Although there are many types of tapping screws, they all have the following similarities: Round head Tapping screw,hex tapping screw,flat head tapping screw,pan head tapping screw,truss head tapping screw Shenzhen Lanejoy Technology Co.,LTD , http://www.wire-spring.com
Shandong Laizhou Stone Industry and Trade Base
Laizhou City as the center, including Yantai, Pingdu, Weihai, Rongcheng, Qingdao and other regions, has 8 imported sheet production lines, with an annual output of 6 million square meters of sheet metal. The stone export volume of Shandong Laizhou, which is also known as “China's Shiduâ€, also exceeded US$50 million, ranking third.
Guangdong Yunfu Stone Industry and Trade Base
The local only produces cloud gray marble. With the attention and support of the local government, it has developed into the largest stone processing trade base in China, processing domestic famous granite and marble, with an annual output of about 15 million square meters. It is also the second largest stone export base in China with an export value of 120 million US dollars.
Sichuan Ya'an Stone Industry and Trade Base
In the Ya'an-Baoxing area, there are abundant marble and granite resources, and there are many medium and high-grade varieties, with an annual output of about 9 million square meters.
Fujian Xiamen Stone Industry and Trade Base
Including Xiamen, Quanzhou, Fuding and other vast areas. This area is rich in granite resources and has a long history of development. The famous Hui'an stone carvings are well-known at home and abroad. It is the dwellings of ordinary people, and they are often constructed with stone and stone slabs. More than a decade ago, the workshop-style small processing plant has been changed to an imported assembly line. The output has been greatly increased and the quality has been greatly improved. The products are sold well both at home and abroad, and the plate alone exceeds 10 million square meters. In addition, there are stone carving processing, stone machinery manufacturing, and stone abrasives manufacturing. In Huaqiao University in Quanzhou, there is also a stone machinery research institute. Its products are everywhere in the country. Fujian stone exports rank the country, accounting for 65.7% of the total export value of the industry. Fujian is the country's largest stone export province. In 2002, it earned 750 million US dollars of foreign exchange, accounting for 65.7% of the country's total stone exports. Xiamen has contributed 450 million US dollars.
(1) are generally made of carbonized carbon steel (accounting for 99% of total production). It can also be made of stainless steel or non-ferrous metals.
(2) The product must be heat treated. Carbon steel tapping screws must be carbonized and stainless steel tapping screws must be solution hardened. In order to make tapping screws to meet the requirements of the standard of mechanical properties and performance.
(3) The product surface hardness is high, the core toughness is good. That is, "soft inside strong outside". This is a major feature of tapping Screw performance requirements. If the surface hardness is low, it can not be screwed into the matrix; If the core toughness is poor, a twist will break, can not be used. So "inside soft outside steel" is self-tapping screw to meet the use of performance, very important requirements.
(4) The surface of the product needs surface protection treatment, generally electroplating treatment. Some product surface must be treated by phosphate (photostatting), such as wall panel self - tapping screws for photostatting.
(5) Production by cold heading process. It is recommended to use high-speed cold heading machine and high-speed wire rolling machine or high-speed planetary wire rolling machine. High speed is emphasized here to ensure product quality. Only the head of tapping screw produced by high-speed machine is well formed and the thread quality is high.
China's major stone industry and trade and export base
After nearly 20 years of hard work, China has built a preliminary modern stone industry system, formed dozens of stone industry and trade bases, and became the largest stone processing trade center in Asia. At present, there are nearly 30,000 stone industry and trade enterprises in China, mainly distributed in Fujian, Guangdong and Shandong. It has formed four processing bases and one logistics distribution center, namely Laizhou in Shandong, Nanan in Fujian, Yunfu in Guangdong and Yaan in Sichuan, and Xiamen in Fujian. Here are a few typical stone production bases: