JP2786954B2 - Manufacturing method of connecting rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for manufacturing a connecting rod, and more particularly, to a connecting rod which is efficiently hot-formed using a rapidly solidified powdered material of an Al-Si alloy and has excellent performance. And a method for producing the same.

[0002]

BACKGROUND ART In recent years, rapidly solidified Al—Si alloys have characteristics such as high-temperature strength and high rigidity.
As a material suitable for the connecting rod), its use has been studied.

When manufacturing a connecting rod from such an Al-Si alloy material, first, a predetermined solidified Al-Si alloy melt is quenched by an appropriate spraying method such as gas atomization. An Si-based alloy powder material is produced, and the obtained powder material is classified, cold-pressed, and further heated and degassed to produce an extruded billet, and the extruded billet is hot-extruded. hand,
After the extruded material is formed into a round bar or a square bar, the extruded material is cut to form a forged material having a predetermined size for obtaining a connecting rod. Next, a predetermined forging operation is applied to such a forged material. However, since it is impossible to form a connecting rod having a desired shape by a single forging, heating-forging-burrs, The forging operation consisting of scratch removal is repeated several times, and after the final forging operation (finishing forging), the obtained forged product is deburred, and further subjected to heat treatment and machining to obtain the first connecting rod. Have got the product.

[0004] However, the rapidly solidified Al-Si alloy material used in the production of such connecting rods has a low hot deformability and poor hot formability. Therefore, it is necessary to reduce the degree of processing, and the number of forging operations for processing to a desired shape is inevitably increased, which causes a problem that productivity is lowered. Was. In addition, since the conventional forging material has a longitudinal shape that gives one connecting rod in the extrusion direction, and from that, forging one connecting rod, this also increases productivity. In addition to the decrease, there are inherent problems such as generation of many burrs and deterioration of the yield.

[0005]

The present invention has been made in view of such circumstances, and an object of the present invention is to produce a connecting rod using a rapidly solidified Al-Si alloy material. The purpose is to enhance the forging yield and to advantageously improve the forging yield.

[0006]

[However, x: hot extrusion ratio of billet, t: forging temperature (° C)]

Forging at y (%), a plurality of connecting rods are formed on the connecting rod material.
A gist of the present invention is a method for manufacturing a connecting rod, which comprises forming a rod.

[0007]

In the present invention, in order to provide excellent performance as a connecting rod and to efficiently perform hot forming, Si: 15.5 on a weight basis.
１８18.5%, Fe: 4 to 7%, Cu: 1 to 6%, M
It is necessary to use an aluminum alloy containing n: 0.3 to 3% and Mg: 0.3 to 3%, with the balance being substantially Al.

In such an alloy composition, Si
Is dispersed in the structure as an Al-Si-Fe-based compound in coexistence with Fe, and increases the fatigue strength and the notch fatigue strength;
It also has the effect of increasing the elastic coefficient and lowering the coefficient of linear expansion, but when its content is reduced, Al-Si-
When the amount of the Fe-based compound is insufficient, the fatigue strength and the notch fatigue strength are reduced, and when the content is too large, the Si particles become coarse, and the fatigue strength and the notch fatigue strength are reduced. It is necessary to select within the range of 15.5 to 18.5% (below the weight basis). Also, Fe
Increases the tensile strength, fatigue strength and notch fatigue strength by dispersing as an Al-Si-Fe-based compound in coexistence with Si and making the Si particles fine, and further increases the elastic modulus while increasing the linear expansion. Although it has the effect of lowering the coefficient, it is necessary to contain it at a rate of 4% or more in order to sufficiently exert those effects. Also, due to problems such as a decrease in ductility and a decrease in hot forgeability, The upper limit needs to be 7%.

Further, Cu coexists with Mg and imparts age hardening properties, and this age hardening improves tensile strength and fatigue strength. However, if the content is less than 1%, Cu If the effect cannot be sufficiently exhibited, and if it exceeds 6%, hot workability such as extrusion and forging is impaired, and corrosion resistance is reduced. Further, Mn is an element to be added in order to improve the heat resistance without significantly reducing the elongation, and it is necessary to contain 0.3% or more in order to sufficiently obtain the effect of the addition. However, when it exceeds 3%, a problem that elongation (ductility) is reduced is caused. Further, Mg is an element that coexists with Cu, imparts age hardening properties, and improves tensile strength, fatigue strength, and notch fatigue strength by age hardening, but its content is less than 0.3%. Then, the effect is not sufficient, and if it exceeds 3%, the effect becomes saturated.

From the molten aluminum alloy having such a composition, a rapidly solidified powder is prepared by a rapid solidification powdering technique similar to the conventional one, for example, a spraying technique such as a gas atomization method using air or an inert gas. Then, it is classified (for example, 297 μm or less) as necessary, and is used as a raw material for producing a target connecting rod.

[0011] Next, when an extrusion billet is manufactured using such a rapidly solidified Al-Si powder material, generally, the powder material is sealed in an aluminum can having a predetermined size, and then heated and degassed. The desired billet is produced by compression molding by hot pressing, cold isostatic pressing or the like to obtain a compressed product having a true density of about 60% or more. In addition, by encapsulating only the rapidly solidified powder material without encapsulating it in an aluminum can, or by encapsulating such a compact in a further aluminum can, then degassing and hot pressing, It is also possible to obtain the desired billet. Also, only the rapidly solidified powder material is compression molded,
Then, after heating to a predetermined temperature, it can be loaded in a hot press container and evacuated, and then the following hot extrusion operation can be performed.

The extruded billet thus obtained is loaded into a container of a hot extruder similar to the conventional one and is hot-extruded. , Are extruded so as to have a shape as close as possible to the outer shape of a form in which a plurality of connecting rods are juxtaposed. That is, as shown in FIG. 1, the extruded material can be extended in its cross-sectional form to an outer shape in which a plurality (two in this case) of connecting rods are juxtaposed without any extra gap. It is hot extruded through an extrusion die so as to have a shape approximately similar. By doing so, as compared with the conventional method of cutting out a forged material that gives a connecting rod one by one in the extrusion direction as shown in FIG.
It is possible to obtain a forged material that gives a plurality of connecting rods, and it is possible to minimize the ratio of unnecessary forged material portions when forging a connecting rod from such a forged material, thereby reducing the connecting rod. The forging yield can be significantly improved. For example, the forging yield was 40% in the past,
By adopting the extruded material shape as described above, it can be increased to 70%.

If the extrusion ratio (bill area / cross-section area of the extruded material) is too small during the hot extrusion, the bonding between the powder materials becomes insufficient, and the critical upsetting ratio is low. In addition, the directionality of the properties of the extruded material is remarkable, causing a problem of cracking in the forging process.On the other hand, if the extrusion ratio is too high, the directionality of the extruded material remains after forging, Since the original alloy characteristics are not obtained, in other words, the structure of the most important I section of the connecting rod is in a direction perpendicular to the extrusion direction, it remains even after forging. The hot extrusion operation is performed at an extrusion ratio in the range of 8 to 12.

Next, the extruded material thus obtained is cut in a direction perpendicular to the extrusion direction at a thickness capable of providing an intended connecting rod as shown by a broken line in FIG. A forged material, which is a connecting rod material, is cut out, and then the following formula is applied to the connecting rod material: 55 ≦ y ≦ x / 2 + 4t / 25-21 8 ≦ x ≦ 12 450 ≦ t ≦ 500 [where x: hot of billet] Extrusion ratio, t: forging temperature (° C.)].

In the above equation, if the degree of work (y) is lower than 55%, the number of forging steps (number of times) and the number of impacts for forging into a target connecting rod shape increase, so that the production Cause the problem of poor performance and high cost, and (x / 2 + 4t / 25-21)
%, A problem arises in that a crack is caused in the forged product. If the forging temperature (t) is lower than 450 ° C., it becomes difficult to forge at a sufficiently large working degree, causing cracks and the like in the forged product and causing an increase in the number of times of forging. On the other hand, when the temperature exceeds 500 ° C., the intermetallic compound present in the rapidly solidified powder material is coarsened, and the primary crystal Si is also coarsened, so that the heat resistance is lowered and the physical properties are adversely affected. Become.

Under such conditions, by forging the forged material cut out from the extruded material, it becomes possible to forge into a target connecting rod shape in three steps of rough, medium and finishing. In addition, in such a forging process, it is no longer necessary to perform the work of removing burrs and flaws, thereby enabling the forging process (number of times) to be advantageously reduced. The operation itself could be simplified.

After that, in such a forging process, the respective connecting rods are taken out from a forged product formed by forming a plurality of connecting rods on a forged material by a conventional deburring process or the like. By performing processing and the like, the intended connecting rod product is completed.

[0018]

Hereinafter, typical examples of the present invention will be described to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. Needless to say, it is not.

The present invention may be modified in various ways based on the knowledge of those skilled in the art, in addition to the following embodiments, and in addition to the above specific description, without departing from the spirit of the present invention. , Modifications, improvements, etc.
It should be understood.

First, Al-17.3% Si-4.45%
Fe-4.12% Cu-0.32% Mn-1.24% M
A rapidly solidified powder was prepared from the molten g alloy by a gas atomizing method similar to the conventional method, and the obtained powder was further classified to obtain a rapidly solidified powder material having a particle size of 149 μm or less. Next, this powder material was added to an outer diameter of 250 mm,
After filling and enclosing in an aluminum can having a can thickness: 5 mm and a length: 1000 mm at a density of 50%, the temperature is passed through a degassing pipe provided in the aluminum can.
Degassing was performed under the conditions of 495 ° C., time: 5 hours, and degree of vacuum: 1 to 10 Pa. Further, the degassed and rapidly solidified powder-enclosed aluminum can is accommodated in a 270 mmφ container, and the temperature is 400 ° C. and the pressure is 20.
Hot pressing under the condition of 0 MPa, the density is almost 10
A 0% extrusion billet was obtained. Thereafter, the billet is further subjected to a surface cutting of about 5 to 10 mm,
The aluminum can material portion present on the billet surface was cut off.

Next, the extruded billet thus obtained is used and stored in a container of a hot extruder,
Heat at a temperature of 400 ° C. and an extrusion ratio of 4, 8, or 12 through an extrusion die that gives an extruded material having a cross-sectional shape as close as possible to the external shape of the two connecting rods juxtaposed as shown in FIG. From the obtained extruded material, a forged material for forging a connecting rod was prepared from the obtained extruded material by cutting at a thickness capable of providing a connecting rod in a direction perpendicular to the extrusion direction.

Thereafter, the forged material is subjected to a rough forging using an ordinary air hammer (drop hammer) at various forging temperatures and working degrees as shown in Table 1 below. While investigating the presence or absence of cracks in the I section of the rough forged product, a plurality of forging operations were repeated on the rough forged product to form a desired connecting rod shape, and the number of times of forging was determined. The results are shown in Table 1 below, together with the results of the comprehensive evaluation. In addition, in the result of the crack evaluation of the I section in Table 1, G indicates that there is no crack, and N indicates that a crack has occurred. Further, in the number of times of forging after the second time, those marked with * indicate that it was necessary to heat again for forging.

[0023]

[Table 1]

As is evident from the results in Table 1, by adopting the forging conditions according to the present invention, the number of times of forging after the rough forging can be reduced to two, and even during the rough forging, the cracks in the I section portion can be obtained. No forging was observed, and a good quality connecting rod forged product could be obtained in a small number of forging steps (times). On the other hand, if the hot extrusion ratio is low or the temperature or working ratio employed in rough forging is low, the number of times of forging after rough forging increases, and it becomes necessary to reheat the forged material. , It ’s bad productivity,
In addition, when the degree of processing was increased in order to increase the productivity, cracking of the I section was caused, and it was impossible to commercialize the product at all.

[0025]

As is apparent from the above description, according to the present invention, a rapidly solidified Al-Si alloy powder material having low hot deformability and difficult to hot forge is used as a connecting rod. It is now possible to produce forged products with excellent characteristics in a small forging process (number of times) with good forging yield and high productivity.
There is great industrial significance of the present invention.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view showing a form of an extruded material obtained by hot extrusion and a cut-out form of a forged material therefrom according to the present invention.

FIG. 2 is a perspective explanatory view showing a form in which a forged material is cut out from an extruded material in a conventional method.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code FI F16C 7/00 F16C 7/00 (72) Inventor Yasuhiro Fukuda 3-1-1-12 Sento, Minato-ku, Nagoya City Sumitomo Light Metal Industries, Ltd. Inside the Technical Research Institute (72) Inventor Yuichi Takemoto 2-1-1 Taoyuan, Ikeda-shi, Osaka Dai-Hatsu Industry Co., Ltd. (72) Inventor Masayuki Suzuki 1350 Noji-cho, Kusatsu-shi, Shiga Prefecture ) Surveyed field (Int.Cl. ⁶ , DB name) B21K 1/14 B21J 1/04 B21J 5/02

Claims (1)

(57) [Claims] 1. Si: 15.5 to 18.5 based on weight
%, Fe: 4 to 7%, Cu: 1 to 6%, Mn: 0.3 to
After producing a billet for extrusion using a rapidly solidified powder of an aluminum alloy containing 3% and Mg: 0.3 to 3%, with the balance being substantially Al, the billet is
At an extrusion ratio of 8 to 12, the extruded material is hot-extruded so that the cross-section becomes as close as possible to the external shape of the form in which a plurality of connecting rods are juxtaposed. The material is cut in a direction perpendicular to the extrusion direction at a thickness that can provide the connecting rod, to obtain a connecting rod material, and then the connecting rod material is divided into the following formula: 55 ≦ y ≦ x / 2 + 4t
/ 25-21 8 ≦ x ≦ 12 450 ≦ t ≦ 500 [where x: hot extrusion ratio of billet, t: forging temperature (° C.)] Then, a plurality of connecting rods are attached to the connecting rod material.
A method for manufacturing a connecting rod, comprising forming a rod.