JPH0466260A - Manufacture of cast iron-made cylinder block - Google Patents

Abstract

PURPOSE:To manufacture a cast iron-made cylinder block having sufficiently high wear resistance without deforming a liner by forming air heat insulating layer at inside of inner peripheral face of the liner separately formed and pouring molten iron into cavity in a mold. CONSTITUTION:The liner 5 is fixed through an upper and a lower fixing jigs 21, 22 in a master mold 1, and by setting a water jacket core 2, a mold DC'' is assembled. This liner 5 is formed e.g., with a high phosphorus cast iron and columnar inner space 23 at the inside thereof becomes an air heat insulating layer. After that, coating agent is applied on the upper fixing jig 21 and the lower fixing jig 22, and by pouring the molten cast iron into the cavity 4, the cylinder block B is cast. Then, cooling of the molten material is made to slow with the air heat insulating layer and joined strength between the liner 5 and inserting material is improved and the deformation is prevented. By this method, the compact cylinder block B having excellent wear resistance on the sliding surface 9 in the liner 5 and easy for machining without any deformation, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a cast iron cylinder block.

[Prior Art] In order to reduce the weight and size of automobiles, Siamese type cylinder blocks or aluminum alloy Norinder blocks are often used. However, since aluminum alloy has low heat resistance and wear resistance, a method of manufacturing a cylinder block has been proposed in which only the liner (cylinder liner) is made of cast iron and this cast iron liner is then cast with aluminum alloy ( For example, JP-A-58-21155
(See Publication No. 0).

However, in a diesel engine, since the heat load is high, sufficient durability cannot be obtained when an aluminum alloy cylinder block is used. Also, since the vibrations are strong,
When using an aluminum alloy cylinder block, vibration noise (
NVH) increases. For this reason, a cast iron cylinder block cast from cast iron is generally used in a diesel engine.

[Problems to be Solved by the Invention] Incidentally, foreign matter such as dust may enter the piston sliding surface of the liner portion of the cylinder block, and this foreign matter may cause damage to the piston sliding surface. For this reason, it is necessary to sufficiently increase the wear resistance of the piston sliding surface of the liner, but it is said that ordinary cast iron cylinder blocks made by casting cannot sufficiently increase the wear resistance of the piston sliding surface. There's a problem.

One possible solution to this problem would be to press-fit a liner made of a highly wear-resistant material into the cast iron cylinder block body, but doing so would require securing a press-fit allowance around the liner press-fit portion. The pitch between bores in the cylinder block becomes longer. For this reason, there is a problem that the cylinder block becomes longer in the longitudinal direction and becomes larger.

Another option would be to cast the cylinder block using cast iron material, which has high hardness, but this would result in a
Since the hardness of the cylinder block as a whole increases, there is a problem in that machining of the cylinder block body becomes difficult.

Therefore, as shown in FIG.
In a mold DC consisting of a water jacket core 2 and a bore core 3, a liner 5 made of a material with high wear resistance is fitted into the bore core 3, and the bore core 3 and the water jacket core 2 are is set in the matrix l to form a cavity 4 of a predetermined shape, and molten cast iron is poured into the cavity 4 to form the liner 5, main body 7, and water jacket 8 as shown in FIG. By obtaining the cylinder block B having the above, it is possible to obtain a compact cylinder block B in which the piston sliding surface 9 has high wear resistance and the main body portion 7 can be easily machined. I thought about it.

However, it has been discovered that when a liner, which is separately formed from a material with high wear resistance, is cast with cast iron, joint failures frequently occur at the joint surfaces between the liner and the cast material.

Furthermore, due to the shrinkage of the molten metal (casting material) during solidification,
It has been discovered that the liner may become deformed.

The present invention has been made in view of the above-mentioned conventional problems, and is a method for manufacturing a 7-wonder block by encasing a separately formed liner with cast iron, in which the cylinder block can be made more compact. The main body can be easily machined, and the wear resistance of the piston sliding surface of the liner can be sufficiently increased.
Can prevent liner deformation when molten metal solidifies,
The purpose of the present invention is to provide a method for manufacturing a cast iron cylinder block.

[Means for Solving the Problems] The present inventors conducted further detailed research on a method of manufacturing a cylinder block by casting a separately formed liner with cast iron, and found that the liner and the casting material were defective in joining. discovered that the reason for this is that in areas where the heat capacity of the molten metal is small, the molten metal cools rapidly and the liner and casting material are not completely fused and integrated. Therefore, the inventors of the present application believe that if the heat radiation from the liner is reduced,
We thought that it would be possible to promote the fusion and integration of the liner and casting material.

In view of these facts and considerations, the invention of claim 1 aims to achieve the above object by providing a cylinder block made of cast iron, in which a cylinder block is cast by casting a separately formed liner with cast iron. A method for manufacturing a cylinder block, the method comprising: forming an air insulation layer inside the inner peripheral surface of a liner;
To provide a method for manufacturing a cast iron cylinder block, characterized in that molten metal is poured into a cavity of a mold.

Further, the invention of claim 2 provides the method for manufacturing a cast iron cylinder block, in which a plurality of intermediate members having hollow portions are arranged along the inner peripheral surface of the liner, and a core is placed inside the annular arrangement of the intermediate members. To provide a method for manufacturing a cast iron cylinder block, characterized in that an air insulation layer is formed by filling sand.

[Operations and Effects of the Invention] According to the invention of claim 1, since an air heat insulating layer is formed inside the inner circumferential surface of the liner, heat radiation from the liner is reduced. The cooling of the liner and the casting material becomes gradual, promoting fusion and integration of the joining surfaces of the liner and the casting material, and the liner and the casting material are firmly joined.

According to the invention of claim 2, the same effects as in claim 1 can be obtained.

Furthermore, since the liner is supported and fixed by a hard intermediate member rather than a sand core, deformation of the liner during solidification of the molten metal is prevented.

[Example] Hereinafter, first to third embodiments of the present invention will be specifically described.

Note that the first embodiment corresponds to the invention of claim 2, and the second embodiment corresponds to the invention of claim 2. The third embodiment corresponds to the invention of claim I.

First Example> In the first example, basically the same mold DC as the conventional one as shown in FIG. 4 is used, and the cylinder block B as shown in FIG. 5 is obtained. Please refer to FIGS. 4 and 5. The method for manufacturing cylinder block B will be described below.

(2) As shown in FIG. 1, an annular intermediate member S consisting of a plurality of cylindrical intermediate members 11 connected in an annular manner is inserted into a liner 5 made of a highly wear-resistant iron-based material. Note that the length of each intermediate member 11 in the axial direction is approximately equal to the length of the liner 5 in the axial direction.

As shown in FIG. 2, the annular intermediate member S is formed by connecting cylindrical ceramic intermediate members 11 with hollow portions 12 without gaps using adhesive tapes 15 and 16, like a blind. The arrangement shape can be changed freely.

As shown again in FIG. 1, when the annular intermediate member S expands so that the cross-sectional area enclosed within it becomes the largest, that is, when each intermediate member 11 bulges outward the most, each intermediate member The most bulging portion of the member 11 is brought into contact with the inner circumferential surface of the liner 5.

■The inside of the annular intermediate member S charged into the liner 5 is filled with molding sand, the annular intermediate member S is bulged toward the inner peripheral surface of the liner, and the most swollen portion of each intermediate member 11 is placed in the liner 5. contact the inner circumferential surface of the Here, the molding sand filled inside the annular intermediate member S becomes the bore core 3. Further, a plurality of outer spaces 17 are formed between the inner circumferential surface of the liner 5 and the outer circumferential surface of the annular intermediate member S. Therefore, between the inner circumferential surface of the liner 5 and the bore core 3, the hollow portion 12 of each intermediate member 1.1 and the outer space portion 17 are formed over the entire circumference of the inner circumferential surface of the liner 5. An air insulation layer is formed.

■As shown in Figure 4, the water jacket core 2 and
A bore core 3 having an annular intermediate member S (see FIG. 1) and a liner 5 on its outer periphery is set in a mother mold 1.

■Pour molten cast iron into cavity 4. Here, since the air heat insulating layer is formed between the liner 5 and the bore core 3 as described above, the amount of heat radiated from the liner 5 is reduced. Therefore, the cooling of the molten metal in contact with the outer circumferential surface of the liner 5 is slowed down, the melting and integration of the molten metal (casting material) and the liner 5 is promoted, and the casting material (cylinder block main body) and the liner 5 are firmly bonded. Joined.

■ Cool and solidify the molten metal. At this time, although the molten metal contracts, the liner 5 is firmly supported and fixed by the hard annular intermediate member S made of ceramic, so the liner 5 is not deformed.

■Remove the matrix l and water jacket core 2. Furthermore, after breaking the bore core 3 and loosening the bulge of the annular intermediate member S, the annular intermediate member S and the bore core 3 are removed,
A cylinder block B as shown in FIG. 5 is obtained.

In this way, a cylinder block B is manufactured in which the liner 5 and the main body part 7 are firmly joined and the liner 5 is not deformed.

<Second Embodiment> As shown in FIG. 3, in the mold DC' of the second embodiment, there is a large part on the upper part of the bore core 3° that supports and fixes the liner 5 by contacting the inner circumferential surface of the liner 5. A diameter portion 3a is formed, and a large diameter portion 3a
A small diameter portion 3b smaller in diameter than this is formed below.

Therefore, an annular space 18 is formed between the inner circumferential surface of the liner 5 and the outer circumferential surface of the small diameter portion 3b, and this annular space 18 becomes an air insulation layer, thereby slowing down the cooling of the molten metal during pouring. The bonding strength between the liner 5 and the casting material is increased.

In addition, the large diameter portion 3a formed at the top of the bore core 3° is
Just press! (not shown), and since the molten metal is inherently difficult to cool down, sufficient bonding strength between the liner 5 and the casting material is ensured.

<Third Example> As shown in FIGS. 6 and 7, the mold D of the third example
C", no bore core is used, and the liner 5 is supported and fixed by the upper fixing jig 21 and the lower fixing jig 22. Therefore, the cylindrical space inside the inner peripheral surface of the liner 5 23 are all air insulation layers.The cylinder block manufactured in the third embodiment is a wet liner type cylinder block in which the liner 5 is brought into direct contact with cooling water in order to enhance the cooling effect of the engine. It is.

In the third embodiment, the mold DC" is assembled by first setting the lower fixing jig 22 on the mother mold l, fitting the lower end of the liner 5 into this lower fixing jig 22, and setting the water jacket core 2. After that, the upper fixing jig 21 is fitted into the upper end of the liner 5.

Here, the liner 5 has an eborin content of 0.6
The upper fixing jig 21 and the lower fixing jig 22 are made of ceramic.

Thereafter, a mold coating agent is applied to the upper fixing jig 21 and the lower fixing jig 22, and molten cast iron is poured to manufacture a cylinder block (not shown). Further, after removing the mold D C", the portion of the liner 5 that protrudes from the mating surface with the cylinder head (not shown) is removed by machining. Here, as the casting material, for example, iron material FC
25 is used, and the temperature of the molten metal is set at 1400°C.

In the third embodiment, the cooling of the molten metal is slowed down by the air insulation layer, and the bonding strength between the liner 5 and the casting material is increased, and the liner 5 is reliably supported and fixed by both fixing jigs 21 and 22. As a result, the dimensional accuracy of the cylinder block is improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of a bore core including a liner and an annular intermediate member, showing a first embodiment of the present invention. 2 is a perspective view of the annular intermediate member shown in FIG. 1; FIG. FIG. 3 is an explanatory longitudinal cross-sectional view of a mold showing a second embodiment of the present invention. FIG. 4 is an explanatory elevation cross-sectional view of a conventional mold, and is basically the same in the first and second embodiments. FIG. 5 is an explanatory elevational cross-sectional view of a cylinder block cast with the mold shown in FIG. 4. FIG. 6 and FIG. 7 are a side elevation cross-sectional view and a double elevation cross-sectional view of a mold, respectively, showing a third embodiment of the present invention. B...Cylinder block, 6c, pc゛, Dco"
・Mold, S... Annular intermediate member, 1... Mother mold, 2... Water jacket core, 3.3°... Bore core, 4...
...Cavity, 5. Liner, 11... Intermediate member, 1
2...Hollow part, 17...Outer space part, I8...Annular space part, 23...Cylindrical space part.

Claims (2)

[Claims] (1) A method for manufacturing a cast iron cylinder block, in which a cylinder block is cast by casting a separately formed liner with cast iron, and the method includes forming an air insulation layer inside the inner peripheral surface of the liner. A method for manufacturing a cast iron cylinder block, characterized by forming the cylinder block and pouring molten metal into a cavity of a mold. (2) In the method for manufacturing a cast iron cylinder block according to claim 1, a plurality of intermediate members having hollow portions are arranged along the inner peripheral surface of the liner, and a core is placed inside the annular arrangement of the intermediate members. A method for manufacturing a cast iron cylinder block, characterized in that an air insulation layer is formed by filling sand.