Cutters – for shaping – Rotary cutting tool – Including holder having seat for inserted tool
Reexamination Certificate
1999-10-15
2001-05-15
Briggs, William (Department: 3722)
Cutters, for shaping
Rotary cutting tool
Including holder having seat for inserted tool
C407S048000, C407S113000, C408S143000, C408S226000
Reexamination Certificate
active
06231274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an end mill and, more particularly, to a throw-away end mill which is capable of carrying out slotting and profiling at once.
2. Description of the Related Art
An end mill which has end cutting edges and side cutting edges or peripheral cutting edges is used widely in a machine tool for slotting, stepping, curved-face milling and profiling. When milling a workpiece to obtain a curved groove or a stepped groove in a surface of the workpiece by the end mill, a groove of a predetermined depth is initially shaped by the end cutting edges of the end mill. Then , the end mill is fed along the groove to shape a curved face by cutting by the side cutting edges. A throw-away end mill which is provided with throw-away tips is conventionally used in the machine tool. The throw-away end mill for the specific purpose of milling curved grooves is provided with end cutting chips for slotting and peripheral cutting chips for curved face milling.
There are some drawbacks to the conventional throw-away end mill as follows. As any large diameter end mills capable of simultaneously carrying out slotting and curved face milling have not been available, when cutting a curved surface of a great width, end mill for the purpose of both slotting and a curved face milling tool, such as a circular cutter, are used in combination. The throw-away end mill capable of simultaneously carrying out both of slotting and curved face milling is subject to a highly intensive cutting force and is liable to chatter.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to solve those problems in the prior art and to provide an end mill capable of simultaneously carrying out both of slotting and curved face milling and of machining a workpiece smoothly without chattering or without breaking its cutting chips.
According to one aspect of the present invention, an end mill comprises a tool body, and throw-away chips attached to an end part of the tool body. Each of the throw-away chips has a cutting edge having a peripheral cutting circular edge section for shaping, and an end straight cutting edge section for end cutting smoothly merging into the peripheral circular edge section.
The end mill of the present invention is capable of carrying out both slotting and curbed-face milling because each of the throw-away chips on its end is provided with the cutting edge having both the peripheral circular cutting edge section and the straight cutting edge section.
Preferably, each of the throw-away chips is retained in place by two retaining faces perpendicular to a bearing face formed in a chip holding part at an end of the tool body to seat the throw-away chip thereon to prevent the chip from becoming loose or from being damaged.
According to the present invention, an arbor holding the tool body may be provided in its lateral surface with longitudinal carbide ribs to enhance the rigidity thereof. The highly rigid arbor suppresses the chattering of the chips of the end mill during machining.
Preferably, a plurality of longitudinal grooves are formed at equal angular intervals in the lateral surface of the arbor and the carbide ribs are fixedly embedded in the longitudinal grooves so that the arbor may have isotropic rigidity.
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Mori Michio
Sakai Husao
Yoneyama Masayoshi
Briggs William
Ergenbright Erica D.
Pillsbury & Winthrop LLP
Toshiba Kikai Kabushiki Kaisha
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