JP2003004119A - Reinforcing fiber base material for resin gear and resin gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain static mechanical strength of a resin gear and improve the durability in actual use by optimizing the construction of a flat sheet formed of an aramido fiber yarn to be used as a reinforcing fiber base material for the resin gear. SOLUTION: The used reinforcing fiber base material is an aramido fiber yarn knitted into a flat sheet. Wales as pitches of knitted loops in the cross direction are set to be 25-35 pieces/inch and courses as pitches of the knitted loops in the longitudinal direction are to be 16-26 pieces/inch. A ring body formed by cylindrically coiling the reinforcing fiber base material and folding its cylindrical body into a bellows in the axial direction and a metal bush arranged at the center thereof are stored in a forming die and the ring body is impregnated with a resin to form an integral molding of the ring body and the metal bush.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a reinforcing fiber base for molding a resin gear and a resin gear using the reinforcing fiber base.

[0002]

2. Description of the Related Art As a reinforcing fiber base material for molding a resin gear, a base material in which aramid fiber yarn is knitted in a tubular shape has been proposed (Japanese Patent Laid-Open No. 8-156124). As shown in FIG. 4, this reinforcing fiber base material 11 is wound up in the axial direction to form a ring body 12, which is used for manufacturing a gear. The ring body and a metal bush arranged in the center of the ring body are housed in a molding die, and the ring body is impregnated with resin to be integrally molded. Then, teeth are formed around the formed ring body by cutting or the like to complete the resin gear. This resin gear is
Since the reinforcing fiber base material is a seamless ring body, the strength around each part of the gear is uniform, which is preferable.

In the above technique, the diameter of the reinforcing fiber base material knitted in a tubular shape is changed according to the diameter of the resin gear to be manufactured. Depending on the gear to be manufactured, the work of knitting the reinforcing fiber base material of various diameters is extremely complicated, and in some cases, the reinforcing fiber base material of the required diameter cannot be prepared. Further, in order to obtain a gear having a wide tooth width, it is necessary to stack the ring-shaped reinforcing fiber bases in multiple stages to secure the tooth width. Therefore, there is a proposal that a reinforcing fiber base material knitted into a flat sheet can be used to easily cope with a change in the diameter of a resin gear (Japanese Patent Application No. 2001-68367). As shown in FIG. 5, the reinforcing fiber base material 11 is rolled into a tubular shape, and the tubular body is axially folded into a bellows shape in a temporary forming die 14 to form a ring body 12 for manufacturing a gear. To use. The ring body 12 and the metal bush 1 arranged at the center of the ring body 12 are housed in a molding die, and the ring body 12 is impregnated with resin to be integrally molded. Then, teeth are formed around the formed ring body by cutting or the like to complete the resin gear. This resin gear can respond to changes in the diameter of the gear by simply changing the diameter of the winding core that wraps the reinforcing fiber base in a tubular shape, and by adjusting the amount of folding into a bellows, you can change the tooth width. Can handle. Since the reinforcing fiber base material is a ring body having no joints, the strength around each part of the gear is also uniform.

[0004]

The problem to be solved by the present invention is to optimize the constitution of a reinforcing fiber base material obtained by knitting the above-mentioned aramid fiber yarn into a flat sheet, and to obtain the static mechanical strength of the resin gear. Is to improve the actual use durability.

[0005]

In order to achieve the above object, the present invention uses a aramid fiber yarn knitted into a flat sheet as a reinforcing fiber base material. As shown in FIG. 1, the pitch of stitches is called a wale in the width direction and a course in the longitudinal direction. The feature of the present invention is that the wale is 25 to 35 yarns / inch and the course is 16 to 2
6 points / inch. Such a reinforcing fiber base material is rolled into a tubular shape and the tubular body is axially folded into a bellows shape, and a metal bush disposed in the center of the ring body is housed in a molding die, The ring body is impregnated with resin and integrally molded, and teeth are formed around the molded ring body to obtain a resin gear.

Since the reinforcing fiber base material knitted in the form of a flat sheet has elasticity, it expands by the pressure applied when the molding die is closed. Therefore, the resin can sufficiently penetrate between the fibers of the reinforcing fiber base material, and a molded article in which the resin and the fibers are uniformly distributed can be obtained. And, the above-mentioned distribution is uniform, and the optimum range of wales and courses that can achieve the object of the present invention is
Range of wales and courses above. If the number of wales and courses is less than the above lower limit, the static mechanical strength and durability of the resin gear will be insufficient. On the other hand, when the number of wales and courses exceeds the upper limit value described above, the static mechanical strength increases, but the durability decreases. This is because when the number of wales and courses exceeds the above upper limit, the resin does not sufficiently penetrate between the fibers of the reinforcing fiber base material and the distribution of the fibers and the resin becomes uneven. The portion where the distribution of fibers is small and which is rich in resin is likely to be damaged during the driving of the gear, and deterioration starts from the minute damaged portion and the durability is reduced.

By setting the number of wales and courses of the reinforcing fiber base formed by knitting aramid fiber yarn into a flat sheet shape within the above range, the durability of the resin gear is improved and the static mechanical strength is maintained. It is extremely important to do so.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In carrying out the present invention, the aramid fiber yarn knitted into a flat sheet is preferably a mixture of para-aramid fiber and other fibers, for example, meta-aramid fiber. If the yarn is composed of only para-aramid fiber, the strength is increased, but the machinability for forming the teeth of the gear is deteriorated, and it becomes difficult to maintain the gear machining accuracy. From the viewpoint of strength and processability, the mixed spinning of para-aramid fiber and meta-aramid fiber is preferably 40/60 to 60/40 in mass ratio. However, for applications with a light load, the mass ratio of the meta-aramid fiber may be increased, and in some cases, it may be 100.

It is preferable that the aramid fiber yarn has a small thickness in order to improve the permeability of the resin into the reinforcing fiber base material and improve the durability. However, considering the workability when knitting into a flat sheet, it is appropriate that the thickness of the aramid fiber yarn is around 20th. The thinner the thread, the easier it is to break when knitting. The number of yarns to be knitted may be one or two or more, but when two or more yarns are knitted, the density of the finished reinforcing fiber base material is high. Considering the resin permeability and mechanical strength, it is preferable to knit one thread in a tubular shape. However, from the viewpoint of reducing the man-hours for knitting and the man-hours for manufacturing the resin gear, it is preferable to knit two or more yarns to knit a flat sheet-shaped reinforcing fiber base material.

The production of a resin gear using the above-mentioned reinforcing fiber base material knitted into a flat sheet is carried out, for example, as follows. First, a flat sheet-shaped reinforcing fiber base material is rolled up in a tubular shape, and the tubular body is axially folded into a bellows shape to form a ring body. As shown in FIG. 2, the ring bodies 12 are stacked in two stages in the molding die 13, and the metal bush 1 is arranged in the center. The ring body 1 is pressed by the pressure when the molding die 13 is closed.
2 is compressed and deformed to conform to the shape of the metal bush 1. Then, the inside of the molding die is depressurized, and a liquid resin (crosslinked polyaminoamide, epoxy resin, polyimide, etc.) is injected and penetrates into the ring body to be cured by heating. Teeth are formed by cutting around the formed ring body to complete a gear. In another manufacturing method, a flat sheet-shaped reinforcing fiber base material is impregnated with a resin in advance and dried. This is rolled into a tubular shape and the tubular body is axially folded into a bellows shape to form a ring body. This ring body is placed in a molding die together with a metal bush and integrated by heat and pressure molding. Teeth are formed by cutting around the formed ring body to complete a gear.

[0011]

Example 1 Para-aramid fiber (fiber length 50 mm, fiber diameter 16 μm)
And meta-aramid fiber (fiber length 50mm, fiber diameter 16μ
m) was mixed and spun at a mass ratio of 50/50 to prepare an aramid fiber yarn having a 20th thickness. A flat sheet-shaped reinforcing fiber base material was knitted with one aramid fiber thread (flat knitting). There are 30 wales / inch and 23 courses / inch. By using two ring bodies obtained by winding the flat sheet-shaped reinforcing fiber base in a tubular shape and folding the tubular body in the axial direction into a bellows shape, by using the method described in the embodiment of the invention, Molded integrally with the bush. The ring body was impregnated with the resin by injecting the crosslinked polyaminoamide into a molding die under a reduced pressure (1300 Pa). The dimension of the molded ring body is 90 mm in outer diameter, 60 mm in inner diameter, and 14 mm in thickness, and the resin content is 50% by mass. As shown in FIG. 3, the ring body 12 and the metal bush 1 are integrally formed with a detent 2 that protrudes from the metal bush and bites into the ring body 12.

Example 2 In Example 1, 29 wales / inch, course 25
This is the same except that the number is book / inch.

Example 3 The same procedure as in Example 1 was carried out except that the tubular reinforcing fiber base was knitted with two aramid fiber threads. In this case, since the density of the reinforcing fiber base material becomes high, the number of times of winding in a tubular shape is made smaller than in Example 1 to obtain a ring body having the same mass as that in Example 1. Since the time for knitting the reinforcing fiber base material is shortened and the number of times of winding is reduced, the number of manufacturing steps is reduced accordingly.

Example 4 The same procedure as in Example 2 was conducted except that a flat sheet-like reinforcing fiber base was knitted with two aramid fiber threads. In this case, since the density of the reinforcing fiber base material is high, the number of times of cylindrical winding is smaller than that of the second embodiment, and the ring body has the same mass as that of the second embodiment. The number of manufacturing steps is reduced as in Example 3.

Comparative Example 1 In Example 1, 23 wales / inch, course 23
This is the same except that the number is book / inch.

Comparative Example 2 In Example 1, 30 wales / inch, course 14
This is the same except that the number is book / inch.

Comparative Example 3 In Example 1, 37 wales / inch, course 22
This is the same except that the number is book / inch.

Comparative Example 4 In Example 1, 30 wales / inch, course 28
This is the same except that the number is book / inch.

In the resin gears of the above respective examples, teeth were formed by cutting on a ring body impregnated with resin and molded. Table 1 shows the measurement results of the bending strength and elastic modulus of the fan-shaped test piece cut out from the molded ring body at an angle of 90 °. In addition, the durability (total number of revolutions until breakage) measurement results when the gears are continuously rotated by applying a load are shown. The bending strength and elastic modulus were measured by applying a pressing force at a speed of 2 mm / min from the inner peripheral side to the test piece supporting the outer peripheral side of the fan shape at a distance of 40 mm. Durability is a resin gear (module (M) = 3.0, number of teeth (Z) =) under a load of root stress of 200 MPa.
22) is continuously rotated in oil at 130 ° C at a speed of 6000 rpm, and the total number of rotations until the resin gear is broken is measured.

[0020]

[Table 1]

Examples 1 and 2 and Comparative Examples 1 to 4 shown in Table 1
It can be understood from the measurement result of 1. that specifying the number of wales and courses effectively works to improve durability even if the static mechanical strength is lowered to some extent. Even if the static mechanical strength is low, it has a level that is practically acceptable. The durability of Examples 3 and 4 is lower than that of Examples 1 and 2, because the flat sheet-shaped reinforcing fiber base material is knitted with two aramid fiber threads. However, also in this case, the specification of the number of wales and courses effectively acts to improve the durability, and in other cases in which two aramid fiber yarns are knitted (the number of wales and courses is outside the specified range of the present invention). If it is), it is more durable.

[0022]

As described above, the flat sheet-like reinforcing fiber base material according to the present invention is used, and the reinforcing fiber base material is rolled up into a tubular shape and the tubular body is axially folded into a bellows-like shape. By configuring the gear with the body, it is possible to obtain a resin gear that maintains static mechanical strength and has a long service life.

[Brief description of drawings]

FIG. 1 is an enlarged view illustrating a configuration of a reinforcing fiber base material according to the present invention.

FIG. 2 is a cross-sectional explanatory view showing a state of molding a resin gear targeted by the present invention.

FIG. 3 is a cross-sectional explanatory diagram of a resin gear targeted by the present invention.

FIG. 4 is an explanatory view showing a manner of forming a ring body from a conventional reinforcing fiber base material.

FIG. 5 is an explanatory view showing a manner of forming a ring body from the reinforcing fiber base material according to the present invention.

[Explanation of symbols]

1 is a metal bush 2 is a rotation stop 11 is a reinforcing fiber base material 12 is a ring 13 is a molding die 14 is a temporary mold

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3J030 BA01 BB02 BC01 BC05                 4F204 AA29 AA39 AA40 AD03 AD05                       AD16 AD35 AG13 AH12 AM28                       FA01 FB01 FB11 FF05 FN11                       FN15 FN17                 4L002 AA06 AB01 AC00 BA01 EA00                       EA05 FA06

Claims (2)

[Claims] 1. A reinforcing fiber base material for a resin gear, which is formed by knitting an aramid fiber yarn into a flat sheet and has a wale of 25 to 35 threads / inch and a course of 16 to 26 threads / inch. 2. A ring body formed by winding the reinforcing fiber base material according to claim 1 in a tubular shape and folding the tubular body into a bellows shape in the axial direction, and a metal bush arranged in the center of the ring body. A resin gear, characterized in that the ring body is impregnated with resin and integrally molded, and teeth are formed around the molded ring body.