JPS58501580A - piston - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Piston This invention relates to a piston for an internal combustion engine.

Pistons made of light metal alloys such as aluminum, especially hollows for diesel engines A piston with a circular combustion chamber may crack its crown under certain operating conditions. is generally well known. This crack mainly occurs at the periphery of the combustion chamber, and This is particularly noticeable when the combustion chamber is of the re-inflow type.

High strength and good heat properties such as IJ Kumu copper alloy, copper-nickel-silicon bronze, etc. Cast-in reinforcing material made of conductive copper alloy can avoid the above cracks. It is also known that the copper alloy part is cut. The machining process prevents the periphery of the combustion chamber, which is normally prone to cracking, from cracking. It is formed in such a way that it is difficult to form.

The aluminum alloy in the piston crown around the copper alloy reinforcement is The legs are generally not strong enough to withstand the stress caused by the inertia of the legs. material (e.g. stainless steel or copper alloy) that does not protrude into the cooling part of the piston. There is the worry of having to fully connect the reinforcing material by inserting the reinforcing material.

However, the manufacture of this type of piston is quite problematic. this problem Basically, a) if the piston is manufactured using the conventional crown casting method; The accuracy of the positioning of each part in b) When casting is performed using the crown-subposition method, make sure that no porous cavities occur in the skirt part. The purpose of this is to prevent, in fact, the precise positioning of the stiffeners and legs.

According to the invention, the piston is entirely made of a light metal alloy with an insertion reinforcement on the top surface. In this method, when casting a piston using the crown-subposition method, the piston is placed on top of the insertion reinforcing material. The heat and pressure conditions for pouring hot water into the alloy are such that the A stone main body is formed and a strong bond is developed between the main body and the reinforcing material. It is considered to be a condition for

One way to effectively carry out the method according to this invention is to Pressurized die casting method or compression casting 1k applied, two-f re-piston alloys are available. It is preferable to apply pressure while the material is not solidified and maintains tif plasticity. Or alternatively First, after rough-cutting the metal block (billet) and making it into a shape that can be fitted with insertion reinforcing material, The above-mentioned strong bond is achieved by placing the billet on top of the reinforcing material, heating it, and forging it under pressure. The mating state may occur between the entire piston upper body and the reinforcing member.

This invention will become clearer by explaining one embodiment with reference to all the drawings below. In the drawings, FIG. 1 shows an example of a piston according to the present invention in the axial direction. It is a cross-sectional view, and Figure 2 shows one step in the manufacturing process of the piston shown in Figure 1. be.

The piston in the figure is made of aluminum alloy and should also be used in diesel engines. It is. The finished product of this piston is shown in Fig. The rim-like combustion chamber +11 is made of a cylindrical combustion chamber. protected by the reinforcement (2), i.e. by the rim it forms. Ru. Examples of alloys for reinforcing materials include PEIJ, IJKUM~copper alloy, or copper-nickel~ It may be silicon-based bronze. The inserted reinforcing material that forms the rim (2) is a piston It is joined to the main body part t3J. The insertion reinforcing material (2) is attached with multiple leg members (4). These legs are each screwed into the reinforcement (2) at one end. Most of the gas is embedded in the skirt of the piston. Each leg material (4) is other If the end is a hakamaku (5) and the enlarged part looks like a childish one, the material is spout. carbonless steel or copper alloy.

Alternatively, all of these leg members may be of irregular shape.

If the piston is conventionally cast using the crown-mounted method, a push-in reinforcing material (2 ) is suspended over the top of the mold, and the melt-resistant aluminum alloy is placed around the top of the mold. Do not imitate □Such operations may interfere with accurate positioning of the reinforcing material (2). vinegar.

In order to avoid such positioning problems, the present invention uses the crown under-fitting method to fix the pin. A stone is cast.

However, since the recessed combustion chamber il+ is quite deep, the thickness of the piston crown is Please note that the size is also quite large.

Therefore, if you simply perform the crown attachment method, the piston will pass through the relatively thin wall of the piston. The casting technique required a large amount of molten metal to be poured into the crown for the crown. This may eventually lead to the formation of porosity in the thin-walled parts of the casting.

This problem can be solved by taking either of the following two methods that can be selected in this invention. It is solved by

That is, the first method is to place the insertion reinforcing material (2) at the bottom of the die for die casting. In this method, the piston is cast using the crown-subposition method. In order to suppress the occurrence of nests Pressure is applied to the injected alloy (C) before solidification is completed. It is given by the casting method or the compression casting method. The piston obtained in either case is The shape is shown in Figure 2, forming a re-inflow type recessed combustion chamber as shown in Figure 1. As much as possible, machining is performed on this piston.

In the second method d:, a piston is manufactured using billet as tl-1 starting material. Ru. This billet was roughly cut into a shape suitable for the reinforcement material and its industrial soil leg material. Afterwards, it is placed in a mold and placed on top of the reinforcing material and leg material. In other words, the main body of the piston The reinforcing material is also placed in the mold on top of the crown. then top The billet is heated to a temperature suitable for forging, and the reinforcing material legs and piston main body are A forging operation is performed to ensure a completely strong joint. As a result of such forging, The piston provided is also as shown in FIG. Following the forging operation h-1 This piston has been machined to form a combustion chamber on the piston crown. is considered to be a finished product as shown in Figure 1.

- The above two methods have the same problem as above, although they have a structure other than that shown in the attached drawings. It is obvious that this prediction can also be applied to the type of piston that is expensive.

The method of the present invention, which was explained in January a) substantially completely preventing the formation of cavities in the thin-walled parts of piston castings; b) Reinforcement (-4 11 legs) (metallurgical or mechanical for τ) minute zygotic deaf whole character i1 C) Bringing about the effects of improving the mechanical properties of the casting alloy as the base material. It should be obvious.

The main purpose of this invention is to imitate the tlE of the mutual positioning of each part of the piston, and to The overall structure is solid ('C), but this invention It also has the effect of reliably fixing the regional VC, which allows for metallurgical bonding (i.e. Reduces dependence on intermetallic compounds (between aluminum alloy and leg metal) can do. Therefore, copper alloy reinforcements and leg materials were previously considered indispensable. It does not necessarily require a preparatory bonding operation as was thought.

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Claims (1)

[Claims] 1. A method of manufacturing a light metal alloy piston having reinforcing metal inserted on the top surface, the method comprising: , the light metal alloy i3+ of the piston on top of the above-mentioned insertion reinforcement (2), this light metal The alloy is molded around the reinforcement to form a strong bond between the two. By introducing the piston under high pressure conditions, the piston can be fully formed with the crown in place. A method characterized by: 2. AT The above-mentioned light metal alloy is formed into a billet, and this ff: This billet '2 is roughly cut into a shape that is compatible with the reinforcing material inserted above, and then the reinforcing material is After placing it on top of the alloy, the metal is placed on top of the alloy to ensure a strong bond between it and the alloy. Claim 1, characterized in that the steel is completely forged. method described in. :3. The above light metal alloy is inserted and repaired by pressure die casting or compression casting. Claim 1. The invention is characterized in that it is firmly joined to a reinforcing material. method described in. 4.Claim 1. Where an aluminum alloy is used as the light metal alloy. do not have 3. method described in any of the above. . 5. Veryricum copper alloy and copper-nickel-silicon system as insertion reinforcing material for 'lUJ' Claims 1. Either raw or raw. The method described. 6. For the above-mentioned insertion reinforcing material, mechanically connect it between the reinforcing material and the light metal alloy. Claim 1. A plurality of leg members (4) are provided. or 5. written in one of Method. 7. When the above-mentioned light metal alloy is in a state after solidification after forging or casting, Recessed combustion chamber fil (i: the reinforcing material reinforces the chamber periphery at the crown of the piston) Claims 1. or 6. of Any of the methods listed below. 8. Claim 7. The combustion chamber is formed into a re-inflow type. method described in. 9. Range of packed ice 1. or 8. Light metal manufactured by any of the methods described in Alloy piston.