Patent Application
20220203418
This application claims priority of Taiwanese Invention Patent Application No. 109146653, filed on Dec. 29, 2020.
The disclosure relates to a method for manufacturing a cold-forged extruded aluminum alloy rod by cold forging and cold extrusion.
A conventional connecting structure of a bicycle is generally made by hot forging and hot extrusion in response to the shape and structural strength requirements. Specifically, a material subjected to hot forging and hot extrusion is first heated in a furnace to a temperature above the recrystallization temperature, followed by a processing step for shaping. Hot forging and hot extrusion not only require a furnace that can withstand high temperature and a material-taking equipment, but also incur a high capital expenditure due to quick wearing of the hot forging and hot extrusion dies and large consumption of energy.
Therefore, an object of the present disclosure is to provide a method for manufacturing a cold-forged extruded aluminum alloy rod by cold forging and cold extrusion that can alleviate at least one of the drawbacks of the prior art.
According to this disclosure, a method for manufacturing a cold-forged extruded aluminum alloy rod includes the steps of:
(A) preparing a primary material having a block shape and made of an aluminum alloy material, and at least one cold extrusion apparatus including a cold extrusion die, and a cold extrusion punch corresponding in position to the cold extrusion die;
(B) processing the primary material to form a solid preform that extends along an axis and that has a first end surface intersecting the axis, a second end surface opposite to the first end surface along the axis, and an outer circumferential surface interconnecting outer circumferential edges of the first end surface and the second end surface, the preform having a length extending from the first end surface to the second end surface, and an outer diameter measured across the outer circumferential surface;
(C) subjecting the preform to a homogeneous annealing which involves heating the preform in a furnace to a temperature ranging from about 410° C. to 510° C., and then removing the preform from the furnace after the furnace is cooled to a temperature ranging from about 160° C. to 200° C. at a cooling rate of 10° C. per hour;
(D) testing the hardness of the preform, the hardness being equal to or below 60 degrees measured on Rockwell Hardness F scale;
(E) immersing the preform in a tank containing a lubricant for a predetermined time;
(F) applying talcum powder on the first end surface, the second end surface and the outer circumferential surface of the preform after the preform is immersed in the lubricant; and
(G) subjecting the preform to cold forging which involves positioning the preform in the cold extrusion die, after which the cold extrusion punch is operated to strike against the preform to thereby form the cold-forged extruded aluminum alloy rod, the cold-forged extruded aluminum alloy rod being a solid rod that extends along the axis, and having a first side surface intersecting the axis, a second side surface opposite to the first side surface along the axis, and an outer circumferential surface interconnecting outer circumferential edges of the first side surface and the second side surface, the cold-forged extruded aluminum alloy rod having a length that extends from the first side surface to the second side surface thereof and that is longer than the length of the preform.
Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, of which:
Referring to
In step 1, referring to
The cold extrusion punch 20, 20′, 20″ of each cold extrusion apparatus 2, 2′, 2″ includes a base 21, 21′, 21″, and a ram 22, 22′, 22″ extending downwardly from the base 21, 21′, 21″. The ram 22, 22′, 22″ of each cold extrusion apparatus 2, 2′, 2″ has a rod shape with a bottom edge thereof being chamfered.
The ram 22 has a first outer diameter (D1) corresponding to the first cavity diameter (d1). The ram 22′ has a second outer diameter (D2) corresponding to the second cavity diameter (d2) and smaller than the first outer diameter (D1). The ram 22″ has a third outer diameter (D3) corresponding to the third cavity diameter (d3) and smaller than the second outer diameter (D2).
In step 2, with reference to
In step 3, the preform 1′ is subjected to a homogeneous annealing which involves heating the preform 1′ in a furnace to a temperature ranging from about 410° C. to 510° C., and then removing the preform 1′ from the furnace after the furnace is cooled to a temperature ranging from about 160° C. to 200° C. at a cooling rate of 10° C. per hour.
In step 4, the hardness of the annealed preform 1′ is tested. The hardness of the preform 1′ is equal to or below 60 degrees measured on Rockwell. Hardness F scale (HRF). The testing of the hardness of the preform 1′ is performed at multiple points of the outer circumferential surface 103 of the preform 1′ and at equal intervals along the axis (X).
In step 5, the preform 1′ is immersed in a tank containing a lubricant (not shown) for a predetermined time. In certain embodiments, the lubricant has a free total acidity (TA) concentration ranging from 40% by weight to 50% by weight at a working temperature ranging from 80° C. to 100° C. The lubricant used may be boron nitride. In other embodiments, the lubricant, for instance, a liquid grease, has a viscosity index (VI) of equal to or above 170, a flash point of equal to or above 240° C., a pour point of equal to or above −24° C. and a fire point of equal to or above 255° C.
In step 6, the first end surface 101, the second end surface 102 and the outer circumferential surface 103 of the preform 1′ are applied with talcum powder after the preform 1′ is immersed in the lubricant.
In step 7, with reference to
In this embodiment, a step of subjecting the first cold-forged extruded aluminum alloy rod 100 to undergo steps 3 to 7 may be further conducted. Referring to
In this embodiment, a step of subjecting the second cold-forged extruded aluminum alloy rod 100′ to undergo steps 3 to 7 may be further conducted. Referring to
Thus, by utilizing the above-mentioned consecutive steps 1 to 7 of the present disclosure and by repeating steps 3 to 7 twice, the primary material 1 can be formed into the third cold-forged extruded aluminum alloy rod 100″. The third cold-forged extruded aluminum alloy rod 100″ can avoid the defects caused by metal heating, can obtain high precision and surface quality, can improve the hardness and strength of a workpiece, and has a large deformation resistance during cold forging. By processing the primary material 1 into the preform 1′ in step 2, the third cold-forged extruded aluminum alloy rod 100″ is not required to undergo precision machining, and the cold extrusion apparatuses 2, 2′, 2″ axe not easily worn out. In addition, the homogeneous annealing process in step 3 can improve plasticity of the preform 1′, the first cold-forged extruded aluminum alloy rod 100 and the second cold-forged extruded aluminum alloy rod 100′, so that in the cold forging process in step 7, residual stress of the first cold-forged extruded aluminum alloy rod 100, the second cold-forged extruded aluminum alloy rod 100′ and the third cold-forged extruded aluminum alloy rod 100″ can be reduced, and the homogenization of the composition and structure thereof can be improved. Furthermore, both steps 5 and 6 can provide a lubricating effect to facilitate the subsequent cold forging process.
Therefore, the method for manufacturing the cold-forged extruded aluminum alloy rod 100, 100′, 100″ of the present disclosure does not require high temperature hot forging equipment and material-taring equipment. In addition, the processing of the primary material 1 into the preform 1′ in step 2 not only can improve precision of the cold-forged extruded aluminum alloy rod 100, 100′, 100″, but also can reduce wearing out of the cold extrusion dies 10, 10′, 10″ of the cold extrusion apparatuses 2, 2′, 2″ so as to prolong the service life thereof. Furthermore, an overall power consumption and the manufacturing cost can be reduced.
It is worth mentioning that, in this disclosure, a step 8 may be provided, in which, referring to
In step 8, the cold-forged extruded aluminum alloy rod 100″ is positioned in the molding die cavity 311, after which the forming punch 30 is operated to strike the forming ram 32 against the third cold-forged extruded aluminum alloy rod 100″ to thereby form the patterned cold-forged extruded aluminum alloy rod (100a).
It should be noted herein that in step 5 of this disclosure, the predetermined time for immersion of the preform 1′ into the lubricant depends on the number of the preform 1′. When the number of the preform 1′ is one, the predetermined time is 4 to 5 minutes. When there are a plurality of the preforms 1′, the predetermined time may range from 25 to 35 minutes.
In sum, the method for manufacturing the cold-forged extruded aluminum alloy rod 100, 100′, 100″ by cold forging of the present disclosure has simple processing steps and equipments, is energy-saving, can effectively reduce the capital cost, and can improve the quality of the obtained cold-forged extruded aluminum alloy rod 100, 100′, 100″.
While the disclosure has been described in connection with what is considered the exemplary embodiment, it is understood that this disclosure is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 109146653 | Dec 2020 | TW | national |
