JPH05123809A - Working method for precise aluminum product having hole - Google Patents

Abstract

PURPOSE:To efficiently form a hole having a high dimensional accuracy by forging or casting a semifinished product and successively correcting the dimension of hole and at the same time, executing plastic working with cold forging. CONSTITUTION:Extrusion is executed to an Al alloy into a hollow rod and this hollow rod is sliced to manufacture a blank 41. Lubricator is coated on the surface of the blank 41 and this blank is heated to 150-350 deg.C and supplied into a die 1 and pressed by a punch 3 to forge the semifinished product having a little larger than the dimension of a product in warm or hot condition. As the other way, the semifinished product is cast by using a mold. After this semifinished product is cooled, lubricating treatment is applied to the surface, and by pressing the other die, the shape and the dimension are corrected and at the same time, the plastic working is executed with the cold forging to obtain the precise Al product having the hole. By this method, the mass- productivity can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision aluminum or aluminum alloy (hereinafter simply referred to as "aluminum") in which all or part of the inner wall is vertical and has holes which require relatively high dimensional accuracy. The present invention relates to a method of processing a product.

[0002]

2. Description of the Related Art For example, a precision aluminum product having a hole for press-fitting a piston of a compressor and a hole for a vertical inner wall surface having a high dimensional accuracy required, such as a receiving plate having a structure for supporting the piston as a whole. In the above, a semi-finished product having a shape close to the product size was processed by warm forging or hot forging, and the hole portion of this semi-finished product was finished by cutting with a ball end mill or the like. This is warm forging (15
This is because the rough working ratio can be obtained by hot forging (300 to 500 ° C.), but the dimensional accuracy cannot be improved.

[0003]

Conventionally, since the hole portion of the semi-finished product processed by warm forging or hot forging has been finished by cutting, it takes a lot of time and labor to cut the cost. Further, for example, when the bottom of the hole is a concave spherical surface, there is a drawback that the cutting process becomes more sophisticated and more expensive. An object of the present invention is to solve the above problems and provide a method for processing a precision aluminum product capable of more efficiently performing hole processing with high dimensional accuracy.

[0004]

In order to achieve the above-mentioned object, the method of the present invention is a step of processing a semi-finished product by warm forging or hot forging at 150 to 350 ° C. with a die having a size slightly larger than the product size. And a step of cold forging this semi-finished product with a die having substantially the same size as the product size.
The temperature selection in warm forging and hot forging is selected depending on the hardness of the material aluminum or its alloy and the complexity of the hole shape. Generally, for soft materials, and when the hole shape is simple and the required dimensional accuracy is relatively low, low temperatures are selected, and vice versa.

In the method of the present invention, if the required hole dimensional accuracy is relatively low, the semi-finished product can be processed by casting instead of being warm forged or hot forged.

In each of the above processing methods, in the case of a material having a high degree of work hardening during processing of a semi-finished product, it is desirable to anneal the semi-finished product by forging or casting before cold forging.

[0007]

According to the processing method of the present invention, the dimensional accuracy of the hole portion of the semi-finished product processed by warm forging, hot forging, or casting is low, but the size of the hole is reduced by cold forging. Precision products will be mass-produced that have holes with precision corrected and very small deviation from design dimensions. Also,
The plastic working during cold forging increases the strength and wear resistance of the hole portion.

[0008]

1 and 2 show examples of a die for forging used in an example of the method of the present invention, and FIG. 4 shows an aluminum product with a hole to be machined in the example of the method of the present invention.
The product 4 of FIGS. 3 and 4 is a ring-shaped receiving member for receiving a piston of a compressor (not shown) in an automobile, and holes 4a for press-fitting pistons of the compressor (not shown) are equiangularly (almost 72 degrees) provided on the outer periphery. To have
It has a hole 4b formed by punching in the center, and the hole 4a
Has a concave spherical inner bottom.

The diameter L of the product 4 in FIG. 4 is 97 mm,
The diameter l of the hole 4b is 35 mm, the diameter of the circle connecting the centers of the holes 4a is 75 mm, the diameter R of the hole 4a is 14.3 mm, and the depth d1 of the vertical wall of the hole 4a is 5.5 mm. The bottom radius d2 is designed to be 7.15 mm.

Molds for forging are SKD-11 and SKH-9.
It is made of a steel material in the middle of the above and is composed of a die 1 and a punch 3 fixed on a machine base 10. A core 11 for forming the hole 4a of the product 4 in the die 1.
And a knockout pin 2 is provided in the central portion thereof, and an escape hole 20 for flushing the material is formed in the upper center of the knockout pin 2.

The first embodiment of the method of the present invention will be described in detail below. First, an aluminum alloy having a composition close to that of an A4032 alloy containing 10% silicon has a diameter of approximately 100 mm.
1 is extruded and sliced to have a wall thickness of about 16 mm to produce the material 41 of FIG.

A lubricant made of sodium metal soap is applied to the surface of the material 41 (coating thickness is about 1 micron), and this is fed into a furnace (not shown) and heated to about 300 ° C. 2 into the die 1 and pressurizing with a punch 3 at about 63 kg / mm ^{2 for} about 0.5 seconds.
The forged semi-finished product 40 is forged. After the forging, the semi-finished product 40 is knocked out from the die 1 and cooled to room temperature. The dimensions of the warm forging die 1 and the punch 3 are set to be slightly larger than the dimensions of the product 4 shown in FIGS. 3 and 4, but the semi-finished product 40 is reduced by cooling and is approximately 85% of the designed size. A semi-finished product 40 having a dimensional accuracy of a degree is manufactured.

Next, the semi-finished product 40 is fed into a furnace (not shown), held at about 320 ° C. for about 2 hours, and then gradually cooled over about 8 hours.

After the cooling, the surface of the semi-finished product 40 is lubricated in the same manner as the above-mentioned lubrication process, and another mold having the same structure as the mold of FIG. By extruding inward at room temperature, the same pressure as in the case of warm forging is applied for the same time to correct the shape and size by about 15%, and plastic working is performed.
The product 4 was manufactured by cutting a portion of the flash 42 of FIG.

When 30 products 4 were manufactured by the above procedure, the vertical wall depth d1 of the hole 4a was ± 0.06 m, which is the design value.
m or less, the radius d2 of the concave spherical bottom of the hole 4a is within +0.025 mm of the design value, and the diameter R of the hole 4a is + of the design value.
Within 0.02 mm, center spacing of holes 4a is ± 1 of design value
It was less than 0 '. In addition, the semi-finished product is machined by warm forging or hot forging, and the productivity of the semi-finished product is much improved as compared with the case where the hole portion of the semi-finished product is cut to ensure the required dimensional accuracy. The portion 4a has improved strength and wear resistance due to plastic working.

Next, a second embodiment of the method of the present invention will be described. A mold (mold) (not shown) having the same size as the design size of the product 4 is prepared in advance, and the casting aluminum alloy AC4A is melted at about 720 ° C. Injecting this molten metal into the mold, supplying cooling water around the mold to cool it for 2 to 3 minutes,
The sprue and puddle of the alloy lump taken out from the mold were cut by a press to manufacture a semi-finished product (not shown) having a dimensional accuracy of about 70% of the design dimension of the product. This semi-finished product is annealed in the same manner as in the first embodiment, and after surface lubrication treatment, it is subjected to cold forging in the same manner as described above to obtain 30%.
The product 4 was manufactured by straightening the shape and dimensions, plastically working the same, and cutting the flash portion formed inside with a press.

When 30 products 4 were manufactured according to the procedure of the second embodiment, the depth d1 of the vertical wall of the hole 4a was ± the design value.
0.09 mm or less, the radius d2 of the concave spherical bottom in the hole 4a
Was within +0.035 mm of the design value, the diameter R of the hole 4a was within +0.04 mm of the design value, and the center interval of the holes 4a was within ± 15 'of the design value. Other effects of the processing method of this embodiment were the same as those of the above-mentioned embodiment.

In each of the above embodiments, the semi-finished product was annealed before cold forging. However, when an alloy having a relatively small work hardening is used, for example, when an A6000 series aluminum alloy is used, the semi-finished product is not annealed. It can be cold forged.

In each of the above-mentioned embodiments, the hole 4a of the product 4 is a round hole and has an inner bottom on a concave spherical surface, but the method of the present invention is not limited to the processing of an aluminum product having such a hole 4a.
It is also effective when processing aluminum products with flat-bottomed holes, conical-shaped holes, polygonal holes, etc. Rather, products with such shaped holes are more resistant to pressure resistance during cold forging. Since the amount of deformation is small, it can be processed more precisely and easily. Further, the method of the present invention is not limited to products made of aluminum or its alloys, but can also be applied to the processing of products with precision holes made of, for example, copper and its alloys, magnesium and other metals.

Generally, forging at 300 ° C. or lower is called warm forging, and forging at 300 ° C. or higher is called hot forging. When hot forging is performed at a temperature higher than 350 ° C., the surface of the material is lubricated. However, there is no effect, and a draft used in the hot forging requires a draft. This draft cannot be corrected during cold forging, and therefore a hole having a portion perpendicular to the inner wall cannot be machined.

[0021]

According to the method of the present invention, a semi-finished product is processed by warm forging or hot forging or casting, which has a poor dimensional accuracy but a large working ratio, and a cold working which has a small working ratio but high dimensional accuracy. Since the hole size is corrected by forging and plastic working is performed, mass productivity is much improved compared to the conventional case where the hole size is corrected by cutting, and aluminum products with holes can be provided at low cost. In addition, the strength and wear resistance of the holes of the product are improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a material is supplied to a forging die used in an embodiment of the method of the present invention.

FIG. 2 is a half sectional view showing a state in which a material is pressed in the mold of FIG.

FIG. 3 is a plan view of a precision aluminum product having holes manufactured by the method of the present invention.

4 is a cross-sectional view taken along the arrow AA of FIG.

[Explanation of symbols]

 1 Die 11 Core 2 Knockout Pin 20 Escape Hole 3 Punch 4 Product 40 Semi-finished Product 41 Material 42 Flash

Claims (3)

[Claims] 1. A step of processing a semi-finished product by warm forging or hot forging at 150 to 350 ° C. with a mold having a size slightly larger than the product size, and the semi-finished product having a size substantially the same as the product size. Cold forging step, and a method for processing a precision aluminum product having a hole. 2. A step of casting a semi-finished product with a mold having substantially the same size as the product size, and a step of cold forging the semi-finished product with a die having substantially the same size as the product size. A method for processing precision aluminum products having holes. 3. The method for processing a precision aluminum product having a hole according to claim 1, wherein the semi-finished product is annealed before cold forging.