JPH0641016B2 - Siamese type cylinder block manufacturing method - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Field of Industrial Application The present invention is a Siamese type cylinder block, and in particular, a cast iron sleeve is cast around each cylinder barrel of an aluminum alloy Siamese cylinder barrel composed of a plurality of cylinder barrels connected in series. The present invention relates to a method of manufacturing things.

(2) Conventional technology Conventionally, in the Siamese type cylinder block having the above-mentioned configuration, the sleeve is installed in the cavity of the mold for the Siamese cylinder barrel, the cylinder block material is die-cast, and then the inner peripheral surface of each sleeve is processed into a perfect circle. It is manufactured by applying.

(3) Problems to be Solved by the Invention However, according to the above-mentioned manufacturing method, the opposing peripheral wall portions of the adjacent sleeves adjacent to each other when the molten metal is filled strongly receive the filling pressure of the molten metal, so that the opposing peripheral wall portions are dented and the cross section of each sleeve The shape becomes a substantially elliptical shape with the long axis orthogonal to the cylinder barrel arrangement direction.

In this case, the cross-sectional shape of each cylinder barrel when it contracts as the aluminum alloy solidifies is a substantially elliptical shape with the long axis parallel to the cylinder barrel arrangement direction, so that each sleeve receives each aluminum alloy contraction force. Although it tries to deform so as to follow the cross-sectional shape of the barrel when contracted, the deformed shape at the time of filling the molten metal is still maintained to the extent that the amount of depression of each opposing peripheral wall portion increases.

Therefore, the cross-sectional shape of each sleeve and the cross-sectional shape of each cylinder barrel are such that their major axes are offset by approximately 90 °, and the casting stress remaining in each sleeve becomes uneven around its circumference. In this state, if the inner peripheral surface of the sleeve is rounded and the engine is assembled and the engine is operated, the amount of thermal expansion around the circumference of the sleeve becomes uneven and a gap is created between the piston ring and the sleeve. There is a problem of increasing oil consumption and wasting oil.

In view of the above, it is an object of the present invention to provide the above-mentioned manufacturing method capable of obtaining a Siamese type cylinder block in which the amount of thermal expansion around the circumference of each sleeve during engine operation is substantially uniform.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention is to install the sleeve in a cavity for molding a Siamese cylinder barrel of a mold and insert a mandrel into the sleeve. A casting process in which the molten aluminum alloy is pressure-filled into the cavity in such a state that the molten metal is solidified; and after the solidification of the molten metal is completed, the cored bar is pulled out from the sleeve, and a diameter expansion mechanism is installed in the sleeve. A step of inserting and expanding the sleeve to apply a expanding force to the sleeve, and cooling the aluminum alloy to room temperature in the expanded expansion applied state; after the cooling, the expanding force is removed and the expanding mechanism is installed. Withdrawing from the inside of the sleeve; applying a perfect circle to the inner peripheral surface of the sleeve;
It is characterized by including.

(2) Action In the above casting process, the sleeve prevents excessive deformation of the sleeve, and after the solidification of the molten metal reaches the temperature at which the mold can be opened, it is replaced with a core. Since the expanding mechanism applies the expanding force to the sleeve, the deformation of the sleeve that occurs when the molten metal is filled can be simply and effectively corrected by the expanding force even when the mandrel is used. Further, since the aluminum alloy is cooled to room temperature in such a state that the expanding force is applied, the deformation of the sleeve due to the contracting force due to the temperature decrease of the aluminum alloy up to room temperature can be regulated, and therefore, the adjacent sleeves Even if a slight recess due to the molten metal filling pressure remains in the opposing peripheral wall portions, there is no fear that the recess amount increases due to the contracting force of the alloy. Further, since the expanding force is removed after the aluminum alloy has cooled, the contracting force of the aluminum alloy acting on the sleeve causes the sleeve to deform so as to follow the sectional shape of the cylinder barrel when contracted.

As a result, the casting stress remaining in each sleeve is made substantially uniform around its circumference.

In this state, when the inner peripheral surface of each sleeve is processed into a perfect circle and the engine is assembled and operated, the thermal expansion amount around the circumference of each sleeve becomes substantially uniform.

(3) Example FIGS. 1 to 3 show a row-type Siamese type cylinder block S obtained according to the present invention. The cylinder block S is a cylinder block body 2 made of an aluminum alloy, and the cylinder block S is cast around the body 2. And a cast iron sleeve 3.
Cylinder block body 2 includes a plurality, illustrated embodiment the Siamese cylinder barrel 1 composed by combining four cylinder barrels 1 ₁ to 1 ₄ in series, an outer wall portion 4 surrounding the Siamese cylinder barrel 1, the outer wall 4 Each cylinder barrel 1 is composed of a crankcase 5 connected to the lower edge.
₁ to 1 _4, wherein the sleeve 3 are the cast Guruma the cylinder bore 3a is formed by the sleeve 3.

A water jacket 6 is formed between the Siamese cylinder barrel 1 and the outer wall portion 4 so as to cover the entire circumference of the Siamese cylinder barrel 1. At the opening on the cylinder head side of the water jacket 6, the Siamese cylinder barrel 1
The outer wall portion 4 and the outer wall portion 4 are connected by a plurality of reinforcing deck portions 8,
The space between the adjacent reinforcing deck portions 8 functions as a communication port 7 to the cylinder head side. As a result, the cylinder block S is constructed as a closed deck type.

5 to 8 show the cylinder block material S shown in FIG.
m is a casting device, which is provided with a mold M, which is movable up and down, and is arranged below the upper mold 9, and in FIG. First and second
It is composed of side molds 10 ₁ and 10 ₂ and a lower mold 11 on which both side molds 10 ₁ and 10 ₂ are slidably mounted.

On the lower surface of the upper mold 9, a mold clamping recess 12 that defines the upper surface of the first cavity C ₁ is formed, and a mold clamping projection 13 that fits into the recess 12 is formed on the upper surfaces of the double-sided molds 10 ₁ , 10 ₂ . Will be projected. As shown in FIG. 6, the first cavity C ₁ includes a cavity Ca for forming a Siamese cylinder barrel and a sand core 59 defined between a sand core 59 for forming a water jacket and a core 70 in a mold closed state. Both sides type 1
Cavity C for molding the outer wall portion defined between 0 ₁ and 10 _2.
b.

As shown in FIGS. 7 and 8, a lower mold 11 is provided with a molten metal reservoir 14 for receiving a molten metal made of an aluminum alloy from a melting furnace (not shown), and a hot water supply cylinder 15 communicating with the molten metal reservoir 14.
And the plunger 16 that is slid on the hot water supply cylinder 15
And a pair of runners 17 branched from the hot water reservoir 14 and extending in the cylinder barrel arrangement direction. Further, the lower die 11 has a forming block 18 protruding upward between the measuring runners 17, and the forming block 18 is a double-sided die 10 ₁ ,
10 ₂ and cooperates to define a second cavity C ₂ for forming the crank case 5. The upper end of the cavity 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 first semi-cylindrical molding parts 18 ₁ formed at predetermined intervals, and adjacent first molding parts 18 ₁ and outermost first molding parts 18 ₁ . more becomes convex-shaped second molded part 18 ₂ located outside, each of the first mold portion 18 ₁ is used to mold the rotation space 20 for the crank pin and the crank arm (second, third panel),
Second forming unit 18 ₂ bearing holder 2 of the crank journal
1 (FIGS. 2 and 3). Each weir 19 is provided corresponding to each second molding portion 18 ₂ .
The large capacity portion of the second cavity C ₂ is filled with the molten metal at an early stage.

Both runners 17 are formed such that the bottom surface of the runners 17 is in the form of several stairs rising from the side of the hot water reservoir 14 so that the cross-sectional area gradually decreases from the side of the hot water reservoir 14 toward the runner tip 17a. . The rising portions 17c connected to the step portions 17b are provided with molten metal at the weirs 19 respectively.
It is formed diagonally so that it can be smoothly guided to.

When the cross-sectional area of the runner 17 is gradually reduced in this way,
In the part with a large cross-sectional area, a large amount of molten metal is dammed at a slow speed.
The second was filled in cavity C _2, and because the small portion of the cross-sectional area can be filled in the second cavity C ₂ through weir 19 a small amount of the molten metal at a high speed through its from both sides lower end within the cavity C ₂ The level of the molten metal rises substantially uniformly over the entire length, so that the molten metal does not cause a turbulent flow in the cavity C ₂ , and gas such as air is prevented from being caught in the molten metal and avoids the formation of cavities. You can Further, since the molten metal filling work is efficiently performed, the casting efficiency can be improved.

As shown in FIGS. 5 and 6, a positioning projection 22 that fits with the inner peripheral surface of the cast iron sleeve 3 is provided on the top surface of each first molding portion 18 ₁ , and a recess is formed at the center of the positioning projection 22. Two
3 is formed. Further, through holes 24 penetrating the first molding portion 18 ₁ are formed on both sides of the positioning protrusion 22 in the two first molding portions 18 ₁ located on both sides, and a pair of temporary setting pins 25 are respectively formed in the through holes 24. The temporary setting pins 25 that are slid together are used for temporary setting of the sand core 59 for forming the water jacket. The lower ends of both temporary setting pins 25 are
It is fixed to a mounting plate 26 arranged below the molding block 18. Two support rods 27 are inserted through the mounting plate 26, and a coil spring 28 is contracted between the lower part of each support rod 27 and the lower surface of the mounting plate 26. Mounting plate 2 when the mold is opened
6 receives each elastic force of each coil spring 28 and each support rod 2
7 until it comes into contact with the stopper 27a at the front end of the first molding portion 18 _{1. As a result, the} front end of each temporary setting pin 25 projects from the top surface of the first molding portion 18 ₁ . A recess 25a that engages with the lower edge of the sand core is formed on the tip surface of each temporary setting pin 25.

The two first mold portion 18 ₁ positioned at both sides, through-holes 29 are formed at the bisecting position between the two through holes 24,
The operating pin 30 is slidably fitted into the through hole 29. The lower end of the operating pin 30 is fixed to the mounting plate 26. When opening the mold,
The tip of the operating pin 29 projects into the recess 23 and is pushed down by the mandrel 70 when the mold is closed, so that both temporary setting pins 25 can be pulled in from the top surface of the first molding portion 18 ₁ .

Core receiving 31 for the installation of the sand core 59 is provided addressed two locations in the central portion of the wall portion defining the second cavity C ₂ in the first and second side mold 10 _1, 10 ₂ . Each core receiver 31 has an engagement hole 31a for positioning the sand core,
Clamping surface 3 that is formed on the outer periphery of the opening and clamps the sand core
It consists of 1b.

A plurality of third cavities C _{3 for} communicating with the first cavity C ₁ for overflowing the molten metal and a fourth cavity C ₄ for forming the communication port 7 are formed in the mold clamping recess 12 of the upper mold 9. Further, the upper mold 9 is formed with gas vent holes 32 and 33 communicating with the third cavity C ₃ and the fourth cavity C ₄ , respectively.

Closing pins 34 and 35 are inserted into the gas vent holes 32 and 33, respectively, and upper ends of the closing pins 34 and 35 are fixed to a mounting plate 36 arranged above the upper die 9.

Each venting holes 32 and 34, both cavity _C 3, _{C 4} small-diameter portion 32a of the communicating end extending over a predetermined length upwards against, 33a are engaged with each closing pin 34, 35 the third cavity and it is able to close the C ₃ and the fourth cavity C _4.

A hydraulic cylinder 39 is interposed between the upper surface of the upper die 9 and the mounting plate 36, and the mounting of the mounting plate 36 by the operation of the hydraulic cylinder 39.
Is moved up and down, and each small diameter portion 32 is caused by each closing pin 34, 35.
A and 33a are opened and closed. 40 is a guide rod for the mounting plate 36.

A mandrel 70 is provided on the lower surface of the upper mold 9 so as to correspond to each sleeve 3, and a convex portion 70 a is formed on the lower surface of each mandrel 70.

9, FIG. 10 shows the water jacket sand core 59, the sand core 59, four cylindrical portion ₆₀ 1 in correspondence with the four cylinder barrels ₁ 1 to 1 ₄ of the cylinder block S 60
_{In order} to form a core main body 61 that is provided with ₄ and lacks peripheral walls where adjacent ones overlap with each other, a communication port 7 that connects the water jacket 6 to the water jacket of the cylinder head, and a reinforcing deck portion 8, A plurality of protrusions 62 projectingly provided on the upper end surface of the core body 61 and both outer surfaces of the core body 61 in the cylinder barrel arrangement direction, in the illustrated example, both of the _two cylindrical portions 60 ₂ and 60 ₃ located in the middle. It is composed of a skirting board 63 protruding from each of the outer side surfaces. Each skirting board 63 is the core body 61
And a large-diameter portion 63a integrally formed with the small-diameter portion 63b, and a small-diameter portion 63b projecting from the end surface thereof.

In FIGS. 11 to 13, reference numeral 41 denotes a diameter expanding mechanism that applies a diameter expanding force to the sleeve 3, and the diameter expanding mechanism 41 is configured as follows.

In FIGS. 11 and 12, a through hole 42 that allows the center line to match the extension axis of the operating pin 30 is formed in a support base 71 that is vertically and horizontally movable. Is inserted. The upper end of the support rod 43 is fixed to a bracket 44 provided upright on the upper surface of the support base 71, and the bottom plate 45 is fixed to the lower end thereof. Bottom plate 4
On the lower surface of No. 5, a convex portion 45a that can be fitted into the concave portion 23 of the top surface of the first molding portion 18 ₁ of the lower mold 11 is formed.

The hollow expanding cylinder 46 has a circular outer peripheral surface and a taper hole 47 having a downward slope from the upper part to the lower part, and the lower part of the support rod 43 projecting downward from the support base 71 is the taper hole of the expanding cylinder 46. The upper end surface of the expanded cylinder 46 is loosely inserted into 47, and the upper end surface of the expanded tube 46 abuts on a convex portion 48 provided on the lower surface of the support base 71. As shown in FIG. 13, the expanded cylinder 46
A plurality of slit grooves 49 extending in the radial direction from the inner peripheral surface and the outer peripheral surface of the peripheral wall portion are alternately formed at equal intervals on the circumference.

A hollow working rod 50 for expanding the diameter expanding cylinder 46 is slidably fitted over the supporting rod 43 over substantially the entire length of the supporting rod 43, and the operating rod 50 has a taper hole 47 in the diameter expanding cylinder 46.
And a perfect circular portion 50b which is provided continuously with the tapered portion 50a and which is slidably fitted into the through hole 42 of the support base 71 and protrudes from the support base 71. A plurality of pins 57 are projectingly provided on the taper portion 50a.
Is inserted into a vertically long pin hole 58 of the expanded tube 46,
As a result, the expanded diameter cylinder 46 is stopped while allowing the vertical movement of the tapered portion 50a.

The hydraulic cylinder 51 is fixed to the upper surface of the support base 71, and hollow piston rods 53 ₁ and 53 ₂ projecting from the upper end surface and the lower end surface of the hollow piston 52 penetrate the upper end wall and the lower end wall of the cylinder body 54, respectively. ing. The true circular portion 50b of the operating rod 50 is inserted into the through hole 55 penetrating the hollow piston 52 and the hollow piston rods 53 ₁ and 53 _2, and the stoppers 56 ₁ and 56 that are fitted in the annular grooves of the true circular portion 50b are retained. ₂ is a hollow piston rod 53 ₁ , 5
On the 3 _2, the hollow piston 5, respectively on the lower end surface brought into contact
The actuating rod 50 is moved up and down by means of 2.
Diameter member such as the flare tube 46 is provided for each cylinder barrel 1 ₁ to 1 ₄ of the cylinder block S.

Next, the casting operation of the cylinder block material Sm by the casting apparatus will be described.

First, as shown in FIG. 5, the upper mold 9 is raised, and the both side molds 10 ₁ and 10 ₂ are moved so as to be separated from each other to perform mold opening. Further, the hydraulic cylinder 39 on the upper die 9 is operated to raise the mounting plate 36, whereby each closing pin 3
4, 35 are disengaged from the small diameter portions 32a, 33a communicating with the third and fourth cavities C ₃ , C ₄ . Further, the plunger 16 in the hot water supply cylinder 15 is lowered. Furthermore, the support base 71 of the diameter expansion mechanism 41 is moved to a position apart from the mold M.

The lower opening of the cast iron sleeve 3 having a substantially perfect circle is formed into the first molding portion 18
_The sleeve 3 is fitted on the _first positioning protrusion 22 and the sleeve 3 is erected on the first molding portion 18 ₁ .

Fifth, both sides of the cylindrical portion 60 _1, 60 ₄ lower edge of the sand core 59 as shown in FIG. 10, the temporary installation pins projecting into the first top surface of the forming portions 18 ₁ on both sides of the lower mold 11 The sand core 59 is temporarily installed by engaging with the recess 25 a of the sand core 25.

The two-sided molds 10 ₁ and 10 ₂ are moved by a predetermined distance in a direction in which they approach each other, and each core support 31 and each skirting board 63 are engaged with each other to perform the main installation of the sand core 59. That is, the small diameter portion 63b of each skirting board 63 of the sand core 59 is fitted into the engagement hole 31a of each core receptacle 31 to position the sand core 59, and the cylinder barrel arrangement direction of each large diameter portion 63a. The end face parallel to the abutment surface abuts against the sandwiching surface 31b of each core receiver 31 to sandwich the sand core 59 with the sandwiching surface 31b.

As shown in FIG. 6, the upper die 9 is lowered and the mandrel 70 is inserted into each of the cylindrical portions 60 _{1 to} 60 ₄ of the sand core 59, and the mandrel 7
The convex portion 70a of 0 is fitted into the concave portion 23 on the top surface of the first molding portion 18 ₁ . As a result, the operating pin 30 is pushed down, so that each temporary setting pin 24 descends and is retracted from the top surface of the first molding portion 18 ₁ . In addition, the mold clamping recess 12 of the upper mold 9 is formed on both sides of the mold 1.
The mold clamping is performed by fitting into the mold clamping projections 13 of 0 ₁ and 10 ₂ .

Aluminum alloy A from the melting furnace into the hot water reservoir 14 of the lower mold 11.
The molten metal is supplied, the plunger 16 is raised, and the molten metal is filled into the cavities C ₂ and the first cavities C ₁ from both lower edges of the second cavities C ₂ through the weirs 19 from both runways 17. Gases such as air in the cavities C ₁ and C ₂ are pushed up by the molten metal and escape above the upper mold 9 through the gas vent holes 32 and 33 communicating with the third and fourth cavities C ₃ and C ₄ .

In this case, since the both runways 17 are formed in a step-like shape of several steps from the side of the hot water reservoir 14 so that the cross-sectional area gradually decreases toward the runway tip 17a as described above, As the plunger 16 rises, the molten metal will flow from both runways 17 to each weir 1.
Through 9, the inside of the cavity C ₂ can be smoothly pushed up substantially uniformly over the entire length from the lower ends on both sides of the second cavity C ₂ . Therefore, the molten metal has both cavities C ₁ and C ₁ .
There is no turbulent flow inside ₂ , and it is possible to prevent gas such as air from being entrained in the molten metal and avoid the formation of cavities.

After the third and fourth cavities C ₃ , C ₄ are filled with the molten metal, the hydraulic cylinder 39 on the upper die 9 is operated to attach the mounting plate 3
6 is lowered, and the small diameter portions 32a, 33a communicating with both cavities C ₃ , C ₄ are closed by the closing pins 34, 35.

In the pouring operation, the displacement of the plunger 16 and the molten metal pressure for filling the second and first cavities C ₂ , C ₁ with the molten metal are controlled as shown in FIG. 14.

That is, the plunger 16 changes its moving speed to the first to third speeds V.
It is controlled in three stages of _{1 to} V ₃ . In this embodiment, the first speed V
₁ 0.08~0.12m / sec, the second speed _{V 2} is 0.14~0.18m / s
ec, as third speed V ₃ is the significant deceleration state from 0.04 to 0.
Each of them is set to 08 m / sec, and by these three-stage speed control, the molten metal is prevented from being ruffled to form a quiet molten metal flow without entraining gas such as air, and the molten metal is stored in both the cavities C ₂ and C ₁ Can be filled efficiently.

Also, at the first speed V ₁ of the plunger 16, the molten metal is in both runways 1.
The pressure P ₁ of the molten metal is kept substantially constant because it is only filled with 7 or the like, and the second and third speeds V ₂ and V ₃ of the plunger 16 are maintained.
Then, since the molten metal is filled in both cavities C ₁ and C ₂ , the pressure P ₂ of the molten metal sharply rises. Plungeer 16 third
After moving at the speed V ₃ for a predetermined time, the melt pressure P ₃ is reduced to about
It is kept at 150 to 400 kg / cm ² for 1.5 seconds, whereby the sand core 59 is completely wrapped with the molten metal and a molten metal coagulation film is formed on the surface thereof.

After the time has elapsed, the plunger 16 is moved to the speed V ₄
Since the pressure P ₄ of the molten metal increases due to the deceleration movement by, the movement of the plunger 16 is stopped when the pressure P ₅ becomes 200 to 600 kg / cm ^2, and the molten metal is solidified in this state.

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 time as described above, the sand core 59 may be protected and damaged by the film when the molten metal is pressed next time. There is no.

In addition, the sand core 59 is a double-sided mold 1 through each skirting board 63 of the sand core 59.
Since it is clamped by 0 ₁ , 10 _{2 in the} correct position,
The sand core 59 does not float when the molten metal is filled in the first cavity C ₁ and when the molten metal in the cavity C ₁ is pressurized. Also, the large diameter portion 6 of each skirting board 63
The end face of 3a has a core holder 31 in the double-sided molds 10 ₁ and 10 ₂ .
Since the sand core 59 abuts against the sandwiching surface 31b, the deforming force of the sand core 59 is supported by the sandwiching surfaces 31b when the sand core 59 tends to swell. A Siamese cylinder barrel 1 having a uniform wall thickness of 3 rounds can be obtained.

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

In the step of filling the molten metal, there is a minute gap between the sleeve 3 and the mandrel 70, as is apparent from FIG. 6, so that within the range of this minute gap, they are adjacent to each other due to the filling pressure of the molten metal. The opposing peripheral wall portions of the sleeves 3 are recessed, and the cross-sectional shape of each sleeve 3 has a substantially elliptical shape with the major axis orthogonal to the cylinder barrel arrangement direction.

After the molten metal has solidified, the upper mold 9 is raised to raise the core 70.
Is pulled out from the sleeve 3.

In the diameter expansion mechanism 41, the hydraulic cylinder 51 is operated to lower the operating rod 50 by the hollow piston 52, and the diameter expansion cylinder 46 is reduced in diameter by the downward movement of the tapered portion 50a.

As shown in FIGS. 11 and 12, the support base 71 of the diameter expansion mechanism 41 is moved above the _two- sided molds 10 ₁ and 10 ₂ and then lowered to insert the diameter expansion cylinder 46 into the sleeve 3. The hydraulic cylinder 51 is actuated, the hollow piston 52 raises the actuating rod 50, and the tapered portion 50a is moved upward to expand the diameter expanding cylinder 46. As a result, a diametrical expansion force is applied to the sleeve 3, so that the depressions in the opposing peripheral wall portions of the adjacent sleeves 3 disappear, and the cross-sectional shape of the sleeve 3 becomes substantially circular.

Aluminum alloy A with expanding force applied to sleeve 3
To room temperature. In this case, the contracting force of the aluminum alloy A acts on the opposing peripheral wall portions of the adjacent sleeves 3, but the expanding force is applied to the sleeve 3, so that the expanding force restricts the deformation of the sleeve 3, and accordingly Even if a slight dent remains in the facing peripheral wall portion, there is no fear that the dent amount will increase due to the shrinkage force when the temperature of the aluminum alloy A is lowered to room temperature.

After the aluminum alloy A is cooled to room temperature, the hydraulic cylinder 51 is operated and the operating rod 50 is lowered to remove the expanding force of the expanding cylinder 46 on the sleeve 3. Thus the sleeve 3 by the contraction force of an aluminum alloy A acting on the sleeve 3 is deformed so as to follow the cross-sectional shape at the time of contraction of the cylinder barrel 1 ₁ to 1 _4.

Through the above steps, the cylinder block material Sm shown in FIG.
Is obtained.

In this cylinder block material Sm, FIG.
Tarirondo measurement (100-fold) of (a) cross-sectional shape of each sleeve 3, as shown in the results, the major axis cylinder barrel 1 ₁ -
Exhibit 1 ₄ substantially elliptical shape which has parallel to the array direction of which is consistent with the cross-sectional shape during solidification contraction of the respective cylinder barrel 1 ₁ to 1 _4. As a result, the casting stress remaining in each sleeve 3 is made substantially uniform over the entire circumference.

FIG. 15 (b) shows the Talylond measurement result of the Siamese type cylinder block material as a comparative example obtained by casting the round sleeve 300 into the cylinder barrels 100 _{1 to} 100 ₄ by the conventional method. As is apparent, the cross-sectional shape of each sleeve 300 has a substantially elliptical shape with the major axis orthogonal to the arrangement direction of the cylinder barrels, and is particularly caused by the filling pressure of the molten metal in the opposing peripheral wall portions of the adjacent sleeves 300. The dent 300a is generated.

After the measurement, the cylinder block material Sm obtained according to the present invention is subjected to grinding, and the protrusions 6 formed by the cooperation of the fourth cavities C ₄ and the protrusions 62 of the sand core 59.
When 4 is removed, each communication port 7 and the reinforcing deck part 8 are formed, and the sand jacket is removed to obtain the water jacket 6. Further, the inner peripheral surface of each sleeve 3 is rounded,
Furthermore, when other predetermined processing is performed, the cylinder block S shown in FIGS. 1 to 3 is obtained.

The cylinder block is obtained by performing the same processing on the comparative example.

FIGS. 16 (a) and 16 (b) show changes in inner diameters of both sleeves 3,300 when the both cylinder blocks are heated uniformly, as expansion amounts. The expansion amount was measured by determining the change in the inner diameter at four points a _{1 to} a ₄ on the circumference as shown in FIG.

FIG. 16 (a) shows the case of the cylinder block S obtained according to the present invention, in which the difference D ₁ between the maximum expansion amount and the minimum expansion amount around 190 °, which is the heating temperature of the cylinder block during engine operation, is 20 μ. The expansion amount at each point a _{1 to} a ₄ varies little. Moreover, the expansion amounts are close to the theoretical expansion amount T. This is because the casting stress remaining in each sleeve 3 is substantially uniform over the entire circumference.

FIG. 16 (b) shows the case of the comparative example, in which the difference D ₂ between the maximum expansion amount and the minimum expansion amount at the same temperature as the above is as large as 128 μ, and the expansion amount at each point a _{1 to} a ₄ varies. Can be seen. Moreover, three points of the expansion amount are a ₂ , a ₃ , and a _4.
The values in are separated by more than the theoretical expansion amount T. This is because the casting stress remaining in each sleeve 300 is non-uniform over the entire circumference.

The present invention is not limited to the column-shaped Siamese type cylinder block, and is also applied to the case of manufacturing a V-shaped Siamese type cylinder block.

C. EFFECTS OF THE INVENTION According to the present invention, the sleeve is prevented from being excessively deformed in the casting process by the mandrel fitted in the sleeve, and further, the temperature at which the molten metal is solidified and the mold can be opened. After that, the diametrical expansion mechanism that replaces the mandrel applied a diametrical expansion force to the sleeve, so even if the mandrel is used, the deformation of the sleeve that occurs when filling the molten metal can be corrected simply and effectively. can do. Since the aluminum alloy is cooled to room temperature while the expanding force is applied to the sleeve in this way, the deformation of the sleeve due to the shrinkage force due to the temperature decrease of the aluminum alloy up to room temperature can be regulated, and thus Siamese Since the residual stress of each sleeve in the die cylinder block material can be made substantially uniform around its circumference, if the inner peripheral surface of each sleeve of the same material is then subjected to perfect circle processing, the engine operating condition will be improved. The thermal expansion amount of each of the sleeves becomes substantially uniform around the circumference thereof, which can contribute to the reduction of the blow-by gas amount and the saving of oil.

In addition, especially in the casting process where the temperature in the cavity and the sleeve are extremely high, a core metal is used to support the sleeve, and after the molten metal has solidified and cooled to a temperature at which the mold can be opened, the core metal is replaced with a diameter expansion mechanism. Since the diametrical expansion force is applied to the sleeve, there is no risk of the diametrical expansion mechanism becoming excessively hot, so there is no need to take special high temperature measures when designing the diametrical expansion mechanism, contributing to cost reduction. can do. Moreover, since the diameter expansion mechanism can be fitted into the sleeve at a relatively low temperature, the cooling time required for the entire cylinder block material including the sleeve to reach room temperature can be minimized. It can contribute to the improvement of work efficiency.

[Brief description 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 II-II in FIG. 1, and FIG. Figure
IIa-IIa sectional view, FIG. 3 is a perspective view seen from below, FIG. 4 is a perspective view seen from above of the Siamese type cylinder block material, FIG. 5 is a vertical sectional front view when the mold of the casting machine is opened, FIG. 6 is a vertical sectional front view of the casting apparatus when the mold is closed, FIG. 7 is a sectional view taken along line VII-VII of FIG. 6, and FIG. 8 is VIII-VIII of FIG.
FIG. 9 is a perspective view of the sand core seen from above, FIG.
Fig. 0 is a sectional view taken along the line XX in Fig. 9, Fig. 11 is a vertical sectional front view similar to Fig. 6 showing a state in which the sleeve is given the expanding force, and Fig. 12 is giving the expanding force to the sleeve. 7 is a cross-sectional view similar to FIG. 7 showing the state of being opened, and FIG.
XIII-XIII sectional view, FIG. 14 is a graph showing the relationship between time and displacement of the plunger and the relationship between time and pressure of the molten metal,
FIG. 15 is a measurement diagram showing the results of the Talylond measurement of the inner diameter shape of the sleeve of the Siamese type cylinder block material obtained in the casting process of the present invention and the sleeve of the comparative example, and FIG. 16 is manufactured by the present invention. FIG. 17 is a graph showing the relationship between the heating temperature and the expansion amount in the sleeve of the Siamese type cylinder block and the sleeve of the comparative example, and FIG. 17 is an explanatory diagram showing the expansion amount measurement position of the sleeve. Sm ...... Siamese type cylinder block material, ₁ 1 to 1 ₄ ...... cylinder barrel, 3 ...... sleeve

Claims (1)

[Claims] 1. A respective cylinder barrel (1 ₁ to 1 of a plurality of cylinder barrel coupled in series (1 1 _{to 1 4)} aluminum alloy Siamese cylinder barrel made of (1)
₄ ) In the method for producing a Siamese type cylinder block in which a cast iron sleeve (3) is cast into the mold (M), the sleeve (3) is installed in the cavity (C ₁ ) for forming the Siamese cylinder barrel of the mold (M). A casting step of press-filling the cavity (C ₁ ) with a molten aluminum alloy with the mandrel (70) fitted in the sleeve (3) and solidifying the molten metal; After the completion, the cored bar (70) is pulled out from the sleeve (3), and a diameter expansion mechanism (41) is fitted into the sleeve (3) to apply a diameter expansion force to the sleeve (3) and expand the expansion. Cooling the aluminum alloy to a room temperature in a state where a radial force is applied; removing the radial expansion force after cooling, and pulling the radial expansion mechanism (41) out of the sleeve (3); sleeve 3) a step the inner peripheral surface subjected to perfect circle machining; characterized in that it comprises a method for producing a Siamese type cylinder block.