JP2006110621A - Method for producing aluminum alloy-made die-forged product, and aluminum alloy-made preformed article for warm die-forging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the generation of burr at the time of die-forging, to simultaneously make high-strengthening and fining of recrystallized grain in the die-forged product and further, to reduce the cost for die-forging. <P>SOLUTION: An aluminum alloy round blank 5 is heated and a cross-rolling work is applied at the warm temperature to this blank, and after obtaining a preformed article (shaft 6 with step) having a volume distribution resembled to the die-forged product, the warm die-forging is applied to the shaft 6 with step by loading the pressurizing force in the perpendicular direction to the axial direction in order to obtain the die-forged product (double-head piston 1 in a swash plate type compressor for air-conditioning). In the double-head piston 1, the large stress is introduced as the total by applying the cross-rolling work and the die-forging at the warm temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improved method for producing an aluminum alloy forged product.

  Forged products made of aluminum alloy, for example, as described in Patent Document 1 below, are generally made by cutting an aluminum alloy round bar (extruded bar or cast bar) into a predetermined length, and this round bar is heated. Manufactured by die forging. However, when manufacturing a forged product whose axial length is longer than the cross-sectional size and whose cross-sectional area varies greatly in the axial direction, if the round bar material is used as it is as a forging material, burrs will appear greatly. There is a problem that the yield of the material is lowered.

  On the other hand, as described in the following Patent Documents 2 and 3, in the field of steel materials, a round bar material cut into a predetermined length is hot roll forged so that the volume distribution approximates that of a die forged product. It is known that a stepped shaft is preformed and the preform is further forged by hot. This preform is called a near net shape material or preform. When die forging is performed using this near net shape preform, there is an advantage that the generation of burrs is suppressed and the yield of the material is improved. However, this method requires repeated roll forging a plurality of times before obtaining a near net shape preform, resulting in poor productivity, and poor molding accuracy, particularly poor axial molding accuracy. is there.

  Furthermore, as described in the following Patent Documents 4 and 5, in the field of steel materials, a round bar material cut into a predetermined length is hot cross-rolled to obtain a volume distribution that approximates a die forging product. It is also known to preform a stepped shaft as described above, and die forge the preform further hot. In cross rolling, a heated round bar material is inserted between a pair of rolls having a convex forging die formed on the peripheral surface with the axial direction parallel to the axial direction of the roll, and the rolls are the same. This is a type of rolling process in which a stepped shaft is formed by making a round bar material bite into the convex part of a forging die in one direction. In this method, the problem of the roll forging is improved.

  JP 2003-231016 A   Japanese Patent Laid-Open No. 11-347680   JP-A-6-277787   JP 2000-158079 A   JP-A-8-132165

Even in aluminum alloy forgings, instead of directly forging a round bar material, a near-net-shaped preform is accurately formed by cross rolling, and die forging is performed by using this to forge. The yield of the material should be able to be suppressed, thereby reducing the cost of the die-forged product.
However, when the cross rolling process is performed hot on an aluminum alloy round bar and then die forging is performed hot, the total amount of strain that can be introduced into the forged product is small, and the strength of the forged product is insufficient. It becomes. In the case of heat-treatable aluminum alloy, it is possible to increase the strength by solution treatment and aging treatment after die forging, but if the amount of strain introduced is small, the recrystallized grains after solution treatment are difficult to be refined and fatigue strength is reduced. May decrease. Furthermore, in order to perform the cross rolling process and the die forging hot, a heating furnace capable of heating the aluminum alloy round bar to a high temperature is required, which is a factor for increasing the cost of the die forging product.

  The present invention has been made in view of the above-mentioned problems when a near net shape preform is obtained from an aluminum alloy round bar and die-forged, and the near net shape preform is obtained with high accuracy and Obtained with high productivity, reducing the occurrence of burrs when die-forging this preformed product, while at the same time making the die-forged product stronger and recrystallized grains smaller, further reducing the cost of the die-forged product It aims to plan.

  According to the knowledge of the present inventor, according to the cross rolling process, a preformed product (stepped shaft) can be obtained without problems by processing an aluminum alloy round bar warm. In addition, by using a near net shape preform as the material for die forging, the deformation amount of die forging is greatly reduced compared to the case of forging a round bar as it is, and the deformation resistance (reaction force) is also reduced. Warm forging can be used. Then, by performing both the cross rolling process and the die forging warm, the amount of strain introduced into the die forging product increases, and it becomes possible to increase the strength and refine the recrystallized grains. The present invention has been made based on this finding.

The method for producing an aluminum alloy die forging according to the present invention is a method of heating an aluminum alloy round bar and performing a cross-rolling process in a warm manner, and setting a radius along the axial direction so that the volume distribution approximates that of the die forging. After obtaining the changed preform (stepped shaft), the preform is warm die forged by applying pressure in a direction perpendicular to the axial direction. In this manufacturing method, for example, the preform is a stepped shaft having a large-diameter portion at both ends, a small-diameter portion at the center, and a tapered portion therebetween, and having a symmetrical shape in the axial direction. This is a double-headed piston of a swash plate compressor.
In addition, the aluminum alloy preform for warm die forging according to the present invention is obtained by cross-rolling an aluminum alloy round bar warmly and along the axial direction so that the volume distribution approximates that of the die forged product. It is a stepped shaft with a changed radius.

According to the present invention, a preform of a near net shape (stepped shaft) can be obtained from an aluminum alloy round bar with high accuracy and high productivity, and burrs are generated when the preform is forged. Can be reduced. In addition, since cross-rolling and die forging are performed not hot (approximately 350 to 450 ° C.) but warm (approximately 200 to 330 ° C.), there is no need for a high-temperature heating furnace for heating the bar material, and the die forging product. The cost of Furthermore, by performing both the cross rolling process and the die forging warm, the total amount of strain introduced into the die forging product increases, and it becomes possible to increase the strength and refine the recrystallized grains.
In addition, since the reaction force at the time of warm die forging is small by using a preform, and the temperature of die forging is low, an inexpensive forging die can be used compared to that for hot. Cost reduction can be achieved.

Hereinafter, the present invention will be described in detail with reference to FIGS.
FIG. 1C shows a double-headed piston 1 (forged product) of a swash plate compressor for air conditioning, which has sliding contact portions 2 having a circular cross section on the left and right sides, and a swash plate and a shoe (not shown) arranged at the center. There is a recessed portion 3 that is symmetrical with respect to the axial direction. Spherical recesses are formed in the left and right seats 4 of the recess 3 so that the shoe comes into spherical contact. The double-headed piston 1 is made of, for example, a high Si-based aluminum alloy (for example, Si content of 6 to 12%) that is lightweight and excellent in wear resistance and machinability.
In manufacturing, as shown in FIG. 1A, an aluminum alloy round bar (casting bar or extruded bar) is cut into a predetermined length to obtain a round bar material 5, and then this round bar material 5 is 250 to 300. Heated to ° C., and formed into a stepped shaft 6 shown in FIG. 1B by warm cross rolling.

As shown in FIG. 2, the cross rolling processing apparatus includes a pair of rolls 9 and 10 each having a convex forging die 7 and 8 formed on the peripheral surface, and rolls the heated round bar material 5 in the axial direction. The rolls 9 and 10 are rotated once in the same direction, and the convex portions of the forging dies 7 and 8 are bitten into the round bar material 5 to form the stepped shaft 6. is there. The stepped shaft 6 includes a large diameter portion 6a at both ends, a small diameter portion 6b at the center, and a tapered portion 6c therebetween. The stepped shaft 6 has a symmetrical shape in the axial direction and approximates the die forging product (double-headed piston 1). Have an allocation.
Subsequently, the stepped shaft 6 is heated again to 250 to 300 ° C., or warm die forging by a semi-sealing die is performed as it is using the residual heat of the cross rolling process, and the forged product shown in FIG. Molded into a double-headed piston 1). FIG. 1C shows a state after deburring.

  According to this method, by using a near-net-shaped preform (stepped shaft 6), the generation of burrs is suppressed, and at the same time, the double-headed piston 1 is required to have the highest strength, wear resistance and fatigue resistance. A large amount of strain is introduced into the portion of the seat 4 by a cross rolling process and die forging performed warm.

  It is a perspective view explaining each process of the manufacturing method of the aluminum alloy die forgings which concerns on this invention.   It is the side view and perspective view explaining a cross rolling process.

Explanation of symbols

1 Double-head piston (forged product)
5 Round bar material 6 Stepped shaft (Preliminary product)
7,8 Forging die 9,10 roll

Claims (3)

  The aluminum alloy round bar is heated and cross-rolled warmly to obtain a preform with the radius changed along the axial direction so that the volume distribution approximates that of the die forging. A method for producing an aluminum alloy die forging, characterized by applying a pressure force in a vertical direction to warm die forge the preform.   The preform is composed of a large diameter portion at both ends, a small diameter portion at the center, and a tapered portion therebetween, and is a stepped shaft that is symmetrical in the axial direction, and the die forging is a double-headed swash plate compressor for air conditioning It is a piston, The manufacturing method of the aluminum alloy die forgings described in Claim 1 characterized by the above-mentioned.   Aluminum for warm die forging, characterized in that aluminum alloy round bars are heated and cross-rolled warmly, and the radius is changed along the axial direction so that the volume distribution approximates that of die forgings. Alloy preform.

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