JPH0112909Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a multi-stage gun reamer, which has been improved to provide high machining accuracy and long life, especially under high-speed cutting.

Conventionally, this type of gun reamer was
As seen in Japanese Patent No. 34784, the diameter of the machined hole is gradually increased and the desired diameter of the machined hole is finally obtained, so the range of its application is gradually expanding.

However, recently there has been a demand for high precision accompanying high-speed machining, and in order to meet this demand, polycrystalline materials such as diamond have been developed, as seen in, for example, Japanese Utility Model Application Publication No. 56-42819 and Japanese Patent Application Publication No. 56-95526. The use of sintered bodies is increasingly being proposed. However, there is still room for improvement in terms of the cutting edge configuration, etc.

The present invention was developed in view of the above points, and includes a carbide blade at one end of the pipe,
The outer periphery of this carbide blade body is provided with flute grooves and guide pads extending in the axial direction, and is a multi-stage gun reamer configured so that the diameter of the cutting edge increases in steps so that the machining diameter can be increased sequentially. The intention is to further improve this to achieve high machining accuracy and long life.

An embodiment of the gun reamer of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, 1 is a pipe having a refueling hole, and a carbide blade 2 is attached to one end of the pipe.
is attached, and a handle portion (not shown) is attached to the other end.

The carbide blade body 2 has flute grooves 3 and guide pads 4 extending in the axial direction formed on its outer circumferential portion, and the diameter of the cutting edge increases in steps so that the machining diameter can be increased sequentially. . This constitutes a so-called multi-stage gun reamer.

In each of the flute grooves 3, a chip seat 6 is recessed, for example, by electrical discharge machining, so that the composite chip 5 can be received. This composite chip 5 is composed of a support piece 7 and a cutting edge layer 8, and has a so-called two-layer structure. In this case, the support piece 7 is made of cemented carbide, and the cutting edge layer 8 is made of a polycrystalline sintered body of diamond, cubic boron nitride, or the like. Further, the two-layer structure can be obtained by sintering and fixing under ultra-high pressure and high temperature using an ultra-high pressure generating device found in belt devices and the like.

Furthermore, the cutting edge structure obtained by the composite chip 5 has a rounded margin 9 on the outer periphery, as well as an inclined cutting edge 10a and a vertical cutting edge 10b to cope with the cutting allowance of the machined hole diameter. It is formed.

In this embodiment, the inclined cutting edge 10a is formed on the first and second composite chips 5, and the vertical cutting edge 10b is formed on the third and fourth composite chips 5. It's summery. especially,
The reason for providing the cutting edge 10a that slopes up to the second angle is to ensure stability when machining deep holes.

In the gun reamer of the present invention constructed in this way, the hole diameter is enlarged by each composite tip 5, and the gun reamer 9 and guide pad 4 perform a burnishing action.
In order to equalize the amount of wear caused by this burnishing effect, the width A of the margin 9 formed on the composite chip 5 is smaller than the width B of the guide pad 4, as shown in FIG. Thereby, the burnishing action is performed in a well-balanced manner by the supply of cutting oil from the injection hole 11, and high machining accuracy is guaranteed.

In this embodiment, the width B of the guide pad 4 is approximately 1.5 to 2.0 times the width A of the margin 9.

Next, an example of cutting using the gun reamer of the present invention for finishing aluminum die casting will be explained.

The tool specifications are a two-flute, four-stage type as shown in Figure 1, and the nominal diameter of each cutting edge is
The composite chip 5 has an axial length of 4 mm and a margin width of A.
was set to 0.7mm. . Furthermore, the guide pad width B was set to 1.0 mm.

The cutting conditions are rotation speed N = 3000 rpm, feed f =
Reaming was performed at a rate of 0.1 mm/rev for pilot holes in the plates that were spaced apart in a parallel relationship.

As a result, the product of the present invention showed roundness as shown in Figure 4 after 3000 holes. In addition, the roundness in this case is at the middle part of the machined hole in the second stage, and the machined hole circle D is shown with respect to the perfect circle C.

On the other hand, margin width A, guide pad width B
When a comparative test was conducted under the same conditions with each hole being equal to 1.0 mm, the roundness (perfect circle C, machined hole circle D) as shown in Fig. 5 was obtained for 3000 holes, and the inventive product It was confirmed that the roundness was excellent. This is guide pad 4
and the wear of the margin 9 is different, and the roundness is lost accordingly.

In addition, the flute groove 3 is one groove with an opening of about 90 degrees,
A similar reaming process was performed on a so-called single-blade type gun reamer with a bearing surf ace on the opposite side of the flute groove 3, and the above-mentioned tendency was observed.

As explained above, the present invention enables high-speed cutting by attaching a composite chip with a cutting edge layer made of polycrystalline sintered material such as diamond to the biting part of the carbide blade, and Since the margin width formed on the composite chip is made smaller than the width B of the guide pad so that the burnishing action can be performed in a well-balanced manner, it has the advantage that high processing accuracy and long life can be expected.

[Brief explanation of the drawing]

Figure 1 is a partial front view of the gun reamer of the present invention, Figure 2 is an end view thereof, Figure 3 is an enlarged partial end view of Figure 2, and Figure 4 is a reamed gun reamer of the present invention. FIG. 5 is an explanatory diagram showing the roundness at the 3000th hole point, and FIG. 5 is an explanatory diagram showing the roundness at the 3000th hole point when reamed with a comparative product. 1... Pipe, 2... Carbide blade body, 3... Flute groove, 4... Guide pat, 5... Composite tip,
7... Support piece, 8... Cutting edge layer, 9... Margin,
10a... Inclined cutting edge ridge, 10b... Vertical cutting edge ridge.

Claims (1)

[Claims for Utility Model Registration] One end of the pipe 1 is provided with a carbide blade body 2, and the outer peripheral portion of this carbide blade body 2 is provided with a flute groove 3 and a guide pad 4 extending in the axial direction. This flute groove 3
The biting part of the cutting edge is equipped with a composite chip 5 in which a cutting edge layer 8 made of a polycrystalline sintered body of diamond, cubic boron nitride, etc. is fixed to a support piece 7 of cemented carbide. In a multi-stage gun reamer configured so that the diameter of the cutting edge increases stepwise, the composite chips 5 are arranged in the order of decreasing diameter of the cutting edge.
Regarding the second and second ones, the inclined cutting edge 10a at least copes with the cutting allowance of the machined hole.
Moreover, a margin 9 formed by the outer edge of the cutting edge layer 8 is located concentrically with respect to the guide pad 4, and has a margin width A.
is formed smaller than the guide pad width B.