Reamer

Details Reamer Reamer

1986-10-17

1989-01-03

Bilinsky, Z. R.

Cutting by use of rotating axially moving tool

With work-engaging structure other than tool or tool-support

Frictionally engaging sides of opening in work

407 62, 408703, 408229, B23D 7700

Patent

active

047952890

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to tools for machining holes and, more particularly, it relates to reamers.


PRIOR ART

There is known in the art a reamer according to U.S.S.R. Inventor's Certificate No. 804,259 issued on Mar. 13, 1974 and published on Feb. 15, 1981. Said prior art reamer comprises teeth each having a cutting portion and a smoothing portion adjacent one another. In the smoothing portion at least part of the rear surface is fashioned as a strip diverging in the direction away from the head portion of the reamer.
Since the front angle of the reamer tooth has one and the same value over the entire length, said prior art reamer fails to produce the required smoothing effect, this affecting the quality of machining holes, especially, in plastic metals and alloys.
The prior art reamer can only be used to perform preliminary reaming of holes in plastic metals and alloys.
The reaming of holes in other alloys is done to a precision of up to the ninth quality (H9). In so doing, the resulting roughness of the hole surface is R.sub.1 =1.6 micron.


SUMMARY OF THE INVENTION

The present invention is aimed at solving the problem of developing a reamer wherein the front angle of tooth would be such as to provide for a stable high quality of machining holes in various materials including plastic ones.
The problem is solved owing to the fact that in a reamer with teeth each having a cutting portion and a smoothing portion, with at least part of the rear surface of the latter smoothing portion being fashioned as a strip diverging in the direction away from a head portion of the reamer, and according to the present invention, each tooth has a front angle smoothly decreasing in the direction away from the head portion of the reamer.
Such a tooth design provides for relative ease of cutting in combination with a high smoothing effect on the surface of the hole being machined because the cutting portion of the tooth has an increased front angle .gamma. in combination with a positive back angle .alpha., owing to which the cutting process is considerably facilitated. As to the smoothing portion of the tooth, the back angle .alpha.=0 and the minimum values of the front angle .gamma. render said portion capable of the smoothing (calibrating) effect, which results in an improved quality of the hole being machined.
It is desirable that the value of reduction of the front angle of the tooth over the entire length thereof be at least 8.degree..
In case the front angle decreases by less than 8.degree., the reamer is inacapable of providing a high quality of holes being machined because of the lack of smoothing effect.


BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood upon considering the following detailed description of an exemplary embodiment thereof, with due reference to the accompanying drawings in which:
FIG. 1 is a general view of a four-groove reamer, according to the invention (side view, broken-off);
FIG. 2 is a tooth section taken in plane II--II passing through the cutting portion of the tooth;
FIG. 3 is a tooth section taken in plane III--III passing through the smoothing portion of the tooth;
FIG. 4 is a tooth section taken in plane IV--IV passing through the smoothing portion of the tooth; and
FIG. 5 is a tooth section taken in plane V--V passing through the smoothing portion of the tooth.


BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to FIG. 1 of the accompanying drawings the herein disclosed reamer comprises a working part 1 and a shank 2. Provided on the working part 1 of the reamer are teeth 3 which have a rear surface and a cutting portion 4 and a smoothing portion 5 adjacent one another.
The cutting portion 4 has a positive back angle .alpha. (FIG. 2). Rear or back angle .alpha. is an angle between the tangent to the rear surface of the blade taken through any cross-section, and a plane which is tangential to the cutting surface and which passes through the blade. It will be appreciated that the back angle .alpha. along the entire blade

REFERENCES:
patent: 2401307 (1946-06-01), Manewich
patent: 4091525 (1978-05-01), Karasiewicz et al.
patent: 4572714 (1986-02-01), Suzuki et al.

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