JPH0788711A - Aluminum cylinder block bore boring method - Google Patents

Abstract

PURPOSE:To obtain the core surface excellent in wear resistance with uncrushed primary crystal silicon existing by making the crushing depth of primary crystal silicon small at the time of performing bore boring to an aluminum cylinder block, and eliminating the crushed layer of the primary crystal silicon at the time of honing in the following process. CONSTITUTION:At the time of performing bore boring at the bore part 2 of an aluminum cylinder block 1 using a cutting tool 3, bore boring is performed under the machining conditions that the average grain diameter of diamond grain of a diamond sintered body forming the cutting edge 3a of the cutting tool 3 is 30mum or more, the rake angle of the cutting edge 3a is 5-10 deg., the clearance angle us 10-15 deg., and the cutting speed is 400-600m/min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bore boring method for an aluminum cylinder block which is used for cutting the inner surface of a cylinder bore portion of a reciprocating engine.

[0002]

2. Description of the Related Art A cylinder block of a reciprocating engine has been used for a long time because it is made of cast iron. For passenger cars and gasoline engines for commercial vehicles, it is made of cast iron blocks with an integrated bore. The mainstream products are cast iron blocks with separate liners.

On the other hand, since cast iron has a large specific gravity, it increases the weight of the cylinder block, that is, the weight of the engine, which violates the requirements for weight reduction and fuel efficiency of automobiles. Therefore, the aluminum cylinder block should be used. Has already been put to practical use (for example, “Automotive Technology Handbook <Second Volume> Design Edition” published on March 1, 1991, 1st edition, Issuer, Japan Society of Automotive Engineers, pages 49 to 52).

In the case of an aluminum cylinder block, a cast iron liner is fitted in the bore portion to improve wear resistance, and a high silicon aluminum alloy containing a large amount of Si is used to form a primary crystal. A technique has also been developed in which silicon is used to improve the wear resistance of the bore.

In the bore portion of such a high silicon aluminum cylinder block, in order to secure the wear resistance of the surface, it is necessary that the primary crystal silicon exists on the surface in a non-crushed state.

When performing bore boring on a cast aluminum cylinder block, diamond particles having excellent wear resistance are formed in the bore portion 2 of the aluminum cylinder block 1 as shown in FIGS. 5 and 6, for example. Blade edge of diamond sintered body with a small average particle size
The cutting tool 3 designated as a was used.

[0007]

However, with the conventionally used tool materials and tool shapes, not only the machined surface of the bore portion but also the primary crystal silicon of the deep portion may be crushed. There are points, tool shape, tool material, which minimizes the crushing depth of primary crystal silicon,
No processing conditions have been found.

That is, during bore boring processing under the conventional processing conditions using such a cutting tool, the processing surface layer portion is elastically deformed by the cutting force. At this elastic deformation, as shown in FIG. It was easy for the primary crystal silicon 5 scattered in the aluminum matrix 4 of the cylinder block 1 to be crushed.
In FIG. 7, 5 (5a) represents crushed primary crystal silicon, and 5 (5b) represents uncrushed primary crystal silicon. ).

When the crushed layer is deep, as shown in FIG.
In the honing process for finishing the boring depth D _B to the honing depth D _{H shown in} (4), the crushed primary crystal silicon 5 (5
Since the surface layer portion where a) exists cannot be removed completely, the crushed primary crystal silicon 5 (5a) still exists on the surface, resulting in a surface having poor wear resistance.

Therefore, it has been a problem to find a tool material, a tool shape, and processing conditions that minimize the crushing depth of primary crystal silicon.

[0011]

SUMMARY OF THE INVENTION The present invention has been conceived in view of the above-mentioned conventional problems, in which the crushing depth of primary crystal silicon is made small during bore boring of an aluminum cylinder block, and honing in the next step is carried out. In order to provide a bore boring method for an aluminum cylinder block, it is possible to remove the crushed layer of primary crystal silicon and obtain a bore surface excellent in wear resistance in which uncrushed primary silicon exists. Has an aim.

[0012]

SUMMARY OF THE INVENTION A bore boring method for an aluminum cylinder block according to the present invention is a diamond sintering forming a cutting edge of the cutting tool when the boring boring of the aluminum cylinder block is performed by using the cutting tool. The average particle diameter of the diamond particles of the body is 30 μm or more, the rake angle of the cutting edge is 5 to 10 °, the clearance angle is 10 to 15 °, and the cutting speed is 400 to 600 m.
In the embodiment of the bore boring method for the aluminum cylinder block according to the present invention, the feed rate is 0.1 to 0.4 mm /. The bore boring process may be performed under the rev machining condition, or the bore boring process may be performed under the nose R of 0.2 to 0.8.

In the bore boring method for an aluminum cylinder block according to the present invention, the average particle diameter of the diamond particles of the diamond sintered body constituting the cutting edge of the cutting tool is set to 30 μm or more. If the grain size is small, it is difficult to form sharp edges on the cutting edge when diamond particles are broken when cutting primary silicon, and the cutting resistance increases, so primary silicon scattered in the aluminum matrix. If the honing process is performed after the boring process by increasing the crushing depth of, the primary silicon that has been crushed by the boring process cannot be removed, and a wear-resistant bore surface can be obtained. This is because it becomes difficult to create.

The reason why the rake angle of the cutting edge is 5 to 10 ° is that the crushing depth of the primary crystal silicon increases as the rake angle of the cutting edge becomes smaller than 5 °, and the rake angle is increased. It is necessary to reduce cutting resistance,
If the rake angle is too large, the crushing depth of primary crystal silicon also increases, so it is desirable to set it to 10 ° or less.

Further, the clearance angle is set to 10 to 15 ° because if the clearance angle is too small, the crushing depth of the primary crystal silicon becomes large, and if the clearance angle is too large, the crushing depth of the primary crystal silicon becomes large. This is because

Further, the cutting speed is 400 to 600 m / m.
The reason for setting to in is that if the cutting speed is too slow, the crushing depth of the primary crystal silicon increases, and if the cutting speed increases, the tool wear increases and the crushing depth of the primary crystal silicon increases. The crushing depth of primary crystal silicon is stable at 400 to 600 m / min without being affected by tool wear.
Is.

In addition, the feed rate is 0.1 to 0.4 mm
/ Rev and the nose R is preferably 0.2 to 0.8.

[0018]

The bore boring method for an aluminum cylinder block according to the present invention has the above-mentioned structure, so that the depth of the primary crystal crushed layer due to the bore boring processing is suppressed to 50 μm or less. Since the crushed layer of primary crystal silicon becomes shallow, the crushed layer of primary crystal silicon will be removed in a short time during the subsequent honing process, and the crushed surface of the bore after the honing process will be crushed. The primary crystal silicon in a state where it has not been present is present, and it becomes possible to finish the bore with excellent wear resistance on the surface, and it becomes an aluminum cylinder block that is lightweight and has good wear resistance.

[0019]

Example An aluminum cylinder block was cast-molded using a high-silicon aluminum alloy having a silicon content of 17.0% by weight.

Then, bore boring is performed on the surface of the bore portion 2 of the aluminum cylinder block 1 in the manner shown in FIGS. 5 and 6, and the cutting edge 3a of the cutting tool 3 is formed at the time of bore boring. The average particle size of the diamond particles of the diamond sintered body is 30 to
As a tool changed in the range of 50 μm, D
X180 (Toshiba Tungaloy Co., Ltd. diamond sintered body; average particle size of diamond particles: 35 μm) and DA90 (Sumitomo Electric Industrial Co., Ltd. diamond sintered body; average particle size of diamond particle: 50 μm) were used, and DX180 and DA90 were used. In the case of a cutting tool using, the rake angle of the cutting edge 3a is changed in the range of 0 to 10 °, the clearance angle is changed in the range of 6 to 15 °, and the cutting tool is DA90 (new). , DA1
50 (new article; Sumitomo Electric Industries, Ltd. diamond sintered body; average particle diameter of diamond particles 5 μm), DA9
0 initial wear product, DA150 initial wear product and D × 1
When the initial wear product is 80, the cutting speed is 400
Cutting processing was performed while changing the range of up to 800 m / min.

As a result, as shown in FIG. 1, the cutting tool 3
By setting the average particle diameter of the diamond particles of the diamond sintered body constituting the cutting edge 3a of
It was confirmed that the crushing depth of primary crystal silicon can be stably made smaller.

In the conventional case, as shown in FIG. 8 (b), the average particle size of the diamond particles of the diamond sintered body is small, so that a sharp edge is secured at the cutting edge 3a. On the other hand, when the average particle size of the diamond particles is as large as 30 μm or more, as shown in FIG. 8 (a), the diamond particles are damaged when the primary crystal silicon is cut. Even if the new cutting edge 3a appears later, the sharp edge of the cutting edge 3a is secured and the cutting resistance becomes small, and the cutting force is not transmitted from the surface to a deeper position and the primary crystal silicon is By being cut clean,
It was found that the crushing depth of primary crystal silicon can be made small.

Further, as shown in FIG. 2, the rake angle of the cutting edge 3a is set to 5 to 10 °, and the cutting resistance is reduced by increasing the rake angle in this way, thereby cutting the primary crystal silicon. It was found that the crushing depth of primary crystal silicon can be made small without the cutting force being transmitted deeper to the inside.

Further, as shown in FIG. 3, the clearance angle is set to 10
It was confirmed that the crushing depth of the primary crystal silicon can be made small by setting the angle to -15 °.

Further, as shown in FIG. 4, when the cutting tool wears at a high cutting speed, the crushing depth of the primary crystal silicon increases and the crushing of the primary crystal silicon is not affected by the tool wear. It was recognized that the depth can be stabilized when the cutting speed is 400 to 600 m / min.

[0026]

EFFECTS OF THE INVENTION Since the bore boring method for an aluminum cylinder block according to the present invention has the above-mentioned structure, it is possible to suppress the depth of the primary crystal crushed layer by the bore boring processing to 50 μm or less. ,
Since it is possible to make the crushed layer of primary crystal silicon shallower, the crushed layer of primary crystal silicon can be removed in a shorter time during the subsequent honing process, and the bore surface after the honing process can be removed. Since it is possible to assume that primary crystal silicon in the uncrushed state was present in the aluminum, it is possible to finish the bore with excellent wear resistance of the surface, lightweight aluminum with good wear resistance. The great effect is that it is possible to provide a cylinder block.

[Brief description of drawings]

FIG. 1 is a graph showing the results of examining the influence of the average particle size of diamond particles on the crushing depth of primary crystal silicon in the example of the present invention.

FIG. 2 is a graph showing the results of examining the influence of the rake angle of the cutting edge on the crushing depth of primary crystal silicon in the example of the present invention.

FIG. 3 is a graph showing the results of examining the influence of the clearance angle on the crushing depth of primary crystal silicon in the example of the present invention.

FIG. 4 is a graph showing the results of examining the influence of the cutting speed on the fracture depth of primary crystal silicon in the example of the present invention.

FIG. 5 is a horizontal cross-sectional explanatory view showing a procedure for performing bore boring processing on the bore portion of the aluminum cylinder block.

FIG. 6 is a vertical cross-sectional explanatory view showing a procedure for performing bore boring processing on the bore portion of the aluminum cylinder block.

FIG. 7 is an explanatory diagram showing that the primary crystal silicon 5 (5a) crushed by the bore boring process of the depth D _B reaches the depth D _H of the subsequent bore honing process.

FIG. 8 is a cutting edge using a diamond sintered body having a large average particle diameter of diamond particles according to the present invention ((a) of FIG. 8).
FIG. 9 is an explanatory diagram showing a cutting edge ((b) of FIG. 8) using a diamond sintered body having a small average particle diameter of diamond particles according to a conventional example.

[Explanation of symbols]

 1 Aluminum Cylinder Block 2 Bore Part 3 Cutting Tool 3a Cutting Tool Edge 4 Aluminum Matrix 5 Primary Silicon 5 (5a) Crushed Primary Silicon 5 (5b) Uncrushed Primary Silicon

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kanda 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Yuhisa Masubuchi Kanagawa Ward, Yokohama City, Kanagawa Prefecture 2 Takaramachi Nissan Motor Co., Ltd.

Claims (3)

[Claims] 1. When performing bore boring of an aluminum cylinder block using a cutting tool, the average particle diameter of the diamond particles of the diamond sintered body forming the cutting edge of the cutting tool is set to 30 μm or more, and the cutting edge of the cutting edge is cut. A bore boring method for an aluminum cylinder block, which is characterized in that the bore boring is performed under processing conditions of an angle of 5 to 10 °, a clearance angle of 10 to 15 °, and a cutting speed of 400 to 600 m / min. 2. The feed rate is 0.1 to 0.4 mm / rev.
The bore boring method for an aluminum cylinder block according to claim 1, wherein the bore boring processing is performed under the processing conditions described above. 3. The bore boring method for an aluminum cylinder block according to claim 1, wherein the boring is carried out under a working condition with a nose R of 0.2 to 0.8.