid and 5-8 parts of potassium fluoride.

7. The method for preparing self-rotating beads according to claim 3, characterized in that, The drying temperature is 100~150℃.

8. A wire saw, characterized in that, Includes the self-rotating beads as described in claim 1 or 2; the beads are alternately mounted in opposite directions on the wire rope.

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