Patent Application
20100019418
1. Field of the Invention
The present invention relates to a method for manufacturing a revolving shaft assembly, and more particularly to a method for manufacturing a nonmetallic revolving shaft assembly with high hardness and abrasion resistance.
2. Description of Related Art
Generally, a revolving shaft assembly is used as a hinge in electronic devices, such as notebook, mobile phone, media player and so on. The revolving shaft assembly includes a driving member and a driven member interfereferingly and pivotally engaging with the driving member. The driving member and the driven member are made of metallic material such as steel or alloyed steel. The driving member and the driven member have lower hardness, so a serious abrasion occurs between the driving member and the driven member after a period of use of the shaft assembly. The function and the lifespan of the revolving shaft assembly are accordingly affected and shortened.
It is therefore desirable to provide a method for manufacturing an improved revolving shaft assembly with a driving member and a driven member which have high hardness and abrasion resistance to avoid being unduly worn.
A method for manufacturing a revolving shaft assembly includes the steps of: 1) offering a plurality of first nonmetallic powder; 2) offering a plurality of second nonmetallic powder; 3) offering a mold cavity and filling the first and second nonmetallic powder in the mold cavity to form a green piece, wherein a plurality of pores is defined between the nonmetallic powder of the green piece; 4) heating the green piece at a temperature between 1100° C. and 1500° C. to sinter the nonmetallic powder to obtain a sintered product; 5) dipping the sintered product in lubricant oil to make the lubricant oil enter the pores of the sintered product to thereby obtain a final desired product.
Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings.
Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Referring to
A method for manufacturing the revolving shaft assembly in accordance with a first embodiment of the present invention comprises the steps of: 1) offering a quantity of ZrO2 powder as a first nonmetallic powder; 2) offering a quantity of Y2O3 powder as a second nonmetallic powder; 3) mixing the ZrO2 powder and the Y2O3 powder to have mixed powder; 4) offering a mold (not shown) having a cavity and filling the mixed powder into the cavity of the mold and pressing the mixed powder to make a green piece, wherein pores (not shown) are defined between the pressed mixed powder and a volume ratio of the pores of the green piece is situated between 30% and 50%, and a volume ratio between 35% and 40% of the pores in the green piece is preferable; 5) heating the green piece at a temperature between 1100° C. and 1500° C., whereby the mixed powder of the green piece is sintered and diffusion bonded together to obtained a sintered product, wherein a volume ratio of pores of the sintered product is situated between 1.5% and 6%, and a hardness value of the sintered product is situated between 900 HV and 1300 HV, and a toughness value of the sintered product is situated between 6K1c and 12K1c; 6) post-treating the inner surfaces of the driving member 10 and the driven member 20 to obtain surface roughness value less than Ra0.1 μm for the driving member 10 and the driven member 20; 7) dipping the sintered product into lubricant oil to fill the lubricant oil in the pores of the sintered product thereby to obtain a final desired product for forming the revolving shaft assembly.
In this embodiment, the Y2O3 powder acting as an additive is added to the ZrO2 powder to improve the hardness and toughness of the ZrO2 powder. The Y2O3 powder accounts for 3%-15% of the revolving shaft assembly by weight. The driving member 10 and the driven member 20 have high hardness and abrasion resistance. When the driving member 10 and the driven member 20 are assembled together, inner surfaces of the driving member 10 and the driven member 20 are intimately engaged with each other. An lubricant oil film is formed between the inner surfaces of the driving member 10 and the driven member 20 to lubricate the revolving shaft assembly. Thus, the driving member 10 and the driven member 20 can rotate smoothly relative to each other and avoid being unduly worn after a period of use thereof.
A method for manufacturing the revolving shaft assembly in accordance with a second embodiment is similar to the first embodiment. A difference between the first and second embodiments is that the second embodiment offers a quantity of Al2O3 powder and Y2O3 powder as a second powder. The Y2O3 powder accounts for 3%-15% of the revolving shaft assembly by weight. The Al2O3 powder accounts for 0.1%-0.3% of the revolving shaft assembly by weight. A hardness value of the sintered production in this embodiment is situated between 1100 HV and 1450 HV, and a toughness value of the sintered product is situated between 7K1c and 14K1c.
A method for manufacturing the revolving shaft assembly in accordance with a third embodiment is similar to the first embodiment. A difference between the first and third embodiments is that the third embodiment offers a quantity of carbide powder as the first powder, and a quantity of Si powder and Y2O3 powder as a second powder. A quantity of SiC powder or WC powder or Tic powder acts as the first powder. The Y2O3 powder accounts for 3%-15% of the revolving shaft assembly by weight. The Si powder accounts for 0.1%-0.3% of the revolving shaft assembly by weight. A hardness value of the sintered production in this embodiment is situated between 2000 HV and 2500 HV. A volume ratio of pores of the sintered product is situated between 0.8% and 5%.
A method for manufacturing the revolving shaft assembly in accordance with a fourth embodiment is similar to the first embodiment. A difference between the first and fourth embodiments is that the fourth embodiment offers a quantity of BN powder and Y2O3 powder as a second powder. The Y2O3 powder accounts for 3%-15% of the revolving shaft assembly by weight. The BN powder accounts for 0.1%-0.3% of the revolving shaft assembly by weight. The friction coefficient of the revolving shaft assembly is small because of the BN powder; thus, the abrasion between the driving member 10 and the driven member 20 is reduced.
The oxide additive, which accounts for 3%-15% of the revolving shaft assembly by weight, of the above-mentioned four embodiments may be CeO2 powder or MgO powder or CaO powder.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
