JPH04312256A - Gear and cam consisting of long-fiber reinforced thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain a lightweight, low-noise, and corrosion-resistant gear or cam that can resist a high load condition by laminating and meltedly forming a compound sheet made up of arranged long-fiber reinforcing materials and short fibers consisting of thermoplastic resins. CONSTITUTION:Long-fiber reinforcing materials 1 such as carbon fibers and glass fibers are extendedly arranged in one direction to form a sheet shape, and short fibers consisting of thermoplastics such as nylon and polyester are mixedly woven to make a compound sheet. And the compound sheets are laminated and meltedly formed to shape a prescribed gear or cam 2. Thus, a high fracture toughness, a strong fatigue strength, a high working accuracy, and lightweight gear or cam can be manufactured with high productivity.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention is a power transmission mechanism.
This article relates to composite gears and cams with numerous features. Specifically, the present invention relates to gears and cams made of long fiber-reinforced thermoplastic resin.

0002

2. Description of the Related Art Conventionally, gears and cams have been manufactured from plastic materials in order to overcome the disadvantages of metal gears (noise generation, corrosion, high weight, etc.). However, although thermoplastic resins have the characteristic that they can be manufactured into products very efficiently and inexpensively by injection molding, etc., they have poor mechanical properties, so they have low strength and cannot be used in high-load parts. Couldn't use it. In order to compensate for this drawback, for example, Japanese Patent Laid-Open No. 54-36443 proposes a gear made of carbon fiber reinforced thermosetting resin. Due to its high strength and physical properties, gears made from this new material can be used in high-load, heavy parts, but compared to thermoplastic resin, molding of thermoset resin generally takes a long time. The production efficiency was extremely low, and when precision was required, cutting was required. The cutting process requires the use of a special jig because the material contains carbon fiber, and considerable consideration must be given to the maintenance of the jig. Furthermore, since this technique uses only woven fabric as the reinforcing material, it has the disadvantage that the strength per weight of the reinforcing material is lower than that of unidirectional materials.

0003

[Problems to be solved by the invention] The problems of the present invention are lightweight,
To provide gears and cams made of fiber-reinforced thermoplastic resin that can be used in high-load parts that have features such as low noise and corrosion resistance, and can be manufactured with high precision and high productivity. It is.

0004

[Means for Solving the Problems] The present invention provides a gear made of a long fiber-reinforced thermoplastic resin which is melt-molded by laminating a composite sheet made of arranged long fiber reinforcement material and short fibers made of a thermoplastic resin. It's a cam. The direction of the long fibers can be determined when laminating composite sheets according to the structure of the gear and cam and the required performance. In general, by stacking and molding long fibers arrayed at a constant angle in the axial direction of gears and cams, a material that is effective in the direction of force transmission can be obtained.

In other words, the force applied to the teeth of a gear is bending stress, and gears in which long fiber reinforcement is arranged perpendicular to the direction of load are very advantageous in terms of bending strength. becomes more applicable to Resin (matrix)
Thermoplastic resins are suitable because of their good moldability, and it is also important to measure the optimal resin from a wide range of resin types, taking into account the heat resistance temperature required for the product. When thermoplastic resin is used as a fiber-reinforced composite material, fracture toughness is excellent due to the ductility effect of the thermoplastic resin, and as a result, impact resistance strength is also improved. Similarly, it is possible to exhibit its characteristics in vibration damping properties and fatigue properties.

[0006] The long fiber reinforcing material used in the present invention may be carbon fiber, glass fiber, or other inorganic or organic fiber, as long as the reinforcing material is not lost at the molding temperature.
Any type of fiber may be used, but carbon fiber is advantageous in terms of physical properties and is suitable when pursuing high functionality of the product. There are various forms of long fiber reinforcement such as woven fabrics, unidirectional fabrics, and knitted fabrics, but unidirectional materials can exhibit the highest strength. For example, in the case of carbon fiber, 3kf is used for textiles, plain weave with a basis weight of about 200g/m2, and for unidirectional materials, the desired basis weight is determined by the thickness and number of fiber bundles, and then spread uniformly to the specified width. It is a thing. However, since it is molded as a gear and exhibits overall high physical properties as a product, a combination of the above-mentioned shapes and materials is naturally necessary.

As mentioned above, the type of thermoplastic resin may be selected based on the required physical properties of the product, but generally nylon, polyester, polypropylene, polycarbonate, polyphenylene sulfide, and high heat resistance for aircraft use are selected. Examples include polyetherketone, polyetheretherketone, polyetherimide, etc. The composite sheet of the present invention is a composite sheet composed of arranged long fiber reinforcement and thermoplastic resin, and the thermoplastic resin has a higher strength contribution to the strength of the reinforcement when it is uniformly dispersed by the long fiber reinforcement. is high. An example of a method for manufacturing a composite sheet with improved dispersibility is shown in WO90-7024.

[0008] In other words, the most suitable reinforcing material is a composite sheet in which short fibers of thermoplastic resin are sufficiently mixed with a unidirectional sheet-like material such as carbon fiber or glass fiber, woven fabric, or knitted fabric. . By driving the short fibers into the reinforcing long fibers with a gas or liquid stream, the short fibers are dispersed between each single fiber.

In view of the ease of intertwining and integration with the reinforcing fiber web and the flexibility of the resulting composite sheet, it is preferable that the short fibers have low rigidity, and this varies depending on the type of polymer used, but in general, the short fibers have low rigidity. length 100cm, preferably 10
cm or less, more preferably 5 cm or less, 1 mm
The diameter of the short fibers is generally less than 200 μm, preferably 100 μm or less, which is not preferable because the short fibers do not get entangled with the long fibers.
Short fibers with a diameter of μ or less, more preferably 50 or less, are preferred. In addition, flash-spun fibers whose fiber length is not clear or microwaves may be used as long as they are intertwined and integrated with the reinforcing fiber web.

The outline of the manufacturing method will be described below. First, the required amount of each raw material is prepared for the above-mentioned composite sheet based on the design of the product to be manufactured. The design utilizes compound rules to ensure that the product exhibits the best cost performance, including material specifications (type of reinforcing fiber, form, basis weight, type of thermoplastic resin, basis weight, etc.) and each composite when cutting the sheet shape. It is preferable that at least the orientation direction of the sheet is clearly indicated. Next, the composite sheet is cut into a specified shape using a cutting machine, taking into consideration the orientation direction, number of sheets, etc. Carbon fiber is harder than other fibers and cannot be easily cut or cut accurately with ordinary cutting tools, so a special jig is required. Cutting methods to specified shapes include punching, cutting with a hard blade, cutting with a single blade, rotary cutting with a round blade or polygonal blade, cutting with a laser beam, cutting with a water jet, cutting with a high frequency vibrating blade, cutting with scissors, There are many types, and each type has various grades such as manual, automatic, computerized, etc. In the case of the material in the form shown above, the material itself is sufficiently intertwined, so even if it is cut into a complicated shape, the ends and periphery will not fall off or be disturbed, and the protrusions will not fall off. When cutting,
The thermoplastic at the cutting end melts and welds to better maintain its shape. The composite sheets are laminated in the design orientation and then stitched together in advance.
There is also a method of forming a prescribed shape using the above-mentioned cutting method. In this case, there are advantages such as fewer mistakes compared to cutting and laminating each sheet one by one. Laminating the cut sheets in an orderly manner according to the design is more efficient, even for beginners, by using a laminating form that matches the shape of the product.

[0011] In the combination of composite sheets, if the surface layer is made of fabric, the disadvantages of the surface layer arrangement of the unidirectional material can be compensated for, and at the same time, the finish is aesthetically pleasing. Furthermore. If high functionality and performance are expected, the laminated shape should be sewn together in the thickness direction, preferably with the same fibers as the reinforcing fibers, or at least the same type of fibers. A mold that has been optimally designed for the product is preheated to a specified temperature, and the laminate produced by the previous method is placed inside it, and the temperature of the mold is raised at a certain heating rate determined by the type of resin. Heat up to temperature. After confirming that the resin has melted, pressurize to the specified pressure and maintain that pressure and temperature for the specified time. Next, the temperature begins to decrease using the provided cooling device, but it is preferable to perform this operation under pressure in order to eliminate voids in the molded product. Once the temperature has fallen to the specified temperature, the molded product is removed from the mold using the expulsion plate. The removed product may have ``burrs'' on its surface due to the condition of the mold and molding conditions. In such cases, it is best to use an appropriate jig to smooth the surface to improve the finish of the product.

0012

[Example] A composite sheet using carbon fiber as the reinforcing long fiber and polyphenylene sulfide as the matrix resin was selected, and as shown in Figure 1, [0°/90°/±4
5°/±22.5°/±67.5°], and a composite sheet made of a woven fabric was laminated on the outermost layer.

[0013] Molding temperature 340°C, molding pressure 10kg/c
Compression molding was performed under molding conditions of m2 and molding time of 5 minutes. The product taken out was of high precision and high performance with little burrs.

[0014]

[Effects of the invention] Compared to conventional composite gears and cams, it has higher fracture toughness, stronger fatigue strength, and higher machining accuracy.
Light gears and cams can be produced with high productivity.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a gear shown in an example.

[Explanation of symbols]

1. Long fibers for reinforcement 2 Gears

Claims (1)

[Claims] Claim 1: Gears and cams made of long fiber reinforced thermoplastic resin, which are made by laminating and melt-molding composite sheets made of arranged long fiber reinforcing material and short fibers made of thermoplastic resin.