JPS6039018A - Reamer for finishing - Google Patents

Abstract

PURPOSE:To improve those of roundness, cylindricality, surface roughness and dimensional accuracy in a hole, by installing a broad front guide in a shunk tip while a pocket in a tip at the rear, respectively. CONSTITUTION:Both front and rear guides are made to be broad enough in size. A cutting edge 311 is formed at the front part of a tipe 31, having a negative rake angle alpha. This cutting edge 311 is tilted as far as a portion for an angle beta in relation to an axial center of a reamer. The rake angle alpha is set to a negative range whereby any damage to a work surface due to a bite of chips will not occur, and all chips are discharged outside along an oil groove. Likewise, with a back taper 312 being formed therein, roundness and cylindricality are all improved ever so better.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a finishing reamer, particularly for improving roundness, cylindricity,
This invention relates to a finishing reamer that can process holes with excellent surface roughness and dimensional accuracy.

(B) Prior Art Conventionally, in hole machining that requires a high degree of precision finishing, for example, hole machining for spool-type hydraulic valves, lapping or a honing machine with automatic sizing has had to be used. Although it is possible to process holes with excellent roundness, cylindricity, surface roughness, and dimensional accuracy using the overcutting method,
The former processing method requires a large amount of processing time and man-hours, while the latter method requires a large amount of equipment cost.

However, in recent years, finishing reamers that can be precisely processed have been proposed and implemented. For example, EVA is something called "Expansion Reamer J" which was developed in Switzerland. However, as a result of using this type of reamer, the surface roughness is 3s according to the JIS standard for a diameter of 14 mm.
Also, the roundness is about 4 μ, which is below the surface roughness of 18 or less and roundness of 1 / Z or less required for hole drilling of the spool type hydraulic valve, and even with this reamer, after processing, The actual situation is that it is necessary to use the lapping process or a honing machine with automatic sizing.

(C) Objective The object of the present invention is to provide a finishing reamer that can process holes with excellent roundness, cylindricity, surface roughness, dimensional accuracy, etc.

(D) Structure The present invention is a finishing reamer that is equipped with a wide front guide at the tip of the shank and a tip in the tip pocket at the rear thereof. The rear part of the tip is wide and forms a rear guide with a back taper of a predetermined length, and the front part of the tip is a finishing reamer provided with a cutting edge having a negative rake angle. .

(P) Embodiment FIG. 1 is a perspective view of the main parts of the finishing reamer according to the present invention, and FIGS. 1. A cross-sectional view of 1.

That is, 10 is S whose cross section is formed into a substantially bent cross shape.
A shank made of K steel, 11 is an oil groove carved into the shank, 20 is a front guide brazed to the tip of the oil groove, and 30 is a tip of the oil groove at the rear of the front guide 20. It is a chip that is brazed into a pocket, and the rear part of the chip serves as a rear guide.

Therefore, the surfaces of the front guide and the rear guide that contact the workpiece are slightly taller than the outer circumference of the shank 10, and the tip 30 is made of CBN mainly made of boron nitride or Compaq made mainly of some kind of artificial diamond. It is composed of a chip body 31 consisting of a base material, etc., and a cemented carbide metal 32.

Both the front guide and the rear guide are wide, and the rear guide has a slightly larger diameter than the front guide. That is, the diameter of the front guide is 13.995 (+O
, -0,01), the diameter of the rear guide is 14
．． 04 (10, -0,01).

Further, a cutting edge 311 is formed in the front part of the tip body 31, and when the rotation direction of this finishing reamer is in the direction of the arrow in FIG. It has a rake angle α of

In a preferred embodiment, the rake angle α is between 5 degrees and 30 degrees.
degree.

Furthermore, the cutting edge 311 is inclined at an angle β relative to the axial center of the finishing reamer, and in a preferred embodiment, this angle β is about 10 degrees.

Furthermore, a back taper 312 having a predetermined length of 0,005/100 to 2/100 is formed at the rear of the chip body 31.

When the finishing reamer configured as described above is inserted into a workpiece with a prepared hole while rotating in the direction of the arrow, the insertion direction of the finishing reamer is first stabilized by the front guide. Cutting is performed by the cutting blade, but by setting the rake angle to be negative, the chips are discharged along the oil groove without getting caught and roughening the surface, and the back taper mentioned above is added. The burnishing effect of the rear guide flattens the unevenness of the cut surface, further increases the directional stability of the finishing reamer, and improves the roundness and cylindricity of the machined hole.

Although this example has been explained using a linear reamer, the same applies to a helical reamer, and the tip is C.
It is not limited to BN, but may be Compax or carbide tips.

Further, the number of chips is not limited to four, and may be any number of chips.

(F) Effects As described above, the finishing reamer according to the present invention is capable of finishing holes with extremely high precision.

The surface roughness of the cut surface by conventional finishing reamers is JIS
The S symbol is 88 to los, and even the Swiss-made expansion reamer, which is considered the highest performance, has a second
As shown in the measurement results in Figure (A), the surface roughness of the cut surface by the reamer according to the present invention is approximately 38, as shown in Figure 2 (B).
As shown in Figure 2, we were able to obtain values below IS.

In addition, the roundness of the hole processed by the reamer according to the present invention is as shown in Figure 3 (A), although conventionally it was usually 5 microns or more as shown in Figure 3 (A). As shown in B), we were able to obtain measured values of 1 micron or less.

[Brief explanation of drawings]

Figure 1 is a perspective view of the main parts of the finishing reamer according to the present invention, Figure 2 is surface roughness comparison data between the conventional reamer and the reamer of the present invention, and Figure 3 is the comparison data between the conventional reamer and the reamer of the present invention. It is a figure showing the comparison data of roundness with the laminar of this invention. 10...Shank, 20...Front guide, 30...
・Chip, 311...cutting blade. Patent applicant Shimadzu Corporation Representative Patent attorney Takaharu Ohnishi

Claims (1)

[Claims] (1) A finishing reamer equipped with a wide front guide at the tip of the shank and a tip in the tip pocket at the rear thereof, the rear part of the tip having a slightly larger diameter and wider width than the front guide, and 1. A finishing reamer, characterized in that a rear guide is formed with a hack taper of a predetermined length, and the front part of the tip is provided with a cutting edge having a negative rake angle.