Cutting tip, cutting method, and cutting-processed element

Details Cutting tip, cutting method, and cutting-processed element Cutting tip, cutting method, and cutting-processed element

2000-07-14

2003-07-22

Tsai, Henry W. H. (Department: 2183)

Turning

Process of turning

C407S114000, C407S115000

Reexamination Certificate

active

06595092

ABSTRACT:

INCORPORATION BY REFERENCE
The entire disclosures of Japanese Patent application Nos. H11-202867 and H11-20268, both filed Jul. 15, 1999, inclusive of their specifications, claims and drawings are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel cutting tip used as a tool for a cutting process, and a cutting method using the novel cutting tip.
2. Description of the Related Art
When a cutting process is performed on a metallic material, the process is normally performed by setting a cutting tip in a machine tool, such as a lathe or the like, and by moving the cutting tip relative to the workpiece while keeping the cutting tip in contact with the workpiece.
Cutting tips vary in correspondence to the shapes of workpieces, desired shapes of cut, and the like. For example, there are cutting tips of various shapes, such as a triangular shape, a quadrangular shape, a rhombus shape, and the like.
As shown in
FIG. 21
, a conventional tip
9
, regardless of what shape it has, has a cutting face
91
and a flank face
92
, and a cutting edge
95
formed along a line of intersection between the cutting face
91
and the flank face
92
. Normally, the cutting tip
9
is set in a shank
99
that holds the cutting tip.
At the time of cutting, the cutting tip
9
is normally placed in contact with a workpiece, with the cutting face
91
standing with respect to the surface of the workpiece, and then it is moved relative to the workpiece. As a result, swarf is separated from the surface of the workpiece, with the cutting edge
95
being a boundary, and it is scooped out onto the cutting face
91
. Cutting processes for metallic materials achieve excellent dimensional precision, but cannot strengthen processed surfaces, unlike a process imparting plastic deformation. Therefore, various methods for strengthening a finished cut surface have been proposed.
For example, there is a method in which in a separate compression process, after the cutting process, the cut surface is pressed with a fillet tool or the like, thereby work-hardening the cut surface.
Japanese Utility Model Application Laid-Open No. HEI 7-20215, Japanese Utility Model Application Laid-Open No. SHO 63-116219, and like publications, have disclosed methods using a composite tool combining a cutting tool feature with a pressing tool feature. The use of such a tool makes it possible to perform successive cutting and compression processes using the same tool.
However, the above-described conventional cutting methods have the following problems.
In the method using a fillet tool or the like, the compression step needs to be separate from the cutting step, so that the overall process becomes complicated.
In the method using a composite tool combining a cutting tool feature with a pressing tool feature, the tool is limited to a specific purpose such as forming a hole, forming a flat surface, or the like. Therefore, the method is not easily applied to various different cutting processes.
SUMMARY OF THE INVENTION
The object of the present invention is to overcome the aforementioned problems. The invention is intended to provide a cutting tip that allows a compression process to be easily performed on a finished cut surface, and a cutting method using the cutting tip.
A first aspect of the invention provides a cutting tip having a cutting face and a flank face, wherein a compression-producing face for plastically deforming the workpiece is provided in at least a portion of an area between the cutting face and the flank face. The compression face intersects both the cutting face and a flank face at angles substantially less than 180 degrees, i.e. to define lines of intersection therewith.
The compression-producing face (hereinafter “compression face”) is a face for plastically deforming a workpiece, as mentioned above. The expression “plastic deformation” as used herein refers to work-hardening involving dislocation.
The compression face is provided on at least a portion of the area between the cutting face and the flank face. Therefore, the compression face may be provided throughout the entire length of a boundary portion between the cutting face and the flank face or may be provided in a portion thereof or in a plurality of separate sites therein.
With the cutting tip provided with a compression face between the cutting face and the flank face, it is possible to produce plastic deformation of the workpiece simultaneously with the cutting process, in a single step, merely by cutting in substantially the same manner as a conventional method.
When cutting with the cutting tip of the invention, the cutting tip is brought into contact with a surface of a workpiece and moved relative thereto in a cutting direction, with the compression face of the cutting tip facing the surface of the workpiece and with the cutting face standing with respect to that surface. In this manner, first, a portion of the workpiece that contacts the cutting face is separated as swarf. A portion of the material of the workpiece facing the compression face is left as a work-hardened “remaining” portion. Then, as the relative movement of the cutting tip progresses, the cut surface left on the workpiece is pressed by the compression face and thereby undergoes plastic deformation and becomes work-hardened. Hence, a work-hardened portion strengthened by plastic deformation is formed on the cut-finished surface over which the compression face of the cutting tip has passed during the cutting process.
According to a second aspect of the invention, a cutting edge may be formed on an intersection line between the compression face and the cutting face. That is, if a clear cut edge is provided at the intersection line between compression face and the cutting face, the separation of swarf can be smoothly performed. Therefore, the subsequent compression of the remaining portion of the surface material by the compression face can also be smoothly performed.
The cutting edge is the starting point for separation of swarf.
According to a third aspect of the invention, the angle formed between the compression face and the cutting face is less than 125 degrees. If this angle is not less than 125 degrees, the intersection line between the compression face and the flank face may act as a cutting edge, thereby creating a problem of failing to properly separate swarf from the workpiece portion and a problem of failing to achieve work-hardening by plastic deformation.
According to a fourth aspect of the invention, the height of the intersection line between the compression face and the cutting face may be set in accordance with a desired amount of plastic deformation. That is, plastic deformation is produced in that portion of the workpiece facing the compression face. Therefore, by setting the height of the intersection line, the amount of plastic deformation produced in the workpiece material can be easily adjusted.
The “height of the intersection line” can be expressed by, for example, the distance from the intersection line to the end of the compression face as viewed from the cutting face.
It is also possible to provide the compression face in the form of a curved surface whereby the intersection line is in the form of a curved line.
A fifth aspect of the invention provides a cutting method for cutting a workpiece by use of a cutting tip having a cutting face, a flank face, and a compression face provided between the cutting face and the flank face, and wherein that portion of the workpiece facing the cutting face is separated as swarf by relative movement of the cutting tip in a cutting direction while the compression face contacts a remaining portion of the workpiece facing the compression face to plastically deform that facing (remaining) portion by compression thereof.
In this cutting method, since a cutting tip having a compression face is used, compression, that is plastic deformation, is easily applied to a cut surface of a workpiece merely by performing a normal cutting operation, as described above.

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