JP2012145161A - Resin gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin gear capable of restricting an increase of an engagement error of gears even when a dimensional change occurs due to swelling by absorption of moisture in a resin molding part.SOLUTION: The resin gear includes: a metal bush 2; and the resin molding part 6 disposed in the periphery of the bush. The resin molding part 6 is formed by impregnating an unwoven fabric base material with a resin and hardening it, and is formed into an inclined tooth including a tip part and a dedendum part, and a helix angle of the tip part is formed larger than the helix angle of the dedendum part. Desirably, the helix angle of the tip part is larger by 0.1-0.5 degree than the helix angle of the dedendum part. This invention can be appropriately used for an unwoven fabric base material formed by a sheet forming method.

Description

  The present invention relates to a resin gear whose entire tooth portion is formed of a resin molded portion.

  Gears used for parts that require high strength and high durability such as automobiles have long been made of metal because of their required characteristics. For this reason, resin gears have been used as mating gears that mesh with metal gears in order to reduce the meshing noise between metal gears as much as possible.

As the resin gear, a metal bush is used as a portion fixed to the rotating shaft, a resin molded portion is provided around the bush, and teeth are formed on the resin molded portion.
The resin molded part is not only simply cured of the resin but also impregnated with resin in order to improve strength and durability, and aramid fiber is often used as the reinforcing fiber.

  More specifically, the reinforcing fiber is described as a doughnut-shaped cylindrical substrate made of aramid fiber yarn woven or knitted outward (see Patent Document 1) or aramid fiber short. A nonwoven fabric substrate (see Patent Document 2) in which fibers are made into a sheet is used.

Japanese Patent Laid-Open No. 08-156124 JP 2009-250364 A

  However, in the resin gear as described above, the resin molded part, particularly the tooth tip of the inclined tooth, swells due to moisture absorption and changes in size depending on the use environment, and as a result, there is a tendency to approach the spur tooth. There is a problem that the meshing error is worsened. As a result, there is a concern that the gears may not rotate smoothly, causing abnormalities at the time of meshing or abnormal noise due to a decrease in the amount of backlash.

  Fabricate resin gears with bevel teeth of the same size for those using reinforced fibers with cylindrical base material and those using non-woven fabric base material, and swell with each resin gear When the test was performed and the change of the tooth profile was confirmed at the upper part, middle part, and lower part of the oblique teeth, the one using the cylindrical base material swelled in the same manner, but the one using the non-woven base material, The R surface tended to swell more greatly than the lower portion, and the L surface tended to swell more greatly than the upper portion. At this time, even if the upper and lower surfaces were switched and the R and L surfaces were reversed, the change in the tooth profile was the same tendency as described above.

In addition, the upper part, the center part, and the lower part of the above-described oblique tooth are the upper part of the part from the tooth tip of the oblique tooth to the tooth base, and the part that is closer to the tooth base side by 20% of the entire length from the tooth tip. The middle part of the overall length is the central part, and the part from the tooth base to the tooth tip side by 20% of the overall length is the lower part (see FIG. 1).
Moreover, the R surface and L surface mentioned above mean the right side and the left side of the tooth surface when the gear is laid (see FIG. 1).

  The resin gear used in this experiment has an outer diameter of 90 mm, an inner diameter of the resin molded part: 60 mm, a tooth width of 12 mm, and an inclined tooth angle of 30 degrees, and the resin gear is 1500 in hot water at 100 ° C. After soaking for an hour, the angle was measured.

In addition, when the change in the torsion angle of the inclined tooth at the tip, center, and root of the inclined tooth was confirmed, the resin gear using the cylindrical base material swelled and twisted in the same manner. The angle became smaller and the amount of change was similar. On the other hand, in the resin gear using the nonwoven fabric base material, the twist angle is small, and the amount of change tends to change greatly at the tooth tip portion of the R and L surfaces compared to the tooth root portion.
Thereby, compared with the resin gear using the cylindrical base material, in the resin gear using the non-woven fabric base material, the change in the tooth tip portion was large, and the meshing was worse.

  An object of the present invention is to provide a resin gear in which the meshing error of the gear is small even when the resin molded portion undergoes a dimensional change due to swelling due to moisture absorption.

The present invention relates to the following.
(1) It has a metal bush and a resin molded part arranged around the bush, and the resin molded part is obtained by impregnating and curing a resin to a nonwoven fabric base material. A resin gear having a tooth tip portion twist angle larger than a tooth root portion twist angle.
(2) The resin gear as described in item (1), wherein the tooth tip twist angle is 0.1 to 0.5 degrees larger than the tooth tip twist angle.
(3) A resin gear in which the resin molded part is obtained by impregnating and curing a resin to a nonwoven fabric base material by papermaking in item (1) or (2).

  When a nonwoven fabric base material is used, it is found that the twist angle of the tooth tip part changes in the spur direction as compared with the tooth base part, and the present invention is based on this new finding.

  The resin gear of the present invention has a tooth tip twist angle larger than the tooth root twist angle, so that when the moisture is absorbed, the tooth tip twist angle approaches the tooth tip twist angle and meshes with the metal. It becomes possible to approach the helix angle corresponding to the gear making, and to suppress the deterioration of the meshing.

In addition, when the tooth tip twist angle is larger by 0.1 to 0.5 degrees than the tooth root twist angle, even if the humidity condition of the use environment changes between 0 and 100%, It is possible to suppress the deterioration of meshing more on average.
If the resin molded part is made by impregnating and curing a non-woven fabric base material with papermaking, the change in the tooth tip is larger than the change in the tooth base, so the meshing error during moisture absorption is further reduced. can do.

It is explanatory drawing of the tooth | gear part of resin gears. It is sectional drawing which shows one Example of the resin gears before forming the tooth | gear used for this invention. It is explanatory drawing of the nonwoven fabric base material manufacturing process by papermaking used for this invention. It is explanatory drawing of the shaping die used for this invention.

<Metal bushing>
The metal bush described in the present invention is provided with a through-hole into which the rotation shaft is inserted at the center, and has an outer peripheral portion where the resin molded portion is integrated.
The material of the bush is made of metal in consideration of strength and durability, and more specifically, carbon steel, aluminum, stainless steel, etc. can be used. Especially, carbon steel has high strength and good productivity. Preferably used.

The method for forming the metal bush is not particularly limited, but is preferably formed by sintering because of its high strength and durability.
Moreover, it is preferable to provide a protrusion on the outer peripheral portion of the metal bush to be in close contact with the resin molded portion in order to prevent the resin molded portion from slipping. The number of the protrusions is not particularly limited, but is preferably a rotating body, and is preferably provided at equiangular intervals. If there are four for each degree, it is preferable to provide every 90 degrees.

<Resin molding part>
The resin molded portion described in the present invention is arranged on the outer peripheral portion of the metal bush described above, and is not particularly limited as long as the nonwoven fabric base material is impregnated with resin. .

(Nonwoven fabric substrate)
The fiber used as the constituent material of the nonwoven fabric is not particularly limited, but an aramid fiber, a carbon fiber, a glass fiber, etc. can be used. In particular, the aramid fiber has a high strength, and the other metal gear meshes with the resin gear. Can be preferably used.

The nonwoven fabric base material can be used by stacking a plurality of sheet-like materials so as to have a thickness and adjusting the outer shape thereof.
When producing a nonwoven fabric substrate by papermaking, the operation of laminating a plurality of sheets as described above can be made unnecessary. More specifically, short fibers are dispersed in a dispersion liquid such as water to make a papermaking slurry. None, by injecting this papermaking slurry into the mold, separating the dispersion, and compressing and drying the short fibers remaining in the mold, a nonwoven fabric substrate having a predetermined thickness can be obtained without laminating a plurality of sheets. .

(resin)
The resin to be impregnated into the nonwoven fabric base material is not particularly limited as long as the deformation amount of the resin gear under the operating environment temperature is within the design error range, but a thermosetting resin should be used. However, it is preferable because it has high strength and excellent heat resistance, and more specifically, a crosslinked polyaminoamide resin, a phenol resin, an epoxy resin, and the like can be used. Particularly, the crosslinked polyaminoamide resin has high strength and heat resistance. Since it is excellent, it can be preferably used.

<Inclined tooth>
The resin molded part is an inclined tooth having a tooth tip part and a tooth base part, and this inclined tooth can be formed at the time of mold forming or by cutting after mold forming, but the tooth profile accuracy is high. Therefore, it is preferable to provide by cutting.
Moreover, it is preferable to divide the cutting into three stages and perform a first process on the outer peripheral portion, a second process of tooth profile creation, and a third process of tooth surface finishing.

The first process is described in more detail. A lathe process is performed, and the outer peripheral surface and the inner diameter part are cut and processed to a predetermined dimension. At this stage, teeth are not produced, and simple circumferential processing is performed.
To describe the second processing in more detail, it is processed into a tooth profile with a hobbing machine. As the hobbing machine, for example, GE15A (trade name) manufactured by Mitsubishi Heavy Industries, Ltd. can be used.
To describe the third process in more detail, the tooth surface is finished with a shaving machine. As the shaving machine, for example, FE30A (trade name) manufactured by Mitsubishi Heavy Industries, Ltd. can be used. In addition, since the shaving process is a final finishing process, the cutting amount is small and is about 20 to 150 μm.

The torsion angle of the inclined tooth needs to be larger than the torsion angle of the tooth root part. When the resin gear is completed, the torsion angle of the tooth tip part is larger than the tooth root part twist angle as described above, but swells as the humidity increases, and becomes the same angle as the tooth root twist angle. Become or get closer.
The torsion angle can be measured by a gear inspection machine or the like. The gear inspection machine inspects the tooth profile shape and tooth trace shape of one side (R surface or L surface) of the tooth. Specifically, TTi-300E (trade name) manufactured by Tokyo Technical Co., Ltd. may be used. it can.

There is no particular limitation as to how much the torsion angle of the tooth tip part is larger than the torsion angle of the tooth root part, but it is preferably 0.1 to 0.5 degree. By making the tooth tip twist angle 0.1 to 0.5 degrees larger than the tooth tip twist angle, the resin gear has a tooth trace between the tooth tip and the tooth root even in an atmosphere where the humidity changes. Is not greatly different, and the meshing error with the counterpart gear (metal gear) can be suppressed.
In addition, the processing environment is not particularly limited in the processing for increasing the torsion angle of the tooth tip portion by 0.1 to 0.5 degrees larger than the torsion angle of the tooth root portion unless it is in an extreme humidity environment. Specifically, it can be performed in a humidity environment of about 20 to 50%.

Examples of the present invention will be described in detail below.
<Example 1>
(Metal bush)
FIG. 2 is a sectional view of a resin gear, which is an embodiment of the present invention. The resin gear 1 has a metal bush 2 disposed at the center and a resin molded portion 6 around the metal bush 2.

The metal bush 2 is made of sintered carbon steel, and has a through hole 3 for connecting a drive shaft (not shown) at the center, and an outer peripheral surface in contact with the resin molded portion 6 is equiangular. Eight protrusions 4A are arranged at intervals.
As can be seen from the cross-sectional shape of the protrusion 4A, a reverse taper is formed in order to prevent the resin molded portion 6 from coming off and spinning, and the angle θ of the reverse taper is 10 degrees.

  The outer diameter of the resin gear 1 (before forming the teeth) is 91 mm, the outer diameter including the protrusion 4A of the metal bush 2 is 62 mm, and the outer diameter not including the protrusion 4A of the metal bush 2 The inner diameter of the through-hole 3 is 29 mm, and the thicknesses of the metal bush 2 and the resin molded part 6 are both 13 mm.

(Preparation of nonwoven fabric substrate)
First, in order to manufacture a papermaking slurry, a tank filled with an amount of water in which the short fiber dispersion concentration is 4 g / liter is prepared. And the short fiber of the quantity from which the total amount of the short fiber in a resin molding becomes 40 volume% is put in this tank. Specifically, as a short fiber, a single fiber fineness: 1.7 dtex, a fiber length: 3 mm-long para-aramid short fiber (“Technora (Teijin Limited)” manufactured by Teijin Limited), 50% by mass, 45% by mass of a meta-aramid short fiber (“Conex (Teijin Limited)” manufactured by Teijin Limited) having a fiber fineness of 2.2 dtex and a fiber length: 3 mm, and “Kevlar (DuPont Limited) manufactured by DuPont Co., Ltd. "Trademark) Pulp" is fibrillated to a freeness value of 300 ml. Next, the water in the tank is stirred with a stirrer to disperse the short fibers.

Next, the metal bush 2 is positioned on the lower bush supporting mold 12 by using the papermaking compression device 7 shown in FIG.
Then, as shown in FIG. 3B, the upper bush supporting mold 11 is moved downward to sandwich the metal bush 2 between the pair of bush supporting molds 11 and 12. Here, the position of the lower compression mold 14 was a position where the distance from the axial center of the metal bush 2 to the upper surface of the bottom member 16 was 40 mm. A papermaking slurry containing dispersed short fibers is filled into the papermaking compression device 7. Then, vacuum suction is performed to drain water from the plurality of through holes 15 provided in the lower compression mold 14, whereby the short fibers and the water are separated to obtain a cylindrical fiber assembly 8. In order to prevent short fibers from flowing out of the through hole 15 during drainage, a bottom member 16 is disposed on the lower compression mold 14. As the bottom member 16, a metal mesh made of metal: 100 mesh (mesh size is defined by “JIS G 3555”) was used.

  Next, compression is performed in order to make the short fiber bite into the detent portion of the metal bush 2 more firmly. As shown in FIG. 3C, the upper compression mold 13 heated to 150 ° C. is moved to a position where the distance from the axial center of the metal bush 2 to the lower surface of the upper compression mold 13 is 40 mm. Lower. This position is a position where the metal bush 2 is located at the center between the pair of compression molds 13 and 14.

As shown in FIG. 3D, the pair of compression dies 13 and 14 are moved at the same speed in a state where the metal bush 2 is located at the center between the pair of compression dies 13 and 14. It moves to the direction which mutually approaches at (5 mm / s), and compresses until the fiber assembly 8 becomes thickness: 10mm.
The nonwoven fabric base material 5 integrated with the metal bush 2 was obtained by compressing for 2 minutes in a heated state. At the time of the compression, the compression is performed while being vacuum-sucked from the through hole 15 of the lower compression mold 14.
The nonwoven fabric substrate 5 has a mass of 40 g, an outer diameter: 91 mm, an inner diameter: 60 mm, and a thickness: 13 mm.

(Production of resin gear)
As shown in FIG. 4, the nonwoven fabric base material 5 integrated with the metal bush 2 obtained in the above process is placed in a moving mold 27 heated to 200 ° C. and clamped. And after depressurizing the inside of the fixed mold 25 to a pressure of 90 kPa or less, a curing accelerator is blended in the thermosetting resin melted therein and injected into the mold, and the nonwoven fabric base material is impregnated and cured, Create a gear material.

  The thermosetting resin is 69 parts by mass of 2,2 ′-(1,3-phenylene) bis-2-oxazoline (manufactured by Mikuni Pharmaceutical Co., Ltd.) and 4,4′-diaminodiphenylmethane (Mitsui Chemical Polyurethane Co., Ltd.). Manufactured by mixing 31 parts by mass and dissolved at 140 ° C., and octyl bromide (manac product name, manufactured by Manac Co., Ltd.) as the curing accelerator is 100 masses of the thermosetting resin described above. 1 part by mass is added to the part.

  After the resin is cured, the gear material is removed from the mold, and the gear material is subjected to the first processing from the outer peripheral side so as to include a metal bush and a resin molded portion. In the first processing, the outer diameter of the resin molded part is left with a machining allowance of 0.5 to 2 mm from the finished dimension, and the thickness is left with a machining allowance of 0.5 to 2 mm from the finished dimension. Manufactured, product name: MW120).

After finishing the first processing, the second processing is performed. In the second processing, the tooth height from the tooth root to the tooth tip: 8 mm, pitch: 80, twist angle: using a hobbing machine (Mitsubishi Heavy Industries, Ltd., trade name: FE30A) to form oblique teeth. Processing at 30 degrees was performed.
After the second processing, the third processing is performed. In the third process, the shaving machine (Mitsubishi Heavy Industries, Ltd., trade name: FE30A) is used to perform the final shaving. Tooth height from tooth root to tooth tip: 8 mm, pitch: 80, tooth tip twist Angle: Processing was performed so as to be 0.2 degrees larger than the root twist angle. Although it differs depending on each part, the cutting amount is 20 to 150 μm.

  By the above processing, a resin gear having a root twist angle of 30 degrees and a tip twist angle of 30.2 degrees was produced.

<Comparative Example 1>
In Example 1, a resin gear was obtained in the same manner as in Example 1 except that the root twist angle was 30 degrees and the tip twist angle was 30 degrees.

  The resin gears produced in the examples and comparative examples were immersed in hot water at 100 ° C. for 1500 hours. Thereafter, evaluation was performed in a meshing test using metal gears meshed with the gear portions of Examples and Comparative Examples.

<Evaluation of meshing test>
The meshing test is a double-toothed meshing test in which the left and right tooth surfaces of two gears are brought into contact with each other and meshed without a back gap, and the amount of change in the center-to-center distance when rotated is measured. . Further, the meshing accuracy is compared with an error from the change amount of the center-to-center distance of the ideal gear accuracy.
(1) One-pitch meshing error is a change in the center-to-center distance while meshing by one pitch (one tooth). Further, the maximum value of one pitch error during one rotation of the gear is displayed.
(2) The full pitch meshing error is the maximum value of the fluctuation of the center distance during one rotation of the gear.

  The evaluation results are shown in Table 1. The values in Table 1 are meshing error change amounts before and after processing.

  As shown in Table 1, the resin gear according to the present invention has a tooth tip portion twist angle larger than the tooth root portion twist angle, so that even when the resin molded portion causes a dimensional change due to swelling due to moisture absorption, The amount of change in tooth meshing error can be kept small. For this reason, there is no fear of meshing abnormalities such as fluctuations in the rotation speed of the gears or the gears not rotating smoothly, or abnormal noise due to a decrease in the amount of backlash.

DESCRIPTION OF SYMBOLS 1 ... Resin gear, 2 ... Metal bush, 3 ... Through-hole, 4A ... Protrusion, 5 ... Nonwoven fabric base material, 6 ... Resin molding part, 7 ... Paper-making compression apparatus, 8 ... Fiber assembly, 10 ... Cylindrical gold 11... Bush supporting mold, 12... Bush supporting mold, 13 .. Compression mold, 14... Compression mold, 15 .. Through hole, 16 .. Bottom member, 21. , 23 ... mold, 25 ... fixed mold, 27 ... moving mold, 29 ... upper mold, 29A ... pressing part

Claims (3)

  A metal bush and a resin molded portion disposed around the bush, wherein the resin molded portion is obtained by impregnating and curing a resin on a nonwoven fabric base, and a tooth tip portion and a tooth root portion. A resin gear having a tooth tip portion twist angle larger than a tooth root portion twist angle.   The resin gear according to claim 1, wherein the tooth top portion twist angle is 0.1 to 0.5 degrees larger than the tooth root portion twist angle.   3. The resin gear according to claim 1, wherein the resin molded portion is obtained by impregnating and curing a resin on a nonwoven fabric substrate made by papermaking.

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