JPS598492B2 - High hardness sintered body reamer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention was developed to cut high-hardness steel materials, and its use has become common in recent years. A sintered body that can process copper alloys and copper alloys with high efficiency and is increasingly used, or a sintered body containing both high-pressure phase boron nitride and diamond, whose development is being considered. The present invention relates to a high-hardness sintered reamer in which one of the reamers is provided in the cutting blade portion.

Sintered bodies containing high-pressure phase boron nitride or diamond or both high-pressure phase boron nitride and diamond (hereinafter referred to as high-hardness sintered bodies) have high hardness and excellent cutting efficiency, but the transverse rupture strength is This is lower than traditional cutting tools such as cemented carbide and high-speed steel.

For example, the resistance of a sintered body containing waltzite-type boron nitride, which is high-pressure phase boron nitride 1, is 81.4 Ky/mm2, while that of WC-CO 10% cemented carbide is 343 Kf.
There is a report that it is /rIrIrL2.

In addition, the transverse rupture strength of a sintered body containing cubic boron nitride, which is another crystal form of high positive phase boron nitride, is 57 kcg/tr.
The transverse rupture strength of an 2 diamond sintered body is 110K
There is also a report of g/rran2.

Although there is no transverse rupture strength value for steel for cutting tools, it is generally said to have properties that are less likely to chip than cemented carbide.

The reamer is used to precisely finish the dimensions of a hole that has been previously drilled using a drill or the like, and to reduce the surface roughness of the inner surface of the hole.

Therefore, the diameter of the tip of the reamer is slightly smaller than the pre-processed hole diameter, and the finished diameter portion is a normal saw, with the finished diameter portion being slightly larger than the pre-processed hole diameter.

Therefore, when the reamer is inserted into a previously provided hole, the side surface near the tip of the reamer is intermittently connected to the inner surface of the hole.

Therefore, if the blade surface near the tip of the reamer is made of a high-hardness sintered material, there is a risk of the cutting edge breaking because the high-hardness sintered material is hard by nature but has low transverse rupture strength. .

In addition, the area near the tip of the reamer is generally called the chamfered part, but as mentioned earlier, the diameter is smaller than the pre-prepared hole diameter, so there is little need for actual cutting, but rather a true machining process. It can be considered as a guide part to the cutting edge part having a diameter.

Therefore, when choosing the material for that part, the focus should be on how difficult it is to be damaged by intermittent impacts, rather than its sharpness or durability when cutting highly hard materials.

Another consideration is the high cost of hard sintered bodies and the limited size available.

High-hardness sintered bodies are subject to economic and technical constraints, such as the use of expensive materials such as high-pressure phase boron nitride and diamond as raw materials, and the use of high temperatures and pressures in the sintering process. ing.

Therefore, it is economically advantageous to use a high-hardness sintered body that is as small as possible, and its maximum dimension is 30W.
A sintered body larger than that of In cannot be obtained at present.

Taking these circumstances into consideration, in the present invention, when the reamer is manufactured using a high-hardness sintered body, the part where the high-hardness sintered body is used is the cutting edge part with the true machining diameter and the small part in front of it. By fixing it in one part and making the other parts of cemented carbide or steel, it is possible to manufacture a framer that is effective in solving the problems of impact resistance, economy, and dimensional constraints of high-hardness sintered bodies. I found out what's possible.

The present invention will be explained below with reference to the drawings.

Figures 1a and 1b are front and side views showing an embodiment of a reamer with a straight cutting edge, and 1 is a high-hardness sintered body, with a high-hardness sintered body part 1a and a cemented carbide part 1b. It consists of two layers, and is brazed to the steel or cemented carbide part 5 at the part 1b.

2 and 2' are depressions provided in the steel or cemented carbide part 5 for brazing the high hardness sintered body 1.

3 is generally called a chamfered part, and is a part that comes into contact with a hole previously provided in the material to be machined before reaching the part having the final machining diameter, and contacts intermittently as described above.

Therefore, as is clear from the drawing, the high hardness sintered body 10
The part that touches the chamfer is a small part in front of the part C that moves from the chamfer to the part with the true machining diameter, that is, 10 mm from the corner part where the chamfer goes to the finishing part to the chamfer part side. limited within.

If it is slightly in front of the true machining diameter, all the blades will come into contact with the pre-prepared holes in the more forward part of the chamfered part, so the high hardness sintered body 1 will be cut intermittently. The possibility of chipping the cutting edge can be minimized due to the low transverse rupture strength.

Further, the portion that overlaps the finished portion is 2 rran or more from the corner portion to the finished portion side.

Reference numeral 4 is referred to as a guide portion, and since it is not substantially processed, steel or cemented carbide is sufficient, and there is no need to provide a high-hardness sintered body.

5 is a handle, which may be similar to a normal reamer.

The part C that moves from the chamfered part to the part with the true machining diameter is the corner where the straight line from the chamfered part and the straight line from the part with the true machining diameter intersect in the figure, but it is shown in Figure 2. like,
It may also be a curved line.

In the case of a curved part, if part C is made up of corners, stress will be concentrated on the corners during cutting, resulting in severe wear at that part, but the stress concentration will be reduced, resulting in less wear. .

Example 25 provided in SNCMg steel tempered to HRC45
．． Length 28rrv machined with O tranΔ drill
1a and 1b according to the invention.
Finished with a 5.4Ω reamer.

As a result, no damage was observed to the reamer even after machining 1000 holes.

Next, for comparison, we created a reamer with the same shape as the reamer shown in Figures 1a and 1b by extending 10 parts of the high-hardness sintered body to the tip of the chamfer, and performed the same processing. 12
After machining 8 pieces, a chipping occurred at a position of 1/3 from the tip of the 10-bit part of the high-hardness sintered body.

The high-hardness sintered body used for the reamer was made of 50% titanium carbonitride containing wurtzite boron nitride and cubic boron nitride in a ratio of 1:1, and titanium carbonitride with a carbon to nitrogen ratio. The mixture was sintered by mixing and sintering 50 parts by weight with an atomic weight ratio of 7:3.

As explained in detail above, the high hardness sintered compact reamer according to the present invention is economical and durable by using steel or cemented carbide for the parts that receive intermittent stress. It is suitable for processing high-hardness materials with excellent properties.

The present invention is also effective for reamers with twisted blades, broach reamers, etc. in addition to those with straight cutting blades.

[Brief explanation of drawings]

Figures 1a and 1b are a front view and a side view showing an embodiment of a high-hardness sintered reamer according to the present invention, and Figure 2 shows a curved section of C in Figure 1, and a high-hardness sintered body. This is a partial drawing. 1... High hardness sintered body, 1a... High hardness sintered body part, 1b... Cemented carbide part, 2 and 2
′...A recess provided in the steel or cemented carbide part in order to provide the high hardness sintered body 1, 3...A chamfered part, 4...
...Inner part, 5...Handle part, C...Corner part where the chamfer part moves to the guide part or the part having the true machining diameter.

Claims (1)

[Claims] 1. In a reamer whose cutting edge is equipped with a high-hardness sintered body containing high-pressure phase boron nitride or diamond or both high-pressure phase boron nitride and diamondogide, the high-pressure phase boron nitride or diamond or high-pressure phase boron nitride and diamond The cutting edge, which is made of a high-hardness sintered body containing both, is intermittently in contact with the workpiece material, from the corner part where the chamfering part moves to the finishing part, within 10 degrees on the chamfering part side, and at least 2 or more on the finishing part side. 1. A high-hardness sintered reamer, characterized in that the part of the reamer is provided so as to be in contact with the workpiece material K, and that a part extending from that part to the tip of the chamfered part is made of steel or cemented carbide.