JPS5982156A - Production of piston for internal-combustion engine - Google Patents

Abstract

PURPOSE:To produce a piston which is free from cracking and seizure and is highly resistant to wear by pressurizing a composite material composed of a semimolten light alloy material and short fibers, etc. in a metallic mold by means of a punch from above thereby forming a rough shape material for a piston. CONSTITUTION:A circular cylindrical composite blank material 5 consisting of a light alloy material, such as aluminum, and short fibers of Al2O3, etc. or whisk kers of SiC, etc. having high resistance to heat and wear is heated to make the light alloy material in the blank material in semimolten state. The semimolten material is disposed in the bottom of an approximately circular cylindrical cavity 7 of a metallic mold 6 open at the top and is pressurized from above by means of a pressurizing punch 8 having a bottom end 10 formed to the outside diameter smaller than the outside diameter of said material 5. A recess 2 on the rear side of the piston into which the end of a connecting rod is inserted is thereby formed; at the same time, the short fibers or the whiskers in the material 5 are oriented vertically whereby a rought shape material for the piston is obtd. The rough shape material is removed from the mold 6 after solidification and is worked with desired rings 1, etc., whereby the piston for an internal combustion engine consisting of the composite material composed of fiber and light alloy is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of manufacturing screws 1 to 1 for internal combustion engines, which are mainly made of light alloy material f'l.

Conventionally, Uchisoba (screws 1 to 1 for 4 bolts and C has been made lighter,
Light alloy materials such as aluminum alloys are often used for the purpose of reducing n-forces. However, light alloy materials generally have lower strength, especially lower creep strength, than iron or the like, and also have the problem that cracks are likely to occur at the bottom of the ring groove. In other words, the piston for opening the inner furnace is generally placed on the outer peripheral surface as shown in Fig. 1. 1! On the other hand, a large four-part (cavity) 2 is formed on the back surface m (lower surface side) of the piston into which the end of a connecting rod (not shown) is inserted, and the recess rgI2 is formed in the ring groove 1. Since the ring groove 1 is formed to a height close to 1 corresponding to the height [1], a wall portion having a predetermined thickness is formed between the bottom of the ring groove 1 and the inner surface of the four parts 2. For this reason, as shown in the figure, cracks 4 are likely to occur at the bottom of the ring groove 1 due to the stress caused by the lifting of the engine.
It becomes unusable at 7.

In order to prevent the occurrence of cracks at the bottom of the ring groove and the resulting decrease in N durability, in conventional screws made of light alloy material yPI, the wall thickness of the ring Mli' is increased. However, if the wall thickness is increased in this way, the lfi of the piston will be increased to 11, resulting in the advantage of using light alloy materials. There is a problem that the performance is not fully demonstrated.

In addition, alloy materials f''!I such as aluminum have lower wear resistance than iron, etc. Therefore, pistons made of light alloy materials have the disadvantage of easily causing wear on the outer circumferential surface, and furthermore, have a high thermal elongation. !It is easy to burn out anywhere in the cylinder, especially between the top land of the screw and the cylinder, and the melting point is low and the heat resistance of rTI is poor, so there is a problem that melting damage is easy to occur. Conventional measures to prevent seizing and melting damage have been to widen the top land width and increase the heat capacity of that area. Problems such as an increase in the thickness and occurrence of fluffing occur. Also, in order to prevent seizure, the clearance between the piston and cylinder is increased, but in this case, 8L of oil is required.
¥? Increase in N or increase in noise by 1? (There is a problem.

Furthermore, in order to prevent the occurrence of melting damage and seizure, Alsil alloy is sometimes cast around the outer circumferential surface of the piston, but in this case, there is a problem that the Alsil alloy layer on the casting hole tends to peel off, and the Alsil alloy layer is easily peeled off. There is also the problem of reduced productivity due to poor castability and workability.

This invention was made in consideration of the above circumstances, so it effectively prevents the occurrence of cracks at the bottom of the ring groove and the resulting decrease in durability without significantly covering the thickness of the bottom of the ring groove, and provides +t
In addition, it improves the wear resistance of the outer peripheral surface of the piston and prevents seizure without causing the problems mentioned above. Light alloy material that effectively prevents 77 losses? 1 main body screw]-
There are some that aim to provide a method for manufacturing a product.

That is, the method for manufacturing internal combustion bolt screws 1 to 1 of the present invention heats a cylindrical composite material in which a light alloy material and short fibers or voice car are integrated, and half the light alloy material in the material is heated. The composite material in a molten state is housed in a preheated mold having a substantially cylindrical cavity with an upper surface distance of 1", and the lower end is made to have an outer diameter smaller than the outer diameter of the material. Pressure is applied from the Leahy side to the h0 pressure bandage, and at the same time, the short fiber or voice car is 1. −
By orienting the light alloy downward and taking it out from the mold after the light alloy is completely solidified, a piston in which the short fibers or voice car and the light alloy are compositely integrated is made. The entire structure is made of light alloy composite material, which improves wear resistance and heat resistance, suppresses thermal expansion, and prevents sintering. By orienting the piston in this way, the piston can effectively prevent cracks from forming at the bottom of the ring groove.

The method of the present invention will be explained in more detail below.

In the method of the present invention, first, a cylindrical composite material 5 (see FIG. 2) made of a navy blue/light alloy composite material in which a light alloy material and a γ, 9 chain or whisker are integrated is prepared and covered. The material 5 can be prepared by any method, but after completely melting the light alloy material, the light alloy material is stirred while stirring the light alloy molten metal so that the short fibers or voice car are dispersed as uniformly as possible inside the ladle. The light alloy is cooled to a temperature between the liquid phase and the solidus line to form a nearly uniform coexistence state (semi-molten state), and the required amount of short fibers or voice car is added to the semi-molten light alloy. It is desirable that the mixture be stirred to a uniformly mixed state and then cooled to a humidity below the common phase line to completely solidify. In the semi-molten state described above, the viscosity is high, so the added short fiber shoulder or voice car is uniformly offshored without settling due to gravity.
Therefore, a composite material in which short fibers or small iskers are uniformly dispersed can be obtained.

Up)! Short 469 used in composite material 5 such as 1S
It is desirable to use whiskers that have high heat resistance (high temperature strength) and abrasion resistance, and whose thermal expansion skewers are superior to light alloy material RJL.From these points of view, short fibers such as △Q203 (Alumina), 8Q
It is preferable to use 203-8ho2 (alumina siliph j), carbon circular phase, etc., and as a whisker, S
i C (ashed silicon M>, silicon nitride (Si3N4)
, K2 Tre O+g (titanium n'd>'Jum), etc. is preferably used.Also, it is preferable to use a material such as K2 Tre O+g (Titanium n'd>'Jum).Also, the blending ratio of Chisa 1f (t or voice car) Ll in the composite material 5 is about 10 to 60%. It is desirable that the content be less than 10%, the desired effect will not be achieved in the piston of the product, and on the other hand, it is difficult to uniformly mix more than 6o96 on an industrial scale. M, and productivity decreases.

Note that it is desirable that the outer diameter of the cylindrical composite material 5 be smaller than the inner diameter of the mold 6 in the forging process described later by a certain culm degree. Of course, in actual manufacturing, a composite material block of any shape and size may be created, and a cylindrical material 5 having a predetermined outer diameter may be cut out from the block.

The composite material 5 as described above is heated to bring the light alloy, which is the 7 trix in the C material, into a semi-molten state again. That is, the light alloy is heated to a moisture content intermediate between the solid phase v4 degrees and the liquidus line to bring the light alloy into a solid-liquid coexistence state.

Then, the material 5 is kept in a state of leakage for a required period of time so that the entire material is uniformly in a solid-liquid coexistence state.In this state, the material 5 is soft as a whole, but it is in a state where it can maintain its shape.

Next, as shown in FIG.
This is placed at the bottom of a preheated mold 6 having a cylindrical cavity 7 with a corresponding inner diameter, and immediately pressurized 1) 11 from above with a pressure punch E) as shown in FIG. ) Do old. Here, press the pressure punch 8 and press tj.
, the outer shape of the lower part 9 is the final [this 17 screw 1]
21. Use a connecting rod shaped to correspond to the white shape of the recess 2 (shown in Figure 1) for inserting the connecting rod into the throat at a temperature of 11°C. Also, the lower tip of the pressure punch 8, that is, the lower end 1'! The first diameter of l110 is set to be smaller than the diameter of the compound mf451. If the total size is 1 ton, make the outer diameter of the composite material 5 larger than the lower part of the Fin pressure bumper.

When the composite material 5 in the lukewarm temperature Bg state is subjected to a pressure of 11 [1] using the pressurizing punch 8, as shown in FIG. A part of it flows upward between the outer surface of the pressure punch lower part 9 and the inner circumferential surface of the mold 6 and fills the space therebetween. Here, 7 pieces of M material '''l short cloth I) or small isker 1
1 is the flow of the composite material r1 when pressurized. As a result, the direction of orientation of the isker 11 is almost the same as the direction of flow. In other words, The short structure [t or the voice car 11 is oriented in the vertical direction along the inner peripheral surface of the mold, that is, in the direction parallel to the axis.

Above) The light alloy in the viewing material is heated under pressure as shown in the figure.
■ After solidification and complete solidification, take out from the mold 6 and heat-treat the screw 1-shaped rough shape material as needed, or perform machining for ring groove formation, etc. (4). You can get screws that are as long as you want.

'' In a piston with a double series (1r4), as shown in Fig. 6, the piston is
, i (+The orientation direction of the small chair 11 is along the -9 downward direction (that is, the direction parallel to the 'l'llll bag).Here, the conventional light alloy material f'' +↑11
As shown in FIG. However, in the screws 1 to 1 of this invention, short fibers or (1 whiskers 11) are combined, and the orientation direction of Since is parallel to the shaft frame direction, the tensile strength in the direction parallel to the @ line direction is extremely high, and therefore the generation of tortoise 1 at the bottom of the ring groove can be effectively prevented.

In addition, the abrasion resistance effect is increased by 1q due to the composite integration of the chisel or whisker in the bis 1~n which has been improved by 1q according to this invention, but in addition to that, the short v11 as mentioned above also has a wear resistance effect of 1q. Wear resistance is further improved by the orientation of the whiskers. In other words, the wear on the outer circumferential surface of the piston is caused by the IM-force in the direction along the line direction between the screws 1 and the cylinder, while the short 111 ft or the screws are oriented in one direction. 1! Composite H has extremely high wear resistance in the orientation direction of A.

Therefore, by matching the orientation direction and the co-movement direction,
Piston wear can be effectively prevented from the start.

Furthermore, in the case of the lζ piston, which is made in the same way as the previous jd;, use 'fJ7 #5't(t or a small isker whose coefficient of thermal expansion is smaller than that of the light alloy material v+1. As a result, the coefficient of thermal expansion of the composite material as a whole is lower than that of the light alloy alone, and as a result, the piston outer diameter is prevented from expanding due to thermal expansion. Seizure is effectively prevented.In addition, the heat-resistant composite material made by combining Hoisuno J-7 with a light alloy has better heat resistance than the 1Q combination of light alloy alone. Therefore, in the piston manufactured by the method of the present invention, it is possible to effectively prevent the top land and the top surface of the screw from melting.

An example will be described below in which the method of the present invention was applied to the production of a screw I~n with an outer diameter of 85ml for a 1800cc four-cylinder gasoline engine.

Example JIS AC8Δ aluminum-containing molten metal was heated and melted in a graphite crucible, and gradually cooled while stirring before complete melting, and when the in-phase ratio reached approximately 60%, Si3N4 hole scar was added at a volume ratio of 1096. The mixture was stirred and mixed thoroughly, and then further cooled to completely solidify the composite material blocks.
A qmm cylindrical material was cut out. This cylindrical material was heated to adjust the temperature so that the homophase ratio of the aluminum alloy as a 71 helix was approximately 4096, and was held at that temperature for approximately 30 minutes. Take this out of the furnace and fft NN
Approximately 350" corresponding to the hen shape
The mixture was oriented at the center of the bottom in a mold (inner diameter 86 mFl) heated to C, and immediately pressurized with a pressure plunger at a pressure of 150 tons while in a semi-molten state.
The pressurized horn was held until completely solidified, and then removed from the mold. Part 1 T6 fever 91J FIId3 and t
Qf = 1 addition] and the final piston is 1rf.

According to the above-described embodiment, a piston 17 made of a composite material in which Si3N+ whiskers and aluminum alloy are integrated is produced, and on the outer peripheral surface of the piston, Si3N4 whiskers are oriented in a direction substantially parallel to the axial direction. It was FflH that it was. In this example, J
: When the obtained piston was assembled into an engine and an actual rIt test was conducted, a crack appeared at the bottom of the ring groove.
It was also confirmed that there was almost no seizure or melting damage to the cylinder, or wear on the outer peripheral surface.

As is clear from the above explanation, the manufacturing method of the present invention includes J:
If so, it is possible to obtain an excellent screw ring that has extremely low risk of cracking at the bottom of the ring groove, has high wear resistance on the outer circumferential surface, and is less likely to cause burns or melt damage. can. In addition, in the 21 manufacturing method of the present invention, the above-mentioned excellent characteristics can be achieved by combining the light alloy such as chim fft or voice car and the direction of orientation of the chim fft or whisker. Measures to prevent groove cracking, wear resistance -V or seizure,
Like a lifting platform to prevent erosion and damage, it also has the effect of not increasing the piston II, increasing the engine height, increasing oil consumption, increasing noise, or causing peeling of some layers. It will be done.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing an example of a conventional screw line made of light alloy material, and Figs. 2 to 5 show an example of the IF4 manufacturing method of the present invention in stages. Fig. 2 is a perspective view of the material, Figs. 3, 4 and 5 are schematic cross-sectional views showing the situation during semi-molten forging, and Fig. 6 is a bismine which has been forged by the manufacturing method of the present invention. FIG. 1...Ring groove, 2...Four parts on the back side of the piston,
5... Composite material, 6... Mold, 7... Cavity, 8... Pressure piston, 11... Knowledge
ft or voice car. Applicant Toyota Motor Corporation Representative Patent Attorney Yutaka 1) Hisashi Take (and 1 other person)

Claims (1)

[Claims] A cylindrical composite material in which the light alloy material r1 and short crosspiece fibers or whiskers are compositely integrated is heated to bring the light alloy material in the material into a semi-molten state, and the composite material in that state is heated. The material is housed in a mold with an approximately cylindrical cavity and an n-sided top, and is pressurized from above using a pressure punch whose lower end has an outer diameter smaller than the outer diameter of the composite material. The lower part of the pressure punch forms the back side opening of the screws 1 to 1 into which the connecting rod ends are inserted, and at the same time forms the Ln f? in the composite material. Internal combustion 11 Kadokawa piston made of fiber/light alloy composite material, characterized in that the i-line or voice car is vertically oriented along the inner surface of the mold and taken out from the mold after the light alloy is completely solidified. J
Construction method.