JP2004260333A - Manufacturing method of speaker diaphragm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a speaker diaphragm for a wooden speaker excellent in stable quality and mass-productivity. <P>SOLUTION: The manufacturing method of speaker diaphragm includes the steps of: (a) adhering a nonwoven fabric or Japanese paper on one surface of a wooden sheet to make the wooden sheet to be an adhered sheet; (b) providing an approximately V-shaped notch to the wooden sheet; (c) wetting and softening the wooden sheet, and impregnating a lubricant to the wooden sheet, the lubricant acting to keep water in the wooden sheet; (d) overlapping edge portions of the notch so as to be latched and kept in an approximately horn shape and applying a first hot press molding to the overlapped parts to tentatively mold them in an approximately horn shape; (e) drying the wooden sheet; (f) incorporating a thermosetting resin into the wooden sheet, (g) half-drying the wooden sheet; (h) applying a second hot press molding to the adhered sheet wherein the thermosetting resin is in a half-drying state; (i) applying a moisture-proof agent to the wooden sheet; and (j) removing a center hole for a voice coil and periphery from the wooden sheet to make a speaker diaphragm having a predetermined dimension and shape. Moreover, a weight appropriating step (g1), a propagation speed appropriating step (h1), a release agent impregnating / drying step (h2), and a third hot press molding step (h3) are added to the manufacturing method. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

なお、図１１中のＡ点はカバ（無垢材）であり、以下、Ｂ点；シナ（無垢材）、Ｃ点；ブナ（無垢材）、Ｄ点；オーク（無垢材）、Ｅ点；チェリー（無垢材）、Ｆ点；スプルース（無垢材）、Ｇ点；シナ合板（共芯）、Ｈ点；ラワン合板、Ｉ点；ＭＦＤ、Ｊ点；パーティクルボードである。
【００３１】
次に、上記スピーカ用振動板３０の第１の実施の形態の製造方法を図１の（ａ）から（ｊ）までのフロー図及び図２、図３の対応する（ａ）から（ｊ）までの模式図に従って説明する。
【００３２】
先ず、請求項１に係る第１の実施の形態のスピーカ用振動板３０の製造工程は、図１に示される破線で囲まれた工程を除くフローとなり、前述の予め素材準備段階で用意された木製シート１０を素材として（ａ）〜（ｊ）までの工程で構成され、（ａ）貼り合わせシート作成、（ｂ）Ｖ字状切り込みの形成、（ｃ）潤滑剤含浸、（ｄ）仮成形の１次プレス、（ｅ）乾燥、（ｆ）熱硬化性樹脂含浸、（ｇ）半乾燥、（ｈ）２次プレス、（ｉ）防湿剤塗布、（ｊ）中心孔・外形抜きの順に行われてスピーカ用振動板の完成となる。
【００３３】
上記各製造工程の詳細内容を以下順に説明する。
【００３４】
工程（ａ）・・・厚さ０．ｌｍｍ〜０．９ｍｍ（好ましくは０．３ｍｍ程度）の木製シート１０の一面側に、接着剤により略０．０２〜０．３０ｍｍ厚の不織布又は和紙１３を貼り合わせて貼り合わせシート１５を作成する。ここにいう不織布はカーボン材その他の合成樹脂からなる周知材料であり、貼り合わせた一面側が完成した振動板３０の背面側となる。上記木製シート１０の厚さは成形性と音響特性及びダイナミック・スピーカの口径を考慮した上でのスピーカ用振動板として適正な厚さである。
【００３５】
工程（ｂ）・・・貼り合わせシート１５に対して、中心部に小穴１２とその小穴１２を頂点とする略Ｖ字状の切り込み１１を設ける。前記切り込み１１は、貼り合わせシート１５の木目方向（矢印ｆ）に概ね沿って設ける。なお、上記小穴１２は略ラッパ形状に成形する際の中心部の割れを防止するために設けられ、更には後述のプレス加熱成形時の位置合わせを簡単且つ正確に行うためのものであり、直径数ミリの円形、楕円形、六角形等であって形状に制限はない。
【００３６】
工程（ｃ）・・・Ｖ字切り込みした前記貼り合わせシート１５が軟化するように、貼り合わせシート１５の中に浸透して水分を与え且つ水分を保持する作用のある潤滑剤１６の液中に５〜６０分浸して十分に含浸させる。
【００３７】
これは後の１次プレス加熱成形を実施する時に割れを未然に防ぎ、歩留まり良く仮成形するためである。本発明者の研究によれば前記潤滑剤１６としては、単なる水若しくはアルカリ水溶液ではなく、糖類を溶解させた水溶液が適する。
【００３８】
工程（ｄ）・・・予め、セッティングの作業性の向上と成形性（しわや割れが少ない）を良好なものとするために貼り合わせシート１５の切り込み１１の両縁部１１ａ、１１ｂ同士を重ね合わせて図２の（ｄ）に示されるように略ラッパ形状になるように成形外領域（余白部分）をホッチキス（商標名）やクリップ等の掛止具２６で仮止め或いは前記成形外領域に互いに引っかける雄雌形状の掛止機構を設けることによって１次プレス加熱成形前に略ラッパ形状に掛止保持しておく。次に、ヒータ３３を各々備えた上型３１と下型３２の金型構成のプレス装置Ｐ１によって、下型３２に載置した前記潤滑剤１６を含浸させ掛止具２６で略ラッパ形状に保持させた貼り合わせシート１５を１次プレス加熱成形（仮成形）する。ここで１次プレス加熱成形の設定条件は、プレス圧力が略１〜１０Ｋｇ、金型温度は上型３１が略８０〜１５０℃、下型３２が略１００〜２００℃、プレス時間が略２〜６０秒を好適とする。なお、１次プレス加熱成形の後は両縁部１１ａ、１１ｂ同士は自然状態で離れない程度に貼着されており、略ラッパ形状が保持される。
【００３９】
工程（ｅ）・・・乾燥炉（５０〜６０℃）に略１０〜３０分間入れて完全乾燥を行なう。
【００４０】
工程（ｆ）・・・乾燥後の貼り合わせシート１５を熱硬化性樹脂１７液中に略３０分〜１８０分浸し、十分に含浸させる。上記熱硬化性樹脂１７としてはフェノール樹脂が適する。
【００４１】
工程（ｇ）・・・熱硬化性樹脂１７の含浸直後、後工程の２次プレスを実施すると、金型に熱硬化性樹脂１７が貼り付いてしまい、プレス後に貼り合わせシート１５を剥がす時に割れや引きちぎれが発生して歩留まりが極度に低下する。逆に完全に乾燥させると成形性が悪くなって割れやすくなる。これを防止するために、乾燥炉（５０℃〜６０℃）に略１〜１０分間入れて熱硬化性樹脂１７を半乾燥状態（指で触ってもべたつかない程度の所謂“指触乾燥状態”である。）にする。
【００４２】
工程（ｈ）・・・前記工程（ｄ）と同様の周知の構成のプレス装置Ｐ２によって、含浸させた熱硬化性樹脂１７が半乾燥状態の貼り合わせシート１５を再度プレス加熱成形する。ここで２次プレス加熱成形の設定条件は、プレス圧力が略２０〜４０Ｋｇ、金型温度は上型３４が略８０〜２００℃、下型３５が略１００〜２００℃、プレス時間が略１０〜１００秒を好適とする。成形後は揮発成分が蒸散して成形形状が略ラッパ状に安定した貼り合わせシート１５となる。なお、この時点で重ね合わせて貼着された前記切り込み１１の縁部１１ａ、１１ｂ（斜線領域）同士はその段差が殆ど判別できない程度に密着しており、音響特性に与える影響は殆ど無いものとなっている。
【００４３】
工程（ｉ）・・・２次プレス後の貼り合わせシート１５の表裏両面に筆による塗布若しくはジャブ漬けにより防湿剤１８を塗布する。この防湿剤１８としては例えば、ポリイソシアネートとポリエステルポリオールを混合し、さらにシンナーを混合したものを用いる。塗布された上記防湿剤１８は自然乾燥又は乾燥炉で完全乾燥を行なう。
【００４４】
工程（ｊ）・・・防湿処理されたプレス加熱成形後の貼り合わせシート１５にボイスコイル用の中心孔２５と外形抜きが施されて所定の振動板形状に加工されてスピーカ用振動板３０が完成する。
【００４５】
上記完成した略ラッパ状のスピーカ用振動板３０は、製品検査を経て従来のダイナミック・スピーカと同様にボイスコイル、ダンパー、エッジ、磁気回路、フレーム等と組み合わされてスピーカユニットに組み込まれる。
【００４６】
上記第１の実施の形態のスピーカ用振動板３０の製造工程では、プレス加熱成形処理は１次、２次の２回であるが、より仕上がりの良い振動板として歩留まりの向上が図れる第２の実施の形態の製造方法として、上記２次プレス加熱成形工程（ｈ）における設定条件で、プレス時間のみを略２〜３０秒と短めの条件として、以下の工程（ｈ２）、（ｈ３）からなる３次プレス加熱成形処理を加えることも形状がより安定して仕上がりの良好な好ましい製造方法である。
【００４７】
工程（ｈ２）・・・工程（ｈ）の２次プレス加熱成形後の略ラッパ形状に成形された貼り合わせシート１５に離型剤４６を含ませて乾燥する。この離型剤４６には例えばシリコン（ケイ素）を用いる。
【００４８】
工程（ｈ３）・・・前記離型剤４６が含まされた貼り合わせシート１５をヒータ３３を備える上型３６と下型３７からなるプレス装置Ｐ３で３次プレス加熱成形する。ここで３次プレス加熱成形の設定条件は、プレス圧力が略２０〜４０Ｋｇ、金型温度は上型３６が略８０〜２００℃、下型３７が略１００〜２００℃、プレス時間が略２〜６０秒を好適とする。
【００４９】
次に、上記第１、第２の実施の形態のスピーカ用振動板３０の製造工程では貼り合わせシート１５に対する品質管理は製造工程中で特段明示されていないが、貼り合わせシート１５のひび・割れ等の外観不良物は当然に製造工程中に適宜振り落とされることを前提とする。この点、素材の木製シート１０が木材という自然物であることから貼り合わせシート１５には外観以外の個体差も不可避的に存在する。したがって、好ましくは製造工程中で貼り合わせシート１５に対するより細かな品質管理を行うことが一層望ましい製造方法と言える。また、完成後の製品検査段階で良品／不良品を選別するよりも製造工程中に品質検査して良品に至らない貼り合わせシートについては、可能であれば前の工程に戻って再処理する等して適正化を図って可及的に良品として救うことが歩留まりの向上にも資すると言える。そこで図１に示される製造工程フローにおいて、破線で囲まれた以下の工程を付加する製造方法が第３、第４の実施の形態として挙げられる。
【００５０】
本発明に係る第３の実施の形態のスピーカ用振動板３０の製造方法として、図１のスピーカ用振動板の製造工程フローにおいて、熱硬化性樹脂１７が含まされた貼り合わせシート１５を半乾き状態になるまで半乾燥する工程（ｇ）の直後に、前記熱硬化性樹脂１７が半乾き状態の貼り合わせシート１５の重量測定を行い、規定値重量以下の貼り合わせシートを再度熱硬化性樹脂１７を含ませる工程（ｆ）に戻してやり直す重量適正化工程（ｇ１）を設ける。
【００５１】
例えば、素材の木製シート１０の密度その他の特性によって熱硬化性樹脂１７の含浸の程度が適正な状態となっているか否かを重量評価で判定し、適正範囲であれば次の２次プレス加熱成形の工程（ｈ）へ進み、重すぎれば再生不可能としてこの時点で廃棄処分とし、軽すぎれば熱硬化性樹脂１７の含浸不足として上記工程（ｆ）へ戻るのである。
【００５２】
次に、本発明に係る第４の実施の形態のスピーカ用振動板３０の製造方法として、上記第１、第２の実施の形態の各製造方法において、２次プレス加熱成形する工程（ｈ）の直後に、２次プレス加熱成形後の貼り合わせシート１５の音波の伝搬速度測定を例えば、図６のようなＹＡＧレーザ（パルス駆動）４１により発生した超音波の挙動をプローブ４２及びプローブ４３を用いて計測し、変位計＆ＦＥＴ解析器４４よりそれらの時間遅れから伝搬速度を求める構成の伝搬速度計測装置４５によって行い、規定値速度以上のものは次の工程へ進み、規定値速度以下の貼り合わせシート１５は再度２次プレス加熱成形を行う工程（ｈ）に戻してやり直すという伝搬速度適正化工程（ｈ１）を設ける。
【００５３】
即ち、貼り合わせシート１５の個体差（密度等の違い）によって一律の２次プレス加熱成形による成形が不十分な場合も有り得るので、剛性に関係する音波の伝搬速度に多少のばらつきが生じ得る。そこで、伝搬速度評価をして規定値以下であれば、再度２次プレス加熱成形の工程（ｈ）を行うこととして伝搬速度の適正化を少なくとも１回は行うこととする。而してこの工程（ｈ１）の追加で品質（音響特性）の安定と歩留まりの向上が図れることとなるのである。
【００５４】
以上の貼り合わせシート１５の所定段階における重量適正化工程（ｇ１）或いは伝搬速度適正化工程（ｈ１）又はその双方を付加することで歩留まりの向上が達成され、木製のスピーカ用振動板３０の品質の安定も達成されることとなる。
【００５５】
次に、本発明に係る第５の実施の形態のスピーカ用振動板３０の製造方法として、前記各製造方法における１次〜３次のプレス加熱成形工程の内、図７に示されるように、少なくとも１次プレス加熱成形工程（ｄ）に使用されるプレス装置Ｐ１の下金型３２中心部に突起ピン３８を設けるとともに上金型３１中心部に前記突起ピン３８に嵌合する窪み３９を設け、プレス加熱成形時に貼り合わせシート１５の中心部に設けられた前記小穴１２を前記下金型３２中心部の突起ピン３８に挿入して位置決めした後にプレス加熱成形を行うようにする。而して当該プレス加熱成形の作業性、貼り合わせシート１５の成形の位置精度が高まることで量産効率と歩留まりの向上が図れることになる。勿論、１次プレス加熱成形工程（ｄ）のみならず２次プレス加熱成形工程（ｈ）のプレス装置Ｐ２や図５の（ｈ３）に示されるように３次プレス加熱成形工程のプレス装置Ｐ３にも同様の突起ピン３８と窪み３９を設けて位置合わせを正確且つ迅速に行うようにすることも好ましい。付言すれば、２次、３次プレス加熱成形工程の段階では、前の１次プレス加熱成形工程である程度形状が所定のラッパ形状に安定しているのでさほど問題ではないが、最初の１次プレス加熱成形工程（ｄ）では、貼り合わせシート１５の形状がプレス前で不安定なために上記小穴１２による位置合わせが特に有効となるのである。
【００５６】
以上の製造方法によって製造されたスピーカ用振動板３０は、本発明者の研究によれば、縦方向伝搬速度が４．５〜６．０ｋｍ／秒、横方向伝搬速度が２．０〜４．５ｋｍ／秒の範囲の木材を選定して上記各実施の形態の製造方法にて製造された振動板が明確に従来の紙パルプ製の振動板やアルミ製の振動板に比べて再生音の解像度向上や歯切れ良い音の向上が得られることが判った。
【００５７】
特に顕著に音響特性の向上が実感されるのは、縦方向伝搬速度が４．５〜６．０ｋｍ／秒、横方向伝搬速度が２．０〜２．５ｋｍ／秒の範囲で内部損失係数が０．０２〜０．０３の範囲の木材を選択して振動板に用いた場合であり、具体的にはカバ材（無垢）が最良であった。
【００５８】
勿論、本発明のスピーカ用振動板は、カバ材のみならず、ブナ、オーク、チェリー、シナ等の他の材木を適用することもできることは言うまでもない。
【００５９】
【発明の効果】
上記のように本発明に係るスピーカ用振動板の製造方法は、１枚の木材を素材とし、従来の紙パルプ製振動板の製造過程に存在するような化学薬品での蒸解や木材繊維の叩解処理が加えられていないので音質劣化が発生しない振動板を作ることができる。
【００６０】
従来の木製振動板のような柔軟化のためのボイル処理、物理的処理、化学的薬品を施さないので音質劣化の発生しない振動板を作ることができる。
【００６１】
プレス加熱成形時のしわや割れの発生が防止され、製造後の変形や割れといった経時変化が殆ど無い仕上がりの良い均一なプレス加熱成形品とすることができる。
【００６２】
軽くて丈夫なコーン振動板が製造可能になり、ウーハーからフルレンジスピーカまで全ての帯域に対応した振動板が製造できる。
【００６３】
プレス加熱成形工程において位置合わせが容易且つ正確にできるため、プレス機へのセッティングの作業性が向上し、仕上がりの良い振動板が実現できる。
【００６４】
重量適正化工程や伝搬速度適正化工程によって、歩留まりが向上するとともに安定した品質の木製振動板の安価供給が実現できる。
【００６５】
本スピーカ用振動板をダイナミック・スピーカ・ユニットに採用することで木製であるが故の自然な振動による生音に迫る再声音が得られる。
【００６６】
さらに、表面に自然の木目が表れているので、高級感のある外観体裁となる。
【図面の簡単な説明】
【図１】本発明に係る第１乃至第５の実施の形態のスピーカ用振動板の製造工程のフロー図である。
【図２】前記製造工程フロー図の各加工状態（前半）を示す模式図である。
【図３】前記製造工程フロー図の各加工状態（後半）を示す模式図である。
【図４】本発明に係るスピーカ用振動板の素材である木材の形状の加工段階を説明する模式図である。
【図５】本発明の第２及び第５の実施の形態の製造方法に係る付加された３次プレス加熱成形処理の工程を示す模式図である。
【図６】本発明の第４の実施の形態の製造方法に係る貼り合わせシートの音波の伝搬速度測定を行う計測装置を示す図である。
【図７】本発明の第５の実施の形態の製造方法に係る１次、２次プレスのためのプレス装置とプレス加熱成形工程を説明する図である。
【図８】本発明に係る略ラッパ形状のダイナミック・コーン・スピーカのスピーカ用振動板の概略図である。
【図９】従来の木製振動板の製造手順を示す図である。
【図１０】従来の木製振動板の製造手順を示す図である。
【図１１】各種木材の有する内部損失係数と音伝搬速度（縦方向）についての関係を従来の材料であるアルミと紙と共に表したグラフである。
【符号の説明】
６ 丸太
７ 削り出し用刃
１０ 木製シート
１１ 略Ｖ字状の切り込み
１１ａ、１１ｂ 両縁部
１２ 小穴
１３ 不織布又は和紙
１５ 貼り合わせシート
１６ 水分を与え且つ水分を保持する作用のある潤滑剤
１７ 熱硬化性樹脂
１８ 防湿剤
２５ 中心孔
２６ 掛止具
３０ スピーカ用振動板
３１、３４、３６ 上型
３３ ヒータ
３２、３５、３７ 下型
３８ 突起ピン
３９ 窪み
４１ ＹＡＧレーザ（パルス駆動）
４２、４３ プローブ
４４ 変位計＆ＦＥＴ解析器
４５ 伝搬速度計測装置
４６ 離型剤
Ｐ１、Ｐ２ プレス装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to the technical field of audio speakers, and more particularly to a method of manufacturing a wooden diaphragm used for a dynamic speaker.
[0002]
[Prior art]
Conventionally, the diaphragm of a dynamic speaker has been mostly made of paper pulp, plastic, or metal such as aluminum. Since these conventional diaphragms are formed by pressing a uniform material, the sound propagation speed in the radial direction from the center is equal in all directions. Therefore, there is a problem that a standing wave is always generated and has a resonance point, the sound pressure frequency characteristic is deteriorated due to the divided vibration in a low frequency region, and the sense of reality is lost. Further, although the diaphragm made of paper pulp or plastic has a relatively large internal loss coefficient, it is inferior in rigidity (the magnitude of the Young's modulus), and the sound wave propagation speed is small, so the resolution of the reproduced sound is slightly dissatisfied. Will remain. On the other hand, although a diaphragm made of metal such as aluminum has a high sound wave propagation velocity, it has a small internal loss coefficient, and therefore has a disadvantage in that the attenuation of the amplitude is small and the division of the reproduced sound becomes unclear (so-called poor sound sharpness). .
[0003]
There is a demand for the realization of a wooden diaphragm as a speaker diaphragm capable of reproducing a more natural sound, instead of a diaphragm made of an existing material having advantages and disadvantages as described above.
[0004]
That is, although the sound wave propagation speed of wood differs depending on the type, it is generally higher than that of paper pulp, and further differs between the grain direction and the direction perpendicular to the grain direction. The propagation speed in the grain direction (vertical direction) is high, and is perpendicular to the grain direction. It has an anisotropic propagation property that the propagation speed in the direction (referred to as the lateral direction) is relatively slow. Wood generally has a suitable internal loss coefficient as a speaker diaphragm, and is lightweight and durable (high rigidity).
[0005]
Therefore, a wooden diaphragm made of wood itself hardly generates a standing wave and hardly has a resonance point, so that almost no split vibration occurs, and it is expected that sound pressure frequency characteristics in a low frequency region are improved. Compared with the diaphragm made of pulp and paper, the resolution of the reproduced sound can be improved and the crisp sound can be improved.
[0006]
Various proposals have already been made, for example, in the following known documents as a method for manufacturing the wooden diaphragm or a dynamic speaker using the wooden diaphragm or a wooden diaphragm.
[0007]
[Patent Document 1] described below discloses a flat thin plate made of WPC which is obtained by impregnating and hardening a plastic such as polyester into a flat thin plate made of a wooden material. The flat thin plate for a speaker has excellent characteristics such as dimensional stability, internal friction, and rigidity. A speaker used as a speaker has been proposed.
[0008]
In the following [Patent Document 2], as shown in the manufacturing procedure shown in FIGS. 9A and 9B, (a) an arc-shaped notch 1a is formed at the center from one piece of wood thin plate 4. Then, a wood sheet 1 having a substantially trumpet-shaped expanded shape having a sector-shaped notch 1b is cut out continuously, and (b) both edges b1, b2 of the sector-shaped notch 1b of the wood sheet 1 are glued. There has been proposed a cone diaphragm 5 formed by overlapping and pasting each other with an adhesive at a margin portion 1c, forming a trumpet shape, and then press forming.
[0009]
Also, as in the manufacturing procedure shown in FIGS. 10A and 10B, a plurality of small wood piece sheets 2a, 2b... A cone diaphragm 2 formed and then pressed is proposed. Further, there has been proposed a cone diaphragm in which a physical moisture resistance treatment or a chemical moisture resistance treatment is applied to the cone diaphragms 1 and 2.
[0010]
[Patent Document 3] described below discloses a softening treatment of a composite sheet composed of an ultrathin wood sheet sliced to 80 μm or less and a nonwoven fabric made of an adhesive resin adhered to the back surface thereof with a softener. There has been proposed an acoustic diaphragm which is formed by laminating a plurality of sheets and further heating and pressing to form a conical shape.
[0011]
[Patent Document 4] described below discloses that a flat thin wooden plate cut into a fan shape is boiled with high-temperature steam, hot water, or an alkaline solution having a pH of 10 or more in order to prevent cracking during molding, and then into a cone shape. A cone diaphragm formed by press molding has been proposed.
[0012]
In the following Patent Document 5, a laminated sheet in which a thin nonwoven fabric or Japanese paper is adhered to one surface side of one wooden sheet is prepared, and this is impregnated into a container containing a lubricant, and the impregnated laminated sheet is impregnated. Has been proposed in which a speaker diaphragm is formed into a substantially trumpet shape by press-heating.
[0013]
In the following Patent Document 6, in order to produce a wooden speaker diaphragm which does not generate wrinkles or cracks during press molding and has little change over time, a thin nonwoven fabric or Japanese paper or A speaker diaphragm has been proposed in which a laminated sheet having a carbon sheet attached thereto is formed, impregnated with a thermosetting resin, and then press-heat-molded to form a substantially trumpet shape.
[0014]
[Patent Document 1] JP-A-62-224196 [Patent Document 2] JP-A-1-288100 [Patent Document 3] JP-A-5-83792 [Patent Document 4] JP-A-6-178386 [ [Patent Document 5] Japanese Patent Application Laid-Open No. 10-304492 [Patent Document 6] Japanese Patent Application Laid-Open No. 2000-59883 [Problems to be Solved by the Invention]
A particular point in the manufacture of wooden speaker diaphragms is how to deal with the fragile nature of the wood material in molding and how to deal with aging.
[0015]
Regarding this point, [Patent Document 1] is directed to a wooden planar diaphragm, which has the characteristics and advantages of being made of wood, but the formability when forming into a substantially trumpet shape (cone shape). No technical data has been provided for this problem because it is flat.
[0016]
Further, in the manufacturing method as shown in FIGS. 9 and 10 of [Patent Document 2], since the wood sheet 1 or the small wood sheets 2a, 2b,. In addition, there is a problem that cracks occur at the time of press molding or that the wood sheets are bonded to each other with an adhesive, so that the bonded portion becomes an obstacle and the desired acoustic characteristics cannot be obtained, and there is a problem that dimensional accuracy cannot be secured. .
[0017]
Also, the manufacturing method of [Patent Document 3] in which a plurality of ultra-thin wood sheets are laminated and press-molded has a drawback in processing accuracy, the number of adhesive layers increases, and the weight of the diaphragm itself increases due to the weight of the adhesive. As a result, the desired acoustic characteristics cannot be obtained, and a large amount of the adhesive adversely affects the sound pressure frequency characteristics.
[0018]
Further, in the case of a manufacturing process including boil treatment with high-temperature steam or an alkaline solution having a pH of 10 or more before press molding as in [Patent Document 4], a constituent material called lignin in wood is also removed, so that wood is removed. Cannot exhibit its original characteristics, which will adversely affect sound quality.
[0019]
Above all, the contents of [Patent Literature 2], [Patent Literature 3], and [Patent Literature 4] have many problems such as cracks, cracks, and wrinkles during manufacturing, and the yield in mass production is extremely high. It has become worse and commercialization has not been realized.
[0020]
Further, a thermosetting resin for preventing impregnation of a lubricant for extracting “tension” and “suppleness” in [Patent Document 5] and [Patent Document 6], preventing generation of wrinkles and cracks, and preventing a change with time is known. The method of manufacturing the speaker diaphragm by press-heating after impregnation has an advantage of the manufacturing process for mass production as compared with the above-mentioned [Patent Document 1] to [Patent Document 4], but it is still sufficient for mass production. It is hard to say that the establishment of the forming process has been achieved, and it is desired to further improve the yield of formability and realize a beautifully finished wooden diaphragm for practical use of the wooden diaphragm.
[0021]
The present invention has been made in view of the above circumstances, and provides a method of manufacturing a wooden speaker diaphragm that is effective for improving the acoustic characteristics of a dynamic speaker and is suitable for mass production.
[0022]
[Means for Solving the Problems]
The present invention, in order to solve the above problems,
(1) In a method for manufacturing a speaker diaphragm including a step of press-molding one wooden sheet as a raw material into a substantially trumpet shape, first, one wooden sheet 10 having a thickness of 0.1 mm to 0.9 mm is formed. Step (a) of attaching a thin nonwoven fabric or Japanese paper 13 to one surface side to form a bonded sheet 15, and secondly, a small hole 12 in the center of the bonded sheet 15 and a substantially V having the small hole 12 as an apex. Step (b) of providing the letter-shaped cut 11, and thirdly, a lubricant 16 having a function of giving moisture to the bonded sheet 15 provided with the cut 11 to soften it and retain moisture in the bonded sheet 15. And (c) fourthly, the laminated sheet 15 containing the lubricant 16 is subjected to primary press heat molding to temporarily form a substantially trumpet shape in which the edges of the cuts 11 are overlapped with each other. A shaping step (d), a fifth step (e) of drying the temporarily formed laminated sheet 15, and a sixth step of including the thermosetting resin 17 in the dried laminated sheet 15. (F), seventhly, a step (g) of semi-drying the bonded sheet 15 containing the thermosetting resin 17 until it becomes a semi-dry state, and eighthly, the thermosetting resin 17 is half-dried. A step (h) of subjecting the bonded sheet 15 in a dry state to secondary press heat molding, a step (i) of applying a moisture-proof agent 18 to the laminated sheet 15 after the secondary press heat molding, and a step (i). (J) forming a center hole 25 for a voice coil and removing an outer shape from the bonded sheet 15 coated with the moisture-proof agent 18 to form a predetermined dimension as a diaphragm. Speaker diaphragm 30 characterized by the following: To provide a process for the production.
(2) In the method for manufacturing the speaker diaphragm 30 according to the above (1), a step of including a release agent 46 in the bonded sheet 15 formed into a substantially trumpet shape after the second press heat forming and drying. The step (h2) and the step (h3) of subjecting the bonded sheet 15 containing the release agent 46 to the third press heating are performed before the step (i) of applying the moisture proof agent 18 to the bonded sheet 15. A method of manufacturing the speaker diaphragm 30 is provided.
(3) In the method for manufacturing the speaker diaphragm 30 according to the above (1) or (2), the step of semi-drying the bonded sheet 15 containing the thermosetting resin 17 until the laminated sheet 15 becomes semi-dry ( Immediately after g), the weight of the bonded sheet 15 in which the thermosetting resin 17 is in a semi-dry state is measured, and the bonding sheet 15 having a specified weight or less is again included in the thermosetting resin 17 (f). And a method for manufacturing a speaker diaphragm 30 provided with a weight optimizing step (g1).
(4) In the manufacturing method of the speaker diaphragm 30 according to the above (1) or (2), immediately after the step (h) of the second press heat molding, the bonded sheet 15 after the second press heat molding. A loudspeaker characterized by providing a propagation velocity optimizing step (h1) of returning the bonded sheet having a prescribed speed or less to the step (h) of performing secondary press heat molding again by measuring the propagation velocity of the sound wave. A method for manufacturing the diaphragm 30 is provided.
(5) In the manufacturing method of the speaker diaphragm 30 according to the above (1), (2), (3), or (4), at least the press device P1 used for the first press heat molding. A projection pin 38 is provided at the center of the mold 32, and a recess 39 is formed at the center of the upper mold 31 so as to fit the projection pin 38. The small hole 12 provided at the center of the bonded sheet 15 at the time of press heating is formed. A method for manufacturing a diaphragm 30 for a speaker, characterized in that press-heating is performed after inserting and positioning the protrusion into a projection pin 38 at the center of the lower mold 32.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of a speaker diaphragm according to the present invention will be described with reference to the drawings. FIG. 1 is a flow chart of the manufacturing process of the speaker diaphragm of the first to fifth embodiments according to the present invention. 2 and 3 are schematic diagrams showing the first half and the second half of each processing state in the manufacturing process. FIG. 4 is a schematic diagram for explaining a processing stage of a shape of wood as a material of the speaker diaphragm according to the present invention. FIG. 5 is a schematic diagram showing an added step of a third press heat forming process according to the manufacturing methods of the second and fifth embodiments of the present invention. FIG. 6 is a diagram showing a measuring device for measuring the propagation speed of the sound wave of the bonded sheet according to the manufacturing method of the fourth embodiment of the present invention. FIG. 7 is a view for explaining a press device for primary and secondary presses and a press heat forming step according to the manufacturing method of the fifth embodiment of the present invention. FIG. 8 is a schematic view of a speaker diaphragm of a substantially cone-shaped dynamic cone speaker according to the present invention.
[0024]
First, in FIG. 4, wood used as a material of the speaker diaphragm 30 of the present invention is prepared as a preparation stage of manufacture, for example, as shown in FIG. As shown in (b), the sheet is cut into an appropriate shape that is larger than the molded part (inside of the dashed circle) that becomes the diaphragm as shown in FIG. For example, in the case of a diaphragm of a dynamic cone loudspeaker having a diameter of about 8 cm, a square having a side of about 12 to 14 cm or a rectangle or a circle having a diameter of about 12 cm is used.
[0025]
Next, in the manufacturing stage, the wooden sheet 10 becomes a bonded sheet 15 through a bonding process of the nonwoven fabric or the Japanese paper 13 shown in FIG. 2A, and as shown in FIG. A substantially V-shaped cut 11 is provided. The shape of the substantially V-shaped notch 11 does not have to be a perfect V-shape, and it is essential that the entire shape be substantially trumpet-shaped (cone-shaped) when both edges are overlapped with no gap.
[0026]
Next, after several press forming steps and the like, a speaker diaphragm 30 of a dynamic cone speaker having a substantially trumpet shape is finally obtained as shown in the schematic diagram of FIG. 8 (cross-sectional view of FIG. 3 (j)). See also).
[0027]
When the grain of the speaker diaphragm 30 shown in FIG. 8 is viewed from the center hole 25 cut out for the voice coil in the radial direction (for example, da to dh), only the da direction exists along the grain direction. Instead, the other direction intersects the grain at an angle. Therefore, the same sound propagation velocity does not exist in almost all directions, and a standing wave is hardly generated, and a resonance point is hardly generated. Therefore, divided vibration is suppressed.
[0028]
In addition, the speaker diaphragm 30 has excellent acoustic characteristics based on being made of wood and has a beautiful grain finish, and is impregnated with a selected lubricant, thermosetting resin, or desiccant, and is formed by a series of press heat molding processes. Due to ingenuity and the like, there are no wrinkles or cracks, little change over time due to humidity, and a long life. It should be noted that the production process is simple but very high in yield, and the production cost is suppressed and excellent in mass productivity.
[0029]
Here, considering wood suitable for the material of the speaker diaphragm 30 of the present invention, the relationship between the internal loss coefficient and the sound propagation speed (vertical direction) of the various woods in FIG. As can be seen from the following table, which shows the density, Young's modulus, sound velocity, and internal loss coefficient (tan δ) of various types of wood, the plywood was roughly (G point, H point, I point, J point). It can be seen that the removed wood (solid wood) can be an excellent material having an appropriate internal loss coefficient and a high sound propagation speed. In particular, it is found that the birch (point A) and beech (point C) are optimal.
[0030]
[Table 1]

In addition, the point A in FIG. 11 is a hippopotamus (solid wood), and hereafter, the point B; china (solid wood), the point C: beech (solid wood), the point D: oak (solid wood), the point E: cherry (Solid wood), point F: spruce (solid wood), point G: plywood (concentric), point H: lauan plywood, point I: MFD, point J: particle board.
[0031]
Next, a method of manufacturing the speaker diaphragm 30 according to the first embodiment will be described with reference to the flowcharts of FIGS. 1A to 1J and the corresponding FIGS. 2A to 3J of FIGS. Description will be made according to the schematic diagrams up to this point.
[0032]
First, the manufacturing process of the speaker diaphragm 30 according to the first embodiment of the present invention is a flow excluding the process surrounded by the broken line shown in FIG. The wooden sheet 10 is used as a raw material, and is composed of steps (a) to (j), (a) preparation of a laminated sheet, (b) formation of a V-shaped cut, (c) impregnation of a lubricant, and (d) temporary molding. Primary press, (e) drying, (f) thermosetting resin impregnation, (g) semi-dry, (h) secondary press, (i) application of moisture proofing agent, (j) center hole / outline This completes the speaker diaphragm.
[0033]
The detailed contents of each of the above manufacturing steps will be described below in order.
[0034]
Step (a): thickness 0. A nonwoven fabric or Japanese paper 13 having a thickness of about 0.02 to 0.30 mm is attached to one surface side of a wooden sheet 10 having a thickness of 1 mm to 0.9 mm (preferably about 0.3 mm) with an adhesive to form a bonded sheet 15. . The nonwoven fabric referred to here is a well-known material made of a carbon material or other synthetic resin, and one side of the bonded nonwoven fabric is the rear side of the completed diaphragm 30. The thickness of the wooden sheet 10 is appropriate for a speaker diaphragm in consideration of formability, acoustic characteristics, and the diameter of a dynamic speaker.
[0035]
Step (b): A small hole 12 and a substantially V-shaped cut 11 having the small hole 12 as an apex are provided in the center of the bonded sheet 15. The cut 11 is provided substantially along the grain direction (arrow f) of the bonded sheet 15. The small holes 12 are provided to prevent cracking of the center portion when forming into a substantially trumpet shape. Further, the small holes 12 are provided for easily and accurately performing positioning at the time of press heat molding described below. The shape is a circle, an ellipse, a hexagon, etc. of several millimeters, and the shape is not limited.
[0036]
Step (c): In a liquid of a lubricant 16 having a function of penetrating into the bonded sheet 15 to give moisture and to retain moisture so that the V-cut cut laminated sheet 15 is softened. Soak for 5-60 minutes to fully impregnate.
[0037]
This is because cracks are prevented beforehand when the primary press heat forming is performed later, and temporary forming is performed with good yield. According to the study of the present inventor, an aqueous solution in which a saccharide is dissolved is suitable as the lubricant 16 instead of a simple water or alkaline aqueous solution.
[0038]
Step (d): Both edges 11a and 11b of the cut 11 of the laminated sheet 15 are overlapped with each other in advance in order to improve the workability of setting and to improve the moldability (less wrinkles and cracks). In addition, as shown in FIG. 2 (d), the outer region (margin portion) is temporarily fixed by a stapler (trademark), a clip or the like so as to have a substantially trumpet shape, or is temporarily fixed to the outer region. By providing a male and female hooking mechanism for hooking each other, the hook is held and held in a substantially trumpet shape before the first press heat forming. Next, the lubricant 16 placed on the lower mold 32 is impregnated by a press device P1 having a mold configuration of an upper mold 31 and a lower mold 32 each having a heater 33, and is held in a substantially trumpet shape by a latch 26. The bonded sheet 15 thus formed is subjected to primary press heat forming (temporary forming). Here, the setting conditions of the primary press heat molding are as follows: the press pressure is about 1 to 10 kg, the mold temperature is about 80 to 150 ° C. for the upper mold 31, about 100 to 200 ° C. for the lower mold 32, and the press time is about 2 to 2. 60 seconds is preferred. After the primary press heat forming, the both edges 11a and 11b are stuck together so that they do not separate from each other in a natural state, and a substantially trumpet shape is maintained.
[0039]
Step (e): Complete drying is carried out by placing in a drying furnace (50-60 ° C.) for about 10-30 minutes.
[0040]
Step (f): The dried bonded sheet 15 is immersed in the liquid 17 of the thermosetting resin for about 30 to 180 minutes to be sufficiently impregnated. A phenol resin is suitable as the thermosetting resin 17.
[0041]
Step (g): Immediately after the impregnation of the thermosetting resin 17, if the secondary press in the subsequent step is performed, the thermosetting resin 17 is stuck to the mold, and is broken when the bonded sheet 15 is peeled off after the pressing. And tearing occurs and the yield is extremely reduced. Conversely, if it is completely dried, the moldability deteriorates and it becomes easy to break. In order to prevent this, the thermosetting resin 17 is placed in a drying oven (50 ° C. to 60 ° C.) for about 1 to 10 minutes to put the thermosetting resin 17 in a semi-dry state (a so-called “touch dry state” which does not stick when touched with a finger). ).
[0042]
Step (h): The bonded sheet 15 in which the impregnated thermosetting resin 17 is in a semi-dry state is press-heat-formed again by the press device P2 having a known configuration similar to that of the step (d). Here, the setting conditions of the secondary press heat molding are as follows: the press pressure is about 20 to 40 kg, the mold temperature is about 80 to 200 ° C. for the upper mold 34, about 100 to 200 ° C. for the lower mold 35, and the press time is about 10 to 10. 100 seconds is preferred. After forming, the volatile components evaporate, and the bonded sheet 15 is stable in a substantially trumpet shape. At this time, the edges 11a and 11b (hatched areas) of the cuts 11 which are superimposed and adhered are in close contact with each other to such an extent that the step can hardly be discriminated, and there is almost no influence on the acoustic characteristics. Has become.
[0043]
Step (i): The moisture proofing agent 18 is applied to both the front and back surfaces of the bonded sheet 15 after the secondary pressing by applying with a brush or dipping in a jab. As the moisture proofing agent 18, for example, a mixture of a polyisocyanate and a polyester polyol and further mixed with a thinner is used. The applied desiccant 18 is completely dried in a natural drying oven or a drying oven.
[0044]
Step (j): A center hole 25 for a voice coil and an outer shape are formed on the bonded sheet 15 after the press heat molding subjected to the moisture proof treatment, and the sheet is processed into a predetermined diaphragm shape. Complete.
[0045]
The completed speaker-like diaphragm 30 in a trumpet shape is subjected to product inspection, and then combined with a voice coil, a damper, an edge, a magnetic circuit, a frame, and the like, as in a conventional dynamic speaker, and is incorporated into a speaker unit.
[0046]
In the manufacturing process of the speaker diaphragm 30 according to the first embodiment, the press heat forming process is performed twice, that is, first and second times. However, the second process can improve the yield as a diaphragm having a better finish. The manufacturing method according to the embodiment includes the following steps (h2) and (h3) under the conditions set in the secondary press heat forming step (h), with only the pressing time being as short as about 2 to 30 seconds. Addition of a tertiary press heat forming treatment is also a preferable manufacturing method with more stable shape and good finish.
[0047]
Step (h2): The release sheet 46 is included in the bonded sheet 15 formed into a substantially trumpet shape after the secondary press heat forming in the step (h), and dried. As the release agent 46, for example, silicon (silicon) is used.
[0048]
Step (h3): The bonded sheet 15 containing the release agent 46 is subjected to tertiary press heat molding by a press device P3 including an upper die 36 and a lower die 37 having a heater 33. Here, the setting conditions of the tertiary press heat molding are as follows: the press pressure is about 20 to 40 kg, the mold temperature is about 80 to 200 ° C. for the upper mold 36, about 100 to 200 ° C. for the lower mold 37, and the press time is about 2 to 2. 60 seconds is preferred.
[0049]
Next, in the manufacturing process of the speaker diaphragm 30 according to the first and second embodiments, quality control for the bonded sheet 15 is not explicitly specified in the manufacturing process, but the bonded sheet 15 is cracked or broken. It is assumed that the defective appearance such as is naturally shaken off during the manufacturing process. In this regard, since the wooden sheet 10 made of a material is a natural material such as wood, individual differences other than the appearance of the bonded sheet 15 are inevitably present. Therefore, it can be said that it is a more desirable manufacturing method to preferably perform more detailed quality control on the bonded sheet 15 during the manufacturing process. Also, rather than sorting out good / defective products at the product inspection stage after completion, for bonded sheets that do not result in good quality during the manufacturing process, return to the previous process and reprocess if possible. It can be said that improving the yield as much as possible and contributing as good as possible also contributes to improving the yield. Therefore, in the manufacturing process flow shown in FIG. 1, a manufacturing method in which the following steps surrounded by broken lines are added is cited as the third and fourth embodiments.
[0050]
As a method of manufacturing the speaker diaphragm 30 according to the third embodiment of the present invention, in the manufacturing process flow of the speaker diaphragm of FIG. 1, the bonded sheet 15 containing the thermosetting resin 17 is semi-dried. Immediately after the step (g) of semi-drying until the state is reached, the weight of the laminated sheet 15 in which the thermosetting resin 17 is semi-dried is measured, and the laminated sheet having a specified weight or less is again cured with the thermosetting resin. 17. A weight optimizing step (g1) is provided which returns to step (f) including step 17 and starts over.
[0051]
For example, it is determined by weight evaluation whether the degree of impregnation of the thermosetting resin 17 is in an appropriate state based on the density and other characteristics of the wooden sheet 10 of the material, and if it is within the appropriate range, the next secondary press heating is performed. The process proceeds to the molding step (h). If it is too heavy, it cannot be regenerated and discarded at this point. If it is too light, the impregnation of the thermosetting resin 17 is insufficient and the process returns to the step (f).
[0052]
Next, as a method of manufacturing the speaker diaphragm 30 of the fourth embodiment according to the present invention, in each of the manufacturing methods of the first and second embodiments, a step (h) of performing secondary press heat molding. Immediately after the measurement, the propagation speed of the sound wave of the bonded sheet 15 after the secondary press heat molding is measured by, for example, measuring the behavior of the ultrasonic wave generated by the YAG laser (pulse drive) 41 as shown in FIG. The measurement is performed using a displacement meter & FET analyzer 44, and the propagation speed is measured by a propagation speed measuring device 45 configured to obtain the propagation speed from the time delay. The laminated sheet 15 is provided with a propagation speed optimizing step (h1) of returning to the step (h) of performing the secondary press heat forming again and starting again.
[0053]
In other words, since uniform molding by secondary press heat molding may be insufficient due to individual differences (differences in density and the like) of the bonded sheets 15, the propagation speed of sound waves related to rigidity may vary slightly. Therefore, the propagation speed is evaluated, and if the value is equal to or less than the specified value, the step (h) of the secondary press heat molding is performed again to optimize the propagation speed at least once. Thus, by adding this step (h1), the quality (acoustic characteristics) can be stabilized and the yield can be improved.
[0054]
By adding the weight optimizing step (g1) and / or the propagation velocity optimizing step (h1) in the predetermined stage of the bonded sheet 15 described above, the yield is improved, and the quality of the wooden speaker diaphragm 30 is improved. Will also be achieved.
[0055]
Next, as a method for manufacturing the speaker diaphragm 30 according to the fifth embodiment of the present invention, as shown in FIG. At least a projection pin 38 is provided at the center of the lower mold 32 of the press device P1 used in the first press heat molding step (d), and a recess 39 is provided at the center of the upper mold 31 to fit the projection pin 38. The press heat molding is performed after the small holes 12 provided at the center of the bonded sheet 15 are inserted into the protruding pins 38 at the center of the lower mold 32 and positioned during the press heat molding. Thus, the workability of the press heat forming and the positional accuracy of the forming of the bonded sheet 15 are improved, so that the mass production efficiency and the yield can be improved. Of course, not only the primary press heat forming step (d) but also the press apparatus P2 of the secondary press heat forming step (h) and the press apparatus P3 of the tertiary press heat forming step as shown in FIG. 5 (h3). It is also preferable to provide similar projection pins 38 and depressions 39 so that positioning can be performed accurately and quickly. In addition, at the stage of the second and third press heat forming step, the shape is stable to a predetermined wrapper shape to some extent in the previous first press heat forming step. In the heat forming step (d), the positioning of the small holes 12 is particularly effective because the shape of the bonded sheet 15 is unstable before pressing.
[0056]
According to the study of the present inventors, the speaker diaphragm 30 manufactured by the above manufacturing method has a vertical propagation velocity of 4.5 to 6.0 km / sec and a horizontal propagation velocity of 2.0 to 4.0 km / sec. A diaphragm manufactured by the manufacturing method of each of the above-described embodiments by selecting wood in a range of 5 km / sec clearly has a higher resolution of reproduced sound than a conventional diaphragm made of paper pulp or an aluminum diaphragm. It has been found that improvement and crisp sound improvement can be obtained.
[0057]
Particularly remarkable improvement in acoustic characteristics is realized when the internal loss coefficient is in the range of 4.5 to 6.0 km / sec in the vertical propagation velocity and 2.0 to 2.5 km / sec in the horizontal propagation velocity. This is a case where wood in the range of 0.02 to 0.03 was selected and used for the diaphragm. Specifically, birch wood (pure) was the best.
[0058]
Needless to say, the speaker diaphragm of the present invention can be applied not only to the birch material but also to other timber such as beech, oak, cherry, and china.
[0059]
【The invention's effect】
As described above, the method for manufacturing a speaker diaphragm according to the present invention uses a single piece of wood as a raw material, and digests or beats wood fibers with a chemical as is present in the process of manufacturing a conventional paper pulp diaphragm. Since no processing is performed, it is possible to produce a diaphragm in which sound quality does not deteriorate.
[0060]
Since a boil process for softening, a physical process, and a chemical agent are not applied to the conventional diaphragm, it is possible to produce a diaphragm that does not deteriorate in sound quality.
[0061]
The generation of wrinkles and cracks at the time of press heat molding is prevented, and it is possible to obtain a uniform press heat molded article having a good finish and substantially no change with time such as deformation and cracks after production.
[0062]
Light and durable cone diaphragms can be manufactured, and diaphragms for all bands from woofers to full-range speakers can be manufactured.
[0063]
Since the positioning can be easily and accurately performed in the press heat forming process, the workability of setting to the press machine is improved, and a diaphragm having a good finish can be realized.
[0064]
By the weight optimizing process and the propagation speed optimizing process, the yield can be improved and the stable supply of the wooden diaphragm with stable quality can be provided at low cost.
[0065]
By adopting the speaker diaphragm for the dynamic speaker unit, a re-voice sound approaching the raw sound due to natural vibration due to the wooden structure can be obtained.
[0066]
Further, since natural wood grain appears on the surface, the appearance is luxurious.
[Brief description of the drawings]
FIG. 1 is a flowchart of a manufacturing process of a speaker diaphragm according to first to fifth embodiments of the present invention.
FIG. 2 is a schematic view showing each processing state (first half) of the manufacturing process flow chart.
FIG. 3 is a schematic diagram showing each processing state (second half) of the manufacturing process flow chart.
FIG. 4 is a schematic diagram illustrating a processing stage of a shape of wood as a raw material of the speaker diaphragm according to the present invention.
FIG. 5 is a schematic view showing an additional tertiary press heat forming process according to the manufacturing methods of the second and fifth embodiments of the present invention.
FIG. 6 is a view showing a measuring device for measuring a sound wave propagation velocity of a bonded sheet according to a manufacturing method of a fourth embodiment of the present invention.
FIG. 7 is a diagram illustrating a press device for primary and secondary presses and a press heat forming process according to a manufacturing method according to a fifth embodiment of the present invention.
FIG. 8 is a schematic diagram of a speaker diaphragm of a substantially trumpet-shaped dynamic cone speaker according to the present invention.
FIG. 9 is a view showing a procedure for manufacturing a conventional wooden diaphragm.
FIG. 10 is a view showing a procedure for manufacturing a conventional wooden diaphragm.
FIG. 11 is a graph showing the relationship between the internal loss coefficient of various types of wood and the sound propagation speed (vertical direction) together with aluminum and paper, which are conventional materials.
[Explanation of symbols]
Reference Signs List 6 Log 7 Cutting blade 10 Wooden sheet 11 Substantially V-shaped cuts 11a, 11b Both edges 12 Small hole 13 Non-woven fabric or Japanese paper 15 Laminated sheet 16 Lubricant having an action of giving and retaining moisture 17 Thermosetting Resin 18 Moisture proofing agent 25 Center hole 26 Hook 30 Speaker diaphragms 31, 34, 36 Upper die 33 Heaters 32, 35, 37 Lower die 38 Projection pin 39 Depression 41 YAG laser (pulse drive)
42, 43 Probe 44 Displacement meter & FET analyzer 45 Propagation velocity measuring device 46 Release agents P1, P2 Press device

Claims (5)

In a method for manufacturing a speaker diaphragm, the method includes a step of press-molding a single wooden sheet as a material into a substantially trumpet shape.
A first step of attaching a thin nonwoven fabric or Japanese paper to one side of one wooden sheet having a thickness of 0.1 mm to 0.9 mm to form a bonded sheet; and a second step of forming a central portion of the bonded sheet. Forming a small hole and a substantially V-shaped notch having the small hole as a vertex; and thirdly, the bonding sheet provided with the notch is provided with moisture to soften and hold moisture in the bonded sheet. And a fourth step of forming the bonded sheet containing the lubricant by primary press heat molding and temporarily forming the cut sheet into a substantially trumpet shape in which the cut edges are overlapped with each other. Fifth, a step of drying the temporarily formed laminated sheet, sixth, a step of including a thermosetting resin in the dried laminated sheet, and seventh, the thermosetting resin is included. The said bonding Eighth, a step of semi-drying the laminated sheet to a semi-dry state, a step of performing a second press heat molding of the bonded sheet in which the thermosetting resin is in a semi-dry state, and a ninth, a step of performing the secondary press heat molding. A step of applying a desiccant to the later bonded sheet, and tenth, a center hole for voice coil and an outer shape are removed from the bonded sheet to which the desiccant has been applied to form a predetermined dimension as a diaphragm And a method of manufacturing a speaker diaphragm. 2. The method for manufacturing a speaker diaphragm according to claim 1, wherein a releasing agent is added to a bonded sheet formed into a substantially trumpet shape after the secondary press heat molding, and drying is performed. A step of subjecting the bonded sheet to tertiary press heating before the step of applying a moisture-proof agent to the bonded sheet. The method for manufacturing a speaker diaphragm according to claim 1, wherein the thermosetting resin is immediately after the step of semi-drying the bonded sheet containing the thermosetting resin until it becomes a semi-dry state. A weight adjustment step of measuring the weight of the bonded sheet in a semi-dry state and returning the bonded sheet having a specified weight or less to the step of including the thermosetting resin again. Manufacturing method. In the method for manufacturing a speaker diaphragm according to claim 1 or 2, immediately after the step of heat-forming the secondary press, the propagation speed of sound waves of the bonded sheet after the heat-pressing of the secondary press is measured. A method for manufacturing a diaphragm for a speaker, comprising a propagation speed adjusting step of returning a bonded sheet having a value of speed or less to a step of performing second press heat forming again. In the method for manufacturing a diaphragm for a speaker according to claim 1, 2, 3, or 4, a projection pin is provided at least in a center portion of a lower die of a press device used for primary press heat molding. A recess is provided at the center of the upper mold to be fitted with the projection pin, and after a small hole provided at the center of the bonded sheet is inserted into the projection pin of the lower mold at the time of press heat molding and positioned, A method of manufacturing a diaphragm for a speaker, comprising performing press heat molding.

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