Research progress of commercial chestnut incision machine *
Yang Lubei ^(1){ }^{1} , Li Guofang ^(1){ }^{1} , Chen Lidong ^(1,2){ }^{1,2} , Ren Xiaoguang ^(1,2){ }^{1,2} , Cui Xiaoyu ^(1){ }^{1} (1. School of Mechatronics Engineering, Hebei Normal University of Science & Technology, Qinhuangdao, Hebei, 066004; 2. Board Industry Technology Education Ministry Engineering Research Center, Qinhuangdao, Hebei, 066004)
Abstract
Abstract: The cut is the first process in the processing of sugar-cooked chestnuts in supermarkets, playing an important role in China's deep processing industry of chestnuts. Currently, chestnut cutting is either manual, with high labor costs and low efficiency, or batch unordered mechanical shelling, with high nut damage rate, irregular cut shapes, and unable to meet the cut requirements of supermarket chestnuts. Based on the analysis of the technical requirements for cuts of sugar-cooked chestnuts in supermarkets, this paper elaborates on the structure and working principles of different types of chestnut cutting machines, summarizes the advantages and disadvantages of various types of chestnut cutting machines, and outlines the current research status of chestnut cutting machines at home and abroad. It analyzes the problems existing in chestnut cutting machines, such as low production efficiency, high nut damage rate, inaccurate cut position, poor opening quality, poor equipment adaptability and reliability, and incomplete cut technical standards. Development strategies are proposed to optimize the cutting process, improve cutting efficiency and quality, introduce machine vision technology to enhance the intelligence level of cutting, improve the standardized production system to enhance the versatility of equipment, etc.
Chinese Library Classification Number: S226.4 Document Code: A Article Number: 2095-5553 (2023) 03-0101-07
Yang Lubo, Li Guofang, Chen Lidong, et al. Research Progress on Supermarket Chestnut Cutting Machine [J]. Journal of Agricultural Machinery of China, 2023, 44(3): 101-107
Yang Lukun，Li Guofang，Chen Lidong，et al．Research progress of commercial chestnut peeling machine［J］．Journal of Chinese Agricultural Mechanization，2023，44（3）：101－107
Research progress of commercial chestnut peeling machine
Yang Lukun ^(1){ }^{1} ，Li Guofang ^(1){ }^{1} ，Chen Lidong ^(1,2){ }^{1,2} ，Ren Xiaoguang ^(1,2){ }^{1,2} ，Cui Xiaoyu ^(1){ }^{1} (1. College of Electromechanical Engineering, Hebei Normal University of Science & Technology, Qinhuangdao, 066004, China; 2. Engineering Research Center of Chestnut Industry Technology, Ministry of Education, Qinhuangdao, 066004, China)
Abstract
The incision is the first step in the process of stir-fried Chinese chestnut with super sugar, which plays an important role in the deep processing industry of Chinese chestnut. At present, chestnut cutting by manual operation with high labor cost and low efficiency; or by batch disordered mechanical shell breaking with a high kernel damage rate and irregular incision shape, cannot meet the requirements of commercial chestnut incision. Based on the analysis of the incision technical requirements of stir-fried chestnuts with super sugar, the structure and working principle of different types of chestnut cutting machines were expounded, and the advantages and disadvantages of various types of chestnut cutting machines were summarized. This paper summarizes the research status of chestnut cutting machinery abroad, analyzes the problems existing in chestnut incision machinery, such as low productivity, high damage rate of chestnuts, inaccurate position of cutting, low quality of opening, poor adaptability of equipment, low reliability, and imperfect cutting technical standards. The development strategies of optimizing the incision process, improving the efficiency and quality of the incision, introducing Machine vision technology, improving the intelligent level of the incision, perfecting the standardized production system, and enhancing the versatility of the equipment are proposed.
Keywords: chestnut; incision equipment; working principle of the incision; mechanical incision; laser type incision
0 Introduction
Chinese chestnut (Castanea mollissima BI), also known as chestnut or hairy chestnut, belongs to the genus Castanea in the family Fagaceae ^([1]){ }^{[1]} . Chestnuts are nutritionally rich and are renowned as "wooden grain food and iron stem crops" ^([2]){ }^{[2]} . China is a major producer of chestnuts, with production areas spanning the country, particularly in Hebei, Henan, Anhui, Zhejiang, Guizhou, and Jiangsu provinces. In the 1950s, the yield was 289.2 kt, which rose to 830 kt by the mid-1980s, and the cultivation area expanded fivefold compared to the mid-1980s by the late 1980s ^([3]){ }^{[3]} . According to statistics from the Food and Agriculture Organization of the United Nations, as of 2021, China's chestnut harvested area 295.661khm^(2)295.661 \mathrm{khm}^{2} reached 1710 kt, ranking first in the world in both area and yield.
Our country's chestnuts are rich in nutrition and of high quality, and are renowned as the "Crown of the World's Chestnuts." Our country offers a variety of chestnut products, such as chestnut flour and chestnut paste made from ground chestnut kernels, chestnut beverages, candied chestnut tins, and roasted chestnuts, etc. ^([4-5]){ }^{[4-5]} . Deep-processed chestnut products are sweet and delicious with fine texture, and are highly popular. The cutting process is an essential first step in deep processing chestnuts, and it has a profound impact on the quality of chestnut products. Although China ranks first in the world in terms of chestnut cultivation area and production, our deep processing technology lags behind developed countries. In developed countries, chestnut processing primarily aims to completely remove the shells, with diverse machinery and high mechanization levels, achieving a processing conversion rate of over 90%90 \% . While China's mechanization level in chestnut deep processing has been increasing year by year, research on chestnut cracking technology is still in its early stages. The mechanization level of cutting is low, with most enterprises still using manual cutting, resulting in high labor costs, low safety, low productivity, and unreliable quality of chestnut kernels. Currently, China's chestnut processing conversion rate is only 20%20 \% , with low mechanization levels in chestnut processing. The opening process faces issues such as high kernel damage rates, irregular cut shapes, and insufficient cutting precision, which have severely hindered the rapid development of the chestnut processing industry.
Among various chestnut products, supermarket roasted chestnuts require neat cuts to facilitate peeling after roasting. Therefore, the cutting process is particularly important. This paper analyzes the current research status of chestnut cutting machines both domestically and internationally, addresses the problems in supermarket chestnut mechanized cutting, and proposes measures to improve cutting quality, aiming to accelerate the development of chestnut deep processing technology.
1 Requirements for Supermarket Chestnut Cutting Technology
Chestnuts sold in supermarkets are primarily processed through roasting, and before roasting, cuts are made at specific positions on the chestnut surface to facilitate peeling along the cuts. Chestnuts have irregular shapes, resembling hemispheres with one end nearly flat and the other curved. A simplified chestnut model is shown in Figure 1. The simplified chestnut model can be described by three dimensions: the maximum dimension ll is the length of the flat side, the minimum dimension is the height of the curved surface hh , and the width is ww .
The process of cutting chestnuts for supermarkets requires cutting along the middle part of the left side arc, the top surface, and the right side surface of the outer periphery of the chestnut. The cut needs to cover three surfaces of the chestnut, break the outer shell, but not damage the inner membrane of the chestnut. The opening depth is approximately 1∼2mm1 \sim 2 \mathrm{~mm} . To achieve the cutting requirements for supermarket chestnuts, cut
Cutting tools should be cut along the ll direction of the chestnut's external dimensions, perpendicular to the ww direction. The tool's movement path is shown in Figure 2, and the qualified cut is shown in Figure 3.
Figure 1 Chestnut Model
Fig. 1 Chestnut model
Figure 2 Schematic diagram of chestnut incision position
Fig. 2 Schematic diagram of chestnut incision position
Figure 3 Qualified chestnut incision diagram
Fig. 3 Qualified chestnut incision diagram
Existing chestnut peeling machines have been reported in the literature, with different working principles and varying performance, and few peeling machines can meet the three-side peeling requirements of commercial supermarkets; there are also no commercially available chestnut peeling machines. To advance the research on supermarket chestnut peeling machines, a classification and organization of peeling machinery have been conducted, analyzing the advantages and disadvantages of different peeling machines, and measures to improve peeling performance have been proposed.
2 Types of Existing Supermarket Chestnut Peeling Machines
Chestnut peeling methods can be divided into two types: mechanical peeling and laser peeling. Mechanical peeling breaks the shell through methods such as squeezing, rotating cutting, and collision friction. Squeezing-type peeling machines typically配备配备 cross-shaped blades, which reciprocate to embed into the chestnut shell through impact and squeezing. Rotating cutting machines often配备配备 circular blades, which move in a rotational motion to create linear cuts on the surface of the chestnut shell. In collision friction peeling machines, the rotating blade disc stirs the chestnuts and cuts through the shell, removing the entire shell ^([8]){ }^{[8]} .
Laser peeling uses a focused, high-power, high-density laser beam to irradiate the chestnuts, creating a shallow cut on the surface. As the chestnuts heat up, they expand, and the air flow at the shallow cut pushes the shell open ^([9-12]){ }^{[9-12]} . Laser cutting equipment has excessively high production costs, and literature reports show that mechanical peeling machines are more common. The comparison of the existing main types of chestnut peeling equipment in terms of peeling principles, working processes, and advantages and disadvantages is shown in Table 1.
Table 1 Comparison of Various Chestnut Incision Machines
Tab. 1 Comparison of all kinds of chestnut incision machines
Type
Working Principle
Constitution
Working process
Pros and cons
Single-row cross栗 cutting machine
Extrusion cut
Feeding device, conveying device, cutting device, power device
Chestnuts enter the groove of the conveyor chain plate through the hopper under the action of gravity, and the chain plate transports the chestnuts to the lower part of the blade; the blade performs reciprocating vertical motion, impacting and extruding the surface of the chestnuts to form a cross-shaped incision
Can achieve opening of chestnuts with similar sizes; the size of chestnuts needs to match the groove, without chestnut holding device, chestnuts may deviate from the groove during cutting, cannot guarantee accurate cutting position
Chestnuts fall down to the conveying device by their own weight, during the conveying process, the clamping device presses the chestnuts into the material position and clamps them, the blade makes a rotational motion, cutting a one-character type opening on the surface of the chestnut shell
The pressing device can ensure the position of the chestnut during cutting to some extent, adapt to the processing of chestnuts of different sizes, the cutting depth is adjustable, and the production rate is relatively high; it cannot guarantee three-side cutting
Lack of material for chestnuts is adjusted by a vibration motor into a row, determined the correct position by a positioning device, enters the laser emission device, the laser beam irradiates the chestnuts, and cuts grooves on the surface of the chestnuts
Simple structure; there is a gap between the chestnuts and the positioning device, the positioning accuracy is low, and the cost is high
Chestnut shell grooving machine
Impact cutting
Feeding device, roller, agitating device, cutting device, gap adjustment device
Chestnuts are batched into the roller, disturbed by the action of the agitating device, while the cutting blade at the bottom of the roller rotates at a certain speed, colliding with and piercing the chestnut shells of the moving chestnuts
Chestnuts are continuously cut, with high production efficiency; the cuts are random, resulting in high damage rate to the chestnut kernels, suitable for chestnut dehulling
Due to different dietary habits and sales markets, there is relatively low demand for candied chestnuts abroad, and the requirements for the position and shape of the chestnut切口 are not stringent. A separate切口 processing technique has not been formed, nor has there been specialized research on the chestnut切口 device. Typically, the goal is complete dehulling, ensuring that the chestnut shells are removed cleanly, without placing excessive precision requirements on the position and depth of the chestnut切口.
In French chestnut processing production lines, chestnuts are dehulled through mechanical extrusion and grinding, as well as by burning. In Figure 4, chestnuts first enter the combustion chamber for roasting, then enter the extrusion and grinding chamber to have their shells removed. This device is often connected to the dehulling process and is suitable for continuous operation.
Figure 4 Schematic diagram of a French chestnut dehuller
Fig. 4 Schematic diagram of French chestnut sheller
The chestnut peeling machine developed in Japan, as shown in Figure 5, transports the chestnuts to the scraping conveyor by the elevator. As the chestnuts are pushed from one end of the conveyor to the other, the roller blades below make incisions on the surface of the chestnuts; the high-speed striker removes the broken shells, completing the peeling process. By coordinating the rotation of the shell-kernel separation device and the high-pressure air nozzle, the shell and kernel are separated.
Separation. The device opens the chestnuts in an unordered state and peels them, easily damaging the nut meat, suitable for continuous operation.
Fig. 5 Schematic diagram of Japanese chestnut sheller
1. Nut container 2. Cracked nut outlet 3. Whole nut outlet 4. Fan 5. Drive unit 6. High-speed blades 7. Elevator 8. High-speed striker 9. Material scraper conveyor 10. Rotating shell-separation machine 11. High-pressure nozzle Korean chestnut sheller is shown in Fig. 6.
Fig. 6 Schematic diagram of Korean chestnut sheller
1. Roller motor 2. Sleeve motor 3. Right shell chamber baffle 4. Bearing cover 5. Center roller 6. Bearing 7. Large pulley 8. Inlet 9. Feeding hopper 10. Bearing 11. Friction device 12. Chestnut pusher 13. Outer sleeve 14. Bearing 15. Bearing cover 16. Left shell chamber baffle 17. Outlet 18. Frame 19. Rubber disc cover 20. Drum 21. Disc tooth blade 22. Disc blade edge 23. Friction contact part 24. Sleeve motor
Date of Submission: October 16, 2022 Date of Revision: December 7, 2022
*Funding Sources: National Key R&D Program Project (2020YFD1000702-3); Hebei Province Graduate Course Ideological and Political Education Demonstration Project (YKCSZ2021160); Hebei Province Chestnut Industry Collaborative Innovation Center Project (2021)
First Author: Yang Lubei, male, born in 1997, from Dezhou, Shandong, master's degree; research direction is agricultural product processing machinery design. E-mail: m17852277608@163.com
Corresponding Author: Li Guofang, female, born in 1970, from Tangshan, Hebei, Ph.D., professor; research direction is harvesting machinery design. E-mail: lgfqyb@aliyun.com
