< class="p" style=""> 1. Background
In the production process of gypsum board, due to the influence of various factors such as equipment, process, raw materials, etc., various defective products are often produced, such as surface defects, uneven width, uneven thickness, non-vertical edges, etc. These defects seriously affect product quality and corporate reputation. At present, the detection of these defects in the market is generally done manually, but the detection quality cannot be guaranteed because of the influence of the environment, fatigue, and emotions on human labor.
Xi'an Huode has conducted repeated field tests and verifications and continued research and development for more than seven years. It has utilized the company's own technological advantages and integrated high-tech technologies such as artificial intelligence technology, machine vision technology, structured light technology, embedded control technology, laser technology, network technology, automatic control technology, and database technology. It has worked hard to overcome many unfavorable conditions at the gypsum board production site, such as high temperature, high dust, high production line speed, and complex and changeable process. It has developed a complete set of gypsum board quality online detection equipment, which has effectively solved the above-mentioned problems.
Xi'an Huode, based on the notice of the "Action Plan for Digital Transformation of Intelligent Manufacturing in the Building Materials Industry (2021-2023)" issued by the General Office of the Ministry of Industry and Information Technology, went deep into the production line, broke through key core technologies, and created hard technology. The system realizes real-time online quality detection of the production process, truly solving a major pain point in product quality control in the gypsum board industry for many years, improving and stabilizing product quality, saving labor costs, and obtaining first-hand data of the production process. It solves the most critical underlying support for digital factories and intelligent manufacturing, completes the informatization of the "last mile", and lays a solid foundation for the establishment of intelligent manufacturing and digital factories in the gypsum board industry.
< class="p" style=""> 2. R&D Process
< class="p" style=""> 1. Initial development
Since March 2018, we have been continuously developing the following equipment at Beixin Xinxiang Gypsum Board Factory. This process will last for 5 years until 2022. We call the entire device of this process version 1.0;
(1) Mobile width detection device. Finally, due to the on-site environment and the fact that the mobile structure could not guarantee the accuracy requirements for long-term operation, it was dismantled.
(2) Fixed width detection device. We pioneered the development of this device, which stably and reliably solved the problem of width detection and has been used ever since.
(3) Upper and lower paper hole detection device: Using our "machine vision" technical expertise, we successfully completed the paper surface defect detection. This device has been in normal use until now. However, due to the supplier's improvement in paper quality, subsequent gypsum board manufacturers did not further adopt it.
(4) Vertical edge detection device: We pioneered the use of "machine vision" 3D measurement technology to complete the detection and display of the vertical edge of the board. This device has been in normal use to this day. Sometimes the camera lens is blurred and cannot be measured due to dust not being cleaned in time, and sometimes the device is displaced and cannot be measured due to a bun failure.
(5) Automatic control device for edge standing: This device was originally intended to achieve closed-loop control of the edge standing. However, due to the complexity of the on-site conditions and the large number of factors that affect the edge standing, the purpose of controlling the edge standing could not be achieved by controlling the clamping plate alone. As a result, this device has not been successfully applied and is still under development.
(6) Panel defect detection device: This device requires high precision (0.05mm) to detect the defects of the entire panel surface, such as bumps, bubbles, wrinkles, and slurry leakage. It is a large-format (including swings up to 1.5 meters wide) and high-speed (up to 120 meters/minute) 3D measurement. There is currently no mature solution. After many principle discussions and practices, we have creatively adopted single-line structured light + array camera + original 3D algorithm to perfectly solve this problem. This device is currently running stably and is still in use today. However, there have been many twists and turns in the research and development process, especially the design, heat dissipation, dust prevention, and stability of the multi-line laser structured light device, which have been repeated many times, as well as the vibration of the panel surface, the influence of dust, and the optimization of the installation structure.
(7) Double-board defect detection device: This device is similar to the above device, but is twice as large as the above device.
(8) Inkjet marking device: In order to eventually remove defective boards, they must be marked. Initially, we used an inkjet marking device to basically solve this problem.
(9) Marking and rejection device: Use a "machine vision" device to automatically identify early inkjet marks, send a signal to the PLC that controls the production line, and reject defective boards.
(10) Online thickness detection device: Originally uses laser technology to automatically detect the thickness of the board, which improves the board size measurement.
(11) Wedge edge measurement device: Using "machine vision" + laser technology, the width and depth of the wedge edge can be automatically measured in real time. (12) Supporting server and application program.
2. Continuous Improvement
Starting from August 2022, based on version 1.0, we gradually started the design and manufacture of equipment for Tianjin, Jinggangshan, Fuping and Gucheng plants under Beijing New Building Materials. These four sets of equipment are version 2.0. We further explored and developed some new online detection devices, as well as optimized and improved some version 1.0 devices. This process will continue until 2024.
(1) Tianjin and Jinggangshan, as the two pilot factories of Beijing New Building Materials in the north and south, are equipped with a full-function testing system. Due to the raging epidemic during the equipment processing period, many supporting work was not in place, and some equipment processing was repeated, resulting in a delay in the project progress.
① Thickness measurement device: Based on version 1.0, the thickness measurement system is further improved, taking into account the influence of power supply and temperature, adding dust removal function, high-precision low-beam sensor, long-distance transmission signal loss and interference problems, etc.
② Panel defect detection device: mainly changes the single-line laser to a multi-line laser, which improves the response speed and monitoring accuracy. However, this laser does not have a standard product. The development of it has gone through many twists and turns, solving engineering problems such as electric cooling, heat dissipation, dust prevention, and impact, and there have been many repetitions. Now this device can be stably operated in various places.
③ Code reading device: Although the inkjet system in Xinxiang can solve the marking problem, it adds a set of inkjet devices, which consumes ink and increases costs. The Tianjin 2.0 solution completely eliminates the inkjet marking system in Xinxiang and uses "machine vision" to automatically read the time mark (code reading device) on the board surface. This perfectly solves the problem of positioning the board during marking and rejection. This device has been running all the time, but there are also problems with inaccurate code reading due to untimely maintenance and dust.
④ Temperature and humidity measurement in the heating furnace: Online detection of temperature and humidity in the heating furnace solves the problem of real-time online detection of temperature and humidity in the heating furnace under high temperature. This set of equipment has been in use.
⑤ Bubble diameter detection device : Using "machine vision" technology, we have specially developed a gypsum board bubble diameter digital detection system, which provides an effective means to improve the foaming quality. For details, please refer to "Gypsum Board Bubble Diameter Digital Detection System Solution (Promotion) v2.1"
⑥ Dynamic detection device for evaporation between layers of dryer: The board surface temperature is detected by non-contact infrared thermal imager, which monitors the temperature of the gypsum board coming out of the dryer. Continuous detection can estimate the temperature inside the furnace. We designed and produced special devices and software for this system and conducted on-site tests, but due to the installation location, it did not achieve the expected purpose.
(2) Fuping and Gucheng, according to customer needs, only partial function detection devices were installed.
①Fuping, dynamic weighing device for dry board: We pioneered the design of a dynamic weighing device in the gypsum board industry, which solved the problem of automatic detection of the single weight index of the gypsum board. The test results were good, and this device has been working stably until now. For details, please see "Fuping Gypsum Board Weighing Test Report 9.17-18-1".
② Fuping, diagonal size online measurement device : Using "machine vision" technology, we designed and manufactured the first diagonal size online measurement device in the gypsum board industry, verified the correctness of the principle, and deeply analyzed the relationship between accuracy, error and moving board. At present, this system still needs to be tested and its accuracy needs to be further improved to meet production needs.
(3) Yichang: A subsidiary of Taishan Gypsum Co., Ltd.
① 3D camera: For the first time, 3D camera was used to measure wedge edge, width and vertical edge. Although the cost is higher, the system is more concise, stable and easy to install. It has been running normally so far.
② Automatic slurry area detection device: uses "machine vision" to detect the slurry area and outputs signals to the control PLC.
(4) In the above five factories, many process problems were solved, such as the elimination of short boards, different elimination lines, automatic switching of QR code recognition, and inkjet code recognition, and more process scenarios were understood;
3. Pursue excellence
Since August 2023, we have conducted a comprehensive discussion and review of version 2.0. By integrating all the functions of the second control, further improving and improving the equipment of the first and third control, and enhancing the functions of the server, we have greatly simplified the difficulty of on-site renovation and installation, simplified operation, enhanced reliability, reduced maintenance work, and further improved the standardization of equipment. We have officially launched version 3.0. For an introduction to version 3.0, please refer to "Gypsum Board Appearance Quality Inspection System V3.0"
< class="p" style=""> 4. Some insights
(1) The gypsum board industry is a niche industry, with only more than 100 production lines nationwide. In terms of automatic testing, large manufacturers have no motivation to invest manpower and material resources to conduct in-depth research and exploration and cultivate this industry. However, due to marketization, some small companies have also made some attempts. However, faced with the harsh production environment of gypsum boards, such as high temperature, low temperature, dust, mud, vibration, impact, high-speed movement, etc., as well as many comprehensive technologies such as machine vision, laser, artificial intelligence, databases, etc., many small factories have only tried briefly, some have given up halfway, and some have failed.
(2) Xi'an Huode entered this industry by chance. Since 2018, we have spent more than 7 years to innovatively design and develop more than 22 online detection devices in this industry. We have raised funds on our own and invested more than 5 million yuan in total, spending a lot of manpower and material resources. Together with our customers, we have been continuously exploring and solving problems encountered, and continuously improving and perfecting them. This process is really difficult and long! Of course, our huge investment has also made us naturally become the leading provider of complete sets of technologies and equipment in this industry nationwide. Yes, we naturally stand at the forefront of automatic detection in this industry. Of course, technology is endless. Compared with similar foreign products, we still have a lot of work to do, such as moisture content measurement, high-precision plate length detection, etc.
(3) The law of product research and development requires continuous iteration, continuous investment, and strong support from users to achieve perfection and stability. Moreover, the gypsum board industry involves more than 20 kinds of testing devices and technologies, so user support is particularly important. At present, we are the only manufacturer in the domestic gypsum board industry that can provide a complete set of online testing equipment. We hope to continue to receive strong support from customers in the gypsum board industry so that we can continue to launch new testing equipment and continuously iterate to contribute to the construction of digital factories in the gypsum board industry.
< class="p" style=""> 3. Main issues solved and features introduced in version 3.0
1. Automation of dimension measurement: fully automatic measurement of basic dimensions such as vertical edge, wedge edge, width and thickness.
2. Automation of defect detection: automatic measurement of appearance defects such as bumps, wrinkles, slurry leakage, bubbles, and board printing.
3. Automatic report generation: Automatically generate reports on output, yield, scrap rate, classification statistics of defective boards, etc.
4. Digitalization of the production process: Automatic detection of gypsum board production lines is the most critical basic support and solid foundation for gypsum board digital factories and intelligent manufacturing.
5. For a detailed introduction of the functions, please refer to "Gypsum Board Appearance Quality Inspection V3.0"
< class="p" style=""> 4. Investment and Return Calculation
1. The following table shows the production statistics of the xx factory in one week. On average, about 35,000 2.4-meter standard boards are produced every day. Each board is sold at 28 yuan, and the daily output value is 980,000 yuan. Calculated based on 300 days a year, the output value is about 294 million yuan. The cost of each meter of standard board is about 3.5 yuan, and labor, materials, and energy each account for one third:
< class="p" align="center" style="">
2. By using this system, considering the measurement of thickness, width, vertical edge angle, wedge edge, board surface defects, automatic rejection, report generation, etc., it is estimated that one person can be reduced, and 3 shifts can reduce 3 people. The per capita cost is calculated as 100,000, and 300,000 yuan can be saved annually;
3. The main function of this device is to monitor the quality of the gypsum board production process, mainly to monitor the board size and appearance defects in real time. Once a defect is found, an alarm will be issued in time to prompt manual intervention; from this point of view, it can reduce the escalation of the situation, reduce waste, reduce energy consumption, improve the yield rate, and improve efficiency. This requires statistics for a period of time (for example, 1-2 months) when this set of equipment and this set of systems are not used as a support. However, by eliminating the number of defective boards and the number of consecutive times, a rough estimate can be made.
(1) Once a defect is detected, the plate will not enter the oven and will be directly dehumidified, saving energy: 200 sheets
(2) Timely reporting of accidents to reduce the risk of accidents and the number of defective boards per day: 400
The above total can save energy costs every year 300 days x 600 sheets x 10/6 = 300,000;
4. Remove defective boards to ensure quality and prevent them from entering the market. The goodwill value generated by this is inestimable.
< class="p" style=""> V. Comparative advantages of Huode products and other similar products
LIMAB: A Swedish company founded in 1979, it is dedicated to the research and development of measurement systems for the gypsum board industry. It is used in several factories in China. Due to the well-known high prices, untimely delivery and service of foreign brands, it is difficult to promote them. However, its size measurement system and moisture content online detection system are very unique and worth learning and studying.
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