JP4407929B2 - Molding method of resin molded gear - Google Patents

Molding method of resin molded gear Download PDF

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JP4407929B2
JP4407929B2 JP2004270338A JP2004270338A JP4407929B2 JP 4407929 B2 JP4407929 B2 JP 4407929B2 JP 2004270338 A JP2004270338 A JP 2004270338A JP 2004270338 A JP2004270338 A JP 2004270338A JP 4407929 B2 JP4407929 B2 JP 4407929B2
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resin
molding
molded gear
molded
web
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JP2006082434A (en
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穣 別所
章弘 望月
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Polyplastics Co Ltd
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Polyplastics Co Ltd
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Priority to PCT/JP2005/016908 priority patent/WO2006030810A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/06—Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
    • B29C45/56—Means for plasticising or homogenising the moulding material or forcing it into the mould using mould parts movable during or after injection, e.g. injection-compression moulding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/76—Measuring, controlling or regulating
    • B29C45/7613—Measuring, controlling or regulating the termination of flow of material into the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/76—Measuring, controlling or regulating
    • B29C45/77—Measuring, controlling or regulating of velocity or pressure of moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2015/00—Gear wheels or similar articles with grooves or projections, e.g. control knobs
    • B29L2015/003—Gears
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/06—Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties
    • F16H2055/065—Moulded gears, e.g. inserts therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/17—Toothed wheels

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Gears, Cams (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Description

本発明は、樹脂射出成形歯車を、エジェクトピン等の局部加圧機構を利用し、低加圧圧力で長時間加圧することによる、局部加圧開始時期などの成形条件の許容幅が広く、得られた樹脂成形歯車が寸法的に高精度で、且つ多数個取り成形を可能とする成形方法、及び該方法により得られた歯車に関する。   The present invention uses a local pressurizing mechanism such as an eject pin for a resin injection molded gear and pressurizes it for a long time at a low pressurizing pressure, thereby allowing a wide range of molding conditions such as local pressurization start time. The present invention relates to a molding method in which the resin-molded gear thus obtained is dimensionally highly accurate and enables a multi-piece molding and a gear obtained by the method.

従来、複写機、プリンター等のＯＡ機器の動力伝達部品として、また、ＶＴＲテープ駆動機構、レーザーディスクプレーヤのローディング機構等に樹脂製の平歯車が多数使用されている。また、低騒音性能および高速性能の要求が強い場合には、噛み合い率が高く、かつ低騒音で大きな力を伝える樹脂はすば歯車が使用されている。
このような樹脂歯車を設計する場合、従来は騒音や伝達効率、摩擦摩耗特性、強度、歯の各部要素の形状及び高度な初期精度等を考慮して、歯車の各構成部材の形状や寸法等を定めている。一般的には騒音や強度、剛性を考慮し、リム厚はピッチ円歯厚の１．５倍程度、または、モジュールの２．５倍程度とし、かつ、ウエブ厚はリム厚とほぼ同じにするように設計される。
例えば、平歯車あるいははすば歯車の断面寸法の標準的寸法割合が示されており、これによると、ピッチ円歯厚とリム厚とウエブ厚の比は１：１．４：１．６である。一方、高度な初期精度を考慮すると、ピッチ円歯厚とリム厚の比は１：０．６〜１．２程度で設計することが一般的であった。（非特許文献１参照） Conventionally, many resin spur gears have been used as power transmission parts for office automation equipment such as copying machines and printers, and for VTR tape drive mechanisms and laser disk player loading mechanisms. Further, when demands for low noise performance and high speed performance are strong, a helical gear is used as a resin that has a high meshing rate and transmits a large force with low noise.
When designing such a resin gear, the shape and size of each component of the gear, etc., taking into account the noise, transmission efficiency, friction and wear characteristics, strength, shape of each element of the tooth and high initial accuracy, etc. Is stipulated. In general, considering the noise, strength, and rigidity, the rim thickness is about 1.5 times the pitch circle tooth thickness, or about 2.5 times the module thickness, and the web thickness is almost the same as the rim thickness. Designed as such.
For example, the standard dimensional ratio of the cross-sectional dimension of a spur gear or a helical gear is shown. According to this, the ratio of pitch circle tooth thickness, rim thickness, and web thickness is 1: 1.4: 1.6. is there. On the other hand, in consideration of high initial accuracy, it is common to design the pitch circle tooth thickness to rim thickness ratio at about 1: 0.6 to 1.2. (See Non-Patent Document 1)

最近、プリンター、複写機等のＯＡ機器の高精度化にともない、これらのＯＡ機器の動力伝達、作動伝達等を行う歯車には、歯車を使用する最も重要な目的である１軸の回転角をその歯数に逆比例して他軸に正しく伝達するか否かを評価する角度伝達誤差の精度が要求されてきている。
しかし、従来技術により、通常の歯車用樹脂を用い、歯車の強度、剛性、低騒音性能、歯の各部要素の形状及び寸法における高度な精度を主体とした歯車の各構成部材の形状、寸法を定める設計においては、例えば、一般的に用いられているポリアセタール樹脂を使用したはすば歯車においては、詳しくは、強度、剛性を考慮した設計の場合、円筒変形が発生し、リムとウエブの交点付近が大きく軸中央に向かってひけるためにJIS B1702(1976)に定められる精度が悪く、結果的に適正な動力伝達を行うことが出来ない。一方、高度な精度を考慮した場合、剛性不足により実際に使用される回転数や回転トルク下で角度伝達誤差が非常に大きくなる。 Recently, with the increase in accuracy of OA equipment such as printers and copiers, the most important purpose of using gears is the rotation angle of one axis, which is the most important purpose of gears for power transmission and operation transmission of these OA equipment. There has been a demand for accuracy of angle transmission error that evaluates whether or not to correctly transmit to other axes in inverse proportion to the number of teeth.
However, according to the prior art, using the usual gear resin, the shape and dimensions of each component of the gear mainly composed of gear strength, rigidity, low noise performance, and high accuracy in the shape and dimensions of each element of the tooth. For example, in the case of a helical gear using polyacetal resin that is generally used, the design that takes into account the strength and rigidity causes a cylindrical deformation and the intersection of the rim and the web. Since the vicinity is large and it moves toward the center of the shaft, the accuracy specified in JIS B1702 (1976) is poor, and as a result, proper power transmission cannot be performed. On the other hand, when high accuracy is taken into account, the angle transmission error becomes very large under the rotational speed and rotational torque actually used due to insufficient rigidity.

そこで、歯１３のピッチ円歯厚Ｓに対するリム厚Ｓｒの比率が１．２倍以上であり、且つ樹脂充填開始から型開き開始までの時間Ｔ３の期間内で、ウエブ１５を加圧成形することを特徴とする樹脂成形歯車の成形方法が知られている。（特許文献１参照）
しかし、従来のエジェクトピン圧縮機構を利用した射出成形での樹脂製歯車の高精度化に対しては、保圧圧力で抑えきれない成形収縮を保圧圧力より大きい機械的な圧力で抑制し、金型への転写性を向上させて樹脂製歯車の高精度化を可能としてきた。従って、従来の加圧成形による樹脂性歯車の高精度化には、大きな圧力を備える特殊仕様の成形機が必要であったり、加圧面積が増える多数個取りの射出成形に対しては不利であった。 Therefore, the web 15 is pressure-molded within a period of time T3 from the start of resin filling to the start of mold opening, where the ratio of the rim thickness Sr to the pitch circle tooth thickness S of the teeth 13 is 1.2 times or more. There is known a method for molding a resin-molded gear characterized by the following. (See Patent Document 1)
However, for higher precision of resin gears in injection molding using the conventional eject pin compression mechanism, molding shrinkage that cannot be suppressed by holding pressure is suppressed by mechanical pressure greater than holding pressure, It has been possible to improve the precision of resin gears by improving the transferability to the mold. Therefore, increasing the precision of conventional resin gears by pressure molding requires a special molding machine with large pressure, or is disadvantageous for multi-cavity injection molding with an increased pressure area. there were.

特開２００２−２３５８３８号公報（請求項１〜１２、段落［００１０］、実施例）JP 2002-235838 A (Claims 1 to 12, paragraph [0010], Example) 「プラスチック成形技術」第１３巻、第８号、１７頁（左側１０行目から１８行目、右側図２）"Plastic molding technology" Vol.13, No.8, p.17 (10th to 18th lines on the left side, Figure 2 on the right side)

本発明は、樹脂成形歯車を、エジェクトピン圧縮機構を備える標準型の成形機を使用して低加圧圧力で高精度に成形し、更には、樹脂成形歯車の多数個取りを可能にすることを目的とする。   According to the present invention, a resin-molded gear is molded with high precision at a low pressure using a standard molding machine equipped with an eject pin compression mechanism, and moreover, a large number of resin-molded gears can be obtained. With the goal.

本発明者は、樹脂成形歯車のウエブを、エジェクトピンを使用して、広い加圧圧力範囲内で局部加圧して成形し、低加圧圧力であっても従来では想定できないほど長時間の加圧圧力を加えることで、高精度歯車の成形が可能であることを見出した。
更に種々の溶融粘度及び半結晶化時間を有する材料樹脂を検討すると同時に、射出開始から冷却工程中に加圧する時期と加圧圧力及びその保持時間を定め、充分な加圧圧力が長時間に渡ってキャビティに加わることが可能な材料樹脂を選定した。
また、樹脂成形歯車の各構成部材の形状および寸法を変化させると同時に、加圧開始時期と加圧圧力及びその保持時間を変化させることにより成形された樹脂歯車の円筒変形とJIS B1702(1976)に定められる精度を、詳細に、総合的に研究することにより、上記課題を解決しうることを見出し、本発明を完成するに至った。 The present inventor has formed a web of a resin-molded gear by applying local pressurization within a wide pressure range using an eject pin, and applying a long time that cannot be assumed in the past even at low pressure. It was found that high precision gears can be formed by applying pressure.
In addition, while studying material resins having various melt viscosities and semi-crystallization times, at the same time, the timing of pressurization during the cooling process from the start of injection, the pressurization pressure, and the holding time are determined, and sufficient pressurization pressure is maintained for a long time. The material resin that can be added to the cavity was selected.
Also, the cylindrical deformation of the resin gear formed by changing the shape and dimensions of each component of the resin molded gear and simultaneously changing the pressure start time, pressure and holding time, and JIS B1702 (1976) The present invention has been completed by finding that the above-mentioned problems can be solved by comprehensively and comprehensively studying the accuracy defined in the above.

即ち、本発明の第１は、円筒状に形成されたリム（１１）、リム（１１）の外周面に円筒の中心軸（１２）から外方向に形成された歯（１３）、リム（１１）の内周面に接合し中心軸（１２）の方向に平円板状に延在するウエブ（１５）、及びウエブ（１５）に接合し中心軸（１２）の心部に形成されたボス類（１６）からなる樹脂成形歯車（１０）を樹脂により一体的に射出成形する方法において、ウエブ（１５）を、加圧圧力Ｐが５〜４５ＭＰａで、充填開始基準で、充填開始からゲートシール終了までの時間Ｔ4の３００〜４００％の加圧開始時期Ｔ1に、加圧を開始し、加圧時間Ｔとして上記時間Ｔ4の１２０〜１５０％の時間、上記加圧圧力範囲内に保持することを特徴とする樹脂成形歯車の成形方法を提供する。
本発明の第２は、ピッチ円歯厚（Ｓ）に対するリム厚（Ｓｒ）の比率が１．６倍以上であり、且つピッチ円歯厚（Ｓ）に対するウエブ厚（Ｓｕ）の比率が２．０倍以上である本発明の第１に記載の樹脂成形歯車の成形方法を提供する。
本発明の第３は、金型温度が樹脂のガラス転移点以上、融点未満の温度で、加圧圧力Ｐが５ＭＰａ以上、３０ＭＰａ未満であることを特徴とする本発明の第１又は２に樹脂成形歯車の成形方法を提供する。
本発明の第４は、金型温度が樹脂の（ガラス転移点＋５０℃）以上、（融点−２０℃）以下であることを特徴とする本発明の第３に記載の樹脂成形歯車の成形方法を提供する。
本発明の第５は、ウエブ（１５）を、樹脂成形歯車を金型から取り出すために使用するエジェクトピン（３７）で加圧することを特徴とする本発明の第１〜４のいずれか１項に記載の樹脂成形歯車の成形方法を提供する。
本発明の第６は、樹脂成形歯車を一度に２個以上成形可能であることを特徴とする本発明の第１〜５のいずれか１項に記載の樹脂成形歯車の成形方法を提供する。
本発明の第７は、樹脂充填後に、ゲート部を機械的に封鎖することを特徴とする本発明の第１〜６のいずれか１項に記載の樹脂成形歯車の成形方法を提供する。
本発明の第８は、樹脂の溶融粘度（ISO 1133によるメルトインデックスに相当する。測定温度は樹脂毎に異なる。）が３５〜４５(ｇ／１０ｍｉｎ)で、半結晶化時間ｔhcが８０〜１２０秒である本発明の第１〜７のいずれか１項に記載の樹脂成形歯車の成形方法を提供する。
本発明の第９は、樹脂が、成形時の収縮率１．０％〜３．０％の熱可塑性樹脂である本発明の第１〜８のいずれか１項に記載の樹脂成形歯車の成形方法を提供する。
本発明の第１０は、樹脂がポリアセタール樹脂である本発明の第１〜９のいずれか１項に記載の樹脂成形歯車の成形方法を提供する。
本発明の第１１は、本発明の第１〜１０のいずれか１項に記載の成形方法により得られる樹脂成形歯車を提供する。
本発明の第１２は、はすば歯車又は平歯車であることを特徴とする本発明の第１１に記載の樹脂成形歯車を提供する。 That is, the first of the present invention is a rim (11) formed in a cylindrical shape, teeth (13) formed on an outer peripheral surface of the rim (11) from a central axis (12) of the cylinder, and a rim (11 ) And a boss formed at the center of the central shaft (12) and joined to the web (15). In the method of integrally injection-molding a resin-molded gear (10) made of resin (16) with resin, the web (15) is gate-sealed from the start of filling on the basis of filling start with a pressure P of 5 to 45 MPa. Pressurization is started at the pressurization start time T1 of 300 to 400% of the time T4 until the end, and the pressurization time T is maintained within the pressurization pressure range for 120 to 150% of the time T4. The molding method of the resin-molded gear characterized by these is provided.
In the second aspect of the present invention, the ratio of the rim thickness (Sr) to the pitch circle tooth thickness (S) is 1.6 times or more, and the ratio of the web thickness (Su) to the pitch circle tooth thickness (S) is 2. The molding method of the resin molded gear according to the first aspect of the present invention, which is 0 times or more, is provided.
A third aspect of the present invention is the resin according to the first or second aspect of the present invention, wherein the mold temperature is a temperature not lower than the glass transition point of the resin and lower than the melting point, and the pressure P is not lower than 5 MPa and lower than 30 MPa. A method for forming a formed gear is provided.
According to a fourth aspect of the present invention, the molding temperature of the resin molded gear according to the third aspect of the present invention is such that the mold temperature is not lower than (glass transition point + 50 ° C.) and not higher than (melting point−20 ° C.) of the resin. I will provide a.
5th of this invention pressurizes a web (15) with the eject pin (37) used in order to take out a resin-molded gear from a metal mold | die, any one of the 1st-4th of this invention characterized by the above-mentioned. The molding method of the resin-molded gear described in 1. is provided.
According to a sixth aspect of the present invention, there is provided the method for molding a resin molded gear according to any one of the first to fifth aspects of the present invention, wherein two or more resin molded gears can be molded at a time.
7th of this invention provides the molding method of the resin molded gear of any one of the 1st-6th of this invention characterized by sealing a gate part mechanically after resin filling.
In the eighth aspect of the present invention, the melt viscosity of the resin (corresponding to the melt index according to ISO 1133. The measurement temperature differs for each resin) is 35 to 45 (g / 10 min), and the half crystallization time t hc is 80 to 80. The molding method of the resin molded gear according to any one of the first to seventh aspects of the present invention, which is 120 seconds.
The ninth of the present invention is the molding of the resin molded gear according to any one of the first to eighth aspects of the present invention, wherein the resin is a thermoplastic resin having a shrinkage rate of 1.0% to 3.0% during molding. Provide a method.
A tenth aspect of the present invention provides the method for molding a resin-molded gear according to any one of the first to ninth aspects of the present invention, wherein the resin is a polyacetal resin.
The eleventh aspect of the present invention provides a resin molded gear obtained by the molding method according to any one of the first to tenth aspects of the present invention.
The twelfth aspect of the present invention provides the resin molded gear according to the eleventh aspect of the present invention, which is a helical gear or a spur gear.

本発明によれば、樹脂成形歯車を、エジェクトピンによる加圧機構を備える標準型の成形機を使用して低加圧圧力で高精度に成形し、更には、樹脂成形歯車の多数個取りを可能にする。
得られた歯車は、複写機・プリンター、ファクシミリ、カメラ、ビデオ、自動車、ＯＡ機器等の部品として使用される。 According to the present invention, a resin-molded gear is molded with high accuracy at a low pressure using a standard molding machine equipped with a pressurizing mechanism using an eject pin. enable.
The obtained gear is used as a part of a copier / printer, a facsimile, a camera, a video, an automobile, an OA device, or the like.

本発明の樹脂成形歯車１０は、円筒状に形成されたリム１１、リム１１の外周面に中心軸１２に対して外方に形成された歯１３、リム１１の内周面に中心軸方向に平円板状に延在するウエブ１５、及びウエブ１５に接合し中心軸心部に形成されたボス類１６からなる（図１参照）。ウエブ１５の設けられる位置は、リム１１の円筒状部分の中間でも上部でも下部でもよい。ボス類１６はボスでも軸でもよい。
樹脂成形歯車１０は、ピッチ円歯厚Ｓに対するリム厚Ｓｒの比率が１．６倍以上、好ましくは２．０以下である。Ｓｒ／Ｓが上記範囲より小さいと、回転伝達誤差が小さい高精度の成形歯車を得ることができない。 The resin molded gear 10 of the present invention includes a rim 11 formed in a cylindrical shape, teeth 13 formed outwardly with respect to the central axis 12 on the outer peripheral surface of the rim 11, and a central axis direction on the inner peripheral surface of the rim 11. It consists of a web 15 extending in the shape of a flat disk and bosses 16 joined to the web 15 and formed at the central axis (see FIG. 1). The position where the web 15 is provided may be in the middle, upper part or lower part of the cylindrical part of the rim 11. The bosses 16 may be bosses or shafts.
In the resin molded gear 10, the ratio of the rim thickness Sr to the pitch circle tooth thickness S is 1.6 times or more, preferably 2.0 or less. If Sr / S is smaller than the above range, a highly accurate formed gear with a small rotation transmission error cannot be obtained.

また、ウエブ１５は平円板状で、リム１１の内周面及びボス１６の外周へ接合される。ピッチ円歯厚Ｓに対して、ウエブ１５の少なくともリム１１及びボス１６への接合部のウエブ厚Ｓｕの比率が、１．５倍以上、好ましくは１．８〜２．０である。ウエブ厚が上記比率の範囲外では十分な円筒精度が得られない。平円板状のウエブ１５は、全面が上記厚みを持つことが好ましいが、必要に応じて、平円板状部分に貫通孔や凹部やリブ等を１つまたは複数個設けてもかまわない。   The web 15 has a flat disk shape and is joined to the inner peripheral surface of the rim 11 and the outer periphery of the boss 16. The ratio of the web thickness Su of the joint portion to at least the rim 11 and the boss 16 of the web 15 to the pitch circle tooth thickness S is 1.5 times or more, preferably 1.8 to 2.0. If the web thickness is out of the above range, sufficient cylindrical accuracy cannot be obtained. The entire surface of the flat disk-like web 15 preferably has the above thickness, but if necessary, one or more through holes, concave parts, ribs, etc. may be provided in the flat disk-like part.

本発明の成形方法は、通常の局部加圧機構を有する標準型の射出成形機、即ち射出力数１００トン程度で、エジェクトピン押出し力数１０トン程度の成形機により行われる。局部加圧機構としては、通常エジェクトピン、スリーブピン、可動式コア等が挙げられ、好ましくはエジェクトピンである。エジェクトピンは、１個の樹脂成形品あたり１個以上、好ましくは２個以上である。
図２に、樹脂の充填及び局部加圧の例を示す。通常の射出成形機を使用して、溶融樹脂がシリンダー側よりゲート３５を経て金型キャビティへ充填される。ゲート３５としては、例えばピンゲートが使用される。ゲートの位置は特に限定するものではなく、ボスの下面でもよいし、側面でもよいし、ウエブ上でもよい。又ゲートの個数も特に限定するものではなく、１個から５，６個でもよい。
局部加圧は、例えば、エジェクトピン３７を用いて行うことができる。エジェクトピン３７の断面形状は丸であっても、四角であってもよく、形状を限定するものではない。又個数に関しても限定するものではない。複数個のエジェクトピン３７による局部加圧は、好ましくは均一に加圧される。
ウエブ１５を円周方向に対して均一に加圧することが好ましい。このため、ウエブ１５上に設定され、中心軸１２に対して同心円状にある２つの円の間で形成されるリング状部分１５’を加圧することが好ましい。リング状部分１５’の面積が、ウエブ１５の面積の、８０〜９０％であるとよい。 The molding method of the present invention is performed by a standard injection molding machine having a normal local pressure mechanism, that is, a molding machine having an ejection force of about 100 tons and an eject pin extrusion force of about 10 tons. Examples of the local pressurizing mechanism include an eject pin, a sleeve pin, a movable core, and the like, and preferably an eject pin. The number of eject pins is one or more, preferably two or more per resin molded product.
FIG. 2 shows an example of resin filling and local pressurization. Using a normal injection molding machine, the molten resin is filled into the mold cavity through the gate 35 from the cylinder side. For example, a pin gate is used as the gate 35. The position of the gate is not particularly limited, and may be the lower surface of the boss, the side surface, or the web. Further, the number of gates is not particularly limited, and may be 1 to 5 or 6.
The local pressurization can be performed using, for example, the eject pin 37. The sectional shape of the eject pin 37 may be round or square, and the shape is not limited. Also, the number is not limited. The local pressurization by the plurality of eject pins 37 is preferably performed uniformly.
It is preferable to pressurize the web 15 uniformly in the circumferential direction. For this reason, it is preferable to pressurize the ring-shaped portion 15 ′ formed between two circles set on the web 15 and concentrically with the central axis 12. The area of the ring-shaped portion 15 ′ is preferably 80 to 90% of the area of the web 15.

樹脂射出充填終了後、保圧が行われる。
樹脂充填開始からゲート部の樹脂が固化するまでの時間をＴ4とすると、Ｔ4は、射出保圧時間と冷却時間の合計を固定し、保圧時間を徐々に増加させ、冷却時間を保圧時間を増加させた分だけ減少させて、スプル、ランナを除く製品重量を測定し、製品重量増加しなくなる射出保圧時間で定義される。 After the resin injection filling is completed, pressure holding is performed.
Assuming that the time from the start of resin filling to the solidification of the resin in the gate is T4, T4 fixes the total injection holding time and cooling time, gradually increases the holding time, and sets the cooling time to the holding time. The product weight excluding the sprue and runner is measured by decreasing the amount by which the product is increased, and is defined as the injection holding time at which the product weight does not increase.

局部加圧するための加圧圧力（即ち、加圧圧力＝[加圧力]／[加圧部の面積]である。）をＰとすると、加圧圧力Ｐは５〜４５ＭＰａ、好ましくは１５〜３０ＭＰａ、さらに好ましくは３０ＭＰａ未満であり、特に好ましくは２５ＭＰａ以下である。
加圧圧力Ｐが上記範囲より小さすぎると、加圧の効果が生じにくく、上記範囲より大きすぎると、加圧による成形品の変形が大きくなり、通常の成形機が使用し難くなったり、多数個取りが困難となる。 When the pressurization pressure for local pressurization (that is, pressurization pressure = [applied pressure] / [area of pressurization section]) is P, the pressurization pressure P is 5 to 45 MPa, preferably 15 to 30 MPa. More preferably, it is less than 30 MPa, and particularly preferably 25 MPa or less.
If the pressurizing pressure P is too smaller than the above range, the effect of pressurizing is difficult to occur. If the pressurizing pressure P is too large, the deformation of the molded product due to pressurization becomes large, making it difficult to use a normal molding machine. It becomes difficult to take pieces.

局部加圧の開始時期、即ち、加圧開始時期Ｔ1は、ゲート部が固化後（即ち、ゲートシール後）であり、充填開始基準で、充填開始からゲートシール終了までの時間Ｔ4の３００〜４００％、好ましくは３４０〜３６０％である。加圧開始時期Ｔ1が上記範囲より早すぎると加圧後の収縮変形が発生し易くなり、遅すぎると加圧の効果が生じ難い。
上記加圧圧力範囲内に保持する加圧時間Ｔとしては、充填開始からゲートシール終了までの時間Ｔ4の１２０〜１５０％の時間、好ましくは１３０〜１４０％の時間である。加圧時間Ｔが上記範囲より短すぎると、加圧の効果が生じ難くなり、長すぎると変形が生じやすい。 The local pressurization start timing, that is, pressurization start timing T1 is after the gate portion is solidified (that is, after the gate seal), and 300 to 400 of time T4 from the start of filling to the end of the gate seal on the basis of filling start. %, Preferably 340 to 360%. If the pressurization start timing T1 is too early than the above range, shrinkage deformation after pressurization tends to occur, and if it is too late, the effect of pressurization hardly occurs.
The pressurization time T held within the above pressurization pressure range is 120 to 150%, preferably 130 to 140% of the time T4 from the start of filling to the end of the gate seal. If the pressurization time T is too short than the above range, the effect of pressurization is difficult to occur, and if it is too long, deformation tends to occur.

本発明で使用できる樹脂は、熱可塑性樹脂であり、好ましくは結晶性樹脂である。樹脂は、溶融粘度（ISO 1133に基づいて測定されたメルトインデックス（MI）に相当する。測定温度は樹脂毎に異なる。）が９〜４５ｇ／１０ｍｉｎ、好ましくは３５〜４５ｇ／１０ｍｉｎである。但し、溶融粘度測定温度は樹脂毎に異なる。
溶融粘度が上記範囲より小さい樹脂を用いると圧力伝達が不十分となるため歯車の精度が不十分となり、上記範囲より大きい樹脂を用いると固化速度が速く加圧の効果が低下する。
上記樹脂は、上記溶融粘度に加えて、半結晶化時間ｔhcが３０〜２００秒、好ましくは８０〜１２０秒である。半結晶化時間ｔhcが上記範囲より短い樹脂を用いると固化が速くて加圧の効果が低下し、長い樹脂を用いると固化が遅くなり、成形サイクルが長くなる。
半結晶化時間ｔhcは、次のように測定される。
装置として示差走査熱量計等を使用し、融点＋４０℃で、５分間溶融状態に維持後、１０℃／分で降温し、融点に保持し、融点到達後結晶化発熱曲線のピークトップが出るまでの時間である。 The resin that can be used in the present invention is a thermoplastic resin, preferably a crystalline resin. The resin has a melt viscosity (corresponding to a melt index (MI) measured based on ISO 1133. The measurement temperature varies depending on the resin) of 9 to 45 g / 10 min, preferably 35 to 45 g / 10 min. However, the melt viscosity measurement temperature differs for each resin.
If a resin having a melt viscosity smaller than the above range is used, pressure transmission becomes insufficient, and the gear accuracy becomes insufficient. If a resin having a melt viscosity larger than the above range is used, the solidification speed is high and the effect of pressurization is reduced.
In addition to the melt viscosity, the resin has a half-crystallization time t hc of 30 to 200 seconds, preferably 80 to 120 seconds. If a resin having a half crystallization time t hc shorter than the above range is used, the solidification is fast and the effect of pressurization is reduced. If a long resin is used, the solidification is slowed down and the molding cycle becomes long.
The half crystallization time t hc is measured as follows.
Use a differential scanning calorimeter or the like as an apparatus, maintain the molten state at a melting point + 40 ° C. for 5 minutes, lower the temperature at 10 ° C./minute, hold the melting point, and reach the peak top of the crystallization exothermic curve after reaching the melting point Is the time.

上記樹脂は、成形時の収縮率が１．０％〜３．０％である熱可塑性樹脂を用いることが好ましい。従来の技術では、この範囲の成形収縮率を有する樹脂を使用すると、成形時の樹脂収縮により成形品と金型形状との寸法差が大きくなり、十分に高精度の歯車を得ることが至難であった。   It is preferable to use a thermoplastic resin having a shrinkage ratio of 1.0% to 3.0% during molding. In the prior art, if a resin having a molding shrinkage rate in this range is used, the dimensional difference between the molded product and the mold shape increases due to resin shrinkage during molding, and it is difficult to obtain a sufficiently accurate gear. there were.

本発明で使用される樹脂は、具体的には、ポリアセタール樹脂、ポリブチレンテレフタレート樹脂、ポリエチレンテレフタレート樹脂、ポリフェニレンサルファイド樹脂又はポリアミド樹脂等が挙げられる。中でも、ポリアセタール樹脂（ＰＯＭ）が、特に好ましく使用できる。   Specific examples of the resin used in the present invention include polyacetal resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, and polyamide resin. Among these, polyacetal resin (POM) can be particularly preferably used.

上記ポリアセタール樹脂は、ホモポリマー、コポリマーのいずれであってもよい。コポリマーの場合には、主鎖の安定化のためにエチレンオキサイド、ジオキソラン等の単量体成分がランダムに共重合されたもの、あるいはブロツクあるいはグラフト重合されたもの、あるいは更に第三成分が導入されたもの等、いかなる共重合形態であってもかまわない。
上記ポリブチレンテレフタレート、ポリエチレンテレフタレート等のポリエステル樹脂は、通常の芳香族ジカルボン酸成分、脂肪族ジオール成分の他に、イソフタル酸、ナフタレンジカルボン酸、アジピン酸等の芳香族又は脂肪族多塩基酸、あるいは、グリコール成分としてエチレングリゴール、ジエチレングリコール、ネオペンチルグリコール等のアルキレングリコールやビスフェノールＡ等の芳香族ヒドロキシ化合物等を用いて変性させて得られる共重合体であってもかまわない。
これらの樹脂は、通常添加される各種添加剤が配合されていてもよいし、これらを主体とする樹脂組成物であってもよい。 The polyacetal resin may be either a homopolymer or a copolymer. In the case of a copolymer, a monomer component such as ethylene oxide or dioxolane is randomly copolymerized, block or graft polymerized, or a third component is introduced to stabilize the main chain. Any form of copolymerization such as rice cake may be used.
Polyester resins such as polybutylene terephthalate and polyethylene terephthalate, in addition to normal aromatic dicarboxylic acid components and aliphatic diol components, aromatic or aliphatic polybasic acids such as isophthalic acid, naphthalenedicarboxylic acid, and adipic acid, or Further, it may be a copolymer obtained by modification using an alkylene glycol such as ethylene glycol or diethylene glycol or neopentyl glycol or an aromatic hydroxy compound such as bisphenol A as a glycol component.
These resins may be blended with various additives that are usually added, or may be a resin composition mainly composed of these additives.

本発明の樹脂成形歯車１０としては、平歯車、はすば歯車、やまば歯車、すぐばかさ歯車、まがりばかさ歯車、ねじば歯車などが挙げられる。歯のねじれ角度は、特に限定されるものではない。
またこれらのはすば歯車や平歯車等はシングル歯車や２段歯車に、または、駆動モータから多段に組み合わせて回転ムラをなくして減速するようにした、組合わせ歯車であってもよい。 Examples of the resin molded gear 10 of the present invention include a spur gear, a helical gear, a helical gear, a short bevel gear, a spiral bevel gear, and a helical gear. The twist angle of the teeth is not particularly limited.
These helical gears and spur gears may be a single gear, a two-stage gear, or a combination gear that is combined in multiple stages from the drive motor and decelerates without rotational unevenness.

（実施例）
以下、実施例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。 (Example)
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

（比較例１）
結晶性ポリマーであるポリアセタール樹脂として、ジュラコンTMJW-03（ポリプラスチックス(株)製、溶融粘度（MI:４５ｇ／１０分（190℃））、歯車を成形する上で好ましい推奨保圧力１００ＭＰａ、ｔhc８７秒、Tm１７５℃、Tg−５０℃）を使用し、下記のハスバ歯車を成形して、歯車の精度を（１）最大半径差（円筒幅方向に５箇所、外径を測定し、それから求めた最大半径と最小半径の差である。）、（２）歯形形状誤差、（３）歯筋形状誤差について評価した。結果を表１に示す。
ポリアセタール樹脂の半結晶化時間ｔhcは、次のように測定した。
装置としてパーキンエルマー社製示差走査熱量計ＤＳＣ７型を使用し、サンプル約５ｍｇを２００℃×５分間溶融状態に維持後、１０℃/分で降温し、１５２℃に達した時点で温度を一定に保持し、１５２℃到達後結晶化発熱曲線のピークのトップが現れるまでの時間である。
成形品歯車諸元:モジュール１、歯数２８、圧力角２０#、ネジレ角（右）２０#、歯幅１５mm、ピッチ円直径２９．７９７mm、歯先円外径３１．７９７mm、ウエブ厚３mm、リム厚２．５mm
成形機:住友重機械工業(株）製ＳＥ−１００Ｄ
溶融樹脂温度：２００℃
金型温度：６０℃
射出速度：１７mm/秒
充填時間：０．８秒
保圧圧力：１００ＭＰａ（推奨保圧圧力）
充填開始からゲートシール終了までの時間Ｔ4：６秒
エジェクトピン加圧力：３．４ton（本成形機のエジェクト力の最大値である）
エジェクトピン加圧断面積：２６２．３２mm2
エジェクトピン加圧圧力：１２０ＭＰａ
エジェクトピンストローク量:１．２mm
エジェクトピン加圧開始時期Ｔ1:２０秒後
エジェクトピン加圧時間Ｔ：８秒間
歯車１個取り (Comparative Example 1)
As polyacetal resin which is a crystalline polymer, Duracon TM JW-03 (manufactured by Polyplastics Co., Ltd., melt viscosity (MI: 45 g / 10 min (190 ° C)), preferable recommended holding pressure of 100 MPa for molding gears, t hc 87 seconds, Tm 175 ° C, Tg-50 ° C), forming the following helical gear, and (1) measuring the accuracy of the gear (1) maximum radius difference (5 locations in the cylinder width direction, outer diameter, It is the difference between the maximum radius and the minimum radius determined from that.) (2) Tooth shape error, (3) Tooth shape error. The results are shown in Table 1.
The semi-crystallization time t hc of the polyacetal resin was measured as follows.
Using a differential scanning calorimeter DSC7 manufactured by PerkinElmer as a device, about 5 mg of sample is maintained in a molten state at 200 ° C. for 5 minutes, then the temperature is lowered at 10 ° C./minute, and when the temperature reaches 152 ° C., the temperature is kept constant. This is the time until the top of the peak of the crystallization exothermic curve appears after reaching 152 ° C.
Molded gear specifications: Module 1, number of teeth 28, pressure angle 20 #, torsion angle (right) 20 #, tooth width 15mm, pitch circle diameter 29.797mm, tip circle diameter 31.797mm, web thickness 3mm, Rim thickness 2.5mm
Molding machine: SE-100D manufactured by Sumitomo Heavy Industries, Ltd.
Molten resin temperature: 200 ° C
Mold temperature: 60 ℃
Injection speed: 17 mm / sec Filling time: 0.8 sec Holding pressure: 100 MPa (recommended holding pressure)
Time from the start of filling to the end of gate seal T4: 6 seconds Ejecting pin pressure: 3.4 ton (this is the maximum ejecting force of this molding machine)
Eject pin pressure cross section: 262.32 mm 2
Eject pin pressure: 120 MPa
Eject pin stroke amount: 1.2mm
Eject pin pressurization start time T1: 20 seconds later Eject pin pressurization time T: 8 seconds Take one gear

（比較例２）
ポリアセタール樹脂として、ジュラコンTMM270-44（ポリプラスチックス(株)製、溶融粘度（MI:２７ｇ／１０分（190℃））、推奨保圧力１００ＭＰａ、ｔhc３７秒、Tm１６２℃、Tg−６０℃）を使用した他は比較例１と同様に行った。結果を表１に示す。 (Comparative Example 2)
As a polyacetal resin, Duracon TM M270-44 (manufactured by Polyplastics Co., Ltd., melt viscosity (MI: 27 g / 10 min (190 ° C.)), recommended holding pressure 100 MPa, t hc 37 seconds, Tm 162 ° C., Tg-60 ° C. ) Was carried out in the same manner as in Comparative Example 1. The results are shown in Table 1.

（実施例１および２）
エジェクトピンの加圧圧力及び加圧開始時期を、表１に示す条件に変え、歯車を１又は２個取りにした以外は比較例１と同様に行い、歯車の精度を評価した。結果を表１に示す。 (Examples 1 and 2)
The accuracy of the gears was evaluated in the same manner as in Comparative Example 1 except that the pressurization pressure and pressurization start timing of the eject pin were changed to the conditions shown in Table 1 and one or two gears were used. The results are shown in Table 1.

（実施例３）
ポリアセタール樹脂として、前記ジュラコンTMM270-44を使用した他は実施例１と同様に行った。結果を表１に示す。 (Example 3)
The same procedure as in Example 1 was performed except that the Duracon ™ M270-44 was used as the polyacetal resin. The results are shown in Table 1.

低加圧圧力で成形すると、加圧開始時期が、保圧終了後であって、充填開始基準で１８秒後から２０秒後の間であると、歯筋精度を中心とする寸法精度を従来の条件より向上させることが可能となった。比較例では、加圧圧力１２０ＭＰａでは加圧開始時期２０秒でやや良くなったが、加圧開始時期は非常に狭い範囲であり、成形しにくい。
また従来の４分の１程度の加圧圧力で寸法精度を満足することから、一般的にエジェクトピン加圧を装備している標準成形機においても実現可能レベルである。同時に低圧加圧であるために、多数個取りにも有効である。 When molding is performed at a low pressurizing pressure, when the pressurization start time is after the end of the pressure holding and between 18 seconds and 20 seconds after the filling start reference, the dimensional accuracy centering on the tooth trace accuracy is conventionally achieved. It has become possible to improve from the above conditions. In the comparative example, the pressurization start time was slightly improved at a pressurization start time of 20 seconds at a pressurization pressure of 120 MPa. However, the pressurization start time is in a very narrow range and is difficult to be molded.
In addition, since the dimensional accuracy is satisfied with a pressure of about one-fourth of the conventional pressure, it is generally a feasible level in a standard molding machine equipped with an eject pin pressure. At the same time, because of the low-pressure pressurization, it is effective for multi-cavity picking.

本発明の樹脂成形歯車の一例の縦断面図である。It is a longitudinal cross-sectional view of an example of the resin molded gear of this invention. 図１に示す樹脂成形歯車を成形する金型の断面図である。It is sectional drawing of the metal mold | die which shape | molds the resin molding gear shown in FIG.

符号の説明Explanation of symbols

１０ 樹脂成形歯車
１１ リム
１２ 中心軸
１３ 歯
１５ ウエブ
１５’リング状部分
１６ ボス類
３１ 歯車入れ子
３２ ラジアルころがり軸受け
３３ スラストころがり軸受け
３５ ゲート
３７ エジェクトピン
Ｄ 歯先円直径
ｂ 歯幅
Ｓ ピッチ円歯厚
Ｓｒ リム厚
Ｓｕ ウエブ厚 10 resin molded gear 11 rim 12 central shaft 13 teeth 15 web 15 'ring-shaped portion 16 bosses 31 gear insert 32 radial rolling bearing 33 thrust rolling bearing 35 gate 37 eject pin D tooth tip diameter b tooth width S pitch circle tooth thickness Sr Rim thickness Su Web thickness

Claims (10)

円筒状に形成されたリム（１１）、リム（１１）の外周面に円筒の中心軸（１２）から外方向に形成された歯（１３）、リム（１１）の内周面に接合し中心軸（１２）の方向に平円板状に延在するウエブ（１５）、及びウエブ（１５）に接合し中心軸（１２）の心部に形成されたボス類（１６）からなる樹脂成形歯車（１０）を樹脂により一体的に射出成形する方法において、
ウエブ（１５）を、加圧圧力Ｐが５〜４５ＭＰａで、充填開始基準で、充填開始からゲートシール終了までの時間Ｔ4の３００〜４００％の加圧開始時期Ｔ1に、加圧を開始し、加圧時間Ｔとして上記時間Ｔ4の１２０〜１５０％の時間、上記加圧圧力範囲内に保持することを特徴とする樹脂成形歯車の成形方法。 The rim (11) formed in a cylindrical shape, the teeth (13) formed outward from the central axis (12) of the cylinder on the outer peripheral surface of the rim (11), and the center joined to the inner peripheral surface of the rim (11) A resin molded gear comprising a web (15) extending in the shape of a flat disk in the direction of the shaft (12), and a boss (16) joined to the web (15) and formed at the center of the central shaft (12) (10) In the method of injection molding integrally with resin,
The pressurization of the web (15) is started at the pressurization start timing T1 of 300 to 400% of the time T4 from the start of filling to the end of the gate seal on the basis of the start of filling at a pressurizing pressure P of 5 to 45 MPa, A method for molding a resin-molded gear, wherein the pressurizing time T is maintained within the range of the pressurizing pressure for 120 to 150% of the time T4. ピッチ円歯厚（Ｓ）に対するリム厚（Ｓｒ）の比率が１．６倍以上であり、且つピッチ円歯厚（Ｓ）に対するウエブ厚（Ｓｕ）の比率が２．０倍以上である請求項１に記載の樹脂成形歯車の成形方法。   The ratio of the rim thickness (Sr) to the pitch circle tooth thickness (S) is 1.6 times or more, and the ratio of the web thickness (Su) to the pitch circle tooth thickness (S) is 2.0 times or more. 2. A molding method for a resin-molded gear according to 1. 金型温度が樹脂のガラス転移点以上、融点未満の温度で、加圧圧力Ｐが５ＭＰａ以上、３０ＭＰａ未満であることを特徴とする請求項１又は２に記載の樹脂成形歯車の成形方法。 The molding method for a resin-molded gear according to claim 1 or 2, wherein the mold temperature is a temperature not lower than the glass transition point of the resin and lower than the melting point, and the pressure P is not lower than 5 MPa and lower than 30 MPa. 金型温度が樹脂の（ガラス転移点＋５０℃）以上、（融点−２０℃）以下であることを特徴とする請求項３に記載の樹脂成形歯車の成形方法。   4. The method for molding a resin-molded gear according to claim 3, wherein the mold temperature is not less than (glass transition point + 50 ° C.) and not more than (melting point−20 ° C.) of the resin. ウエブ（１５）を、樹脂成形歯車を金型から取り出すために使用するエジェクトピン（３７）で加圧することを特徴とする請求項１〜４のいずれか１項に記載の樹脂成形歯車の成形方法。   The method for molding a resin-molded gear according to any one of claims 1 to 4, wherein the web (15) is pressurized with an eject pin (37) used for removing the resin-molded gear from the mold. . 樹脂成形歯車を一度に２個以上成形可能であることを特徴とする請求項１〜５のいずれか１項に記載の樹脂成形歯車の成形方法。   6. The method for molding a resin molded gear according to claim 1, wherein two or more resin molded gears can be molded at a time. 樹脂充填後に、ゲート部を機械的に封鎖することを特徴とする請求項１〜６のいずれか１項に記載の樹脂成形歯車の成形方法。   The method for molding a resin-molded gear according to any one of claims 1 to 6, wherein the gate portion is mechanically sealed after resin filling. 樹脂の溶融粘度（ISO 1133によるメルトインデックスに相当する。測定温度は樹脂毎に異なる。）が３５〜４５(ｇ／１０ｍｉｎ)で、半結晶化時間ｔhcが８０〜１２０秒である請求項１〜７のいずれか１項に記載の樹脂成形歯車の成形方法。 The melt viscosity of the resin (corresponding to the melt index according to ISO 1133. The measurement temperature differs for each resin) is 35 to 45 (g / 10 min), and the half-crystallization time t hc is 80 to 120 seconds. The molding method of the resin molded gear of any one of -7. 樹脂が、成形時の収縮率１．０％〜３．０％の熱可塑性樹脂である請求項１〜８のいずれか１項に記載の樹脂成形歯車の成形方法。   The method of molding a resin molded gear according to any one of claims 1 to 8, wherein the resin is a thermoplastic resin having a shrinkage ratio of 1.0% to 3.0% during molding. 樹脂がポリアセタール樹脂である請求項１〜９のいずれか１項に記載の樹脂成形歯車の成形方法。   The resin molding gear molding method according to any one of claims 1 to 9, wherein the resin is a polyacetal resin.
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