JP4210469B2 - Method for producing cast iron cast member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a cast iron cast member cast into another metal, for example, an aluminum alloy.
[0002]
[Prior art]
For example, in a cylinder block constituting an automobile engine, an aluminum alloy cylinder block is generally employed for weight reduction. At that time, a cast iron cylinder liner (cast walnut member) is incorporated corresponding to a sliding surface that requires wear resistance and the like. Similarly, in the brake drum, a cast iron shoe (casting member) is used.
[0003]
By the way, when casting a cast-iron member made of cast iron with another metal, for example, an aluminum alloy, adhesion between the cast-in member and the aluminum alloy and a filling property of the aluminum alloy are required. Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 2001-170755, it has a cast-in surface having a maximum height of surface roughness of 65 μm to 260 μm and an average interval of irregularities of 0.6 mm to 1.5 mm. There is known a cast iron member for casting.
[0004]
As a result, when an aluminum alloy is die-cast on the outer periphery of the cast-in member, it is possible to obtain a cast-in product having good filling properties of the aluminum alloy into the concavo-convex part and excellent adhesion to the aluminum alloy. Yes.
[0005]
[Problems to be solved by the invention]
By the way, in said prior art, when forming a desired cast-off surface, 20 mass%-45 mass% of silica sand whose average particle diameter is 0.05 mm-0.5 mm as a coating material, and an average particle diameter are 0.00. A turbid liquid in which 10% by mass to 30% by mass of silica flower of 1 mm or less, 2% by mass to 10% by mass of a binder, and 30% by mass to 60% by mass of water are used.
[0006]
Therefore, in this prior art, when the coating agent is applied to the heated inner surface of the mold and dried, innumerable fine depressions are generated due to vapor holes generated from the coating material, and molten cast iron is poured. Thus, a cast-in surface having a needle-like protrusion corresponding to the depression is formed.
[0007]
In this case, as shown in FIG. 8, the cast-in member 1 is formed with a cast-in surface 3 having needle-like protrusions 2, and this cast-in surface 3 is cast into the aluminum alloy material 4 and cast-in. Product 5 is obtained. At that time, since the plurality of needle-like protrusions 2 are provided on the cast-in surface 3, no relative displacement in the direction of arrow A occurs, and the residual stress can be reduced.
[0008]
However, in the cast-in product 5 described above, peeling is likely to occur between the cast-in member 1 and the aluminum alloy material 4 along the arrow B direction parallel to the needle-like protrusions 2. Thereby, while the adhesiveness of the cast-in member 1 and the aluminum alloy material 4 falls, the contact area of the said cast-in member 1 and the said aluminum alloy material 4 falls, and there exists a problem that heat conductivity falls. It has been pointed out.
[0009]
The present invention solves this type of problem, and it is a cast iron cast-off member capable of effectively improving adhesion with other metals and maintaining desired thermal conductivity with a simple process. It aims at providing the manufacturing method of.
[0010]
[Means for Solving the Problems]
In the method for producing a cast iron cast member according to the present invention, a coating material containing a heat insulating material, a binder, a mold release agent, a surfactant and water is applied to the mold, and then the mold is not filled. Replaced with an active gas atmosphere. In this state, the cast iron melt is poured into the mold while the mold is rotated, so that the surface of the cast walnut has a substantially conical undercut portion that expands outward. A plurality of protrusions are provided.
[0011]
That is, when a coating material is applied in a mold, a part of the coating material forms a spherical portion by surface tension under the action of a surfactant contained in the coating material. For this reason, the coating material is provided with a large number of spherical portions having undercut portions from the coating surface corresponding to the inner surface of the mold.
[0012]
Next, since the inside of the mold is replaced with an inert gas atmosphere, the formation of an oxide film on the surface of the molten metal can be prevented, and the flowability of the molten metal within the mold is effectively improved. Therefore, the molten metal is smoothly and reliably filled up to the undercut portion covering the spherical portion of the coating material, and the shape of the coating material can be accurately transferred.
[0013]
Thereby, the cast iron cast-out member can reliably provide a plurality of protrusions having a substantially conical undercut portion that expands outward on the cast-out surface, for example, other aluminum alloy or the like. Adhesion with metal and thermal conductivity are effectively improved.
[0014]
The mold material is 20% to 35% by mass of diatomaceous earth as a heat insulating material, 1% to 7% by mass of bentonite as a binder, 1% to 5% by mass of a release agent, and 5ppm of a surfactant. ˜50 ppm, balance is set to water.
[0015]
If the diatomaceous earth is less than 20% by mass, the effect as a heat insulating material cannot be obtained. On the other hand, if it exceeds 35% by mass, the viscosity increases and the fluidity decreases. If the bentonite is less than 1% by mass, sufficient caking properties cannot be obtained and other substances are separated. On the other hand, if it exceeds 7% by mass, the viscosity increases and the disintegration property decreases.
[0016]
When the release agent is less than 1% by mass, the effect as the release agent cannot be obtained. On the other hand, when it exceeds 5% by mass, the structural water contained in the composition becomes gas due to the heat of the molten metal at the time of casting. There is a risk of gas defects occurring in the cast-in member. If the surfactant is less than 5 ppm, the shape maintaining effect cannot be obtained, while if it exceeds 50 ppm, foaming occurs.
[0017]
Furthermore, when the mold rotational speed of the mold is GNo. 25-GNo. 35. Mold rotation speed is GNo. If it is less than 25, crushing of the spherical portions of the coating material is reduced, and the interval between the spherical portions is widened. For this reason, a desired undercut amount cannot be ensured in the projections of the cast iron cast member, and sufficient adhesion cannot be obtained. On the other hand, the mold rotation speed is GNo. If it exceeds 35, the spherical portions of the coating material will be crushed and the intervals between the spherical portions will be reduced. Accordingly, in the projection of the cast iron cast member made of cast iron, the diameter of the small diameter portion becomes considerably small corresponding to the space between the spherical portions, and this small diameter portion may be broken.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a partially exploded perspective view of a cylinder block 12 for casting a cylinder liner (cast iron cast member) 10 manufactured by a method for manufacturing a cast iron cast member according to an embodiment of the present invention.
[0019]
The cylinder block 12 includes, for example, an aluminum alloy block 14 in order to reduce the weight. The cylinder block 12 is manufactured by casting the cylinder liner 10 made of cast iron and casting the aluminum alloy block 14.
[0020]
As will be described later, the cylinder liner 10 is manufactured using cast iron by a centrifugal casting method. As schematically shown in FIG. 2, a plurality of protrusions 20 having a substantially conical undercut portion 18 that expands outward is formed on the cast-out surface 16 provided on the outer peripheral surface of the cylinder liner 10. Is provided.
[0021]
As shown in FIG. 3, in the cylinder block 12, the gap between the protrusions 20 of the cylinder liner 10 is filled with an aluminum alloy block 14 to form a spherical joint 22.
[0022]
Next, a method for manufacturing the cylinder liner 10 configured as described above will be described.
[0023]
First, as shown in FIG. 4, a mold (die) 30 constituting the centrifugal casting apparatus has, for example, a cylindrical shape, and is rotatably supported via a drive unit (not shown).
[0024]
Therefore, the mold 30 has a mold rotational speed of GNo. 25-GNo. A coating material 36 is applied to the inner peripheral surface 34 of the mold 30 while rotating within the range 35. The mold material 36 includes a heat insulating material, a binder, a release agent, a surfactant, and water. Specifically, as a heat insulating material, for example, diatomaceous earth is 20% by mass to 35% by mass, and as a binder, for example, bentonite is 1% by mass to 7% by mass, a release agent is 1% by mass to 5% by mass, The surfactant is set to 5 ppm to 50 ppm, and the balance is set to water.
[0025]
When the coating material 36 is applied, a spherical portion 36b in which a part of the coating material 36 bulges out from the coating surface 36a due to surface tension is formed under the action of the surfactant contained in the coating material 36. . For this reason, the coating material 36 is provided with a large number of spherical portions 36b having undercut portions 36c from the coating surface 36a corresponding to the inner peripheral surface 34 which is a mold surface.
[0026]
Next, the atmosphere in the mold 30 is replaced with an inert gas atmosphere such as argon gas, for example. In this state, the mold 30 has a mold rotational speed of GNo. 100-GNo. While rotating within the range of 135, molten cast iron 40 is poured into the mold 30.
[0027]
Therefore, the molten metal 40 is filled so as to cover the spherical portion 36b of the coating material 36, and the shape of the coating material 36 is transferred. As a result, the cylinder liner 10 having the cylindrical shape and the cast-out surface 16 having the plurality of protrusions 20 formed on the outer peripheral surface is manufactured in the mold 30.
[0028]
In this case, in the present embodiment, the coating material 36 includes a heat insulating material, a binder, a release agent, a surfactant, and water. The heat insulating material is, for example, diatomaceous earth and has a function of optimally holding the temperature of the molten metal 40 poured into the mold 30. Diatomaceous earth is set to 20% by mass to 35% by mass. If the diatomaceous earth is less than 20% by mass, the effect as a heat insulating material cannot be obtained. On the other hand, if it exceeds 35% by mass, the viscosity increases and the fluidity decreases.
[0029]
The binder has a function of maintaining the shape of the spherical portion 36b of the coating material 36, and for example, bentonite is used. This bentonite is set to 1 mass% to 7 mass%. If the bentonite is less than 1% by mass, sufficient caking properties cannot be obtained and other substances are separated. On the other hand, if it exceeds 7% by mass, the viscosity increases and the disintegration property decreases.
[0030]
A mold release agent is set to 1 mass%-5 mass%. If the release agent is less than 1% by mass, the effect as the release agent cannot be obtained. On the other hand, if it exceeds 5% by mass, the structural water contained in the composition becomes gas due to the heat of the molten metal 40 during casting, and the cylinder liner 10 may cause a gas defect.
[0031]
The surfactant has a function of increasing the surface tension of the coating material 36 and maintaining the shape of the spherical portion 36b. The surfactant is set to 5 ppm to 50 ppm. If this surfactant is less than 5 ppm, the shape maintaining effect cannot be obtained, while if it exceeds 50 ppm, foaming occurs.
[0032]
In the present embodiment, after the application of the coating material 36 to the inner peripheral surface 34 of the mold 30 is completed, the molten metal 40 is poured in a state where the interior of the mold 30 is replaced with an inert gas atmosphere. For this reason, an oxide film is not formed on the surface of the molten metal 40 poured into the mold 30, and the flowability of the molten metal 40 in the mold 30 is effectively improved. Therefore, the molten metal 40 is smoothly and surely filled up to the undercut portion 36c covering the spherical portion 36b of the coating material 36, and the shape of the coating material 36 can be accurately transferred.
[0033]
Thereby, the cylinder liner 10 can reliably provide a plurality of protrusions 20 having a substantially conical undercut portion 18 that expands outward on the casting surface 16. For this reason, the effect that the adhesiveness with the aluminum alloy block 14 which casts the cylinder liner 10 and heat conductivity improves effectively is acquired.
[0034]
Furthermore, in this embodiment, as schematically shown in FIG. 2, the undercut portions 18 of the protrusions 20 are formed in a substantially conical shape, and the circumferential direction (arrow X direction) and the axial direction (arrow Y) of the cylinder liner 10 are formed. (Under direction) also has an undercut shape. Therefore, as shown in FIG. 3, in the cylinder liner 10 and the aluminum alloy block 14, the projection 20 of the cylinder liner 10 and the spherical joint portion 22 of the aluminum alloy block 14 are in close contact with each other.
[0035]
As a result, the cylinder liner 10 and the aluminum alloy block 14 are displaced in the direction of arrow A, that is, prevented from being displaced to reduce the residual stress generated in the inter-shaft portion 15 of the cylinder block 12, and in the direction of arrow B. It is possible to avoid as much as possible that the displacement, that is, peeling, is prevented and the mutual adhesion strength is reduced.
[0036]
Moreover, the contact surface area between the cylinder liner 10 and the aluminum alloy block 14 increases. For this reason, heat generated in the cylinder liner 10 due to sliding or the like can be efficiently transmitted to the aluminum alloy block 14, and heat dissipation can be improved.
[0037]
Further, the mold rotation speed of the mold 30 is such that the GNo. 25-GNo. 35. Mold rotation speed is GNo. If it is less than 25, as shown in FIG. 6, the collapse of the spherical portion 36b of the coating material 36 becomes small, and the interval H1 between the spherical portions 36b becomes wide. Thereby, a desired undercut amount cannot be ensured in the protrusion 20 of the cylinder liner 10, and sufficient adhesion cannot be obtained.
[0038]
On the other hand, the mold rotation speed is GNo. When it exceeds 35, as shown in FIG. 7, the spherical portion 36b of the coating material 36 is greatly crushed, and the interval H2 between the spherical portions 36b becomes narrow. Accordingly, the projection 20 of the cylinder liner 10 has a small diameter corresponding to the space between the spherical portions 36b, and the small diameter portion may be broken.
[0039]
In the present embodiment, the cylinder liner 10 of the cylinder block 12 is described as a cast iron cast-in member, but the present invention is not limited to this, and can be applied to, for example, a brake shoe of a brake drum. .
[0040]
【The invention's effect】
In the method for producing a cast iron cast member according to the present invention, a spherical protrusion having a substantially conical undercut portion can be reliably provided on the cast bur surface of the cast iron cast member by a simple process, For example, adhesion with other metals such as an aluminum alloy and thermal conductivity are improved.
[Brief description of the drawings]
FIG. 1 is a partially exploded perspective view of a cylinder block for casting a cylinder liner manufactured by a method for manufacturing a cast iron cast-out member according to an embodiment of the present invention.
FIG. 2 is a partially enlarged perspective view schematically showing protrusions of the cylinder liner.
FIG. 3 is a partial cross-sectional explanatory view of the cylinder block.
FIG. 4 is an explanatory diagram when a coating material is applied to a mold.
FIG. 5 is an explanatory diagram when pouring molten metal into the mold.
FIG. 6 is an explanatory diagram of a coating material when the rotation speed is small.
FIG. 7 is an explanatory diagram of a coating material when the number of rotations is large.
FIG. 8 is an explanatory view of a conventional cast-in member.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Cylinder liner 12 ... Cylinder block 14 ... Aluminum alloy block 16 ... Cast-in surface 18, 36c ... Undercut part 20 ... Protrusion 22 ... Spherical joining part 30 ... Mold 34 ... Inner peripheral surface 36 ... Coating material 36a ... Coating type Surface 36b ... Spherical part 40 ... Molten metal

Claims (2)

20% by mass to 35% by mass of diatomaceous earth as a heat insulating material, 1% by mass to 7% by mass of bentonite as a binder, 1% by mass to 5% by mass of a release agent, and 5ppm of a surfactant in a mold. wherein ～50Ppm, balance by applying a coating material is water, under the action of the surfactant, a step of Ru provided a plurality of spherical portions having an undercut portion protruding from the mold coating surface of the coating type material,
Replacing the inside of the mold with an inert gas atmosphere;
While rotating the mold coated with the coating material, by pouring a molten cast iron into the mold, the spherical portion protruding from the coating surface is transferred to the molten metal , Providing a plurality of protrusions having a substantially conical undercut portion that expands outward on the cast-out surface;
A method for producing a cast iron cast member made of cast iron.   The manufacturing method according to claim 1, wherein the mold rotational speed of the mold is set to GNo. 25-GNo. 35. A method for producing a cast iron cast member made of cast iron.

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