Research and application of analytical super-tight bolts

For high-torque applications such as ship propeller shafts, rudder systems, gas turbine generators, and rollers, super-tight bolts offer significant advantages. These bolts simplify the machining process by eliminating the need for regrinding or additional finishing of the screw holes. The gap between the bolt and the hole remains free and safe, reducing the risk of damage or failure. Assembly and disassembly are faster and more efficient compared to traditional bolts, saving time and effort. The tight fit created by these bolts helps eliminate flange slippage, ensuring better alignment and stability. Their expandable design allows for quick centering of flanges, making it easier to align shafts accurately. Additionally, super-tight bolts are interchangeable and reusable, which means no spare parts are needed. This makes them cost-effective and practical for repeated use. Installation requires only a simple set of tools: a tensioner with attachments, a hand pump, and a hose with a quick coupling. The working principle involves a tapered bolt body, an expansion sleeve, and two nuts. When pulled using a tensioner, the expansion sleeve expands to create a secure fit within the screw hole. One nut is tightened manually, while the other provides resistance, allowing the pre-tightening force to be applied effectively. When removing the bolt, oil is injected into the central hole, causing the cone to contract and release the bolt. A pressure gauge on the hand pump ensures precise control over the expansion and tension forces. During assembly, the bolts are inserted into the coupling holes, and due to the proper clearance, they can be easily pushed in by hand. Typically, at least six bolts are used to ensure structural integrity. The design torque is calculated using the formula TD = TN × S, where TN is the normal torque and S is the alternating coefficient. Bolt size selection follows a specific calculation involving the shaft diameter, hydraulic tensioner outer diameter, and bolt hole center distance. The maximum shear stress is designed to be 280 N/mm², while the inter-axial stress is limited to 350 N/mm². When combining super-tight bolts with regular bolts, the number of each type must be carefully determined. The total number of bolts should be a multiple of the super-tight ones. Torque calculations help determine how much load each bolt can handle, ensuring even distribution and safety. This method guarantees reliable performance in demanding mechanical environments.

OTIS LG Sigma Elevator Spare Parts

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Sigma Elevator Company is a subsidiary of Otis Elevator Korea (OEK) in South Korea for all overseas/export markets. It was founded in 2000.

Starting in 1968, "Goldstar" elevators, and later on, "LG" elevators, were counted among the world's top elevator brands. With the beginning of this new millennium, that legacy lives on through the birth of "SIGMA" elevators.

SIGMA Elevator Company will continue on with its mission of supplying elevators and escalators to more than 50 nations worldwide through its global network of 11 sales companies, 2 offices, and 52 agents or distributors.

SIGMA Elevator Company is dedicated to providing its customers with the best quality products and services. SIGMA elevators feature unmatched safety, ride comfort, and modern design. SIGMA escalators and moving walkways are held to similar safety and comfort standards and are integral parts of our modern urban aesthetics.

Changwon factory, Korea, the main factory of SIGMA Elevator, has long been a well-established name in the global elevator industry. SIGMA`s Dalian factory in China produces elevators & escalators to meet the demands of the local and worldwide markets as well.

SIGMA Elevator Company is committed to increasing customer value through a sharp focus on product innovation and customer satisfaction. With technology developed over the past 30 years, an enduring innovative spirit, and enthusiastic attitude towards providing customer value, Sigma Elevator Company stands by its product and service lines with confidence.

 

Sigma currently has businesses in more than 75 countries worldwide, and subsidiaries in five countries; Hong Kong (China), Vietnam, Thailand, Malaysia and Singapore.

In the United States, Sigma elevators were distributed by CemcoLift, which was a historic elevator company bought by Otis and based in Hatfield, PA. However, in 2012 CemcoLift has gone bankrupt and replaced by a new company called Minnesota Elevator Solutions.

It's headquarter, factory and testing tower are located in Changwon, South Korea, which are also operated by Otis Elevator Korea. It also has a secondary factory in Dalian, China, opened in 1998 to meet demands on Chinese elevator market.

In 2014, Sigma had a partnership with EXPRESS Elevator Co., Ltd., an elevator company based in Suzhou, China as well as a subsidiary of Otis. In 2016, Express/Sigma opened their headquarters in Suzhou, China

 

 

LG Elevators was the elevator and escalator division of LG Electronics. It was acquired by Otis in 1999 and was later known as LG-OTIS Elevator Company.

 

LG changed its name from GoldStar in 1994 after GoldStar merged with Lucky Chemical. In 1999, it was acquired by Otis Elevator Company, later known as LG-OTIS Elevator Company from 2000 until 2003, when it was renamed to OTIS-LG Elevator Company.  Later in 2006, OTIS-LG was again renamed to Otis Elevator Korea.

LG-OTIS Elevator Company (later OTIS-LG Elevator Company then Otis Elevator Korea) was a joint venture company between Otis and LG Electronics` elevator and escalator division, LG Elevators in South Korea. It was formed in 2000. The brand was renamed to OTIS-LG Elevator Company in 2003 and later Otis Elevator Korea in 2006, where it is currently known as that in South Korea

 

 

 

 

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CEP Elevator Products ( China ) Co., Ltd. , https://www.china-elevators.com