JPH0245943B2 - - Google Patents

Description

Detailed Description of the Invention A. Purpose of the Invention (1) Industrial Field of Application The present invention relates to a Siamese cylinder block, particularly an aluminum alloy Siamese cylinder barrel formed by connecting a plurality of cylinder barrels, each cylinder barrel being made of cast iron. This invention relates to a method of manufacturing a sleeve-cast product.

(2) Conventional technology Conventionally, the Siamese type cylinder block having the above structure has been manufactured by installing sleeves in a mold, die-casting the cylinder block material, and then processing the inner peripheral surface of each sleeve into a perfect circle. There is.

(3) Problems to be Solved by the Invention Casting distortion occurs in the cylinder barrel of the cylinder block material obtained in the above casting process due to casting pressure and rapid solidification of the aluminum alloy, and the sleeve is thin. In the case of low steel properties, the casting distortion affects the sleeve, causing distortion in the sleeve.
In order to avoid this, it is possible to increase the wall thickness of the sleeve, but even in this case, if the inner peripheral surface of the sleeve is machined into a perfect circle immediately after casting and the engine is assembled and operated, the cylinder barrel will heat up during operation. When the cylinder returns to room temperature after stopping operation, the casting distortion of the cylinder barrel affects the sleeve, increasing the amount of permanent deformation of its inner diameter, creating a gap between the piston ring and the sleeve, increasing blow-by gas, and causing oil leakage. There is a problem with wasted consumption.

In view of the above, the present invention reduces the influence of casting distortion of the cylinder barrel on the sleeve by using a thick-walled and highly rigid sleeve, and also reduces the casting distortion of the cylinder barrel by heat treatment, thereby permanently changing the inner diameter of each sleeve. It is an object of the present invention to provide the above-mentioned manufacturing method, which makes it possible to obtain a Siamese-type cylinder block with significantly reduced deformation.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a method of installing the thick-walled and highly rigid sleeve whose wall thickness is set to 10% or more of the inner diameter in a mold. Then, a cylinder block material casting process in which molten metal is pressurized and filled into the mold; heat treatment is applied to the cylinder block material taken out from the mold in order to reduce the casting strain generated in the cylinder barrel during the casting process; The method is characterized by using the steps of: applying the heat treatment to the inner circumferential surface of the sleeve in the cylinder block material subjected to the heat treatment.

(2) Effect If a thick-walled, highly rigid sleeve is used, the influence of casting distortion of the cylinder barrel on it will be reduced.
Further, by heat-treating the cylinder block material taken out from the mold after casting, the casting strain generated in the cylinder barrel during the casting process is reduced. When the sleeve is then machined into a perfect circle, even if it becomes thin and has low rigidity, the casting strain of the cylinder barrel is reduced, so that the influence of the casting strain on the sleeve is almost eliminated.

When an engine is assembled and operated using the cylinder block thus obtained, the amount of permanent deformation of the inner diameter of each sleeve is minimal.

(3) Embodiment FIGS. 1 to 3 show a Siamese type cylinder block S obtained according to the present invention, which consists of a cylinder block body 2 made of aluminum alloy and a sleeve 3 made of cast iron. The cylinder block body 2 has a plurality of cylinder barrels 1 ₁ to 4 in the illustrated example.
1 ₄ , an outer wall portion 4 surrounding the Siamese cylinder barrel 1, and a crankcase 5 connected to the lower edge of the outer wall portion 4. A water jacket 6 facing the outer periphery of the Siamese cylinder barrel 1 is formed between the Siamese cylinder barrel 1 and the outer wall 4, and each cylinder barrel 1 ₁ to 1 ₄ is connected to the cylinder head side end of the water jacket 6.
and the outer wall portion 4 are partially connected by a plurality of reinforcing deck portions 8 arranged in the circumferential direction, and the space between adjacent reinforcing deck portions 8 functions as a communication port 7 to the cylinder head side of the water jacket 6. do. As a result, the cylinder block S is constructed into a closed deck type. Sleeve 3 is attached to each cylinder barrel 1 ₁ ~
₁₄ , and the sleeve 3 defines a cylinder bore 3a.

Figure 4 shows the cylinder block material Sm obtained by casting, and the sleeve 3 in this material Sm.
The inner diameter of the tube is 78 mm, and the wall thickness is 10% or more of the inner diameter, for example, 8 mm.

5 to 9 show the cylinder block material
Showing a casting device for Sm, the device includes a mold M,
The mold M includes an upper mold 9 that can be raised and lowered, and is disposed below the upper mold ₉ , and as shown in _FIGS . In Figure 7, the third and fourth side molds 1 are divided into left and right halves.
0 ₃ , 10 ₄ and a lower mold 11 on which the side molds 10 ₁ to 10 ₄ are slidably placed.

A mold clamping recess 12 is formed on the lower surface of the upper mold 9 to define a first cavity C ₁ in order to mold the Siamese cylinder barrel ₁ and the outer wall ₄ in cooperation with the upper half of each of the side molds 10 1 to 10 4 . is formed, and its recess 12
The mold clamping convex portion 13 that fits with each side mold 10 ₁ to 1
0 ₄ protrudes from the top surface.

As shown in FIGS. 7 and 8, the lower mold 11 includes a sump 14 that receives molten metal made of aluminum alloy from a melting furnace (not shown), a hot water cylinder 15 communicating with the sump 14, and a hot water supply cylinder 15 that communicates with the sump 14. A plunger 16 that slides onto the hot water supply cylinder 15 and a
branching into the book in the longitudinal direction of the first cavity _C1 ;
In addition, a pair of runners 17 are provided that extend over approximately the same length. Also, the lower mold 11 has both runners 17
It has a molding block 18 projecting upwardly in between, and the molding block 18 is connected to each side mold 10 ₁ to 10 _{4 .}
A second cavity _C2 is formed which forms the crankcase 5 in cooperation with the lower half of the crankcase C2. that cavity
The upper end of C ₂ communicates with the first cavity C ₁ , and the lower ends on both sides communicate with both runners 17 via a plurality of weirs 19 .

The molding block 18 includes four tall semi-cylindrical first molding parts ₁₈₁ formed at predetermined intervals;
Between adjacent first molded parts 18 ₁ and both outermost first molded parts 18 1
It consists _of a convex second molding part ₁₈₂ located outside the molding part 181, and each first molding part ₁₈₁ is for molding a rotation space 20 for a crank pin and a crank arm (FIGS. 2 and 3). The second molded part 18 ₂ is used for the bearing holder 2 of the crank journal.
1 (Figures 2 and 3). Each weir 19 is provided corresponding to each second molding section 18 ₂ , and is designed to quickly fill the large capacity portion of the second cavity C ₂ with molten metal.

The runners 17 are arranged such that the cross-sectional area of both runners 17 gradually decreases from the water reservoir 14 side toward the runner tip 17a.
The bottom surface of 7 is formed in the shape of several steps ascending from the trough portion 14 side. Each rising portion 17c connected to each step portion 17b is formed diagonally so that the molten metal can be smoothly guided to each weir 19.

If the cross-sectional area of the runner 17 is reduced in stages, a large amount of molten metal will be filled into the second cavity _C2 through the weir 19 at a slow speed in the large cross-sectional area, and a small amount will be filled in the small cross-sectional area. can be filled into the second cavity C ₂ through the weir 19 at a high speed, so that the cavity C ₂
Inside, the molten metal level rises almost evenly over the entire length from the lower ends of both sides, so that the molten metal rises to the second cavity.
There is no turbulence in C ₂ , and gases such as air are prevented from being drawn into the molten metal, thereby avoiding the formation of cavities. Further, since the molten metal filling operation is performed efficiently, casting efficiency can be improved.

As shown in FIGS. 5 and 6, each first molding section 18 ₁
A positioning protrusion 22 that fits into the inner circumferential surface of the cast iron sleeve 3 is protruded from the top surface of the cast iron sleeve 3, and a recess 23 is formed in the center of the positioning protrusion 22. Further, in the two first molded parts 18 ₁ located on both sides, through holes 24 are formed that penetrate through the first molded parts 18 ₁ on both sides of the positioning protrusion 22 .
4, a pair of temporary installation pins 25 are slid together, respectively.
These temporary installation pins 25 are used for temporary installation of a sand core for a water jacket. The lower ends of both temporary installation pins 25 are fixed to a mounting plate 26 disposed below the molding block 18. Its mounting plate 26
Two support rods 27 are inserted through the support rods 27, and a coil spring 28 is compressed between the lower part of each support rod 27 and the lower surface of the mounting plate 26. When the mold is opened, the mounting plate 26 receives the elastic force of each coil spring 28 and rises until it comes into contact with the stopper 27a at the tip of each support rod 27, so that the tip of each temporary installation pin 25 is attached to the first molded part 18 ₁ It protrudes from the top. A recess 25a that engages with the lower edge of the sand core is formed on the tip end surface of each temporary installation pin 25.

Further, in the two first molded parts 18 ₁ located on both sides, a through hole 29 is formed that penetrates the first molded part 18 ₁ at a bisecting position between both through holes 24 , and the lower end is inserted into the through hole 29 . An operating pin 30 fixed to the mounting plate 26 is slid together. When the mold is opened, the tip of the operating pin 30 protrudes into the recess 23, and when the mold is closed, it is pushed down by a diameter expanding mechanism, which will be described later, so that both temporary pins 25 are retracted from the top surface of the first molding section ₁₈₁ . It's summery.

The second in the first and second side molds 10 ₁ , 10 ₂
Core holders 31 for actually installing sand cores are provided at two locations in the center of the wall defining the cavity _C2 . Each core holder 31 includes an engagement hole 31a for positioning the sand core, and a clamping surface 31b formed on the outer periphery of the opening to clamp the sand core.

A first cavity is placed in the mold clamping recess 12 of the upper mold 9.
A plurality of _third cavities C ₃ for overflow and fourth cavities C ₄ for forming communication ports are opened, and each third cavity C 3 is connected to the upper die 9 .
Through holes 32 and 33 communicating with C ₃ and each fourth cavity C ₄ are formed, respectively.

The through holes 32 and 33 have closing pins 34 and 3.
5 are inserted, respectively, and the closing pins 34, 3
The upper end of 5 is a mounting plate 36 disposed above the upper mold 9.
Fixed.

Both cavities C ₃ and C ₄ of each through hole 32 and 34
The small diameter portions 32a, 33a extend upwardly over a predetermined length from the communicating ends of the respective closing pins 34, 3.
5 to close the third and fourth cavities C ₃ and C ₄ , but the diameter of the outer portion is smaller than that of each closing pin 3 .
4, 35, thereby forming air passages 37, 38 between each closing pin 34, 35 and each through hole 32, 33.

A hydraulic cylinder 39 is interposed between the top surface of the upper die 9 and the mounting plate 36, and the operation of the hydraulic cylinder 39 moves the mounting plate 36 up and down to close each closing pin 34, 3.
5 to open and close each small diameter portion 32a, 33a. 40 is a guide rod for the mounting plate 36.

The upper mold 9 has a diameter expanding mechanism 4 for holding the sleeve 3 cast into each cylinder barrel 1 ₁ to 1 _{4 .}
1 is provided, and its mechanism 41 is constructed as follows.

A through hole 42 whose center line coincides with the extension axis of the operating pin 30 is formed in the upper mold 9, and a support rod 43 is loosely inserted into the through hole 42. The upper end of the support rod 43 is fixed to a bracket 44 erected on the top surface of the upper mold 9, and a molten metal intrusion prevention plate 45 is fixed to the lower end. A convex portion 45 a that can fit into the concave portion 23 on the top surface of the first molded portion 18 ₁ in the lower mold 11 is formed on the lower surface of the molten metal intrusion prevention plate 45 .

The hollow holding cylinder 46 has a circular outer peripheral surface and a tapered hole 47 with a downward slope from the top to the bottom. The holding cylinder 46 is inserted loosely, and its upper end surface abuts a protrusion 48 protruding from the recess 12 of the upper mold 9, and its lower end surface abuts a molten metal intrusion prevention plate 45. As shown in FIG.
A plurality of slot grooves 49 extending radially from the inner circumferential surface and outer circumferential surface of the circumferential wall are formed alternately and at equal intervals on the circumference.

A hollow actuating rod 50 for expanding the diameter of the holding tube 46 is slid onto the supporting rod 43 over substantially the entire length of the supporting rod 43, and the actuating rod 50 has a tapered shape that fits into the tapered hole 47 of the holding tube 46. Part 50
a, and a perfectly circular portion 50b that is connected to the tapered portion 50a, slides into the through hole 42 of the upper mold 9, and projects from the upper mold 9. A plurality of pins 57 are provided protruding from the tapered portion 50a, and these pins 57 are inserted into pin holes 58 that are long in the vertical direction of the holding tube 46, thereby allowing the rotation of the holding tube 46 while allowing the vertical movement of the tapered portion 50a. A stop is made.

A hydraulic cylinder 51 is fixed to the top surface of the upper die 9, and hollow piston rods 53 ₁ and 53 ₂ projecting from the upper and lower end surfaces of the hollow piston 52 respectively touch the upper and lower end walls of the cylinder body 54. Penetrating. A true circular portion 50b of the actuating rod 50 is inserted into a through hole 55 passing through the hollow piston 52 and the hollow piston rod 53, and a stopper 56 ₁ to prevent removal is fitted into an annular groove of the circular portion 50b.
56 ₂ on the hollow piston rods 53 ₁ and 53 ₂ ,
The actuating rod 50 is raised and lowered by a hollow piston 52, which is brought into contact with the lower end surface. Four diameter expanding mechanisms 41 are provided corresponding to each of the cylinder barrels ₁₁ to ₁₄ of the cylinder block S.

10 and 11 show a sand core 59 for a water jacket, and the sand core 59 has four cylindrical portions 60 ₁ corresponding to the four cylinder barrels 1 ₁ to 1 ₄ of the cylinder block S. - ₆₀₄ , and a core body 61 which lacks the circumferential walls overlapping their adjacent ones, and a communication port 7 which communicates the water jacket with the water jacket of the cylinder head.
In order to form a plurality of protrusions 62 protruding from the upper end surface of the core body 61 and protruding from both outer surfaces of the two cylindrical parts 60 ₂ and 60 ₃ located in the middle of the core body 61, respectively. The baseboard 63 is made of Each baseboard 63 has a large diameter portion 63a integrated with the core body 61,
It is formed with a small diameter portion 63b protruding from its end surface. In this case, the protrusion 62 is connected to the fourth cavity.
Its dimensions are set so that it can be inserted loosely into _C4 .

Next, the cylinder block material is made by the casting machine.
I will explain the casting work of Sm.

First, as shown in FIG. 5, the upper mold 9 is raised,
Also, opposing both sides 10 ₁ , 10 ₂ ; 10 ₃ , 1
0 ₄ are moved apart from each other to open the mold. In the diameter expanding mechanism 41, each hydraulic cylinder 51 is operated to lower the actuating rod 50 using the hollow piston 52, and the diameter of the holding cylinder 46 is reduced by moving the tapered portion 50a downward. Also upper mold 9
The upper hydraulic cylinder 39 is operated to raise the mounting plate 36, thereby opening the small diameter portion 3 that communicates each closing pin 34, 35 with the third and fourth cavities _C3 , _C4 .
It is separated from 2a and 33a. Furthermore, the plunger 16 in the hot water supply cylinder 15 is lowered.

A thick-walled, highly rigid cast iron sleeve 3 having a wall thickness of 8 mm and having a substantially perfect circle is loosely fitted into each holding cylinder 46, and the upper end opening of the sleeve 3 is closed by fitting into the convex portion 48 of the upper mold 9. The lower end surface of the sleeve 3 is aligned with the lower end surface of the convex portion 45a of the molten metal intrusion prevention plate 45, and the lower end opening of the sleeve 3 is closed by the molten metal intrusion prevention plate 45. Then, the hydraulic cylinder 51 of the diameter expanding mechanism 41 is operated, and the hollow piston 52 causes the operating rod 50
to rise. As a result, the tapered portion 50a moves upward, so that the holding cylinder 46 expands in diameter, and the sleeve 3
is reliably held in the holding cylinder 46 by receiving the expanded path.

As shown in FIGS. 5 and 11, the lower edges of the cylindrical portions 60 ₁ and 60 ₄ on both sides of the sand core 59 are connected to temporary installation pins that protrude from the top surface of the first molding portions 18 ₁ on both sides of the lower mold 11. The sand core 59 is temporarily installed by engaging the recess 25a of the sand core 59.

The two-sided molds 10 ₁ and 10 ₂ are moved a predetermined distance in the direction in which they approach each other, and the small diameter portion 63b of each baseboard 63 of the sand core 59 is fitted into the engagement hole 31a of each core receiver 31, and the sand The core 59 is positioned, and the end face of each large diameter portion 63a is aligned with the clamping surface 3 of each core receiver 31.
1b, thereby accurately positioning the sand core 59 and sandwiching it between the molds 10 ₁ and 10 ₂ on both sides, thereby performing the actual installation of the sand core 59. Also, other double-sided type 10 ₃ , 1
Move 0 ₄ in the same way.

As shown in FIG. 6, the upper die 9 is lowered and each sleeve 3 is inserted into each cylindrical portion 60 ₁ to 60 ₄ of the sand core 59, and the convex portion 45a of the molten metal infiltration prevention plate 45 is first formed. Part 18 ₁ fits into the recess 23 on the top surface. As a result, the operating pins 30 are pushed down by the convex portions 45a of the molten metal intrusion prevention plate 45, so that each temporary installation pin 2
4 descends and retracts from the top surface of the first molded part ₁₈₁ .
Moreover, the mold clamping recess 12 of the upper mold 9 is connected to each side mold 10 ₁ to
The mold clamping is performed by fitting into the mold clamping convex portion 13 of 10 ₄ .

A molten metal made of aluminum alloy is supplied from the melting furnace to the sump 14 of the lower mold 11, and the plunger 16 is raised to allow the molten metal to pass through the weir 19 from both runners 17 and into the cavity from both lower edges of the second cavity _C2 .
Fill C ₂ and the first cavity C ₁ . Gas such as air in both cavities C ₁ and C ₂ is pushed up by the molten metal and escapes above the upper mold 9 through air passages 37 and 38 communicating with the third and fourth cavities C ₃ and C ₄ .

In this case, the bottom surface of the runners is formed in several ascending steps from the trough portion 14 side so that the cross-sectional area of both runners 17 gradually decreases toward the runner tip 17a as described above. As the plunger 16 rises, the molten metal is smoothly pushed up into the cavity C 2 from both runners 17 and through each weir 19 from the lower ends of both sides of the second cavity C ₂ almost uniformly over _its entire length. Therefore, the molten metal has both cavities C ₁ and C ₂
This prevents turbulence within the molten metal, prevents gases such as air from getting into the molten metal, and prevents the formation of cavities.

When the third and fourth cavities C ₃ and C ₄ are filled with molten metal, the hydraulic cylinder 39 on the upper mold 9 is operated to lower the mounting plate 36, and the closing pin 34,
35 closes the small diameter portions 32a and 33a communicating with both cavities C ₃ and C ₄ .

In the pouring work, the second and first cavities
Plunger 16 for filling C ₂ and C ₁ with molten metal
The displacement and molten metal pressure are controlled as shown in FIG.

That is, the plunger 16 changes its moving speed from the first to
The third speed is controlled in three stages, _V1 to _V3 . In this example, the first speed V ₁ is 0.08 to 0.12 m/sec, and the second speed V ₂ is
0.14 to 0.18 m/sec, and the third speed V ₃ is set to 0.04 to 0.08 m/sec to achieve a significant deceleration state. By controlling the speed in these three stages, the molten metal is prevented from rippling and air etc. Forms a quiet flow of molten metal without involving any gases, and directs the molten metal into both cavities.
C ₂ and C ₁ can be efficiently filled.

In addition, at the first speed V ₁ of the plunger 16, the molten metal only fills both runners 17, etc., so the pressure P ₁ of the molten metal is kept approximately constant, and at the second and third speeds V ₂ and V of the plunger 16. In ₃ , the molten metal is in both cavities C ₁ ,
Since C ₂ is filled with molten metal, the pressure P ₂ of the molten metal rises rapidly. After moving the plunger 16 at the third speed _V3 for a predetermined time, the molten metal filling pressure _P3 is increased to 150°C for about 1.5 seconds.
The temperature is maintained at ~400 Kg/cm ² , thereby completely covering the sand core 59 with the molten metal and forming a molten metal coagulation film on its surface.

After the above-mentioned time has elapsed, the plunger 16 is moved at a reduced speed _V4 , so the pressure _P4 of the molten metal rises, and when the pressure _P5 reaches 200 to 600 kg/ ^cm2 , the plunger 16 stops moving. solidify the molten metal.

If a molten metal coagulation film is formed on the surface of the sand core 59 by keeping the pressure of the molten metal substantially constant for a predetermined period of time as described above, the sand core 59 will be protected by the film and damaged during the next pressurization of the molten metal. There is no.

Furthermore, the sand core 59 expands due to the molten metal, but since the protrusion 62 is loosely inserted into the fourth cavity _C4 , the protrusion 62 follows the expansion of the sand core 59, thereby preventing the protrusion 62 from breaking. Avoided.

Furthermore, since the sand core 59 is held in an accurate position by the molds 10 ₁ and 10 ₂ on both sides through its baseboards 63, the sand core 59 is held in an accurate position by the molds 10 1 and _{10 2} on both sides. When the molten metal in ₁ is pressurized, the sand core 59 does not float or sag. Furthermore, since the end surface of the large diameter portion 63a of each skirting board 63 abuts against the clamping surface 31b of the core receiver 31 in the double-sided molds 10 ₁ and 10 ₂ , when the sand core 59 tends to swell, the deformation occurs. The force is applied to each clamping surface 31
b, thereby preventing deformation of the sand core 59 and providing a Siamese cylinder barrel 1 with uniform wall thickness around each sleeve 3.

By controlling the moving speed of the plunger 16 and the pressure of the molten metal as described above, a closed deck cylinder block material can be cast with substantially the same production efficiency as die casting.

When the molten metal has completely solidified, the hydraulic cylinder 51 of the diameter expanding mechanism 41 is operated to lower the actuating rod 50, thereby removing the holding cylinder 46 from the sleeve 3.
After that, the mold is opened and the fourth
Take out the cylinder block material Sm shown in the figure.

In this cylinder block material Sm, since each sleeve 3 has a thick wall and high rigidity, the effect of casting distortion of each cylinder barrel _{1 1} to 1 ₄ on each sleeve 3 is small.

Next, the cylinder block material Sm is heat treated at 220 DEG C. for 3 hours to reduce the casting strain generated in each of the cylinder barrels ₁₁ to ₁₄ .

After that, the cylinder block material Sm is subjected to a grinding process to remove the protrusions 64 formed by the cooperation between the fourth cavities _C4 and the protrusions 62 of the sand core 59, and the protrusions 62 form the communication ports 7. Further, reinforcing deck portions 8 are formed between adjacent communication ports 7, respectively. Next, the water jacket 6 is obtained by removing sand, and the inner peripheral surface of each sleeve 3 is processed into a perfect circle to have a wall thickness of 5 mm, and other predetermined processing is performed to obtain the first water jacket 6.
~The cylinder block S shown in FIG. 3 is obtained.

In FIG. 13, a shows the amount of permanent deformation of the inner diameter of the sleeve 3 at room temperature after heating the entire cylinder block S at 200° C., which is the temperature during engine operation, for one hour. b shows a comparative example obtained using an as-cast cylinder block material without heat treatment.

As is clear from Fig. 13, in the cylinder block of the comparative example, the amount of permanent deformation of the inner diameter of the sleeve is the depth from the gasket joint surface of the sleeve.
However, the cylinder block S obtained by the present invention shows a maximum value of 15μ at a depth of 30mm from the gasket joint surface Ga, and by heat-treating the cylinder block material Sm after casting, The amount of permanent deformation of the inner diameter of the sleeve 3 can be significantly reduced.

Note that if the wall thickness of the sleeve 3 is less than 10% of its inner diameter, the sleeve 3 will have low rigidity, and the casting strain of each cylinder barrel 1 ₁ to 1 ₄ will affect each sleeve 3, causing strain in each sleeve 3. This is not desirable because it occurs.

C. Effects of the Invention As described above, according to the present invention, the wall thickness is 10% of the inner diameter.
Since each cylinder barrel is cast with each thick-walled and highly rigid sleeve having a thickness of at least 100%, it is possible to reduce the influence of casting distortion of the cylinder barrel on the sleeve itself. Next, the cylinder block material taken out from the mold is heat treated to reduce casting distortion of the cylinder barrel, and the inner peripheral surface of the sleeve is machined into a perfect circle. Even if the rigidity is low, the effect of the casting strain on the sleeve can be almost eliminated by reducing the casting strain in each cylinder barrel.

Therefore, when an engine is assembled and operated using such a cylinder block, the amount of permanent deformation of the inner diameter of each sleeve is small.
By suppressing the gap between the piston ring and the sleeve as much as possible, problems such as an increase in blow-by gas and wasteful consumption of oil can be solved.

In addition, since the effects of casting distortion of each cylinder barrel on each sleeve itself are small, it is possible to make the spacing between adjacent sleeves as close as possible, which makes the cylinder block, and therefore the entire engine, smaller and lighter. can be achieved.

[Brief explanation of drawings]

1 to 3 show a Siamese type cylinder block manufactured according to the present invention, FIG. 1 is a perspective view seen from above, FIG. 2 is a sectional view taken along the line of FIG. 1, and FIG. -a line sectional view, 3rd
The figure is a perspective view seen from below, and Figure 4 is a perspective view of the Siamese type cylinder block material seen from above.
Figure 5 is a longitudinal sectional front view of the casting machine when the mold is opened;
The figure is a longitudinal sectional front view of the casting device when the mold is closed, FIG. 7 is a sectional view taken along the line shown in FIG. 6, FIG. 10
The figure is a perspective view of the sand core seen from above, Figure 11 is a sectional view taken along the line XI-XI in Figure 10, Figure 12 is a graph showing the relationship between the displacement of the plunger and the pressure of the molten metal over time, and Figure 13 The figure is a graph showing the relationship between the amount of permanent deformation of the inner diameter of the sleeve and the depth from the gasket joint surface of the sleeve. M...Mold, S...Cylinder block, Sm...
... Cylinder block material, 1 ₁ to 1 ₄ ... Cylinder barrel, 3 ... Sleeve.

Claims (1)

[Claims] 1. When manufacturing a Siamese type cylinder block in which a cast iron sleeve 3 is cast into an aluminum alloy Siamese cylinder barrel 1 formed by joining a plurality of cylinder barrels _{1 1} to _{1 4} , the wall thickness must be at least 10% of the inner diameter. A cylinder block material casting step in which the thick-walled and highly rigid sleeve 3 set to 1 is installed in a mold M, and then the mold M is filled with molten metal under pressure; In order to reduce casting distortion, a step of heat-treating the cylinder block material Sm taken out from the mold M; processing the inner peripheral surface of the sleeve 3 in the heat-treated cylinder block material Sm into a perfect circle; A method for manufacturing a Siamese type cylinder block, characterized by using the steps of: