Casting product

Abstract

In this casting product, a hole can be well formed by casting out the hole in a mold during casting while minimizing turbulence in the flow of melt. The cast hole 2 (hole of the present invention) has a shape symmetrical with respect to the melt flow direction A and includes: a first arc portion 3 that is arranged on the upstream side in the melt flow direction A and is convex toward the upstream side in the melt flow direction A; a second arc portion 4 that is arranged on the downstream side in the melt flow direction A and is convex toward the downstream side in the melt flow direction A; and a pair of third arc portions 5, 5 that are arranged between the first arc portion 3 and the second arc portion 4 and are convex in directions away from each other in a direction perpendicular to the melt flow direction A. The length L1 of an apex connecting line 6 connecting apexes 5a, 5a of the third arc portions 5, 5 is formed to be longer than the length L2 of the chord of the first arc portion 3. An end portion 3a of the first arc portion 3 and an end portion 4a of the second arc portion 4 are connected via the third arc portion 5.

Description

Castings

[0001] The present invention relates to a casting having a hole formed by casting.

[0002] Conventionally, there have been suspension arms for vehicles that connect the vehicle body and the wheels and are formed by casting (see, for example, Patent Document 1). There have also been suspension arms that have circular holes formed in them, such as holes for work or drainage holes (see, for example, Patent Document 2).

[0003] JP 2016-168992 A JP 2002-205520 A

[0004] However, if circular holes such as the work holes and drain holes of Patent Document 2 are formed by casting using a mold during casting, there is a risk that the flow of molten metal will be disturbed, resulting in quality problems such as cold shuts, molten metal wrinkles, and hot water bubbles. For this reason, circular holes have been drilled after the casting has been cast, but this increases the number of processing steps.

[0005] Therefore, an object of the present invention is to provide a casting product in which holes can be well formed by casting out a mold during casting while minimizing turbulence in the flow of molten metal.

[0006] In order to achieve the above object, the casting of the present invention is a casting having a hole formed by casting, the hole having a shape symmetrical with respect to the molten metal flow direction, and comprising: a first arc portion that is arranged upstream in the molten metal flow direction and convex toward the upstream side in the molten metal flow direction; a second arc portion that is arranged downstream in the molten metal flow direction and convex toward the downstream side in the molten metal flow direction; and a pair of third arc portions that are arranged between the first arc portion and the second arc portion and convex toward directions separating from each other in a direction perpendicular to the molten metal flow direction, wherein a length of an apex connecting line connecting apexes of the pair of third arc portions is formed longer than a length of a chord of the first arc portion, and an end of the first arc portion and an end of the second arc portion are connected via the pair of third arc portions.

[0007] Furthermore, the casting of the present invention is a casting having a hole formed by casting, the hole having a shape symmetrical with respect to the molten metal flow direction, and comprising a first arc portion that is arranged upstream in the molten metal flow direction and is convex toward the upstream side in the molten metal flow direction, and a second arc portion that is arranged downstream in the molten metal flow direction and is convex toward the downstream side in the molten metal flow direction, the chord length of the second arc portion is formed to be longer than the chord length of the first arc portion, and the end of the first arc portion and the end of the second arc portion are connected via a tapered portion that gradually widens from the first arc portion toward the second arc portion.

[0008] According to the casting of the present invention, holes can be formed by casting out using a mold while minimizing turbulence in the flow of molten metal.

[0009] Fig. 1 is a plan view showing a first embodiment in which the casting of the present invention is applied to a lower arm. Fig. 2 is an enlarged plan view showing a hole (cast hole) of the first embodiment. Fig. 3 is an enlarged plan view of a hole (cast hole) showing a second embodiment of the present invention. Fig. 4 is an enlarged plan view of a hole (cast hole) showing a third embodiment of the present invention. Fig. 5 is an enlarged plan view of a hole (cast hole) showing a fourth embodiment of the present invention. Fig. 6 is a diagram showing the shapes of the cast holes of Comparative Examples 1 and 2 and Examples 1 and 2 in Table 1.

[0010] 1 and 2 show a first embodiment in which the casting of the present invention is applied to a lower arm 41, which is one form of a suspension arm.

[0011] 1, the lower arm 41 is an arm that connects the body and wheels of an automobile or the like. The lower arm 41 is disposed below the body and has a recessed portion 42 (thin portion of the present invention) provided in the center in the longitudinal direction, a bifurcated body connecting portion 43 provided on one side in the longitudinal direction, and a wheel connecting portion 44 provided on the other side in the longitudinal direction.

[0012] A cylindrical portion 45 for receiving a compression coil spring and a drain hole 46 are formed in the bottom wall 42a of the recess 42. The drain hole 46 is a hole of the present invention, and is formed on one side of the bottom wall 42a in the longitudinal direction and in the center in the width direction.

[0013] The lower arm 41 is formed by casting using a metal material such as aluminum, and during casting, molten metal flows in the direction A from a sprue provided on one end where the body connecting portion 43 is formed. In addition, the drainage hole 46 is formed by casting using a mold when the lower arm 41 is cast.

[0014] FIG. 2 is an enlarged plan view showing drainage holes (hereinafter referred to as "cast holes") formed in the lower arm 41 (cast product 1).

[0015] The cast-out hole 2 (drainage hole 46) is formed in a shape symmetrical with respect to the molten metal flow direction A, and is provided with a first arc portion 3 that is arranged upstream of the molten metal flow direction A and convex toward the upstream side of the molten metal flow direction A, a second arc portion 4 that is arranged downstream of the molten metal flow direction A and convex toward the downstream side of the molten metal flow direction A, and a pair of third arc portions 5, 5 that are arranged between the first arc portion 3 and the second arc portion 4 and convex toward directions that move away from each other in a direction perpendicular to the molten metal flow direction A.

[0016] The first arc portion 3 is an arc with a radius of curvature R1, the second arc portion 4 is an arc with a radius of curvature R2, and the third arc portion is an arc with a radius of curvature R3, where R3<R2<R1. Furthermore, the length L1 of the apex connecting line 6 connecting the apexes 5a of the pair of third arc portions 5 is longer than the length L2 of the chord of the first arc portion 3. Furthermore, the length L3 from the apex connecting line 6 to the apex 3b of the first arc portion 3 is longer than the length L4 from the apex connecting line 6 to the apex 4b of the second arc portion 4.

[0017] Furthermore, the ends 3a, 3a of the first arc portion 3 and one end 5b, 5b on the upstream side in the molten metal flow direction A of the third arc portion 5 are connected via first tapered portions 7a, 7a (tapered portions of the present invention) which gradually widen from the end 3a, 3a toward the one end 5b, 5b. Also, the other end 5c, 5c on the downstream side in the molten metal flow direction A of the third arc portion 5 and the end 4a, 4a of the second arc portion 4 are linearly connected via second tapered portions 7b, 7b which gradually narrow from the other end 5c, 5c toward the end 4a, 4a.

[0018] The above-described casting 1 is cast using a mold (not shown) equipped with a core hole forming portion (not shown) having the same shape as the core hole 2. The molten metal flowing from direction A first strikes the first arc portion 3 and flows along the arc of the first arc portion 3. Next, the molten metal flows from the ends 3a of the first arc portion 3 along the first tapered portions 7a, 7a, while separating (widening). Furthermore, upon reaching one end 5b of the third arc portion 5, the molten metal flows via the other end 5c of the third arc portion 5, 5, along the second tapered portions 7b, 7b in a converging direction (narrowing direction), and then converges at the apex 4b of the second arc portion 4. This allows the core hole 2 to be well formed during casting, while minimizing turbulence in the flow of the molten metal.

[0019] FIG. 3 shows a second embodiment of the casting, in which the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted.

[0020] In the cast-out hole 12 of this embodiment, the other end portions 5c, 5c of the third arc portion 5 on the downstream side in the molten metal flow direction A and the end portions 4a, 4a of the second arc portion 4 are connected in a curved manner via curved portions 12a, 12a.

[0021] As a result, the hot water that reaches one end 5b, 5b of the third arc portion 5, 5 flows gently along the curved portions 12a, 12a from the other end 5c, 5c via the third arc portion 5, 5, and joins at the top 4b of the second arc portion 4.

[0022] FIG. 4 shows a third embodiment of the casting, in which the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted.

[0023] In the cast hole 22 of this embodiment, the first arc portion 3 is formed as an arc with a radius of curvature R4, the second arc portion 4 is formed as an arc with a radius of curvature R5, and the third arc portion 5 is formed as an arc with a radius of curvature R6, where R6 < R4 < R5, and the radius of curvature R5 of the second arc portion 4 located downstream in the molten metal flow direction A is larger than the radius of curvature R4 of the first arc portion 3 located upstream in the molten metal flow direction A. Furthermore, the length L3 of the apex connecting line 23 connecting the apexes 5a, 5a of the third arc portion 5 is longer than the length L4 of the chord of the first arc portion 3. Furthermore, the length L5 from the apex connecting line 23 to the apex 3b of the first arc portion 3 is longer than the length L6 from the apex connecting line 23 to the apex 4b of the second arc portion 4.

[0024] FIG. 5 shows a fourth example of a casting, in which the cast hole 32 has a shape symmetrical with respect to the molten metal flow direction A, and is provided with a first arc portion 33 that is arranged upstream of the molten metal flow direction A and is convex toward the upstream side of the molten metal flow direction A, and a second arc portion 34 that is arranged downstream of the molten metal flow direction A and is convex toward the downstream side of the molten metal flow direction A.

[0025] The first arc portion 33 is formed as an arc with a radius of curvature R7, and the second arc portion 34 is formed as an arc with a radius of curvature R8, with R7<R8. Furthermore, the length L7 of the chord 35 of the second arc portion 34 is formed longer than the length L8 of the chord of the first arc portion 33. Furthermore, the length L9 from the chord 35 to the apex 33a of the first arc portion 33 is formed longer than the length L10 from the chord 35 to the apex 34b of the second arc portion 34.

[0026] Furthermore, the ends 33b, 33b of the first arc portion 33 and the ends 34a, 34a of the second arc portion 34 are connected via tapered portions 36, 36 that gradually widen from the first arc portion 33 toward the second arc portion 34.

[0027] In the fourth embodiment described above, the chord of the first arc portion 33 and the chord 35 of the second arc portion 34 are diameter lines passing through the centers of the circles that make up the first arc portion 33 or the second arc portion 34, respectively, but these chords do not have to pass through the centers of the circles that make up the first arc portion 33 or the second arc portion 34.

[0028] As described above, in each of the first to fourth embodiments, during casting, the molten metal first hits the curved first arc portion, flows along the tapered portion while widening (separating), then flows gently in a direction narrowing (merging direction) toward the second arc portion, and merges at the top of the curved second arc portion. This makes it possible to form a good cast-out hole while minimizing turbulence in the flow of the molten metal.

[0029] Next, the flow speed of the molten metal was measured and compared when casting two cast holes (Examples 1 and 2) formed by changing the length L9 from the chord 35 of the cast hole 32 to the apex 33a of the first arc portion 33 and the length L10 from the chord 35 to the apex 34b of the second arc portion 34, a circular cast hole (Comparative Example 1), and a cast hole (Comparative Example 2) in which the radius of curvature R7 of the first arc portion 33 was larger than the radius of curvature R8 of the second arc portion 34. The results are shown in Table 1.

[0030] The molten metal velocity was measured as V1 just before point P1, where the molten metal first reaches the core, and as V2 just before point P2, where the molten metal meets the core. The pouring conditions were a flow rate of 10 g / sec and a pouring angle of 45 degrees. The core holes of Comparative Examples 1 and 2 and Examples 1 and 2 were formed based on the values ​​in the table, and are shown in Figures 6a to 6d.

[0031]

[0032] Examples 1 and 2 are the cast holes shown in the fourth embodiment described above, with Example 2 being formed with a longer length L9 than Example 1. Comparative Example 2 is formed by reversing the positions of the first arc portion and the second arc portion of Example 1, with the radius of curvature R7 of the first arc portion being larger than the radius of curvature R8 of the second arc portion.

[0033] As shown in Table 1, the difference between the velocity V1 just before the arrival point P1 and the velocity V2 just before the junction P2 is smaller in the cast holes of Examples 1 and 2 compared to the cast holes of Comparative Examples 1 and 2, so that turbulence in the flow of molten metal is less likely to occur, and it was found that making the radius of curvature R8 of the second arc portion, i.e., the length of the chord of the second arc portion, longer than the radius of curvature R7 of the first arc portion, i.e., the length of the chord of the first arc portion, makes turbulence in the flow of molten metal less likely to occur. Furthermore, it was found from Examples 1 and 2 that by increasing the length L9 from the chord of the second arc portion to the apex of the first arc portion, the difference between the velocity V1 just before the arrival point P1 and the velocity V2 just before the junction P2 is eliminated, allowing for good formation of the cast holes and less turbulence in the flow of molten metal.

[0034] As described above, the holes of the present invention can be formed while stabilizing the flow of molten metal and can be applied to any casting, but are particularly effective in castings such as lower arms that require a flat, thin-walled portion (bottom wall) to hold a compression spring, because they can form drainage holes in the thin-walled portion without causing quality problems such as cold shuts, creases, or lumps. Furthermore, the radius of curvature of each arc portion and their location are not limited to the above-mentioned examples and can be arbitrarily selected.

[0035] DESCRIPTION OF SYMBOLS 1...casting, 2...cast hole, 3...first arc portion, 3a...end portion, 3b...top portion, 4...second arc portion, 4a...end portion, 4b...top portion, 5...third arc portion, 5a...top portion, 5b...one end portion, 5c...other end portion, 6...top connecting line, 7a...first tapered portion, 7b...second tapered portion, 12...cast hole, 12a...curved portion, 22...cast hole, 23...top connecting line, 32...cast hole, 33...first arc portion, 33a...top portion, 33b...end portion, 34...second arc portion, 34a...end portion, 34b...top portion, 35...chord, 36...tapered portion, 41...lower arm, 42...recessed portion, 42a...bottom wall, 43...body connecting portion, 44...wheel connecting portion, 45...cylindrical portion, 46...water drainage hole

Claims

1. A casting having a hole formed by casting, the hole having a shape symmetrical with respect to the direction of molten metal flow, the casting comprising: a first arc portion located upstream of the direction of molten metal flow and convex toward the upstream side of the direction of molten metal flow; a second arc portion located downstream of the direction of molten metal flow and convex toward the downstream side of the direction of molten metal flow; and a pair of third arc portions located between the first arc portion and the second arc portion and convex toward directions separating them in a direction perpendicular to the direction of molten metal flow, wherein the length of an apex connecting line connecting the apexes of the pair of third arc portions is longer than the length of a chord of the first arc portion; and the casting comprising: an end of the first arc portion and an end of the second arc portion connected via the pair of third arc portions.

2. A casting according to claim 1, characterized in that the first arc portion and the third arc portion are connected via a tapered portion that gradually widens from the first arc portion toward the third arc portion.

3. A casting according to claim 2, wherein said third arc portion and said second arc portion are connected in a straight line.

4. A casting according to claim 2, wherein said third arc portion and said second arc portion are connected in a curved line.

5. A casting according to claim 1, wherein the length from said apex connecting line to the apex of said first arc portion is longer than the length from said apex connecting line to the apex of said second arc portion.

6. A casting having a hole formed by casting, the hole having a shape symmetrical with respect to the direction of molten metal flow, the casting comprising: a first arc portion located upstream in the direction of molten metal flow and convex toward the upstream side in the direction of molten metal flow; and a second arc portion located downstream in the direction of molten metal flow and convex toward the downstream side in the direction of molten metal flow, the chord length of the second arc portion being longer than the chord length of the first arc portion, and the end of the first arc portion and the end of the second arc portion being connected via a tapered portion that gradually widens from the first arc portion toward the second arc portion.

7. A casting according to claim 6, characterized in that the length from the chord of said second arc portion to the apex of said first arc portion is longer than the length from the chord of said second arc portion to the apex of said second arc portion.

8. A casting according to any one of claims 1 to 7, characterized in that the casting is a suspension arm.

9. A casting according to any one of claims 1 to 7, characterized in that the hole is formed in the thin-walled portion.

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