JPS5997362A - Piston pin and manufacture thereof - Google Patents

Abstract

PURPOSE:To heighten shearing strength and reduce the weight of a piston pin by disposing a thin steel pipe near a boundary between a piston portion and a connecting rod portion, forming the other portions with fiber/light alloy composite materials and manufacturing a piston rod by high-pressure casting. CONSTITUTION:Gaps 6A, 6B between a piston 2 and a connecting rod 3, where large shearing load is repeatedly applied, are provided with thin steel pipes 4A, 4B in such a manner as to extend broader in some measure than the width of the corresponding portions to ensure sufficient mechanical strength for repeated shearing load. The other portions are formed by a composite material of a light alloy material such as aluminum alloy, magnesium alloy or the like and various inorganic fibers, long fiber, short fiber composed of metal fiber, or whisker to reduce the total weight of the piston pin. Thus, the piston pin is manufactured by disposing fibers on the inside of a thin steel pipe raw material 7, performing high pressure casting with light alloy molten metal, and cutting the outer peripheral surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston pin used in a piston for internal combustion and a method for manufacturing the same, particularly a piston made of a fiber/light alloy composite material (fiber reinforced metal) and a 1M pipe. The present invention relates to a pin and a method for manufacturing the same.

As is well known, the piston pin is used to connect the piston and the connecting rod, and during use, a large shearing force is applied by the piston and the connecting rod, so it is required to have high strength and reliability. Since it is a moving part in an internal combustion engine, it is required to have a wide eave in order to reduce inertia. Conventional piston pins have generally been made of steel pipes, but although this has sufficient strength, it has the drawback of lacking lightness. Recently, it has been considered that fibers are integrated into light alloy materials such as aluminum alloys and magnesium alloys, and the light alloy material is reinforced with fibers to make piston pins. In this case, it is lightweight and has considerable strength, but the reality is that it does not always have sufficient strength against the shearing force applied in the direction perpendicular to the axis. in.

So the inventors! In order to take advantage of the advantages of i-fiber/light alloy composite material and steel pipe, we are developing a composite piston pin that uses both. Like this steel pipe and ff1l
A specific example of using the ff/light alloy composite material is to cover the outside of the fiber/light alloy composite material with a hollow steel pipe, but this alone is not necessarily sufficient to reduce the weight. In addition, bonding or press-fitting methods are generally known as conventional methods for joining hollow steel pipes and FIlt/light alloy composites, but these methods do not improve the bonding strength between the steel pipes and mechanical/light alloy composites. is not sufficient, and the force applied during use may cause the two to separate, so it is actually a bad idea to apply it to a piston pin. In addition, these methods do not allow the wall thickness of the closed tube to be made very thin, and in this sense, it is difficult to achieve sufficient weight reduction.

This invention was made in view of the above circumstances, and provides a composite piston that has sufficient strength against repeatedly applied shear loads and is sufficiently lightweight.
The object of the present invention is to provide a method for practically obtaining a composite piston pin having such excellent properties and excellent peeling resistance.

In other words, in the piston pin of the first invention, the surface layer near the boundary between the part in contact with the piston and the part in contact with the connecting rod is made of a thin-walled steel tube, and the other base part is made of fiber/light alloy. It is constructed of composite materials, and by placing thin-walled steel pipes only in the areas where shear loads are applied by the piston and connecting rod during use, it is possible to obtain sufficient strength against shear loads while at the same time reducing the weight sufficiently. This was achieved.

In addition, the piston pin manufacturing method of the M2 invention prepares a hollow thin-walled RF4 pipe material that is made so that the inner diameter of only the portion corresponding to the boundary between the portion in contact with the piston and the portion in contact with the funnel rod is smaller than the other portions. Then, m-fibers are placed inside this thin-walled steel pipe material, molten light alloy is poured into it, and r
By applying pressure to IIll, the fiber and light alloy are integrated into a composite, and the fiber I/1'! The base metal composite material and the outer pipe material are integrated, and after the molten metal solidifies, the outer thin wall tII
The piston pin of the first aspect of the invention is obtained by cutting the I-tube from the outer circumferential side, leaving a four-walled steel tube only in a portion corresponding to the vicinity of the boundary.

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 3 show a piston pin 1 according to one embodiment of the present invention, and FIG. 4 shows the piston pin 1 of this embodiment assembled to a piston 2 and a connecting rod 3 for opening the internal combustion R. Shows the attached state.

In FIGS. 1 to 3, the piston pin 1 includes a pair of single-walled steel pipes 4A and 4B forming a predetermined portion of the surface layer on the outer circumferential side, and fibers/fibers forming the other base portion □. It is formed from a light alloy composite material 5.

As is clear from FIG. 4, the thin-walled steel pipes 4A and 4B are arranged near the boundary between the portion in contact with the piston 2 and the portion in contact with the connecting rod 3, that is, in the gap between the piston 2 and the connecting rod 3. It is defined to be centered on the portion corresponding to the gaps 6A and 6B and to be located over a somewhat wider range than the width of the gaps 6A and 6B. Both of these positions are the piston 2 during use.
These are the parts where large shear loads are repeatedly applied by the connecting rods 3 and 3, and therefore thin-walled m-tubes 4A, 4 are
By arranging B, sufficient mechanical strength against repeated shearing loads can be ensured. In addition, as mentioned above, only the thin-walled steel pipes 4A and 4 are exposed to the shearing load.
B, and the other base portions are made of lightweight fiber/light alloy composite material 5, so the overall weight is slim.

The S miscellaneous/light alloy composite material 5 may include long fibers made of various inorganic materials or gold Rmlft for light alloy materials such as aluminum alloy or magnesium alloy.
A combination of short m fibers or voice car may be used. Here, it is desirable to select fibers that have sufficient heat resistance to withstand the working temperature of the piston pin and have excellent mechanical strength.Specifically, long fibers such as carbon fiber, alumina It is preferable to use gold FilQ fibers as the short fibers and silicon carbide as the voice car. Further, it is desirable that the mixing ratio of mu and the light alloy material is such that the volume ratio of the texture is about 30% to 70%.

Next, a method of manufacturing the above-mentioned piston pin, ie, the second invention, will be described with reference to FIGS. 5(A) to 5(C).

As shown in FIG. 5(A), a hollow thin-walled steel pipe material 7 is prepared in advance, with only the inner diameter of the necessary portions smaller than the inner diameter of the other portions. Portions 7A and 7B with small inner diameters in the thin ri pipe material 7 are set so as to be located near the boundary between the portion in contact with the screws 1 to 1 and the connecting rod in the final product. In addition, the inner diameter R1 of the thin-walled m-tube material 7 other than the small inner diameter portions 7A and 7B is approximately equal to or larger than the outer diameter of the piston pin to be finally replaced, and the small inner diameter portion 7A , 7B is set to be slightly smaller than the outer diameter of the piston pin that should finally turn blue.

Such a thin-walled steel pipe material 7 is placed in a high-pressure TVI mold, and fibers are arranged inside the thin-walled m-tube material 7, and light alloys such as aluminum alloy or magnesium alloy are used. m
A piston pin material is created by applying pressure to the piston pin and performing so-called high-pressure finishing.

Note that this pressing force is maintained until the light alloy melt is completely solidified.

The obtained piston pin material 8 is shown in FIG. 5(B). By performing high-pressure casting as described above, the void between the lapels is impregnated with the light alloy, and the mfl and the light alloy are integrated.
The inner side of the thin-walled steel pipe material 7 becomes the torture 1/light alloy composite material 5.

At the same time, the outer thin-walled m-tube material 7 and the fiber/light alloy composite material 5 are joined together. Note that in this casting process, it is desirable that the fibers placed inside the thin-walled steel pipe material 7 be formed in advance into a thick-walled hollow cylindrical shape.

Next, the entire outer peripheral surface of the piston pin material 8, that is, the outer peripheral surface of the thin-walled steel pipe material 7, is subjected to cutting. The cutting allowance at this time exceeds the thickness of the thin wall portions other than the small inner diameter portions 7Δ, 7[3, and the small inner diameter portions 7A, 7B.
shall not be removed. By performing such cutting, the thin wall m is formed on the outer peripheral surface of the piston pin* material 8.
Only the inner layer portions of the small inner diameter portions 7A and 7B of the tube material 7 remain as thin-walled steel tubes 2A and 2B, respectively. That is, as shown in No. 51"?1 (C), the part in contact with the piston] corresponds to the vicinity of the boundary with the part in contact with the rod.
The thin-walled steel pipes 2Δ and 2B remain only at t'i.

In the manufacturing method described above, the light alloy molten metal is heated at high pressure
The outer steel pipe part and own cost 1 are cast by 4 construction.
1. Since the Rei/light alloy composite material is welded and integrated, the bonding strength between the two is much higher than that of the press-fitting method or adhesive bonding that has been used since TT.Therefore, there is no possibility that the thin-walled mesh pipe will peel off during use. That's extremely rare. Also, after making a bozo, that is, p
After integrating the A pipe part and the light alloy composite material, the outer periphery is cut to make the steel pipe part thinner, so the final circular pipe part is much thinner than when using the conventional method. It can be made thinner, and therefore the weight can be sufficiently reduced.

As is clear from the above explanation, the piston pin of the present invention uses a thin-walled steel tube only in the area where repeated shearing loads are applied during use, that is, the area near the boundary between the part in contact with the screw I and the part in contact with the connecting rod. Arrangement and other parts are made of fiber/1! ! Since it is constructed from an alloy composite material, it has sufficient strength against shear loads, while at the same time achieving a reduction in weight as a whole, resulting in improved reliability and
High safety and low fuel consumption during internal combustion are also achieved.

Further, according to the manufacturing method of the present invention, not only can a piston pin having excellent characteristics as described above be practically manufactured by FJ, but also especially thin-walled steel pipes and l! It is possible to obtain a highly reliable piston pin with less risk of #J111 occurring between IIC/light alloy composite material, and the piston pin is sufficiently lightweight by making the wall thickness of the steel pipe sufficiently thin. Obtainable.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of the screw 1 hembin of the present invention, Fig. 2 is a sectional view at II-=II cotton in Fig. 1, and Fig. 3 is a concavity of the gate at line 1111 in Fig. 1. , Fig. 4 is a side view showing the piston pin shown in Fig. 1 attached to the internal jQ IF gate screws 1 to 1 and the connecting rod, and Figs. An example of the piston pin manufacturing method of the invention is shown step by step with a sheet cross section. 1... Piston pin, 2... Piston, 3...
・Connecting rod, 4△, 4B...thin wall m tube, 5...
・Group i/Light alloy composite material, 7... Thin wall closed tube material, 7
A, 7B...Small inner diameter part. Participant 1-Yota Automatic Width Co., Ltd. Agent Patent Attorney Ashi 1) Hisashi Take (and 1 other person) Figure 1 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) Of the surface layer on the outer peripheral surface of the piston pin, the surface layer near the boundary between the part in contact with screws 1 to 1 and the part in contact with the connecting rod is made of thin-walled steel pipe, and the other base part is made of fiber/light alloy composite. A piston pin characterized by being made of wood. (2) Prepare a hollow thin-walled steel pipe material whose inner diameter is smaller than the other parts only in the part corresponding to the boundary between the part in contact with the piston and the part in contact with the connecting rod. The mmi is placed to pour the light alloy molten metal, apply pressure to the molten metal, integrate the fibers and the light alloy, and integrate the fiber/light alloy composite material with the outer thin-walled steel pipe material. A method for producing a piston pin, which comprises cutting an outer thin-walled steel pipe material from its outer peripheral surface after solidification, leaving a thin-walled m-tube only in a portion corresponding to the vicinity of the boundary.