Cutting by use of rotating axially moving tool – Tool or tool with support – Having axial – core-receiving central portion
Patent
1983-12-13
1986-05-27
Weidenfeld, Gil
Cutting by use of rotating axially moving tool
Tool or tool with support
Having axial, core-receiving central portion
408227, 408233, 408703, 408713, B23B 4102, B23B 5104
Patent
active
045913030
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a drilling tool having a plurality of cutting tips (inserts) which enable it to perform trepanning.
BACKGROUND ART
Among contemporary drilling tools, the drilling tool for performing trepanning, to leave the central columnar portion of a material, generally has low cutting energy consumption and a small thrust at the time of cutting, as compared to other types of cutting tools for cutting into entire portions of pieces, such as those used in cutting a hole. For this reason, only limited machining power can be used effectively, and drilling with higher efficiency can be performed by the same cutting force as in other types of drilling tools. In addition to this advantage, the core portion which is removed can be reused.
However, such a trepan drilling tool comprises a cylindrical cutting tool which does not have a portion corresponding to the center of rotation, so that both chatter vibration and swinging tend to occur during cutting, particularly at the start of cutting. To avoid such problems in the conventional trepan drilling tool, a guide pad is mounted around the tool. Alternatively, a centering drill is mounted at the center of the tool, to reduce the chatter and swinging at the start of drilling, and a guide pad is mounted to guide the tool after the leading part has cut into the material.
In the conventional trepan drilling tool, a guide pad and a guide bush must be mounted, and these members must be adjusted before drilling. Furthermore, a center hole must be predrilled. As a result, the predrilling time becomes longer than the drilling time, so that the entire drilling operation becomes time-consuming and extremely inefficient.
Since the present invention has been contrived to eliminate the drawbacks described above, its primary object is to provide a trepan drilling tool which has good cutting force balance and reduces chatter vibration and swinging, both at the start of drilling and after the leading part has cut into a workpiece.
DISCLOSURE OF INVENTION
In a drilling tool having a plurality of cutting tips at the annular end of a cylindrical main body, allowing said tool to perform trepanning, the cutting tips are so disposed along the annular end of the main body as to be equidistantly spaced apart from each other, in such a way that the resultant force, which is produced by all of the cutting tips and acting at right angles to the axial direction of the main body, becomes smaller than the component of the cutting force, which is produced by each individual cutting tip and acting at right angles to the axial direction of the main body.
Furthermore, according to the present invention, in a drilling tool having a plurality of cutting tips at the annular end of a cylindrical main body, allowing said tool to perform trepanning, the cutting tips are equidistantly spaced apart from each other along the annular end of the main body, the cutting widths of the cutting tips in the radial direction of the main body are substantially equal, and an intermediate cutting tip among the cutting tips disposed at an intermediate position in the radial direction of the main body has a V-shaped cutting edge.
The cutting force is thus well balanced, and both chatter vibration and the swinging of the tool, at the start of drilling or after the leading part of the tool has cut into the workpiece, can be reduced. In addition to this advantage, since chatter/swinging prevention jigs such as a guide bush are not required, the preparation time for drilling can be shortened. Since a good cutting balance is obtained, drilling precision and efficiency are improved, and the worked surface is thereby smoothened.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a front view of a drilling tool according to an embodiment of the present invention;
FIG. 2 is a side view thereof;
FIG. 3 shows the disposition of cutting tips at the distal end portion of the tool shown in FIG. 1;
FIG. 4 shows the disposition of cutting tips according to another embodiment of the present invention;
FI
REFERENCES:
patent: 3548687 (1970-12-01), Holloway
patent: 3591306 (1971-07-01), Kaser
patent: 4129400 (1978-12-01), Wozar
patent: 4149821 (1979-04-01), Faber
patent: 4230429 (1980-10-01), Eckle
patent: 4500234 (1985-02-01), Orth et al.
Miyamoto Tatsuo
Sasaki Ken-ichi
Sato Yoshihiro
Tsuzaka Hideo
Bishop Steven C.
Tokyo Shibaura Denki Kabushiki Kaisha
Toshiba Tungaloy Co., Ltd.
Weidenfeld Gil
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