JP2000233271A - Manufacture of cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time for grinding an inner diameter and to reduce a manufacturing cost by integrally fitting a cylinder liner into a cylinder block with an engagement and reducing a finish machining allowance in the inner diameter (bore) to easily execute the finish machining. SOLUTION: This manufacturing method comprises a process for producing an aluminum base composite billet 35 by charging an alumina 21, aluminum alloy 31 and magnesium 32 or magnesium generating source in a furnace, reducing the alumina with magnesium nitride 34 and impregnating the alumina with the molten aluminum alloy, an extruding process for forming the billet into a cylinder with an extrusion press, a drawing process for finishing the cylinder after extruding with a drawing device, a machining process for forming a cylinder liner of the aluminum base composite material by machining the cylinder after drawing and an engaging process for engaging the cylinder liner into the cylinder block.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a cylinder block using an aluminum-based composite material.

[0002]

2. Description of the Related Art A method of manufacturing a cylinder block using an aluminum-based composite material is disclosed in, for example, Japanese Patent Application Laid-Open No.
No. 154, "Method of Manufacturing Cylinder". The method of manufacturing this cylinder is as shown in the lower left column, page 8, lines 17 of page 2 of the publication. These are summarized below. (A) A chip of SiC is stirred and dispersed in a molten aluminum and solidified. (B) The solidified product is drawn while being heated to about 250 ° C. to form a pipe. (C) After the pipe is cut into a sleeve and fitted into a die casting mold, an aluminum alloy (AD
The cylinder is manufactured by casting in C12).

[0003]

The above-mentioned sleeve-shaped material is a composite material in which a SiC chip is compounded in a molten aluminum, and has a high resistance to plastic deformation, and
The interface between aluminum and SiC is only in a mechanically bonded state, and therefore has low elongation and poor workability like a general composite material. As a result, it is difficult to form the pipe by the method of drawing or extruding to form the pipe, and it is difficult to improve the quality of the pipe and increase the production efficiency. In addition, when being cast with an aluminum alloy, the sleeve-shaped material is subjected to shrinkage strain, so it is necessary to provide a large allowance for the sleeve-shaped inner surface. It takes time to finish the process of ()). Further, there is a concern that a casting defect may occur at a joint between the cast aluminum alloy (ADC12) and the outer surface of the sleeve.

Accordingly, an object of the present invention is to provide a method of manufacturing a high-quality cylinder block with high production efficiency.

[0005]

Means for Solving the Problems To achieve the above object, a first aspect of the present invention is to place an aluminum alloy and magnesium or a magnesium source in a furnace together with a porous formed body made of an oxide-based ceramic. The process of reducing oxide-based ceramics by the action of aluminum and infiltrating the molten aluminum alloy into the porosity of the oxide-based ceramics to produce an aluminum-based composite billet, and extruding the aluminum-based composite billet into a cylinder by pressing and pressing Extrusion process, a drawing process of finishing the extruded tube with a drawing device to give accuracy to the inner and outer diameters, and a cutting process of cutting the drawn tube to a predetermined length to form a cylinder liner of an aluminum-based composite material. And a fitting step of fitting the cylinder liner to the cylinder block.

[0006] By reducing the oxide ceramics, the porous surface is metallized to improve the wettability between the oxide ceramics and the molten aluminum alloy. In the aluminum matrix composite thus obtained, the interface between the aluminum and the reinforcing material is firmly bonded by chemical contact,
It is an aluminum-based composite material having excellent moldability, and can be easily extruded and drawn in a later step, can increase an extrusion ratio, and can be deformed by a high extrusion ratio. As a result, internal defects can be removed and densification can be achieved, and quality can be improved. In the drawing step, the finishing accuracy of the inner and outer diameters of the cylinder is improved. When the cylinder liner is assembled to the cylinder block by fitting, the inner diameter (bore) can be easily finished because the change in inner diameter after fitting is small.

A second aspect of the present invention is to set the extrusion ratio in the extrusion step to 10 to 50 when a value obtained by dividing the sectional area of the billet before extrusion by the sectional area of the cylinder after extrusion is used as the extrusion ratio. Features. If the extrusion ratio is less than 10, sufficient tensile strength and proof stress cannot be imparted to the obtained cylinder. When the extrusion ratio is large, a relatively large number of products can be formed by one extrusion, so that the productivity is improved, and it is desirable that the extrusion ratio is large. However, when the extrusion ratio exceeds 50, the extrusion force increases, the equipment becomes large-scale, and the equipment cost increases. As a result, the lower limit is set to 10 from the viewpoint of the mechanical properties of the aluminum-based composite material, and the upper limit is set to 50 from the viewpoint of the equipment capacity (extrusion press output).

According to a third aspect of the present invention, the fitting step is shrink fit. Since it is a shrink fit in which the cylinder block side is heated and a cylinder liner at room temperature is fitted, a uniform tightening force is applied to the outer surface at room temperature, and the inside diameter (bore) changes are minute, so that the finishing is easier.

According to a fourth aspect of the present invention, the fitting step is a cold fit. Cool the cylinder liner side and fit it into the room temperature cylinder block. Since the cylinder liner is a small part, the equipment for cooling the cylinder liner is small,
And it can be made simple.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a schematic structural view of an apparatus for manufacturing an aluminum-based composite material according to the present invention. The apparatus for manufacturing an aluminum-based composite material 1 includes an atmosphere furnace 2, a heating device 3 attached to the atmosphere furnace 2, and an atmosphere furnace 2. Supply device 6 for supplying an inert gas to the furnace, and a vacuum pump 7 for reducing the pressure in the atmosphere furnace 2
Consists of 8 and 9 are crucibles (crucibles). Specifically, the heating device 3 includes, for example, a control device 11, a temperature sensor 12, and a heating coil 13;
Are a cylinder 15 of argon gas (Ar) 14, a cylinder 17 of nitrogen gas (N ₂ ) 16,
A pipe 18 for supplying the gas of 17 to the atmosphere furnace 2;
8 is provided with a pressure gauge 19.

The crucible 8 is a container for holding porous alumina (Al ₂ O ₃ ) 21 and an aluminum alloy 31 which are oxide ceramics, and the crucible 9 is a container for holding magnesium (Mg) 32. Aluminum alloy 3
1 is, for example, A6061. Magnesium (Mg)
32 may be a magnesium alloy.

FIGS. 2 (a) to 2 (d) are diagrams showing the procedure for producing the aluminum-based composite billet according to the present invention.
(C) schematically shows the process up to penetration. (A): First, an aluminum alloy 31 and magnesium (Mg) 32 are placed in a furnace together with alumina (Al ₂ O ₃ ) 21 which is an oxide ceramic. Specifically, alumina 21 is placed in crucible 8, aluminum alloy 31 is placed on alumina 21, and magnesium 32 is placed in crucible 9.

Next, the inside of the atmosphere furnace 2 is evacuated to remove oxygen in the atmosphere furnace 2, and when a certain degree of vacuum is reached, the vacuum pump 7 is stopped, and argon gas (Ar) 14 is supplied to the atmosphere furnace 2. Is supplied as shown by the arrow, and the porous alumina 21 and the aluminum alloy 3 are supplied by the heating coil 13 as shown by the arrow.
Heating of 1 and magnesium 32 is started.

The temperature in the atmosphere furnace 2 is raised (automatically) while being detected by the temperature sensor 12. A predetermined temperature (for example, about 75
In the process of reaching 0 ° C. to about 900 ° C.), the aluminum alloy 31 melts. At the same time, the magnesium (Mg) 32 evaporates as shown by the arrow. At this time, since the atmosphere furnace 2 is under the atmosphere of the argon gas (Ar) 14, the aluminum alloy 31 and the magnesium (Mg) 32 are not oxidized.

(B): Next, the inside of the atmosphere furnace 2 is pressurized, and the alumina (Al ₂ O ₃ )
To reduce the aluminum alloy 3
Aluminum-based composite billet 3
5 is manufactured. Specifically, nitrogen gas (N
₂ ) Pressurizing (for example, atmospheric pressure + about 0.5 kg / cm ² ) while supplying 16 as shown by the arrow, and replace the atmosphere in the atmosphere furnace 2 with nitrogen gas (N ₂ ) 16.

When the atmosphere in the atmosphere furnace 2 becomes an atmosphere of nitrogen gas (N ₂ ) 16, the nitrogen gas 16 becomes magnesium (Mg).
Reacts with magnesium to produce magnesium nitride (Mg ₃ N ₂ ) 34. This magnesium nitride 34 is made of alumina (Al ₂
Since O ₃ ) 21 is reduced, the alumina 21 has good wettability. As a result, the molten metal of the aluminum alloy 31 permeates into the porosity of the alumina 21. The aluminum alloy 31 solidifies to complete the aluminum-based composite billet 35. In the infiltration process, if the atmosphere furnace 2 is placed in a pressurized atmosphere, the infiltration is accelerated, and the aluminum-based composite billet 35 can be manufactured in a short time. The pressure in the atmosphere furnace 2 is reduced by the vacuum pump 7 so that the atmosphere can be permeated in a short time even under a reduced-pressure nitrogen atmosphere.

(C): Aluminum-based composite billet 3
5 (hereinafter abbreviated as “billet 35”) is made of alumina 21 which is an oxide ceramic and aluminum alloy 3
1 is a composite material having excellent moldability and easy plastic deformation. (D): Finally, the billet 35 is cut to a predetermined size by an NC (numerical control) lathe 36. The dimensions are adapted to the extrusion press in the next step.

FIG. 3 is an explanatory view of the extrusion process according to the present invention.
1 and extruded with a ram 42 to form a die 43
And is formed into a tube 45 through the space between the mandrel 44. The cross-sectional area of the billet 35 before extrusion is A0, and the cross-sectional area of the cylinder 45 after extrusion is A1.

Since the billet 35 is a composite material in which the interface between aluminum and the reinforcing material is firmly bonded by chemical contacts, the billet 35 has good moldability, and as a result, the cylinder 45 can be easily extruded. In addition, by applying deformation at a high extrusion ratio, internal defects can be removed and densification can be achieved, and quality can be improved.

Here, the extrusion ratio R is defined as R = A0 / A1. That is, the extrusion ratio R is the billet 3 before extrusion.
This is a value obtained by dividing the cross-sectional area A0 of No. 5 by the cross-sectional area A1 of the cylinder 45 after extrusion.

FIG. 4 shows the extrusion ratio and tensile strength according to the present invention.
It is the graph which showed the relationship of proof stress, and the horizontal axis set extrusion ratio R and the vertical axis set tensile strength (sigma) _B and proof stress (sigma) _0.2 . Note that σ _0.2 is an abbreviation for 0.2% proof stress. When the extrusion ratio R is less than 10, the tensile strength σ _B is proportional to the extrusion ratio R. Therefore, the tensile strength σ _B can be increased by the extrusion ratio R. Similarly, the proof stress σ _0.2 can be increased. When the extrusion ratio R is 10 or more, the increase in the tensile strength σ _{B with} respect to the increase in the extrusion ratio R is extremely small, and becomes almost constant. Similarly, the proof stress σ _0.2 is almost constant.
If the extrusion ratio is large, the productivity is improved, so that the extrusion ratio is preferably large. However, when the extrusion ratio exceeds 50,
Extrusion force increases and large equipment is required. As a result, the lower limit was set to 10 from the viewpoint of the mechanical properties of the aluminum-based composite material, and the facility capacity (extrusion press output)
The upper limit is set to 50 from the viewpoint of.

FIG. 5 is an explanatory view of the drawing step according to the present invention. The extruded tube 45 is set in a drawing device 50,
The die 52 and the plug 5 are pulled by the gripper 51.
Throughout the interval between 3, the tube 56 is formed (cold).

The cylinder 56 has an inner diameter D1, an outer diameter D2, and a thickness t. These dimensions are within a predetermined tolerance range, and at the same time, have predetermined roundness and surface roughness. .
Since the aluminum-based composite material of the present invention is easily plastically deformed, a desired accuracy can be imparted to the inner and outer diameters D1 and D2 by one drawing.

FIG. 6 is a graph of an example comparing the processing accuracy of only extrusion and the processing accuracy after drawing according to the present invention.
The horizontal axis represents the inner diameter, and the vertical axis represents the tolerance. For example, the processing accuracy after drawing of an inner diameter of 50 mm is within a tolerance of ± 0.
The machining accuracy is within the range of 02 mm and the inner diameter of 80 mm is within the tolerance of ± 0.03 mm. The accuracy of the inner diameter can be greatly increased in the cold drawing process. The outer diameter has the same tolerance. From this fact, it can be seen that, compared to the case where the cylinder is formed only by the extrusion, the finishing method according to the present invention in which the extrusion is performed and the drawing is performed can improve the finishing accuracy by about 10 times.

FIG. 7 is an explanatory view of the tube cutting step according to the present invention. The drawn cylinder 56 is cut into a predetermined length L1 to form a cylinder liner 57 of an aluminum-based composite material.
The length L1 is fixed, and the end face 5 of the cylinder liner 57 is
8, 58 are cut by the cutter 59 and finished at the same time.

FIG. 8 is an explanatory view of the fitting step (first embodiment) of the cylinder liner according to the present invention. Cylinder liner 5
(... denotes a plurality; the same applies hereinafter) are fitted to the cylinder block 60. Specifically, the cylinder block 6
0 has a cylinder portion 61..., A jacket portion 62, and a lower crankcase portion 63. Cylinder part 61
.. Are separate bodies into which the cylinder liners 57 are fitted, and the holes 65.
Finish to the specified inner diameter with a processing machine. Next, holes 65 ...
Are fitted (in the direction of the arrow).

The inner diameter of the hole 65 is slightly smaller than the outer diameter of the cylinder liner 57.
7 are integrally attached to the cylinder part 61 by fitting. The circularity of the cylinder liner 57 after being pulled out is good, and the outer surface of the cylinder liner 57 and the cylinder portion 61 are in close contact with each other, and there is no fear that a gap is formed.

FIG. 9 is an explanatory view of a cylinder finishing process according to the present invention, in which the inner surfaces of the cylinder liners 57 are finished by a honing machine 70. Specifically, first, the cylinder block 60 is connected to the honing machine 7 based on the cylinder portion 61.
Set to 0. Next, the whetstone 71 of the honing machine 70
Is rotated while being moved up and down as indicated by arrows, and the allowance for the cylinder liner 57 is ground. Thus, a cylinder having a predetermined dimension (bore) is completed.

FIG. 10 is an enlarged view of a main part of the cylinder liner according to the present invention. The inner diameter of the cylinder liner 57 after fitting to the cylinder block 60 is D3 (the inner diameter D1 (see FIG. 7) is slightly reduced), and the finished inner diameter (bore) is D3.
4. The allowance at that time is T. Since the cylinder liner 57 has high accuracy of the inner and outer diameters and the fitting is performed, the inner diameter does not become distorted after the assembling, and there is no fear that the inner diameter becomes too large (the inner diameter D4 + α).
Can be made extremely small. As a result, the processing time for grinding the allowance T is reduced, and the production efficiency is improved.

Next, another embodiment of the fitting process of the cylinder liner will be described. FIG. 11 is an explanatory diagram of a cylinder liner fitting process (second embodiment) according to the present invention. The machined cylinder block 60 is placed in a heating device and heated to a predetermined temperature as indicated by the arrow. When heated under desired conditions, the hole 65 changes from the inner diameter D5 to the inner diameter D6 due to expansion (the amount of deformation H1), and a gap S1 is formed between the inner diameter D6 and the outer diameter D2. Can be easily assembled. Also, in the assembly by shrink fitting, the tightening force can be made relatively large, so that the cylinder liner 57 itself does not move.

FIG. 12 is an explanatory view of a cylinder liner fitting process (third embodiment) according to the present invention. The cylinder liner 57 is put into the refrigerating apparatus and cooled to a predetermined temperature as shown by the arrow. When cooled under desired conditions, the cylinder liner 57 contracts (deformation amount H2) to change from the outer diameter D2 to the outer diameter D7, and a gap S2 is formed between the outer diameter D7 and the inner diameter D8 of the hole 65. The cylinder liner 57 can be easily assembled to the portion 61. Further, in the assembly by cold fitting, the cylinder liner 57, which is a small component, is cooled, so that the size of the equipment (refrigeration apparatus) can be reduced and simplified.

FIG. 2 shows an embodiment of the present invention.
In the production of magnesium nitride (Mg ₃ N ₂ ) 34 in (b), magnesium was put in a crucible, but this is only an example and the present invention is not limited to this. For example, the porous molded body may contain magnesium (Mg) in advance to generate magnesium nitride.
Although the cylinder block 60 in FIG. 8 is a cylinder block of an in-line four-cylinder engine, the number of cylinders and the cylinder arrangement are not limited to this. For example, the cylinder block may be a single cylinder, a V-type 8-cylinder cylinder, or a horizontally opposed piston type cylinder block. In the fitting steps shown in FIGS. 11 and 12, depending on conditions, it is necessary to further reduce the tolerance range of the outer diameter of the cylinder liner, and the drawing is not limited to one time.

[0033]

According to the present invention, the following effects are exhibited by the above configuration. In the first aspect, the oxide ceramics is reduced by the action of magnesium nitride. When alumina (Al ₂ O ₃ ), which is an oxide ceramic, is reduced and metallized, the wettability is improved and the alumina can be combined with an aluminum alloy. The molten aluminum alloy is infiltrated into the porous ceramics. The aluminum alloy easily penetrates into the porosity of the reduced oxide-based ceramics and chemically bonds strongly to the oxide-based ceramics.
As a result, an aluminum-based composite material that easily undergoes plastic deformation and is excellent in formability can be obtained, and extrusion and drawing in a subsequent step become easy.

The aluminum-based composite billet is formed into a cylinder by an extrusion press. Aluminum-based composite billets have good moldability and are easy to extrude. In addition, by applying deformation at a high extrusion ratio, internal defects can be removed and densification can be achieved, and quality can be improved. Increase the accuracy of the inner and outer diameter of the cylinder by pulling. Since the inner and outer diameters have high accuracy, they can be assembled without cutting. The cylinder after the drawing is cut to produce a cylinder liner. The cylinder liner is completed only by cutting, thus improving production efficiency.

The cylinder liner is fitted to the cylinder block. When integrated with fitting, unlike conventional liner castings, the inner diameter of the cylinder liner is not distorted due to heat during casting and the roundness is good, so the finishing allowance for the inner diameter can be reduced. , Making the finishing process easier. As a result, the grinding time of the inner diameter can be reduced, and the cost of machining can be reduced. Further, since the fitting is performed, unlike the conventional cast-in, there is no casting defect at the joint between the cylinder block and the cylinder liner, and the quality is improved.

In the second aspect, the extrusion ratio in the extrusion step is 10
Set to ~ 50. When the extrusion ratio is 10 or more, the tensile strength and proof stress of the aluminum-based composite material become almost constant. If the extrusion ratio is large, the productivity is improved, so that the extrusion ratio is preferably large. However, when the extrusion ratio exceeds 50, the extrusion force increases, and a large-sized facility is newly required. As a result, by setting the extrusion ratio to 10 to 50, the tensile strength and proof stress of the aluminum-based composite can be increased, and the production cost can be reduced using existing equipment. In addition, since the present aluminum-based composite material has good moldability, it can be molded by increasing the extrusion ratio to 50, and the productivity can be improved.

In the third aspect, the cylinder block is heated to a predetermined temperature to form a gap between the hole of the cylinder block and the cylinder liner, so that the cylinder liner can be easily assembled to the cylinder portion. Further, at normal temperature, a uniform tightening force is applied to the outer surface, and the change in the inner diameter is small, so that the finishing is easier. As a result, the grinding time for the inner diameter of the cylinder can be reduced, and the production efficiency of the cylinder block can be improved.

According to the fourth aspect, the cylinder liner side is cooled and fitted into a normal-temperature cylinder block. Since the cylinder liner is a small part, the equipment for cooling the cylinder liner can be reduced in size and simplified, and the equipment cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of an apparatus for manufacturing an aluminum-based composite material according to the present invention.

FIG. 2 is a manufacturing procedure diagram of an aluminum-based composite billet according to the present invention.

FIG. 3 is an explanatory diagram of an extrusion process according to the present invention.

FIG. 4 is a graph showing the relationship between the extrusion ratio and the tensile strength / proof stress according to the present invention.

FIG. 5 is an explanatory view of a drawing step according to the present invention.

FIG. 6 is a graph of an example comparing the processing accuracy of only extrusion and the processing accuracy after drawing according to the present invention.

FIG. 7 is an explanatory view of a tube cutting step according to the present invention.

FIG. 8 is a diagram illustrating a process of fitting a cylinder liner (first
Illustration of Example)

FIG. 9 is an explanatory diagram of a finishing process of the cylinder according to the present invention.

FIG. 10 is an enlarged view of a main part of the cylinder liner according to the present invention.

FIG. 11 is an explanatory view of a fitting process of a cylinder liner according to the present invention (second embodiment).

FIG. 12 is an explanatory view of a fitting step (third embodiment) of the cylinder liner according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Aluminum-based composite material manufacturing apparatus, 21 ... Oxide ceramics (alumina), 31 ... Aluminum alloy, 3
2 ... magnesium, 34 ... magnesium nitride, 35 ... aluminum-based composite billet, 45 ... cylinder (cylinder) after extrusion, 50 ... drawing device, 56 ... cylinder (cylinder) after extraction, 57 ... cylinder liner, 60 ... cylinder Block, 61: cylinder part, A0: cross-sectional area of billet before extrusion, A1: cross-sectional area of cylinder after extrusion, R: extrusion ratio.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B23P 11/02 B23P 11/02 A F02F 1/00 F02F 1/00 C 1/08 1/08 Z (72) Inventor Hiroto Shoko 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Takashi Kato 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. F-term (reference) 3G024 AA26 AA27 FA00 FA14 GA00 GA10 GA12 GA25 GA30 HA07 HA10 4E029 AA02 AA06 AC01 CA03

Claims (4)

[Claims] 1. An aluminum alloy and a magnesium or magnesium source are placed in a furnace together with a porous formed body made of an oxide ceramic, and the oxide ceramic is reduced by the action of magnesium nitride. A step of manufacturing an aluminum-based composite billet by infiltrating a molten aluminum alloy into a porous body; an extruding step of forming the aluminum-based composite billet into a cylinder by an extrusion press; and finishing the extruded cylinder with a drawing device. A drawing step of imparting accuracy to the inner and outer diameters; a cutting step of cutting the drawn cylinder to a predetermined length to form a cylinder liner of an aluminum-based composite material; and fitting the cylinder liner to a cylinder block. A method for manufacturing a cylinder block, comprising: a fitting step. 2. The extrusion ratio in the extrusion step is set to 10 to 50 when a value obtained by dividing a sectional area of a billet before extrusion by a sectional area of a cylinder after extrusion is set as an extrusion ratio. The method for manufacturing a cylinder block according to claim 1. 3. The method according to claim 1, wherein said fitting step is shrink fitting. 4. The method according to claim 1, wherein the fitting step is a cold fitting.