JP4210468B2 - Cast iron cast-in member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cast iron cast member cast into another metal such as an aluminum alloy by casting.
[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 the above prior art, when applying the coating agent to the heated inner surface of the mold and drying it, countless minute depressions are generated due to the 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.
[0006]
In this case, as shown in FIG. 7, the cast-in member 1 is formed with a cast-in surface 3 having needle-like protrusions 2, and the 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.
[0007]
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 thermal conductivity deteriorates. It has been pointed out.
[0008]
Further, after casting the cast-in member 1, it is necessary to process the inner surface (sliding surface) of the cast-in member 1. At the time of processing the inner surface, the cast-in member 1 is clamped by positioning the outer peripheral surface by a clamp mechanism.
[0009]
However, a needle-like protrusion 2 is provided on the outer peripheral surface of the cast-in member 1 and the tip of the needle-like protrusion 2 is held by point contact with the positioning clamp surface of the clamp mechanism. Thereby, the contact area of the positioning clamp surface and the cast-in member 1 decreases, and the clamp positioning accuracy of the cast-in member 1 decreases. Therefore, there is a problem that the processing accuracy of the inner surface of the cast-in member 1 is considerably reduced.
[0010]
The present invention solves this type of problem, and it is a cast iron cast member that can effectively improve the adhesion to other metals and maintain the desired clamp positioning accuracy with a simple process. The purpose is to provide.
[0011]
[Means for Solving the Problems]
In the cast iron cast member according to the present invention, a plurality of protrusions having a substantially conical undercut portion that expands outward are formed independently of each other on the cast fill surface that comes into contact with the molten metal of other metal during casting. It is provided so as to be scattered .
[0012]
As a result, the cast iron cast member is provided with a substantially conical undercut portion that expands in various directions on the cast fill surface, so that, for example, adhesion to other metals such as an aluminum alloy is improved. Effectively improve. In addition, since the surface area of each protrusion increases compared to conventional needle-like protrusions, the heat generated in cast iron cast-in members due to sliding, etc. when aluminum cast products are actually used is good for aluminum alloys. The heat dissipation can be effectively improved.
[0013]
Moreover, the flat part is provided in the front-end | tip of each protrusion corresponding to the front-end | tip of the undercut part which spreads outward. For this reason, a contact area with the clamp surface which clamps the outer peripheral surface of a cast iron cast-in member is significantly increased as compared with a conventional needle-like protrusion. This is because point contact is changed to surface contact. Therefore, the clamp positioning accuracy of the cast iron cast-in member is improved, and the cast iron cast-in member can be processed with high accuracy and good performance.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a partially exploded perspective view of a cylinder block (cast product) 12 that casts a cylinder liner (cast iron cast member) 10 according to an embodiment of the present invention.
[0015]
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.
[0016]
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. A flat portion 21 is provided at the tip of each protrusion 20 corresponding to the tip of the undercut portion 18 that expands outward.
[0017]
For example, when the outer diameter of the cylinder liner 10 is set to 60 mm to 100 mm, the height of each projection 20 from the cast-in surface 16 is set to a range of 0.5 mm to 1.2 mm. The inner surface 10a of the cylinder liner 10 constitutes a sliding surface, and the inner surface 10a is machined after casting.
[0018]
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.
[0019]
Next, a method for manufacturing the cylinder liner 10 configured as described above will be described.
[0020]
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).
[0021]
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.
[0022]
When the coating material 36 is applied, a spherical portion 36b is formed by part of the coating material 36 bulging out from the coating surface 36a due to surface tension under the action of the surfactant contained in the coating material 36. Is done. 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.
[0023]
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.
[0024]
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.
[0025]
Further, as shown in FIG. 6, the cast cylinder liner 10 is processed on the inner surface 10 a through a processing machine (not shown) while being positioned and held by the clamp mechanism 50. At that time, the clamp surface 52 constituting the clamp mechanism 50 is in surface contact with the flat portion 21 provided at the tip of the projection 20 of the cylinder liner 10.
[0026]
Thus, since the cylinder liner 10 is held by surface contact, the contact area is greatly increased compared to the case where the conventional needle-like protrusion 2 (see FIG. 7) is held by point contact with the clamp surface 52. It is done. As a result, the cylinder liner 10 can be clamped and positioned with high accuracy through the clamp mechanism 50, and the processing accuracy of the inner surface 10a of the cylinder liner 10 can be improved.
[0027]
The cylinder liner 10 subjected to predetermined processing including processing of the inner surface 10a is arranged in a cylinder block casting mold (not shown). Next, another metal, for example, a molten aluminum alloy is poured into the mold, and the cylinder liner 10 is cast by the aluminum alloy block 14 to manufacture the cylinder block 12.
[0028]
In this case, in this embodiment, as schematically shown in FIG. 2, the undercut portion 18 of each protrusion 20 has a substantially conical shape, and the circumferential direction (arrow X direction) and the axial direction (arrow Y) of the cylinder liner 10. (Under direction) also has an undercut shape. Therefore, as shown in FIG. 3, the protrusion 20 of the cylinder liner 10 and the spherical joint 22 of the aluminum alloy block 14 are in close contact with each other.
[0029]
Thereby, the cylinder liner 10 and the aluminum alloy block 14 prevent displacement in the direction of arrow A, that is, displacement, and reduce the residual stress generated in the inter-shaft portion 15 (see FIG. 1) of the cylinder block 12. At the same time, it is possible to avoid as much as possible a shift in the direction of the arrow B, that is, a reduction in mutual adhesion strength by preventing peeling.
[0030]
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.
[0031]
Furthermore, in this embodiment, the height of the protrusion 20 of the cylinder liner 10 is set between 0.5 mm and 1.2 mm. If the height of the protrusion 20 is less than 0.5 mm, it becomes difficult to form the undercut portion 18 having a desired shape, and the adhesiveness with the aluminum alloy block 14 is lowered. On the other hand, when the height of the protrusion 20 exceeds 1.2 mm, the length of the small diameter portion of the protrusion 20 becomes long and the small diameter portion may be broken.
[0032]
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. .
[0033]
At that time, when the outer shape of the brake shoe is about 130 mm, it is preferable to set the height of the protrusion provided on the brake shoe within a range of 0.5 mm to 2 mm.
[0034]
【The invention's effect】
In the cast iron cast member according to the present invention, since the substantially conical undercut portion that expands in various directions is provided on the cast fill surface, for example, the adhesion with other metals such as an aluminum alloy is improved. Effectively improve. Furthermore, since the surface area of each protrusion is increased compared to conventional needle-like protrusions, when using a cast product, heat generated in the cast iron cast member can be transferred well to the aluminum alloy, Effectively improves heat dissipation.
[0035]
Moreover, the flat part is provided in the front-end | tip of each protrusion corresponding to the front-end | tip of the undercut part which spreads outward. For this reason, a contact area with the clamp surface which clamps the outer peripheral surface of a cast iron cast-in member is significantly increased as compared with a conventional needle-like protrusion. Therefore, the clamp positioning accuracy of the cast iron cast-in member is improved, and the cast iron cast-in member can be processed with high accuracy and good performance.
[Brief description of the drawings]
FIG. 1 is a partially exploded perspective view of a cylinder block for casting a cylinder liner 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 view when the cylinder liner is positioned by a clamp mechanism.
FIG. 7 is an explanatory view of a conventional cast-in member.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Cylinder liner 10a ... Inner surface 12 ... Cylinder block 14 ... Aluminum alloy block 16 ... Cast-off surface 18, 36c ... Undercut part 20 ... Protrusion 21 ... Flat part 22 ... Spherical joining part 30 ... Mold 34 ... Inner peripheral surface 36 ... Coating material 36a ... Coating surface 36b ... Spherical part 40 ... Melting metal 50 ... Clamp mechanism 52 ... Clamping surface

Claims (1)

A cast iron cast member cast around other metal by casting,
A plurality of protrusions having a substantially conical undercut portion that expands outward is provided on the cast walnut surface that contacts the molten metal of the other metal during casting ,
The projection is cast iron insert casting member, characterized that you interspersed independently of one another.

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