Cutters – for shaping – Comprising cutting edge bonded to tool shank
Reexamination Certificate
2000-09-13
2002-08-06
Tsai, Henry (Department: 3722)
Cutters, for shaping
Comprising cutting edge bonded to tool shank
C407S119000, C428S212000, C428S698000
Reexamination Certificate
active
06428249
ABSTRACT:
TECHNICAL FIELD
The present invention relates, in general, to a method of manufacturing diamond cutting tools through an instantaneous heating process and a quick cooling process and to a diamond cutting tool manufactured by the method and, more particularly, to a method of manufacturing diamond cutting tools by integrating a shank and a blank together into a desired cutting tool or a desired abrasion resistant tool through an instantaneous heating process and a cooling process, with the blank being made of natural diamond, polycrystalline diamond (PCD), chemical vapor deposited (CVD) thick or thin diamond, or a cubic boron nitride (CBN), the present invention also relating to a diamond cutting tool produced through such a method.
BACKGROUND ART
As well known to those skilled in the art, diamond and cubic boron nitrides are optimum materials of putting tools since they have a high abrasion resistance and high machining properties.
A variety of materials, such as natural diamond, polycrystalline diamond (PCD) sintered with metal, chemical vapor deposited (CVD) thick diamond produced through a vapor deposition process, and polycrystalline cubic boron nitrides (PCBN), have been proposed and used as materials of such diamond cutting tools.
The above-mentioned materials for the diamond cutting tools have been typically prepared in the form of sheet blanks. That is, when a desired diamond cutting tool or a desired diamond dresser (hereinbelow, referred to simply as “diamond cutting tool” for ease of description) is produced using such materials, it is necessary to primarily prepare a sheet blank
1
made of diamond, PCBN or CVD thick diamond, and to firmly integrate the blank
1
with a shank
3
into a single body using a welding material
2
as shown in
FIGS. 1 and 2
. In such a diamond cutting tool, the welding material
2
is made of a welding metal alloy, while the shank
3
acts as a support of the cutting tool and is typically made of a cemented carbide (WC-Co alloy) or a tool steel.
In the above diamond cutting tool, the welding material
2
, or the integration material used for jointing the blank
1
to the shank
3
, also acts at a medium transmitting the cutting load to the shank
3
, with the cutting load being generated between the blank
1
and a workpiece during a cutting operation of the tool. Therefore, it is necessary for the welding material
2
to have a high strength enough to effectively resist against such cutting load and to retain the integration of the blank
1
with the shank
3
.
It has been thus noted that the technique of integrating the blank
1
with the shank
3
using such a welding material is a very important factor while producing such a diamond cutting tool.
In the prior art, such an integration has been accomplished through a welding process using a torch lamp or an induction heater.
However, such a conventional welding process of producing the diamond cutting tools has to be performed under the condition that the welding material is heated at a high temperature and is exposed to atmospheric air. The welding process thus undesirably oxidizes the welding layer, formed in a resulting tool by the welding material, and forms a plurality of pores in the structure of the welding layer. This finally reduces the physical properties of the resulting cutting tools. Another problem, derived in the conventional welding process, resides in that the process has to be performed manually and undesirably reduces productivity while producing such tools. The conventional welding process also allows the physical properties of resulting tools to be different from each other in accordance with producers of the tools. It is thus almost impossible for the welding process to produce diamond cutting tools having equal properties.
In an effort to overcome the above-mentioned problems, another welding process using a vacuum furnace has been proposed.
However, the welding process using such a vacuum furnace consumes a lengthy period of time, at least 8-10 hours, while raising and lowering the temperature to desired degrees. The above process thus undesirably requires a lengthy period of processing time while producing the cutting tools. During this welding process, the shank is undesirably heated at a welding temperature, and so the shank is reduced in mechanical strength. Therefore, the resulting tools of the above welding process are regrettably limited in use.
The above-mentioned problems of the conventional processes finally result in an increase in the production cost of diamond cutting tools.
It is thus necessary to provide a new welding process of producing diamond cutting tools, which reduces the processing cost, produces diamond cutting tools having equal properties, and allows such cutting tools to be automatically produced in commercial quantity, thus almost completely overcoming the problems derived in the conventional processes.
DISCLOSURE OF THE INVENTION
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of manufacturing diamond cutting tools by heating both a diamond sheet blank and a welding material through an instantaneous heating process without heating a shank while appropriately controlling a welding atmosphere, thus integrating the blank with the shank into a desired diamond cutting tool and quickly producing a desired number of tools having equal properties.
In order to accomplish the above-mentioned object, the present invention uses a light heating process, using a halogen lamp, as the instantaneous heating process while producing diamond cutting tools. In the method of this invention, a welding chamber for blanks is designed to be controlled in both pressure and atmosphere so as to accomplish a desired degree of vacuum ranging from almost zero up to several ten Torr, thus accomplishing a desired atmosphere capable of preventing a thermal deterioration of a diamond blank, a welding metal or a shank material.
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patent: 3260029 (1991-11-01), None
English Translation of JP 3260029 dated Nov. 20, 1991.
Chae Ki Woong
Min Eoung Sik
Ladas & Parry
Precision Diamond Co., Ltd.
Tsai Henry
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