【０００１】
【産業上の利用分野】
本発明は叩き鑿又は押し鑿等の平鑿の刃先を交換可能な替刃とした、替刃式鑿及びこれに用いる替刃に関する。
【０００２】
【従来の技術】
替刃式鉋は特公平５−３０６０１号等に開示され、現在広く用いられている。又従来の通常の木工用鑿は切れ味が鈍ると大工職人等の作業者が自らその鑿の刃を砥石で研ぐ必要があり、その研ぎには熟練した技能が必要であり、又熟練者でも長時間を要し、鑿の刃を研ぐためにかなりの時間と労力を要するという欠点があった。そこで、替刃式鉋と同様に刃先を替刃式とした替刃式鑿が提案され、意匠登録第８８２６２３号として開示されている。
【０００３】
上記意匠登録第８８２６２３に開示された替刃式鑿は、図１の正面図、図２の平面図、図３の底面図、図４のＡ−Ａ断面図に示すように、鑿本体１の刃裏面２に片刃平板状替刃３を嵌合装着し２本の雄ねじ４で固着してなる。
【発明が解決しようとする課題】
【０００４】
上記従来の替刃式鑿は一応製品として完成され、本願出願人が製造、販売しているものであるが、これを実際に使用すると、切削作業中に替刃と鑿本体の間に極めて微細な木の削り屑が挟まり、一旦微細な木屑が挟まると鑿の切れ味が極端に低下して快適に切削作業を行うことが困難であり、従来の替刃式鑿はプロの大工職人が使用する実用的な替刃式鑿としては、充分に使用に耐えるものではなかった。
【０００５】
従って本発明は替刃式鑿において、鑿本体と替刃の間に微細な削り木屑が全く挟まるおそれがなく、快適に切削作業を行うことができ、プロの大工職人が使用することができる替刃式鑿を提供することを目的とする。
【０００６】
【課題を解決するための手段】
上記目的を達成すべく、本発明者は鋭意研究を重ねた結果、叩き鑿等の柄尻を槌等で叩いて切削作業を行うと、槌で鑿の柄尻を叩いた際の衝撃により発生する振動により、鑿本体と替刃の間に瞬間的に微細な隙間を生じ、その隙間に微細な木屑が挟まってしまい、これが鑿の切れ味を損なう原因であることを発見した。従って、鑿を槌で叩いて鑿本体と替刃に衝撃が加わっても、鑿本体と替刃の間に微細な隙間も生じないようにする必要があることが判明した。
【０００７】
そこで本願発明者は鑿本体の従来の替刃式鑿において、鑿本体の刃裏面に設けた凹部に嵌合する替刃を従来の単なる片刃平板状替刃でなく、平板状替刃の刃表平面と刃先傾斜面の境界線である鎬線に沿って、該刃表平面から段状に、該鎬線から該替刃のみね部まで一定深さに切削して、該鎬線に沿って段部を形成し、該段部を蟻溝状に形成して段部の立上がり面が該刃表平面に対し鋭角をなすように形成すると共に、鑿本体の刃裏面に替刃がびったりと嵌合する凹部を設けることにより、鑿の柄尻を槌で叩いて刃先を木材に食い込ませた時、その打撃の衝撃で蟻溝状に形成した替刃の立ち上がり面がこれに当接する鑿本体の先端に圧接され、僅かな微小間隙も生ずることがなく、その間隙に微細木屑の嵌入が防止されることを見出し、本発明を完成するに到った。
【０００８】
即ち、本発明は木工用の平鑿の鑿本体の刃裏部に片刃の平板状替刃を着脱自在に装着した替刃式鑿において、該替刃の刃表平面と刃先傾斜面の境界線である鎬線に沿って、該刃表平面から段状に、該鎬線から該替刃のみね部まで一定深さに切削して、該鎬線に沿って段部を形成し、該段部を蟻状に形成して段部の立上がり面が該刃表平面に対し鋭角をなすように形成すると共に、該鑿本体の刃裏部に該替刃を嵌着するための該替刃と略同形の凹部を設け、該替刃の該段部の立ち上がり面に当接する鑿本体の先端部を該替刃の該立ち上がり面に密着する角度に形成したことを特徴とする替刃式鑿を要旨とする。
【０００９】
他の本発明は木工用の平鑿の鑿本体の刃裏部に片刃の平板状替刃を着脱自在に装着する替刃式鑿用の替刃において、該替刃の刃表平面と刃先傾斜面の境界線である鎬線に沿って、該刃表平面から段状に、該鎬線から該替刃のみね部まで一定深さに切削して、該鎬線に沿って段部を形成し、該段部を蟻状に形成して段部の立上がり面が該刃表平面に対し鋭角をなすように形成したことを特徴とする替刃式鑿用替刃を要旨とする。
【００１０】
【発明の実施の形態】
次に本発明の内容を図面により詳細に説明する。図５は本発明の替刃式鑿５の一例の平面図、図６は同底面図、図７は同穂先部の一部拡大平面図、図８は同底面図、図９はＢ−Ｂ断面図である。
【００１１】
鑿本体１の穂先部６の刃裏７は平面状をなし、その先端部に替刃３を丁度嵌合する凹部８を設ける。替刃３は鋼製平板よりなり、図１０及び図１１に示す凸字状平面形状を有し、その片面に片刃を設ける。片刃の刃先角θは通常の鑿の刃先角と同様とすることができる。刃先角θで傾斜した刃先傾斜面９と替刃３の刃表平面１０との境界線である鎬線１１に沿って段部１２を設け、鎬線１１からみね部１３まで替刃３の刃表平面１０を一定深さまで切削削除する。替刃３の刃表平面１０の階段状削除により、鎬線１１に沿って断面三角形状の突起１５が残される。段部１２の立ち上がり面１３は刃表平面１０に対して垂直でなく、みね部１３側に傾き、刃表平面１０と立ち上がり面１４のなす角φが９０度以下の鋭角に形成されている。その鋭角の角度は特に制限はないが、通常６０〜８９度が好ましく、８０〜８９°が更に好ましい。この鋭角の角度が小さ過ぎると鑿の使用時に柄尻２４を槌で叩いた時の衝撃が、立ち上がり面１４と刃表平面１０の鋭角の入り隅に集中して、強い力が加わり過ぎて好ましくない。
【００１２】
替刃３の厚みｄは特に制限はないが、１．５〜３ｍｍ程度が好ましく用いられる。この厚みｄが薄すぎると鑿の使用時の打撃による衝撃で替刃３が振動して好ましくなく、一定の厚み以上では使用の強度に影響がなく、替刃３の製造コストが嵩む。
【００１３】
刃表平面１０の切削深さ、即ち立ち上がり面１４の高さｈは特に制限はないが、０．３〜１ｍｍ程度が選ばれ、０．４〜０．６ｍｍが好ましい。この高さｈが大きいと、替刃３の製作の際の切削量が大きくなり、小さいと替刃３の立ち上がり面１４と鑿本体１の先端部１７との係合面積が小さくなり過ぎて好ましくない。
【００１４】
替刃３の刃先１６は刃先傾斜面９の傾斜角度を刃先角θに形成し、更にその刃先１６の先端部の極めて狭い幅の部分のみを、刃先角θよりも大きな刃先先端角に研磨するのが望ましい。これにより刃先１６の強度が増し、替刃３の寿命を延ばすことができる。また刃先角θよりも刃先先端角を大きく研磨することにより、替刃３の製造工程で、刃先傾斜面９を刃先角θに研磨する際には若干粗く研磨しておき、刃先先端部の極めて狭い部分のみを刃先角θよりも若干大きな角度に極めて精密に研磨することにより、替刃３の刃先１６の研磨工程の作業能率を高めると同時に、精密研磨により刃先１６が研磨できるため、切れ味の極めて優れた替刃３を効率よく生産することができる。
【００１５】
替刃３の材質は通常の鑿の刃先の材質と同様の鋼材質であってよいが、高速度鋼等の硬質鋼材を用いてもよい。又替刃３全体を均一な鋼材で形成してもよいし、替刃３の刃先１６から刃裏面２に沿う部分のみをより硬質の鋼材で形成してもよい。
【００１６】
一方替刃３を嵌合装着する鑿本体１の刃裏７に設ける凹部８は、替刃３の平面形状と同形で、替刃３の厚みｄと略同じ深さの凹部８を設ける。鑿本体１の刃表２３側の先端部は、通常の鑿と同様に刃先角と略同傾斜の傾斜面２１を設け、その先端部は、替刃３の段部１２の立ち上がり面１４の傾斜角と略等しい鋭角の傾斜角を有する先端傾斜面２２とする。先端傾斜面２２の高さは立ち上がり面１４の高さよりも若干低く形成するのが望ましい。これにより鑿本体１に替刃３を嵌合した際に、替刃３の刃先傾斜面９が鑿本体１の傾斜面２１よりも若干突出し、鑿で木材を切削する際に替刃３と鑿本体１の接合部の段違いが切削の障害となることがない。この替刃３の刃先傾斜面９と鑿本体１の傾斜面２１の関係が逆になり、鑿本体１の傾斜面２１の方が突出すると、鑿による木材の切削の際、その段差が切削の障害となり、円滑な切削作業が不可能となる。
【００１７】
また上記のごとく、替刃３を鑿本体１に装着した際に替刃３の刃先傾斜面９の方が若干突出する状態に嵌合しておくと、その段差が替刃３の刃先の一部に刃こぼれが生じたとき、替刃３の刃先を研ぐための研ぎ代となり、替刃３の刃先を少し研いで研削しても、替刃３の刃先傾斜面９と鑿本体１の傾斜面２１が同一平面になるまでは替刃３を研ぐことが可能となる。
【００１８】
替刃３の平面形状とこれを嵌着する鑿本体１の刃裏７の形状は、鑿本体１に嵌着した替刃３が刃先１６に平行な横方向に変位不能に保持するようにした保持手段を備えた形状である必要がある。即ち図１０に示す凸字状平面形状の替刃３とこれを嵌合する鑿本体１の刃裏７の、凸字状替刃３の凸字の両側の凹所に嵌合する保持突起１８により保持手段が構成され、刃裏７の凹部８に嵌合した替刃３は横方向には全く変位不能に保持される。
【００１９】
替刃３の平面形状は図１０に示すような凸字状形状である必要はなく、鑿本体１の刃裏７に形成する替刃の横方向の変位を完全に束縛して保持するための保持突起１８の形状に合わせて種々形状を採用することができる。図１０に示すように、替刃３を凸字状に形成して、凸字の両側の凹み部に嵌合する保持突起１８を鑿本体１の刃裏７に形成する方法のほか、例えば替刃３に１又は２個以上の保持用孔を設け、この保持用孔に丁度嵌合する保持突起１８を鑿本体１の刃裏７に設けてもよい。いずれの手段であっても、保持突起１８とこれに嵌合する替刃３の嵌合部は横方向にはぴったりと変位不能に嵌合すると共に、縦方向には、替刃３を鑿本体１に装着する際に、替刃３を縦方向に摺動して、上記蟻溝状段部１２を鑿本体１の先端部にびったりと嵌合させるために、若干縦方向の摺動を許容するように形成する必要がある。
【００２０】
替刃３には図１０に示すように１または２以上のねじ孔１９を設け、鑿本体１の刃裏７のそのねじ孔に対応する位置に雌ねじ孔２０を設け皿ビス状の雄ねじ４で替刃３を鑿本体１に締結する。このねじ孔１９は雄ねじ４を遊嵌しているので、この雄ねじ４をどんなに強く締結しても、この雄ねじ４による締結のみでは、替刃３を鑿本体１に完全に固定することは不可能であり、上記蟻溝状の段部１２と鑿本体１の先端部１７との嵌合、及び替刃３の横方向の変位不能の保持手段が必要となる。
【００２１】
本発明の替刃式鑿５を用いて木材等に孔穿け作業を行う際、鑿本体１の柄尻２４を槌等で叩くと、鑿本体１の先端部１７の先端傾斜面２２が替刃３の段部１２の立ち上がり面１４に圧接して、先端傾斜面２２と立ち上がり面１４がびったりと密着して、鑿本体１の先端部１７が蟻溝状の段部１２の入り隅に食い込むようにして、槌の衝撃を替刃３に伝えるため、槌による振動によっても、替刃３の立ち上がり面１４と鑿本体１の先端部１７の先端傾斜面２２の間に微小な隙間も全く生ずることがなく、その隙間に木の微細な削り屑が挟まる虞が全くない。従って替刃３と鑿本体１の間に微細な木屑の侵入による、鑿の切れ味の低下が全く生じない。
【００２２】
本発明の替刃式鑿はあらゆる種類の平鑿に適用することができ、向待鑿、追入鑿等の叩き鑿、押し鑿等に全て適用可能である。鑿の幅は用途に応じてあらゆる幅の鑿に適用することができる。
【００２３】
【発明の効果】
本発明の替刃式鑿によれば、鑿の刃先を研ぐ必要がなく、替刃３を交換して、予め替刃の製造工場で完全に研磨された替刃３を装着するだけで、極めて切れ味の優れた鑿を使用することができ、プロの大工職人でもその作業能率を大幅に高めることができる。
【００２４】
従来の替刃式鑿の欠点であった、替刃３と鑿本体１の極めて微小な隙間に、木の削り屑が挟まり、切れ味を損なう虞が全くなく、常に極めて優れた切れ味を保つことができる。
【図面の簡単な説明】
【図１】従来の替刃式鑿の正面図である。
【図２】従来の替刃式鑿の平面図である。
【図３】従来の替刃式鑿の底面図である。
【図４】従来の替刃式鑿のＡ−Ａ断面図である。
【図５】本発明の替刃式鑿の一例の平面図である。
【図６】本発明の替刃式鑿の一例の底面図である。
【図７】本発明の替刃式鑿の一例の穂先部の一部拡大平面図である。
【図８】本発明の替刃式鑿の一例の穂先部の一部拡大底面図である。
【図９】本発明の替刃式鑿の一例の穂先部の一部拡大Ｂ−Ｂ断面図である。
【図１０】本発明の替刃式鑿に用いる替刃の一例の平面図である。
【図１１】本発明の替刃式鑿に用いる替刃の一例のＣ−Ｃ断面図である。
１ 鑿本体
２ 刃裏面
３ 替刃
４ 雄ねじ
５ 替刃式鑿
６ 穂先部
７ 刃裏
８ 凹部
９ 刃先傾斜面
１０ 刃表平面
１１ 鎬線
１２ 段部
１３ みね部
１４ 立ち上がり面
１５ 突起
１６ 刃先
１７ 先端部
１８ 保持突起
１９ ねじ孔
２０ 雌ねじ孔
２１ 傾斜面
２２ 先端傾斜面
２３ 刃表
２４ 柄尻[0001]
[Industrial applications]
The present invention relates to a replaceable blade-type chisel in which the blade of a flat chisel such as a hitting chisel or a push chisel is replaceable, and a replaceable blade used for the same.
[0002]
[Prior art]
Spare blade planes are disclosed in Japanese Examined Patent Publication No. 5-30601 and are widely used at present. In addition, when the sharpness of conventional woodworking chisels becomes dull, it is necessary for a carpenter or other worker to sharpen the blade of the chisel with a grindstone, and sharpening requires skilled skills. The disadvantage is that it takes time and it takes considerable time and effort to sharpen the blade of the chisel. Therefore, a replaceable blade chisel having a replaceable blade as in the case of the replaceable blade plane has been proposed and disclosed as Design Registration No. 882623.
[0003]
As shown in the front view of FIG. 1, the plan view of FIG. 2, the bottom view of FIG. 3, and the cross-sectional view taken along line AA of FIG. A single-blade flat blade 3 is fitted and mounted on the blade back surface 2 and fixed with two male screws 4.
[Problems to be solved by the invention]
[0004]
The above-mentioned conventional blade-type chisel is tentatively completed as a product and manufactured and sold by the applicant of the present invention. Once the fine wood shavings are caught, the sharpness of the chisel will be extremely low and it will be difficult to perform comfortable cutting work once the fine wood shavings are caught. As a practical replaceable blade chisel, it was not enough to withstand use.
[0005]
Therefore, the present invention provides a spare blade type chisel, in which there is no danger of fine shavings being caught between the chisel body and the spare blade, the cutting operation can be performed comfortably, and a professional carpenter can use the spare blade. It is intended to provide a blade-type chisel.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor has conducted intensive research and found that when performing a cutting work by hitting the handle of a chisel with a hammer or the like, the impact generated when the handle of the chisel was hit with a hammer was performed. Due to the vibration, a minute gap was instantaneously generated between the chisel body and the spare blade, and fine wood chips were caught in the gap, which was found to be a cause of impairing the sharpness of the chisel. Therefore, it has been found that it is necessary to prevent a fine gap from being generated between the chisel body and the spare blade even if the chisel and the spare blade are impacted by hitting the chisel with a hammer.
[0007]
In view of the above, the present inventor of the present application has proposed a conventional blade-type chisel for a chisel body, in which the blade fitted to the concave portion provided on the back surface of the blade of the chisel body is not a conventional simple single-blade flat blade but a blade table of a flat blade. Along the ho-line, which is the boundary between the plane and the blade tip inclined surface, cut to a constant depth from the ho-line to the ridge of the spare blade, stepwise from the blade surface, and along the ho-line. A step is formed, and the step is formed in a dovetail shape so that a rising surface of the step forms an acute angle with respect to the blade surface, and a spare blade is attached to the back of the blade of the chisel body. By providing a fitting recess, when the handle of the chisel is hit with a hammer and the cutting edge is cut into the wood, the impact of the impact causes the rising surface of the dovetail blade formed in a dovetail shape to come into contact with this The present invention was found to be pressed against the tip of the slab, and to prevent the generation of fine wood chips into the gap without generating any minute gap. And it has completed.
[0008]
That is, the present invention relates to a blade-type chisel in which a single-blade flat blade is detachably mounted on the back of the chisel body of a flat chisel for woodworking. Along the ho line, the blade is cut in a stepped manner from the front surface of the blade, from the ho line to the ridge of the spare blade to a certain depth, and a step is formed along the ho line, and the step is formed. A part is formed in a dovetail shape so that the rising surface of the step is formed at an acute angle with respect to the front surface of the blade, and the spare blade for fitting the spare blade to the back of the blade of the chisel body is provided. A disposable blade-type chisel, wherein a concave portion having substantially the same shape is provided, and a tip portion of the chisel body that abuts on the rising surface of the step portion of the replacement blade is formed at an angle that is in close contact with the rising surface of the replacement blade. Make a summary.
[0009]
Another aspect of the present invention is a blade for a blade-type chisel in which a single-blade flat blade is detachably mounted on the back of the chisel body of a flat chisel for woodworking. Along the ho-line, which is the boundary of the surface, the blade is cut in a stepped manner from the front surface of the blade to a constant depth from the ho-line to the ridge of the spare blade to form a step along the ho-line. The present invention further provides a blade for a blade-type chisel, wherein the step is formed in a dovetail shape so that a rising surface of the step forms an acute angle with respect to the blade surface.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the contents of the present invention will be described in detail with reference to the drawings. FIG. 5 is a plan view of an example of the blade-type chisel 5 of the present invention, FIG. 6 is a bottom view thereof, FIG. 7 is a partially enlarged plan view of the same ear tip, FIG. 8 is a bottom view thereof, and FIG. It is sectional drawing.
[0011]
The blade back 7 of the tip portion 6 of the chisel body 1 has a flat shape, and a concave portion 8 is provided at the tip of the tip portion 6 for fitting the blade 3 exactly. The spare blade 3 is made of a steel flat plate, has a convex planar shape shown in FIGS. 10 and 11, and has a single blade provided on one surface thereof. The tip angle θ of a single blade can be the same as the tip angle of a normal chisel. A step portion 12 is provided along a ho-line 11 which is a boundary line between the blade-inclined surface 9 inclined at the blade angle θ and the blade surface 10 of the replacement blade 3, and the blade of the replacement blade 3 extends from the ho-line 11 to the ridge 13. The front surface 10 is cut and removed to a certain depth. Due to the stepwise deletion of the blade surface 10 of the replacement blade 3, a protrusion 15 having a triangular cross section is left along the horizontal line 11. The rising surface 13 of the step portion 12 is not perpendicular to the blade surface 10, but is inclined toward the ridge portion 13, and the angle φ between the blade surface 10 and the rising surface 14 is formed to be an acute angle of 90 degrees or less. The acute angle is not particularly limited, but is usually preferably 60 to 89 degrees, and more preferably 80 to 89 degrees. If the angle of this acute angle is too small, the impact when the handle 24 is hit with a hammer when using a chisel is concentrated on the sharp corners of the rising surface 14 and the blade surface 10, and a strong force is applied too much, which is preferable. Absent.
[0012]
The thickness d of the replacement blade 3 is not particularly limited, but is preferably about 1.5 to 3 mm. If the thickness d is too thin, the blade 3 vibrates due to the impact of the impact when the chisel is used, which is not preferable. If the thickness d is more than a certain thickness, the strength of use is not affected, and the manufacturing cost of the blade 3 increases.
[0013]
The cutting depth of the blade front surface 10, that is, the height h of the rising surface 14 is not particularly limited, but is selected to be about 0.3 to 1 mm, and preferably 0.4 to 0.6 mm. If the height h is large, the amount of cutting when manufacturing the spare blade 3 becomes large, and if the height h is small, the engagement area between the rising surface 14 of the spare blade 3 and the tip end portion 17 of the chisel body 1 becomes too small, which is preferable. Absent.
[0014]
The blade edge 16 of the replacement blade 3 forms the angle of inclination of the blade edge inclined surface 9 at the blade angle θ, and further grinds only a very narrow portion at the tip of the blade edge 16 to a blade tip angle larger than the blade angle θ. It is desirable. As a result, the strength of the blade edge 16 increases, and the life of the replacement blade 3 can be extended. Also, by polishing the blade tip angle larger than the blade angle θ, in the manufacturing process of the replacement blade 3, when polishing the blade inclined surface 9 to the blade angle θ, it is polished slightly coarsely, By sharply polishing only the narrow portion to an angle slightly larger than the blade angle θ, the work efficiency of the polishing process of the blade 16 of the spare blade 3 is improved, and at the same time, the blade 16 can be polished by precision polishing, so that the sharpness is sharp. Extremely excellent replacement blades 3 can be efficiently produced.
[0015]
The material of the spare blade 3 may be the same steel material as the material of the blade of a normal chisel, but a hard steel material such as high-speed steel may be used. Further, the entire replacement blade 3 may be formed of a uniform steel material, or only the portion of the replacement blade 3 from the cutting edge 16 to the blade back surface 2 may be formed of a harder steel material.
[0016]
On the other hand, the recess 8 provided on the blade back 7 of the chisel body 1 in which the replacement blade 3 is fitted and fitted has the same shape as the plane shape of the replacement blade 3 and a depth 8 substantially the same as the thickness d of the replacement blade 3. The tip of the chisel body 1 on the side of the blade table 23 is provided with an inclined surface 21 having substantially the same inclination as the included angle of the blade as in a normal chisel. The tip inclined surface 22 has an acute inclination angle substantially equal to the angle. It is desirable that the height of the tip inclined surface 22 be formed slightly lower than the height of the rising surface 14. Thus, when the spare blade 3 is fitted to the chisel body 1, the blade inclined surface 9 of the spare blade 3 slightly protrudes from the inclined surface 21 of the chisel body 1, and when cutting wood with a chisel, the spare blade 3 and the chisel are used. The step at the joint of the main body 1 does not hinder cutting. The relationship between the inclined surface 9 of the blade 3 and the inclined surface 21 of the chisel body 1 is reversed, and when the inclined surface 21 of the chisel body 1 protrudes, when cutting wood with a chisel, the step is reduced. It becomes an obstacle, making smooth cutting work impossible.
[0017]
As described above, when the blade 3 is fitted to the chisel body 1 so that the blade inclined surface 9 of the blade 3 is slightly protruded, the step becomes one of the blades of the blade 3. When the blade spills on the part, it becomes a sharpening allowance for sharpening the blade edge of the spare blade 3, and even if the blade edge of the spare blade 3 is slightly sharpened, the inclined surface 9 of the spare blade 3 and the inclination of the chisel body 1 are sharpened. The blade 3 can be sharpened until the surface 21 is flush with the surface.
[0018]
The plane shape of the spare blade 3 and the shape of the blade back 7 of the chisel body 1 to which the spare blade 3 is fitted are such that the spare blade 3 fitted to the chisel body 1 is held so as not to be displaceable in a lateral direction parallel to the blade tip 16. It is necessary that the shape has a holding means. That is, the holding blade 18 which fits in the concave portion on both sides of the convex shape of the convex replacement blade 3 on the blade back 7 of the chisel body 1 to which the blade 3 having the convex planar shape shown in FIG. , The replacement blade 3 fitted into the recess 8 of the blade back 7 is held so as not to be displaced in the lateral direction.
[0019]
The plane shape of the spare blade 3 does not need to be a convex shape as shown in FIG. 10, and is used to completely restrain and hold the lateral displacement of the spare blade formed on the blade back 7 of the chisel body 1. Various shapes can be adopted according to the shape of the holding projection 18. As shown in FIG. 10, besides the method of forming the replacement blade 3 in a convex shape and forming the holding projections 18 to be fitted into the concave portions on both sides of the convex shape on the blade back 7 of the chisel body 1, for example, The blade 3 may be provided with one or more holding holes, and a holding projection 18 which is fitted into the holding hole may be provided on the back 7 of the chisel body 1. In any case, the holding projection 18 and the fitting portion of the replacement blade 3 fitted thereto are fitted in the horizontal direction exactly and non-displaceably, and the replacement blade 3 is vertically When the blade 1 is mounted on the chisel 1, the spare blade 3 is slid in the vertical direction so that the dovetail-shaped stepped portion 12 is fitted to the tip of the chisel body 1 by a slight vertical sliding. It must be formed to allow.
[0020]
As shown in FIG. 10, the spare blade 3 is provided with one or more screw holes 19, a female screw hole 20 is provided at a position corresponding to the screw hole on the blade back 7 of the chisel body 1, and a countersunk screw-shaped male screw 4 is used. The blade 3 is fastened to the chisel body 1. Since the male screw 4 is loosely fitted in the screw hole 19, no matter how strongly the male screw 4 is fastened, it is not possible to completely fix the spare blade 3 to the chisel body 1 only by fastening with the male screw 4. In this case, the dovetail-shaped stepped portion 12 is fitted to the distal end portion 17 of the chisel body 1 and a holding means for displacing the blade 3 in the lateral direction is required.
[0021]
When drilling holes in wood or the like using the blade-type chisel 5 according to the present invention, the handle 24 of the chisel body 1 is hit with a hammer or the like, and the tip inclined surface 22 of the tip portion 17 of the chisel body 1 is replaced with a blade. 3 is pressed against the rising surface 14 of the step 12, and the tip inclined surface 22 and the rising surface 14 come into close contact with each other so that the tip 17 of the chisel body 1 bites into the entry corner of the dovetail-shaped step 12. In this way, since the impact of the hammer is transmitted to the spare blade 3, even a small gap is completely generated between the rising surface 14 of the spare blade 3 and the tip inclined surface 22 of the tip portion 17 of the chisel body 1 by the vibration of the hammer. There is no danger that fine shavings of wood will be caught in the gap. Therefore, the sharpness of the chisel does not deteriorate at all due to the intrusion of fine wood chips between the spare blade 3 and the chisel body 1.
[0022]
The blade-type chisel of the present invention can be applied to all kinds of flat chisels, and can be applied to all types of hitting chisels, push chisels, and the like, such as anti-machining chisels and additional chisels. The width of the chisel can be applied to chisels of any width depending on the application.
[0023]
【The invention's effect】
According to the spare blade type chisel of the present invention, there is no need to sharpen the blade of the chisel, and only by replacing the spare blade 3 and mounting the completely polished spare blade 3 in advance in a spare blade manufacturing plant, it is extremely difficult. A sharp chisel can be used, and even a professional carpenter can greatly increase the work efficiency.
[0024]
The extremely small gap between the blade 3 and the chisel body 1, which is a drawback of the conventional blade-type chisel, has no possibility of wood shavings being caught in the very small gap. it can.
[Brief description of the drawings]
FIG. 1 is a front view of a conventional blade-type chisel.
FIG. 2 is a plan view of a conventional blade-type chisel.
FIG. 3 is a bottom view of a conventional blade-type chisel.
FIG. 4 is a sectional view taken along line AA of a conventional blade-type chisel.
FIG. 5 is a plan view of an example of a replaceable blade chisel according to the present invention.
FIG. 6 is a bottom view of an example of the blade-type chisel of the present invention.
FIG. 7 is a partially enlarged plan view of a tip portion of an example of the replaceable blade chisel of the present invention.
FIG. 8 is a partially enlarged bottom view of a tip portion of an example of the replaceable blade chisel of the present invention.
FIG. 9 is a partially enlarged BB cross-sectional view of a tip portion of an example of the replaceable blade chisel of the present invention.
FIG. 10 is a plan view of an example of a spare blade used in the spare blade chisel of the present invention.
FIG. 11 is a sectional view taken along line CC of an example of a spare blade used in the spare blade chisel of the present invention.
DESCRIPTION OF SYMBOLS 1 Chisel body 2 Blade back surface 3 Spare blade 4 Male screw 5 Spare blade type chisel 6 Head part 7 Blade back 8 Concave 9 Blade tip inclined surface 10 Blade surface 11 Ho-line 12 Step 13 Minute part 14 Rising surface 15 Protrusion 16 Blade tip 17 Tip Part 18 Holding projection 19 Screw hole 20 Female screw hole 21 Inclined surface 22 Tip inclined surface 23 Blade table 24 Handle bottom