Blade mounting device for mounting blade of pushing cut tool
A blade mounting device allows a blade of a pushing cut tool that cuts a workpiece by pushing a cutting edge forward to be mounted on an impact tool. This blade mounting device has a blade mounting portion for mounting the blade on the blade mounting device and a tool mounting portion secured to the blade mounting portion in order to mount the blade mounting device on the impact tool. The blade mounting portion has a front end portion where an inverted tapered hole complementary to an inclined shape surface formed on a tang of the blade is formed. The tool mounting portion is provided with a through hole perpendicular to the center axis and a center hole that reaches a through hole from a front side end surface of the tool mounting portion along the center axis.
1. A blade mounting device for mounting a blade of a pushing cut tool that cuts a workpiece by pushing a cutting edge forward on an impact tool, the blade mounting device comprising:
a blade mounting portion configured to mount the blade on the blade mounting device; and
a tool mounting portion that is secured to the blade mounting portion and configured to mount the blade mounting device on the impact tool, wherein
the blade mounting portion has a front end portion where an inverted tapered hole is formed to be complementary to an inclined shape surface formed on a tang of the blade,
the tool mounting portion is provided with a through hole perpendicular to a center axis of the tool mounting portion and a center hole that reaches the through hole from a front side end surface of the tool mounting portion along the center axis,
the blade mounting device is configured such that an impact force applied from the impact tool to the blade mounting device is transmitted to the blade via an inner surface of the inverted tapered hole and the inclined shape surface, and
the blade mounting device further comprises a knocker including a knocker main body and a spring, the knocker being configured to allow hammering the tang forward, wherein
the blade mounting device is configured to mount a blade of a chisel as the blade,
the blade mounting portion is provided with a knocker housing hole that houses the spring and the knocker main body along the center axis of the blade mounting portion so that the spring and the knocker main body can be ordered in either direction along the center axis, and an air discharge hole and an air vent hole perpendicular to the center axis to reach the knocker housing hole from an outer surface of the blade mounting portion, the blade mounting portion being provided with the inverted tapered hole in a front side of the knocker housing hole,
the knocker housing hole has an inner diameter set to be larger than an inner diameter of a rear side end of the inverted tapered hole,
the knocker main body has a large diameter portion set to have an outer diameter identical to the inner diameter of the knocker housing hole and a small diameter portion disposed in a front side of the large diameter portion, the small diameter portion having an outer diameter smaller than an inner diameter of the spring,
the air discharge hole is provided such that the large diameter portion is positioned in a front with respect to the air discharge hole when the spring is brought into contact with both a side end surface of the knocker housing hole and the large diameter portion in a length, and
the air vent hole is provided in a front with respect to the air discharge hole.
2. The blade mounting device according to claim 1 , wherein the inclined shape surface and the inverted tapered hole have an inclined angle set to be in a range of 4° to 6°.
3. The blade mounting device according to claim 1 , wherein
a combination of the tool mounting portion and the tang of the blade, which are securely mounted on one another to transmit the impact force in the blade mounting device, is secured by meshing the inverted tapered hole of the blade mounting portion and the inclined shape surface of the tang of the blade.