JP6747912B2 - Weight roller and manufacturing method thereof - Google Patents

Description

The technique disclosed in the present specification relates to a weight roller used in a continuously variable transmission and the like, and a manufacturing method thereof.

BACKGROUND ART Motorcycles and the like use a continuously variable transmission that automatically shifts gears in accordance with the engine speed. The continuously variable transmission includes a pulley having a fixed plate and a movable plate, a V-belt wound around the pulley, and a guide plate fixed to the rotary shaft on the back side of the movable plate. A cylindrical weight roller arranged so as to be movable in the radial direction of the pulley is provided in the gap between the guide plate and the movable plate.

The gap between the guide plate and the movable plate becomes narrower toward the outside in the radial direction of the pulley. When the engine speed increases and the centrifugal force applied to the weight roller increases, the weight roller moves to the outside in the radial direction of the pulley. .. With this movement, the back surface of the movable plate is pushed by the weight roller, and the width of the V-shaped groove formed by the movable plate and the fixed plate becomes narrow. As a result, the winding radius of the V-belt around the pulley is increased, and stepless speed change is performed.

Patent Literatures 1 to 3 describe conventional weight rollers. The conventional weight roller includes, for example, a weight adjusting member made of metal and a resin covering member that covers the outer surface of the weight adjusting member.

JP-A-2000-55154 JP-A-8-14346 JP 9-42396 A

By the way, for example, the weight roller described in Patent Document 1 is formed by separately manufacturing the weight adjusting member and the covering member, and then press-fitting the weight adjusting member into the covering member. On the other hand, by forming the covering member that covers the weight adjusting member by insert molding, the press-fitting step can be omitted and the manufacturing cost can be reduced.

However, in the weight roller manufactured by insert molding, stress tends to concentrate on the portion of the covering member that covers the corner portion of the weight adjusting member due to a rapid temperature change (that is, heat shock). Breakage and cracks are more likely to occur as compared with the weight roller.

It is considered that the possibility of breaking and cracking can be reduced by mixing the reinforcing fiber into the covering member, but if a large amount of expensive reinforcing fiber is used, the production cost may be increased. ..

On the other hand, since the weight roller slides on the movable plate and the guide plate, it is desired to have excellent wear resistance.

The present invention has been made in view of the above points, and an object of the present invention is to provide a weight roller provided with a covering member that is less likely to be broken or cracked by heat shock and has excellent wear resistance at an appropriate manufacturing cost.

The weight roller disclosed in the present specification is a cylindrical weight roller including a cylindrical weight adjusting member and a covering member provided on the outer peripheral surface of the weight adjusting member. The covering member is made of a resin composition containing polyamide as a base resin, and contains 2.5% by mass or more and less than 7% by mass of inorganic fibers having a tensile elastic modulus of 100 GPa or more and 650 GPa or less and a tensile elastic modulus of 7 GPa or more and 110 GPa or less. The following organic fibers may be contained in an amount of 1% by mass or more and 7% by mass or less, and a lubricant in a content of 12% by mass or more and 20% by mass or less.

According to this configuration, the polyamide which is the base resin, the inorganic fiber and the organic fiber are added together as the reinforcing fiber, so that the amount used is smaller than that when the inorganic fiber and the organic fiber are added individually. Thus, it is possible to effectively suppress the occurrence of cracks and the like due to heat shock. Further, by setting the lubricant to 12% by mass or more and 20% by mass or less, it is possible to significantly improve the wear resistance of the covering member that comes into contact with the movable plate or the guide plate during use while ensuring sufficient strength. ..

The weight roller disclosed in the present specification is provided with a coating member that is not easily broken or cracked by heat shock and has excellent wear resistance. Further, the weight roller can be manufactured at an appropriate manufacturing cost.

FIG. 1 is a diagram showing a weight roller disclosed in the present specification. FIG. 2 is a diagram showing a modification of the weight roller disclosed in this specification. FIG. 3 is a cross-sectional view showing a method for manufacturing the weight roller shown in FIG. FIG. 4 is a cross-sectional view showing a method for manufacturing the weight roller shown in FIG. FIG. 5 is a sectional view showing a part of a continuously variable transmission using the weight roller disclosed in this specification. FIG. 6 is a diagram for explaining a friction and wear test of resin. FIG. 7 is a diagram showing the relationship between the PTFE content (blending ratio) in the resin composition and the specific wear amount based on the results shown in Table 3. 8: is a figure which shows the measurement result of the dimensional change rate described in Table 4. FIG. 9: is a figure which shows the measurement result of the dimensional change rate described in Table 5. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification, for convenience of description, in the cylindrical weight roller, an end face side on which a gate mark is formed may be referred to as a bottom portion or a lower portion, and the other end face side may be referred to as an upper portion.

(Embodiment)
-Structure of weight roller-
FIG. 1 is a diagram showing a weight roller 1 disclosed in this specification. The left view of FIG. 1 is a cross-sectional view in a direction parallel to the axis of the weight roller 1, and the right view of FIG. 1 is a plan view of the weight roller 1 seen from the bottom surface side.

As shown in FIG. 1, the weight roller 1 of the present embodiment includes a cylindrical weight adjusting member 3 and a covering member 5 made of a resin composition and provided on the outer peripheral surface 7 of the weight adjusting member 3, Has a cylindrical shape. The covering member 5 covers not only the outer peripheral surface 7 of the weight adjusting member 3 but also the bottom surface of the weight adjusting member 3 and at least a part of the upper surface thereof for the purpose of preventing the weight adjusting member 3 from falling off from the covering member 5. May be covered. The covering member 5 may have a bottomed tubular shape, and a circular disc gate mark 11 in a plan view may be formed in the center of the bottom portion thereof.

The covering member 5 is formed by disc gate type insert molding, and the covering member 5 is in close contact with the weight adjusting member 3 in a region extending from a part of the upper surface of the weight adjusting member 3 to the outer peripheral surface 7 and a part of the lower surface. doing. The thickness of the portion of the covering member 5 that covers the outer peripheral surface of the weight adjusting member 3 is substantially uniform except for the upper and lower ends, and the thickness is, for example, about 1.5 mm or more and 2.5 mm or less. Good. If the thickness of the covering member 5 is too small, breakage or cracks easily occur due to heat shock, and if the thickness of the covering member 5 is too large, the manufacturing cost increases.

The resin composition forming the covering member 5 preferably has a self-lubricating property. “Having self-lubricating property” means that the coefficient of friction is small. Since the resin composition has self-lubricating properties, it is possible to reduce the amount of wear when sliding on a member made of metal. The resin composition constituting the covering member 5 has a specific wear amount of 0.5 (10 ⁻³ mm ³ /(N·km)) measured by, for example, a thrust cylinder type friction wear test (JIS K 7218-1986). ) The following materials are preferably used.

The resin constituting the coating member 5 is, for example, polyamide as a base resin, inorganic fiber is 2.5% by mass or more and less than 7% by mass, organic fiber is 1% by mass or more and 7% by mass or less, and lubricant is 12% by mass or more and 20% by mass or more. The content of each is less than or equal to mass %.

Polyamide has excellent toughness, impact resistance, and flexibility, and has a high affinity with reinforcing fibers such as inorganic fibers and organic fibers, and thus is preferably used as a base resin. As the polyamide, for example, condensation polymerization type nylon 66, nylon 46, nylon 610, nylon 9T, nylon 10T, ring opening polymerization type nylon 6, nylon 11, nylon 12, etc. can be used. Not limited. Also, a blend of a plurality of polyamides may be used as the base resin.

Of polyamides, aliphatic nylons such as nylon 66 and nylon 46 have excellent heat resistance, toughness, and self-lubricating properties, and thus have excellent wear resistance. Therefore, nylon 66 and nylon 46 are more preferably used as the base resin. Nylon 66 is more preferably used as a base resin because it has lower water absorption than nylon 46, has a small dimensional change due to water absorption, and is inexpensive.

The content of the polyamide in the covering member 5 may be at least 66 mass% or more, and may be the highest among the constituent materials of the resin composition.

Further, in the resin composition constituting the covering member 5, the content of the inorganic fibers when the content of the base resin is 100% may be, for example, 3% or more and 10% or less.

As the inorganic fiber, for example, a linear fiber having a tensile elastic modulus of 100 Gpa or more and 650 Gpa or less is used. Examples of inorganic fibers include carbon fibers, glass fibers, basalt fibers, and the like, and mixtures thereof. Of these, carbon fibers and glass fibers are preferably used because of their excellent heat resistance. Carbon fiber is more preferably used as the reinforcing fiber of the covering member 5 because it has excellent strength and rigidity, and its mechanical properties do not easily deteriorate even at high temperatures.

Although the type of glass fiber is not particularly limited, for example, E glass (aluminoborosilicate glass) and S glass (magnesium aluminosilicate glass) have high tensile elastic modulus and excellent heat resistance, and therefore, they are used as reinforcing fibers. It is preferably used.

The carbon fiber may be either a polyacrylonitrile (PAN)-based carbon fiber or a pitch-based carbon fiber, or may be a combination of these carbon fibers. Among these carbon fibers, PAN-based carbon fibers are preferably used because of their high strength and high elastic modulus. The tensile elastic modulus of the carbon fiber is preferably 100 GPa or more, for example, and more preferably 200 GPa or more because damage to the covering member 5 can be prevented even with a small amount. Such a carbon fiber may have a tensile strength of, for example, 1.0 Gpa or more, and more preferably 2.5 Gpa or more.

The diameter and length of the inorganic fibers in the covering member 5 are not particularly limited, but the diameter of the inorganic fibers may be, for example, 5 μm or more and 18 μm or less.

In addition, in the resin composition forming the covering member 5, the content of the organic fibers when the content of the base resin is 100% may be, for example, 1% or more and 10% or less.

As the organic fiber, for example, a fiber having a tensile elastic modulus of 7 Gpa or more and 110 Gpa or less is used. Examples of the organic fiber include various fibers such as aromatic polyamide fiber (aramid fiber), ultra high molecular weight polyethylene fiber, polyarylate fiber, PBO (polyparaphenylene benzobisoxazal) fiber, and two or more kinds thereof. Mixed fibers can be used.

Among these organic fibers, a para-type or meta-type aromatic polyamide fiber (aramid fiber) having high heat resistance and excellent strength is preferably used as the reinforcing fiber. Examples of the material of the para-aramid fiber include copolyparaphenylene-3,4′oxydiphenylene terephthalamide and polyparaphenylene terephthalamide (PPTA), and examples of the meta-aramid fiber include polymetaphenylene isophthalamide ( MPIA) is used. Among the above aramid fiber materials, copolyparaphenylene-3,4'oxydiphenylene terephthalamide and PPTA are preferably used from the viewpoint of excellent physical properties. The PPTA fiber has a high tensile elastic modulus of 72 GPa and a high tensile strength of 2950 MPa, does not easily expand and contract, and is inexpensive, so that it is more preferably used as a reinforcing fiber used together with the inorganic fiber.

In addition, as the organic fiber, a fiber obtained by mixing two or more of the above fibers may be used.

In the covering member 5, since the organic fibers are flexible, most of them have a bent portion at least in part. Therefore, as will be described later, most of the organic fibers are entangled with the inorganic fibers in the covering member 5, and even if the content ratio of the fibers is reduced as compared with the case where the inorganic fibers and the organic fibers are used alone. It is considered that the occurrence of cracks can be reduced.

The diameter and length of the organic fiber in the covering member 5 are not particularly limited, but the diameter of the organic fiber may be, for example, about 10 to 16 μm, and the length of the organic fiber is, for example, about 1 mm or more and 3.5 mm or less. May be. When the length of the organic fiber is 1 mm or more, it is easy to entangle with the inorganic fiber, and when the length of the organic fiber is 3.5 mm or less, kneading is easy, which is preferable. When the length of the organic fiber is 1 mm, it is more preferable in terms of workability.

Since the above-mentioned inorganic fibers are easily broken at the time of kneading the resin composition or when injecting the resin composition into the mold, the fiber length thereof is short in the covering member 5 after molding. On the other hand, since the organic fibers are less likely to be broken, the fiber length when added to the resin in the covering member 5 is maintained almost unchanged.

Wear resistance by fixing the content rate of the inorganic fibers in the resin composition constituting the covering member 5 to, for example, 3 mass% and increasing the content rate of the organic fibers within the range of 1 mass% to 7 mass %. Can be improved. Further, the heat shock resistance can be improved by fixing the content rate of the organic fiber to, for example, 2 mass% and increasing the content rate of the inorganic fiber within the range of 2.5 mass% to 7.0 mass %. it can.

Further, the sum of the content rate of the inorganic fibers and the content rate of the organic fibers in the resin composition constituting the covering member 5 may be 3.5% by mass or more and 8% by mass or less, and 3% by mass or more and 5% by mass or more. It may be less than or equal to mass %. If the sum of the content rate of the inorganic fiber and the content rate of the organic fiber is 3.5% by mass or more, the occurrence of cracks and the like can be suppressed even when the PTFE is set to a sufficiently high value of 14% by mass. When the sum of the content rates is 8.0 mass% or less, an increase in cost can be suppressed. When the sum of the above content rates is 5.0% by mass or less, the cost can be further reduced, which is preferable.

As the lubricant, for example, in addition to a liquid type, a fluorine-based lubricant such as polytetrafluoroethylene (PTFE), a solid type lubricant such as graphite, molybdenum disulfide, and boron nitride, and two types of these lubricants A mixture of the above can be used. The lubricant may be contained in the coating member 5 in a particulate and dispersed state. If a liquid lubricant is used, it may exude from the resin surface and cause abrasion powder to adhere. However, if a granular lubricant is used, the abrasion powder will be less likely to adhere and abnormal wear will be less likely to occur. it can. It should be noted that these lubricants impart self-lubricating properties to the resin forming the covering member 5.

The weight adjusting member 3 may be made of a material having a larger specific gravity than the covering member 5, and is made of, for example, a metal such as free cutting steel (SUM22, 23) or carbon steel wire for cold heading (SWCH). May be. The inner diameter and the outer diameter of the weight adjusting member 3 may be arbitrarily adjusted.

FIG. 2 is a diagram showing a modification of the weight roller 1 disclosed in this specification. The left diagram of FIG. 2 is a cross-sectional view in a direction parallel to the axis of the weight roller 1, and the right diagram of FIG. 2 is a plan view of the weight roller 1 seen from the bottom side.

As shown in FIG. 2, in the weight roller 1, the covering member 5 is provided so as to cover the region extending from the outer peripheral surface 7 of the weight adjusting member 3 to the upper and lower corner portions. The covering member 5 does not need to cover the entire bottom surface of the weight adjusting member 3, and may cover only a part of the bottom surface of the weight adjusting member 3. A gate trace 13 of a pin gate is formed on the outer peripheral edge of the bottom of the covering member 5.

-Effect of weight roller-
Since the weight roller 1 formed by insert molding as shown in FIGS. 1 and 2 can cover at least a part of each of the upper surface and the lower surface of the weight adjusting member 3, the weight roller formed by the press-fitting process can be used. In comparison, the weight adjusting member 3 is less likely to fall off the covering member 5. However, since the covering member 5 is repeatedly contracted and expanded in the axial direction and the radial direction in a state where the covering member 5 is in close contact with the weight adjusting member 3 due to a heat shock, the covering members 5 are covered with the portions 10a and 10b covering the corners of the weight adjusting member 3. Is subject to strong stress. Therefore, if the content of the inorganic fibers in the covering member 5 is low, cracks and breaks along the radial direction may occur in the portions 10a and 10b when actually used.

Here, according to an independent study by the inventors of the present application, when polyamide is used as a base resin and the covering member 5 is made of a resin that does not contain a lubricant, if the inorganic fiber alone contains 7% by mass or more, cracks and fractures occur. It has been found that it is possible to suppress the occurrence of. However, since inorganic fibers such as carbon fibers are expensive, if the content of the inorganic fibers is too high, the manufacturing cost will increase.

Furthermore, it has been found that when a lubricant such as a fluorine-based resin is added to the covering member 5 in order to improve the wear resistance of the weight roller, cracks and fractures are more likely to occur. It has also been found that when an organic fiber such as aramid fiber is used alone, the occurrence of cracks cannot be sufficiently suppressed even if the content rate of the fiber is increased.

Based on the above findings, as a result of repeated studies by the inventors of the present application, when polyamide is used as the base resin and the covering member 5 is made of a resin containing a lubricant, the tensile elastic modulus is 100 Gpa or more and 650 Gpa or less, and inorganic fibers, It has been clarified that the addition amount of the organic fiber having the tensile elastic modulus of 7 Gpa or more and 110 Gpa or less together can effectively reduce the amount of the inorganic fiber used while suppressing the occurrence of cracks due to heat shock. It is estimated that this is because the inorganic fiber and the organic fiber having the bent portion are entangled in the covering member 5 to form a fiber network.

The tensile elastic modulus of the inorganic fiber (for example, carbon fiber) is measured by the method based on JIS R7606, and the tensile elastic modulus of the organic fiber (for example, aramid fiber) is measured by the method based on JIS L1017.

In the weight roller 1 of the present embodiment, in the resin forming the covering member 5, the content ratio of the inorganic fiber is 2.5% by mass or more and less than 7% by mass, and the organic fiber is 1% by mass or more and 7% by mass or less. By imparting the self-lubricating property, it becomes possible to effectively reduce the occurrence of cracks and fractures while reducing the amount of inorganic fibers used and reducing the manufacturing cost. It is more preferable that the content of the inorganic fibers is 3% by mass or more, since the occurrence of cracks can be more reliably reduced.

In addition, by setting the content of the lubricant in the resin composition constituting the covering member 5 to be 12% by mass or more and 20% by mass or less, abrasion resistance is significantly improved, and cracks due to addition of the lubricant are prevented. It is possible to suppress the occurrence.

It is more preferable that the content of the inorganic fibers in the resin composition forming the covering member 5 is 2.5% by mass or more and 3.0% by mass or less because the cost of the inorganic fibers can be more effectively reduced. Further, if the content of the inorganic fibers is at least 2.5% by mass, it is possible to reduce the dimensional change when the covering member 5 absorbs water. Therefore, even in a high humidity environment, the weight roller 1 of the weight roller 1 is prevented. A smooth operation can be realized.

Further, it is more preferable that the content rate of the organic fibers in the resin composition forming the covering member 5 is 1.0% by mass or more and 2.0% by mass or less. By setting the content rate of the organic fiber within this range, it is possible to suppress the amount of the organic fiber used and suppress the occurrence of cracks or breakage due to heat shock.

When the content of the lubricant in the resin composition constituting the covering member 5 is 12% by mass or more and 14% by mass or less, it is possible to significantly improve wear resistance and make cracks and the like less likely to occur.

According to the study by the inventor, it has been found that the length of the inorganic fiber used for manufacturing the covering member 5 does not significantly affect the heat shock resistance of the covering member 5. Further, the length of the organic fiber used for manufacturing the covering member 5 does not significantly affect the heat shock resistance of the covering member 5.

-Manufacturing method of weight roller-
FIG. 3 is a cross-sectional view showing a method of manufacturing the weight roller 1 shown in FIG. The weight roller 1 of this embodiment is manufactured by the insert molding method.

When manufacturing the weight roller 1 of the present embodiment, first, the cylindrical weight adjusting member 3 made of metal is manufactured by a known molding method or the like using a separate mold. On the other hand, the polyamide resin material (resin 31) to which the above-mentioned inorganic fibers, organic fibers and lubricant are added so as to have a predetermined content rate is kneaded so that the fibers and the lubricant are uniformly mixed. The weight adjusting member 3 is formed into a desired shape by forging using a die or cutting.

Next, the weight adjusting member 3 is installed in the cylindrical cavity formed by the first mold 27 having the recess formed therein and the cylindrical core pin 21 installed at the center of the recess, and the runner 25 is installed. The cavity is covered with the second mold 29 in which is formed. The disk gate 23 is provided in the center of the recess. 3, reference numeral 37 indicates the inner diameter of the weight adjusting member 3, reference numeral 35 indicates the diameter of the core pin 21, and reference numeral 33 indicates the difference (that is, clearance) between the inner diameter 37 of the weight adjusting member 3 and the diameter 35 of the core pin 21. Show.

In this state, the heated liquid resin 31 is injected into the cavity via the runner 25 and the disc gate 23. After the mold is cooled and the resin 31 is solidified, the second mold 29 is opened and the formed weight roller 1 is taken out from the first mold 27. The temperatures of the first mold 27 and the second mold 29 when the resin 31 is injected are determined by the base resin. For example, when nylon 66 or nylon 46 is used as the base resin, the mold temperature is about 80°C to 90°C.

According to the above method, since the resin 31 is injected from the disk gate 23 provided at the center of the cavity end face, the weight adjusting member 3 is centered by the flow 40 of the resin 31 from the center of the cavity end face to the peripheral portion. It Therefore, the variation of the clearance 33 depending on the position is reduced, and the positional deviation between the central axis of the weight adjusting member 3 and the central axis of the core pin 21 can be reduced.

However, the weight roller 1 may be manufactured using a pin gate type mold as shown in FIG.

In this case, the runners 43 and the pin gates 45 of the second mold 41 that cover the recesses of the first mold 27 are provided at positions corresponding to the peripheral portion of the cavity end face, and the resin 39 passes through the pin gates 45. Is injected into the cavity. By this method, the weight roller 1 according to the modified example shown in FIG. 2 can be manufactured.

-How to use the weight roller 1-
FIG. 5 is a sectional view showing a part of a continuously variable transmission using the weight roller 1. This continuously variable transmission includes a pulley 55 that rotates about a rotary shaft 61, a V belt 59 wound around a V-shaped groove of the pulley 55, a weight roller 1, and a guide plate 57. The pulley 55 is composed of a fixed plate 51 fixed to the rotary shaft 61 and a movable plate 53 that is movable in the axial direction of the rotary shaft 61.

The substantially disc-shaped guide plate 57 is fixed to the rotary shaft 61 on the rear surface side of the movable plate 53 with a gap between which the weight roller 1 can be held. The gap between the movable plate 53 and the guide plate 57 becomes narrower toward the radially outer side of the pulley 55.

In this continuously variable transmission, when the rotation speed of the engine coupled to the rotary shaft 61 increases, the weight roller 1 moves radially outward of the pulley 55. Then, the movable plate 53 pushed by the weight roller 1 moves in the direction in which the groove width of the pulley 55 becomes narrower. As a result, the winding radius of the V-belt 59 becomes large, and stepless speed change is performed.

Although the weight roller 1 and an example of the manufacturing method thereof and a method of using the weight roller 1 have been described above, the shapes, configurations, arrangements, constituent materials, sizes, manufacturing conditions, and before and after of each member deviate from the spirit of the present invention. It can be changed as appropriate within the range not to do.

For example, by forming a concave portion or a convex portion that extends in the circumferential direction on the outer peripheral surface of the weight adjusting member 3 and forming a convex portion or a concave portion that fits the concave portion or the convex portion on the inner peripheral surface of the covering member 5, Expansion and contraction due to heat may be suppressed to improve heat shock resistance.

Further, the mold temperature during molding is increased to improve the material properties, and residual stress is removed by applying thermal annealing at, for example, about 150° C. for a predetermined time after molding, and the heat shock resistance of the covering member 5 is improved. You may plan.

The results obtained by actually manufacturing the weight rollers according to Examples or Comparative Examples described later and evaluating them by the heat cycle test and the friction wear test will be described below. The present invention is not limitedly interpreted by these examples.

-Production of weight roller-
The weight rollers according to Examples 1 to 10 and the weight rollers according to Comparative Examples 1 to 19, 21, and 23 were manufactured according to the above-described disk gate method or pin gate method manufacturing method. Specifically, the weight rollers according to Examples 1 and 2 and Comparative Examples 1 to 3 were manufactured by a pin gate method, and the weight rollers according to Examples 3 to 10 and Comparative Examples 4 to 19, 21 and 23 were manufactured by a disk gate method. The mold temperature during molding was 90° C. in all cases.

The weight rollers according to Comparative Examples 20 and 22 were formed by molding the covering member using a mold and then press-fitting the weight adjusting member into the covering member.

The outer diameter of the weight rollers according to Examples 5 to 7 and Comparative Examples 8 to 13, 20, and 21 was 18 mm, and the height was 14 mm. The outer diameters of the weight rollers according to Examples 8 to 10 and Comparative Examples 14 to 19, 22, and 23 were 20 mm, and the height was 15 mm.

The material for the weight adjusting member was free-cutting steel (SUM22, 23) in each of the examples and comparative examples. The composition of the resin forming the covering member was changed for each of Examples and Comparative Examples as described later. In the following Examples and Comparative Examples, a resin material mixed with carbon fibers and/or PTFE, a resin material mixed with aramid fibers, etc., so that the content ratios of carbon fibers, aramid fibers, etc. are as follows: Was dry-blended and then molded to form a covering member.

<Example 1>
Nylon 46 (expressed as “PA46” in the following table) was used as the base resin, and carbon fiber (expressed as “CF” in the table below) was used as the inorganic fiber.

As the organic fiber, a cut fiber of 1 mm long para-aramid fiber (manufactured by Teijin Ltd., trade name "Technora") was used. The aramid fiber is made of copolyparaphenylene-3,4'oxydiphenylene terephthalamide, and has a tensile elastic modulus of 73.5 GPa and a tensile strength of 3400 MPa. The tensile elastic modulus of the organic fiber is a value measured by a method according to JIS L1017.

The carbon fiber content was 3.1% by mass of the entire resin composition, and the organic fiber content was 2.4% of the entire resin composition.

As the lubricant, 15.4% by mass of PTFE based on the whole resin composition was used.

<Example 2>
Nylon 46 was used as the base resin and glass fiber (indicated as “GF” in the table below) was used as the inorganic fiber. As the organic fiber, a cut fiber of 1 mm long aramid fiber (manufactured by Teijin Ltd., trade name "Technora") was used.

The glass fiber content was 5.0% by mass of the total resin, and the aramid fiber content was 6.3% by mass of the entire resin.

As the lubricant, 13.5% by mass of PTFE of the whole resin was used.

<Example 3>
Nylon 46 was used as the base resin and carbon fiber was used as the inorganic fiber. As the organic fiber, a cut fiber of 1 mm long aramid fiber (manufactured by Teijin Ltd., trade name "Technora") was used.

The carbon fiber content was 3.0% by mass of the entire resin, and the aramid fiber content was 2.1% by mass of the entire resin.

As the lubricant, 13.8% by mass of PTFE and 0.7% by mass of polyethylene based on the whole resin were used.

<Example 4>
Nylon 46 was used as the base resin and carbon fiber was used as the inorganic fiber. As the organic fiber, a cut fiber of 1 mm long aramid fiber (manufactured by Teijin Ltd., trade name "Technora") was used.

The carbon fiber content was 3.0% by mass of the entire resin, and the aramid fiber content was 2.4% by mass of the entire resin.

As the lubricant, PTFE of 15.4 mass% and polyethylene of 0.8 mass% of the whole resin were used.

<Example 5>
Nylon 66 (manufactured by BASF, trade name “ULTRAMID A3W”; described as “PA66” in the table below) was used as the base resin, and carbon fiber was used as the inorganic fiber. The base resin has a melting point of 260° C., 23° C., and a water absorption rate of 2.50 to 3.10% under a humidity of 50%.

As the organic fiber, a cut fiber of 1 mm long para-aramid fiber (manufactured by Teijin Ltd., trade name “Twaron 1684”) was used. This aramid fiber is made of PPTA and has a tensile elastic modulus of 72 GPa and a tensile strength of 2950 MPa.

The carbon fiber content was 3.0% by mass of the entire resin, and the aramid fiber content was 2.0% by mass of the entire resin. As the lubricant, 12.0% by mass of the total resin, PTFE (manufactured by Solvay Specialty Polymers, trade name “Polymist F284”) was used.

In the weight rollers according to Examples 6 to 10, the type and content of the fibers used are the same as those of the weight roller according to Example 5, but the content of PTFE as a lubricant is different.

<Example 6>
In the resin composition used for molding, the carbon fiber content was 3.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 13.0% by mass.

<Example 7>
In the resin composition used for molding, the carbon fiber content was 3.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 14.0% by mass.

<Example 8>
In the resin composition used for molding, the carbon fiber content was 3.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 12.0% by mass.

<Example 9>
In the resin composition used for molding, the carbon fiber content was 3.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 13.0% by mass.

<Example 10>
In the resin composition used for molding, the carbon fiber content was 3.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 14.0% by mass.

<Comparative Example 1>
Nylon 66 was used as the base resin and carbon fiber was used as the inorganic fiber. The content of carbon fibers in the resin composition used for molding was 3.0% by mass. No organic fibers or lubricants were used.

<Comparative example 2>
Nylon 66 was used as the base resin and carbon fiber was used as the inorganic fiber. The carbon fiber content in the resin composition used for molding was 7.0 mass %. No organic fibers or lubricants were used.

<Comparative example 3>
Nylon 46 was used as the base resin, and 1 mm long para-aramid fiber (manufactured by Teijin Ltd., trade name "Technora") cut fiber was used as the organic fiber. The content of aramid fibers in the resin composition used for molding was 7.0% by mass. As the lubricant, 15.0% by mass of PTFE was used. No inorganic fiber was used.

<Comparative example 4>
Nylon 66 was used as the base resin and carbon fiber was used as the inorganic fiber. The content of carbon fibers in the resin composition used for molding was 3.1% by mass. As the lubricant, 8.0% by mass of PTFE was used. No organic fiber was used.

<Comparative Example 5>
Nylon 66 was used as the base resin and carbon fiber was used as the inorganic fiber. The carbon fiber content in the resin composition used for molding was 7.0 mass %. As the lubricant, 5.4 mass% PTFE was used. No organic fiber was used.

<Comparative example 6>
Nylon 46 was used as the base resin, and para-aramid fiber having a length of 1 mm (manufactured by Teijin Ltd., trade name “Technora”) was used as the organic fiber. The content of aramid fibers in the resin composition used for molding was 7.0% by mass. As the lubricant, 15.0% by mass of PTFE was used. No inorganic fiber was used.

<Comparative Example 7>
Nylon 66 was used as the base resin, and para-aramid fiber having a length of 1 mm (trade name “Technora” manufactured by Teijin Ltd.) was used as the organic fiber. The content of aramid fibers in the resin composition used for molding was 3.0% by mass. As the lubricant, 10.0% by mass of PTFE was used. No inorganic fiber was used.

<Comparative Example 8>
Nylon 66 was used as the base resin, and carbon fiber was used as the inorganic fiber. As the organic fiber, a cut fiber of 1 mm long para-aramid fiber (manufactured by Teijin Ltd., trade name “Twaron 1684”) was used.

The carbon fiber content was 1.0% by mass of the entire resin, and the aramid fiber content was 2.0% by mass of the entire resin. As the lubricant, 14.0% by mass of PTFE of the whole resin was used.

In the weight rollers according to Comparative Examples 9 to 19, similarly to the weight roller according to Comparative Example 8, the base resin was nylon 66, and 2% by mass of Twaron 1684 was used as the aramid fiber. In the weight rollers according to Comparative Examples 9 to 19, the same carbon fiber as that used in Comparative Example 8 was used, and the same PTFE was used as the lubricant.

<Comparative Example 9>
In the resin composition used for molding, the carbon fiber content was 2.0 mass %, the aramid fiber content was 2.0 mass %, and the PTFE content was 10.0 mass %.

<Comparative Example 10>
In the resin composition used for molding, the carbon fiber content was 2.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 12.0% by mass.

<Comparative Example 11>
In the resin composition used for molding, the carbon fiber content was 2.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 13.0% by mass.

<Comparative Example 12>
In the resin composition used for molding, the carbon fiber content was 2.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 14.0% by mass.

<Comparative Example 13>
In the resin composition used for molding, the carbon fiber content was 3.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 10.0% by mass.

<Comparative Example 14>
In the resin composition used for molding, the carbon fiber content was 1.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 14.0% by mass.

<Comparative Example 15>
In the resin composition used for molding, the carbon fiber content was 2.0 mass %, the aramid fiber content was 2.0 mass %, and the PTFE content was 10.0 mass %.

<Comparative Example 16>
In the resin composition used for molding, the carbon fiber content was 2.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 12.0% by mass.

<Comparative Example 17>
In the resin composition used for molding, the carbon fiber content was 2.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 13.0% by mass.

<Comparative Example 18>
In the resin composition used for molding, the carbon fiber content was 2.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 14.0% by mass.

<Comparative Example 19>
In the resin composition used for molding, the carbon fiber content was 3.0% by mass, the aramid fiber content was 2.0% by mass, and the PTFE content was 10.0% by mass.

<Comparative Examples 20 to 23>
The composition of the resin composition forming the covering member was the same as that of Comparative Example 3. The thickness of the covering member was 1.5 mm.

-Heat cycle test-
With respect to the weight rollers according to Examples 1 to 10 and Comparative Examples 1 to 19, the treatment at -20°C for 30 minutes and the treatment at 130°C for 30 minutes was set as one cycle, the treatment was performed up to 1000 cycles, and the heat shock resistance was evaluated. .. The presence or absence of cracks and breaks was visually confirmed every approximately 200 cycles.

The treatment of the weight rollers according to Examples 1 to 4 and Comparative Examples 1 to 7 was performed using a thermal shock device (manufactured by ESPEC Corp., model number: TSA-41L-A), and Examples 5 to 10 and Comparative Examples 8 to 19 were performed. The treatment of the weight roller according to (1) was performed using a thermal shock device (manufactured by ESPEC Corp., model number: TSE-11-A).

-Friction wear test-
A friction and wear test based on JIS K 7218-1986 was performed.

FIG. 6 is a diagram for explaining a friction and wear test of resin. As shown in the figure, a cylindrical test piece 62 having an inner diameter of 20 mm and an outer diameter of 25.6 mm was produced using a resin having the same composition as that of the covering member. This test piece 62 is brought into contact with a disk-shaped mating member 60 made of ADC12 (an alloy containing copper, silicon, aluminum, etc.), and is rotationally slid at a speed of 20 mm/s under a load of 1600 N. .. After performing this treatment for 20 hours, the amount of wear of the test piece 62 was measured to determine the specific amount of wear.

<Examples 11 to 13>
A test piece 62 was produced using a resin having the same composition as that of the covering member in Examples 5 and 8, and this was set as Example 11. A test piece 62 was produced using a resin having the same composition as that of the covering member in Examples 6 and 9, and this was set as Example 12. A test piece 62 was prepared using a resin having the same composition as that of the covering member in Examples 7 and 10, and this was set as Example 13.

<Comparative Example 24>
Further, a test piece 62 was produced using a resin having the same composition as that of the covering member in Comparative Examples 13 and 19, and this was set as Comparative Example 24.

-Measurement of dimensional change when absorbing water-
With respect to the weight rollers according to some examples and comparative examples, the rate of change in the axial length (total length) during water absorption was measured. Specifically, the weight roller was placed in an environment of 50° C. and a humidity of 95%, and the length in the axial direction was measured after the elapse of a predetermined period. The rate of change in total length due to water absorption was calculated by {(axial length of weight roller during measurement)-(initial axial length of weight roller)}/(initial axial length of weight roller).

-Evaluation result-
Table 1 shows the heat cycle test results of the weight rollers according to Examples 1 to 4 and Comparative Examples 1 to 7. In addition, Table 2 shows the heat cycle test results of the weight rollers according to Examples 5 to 10 and Comparative Examples 8 to 19.

From the comparison of Comparative Examples 1 and 3 and the comparison of Comparative Examples 4 and 5, in the case of using only carbon fiber as the reinforcing fiber, rupture occurred at a content rate of 3% by mass regardless of the molding method. It has been found that with a content of mass%, cracks and fractures do not occur with any molding method.

Further, from the results of Comparative Examples 3, 6, and 7, it was found that when only the aramid fiber was used as the reinforcing fiber, the occurrence of cracks or fractures could not be prevented even if the fiber content was increased.

On the other hand, from the results of Examples 1, 3, and 4, even if the content rate of the inorganic fiber is about 3%, the occurrence of cracks or fractures is caused by using the aramid fiber in an amount of 1% by mass or more and 7% by mass or less. It was confirmed that it can be effectively prevented.

Further, from the results of Example 2, it was found that not only carbon fibers but also glass fibers can exhibit an excellent reinforcing effect by using together with aramid fibers.

From the comparison between Comparative Examples 9 and 10 and Comparative Examples 15 and 16, it was suggested that cracks and fractures were more likely to occur as the content of PTFE increased.

However, from the results of Examples 1 to 10, by setting the content rate of the inorganic fiber to 3% or more and the content rate of the aramid fiber to 1% by mass or more and 7% by mass or less, the content rate of PTFE is 15% or more. Even in the case, it has been found that the occurrence of cracks and fractures can be effectively prevented.

Table 3 shows the results of the friction and wear test. Further, FIG. 7 is a diagram showing the relationship between the content rate (blending rate) of PTFE in the resin composition and the specific wear amount based on the results shown in Table 3.

From the results shown in Table 3 and FIG. 7, when the content of PTFE as the lubricant is 12% by mass or more, the specific wear amount is significantly reduced as compared with the case where the content of PTFE is 10% by mass. Do you get it. Further, it was confirmed that in the range of the PTFE content of at least 12% by mass and 14% by mass or less, the decrease in the specific wear amount was relatively small even when the PTFE content was increased.

Table 4 shows the axial length change rate (that is, the total length change rate) during water absorption for the weight rollers according to the example and the comparative example having an outer diameter of 18 mm, and in Table 5, the outer diameter is 20 mm. 5 shows the rate of change in the total length of a weight roller according to an example and a comparative example when absorbing water.

FIG. 8 is a diagram showing the results shown in Table 4, and FIG. 9 is a diagram showing the results shown in Table 5.

From the results shown in Tables 4 and 5 and FIGS. 8 and 9, regardless of the outer diameter of the weight roller, the base resin was nylon 66, the coating member contained 2% by mass to 3% by mass of carbon fiber, and the aramid fiber contained about 2% by mass. It was confirmed that if contained, the dimensional change due to water absorption can be suppressed to a small level.

On the other hand, in the weight rollers according to Comparative Examples 20 to 23, the total length change rate due to water absorption is extremely higher than that of the weight rollers according to Examples 5 to 10 and Comparative Examples 9, 10, 12, 13, 15, 16, 18, and 19. Was getting bigger. It is considered that this is because nylon 66 having low water absorption is used as the base resin in the weight rollers according to Examples 5 to 10 and Comparative Examples 9, 10, 12, 13, 15, 16, 18, and 19.

Further, from the comparison between Comparative Example 20 and Comparative Example 21 and the comparison between Comparative Example 22 and Comparative Example 23, even if the resin compositions constituting the covering member have the same composition, the weight roller produced by insert molding It was found that the above method can reduce the change rate of the total length when absorbing water, as compared with the weight roller manufactured by the press fitting process.

This is considered to be because, according to the insert molding, a molding shrinkage force is generated not only in the radial direction but also in the axial direction, so that the dimensional change is suppressed even when the constituent material of the clothing member is the same.

It was also confirmed that when the content of carbon fibers in the covering member was 3% by mass, the dimensional change due to water absorption could be slightly suppressed as compared with the case where the content of carbon fibers was 2% by mass.

As described above, the weight roller disclosed in the present specification can be used in a continuously variable transmission such as a motorcycle.

1 Weight roller 3 Weight adjusting member 5 Covering member 7 Outer peripheral surface
10a, 10b Part that covers the corner portion 11 Disc gate trace 13 Gate trace 21 Core pin 23 Disc gate 25, 43 Runner 27 First mold 29, 41 Second mold 31, 39 Resin 45 Pin gate 51 Fixed plate 53 Movable plate 55 pulley 57 guide plate 59 V belt 61 rotating shaft

Claims (7)

A cylindrical weight roller having a cylindrical weight adjusting member and a covering member provided on the outer peripheral surface of the weight adjusting member,
The coating member is made of a resin composition containing polyamide as a base resin,
Inorganic fibers having a tensile elastic modulus of 100 GPa or more and 650 GPa or less are 2.5 mass% or more and less than 7 mass%, organic fibers having a tensile elastic modulus of 7 GPa or more and 110 GPa or less are 1 mass% or more and 7 mass% or less, and a lubricant is 12 mass%. A weight roller that contains each of the above content rates of 20 mass% or less. The weight roller according to claim 1,
The inorganic fibers are carbon fibers, glass fibers or mixed fibers thereof,
The weight roller, wherein the organic fiber is an aromatic polyamide fiber. The weight roller according to claim 1 or 2,
The weight roller, wherein the sum of the content of the inorganic fibers and the content of the organic fibers in the resin composition is 3.5% by mass or more and 14% by mass or less. The weight roller according to any one of claims 1 to 3,
The weight roller, wherein the inorganic fibers are linear and the organic fibers have a bent portion. The weight roller according to any one of claims 1 to 4,
The weight roller, wherein the lubricant is particulate polytetrafluoroethylene. The weight roller according to any one of claims 1 to 5,
The covering member is tubular with a bottom,
A weight roller, wherein a disc gate mark is formed in the center of the bottom of the covering member. A step of injecting a resin composition from a gate in a state where a cylindrical weight adjusting member is arranged in a mold, and forming a covering member that covers an outer peripheral surface of the weight adjusting member,
The resin composition injected from the gate is made of polyamide as a base resin, and has an inorganic fiber having a tensile elastic modulus of 100 GPa or more and 650 GPa or less and 2.5 mass% or more and less than 7 mass% and a tensile elastic modulus of 7 GPa or more and 110 GPa or less. A method for producing a weight roller, comprising fibers in an amount of 1% by mass to 7% by mass and a lubricant in an amount of 12% by mass to 20% by mass.

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