SPIN FORMING METHOD FOR RIM OF CAST-SPUN ALUMINUM ALLOY HUB

Abstract

The present disclosure discloses a method for forming a rim of a cast-spun aluminum alloy hub, that is, a special spinning composite machining method for forming a structure that the spokes and the inner wheel flange of the hub are cast and the middle of the rim is spun. The method can prevent the performance, strength and as-cast structure of the inner wheel flange from being destroyed, effectively improve the impact resistance of the cast-spun hub at the inner wheel flange, prevent the inner wheel flange of the cast-spun hub from cracking during radial impact and improve the performance of the spun structure of the rim, is beneficial to thinning the rim and realizes light weight of the rim.

Claims

1. A spin forming method for a rim of a cast-spun aluminum alloy hub, wherein the inner wheel flange C of a new cast rim and the inner wheel flange D of a new spun rim are set to be identical in shape, the new cast rim is spun into the new spun rim by three spinning rollers, at the same time, the inner wheel flange C of the new cast rim is formed to the inner wheel flange D of the new spun rim, that is, C is superposed with D; in consideration with feeding at the inner wheel flange D, a feeding channel of the new cast rim is set at 13.5-15 mm; in order to ensure sequential solidification of the cast rim, the inside inclination angle of the blank of the new cast rim, the outside inclination angle of the blank of the new cast rim and a wheel well have certain structural gradient; a casting mold for the new cast rim is cooled with water; according to the casting process, the preheating temperature of the mold is 320-380, the temperature of molten aluminum is 690-710, the holding pressure is 830-860 mbar, the holding time is 130-150 s, and the cooling time after pressure relief is 25-35 s; strong thermal spinning is performed on the high-temperature new cast rim by adopting three times of vertical spinning, that is, three spinning rollers in different shapes are adopted for spin forming of the cast rim according to different spinning trajectories; the fillet radius of each spinning roller is set at R6.5-R25, and the forming angle is 10-35; during forming, the heating temperature of the blank is controlled at 350-380 C., and the initial temperature of the mold is controlled at 250-300 C.; the total thinning rate of the cast blank is not less than 65%, the thinning rate of each spinning with a spinning roller being 15%-35%, the offset distances of the spinning rollers being 2-5 mm, the feed rates being 500-1200 mm/min, the revolving speed of a spinning machine spindle being 400-600 r/min, the tail cap pressure being set at 3.5-6 Mpa, and the spinning time is 45-60 s.

2. The spin forming method for a rim of a cast-spun aluminum alloy hub according to claim 1, wherein the feeding channel of the new cast rim is set at 13.5 mm; in order to ensure sequential solidification of the cast rim, the inside inclination angle of the blank of the new cast rim is 19, the outside inclination angle of the blank of the new cast rim is 18, and the thickness of the wheel well is 18.6 mm, so that the new cast rim has certain structural gradient; the casting mold for the casting process of the new cast rim is cooled with water, the preheating temperature of the casting mold being 320 C., the temperature of molten aluminum being 690 C., the holding pressure being 830 mbar, the holding time being 130 s, and the cooling time after pressure relief being 25 s; the new cast rim is spun at a temperature of 360 C.; according to the new spinning process, in the case where the structure of the existing spinning mold is unchanged, the fillet radius of a first spinning roller is R25 and the forming angle being 20, the fillet radius of a second spinning roller being R12.5 and the forming angle being 25, and the fillet radius of a third spinning roller being R6.5 and the forming angle being 35; during forming, the initial temperature of the spinning mold is controlled at 250 C.; the total thinning rate of the cast blank is 69.6%, the thinning rates of the three times of spinning with the spinning rollers being 40%, 34.5% and 26.3% respectively, the offset distances of the spinning rollers being 2 mm and 3.5 mm respectively, the feed rates of the spinning rollers being 500 mm/min, 600 mm/min and 900 mm/min respectively, the revolving speed of the spinning machine spindle being 400 r/min, the tail cap pressure is set at 3.5 Mpa, and the spinning time is 60 s.

3. The spin forming method for a rim of a cast-spun aluminum alloy hub according to claim 1, wherein the feeding channel of the new cast rim is set at 15 mm; the inside inclination angle of the blank of the new cast rim is set at 19, the outside inclination angle of the blank of the new cast rim being set at 16, and the thickness of the wheel well being 19.5 mm; the casting mold for the casting process of the new cast rim is cooled with water, the preheating temperature of the casting mold being 380 C., the temperature of molten aluminum being 700 C., the holding pressure being 860 mbar, the holding time being 150 s, and the cooling time after pressure relief being 35 s; the new cast rim is spun at a temperature of 380 C.; according to the new spinning process, in the case where the structure of the existing spinning mold is unchanged, the fillet radius of a first spinning roller is R25 and the forming angle is 20, the fillet radius of a second spinning roller being R11 and the forming angle being 28, and the fillet radius of a third spinning roller being R7 and the forming angle being 35; during forming, the initial temperature of the spinning mold is controlled at 300 C.; the total thinning rate of the cast blank is 69.6%, the thinning rates of the three times of spinning with the spinning rollers being 47.8%, 29.2% and 17.63% respectively, the offset distances of the spinning rollers being 3 mm and 2.5 mm respectively, the feed rates of the spinning rollers being 600 mm/min, 750 mm/min and 1100 mm/min respectively, the revolving speed of the spinning machine spindle being 550 r/min, the tail cap pressure being set at 4.5 Mpa, and the spinning time being 45 s.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0013] FIG. 1 is a schematic diagram of forming of an original cast structured rim.

[0014] FIG. 2 is a schematic diagram of forming of a new cast structured rim according to the present disclosure.

[0015] FIG. 3 is a schematic diagram of spin forming according to the present disclosure.

LIST OF REFERENCE SYMBOLS

[0016] 1original cast rim, 2original spun rim, 3spoke, 4new cast rim, 5new spun rim, 6feeding channel, 7inside inclination angle of new cast rim blank, 8outside inclination angle of new cast rim blank, 9wheel well, 10spinning roller trajectory for the first spinning, 11spinning roller trajectory for the second spinning, 12spinning roller trajectory for the third spinning, Aoriginal cast rim inner wheel flange, Boriginal spun inner wheel flange, Cnew cast rim inner wheel flange, Dnew spun inner wheel flange.

DETAILED DESCRIPTION

[0017] The technical solution of the present disclosure will be further specifically described below through embodiments and in combination with the accompanying drawings.

[0018] In an embodiment, a feeding channel 6 of a new cast rim 4 is set at 13.5 mm; in order to ensure sequential solidification of the cast rim, the inside inclination angle 7 of the blank of the new cast rim 4 is 19, the outside inclination angle 8 of the blank of the new cast rim 4 is 18, and the thickness of a wheel well 9 is 18.6 mm, so that the new cast rim 4 has certain structural gradient.

[0019] A casting mold for the casting process of the new cast rim 4, especially the inner wheel flange, is cooled with water. The preheating temperature of the casting mold is 320 C., the temperature of molten aluminum is 690 C., the holding pressure is 830 mbar, the holding time is 130 s, the cooling time after pressure relief is 25 s, the production cycle is improved from original 5.5 min/piece to 3.8 min/piece, and the casting production efficiency is improved by 30.9%. The elongation of the rim is improved to not less than 10%, and the elongation of the inner wheel flange can be improved to not less than 12%. The strength of the spun rim can be further improved by improving the strength of the cast rim, that is, the wall thickness of the rim can be reduced to 2.5 mm. At the same time, the water-cooled mold dispenses with air cooling, saves the cost of compressed air and reduces the manufacturing cost by 1.2 yuan.

[0020] The new cast rim 4 is spun at a temperature of 360 C., and three times of vertical spinning are adopted, with the spinning roller trajectory for the first spinning being 10, the spinning roller trajectory for the second spinning being 11 and the spinning roller trajectory for the third spinning being 12.

[0021] According to the new spinning process, in the case where the structure of the existing spinning mold is unchanged, the fillet radius of a first spinning roller is R25 and the forming angle is 20, the fillet radius of a second spinning roller is R12.5 and the forming angle is 25, and the fillet radius of a third spinning roller is R6.5 and the forming angle is 35. During forming, the initial temperature of a spinning mold is controlled at 250 C. The total thinning rate of the cast blank is 69.6%, the thinning rates of the three times of spinning with the spinning rollers are respectively 40%, 34.5% and 26.3%, the offset distances of the spinning rollers are respectively 2 mm and 3.5 mm, the feed rates of the spinning rollers are respectively 500 mm/min, 600 mm/min and 900 mm/min, the revolving speed of a spinning machine spindle is 400 r/min, the tail cap pressure is set at 3.5 Mpa, and the spinning time is 60 s.

[0022] The performance parameters of the aluminum alloy cast-spun hub formed by the above steps are shown in the table:

TABLE-US-00001 TABLE 1 Tensile Cast-spun hub Yield strength MPa strength MPa Elongation % Inner wheel flange 220 292 12 Rim 222 295 13.5 Spokes 194 265 7.2

[0023] It can be seen from table 1 that the cast-spun hub manufactured in embodiment 1 has the advantages that the performance of the rim is good, thinning of the rim is facilitated, the strength of the inner wheel flange is high, the structure is uniform and the radial impact resistance is improved.

[0024] In another email, a feeding channel 6 of a new cast rim 4 is set at 15 mm; in order to ensure sequential solidification of the cast rim, the inside inclination angle 7 of the blank of the new cast rim 4 is set at 19, the outside inclination angle 8 of the blank of the new cast rim 4 is set at 16, and the thickness of a wheel well 9 is set at 19.5 mm, so that the new cast rim 4 has certain structural gradient.

[0025] A casting mold for the casting process of the new cast rim 4, especially the inner wheel flange, is cooled with water. The preheating temperature of the casting mold is 380 C., the temperature of molten aluminum is 700 C., the holding pressure is 860 mbar, the holding time is 150 s, the cooling time after pressure relief is 35 s, the production cycle is improved from original 6.5 min/piece to 4.5 min/piece, the casting production efficiency is improved by 30.7%, the elongation of the rim is improved to not less than 11%, and the elongation of the inner wheel flange can be improved to not less than 13%. The strength of the spun rim can be further improved by improving the strength of the original cast rim, that is, the wall thickness of the rim can be further reduced to 2.2 mm, which is beneficial to the weight reduction of a wheel product of the cast-spun hub. At the same time, the water-cooled mold dispenses with air cooling, saves the cost of compressed air and reduces the manufacturing cost by 1.35 yuan.

[0026] The new cast rim 4 is spun at a temperature of 380, and three times of vertical spinning are adopted, with the spinning roller trajectory for the first spinning being 10, the spinning roller trajectory for the second spinning being 11 and the spinning roller trajectory for the third spinning being 12.

[0027] According to the spinning process, in the case where the structure of the existing spinning mold is unchanged, the fillet radius of a first spinning roller is R25 and the forming angle is 20, the fillet radius of a second spinning roller is R11 and the forming angle is 28, and the fillet radius of a third spinning roller is R7 and the forming angle is 35. During forming, the initial temperature of a spinning mold is controlled at 300. The total thinning rate of the cast blank is 69.6%, the thinning rates of the three times of spinning with the spinning rollers are respectively 47.8%, 29.2% and 17.63%, the offset distances of the spinning rollers are respectively 3 mm and 2.5 mm, the feed rates of the spinning rollers are respectively 600 mm/min, 750 mm/min and 1100 mm/min, the revolving speed of a spinning machine spindle is 550 r/min, the tail cap pressure is set at 4.5 Mpa, and the spinning time is 45 s.

[0028] The performance parameters of the aluminum alloy cast-spun hub formed by the above steps are shown in table 2:

TABLE-US-00002 TABLE 2 Tensile strength Cast-spun hub Yield strength MPa MPa Elongation % Inner wheel 226 298 12.6 flange Rim 232 302 14.2 Spokes 196 270 8.3

[0029] It can be seen from table 2 that the cast-spun hub manufactured in embodiment 2 has the advantages that the performance of the rim is good, thinning of the rim is facilitated, the strength of the inner wheel flange is high, the structure is uniform and the radial impact resistance is improved.

[0030] The foregoing descriptions are merely preferred embodiments of the present disclosure but are not intended to limit the patent scope of the present disclosure. Any equivalent modifications made to the structures or processes based on the specification of the present disclosure, or direct or indirect use in other relevant technical fields, shall also be encompassed in the patent protection scope of the present disclosure.