As we all know, in the general concept of weighing instruments, any weighing instrument with electronic devices can be called an electronic weighing instrument. From the understanding of the concept of automatic weighing instruments, we can think that any weighing instrument that does not require operator intervention during the weighing process and works automatically according to a predetermined processing procedure can be considered an automatic weighing instrument. From the perspective of the development of weighing instrument technology, automatic weighing instruments should be the most important member of electronic weighing instruments.
As for automatic weighing instruments, they include both dynamic automatic weighing instruments that we usually call "during the weighing process, the weighed object and the weighing carrier have relative motion", and non-dynamic automatic weighing instruments that "during the weighing process, although the weighed object and the weighing carrier do not have relative motion, the weighing works automatically and continuously according to a predetermined processing procedure". Automatic weighing instrument products mainly include the following categories:
(1) Continuous cumulative automatic weighing instruments: The main products include non-quantitative belt scales, quantitative belt scales (including quantitative feeders, pressure-resistant metering coal feeders, belt-type batching scales, etc.), nuclear belt scales, impulse flow meters, spiral feeder scales, rotor feeders, continuous loss-in-weight scales, etc.
(2) Automatic sorting scales: The main products include weight sorting scales, price tag scales, vehicle weighing instruments, etc.
(3) Gravity type automatic loading scales (hopper type): The main products include quantitative packaging scales, intelligent combination scales, quantitative cumulative scales, reduction scales, quantitative batching hopper scales, quantitative liquid filling scales, etc.
(4) Non-continuous cumulative automatic scales: The main products include cumulative hopper scales, bulk grain hopper scales, etc.
(5) Dynamic vehicle scales: The main products include dynamic track scales (different track gauges), continuous track scales, single vehicle track scales, combined track scales, dynamic vehicle scales, dynamic axle weight scales, etc.
Looking back at the development history of automatic scales in my country, it can be traced back to the 1970s and 1980s, when it was a great time for reform and opening up. The China Weighing Instrument Association proposed the industry development policy of "changing mechanical to electronic, manual to automatic", which opened a new chapter in the development of my country's weighing industry. The development of automatic weighing instrument technology in my country is accompanied by: ① Equipment import + ② Technology introduction + ③ Technology imitation + ④ Independent research and development + ⑤ Technology innovation, and gradually developed. The development process can be roughly divided into the following stages:
The first stage, the equipment import stage. Initially in the 1960s and 1970s, due to the needs of my country's economic development, from metallurgy, petrochemical, electric power, building materials, railways and other systems, a considerable number of various automatic weighing instruments were imported at the same time as the complete system was imported. The wide range almost includes all varieties of automatic weighing instruments, which laid the foundation for the subsequent development of my country's automatic weighing instrument industry; The second stage, the technology introduction stage. In the 1980s, due to the needs of reform and opening up, during the Sixth Five-Year Plan to the Seventh Five-Year Plan, my country invested nearly 100 million yuan from the light industry and electromechanical departments, and introduced electronic price scales, electronic belt scales, electronic truck scales, dynamic electronic track scales, metering coal feeder technologies from Japan, the United States and other advanced Western industrial countries, as well as subsequent bulk grain electronic hopper scales, quantitative feeders, quantitative packaging scales, intelligent combination scales, weight sorting scales and other electronic weighing instrument product technologies;
The third stage: technology imitation stage
This stage started in the mid-1990s. For foreign-funded enterprises, it was mainly a simple scaling of structural dimensions based on digestion and absorption. For some state-owned and private enterprises dedicated to the production of automatic weighing instruments, it was mainly a simple mapping and imitation of imported products;
The fourth stage: independent research and innovation stage
This stage has begun since the beginning of this century. Strictly speaking, it is still in the beginning and ongoing tense. In order to occupy more market share of China's automatic weighing instruments, most foreign-funded, state-owned and private automatic weighing instrument manufacturers have begun to independently develop low-cost and high-quality automatic weighing instruments that can adapt to the Chinese market. This change can be seen from the annual increase in the number of invention and utility model patents applied. Of course, there is still a long way to go for patents to be recognized by the market.
The following discusses the development history, current situation and prospects of automatic weighing instrument products in different categories.
2. Development history, current situation and prospects of continuous cumulative automatic weighing instrument technology
Continuous cumulative automatic weighing instruments mainly refer to belt-type continuous cumulative automatic weighing instruments, referred to as belt scales. The first mechanical non-quantitative belt scale appeared in my country in the 1950s, and the real electronic non-quantitative belt scale appeared in the 1960s. At that time, the Beijing Hoisting and Transportation Machinery Research Institute of the Ministry of Machinery and Yingkou Instrument Factory No. 3 jointly developed and produced the first generation of electronic non-quantitative belt scales. Subsequently, the Shanghai Industrial Automation Instrumentation Research Institute of the Ministry of Machinery, Taiyuan Institute of Technology and other units also developed all-electronic non-quantitative belt scale products.
In the 1970s and 1980s, with the development of my country's economy and the need for reform and opening up, a considerable number of various belt scale products were imported from metallurgy, electricity, building materials and other systems while importing complete sets of systems. The most prominent feature of this stage was that Shanghai Baosteel Group imported a considerable number of non-quantitative/quantitative belt scale products produced by Yamato of Japan in the first and second phases of the project. Due to the stable and reliable quality of the product, it won the recognition of the Chinese market. In the 1970s and 1980s, the Ministry of Machinery organized Yingkou Instrument Factory No. 3 to introduce non-quantitative/quantitative belt scale complete product technology from Yamato of Japan; Shanghai Huadong Electronic Instrument Factory introduced non-quantitative/quantitative belt scale complete product technology from Melick of the United States; Chengde Automation Measuring Instrument Factory and Chengdu Scientific Instrument Factory introduced quantitative belt scale complete product technology from Schenck of Germany; the Ministry of Light Industry organized Xuzhou Weighing Instrument Factory to introduce non-quantitative/quantitative belt scale complete product technology from Ramsey of the United States; the Ministry of Electric Power organized Shenyang Electric Power Repair Factory to introduce coal feeder (quantitative belt scale) complete product technology from Yamato of Japan to establish Shenyang Huadian Company; the Ministry of Electric Power introduced coal feeder (quantitative belt scale) complete product technology from Stock of the United States to establish Shenyang Stock Company; at the same time, Shanghai Power Generation Equipment Research Institute and Shanghai Heavy Machinery Factory also introduced or imitated Stock coal feeder technology from the United States. The development of pressure-resistant metering coal feeder, one of the most critical weighing equipment in my country's thermal power generation industry, represents that my country's electronic belt scale product technology has developed to a higher level. At the end of the last century and the beginning of this century, a number of former state-owned enterprises, colleges and universities, and scientific research institutes separated due to institutional problems. Many private enterprises, such as Nanjing San'e, Chengde Chengshen, Xuzhou Huaneng, Xuzhou Sanyuan, Shanxi Xinyuan and other well-known enterprises have independently developed various belt scale products. At this stage, joint ventures such as Beijing Yamato introduced Japan's Yamato CFC-100 belt scale instrument technology; Shanghai Yamato fully introduced Japan's Yamato and non-quantitative/quantitative belt scales including sensors, instruments and whole machine development technology for pressure-resistant metering coal feeders after the Japanese side increased its capital and took control; Xuzhou Ramsey transformed from a joint venture to a private enterprise and established Xuzhou Saimo Group to establish a mechanism of self-development after introduction.
At present, my country is mainly dominated by two categories of products: non-quantitative belt scales and quantitative belt scales. Other non-belt continuous cumulative automatic scales cannot compete with the above two products in terms of quantity. However, the continuous loss-in-weight scale, rotor feeder, spiral feeder, impulse flowmeter and other structures have expanded the application scope of continuous cumulative automatic scales. In particular, continuous loss-in-weight scales, rotor feeders and other products have broken through the traditional dynamic weighing mode, and transformed from instantaneous weighing to continuous cumulative weighing, which can greatly increase the structural space and have advantages for the continuous cumulative weighing of some special powders and sticky materials. At present, quantitative belt scales have been widely used in occasions of continuous batching and feeding metering of bulk materials. They are the most widely used products of quantitative continuous cumulative batching and feeding automatic scales in my country, and they have a great development trend of replacing non-quantitative belt scales.
In general, the structural forms of the load-bearing devices of non-quantitative belt scales and quantitative belt scales in my country have not completely broken through the above types. In particular, some non-quantitative belt scale manufacturers do not work hard on sensors, instruments, structures and control systems, but only pursue quantity, not quality. At present, there is a trend of more and more abuse, and belt scales with a sales price of less than 20,000 yuan are everywhere. The mechanical structure is shoddy, and the reliability of sensors and instruments is far from meeting the requirements of the harsh environment on site. At present, there is still a lack of practical breakthroughs in basic testing and theoretical research for different harsh environments on site. Since the dynamic accuracy of belt scales is affected by too many factors of environmental changes, it should be objectively said that the reliability application and research of belt scale products in my country are still quite backward compared with the advanced level abroad. The stability detection method of belt scales has always been a restrictive factor that troubles and hinders the accuracy of belt scales in my country. The belt scale test base built in Tongling, Anhui in the 1980s was once used as an evaluation site for the performance test of the whole machine for the market access of the Ministry of Electric Power's belt scale products, but unfortunately it has been abandoned for various reasons. In recent years, my country has made breakthroughs in the development of material simulation test devices and achieved remarkable results. The cycle chain code test, empty material segment chain code test, and material weight superposition test have all achieved phased results, which are closer to automatically performing dynamic inspections on belt scales without changing the material conveying conditions. However, most manufacturers and users have overlooked one point, that is, the first accuracy confirmation of belt scales must be determined by physical tests. At present, the above methods developed in China can only be used as stability inspection methods in daily use. Fortunately, some far-sighted enterprises have realized the seriousness of this problem. An intelligent and automated dynamic testing center for belt scales that integrates various on-site working conditions has passed provincial acceptance.