JP2007093012A

JP2007093012A - Molded gear

Info

Publication number: JP2007093012A
Application number: JP2006312950A
Authority: JP
Inventors: Toru Hagiwara; 徹萩原
Original assignee: Enplas Corp
Current assignee: Enplas Corp
Priority date: 2006-11-20
Filing date: 2006-11-20
Publication date: 2007-04-12

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molded gear which can secure the precision of a tooth profile, and can sufficiently secure the strength of teeth. <P>SOLUTION: Saved portions 11 smoothly recessed from the inner periphery of a rim 3 toward the tool tip are formed on the inner peripheral side of the rim 3 at the portions where the teeth 10 are to be formed. Therefore, a difference in the thickness between the portions having the teeth 10 formed thereon and the portions having no teeth thereon (the portions of bottom lands 12) is reduced, and as a result, the difference of the cooling and solidifying time between the portions having the teeth 10 formed thereon and other portions can be reduced. As a result, the generation of shrinkages and voids can be prevented to secure the strength sufficient for transmitting the power, and also the tooth profile can be accurately formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

この発明は、溶融材料（プラスチック（ポリアセタール，ポリアミド等）、金属（マグネシウム合金，アルミニウム合金等））を型内で固化させることにより成形されるモールドギヤに関する。 The present invention relates to a molded gear formed by solidifying a molten material (plastic (polyacetal, polyamide, etc.), metal (magnesium alloy, aluminum alloy, etc.)) in a mold.

例えば、プラスチックを射出成形することにより成形されるモールドギヤ２１であって、図６〜図７に示すようなモールドギヤ２１は、リム３の外周に複数の歯１０が形成されており、歯１０が形成された部分と歯１０が形成されてない部分（歯底１２に対応する部分）の肉厚の差が大きいため、これら部分の金型内での冷却・固化に要する時間に差が生じ、リム３の歯底１２に対応する部分が先に冷却・固化し、歯１０が形成されている部分が遅れて冷却・固化する。その結果、このようなモールドギヤ２１は、歯１０が形成された部分の肉が先に冷却・固化する歯底１２側に引っ張られ、歯１０が形成された部分にヒケ１４やボイド１５が発生しやすいという問題や、歯形精度を確保するのが難しいという問題を有している。 For example, the mold gear 21 is formed by injection molding of plastic, and the mold gear 21 as shown in FIGS. 6 to 7 has a plurality of teeth 10 formed on the outer periphery of the rim 3, and the teeth 10 are formed. Since there is a large difference in wall thickness between the formed portion and the portion where the tooth 10 is not formed (the portion corresponding to the tooth bottom 12), there is a difference in the time required for cooling and solidifying these portions in the mold. The portion corresponding to the third tooth bottom 12 is cooled and solidified first, and the portion where the tooth 10 is formed is delayed and cooled and solidified. As a result, the mold gear 21 is pulled toward the root 12 where the meat in the portion where the teeth 10 are formed is cooled and solidified first, and sink marks 14 and voids 15 are generated in the portion where the teeth 10 are formed. There is a problem that it is easy and it is difficult to ensure the tooth profile accuracy.

そこで、図８に示すように、歯形に沿った凹部２２を各歯１０に形成し、歯１０の肉厚を均一化し、歯形精度を確保するようにしたモールドギヤ２３が既に案出された（特許文献１参照）。
特開平４−２３６８４８号公報 Therefore, as shown in FIG. 8, a molded gear 23 has been devised in which recesses 22 along the tooth profile are formed in each tooth 10, the thickness of the tooth 10 is made uniform, and the tooth profile accuracy is ensured (patent). Reference 1).
JP-A-4-236848

しかしながら、図８に示すようなモールドギヤ２３は、歯形精度を確保することは容易であるが、歯形に沿った凹部２２を形成しないモールドギヤ２１（図７参照）に比較して強度が著しく劣るため、動力伝達機構に使用することが難しいという不具合を有している。 However, the mold gear 23 as shown in FIG. 8 is easy to ensure the tooth profile accuracy, but the strength is significantly inferior to the mold gear 21 (see FIG. 7) that does not form the recess 22 along the tooth profile. There is a problem that it is difficult to use the power transmission mechanism.

そこで、本発明は、歯形精度を確保できると共に、歯の強度を充分に確保できるモールドギヤを提供することを目的とする。 Then, an object of this invention is to provide the mold gear which can ensure a tooth profile precision and can fully ensure the intensity | strength of a tooth | gear.

請求項１の発明は、溶融材料を型内で固化させ、リムの外周に複数の歯を形成してなるモールドギヤであって、前記リムの内周側で且つ各歯に対応する位置に、リムの内周から歯先側へ向かって滑らかに凹む肉ぬすみ部を形成したことを特徴としている。 The invention of claim 1 is a mold gear in which a molten material is solidified in a mold and a plurality of teeth are formed on the outer periphery of the rim, and the rim is positioned on the inner peripheral side of the rim and corresponding to each tooth. It is characterized in that a meat thinning portion that is smoothly recessed from the inner periphery to the tooth tip side is formed.

請求項２の発明は、溶融材料を型内で固化させ、リムの外周に複数の歯を形成してなるモールドギヤであって、前記リムの内周を、各歯に対応する位置において歯先側へ滑らかに凹み、各歯底に対応する位置において回転中心側へ滑らかに出っ張る波形曲面形状にしたことを特徴としている。 The invention according to claim 2 is a mold gear in which the molten material is solidified in a mold and a plurality of teeth are formed on the outer periphery of the rim, and the inner periphery of the rim is on the tooth tip side at a position corresponding to each tooth. It is characterized by having a corrugated curved surface that dents smoothly and protrudes smoothly toward the center of rotation at a position corresponding to each tooth bottom.

本発明は、ヒケやボイドが発生し易い歯に対応するリムの内周側に、リムの内周から歯先側へ向かって滑らかに凹む肉ぬすみ部が形成されており、歯が形成された部分と歯が形成されない部分（歯底部分）との肉厚の差を小さくし、歯が形成された部分と他部との冷却・固化時間の差を小さくするようになっているため、ヒケやボイドの発生を防止でき、動力伝達が可能な充分な強度を確保できると共に、歯形を高精度に成形することが可能になる。 In the present invention, on the inner peripheral side of the rim corresponding to a tooth where sink marks and voids are likely to occur, a meat thinning portion that is smoothly dented from the inner periphery of the rim toward the tooth tip side is formed, and the tooth is formed. The difference in thickness between the part and the part where the teeth are not formed (the root part) is reduced, and the difference between the cooling and setting time between the part where the teeth are formed and the other part is reduced. Generation of voids and voids can be prevented, sufficient strength capable of power transmission can be secured, and the tooth profile can be formed with high accuracy.

以下、本発明の最良の実施の形態を図面に基づき詳述する。
［第１の実施の形態］
図１〜図３は、溶融プラスチックを金型に形成されたキャビティ内で冷却・固化させてなるモールドギヤ（射出成形ギヤ）１を示すものである。これらの図に示すように、モールドギヤ１は、ボス２とリム３が略円板状のウェブ４により接続され、リム３の半径方向内方近傍にウェブ４の両面から突出するリング状リブ５が形成されると共に、このリング状リブ５とボス２を放射状に接続する複数のアーム状リブ６がウェブ４の両面から突出するように形成されている。 The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
[First Embodiment]
1 to 3 show a mold gear (injection molding gear) 1 formed by cooling and solidifying molten plastic in a cavity formed in a mold. As shown in these drawings, the molded gear 1 has a boss 2 and a rim 3 connected by a substantially disc-shaped web 4, and ring-shaped ribs 5 projecting from both surfaces of the web 4 in the radially inward vicinity of the rim 3. At the same time, a plurality of arm-shaped ribs 6 that radially connect the ring-shaped rib 5 and the boss 2 are formed so as to protrude from both surfaces of the web 4.

このうち、ボス２には、軸７に嵌合される軸穴８が形成されている。又、ウェブ４は、ボス２の軸方向略中央部とリム３の幅方向略中央部を接続するようになっており、リング状リブ５及びアーム状リブ６で補強されることを考慮して、可能な限り薄い肉厚でほぼ均一に形成されている。又、リング状リブ５及びアーム状リブ６は、その側面５ａ，５ａ（６ａ，６ａ）間の幅寸法Ｗ１がリム３の幅寸法Ｗ２よりも小さくなるように形成されており、その側面５ａ，５ａ（６ａ，６ａ）がリム３の側面３ａ，３ａやボス２の側面２ａ，２ａよりも外側（図３の左右方向）へ出っ張るようなことがない。 Among these, the boss 2 is formed with a shaft hole 8 to be fitted to the shaft 7. Further, the web 4 is connected to the substantially central portion in the axial direction of the boss 2 and the substantially central portion in the width direction of the rim 3, and is considered to be reinforced by the ring-shaped rib 5 and the arm-shaped rib 6. It is almost uniformly formed with the smallest possible wall thickness. The ring-shaped rib 5 and the arm-shaped rib 6 are formed such that the width dimension W1 between the side surfaces 5a, 5a (6a, 6a) is smaller than the width dimension W2 of the rim 3, and the side surfaces 5a, 5a (6a, 6a) does not protrude beyond the side surfaces 3a, 3a of the rim 3 and the side surfaces 2a, 2a of the boss 2 (in the left-right direction in FIG. 3).

リム３の外周側には複数の歯１０が形成されており、リム３の内周側には滑らかな曲面で形成された肉ぬすみ部１１が形成されている。この肉ぬすみ部１１は、歯１０に対応する部位がリム３の内周側から歯先側へ向かって滑らかに凹む円弧状の曲面になっている。そして、隣り合う肉ぬすみ部１１，１１間は、歯底１２側から回転中心側へ滑らかに出っ張る円弧状の曲面１３になっており、これら肉ぬすみ部１１と曲面１３が滑らかに接続されて波形曲面形状になっている。 A plurality of teeth 10 are formed on the outer peripheral side of the rim 3, and a meat thinning portion 11 formed with a smooth curved surface is formed on the inner peripheral side of the rim 3. The meat thinning portion 11 has an arcuate curved surface in which a portion corresponding to the tooth 10 is smoothly recessed from the inner peripheral side of the rim 3 toward the tooth tip side. And between the adjacent meat thinning portions 11 and 11 is an arcuate curved surface 13 that protrudes smoothly from the tooth bottom 12 side to the rotation center side, and the meat thinning portion 11 and the curved surface 13 are smoothly connected and corrugated. It has a curved shape.

この肉ぬすみ部１１が形成された部分（リム３の歯１０に対応する部分）は、図７に示すように、ヒケ１４やボイド１５が発生し易い部分である。しかし、本実施の形態は、図１〜図３に示すように、肉ぬすみ部１１がリム３の内周側に形成されることにより、歯１０が形成された部分と歯１０が形成されない部分（歯底１２部分）との肉厚の差が小さくなり、歯１０が形成された部分と他部との冷却・固化時間の差を小さくすることができるため、ヒケ１４、ボイド１５やその他の成形不良（例えば、歯の反り）の発生を防止できると共に、歯形や歯すじなどの歯車形状を高精度に成形することが可能になる。 As shown in FIG. 7, the portion where the thinned portion 11 is formed (the portion corresponding to the tooth 10 of the rim 3) is a portion where sink marks 14 and voids 15 are easily generated. However, in the present embodiment, as shown in FIG. 1 to FIG. 3, a portion where the teeth 10 are formed and a portion where the teeth 10 are not formed by forming the meat thinning portion 11 on the inner peripheral side of the rim 3. Since the difference in wall thickness with the (tooth 12 portion) is reduced and the difference in cooling / solidifying time between the portion where the tooth 10 is formed and the other portion can be reduced, sink marks 14, voids 15 and other It is possible to prevent the occurrence of molding defects (for example, tooth warpage) and to form gear shapes such as tooth shapes and tooth lines with high accuracy.

又、本実施の形態のモールドギヤ１は、肉ぬすみ部１１がリム３の内周側に形成されており、肉ぬすみ部１１が歯１０に食い込むようなことがなく、歯１０の強度を損なうことがないため、確実且つ高精度の動力伝達が可能になる。 Further, in the molded gear 1 of the present embodiment, the thinned portion 11 is formed on the inner peripheral side of the rim 3, and the thinned portion 11 does not bite into the teeth 10, and the strength of the teeth 10 is impaired. Therefore, reliable and highly accurate power transmission becomes possible.

尚、ウェブ４の肉厚が厚いと、ウェブ４とリム３の接続部及びその近傍の冷却・固化が遅れ、成形時の収縮により歯面部精度が悪化する。しかし、本実施の形態のモールドギヤ１は、リング状リブ５及びアーム状リブ６によりウェブ４の強度が補強されるようになっているため、ウェブ４の肉厚を極力薄くすることができ、成形時の収縮に起因する歯面部精度の悪化を防止することができる。従って、本実施の形態のモールドギヤ１は、前記肉ぬすみ部１１を形成することの効果と相俟って、高精度の歯形が形成される。 If the web 4 is thick, cooling and solidification of the connecting portion of the web 4 and the rim 3 and the vicinity thereof is delayed, and the tooth surface accuracy is deteriorated due to shrinkage during molding. However, since the strength of the web 4 is reinforced by the ring-shaped rib 5 and the arm-shaped rib 6 in the molded gear 1 of the present embodiment, the thickness of the web 4 can be reduced as much as possible. It is possible to prevent the deterioration of the tooth surface accuracy due to the time contraction. Therefore, the mold gear 1 of the present embodiment forms a highly accurate tooth profile in combination with the effect of forming the thinned portion 11.

又、本実施の形態は、図３及び図５に示すように、射出成形時のゲート１６の位置をウェブ４の部分に配置し、エジェクトピン１７の押圧位置をリング状リブ５とアーム状リブ６との接続部側面に配置してあり、リング状リブ５とアーム状リブ６との接続部側面やウェブ４がリム３の側面３ａ，３ａ及びボス２の側面２ａ，２ａよりも外側へ出っ張ることがないため、ゲート痕やエジェクトピンの押圧痕があっても、モールドギヤ１の組み付け作業に不都合を生じることがない。 Further, in this embodiment, as shown in FIGS. 3 and 5, the position of the gate 16 at the time of injection molding is arranged on the web 4 portion, and the pressing position of the eject pin 17 is set to the ring-shaped rib 5 and the arm-shaped rib. 6 is disposed on the side surface of the connecting portion with the ring-shaped rib 5, and the side surface of the connecting portion between the ring-shaped rib 5 and the arm-shaped rib 6 and the web 4 protrude outward from the side surfaces 3 a and 3 a of the rim 3 and the side surfaces 2 a and 2 a of the boss 2. Therefore, there is no inconvenience in the assembly work of the mold gear 1 even if there is a gate mark or a pressing mark on the eject pin.

又、本実施の形態は、リム３の内周に形成される肉ぬすみ部１１が滑らかな円弧形状であり、リム３の内周全体が滑らかな波形曲面形状に形成されているため、肉ぬすみ部１１に応力が集中することによる強度低下を生じることがない。
［第２の実施の形態］
図４は、本発明の第２の実施の形態に係るモールドギヤ１のリム３の一部を拡大して示す図である。尚、本実施の形態に係るモールドギヤ１は、リム３の内周側の形状のみが前記第１の実施の形態と相違するので、前記第１の実施の形態と同一の構成については省略して説明する。 Further, in the present embodiment, the thinned portion 11 formed on the inner periphery of the rim 3 has a smooth arc shape, and the entire inner periphery of the rim 3 is formed in a smooth corrugated curved surface shape. The strength does not decrease due to the concentration of stress on the portion 11.
[Second Embodiment]
FIG. 4 is an enlarged view showing a part of the rim 3 of the molded gear 1 according to the second embodiment of the present invention. Note that the molded gear 1 according to the present embodiment is different from the first embodiment only in the shape of the inner periphery side of the rim 3, and therefore the same configuration as that of the first embodiment is omitted. explain.

この図４に示すように、本実施の形態に係るモールドギヤ１は、リム３の内周側で且つ各歯１０に対応する位置に、リム３の内周面３ｂから歯先側へ向かって円弧状に滑らかに凹む肉ぬすみ部１１が形成されている。そして、この肉ぬすみ部１１とリム３の内周面３ｂとの接続部がＲ面取りされ、肉ぬすみ部１１とリム３の内周面３ｂが滑らかに接続されており、肉ぬすみ部１１とリム３の内周面３ｂとの接続部に応力が集中しないように工夫されている。 As shown in FIG. 4, the mold gear 1 according to the present embodiment has a circular shape from the inner peripheral surface 3 b of the rim 3 toward the tooth tip side at a position corresponding to each tooth 10 on the inner peripheral side of the rim 3. A meat thinning portion 11 that is smoothly recessed in an arc shape is formed. The connecting portion between the meat thinning portion 11 and the inner peripheral surface 3b of the rim 3 is rounded, and the meat thinning portion 11 and the inner peripheral surface 3b of the rim 3 are smoothly connected. 3 is devised so that stress does not concentrate on the connecting portion with the inner peripheral surface 3b.

このような構成の本実施の形態のモールドギヤ１は、上記第１の実施形態と同様の効果を得ることができる。 The mold gear 1 of the present embodiment having such a configuration can obtain the same effects as those of the first embodiment.

尚、上記の各実施の形態は、射出成形により製造されるプラスチックモールドギヤを例に採って説明した。しかし、本発明は、これに限られず、ダイカストによって成形される金属モールドギヤや、特殊鋳造法によって成形されるモールドギヤのように、溶融材料を型内で冷却・固化させることにより所望形状に成形されるギヤに広く適用できる。 Each of the above embodiments has been described by taking a plastic mold gear manufactured by injection molding as an example. However, the present invention is not limited to this, and is formed into a desired shape by cooling and solidifying the molten material in a mold, such as a metal mold gear formed by die casting or a mold gear formed by a special casting method. Widely applicable to gears.

又、上記各実施の形態は、平歯車を例示しているが、これに限られず、はすば歯車にも適用できる。但し、この場合は、歯のねじれ方向に沿って肉ぬすみ部が形成される。 Moreover, although each said embodiment illustrated the spur gear, it is not restricted to this, It can apply also to a helical gear. However, in this case, a thinned portion is formed along the twisting direction of the teeth.

又、肉ぬすみ部１１は、上記各実施の形態において円弧状に形成する態様を示したが、これに限られるものではなく、リム３の内周側から歯先側へ向かって滑らかに凹むものであれば、略三角形状や略台形形状等の多角形形状のものでもよい。但し、各辺の交叉部は、応力集中が生じないように、円弧状に形成される必要がある。 Moreover, although the meat thinning part 11 showed the aspect formed in circular arc shape in said each embodiment, it is not restricted to this, What is dented smoothly toward the tooth tip side from the inner peripheral side of the rim | limb 3 If it is, a polygonal shape such as a substantially triangular shape or a substantially trapezoidal shape may be used. However, the crossing portion of each side needs to be formed in an arc shape so that stress concentration does not occur.

又、ウェブ４の形状や各リブ５，６の形成位置及び各リブ５，６の形状等のリム３を除く部分は、上記実施の形態の態様に限られるものでなく、設計条件等に応じて適宜変更することができる。 Further, the shape of the web 4, the formation positions of the ribs 5 and 6, and the portions of the ribs 5 and 6 excluding the rim 3 are not limited to the above-described embodiments, and can be determined according to design conditions and the like. Can be changed as appropriate.

本発明の第１の実施の形態に係るモールドギヤの側面図（図３のＡ方向から見た図）である。It is a side view (figure seen from A direction of Drawing 3) of a mold gear concerning a 1st embodiment of the present invention. 図１のモールドギヤのリムの一部を拡大して示す図である。It is a figure which expands and shows a part of rim | limb of the mold gear of FIG. 図１のＣ−Ｃ線に沿って切断して示す断面図である。It is sectional drawing cut | disconnected and shown along the CC line | wire of FIG. 本発明の第２の実施の形態に係るモールドギヤのリムの一部を拡大して示す図である。It is a figure which expands and shows a part of rim | limb of the mold gear which concerns on the 2nd Embodiment of this invention. 図３のＢ方向から見た図である。It is the figure seen from the B direction of FIG. 従来のモールドギヤの外観斜視図である。It is an external appearance perspective view of the conventional mold gear. 図６のモールドギヤのリムの一部を拡大して示す図である。It is a figure which expands and shows a part of rim | limb of the mold gear of FIG. 他の従来例を示すモールドギヤのリムの一部拡大図である。It is a partially enlarged view of a rim of a molded gear showing another conventional example.

Explanation of symbols

１……モールドギヤ、３……リム、３ａ……内周、１０……歯、１１……肉ぬすみ部 1 ... Mold gear, 3 ... Rim, 3a ... Inner circumference, 10 ... Teeth, 11 ... Meat fillet

Claims

In the mold gear formed by solidifying the molten material in the mold and forming a plurality of teeth on the outer periphery of the rim,
A molded gear, characterized in that a meat thinning portion that is smoothly recessed from the inner periphery of the rim toward the tooth tip side is formed at a position corresponding to each tooth on the inner periphery side of the rim.

In the mold gear formed by solidifying the molten material in the mold and forming a plurality of teeth on the outer periphery of the rim,
A molded gear characterized in that the inner periphery of the rim is formed into a wave-like curved surface that is smoothly dented toward the tooth tip at a position corresponding to each tooth and smoothly protrudes toward the center of rotation at a position corresponding to each tooth bottom.