Cutting by use of rotating axially moving tool – With means to apply transient – fluent medium to work or product – Including tool with duct
Reexamination Certificate
1999-10-01
2001-03-27
Howell, Daniel W. (Department: 3722)
Cutting by use of rotating axially moving tool
With means to apply transient, fluent medium to work or product
Including tool with duct
C408S0010BD, C408S083000, C408S144000, C408S145000, C408S199000, C408S227000
Reexamination Certificate
active
06206617
ABSTRACT:
The present application is based on Japanese Patent Application No. 10-350320 filed Dec. 9, 1998, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a reamer, and a method of finishing a hole prepared in a workpiece made of aluminum or other material by using the reamer.
2. Discussion of the Related Art
In the art of finishing a hole prepared in a workpiece made of aluminum or other material with a high degree of roundness of the finished hole and a high degree of smoothness of the inner circumferential surface of the finished hole, a two-blade or a four-blade reamer has been employed. The two-blade reamer has two blades diametrically opposed to each other, and two guide pads each circumferentially spaced apart from the two blades by 90°. The four-blade reamer has four blades which are equiangularly spaced apart from each other by 90° in its circumferential direction. Further, for finishing a hole in a gun barrel or other deep hole, a single-blade reamer (gun reamer) has been conventionally used. However, these conventional reamers are not capable of assuredly satisfying severe reaming requirements, i.e., finishing the hole with a high degree of roundness and a high degree of surface smoothness, for example, a roundness of 7 &mgr;m or less and a surface roughness of 6z or less (6 &mgr;m or less in ten point height of irregularities (Rz)).
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to provide a reamer which is capable of finishing a hole prepared in a workpiece made of an aluminum or other material, with a high degree of roundness and a high degree of surface smoothness.
It is a second object of the invention to provide a method of finishing such a hole with a high degree of roundness and a high degree of surface smoothness, by using the reamer constructed according to the invention.
The above first object may be achieved according to any one of the following modes of the present invention, which are numbered and dependent from each other, like the appended claims, to indicate possible combinations of elements or features in preferred forms of the present invention.
(1) A reamer including;
a generally cylindrical cutter body having (a) a flute formed in an outer circumferential surface of the cutter body and extending from an axially distal end of the cutter body toward an axially proximal end of the cutter body, (b) a cutting blade portion positioned at a longitudinally distal end of a downstream one of widthwise opposite edges of the flute as viewed in a rotating direction of the reamer, and (c) a guide portion having a guide surface which is circumferentially adjacent to the flute and which circumferentially extends over at least 240° about an axis of the cutter body, the guide surface being a part of the outer circumferential surface of the cutter body.
The reamer constructed according to the present mode of the invention has the guide surface circumferentially extending over at least 240° about the axis of the cutter body. The cutting blade portion is positioned at the longitudinally distal end of the downstream one of widthwise opposite edges of the flute, namely, at the longitudinally distal end of the downstream one of the opposite edges which circumferentially define the flute. When this reamer is used to finish a hole prepared in a workpiece, the inner circumferential surface of the hole is cut with the cutter body of the reamer being guided at the guide surface by the inner circumferential surface of the hole. Thus, the reamer is held, over at least 240°, i.e., at least two-thirds of its periphery, by the inner circumferential surface of the hole, whereby the reamer is prevented from being radially displaced relative to the axis of the hole during the cutting operation, resulting in improved roundness and cylindricity of the hole. It is preferable that the guide surface circumferentially extend over at least 255°. It is more preferable that the guide surface circumferentially extend over at least 270°. The flute may extend in parallel with the axis, or alternatively may extend in a helical direction of the cutter body. It is noted that the present reamer is suitable, particularly, for finishing the hole prepared in an aluminum workpiece, although the reamer may be used for any other purpose.
(2) A reamer according to mode (1), wherein a radial distance from the axis to the guide surface is constant over a circumferential length of the guide surface.
(3) A reamer according to mode (1) or (2), wherein at least a portion of the generally cylindrical cutter body which is other than the cutting blade portion is made of the same material.
(4) A reamer according to mode (3), wherein the same material is a cemented carbide.
(5) A reamer according to any one of modes (1)-(4), wherein the cutting blade portion is coated with a ultra-high temperature and ultra-high pressure sintered compact.
In the reamer constructed according to this mode (5), the ultra-high temperature and ultra-high pressure sintered compact may be a sintered compact which is formed by sintering a diamond powder (for example, a mixture of natural diamond and artificial diamond), or a CBN sintered compact which is formed of a cubic boron nitride at a ultra-high temperature and under a ultra-high pressure.
(6) A reamer according to any one of modes (1)-(5), wherein the generally cylindrical cutter body further has a fluid passage formed therethrough, and a fluid supply spout communicating with the fluid passage and open in a flank face which is circumferentially contiguous to and positioned on a downstream side of the flute as viewed in the rotating direction, so that a fluid flowing through the fluid passage is delivered through the fluid supply spout to the flank face.
During the cutting operation, some cutting chips are likely to be moved toward the downstream side of the flute. If such cutting chips are drawn into a radial gap or clearance between the guide surface and the inner circumferential surface of the hole being cut, the inner circumferential surface of the hole is possibly scratched by the cutting chips, and also the cutting chips may stick to the guide surface, deteriorating the surface smoothness and the dimensional accuracy of the guide surface. According to the reamer of the present mode (6), the fluid spouts out of the fluid supply spout open in the flank face, so as to wash away or clean up the cutting chips from the downstream side of the flute, thereby preventing the cutting chips from entering the radial gap between the guide surface and the inner circumferential surface of the hole. Thus, the present reamer assures a further improved roundness of the hole and a further improved surface smoothness of its inner circumferential surface. It is possible to use a coolant liquid, a pressurized air (air blast) or any other suitable kind of fluid as the above-described fluid to be supplied to the fluid passage. Where the coolant fluid is used, the fluid can also serves to lubricate and cool the guide surface and the inner circumferential surface of the hole. It is more preferable to form another fluid supply spout in the flute.
(7) A reamer according to any one of modes (1)-(5), wherein the generally cylindrical cutter body has a second flute in addition to the flute as a first flute, the second flute being formed in the outer circumferential surface, extending from the axially distal end of the cutter body toward the axially proximal end of the cutter body, and circumferentially contiguous to and positioned on a downstream side of the first flute as viewed in the rotating direction, so that a lateral surface defined by widthwise opposite edges of the second flute is generally concaved toward the axis as viewed in a transverse cross section of the cutter body, and wherein a portion of the lateral surface which is circumferentially remotest from the first flute intersects with the outer circumferential surface of the cutter body at substantially right an
Kawazoe Tetsuhiro
Nakamura Motoshi
Nakanose Tetsuro
Sakai Hiroyasu
Tomioka Mitsuhiko
Fuji Seiko Limited
Howell Daniel W.
Oliff & Berridg,e PLC
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