JP2008208991A - Transmission belt and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission belt hard to be broken and easy to be manufactured, and to provide a manufacturing method thereof. <P>SOLUTION: This transmission belt comprises an annular metal cord C1 as a tensile-resistant body and a cover part covering the annular metal cord C1. The annular metal cord C1 has an annular core part 3 formed by forming one part of a first metal strand 31 into a predetermined annular diameter of loop, spirally winding the residual length of the first metal strand 31 along the loop several times and connecting a starting end 31a and a terminal end 31b of the first metal strand 31 to each other, and an outer layer part 4 formed by spirally winding one strand material 1, which is formed by twisting several second strands 11, around the annular core part 3 so as to cover the peripheral surface of the annular core part 3 and connecting a winding starting end 1a and a winding terminal end 1b of the strand material 1 to each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission belt and a manufacturing method thereof.

Conventionally, as a kind of transmission belt, for example, as described in Patent Document 1, a belt using a metal cord as a core material is known. The metal cord serving as a core material includes at least one filament serving as a central core and a plurality of filaments surrounding the central core.
Further, as described in Patent Document 2, a transmission belt using a twisted cord as a core material is also known. In this transmission belt, the ends of the pair of twisted cords are once untwisted and joined, and then twisted again after the joining as a core material.
JP-A-4-307146 JP 2000-213601 A

  In the power transmission belt described in Patent Document 1, it is necessary to work by joining both ends of the metal cord into an annular shape. When joining both ends of the metal cord, the method of joining twisted cords described in Patent Document 2 can be applied to the metal cord. However, when the joining method described in Patent Document 2 is applied, filament untwisting work, joining work, and twisting work occur. For this reason, the process for coupling becomes complicated, and it becomes difficult to manufacture the transmission belt. Further, when the ends of the filament are twisted again, the twisted state differs between the bonded portion and the other portion, which may reduce the mechanical strength of the bonded portion. When the mechanical strength of the joint portion is reduced, the metal cord is broken, and as a result, the transmission belt is easily broken.

  As a method of joining both ends of the metal cord, a method of joining both ends of the metal cord together is also conceivable. However, in this method, since the coupling portion is concentrated at one place in the circumferential direction, the metal cord is easily broken completely.

  Accordingly, an object of the present invention is to provide a transmission belt that is less likely to break and that is easy to manufacture and a method for manufacturing the same.

  A transmission belt according to the present invention capable of solving the above-described problems includes an annular metal cord serving as a tensile body and a covering portion covering the annular metal cord, and the annular metal cord is formed of the first metal strand. A part of the loop is a loop having a predetermined annular diameter, and the extra length of the first metal strand is spirally wound around the loop, and the start end and the end of the first metal strand are An annular core portion formed by joining together and a single strand material formed by twisting a plurality of second metal strands are spirally wound around the annular core portion so that the annular core portion The outer layer part is covered, The outer layer part formed by combining the winding start end part and winding end part of the said strand material, It is characterized by the above-mentioned.

As described above, in the annular metal cord serving as the tensile body, the annular core portion forms a loop with a part of the first metal strand, and the remaining length of the first metal strand is spiral after the loop. The first end of the first metal element wire and the end of the first metal strand are joined together. For this reason, the connecting portion of the annular core portion is only the first end portion and the terminal end portion of the first metal strand, and compared with the case where the strand materials are combined together at one location in the circumferential direction, The cross-sectional area of the portion) is reduced, and the strength of the annular core portion can be improved.
Further, since the outer layer portion is not wound with a plurality of strand materials around the annular core portion, the strand material is wound continuously over a plurality of circumferences, so that only one strand material is required. As compared with the case where a plurality of cords are used, the number of joints is reduced, so that the reduction in the breaking strength of the annular metal cord can be suppressed and the manufacturing can be facilitated. Further, if the strand material of the outer layer portion is wound at a predetermined winding angle, an annular metal cord having a substantially uniform surface state can be obtained without the strand material being disturbed. Since such an annular metal cord is uniformly applied while avoiding the concentration of external force on a specific portion, it is possible to suppress a decrease in breaking strength.
Thus, according to the present invention, it is possible to obtain an annular metal cord that is easy to manufacture and excellent in breaking strength. Therefore, the transmission belt in which such an annular metal cord is covered with the covering portion is also difficult to break and easy to manufacture.

In the power transmission belt according to the present invention, the number of times that the first metal strand is spirally wound around the loop of the first metal strand is not less than 3 times and not more than 30 times per round. It is preferable.
Assuming that the metal strands are aligned in parallel as the annular core portion, the metal strands are easy to move freely, lack a sense of unity, and do not easily become a uniform load with respect to external force. Therefore, by winding the first metal wire around the loop 3 times / round or more, it becomes a stable and integrated structure that is less prone to movement and displacement, so that the load acts uniformly on the external force. Thus, the breaking strength can be increased. In addition, by limiting the winding to 30 times / circumference or less, it is possible to make it difficult to stretch against an external force when the ring metal cord is formed.

In the transmission belt according to the present invention, the number of turns in which the first metal element wire is spirally wound around the loop of the first metal element wire is 2 or more and 6 or less. preferable.
Thus, when the outer layer portion is formed by wrapping with the strand material using the second metal strand on the annular core portion formed of the first metal strand, The same rigidity and cross-sectional area can be secured.

In the power transmission belt according to the present invention, the position of the annular metal cord in the annular direction differs between the joined portion of the first metal strand and the joined portion of the strand material using the second metal strand. It is preferable.
In this way, by shifting the position of the coupling portion from each other, simultaneous fracture of the annular core portion and the outer layer portion is less likely to occur. Therefore, it is possible to suppress a decrease in breaking strength in the annular metal cord, and it is also possible to suppress a decrease in breaking strength for the transmission belt.

In the transmission belt according to the present invention, both end portions of the first metal strand are joined by welding, and both end portions of the strand material are joined by welding and covered by a coil spring-like sleeve. It is preferably reinforced.
As a result, the ends of the first metal strands can be easily connected to each other, the ends of the strand material can be easily connected to each other, and the connecting portion of the strand material that is the outer layer portion is protected and reinforced by the coil spring-like sleeve. can do. In addition, since the coil spring-like sleeve has good flexibility, it is flexibly deformed in accordance with the curved shape of the spirally wound strand material, and maintains a tight contact state with the joined portion, and the strand material in the joined portion is maintained. The connecting member does not hinder the deformation. That is, the mechanical properties of the annular metal cord can be made substantially uniform over the entire circumference, and the joined portion of the strand material can be made more difficult to break. Accordingly, the transmission belt can be easily manufactured, the mechanical characteristics can be made uniform, and it is difficult to break.

In the power transmission belt according to the present invention, it is preferable that both ends of the strand material are coated with an adhesive at a location where they are joined by welding.
Thereby, while being able to suppress a motion of a joint part, even if a metal strand is cut in a part, it can prevent that an outer layer part is scattered.

In the transmission belt according to the present invention, the material of the first metal strand is C: 0.08 to 0.27 mass%, Si: 0.30 to 2.00 mass%, Mn: 0.50 to 2 0.000% by mass, Cr: 0.20 to 2.00% by mass, and Al, Nb, Ti, and V in the range of 0.001 to 0.10% by mass, respectively, and the balance Is preferably an alloy steel composed of Fe and impurities inevitably mixed.
Thereby, a 1st metal strand becomes the thing excellent in weldability. As a result, it becomes easier to manufacture the annular metal cord and the transmission belt, and the breaking strength is also increased.

In the transmission belt according to the present invention, it is preferable that a wire diameter of the first metal strand is 0.10 mm or more and 0.40 mm or less.
For example, when an annular core is formed using a strand material, the joint portion is welded to the entire surface of the annular core, so that the strength is significantly reduced. Therefore, in order to avoid this, the annular core portion is formed of one metal strand, so welding for one strand is performed on the annular core.
In general, when the wire diameter is increased, a greater tensile stress or compressive stress tends to act on the welded joint, particularly on the outer side away from the center. Unlike the outer layer portion, the connecting portion of the first metal element wire at the start end portion and the end end portion is located at the center of the annular metal cord, so that bending stress is reduced, and even if the wire diameter is large, there is no particular inconvenience.

In the transmission belt according to the present invention, it is preferable that a wire diameter of the second metal element wire is 0.06 mm or more and 0.30 mm or less.
Thereby, moderate rigidity can be given to a strand material and a strand material can have favorable fatigue resistance. As a result, the annular metal cord and the transmission belt can be made more durable.

In the transmission belt according to the present invention, it is preferable that the twist direction of the second metal element wire in the strand material and the winding direction of the strand material around the annular core portion are opposite.
Thereby, after winding of a strand material, the cyclic | annular metal cord with few unevenness | corrugations in the surface appearance can be obtained. Also, the annular metal cord can be made difficult to twist. By using such an annular metal cord, the transmission belt is more difficult to break.

In the transmission belt according to the present invention, it is preferable that the winding angle of the strand material with respect to the central axis of the annular core portion is 4.5 degrees or more and 13.8 degrees or less.
As a result, the winding work of the strand material is facilitated, so that the transmission belt can be more easily manufactured by extending the annular metal cord. Moreover, the cyclic | annular metal cord which has moderate elongation and there is no winding looseness of a strand material can be obtained. Thereby, the breaking strength of the transmission belt can be further improved.

In the transmission belt according to the present invention, it is preferable that the strand material is wound not less than 6 laps and not more than 8 laps along the outer peripheral surface of the annular core portion.
Thereby, since an outer layer part will cover a cyclic | annular core part closely, a cyclic | annular metal cord can be made into the thing of the state stabilized geometrically. Therefore, it is possible to reliably obtain an annular metal cord that is excellent in breaking strength and hardly deforms in the radial direction. As a result, the power transmission belt is also excellent in breaking strength and fatigue resistance and hardly deforms.

In the power transmission belt according to the present invention, it is preferable that the annular core portion and the outer layer portion are subjected to a low temperature annealing treatment.
Thereby, the internal distortion of a metal strand can be removed. Therefore, the annular metal cord and thus the transmission belt can be made more difficult to break.

In the annealing, it is preferable that the outer layer portion is spirally shaped with respect to the annular core portion.
As a result, the strength utilization factor of the annular metal cord can be improved, it is not necessary to expect an excessive safety factor of the transmission belt, and the strength can be secured even if the diameters of the annular core portion and the outer layer portion are reduced. It is possible to reduce the weight.

  Moreover, the manufacturing method of the power transmission belt according to the present invention that can solve the above-described problem includes an annular metal cord that serves as a strength member, and a covering portion that covers the annular metal cord, and the annular metal cord is annular. A transmission belt manufacturing method comprising: a formed annular core portion; and an outer layer portion that is wound around the annular core portion in a plurality of spirals and covers an outer peripheral surface of the annular core portion, wherein the first metal A part of the strand is formed into a loop with a predetermined annular diameter, and the extra length of the first metal strand is continuously wound around the loop in a plurality of turns, and the start end of the first metal strand And a terminal portion are joined together to form an annular core portion, and a single strand material formed by twisting a plurality of second metal strands is spirally wound around the annular core portion in a plurality of turns. Cover the outer peripheral surface of the annular core, To form the outer layer portion by coupling the terminal end winding start end winding of the serial strand material, and forming the annular metal cord.

As described above, the annular metal cord serving as the strength member has a ring-shaped core portion that forms a loop with a part of the first metal strand, and the remaining length of the first metal strand is spirally formed following the loop. A plurality of windings are wound around each other, and the first end of the first metal strand and the end are joined together. For this reason, the connecting portion of the annular core portion is only the first end portion and the terminal end portion of the first metal strand, and compared with the case where the strand materials are combined together at one location in the circumferential direction, The cross-sectional area of the portion) is reduced, and the strength of the annular core portion can be improved.
In addition, the outer layer portion does not wind a plurality of strand materials around the annular core portion, but continuously wraps the strand material over a plurality of circumferences. Therefore, only one strand material is required, and thus a plurality of strand materials are required. Since the number of joints is smaller than that in the case of using, it is possible to suppress the decrease in the breaking strength of the annular metal cord and to facilitate the production. Further, if the strand material of the outer layer portion is wound at a predetermined winding angle, an annular metal cord having a substantially uniform surface state can be obtained without the strand material being disturbed. Since such an annular metal cord is uniformly applied while avoiding the concentration of external force on a specific portion, it is possible to suppress a decrease in breaking strength.
Thus, according to the present invention, it is possible to manufacture an annular metal cord that is easy to manufacture and excellent in breaking strength. Therefore, the transmission belt in which such an annular metal cord is covered with the covering portion is also difficult to break and easy to manufacture.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in breaking strength and fatigue resistance, and can provide the transmission belt which is easy to manufacture, and its manufacturing method. Therefore, if the transmission belt of the present invention is used in an industrial machine, the industrial machine can be made excellent in durability.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  FIG. 1 is a cross-sectional perspective view of a transmission belt according to the present embodiment. The transmission belt B1 according to the present embodiment is a general industrial V-belt. The transmission belt B <b> 1 includes an annular metal cord C <b> 1 that is a strength member and a covering portion 70. The covering portion 70 covers the annular metal cord C1, and a cloth layer 72 is provided on the upper and lower surfaces of the covering portion 70. The covering portion 70 includes a material such as rubber.

  The transmission belt B1 has five annular metal cords C1. 2 is a perspective view of the annular metal cord C1, and FIG. 3 is a radial sectional perspective view showing the annular metal cord C1. FIG. 4 is a perspective view showing a state when the annular core portion 3 is formed from the first metal strand 31. Fig.5 (a) is a perspective view which shows a mode that the strand material 1 was wound 1 round around the cyclic | annular core part 3 with which the cyclic | annular metal cord C1 is provided, The same figure (b) is the A section enlarged view. FIG. 6A is a radial sectional view showing the annular metal cord C1, and FIG. 6B is a side view of the annular metal cord C1. FIG. 7 is an enlarged perspective view showing a part of the annular metal cord C1.

  As shown in FIGS. 2 and 3, the annular metal cord C <b> 1 includes an annular core portion 3 and an outer layer portion 4 that covers the outer peripheral surface of the annular core portion 3.

As shown in FIG. 4, the annular core portion 3 forms a loop with a predetermined annular diameter necessary as an annular core portion by a part of the first metal strand 31, and continues to the loop. After the extra length of one metal strand 31 is spirally wound over a plurality of circumferences, the start end portion 31a and the end end portion 31b of the first metal strand 31 are joined by welding as shown in FIG. It is formed by doing.
For example, when the annular core portion 3 is formed by bonding a strand material in which a plurality of metal strands are previously twisted together, the bonded portion is welded to the entire surface of the strand material, so that the strength is significantly reduced. Therefore, in this embodiment, in order to avoid this strength reduction, a single strand of metal 31 is used to form a loop as described above, and the excess length is continuously wound to obtain a stranded wire structure equivalent to that of the strand material. However, the first metal wires 31 are joined by welding for one wire.

  As shown in FIG. 6, the outer layer portion 4 around the annular core portion 3 is made of a strand material 1 formed by twisting a plurality of second metal strands 11 (seven in this embodiment), and the annular core portion 3. It is formed by covering the outer peripheral surface.

It is preferable that the first metal strand 31 itself is continuously spirally wound around the loop of the first metal strand 31 so that the number of turns per turn is 3 to 30 times.
When the first metal strands 31 are arranged in parallel as an annular core portion, the number of times of winding is such that the sense of unity between the first metal strands 31 is poor, and it becomes easy to move freely or external force. This is to prevent a uniform load from occurring. Therefore, in order to avoid such an inconvenience, it is necessary to wind at least 3 times / turn. In addition, if the number of turns exceeds 30 turns / circulation, the wound first metal strand 31 is likely to extend in the circumferential direction of the annular core portion 3, so that it is difficult to ensure a uniform load when the annular metal cord C1 is formed. It becomes.

In addition, in the case of the present embodiment, the number of turns that the first metal wire 31 itself continuously spirals around the loop of the first metal wire 31 is six. In addition, it is preferable that the frequency | count wound around a loop is 2 to 6 rounds. The reason for winding at such a frequency is to ensure the rigidity and cross-sectional shape of the annular core portion 3 as a core when the strand material 1 constituting the outer layer portion 4 is wound to form the outer layer portion 4.
In the present embodiment, the direction in which the first metal strand 31 itself continues to be spirally wound around the loop of the first metal strand 31 is the S twist direction.

  The material of the 1st metal strand 31 is C: 0.08-0.27 mass%, Si: 0.30-2.00 mass%, Mn: 0.50-2.00 mass%, Cr: 0 .20 to 2.00% by mass, and Al, Nb, Ti, and V are each contained in the range of 0.001 to 0.10% by mass, the balance being Fe and unavoidable Use alloy steel consisting of mixed impurities. Thereby, the 1st metal strand 31 becomes the thing excellent in weldability. As a result, it becomes easier to manufacture the annular core portion 3, and thus the annular metal cord C1, and further the transmission belt, and the breaking strength is further improved.

Moreover, the wire diameter of the 1st metal strand 31 is 0.10 mm or more and 0.40 mm or less.
As described above, the annular core portion 3 is formed using one first metal strand 31, and welding for one first metal strand 31 is performed. In the welding for one metal strand, since the cross-sectional area of the welding is small, the wire diameter of the first metal strand 31 is required to be relatively thick. In the present embodiment, the first metal The wire 31 has a wire diameter that is larger than the wire diameter of the second metal strand 11 and is not less than 0.10 mm and not more than 0.40 mm.
On the other hand, generally, when the wire diameter is increased, there is a tendency that a larger tensile stress or compressive stress acts on the outer side of the element wire that is away from the center in the radial direction. However, the connecting portion between the start end portion 31a and the end end portion 31b of the first metal strand 31 is located near the center of the annular metal cord C1 unlike the outer layer portion 4, so that the bending stress is reduced. For this reason, the first metal element wire 31 is not particularly disadvantageous even if the wire diameter is large.

  The outer layer portion 4 is formed of a strand material 1 made of a second metal strand 11 different from the first metal strand 31 that forms the annular core portion 3. The strand material 1 constituting the outer layer portion 4 is wound around the annular core portion 3 over a plurality of circumferences, and is wound spirally as shown in FIGS. 3 and 5. The strand material 1 is wound so as not to be twisted. By winding without twisting, loosening of the strand material 1 can be suppressed.

  The strand material 1 constituting the outer layer portion 4 is obtained by twisting a plurality of second metal strands 11 together. In this embodiment, as shown in FIGS. 3 and 6A, the strand material 1 is centered on one second metal strand 11, and on the outer peripheral surface of the second metal strand 11. Six second metal strands 11 are wound around an S twist. Thus, since the strand material 1 is a geometrically stable seven-strand, the shape does not collapse in the process of use, and is strong and not easily broken.

  The 2nd metal strand 11 consists of a high carbon steel wire containing 0.7 mass% or more of carbon (C), for example. By selecting a material containing 0.70% by mass or more of C, the second metal element wire 11 can be made a steel wire having more excellent breaking strength. Further, the surface of the second metal element wire 11 may be subjected to a copper alloy (for example, brass) or zinc plating treatment. In addition, the material of the 2nd metal strand 11 is not restricted to the above-mentioned thing, For example, you may consist of the material of the same quality as the 1st metal strand 31. FIG.

  Moreover, the wire diameter of the 2nd metal strand for strands of this invention is 0.06 mm or more and 0.30 mm or less. Thus, in this invention, since the diameter of a 2nd metal strand is 0.06 mm or more, the rigidity of the strand material 1 can be maintained at the minimum, and the outer layer part 4 shall endure a deformation | transformation. be able to. Moreover, since the diameter of a 2nd metal strand is 0.30 mm or less, the rigidity of the strand material 1 which comprises the outer layer part 4 does not need to become large too much. Therefore, the annular metal cord C1 can be less likely to cause fatigue fracture due to the feeding stress.

  That is, when the strand material 1 is formed of the second metal strand 11 having such a diameter, the strand material 1 having appropriate rigidity can be obtained. Therefore, it becomes easy to wind the outer layer portion 4 (strand material 1) around the annular core portion 3, and the outer layer portion 4 is less likely to be loosened.

  In the present embodiment, the strand material 1 constituting the outer layer portion 4 is wound six times along the outer peripheral surface of the annular core portion 3 as shown in FIG. The number of windings of the strand material 1 constituting the outer layer portion 4 around the annular core portion 3 is preferably 6 or more and 8 or less. As described above, the outer layer portion 4 of the annular metal cord C1 is composed of one continuous strand material 1, but as shown in FIG. 6A, the strand material 1 is annular when viewed in cross section. Six of them are arranged uniformly around the core portion 3. This cross-sectional shape is substantially the same as the cross-sectional shape when six strand materials 1 are twisted around the annular core portion 3. Therefore, the annular metal cord C1 has a geometrically stable structure. For this reason, the annular metal cord C1 is excellent in breaking strength and fatigue resistance and can withstand radial deformation.

  As shown in FIG. 6A, the annular metal cord C1 has a cross-section close-packed twist structure that is advantageous for space saving, and the strand material is formed in the first outer layer portion around one annular core portion 3. In the second outer layer portion, 12 strand materials 1 are arranged, but when the annular core portion 3 and the strand material 1 have the same diameter, depending on the linear tolerance, If the strand material 1 is rotated six times in the outer layer portion of the first layer, it is difficult to arrange the six strands on the cross section, the strand materials 1 may interfere with each other, or the contact with the annular core portion 3 may become uneven. To do. Therefore, when the diameter of the annular core portion 3 is larger than the diameter of the strand material 1, such a problem can be avoided.

  As shown in FIGS. 3 and 5, the strand material 1 constituting the outer layer portion 4 is Z-twisted on the outer peripheral surface of the annular core portion 3, that is, the twist direction of the second metal strand 11 constituting the strand material 1. Is wound in the opposite direction. On the other hand, the annular core portion 3 has a configuration in which the first metal strand 31 is S-twisted, and the strand material 1 has a configuration in which the second metal strand 11 is S-twisted. The twist structure and the Z-winding structure are combined. Therefore, the twisting direction of the first metal strand 31 and the second metal strand 11 and the winding direction of the outer layer portion 4 around the annular core portion 3 are opposite to each other. The code C1 can be obtained.

  Further, the strand material 1 constituting the outer layer portion 4 is wound at a predetermined winding angle with respect to the central axis of the annular core portion 3. For this reason, the strand material 1 is wound without disturbance, and the annular metal cord C1 having a substantially uniform surface state can be obtained. In the present embodiment, as shown in FIG. 6B, the winding angle θ of the strand material 1 with respect to the X direction, that is, the direction in which the central axis of the annular core portion 3 extends is 4.5 degrees or more and 13.8 degrees or less. It has become. When the winding angle θ is set to 4.5 degrees or more, the strand material 1 is hardly loosened. By setting the winding angle θ to 13.8 degrees or less, the elongation of the strand material 1 can be prevented from becoming excessively large. That is, by setting the winding angle θ of the strand material 1 of the outer layer portion 4 wound around the annular core portion 3 to 4.5 degrees or more and 13.8 degrees or less, it has an appropriate elongation and a supple annular metal cord C1. Can be obtained.

  As shown in FIG. 7, the winding start end portion 1 a and the winding end portion 1 b of the strand material 1 constituting the outer layer portion 4 are coupled to each other by welding, and the coupling portion is further connected by a connecting member 7. Covered. Further, the connecting portion of the strand material 1 (the winding start end portion 1a and the winding end portion 1b) and the connecting portion of the first metal element wire 31 (the start end portion 31a and the end portion 31b) are an annular metal cord. The positions of C1 in the annular direction are made different. In this way, by arranging the coupling positions differently, it is possible to avoid the concentration of points that tend to be weak in strength.

  The connecting member 7 is formed of a sleeve having excellent flexibility formed in a coil spring shape, and the connecting member 7 has an outer periphery of a joint portion between the start end 1 a and the end end 1 b which are both ends of the strand material 1. It is fixed with an adhesive so as to cover it. The connecting member 7 formed of a coil spring-like sleeve is flexibly deformed according to the curved shape of the strand material 1 to protect and reinforce the welded portion of the strand material 1.

  Thus, the start end of the strand material 1 on the annular core portion 3 side is obtained by connecting the start end portion 1a and the end end portion 1b of the strand material 1 using the connecting member 7 formed of a coil spring-like sleeve having excellent flexibility. The joint portion between the portion 1a and the end portion 1b of the strand material 1 of the outer layer portion 4 that is inclined with respect to the start end portion 1a can be attached in a state of being well covered according to its shape. Thereby, the coupling | bond part of the start end part 1a and the termination | terminus part 1b of this strand material 1 can be protected favorably. Further, since the connecting member 7 does not hinder the deformation of the strand material 1 at the joint portion, the flexibility of the strand material 1 at the joint portion and other portions can be ensured equally, and the mechanical characteristics of the annular metal cord C1 can be fully achieved. It can be made substantially uniform over the circumference.

  In addition, the connecting portion between the start end portion 1a and the end end portion 1b is disposed on one side on both sides of the circular metal cord C1 except for the inner peripheral side and the outer peripheral side of the circular arc. Thereby, even if the cyclic | annular metal cord C1 deform | transforms in the radial direction, the load which acts on this coupling | bond part can be reduced, and the fracture | rupture in a coupling | bond part can be suppressed.

  As described above, the annular metal cord C1 is formed by winding the connecting member 7 after winding the single strand material 1 constituting the outer layer portion 4 around the outer periphery of the annular core portion 3 composed of the single first metal strand 31. It is formed by joining the start end 1a and the end end 1b of the strand material 1 by using.

Then, the manufacturing method of the cyclic | annular metal cord C1 is demonstrated. FIG. 8 is a perspective view showing an example of a manufacturing apparatus for manufacturing the annular metal cord C1.
The manufacturing apparatus M1 includes a driving unit 40 that rotates the annular core portion 3 in the circumferential direction, and a supply portion 50 of the strand material 1 that supplies the strand material 1 wound around the reel 51 to the winding portion of the annular core portion 3. Have.

The supply unit 50 of the strand material 1 is fixed at a predetermined position.
The driving unit 40 includes two pinch rollers 42a and 42b that are installed on an arcuate holding arm 41 and connected to a drive motor to rotate the annular core portion 3 in the circumferential direction.

  The holding arm 41 is provided with a clamp unit 43 that surrounds the periphery of the annular core portion 3 on the supply side of the strand material 1 positioned in the direction opposite to the rotation direction of the annular core portion 3. The clamp unit 43 is composed of two rollers 43a and 43b, prevents lateral vibration of the annular core portion 3, maintains stable circumferential rotation, positions the winding point of the strand material 1, and is high. Winding property is obtained. In this example, the annular core portion 3 is made vertical so as to suppress lateral vibration and rotate in the circumferential direction.

  The clamp unit 43 composed of the two rollers 43a and 43b prevents the lateral swing of the annular core portion 3, and surrounds the periphery of the annular core portion 3 even with the final finished cord diameter to maintain a stable circumferential rotation. However, as long as it has a function of fixing the winding point as a twisting port of the strand material 1, the groove shape is not particularly limited, and in addition to the U-shaped groove shape, the arc-shaped groove shape and the V-shaped groove shape may be used. Good.

The holding arm 41 is swingably installed on the stand 44 so as to perform a pendulum motion by a swing mechanism 60 including a rotary disk 61 and a crankshaft 62 with the clamp unit 43 as a fulcrum.
The annular core portion 3 held by the holding arm 41 is at one end of the period of the pendulum motion, and as shown by the solid line in FIG. 9, the reel 51 is positioned outside the ring of the annular core portion 3. At the other end of the period of the pendulum motion, as shown by the solid line in FIG. 9, the swing is performed so as to be positioned in the ring of the annular core portion 3.

  In the supply unit 50 of the strand material 1, a pair of front and rear cassette stands 52 are horizontally installed at a distance that does not hinder the pendulum movement of the annular core portion 3 held by the holding arm 41. A reel delivery mechanism is provided at the tip so as to face each other across the surface of the annular core portion 3.

  The supply unit 50 includes a reel 51 around which the strand material 1 is wound, and a cassette 53 having a cylindrical outer peripheral wall having a diameter slightly larger than the outer diameter of the reel 51 and corresponding to at least the inner width of the reel. The reel 51 is rotatably accommodated in a cassette 53 so as to cover the entire winding surface of the strand material 1, and is formed into a so-called cartridge. An unwinding hole is formed in the outer peripheral wall of the cassette 53, and the strand material 1 is drawn from the unwinding hole toward the clamp unit 43 at the winding point of the annular core portion 3. The strand material 1 is wound around a reel 51 with a coil diameter adjusted in advance, and is set in a cassette 53 of the supply unit 50.

  A guide rod to which the cassette 53 can be removably mounted, and a delivery mechanism for transferring the cassette 53 mounted on one guide rod to the other guide rod, respectively, at opposite positions of the front ends of the pair of cassette stands 52. And are installed. In this delivery mechanism, the cassette 53 mounted on one guide rod can be transferred to the other guide rod by moving the rod in and out by an air cylinder and pushing the center of the cassette 53.

  When the manufacturing apparatus M1 having such a configuration is used, the annular metal cord C1 is manufactured through the following steps.

  First, while forming a loop of a predetermined annular diameter required as an annular core portion with a part of the first metal strand 31, the remaining length of the first metal strand 31 is continuously spiraled with respect to this loop. And after winding over multiple circumferences, as shown in FIG. 5, the start end part 31a and the end part 31b of the 1st metal strand 31 are couple | bonded by welding, and the annular core part 3 is formed. Even in the formation of the annular core portion 3, the step of winding the extra length of the first metal strand 31 in a spiral manner is performed in the same manner as the step of winding the strand material 1 using the manufacturing apparatus M1 described below. Can do.

  After forming the annular core portion 3, the winding start end (start end portion 1a) of the strand material 1 is temporarily fixed to the annular core portion 3 using an adhesive tape or the like. After the temporary fixing, the annular core portion 3 is set in the driving unit 40 of the manufacturing apparatus M1, and the annular core portion 3 is rotated in the circumferential direction to start winding the strand material 1 around the annular core portion 3.

  In the case of the Z winding, the reel 51 of the strand material 1 is positioned on the left side with respect to the surface of the annular core portion 3, and the reel 51 indicated by a solid line in FIG. 3 to the position where the reel 51 shown by the solid line in FIG. 10 enters the ring of the annular core part 3 from the state of being located outside the ring of the ring 3 with the clamp unit 43 as a fulcrum. 3, the reel 51 is moved at right angles to the surface of the annular core portion 3 by an air cylinder provided at the tip of the cassette stand 52, and the cassette 53 is transferred to the guide rod of the other cassette stand 52. Then, the winding is performed half a turn. Thereafter, from the state where the reel 51 indicated by the solid line in FIG. 10 is located in the ring of the annular core portion 3, the reel 51 indicated by the solid line in FIG. The annular core part 3 is moved in a pendulum manner until it comes out of the ring of the part 3, and the reel 51 is moved at right angles to the annular core surface together with the cassette 53 by the air cylinder outside the ring of the annular core part 3. And one winding is completed. By repeating such an operation, the strand material 1 serving as the outer layer portion 4 is spirally wound around the outer peripheral surface of the annular core portion 3.

  The reel 51 reciprocates back and forth across the core surface of the annular core portion 3 at a predetermined position, and the annular core portion 3 performs a pendulum motion with the clamp unit 43 serving as a winding point of the strand material 1 as a fulcrum. The distance to the winding point of the material 1 is kept substantially constant, and the strand material 1 drawn from the reel 51 does not loosen during winding, and the strand material 1 is wound around the annular core portion 3 under a constant tension. .

The movement trajectory of the reel 51 around which the strand material 1 is wound and the movement trajectory of the annular core portion 3 that performs the pendulum motion are illustrated in FIG.
That is, the reel 51 is annular from the state shown in FIG. 11A outside the annular core portion 3 to the state where the reel 51 is located in the ring of the annular core portion 3 shown in FIG. The core portion 3 is moved in a pendulum manner, and the reel 51 is transferred to the opposite surface of the annular core portion 3 shown in FIG. 11 (c) at the position shown in FIG. In a state where the reel 51 is present, the annular core portion 3 is moved in a pendulum manner from the position shown in FIG. 11C to the state where the reel 51 is located outside the ring of the annular core portion 3 shown in FIG. The cycle of returning 51 from the opposite surface of the annular core portion 3 to the starting position of the original surface (position (a) in FIG. 11) is repeated. As described above, in the present embodiment, the annular core portion 3 is moved by the pendulum with respect to the reel 51 as shown in (a) → (b) → (c) → (d) → (a) in FIG. As shown in (b) → (c) and (d) → (a) of FIG. 11, the strand 51 is moved at right angles with respect to the core surface of the annular core portion 3, whereby the strand material 1 is removed from the annular core portion 3. It is wound around the periphery in a spiral.

  After the winding of the strand material 1 is finished, the winding end portion 1b of the strand material 1 is inserted into the connecting member 7 (see FIG. 7), the temporary fixing of the start end portion 1a is removed, and the start end portion 1a and the end end portion 1b are welded. Join. Next, an adhesive is applied to the joint portion between the start end portion 1a and the terminal end portion 1b, and the connecting member 7 is slid to a position covering the joint portion. If it does in this way, as FIG. 7 shows, the connection member 7 will be fixed to a coupling | bond part by an adhesive agent, a coupling | bond part will be protected by the connection member 7, and the fracture | rupture in a coupling | bond part will be suppressed.

Here, in the strand material 1, the joint portion is slightly curved in accordance with the annular shape of the annular metal cord C 1, but the connecting member 7 is excellent in flexibility made of a coil spring-like sleeve. It can be easily attached to the coupling part.
Then, as described above, the outer layer portion 4 can be provided around the annular core portion 3 by winding the strand material 1 around the annular core portion 3 and joining the start end portion 1a and the end portion 1b.

After the start end portion 1a and the end portion 1b are joined, the above-described annular core portion 3 and outer layer portion 4 may be subjected to a low temperature annealing treatment. More specifically, heat treatment is performed on the annular core portion 3 and the outer layer portion 4 in a pressure chamber in which argon is introduced in a vacuum or a reduced-pressure atmosphere. The temperature during the heat treatment is 70 ° C to 380 ° C. Thereby, the internal distortion of the 1st metal strand 31 and the 2nd metal strand 11 can be removed, and the cyclic metal cord C1 without a distortion can be obtained. When such an annular metal cord C1 is used for a transmission belt, a transmission belt that rotates without meandering can be obtained. Since the transmission belt rotating without meandering does not wear due to contact with surrounding parts, it can maintain high performance over a long period of time.
In addition, it is good to perform a low temperature annealing process before apply | coating the adhesive agent for adhere | attaching the connection member 7 to the coupling | bond part of the start part 1a and the termination | terminus part 1b.

Further, it is preferable that the outer layer portion 4 is spirally shaped with respect to the annular core portion 3 by a low temperature annealing process.
Preferably, the molding process is performed so that the diameter molding rate of the outer layer portion 4 is 20% or more and 100% or less. Here, the diameter shaping ratio means that the diameter (wire diameter) of the annular metal cord C1 is D, and the wave height (including the self-diameter) that is the helical outer diameter of the molded outer layer portion 4 is H. Molding rate (%) = H / D × 100 ”. Since the shape of the outer layer portion 4 is held in a spiral shape wound around the annular core portion 3 by setting the diameter die attachment ratio to 20% or more, preferably 50% or more, the strength utilization of the annular metal cord C1 is utilized. The rate can be improved. Further, in the range where the diameter mold attachment ratio does not exceed 100%, the strength utilization ratio is improved as the diameter mold attachment ratio is increased.

  By performing the annealing of the die-molding process in the environment reduced in pressure as described above, the surface oxidation of the outer layer portion 4 can be prevented, and the outer layer portion 4 can be shaped in a shape wound around the annular core portion 3. .

  When at least one of the annular core portion 3 and the outer layer portion 4 is brass-plated, the amount of annealing in the mold treatment is a heating temperature of 180 ° C. or higher and 320 ° C. or lower and a heating time of 10 minutes or longer and 120 minutes or shorter. And When there is brass plating, it is preferable to consider the melting point (419.6 ° C.) of zinc contained in the brass, and the annealing temperature of the molding process is suitably 320 ° C. or less.

  In addition, when both the annular core portion 3 and the outer layer portion 4 are not subjected to copper alloy plating treatment such as brass plating or galvanization treatment, the annealing amount of the mold forming treatment is 10 at a heating temperature of 180 ° C. or more and 380 ° C. or less. The heating time is from 1 minute to 120 minutes. When the heating temperature of the molding process exceeds 350 ° C., the strength due to age hardening of the annular core part 3 itself tends to decrease. However, since the molding rate of the annular core part 3 improves as the temperature rises, both these characteristics are The critical heating temperature at which the strength utilization factor that affects the temperature does not decrease is about 380 ° C.

  Thus, the strength utilization factor of the outer layer part 4 can be improved by subjecting the outer layer part 4 to the annular core part 3 in a spiral molding process. This eliminates the need for an excessive safety factor when the annular metal cord C1 is used for the transmission belt B1, and can ensure strength even when the diameters of the annular core portion 3 and the outer layer portion 4 are reduced. Weight reduction can be achieved.

  In addition, since the molding process is performed after the outer layer part 4 is formed, the winding pitch when the strand material 1 that becomes the outer layer part 4 is wound around the annular core part 3 can be set to a desired value, and the winding tension can be stabilized. Therefore, the operation of winding the strand material 1 can be performed smoothly and the manufacturability is good.

As described above, the transmission belt B1 of the present embodiment has the annular metal cord C1 as a strength member. The annular metal cord C1 is composed of an annular core portion 3 formed by one first metal strand 31 and one strand material 1 formed by twisting seven second metal strands 11 together. The outer layer portion 4 is wound around the portion 3 in a spiral manner and covers the outer peripheral surface of the annular core portion 3.
Therefore, in the conventional configuration in which the strand material is the annular core portion, there is a fear that the strength may be lowered because a joint portion of the entire surface welding is formed in a part of the annular core portion in the annular direction. Since the annular core portion 3 is formed of metal strands, only one portion of the first metal strand 31, that is, only the annular core portion 3 is partially welded at one place, and the strength is improved. Can be planned.

  Moreover, in the present embodiment, when forming the outer layer portion 4, a plurality of strand materials 1 are not wound, but the strand material 1 is continuously wound around the annular core portion 3 over 6 laps. 1 only needs to be one. Therefore, compared with the case where a plurality of strand materials 1 are used, since the number of joints is reduced, it is possible to suppress a decrease in the breaking strength of the annular metal cord C1 and to facilitate the manufacture. Moreover, since the strand material 1 of the outer layer part 4 is wound at a predetermined winding angle, the strand material 1 is not disturbed and an annular metal cord C1 having a substantially uniform surface state can be obtained. Since an external force is uniformly applied to such an annular metal cord C1, it is possible to suppress a decrease in breaking strength.

  In addition, the start end portion 1 a and the end end portion 1 b of the strand material 1 are combined using a connection member 7, and the connection portion is protected by the connection member 7. In this case, the joined portion of the strand material 1 is more difficult to break. Further, since the connecting member 7 is formed of a coil spring-like sleeve, it is possible to facilitate the mounting, and therefore, it is easy to connect the start end portion 1a and the end end portion 1b of the strand material 1.

  Moreover, the diameter of the 2nd metal strand 11 which comprises the strand material 1 is 0.06 mm or more and 0.30 mm or less, In this case, the strand material 1 can be given moderate rigidity, It can have good fatigue resistance.

  In addition, the strand material 1 is obtained by twisting the second metal element wire 11 S, and the winding of the strand material 1 serving as the outer layer portion 4 with respect to the annular core portion 3 is a Z winding. In this case, it is possible to obtain an annular metal cord C1 that has less irregularities on the surface appearance, is less likely to twist, and is less likely to loosen the strand material 1 of the outer layer portion 4 with respect to the annular core portion 3.

  Moreover, the winding angle of the strand material 1 with respect to the central axis of the annular core part 3 is 4.5 degrees or more and 13.8 degrees or less. In this case, the winding work of the strand material 1 becomes easy. Moreover, the cyclic | annular metal cord C1 which has moderate elongation and there is no winding looseness of the strand material 1 can be obtained.

  Further, the strand material 1 that becomes the outer layer portion 4 is wound around the outer periphery of the annular core portion 3 over six circumferences. Thereby, since the outer layer part 4 covers the annular core part 3 densely, the annular metal cord C1 can be made geometrically stable. As a result, it is possible to reliably obtain the annular metal cord C1 that has excellent breaking strength and fatigue resistance and can withstand radial deformation.

  Further, the annular core portion 3 and the outer layer portion 4 are subjected to a low temperature annealing treatment. In this case, the internal distortion of the first metal strand 31 and the second metal strand 11 can be removed. By using the first and second metal strands from which the internal strain has been removed, it is possible to reliably obtain the annular metal cord C1 that is more difficult to break.

  As described above, since the annular metal cord C1 that is excellent in breaking strength and fatigue resistance and easy to manufacture is used, the transmission belt B1 is also excellent in breaking strength and fatigue resistance and easy to manufacture. .

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the annular metal cord C1 of the transmission belt B1 of the present embodiment, the strand material 1 is wound six times along the outer peripheral surface of the annular core portion 3 to form the outer layer portion 4. The diameter may be increased to wind 7 or 8 turns.

  Further, in the annular metal cord C1 of the transmission belt B1 of the present embodiment, as shown in FIG. 6A, the outer peripheral surface of the annular core portion 3 is covered with one layer of the strand material 1. Alternatively, a plurality of layers of the strand material 1 may cover the outer peripheral surface of the annular core portion 3. For example, when the outer peripheral surface of the annular core portion 3 is covered with two layers of the strand material 1, the strand material 1 is wound around the outer peripheral surface of the annular core portion 3 to form the first layer, and then the first layer is formed. The second layer is formed by winding 12 strands of the strand material 1 around the outer peripheral surface. The winding direction (twisting direction) of 12 turns corresponding to the second layer is preferably opposite to the winding direction of 6 turns corresponding to the first layer. Setting such a winding direction is important in obtaining good winding properties and obtaining an outer surface with less unevenness.

  Further, in the annular metal cord C1 of the transmission belt B1 of the present embodiment, the second metal strand 11 constituting the strand material 1 is S-twisted, and the winding of the strand material 1 of the outer layer portion 4 around the annular core portion 3 is Z Although it is performed by twisting, the second metal strand 11 of the strand material 1 may be Z-twisted, and the strand material 1 of the outer layer portion 4 may be wound around the annular core portion 3 by S-twisting.

  Moreover, as shown to Fig.6 (a), although the cyclic | annular metal cord C1 of this embodiment has a substantially circular cross section, it is good also considering a cross section as a flat shape. In this case, the substantially circular annular metal cord C1 is deformed by pressing or the like.

  Further, the transmission belt B1 of the present embodiment has five annular metal cords C1, but the number of the annular metal cords C1 is not limited to this. The number of the annular metal cords C1 can be adjusted according to the required bending resistance and durability.

  Moreover, the kind of transmission belt is not restricted to the general industrial V belt. FIG. 12 is a cross-sectional perspective view showing another modification of the transmission belt. The transmission belt B2 shown in FIG. 12 is a toothed timing belt, and is formed by covering the annular metal cord C1 with a covering member 80 using a tensile strength member. The covering portion 80 includes a material such as rubber. Such a transmission belt B2 is also excellent in breaking strength and fatigue resistance.

  Moreover, the material of the 1st metal strand 31 and the 2nd metal strand 11 is not restricted to said thing.

It is a section perspective view of the power transmission belt concerning this embodiment. It is a perspective view of an annular metal cord. It is a cross-sectional perspective view of the radial direction which shows a cyclic | annular metal cord. It is a perspective view which shows a mode that a metal strand is continuously wound around the loop part of the metal strand of the cyclic | annular core part contained in a cyclic | annular metal cord. (A) is a perspective view which shows a mode that the strand material was wound around the cyclic | annular core part contained in a cyclic | annular metal cord, and (b) is an enlarged view which shows the coupling | bond part of a cyclic | annular core part. (A) is sectional drawing of the radial direction which shows a cyclic | annular metal cord, (b) is a side view of a cyclic | annular metal cord. It is an expansion perspective view which shows a part including the coupling | bond part of the outer layer part of a cyclic | annular metal cord. It is a perspective view which shows an example of the manufacturing apparatus for manufacturing a cyclic | annular metal cord. The state where the reel is located outside the ring of the annular core part at one end of the period of the pendulum movement of the annular core part is indicated by a solid line, and the reel is located inside the ring of the annular core part at the other end of the period of the pendulum movement of the annular core part. It is a front view of the apparatus of FIG. 8 which showed the state located in a chain line. Contrary to FIG. 9, the state where the reel is located in the ring of the annular core portion at one end of the cycle of the pendulum motion of the annular core portion is indicated by a solid line, and the reel is at the other end of the cycle of the pendulum motion of the annular core portion. It is the front view of the apparatus of FIG. 8 which showed the state located outside the ring | wheel of an annular core part with the dashed line. It is a conceptual diagram when the movement state of the reel at the time of manufacturing the cyclic | annular metal cord which concerns on this embodiment is seen from the upper surface. It is a cross-sectional perspective view which shows the modification of a power transmission belt.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Strand material, 1a ... Winding start end part, 1b ... Winding termination | terminus part, 3 ... Ring core part, 11 ... 2nd metal strand, 31 ... 1st metal strand, 31a ... Start end part, 31b ... Termination part DESCRIPTION OF SYMBOLS 4 ... Outer layer part, 7 ... Connection member (coil spring-like sleeve), 70, 80 ... Covering part, B1, B2 ... Transmission belt, C1 ... Ring metal cord.

Claims (15)

An annular metal cord serving as a tensile body, and a covering portion covering the annular metal cord,
The annular metal cord is
A part of the first metal strand is a loop having a predetermined annular diameter, and the extra length of the first metal strand is spirally wound around the loop, and the first metal strand is wound. An annular core portion formed by joining the start and end portions of
One strand material formed by twisting a plurality of second metal strands is wound around the annular core portion in a spiral manner to cover the outer peripheral surface of the annular core portion, and the winding start end of the strand material A power transmission belt comprising: an outer layer portion formed by coupling a winding end portion and a winding end portion. The transmission belt according to claim 1,
The power transmission belt is characterized in that the number of times that the first metal strand is spirally wound around the loop of the first metal strand is not less than 3 times and not more than 30 times per round. The transmission belt according to claim 1 or 2,
The power transmission belt according to claim 1, wherein the first metal element wire is spirally wound around the loop of the first metal element wire in a spiral shape of 2 to 6 turns. The transmission belt according to any one of claims 1 to 3,
The transmission belt according to claim 1, wherein the first metal element and the strand material have different positions in the annular direction of the annular metal cord. The transmission belt according to any one of claims 1 to 4,
Both ends of the first metal strand are joined by welding,
Both ends of the strand material are joined by welding and are covered and reinforced by a coil spring-like sleeve. The transmission belt according to claim 5,
The transmission belt is characterized in that an adhesive is applied to both ends of the strand material that are joined by welding. The transmission belt according to any one of claims 1 to 6,
The material of the first metal strand is C: 0.08 to 0.27 mass%, Si: 0.30 to 2.00 mass%, Mn: 0.50 to 2.00 mass%, Cr: 0 .20 to 2.00% by mass, Al, Nb, Ti, and V are contained in the range of 0.001 to 0.10% by mass, respectively, and the balance is mixed with Fe and unavoidable A transmission belt characterized by alloy steel made of impurities coming from. The transmission belt according to any one of claims 1 to 7,
The transmission belt according to claim 1, wherein a wire diameter of the first metal element wire is 0.10 mm or more and 0.40 mm or less. The transmission belt according to any one of claims 1 to 8,
The power transmission belt, wherein a diameter of the second metal element wire is 0.06 mm or more and 0.30 mm or less. The transmission belt according to any one of claims 1 to 9,
The transmission belt, wherein a twist direction of the second metal element wire in the strand material and a winding direction of the strand material around the annular core portion are opposite. A transmission belt according to any one of claims 1 to 10,
The transmission belt, wherein a winding angle of the strand material with respect to a central axis of the annular core portion is 4.5 degrees or more and 13.8 degrees or less. The transmission belt according to any one of claims 1 to 11,
6. The transmission belt according to claim 1, wherein the strand material is wound not less than 6 times and not more than 8 times along the outer peripheral surface of the annular core portion. The transmission belt according to any one of claims 1 to 12,
The transmission belt, wherein the annular core portion and the outer layer portion are subjected to a low temperature annealing treatment. The transmission belt according to claim 13,
The transmission belt according to claim 1, wherein the outer layer portion is spirally shaped with respect to the annular core portion. An annular metal cord serving as a tensile body, and a covering portion that covers the annular metal cord, the annular metal cord being annularly formed, and a plurality of spiral windings around the annular core portion And an outer layer portion covering the outer peripheral surface of the annular core portion,
A part of the first metal strand is formed into a loop having a predetermined annular diameter, and the extra length of the first metal strand is continuously wound around the loop in a plurality of rounds, and the first metal strand is wound. An annular core portion is formed by joining the start and end portions of the wire,
One strand material formed by twisting a plurality of second metal strands is wound around the annular core portion in a spiral manner to cover the outer peripheral surface of the annular core portion, and the winding start end of the strand material An outer layer portion is formed by joining a portion and a winding end portion to form the annular metal cord.

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