JP5134268B2 - Method for manufacturing hollow member - Google Patents

Description

The present invention relates to a process for the preparation of a suitable hollow member as a cylinder sleeve which is arranged in a bore of a cylinder block of an internal combustion engine.

  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.

  As described in Patent Document 1, 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. In this state, the cylinder sleeve is provided by performing machining such as cutting out on the cylindrical preform obtained by cooling and solidifying the molten metal. In addition, what is called a spiny is formed in the outer peripheral wall of a cylinder sleeve by transferring the uneven | corrugated shape formed in the surface of a 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.

Japanese Patent Publication No.52-27608

  By the way, when centrifugal casting is performed according to the description of Patent Document 1, a large amount of primary crystal Si is unevenly distributed on the outer peripheral wall side, so that the amount of primary crystal Si is reduced in the vicinity of the middle in the diameter direction of the preform. Therefore, when cutting out from the inner peripheral wall side of the preform, a cylinder sleeve with a small amount of primary crystal Si on the inner peripheral wall with which the piston is slidably contacted is obtained. In other words, when a cylinder sleeve made of an Al-Si alloy is produced by centrifugal casting, it is not easy to control the composition ratio of Si in the cylinder sleeve, and it is difficult to express desired characteristics for this reason. The problem of being is obvious.

  In addition, in order to ensure toughness while responding to the need for further improvement in the strength of the cylinder sleeve, the structure is improved, specifically, the primary crystal Si that precipitates when the molten Al-Si alloy solidifies is refined. To be considered. However, in order to refine the primary crystal Si when performing centrifugal casting, it is necessary to optimize the casting conditions such as the rotational speed and temperature of the cylindrical mold in various ways. That is, trial and error for optimizing casting conditions must be repeated. Moreover, at the time of mass production, it is necessary to strictly manage the optimized casting conditions.

The present invention has been made to solve the problems described above, it is possible to refine the primary crystal Si, moreover, the production method of strict management also unnecessary hollow member of convenient casting conditions work The purpose is to provide.

In order to achieve the above object, the present invention is a laminated hollow member having a substantially cylindrical shape,
Having an inner cylindrical cast and an outer cylindrical molded body in this order from the inner circumference side,
The inner cylindrical casting is made of aluminum or an aluminum alloy,
The outer cylindrical shaped body is made of an Al—Si based alloy.

  As will be described later, the inner cylindrical cast body is provided by centrifugal casting inside the outer cylindrical molded body inserted in advance in a cylindrical mold constituting the centrifugal casting apparatus. At this time, the outer cylindrical molded body functions as a chiller, so that the cooling rate of the molten metal is increased. For this reason, an inner cylindrical cast body in which fine primary crystal Si is dispersed substantially uniformly in the diameter direction is obtained. can get. In other words, in the inner cylindrical cast body constituting this hollow member, fine primary crystal Si is uniformly dispersed. Therefore, even if it is a different site | part, various characteristics are substantially equivalent.

  Moreover, for example, even if the hollow member is machined from the inner peripheral wall side (inner cylindrical cast body side) and thinned, the primary crystal Si is substantially uniformly dispersed as described above. It is possible to ensure excellent wear resistance and the like.

  In addition, it is preferable that the average particle diameter of primary crystal Si in the metal structure of the inner cylindrical cast is 35 μm or less. In this case, a hollow member having excellent wear resistance and good strength can be obtained.

  Here, as a preferable example of the hollow member, a cylinder sleeve disposed in a bore of a cylinder block constituting the internal combustion engine can be exemplified.

Further, the present invention is a method for producing a hollow member in which an inner cylindrical cast body and an outer cylindrical molded body are laminated in this order from the inner peripheral side,
Inserting a cylindrical body made of aluminum or aluminum alloy to be an outer cylindrical molded body into a cylindrical mold of a centrifugal casting apparatus;
Supplying a molten Al-Si alloy to the rotating cylindrical mold and providing an inner cylindrical cast body by centrifugal casting to form a laminated preform;
It is characterized by having.

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

  Moreover, after inserting a cylindrical body (outer cylindrical molded body), which is a molded body, into the cylindrical mold in advance, it is only necessary to perform a simple operation of supplying the molten Al-Si alloy to the cylindrical mold. Therefore, the manufacturing cost of the hollow member does not increase. As a result, the hollow member can be manufactured at low cost.

  In this case, it is preferable to set the thickness of the outer cylindrical shaped body to 1.0 to 2.0 mm. Thereby, the average particle diameter of primary crystal Si can be 35 micrometers or less. In addition, the particle size distribution width of primary Si becomes narrow.

  In order to obtain the cylinder sleeve, a step of cutting from the inner peripheral wall side of the preform may be provided.

  According to the present invention, the molten metal that becomes the inner cylindrical cast body is cooled and solidified while the cylindrical body (outer cylindrical molded body) previously inserted in the cylindrical mold functions as a chiller. As a result, an inner cylindrical cast body in which fine primary Si is dispersed substantially uniformly is obtained. That is, it is possible to easily configure a hollow member having an inner cylindrical cast body having a structure in which fine primary crystal Si is substantially uniformly dispersed and the characteristics are substantially the same throughout.

Hereinafter, like the preferred embodiment for the production method of the hollow member 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. The preformed body 10 is a laminated body in which an inner cylindrical cast body 12 and an outer cylindrical shaped body 14 are laminated, and is a hollow member having a through hole along the longitudinal direction thereof.

  In this case, the inner cylindrical cast body 12 is a cast product made of an Al-23% Si alloy (numbers are% by weight, the same applies hereinafter). That is, as will be described later, the inner cylindrical cast body 12 is provided by cooling and solidifying the molten metal. The thickness T1 is set to about 5 to 6 mm.

  In this inner cylindrical cast 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 shaped body 14 side). ing. In addition, the grain size distribution width of primary Si is small. In other words, the microstructure of the inner cylindrical cast body 12 is in a state where the fine primary crystals of substantially the same size are uniformly dispersed.

  One outer cylindrical shaped body 14 is a cylindrical body made of, for example, an Al-11% Si-2.5% Cu-based alloy (ADC12), and an inner peripheral wall thereof is an outer peripheral wall of the inner cylindrical cast body 12. It is joined. As shown in FIGS. 2 and 3, the outer cylindrical molded body 14 is inserted in advance into a cylindrical mold 22 constituting the centrifugal casting apparatus 20 before providing the inner cylindrical cast body 12. . A suitable thickness T2 of the outer cylindrical shaped body 14 is in the range of 1.0 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 cast body 12. In other words, the inner cylindrical casting 12 is thinned to a predetermined thickness. Thus, the inner cylindrical cast body 12 is provided as a machining allowance for the preformed body 10.

  As described above, in the inner cylindrical cast body 12, the primary crystal Si that is fine and has substantially the same dimensions 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 providing a through hole 34, and a pouring pipe 38 of the trough 36 is inserted into the cylindrical mold 22 through the through hole 34.

  The main body of the trough 36 accommodates a molten metal L of Al-23% Si-based alloy for providing the inner cylindrical cast body 12. A tiltable pot 40 is disposed in the vicinity of the trough 36, and the molten metal L is supplied to the trough 36 through the pot 40.

  In manufacturing the cylinder sleeve, first, a cylindrical body made of the ADC 12, that is, the outer cylindrical molded body 14 is inserted into the cylindrical mold 22 (see FIGS. 2 and 3). Of course, the outer diameter of the outer cylindrical molded body 14 corresponds to the inner diameter of the cylindrical mold 22, and therefore the outer cylindrical molded body 14 and the cylindrical mold 22 are hardly separated.

  In this state, the rotation of the roller 26 is started, and the cylindrical mold 22 is rotated following the rotation. As described above, since the play between the outer cylindrical molded body 14 and the cylindrical mold 22 is extremely small, the outer cylindrical molded body 14 does not vibrate in the cylindrical mold 22.

  On the other hand, as shown in FIG. 4, the pouring pipe 38 of the trough 36 is inserted into the cylindrical mold 22 through the through hole 34. Further, the Al-23% Si alloy melt L prepared in the melting furnace is moved to the pot 40 and moved to the main body of the trough 36 as the pot 40 is tilted. After that, a predetermined amount of the molten metal L of Al-23% Si-based alloy is supplied to the inside of the outer cylindrical shaped body 14 through the trough 36, and a disc-shaped closing member along the longitudinal direction of the outer cylindrical shaped body 14. Flows to 30 side. The molten metal L is further unevenly distributed on the inner peripheral wall of the outer cylindrical shaped body 14 by the action of centrifugal force so as to form the inner cylindrical shaped body 12. Here, in the present embodiment, the molten metal L is supplied in such an amount that the thickness of the inner cylindrical cast body 12 is in the range of 5 to 6 mm.

  As described above, the inner cylindrical casting 12 is formed as shown in FIG. As a result, the outer cylindrical molded body 14 is laminated on the outer side of the inner cylindrical molded body 12, and the inner peripheral wall of the outer cylindrical molded body 14 is joined to the outer peripheral wall of the inner cylindrical cast body 12. Is obtained.

  When the inner cylindrical cast body 12 is cooled and solidified, the outer cylindrical molded body 14 functions as a chiller. For this reason, in this Embodiment, the cooling rate of the molten metal L becomes large compared with general centrifugal casting. That is, since the molten metal L is solidified before the primary crystal Si grows greatly, a fine structure of the primary crystal Si is obtained. In the present embodiment in which the thickness T2 of the outer cylindrical molded body 14 is set to 1.0 to 2.0 mm, the average grain size of primary crystal Si is approximately 35 μm or less.

  Moreover, since the cooling rate is high, solidification occurs before Si in the molten metal L moves to the outer peripheral wall side by centrifugal force. Accordingly, uneven distribution of primary crystal Si is suppressed, and the primary crystal Si is dispersed substantially uniformly along the diameter direction of the inner cylindrical cast body 12. In this way, by making the outer cylindrical shaped body 14 function as a chiller, it is possible to obtain the inner cylindrical cast 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 preform 10 in which the inner cylindrical cast body 12 and the outer cylindrical molded body 14 are joined from this end side. Pull out and take out with the mold material. Thereafter, fine irregularities are provided on the outer peripheral wall of the outer cylindrical shaped body 14 by shot blasting or the like. Furthermore, if a machining is performed to remove a predetermined amount of machining allowance from the inner peripheral wall side of the inner cylindrical cast body 12, a cylinder sleeve having the inner cylindrical cast body 12 in which the primary crystal Si is dispersed substantially uniformly is obtained. .

  When the inner cylindrical cast body 12 is provided by centrifugal casting, the primary crystal Si is slightly unevenly distributed on the outer cylindrical molded body 14 side, and is located on the inner side of the diametrical middle part (the inner peripheral wall side of the inner cylindrical cast body 12). Even if the amount of primary Si is slightly reduced, as described above, since the cutting is performed from the inner peripheral wall side of the preformed body 10, the 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 shaped body 14 is made to function as a chiller so that the primary crystal Si can be refined. Therefore, the casting conditions such as the rotational speed and temperature of the cylindrical mold are strictly limited. There is no need to manage.

  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 metal used as a cylinder block, for example, molten metal, such as ADC12, is introduce | transduced with respect to this cavity.

  Eventually, a cylinder sleeve is cast in the cylinder block, thereby forming an internal combustion engine. At the time of this casting, the unevenness provided on the outer peripheral wall of the cylinder sleeve (outer cylindrical shaped body 14) functions as an anchor. Further, since the cylinder block and the outer cylindrical molded body 14 are the ADC 12, the linear expansion coefficients of the cylinder block and the outer cylindrical molded body 14 coincide with each other, and when the molten metal is introduced and when the molten metal is cooled and solidified. The cylinder sleeve and the cylinder block expand and contract to approximately the same extent. For this reason, peeling hardly occurs between the cylinder sleeve and the cylinder block. Therefore, sufficient bonding strength is ensured between the cylinder sleeve and the cylinder block only by the uneven anchor effect.

  In the internal combustion engine, the piston is in sliding contact with the inner peripheral wall of the cylinder sleeve. As described above, the inner peripheral wall of the cylinder sleeve is the inner cylindrical cast body 12 made of an Al-23% Si-based alloy rich in primary Si, 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.

  In the above-described embodiment, the case where the ADC 12 is selected as the material of the outer cylindrical molded body 14 constituting the cylinder sleeve has been described as an example. However, the present invention is not particularly limited to this, and the inner cylinder is not limited thereto. The same Al-23% Si alloy as the shape casting 12 may be used, or other aluminum alloys such as ADC10 may be used. Furthermore, aluminum may be sufficient.

  Further, the material of the inner cylindrical cast body 12 is not particularly limited to the Al-23% Si alloy, and may be, for example, ADC10 or ADC12.

  Further, the thickness T2 of the outer cylindrical molded body 14 is not particularly limited to the range of 1.0 to 2.0 mm, and a desired structure is obtained by controlling the cooling rate of the inner cylindrical molded body 12. To be set.

  Furthermore, although the cylinder sleeve preform 10 has been described as an example of the hollow member, the hollow sleeve member is not particularly limited to this, and any member may be used.

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 cross-sectional explanatory view in the diameter direction of the centrifugal casting apparatus showing a state in which an outer cylindrical molded body is inserted into a cylindrical mold constituting the centrifugal casting apparatus of FIG. 2. FIG. 3 is a longitudinal sectional explanatory view showing a state in which an inner cylindrical cast body is provided using the centrifugal casting apparatus of FIG. 2. It is diameter direction cross-section explanatory drawing of the centrifugal casting apparatus in the state in which the inner cylindrical casting was provided.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Preliminary molded object 12 ... Inner cylindrical shape molded object 14 ... Outer cylindrical shape molded object 20 ... Centrifugal casting apparatus 22 ... Cylindrical metal mold 26 ... Roller 36 ... Trough 38 ... Pouring pipe 40 ... Pot L ... Molten metal

Claims (3)

A method for producing a hollow member having a substantially cylindrical shape, in which an inner cylindrical cast body and an outer cylindrical molded body are laminated in this order from the inner peripheral side,
Inserting a cylindrical body made of aluminum or aluminum alloy to be an outer cylindrical molded body into a cylindrical mold of a centrifugal casting apparatus;
Supplying a molten Al-Si alloy to the rotating cylindrical mold and providing an inner cylindrical cast body by centrifugal casting to form a laminated preform;
A method for producing a hollow member, comprising: 2. The method for manufacturing a hollow member according to claim 1 , wherein a thickness of the cylindrical body that is the outer cylindrical shaped body is set to 1.0 to 2.0 mm. 3. The manufacturing method according to claim 1 , further comprising a step of cutting out from the inner peripheral wall side of the preform and forming a cylinder sleeve disposed in a bore of a cylinder block constituting the internal combustion engine. A method for producing a hollow member characterized by the above.

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