Sheath type disposable safety scalpel

A sheath type disposable safety scalpel consists of a blade, a handle, and a sheath, the blade is fixed on the front end of handle and the sheath covers the front end of handle handle and is connected with the handle through a sliding mechanism and a positioning mechanism;

• wherein:
• the positioning mechanism is formed by the matching of a button set on the top of sheath and a blade protection locking notch and a blade exposure locking notch at the side of the handle;
• the button is a flexible arm extending from the sheath and the flexible arm is set with a pressing portion, the flexible arm is transformed flexibly in the width direction of the handle when pressing the button, and a locking head is set at the end of flexible arm facing the side of handle;
• the blade protection locking notch is located in the blade protection position at the lateral face at the front of handle and the blade exposure locking notch is located in the blade exposure position at the lateral face in the middle of handle;
• the blade protection locking notch is the first concave notch, and a first blocking face is set at the right side of the first concave notch from the front face of the blade protection locking notch, and a first unlocking inclined face is set at the lower portion of first concave notch;
• the blade exposure locking notch is the second concave notch, and a second blocking face is set at the left side of the second concave notch, and a second unlocking inclined face is set at the lower portion of the second concave notch;
• under the assembly state, when the sheath presents the blade protection state in relation to the handle, the locking head is inserted into the blade protection locking notch to form the positioning and locking of blade protection and when the sheath presents the blade exposure state in relation to the handle, the locking head is inserted into the blade exposure locking notch to form the positioning and locking of blade exposure;
• under the blade protection state, when the button is pressed and pulled backward, the locking head climbs out of the blade protection locking notch along the first unlocking inclined face to unlock and slides backward along with the sheath until it drops in the blade exposure locking notch;
• under the blade exposure state, when the button is pressed and pushed forward, the locking head climbs out of the blade exposure locking notch along the second unlocking inclined face to unlock and slides forward along with the sheath until it drops in the blade protection locking notch, so that sheath slides between blade protection locking notch and blade exposure locking notch in relation to the handle.