Development History and Introduction of Hydraulic Thread Insert Valves
The thread insertion connection form stands out in the long-term application of various connection methods in hydraulic components, and has formed a valve type that was not fully recognized in the past. The use of this common and universal connection method as the installation form of a hydraulic valve is an evolution of thinking. For the long-standing problem of leakage in the hydraulic industry over the past two to three decades, it is a simple and inexpensive solution. This method has also been continuously extended. In the DBD overflow pilot valve of the familiar plate relief valve, the connection between the electromagnet and the valve body of the plate valve has been improved from the original plate connection, screw connection, etc. to this non-standard plug thread connection method, and has achieved good results, basically solving the problem of hydraulic leakage. It was not until 20-30 years later that this type of threaded insert valve became popular among enterprises and professionals, forming a hot spot for major multinational companies to compete for mergers and acquisitions. And it is becoming one of the main types of hydraulic valves.
Throughout the development history of threaded plug-in valves, it can be seen that they have gone through stages of formation, development, and integration.
Formation stage (1970-1980): With the establishment of professional factories such as SUN in the United States in 1970 and Intergraded Hydraulic in the United Kingdom in 1972, it marked its formation. Its application can be traced back to the relief valve and other components previously used by the US Air Force on aircraft fuel pumps. Due to its small size and light weight, it has been extended to related fields. The World Hydraulic Industry Association was established in various countries in the 1950s and 1960s, and we can trace the traces of this type of valve. But it did not form a climate and was only adopted locally.
Development stage (1980-2000): A group of threaded plug valve manufacturers have been established. Based in the United States, there are Hydraforce, Sun, Fluid Power Systems, Delta Power, W aterman Parker Hannifin, Fluid Control (Danfoss), Vickers Modular Controls, etc. In the UK, there are Sterling and Integrated, in Switzerland there are Wandfluh, Bucher. Frutigen, in Italy there are Comatrol and Oil Control, in Germany there are Rexroth, IMAV, Tries, Fluid Team, HYDAC, and so on.
After extensive adoption, threaded plug-in valves have gradually formed a series and have occupied a certain market share. That is to say, during this period, there was a requirement to unify the geometric dimensions of valve holes for insertion in order to improve interchangeability, and international standards began to be formulated. Due to significant differences, it was not until 1998 that ISO7789 was adopted as the international standard for threaded plug valve mounting holes. This has lost its optimal timing for the goal of standardization. China established its first threaded plug-in valve factory, Ningbo Haihong Hydraulic Parts Factory, in 1992, mainly to support the relief valve in the multi way valves produced by its parent company.
Merger stage (2000-2010): This period has sparked a wave of mergers and acquisitions among hydraulic multinational enterprises around the world. Except for MOOG, which mainly produces servo valves, which has not entered the competition, hydraulic multinational companies with sales of $1 billion in the world have acquired their own specialized threaded plug valve factories, such as Parker, Bosch Rexroth, Eaton, Sauer Danfoss, etc. Parker acquired Sterling; Rexroth acquired Oil Control; Eaton acquired Integrated; Sauer Danfoss acquired Comatrol, and Bucher acquired CCC (Command Control Co.). Currently, it is still in the process of integration and integration after the acquisition.
At this stage, Chinese threaded plug-in valve enterprises are also brewing new development opportunities. Ningbo Ketai Hydraulic Co., Ltd. has developed with half of the domestic and foreign markets, with a greater emphasis on electromagnetic valves. Currently, there are also many Taiwanese manufacturers involved in this field, and other small domestic enterprises are also establishing one after another. According to publicly available information, the annual production of Hydraforce in China in recent years has reached 6 million pieces, which is equivalent to the total annual production of all hydraulic components in China in 2005; China's Haihong has also claimed an annual production of 1 million pieces in recent years.
It can be expected that under the guidance and support of the "Equipment Manufacturing Revitalization Plan" and the "Twelfth Five Year Plan" issued by the State Council of China in 2009, the production and research and development of threaded plug-in valves in China will make a leap with the great development opportunities of the entire hydraulic industry in China. The development of the world's threaded valve industry will be based on inheritance and innovation, and the entry of China's threaded valve industry will become more active. They will enter a new period of development together with the world's leading threaded valve industry and a group of strong competitors of threaded valve industry.
Thread insertion valve is a gradually developing new main connection method following the tube, plate, stacked, and two-way insertion types of hydraulic control valves. In the future, hydraulic threaded cartridge valves will be used together with two-way cartridge valves to divide the flow range and occupy a dominant position in hydraulic valves, which is being and will be further confirmed by practice.
Although hydraulic threaded plug-in valves have been formed for a long time, there was little understanding in the industry in China until the end of the last century. The "Newly Compiled Hydraulic Engineering Manual" published in 1999, which represents the level of China's hydraulic academic and industry circles, only has one page to describe this valve, which is a clear proof. It was not until the 1990s that China established a state-owned professional factory for this valve. However, due to the long-term positioning of only supporting multiple way valves, the pace of development in product specifications was not significant; It was not until this century, with the rapid development of China's hydraulic industry, that the localization of threaded plug-in valves entered a period of rapid growth. Although the threaded plug-in type is a change in connection method, it has developed into a major valve type because it has many irreplaceable advantages. One of the advantages of this technology is its zero leakage, light weight, high integration, relatively easy processing and modification, cost reduction, and green manufacturing. Therefore, it has an increasingly obvious advantage in promoting the development of hydraulic components and updating the design concept of hydraulic systems. Although this advantage has not been fully developed by hydraulic users in the early stages of development and even today, there is still room for promotion and development of this technology.
The formation of threaded plug-in valves as valve types is a gradual process. So far, there are few technical books related to this area, and China has not yet published them, and there are also few articles published in magazines. The reason behind this is that it appears to be only a structural change on the surface, without any innovation in principles or breakthroughs in performance. Therefore, it does not belong to the category of high-tech, but is only a practical technology, and its development has not received high attention. However, after an unknown development, it gradually formed its own system and characteristics in the field of engineering machinery, and its influence on the development of hydraulic valves gradually strengthened. Some of its advantages were developed and became a type of valve, and from the moment it became one of the mainstream, it transformed from a quantitative change to a qualitative change. In the early 21st century, major multinational hydraulic companies acquired influential or distinctive threaded plug valve enterprises or companies in the world hydraulic field, and incorporated them into their own business areas, forming a wave of acquisitions, which also illustrates this point. This also proves that this type of valve will have further development vitality.
Although China's hydraulic industry is developing rapidly, it lags behind and is relatively weak in terms of technology, especially in terms of innovative technology, including the technology of threaded plug-in valves. So far, there are only 2-3 well-known domestic threaded plug-in valve enterprises, and their international influence is just beginning. Since the 1990s, professional operators and technicians in our country have only realized strongly that this type of component has become increasingly popular in the market, with a trend of not only occupying a corner but also squeezing out other valve types. They have realized that it is a technology with great development prospects. However, there are not many discussions and application examples in hydraulic books and magazines in this area, which also indicates that technical personnel in China are not yet familiar with this technology, and there is relatively little use of the characteristics of this new valve type to develop products and form more distinctive systems. In recent years, there has been rapid development in this area in China, with an increasing number of hydraulic component companies and host application companies involved.