Magnesium alloys, bicycle rims, and preparation methods

Abstract

The present invention discloses magnesium alloys, bicycle rims made of magnesium alloys, and methods of preparing the alloys and bicycle components made of the alloys. The alloys may include the following components in percentage by weight: 5.5-6.0% of Zn, 0.3-0.6% of Zr, 0.5-2.0% of lanthanum-rich mixed rare earth and the balance of Mg.

Claims

1. A magnesium alloy, comprising the following components in percentage by weight of the magnesium alloy: 5.5-6.0% of Zn, 0.3-0.6% of Zr, 0.5-2.0% of a yttrium-rich mixture of rare earth metals, and the balance of Mg, and wherein the yttrium-rich mixture includes the following components in percentage by weight of the yttrium-rich mixture: 25-30% of Y, 15-20% of Nd, 12-16% of Gd, 10-15% of Dy, 8-12% of La, 6-10% of Ce, 3-6% of Pr, 2-5% of Ho, 1-3% of Er, and and the balance of other rare earth metals.

2. The magnesium alloy of claim 1, wherein the yttrium-rich mixture consists of the following components in percentage by weight of the yttrium-rich mixture: 25-30% of Y, 15-20% of Nd, 12-16% of Gd, 10-15% of Dy, 8-12% of La, 6-10% of Ce, 3-6% of Pr, 2-5% of Ho, and 1-3% of Er.

3. The magnesium alloy of claim 2, wherein the magnesium alloy consists of the following components in percentages by weight of the magnesium alloy: 5.5-6.0% of Zn, 0.3-0.6% of Zr, 0.5-2.0% of the yttrium-rich mixture of rare earth metals, and the balance of Mg, and wherein the yttrium-rich mixture consists of the following components in percentage by weight of the yttrium-rich mixture: 25-30% of Y, 15-20% of Nd, 12-16% of Gd, 10-15% of Dy, 8-12% of La, 6-10% of Ce, 3-6% of Pr, 2-5% of Ho, and 1-3% of Er.

4. A method of preparing a magnesium alloy section bar used as a bicycle rim, the method comprising: preparing a magnesium alloy bar stock, wherein the magnesium alloy bar stock includes a magnesium alloy according to claim 1; heating the magnesium alloy bar stock to a temperature between 300° C. and 400° C.; extruding the magnesium alloy bar stock from an extruder to produce a magnesium alloy section bar.

5. The method of claim 4, further including heating a bicycle rim section bar mold to a temperature between 300° C. and 400° C.

6. The method of claim 5, further including heating the extruder to a temperature of between 300° C. and 380° C. before extruding the magnesium alloy bar stock from the extruder.

7. The method of claim 4, wherein the magnesium alloy is prepared using Mg-5Zr master alloy and Mg-10Re rare earth master alloy.

8. The method of claim 4, wherein the magnesium alloy is prepared by directing a magnesium ingot into a furnace; covering a surface of the magnesium ingot with a covering agent; heating the magnesium ingot to a temperature of between 700° C. and 730° C. to produce melted magnesium; adding zinc, Mg-5Zr master alloy, and Mg-10Re rare earth master alloy to the melted magnesium and stirring to obtain a magnesium alloy melt; allowing the magnesium alloy melt to stand still; removing the covering agent from the magnesium alloy melt; heating the magnesium alloy melt to a temperature of between 730° C. and 750° C.; adding a magnesium alloy refining agent to the magnesium alloy melt and stirring to produce a refined magnesium alloy melt; allowing the refined magnesium alloy melt to stand still; cooling the refined magnesium alloy melt to a temperature of between 680° C. and 700° C. to produce a cooled refined magnesium alloy melt.

9. The method of claim 8, further including: casting the cooled refined magnesium alloy melt in a cast rod crystallizer to form the magnesium alloy bar stock.

10. A method of preparing a magnesium alloy bicycle rim, the method comprising: providing a magnesium alloy section bar prepared according to claim 4; cutting and coiling the magnesium alloy section bar to form a coiled magnesium alloy section bar, wherein the coiled magnesium alloy section bar includes two ends forming a joint; securing a connecting piece to the two ends of the joint of the coiled magnesium alloy section bar to form a connected alloy rim; heat treating the connected alloy rim to form the magnesium alloy bicycle rim.

11. The method of claim 10, further including removing excess material from the two ends of the joint prior to securing the connecting piece to the two ends of the joint.

12. The method of claim 10, wherein securing the connecting piece to the two ends of the joint includes forming holes in both ends of the joint and the connecting piece and welding the connecting piece to the two ends of the joint.

13. The method of claim 12, wherein an argon arc wire welder is used to weld the connecting piece to the two ends of the joint.

14. The method of claim 10, further including deburring the connected alloy rim before it is heat treated.

15. The method of claim 10, wherein heat treating the connected alloy rim includes heating the connected alloy rim to a temperature of 200° C. for a period of between 1 and 2 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a cross-sectional view of a magnesium alloy section bar used as a bicycle rim prepared by the present invention;

(2) FIG. 2 is a schematic diagram of a coiling process in a preparation method of a magnesium alloy rim of the present invention;

(3) FIG. 3 is a schematic diagram of a cutting process in the preparation method of the magnesium alloy rim of the present invention;

(4) FIG. 4 is a schematic diagram of an inserting process in the preparation method of the magnesium alloy rim of the present invention; and

(5) FIG. 5 is a schematic structural diagram of a joint of a prepared magnesium alloy rim.

DETAILED DESCRIPTION

(6) The technical scheme of the present invention will be further described below in conjunction with the drawings.

Example 1 Preparation of a Magnesium Alloy Section Bar

(7) (1) Material Preparation

(8) Magnesium alloy components include 5.5% of Zn, 0.3% of Zr, 0.5% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 27.2% of Y, 18.1% of Nd, 14.6% of Gd, 13.4% of Dy, 11.8% of La, 7.1% of Ce, 4.5% of Pr, 2.3% of Ho and 1.1% of Er.

(9) Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

(10) (2) Smelting

(11) The prepared magnesium ingot charged into a crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 720° C.; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy block are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, after the melt is heated to 740° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 700° C. to prepare for casting.

(12) (3) Casting: the magnesium alloy melt cooled to 700° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling water flow rate to finally form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters.

(13) (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 300° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 320° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar 1 with the cross section shown as FIG. 1.

Example 2 Preparation of a Magnesium Alloy Section Bar

(14) (1) Material Preparation

(15) Magnesium alloy components include 6.0% of Zn, 0.6% of Zr, 2.0% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 26.1% of Y, 16.2% of Nd, 15.8% of Gd, 14.7% of Dy, 11.5% of La, 6.6% of Ce, 4.3% of Pr, 3.2% of Ho and 1.6% of Er.

(16) Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

(17) (2) Smelting

(18) The prepared magnesium ingot is charged into a crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 730° C.; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy blocks are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, after the melt is heated to 750° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 680° C. to prepare for casting.

(19) (3) Casting: the magnesium alloy melt cooled to 680° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling speed to finally form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters.

(20) (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 400° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 380° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar which meets the requirements for rim mechanical properties.

Example 3 Preparation of a Magnesium Alloy Section Bar

(21) (1) Material Preparation

(22) Magnesium alloy components include 5.8% of Zn, 0.5% of Zr, 1.2% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 27.9% of Y, 17.8% of Nd, 14.7% of Gd, 13.3% of Dy, 10.6% of La, 6.1% of Ce, 4.2% of Pr, 3.1% of Ho and 2.3% of Er.

(23) Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

(24) (2) Smelting

(25) The prepared magnesium ingot is charged into a resistance crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 730° C. by energizing; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy blocks are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, the melt is heated to 730° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 690° C. to prepare for casting.

(26) (3) Casting: the magnesium alloy melt cooled to 690° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling speed to form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters at last.

(27) (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 350° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 360° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar which meets the requirements for rim mechanical properties.

Example 4 Preparation of a Magnesium Alloy Section Bar

(28) (1) Material Preparation

(29) Magnesium alloy components include 5.8% of Zn, 0.5% of Zr, 1.5% of yttrium-rich mixed rare earth and the balance of Mg, wherein the yttrium-rich mixed rare earth includes 29.8% of Y, 19.7% of Nd, 12.1% of Gd, 10.1% of Dy, 8.0% of La, 9.8% of Ce, 3.1% of Pr, 4.6% of Ho and 2.8% of Er.

(30) Mg and Zn are added in the form of a magnesium ingot and a zinc ingot, the magnesium ingot and the zinc ingot are pressed into small pieces, Zr is added in the form of Mg-5Zr master alloy, and the yttrium-rich mixed rare earth is added in the form of Mg-10Re rare earth master alloy.

(31) (2) Smelting

(32) The prepared magnesium ingot is charged into a resistance crucible furnace, the upper surface of the magnesium ingot is covered with a layer of a magnesium alloy smelting covering agent, and the furnace charge is heated to 700° C. by energizing; after the magnesium ingot is completely melted, the zinc ingot, and Mg-5Zr master alloy and Mg-10Re rare earth master alloy blocks are added, and after the components are melt, a magnesium alloy melt is fully stirred with a stirrer to make components of the magnesium alloy melt uniform; the melt is subjected to standing still for 15 minutes, the covering agent on the surface of a molten pool is removed by a slag spoon, the melt is heated to 740° C., a magnesium alloy refining agent is added, the magnesium alloy melt is fully stirred with a stirrer, the magnesium alloy is refined to remove gas and debris in the magnesium alloy melt, and then the magnesium alloy melt is subjected to standing still and cooled to 690° C. to prepare for casting.

(33) (3) Casting: the magnesium alloy melt cooled to 690° C. is cast into a magnesium alloy semi-continuous cast rod crystallizer of a specific specification, and the magnesium alloy can be solidified sequentially by controlling the casting speed, the crystallizer withdrawal speed and the cooling speed to form a magnesium alloy semi-continuous cast rod with the length of 10-12 meters at last.

(34) (4) The magnesium alloy cast rod and a bicycle rim section bar mold are put into a resistance heating furnace for heating to 300° C., and then the magnesium alloy bar stock is taken out from the heating furnace and put into an extruder preheated to 300° C. in advance for rim section bar extrusion production to obtain a magnesium alloy section bar which meets the requirements for rim mechanical properties.

(35) The mechanical properties of the magnesium alloy section bars prepared in Examples 1 to 4 are tested, and the results obtained are shown as Table 1:

(36) TABLE-US-00001 TABLE 1 Mechanical properties of the magnesium alloy section bars prepared in Examples 1 to 3 Example 1 Example 2 Example 3 Example 4 Tensile strength 405 MPa 397 MPa 393 MPa 409 MPa Yield strength 296 MPa 287 MPa 295 MPa 302 MPa Elongation 12.9% 18.7% 16.8% 15.2%

Example 5 Preparation of a Magnesium Alloy Rim

(37) With the magnesium alloy section bar prepared in Example 3 as a raw material, a magnesium alloy rim is prepared, and the steps are as follows:

(38) {circle around (1)} Blanking: the required length of the magnesium alloy section bar is determined according to the diameter of a rim, and sawing is carried out;

(39) {circle around (2)} Coiling: as shown in FIG. 2, the magnesium alloy section bar 1 is put on a track of a coiling device, and device parameters are adjusted for coiling according to the diameter of the rim;

(40) {circle around (3)} Cutting: the coiled rim 2 is put on a special cutting device 4, and the excess material near a rim joint 3 is cut, as shown in FIG. 3;

(41) {circle around (4)} Inserting: as shown in FIG. 4, a rim lining connecting piece 5 is inserted into the magnesium alloy section bar at the rim joint 3, then the rim is put on a special inserting machine, and the rim lining connecting piece 5 is fully pressed into the rim joint 3 by using the inserting machine to make the inside of a connector pressed and connected;

(42) {circle around (5)} Drilling: the connected rim is put on a rim drilling platform and fixed, and spoke holes are automatically drilled;

(43) {circle around (6)} Welding: circular holes 6 with the diameter of 5 mm are drilled respectively in the parts 15 mm away from the both sides of the joint at the inner side of a rim on which a tire is mounted, then the rim lining connecting piece 5 and the rim 2 are fixed by argon arc welding with a welding wire, and the structure of the rim joint is shown as FIG. 5;

(44) {circle around (7)} Deburring: after rim welding is completed, burrs and chamfers at the drilling parts and other parts are removed to complete rim processing; and

(45) {circle around (8)} Heat treatment: the processed rim is put into a heat treatment furnace, heated to 200° C. and then taken out from the furnace after temperature keeping for 2 hours.

Comparative Example

(46) With the magnesium alloy section bar prepared in Example 3 as a raw material, a magnesium alloy rim is prepared by using a conventional method in the prior art, and the steps are as follows:

(47) {circle around (1)} Blanking: the required length of the magnesium alloy section bar is determined according to the diameter of a rim, and sawing is carried out;

(48) {circle around (2)} Coiling: as shown in FIG. 2, the magnesium alloy section bar is put on a track of a coiling device, and device parameters are adjusted for coiling according to the diameter of the rim;

(49) {circle around (3)} Cutting: the coiled rim is put on a special cutting device, and the excess material near a rim joint is cut, as shown in FIG. 3;

(50) {circle around (4)} Inserting: as shown in FIG. 4, a rim lining connecting piece after gluing is inserted into the magnesium alloy section bar at the rim joint, then the rim is put on a special inserting machine, and the rim lining connecting piece is fully pressed into the rim joint by using the inserting machine to make the inside of a connector pressed and connected;

(51) {circle around (5)} Deburring: after rim welding is completed, burrs and chamfers at the drilling parts and other parts are removed to complete rim processing; and

(52) {circle around (6)} Heat treatment: the processed rim is put into a heat treatment furnace, heated to 200° C. and then taken out from the furnace after temperature keeping for 1-2 hours.

(53) The bicycle rims prepared in Example 5 and Comparative Example are tested for rim compressive deformation, and the detection standard is that the compressive deformation of a rim under a load of 500 N for 2 minutes is lower than 1 mm; the test results are shown as Table 2, and it can be seen that the deformation of the bicycle rim prepared in Example 5 is lower than 1 mm, indicating that it meets the use requirements of bicycle rims; and the deformation of the bicycle rim prepared in Comparative Example is higher than 1 mm, and obviously, the compressive deformation of the rim exceeds the standard.

(54) TABLE-US-00002 TABLE 2 Test results of compressive deformation of rims Example 5 Comparative Example Compressive deformation of rims 0.425 mm 2.351 mm Result judgment Qualified Unqualified