JP4355431B2 - Piston manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piston for producing how that were distributed functionality that is suitable for use environment component composition by grading in the material.
[0002]
[Prior art]
As a method of manufacturing a functionally gradient material, a manufacturing method using a pulsed current pressure sintering method including a discharge plasma sintering method, a discharge sintering method, a plasma activated sintering method, or the like proposed by the present applicant is known. It has been. That is, a raw material filling hole made of a conductive material such as graphite that penetrates in the central axis direction, a small diameter portion and a large large diameter portion that are separated from each other in the axial direction and have a small outer diameter, and the small diameter portion and the large diameter portion Using a die with an irregular shape with a taper between the two or more kinds of mixed powders in the raw material filling hole of this die with their blending ratios etc. being different in the central axis direction and sequentially laminating , A pair of upper and lower punches made of conductive material such as push rod graphite is inserted and pressed from both sides of the die filling hole, and the mixed powder is compressed into a green compact. Directly on / off DC pulsed voltage / current is applied to manufacture functionally gradient materials. In this sintering method, a micro spark discharge phenomenon occurs at the initial stage of energization, and the powder particle surface is purified and activated by the sputtering effect of the discharge impact pressure. Is believed to progress. The main sintering driving force during energization to late phase is Joule heat and time and plastic deformation pressure due to pulse energization of the powder and sintering mold (die, punch) as a whole. To promote the progress of sintering. At this time, the electric resistance (R) of the fixed resistance (α) conductor is proportional to the length (L) of the conductor and inversely proportional to the cross-sectional area (S). R = α (L / S). Further, the work (W) performed by the current (I) at time (t) is represented by (W = I2 × R × t).
[0003]
For this reason, the calorific value becomes large at the part having a small cross-sectional area of the die, while the calorific value becomes small at the part having a large cross-sectional area, thereby causing a temperature gradient and a difference in sintering temperature. Thus, a functionally gradient material having a desired function is obtained.
[0004]
[Problems to be solved by the invention]
However, the conventional method for producing a functionally gradient material has the following problems.
[0005]
That is, even when the discharge plasma sintering method is used, when the mixed powder laminated in the raw material filling hole of a die such as a die having a straight uniform cross section is a mixed powder of conductive metal, pulse energization is performed. It is carried out through a mixed powder of metal. For this reason, the mixed powder of metal is directly and simultaneously heated, and a temperature gradient cannot be developed, and a desired functionally gradient material cannot be produced.
[0006]
In addition, in the case of using a temperature gradient and irregularly shaped die that varies the electrical resistance depending on the cross-sectional area difference of the die and has a difference in the heat generation amount, melting between the mixed powders laminated in the raw material filling hole of the die When there is a large difference in temperature, it is difficult to form a difference in cross-sectional area that gives a difference in calorific value on the die, and a high sintering temperature substance (powder) and a low sintering temperature substance (powder) The interval between the layers cannot be reduced.
[0007]
Furthermore, in order to make the heat generation amount different by changing the electric resistance by the cross-sectional area difference, the die having an irregular shape as described above is necessary, so that it is difficult to process the die and it is necessary to process the die. Cost will increase.
[0008]
The present invention has been made in view of the foregoing, it is an object in the case of using a mixed powder of a metal with electrical conductivity, and have high sintering temperature of the powder and a low sintering temperature powder it is to provide a narrowing of the interlayer spacing, type producing how the piston can be achieved cost reduction of the workability of simplicity and cost (die) a.
[0009]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the piston manufacturing method according to claim 1 is the method comprising the steps of filling an upper intermediate layer after filling an aluminum alloy piston main body with an aluminum-silicon rapidly solidified powder as a lower intermediate layer. mixed powder of titanium powder and aluminum powder as filled and then, at different mixing powder and mixing ratio of the upper intermediate layer Rutotomoni, titanium as a top layer of high sintering temperature than the mixed powder of the upper intermediate layer Filled with powder and mixed powder of aluminum powder, pulsed current pressing by discharge plasma sintering method is applied to the laminated piston body, aluminum-silicon rapidly solidified powder, and upper and lower mixed powder, and the uppermost layer is mixed The upper intermediate layer is formed by using the heat generated by the exothermic reaction when the intermetallic compound is produced by the powder and the intermetallic compound is produced. The mixed powder and the lower intermediate layer aluminum-silicon rapid solidified powder are sintered, and the intermetallic compound and the upper intermediate layer, the upper intermediate layer and the lower intermediate layer, and the lower intermediate layer and the piston body are sintered and joined. It is characterized by this.
[0010]
Thus, an aluminum alloy piston body, an aluminum-silicon rapidly solidified powder as a lower intermediate layer, a mixed powder of titanium powder and aluminum powder as an upper intermediate layer, and a mixed powder of an upper intermediate layer The mixed powder of titanium powder and aluminum powder as the uppermost layer with different rates is pulsed by the whole die and punch while being pressed by a push rod punch inserted from both sides of the raw material filling hole of the die. It is heated by doing. Then, the mixed powder in the uppermost layer generates heat due to the heat generated by the pulse current in the entire die and punch, and an intermetallic compound is generated. At this time, the heat of the exothermic reaction of the intermetallic compound is used in combination to sinter the mixed powder of the upper intermediate layer and the aluminum-silicon rapidly solidified powder of the lower intermediate layer. The piston main body is sintered and joined via the upper and lower intermediate layers . Thereby, the intermetallic compound having a high sintering temperature and the piston body made of aluminum alloy are simultaneously joined via the upper and lower intermediate layers having a low sintering temperature, thereby producing a piston having a desired gradient functionality . In addition, it is possible to significantly reduce the time required for the production.
[0011]
Moreover, the piston body made of aluminum alloy is moved through the upper and lower intermediate layers having a low sintering temperature by the exothermic reaction of the mixed powder (intermetallic compound) having a high sintering temperature heated during the pulse energization of the entire die and punch. By joining with an intermetallic compound, it becomes possible to narrow the space | interval between layers of an intermetallic compound and the piston main body made from an aluminum alloy .
[0012]
In addition, there is no need for an irregularly shaped die that changes the electrical resistance due to the difference in cross-sectional area, and the amount of heat generation is not required, so that the die can be easily formed and the cost for processing the die is greatly reduced. It will be.
[0013]
Also, by sinter-bonded intermetallic compound via an intermediate layer of the upper and lower piston body made of aluminum alloy, it is possible to reduce the heat resistance of the piston top.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
Figure 1 shows a piston which is produced by using the piston production method according to an embodiment of the present invention.
[0017]
In FIG. 1, a piston 1 is made of a functionally graded material in which the component composition in the material is graded and functions suitable for the usage environment are distributed in four layers. Specifically, the piston 1 includes an intermetallic compound 11 made of TiAl (titanium aluminum) provided on the topmost side (combustion chamber side not shown), and a piston rod side of the intermetallic compound 11 (in FIG. 1). The lower intermediate layer 12 connected to the lower intermediate layer 12, the lower intermediate layer 13 connected to the piston rod side of the upper intermediate layer 12, and the piston rod side of the lower intermediate layer 13 It is formed in four layers with a metallic material 14 made of aluminum alloy.
[0018]
The intermetallic compound 11 is produced by a combustion synthesis reaction of 50 at% Ti powder (titanium powder) and 50 at% Al powder (aluminum powder), and has very excellent heat resistance.
[0019]
The upper intermediate layer 12 is made of 30 at% Ti powder (titanium powder) and 70 at% Al powder (aluminum powder), and is provided to ensure consistency of thermal expansion coefficients.
[0020]
The lower intermediate layer 13 is a rapidly solidified powder containing a large amount of Si element (silicon element) with respect to Al element ( aluminum element) , has excellent wear resistance, and matches the thermal expansion coefficient. It is provided to take sex.
[0021]
The metal material 14 is an aluminum alloy casting formed by a casting method, and forms a piston body.
[0022]
The lower intermediate layer 13 of the piston 1 is formed with a first piston groove 15 near the most combustion chamber that is close to the intermetallic compound 11 side. In addition, upper and lower second piston grooves 16 and third piston grooves 17 are formed above the metal substance 14.
[0023]
Next, the procedure in the case of manufacturing such a multi-layer piston 1 by the discharge plasma sintering method will be described with reference to FIG.
[0024]
2 and 3 show schematic configuration diagrams of a manufacturing apparatus X used when the piston 1 is manufactured by a discharge plasma sintering method.
[0025]
As shown in FIG. 3, the discharge plasma sintering apparatus X includes a forming die 2 for filling powder and the like, and a pair of upper and lower pressurizing energization punches 22 and 22. Each punch 22 is driven by a pressurizing drive mechanism 32, and a pulse current is supplied by a pair of upper and lower pressurizing energizing punch electrodes 34 and 35 having a built-in cooling water passage 33. Further, the die 2 and each punch 22 are accommodated in a vacuum chamber 37 provided with a vacuum pump 36 in order to prevent oxidation during sintering of powder or the like. Thereby, the inside of the vacuum chamber 37 is maintained at a predetermined degree of vacuum. In this case, the inside of the vacuum chamber 37 may be an argon atmosphere instead of a vacuum.
[0026]
Here, the procedure for manufacturing the piston 1 by the discharge plasma sintering method will be described.
[0027]
First, as shown in FIG. 2, a substantially cylindrical die 2 having a raw material filling hole 21 penetrating in the central axis direction and made of a conductive material such as graphite is prepared, and the raw material filling hole 21 of this die 2 is prepared. A substantially cylindrical metal material 14 made of an aluminum alloy casting is inserted therein, and this metal material 14 is used as the lowermost layer.
[0028]
Next, rapidly solidified powder containing a large amount of Si element (silicon element) with respect to Al element is filled on the upper side of the metal material 14 so that the lower intermediate layer 13 is overlaid.
[0029]
Further, a mixed powder of 30 at% Ti powder (titanium powder) and 70 at% Al powder (aluminum powder) is filled on the upper side of the lower intermediate layer 13 so that the upper intermediate layer 12 is overlaid.
[0030]
The upper intermediate layer 12 is filled with a mixed powder of 50 at% Ti powder (titanium powder) and 50 at% Al powder (aluminum powder), and the layer of the intermetallic compound 11 (uppermost layer) is overlaid. Like that.
[0031]
Thereafter, the pressurizing energizing punches 22 and 22 inserted from both sides of the raw material filling hole 21 of the die 2 are set in a vacuum chamber 37 (shown in FIG. 3), and the vacuum chamber 37 is sealed. After the vacuum pump 36 is evacuated or filled with an inert atmosphere gas as necessary, the punch 22 is pressurized in the vertical direction (arrow direction shown in FIGS. 2 and 3) to compress the mixed powder. To make a green compact. Further, a large pulse current of on / off direct current is passed directly to the gap between the green compact particles. This heats the layers 11-14 of each material.
[0032]
Thereafter, when the temperature of the mixed powder of the uppermost 50 at% Ti powder (titanium powder) and 50 at% Al powder (aluminum powder) reaches a predetermined temperature, for example, a temperature equal to or higher than the melting point of aluminum, the mixed powder An intermetallic compound 11 is generated by inducing a combustion synthesis reaction. At this time, the intermetallic compound 11 is sintered by heat generation during generation, self-heating of the powder due to pulse energization, resistance heat generation of the die 2, and pressure, and further, the upper intermediate layer 12 is heated and the upper intermediate layer 12 is heated. And the intermetallic compound 11 is firmly sintered and joined to the upper side of the upper intermediate layer 12. Further, the lower intermediate layer 13 is also sintered by the heat generated when the intermetallic compound 11 and the upper intermediate layer 12 are generated, the self-heating of the powder by pulse energization, the resistance heat generation of the die 2, and the applied pressure. The upper intermediate layer 12 is firmly sintered and bonded to the upper side of the layer 13, and the lower intermediate layer 13 is strongly sintered and bonded to the upper side of the metal material 14. As a result, the component composition in the material is inclined in order for each of the layers 11 to 14, thereby obtaining the piston 1 having the inclined functionality in which the functions are distributed suitable for the use environment. In that case, the pulse energization time required for the production of the piston 1 is such that the layers 11 to 14 are energized directly and the heat generated by the combustion synthesis reaction of the intermetallic compound 11 is used in a composite manner. Even if the cooling time is taken into account, it can be accommodated in about 10 to 20 minutes.
[0033]
At the same time, the first piston groove 15 is formed in the lower intermediate layer 13, and the upper and lower second piston grooves 16 and the third piston groove 17 are formed above the metal substance 14.
[0034]
Therefore, in this embodiment, the intermetallic compound 11 having a high sintering temperature and the metal material 14 made of an aluminum alloy having a low sintering temperature are simultaneously bonded together with the sintering of the upper and lower intermediate layers 12 and 13 to obtain a desired gradient. A piston 1 made of a functional material can be generated. Further, the time required for manufacturing the piston 1 is only about 10 to 20 minutes, and the manufacturing time of the piston 1 can be greatly shortened.
[0035]
Further, the metal material 14 having a low sintering temperature is sintered by the exothermic reaction of the mixed powder (intermetallic compound 11) having a high sintering temperature heated during pulse energization in the die 2 and the punch 22 as a whole. The spacing between the mixed powder (intermetallic compound 11) having a high sintering temperature and the upper intermediate layer 12, the lower intermediate layer 13 and the metal substance 14 having a sintering temperature lower than that can be narrowed.
[0036]
Further, a large pulse current of on / off direct current is directly applied to the layers 11 to 14 of each material (each powder and metal substance 14), and the heat generated by the combustion synthesis reaction of the intermetallic compound 11 is used in combination. Therefore, the cylindrical die 2 may be used, and a die having a different shape that changes the electric resistance due to a difference in cross-sectional area and has a difference in heat generation becomes unnecessary. Thereby, the die 2 can be easily formed, and the cost for processing the die 2 can be greatly reduced.
[0037]
And the intermetallic compound 11 is easily sintered on the top of the piston body made of aluminum alloy by sintering the intermetallic compound 11 on the top of the piston body (metal substance 14) via the upper and lower intermediate layers 12 and 13. The heat resistance of the piston body top can be achieved.
[0038]
Further, the lower intermediate layer 13 produced by the rapidly solidified powder containing a large amount of silicon element relative to the aluminum element is sintered between the intermetallic compound 11 and the metal substance 14 (aluminum alloy) via the upper intermediate layer 12. As a result, since the first piston groove 15 closer to the most combustion chamber is formed in the intermediate layer 13, the combustion heat from the combustion chamber closer to the intermetallic compound 11 when the piston moves in the cylinder and Wear of the first ring groove 15 due to a load from the piston ring that expands and contracts due to pressure can be effectively reduced.
[0039]
Furthermore, by utilizing the heat generated by the combustion synthesis reaction of the intermetallic compound 11, the pulse energization time required for manufacturing the piston 1 is about 10 to 20 even if the cooling time of the material of each layer 11 to 14 is taken into account. In the lower intermediate layer 13, the coarsening of silicon particles mixed in aluminum is suppressed, and a characteristic characteristic of rapidly solidified powder, that is, a characteristic that silicon is dispersed in aluminum while remaining in the form of fine particles is obtained. Will be. For this reason, it is possible to effectively improve the wear resistance of the lower intermediate layer 13 itself, and to reduce the material cost compared to the case where the wear resistance is increased by using an expensive fiber such as ceramic for the aluminum powder. The cost required for this can be reduced.
[0040]
In the present embodiment, the lower intermediate layer 13 is formed from a rapidly solidified powder containing a large amount of silicon element relative to the aluminum element. However, a 40 at% Ti powder (titanium powder) and a 60 at% Al powder (aluminum powder) are used. And may be produced by a mixed powder. In this case, in combination with the upper intermediate layer 12, it is very advantageous for achieving consistency of thermal expansion coefficients.
[0041]
Moreover, in this embodiment, although the intermetallic compound 11 was produced | generated by the combustion synthesis reaction of 50at% Ti powder (titanium powder) and 50at% Al powder (aluminum powder), 50at% Fe powder (iron powder) and Sintering an intermetallic compound against a metal material by a combustion synthesis reaction with 50 at% Al powder (aluminum powder) or a combustion synthesis reaction between 50 at% Cu powder (copper powder) and 50 at% Al powder (aluminum powder) It can also be applied to cases.
[0042]
Furthermore, in the said embodiment, although the piston 1 was manufactured with the functionally gradient material, it is not limited to a piston, The functionally gradient material which distributed the function suitable for a use environment by inclining the component composition in material. Of course, this method can also be applied to the manufacture of
[0043]
【The invention's effect】
As described above, according to this onset bright, the heat caused by the pulse current in the entire die and punch by heating the mixed powder of the top layer of titanium powder and aluminum powder to produce an intermetallic compound, intermetallic compounds The upper and lower intermediate layers are sintered using the combined exothermic reaction of the metal and the intermetallic compound and the aluminum alloy piston body are joined simultaneously with the sintering of the upper and lower intermediate layers . on can be produced piston having, a time required for the production can be greatly shortened. Moreover, by joining by sintering the low and below the intermediate layer of the sintering temperature of the piston body made of aluminum alloy by the exothermic reaction of high intermetallic compound of sintering temperature, high intermetallic compound of Sintering Temperature and aluminum The distance between the layers of the alloy piston body can be reduced. Furthermore, the die can be easily formed, and the cost for processing the die can be greatly reduced. Moreover, the heat resistance of a piston top part can be aimed at by sintering an intermetallic compound to the top part of a piston.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a piston manufactured using a piston manufacturing method according to an embodiment of the present invention.
FIG. 2 is an explanatory view showing a state of filling each powder in a die and punch and inserting a metal substance when a piston is manufactured by a discharge plasma sintering method.
FIG. 3 is a schematic configuration diagram of a manufacturing apparatus used when manufacturing a piston by a discharge plasma sintering method.
[Explanation of symbols]
1 Piston 11 Intermetallic compound
12 upper intermediate layer 13 below the intermediate layer 14 piston body 15 first piston groove

Claims (1)

After the aluminum alloy piston main body is filled with the aluminum-silicon rapid solidified powder as the lower intermediate layer, the mixed powder of titanium powder and aluminum powder is filled as the upper intermediate layer, and then the upper intermediate layer is filled. Rutotomoni at different mixing powder and blending of the layer, than the mixed powder of the upper intermediate layer was filled with mixed powder of titanium powder and aluminum powder as a high top layer of the sintering temperature, these laminated piston body, When aluminum-silicon-based rapidly solidified powder and upper and lower mixed powders are pulsed and pressurized by the discharge plasma sintering method to produce an intermetallic compound with the uppermost mixed powder, and when this intermetallic compound is produced Combined use of heat from the exothermic reaction of the upper intermediate layer mixed powder and lower intermediate layer aluminum-silicon rapidly solidified powder Together to sinter the intermetallic compound and the upper intermediate layer, the upper intermediate layer and the lower intermediate layer, the piston production method of, characterized in that for joining sinter the lower intermediate layer and the piston body.

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