JP2019065802A - Casting member and manufacturing method thereof - Google Patents

Abstract

To reduce the weight and size of a casting member used as a cylinder sleeve mounted on a cylinder block.SOLUTION: A cylindrical casting member used as a cylinder sleeve of a cylinder block mounted on a vehicular engine, comprises a plurality of convex parts 2 provided on an outer peripheral surface 1a so as to project radially outward, and on the radially outward side of the convex part 2, a flat part 5 is provided so as to extend in a direction orthogonal to a radial direction. An undercut shape part 6 is composed of a side wall surface 3a of the convex part 2 and the flat part 5.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a cast-in member and a method of manufacturing the same.

  With the development of die casting technology, etc., the previously cast member is set in a mold, and a metal (melt) such as aluminum melted between the part and the mold is poured to bond or adhere to the part The so-called cast-in-cast method has come to be used. A member cast by this method is called a cast-in member.

  For example, as disclosed in Patent Document 1, needle-like (or convex) protrusions having undercut performance on the outer peripheral surface of a cylinder block of an automobile engine are generally uniformly formed in the circumferential direction. The cast-in member (cylinder sleeve) is widely used.

  In order to reduce the weight of the vehicle, it is required to reduce the weight of parts constituting the vehicle, such as a cylinder block. In the case of thinning a cylinder sleeve having a single needle-like protrusion whose tip is constricted to the outer peripheral surface as in Patent Document 1, for example, a method of thinning the effective thickness without changing the height of the protrusion. And a method of lowering the height of the projections to secure an effective thickness.

Patent No. 4429025 gazette

  However, when attempting to reduce the effective thickness without changing the height of the projections as in the above method, the rigidity of the sleeve is reduced.

  Generally, when a cast-in member (cylinder sleeve) is cast-wrapped in die-casting of a cylinder block, the cylinder sleeve is exposed to the high injection pressure of molten aluminum and has residual stress. In addition, even after the cylinder sleeve is cast and wrapped in the cylinder block, a high compressive load is applied by the bolt axial force at the time of fastening with the cylinder head.

  Under the above conditions, if high in-cylinder combustion pressure is intermittently applied to the cylinder sleeve during operation, distortion is likely to occur in the radial direction and axial direction in the low rigidity cylinder sleeve, resulting in large bore roundness. It will change. As a result, mechanical loss and blow-by gas increase are caused, and fuel consumption is reduced. Furthermore, the rigidity of the cylinder block may be reduced, and the NV characteristics may also be reduced.

  Further, there is a correlation between the height of the protrusion of the cylinder sleeve and the adhesion strength to the aluminum that is casted in the cylinder sleeve. If the height of the protrusion is reduced, the adhesion strength to the aluminum will be reduced. Then, due to the difference in coefficient of linear expansion between cast iron and aluminum, a gap is easily generated at the interface of the sleeve during operation, and uniform cooling of the engine is difficult to obtain.

  The present invention has been made to solve the above-mentioned problems, and an object thereof is to reduce the weight and downsizing of a cast-in member used as a cylinder sleeve mounted on a cylinder block.

  In order to achieve the above object, the cast-in member according to the present invention is a cylindrical member used as a cylinder sleeve of a cylinder block mounted on a vehicle engine. In the cast-in member, the outer peripheral surface is provided with a plurality of convex portions protruding outward in the radial direction, and on the radial outer side of the convex portions, a flat portion extending in the direction orthogonal to the radial direction An undercut shape portion is formed by the side wall of the convex portion and the flat portion.

  According to the present invention, the cast-in member used as the cylinder sleeve mounted on the cylinder block can be reduced in weight and downsized.

It is a perspective view which shows typically the member for cast-wrap based on this invention. It is a schematic cross-sectional view which shows typically the cross section perpendicular | vertical to the axial direction of the member for cast-in of FIG. It is the photograph which expands and shows the A section of FIG. It is the perspective view which showed the mesh-like convex part of FIG. 3 typically. It is sectional drawing which shows typically the cross section of the linear part of FIG. An example of a shape different from the linear portion of FIG. 5 is shown in (A), and another example is shown in (B). It is sectional drawing which shows typically the convex part of the state before making a radial direction compressive load etc. act on the convex part of FIG.

  BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the cast-in member 1 according to the present invention and the method for manufacturing the same will be described below with reference to the drawings (FIGS. 1 to 7).

  First, the structure of the casting member 1 of the present embodiment will be described. The cast-in member 1 of the present embodiment is a cylindrical member which is used for a cylinder sleeve (also referred to as a cylinder liner or a sleeve) of a cylinder block and is formed of cast iron or the like. The convex part 2 of is formed.

  The cast iron used for the cast-in member 1 is generally a ternary alloy containing iron, carbon and silicon, and may contain other elements depending on the application. For example, in addition to Fe, cast iron has 3.1 to 3.8 mass% of T.V. C (Total Carbon), 1.9 to 2.5% by mass of Si, 0.5 to 1.0% by mass of Mn, 0.01 to 0.5% by mass of P, 0.002 to 0.2% % S may be included.

  As shown in FIG. 1, the convex part 2 is provided in the whole region of the outer peripheral surface 1a of the casting member 1. Moreover, the casting member 1 has an effective thickness T. Here, the effective thickness T is, as shown in FIG. 2, a radial distance from the inner circumferential surface 9 of the cylindrical member constituting the cast-in member 1 to the bottom of the convex portion 2. The effective thickness T in this example is set, for example, in the range of 1 mm to 7 mm.

  The convex part 2 has the some linear part 2a and the some concentration part 2b, as shown in FIG.3 and FIG.4. The linear portion 2 a extends on the outer peripheral surface 1 a of the cast-in member 1 in a state of projecting radially outward from the outer peripheral surface 1 a. The concentrated portion 2 b is, for example, a portion formed by connecting the ends of three linear portions 2 a. The convex portion 2 in this example constitutes a mesh structure as a whole by the plurality of linear portions 2 a and the plurality of concentrated portions 2 b.

  In addition, FIG. 3 is a SEM photograph which observed the convex part 2 from diagonally upward. FIG. 4 is a perspective view schematically showing the convex portion 2, and schematically shows, for example, a portion B of FIG.

  The linear portion 2 a of the convex portion 2 has a vertical wall portion 3 and a flat portion 5. As shown in FIG. 4, the vertical wall portion 3 is a long wall portion protruding radially outward from the outer peripheral surface 1 a of the cast-in member 1. The flat part 5 is a part which is arrange | positioned at the radial direction outer side end of the convex part 2, and is extended in the direction orthogonal to radial direction, as shown in FIG. Hereinafter, the structure of the flat portion 5 will be described.

  The flat part 5 has the linear part 5a extended in the direction orthogonal to radial direction in the state which spaced apart radial direction with respect to the outer peripheral surface 1a, as shown in FIG. The straight portion 5 a protrudes from the side wall surface 3 a of the vertical wall portion 3 in the direction orthogonal to the radial direction. The projecting direction of the straight portion 5a may be either the axial direction or the circumferential direction.

  The straight portions 5a of the convex portion 2 shown on the left side in FIG. 5 extend to the left and right sides in FIG. The vertical wall portion 3 and the straight portion 5 a of the flat portion 5 form a substantially T-shape. On the other hand, the straight portion 5a of the convex portion 2 shown on the right side in FIG. 5 extends from the top of the vertical wall portion 3 to one side (left in FIG. 5). In this case, the vertical wall portion 3 and the straight portion 5 a of the flat portion 5 form a substantially bowl shape. The angle formed by the side wall surface 3a of the vertical wall portion 3 and the straight portion 5a of the flat portion 5 is preferably an acute angle, but may be an obtuse angle.

  A flat surface 5b extending in a direction orthogonal to the radial direction is formed on the radial direction outer side of the linear portion 5a. The flat surface 5b is preferably parallel to the axial direction, but may be inclined with respect to the axial direction. The method of forming the flat surface 5b will be described later.

  Further, the undercut shape portion 6 is provided in the convex portion 2. For example, as shown in FIG. 5, the undercut shape portion 6 is a portion configured by the straight portion 5 a and the side wall surface 3 a of the vertical wall portion 3 and is a so-called narrowed portion. The height h of the convex portion 2 indicates the amount by which the convex portion 2 protrudes radially outward, and is indicated by the distance from the base surface 8 of the outer peripheral surface 1 a to the flat surface 5 b of the linear portion 5 a. Since the base surface 8 is not strictly flat, the height h of the convex portion 2 may be defined as an average distance from the base surface 8 to the flat surface 5 b.

  In addition, since the anchor effect may be obtained by the whole vertical wall 3 and flat part 5 of the convex part 2, the shape of the whole convex part 2 including the vertical wall 3 and the flat part 5 is defined as an undercut shape It can also be done. In this case, the height h of the convex portion 2 may be defined as the height of the undercut shape.

  By providing the undercut shape portion 6 in the convex portion 2, when the cast-in member 1 is cast, for example, the molten metal wraps around the undercut shape portion 6 having a constriction, and the anchor effect can be improved. It becomes.

  The flat portion 5 may be provided with an extending portion 5 c like the convex portion 2 shown on the right side of FIG. 5. The flat portion 5 in this case has a straight portion 5a and an extending portion 5c, which are integrally formed. The extension part 5c is a part which protrudes toward the outer peripheral surface 1a from the front-end | tip of the linear part 5a. The undercut shape portion 6 in this example is configured by the side wall surface 3a of the vertical wall portion 3, the straight portion 5a, and the extension portion 5c. The anchor effect by the undercut shape portion 6 is improved by providing the extension portion 5c.

  In FIG. 6, the modification of the convex part 2 is shown. In FIG. 6A, the flat portion 5 is provided on the top of the vertical wall portion 3, and the portion which is the boundary between the flat portion 5 and the vertical wall portion 3 is narrowed. The convex portion 2 in this example is a so-called I-type, and the undercut shape portion 6 is configured by the constriction formed by the surface of the vertical wall portion 3.

  Moreover, as shown to FIG. 6 (B), another vertical wall part 3c may be arrange | positioned between the linear part 5a and the outer peripheral surface 1a. Thus, by having another vertical wall 3c, the anchor effect is improved by the tip of the straight portion 5a and the other vertical wall 3c. The cross-sectional shape of the undercut portion 6 of the convex portion 2 as shown in FIG. 5 and FIG. 6 is preferable from the viewpoint of improving the adhesion strength with the metal to be cast and thermal conductivity when cast and wrapped.

  In addition, the undercut shape part 6 can also be provided in the concentration part 2b of the convex part 2 similarly to the linear part 2a.

  Then, the manufacturing method of member 1 for cast in the embodiment is explained.

  First, on the outer peripheral surface 1a of the cylindrical member constituting the cast-in member 1, a mesh-like convex portion 2 projecting outward in the radial direction from the outer peripheral surface 1a is formed. About the process of forming convex part 2, although illustration by illustration is omitted, the process concerned applies the mold wash to the field which it is going to pour the molten metal of a mold, and the drying and solidification of the coated mold wash As shown in FIG. 7 by having a process of forming a moldable layer having a shape of a crack on the surface by shrinkage accompanying the process, and a process of pouring molten metal from above the moldable layer and casting while rotating a mold. The convex portion 2 is formed. The flat portion 5 is not formed on the convex portion 2 at this time.

  Next, the flat portion 5 of the undercut shape portion 6 is formed. In the present embodiment, for example, a compressive load is applied radially inward (downward in FIG. 7) to the radially outer end of the convex portion 2 shown in FIG. 7 by, for example, outer diameter reduction rolling using a pipe rolling mill. Thereby, the radial direction end of the convex part 2 deforms plastically. By plastically deforming, as shown in FIG. 5 and FIG. 6, a linear portion 5a constituting a flat portion 5 extending along the outer peripheral surface 1a is formed. A flat surface 5b is formed at the radially outer end of the straight portion 5a.

  By providing the flat portion 5 in the convex portion 2, the height of the convex portion 2 can be relatively lowered, and the anchor effect is improved by the undercut shape portion 6 in the radially outer portion of the convex portion 2. . Therefore, it becomes possible to satisfy the required characteristics of the cast-in member 1 used as the cylinder sleeve, that is, to thin the cylinder sleeve. Along with this, it is possible to shorten the pitch between the bores of the cylinder sleeves juxtaposed in the cylinder block.

  In addition, the contact area between the mesh-like plurality of convex portions 2 and the aluminum is entirely stabilized in the circumferential direction of the cylinder sleeve. Therefore, the heat conductivity from the cylinder sleeve to the aluminum side of the surrounding cylinder barrel can be improved and made uniform, and the heat of combustion in the cylinder can be dissipated more evenly. As a result, the heat dissipation of the engine combustion is improved.

  Furthermore, the anchor effect by the constriction of the mesh-like convex portion 2 can prevent the generation of a partial gap at the contact interface between the cylinder sleeve and the aluminum, and the wall temperature of the cylinder sleeve can be stabilized. As a result, it is possible to suppress the rise of the combustion temperature due to the high compression and to cope with the rise in the in-cylinder temperature.

  As a result, engine weight reduction and downsizing can be achieved, and engine compression can be further enhanced. Further, even if the height h of the convex portion 2 of the outer peripheral surface 1a of the cast-in member 1 used as the cylinder sleeve is low, the adhesion strength can be sufficiently secured, and weight reduction and high rigidity can be achieved. Therefore, by using the cast-in member 1 thus configured as a cylinder sleeve, the rigidity of the cylinder block itself can be improved, and the NV characteristics can be improved.

  Furthermore, in the present embodiment, when a compressive load is applied, a shear load may be applied in the axial direction of the cast-in member 1. In this case, the straight portion 5a of the flat portion 5 is formed to extend in the axial direction (shearing direction). Moreover, the extension part 5c is formed in the front-end | tip of the linear part 5a.

  For example, in FIG. 3, the vertical direction in FIG. 3 corresponds to the radial direction of the cast-in member 1, and the horizontal direction in FIG. 3 corresponds to the axial direction of the cast-in member 1. Arrow X in FIG. 3 indicates the direction of the compressive load. In contrast, the arrow Y indicates the direction of the shear load. The shear load shown in FIG. 3 acts on the left side in FIG. Therefore, the flat portion 5 shown in FIG. 3 often extends to the left in FIG.

  By applying a shear load in the axial direction while applying a compressive load inward in the radial direction and plastically deforming the radially outer portion of the convex portion 2, the flat portions 5 of the plurality of convex portions 2 in the direction of the shear load The orientation is made, and the flat portion 5 of the convex portion 2 has a superior orientation. Thereby, the anchor effect by the undercut shape part 6 improves.

  It is good to set height h of convex part 2 at this time as 0.1 mm-2.0 mm. The upper limit value of the height of the convex portion 2 is a value in consideration of the rigidity of the convex portion 2 and the rigidity required for the convex portion 2 can be obtained by setting it to 2.0 mm or less. The height of the convex portion 2 is more preferably 0.3 mm to 1.0 mm.

  Further, it is preferable that the variation (standard deviation σ) of the height h of the plurality of convex portions 2 be 150 μm or less, and the height h of the plurality of convex portions 2 be equalized. Furthermore, the standard deviation σ is preferably 30 μm or less. As shown in FIG. 5, it is preferable that the heights h of the convex portions 2 disposed on the left and right sides be equal. That is, it is preferable that the radial direction position of each flat surface 5b is equal.

  By setting the standard deviation σ of the height h of the plurality of projections 2 as described above, the height h of the plurality of projections 2 is equalized and stabilized. Thereby, the reinforcing rib effect by the mesh-like convex part 2 is relatively stabilized. Therefore, the variation in the specific elastic modulus of the cylinder sleeve in both the axial direction and the radial direction is reduced, and the change in performance caused by the difference in height h of the plurality of convex portions 2 of the outer peripheral surface 1a is extremely reduced. For example, the outer diameter size is stabilized, and the dimensional accuracy such as the inner diameter, roundness, cylindricity, perpendicularity, wall thickness, etc. of the machined cylinder sleeve is improved, and the thermal conductivity of the entire cylinder sleeve surface is improved Stabilize.

  Therefore, for example, even if external force such as injection pressure at the time of die casting, compression load at the time of cylinder head fastening to the cylinder block, and in-cylinder combustion pressure at the time of operation act, elastic deformation hardly occurs and distortion hardly occurs. That is, the cylinder sleeve performance is stabilized.

  In addition, before casting and covering the cast-in member 1 to be the cylinder sleeve, for example, after machining, it is possible to suppress a change in bore roundness at the time of fastening the cylinder head and at the time of operation. As a result, improvement in fuel consumption can be expected by reduction of mechanical loss and blow-by gas.

  Further, the height h of the convex portion 2 is stabilized by orienting the tip (radial outer end) of the convex portion 2 in the direction in which the shear load acts, and the undercut shape portion 6 of the convex portion 2 is constant. Because of the preferential orientation, the effect of the mesh-like convex portion 2 as a reinforcing rib becomes relatively more stable. That is, the cylinder sleeve performance is further stabilized.

  In addition, the overall rolling reduction is 0.1 to 5.0%, preferably 1.0 to 3.0%, to the cylindrical rough material in a high temperature state (about 400 ° C. or more) immediately after being extracted from the mold by the above-described centrifugal casting. Outer diameter reduction rolling etc.

  Also, if cold to less than 400 ° C., after the sleeve inner diameter portion is pre-processed, a high rigid mandrel is inserted into the inner diameter portion, and the total rolling reduction is 0.1 to 5.0%, preferably 1.0 to 3. Outer diameter reduction rolling or the like may be performed at 0%.

  Here, the rolling reduction is the thickness indicated by (φ1−φ2) / φ1 × 100, where the outer diameter of the rough material before and after rolling is φ1 and φ2, respectively, when rolling the rough material of a cylindrical cross section It is a decreasing rate. By setting the rolling reduction as described above, it becomes possible to further reduce the variation in height h of the plurality of convex portions 2, that is, the standard deviation σ.

  The description of the present embodiment is an example for describing the present invention, and does not limit the invention described in the claims. Moreover, each part structure of this invention can be variously deformed within the technical range as described in not only the said embodiment but the claim.

  The shear load applied to the flat portion 5 of the present embodiment is applied in the axial direction in the above embodiment, but the present invention is not limited to this. For example, a shear load may be applied in an optimal direction for each predetermined region of the outer peripheral surface 1 a of the cast-in member 1.

Reference Signs List 1 cast-in member 1a outer circumferential surface 2 convex portion 2a linear portion 2b concentrated portion 3 vertical wall 3a side wall surface 5 flat portion 5a straight portion 5b flat surface 5c extension portion 6 undercut shape portion 8 base surface 9 inner circumferential surface

Claims (8)

In a cylindrical cast-in member used as a cylinder sleeve of a cylinder block mounted on a vehicle engine,
The outer peripheral surface is provided with a plurality of convex portions projecting radially outward, and the radial outer side of the convex portions is provided with a flat portion extending in a direction orthogonal to the radial direction,
An undercut-shaped part is comprised by the side wall of the said convex part, and the said flat part, The member for cast-up characterized by the above-mentioned.   The flat portion includes a linear portion extending in a direction orthogonal to the radial direction with a radial interval in the outer peripheral surface, and an extension portion extending from the tip of the linear portion toward the outer peripheral surface. The cast-in member according to claim 1, characterized in that it has.   The cast-wrap member according to claim 1 or 2, wherein the height from the outer peripheral surface to the flat portion in the convex portion is 0.1 mm to 2.0 mm.   The member for cast-in according to claim 3, wherein a standard deviation of heights of the plurality of convex portions is 150 μm or less.   5. The cast-in member according to any one of claims 1 to 4, wherein longitudinal directions of the flat portions extend in the same direction. In a method of manufacturing a cylindrical cast-in member used as a cylinder sleeve of a cylinder block mounted on a vehicle engine,
Forming on the outer peripheral surface of the cast-in member a plurality of projections projecting radially outward from the outer peripheral surface;
A flat portion extending along the outer peripheral surface is formed by plastically deforming the radially outer end of the convex portion by a compressive load acting radially inward, and is constituted by the side wall of the convex portion and the flat portion And a step of forming an undercut shape portion.   The method of manufacturing a member for cast-in according to claim 6, wherein the step of forming the undercut shape portion includes a step of applying a shear load in an axial direction when applying the compressive load. In the step of applying the compressive load, the total rolling reduction is made 0.1 to 5.0%,
The total rolling reduction is represented by (φ1−φ2) / φ1 when the outer diameter of the rough material before and after rolling is φ1 and φ2, respectively, when the coarse material of the cross section is subjected to outer diameter reduction rolling.
The manufacturing method of the member for cast-in of Claim 6 or 7 characterized by these.