Throw-away type end mill

摘要

First and second tips (4A) and (4B) are disposed on the outer periphery of the forward end of an end mill body (1) in the following manner. The tips (4A) and (4B) are displaced from each other in the peripheral direction of the end mill body (1). The rotation loci of edges of the first and second tips (4A) and (4B) around the axis (O) of the end mill body (1) are overlapped with each other. The edge of the first tip (4A) protrudes slightly farther toward the forward end of the end mill than the edge of the second tip (4B). Further, third tips (4C) ... are disposed adjacent to the base end of the second tip (4B) in such a manner that no gap is formed between the rotation locus of the edge of the third tip (4C) located most adjacent to the forward end of the end mill body and the rotation locus of the rear end of the second tip (4B). As a consequence, the second tip (4B) and the third tips (4C) ... can be spirally formed in the rearward rotating direction of the end mill as they go toward the base end of the end mill. The respective tips (4) ... are formed of only one type of tips of the same shape and dimensions.