JP3852126B2

JP3852126B2 - Sharp pencil

Info

Publication number: JP3852126B2
Application number: JP06736896A
Authority: JP
Inventors: 司佐々木
Original assignee: Pentel Co Ltd
Current assignee: Pentel Co Ltd
Priority date: 1995-02-28
Filing date: 1996-02-28
Publication date: 2006-11-29
Anticipated expiration: 2016-02-28
Also published as: JPH09183294A

Description

【０００１】
【産業上の利用分野】
本発明は、軸筒内に鉛芯繰り出し機構を配置すると共に、軸筒の先端に芯保持管を配置したシャ−プペンシルに関するものである。
【０００２】
【従来の技術】
筆記に連れ芯が短くなった場合、この芯は、鉛芯繰り出し機構である芯の把持を行なう三割チャック、ボ−ルチャックなどのチャックから開放される。チャックから開放された芯は、チャック先端からシャ−プペンシル（芯保護管）先端までの間に残ることになる。この残った芯（以下残芯という）は、芯戻り止め部材に軽く保持されているだけである。よって、この残芯部分で筆記を行うと芯が回転してしまい、筆記感が悪くなり、一般的には後続芯により押出し排出させたり、引き抜いたりして破棄してしまうものであった。さらに、芯戻り止め部材から外れた残芯であると、前述した現象は顕著にみられ、芯が自重により落下してしまう場合もあった。
【０００３】
【考案が解決しようとする課題】
そこで、この残芯を無くすか極力小にして芯を有効に活用するために、芯保護管に対する種々の提案がなされてきた。例えば、特開昭５６−１１８８９８号や特開昭５８−２０３０９９号に示される考案である。何れの考案も芯保護管の内面に突起を形成し、その突起を残芯に食い込ませることにより、残芯筆記時における回転を防止するものである。しかし、残芯の回転は防止できるものの、芯の表面に突起による傷を付けてしまい、細い芯の強度を著しく損ねてしまうものであり実用的ではなかった。
【０００４】
【課題を解決するための手段】
本発明は、上記問題点に鑑みてなされたものであり、軸筒内に鉛芯繰り出し機構を配置すると共に、軸筒の先端に芯保護管を配置したシャ−プペンシルにあって、この芯保護管の内側に筒状のゴム弾性部材からなる芯保持部材を配置すると共に、芯保持部材の前方に逃げ空間部を設け、これによって、前記芯保持部材を芯保護管に対して移動および／又は変形可能に挿着し、また、前記芯保護管における芯保持部材の前後にその芯保持部材の芯保護管からの脱落を防止する脱落防止手段を設けたことを第１の要旨とし、軸筒内に鉛芯繰り出し機構を配置すると共に、軸筒の先端に芯保護管を配置したシャ−プペンシルにあって、この芯保護管の内側に筒状のゴム弾性部材からなる芯保持部材を配置すると共に、芯保持部材の前方に逃げ空間部を設け、これによって、前記芯保持部材を芯保護管に対して移動および／又は変形可能に挿着し、また、前記芯保護管における芯保持部材の前後に固定リングを設けるか、或いは、前記芯保護管における芯保持部材の前方に絞り部、或いは、段部、或いは、縮径部を設けるか、或いは、芯保護管の中間部の外面に凹部を形成することによって内面に凸部を設け、さらに、前記芯保持部材の少なくとも芯挿通方向の端部内面に拡開部を形成するとともに、その拡開部を芯保持部材の中間部内面よりロ−ト状に形成したことを第２の要旨とするものである。
【０００５】
【実施例】
参照符号１は、シャ−プペンシルの軸筒であり、該軸筒１内には、チャックリング２を前方部外周に外嵌したチャック３（図中は三つ割チャックを示したが、一般にボールチャックと称されるチャックであってもよい）が配置されている。また、軸筒１の前方には先部材４が螺着されているが、先部材４は軸筒１と一体であっても良い。更に、先部材４の先端には金属、合成樹脂などよりなる芯保護管５が圧入されているが、その芯保護管５は先部材４と一体であってもよい。
参照符号６は、軸筒１の前方に外嵌されているグリップ部材である。また、参照符号７は、チャック体３などの芯繰り出し機構を後方に付勢（図中上方）するコイルスプリングなどの弾撥部材である。
尚、残芯を極力少なくするために、チャック３をチャック前進の際、芯保護管５の後端直前に位置するように配設したが、チャック３と芯保護管５との間に一般的なシャ−プペンシルに設置されているような、芯の後退を阻止するための芯戻り止め部材を配置しても良い。
【０００６】
以上の構成は、従来の一般的なシャ−プペンシルの構成と同じである。本発明の特徴は、芯保護管５の内側に芯Ｌを保持する芯保持部材８（残芯保持手段）を配置させた点にある。
【０００７】
以下、詳細に説明する。
前記芯保護管５の内側には、その芯保護管５の内径と略同径か若干大きな外径を有し、挿通する芯の外径より若干小径の内径を有する筒状のゴム弾性体からなる芯保持部材８が配置されている。勿論、芯を回転しないようにするための設定でもあり、また、芯の外径のバラツキを考慮してのことでもある。ちなみに、呼び値が０．５（日本工業規格：ＪＩＳＳ６０１３）の芯の芯保持部材５に対する保持力は、２０ｇｆ〜１００ｇｆ程度あればよいもので、残芯筆記時の回転は防止できるものである。よって、上記した材質からなる芯保持部材７の厚さや長さなどは、保持力が２０ｇｆ〜１００ｇｆ程度になるように形成されている。ここで、保持力とは、芯を芯保持部材に挿着し、その挿着状態より芯が芯の繰り出し方向に動いているときの抵抗力である。また、呼び値が０．５（日本工業規格：ＪＩＳＳ６０１３）の芯のバラツキの範囲は、０．５５ｍｍ〜０．５８ｍｍとされている。
また、芯保護管５の後方の内側には、芯保持部材８の後方への移動を防止する芯径と略同内径の固定リング９が圧入された状態で固定されている。そして、その固定リング９の後端内面には、芯Ｌが通過しやすいようにロ−ト状（ロ−ト部９ａ）に形成されている。この固定リング９によって芯Ｌの径方向の振れも防止している。
また、前記芯保持部材８の長手方向の長さＹは、芯保持部材８の直径（外径）よりも長く形成されている。具体的には、芯保持部材の直径の少なくとも０．６倍以上の長さを有している。芯保持部材の直径よりも短いと、芯を芯保持部材に挿入した際、芯保持部材がその端面部から内側方向にめくれてしまったり、また、芯保持部材が倒れてしまったりする危険性があるからである。尚、長さＹの最大長さは、前記チャック体３の最前進位置までであることは云うまでもないが、あまり長くすると、組立性も悪くなり生産性が悪くなる。また、芯の繰り出し性能的な試験結果から、芯の硬さ、芯の芯保持部材への圧入力などによっても多少変わるが、多くとも（長くても）芯保持部材の直径の３倍以下が好ましいようである。以下、組立の容易性、芯繰り出し性能の良好性の観点から試験した結果を表１に示す。尚、芯保持部材の直径に下記Ｘを積した値が試験した芯保持部材の長さＹとなる。例えば、芯保持部材の直径が０．７ｍｍで、下記Ｘを０．２とした場合には、０．７×０．２となり、長さＹ＝０．１４ｍｍの芯保持部材を試験したことになる。
また、芯の直径（呼び値）が０．５ｍｍ（日本工業規格：ＪＩＳＳ６０１３）のものを使用し試験をした。
【０００８】
【表１】

Ｘ：芯保持部材の直径に積した数、※１：芯保持部材が倒れる、※２：芯保持材が倒れているため芯が出ない、※３：芯保持部材が座屈する、挿入できない
【０００９】
次に、前記Ｘが１．０並びに２．０の芯保持部材で、芯保持力を変化させ、芯の繰り出し性能（Ａ）、並びに、回転防止性能（Ｂ）を試験した。その結果を表２に示す。
【００１０】
【表２】

△：良好なときと、不良なときとが混在保持力の単位：ｇｆ
【００１１】
一方、前記芯保護管５の前端部は、内側に向かって円弧状に絞られており（絞り部５ａ）、芯保持部材８の前方への移動（芯保護管５からの脱落）を防止している。尚、芯保護管５の先端が円弧状に絞られているため、筆記の際、芯保護管５の先端が筆記面に当接してもひっかかることもなく、また、芯Ｌの先端が見やすくもなり良好に筆記することができる。
前記芯保護管５の先端形状は、芯保護管５の内側を切削などにより直角に加工し、段部５ｂとして形成（図３参照）してもよく、また、絞り加工あるいは圧延加工、切削加工などにより縮径部５ｃとして形成（図４参照）してもよいものである。前者においては、芯保持部材７の前端部における固定が確実なものとなり、後者においては、縮径部５ｃによりさらに先端が見やすくなり良好な筆記が得られるものである。
【００１２】
次に、筒状のゴム弾性体からなる芯保持部材８の材質について説明する。ゴムの材質は、種々あるが、芯が常に当接し摺動すること、また、芯にはワックスや油などの添加剤が含まれていることを考慮し、さらに、経時的な復元性の維持を望むと、ジメチル系、メチルビニル系、メチルフェニルビニル系、メチルフルオロアルキル系などのシリコ−ンゴムや、ウレタンゴム、エチレンアクリルゴム、エピクロルヒドリンゴム、アクリルゴム、エチレンプロピレンゴム、クロロプレンゴム、天然ゴム、イソプレンゴム、塩素化ポリエチレン、ニトリルゴムや、これらに他の成分をブレンドしたもの、例えば、具体的には前記エチレンプロピレンゴム、クロロプレンゴム、天然ゴムに液状ゴムなどをブレンドしたものや、スチレン系、オレフィン系、エステル系、ウレタン系などの熱可塑性エラストマ−などが挙げられ、要は、弾性が高く、永久ひずみ特性の低いゴム状弾性体であれば適宜のものが採用できる。
【００１３】
次に、芯保持部材８の芯保護管５への挿着方法について説明する。図１に示す例は、あらかじめ、芯保護管となるパイプと、芯保持部材となる筒状のゴム弾性体を適宜の長さに切断しておき、まず、芯保護管５の先端を絞った後、芯保持部材８を芯保護管５に挿入し、次いで、芯保護管５の後方から固定リング９を嵌入させ、最後に、芯保護管５を先部材４に圧入固定したものである。しかし、これに捕らわれることなく、例えば、あらかじめ、芯保護管となるパイプに芯保持部材となる筒状のゴム弾性体を挿入しておき、次いで、これを一緒に適宜の長さに切断し、最後に、芯保持部材８が挿着された芯保護管５を先部材４に圧入固定してもよい。尚、本例においては、芯保持部材を芯保護管の前方に配置したが、なるべく軽い保持力で芯の回転を防止できるようにしたためであり、中央部分に配置しても良い。
尚、芯保護管を先部材などと一体的に樹脂で成形した場合には、あらかじめ、芯保護管の前端内面に段部（図３に示すような）が形成されるよう成形し、成形後、芯保護管の後方から切断した芯保持部材を挿着しても良い。また、芯保護管の前端内面に段部を形成しない場合には、芯保持部材を挿着後、芯保護管の前端内面に前記固定リング９と同様な固定リングを圧入しても良い。
【００１４】
図５に示す例は、固定リング９の上方に鍔部９ｂを形成すると共に、その鍔部９ｂの中心部に、前例のロ−ト部９ａより大径のロ−ト部９ｃを形成したものである。大きなロ−ト部とすることにより、芯の固定パイプへの挿入が前例のものより更に向上する。また、残芯と後続する新芯との連結部に生じる芯ずれによる固定パイプへの挿入不良も防止される。
次に、この例における組立方法を説明する。あらかじめ適宜の長さに切断した芯保護管５の先端を絞った後、その芯保護管５に芯保持部材８を挿着する。次いで、その芯保護管５を先部材４に圧入固定する。最後に、固定リング９を先部材４の後方より挿入し、芯保護管５の後方に嵌入する。
【００１５】
次に、第２実施例について説明する。前例の芯保持部材に加え、芯の挿通により芯保持部材が変形しようとした際、その変形を容易となすために逃げ空間部を設けた例である。
第１例を図６、図７に示す。前記図３の拡大図でもある。芯保護管５の後方の内側には、芯保持部材８の後方への移動を防止する芯径と略同内径で、また、前記芯保持部材８の内径より若干大径の内径を有する固定リング９が圧入固定されている。そして、その固定リング９の後端内面には、芯が通過しやすいようにロ−ト状（ロ−ト状部９ａ）に形成されている。そして、前記芯保持部材８の内径と固定リング９の内径の差によって生じる段差が、芯保持部材８の逃げ空間部１０となっている。この逃げ空間部１０は、芯保持部材８の前方にも形成されており、芯保護管５の先端の孔５ａの内径を芯保持部材８の内径より若干大径にすることにより形成されている。符号１１がその逃げ空間部である。
次に、作用について説明する。図６の状態より、芯が挿通されると、あらかじめ芯Ｌが芯保持部材８に対して圧接されるように設定されているので、芯径のバラツキにより芯径が大きいものにあっては、圧接力も大きくなる。このようなときに、芯保持部材８の膨れようとする体積部分が端部方向に移動し、その移動した部分が最終的に逃げ空間部１０、１１に変形し（図７参照）、バラツキの有無に関わらず圧接力が平準化される。よって、芯径のバラツキが大きいものにあってもスム−ズな繰り出しがなされる。
【００１６】
第２例を図８に示す。前記第１例と異なる点は、芯保持部材８の前端と、芯保護管５の先端の孔５ａとの間に、その先端の孔５ａの内径よりも大きい内径を有する第２の固定リング１２を配置したことにある。前方の逃げ空間部１１を多く設けることにより、芯保持部材８の前方への変形をより容易にした例である。芯の繰り出す方向を考慮し、後方に比べ前方側の変形をより容易にしたのである。
次に、第３例を図９に示す。芯保持部材８の中間部に周状のあるいは等間隔の凹部１３を形成するとともに、芯保護管５の中間部には、その凹部１３と係合する凸部１４を形成したものである。この係合作用により芯保持部材８が芯保護管５に対して固定され、又、芯保持部材８の前方への変形がより容易になる。つまり、芯保持部材８の前方部分の全てが逃げ空間部１５となる
尚、本例において、前記芯保護管５の凸部１４は、外側方向より治具を押し当て、芯保護管を回転させることにより形成している（一般的には、ロ−ル加工とも云われている）。部分的に形成するよりも、容易に形成でき、高さなどが正確に調整できるためである。
【００１７】
第４例を図１０に示す。前記第１例の変形例であり、芯保持部材８の両端内面に面取り加工を施し、この面取り加工を施した部分を逃げ空間部１６とした例である。また、図１１、図１２に第５例を示すが、この例は、逃げ空間部を芯保持部材８の外周に形成したものである。詳しくは、芯保持部材８の外周縦方向に放射状に溝を形成し、その溝を逃げ空間部１７としたものである。芯の挿通により、芯保持部材８の膨れは、径方向（逃げ空間部１７）に移動する。芯保持部材となるパイプ部材を成形する際、この溝も形成されるようなダイス（金型）を使用すれば成形と同時に簡単にできるものである。
第６例を図１３に示す。芯保護管５の内側と芯保持部材８の外側との間に空間部を形成し、この空間部を逃げ空間部１８としたものである。前記第５例と、逃げ空間部を径方向にも設けたという点で類似している。
図１４は、第７例を示すものであるが、芯保持部材８を成形する際、その芯保持部材８の内部に気泡ができるように成形したものである。そして、この気泡を逃げ空間部１９としたものである。縦方向や径方向の規制を受けず、自由に変形できるものである。尚、前記気泡を有する芯保持部材の材質の例としては、ウレタンフォ−ムやフォ−ムラバ−、シリコンフォ−ム、ビニルフォ−ムなどが挙げられる。
第８例を図１５に示し説明する。芯保持部材８を芯保護管５に固定することなく、比較的自由に移動できるようにした例である。そして、この移動できる空間部を逃げ空間部２０としたものである。芯保持部材８の後方、前方に関わらず、また、自由な位置で変形できるものである。符号９は、芯保持部材８の後方からの脱落を防止する固定パイプである。
尚、前記図１にも示されているように、芯保護管５の先端を円弧状に絞ることによって、その円弧部分の内側部分を逃げ空間部２１としても良い。
【００１８】
次に、第３実施例について説明する。前記第１実施例及び／又は、第２実施例の芯保持部材に加え、その芯保持部材の芯挿通方向の内面端部に拡開部を形成し、芯Ｌが容易に芯保持部材に挿入するようにした例である。
第１例を図１６に示す。芯保持部材８の芯挿通方向の端部内面には、ロ−ト状の拡開部２２が形成されている。このロ−ト状の拡開部２２は、芯の径よりも大径であって、切削などによって形成しても良いが、射出成形などで芯保持部材を成形時に同時に形成しても良い。
また、芯保持部材８の後方で前記芯保護管５の後方の内側には、芯保持部材８の後方への移動を阻止する芯径と略同内径か若干大径で、また、前記芯保持部材８の内径より若干大径の内径を有する固定リング９が圧入固定されている。そして、その固定リング９の後端内面には、芯が通過しやすいようにロ−ト状部９ｃが形成されている。前記図５に示されているような固定パイプと同様なものである。
符号２３は、前記芯保持部材８と固定リング９との間に設けられた空間部であり、芯Ｌが芯保持部材６に挿通された際、芯保持部材６の膨れ上がりが変形できる逃げ空間部である。また、本例においては、前記拡開部２２も逃げ空間部の役割も果たしている。
前記芯保護管５の前端内面には、内側段部２４が形成されており、芯保持部材８の脱落を防止している。その内側段部２４の後端面は、ロ−ト状に形成されており、この部分も芯保持部材８の膨れ上がりが移動し変形する逃げ空間部２５となっている。
【００１９】
次に、作用について説明する。芯Ｌがチャック３により前進せしめられると、固定リング９のロ−ト状部９ｃによって芯Ｌが正確な位置に導かれ、やがて、芯保持部材８の拡開部２２へと導かれる。そして、拡開部２２によっても芯Ｌは正確に位置決めされ、芯保持部材８にスム−ズに挿通される。
芯Ｌが芯保持部材８に挿通されると、あらかじめ芯Ｌが芯保持部材８に対して圧接されるように設定されているので、芯径のバラツキにより芯径が大きいものにあっては、圧接力も大きくなってしまい膨れ上がろうとする。しかし、このようなとき、芯保持部材８の端部が逃げ空間部２３、２５並びに、拡開部２２の部分に移動変形し、バラツキの有無に関わらず圧接力が平準化される。よって、芯径のバラツキが大きいものにあってもスム−ズな繰り出しがなされる。
【００２０】
第２例を図１７に示す。前記第１例と異なる点は、芯保持部材にある。本例における芯保持部材２６は、長い筒状のゴム弾性体（所謂、チュ−ブと云われているもの）から適宜長さに切断したものである。従って、その切断面は、芯保持部材２６の長手方向に対して垂直になっている。しかし、切断したままの状態で芯保護管に挿着し使用すると、芯Ｌが芯保持部材２６に挿通させる際、芯保持部材２６の端部内面の角部に芯Ｌが接触してしまい芯Ｌの挿通が不完全なものとなってしまう。そこで、本例は、前例における固定リング９の先端内面に大径孔部２７を形成し、その大径孔部２７の前端面を前記芯保持部材２６の後端に圧接することにより、その芯保持部材２６の後端を広げ、拡開部２８を形成したのである。そして、この拡開部２８によって芯Ｌは正確に位置決めされ芯保持部材２６に挿通されるのである。
符号２９は、前記拡開部２８が形成されるための芯保護管５の内面凹部でもあり、また、芯が挿着されたときの芯保持部材２６の膨れ上がりが変形する逃げ空間部でもある。
【００２１】
第３例を図１８に示し説明する。本例も前記第２例と同様に、芯保持部材を、長い筒状のゴム弾性体（所謂、チュ−ブと云われているもの）から適宜長さに切断したものである。そして、相違する点としては、拡開部を形成する方法にある。本例においては、固定リング９の前端に、芯保持部材８の後方内側に挿入する挿入筒部３０を形成したのである。この挿入筒部３０により芯保持部材８の後端は、広げられ拡開部３１が形成される。
尚、前記第２実施例における第２例、第３例において、各々の芯保持部材を図示の如く、射出成形により形成すれば、固定リングの先端の加工（ロ−ト部、挿入筒部）は必ずしも必要ないものである。また、第２例、第３例においては、芯保護管５の先端内面を芯保持部材２６（８）の内径より大径とすることにより、その段差部分を逃げ空間部３２ともしている。
【００２２】
【発明の効果】
本発明は、軸筒内に鉛芯繰り出し機構を配置すると共に、軸筒の先端に芯保護管を配置したシャ−プペンシルにあって、この芯保護管の内側に筒状のゴム弾性部材からなる芯保持部材を配置すると共に、芯保持部材の前方に逃げ空間部を設け、これによって、前記芯保持部材を芯保護管に対して移動および／又は変形可能に挿着し、また、前記芯保護管における芯保持部材の前後にその芯保持部材の芯保護管からの脱落を防止する脱落防止手段を設けたことを第１の要旨とし、軸筒内に鉛芯繰り出し機構を配置すると共に、軸筒の先端に芯保護管を配置したシャ−プペンシルにあって、この芯保護管の内側に筒状のゴム弾性部材からなる芯保持部材を配置すると共に、芯保持部材の前方に逃げ空間部を設け、これによって、前記芯保持部材を芯保護管に対して移動および／又は変形可能に挿着し、また、前記芯保護管における芯保持部材の前後に固定リングを設けるか、或いは、前記芯保護管における芯保持部材の前方に絞り部、或いは、段部、或いは、縮径部を設けるか、或いは、芯保護管の中間部の外面に凹部を形成することによって内面に凸部を設け、さらに、前記芯保持部材の少なくとも芯挿通方向の端部内面に拡開部を形成するとともに、その拡開部を芯保持部材の中間部内面よりロ−ト状に形成したことを第２の要旨としたので、残芯を有効に使用することができると共に、芯の強度を損ねることもない。
【図面の簡単な説明】
【図１】本発明の第１実施例を示す要部縦断面図。
【図２】図１に相当し芯を挿着状態を示す要部縦断面図。
【図３】本発明の芯保護管の他の例を示す要部縦断面図。
【図４】本発明の芯保護管の更に他の例を示す要部縦断面図。
【図５】本発明の固定リングの他の例を示す要部縦断面図。
【図６】本発明の第２実施例を示す要部縦断面図。
【図７】図６に相当し芯を挿着した状態を示す要部縦断面図。
【図８】本発明の逃げ空間部の他の例を示す要部縦断面図。
【図９】本発明の逃げ空間部の更に他の例を示す要部縦断面図。
【図１０】本発明の逃げ空間部の更に他の例を示す要部縦断面図。
【図１１】本発明の逃げ空間部の更に他の例を示す要部縦断面図。
【図１２】図１１のＡ−Ａ線断面図。
【図１３】本発明の逃げ空間部の更に他の例を示す要部縦断面図。
【図１４】本発明の逃げ空間部の更に他の例を示す要部縦断面図。
【図１５】本発明の逃げ空間部の更に他の例を示す要部縦断面図。
【図１６】本発明の３実施例を示す要部縦断面図。
【図１７】本発明の芯保持部材の他の例を示す要部縦断面図。
【図１８】本発明の芯保持部材の更に他の例を示す要部縦断面図。
【符号の説明】
１軸筒
２チャックリング
３チャック体
４先部材
５芯保護管
５ａ絞り部
５ｂ段部
５ｃ縮径部
６グリップ部材
７弾撥部材
８芯保持部材
９固定パイプ
９ａロ−ト部
９ｂ鍔部
９ｃロ−ト部
１０逃げ空間部
１１逃げ空間部
１２固定リング
１３凹部
１４凸部
１５逃げ空間部
１６逃げ空間部
１７逃げ空間部
１８逃げ空間部
１９逃げ空間部
２０逃げ空間部
２１逃げ空間部
２２ロ−ト状の拡開部
２３逃げ空間部
２４内側段部
２５逃げ空間部
２６芯保持部材
２７大径孔部
２８拡開部
２９逃げ空間部
３０挿入筒部
３１拡開部
３２逃げ空間部
Ｌ芯[0001]
[Industrial application fields]
The present invention relates to a sharp pencil in which a lead core feeding mechanism is disposed in a shaft cylinder and a core holding tube is disposed at the tip of the shaft cylinder.
[0002]
[Prior art]
When the lead is shortened in writing, the lead is released from a chuck such as a 30% chuck or a ball chuck for gripping the lead as a lead lead feeding mechanism. The lead released from the chuck remains between the tip of the chuck and the tip of the sharp pencil (core protection tube). The remaining core (hereinafter referred to as the remaining core) is only lightly held by the core detent member. Therefore, if writing is performed on the remaining core portion, the core rotates, and the writing feeling is deteriorated. In general, the core is pushed out by the subsequent core, or is pulled out and discarded. Furthermore, if the remaining core is removed from the core detent member, the phenomenon described above is noticeable, and the core may fall due to its own weight.
[0003]
[Problems to be solved by the invention]
Accordingly, various proposals have been made for the core protection tube in order to eliminate the residual core or minimize the core as much as possible. For example, it is devised as shown in JP 56-118898 and JP 58-203099. In either case, a protrusion is formed on the inner surface of the core protection tube, and the protrusion is bitten into the remaining core to prevent rotation during writing of the remaining core. However, although the rotation of the remaining core can be prevented, the surface of the core is damaged by a protrusion, and the strength of the thin core is remarkably impaired, which is not practical.
[0004]
[Means for Solving the Problems]
The present invention has been made in view of the above problems. A sharp pencil having a lead core feeding mechanism disposed in a shaft cylinder and a core protection tube disposed at the tip of the shaft cylinder is provided. A core holding member made of a cylindrical rubber elastic member is disposed inside the tube, and a relief space is provided in front of the core holding member, whereby the core holding member is moved with respect to the core protection tube and / or The first gist of the present invention is to provide a drop-off prevention means for preventing deformation of the core holding member from the core protection tube before and after the core holding member in the core protection tube. A lead pencil feeding mechanism is arranged in the inside of the pencil and a core pencil is arranged at the tip of the shaft cylinder, and a core holding member made of a cylindrical rubber elastic member is arranged inside the core protection tube. And escape space in front of the core holding member Provided, or whereby, the core holding member inserted and attached moving and / or deformable with respect to the core protecting tube, also provided fixing ring around the core holding member in the core protecting tube, or the core Providing a convex part on the inner surface by providing a constricted part, a stepped part, or a reduced diameter part in front of the core holding member in the protective tube , or forming a concave part on the outer surface of the intermediate part of the core protective tube , Furthermore, the expansion portion is formed at least on the inner surface of the end portion of the core holding member in the core insertion direction, and the expanded portion is formed in a funnel shape from the inner surface of the intermediate portion of the core holding member. It is what.
[0005]
【Example】
Reference numeral 1 denotes a shaft cylinder of a sharp pencil. In the shaft cylinder 1, a chuck 3 having a chuck ring 2 fitted on the outer periphery of the front portion (in the figure, a three-part chuck is shown, It may be a chuck called a chuck). Further, the front member 4 is screwed in front of the shaft tube 1, but the front member 4 may be integrated with the shaft tube 1. Further, a core protection tube 5 made of metal, synthetic resin or the like is press-fitted into the tip of the tip member 4, but the core protection tube 5 may be integrated with the tip member 4.
Reference numeral 6 denotes a grip member that is fitted on the front side of the shaft tube 1. Reference numeral 7 denotes an elastic member such as a coil spring that urges a core feeding mechanism such as the chuck body 3 backward (upward in the figure).
In order to reduce the remaining core as much as possible, the chuck 3 is disposed so as to be positioned immediately before the rear end of the core protection tube 5 when the chuck advances, but the chuck 3 is generally disposed between the chuck 3 and the core protection tube 5. A core detent member for preventing the retraction of the core, such as that installed in a sharp pencil, may be arranged.
[0006]
The above configuration is the same as that of a conventional general sharp pencil. The feature of the present invention is that a core holding member 8 (remaining core holding means) for holding the core L is arranged inside the core protection tube 5.
[0007]
This will be described in detail below.
An inner diameter of the core protection tube 5 is a cylindrical rubber elastic body having an outer diameter substantially the same as or slightly larger than the inner diameter of the core protection tube 5 and having an inner diameter slightly smaller than the outer diameter of the core to be inserted. A core holding member 8 is arranged. Of course, it is also a setting for preventing the core from rotating, and also taking into account variations in the outer diameter of the core. Incidentally, the holding force of the core having a nominal value of 0.5 (Japanese Industrial Standard: JIS S 6013) with respect to the core holding member 5 may be about 20 gf to 100 gf, and rotation during writing of the remaining core can be prevented. . Therefore, the thickness and length of the core holding member 7 made of the above-described material is formed so that the holding force is about 20 gf to 100 gf. Here, the holding force is a resistance force when the lead is inserted into the lead holding member and the lead is moving in the feeding direction of the lead from the inserted state. Moreover, the range of the variation of the core whose nominal value is 0.5 (Japanese Industrial Standard: JIS S 6013) is 0.55 mm to 0.58 mm.
A fixing ring 9 having an inner diameter substantially the same as the core diameter for preventing the core holding member 8 from moving backward is fixed inside the rear side of the core protection tube 5 in a press-fitted state. The inner surface of the rear end of the fixing ring 9 is formed in a funnel shape (roof portion 9a) so that the core L can easily pass therethrough. The fixing ring 9 also prevents the core L from shaking in the radial direction.
The length Y of the core holding member 8 in the longitudinal direction is longer than the diameter (outer diameter) of the core holding member 8. Specifically, it has a length of at least 0.6 times the diameter of the core holding member. If the diameter of the core holding member is shorter than the diameter of the core holding member, there is a risk that the core holding member may be turned inward from the end surface when the core is inserted into the core holding member, or the core holding member may fall down. Because there is. Needless to say, the maximum length Y is up to the most advanced position of the chuck body 3. However, if the length is too long, the assemblability deteriorates and the productivity deteriorates. In addition, the test results of the lead feeding performance vary somewhat depending on the hardness of the lead and the pressure input to the lead holding member, but at most (even at most) less than three times the diameter of the lead holding member. Seems to be preferred. Table 1 shows the results of the test conducted from the viewpoint of ease of assembly and good core feeding performance. A value obtained by multiplying the diameter of the core holding member by the following X is the length Y of the tested core holding member. For example, when the diameter of the core holding member is 0.7 mm and the following X is 0.2, it becomes 0.7 × 0.2, and the core holding member having a length Y = 0.14 mm is tested. Become.
The test was performed using a core having a core diameter (nominal value) of 0.5 mm (Japanese Industrial Standard: JIS S 6013).
[0008]
[Table 1]

X: Number stacked on the diameter of the core holding member, * 1: The core holding member falls, * 2: The core holding member does not come out because the core holding material is tilted, * 3: The core holding member buckles or cannot be inserted. 0009
Next, the core holding force was changed with the core holding members having X of 1.0 and 2.0, and the core feeding performance (A) and anti-rotation performance (B) were tested. The results are shown in Table 2.
[0010]
[Table 2]

Δ: When good and bad are mixed Holding force unit: gf
[0011]
On the other hand, the front end portion of the core protection tube 5 is narrowed in an arc shape toward the inside (throttle portion 5a), and prevents the core holding member 8 from moving forward (dropping off from the core protection tube 5). ing. Since the tip of the core protection tube 5 is narrowed in an arc shape, even when the tip of the core protection tube 5 comes into contact with the writing surface during writing, the tip of the core L is easy to see. You can write well.
The tip shape of the core protection tube 5 may be formed as a stepped portion 5b by machining the inside of the core protection tube 5 at a right angle by cutting or the like (see FIG. 3), or by drawing, rolling or cutting. For example, it may be formed as the reduced diameter portion 5c (see FIG. 4). In the former, fixing at the front end of the core holding member 7 is ensured, and in the latter, the reduced diameter portion 5c makes the tip easier to see and good writing can be obtained.
[0012]
Next, the material of the core holding member 8 made of a cylindrical rubber elastic body will be described. There are various rubber materials, but considering that the core always contacts and slides, and that the core contains additives such as wax and oil, it is possible to maintain resilience over time. , Silicone rubber such as dimethyl, methyl vinyl, methyl phenyl vinyl, methyl fluoroalkyl, urethane rubber, ethylene acrylic rubber, epichlorohydrin rubber, acrylic rubber, ethylene propylene rubber, chloroprene rubber, natural rubber, Isoprene rubber, chlorinated polyethylene, nitrile rubber, and those blended with other components, such as, specifically, ethylene propylene rubber, chloroprene rubber, natural rubber blended with liquid rubber, styrene, Examples include olefin-based, ester-based, urethane-based thermoplastic elastomers, etc. In short, the elastic is high, those suitable may be employed if low rubber-like elastic body of permanent set properties.
[0013]
Next, a method for inserting the core holding member 8 into the core protection tube 5 will be described. In the example shown in FIG. 1, a pipe serving as a core protection tube and a cylindrical rubber elastic body serving as a core holding member are cut into appropriate lengths in advance, and the tip of the core protection tube 5 is first squeezed. Thereafter, the core holding member 8 is inserted into the core protection tube 5, and then the fixing ring 9 is fitted from the rear of the core protection tube 5. Finally, the core protection tube 5 is press-fitted and fixed to the tip member 4. However, without being caught by this, for example, in advance, a cylindrical rubber elastic body serving as a core holding member is inserted into a pipe serving as a core protection tube, and then cut together to an appropriate length, Finally, the core protecting tube 5 with the core holding member 8 inserted may be press-fitted and fixed to the tip member 4. In this example, the lead holding member is arranged in front of the lead protecting tube, but this is because the lead can be prevented from rotating with as little holding force as possible, and may be arranged in the center portion.
In addition, when the core protection tube is molded integrally with the tip member from resin, the core protection tube is molded in advance so that a step portion (as shown in FIG. 3) is formed on the inner surface of the front end of the core protection tube. A core holding member cut from the rear of the core protection tube may be inserted. Further, when a step portion is not formed on the inner surface of the front end of the core protection tube, a fixing ring similar to the fixing ring 9 may be press-fitted into the inner surface of the front end of the core protection tube after the core holding member is inserted.
[0014]
In the example shown in FIG. 5, a flange portion 9b is formed above the fixing ring 9, and a central portion of the flange portion 9b is formed with a rotor portion 9c having a diameter larger than that of the previous rotor portion 9a. It is. By using a large rotor portion, the insertion of the core into the fixed pipe is further improved than in the previous example. In addition, poor insertion into the fixed pipe due to misalignment occurring at the connecting portion between the remaining core and the subsequent new core is also prevented.
Next, an assembling method in this example will be described. After narrowing the tip of the core protection tube 5 that has been cut to an appropriate length in advance, the core holding member 8 is inserted into the core protection tube 5. Next, the core protection tube 5 is press-fitted and fixed to the tip member 4. Finally, the fixing ring 9 is inserted from the back of the tip member 4 and is inserted into the back of the core protection tube 5.
[0015]
Next, a second embodiment will be described. In addition to the lead holding member of the previous example, when the lead holding member is about to be deformed by insertion of the lead, an escape space portion is provided to facilitate the deformation.
A first example is shown in FIGS. It is also an enlarged view of FIG. A fixing ring having an inner diameter that is substantially the same as the inner diameter of the core holding member 8 and that is slightly larger than the inner diameter of the core holding member 8 is provided inside the rear of the core protection tube 5. 9 is press-fitted and fixed. And the inner surface of the rear end of the fixing ring 9 is formed in a funnel shape (a funnel portion 9a) so that the core can easily pass through. A step caused by the difference between the inner diameter of the core holding member 8 and the inner diameter of the fixing ring 9 is a relief space 10 of the core holding member 8. The escape space 10 is also formed in front of the core holding member 8, and is formed by making the inner diameter of the hole 5 a at the tip of the core protection tube 5 slightly larger than the inner diameter of the core holding member 8. . Reference numeral 11 denotes the escape space.
Next, the operation will be described. From the state of FIG. 6, when the core is inserted, the core L is set so as to be pressed against the core holding member 8 in advance, so that the core diameter is large due to variations in the core diameter, The pressure contact also increases. In such a case, the volume portion of the core holding member 8 which is about to swell moves in the direction of the end portion, and the moved portion finally deforms into the escape space portions 10 and 11 (see FIG. 7). The pressing force is leveled regardless of the presence or absence. Therefore, even if there is a large variation in the core diameter, smooth feeding is performed.
[0016]
A second example is shown in FIG. The difference from the first example is that the second fixing ring 12 has an inner diameter larger than the inner diameter of the hole 5a at the tip between the front end of the core holding member 8 and the hole 5a at the tip of the core protection tube 5. It is in having arranged. This is an example in which the lead holding member 8 is more easily deformed forward by providing a large number of front clearance spaces 11. In consideration of the direction in which the lead is extended, the deformation on the front side is made easier than on the rear side.
Next, a third example is shown in FIG. A circumferentially or equally spaced recess 13 is formed in the intermediate portion of the core holding member 8, and a convex portion 14 that engages with the recess 13 is formed in the intermediate portion of the core protection tube 5. By this engaging action, the lead holding member 8 is fixed to the lead protecting tube 5, and the lead holding member 8 can be more easily deformed forward. That is, all of the front portion of the core holding member 8 becomes the escape space 15. In this example, the convex portion 14 of the core protection tube 5 presses a jig from the outside direction to rotate the core protection tube. (Generally also referred to as roll processing). This is because it can be easily formed and the height can be accurately adjusted rather than partially formed.
[0017]
A fourth example is shown in FIG. This is a modification of the first example, in which chamfering is performed on the inner surfaces of both ends of the core holding member 8 and the chamfered portion is used as the escape space 16. FIGS. 11 and 12 show a fifth example. In this example, the escape space is formed on the outer periphery of the core holding member 8. Specifically, grooves are formed radially in the longitudinal direction of the outer periphery of the core holding member 8, and the grooves serve as escape spaces 17. Due to the insertion of the lead, the swelling of the lead holding member 8 moves in the radial direction (relief space 17). When a pipe member serving as a core holding member is molded, if a die (die) in which this groove is also formed is used, it can be simplified simultaneously with the molding.
A sixth example is shown in FIG. A space is formed between the inside of the core protection tube 5 and the outside of the core holding member 8, and this space is used as the escape space 18. This is similar to the fifth example in that relief spaces are also provided in the radial direction.
FIG. 14 shows a seventh example. When the core holding member 8 is molded, the core holding member 8 is molded so that bubbles are formed inside. This bubble is used as the escape space 19. It can be freely deformed without being restricted in the vertical and radial directions. Examples of the material of the core holding member having bubbles include urethane foam, foam rubber, silicon foam, vinyl foam, and the like.
An eighth example will be described with reference to FIG. This is an example in which the core holding member 8 can be moved relatively freely without being fixed to the core protection tube 5. Then, the movable space portion is the escape space portion 20. The core holding member 8 can be deformed at any position regardless of whether it is behind or in front. Reference numeral 9 denotes a fixed pipe that prevents the core holding member 8 from falling off from the rear.
As shown in FIG. 1, the inner portion of the arc portion may be used as the escape space portion 21 by narrowing the tip of the core protection tube 5 in an arc shape.
[0018]
Next, a third embodiment will be described. In addition to the core holding member of the first embodiment and / or the second embodiment, an expanded portion is formed at the inner surface end in the core insertion direction of the core holding member, and the core L is easily inserted into the core holding member. This is an example.
A first example is shown in FIG. On the inner surface of the end portion of the core holding member 8 in the core insertion direction, a funnel-shaped widened portion 22 is formed. The funnel-shaped widened portion 22 has a diameter larger than the diameter of the core, and may be formed by cutting or the like, but the core holding member may be formed simultaneously with molding by injection molding or the like.
The core holding member 8 has a core diameter that is substantially the same as or slightly larger than the core diameter that prevents the core holding member 8 from moving backward. A fixing ring 9 having an inner diameter slightly larger than the inner diameter of the member 8 is press-fitted and fixed. A funnel portion 9c is formed on the inner surface of the rear end of the fixing ring 9 so that the core can easily pass therethrough. This is similar to the fixed pipe as shown in FIG.
Reference numeral 23 denotes a space provided between the core holding member 8 and the fixing ring 9. When the core L is inserted through the core holding member 6, a clearance space in which the swelling of the core holding member 6 can be deformed. Part. Moreover, in this example, the said expansion part 22 also plays the role of the escape space part.
An inner step 24 is formed on the inner surface of the front end of the core protection tube 5 to prevent the core holding member 8 from falling off. The rear end surface of the inner stepped portion 24 is formed in a funnel shape, and this portion is also a relief space portion 25 where the swelling of the core holding member 8 moves and deforms.
[0019]
Next, the operation will be described. When the lead L is advanced by the chuck 3, the lead L is guided to an accurate position by the rotor-like portion 9 c of the fixing ring 9, and is eventually guided to the expanded portion 22 of the lead holding member 8. The lead L is accurately positioned by the expanded portion 22 and is smoothly inserted into the lead holding member 8.
When the core L is inserted through the core holding member 8, the core L is set in advance so as to be in pressure contact with the core holding member 8. Therefore, if the core diameter is large due to variations in the core diameter, The pressure contact force increases and tries to rise. However, in such a case, the end portion of the core holding member 8 is moved and deformed to the

escape space portions

23 and 25 and the expanded portion 22, and the pressure contact force is leveled regardless of the presence or absence of variation. Therefore, even if there is a large variation in the core diameter, smooth feeding is performed.
[0020]
A second example is shown in FIG. The difference from the first example is the core holding member. The core holding member 26 in this example is obtained by cutting a long cylindrical rubber elastic body (what is called a tube) to an appropriate length. Therefore, the cut surface is perpendicular to the longitudinal direction of the core holding member 26. However, if the core L is inserted into the core protection tube while being cut and used, when the core L is inserted through the core holding member 26, the core L comes into contact with the corners of the inner surface of the end of the core holding member 26. The insertion of L will be incomplete. Therefore, in this example, a large-diameter hole portion 27 is formed on the inner surface of the front end of the fixing ring 9 in the previous example, and the front end surface of the large-diameter hole portion 27 is pressed against the rear end of the core holding member 26 to thereby obtain the core. The rear end of the holding member 26 is widened to form an expanded portion 28. Then, the core L is accurately positioned and inserted through the core holding member 26 by the expanded portion 28.
Reference numeral 29 denotes an inner surface concave portion of the core protection tube 5 for forming the expanded portion 28, and also a relief space portion where the swelling of the core holding member 26 is deformed when the core is inserted. .
[0021]
A third example will be described with reference to FIG. In this example, similarly to the second example, the core holding member is appropriately cut from a long cylindrical rubber elastic body (so-called tube). The difference is in the method of forming the expanded portion. In this example, the insertion tube portion 30 to be inserted into the rear inner side of the core holding member 8 is formed at the front end of the fixing ring 9. By this insertion cylinder part 30, the rear end of the core holding member 8 is widened to form an enlarged part 31.
In the second and third examples of the second embodiment, if each core holding member is formed by injection molding as shown in the drawing, the end of the fixing ring (roof part, insertion cylinder part) is processed. Is not always necessary. Further, in the second example and the third example, the inner surface of the tip of the core protection tube 5 is made larger than the inner diameter of the core holding member 26 (8), so that the stepped portion is also used as the escape space portion 32.
[0022]
【The invention's effect】
The present invention is a sharp pencil in which a lead core feeding mechanism is disposed in a shaft cylinder and a core protection tube is disposed at the tip of the shaft cylinder, and is formed of a cylindrical rubber elastic member inside the core protection tube. with placing the core holding member, a space portion provided relief in front of the core holding member, thereby, moving and / or deformable and inserted the core holding member with respect to the core protecting tube, also the core protection The first gist is to provide a drop prevention means for preventing the core holding member from falling off from the core protection tube before and after the core holding member in the tube. A sharp pencil having a core protection tube arranged at the tip of the cylinder, a core holding member made of a cylindrical rubber elastic member is arranged inside the core protection pipe, and a relief space is formed in front of the core holding member. Thereby providing the lead holding member Moving and / or deformable and inserted the protective tube, also either providing a fixing ring around the core holding member in the core protecting tube, or forward stop portion of the core holding member in the core protecting tube Alternatively, a stepped portion or a reduced diameter portion is provided, or a convex portion is provided on the inner surface by forming a concave portion on the outer surface of the intermediate portion of the core protection tube, and at least the core insertion direction of the core holding member Since the second gist is that the expanded portion is formed on the inner surface of the end portion of the core and the expanded portion is formed in a funnel shape from the inner surface of the intermediate portion of the core holding member, the remaining core is effectively used. And the strength of the core is not impaired.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part showing a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of an essential part corresponding to FIG. 1 and showing a state where a core is inserted.
FIG. 3 is a longitudinal sectional view of an essential part showing another example of the core protective tube of the present invention.
FIG. 4 is a longitudinal sectional view of an essential part showing still another example of the core protective tube of the present invention.
FIG. 5 is a longitudinal sectional view of an essential part showing another example of the fixing ring of the present invention.
FIG. 6 is a longitudinal sectional view of an essential part showing a second embodiment of the present invention.
7 corresponds to FIG. 6 and is a longitudinal sectional view of an essential part showing a state in which a core is inserted. FIG.
FIG. 8 is a longitudinal sectional view of an essential part showing another example of the escape space portion of the present invention.
FIG. 9 is a longitudinal sectional view of an essential part showing still another example of a clearance space part of the present invention.
FIG. 10 is a longitudinal sectional view of a main part showing still another example of the escape space portion of the present invention.
FIG. 11 is a longitudinal sectional view of a main part showing still another example of the escape space portion of the present invention.
12 is a cross-sectional view taken along line AA in FIG.
FIG. 13 is a longitudinal sectional view of a main part showing still another example of the escape space portion of the present invention.
FIG. 14 is a longitudinal sectional view of a main part showing still another example of the escape space portion of the present invention.
FIG. 15 is a longitudinal sectional view of an essential part showing still another example of the escape space of the present invention.
FIG. 16 is a longitudinal sectional view of an essential part showing a third embodiment of the present invention.
FIG. 17 is a longitudinal sectional view of an essential part showing another example of the core holding member of the present invention.
FIG. 18 is a longitudinal sectional view of an essential part showing still another example of the core holding member of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shaft cylinder 2 Chuck ring 3 Chuck body 4 Tip member 5 Core protection tube 5a Restriction part 5b Step part 5c Reduced diameter part 6 Grip member 7 Repellent member 8 Core holding member 9 Fixed pipe 9a Roto part 9b Eave part 9c -Gap portion 10 Relief space portion 11 Relief space portion 12 Fixing ring 13 Recessed portion 14 Convex portion 15 Relief space portion 16 Relief space portion 17 Relief space portion 18 Relief space portion 19 Relief space portion 20 Escape space portion 21 G-shaped expanded portion 23 Escape space portion 24 Inner step portion 25 Escape space portion 26 Core holding member 27 Large-diameter hole portion 28 Expanded portion 29 Escape space portion 30 Insertion cylinder portion 31 Expanded portion 32 Escape space portion L core

Claims

A lead pencil feeding mechanism is arranged in the shaft cylinder, and a core pencil is provided with a core protection tube at the tip of the shaft cylinder. A core holding member made of a cylindrical rubber elastic member is provided inside the core protection tube. with placing, the space provided relief in front of the core holding member, thereby, the core holding member inserted and attached moving and / or deformable with respect to the core protecting tube, also the core retention in the core protecting tube A sharp pencil characterized in that drop prevention means for preventing the lead holding member from dropping from the core protective tube is provided before and after the member .

A lead pencil feeding mechanism is arranged in the shaft cylinder, and a core pencil is provided with a core protection tube at the tip of the shaft cylinder. A core holding member made of a cylindrical rubber elastic member is provided inside the core protection tube. with placing, the space provided relief in front of the core holding member, thereby, the core holding member inserted and attached moving and / or deformable with respect to the core protecting tube, also the core retention in the core protecting tube A fixing ring is provided before and after the member, or a throttle part, a step part, or a reduced diameter part is provided in front of the core holding member in the core protection pipe , or the outer surface of the intermediate part of the core protection pipe By forming a recess in the inner surface, a convex portion is provided on the inner surface, and further, an expanded portion is formed at least on the inner surface of the end portion in the core insertion direction of the core holding member, and the expanded portion is formed on the inner surface of the intermediate portion of the core holding member. More funnel Shah and said - Pupenshiru.