JPS61144258A - Manufacture of siamese-type cylinder block - Google Patents

Abstract

PURPOSE:To make the amount of thermal expansion around the circumference of each sleeve approximately uniform during the running of an engine by filling under pressure a molten metal into a sleeve to be set on a metal mold in a state of providing a radially expanding force to the sleeve, and removing the force after solidifying the molten metal to provide boring work to the inner circumferential surface of sleeve. CONSTITUTION:A holding cylinder 46 is radially contracted by raising an upper mold 9, separating side molds 101, 102 from each other to open the mold, and lowering an actuation rod 50 with the aid of a hollow piston 52 by actuating a hydraulic cylinder 51 to move a taper part 50a downward. Next, the metal mold M is filled with a molten metal under pressure from the sprue 17 of a lower mold 11; in a state of loosely fitting an approximately round cast-iron sleeve 3 to the cylinder 46 radially expanding the cylinder 46 by actuating the cylinder 51 reversely to said operations, and providing a radially expanding force to the sleeve 3. After the molten metal is solidified, said expanding force is removed to open the mold in order to obtain a stock cylinder block, and then the inner circumferential surface of sleeve 3 is subjected to boring work.

Description

[Detailed Description of the Invention] A0 Objective of the Invention +1) Industrial Application Field The present invention relates to a Siamese type cylinder block, particularly a Siamese type cylinder block in which a plurality of cast iron sleeves are cast into a plurality of aluminum alloy cylinder barrels arranged in series. Regarding the manufacturing method.

(2) Conventional technology Conventionally, the Siamese-type cylinder block having the above configuration was produced by installing a sleeve in each cylinder barrel molding cavity of a mold, die-casting the cylinder block material, and then machining the inner peripheral surface of each sleeve into a perfect circle. It is manufactured by applying

(3) Problems to be Solved by the Invention However, according to the above manufacturing method, since the opposing circumferential wall portions of adjacent sleeves are strongly subjected to the filling pressure of molten metal during filling with molten metal, each sleeve has a long axis that is similar to the arrangement of a plurality of cylinder barrels. It is deformed to have a substantially elliptical cross-sectional shape perpendicular to the direction.

In this case, the cross-sectional shape of each cylinder barrel when it contracts as the aluminum alloy solidifies takes on an approximately elliptical shape with its long axis parallel to the direction in which the cylinder barrels are arranged, so each sleeve receives the shrinkage force of the aluminum alloy and It attempts to deform to follow the cross-sectional shape of the cylinder barrel when it contracts, but the deformed shape during filling with molten metal changes only slightly.

Therefore, the cross-sectional shape of each sleeve and the cross-sectional shape of each cylinder barrel have their long axes offset by 90'', and the casting stress remaining in each sleeve becomes uneven on its inner peripheral surface.This state If you assemble and operate an engine with the inner circumferential surface of the sleeve machined into a perfect circle, the amount of thermal expansion on the inner circumferential surface of the sleeve will be uneven, creating a gap between the piston ring and the sleeve, which will cause blow-by gas. There are problems such as increased oil consumption and wasteful consumption of oil.

In view of the above, an object of the present invention is to provide the above-mentioned manufacturing method capable of obtaining a Siamese-type cylinder block in which the amount of thermal expansion on the inner circumferential surface of each sleeve is approximately equalized during engine operation.

B9 Structure of the Invention 1) Means for Solving the Problems The present invention provides pressure filling of molten metal into each cylinder barrel molding cavity of a mold while applying a diameter expanding force to the sleeve installed in the cavity. Then, after the molten metal has solidified, the cylinder block material casting step is performed to remove the diameter expanding force; and the step of machining the inner peripheral surface of the sleeve into a perfect circle is used.

(2) Effect By applying a diameter expanding force to each sleeve when filling the molten metal, deformation of each sleeve due to the filling pressure of the molten metal can be prevented.

After the molten metal has solidified, when the expansion force of each sleeve is removed, each sleeve deforms to follow the cross-sectional shape of the cylinder barrel when it contracts, and the cross-sectional shape of each sleeve has its long axis in the direction of arrangement of the cylinder barrels. It comes to take on an approximately elliptical shape parallel to .

As a result, the casting stress remaining in each sleeve is approximately equalized on its inner circumferential surface, resulting in a good stress balance.

In this state, when the inner circumferential surface of each sleeve is machined into a perfect circle and an engine is assembled and operated, the amount of thermal expansion on the inner circumferential surface of each sleeve becomes approximately equal.

(3) Example Figures 1 to 3 show a Siamese type cylinder block S obtained according to the present invention, which is made of an aluminum alloy having a plurality of cylinder barrels 11 to 14 arranged in series, and the illustrated example has four cylinder barrels 11 to 14. cylinder block body 2 and cylinder bores 3a that are cast into each cylinder barrel II to 14.
It consists of a cast iron sleeve 3 forming a. The cylinder block body 2 includes each cylinder barrel 1. ~1. The cylinder barrel row 4 is an assembly of cylinder barrels 4, and a crankcase 5 is integrally provided at the lower edge of the cylinder barrel row 4. A plurality of communicating lowers in the water jacket 6 toward the cylinder head side are opened at the upper end surface of the cylinder barrel row 4 so as to surround each cylinder bore 3a, and a reinforcing deck portion 8 is provided between adjacent communicating lowers. This causes the cylinder block S
is constructed as a closed deck type.

Figures 5 to 9 show the cylinder block material S shown in Figure 4.
The apparatus is equipped with a mold M, and the mold M is provided with an upper mold 9 which can be raised and lowered, and which is disposed below the upper mold 9. In FIG. 5, the first and second side molds 10 are divided into left and right halves. , iot, and a lower mold 11 on which the molds 10+ and 10t on both sides are slidably placed.

On the lower surface of the upper mold 9, there is a mold clamping recess 1 that cooperates with both side molds io+ and 10g to define a cylinder barrel row molding cavity CI in which each cylinder barrel molding cavity is assembled.
2 is formed, and the mold clamping convex part 1 fits into the concave part 12.
3 is bilateral type 10I.

10□Protrudes from the top surface.

7th. As shown in FIG. 8, the lower die 11 includes a sump 14 that receives molten aluminum alloy from a melting furnace (not shown), and a hot water cylinder 15 that communicates with the sump 14.
and a plunger 16 that is slid onto the hot water cylinder 15.
A pair of runners 17 are formed which branch into two from the sump portion 14 and extend in the longitudinal direction of the cylinder barrel row molding cavity C1 and over approximately the same length. Further, the lower mold 11 has a molding block 18 projecting upward between the two runners 17, and the molding block 18 is connected to the mold 10 on both sides.
．． ．． 10□ to define a crankcase molding cavity C2. The upper end of the cavity C2 communicates with the cylinder barrel row molding cavity CI, 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 18I formed at predetermined intervals, 181 adjacent first molding parts and an outermost brush 1 molding part 18. and a convex-shaped second molding part 8 □ located on the outside of each first molding part 18 . is used to form a rotation space 20 (FIGS. 2 and 3) for the crank pin and crank arm,
The second molded part 18□ is the bearing holder 2 of the crank journal.
1 (Figures 2 and 3).

Each base 19 has a respective second molded portion 18. It is provided to correspond to the above, and the large capacity portion of the crankcase molding cavity C2 is filled with molten metal at an early stage.

Both runners 17 are formed such that the bottom surface of the runners 17 is shaped like several steps ascending from the trough portion 14 side so that the cross-sectional area gradually decreases from the trough portion 14 side toward the runner light 17a. There is. Each rising portion 17c connected to each step portion 17b allows the molten metal to flow into each base 19.
It is formed diagonally so that it can be guided smoothly.

When the cross-sectional area of the runner 17 is reduced in stages in this way,
In areas with large cross-sectional areas, a large amount of molten metal is pumped through the weir 19 at a slow speed.
In addition, in parts with a small cross-sectional area, a small amount of molten metal can be filled into the crankcase molding cavity C2 through the weir 19 at a high speed. The scene rises almost evenly over its entire length,
Therefore, the molten metal causes turbulent flow within the cavity C2.
It is possible to prevent gases such as air 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.

Fifth. As shown in FIG. 6, the top surface of each first molded part IL has a positioning protrusion 2 that fits into the inner circumferential surface of the cast iron sleeve 3.
2 is provided protrudingly, and a recess 2 is provided at the center of the positioning protrusion 22.
3 is formed. Also, two first molded parts 18 located on both sides. , the first molded portion 18 . A pair of temporary installation pins 25 are slid into each of the through holes 24, and these temporary installation pins 25 are used for temporary installation of a sand core for a water jacket. The lower ends of both plate installation bins 25 are fixed to a mounting plate 26 disposed below the molded block 1. Two support rods 27 are inserted through the mounting plate 26, and a coil spring 28 is compressed between the lower part of each support rod 27 and the lower surface of the mounting plate 2-6. 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 2, so that the tip of each temporary installation pin 25 touches the first molded part 18. ．． 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.

Also, two first molded parts 18 located on both sides. , the first molded portion 18. A through hole 29 is formed through the through hole 29, and an operating pin 30 whose lower end is fixed to the mounting plate 26 is slid into the through hole 29. When the mold is opened, the tip of the actuating pin 29 protrudes into the recess 23, and when the mold is closed, it is pushed down by a collet mechanism described later, thereby moving both plate installation pins 25 into the first molding section 18.
゜It is designed to be pulled in from the top surface.

First and second side molds10. ．． Positioning means 31 for actually installing the sand core are provided at two locations on the inner surface of the central portion of the 10□. Each positioning means 31 has a small diameter hole 31a.
and a stepped portion 31b formed on the outer periphery of the opening.

The mold clamping recess 12 of the upper mold 9 is formed with a plurality of overflow cavities C3 and communication port molding cavities C4, which communicate with the cylinder barrel row molding cavities CI, and the upper mold 9 has a plurality of overflow cavities C4 communicating with the cylinder barrel row molding cavities CI. Through holes 32 and 33 communicating with C2 and each communicating molding cavity C4 are formed, respectively.

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

The small diameter portion 3 of each through hole 32, 34 extends upward over a predetermined length from the far end with respect to both cavities C3, C4.
2a, 33a can be fitted with each of the closing pins 34 and 35 to close the overflow cavity Cj and the connecting mouth molding cavity C4, but the diameter of the outside portion thereof is larger than the diameter of each of the closing pins 34 and 35. , thereby creating an air passage 37.3 between each closing pin 34.35 and each through hole 32.33.
8 is formed.

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 causes the mounting plate 3 to
6 and lower each small diameter part 32 by each closing pin 34,35.
a, 33a are opened and closed. 40 is a guide rod of the mounting plate 36.

The upper die 9 is provided with a collet mechanism 41 for holding the sleeve 3 that is cast into each cylinder barrel, ~I4, and the mechanism 41 is configured 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 thereof. The lower surface of the molten metal intrusion prevention plate 45 is provided with the first molding portion 1 of the lower mold 11.
8. A protrusion 45a that can fit into the recess 23 on the top surface is formed.

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. 9, a plurality of slot grooves 49 extending radially from the inner and outer peripheral surfaces of the holding cylinder 46 are formed alternately and at equal intervals on the circumference in the peripheral wall portion of the holding cylinder 46.

A hollow actuating rod 50 for expanding the diameter of the holding cylinder 46 is slidably connected to the supporting rod 43 over substantially the entire length of the supporting rod 43, and the actuating rod 50 is inserted into the tapered hole 4 of the holding cylinder 46.
7, and a true inner portion 50b that is connected to the tapered portion 50a, slides into the through hole 42 of the upper mold 9, and protrudes from the upper mold 9. Tapered part 50
A plurality of pins 57 are provided protrudingly from b, and these pins 57 are inserted into vertically long pin holes 58 of the holding tube 46, thereby allowing the holding tube 46 to move vertically while allowing the tapered portion 50a to move up and down.
rotation will be stopped.

A hydraulic cylinder 51 is fixed to the top surface of the upper mold 9, and a hollow piston rod 53. ．． 53□ passes through the upper end wall and the lower end wall of the cylinder body 54, respectively. The true interior 50b of the actuating rod 50 is inserted into the through hole 55 passing through the hollow piston 52 and the hollow piston rod 53,
A retaining stopper 56 fitted into the annular groove inside 50b thereof
19.56. The hollow piston rod 53. ．． 53! The actuating rod 50 is moved up and down by a hollow piston 52 while in contact with the upper and lower end surfaces of the actuating rod 50, respectively. The collet mechanism 41 is connected to each cylinder barrel 1 of the cylinder block S. 4 aircraft will be installed corresponding to 14.

10th. FIG. 11 shows a sand core 59 for a water jacket, and the sand core 59 has four cylindrical parts 60. 604, and the core body 61 is omitted from the circumferential walls overlapping with each other, and the upper part of the core body 61 is formed to form a communicating lower that communicates the water jacket with the water jacket of the cylinder head. It is composed of a plurality of protrusions 62 protruding from the end face, and positioning protrusions 63 protruding from both outer surfaces of two cylindrical parts 60g and 60s located in the middle of the core body 61. Each positioning protrusion 63 is formed of a large diameter part 63a that is integral with the core body 61 and a small diameter part 63b that projects from the end surface thereof.

Next, a description will be given of the casting operation of the cylinder block material Sm using the casting apparatus.

First, as shown in FIG. 5, the upper mold 9 is raised and the molds IL and 10z are moved apart from each other to open the mold. In the collet mechanism 41, each hydraulic cylinder 51 is operated to lower the operating rod 50 using the hollow piston 52, and the diameter of the holding cylinder 46 is reduced by moving the tapered part 50a downward. The cylinder 39 is actuated to raise the mounting plate 36, thereby communicating the small diameter portion 32 of each closing pin 34.35 with the overflow cavity C1 and the communication port molding cavity C4.
a, detach from 33a. Further, the plunger 16 in the hot water supply cylinder 15 is lowered.

A substantially perfect circular cast iron sleeve 3 is loosely fitted into each holding cylinder 46, the upper end opening of the sleeve 3 is closed by fitting into the convex part 48 of the upper mold 9, and the lower end surface of the sleeve 3 is fitted with a molten metal intrusion prevention plate. The convex portion 45a of 45 is aligned with the lower end surface of the molten metal intrusion prevention plate 45.
The lower end opening of the sleeve 3 is closed. Then, the hydraulic cylinder 51 of the collet mechanism 41 is operated, and the hollow piston 52 raises the operating rod 50. As a result, the tapered portion 50a moves upward, so that the holding tube 46 expands in diameter, and the sleeve 3 is reliably held in the holding tube 46 by receiving the diameter expanding force.

Fifth. As shown in FIG. 11, cylindrical portions 60 on both sides of the sand core 59. ．． The sand core 59 is temporarily installed by engaging the lower edge of the sand core 604 with the recess 25a of each temporary installation pin 25 protruding from the top surface of the first molding part 18I on both sides of the lower mold 11.

Both sides type 10+, tO□ when they approach each other.
Each positioning means 3
The small diameter portion 63b of each positioning protrusion 63 in the sand core 59 is fitted into the small diameter hole 31a of the sand core 59, and the end face of each large diameter portion 63a is abutted against the step portion 31b of each positioning means 31. The child 59 is accurately positioned and the both side walls 10. ．． 10
□ and perform the final installation of the sand core 59.

As shown in FIG. 6, the upper mold 9 is lowered and each sleeve 3 is
each cylindrical part 60 of the sand core 59. 604, and the convex portion 45a of the molten metal intrusion prevention plate 45 is fitted into the concave portion 23 on the top surface of the first molded portion 18I. As a result, the molten metal intrusion prevention plate 45
Since the operating pin 30 is pushed down by the convex portion 45a, each temporary installation pin 24 is lowered and retracted from the top surface of the first molded portion 181.

Moreover, the mold clamping recess 12 of the upper mold 9 is a double-sided type IL.

The mold clamping is performed by fitting into the mold clamping convex portion 13 of 108.

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 the two runners 17 to the lower edge of the crankcase molding cavity C2 and into the cavity. C! and fills the cylinder barrel row molding cavity CI. Gas such as air in both cavities C, , C, is pushed up by the molten metal and is passed through an air passage 37.3 that communicates with the overflow cavity C3 and the communication port molding cavity C4.
8 and exits above the upper mold 9.

In this case, both runners 17 are formed in the shape of several steps ascending from the trough portion 14 side so that the cross-sectional area of both runners 17 gradually decreases toward the runner light 17a, as described above. As the plunger 16 rises, the molten metal flows from both runners 17 to each base 1.
9, from the lower ends of both sides of the crankcase molding cavity C2, approximately evenly over the entire length of the cavity C2.
The inside can be pushed up smoothly. Therefore, the molten metal does not cause turbulent flow within the cavities C, , C, and gases such as air are prevented from being drawn into the molten metal, thereby avoiding the formation of cavities.

When each overflow cavity C5 and each communication port forming cavity C4 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 both cavities C3. ,C4
The small diameter portions 32a and 33a that communicate with the are closed.

In the pouring operation, the displacement of the plunger 16 and the pressure of the molten metal for filling the crankcase molding cavity C2 and the cylinder barrel row molding cavity CI with molten metal are controlled as shown in FIG.

That is, the plunger 16 changes its moving speed to the first to third speeds V.
, ~V3. In this embodiment, the first speed V
, is 0.08 to 0.3 m/sec, 2nd speed ■2 is 0
．． 14 to 0.18 m/sec, and the third speed V is set to 0.04 to 0.08 m/sec to achieve a significant deceleration state, and this three-stage speed control prevents waving of the molten metal. to form a quiet molten metal flow that does not involve gas such as air, and transfer the molten metal to both cavities Ct.
, Ct can be filled efficiently.

In addition, at the first speed vI of the plunger 16, the molten metal flows through both runners 1
7 etc., the pressure P of the molten metal is kept approximately constant, and the second and third speeds V, , V, of the plunger 16
Then, since the molten metal fills both cavities C1 and C2, the pressure P2 of the molten metal rises rapidly. 3rd plunger 16
After moving at speed 3 for a predetermined time, the filling pressure P of the molten metal is maintained at 150 to 400 kg/ad for about 1.5 seconds, thereby completely enveloping the sand core 59 with the molten metal and applying it to its surface. Produces a molten metal solidification film.

After the above-mentioned time has elapsed, the plunger 16 is moved to the speed V4.
Since the molten metal is moved at a reduced speed, the pressure P4 of the molten metal increases, and when the pressure P% reaches 200 to 600 kg/aa, the movement of the plunger 16 is stopped and the molten metal is solidified in this state.

When a molten metal coagulation film is formed on the surface of the sand core 59 by moving the plunger at a reduced speed and keeping the pressure of the molten metal constant for a predetermined period of time as described above, the sand core 59 will be solidified by the film when pressurizing the molten metal next time. Protected and undamaged.

In addition, since the sand core 59 is held in an accurate position by the two-sided molds TO+ and Ioz through each of its positioning protrusions 63, the sand core 59 is held in an accurate position by the two-sided molds TO+ and Ioz, so that when filling the cylinder barrel row molding cavity CI with molten metal and the cavity C1. The sand core 59 does not float up when the molten metal inside is pressurized, and the end face of the large diameter portion 6'3a of each positioning protrusion 63 is a step of the positioning means 31 in the double-sided type 1° 1.10 □. 31b, the pressure of the molten metal acting on the sand core 59 is transmitted through the end face of the large diameter portion 63a of each positioning protrusion 63 to the side mold 10. ．． 10□, thereby preventing deformation of the sand core 59 and providing a cylinder barrel row 4 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 type cylinder block material can be cast with substantially the same production efficiency as die casting.

After the molten metal has completely solidified, the hydraulic cylinder 51 of the collet mechanism 41 is operated, the operating rod 5o is lowered to remove the diameter expansion force of the holding cylinder 46 against the sleeve 3, and the mold is opened, as shown in FIG. A cylinder block material Sm is obtained.

In this cylinder block material Sm, Fig. 13 (
As shown in the results of the Kryrod measurement (100 times magnification) in a), the cross-sectional shape of each sleeve 3 has a long axis extending from the cylinder barrel 11 to
It has a substantially elliptical shape parallel to the arrangement direction of cylinder barrels II to 14, and this matches the cross-sectional shape of each cylinder barrel II to 14 when contracted.

The reason why such a result is obtained is that the collet mechanism 41 applies diameter expansion force to each sleeve 3 when filling the molten metal, which prevents each sleeve 3 from deforming due to the filling pressure of the molten metal and prevents the molten metal from solidifying. After the expansion force of each sleeve 3 is removed, each sleeve 3 is connected to each cylinder barrel II.
This is because it deforms so as to follow the cross-sectional shape at the time of contraction of 14.

As a result, the casting stress remaining in each sleeve 3 is approximately equalized over its entire circumference.

In the thirteenth (b), a perfectly circular sleeve 300 is attached to the cylinder barrel 100 without using the collet mechanism 41. Figures 1004 and 1004 show the results of Kryrod measurements of a Siamese-type cylinder block material as a comparative example obtained by casting. Particularly between adjacent cylinder barrels, the opposing circumferential walls of both sleeves 300 receive the filling pressure of the molten metal and form a concave portion 300a.

FIG. 14(a) shows the degree of balance of casting stress remaining in each sleeve 3 in the cylinder block material Sm obtained by the present invention, and a perfect circle C indicates the zero point of casting stress. From this figure, in the material Sm, each sleeve 3
It is clear that a good balance is maintained over the entire circumference.

FIG. 14(b) shows each sleeve 300 in the comparative example.
It shows the degree of balance of casting stress remaining in the figure, and there is a peculiar tendency between adjacent cylinder barrels, resulting in poor balance.

After the measurement, the cylinder block material Sm obtained according to the present invention is subjected to a grinding process to form a molding cavity C4 on each consecutive day.
By removing the protrusions 64 formed by the cooperation of the protrusions 62 of the sand core 59, the communicating lowers are formed, and by removing the sand, the water jacket 6 is obtained.
Further, the inner circumferential surface of each sleeve 3 is machined into a perfect circle, and other predetermined processes are performed to obtain the cylinder block S shown in FIGS. 1 to 3.

A cylinder block of a comparative example is also obtained by applying the same processing.

FIGS. 15(a) and 15(b) show changes in the inner diameters of both sleeves 3, 300 as expansion amounts when both cylinder blocks are uniformly heated. The amount of expansion was measured at four points a on the circumference as shown in Figure 16.

The change in inner diameter at ~a4 was determined.

FIG. 15(a) shows the case of the cylinder block S obtained according to the present invention, in which the difference D1 between the maximum expansion amount and the minimum expansion amount at around 190'', which is the heating temperature of the cylinder block during engine operation, is 20μ. Each small point a, “wa4
There is little variation in the amount of expansion. Moreover, these expansion amounts are close to the theoretical expansion amount T. This is due to the well-balanced casting stress remaining in each sleeve 31 as described above.

FIG. 15(b) shows the case of a comparative example, in which the difference D2 between the maximum expansion amount and the minimum expansion amount at the same temperature as above is 128μ.
Large variations can be seen in the amount of expansion at each point a to a4. Moreover, among those expansion amounts, 3 points aZ + a
Those at 3 + aa are separated by a larger distance than the theoretical expansion amount T. This is due to the poor balance of casting stress remaining in each sleeve 300 as described above.

C3 Effects of the Invention According to the present invention, molten metal is pressurized and filled into each cylinder barrel molding cavity of the mold while applying a diameter expanding force to the sleeve, so that each cylinder barrel molding cavity of the mold is filled with molten metal under pressure. Deformation of the sleeve is prevented. Then, after the molten metal has solidified, the diameter expansion force is removed, so that each sleeve deforms to follow the cross-sectional shape of each cylinder barrel when it contracts, and as a result, the casting stress remaining in each sleeve is transferred to its inner circumferential surface. The stress is approximately equalized in the process, resulting in a good balance of stress.

After that, the inner circumferential surface of each sleeve is machined into a perfect circle, so that the amount of thermal expansion on the inner circumferential surface of each sleeve is approximately equal during engine operation, and as a result, gaps between the piston ring and the sleeve are minimized. This can solve problems such as increased blow-by gas and wasteful oil consumption.

Additionally, since each sleeve does not deform due to the filling pressure of molten metal, it is possible to make the spacing between adjacent sleeves as close as possible, which allows the cylinder block, and therefore the entire engine, to be made smaller and lighter. be able to.

[Brief explanation of the drawing]

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 line nn in FIG. Figure 4 is a perspective view of the Siamese-type cylinder block material seen from above, Figure 5 is a vertical front view of the casting machine when the mold is opened, and Figure 6 is a vertical front view of the casting machine when the mold is closed. Figure 7 is a sectional view taken along line nn of Figure 1, Figure 8 is a sectional view taken along line nn of Figure 1, Figure 9 is a sectional view taken along line nn of Figure 1,
The θ diagram is a perspective view of the sand core seen from above, and Figure 11 is the 10th diagram.
Figure 12 is a graph showing the relationship between the displacement of the plunger with respect to time and the pressure of molten metal with respect to time. Fig. 14 (a) is a measurement diagram showing the results of Kryrod measurements on the inner diameter shape of the sleeve in the Siamese type cylinder block material and comparative example.
, (bl is an explanatory diagram showing the balance of casting stress remaining in the Siamese type cylinder block material obtained in the casting process of the present invention and the sleeve in the comparative example, No. 15
Figure (a). (b) is a graph showing the relationship between the expansion amount and the heating temperature of the sleeve in the Siamese type cylinder block manufactured by the present invention and a comparative example, and FIG. 16 is an explanatory diagram showing the measurement position of the expansion amount of the sleeve. CI...Cylinder barrel row molding cavity which is a collection of cylinder barrel molding cavities, M...Mold, S
...Cylinder block, Sm...Cylinder block material, 11-14...Cylinder barrel, 3...Sleeve procedure official document (method) March 19, 1985

Claims (1)

[Claims] In a method for manufacturing a Siamese-type cylinder block in which a plurality of cast iron sleeves are cast into a plurality of aluminum alloy cylinder barrels arranged in series, the diameter of the sleeves installed in each cylinder barrel molding cavity of a mold is enlarged. A cylinder block material casting process in which molten metal is pressurized and filled into the cavity under force, and then the diameter expansion force is removed after the molten metal has solidified; A method for manufacturing a Siamese type cylinder block, comprising: a step of applying;