JP2023092010A - Cutting blade, glass fiber cutting device, glass fiber manufacturing method, and cutting blade manufacturing method - Google Patents

Abstract

To reliably suppress generation of a crack in a junction of a cutting blade.SOLUTION: A cutting blade 4 includes: a blade part 6 including a cemented carbide; a substrate part 7 including a carbon tool steel; and a junction 8 including nickel or cobalt and joining the blade part 6 to the substrate part 7. The junction 8 includes a dendrite layer 9. The number of voids V having 50 μm or more of equivalent circle diameter is two or less per 1 mm2 at any orthogonal cross section of the junction 8 relative to a longitudinal direction X of the cutting blade 4.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a technique for cutting glass fibers into a predetermined length.

A glass fiber cutting device includes a cutting roll having a plurality of cutting blades and a contact roll made of rubber opposed thereto. Cutting glass fibers (chopped strands) are manufactured by continuously supplying long glass fibers between a cutting roll and a contact roll. Cut glass fibers are used as reinforcing materials in a wide range of fields such as automobiles, electric/electronic equipment, and housing equipment.

For example, in Patent Document 1, the cutting blade includes a blade portion made of cemented carbide, a base portion made of carbon tool steel, and a joint portion (alloy layer) that joins the blade portion and the base portion. something is disclosed. The joint is made of nickel alloy or cobalt alloy.

Such a cutting blade is excellent in wear resistance because the cutting edge is made of cemented carbide, and is excellent in impact resistance because the base is made of carbon tool steel. In addition, since nickel or cobalt is dissolved in the carbon tool steel and the cemented carbide, the bonding strength between the blade and the base is increased. As a result, there is an advantage that the cutting blade can be used for a long period of time and is less likely to break even if an excessive impact load is applied to the cutting blade.

JP 2008-100348 A

In this type of cutting blade, a bonding material made of nickel or cobalt is placed between the blade portion and the base portion, and the bonding material is heated by laser irradiation to bond the blade portion and the base portion. manufactured.

However, depending on the type of laser used (e.g., _CO2 laser), the amount of heat applied to the joint between the blade and the base may be excessive, and as a result, long-term use of such cutting blades may cause the joint to lose heat. There is a problem that cracks occur. Such cracks can cause breakage of the cutting blade.

An object of the present invention is to reliably suppress the occurrence of cracks in the joints of cutting blades.

(1) The present invention, which has been devised to solve the above problems, provides a blade portion containing cemented carbide, a base portion containing carbon tool steel, a blade portion and the base portion joined together, and containing nickel or cobalt. and a joint portion, wherein the joint portion has a dendrite layer, and in any cross section of the joint portion perpendicular to the longitudinal direction of the cutting blade, there are 2 voids with an equivalent circle diameter of 50 μm or more per ¹ mm 2 It is characterized by the following. Here, the "perpendicular cross section of the joint" includes the interface between the joint and the blade, and the interface between the joint and the base. By "equivalent circle diameter" is meant the diameter of a circle having an area equal to the area of the void. "Arbitrary orthogonal cross-section" means one randomly selected orthogonal cross-section with respect to the longitudinal direction of the cutting blade.

By doing so, the bonding strength between the blade portion and the base portion is increased due to the anchoring effect of the dendrite layer. Also, the number of large voids (cavity defects) included in the joint is small. Therefore, it is possible to reliably prevent cracks from occurring in the joint starting from voids.

(2) In the configuration of (1) above, it is preferable that the dendrite layer is formed over the entire thickness direction of the cutting blade.

By doing so, the bonding strength between the blade portion and the base portion is further improved.

(3) In the configuration of (1) or (2) above, it is preferable that the number of voids contained in the dendrite layer is 10 or less in the orthogonal cross section of the joint.

By doing so, it is possible to more reliably improve the bonding strength of the dendrite layer.

(4) In any one of the above configurations (1) to (3), it is preferable that voids having an equivalent circle diameter of 20 μm or more are 4 or less per 1 mm ² in the orthogonal cross section of the joint.

By doing so, the number of small voids included in the joint portion is also reduced, so cracks originating from the voids are less likely to occur.

(5) In any one of the above configurations (1) to (4), the number of voids with an equivalent circle diameter of 10 μm or more is 0.1 mm at the interface between the joint and the blade in the orthogonal cross section of the joint. It is preferable that it is 3 or less per ² .

In general, cracks are particularly likely to occur at the interface between the joint and the blade. Cracks are less likely to occur at the interface between the edge and the blade.

(6) In any one of the above configurations (1) to (5), the number of voids with an equivalent circle diameter of 50 μm or more included in the orthogonal cross section of the joint at one end in the longitudinal direction of the cutting blade is the number of voids in the cutting blade. The thickness of the dendrite layer contained in the joint at one end in the longitudinal direction of the cutting blade is greater than the number of voids with an equivalent circle diameter of 50 μm or more contained in the orthogonal cross section of the joint at the other end in the longitudinal direction. It may be greater than the layer thickness of the dendrite layer included in the joint at the other longitudinal end of the blade.

For example, as in the configuration (10) described later, in the joining step, if the scanning speed of the fiber laser at one end of the bonding material is slower than the scanning speed of the fiber laser at the other end of the bonding material, one end of the bonding material The amount of heat supplied to the part becomes relatively large. Therefore, in the manufactured cutting blade, the number of voids with an equivalent circle diameter of 50 μm or more included in the orthogonal cross section of one end of the joint is less than the number of voids with an equivalent circle diameter of 50 μm or more included in the orthogonal cross section of the other end of the joint. may be greater than the number of In this case, there is concern that cracks originating from voids are more likely to occur at one end of the joint than at the other end of the joint. However, in the above configuration, since the thickness of the dendrite layer included in one end of the joint is greater than the thickness of the dendrite layer included in the other end of the joint, the joint strength at the one end of the joint is reduced. is relatively high. Therefore, a state in which cracks are less likely to occur in the joint is maintained.

(7) The present invention, invented to solve the above problems, is a glass fiber cutting device comprising a cutting blade having any one of the above configurations (1) to (6), The glass fiber is cut to a predetermined length by

In this way, chopped strands can be stably manufactured.

(8) The present invention, which has been devised to solve the above problems, is a method for producing glass fibers, wherein a cutting blade having any one of the above (1) to (6) is used to cut glass fibers into a predetermined shape. It is characterized by comprising a cutting step of cutting to length.

In this way, chopped strands can be stably manufactured.

(9) The present invention, which has been devised to solve the above problems, is a bonding preparation method in which a bonding material containing nickel or cobalt is arranged between a blade containing cemented carbide and a base containing carbon tool steel. and, after the bonding preparation step, a bonding step of heating the bonding material by irradiating the fiber laser and bonding the blade portion and the base portion.

If a fiber laser is used in the joining process in this way, a dendrite layer is formed in the joint portion of the manufactured cutting blade, and the number of voids is greatly reduced. Therefore, it is possible to provide a cutting blade that is less susceptible to cracks originating from voids in the joint.

(10) In the above configuration (9), in the joining step, the fiber laser is scanned from one end side of the joining material toward the other end side along the longitudinal direction of the cutting blade, and the one end of the joining material It is preferable that the scanning speed of the fiber laser at is slower than the scanning speed of the fiber laser at other portions including the other end portion of the bonding material.

If the scanning speed of the fiber laser at the one end of the joint material is relatively slowed down in this way, the amount of heat supplied from the fiber laser at the one end of the joint material becomes relatively large. This amount of heat melts one end of the bonding material and preheats other portions including the other end of the bonding material. Therefore, the bonding material can be sufficiently melted even if the scanning speed of the fiber laser is relatively high in other portions including the other end of the bonding material. Therefore, it is possible to firmly join the blade portion and the base portion while shortening the time required for the joining step.

ADVANTAGE OF THE INVENTION According to this invention, it can suppress reliably that a crack arises in the junction part of a cutting blade.

1 is a side view showing a glass fiber cutting device according to an embodiment of the present invention; FIG. It is a front view of a cutting blade according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2; It is an example of an electron microscope image of a cross section orthogonal to the longitudinal direction of the cutting blade. It is an example of an electron microscope image of a cross section orthogonal to the longitudinal direction of the cutting blade. FIG. 4 is a diagram schematically showing a cross section of the joint along the longitudinal direction of the cutting blade; It is a flow figure showing a manufacturing method of a cutting blade concerning an embodiment of the present invention. It is sectional drawing which shows the joining preparation process included in the manufacturing method of a cutting blade. FIG. 4 is a cross-sectional view showing a joining step included in the manufacturing method of the cutting blade; It is a front view which shows the joining process included in the manufacturing method of a cutting blade.

EMBODIMENT OF THE INVENTION Hereinafter, it demonstrates, referring drawings for the form for implementing this invention. Note that X, Y, and Z in the figure are in an orthogonal coordinate system.

As shown in FIG. 1, a glass fiber cutting apparatus 1 according to the present embodiment includes a cutting roll 2 and a contact roll 3 opposed thereto.

The cutting roll 2 has a plurality of cutting blades 4 radially on its outer peripheral surface. In this embodiment, the plurality of cutting blades 4 are provided at equal intervals in the circumferential direction of the outer peripheral surface of the cutting roll 2 .

The contact roll 3 has a rubber layer 5 on its outer peripheral surface.

In the cutting step included in the method for producing glass fibers according to the present embodiment, long glass fibers G are continuously supplied between the cutting roll 2 and the contact roll 3 while the cutting roll 2 and the contact roll 3 are rotated. , glass fibers (chopped strands) S cut to a predetermined length (for example, 1.5 to 12 mm) by the cutting blade 4 are produced. The cut glass fibers S are used, for example, in fiber reinforced thermoplastics (FRTP) and glass fiber reinforced cements (GRC). The glass fibers G and S may be monofilaments, but in the present embodiment, a large number of monofilaments are bundled with a sizing agent.

As shown in FIGS. 2 and 3, the cutting blade 4 includes a blade portion 6, a base portion 7, and a joint portion 8 for joining a base end 6b of the blade portion 6 and a tip end 7a of the base portion 7 together.

The thickness (dimension in the Z direction) of the cutting blade 4 is preferably 0.3 to 4.5 mm, more preferably 0.3 to 1.5 mm. This is because if the thickness of the cutting blade 4 becomes too small, the strength of the cutting blade 4 decreases, and if the thickness of the cutting blade 4 becomes too large, it becomes difficult to shorten the cut length of the glass fiber G.

The blade portion 6 is made of cemented carbide, and has a sharp tip 6a. As the cemented carbide, it is possible to use an extremely hard alloy obtained by mixing and sintering a powder of a metal element carbide and a metal powder. It is preferable that the cemented carbide has excellent wear resistance and can be reused by polishing even if it is worn. Specifically, WC--Co, WC--TaC--Co, WC--TiC--Co, and WC--TiC--TaC--Co alloys can be used, and the coefficient of thermal expansion of these alloys is 25-200. 48 to 62×10 ^-7 /°C in the temperature range of °C.

For example, the blade portion 6 is made by mixing 85 to 95% by mass of tungsten carbide (WC) powder with an average particle size of 0.3 to 1.0 μm and 5 to 15% by mass of cobalt (Co) powder and sintering. It can be obtained by molding into a predetermined size and shape (for example, the dimension from the proximal end 6b to the distal end 6a of the blade portion 6 is 3 to 7 mm).

The base portion 7 is made of carbon tool steel. Carbon tool steel is made by quenching and tempering iron containing carbon. Carbon tool steel preferably has excellent impact resistance. Specifically, SK-5, SK-2, etc. can be used, and their coefficient of thermal expansion is 100 to 120×10 ^-7 /°C in the temperature range of 25 to 200°C.

The base portion 7 is formed by quenching and tempering iron (Fe) containing 0.8 to 1.3% by mass of carbon (C) so as to have a predetermined shape (for example, from the base end 7b to the tip 7a of the base portion 7). 12 to 20 mm) can be obtained by molding.

The Vickers hardness of the blade portion 6 is preferably 2.0 to 3.0 times the Vickers hardness of the base portion 7 . If the ratio of the Vickers hardness of the blade portion 6 to the Vickers hardness of the base portion 7 becomes too small, the entire cutting blade 4 tends to be excessively deformed (sticky) when cutting the glass fiber G, and the contact roll 3 in particular is worn. This is because the blade portion 6 does not accurately contact the glass fibers G in such a case, and cutting defects tend to occur. Also, if the ratio of the Vickers hardness of the blade portion 6 to the Vickers hardness of the base portion 7 becomes too large, the difference in thermal expansion coefficient between the base portion 7 and the blade portion 6 may increase, making it difficult to achieve stable bonding. This is because

The joint 8 is formed from a nickel alloy layer or a cobalt alloy layer. In particular, the nickel alloy layer has a thermal expansion coefficient (40 to 47×10 ⁻⁷ /° C. in a temperature range of 30 to 300° C.) that is close to that of cemented carbide, so residual stress is generated in the joint 8. There is an advantage that deformation of the joint portion 8 can be suppressed.

As shown in FIG. 4 , the joint 8 has a dendrite layer 9 in a cross section orthogonal to the longitudinal direction X of the cutting blade 4 (hereinafter simply referred to as “orthogonal cross section of the joint 8”). The orthogonal cross section of the joint 8 is a cross section along the Y direction, such as the AA cross section in FIG. The dendrite layer 9 is a layer containing dendrites (dendritic crystals) D. As shown in FIG. The dendrite D is, for example, Ni—Co precipitates, and is presumed to be precipitated by the diffusion of the component (eg, Co) of the blade portion 6 into the joint portion 8 (eg, Ni).

In this embodiment, the dendrite layer 9 is formed in a region of the joint portion 8 including the vicinity of the interface portion 8 a with the blade portion 6 . The dendrite layer 9 is preferably formed uniformly over the entire thickness direction Z of the cutting blade 4 . The dendrite D contained in the dendrite layer 9 spreads in a dendritic manner from the interface 8a with the blade 6 into the joint 8, so that the adhesion between the joint 8 and the blade 6 is improved by the anchor effect. The dendrite layer 9 may be formed in a region of the joint portion 8 including the vicinity of the interface portion 8b with the base portion 7 . In this case, the adhesion between the joint portion 8 and the base portion 7 is improved due to the anchor effect. Therefore, from the viewpoint of improving the bonding strength of the joint portion 8, the dendrite layer 9 is a region (joint portion 8 is preferably formed over the entire Y-direction of the . The thickness of the dentrite layer 9 in the longitudinal direction X of the cutting blade 4 need not be constant. For example, as will be described later, the layer thickness T1 of the dendrite layer 9 included at one end portion 8c in the longitudinal direction X of the joint portion 8 is equal to the layer thickness T1 of the dendrite layer 9 included at the other end portion 8d in the longitudinal direction X of the joint portion 8. It may be different from T2 (see FIG. 6).

Although illustration is omitted, a diffusion layer is formed on the base end 6 b side of the blade portion 6 by diffusing the component (for example, Ni) of the joint portion 8 into the blade portion 6 .

As shown in FIG. 5, in an orthogonal cross-section of the joint 8, the joint 8 may contain voids (shown in black in FIG. 5) V. As shown in FIG. However, in any orthogonal cross-section of the joint 8, the number of voids V having an equivalent circle diameter of 50 μm or more is 2 or less per 1 mm ² . The number of voids V having an equivalent circle diameter of 50 μm or more is preferably 1 or less per 1 mm ² , more preferably 0. As a result, it is possible to reliably prevent cracks from occurring in the joint portion 8 starting from the void V. As shown in FIG. For the arbitrary orthogonal cross section, one central portion in the longitudinal direction X may be randomly selected, or one central portion in the longitudinal direction X, one end portion 8c, and one end portion 8d may be randomly selected. You may

The number of voids V contained in the dendrite layer 9 is preferably 10 or less in any orthogonal cross section of the junction 8 .

In any orthogonal cross section of the joint 8, the number of voids V having an equivalent circle diameter of 20 μm or more is preferably 4 or less per 1 mm ² , more preferably 2 or less, and more preferably 0. .

At the interface portion 8a with the blade portion 6 in an arbitrary orthogonal cross section of the joint portion 8, the number of voids V having an equivalent circle diameter of 10 μm or more is preferably 3 or less per 0.1 mm ² , and preferably 2 or less. More preferably, the number is 0. The number of voids V having an equivalent circle diameter of 10 μm or more is the number of voids V included in an area of 0.1 mm ² including the interface portion 8a.

The number of voids V with an equivalent circle diameter of 50 μm or more included in the orthogonal cross section of one end 8c of the joint 8 in the longitudinal direction X is the equivalent circle diameter included in the orthogonal cross section of the other end 8d in the longitudinal direction X of the joint 8. It may be larger than the number of voids V of 50 μm or more. In this case, as shown in FIG. 6, the layer thickness (Y-direction dimension) T1 of the dendrite layer 9 included in one end portion 8c in the longitudinal direction X of the joint portion 8 is equal to the other end portion in the longitudinal direction X of the joint portion 8. As shown in FIG. It is preferably larger than the layer thickness T2 of the dendrite layer 9 included in 8d. As a result, even if the number of voids V is relatively large at one end portion 8c of the joint portion 8, the layer thickness of the dendrite layer 9 is increased at the portion 8c, so that the joint portion 8 is kept in a state in which cracks are less likely to occur. be. FIG. 6 is a cross section of the joint 8 along the longitudinal direction X, and schematically shows the formation range of the dendrite layer 9 (the cross-hatched portion). The layer thicknesses T1 and T2 of the dendrite layer 9 may be measured, for example, in an orthogonal cross section of the joint 8 where the number of voids V is measured. When the layer thickness of the dendrite layer 9 varies within the orthogonal cross section of the joint portion 8, the layer thicknesses T1 and T2 are defined, for example, by the maximum thickness of the dendrite layer 9 included in the cross section.

In addition, when the layer thickness of the dendrite layer 9 changes in the longitudinal direction X, although illustration is omitted, diffusion included in one end portion in the longitudinal direction X of the blade portion 6 (the end portion on the one end portion 8c side of the joint portion 8) The layer thickness of the layer (the layer in which the component of the bonding portion 8 is diffused into the blade portion 6) is also the diffusion layer included in the other end portion of the blade portion 6 in the longitudinal direction X (the end portion on the side of the other end portion 8d of the bonding portion). can be greater than the layer thickness of

Next, a method for manufacturing the cutting blade 4 configured as described above will be described.

As shown in FIG. 7, this manufacturing method includes a blade portion preparation step S1 for preparing the blade portion 6, a base portion preparation step S2 for preparing the base portion 7, and a joint between the blade portion 6 and the base portion 7. A bonding preparation step S3 for arranging the material 11, a bonding step S4 for bonding the blade portion 6 and the base portion 7 using the bonding material 11, and a blade for polishing the tip 6a of the blade portion 6 bonded to the base portion 7 and a attaching step S5.

In the blade portion preparation step S1, the blade portion 6 is made of tungsten carbide (WC) powder having an average particle size of 0.3 to 1.0 μm and containing 85 to 95% by mass and cobalt (Co) powder containing 5 to 15% by mass. are blended and sintered to prepare a cemented carbide molded into a predetermined shape (for example, the dimension from the base end 6b to the tip 6a of the blade portion 6 is 3 to 7 mm).

In the base portion preparation step S2, as the base portion 7, iron (Fe) containing 0.8 to 1.3% by mass of carbon (C) is quenched and tempered to obtain a predetermined size and shape (for example, the base portion 7 A carbon tool steel is prepared which has a dimension of 12 to 20 mm from the proximal end 7b to the distal end 7a.

As shown in FIG. 8, in the bonding preparation step S3, the base portion 7 is arranged so that the bonding material 11 is sandwiched from both sides by the front end 7a of the base portion 7 and the base end 6b of the blade portion 6, which are aligned in the longitudinal direction X with each other. , the blade portion 6 and the bonding material 11 are arranged. The bonding material 11 is, for example, nickel foil or cobalt foil having a thickness of 0.2 to 0.5 mm.

As shown in FIG. 9, in the bonding step S4, the bonding material 11 is heated by irradiation with the fiber laser L. As shown in FIG. As a result, the bonding material 11 and its vicinity are locally heated, and a bonding portion 8 that bonds the blade portion 6 and the base portion 7 is formed. The joint portion 8 is formed of a nickel alloy layer or a cobalt alloy layer. The alloy layer is formed by dissolving nickel or cobalt with iron, which is the main component of the carbon tool steel, and by melting into the cemented carbide. The fiber laser L is a type of solid-state laser that uses an optical fiber as an amplification medium.

If the fiber laser L is used in the joining step S4 in this way, the dendrite layer 9 is formed in the joining portion 8 and the number of voids V in the joining portion 8 is greatly reduced as described above. Therefore, cracks originating from the void V are less likely to occur in the joint portion 8 .

The wavelength of the fiber laser L is, for example, 1.06 μm. The laser output of the fiber laser L is preferably 500-1000W, more preferably 600-800W. The spot diameter of the fiber laser L is preferably 50-300 μm, more preferably 100-200 μm.

As shown in FIG. 10, the fiber laser L scans along the longitudinal direction X from one end portion 11c side of the bonding material 11 toward the other end portion 11d side. The scanning speed of the fiber laser L may be constant in the longitudinal direction X of the bonding material 11, or may vary.

When changing the scanning speed of the fiber laser L, the scanning speed R1 of the fiber laser L at one end (welding start side end) 11c of the bonding material 11 is changed to the other end (welding end side end) 11d of the bonding material 11. It is preferable that the scanning speed R2 of the fiber laser L be slower than the scanning speed R2 in the other portions including. The scanning speed R2 is, for example, 1.2 to 2.0 times the scanning speed R1. By doing so, the amount of heat supplied from the fiber laser L to the one end portion 11c of the bonding material 11 becomes relatively large. Therefore, the amount of heat supplied to the one end portion 11c of the bonding material 11 melts the one end portion 11c of the bonding material 11 and preheats other portions including the other end portion 11d of the bonding material 11 . Therefore, since other portions including the other end portion 11d of the bonding material 11 are easily melted in advance with a small amount of heat, the bonding material 11 is sufficiently melted even if the scanning speed R2 of the fiber laser L is relatively increased. It has the advantage of being able to

In this case, the number of voids V with an equivalent circle diameter of 50 μm or more included in the orthogonal cross section of the one end portion 8c of the joint portion 8 is equal to the number of voids V with an equivalent circle diameter of 50 μm or more included in the orthogonal cross section of the other end portion 8d of the joint portion 8. tend to be larger than the number of On the other hand, the layer thickness T1 of the dendrite layer 9 included in the one end portion 8c of the joint portion 8 tends to be larger than the layer thickness T2 of the dendrite layer 9 included in the other end portion 8d of the joint portion 8 . Therefore, in a portion where the number of voids V increases, the thickness of the dendrite layer 9 increases and the bonding strength is increased, so that the state in which cracks are unlikely to occur in the bonding portion 8 is maintained.

In the sharpening step S5, the tip 6a of the blade portion 6 is ground to form a sharp cutting edge. As a result, the cutting blade 4 including the blade portion 6, the base portion 7, and the joint portion 8 that joins the blade portion 6 and the base portion 7 is manufactured. In the sharpening step S5, if necessary, surplus portions of the joint portion 8 projecting outward from both main surfaces of the cutting blade 4 may be removed by grinding.

The present invention is not limited to the configurations of the above-described embodiments, nor is it limited to the above-described effects. Various modifications can be made to the present invention without departing from the gist of the present invention.

In the above embodiment, the method for producing glass fibers may include the following steps. The method for producing glass fibers includes a spinning step in which molten glass is drawn out from a number of nozzles formed at the bottom of the bushing and spun out as continuous thin glass filaments, a cooling step in which the glass filaments are cooled with a water spray, and a bundle A process of coating an agent on the surface of a glass film and collecting several hundred to several thousand to form glass strands; a winding process of winding the glass strands with a winder; and cutting to a predetermined length to form glass chopped strands. In the cutting process, the cutting device 1 (cutting blade 4) described above is used.

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

(1) Blade As the blade, a cemented carbide was prepared by blending tungsten carbide (WC) powder and cobalt (Co) powder and sintering them to form a predetermined size and shape.
(2) Substrate As the substrate, carbon tool steel was prepared by quenching and tempering iron (Fe) containing carbon (C) so as to have a predetermined size and shape.
(3) Joining material (joint part)
A nickel foil (thickness: 0.35 mm) was prepared as a bonding material.

In a comparative example, a cutting blade was manufactured by heating the bonding material using a CO ₂ laser to bond the blade portion and the base portion. On the other hand, in Examples 1 and 2, the cutting blade was manufactured by heating the bonding material using a fiber laser to bond the blade portion and the base portion. Then, the orthogonal cross section of the joint portion of each cutting blade was observed with an electron microscope, and the presence or absence of the dendrite layer and the number of voids in the orthogonal cross section of the joint portion were observed. Table 1 shows the results.

From Table 1 above, it can be confirmed that the number of voids of various sizes in the orthogonal cross section of the joint portion is large in the cutting blade according to the comparative example joined using the CO ₂ laser, without forming a dendritic layer. . On the other hand, from Table 1 above, the cutting blades according to Examples 1 and 2, which were joined using a fiber laser, formed a dendritic layer, and the number of voids of various sizes in the orthogonal cross section of the joint was very large. It can be confirmed that the In particular, in Example 2 in which the laser output of the fiber laser was 800 W, good results were obtained in which the dendrite layer was densely formed and the number of voids of various sizes was zero. Then, with the cutting blade according to the comparative example, cracks originating from voids occurred in the joint due to long-term use (for example, 200 hours). No cracks originating from voids occurred at the joints.

1 cutting device 2 cutting roll 3 contact roll 4 cutting blade 5 rubber layer 6 blade portion 7 base portion 8 joining portion 9 dendrite layer 11 joining material V void (cavity defect)
D Dendrite (dendritic crystal)
G Glass fiber L Fiber laser S Chopped strand S1 Blade part preparation process S2 Base part preparation process S3 Bonding preparation process S4 Bonding process S5 Cutting process

Claims (10)

A cutting blade comprising a blade portion containing cemented carbide, a base portion containing carbon tool steel, and a joint portion joining the blade portion and the base portion and containing nickel or cobalt,
the junction has a dendrite layer,
A cutting blade, wherein the number of voids having an equivalent circle diameter of 50 μm or more is 2 or less per 1 mm ² in any cross section of the joint portion perpendicular to the longitudinal direction of the cutting blade. The cutting blade according to claim 1, wherein the dendrite layer is formed over the entire thickness direction of the cutting blade. 3. The cutting blade according to claim 1, wherein the dendrite layer contains 10 or less voids in the orthogonal cross section of the joint. The cutting blade according to any one of claims 1 to 3, wherein voids having an equivalent circle diameter of 20 µm or more are 4 or less per 1 mm ² in the orthogonal cross section of the joint. 5. Any one of claims 1 to 4, wherein voids having an equivalent circle diameter of 10 μm or more are 3 or less per 0.1 mm ² at the interface between the joint portion and the blade portion in the orthogonal cross section of the joint portion. The cutting blade described in . The number of voids having an equivalent circle diameter of 50 μm or more included in the orthogonal cross section of the joint at one end in the longitudinal direction of the cutting blade is equal to or greater than the number of voids in the orthogonal cross section of the joint at the other end in the longitudinal direction of the cutting blade. more than the number of voids with an equivalent circle diameter of 50 μm or more,
The thickness of the dendrite layer included in the joint portion at one end portion in the longitudinal direction of the cutting blade is greater than the layer thickness of the dendrite layer included in the joint portion at the other end portion in the longitudinal direction of the cutting blade. The cutting blade according to any one of claims 1-5. A glass fiber cutting device comprising the cutting blade according to any one of claims 1 to 6, wherein the cutting blade cuts the glass fiber into a predetermined length. A method for producing glass fibers, comprising a cutting step of cutting glass fibers into a predetermined length with the cutting blade according to any one of claims 1 to 6. A bonding preparation step of disposing a bonding material containing nickel or cobalt between a blade portion containing cemented carbide and a base portion containing carbon tool steel;
A method for manufacturing a cutting blade, further comprising, after the bonding preparation step, a bonding step of heating the bonding material by irradiating a fiber laser to bond the blade portion and the base portion. In the joining step, a fiber laser is scanned from one end side of the joining material toward the other end side along the longitudinal direction of the cutting blade,
10. The method of manufacturing a cutting blade according to claim 9, wherein the scanning speed of the fiber laser at one end portion of the bonding material is made slower than the scanning speed of the fiber laser at other portions including the other end portion of the bonding material.

Images