JP2008223699A - Cylinder sleeve and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder sleeve in which joining strength between a cylinder block and the cylinder sleeve is ensured and the abrasion resistance of an inner peripheral wall is excellent. <P>SOLUTION: First, an outer cylindrical body 14 formed of an Al-Si-based alloy with a comparatively small difference in the coefficient of linear expansion from the cylinder block, for example, an ADC 12. Next, after a predetermined time elapses, and preferably, the temperature of the outer cylindrical body 14 becomes lower than a liquid phase-solid phase line in a phase diagram, an inner cylindrical body 12 is formed in a manner that molten metal L2 is introduced to the side of the inner peripheral wall of the outer cylindrical body 14 while continuously rotating a cylindrical die 22. The outer cylindrical body 14 functions as a cooling metal (a chiller) when the molten metal L2 is cooled and solidified. As the molten metal L2, for example, an Al-17 to 23% Si-based alloy is selected which is excellent in abrasion resistance in comparison with the Al-Si-based alloy forming the outer cylindrical body 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylinder sleeve disposed in a bore of a cylinder block constituting an internal combustion engine and a method for manufacturing the same.

  In an internal combustion engine that is a drive source for running an automobile, a cylinder sleeve may be disposed in the cylinder bore. In this case, the side peripheral wall portion of the piston that reciprocates within the cylinder bore is in sliding contact with the inner peripheral wall of the cylinder sleeve.

  The cylinder sleeve may be manufactured by a so-called centrifugal casting method. That is, when the molten metal is introduced into the rotating cylindrical mold, the molten metal is unevenly distributed on the inner peripheral wall of the cylindrical mold by centrifugal force, and a cylindrical body is formed. A cylinder sleeve is obtained by cooling and solidifying the molten metal in this state. At this time, a so-called spiny is formed on the outer peripheral wall of the cylinder sleeve by transferring the irregular shape formed on the surface of the coating material.

  After the cylinder sleeve is arranged at a predetermined position of the mold, a molten metal is poured into the mold and cooled and solidified (that is, when casting is performed), thereby providing a cylinder block in which the cylinder sleeve is cast. . At this time, the spiny, the undulations (for example, groove-like streaks) provided on the outer peripheral wall of the cylinder sleeve by machining such as cutting, the irregularities provided on the outer peripheral wall of the cylinder sleeve by shot blasting, etc. By functioning as an anchor, the joining strength between the cylinder block and the cylinder sleeve is ensured.

  In recent years, an Al-Si alloy is increasingly selected as a material for this type of cylinder sleeve because it is lightweight but has excellent wear resistance and high strength. Also, the case where aluminum or an alloy thereof is selected as the material of one cylinder block is increasing.

  Here, the molten metal for providing the cylinder block is prepared to have a composition with good hot-rollability so that the casting operation proceeds smoothly. However, this composition does not necessarily coincide with a composition for developing excellent wear resistance in the cylinder sleeve. Due to the difference in composition, the linear expansion coefficients of the cylinder block and the cylinder sleeve are different from each other.

  When the linear expansion coefficients are significantly different, when the molten metal is cooled and solidified when casting the cylinder block, it may not be easy to ensure sufficient bonding strength even if the anchor effect is caused by spiny. Therefore, in Patent Document 1, it is proposed that the outer peripheral wall of the cylinder sleeve is provided with a projection larger than the spiny in order to improve the bonding strength. According to Patent Document 2, it is effective to improve the joining strength by coating the outer peripheral wall of the cylinder sleeve with a low melting point alloy.

Japanese Patent No. 3866636 JP 2006-43708 A

  Regardless of the prior art as described above, it is desired to improve the joining strength between the cylinder sleeve and the cylinder block by a simpler operation. Further, when a cylinder sleeve made of an Al-Si alloy is produced by centrifugal casting, there is a problem that the amount of primary Si that improves wear resistance is reduced on the inner peripheral wall side where the wear resistance is most required. Further, in order to improve the strength of the cylinder sleeve, it is necessary to refine the primary crystal Si. However, in Patent Documents 1 and 2, the primary crystal Si is dispersed almost uniformly in the cylinder sleeve, A measure for reducing the crystal Si is not disclosed.

  The present invention has been made to solve the above-described problems, and can be reliably bonded to the cylinder block by a simple operation, and fine primary crystal Si is dispersed substantially evenly. It is an object of the present invention to provide a cylinder sleeve having an inner peripheral wall excellent in wear resistance and a method for manufacturing the same.

In order to achieve the above object, the present invention provides a cylinder sleeve disposed in a bore of a cylinder block constituting an internal combustion engine,
Having the outer cylindrical body and the inner cylindrical body in this order from the outer periphery side,
The inner cylindrical body and the outer cylindrical body are different types of Al—Si alloys.

  In the present invention, the characteristics are different based on the fact that materials are different between the outer peripheral side and the inner peripheral side. Therefore, it is possible to deal with applications in which characteristics required for the outer peripheral side and the inner peripheral side are different.

  Specifically, it is desired that the inner peripheral wall of the cylinder sleeve has good wear resistance. This is because the piston is in sliding contact with the inner peripheral wall. Therefore, it is preferable that the Al—Si based alloy forming the inner cylindrical body has higher wear resistance than the Al—Si based alloy forming the outer cylindrical body.

Further, the material of the outer cylindrical body preferably has a difference in linear expansion coefficient from the material forming the cylinder block within 3 × 10 ⁻⁶ / ° C. By selecting materials having similar linear expansion coefficients as the material of the cylinder block and the outer cylindrical body in this way, it becomes easy to ensure the bonding strength with the cylinder block.

  And it is preferable that the unevenness | corrugation is formed in the outer peripheral wall of an outer side cylindrical shape body. This is because the unevenness exhibits a so-called anchor effect, and as a result, the bonding strength with the cylinder block is further improved.

Further, the present invention is a method for manufacturing a cylinder sleeve disposed in a bore of a cylinder block constituting an internal combustion engine,
Supplying a first molten Al-Si alloy to a rotating cylindrical mold and providing an inner cylindrical body by centrifugal casting;
While rotating the cylindrical mold, a second molten metal different from the first molten metal is supplied to the inside of the first layer to provide an outer cylindrical body by centrifugal casting, A step of making a laminated preform, and
Cutting out from the inner peripheral wall side of the preform,
It is characterized by having.

  By passing through the above-described steps, cylinder sleeves having different characteristics on the inner peripheral side and the outer peripheral side can be manufactured.

  Moreover, in the present invention, when the inner cylindrical body is provided, the outer cylindrical body functions as a chiller (chiller), so the cooling rate of the second molten metal is increased. That is, the molten metal solidifies before the primary crystal Si grows large or moves to the outer cylindrical body side. Accordingly, an inner cylindrical body having a structure in which fine primary crystal Si is dispersed substantially uniformly is obtained.

  In addition, in the present invention, a cylinder sleeve having different characteristics on the outer peripheral side and the inner peripheral side can be easily manufactured only by performing a very simple operation of supplying another type of molten metal during centrifugal casting.

  When obtaining a cylinder sleeve having a large wear resistance on the inner peripheral wall, a molten Al-Si alloy having higher wear resistance than the Al-Si alloy of the first molten metal is used as the second molten metal. Good.

Further, in order to ensure the bonding strength with the cylinder block, the first molten metal having a difference in linear expansion coefficient from the material forming the cylinder block within 3 × 10 ⁻⁶ / ° C. should be used. Good.

  According to the present invention, since the materials of the outer cylindrical body and the inner cylindrical body are different types of Al-Si alloys, for example, the material capable of ensuring the bonding strength with the cylinder block is the outer peripheral side. In addition, it is possible to provide a cylinder sleeve suitable for applications in which characteristics required for the outer peripheral side and the inner peripheral side are different, for example, a material having excellent wear resistance is used on the inner peripheral side.

  Moreover, in the inner cylindrical body, fine primary crystal Si is dispersed substantially evenly. That is, according to the present invention, it is also possible to constitute a cylinder sleeve having an inner cylindrical body having a structure in which fine primary crystal Si is substantially uniformly dispersed, and the characteristics are substantially the same throughout. Is possible.

  Hereinafter, preferred embodiments of a cylinder sleeve and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic overall perspective view of a preformed body 10 for providing a cylinder sleeve according to the present embodiment. This preform 10 is a laminated body in which an inner cylindrical body 12 and an outer cylindrical body 14 are laminated.

  In this case, the inner cylindrical body 12 is an Al-17 to 23% Si-2.5% Cu alloy (numbers are% by weight, the same applies hereinafter), that is, an A390 equivalent material (Al-17% alloy) or AC9A equivalent. It is made of a material (Al-23% alloy) and, as will be described later, is a casting provided by cooling and solidifying the molten metal. The thickness T1 is set to about 5 to 6 mm.

  In this inner cylindrical body 12, fine primary crystal Si having an average particle size of 35 μm or less is distributed substantially uniformly along the diameter direction without being unevenly distributed on the outer peripheral wall side (outer cylindrical body 14 side). . In addition, the grain size distribution width of primary Si is small. In other words, the microstructure of the inner cylindrical body 12 is in a state where the fine primary crystals Si having substantially the same dimensions are uniformly dispersed.

  On the other hand, the outer cylindrical body 14 is a cast product made of an Al-11% Si-2.5% Cu-based alloy (ADC12). That is, the outer cylindrical body 14 is also provided by cooling and solidifying the molten metal, and its inner peripheral wall is joined to the outer peripheral wall of the inner cylindrical body 12. In addition, the suitable thickness T2 of the outer cylindrical body 14 is in the range of 0.5 to 2.0 mm.

  When the cylinder sleeve is manufactured from the preformed body 10 configured as described above, cutting is performed from the inner peripheral wall side of the preformed body 10, that is, from the inner cylindrical body 12. In other words, the inner cylindrical body 12 is thinned to a predetermined thickness. Thus, the inner cylindrical body 12 is provided as a machining allowance for the preformed body 10.

  As described above, in the inner cylindrical body 12, primary crystal Si that is fine and has substantially the same size as each other is uniformly dispersed along the diameter direction. For this reason, in the preformed body 10 after processing, that is, the cylinder sleeve, excellent wear resistance also appears on the inner peripheral wall with which the piston slides. In addition, it has high strength throughout. Therefore, the internal combustion engine incorporating this cylinder sleeve shows excellent durability.

  Next, this cylinder sleeve manufacturing method will be described by exemplifying a case where the centrifugal casting apparatus 20 shown in FIG. 2 is used.

  The centrifugal casting apparatus 20 includes a cylindrical mold 22 that is lying along a substantially horizontal direction. Two annular grooves 24, 24 are provided on the outer peripheral wall of the cylindrical mold 22 so as to cut out the outer peripheral wall along the circumferential direction, and at the bottom of each of the annular grooves 24, 24. Are in sliding contact with the outer peripheral walls of the rollers 26 and 26 forming a roller pair. That is, the cylindrical mold 22 is supported by two pairs of rollers.

  The four rollers 26 are connected to a rotational drive source (not shown). Therefore, the cylindrical mold 22 rotates as each of the rollers 26 rotates under the action of the rotational drive source.

  A disc-shaped closing member 30 is fitted to one end of the cylindrical mold 22, while an annular frame 32 is attached to the other end. The annular frame 32 is opened by being provided with a through hole 34, and a pouring pipe 38 of the first trough 36 or a pouring pipe 42 of the second trough 40 is formed through the through hole 34 in a cylindrical mold. 22 is inserted into the interior.

  The main body of the first trough 36 accommodates a melt L1 of the ADC 12 for providing the outer cylindrical body 14. A tiltable first pot 44 is disposed in the vicinity of the first trough 36, and the molten metal L <b> 1 is supplied to the first trough 36 through the first pot 44.

  On the other hand, the main body of the second trough 40 accommodates a molten metal L2 for providing the inner cylindrical body 14. Similarly to the above, a second pot 46 that is tiltable is also provided in the vicinity of the second trough 40, and the molten metal L <b> 2 is supplied from the second pot 46 toward the second trough 40.

  When manufacturing the preform 10 to be the cylinder sleeve, first, the molten metal L1 of the ADC 12 prepared in the melting furnace is transferred to the first pot 44, and further, the first pot 44 is tilted. It is moved to the main body of the first trough 36. On the other hand, a coating material is applied to the inner peripheral wall of the cylindrical mold 22, and then, as shown in FIG. 3, the pouring pipe 38 of the first trough 36 is connected to the cylindrical mold 22 through the through hole 34. Inserted inside. Although the pouring pipe 42 of the second trough 40 is not shown in FIG. 3, the pouring pipe 42 may be arranged at a position where it does not interfere with the first trough 36.

  In this state, the rotation of the roller 26 is started, and the cylindrical mold 22 is rotated following the rotation. Thereafter, a predetermined amount of the molten metal L1 of the ADC 12 is supplied to the inside of the cylindrical mold 22 through the first trough 36 and flows along the longitudinal direction of the cylindrical mold 22. Further, the molten metal L1 is unevenly distributed on the inner peripheral wall of the cylindrical mold 22 so as to form a cylindrical body by the action of centrifugal force, thereby forming the outer cylindrical body 14. Here, in the present embodiment, the molten metal L1 is supplied in such an amount that the thickness of the outer cylindrical body 14 is in the range of 0.5 to 2.0 mm.

  While the outer cylindrical body 14 is formed in this way, the spiny of the coating material is transferred to the outer peripheral wall of the outer cylindrical body 14.

  Meanwhile, the molten metal L2 of A390 equivalent material (Al-17% alloy) or AC9A equivalent material (Al-23% alloy) prepared in the melting furnace is transferred to the second pot 46. Then, a predetermined time required for the temperature of the outer cylindrical body 14 to be equal to or lower than the liquidus-solidus temperature in the state diagram, for example, immediately after 8 to 25 seconds is suitably passed under certain conditions (in other words, For example, immediately after the temperature of the outer cylindrical body 14 becomes equal to or lower than the liquid-solidus temperature in the state diagram), the second pot 46 is tilted to move the molten metal L2 to the main body of the second trough 40. Following this, as shown in FIG. 5, the molten metal L <b> 2 is introduced into the cylindrical mold 22 through the pouring pipe 42 of the second trough 40. The introduced molten metal L2 expands to the disk-shaped closing member 30 side due to its fluidity. Of course, while the molten metal L2 is introduced, the rotating operation of the cylindrical mold 22 is continued.

  The molten metal L2 is unevenly distributed so as to be attached to the inner peripheral wall of the outer cylindrical body 14 by centrifugal force, whereby the inner cylindrical body 12 is formed as shown in FIG. As a result, the preformed body 10 is obtained in which the outer cylindrical body 14 is laminated outside the inner cylindrical body 12 and the inner peripheral wall of the outer cylindrical body 14 is joined to the outer peripheral wall of the inner cylindrical body 12.

  When the inner cylindrical body 12 is cooled and solidified, the outer cylindrical body 14 functions as a chiller. For this reason, in this Embodiment, the cooling rate of the molten metal L2 becomes large compared with general centrifugal casting. That is, since the molten metal L2 is solidified before the primary crystal Si grows greatly, a fine structure of the primary crystal Si is obtained. The average grain size of primary crystal Si is approximately 35 μm or less.

  Further, since the cooling rate is high, solidification occurs before Si in the molten metal L2 moves to the outer peripheral wall side by centrifugal force. Accordingly, uneven distribution of primary Si is suppressed, and the primary crystal Si is distributed substantially uniformly along the diameter direction of the inner cylindrical body 12. In this way, by making the outer cylindrical body 14 function as a chiller, it is possible to obtain the inner cylindrical body 12 in which primary crystal Si having fine and substantially the same dimensions are uniformly dispersed.

  Next, after removing the annular frame 32 from one end of the cylindrical mold 22, the preformed body 10 in which the inner cylindrical body 12 and the outer cylindrical body 14 are joined is pulled out from this end side. Take out with the mold material. Thereafter, the coating material adhering to the outer peripheral wall of the outer cylindrical body 14 is removed by shot blasting or the like, and further, a cutting process for removing a predetermined amount of machining allowance from the inner peripheral wall side of the inner cylindrical body 12 is performed. A cylinder sleeve including the inner cylindrical body 12 in which the primary crystal Si is dispersed substantially uniformly is obtained.

  When the inner cylindrical body 12 is provided by centrifugal casting, the primary crystal Si is slightly unevenly distributed on the outer cylindrical body 14 side, and the primary crystal is located on the inner side (the inner peripheral wall side of the inner cylindrical body 12) in the diameter direction. Even if the amount of Si is slightly reduced, as described above, since the cutting is performed from the inner peripheral wall side of the preformed body 10, a portion with a small amount of Si is removed as a machining allowance. Eventually, a cylinder sleeve with a sufficient amount of primary Si can be obtained.

  As described above, according to the present embodiment, a cylinder sleeve having high strength and excellent wear resistance can be produced.

  In the present embodiment, the outer cylindrical body 14 is made to function as a chiller to refine the primary crystal Si, so that the casting conditions such as the rotational speed and temperature of the cylindrical mold are strictly controlled. There is no need to do.

  The cylinder sleeve thus obtained is arranged in a cavity of a casting mold for casting a cylinder block constituting an internal combustion engine for automobiles. And the molten metal used as a cylinder block is introduced with respect to this cavity.

  In this case, aluminum or Al-9% Si-3% Cu alloy (ADC10 to ADC12) is selected as the molten metal. Since the linear expansion coefficient of aluminum, ADC 10 or ADC 12 is substantially the same as the linear expansion coefficient of ADC 12 which is the material of the outer cylindrical body 14, the cylinder sleeve is used when the molten metal is introduced and when the molten metal is cooled and solidified. The cylinder block expands and contracts to approximately the same extent. Therefore, a sufficient bonding strength is secured between the cylinder sleeve and the cylinder block by the spine anchor effect transferred to the outer peripheral wall of the outer cylindrical body 14. The Eventually, a cylinder sleeve is cast in the cylinder block, thereby forming an internal combustion engine.

  In the internal combustion engine, the piston is in sliding contact with the inner peripheral wall of the cylinder sleeve. The inner peripheral wall of this cylinder sleeve is the inner cylindrical body 12 made of an A390 equivalent material or an AC9A equivalent material rich in primary Si as described above, and therefore has extremely high wear resistance. For this reason, it is excellent in durability.

  As described above, according to the present embodiment, it is possible to configure a cylinder sleeve that has high bonding strength with the cylinder block and good wear resistance of the inner peripheral wall with which the piston slides.

  A centrifugal casting apparatus 50 as shown in FIG. 7 may be configured, and the inner cylindrical body 12 may be provided by introducing the molten metal L2 into the cylindrical mold 22. Hereinafter, this embodiment will be described.

  In this case, a pouring pipe 52 is passed through the through hole 34 of the annular frame 32. In other words, the pouring pipe 52 is inserted into the cylindrical mold 22 through the through hole 34.

  The pouring pipe 52 is surrounded by four bar heaters 54. That is, each of the first sandwiching plate 56, the first penetration support plate 58, the second penetration support plate 60, and the second sandwiching plate 62 in which the pouring pipes 52 are passed through the respective central through holes, The rod 52 is positioned and fixed in this order from the distal end side of the tube 52, and both end portions of each bar heater 54 are sandwiched between the first sandwiching plate 56 and the second sandwiching plate 62 therein. Moreover, the 1st penetration support plate 58 and the 2nd penetration support plate 60 are supporting the middle part by letting each rod-shaped heater 54 pass to the small through-hole formed in the circumference | surroundings of the said center through-hole. .

  As shown in FIG. 8, the pouring pipe 52 is connected to a molten metal holding furnace 66 through a supply pipe 64. That is, the supply pipe 64 is formed by connecting a flexible tube 68 connected to the pouring pipe 52 and an inverted L-shaped pipe 70 extending from the molten metal holding furnace 66 and having a substantially inverted L shape to each other, A bridge is formed from the pouring pipe 52 to the molten metal holding furnace 66.

  On the other hand, wheels 72 are provided on the bottom surface of the molten metal holding furnace 66, and each wheel 72 is slidably engaged with a guide rail 74 laid on the floor of the work station. That is, the molten metal holding furnace 66 is displaced along the guide rail 74 when the wheel 72 rotates.

  A heat insulating material 76 is accommodated inside the molten metal holding furnace 66, and a molten metal container 78 is inserted so as to be surrounded by the heat insulating material 76. An immersion heater (not shown) is inserted into the molten metal container 78, and the molten metal L2 of A390 equivalent material or AC9A equivalent material stored in the molten metal container 78 is heated by the immersion heater and It is kept warm by the heat insulating material 76.

  In addition, an opening for introducing the molten metal is provided in a part of the upper end portion of the molten metal container 78, and the opening is sealed with a lid member 80.

  The lid member 80 is provided with two through-holes, and one of them is passed through the inverted L-shaped tube 70 constituting the supply tube 64 as described above. The tip of the inverted L-shaped tube 70 is immersed in the molten metal L2. In addition, a gas introduction pipe 82 connected to an argon gas supply source (not shown) is passed through the remaining one, and the gas introduction pipe 82 is slightly separated from the liquid surface of the molten metal L2.

  When manufacturing the preform 10 with the centrifugal casting apparatus 50 configured as described above, first, a coating material is applied to the inner peripheral wall of the cylindrical mold 22. Thereafter, the rotation of the roller 26 is started, and the cylindrical mold 22 is rotated following the rotation. In the same manner as described above, the molten metal L1 of the ADC 12 is supplied from the pouring pipe 38 of the first trough 36 inserted into the cylindrical mold 22 through the through hole 34. The pouring pipe 38 of the first trough 36 moves backward to the outside of the cylindrical mold 22 after a predetermined amount of the molten metal L1 is supplied.

  Next, immediately after the temperature of the outer cylindrical body 14 becomes equal to or lower than the liquid-solidus temperature in the state diagram in accordance with the above, argon gas (inert gas) is supplied from the argon gas supply source, and the gas After passing through the introduction pipe 82, it is discharged into the molten metal container 78 constituting the molten metal holding furnace 66.

  In the molten metal container 78, the molten metal L2 is pressed by argon gas. When the pressure of the argon gas further rises, the molten metal L <b> 2 moves up the inverted L-shaped tube 70, passes through the flexible tube 68, and reaches the pouring tube 52. As described above, in the present embodiment, the molten metal L2 is pressed with the inert gas so that the liquid is transferred from the molten metal holding furnace 66 to the cylindrical mold 22, so that it is difficult to entrain the atmosphere. Active gas is also difficult to entrain.

  As shown in FIG. 9, the pouring pipe 52 is inserted into the cylindrical mold 22 until the tip thereof is positioned in the vicinity of the disc-like closing member 30. For this reason, the molten metal L2 is led out in the vicinity of the disk-shaped closing member 30, and then flows toward the annular frame 32 side.

  While the molten metal L2 is being led out, the rotating operation of the cylindrical mold 22 is continued. For this reason, as shown in FIG. 10, the molten metal L2 is unevenly distributed on the inner peripheral wall of the outer cylindrical body 14 by the action of centrifugal force to form the inner cylindrical body 12. Prior to the introduction of the molten metal L2, the rod heater 54 is heated in advance. What is necessary is just to set the total calorific value of the rod-shaped heater 54 to about 30 kW, for example.

  In this case, the molten metal L2 is supplied in such an amount that the final thickness of the preform 10 is in the range of 5 to 6 mm. As a result, the clearance between the rod heater 54 and the inner peripheral wall of the preform 10 is about 5 mm. It becomes. As described above, even if the molten metal L entrains the atmosphere or other gas, the amount thereof is extremely small, so that bubbles (internal defects) are hardly generated in the preform 10. In addition, when the clearance is 5 mm, the present inventors have confirmed that the amount of entrainment is extremely small.

  Next, the molten metal L <b> 2 is cooled and solidified while the pouring pipe 52 stays inside the cylindrical mold 22. As described above, since the rod heater 54 is heated in advance, the inner peripheral wall of the inner cylindrical body 12 is heated by the rod heater 54 during cooling and solidification. On the other hand, the outer peripheral wall of the inner cylindrical body 12 is in contact with the outer cylindrical body 14 solidified first. Therefore, the cooling rate in the inner cylindrical body 12 is larger on the outer peripheral wall side and smaller on the inner peripheral wall side.

  Even if argon gas is entrained in the molten metal L2 due to such a thermal gradient in the inner cylindrical body 12, even if bubbles are generated, the bubbles are solidified at a lower cooling rate than the outer peripheral wall side. It can move to the inner wall side, which takes time.

  On the other hand, since the cooling rate is large on the outer peripheral wall side, the primary crystal Si is prevented from growing and coarsening. That is, according to the present embodiment, it is possible to obtain the inner cylindrical body 12 in which fine primary crystal Si is dispersed on the outer peripheral wall side and defects are concentrated on the inner peripheral wall side.

  Next, a force is applied to the molten metal holding furnace 66, whereby the molten metal holding furnace 66 is displaced along the guide rail 74 in a direction away from the cylindrical mold 22. Of course, at this time, the wheel 72 provided on the bottom surface of the molten metal holding furnace 66 rotates.

  Following the displacement of the molten metal holding furnace 66 described above, the pouring pipe 52 and the rod heater 54 are led out of the cylindrical mold 22. The molten metal holding furnace 66 is finally displaced to the molten metal replenishment station, and the molten metal L is replenished to the molten metal container 78 after the displacement is stopped.

  Next, after removing the annular frame 32 from one end of the cylindrical mold 22, the preformed body 10 is pulled out from this end and taken out together with the coating material. Thereafter, the outer peripheral wall of the preform 10 is subjected to shot blasting or the like to remove the coating material. Further, if the cutting is performed from the inner peripheral wall side, the inner peripheral wall side where defects are concentrated is removed, and fine The outer peripheral wall side where the primary crystal Si is dispersed substantially uniformly remains. In other words, a cylinder sleeve having high strength and excellent wear resistance can be obtained because it has very few internal defects and is rich in fine primary crystal Si. Of course, a spiny is formed on the outer peripheral wall of the cylinder sleeve by transferring the irregularities on the surface of the coating material.

In the above-described embodiment, aluminum, ADC 10 or ADC 12 is selected as the material of the cylinder block, and ADC 12 is selected as the material of the outer cylindrical body 14, but for securing the bonding strength. The material of the outer cylindrical body 14 is not particularly limited as long as the difference between the thermal expansion coefficient and the linear expansion coefficient of the cylinder block material is within 3 × 10 ⁻⁶ / ° C. . Of course, the cylinder block and the outer cylindrical body 14 may be made of the same aluminum alloy.

  Further, the material of the inner cylindrical body 12 is not particularly limited to an A390 equivalent material (Al-17% alloy) or an AC9A equivalent material (Al-23% alloy), and when ensuring wear resistance, Any Al-Si based alloy having higher wear resistance than the Al-Si based alloy forming the outer cylindrical body 14 may be used.

  Further, the material of the inner cylindrical body 12 is not particularly limited to the one having high wear resistance, and the material of the outer cylindrical body 14 is not limited to the one close to the linear expansion coefficient of the cylinder block. What is necessary is just to change suitably.

  Furthermore, the thickness T2 of the outer cylindrical body 14 is not particularly limited to the range of 0.5 to 2.0 mm, and a desired tissue can be obtained by controlling the cooling rate of the inner cylindrical body 12. Set to

It is a general | schematic whole perspective view of the preforming body for providing the cylinder sleeve which concerns on this Embodiment. It is a principal part schematic block diagram of the centrifugal casting apparatus for producing the preform shown in FIG. FIG. 3 is a longitudinal sectional explanatory view showing a state in which an outer cylindrical body is provided using the centrifugal casting apparatus of FIG. 2. It is diameter direction cross-sectional explanatory drawing of the centrifugal casting apparatus in the state in which the outer cylindrical shape body was provided. It is a longitudinal direction cross-sectional explanatory drawing which shows the state which has provided the inner side cylindrical shape body using the centrifugal casting apparatus of FIG. It is diameter direction cross-section explanatory drawing of the centrifugal casting apparatus in the state in which the inner cylindrical body was provided. It is a principal part schematic block diagram of another centrifugal casting apparatus. It is a partial longitudinal cross-section principal part explanatory drawing which shows schematic structure of the pouring pipe and the molten metal holding furnace which comprise the centrifugal casting apparatus of FIG. FIG. 8 is a cross-sectional explanatory view along the longitudinal direction of the cylindrical mold showing a state where introduction of the molten metal into the cylindrical mold constituting the centrifugal casting apparatus of FIG. 7 is started. It is sectional explanatory drawing in alignment with the longitudinal direction of the cylindrical metal mold | die explaining the state which is heating the cylindrical body with the rod-shaped heater from the inner peripheral wall side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Preliminary body 12 ... Inner cylindrical shape body 14 ... Outer cylindrical shape body 20, 50 ... Centrifugal casting apparatus 22 ... Cylindrical metal mold 26 ... Roller 36, 40 ... Trough 38, 42, 52 ... Pouring pipes 44, 46 ... Pot 54 ... Rod heater 64 ... Supply pipe 66 ... Melt holding furnace 72 ... Wheel 74 ... Guide rail 76 ... Heat insulating material 78 ... Molten container 82 ... Gas introduction pipes L1, L2 ... Molten metal

Claims (7)

A cylinder sleeve disposed in a bore of a cylinder block constituting an internal combustion engine,
Having the outer cylindrical body and the inner cylindrical body in this order from the outer periphery side,
The cylinder sleeve characterized in that the inner cylindrical body and the outer cylindrical body are different types of Al-Si alloys.   2. The cylinder sleeve according to claim 1, wherein the Al—Si based alloy forming the inner cylindrical body has higher wear resistance than the Al—Si based alloy forming the outer cylindrical body. Cylinder sleeve. 3. The cylinder sleeve according to claim 1, wherein the outer cylindrical body is made of an Al—Si based alloy having a difference in linear expansion coefficient within 3 × 10 ⁻⁶ / ° C. with respect to a material forming the cylinder block. Cylinder sleeve characterized by   The cylinder sleeve according to any one of claims 1 to 3, wherein irregularities are formed on an outer peripheral wall of the outer cylindrical body. A method of manufacturing a cylinder sleeve disposed in a bore of a cylinder block constituting an internal combustion engine,
Supplying a first molten Al-Si alloy to a rotating cylindrical mold and providing an outer cylindrical body by centrifugal casting;
While rotating the cylindrical mold, an inner cylindrical body is provided by centrifugal casting by supplying a second molten metal, which is an Al-Si alloy different from the first molten metal, to the inside of the outer cylindrical body. A step of making a laminated preform,
Cutting out from the inner peripheral wall side of the preform,
A method for manufacturing a cylinder sleeve, comprising:   6. The cylinder sleeve according to claim 5, wherein the second molten metal is an Al-Si alloy molten metal having higher wear resistance than the Al-Si alloy of the first molten metal. Manufacturing method. 7. The manufacturing method according to claim 5, wherein the first molten metal has a linear expansion coefficient difference of 3 × 10 ⁻⁶ / ° C. or less with respect to a material forming the cylinder block. Manufacturing method.

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