JP7447068B2 - Toothed belt and its manufacturing method - Google Patents

Description

The present invention relates to a toothed belt used for synchronous transmission in a device that transmits power by belt drive.

Transmission belts that transmit power are broadly classified into friction transmission belts and meshing transmission belts. Examples of friction transmission belts include flat belts, V belts, and V-ribbed belts, and examples of meshing transmission belts include toothed belts. A toothed belt consists of a back part in which core wires are buried approximately parallel to the belt's longitudinal direction, teeth parts arranged at predetermined intervals in the belt's longitudinal direction, and a protective layer (reinforced by a fiber material) that forms the surface of the tooth parts. A belt having a layer) is commonly used. As the protective layer (fiber member), a cloth material (tooth cloth) such as a woven fabric or a knitted fabric is usually used (see Patent Document 1).

When a woven fabric is used for the protective layer (fiber member), a woven fabric with ends is used, and both ends of the woven fabric are joined by welding, sewing, or the like, and the woven fabric is placed in a ring shape on a toothed belt. Therefore, there are joints (seams) of the woven fabric within the circumference of the toothed belt. There are disadvantages in that cracks occur at the joints and the rubber composition constituting the teeth tends to ooze out. In addition, if both ends of the woven fabric are overlapped and joined, bleeding can be suppressed, but if a thick overlapped part is placed at the bottom of the tooth, the position of the core wire (PLD: Pitch Line Differential) will be unstable. become. Furthermore, the manufacturing process including bonding requires expensive equipment and a great deal of labor and time, which is not economical.

In addition, in the case of knitted fabric, it is possible to produce a cylindrical knitted fabric with no joints (seams) due to its manufacturing method, so there is no need for a separate joining process, and there are no joints (seams) within the circumference of the toothed belt. ) does not exist.

Patent No. 5039838

However, since knitted fabrics are generally knitted with threads intertwined in a loop, large gaps inevitably exist between the threads of the knitted fabric. Due to the existence of this gap, when manufacturing a toothed belt, the rubber composition forming the tooth portion is likely to pass through the gap between the threads of the knitted fabric and be exposed to the outside. That is, on the meshing transmission surface of the toothed belt, there are places where the rubber composition is not covered with the knitted fabric.

Therefore, an object of the present invention is to provide a protective layer (fiber member) that constitutes the surface of the teeth, which is the meshing and transmission surface of a toothed belt, without joints (seams), and to provide a rubber composition that forms the teeth. It is to suppress exposure (bleeding).

The toothed belt of the present invention has a plurality of teeth arranged at predetermined intervals in the belt longitudinal direction,
The surface of the tooth portion is composed of a braid formed by combining three or more braid threads,
The braided yarn is characterized in that it is made of a yarn obtained by combining a bulky processed yarn and a shape-retaining yarn having lower stretchability than the bulky processed yarn.

According to the above configuration, in the braided fabric, since the plurality of braided threads are arranged densely, the gaps between the threads are smaller than in a knitted fabric. Further, the braided thread is made of a thread obtained by combining a bulky processed thread with high elasticity and a shape-retaining thread with low elasticity. Therefore, when forming a braid, the shape-retaining thread with low elasticity bears most of the tension applied to the braid. This prevents the bulky textured yarn from stretching completely and suppresses the gap between the yarns from widening. Therefore, in the present invention, since the above-mentioned braid is employed as a protective layer that constitutes the surface of the tooth portion that becomes the meshing transmission surface, it is possible to suppress the rubber composition that constitutes the tooth portion from being exposed from the braid. Can be done.

Further, the present invention may be characterized in that the shape-retaining thread in the toothed belt is thermoplastic.

According to the above configuration, the shape-retaining thread is melted by heat treatment after the braid is braided with the braid containing the thermoplastic shape-retaining thread, so the braid is braided with the braid thread containing the shape-retaining thread. can be easily molded into the desired shape. Moreover, by cooling the braid after forming it, the shape-retaining threads solidify and the shape of the braid is stabilized. Thereby, in the manufacturing process of the toothed belt, the work of covering the belt molded body with the braid can be easily performed.

Further, in the toothed belt of the present invention, the shape-retaining thread may have a melting point of 100°C or more and 180°C or less.

According to the above configuration, the melting point of the shape-retaining thread is 100°C or higher. According to this, the shape-retaining threads do not melt when the toothed belt is used, so it is possible to avoid abnormal noises and transmission failures. Further, the melting point of the shape-retaining thread is 180°C or lower. According to this, since the shape-retaining yarn is melted during the vulcanization process in the manufacturing process of the toothed belt, the braided yarn is stretched, and the shape of the toothed portion can be stably formed.

Further, in the toothed belt of the present invention, the braid may be a seamless tubular braid.

According to the above configuration, since there is no seam in the braid, it is possible to prevent the braid from cracking at the seam and peeling off from the interface with the tooth portion.

Further, in the toothed belt of the present invention, the braid may include 30 or more braided threads.

According to the above configuration, the effect of protecting the interface between the braid and the tooth portion can be enhanced.

Further, in the toothed belt of the present invention, the intersecting braided threads of the braid may have a braiding angle in a range of 85° or more and 89° or less with respect to the belt width direction. .

According to the above configuration, by arranging the braid at an angle close to the longitudinal direction of the belt, it is possible to ensure the extension of the braid in the longitudinal direction of the belt, and to arrange the braid along the surface of the tooth portion. . Furthermore, it is possible to reinforce the toothed belt in the longitudinal direction of the belt, in which the direction in which stress (load) is applied due to contact between the teeth and the pulley is mainly in the longitudinal direction of the belt.

Further, in the toothed belt of the present invention, the ratio of the fineness of the shape-retaining yarn to the total fineness of the bulky processed yarn and the shape-retaining yarn of the braided yarn is 10% or more and 50% or less. This may be a feature.

If the fineness of the shape-retaining yarn is less than 10% of the total fineness, the shape-retaining effect of the braid cannot be obtained, and if the fineness of the shape-retaining yarn is more than 50% of the total fineness, it will not melt during the manufacturing process of the toothed belt. The proportion of remaining fibers decreases, and the effect of the fibers (the effect of protecting the teeth) becomes smaller. Therefore, by setting the fineness of the shape-retaining yarn to the total fineness of 10% or more and 50 or less, it is possible to obtain the shape-retaining effect of the braid while ensuring the effect of protecting the teeth.

Further, in the toothed belt of the present invention, the bulky textured yarn may be a composite yarn containing two or more types of yarn.

According to the above configuration, it is possible to impart complex extensibility to the braid depending on the type of yarn.

Further, the present invention may be characterized in that, in the toothed belt, the composite yarn includes a polyurethane elastic yarn and a woolly processed polyamide (nylon) yarn.

According to the above configuration, sufficient stretchability is ensured for placing the braid along the surface of the teeth, and the braid retains its shape while also exhibiting a good effect of protecting the teeth. Can be done.

The present invention also provides a method for manufacturing the toothed belt, comprising:
Arranging the cylindrical braid on the outer periphery of a cylindrical mold whose outer periphery is provided with tooth grooves corresponding to the teeth of the toothed belt, further arranging the belt molded body on the outside in the radial direction, By pressing the belt molded body from the outer peripheral side toward the inside in the radial direction, the braid is press-fitted together with the belt molded body into the tooth groove, and as the tooth portion is formed, the belt molded body is pressed along the surface of the tooth portion. It is characterized by the arrangement of braids.

According to the above method, the braid extending in the longitudinal direction of the toothed belt can be stably arranged along the shape of the teeth.

The present invention also provides the method for manufacturing the toothed belt, comprising:
Forming the seamless cylindrical braid by combining three or more of the braided threads including the thermoplastic shape-retaining threads on the outer periphery of the mandrel;
The formed braid may be heat-treated at a first predetermined temperature for a predetermined time and then cooled to a second predetermined temperature.

According to the above method, since the shape-retaining threads are melted or softened by heat treatment at the first predetermined temperature, it is possible to easily mold a braided article made of braided threads including shape-retaining threads into a desired shape. can. Further, after the braid is formed, the shape-retaining thread is solidified by cooling the braid to a second predetermined temperature, thereby stabilizing the shape of the braid. Thereby, the work of covering the mold for manufacturing the toothed belt with the braid can be easily performed. That is, the shape-retaining thread functions as a melting thread that melts or softens through heat treatment, and contributes to maintaining the shape of the braid.

The present invention also provides the method for manufacturing the toothed belt, comprising:
The braid may be formed by combining three or more braided yarns on the outer periphery of the cylindrical mold.

According to the above method, a cylindrical braid can be formed by combining braided threads on the outer periphery of a cylindrical mold, or by combining braided threads and shaft threads. In this case, the work of combining the braided yarns with each other on the outer periphery of the mandrel is not performed, and the demolding work of pulling them out from the mandrel is not necessary. Therefore, it is not necessary to heat-treat the formed braid. When assembling a braid on the outer periphery of a cylindrical mold, the shape-retaining threads with low elasticity bear the tension on the braid, preventing the bulky textured threads from stretching out, and improving the bond between the threads of the braid and the threads. This can prevent the gap between them from widening. That is, the shape-retaining yarn functions as a tension-bearing member that bears the tension applied to the braid, and contributes to maintaining the shape of the braid.

In the protective layer (fiber member) that constitutes the surface of the teeth, which is the meshing transmission surface of the toothed belt, there are no joints (seams), and the rubber composition that forms the teeth is prevented from being exposed (bleeding). . Furthermore, the belt manufacturing process is simplified by simplifying the fabric manufacturing process, which requires a great deal of labor and time.

It is a cross-sectional perspective view showing an example of a toothed belt concerning this embodiment. FIG. 2 is a cross-sectional view (illustrative diagram) of the toothed belt according to the present embodiment in the belt longitudinal direction. (a) It is an explanatory view of the cylindrical braid used as a protective layer of the toothed belt concerning this embodiment. (b) It is a figure which shows the knitted fabric used as the comparison object of a braid. (a) It is a schematic diagram of the assembling machine of this embodiment. (b) It is an orbital diagram of the spindle when producing a braid with a braiding machine. It is an explanatory view of a manufacturing method of a toothed belt.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Toothed belt 1)
FIG. 1 is a cross-sectional perspective view showing an example of a toothed belt according to the present embodiment.
As shown in FIG. 1, the toothed belt 1 includes a back part 4 in which the core wire 3 is embedded spirally along the belt longitudinal direction, and an inner circumferential surface of the back part 4 (corresponding to one surface of the back part 4). The belt has a plurality of teeth 2 provided at predetermined intervals along the longitudinal direction of the belt. In this embodiment, the plurality of teeth 2 are integrally formed on the inner circumferential surface of the back portion 4 . Further, as shown in FIG. 1, the tooth portion 2 extends parallel to the belt width direction, and the tooth portion 2 has a trapezoidal longitudinal cross-sectional shape in the belt longitudinal direction. Further, the inner circumferential surface of the toothed belt 1 , that is, the surface of the tooth portion 2 and a portion of the inner circumferential surface (tooth bottom portion) of the back portion 4 are constituted by a protective layer 5 . The surface constituted by this protective layer 5 becomes a contact surface (meshing transmission surface) with a toothed pulley or the like.

Note that the shape of the toothed belt 1 is not limited to the structure shown in FIG. It suffices if it has a plurality of teeth 2 or convex portions that can be engaged with each other. The cross-sectional shape of the toothed portion 2 or the convex portion (cross-sectional shape in the belt longitudinal direction or belt width direction) is not limited to the trapezoid, but may be, for example, semicircular, semielliptic, or polygonal depending on the form of the toothed pulley. It may be a square (triangle, quadrilateral (rectangle, etc.), etc.). Further, the interval between adjacent teeth 2 or protrusions in the belt longitudinal direction (tooth pitch P (see Fig. 2)) is, for example, about 1 to 14 mm, preferably about 3 to 8 mm, depending on the form of the toothed pulley. There may be. Further, the circumferential length of the toothed belt 1 is, for example, 80 to 400 mm. The width W of the toothed belt 1 is, for example, 4 to 30 mm. That is, the toothed belt 1 of this embodiment is used for relatively low load applications.

(back part 4 and tooth part 2)
The back portion 4 and the tooth portion 2 are made of a rubber composition, and the rubber components of this rubber composition include chloroprene rubber (CR), nitrile rubber, hydrogenated nitrile rubber (HNBR), and ethylene-propylene copolymer (EPM). ), ethylene-propylene-diene terpolymer (EPDM), styrene-butadiene rubber (SBR), butyl rubber (IIR), chlorosulfonated polyethylene rubber (CSM), etc. are used. In particular, ethylene-propylene-diene terpolymer (EPDM), chloroprene rubber (CR), and hydrogenated nitrile rubber (HNBR) are preferably used. In this embodiment, the rubber compositions constituting the back portion 4 and the tooth portions 2 are made of the same rubber composition, but may be made of different rubber compositions.

The rubber composition constituting the back portion 4 and the tooth portion 2 may contain various conventional additives (or compounding agents) as necessary. Additives include vulcanizing agents or crosslinking agents (for example, oximes (quinone dioxime, etc.), guanidines (diphenylguanidine, etc.), metal oxides (magnesium oxide, zinc oxide, etc.)), vulcanization aids, Sulfur accelerators, vulcanization retarders, reinforcing agents (carbon black, silicon oxides such as hydrated silica, etc.), metal oxides (e.g. zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide) , aluminum oxide, etc.), fillers (clay, calcium carbonate, talc, mica, etc.), plasticizers, softeners (oils such as paraffin oil, naphthenic oil, etc.), processing agents or processing aids (stearic acid, stearin acid metal salts, waxes, paraffins, etc.), anti-aging agents (aromatic amine anti-aging agents, benzimidazole anti-aging agents, etc.), stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), lubricants , flame retardants, antistatic agents, etc. These additives can be used alone or in combination, and can be selected depending on the type, application, performance, etc. of the rubber component.

(core wire 3)
In order to improve running stability and belt strength, the core wire 3 usually has twisted cords extending along the longitudinal direction of the belt spirally embedded at predetermined intervals in the width direction of the belt. More specifically, as shown in FIGS. 1 and 2, the core wires 3 are arranged at predetermined intervals (or pitches) (or at equal intervals) from one end of the back portion 4 in the belt width direction to the other end. ) may be buried. The spacing (spinning pitch SP), which is the distance between the centers of adjacent core wires 3, may be, for example, about 0.4 to 2.0 mm depending on the diameter of the core wires 3.

The core wire 3 may be formed of a twisted cord made by twisting a plurality of strands or multifilament yarns. Among these, a twisted strand cord is preferred, and one strand may be formed by bundling filaments (long fibers). The average wire diameter (diameter of the twisted cord) of the core wire 3 is, for example, about 0.2 to 2.5 mm. There are no particular restrictions on the thickness of the filaments forming the twisted cord, the number of converged filaments, the number of strands, and the twist configuration of the twisting method.

The fibers forming the core wire 3 are not particularly limited, and include, for example, polyester fibers (polyalkylene arylate fibers, polyparaphenylene naphthalate fibers), polybenzoxazole fibers, acrylic fibers, polyamide fibers (fatty Examples include synthetic fibers such as group polyamide fibers and aramid fibers, and inorganic fibers such as glass fibers, carbon fibers, and metal fibers (steel fibers). These fibers can be used alone or in combination. As the fibers forming the core wire 3, synthetic fibers such as polyester fibers and polyamide fibers, and inorganic fibers such as glass fibers and carbon fibers are commonly used because of their low elongation and high strength.

The core wire 3 may be subjected to an adhesive treatment in order to improve its adhesion to the back portion 4. The adhesive treatment method may be, for example, a method in which a twisted cord is immersed in a resorcinol-formalin-latex treatment liquid (RFL treatment liquid) and then heated and dried to form a uniform adhesive layer on the surface of the twisted cord. good. The RFL treatment liquid is a mixture of latex and an initial condensate of resorcinol and formalin, and the latex includes, for example, chloroprene rubber, styrene-butadiene-vinylpyridine terpolymer (VP latex), nitrile rubber, and hydrogen. Chemical nitrile rubber or the like may also be used. Furthermore, the method of adhesion treatment may be a method of performing pretreatment with an epoxy compound or isocyanate compound and then treating with an RFL treatment liquid.

(Protective layer 5)
The surface of the toothed portion 2 of the toothed belt 1 of this embodiment and a portion of the inner circumferential surface (tooth bottom portion) of the back portion 4, that is, the meshing transmission surface of the toothed belt 1 are constituted by the protective layer 5. This suppresses wear on the surface of the toothed portion 2 and a portion of the inner circumferential surface of the back portion 4 due to contact with the toothed pulley, improving durability. Furthermore, since the exposure of the rubber composition to the meshing transmission surfaces is suppressed, the protective effect is improved.

(Protective layer 5: braid 7)
In this embodiment, a braid 7 is particularly used as the protective layer 5 constituting the meshing transmission surface. The braided fabric 7 is a fabric made by combining three or more braided threads 71, and its fiber structure is significantly different from a knitted fabric in which the threads are intertwined in a loop or a woven fabric in which the warp and weft are woven orthogonally. The braid 7 has two characteristics: high elasticity and high thread density. First, the braid 7 has much higher stretchability due to its fiber structure than a woven fabric woven with warp and weft yarns. On the other hand, the stretchability of the knitted fabric is as high as that of the braid 7. However, the braid 7 is definitely different from a knitted fabric in that the braid 71 is densely arranged.

As shown in FIG. 3(b), since the knitted fabric is knitted by intertwining the threads in a loop, large gaps inevitably exist between the threads. On the other hand, as shown in FIG. 3(a), in the braid 7, since the threads are arranged densely, the gaps between the threads are smaller than in the knitted fabric.

Furthermore, the braid 7 used in this embodiment is a seamless tubular braid 7 that has no seams and is excellent in strength. Since there is no seam in the braid 7, the rubber layer (teeth 2, back part 4) and the protective layer 5 of the protective layer 5 (braid 7) may crack due to cracks in the braid 7 from the seams. Peeling from the interface is less likely to occur. Further, since the overlapped portion due to the seam is not arranged at the bottom of the tooth, the position of the core wire 3 (PLD: Pitch Line Differential) is stabilized.

The braid 7 of this embodiment is formed by combining three or more braid threads 71 and axis threads 72 with each other. As shown in FIG. 3(a), the braided threads 71 intersect with the axis (axial direction (belt width direction)) of the braided material 7 at a predetermined braiding angle ±θ.
In the toothed belt 1, the direction in which stress (load) is received due to contact with the toothed pulley is the belt longitudinal direction (circumferential direction). Therefore, it is important to reinforce the belt in the longitudinal direction from the viewpoint of increasing tooth chipping resistance, which leads to durability. Therefore, in this embodiment, each of the intersecting braiding yarns 71 of the braiding 7 has a braiding angle (85 (°≦θ≦89°). The braiding angle in this range is an angle extremely close to 90° with respect to the axis, that is, an angle at which the braiding threads 71 are arranged substantially facing the longitudinal direction of the belt (circumferential direction of the braid 7: see FIG. 3(a)). It means that. Thereby, the braid 7 can be arranged along the surface of the tooth portion 2 while ensuring the extension of the braid 7 in the belt longitudinal direction. Furthermore, it is possible to reinforce the toothed belt 1 in the longitudinal direction of the belt, in which the direction in which stress (load) is received due to the contact between the toothed portion 2 and the toothed pulley is mainly in the longitudinal direction of the belt.

The braid 7 can be formed only with a plurality of braids 71, but from the viewpoint of improving the shape retention of the tubular braid 7 and improving the handling in the toothed belt manufacturing process described below, Axial threads 72 parallel to the axis (axial direction (belt width direction)) of the tubular braid 7 may be used.

(Kumi thread 71)
The braided yarn 71 is made of a yarn made by combining a bulky processed yarn and a shape-retaining yarn having lower stretchability than the bulky processed yarn. The braided yarn 71 is a bulky textured yarn with high elasticity, so that the braided fabric 7 can be made stretchable. In addition, the braiding yarn 71 prevents the bulky processed yarn from stretching completely and prevents the gap between the threads of the braiding 7 from widening because the shape-retaining thread with low elasticity bears the tension applied to the braiding thread 71. It can be prevented. That is, the shape-retaining yarn functions as a tension-bearing member that bears the tension related to the braided thread 71, and contributes to maintaining the shape of the braided article 7.

Moreover, the shape-retaining thread is thermoplastic. After braiding the braid 7 with the braiding threads 71, the shape-retaining threads are melted or softened by heat treatment, so the braid 7 braided with the braiding threads 71 including the shape-retaining threads can be easily molded into the desired shape. Become. Further, after forming the braid 7, cooling is performed to solidify the shape-retaining threads and stabilize the shape of the braid 7. Thereby, in the manufacturing process of the toothed belt 1 which will be described later, the work of covering the braid 7 on the cylindrical mold 90 for manufacturing the toothed belt can be easily performed.

Furthermore, the shape-retaining thread has a melting point in a range of 100°C or more and 180°C or less. According to this, when the toothed belt 1 is used, the shape-retaining threads do not melt, so it is possible to avoid abnormal noises and transmission failures. In the manufacturing process of the toothed belt 1, the rubber composition and the cylindrical braid 7 are press-fitted into the groove 91 of the cylindrical mold 90 by heat and pressure, and the cylindrical braid 7 is shaped into the contour shape of the toothed part 2. Since the shape-retaining thread melts or softens in the process of being stretched into a shape along the shape and disposed on the surface of the tooth portion 2, the elongation of the bulky processed thread proceeds without being hindered by the shape-retaining thread. As a result, the braided yarn 71 is stretched, and a shape that follows the contour of the tooth portion 2 can be stably formed. That is, the shape-retaining thread functions as a melting thread that melts or softens through heat treatment or vulcanization treatment, and contributes to maintaining the shape of the braid 7.

As the bulky yarn, a composite yarn containing two or more types of highly elastic yarns can be used. As the elastic yarn having good elasticity, for example, polyurethane elastic yarns such as Spandex (registered trademark) and Roica (registered trademark) can be employed. Alternatively, processed yarns such as woolly processed yarn, Taslan processed yarn, conjugate yarn, and covering yarn can be used.

Woolly textured yarn is a yarn that has elasticity from a structural point of view.For example, woolly textured yarn uses a yarn with curls obtained by false twisting the fibers, heat setting them, and then untwisting the fibers. It's okay.

Conjugate yarn has a cross-sectional structure in which two or more types of polymers with different heat shrinkage rates are bonded together in the fiber axis direction, and when heat is applied during manufacturing or processing, the shrinkage rates (heat shrinkage rates) of each polymer differ. This causes crimp and results in a bulky yarn. For example, there are composite yarns that are a conjugate of polytrimethylene terephthalate (PTT) and polyethylene terephthalate (PET) (PTT/PET conjugate yarn), and composite yarns that are a conjugate of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) (PTT/PET conjugate yarn). PBT/PET conjugate yarn). As mentioned above, conjugate yarns containing polyethylene terephthalate (PET) can be used.

In addition, the covered yarn is a yarn whose cross-sectional volume as a whole is increased by covering (covering) the periphery of the core yarn with another yarn. For example, there are composite yarns (PET/PU covered yarn) in which highly elastic polyurethane (PU) yarn is used as a core yarn and its surface is covered with polyethylene terephthalate (PET), and composite yarns in which PU is used as a core yarn and covered with polyamide (PA). There is a composite yarn (PA/PU covered yarn). Among these composite yarns, PTT/PET conjugate yarns or PET/PU covered yarns are preferred because they have excellent elasticity and abrasion resistance.

The material of the bulky yarn includes, for example, water absorbent fibers (e.g., cellulose fibers), polyamide fibers (e.g., nylon fibers and aramid fibers), polyester fibers (e.g., polyethylene terephthalate fibers and polybutylene terephthalate fibers), and polyurethane elastic fibers. Bulky textured yarn made of a material such as fiber containing yarn can be used. Note that cellulose fibers include bamboo fibers, sugarcane fibers, seed hair fibers (cotton fibers (cotton linters), kapok, etc.), ginskin fibers (for example, hemp, mulberry, mitsumata, etc.), and leaf fibers (for example, Manila hemp, New Zealand hemp, etc.). Examples include cellulose fibers (pulp fibers) derived from natural plants such as (hemp, etc.), cellulose fibers derived from animals such as wool, silk, and ascidian cellulose, bacterial cellulose fibers, and cellulose from algae.

Among these elastic yarns, it is particularly preferable to use a composite yarn containing a polyurethane elastic yarn and a woolly textured polyamide (nylon) yarn. According to this, sufficient extensibility is ensured to arrange the braid 7 along the surface of the tooth part 2, and the effect of protecting the tooth part 2 can be achieved while obtaining the shape-retaining effect of the braid 7. able to demonstrate.

Further, as the shape-retaining thread, for example, low melting point nylon thread, polypropylene thread, low melting point PET thread, polylactic acid thread, etc. can be employed. Note that the yarn obtained by combining the bulky processed yarn and the shape-retaining yarn may be a yarn obtained by simply pulling the bulky processed yarn and the shape-retaining yarn together, or by twisting the bulky processed yarn and the shape-retaining yarn after aligning them. It can also be twisted yarn. Furthermore, any of the above-mentioned yarns may be further heat-treated to integrate a bulky textured yarn and a shape-retaining yarn.

Additionally, due to its fiber structure, the braid 7 has threads arranged more densely than knitted fabric, but it is also possible to protect the interface between the rubber layer (teeth 2, back 4) and the protective layer 5. In order to enhance the effect, it is desirable to keep the spacing between the threads as small as possible. Therefore, in this embodiment, the number of threads 71 forming the braid 7 is 30 or more. Further, the set pitch d, which is the distance between the center lines of adjacent braided threads 71, is 30 mm or less, preferably 15 mm or less (see FIG. 3(a)). The total fineness of one braided yarn 71 is 500 dtex or more, preferably 800 dtex or more.

Further, it is preferable that the ratio of the fineness of the shape-retaining yarn to the total fineness of one braided yarn 71 (the combined fineness of the bulky textured yarn and the shape-retaining yarn) is 10% or more and 50% or less. If the proportion is too small, the shape-retaining effect cannot be obtained, and if the proportion is too large, the proportion of the fibers that remain without being melted decreases, and the effect of the fibers (the effect of protecting the tooth portion 2) becomes small.

(Axoneme 72)
From the viewpoint of improving the shape retention of the tubular braid 7 and improving handling in the manufacturing process of the toothed belt 1, which will be described later, it is possible to use the shaft threads 72 parallel to the axial direction of the tubular braid 7. good. The shaft thread 72 may be a molten thread that is melted or softened by heat treatment or vulcanization treatment. Examples of the melt thread include thermoplastic threads such as low melting point nylon threads and polypropylene threads used as shape-retaining threads of the braided threads 71.

In addition, in the toothed belt 1 of this embodiment, the direction in which stress (load) is received due to contact with the toothed pulley is the longitudinal direction of the belt, so the direction in which reinforcement in the tubular braid 7 is required is mainly in the longitudinal direction of the belt. direction (circumferential direction), and it is possible to omit reinforcement in the belt width direction. Therefore, the cylindrical braid 7 may be used for the toothed belt 1 without the axis thread 72 parallel to the axial direction (belt width direction) of the cylindrical braid 7.

(Manufacturing method of toothed belt 1: heat treatment demolding method)
(Preparation of tubular braid 7)
As shown in FIG. 4(a), the cylindrical braid 7 is produced using a braiding machine 8. The shaft thread 72 is fed from the lower part of the braiding machine 8 through a fixed cylinder 10, and the braiding thread 71 is wound around the spindle 11. A cylindrical mandrel 9 is installed in the center of the braiding machine 8, and the braid 7 is formed by combining the braid 71 and the shaft thread 72 on the outer periphery of the upper part of the mandrel 9 (three or more braid threads 71 ). As shown in FIG. 4(b), as the spindle 11 moves along the track 12, the braid 71 and the axis thread 72 are combined, forming a seamless braid 7 on the upper part of the mandrel 9. The object 7 is rolled up by a winding device 13. Note that the outer circumferential length of the mandrel 9 is longer than the outer circumferential length of a cylindrical mold 90 (cylindrical mold) for manufacturing the toothed belt 1, which will be described later.

As described above, when braiding the braid 7 on the outer periphery of the mandrel 9, the shape-retaining threads with low elasticity bear the tension applied to the braiding thread 71, thereby preventing the bulky textured threads from stretching completely and making the braid 7 This can prevent the gap between the threads from widening. That is, the shape-retaining yarn functions as a tension-bearing member that bears the tension applied to the braided thread 71, and contributes to maintaining the shape of the braided fabric 7.

In the method for producing the braid 7 described above, the braid 71 and the axis thread 72 are combined with each other on the outer periphery of the mandrel 9. This makes the gaps between the braided threads 71 in one tubular braid 7 uniform.

In addition, although the tubular braid 7 contracts after being pulled out from the mandrel 9, by forming the tubular braid 7 in advance to have a long circumference in anticipation of the shrinkage, it is possible to prevent the tubular braid 7 from being removed in subsequent steps. This does not make it difficult to cover the cylindrical mold 90 for manufacturing the toothed belt 1 with the cylindrical braid 7.

Further, after forming the braid 7 on the outer periphery of the mandrel 9, the braid 7 is heat-treated at a first predetermined temperature for a predetermined time, and then cooled to a second predetermined temperature. After braiding the braid 7 with the braiding threads 71, the shape-retaining threads are melted or softened by heat treatment, so the braid 7 braided with the braiding threads 71 including the shape-retaining threads can be easily molded into the desired shape. Become. Further, after forming the braid 7, cooling is performed to solidify the shape-retaining threads and stabilize the shape of the braid 7. Thereby, the work of covering the braid 7 on the cylindrical mold 90 (cylindrical mold) for manufacturing the toothed belt 1 can be easily performed. That is, the shape-retaining thread functions as a melting thread that melts or softens through heat treatment, and contributes to maintaining the shape of the braid 7.

Note that the first predetermined temperature when performing the heat treatment is any temperature within the range of "melting point -20°C" to "melting point +50°C" of the shape-retaining thread. Moreover, the predetermined time is determined according to the first predetermined temperature. That is, when the first predetermined temperature is high, the predetermined time becomes short, and when the first predetermined temperature is low, the predetermined time becomes long. According to the first predetermined temperature and the predetermined time, the shape-retaining thread is melted or softened, so that the braid can be easily formed. Further, the second predetermined temperature may be any value as long as it is a temperature at which the shape-retaining thread solidifies. Further, "cooling until the second predetermined temperature is reached" may be performed by a cooling device or the like, or may be natural cooling by leaving at room temperature. The method for manufacturing the cylindrical braid 7 described here will be referred to as a heat treatment demolding method in the examples described below.

(Adhesion treatment of braid 7)
The braid 7 is subjected to an adhesive treatment for the purpose of improving the adhesion between the rubber layer (tooth portion 2, back portion 4) formed of a rubber composition and the interface between the protective layer 5 (braid 7). Can be done. The adhesive treatment for such a braid 7 is a resin-based treatment in which a resin component such as an epoxy compound, an isocyanate compound, or a carbodiimide compound is dissolved (dispersed) in a solvent (dispersion medium) such as toluene, xylene, methyl ethyl ketone, or water. Examples include immersion treatment in a liquid, immersion treatment in a resorcinol-formalin-latex liquid (RFL liquid), and immersion treatment in a rubber paste prepared by dissolving a rubber composition in an organic solvent. Other adhesive treatment methods include, for example, a friction process in which the braid 7 and the rubber composition are passed through a calendar roll to imprint the rubber composition on the braid 7, a spreading process in which rubber glue is applied to the braid 7, A coating process or the like in which a rubber composition is laminated on the braid 7 can also be employed.

In this way, by applying the adhesive treatment to the braid 7, the adhesiveness between the rubber layer (tooth portion 2, back portion 4) and the protective layer 5 (braid 7) is improved, and when the toothed belt 1 runs, Peeling of the protective layer 5 (braid 7) can be prevented. Moreover, the wear resistance of the tooth portion 2 can also be improved by performing adhesive treatment. By adhering the rubber composition constituting the rubber layer (teeth 2, back 4) to the protective layer 5 (braid 7) through the above adhesive treatment, the rubber composition of the rubber layer (teeth 2, back 4) is less likely to be exposed from the protective layer 5.

(Manufacture of toothed belt 1)
The toothed belt 1 of the present invention can be manufactured by a conventional method. For example, the toothed belt 1 shown in FIG. 1 can be manufactured by the following procedure.

First, a cylindrical assembly for forming the protective layer 5 on the outer peripheral surface of a cylindrical mold 90 (cylindrical mold or mold) having a plurality of grooves 91 (concave lines) corresponding to the teeth 2 of the toothed belt 1. Cover with object 7 (see Figure 5). Subsequently, the twisted cord constituting the core wire 3 is spirally wound around the outer peripheral surface of the covered cylindrical braid 7 at a predetermined pitch (a predetermined spinning pitch SP with respect to the axial direction of the cylindrical mold 90). Further, an unvulcanized rubber sheet 4A forming the back portion 4 and tooth portions 2 is wrapped around the outer circumferential side to form an unvulcanized belt molded body (unvulcanized laminate).

Next, while the unvulcanized belt molded body is placed around the outer periphery of the cylindrical mold 90, a rubber jacket serving as a vapor barrier material is placed over the outside of the cylindrical mold 90 (not shown). Subsequently, the jacketed belt molded body and the cylindrical mold 90 are housed inside a vulcanization device such as a vulcanization can. Then, when the belt molded body is heated and pressurized inside the vulcanizer, the rubber composition of the unvulcanized rubber sheet 4A and the cylindrical braid 7 are press-fitted into the groove 91 of the cylindrical mold 90, and a desired shape is formed. While the teeth 2 are formed, the rubber composition of the unvulcanized rubber sheet 4A is vulcanized, resulting in a sleeve-shaped vulcanized product in which the rubber composition, the cylindrical braid 7, and the core wire 3 are integrated. (vulcanized belt sleeve) is formed. At this time, the cylindrical braid 7 is expanded to follow the contour shape of the toothed portion 2, and serves as a protective layer 5 disposed on the surface of the toothed portion 2. Then, by cutting the vulcanized belt sleeve removed from the cylindrical mold 90 into a predetermined width, a plurality of toothed belts 1 are obtained.

Alternatively, the toothed belt 1 may be manufactured by the following procedure using a preforming method.
First, the cylindrical mold 90 having a plurality of grooves 91 (grooves) is sequentially covered with the cylindrical braid 7 and the unvulcanized rubber sheet 4B at a temperature at which the rubber composition softens (for example, 70 to 90°C). ℃), the rubber composition of the unvulcanized rubber sheet 4B and the cylindrical braid 7 are press-fitted into the grooves 91 (concave stripes) of the cylindrical mold 90 to form the teeth 2, and the preforming is performed. Get a body. Next, the core wire 3 is spirally spun on the outer peripheral surface of the obtained preform. Further, an unvulcanized rubber sheet 4C constituting the back portion 4 is wrapped around the outer peripheral surface of the belt to form an unvulcanized belt molded body (unvulcanized laminate).

Thereafter, a vulcanized molded body (vulcanized belt sleeve) is formed using the same procedure as the above-described manufacturing method. In addition, in this preforming method, since the tooth portion 2 is formed in advance before vulcanization, the unvulcanized rubber is lined up at a predetermined pitch (spinning pitch SP) from the back side to the tooth side during vulcanization. There is no need to flow or extrude through the gaps in the lines 3 to form the teeth 2. Therefore, it is possible to reduce the distance (pitch) between adjacent core wires.

In the above manufacturing method, the rubber composition and the cylindrical braid 7 are press-fitted into the groove 91 of the cylindrical mold 90 by heating and pressurizing, and the cylindrical braid 7 is formed into a shape that follows the contour shape of the tooth portion 2. In the process of stretching and disposing it on the surface of the tooth portion 2, if the elasticity of the tubular braid 7 constituting the protective layer 5 is small, press-fitting of the rubber composition into the groove portion 91 will be inhibited, and the desired result will not be obtained. The tooth shape is not sufficiently formed. Therefore, the protective layer 5 constituting the surface of the toothed portion 2, which is the meshing transmission surface, must have elasticity. Therefore, the braid 7 with high elasticity is suitable for the protective layer 5.

Further, in the above manufacturing method, the circumferential direction of the tubular braid 7 coincides with the longitudinal direction (circumferential direction) of the toothed belt 1. Therefore, as the rubber composition flows into the groove 91 of the cylindrical mold 90 to form a tooth shape, the cylindrical braid 7 expands in the circumferential direction, thereby providing an outline of the tooth 2 to be formed. placed on the surface along the shape. Therefore, it is preferable to use a composite thread, which is a stretchable thread having good stretchability, as the braided thread 71 that stretches in the circumferential direction.

Moreover, in this process, the shape-retaining threads of the braid 7 are melted or softened by heating, so that the elongation of the bulky textured threads proceeds without being inhibited by the shape-retaining threads. As a result, the braided yarn 71 is stretched, and a shape that follows the contour of the tooth portion 2 can be stably formed. That is, the shape-retaining thread functions as a melting thread that melts or softens through heat treatment, and contributes to maintaining the shape of the braid 7.

In addition, in this process, when a cloth with joints (seams) such as woven fabric is used as the protective layer 5, cracks at the joints and exposure of the rubber composition to the surface side ( oozing) and PLD instability due to overlapping parts are likely to occur. When a fabric having a structure with large gaps, such as a knitted fabric, is used as the protective layer 5, the rubber composition is likely to permeate between the threads of the protective layer 5 during vulcanization and be exposed on the surface side. In this respect, the braid 7 in which the braid threads 71 are closely arranged is suitable for the protective layer 5. Furthermore, it is preferable to reduce the thread spacing by adjusting the braiding pitch d, the number of braiding threads 71, and the total fineness of the braiding threads 71.

(Manufacturing method of toothed belt 1: direct molding method)
The cylindrical braid 7 is produced by combining only the braid 71 (combining three or more braid threads) on the outer periphery of the cylindrical mold 90 for manufacturing the toothed belt 1 instead of using the mandrel 9. Alternatively, it may be formed by combining the braided threads 71 and the axis threads 72 (combining three or more braided threads). In this case, the work of combining the braided threads 71 and the shaft threads 72 with each other on the outer periphery of the mandrel 9 is not performed, and the demolding work of extracting them from the mandrel 9 is not necessary. Therefore, it is not necessary to perform heat treatment on the formed braid 7. When assembling a braid on the outer periphery of the cylindrical mold 90 for manufacturing the toothed belt 1, the shape-retaining yarn with low elasticity carries the tension applied to the braid 71, thereby preventing the bulky textured yarn from stretching completely. , it is possible to prevent the gap between the threads of the braid 7 from widening. That is, the shape-retaining yarn functions as a tension-bearing member that bears the tension applied to the braided thread 71, and contributes to maintaining the shape of the braided fabric 7. Furthermore, when the braid 7 is assembled on the outer periphery of the cylindrical mold 90 for manufacturing the toothed belt 1, the state shown in FIG. The press-fitting, vulcanization treatment, and demolding treatment are the same as the method for manufacturing the toothed belt 1 described above. The method for manufacturing the cylindrical braid 7 and the toothed belt 1 described here will be referred to as a direct molding method in the examples described below.

Next, the toothed belts according to Examples 1 to 5, Comparative Examples 1 to 4, and Reference Examples 1 to 4, which will be explained below, were manufactured to improve the shape retention (shape stability) of the braid and the formation of toothed parts. The aspect and the exposure aspect (bleeding) of the rubber composition from the protective layer were evaluated.

(Materials used)
The materials of the braids constituting the braids of the toothed belts of Examples 1 to 5, Comparative Examples 1 to 4, and Reference Examples 1 to 4 are listed below (see Table 1).
Composite yarn: Polyurethane elastic yarn (core yarn) covered with nylon woolly processed yarn as the core yarn, and then covered with nylon woolly processed yarn to have a total fineness of 560 dtex (Shima Seiki Seisakusho Co., Ltd.) Composite yarn manufactured by SSUPY (registered trademark), hereinafter referred to as "composite yarn containing polyurethane elastic yarn and nylon woolly processed yarn")
Nylon yarn (filament yarn): Nylon 66 filament fiber bundle manufactured by Asahi Kasei Corporation, 940 dtex
Nylon woolly processed yarn: FORMOSA CHEMICALS & FIBRE CORPORATION nylon 6 woolly processed yarn, total fineness 440 dtex
Low melting point nylon thread A: Elder (registered trademark) manufactured by Toray Industries, Inc., fineness 330 dtex, melting point 110°C, softening point 60°C
Low melting point nylon thread B: Elder (registered trademark) manufactured by Toray Industries, Inc., fineness 78 dtex, melting point 110°C, softening point 60°C
Low-melting point nylon yarn C: Low-melting point nylon yarn made by combining 7 low-melting point nylon yarns B to have a total fineness of 546 dtex.Low-melting point nylon yarn D: Made by combining 10 low-melting point nylon yarns B to have a total fineness of 780 dtex. Low melting point nylon thread Cotton thread: 10s

(Example 1)
As a braided thread, a composite yarn (total fineness of 560 dtex) containing polyurethane elastic yarn, which is a bulky processed yarn, and a nylon woolly processed yarn, and a low-melting point nylon yarn A (fineness: 330 dtex), which is a shape-retaining yarn, are aligned. I used thread. The ratio of the fineness of the shape-retaining yarn to the total fineness of this one braided yarn (doubled yarn) was 37%.

In addition, the tubular braid and the toothed belt were produced using a heat treatment demolding method. The cylindrical braid was produced using a mandrel with a diameter of 36 mm and an outer circumferential length of 113 mm, with 32 threads, a braid pitch (d) of 4 mm, and a braid angle (θ) of 88°. Specifically, after a braid was assembled into a cylindrical shape on the outer periphery of a mandrel, the low melting point nylon thread A was melted or softened by heat treatment in which hot air at 120° C. was applied for 1 minute. Then, after naturally cooling for 10 minutes, the cylindrical braid was pulled out from the mandrel to produce a cylindrical braid.

Then, the produced cylindrical braid was placed over the outer periphery of a cylindrical mold for manufacturing a toothed belt, and the toothed belt was formed using the method for manufacturing a toothed belt described in the embodiment. A toothed belt (vulcanized belt sleeve) was manufactured.

(Example 2)
A composite yarn made by twisting the braided yarn into a composite yarn (total fineness of 560 dtex) containing polyurethane elastic yarn, which is a bulky processed yarn, and nylon woolly processed yarn, and low-melting point nylon yarn A (fineness: 330 dtex), which is a shape-retaining yarn. A toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 34, and circumferential length 102 mm was produced in the same manner as in Example 1, except for the following.

(Example 3)
Using the direct molding method of assembling braids around the outer periphery of a cylindrical mold (diameter 41 mm, outer circumference length 129 mm) for manufacturing toothed belts, 32 braided yarns were produced using a method similar to Example 1, with a braid pitch (d) of 9 mm. A cylindrical braid was prepared with a set angle (θ) of 86°, and a toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 44, and circumferential length 132 mm was produced.

(Example 4)
Except that low melting point nylon yarn B (fineness 78 dtex) was used as the shape-retaining thread constituting the braided thread, and the ratio of the fineness of the shape-retaining thread to the total fineness of one braided thread (doubled thread) was 12%. A toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 44, and circumferential length 132 mm was produced in the same manner as in Example 3.

(Example 5)
Except that low-melting point nylon thread C (fineness 546 dtex) was used as the shape-retaining thread constituting the braided thread, and the ratio of the fineness of the shape-retaining thread to the total fineness of one braided thread (doubled thread) was 49%. A toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 44, and circumferential length 132 mm was produced in the same manner as in Example 1.

(Comparative example 1)
A toothed belt (vulcanized belt sleeve) with a tooth pattern S3M, number of teeth 34, and circumference 102 mm was prepared in the same manner as in Example 1, except that the braided yarn was a nylon yarn (filament yarn) with a total fineness of 940 dtex. ) was created.

(Comparative example 2)
Example 1 except that the braided yarn was only a composite yarn (total fineness of 560 dtex) containing polyurethane elastic yarn, which is a bulky yarn, and nylon woolly yarn, and no shape-retaining yarn (low melting point nylon yarn) was used. A toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 34, and circumferential length 102 mm was produced in the same manner as described above.

(Comparative example 3)
Example 1 except that the braided yarn was a composite yarn (total fineness 560 dtex) containing polyurethane elastic yarn, which is a bulky yarn, and nylon woolly processed yarn, and a double yarn made of cotton yarn (fineness 10s). A toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 34, and circumferential length 102 mm was produced in the same manner as described above.

(Comparative example 4)
The braided thread is a doubling yarn made by aligning nylon woolly processed yarn (total fineness 440 dtex, not including polyurethane elastic yarn), which is a bulky processed yarn, and low melting point nylon yarn A (fineness 330 dtex), which is a shape-retaining yarn. Except for the above, a toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 34, and circumferential length 102 mm was produced in the same manner as in Example 1.

(Reference example 1)
A toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 34, and circumferential length 102 mm was produced in the same manner as in Example 1, except that the number of braided threads was reduced to 16.

(Reference example 2)
A toothed belt (vulcanized belt sleeve) having a tooth profile S3M, number of teeth 34, and circumferential length 102 mm was produced in the same manner as in Example 1, except that the assembly angle (θ) was 80°.

(Reference example 3)
Except that low-melting point nylon yarn B (fineness 78 dtex) was used as the shape-retaining yarn constituting the braided yarn, and the ratio of the fineness of the shape-retaining yarn to the total fineness of one braided yarn (doubled yarn) was 6.5%. In the same manner as in Example 1, a toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 34, and circumferential length 102 mm was manufactured.

(Reference example 4)
Except that low-melting point nylon yarn D (fineness 780 dtex) was used as the shape-retaining thread constituting the braided thread, and the ratio of the fineness of the shape-retaining thread to the total fineness of one braided thread (doubled thread) was 58%. A toothed belt (vulcanized belt sleeve) having a tooth pattern S3M, number of teeth 34, and circumferential length 102 mm was produced in the same manner as in Example 1.

(Evaluation of moldability)
Table 1 shows the shape retention of the plait (shape stability), formation of tooth portions, and rubber composition of the toothed belts produced in Examples 1 to 5, Comparative Examples 1 to 4, and Reference Examples 1 to 4. The evaluation results (evaluation of moldability) of exposure (bleeding) from the protective layer of the object are shown. In addition, evaluation of moldability was determined based on the following index.

(Indicator for evaluation of formability)
・Shape retention of braids (shape stability)
From the production of the tubular braid to the manufacture of the toothed belt, the case where the tubular braid maintains the desired form (the arrangement of the braided threads, the braid angle, etc.) is considered good (○). A case where it could not be held was determined to be defective (×).

・Formation of teeth In manufacturing toothed belts, the teeth of a desired shape are formed, and the tubular braid is shaped to follow the contour of the teeth, and the outermost surface has a texture of fibers (raised texture). ) remained and was placed on the surface of the tooth portion, it was judged as good (◯).
On the other hand, if the tooth part is not formed in the desired shape, or if the tubular braid is not placed on the surface of the tooth part (embedded in the rubber layer) even if the tooth part with the desired shape is formed, the tubular braid If the texture of the fibers (raised feel) does not remain even if the braid is placed on the surface of the tooth along the contour of the tooth (the texture of the fiber disappears due to melting and solidification of the shape-retaining thread), this is considered defective. It was judged as (×).

・Rubber exposure (bleeding)
A case in which the rubber composition permeated the tubular braid (protective layer) and was exposed on the outermost surface of the tooth portion was judged as poor (×), and a case in which there was no noticeable exposure was judged as good (◯).

(Evaluation results of comparative example)
The toothed belt of Comparative Example 1, which used nylon raw yarn that is not a bulky processed yarn as the braided yarn, had insufficient extensibility required when forming teeth by press-fitting, so it was difficult to form the desired tooth shape. The rubber composition penetrated through the protective layer and was exposed on the surface side.

The toothed belt of Comparative Example 2, in which only a composite yarn containing polyurethane elastic yarn and nylon woolly processed yarn was used as the braiding yarn, and no shape-retaining yarn (low-melting point nylon yarn) was used, was manufactured by applying tension to the composite yarn during the fabrication of the braid. was stretched and its extensibility was reduced, resulting in failure to form the desired tooth shape, and the rubber composition permeated through the protective layer and was exposed on the surface side.

In the toothed belt of Comparative Example 3, which uses a composite yarn containing polyurethane elastic yarn and nylon woolly processed yarn as a braided yarn, and a composite yarn with cotton yarn, the cotton yarn maintains the extensibility of the composite yarn as a tension-bearing member. Although the braid was successfully made, the cotton thread did not melt during the process of press-fitting the teeth of the toothed belt, which prevented the braid from stretching along the tooth shape. As a result, the desired tooth shape was not formed, resulting in defects, and furthermore, the rubber composition penetrated through the protective layer and was exposed on the surface side.

The toothed belt of Comparative Example 4, which used a yarn of nylon woolly processed yarn (not including polyurethane elastic yarn) as a braided yarn and low melting point nylon yarn A (fineness 330 dtex) as a shape-retaining yarn, had teeth formed by press-fitting. Because the extensibility required when forming the part was insufficient, the desired tooth shape was not formed, resulting in defects, and furthermore, the rubber composition permeated through the protective layer and was exposed on the surface side.

(Evaluation results of examples)
On the other hand, a composite yarn containing a polyurethane elastic yarn and a nylon woolly processed yarn and a low melting point nylon yarn A as a shape-retaining yarn were used as a braided yarn, and a composite yarn was prepared by a heat treatment demolding method. In the toothed belt of Example 1, the plait extended along the desired tooth shape, good tooth portions were formed, and there was no exposure due to penetration of the rubber composition from the protective layer to the surface side. In addition, the toothed belt of Example 1 had a good evaluation of "rubber exposure (oozing)", which indicates that the toothed belt is more effective in protecting the teeth than Comparative Examples 1 to 4. was confirmed.

In addition, the toothed yarn of Example 2 using a doubled yarn (mixed twisted yarn) obtained by twisting a composite yarn containing a polyurethane elastic yarn and a nylon woolly processed yarn as a braided yarn, and a low melting point nylon yarn A as a shape-retaining yarn. As in Example 1, the belt also had good toothed portions. Furthermore, since the toothed belt of Example 2 also had a good evaluation of "rubber exposure (oozing)", the effect of protecting the teeth of the toothed belt was higher than that of Comparative Examples 1 to 4. was confirmed.

In addition, in Examples 3 and 4, a composite yarn containing a polyurethane elastic yarn and a nylon woolly processed yarn and a low melting point nylon yarn as a shape-retaining yarn (low melting point nylon yarn A in Example 3, and nylon yarn A in Example 4) were used. When using a doubling yarn with low-melting point nylon yarn B), a toothed structure with good teeth can be formed as in Example 1 even by a direct molding method that does not require heat treatment on a mandrel or demolding. It was confirmed that belts could be manufactured. In addition, since the evaluation of "rubber exposure (oozing)" was good in Examples 3 and 4, the effect of protecting the teeth of the toothed belt was higher than in Comparative Examples 1 to 4. was confirmed.

In addition, in the toothed belt of Example 5, in which the ratio of the fineness of the shape-retaining yarn to the total fineness of one braided yarn (doubled yarn) was increased to 49% compared to the toothed belt of Example 1, A tooth portion as good as that in Example 1 was formed. In addition, since the toothed belt of Example 5 also had a good evaluation of "rubber exposure (bleeding)", the effect of protecting the teeth of the toothed belt was higher than that of Comparative Examples 1 to 4. was confirmed.

(Evaluation results of reference example)
Compared to the toothed belt of Example 1, in the toothed belt of Reference Example 1, in which the number of braided threads was reduced to 16 and the spacing between the threads was increased, the shape retention of the braid was In terms of the formation of the teeth and teeth, the results were as good as in Example 1. However, since the distance between adjacent threads was large, the rubber composition was observed to penetrate through the gap and be exposed (ooze) to the surface side. Therefore, the effect of protecting the tooth portion in Reference Example 1 was smaller than that in Example 1.

In contrast to the toothed belt of Example 1, in the toothed belt of Reference Example 2, in which the assembly angle (θ) was set to 80°, when forming the teeth by press-fitting, the shape retention of the braid and the formation of the teeth In terms of this, it was as good as Example 1. However, perhaps because the gaps between the intersecting threads became larger, some of the rubber composition was observed to penetrate through the gaps and be exposed (ooze) to the surface side. Therefore, in comparison with Example 1, Reference Example 2 had a smaller effect of protecting the tooth portion.

In contrast to the toothed belt of Example 1, in the toothed belt of Reference Example 3, the ratio of the fineness of the shape-retaining yarn to the total fineness of one braided yarn (doubled yarn) was reduced to 6.5%, the teeth were formed by press-fitting. When forming the part, the formation of the tooth part and the rubber exposure (bleeding) were as good as in Example 1. However, because the proportion of shape-retaining threads in the braided threads was small, there were some parts where the desired shape of the tubular braided braid was not maintained. Therefore, in comparison with Example 1, Reference Example 3 resulted in a braid lacking in shape retention (shape stability).

In contrast to the toothed belt of Example 1, in the toothed belt of Reference Example 4, the ratio of the fineness of the shape-retaining yarn to the total fineness of one braided yarn (doubled yarn) was increased to 58%, the teeth were formed by press-fitting. During formation, the braid was as good as Example 1 in terms of shape retention and rubber exposure (bleeding). However, even if the tubular braid is placed on the surface of the tooth along the contour of the tooth, since the proportion of shape-retaining thread in the braid is high, the melting and solidification of the shape-retaining thread may cause the texture of the fibers to change. (the feeling of napping) seemed to be disappearing. Therefore, in comparison with Example 1, Reference Example 4 lacked the effects of fibers (protection of teeth, surface friction coefficient, etc.) in the formation of teeth.

1 Toothed belt 2 Tooth portion 3 Core wire 4 Back portion 5 Protective layer 7 Braid (cylindrical braid)
71 Braid thread 72 Axial thread 90 Cylindrical mold 91 Groove

Claims (12)

The belt has a plurality of teeth arranged at predetermined intervals in the longitudinal direction,
The surface of the tooth portion is composed of a braid formed by combining three or more braid threads,
The toothed belt is characterized in that the braided yarn is made of a thread obtained by combining a bulky processed yarn and a shape-retaining yarn having lower elasticity than the bulky processed yarn. The toothed belt according to claim 1, wherein the shape-retaining thread is thermoplastic. The toothed belt according to claim 2, wherein the shape-retaining thread has a melting point of 100°C or more and 180°C or less. The toothed belt according to any one of claims 1 to 3, wherein the braid is a seamless tubular braid. The toothed belt according to any one of claims 1 to 4, wherein the braid includes 30 or more braided threads. 6. The intersecting braided yarns of the braid have a braiding angle in a range of 85° or more and 89° or less with respect to the belt width direction. toothed belt. Any one of claims 1 to 6, characterized in that the proportion of the fineness of the shape-retaining yarn to the total fineness of the bulky processed yarn and the shape-retaining yarn of the braided yarn is 10% or more and 50% or less. The toothed belt according to item 1. The toothed belt according to any one of claims 1 to 7, wherein the bulky processed yarn is a composite yarn containing two or more types of yarn. The toothed belt according to claim 8, wherein the composite yarn includes a polyurethane elastic yarn and a woolly processed polyamide (nylon) yarn. A method for manufacturing a toothed belt according to any one of claims 1 to 9,
Arranging the cylindrical braid on the outer periphery of a cylindrical mold whose outer periphery is provided with tooth grooves corresponding to the teeth of the toothed belt, further arranging the belt molded body on the outside in the radial direction, By pressing the belt molded body from the outer peripheral side toward the inside in the radial direction, the braid is press-fitted together with the belt molded body into the tooth groove, and as the tooth portion is formed, the belt molded body is pressed along the surface of the tooth portion. A method for manufacturing a toothed belt, characterized by arranging braids. Forming the seamless cylindrical braid by combining three or more of the braided threads including the thermoplastic shape-retaining threads on the outer periphery of the mandrel;
11. The method for manufacturing a toothed belt according to claim 10, wherein the formed braid is heat-treated at a first predetermined temperature for a predetermined time and then cooled to a second predetermined temperature. 11. The method for manufacturing a toothed belt according to claim 10, wherein the braid is formed by combining three or more of the braided yarns on the outer periphery of the cylindrical mold.

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