Patent ID: 7950308

Claim:
A hammer for breaking polycrystalline silicon comprising: a rod-shaped handle portion; and a head portion extending in a direction intersecting a center axis of the handle portion at a leading end of the handle portion, wherein the head portion is provided with a head main body connecting with the handle portion, a striking part installed at one end of the head main body via a coupling shaft portion, and a counter weight portion installed at the other end of the head main body, the head main body, the coupling shaft portion, the striking part and the counter weight portion are formed integrally, and a first striking surface is formed at the striking part, the striking part is formed in a half-spherical shape, a second striking surface is formed at the counter weight portion wherein the second striking surface is formed in a half-spherical shape, a curvature radius R of the first striking surface and the second striking surface is the range of 5 mm to 30 mm, and a distance from the center axis of the handle portion to the first striking surface is farther than a distance from the center axis to the second striking surface.