Microsoft Word - 01-AMME0958排版.docx
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Research and Application of Motor-Driven Gear-Rack Pre-
compression Packaging Machine Set
Shuiming Wang1, 2, *, Pengfei Li1, 2, Jiazhi Ni1, 2, Dong Li1, 2, Qianjin Chen1, 2,
Hao Wang1, 2, Xiangang Zhou1, 2, Jianhua Liu1, 2, Rui Peng1, 2, Li Wang1, 2,
Tao Qiu1, 2, Lianfeng Huang1, 2
1China Tobacco Hubei Industrial Co, Ltd, Wuhan 430000, China
2Hubei Xinye Reconstituted Tobacco Development Co, Ltd, Wuhan 430000, China
*Corresponding author e-mail: 1430173134@qq.com
Abstract. The tobacco sheet pre-compression and packaging machine is primarily used for the pre-
compression and packaging process in the reconstituted tobacco production line. It compresses the
loose reconstituted tobacco sheets (after being weighed) that have been sliced by a shredding
machine and boxed into a tobacco sheet pile of a specific size and specification, meeting the
packaging and transportation requirements of subsequent processes. Currently, pre-compression
and packaging machines in the reconstituted tobacco industry utilize hydraulic systems for
packaging due to their unique characteristics and installation positions (with piston rods and pressing
heads located within the packaging material box). The transmission medium primarily relies on
hydraulic oil. During the process of the piston rod descending to compress the package, the piston
rod emerges from the main cylinder, bringing out a certain amount of oil film, which poses a risk of
contamination in the tobacco leaves. Starting from the source of risk control, namely the hydraulic
oil, this paper conducts research and design on the power source of pre-compression and packaging.
The power system is converted from hydraulic drive to electric motor drive, transforming the hydraulic
pre-compression and packaging machine into an electric motor-driven rack and pinion pre-
compression and packaging machine. This change eliminates the risk of oil contamination from the
source and simultaneously achieves effective energy savings and reduces spare part and
maintenance costs.
Keywords: Reconstituted Tobacco Leaf; Pre-compression and Packaging Machine; Rack and
Pinion Drive System.
1. Introduction
The pre-compression and packaging machine used before the modification was a dual-hydraulic
pre-compression and packaging machine driven by a variable-frequency motor-powered hydraulic
pump. Research has shown that this hydraulic system mainly has the following issues: Firstly, the
power source employs hydraulic drive, and there is a potential risk of hydraulic oil leakage in the
hydraulic system, posing a significant threat to the purity of the finished tobacco leaves. Secondly,
during equipment operation, there is significant noise and vibration, and it is difficult to directly
diagnose faults in the hydraulic system. Only those familiar with the hydraulic system can identify
and address issues, requiring a large number of maintenance personnel, a long period, and significant
difficulty. Thirdly, when the over-frequency motor operates at low frequencies, the self-priming
capacity of the vane pump decreases, generating pulsating torque, which causes fluctuations in motor
speed and insufficient low-frequency torque, resulting in poor low-speed stability of the system. Since
the system uses a high-power 25 KW motor, it has a large rotational inertia, leading to slow system
response and low control accuracy (Figure 1). [1]-[3]
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Figure 1. Double-Hydraulic Pre-Pressing and Packaging Machine of Hubei Xinye Tobacco
Sheet Development Co., Ltd.
2. Technical Research
The new pre-compression and packaging system is designed to address the issues existing in
current production. Therefore, it is necessary not only to ensure the stability and reliability of the
system but also to completely eliminate the risk of hydraulic oil contamination from the source.
Additionally, the economic costs of equipment construction and maintenance should be considered,
facilitating ease of maintenance for repair personnel. Taking all these factors into account, our
company, in collaboration with Kunming Shipbuilding Equipment Group Co., Ltd., after continuous
research and verification, ultimately proposed the adoption of a motor-driven rack and pinion pre-
compression and packaging system to replace the original hydraulic system of the hydraulic
packaging machine[4]-[6].An electric servo torque and speed synchronization system technology was
also adopted to ensure the synchronous drive of the pressing heads and meet the requirements for
speed, pressure, and pressure holding time. The following table 1 compares the parameters of the
motor-driven rack and pinion pre-compression and packaging system with the hydraulic pre-
compression and packaging system:
Table 1. Comparison of Parameters Before and After Renovation
Model
Electric Motor-Driven Gear-Rack
Pre-compression Packing System
Hydraulic Pre-compression Packing
System
Packaging Specifications and Format
Compliant with YC/T 137.1-1998
standards or C48 cartons
Compliant with YC/T 137.1-1998
standards or C48 cartons
Rated Production Capacity (boxes/hour) 52 48
Maximum Dimensions (L×W×H) (mm) 8180×6430×9315
8180×6430×9315 (excluding
hydraulic pump station)
Hydraulic Pump Station (mm) None 3000×3000×1500
Feed Height (mm) 8745 8745
Discharge Height (mm) 610 610
Material Box and Pressing Head Drive
Motor Power (kW)
59 67
Hydraulic Oil Consumption (L) None 3500
Hydraulic Oil Cooling System None
Cooling tower, 3KW fan motor,
3KW water pump motor, 2.2KW
hydraulic oil circulation motor
Hydraulic Seal Wear None Yes (replaced every 2 years)
Estimated Gear Lifespan (years) 3 None
Estimated Rack Lifespan (years) 5 None
Hydraulic System Maintenance None Required
Risk of Hydraulic Oil Leakage None Present
Risk of Hydraulic Oil Contamination to
Tobacco Leaves
None Present
Maintenance Workload Low High
Maintenance Difficulty Easy Difficult
Maintenance Time Short Long
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3. Hydraulic Technology with Motor Drive Technology
3.1. Complete Replacement of Hydraulic Technology with Motor Drive Technology
3.1.1 The complete replacement of the hydraulic system with a motor-driven rack and pinion
eliminates the constraints imposed by the hydraulic system on the entire equipment, thereby
eradicating the risk of hydraulic oil leakage contaminating tobacco leaves.
3.1.2 The removal of hydraulic piping, hydraulic pump stations, hydraulic oil, hydraulic cylinders,
etc., significantly reduces the equipment's footprint and maintenance workload, eliminating the need
for periodic replacement of sealing rings, hydraulic oil, etc.
3.1.3 The system is energy-efficient, structurally simple, reliable, convenient for use and
maintenance, operates smoothly without noise, and significantly improves electrical control accuracy.
(Figure 2)
Figure 2. Conversion from Hydraulic Packaging System to Electric Packaging System
3.2. Driving the Pressing Heads with an Electric Servo Torque and Speed Synchronization
System
3.2.1 The original piston rods driving the pressing heads are removed, and rack gears on the left
and right sides of the pressing heads are used to drive their upward and downward movements. Since
it is necessary to ensure that the speeds of the rack gears on both sides match, an electric servo torque
and speed synchronization system technology is adopted to drive the pressing heads, achieving
synchronous operation of the rack gears. At the same time, while satisfying the pressing force
requirements, it fulfills the speed and pressure holding requirements of the pressing heads under
various operating conditions. (Figure 3,4)
Figure 3. Hydraulic Drive Converted to Electric Motor Drive
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Figure 4. Schematic Diagram of Ram Motion Process
3.2.2 The original hydraulic system operated continuously, but now with the adoption of the servo
electric drive system, it operates intermittently. Compared to the previous hydraulic pump, the new
system consumes no electricity during the rapid descent process, resulting in a significant reduction
in operating power. This significantly conserves energy consumption and aligns with the national
tobacco industry's requirements for improving quality and reducing consumption. (Figure 5)
Figure 5. Comparison Chart of Power Consumption
3.3. Rational Material Selection and Precision Machining to Ensure System Efficiency and
Stability
3.3.1 Military-grade processing techniques and quality standards are adopted to enhance the
meshing accuracy and transmission precision of the gears and rack gears, ensuring stable and reliable
transmission of the long rack gears. The maximum pressure of the original hydraulic packaging
machine was 12 tons, while the current electric-driven packaging machine can achieve a pressure of
up to 16 tons. (Figure 6)
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Figure 6. Military-Grade Machining Site
3.2.2 Military-grade ion plating technology is adopted to meet wear resistance and lifespan
requirements. (Figure 7)
Figure 7. Comparative Test of Military-Grade Ion Coating
3.4. Optimizing the Structure of the Pressing Head to Solve Practical Problems in Production
and Maintenance
The original pressing head, during the ascent after pressure holding, would lift some tobacco leaves
due to the adhesive properties between the leaves and the pressing head. This issue was particularly
evident when processing tobacco leaves with high oil content and a fluffy texture. During this
renovation, the structure of the pressing head was optimized in two ways: first, a material guiding
hood was added to the pressing head to prevent material accumulation above it, thereby solving the
problem of material being carried by the pressing head; second, a new non-stick coating technology
(PTFE coating) was applied to the pressing head to reduce the phenomenon of material sticking to its
underside. The left image below shows the pressing head before the renovation, and the right image
shows it after the renovation. (Figure 8)
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Figure 8. Optimized Structure Diagram of Press Ram
4. Application Effects
For the electrically-driven pre-compression and packaging unit of the tobacco threshing and air
classification equipment under research and application, we have evaluated its technical indicators,
conducted comparisons with traditional hydraulic packaging units in terms of economic benefits and
maintenance costs, performed energy-saving test verifications, and analyzed the benefits.
4.1. Technical Indicators Meet Standards
4.1.1 Through visual observation, the leaf rebound rate is relatively low, the molding is good, there
is less tobacco left on the ground at the site, and the hygiene is better. Through instrumental testing,
the packing density remains within 10.
4.1.2 The overall structure is simple and intuitive, with few faults, easy maintenance and repair,
easy location of fault points, good stability, and few spare parts required with low costs.
4.1.3 No equipment faults occurred during the operation of one tobacco drying season.
4.1.4 The gears and rack gears driving the material bin and pressing head are stable and reliable
during operation, with little wear.
4.1.5 When the equipment is running, the three channels driven by hydraulics can only operate
sequentially, not simultaneously, while the electrically-driven ones can operate simultaneously.
4.2. Significant Economic Benefits
4.2.1 Reduced Equipment Footprint: The electrically-driven pre-compressor eliminates the
hydraulic pump room, reducing equipment footprint by approximately 15m².
4.2.2 Lower Maintenance Costs: The replacement cycle for hydraulic oil and spare parts of the
hydraulic system is 2 years, with high procurement costs for spare parts, long cycles (for imported
parts), and difficult installation. After switching to an electrically-driven packaging machine, the gear
replacement cycle is 3 years and the rack gear replacement cycle is 5 years. The price comparison is
as follows Table 2:
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Table 2. Comparison of Maintenance Costs
Project Before Renovation After Renovation
Maintenance Material
Cost
Hydraulic System Spares: 340,000/2
years
Great Wall Hydraulic Oil:
90,000/2 years
Gears: 180,000/3 years
Rack Gears:
180,000/5 years
Total 10-Year
Maintenance Material
Cost
2150000 960000
4.2.3 Lower Labor Costs: Hydraulic packaging machines require specialized maintenance, usually
performed by personnel from the equipment manufacturer. The maintenance period requires 6 people
for 20 days, costing 80,000 yuan. After switching to an electrically-driven packaging machine,
company repair workers can complete the maintenance work without hiring additional professionals.
The maintenance period requires 3 people for 7 days, costing 0 yuan. (Table 3)
Table 3. Comparison of Labor Costs
Project Before Renovation After Renovation
Personnel External Hire: 6 People Internal: 3 People
Duration 20 Days 7 Days
Labor Cost 80,000/Time
None (Completed
Internally)
4.2.4 Reduced Energy Consumption: When the equipment is running, the average power of the
hydraulic system is approximately 75.2KW, while the average power of the electrically-driven system
is approximately 55KW, with a power difference of 20.2KW, resulting in a 26% savings in electricity
costs.
4.3. Significantly Reduced Equipment Maintenance Difficulty and Workload
4.3.1 During Shutdown and Overhaul: Maintaining a triplex hydraulic packaging machine
generally requires a maintenance cycle of around 20 days for 6 people, with at least 1-2 people
familiar with the hydraulic system. General mechanics cannot perform the repairs. Maintaining a
triplex electrically-driven packaging machine generally requires a maintenance cycle of around 7
days for 3 people, and it is more intuitive, allowing general repair personnel to perform the repairs.
4.3.2 During Normal Production: Faults in the hydraulic system are difficult to diagnose directly
and require personnel familiar with the hydraulic system to identify and address them, causing long
downtime and severely affecting production efficiency. There is also a risk of hydraulic oil leakage
contaminating finished tobacco leaves during maintenance, and leakage from worn cylinder seals will
directly contaminate the finished tobacco leaves. The electrically-driven system only has motor drives,
making it more intuitive and easier to troubleshoot, without the risk of contaminating finished tobacco
leaves during maintenance, resulting in faster troubleshooting and shorter downtime.
5. Summary
The overall equipment features energy conservation, consumption reduction, noise reduction, and
safe operation, with a mature, reliable, and user-friendly structure. The electric servo gear and rack
drive replaces the hydraulic system, thereby minimizing the potential risks of hydraulic oil leakage
and associated product quality issues. It requires minimal maintenance, utilizes fewer parts, and
incurs lower maintenance costs. The electric technology and mechanical structure fully replace
hydraulic technology, reducing the need for hydraulic piping, hydraulic pump stations, hydraulic oil,
and hydraulic cylinders, among others. The structure is simplified, and the electric control system and
programming are stable, reliable, and easy to maintain. This equipment aligns with the national
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tobacco industry's initiatives for energy conservation, consumption reduction, and homogenization,
and meets the high standards for tobacco leaf purity. It represents a significant innovation in pre-
compression and packaging technology and is worthy of promotion throughout the tobacco leaf
reprocessing industry.
References
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by Servo Motor Quantitative Pump [J]. Proceedings of the CSEE, 2006(08): 93-98.
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[D]. Jiangsu University of Science and Technology, 2012.
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