Design and Research of Leather Vacuum Drum for Chinese Leatherbookmark0 Zheng Chensheng (College of Mechanical and Electrical Engineering, Shaanxi University of Science and Technology, Xianyang 712081) The design of the mechanism and structure of air, temperature, and mechanical roll-down mechanism has developed a kind of high production efficiency and wide application range. , Low-contamination leather vacuum drum rumor At present, the main wet processing operations in leather production are completed in the ordinary atmospheric pressure drum, in addition to the drum can be used for all the wet operation of the tanning preparation stage and tanning stage In addition, it can also be used for dry operations such as the immersion of water-soaked skin, the softening of suede garment leather, the evening of leather after moisturizing, and the rolling of fur, so that the drum occupies the tanning production equipment. In an important position, however, the conventional drums have always had problems such as low production efficiency, large floor space, difficulty in loading and unloading, serious pollution, and low degree of automation. In order to solve the above problems, we proposed to introduce the vacuum mechanism into the leather wet processing process. In addition, the structure was boldly reformed. The drum body was composed of a swingable sandwich heat supply cylinder and a rotating inner drum. With two-way complex movements, after a lot of tests, a satisfactory leather tanning and drum roll softening effect was achieved. On this basis, a vacuum vessel of a new type of leather vacuum drum with a high degree of automation was developed. In a vacuum state, its internal gas is relatively thin, resulting in a corresponding physical and chemical change of the material in the container. Using a vacuum drum for wet leather operation is a typical vacuum impregnation process. At this time, the bare skin is equivalent to the material and wet. The chemical liquid in the process is equivalent to the following effects of the impregnating liquid in the drum under the vacuum mechanism: Pressure difference effect: The bare skin material is in a vacuum and low pressure environment in the drum, when the liquid is immersed in the immersion liquid, chrome enamel, etc. When the liquid enters the drum from a state of atmospheric pressure or above atmospheric pressure, the contact and adsorption processes of the impregnated material liquid and the leather can be strengthened by the action of the pressure difference.

The bulking effect of the pelt material: Under a sufficiently low pressure (vacuum of 2660-4000 Pa), the leather collagen fiber tissue will have a certain swelling due to the reduction of the external pressure, and the leather collagen fiber's bulkiness will facilitate the impregnation material. Diffusion of liquid into this penetrating impregnation process creates good conditions for the leather modification reaction.

Degassing of leather collagen fiber tissue: Under low pressure conditions, the gas contained in the pores dissolved in the tissue or in the tissue of the pelt will continue to diffuse into the low pressure environment due to its high partial pressure and be evacuated by the vacuum system. The liquid enters the cavity left by the escaped gas by the action of the pressure difference, thereby accelerating the penetration of the impregnating liquid into the leather and accelerating the reaction process: the tanning process in the leather wet processing is the penetration of the tanning agent molecule into the skin and the collagen molecule The functional group bonding process changes the reaction equilibrium and reaction kinetics due to the above-mentioned low-pressure effect and exhausting effect. When the appropriate temperature adjustment mechanism is used, the penetration of the chemical material into the skin and the skin in the tanning process are promoted. The combination of 3 leather vacuum drum working principle and structural characteristics of the traditional leather drum is a wooden or steel fixed shaft rotary cylinder equipment, mainly by the drum body, drum door, feeding device, rotary joints and transmission Composition In order to organically combine the vacuum mechanism, temperature and mechanical roll mechanism, the leather vacuum drum is designed with the following conditions in mind: (1) High vacuum Vacuum system with larger suction capacity; (2) Tumblewheel continuously variable transmission system and longitudinal swing system that can be changed according to different types of pelt and wet processing procedures; (3) It has the advantages of convenient inlet and outlet materials and vacuum sealing conditions. The outer cylinder; (4) has a heating system for automatic temperature control; (5) a device that automatically and uniformly feeds liquid without stopping the machine.

The vacuum drum designed according to the above conditions is shown as a sandwich drum and swinging device, a cartridge door and an automatic opening device, a rotary drum and a transmission device thereof, an evacuation system, a liquid suction and spray device, a heating system, and a control system. In some parts, the sandwich of the cylinder 3 is made of the inner liner, the outer bladder and the partition, and the heating source inlet 4 is connected to the heating tube through the control valve 5 to constitute a heating system. The control valve 5 and the temperature sensor provided on the barrel 3 are used to automatically control and adjust the temperature required by the material liquid in the barrel. The condensation water outlet 13 is used to discharge the condensation water. The swing mechanism 15 is driven by the power to make the barrel The body 3 can oscillate back and forth around the fulcrum 0 to realize the swing of the drum 3 and the drum 9. The drum swinging mechanism 15 can adopt an oil cylinder or a cylinder drive linkage mechanism to realize the intermittent oscillation of the drum, and a large speed ratio reducer can also be used. Combined with the linkage mechanism to achieve continuous oscillation of the cylinder.

The cylinder door opening and closing mechanism 2 installed on the cylinder body realizes the automatic opening and closing of the cartridge door through a cylinder or a cylinder to drive the liquid suction and spraying device through the conduit and the valve 11 to feed the liquid and the liquid in the material cylinder 12 to the cylinder. The suction liquid inlet 10 is connected, and the feed liquid control valve 11 is controlled in accordance with the process requirements. The feed drum 9 is formed by winding a steel plate filled with small holes, and one end is welded to a steel plate with a central rotary shaft, and the cylinder is provided with convex 14, the drum 9 is supported by the roller 16 and is driven by the transmission device 8 to rotate the transmission device 8 around its axis. The stepless transmission with a high speed ratio is directly connected with the drum spindle to drive the rotary drum 9 to rotate at different speeds. The requirements for mechanical action of various processes on leather materials The evacuation system 6 is connected to the body cavity of the cylinder through the air extraction port 4 in order to obtain the required degree of vacuum in the cartridge. If the vacuum system uses a 2 or 3 stage steam jet pump, then the exhaust gas from the last stage can be connected to the heating chamber through a heating pipe. This forms a heating system that uses exhaust gas. The energy saving device can also be designed as hot water. Circulation structure, the structure of the hot water pump will meet the process requirements of the temperature of hot water constantly pumped into the heating tube, heat exchange of water from the discharge pipe into the cooling tower to form a cycle control system can be manually controlled by the relay, can also be used PC automatic control In the wet processing temperature control is very important, with a temperature sensor on the drum, according to the temperature of different processes can automatically control the size of the heating source valve or heating medium temperature, to ensure that the liquid temperature within the barrel meets the process requirements for The cylinder body 3 swings freely, and the pipe connected to the cylinder body 3 needs to use a metal hose or a heat-resistant and corrosion-resistant hose. After emptying, the material is drained and the cartridge door is opened to load and unload the material. For the convenience of operation, the height of the cylinder is 1.5-1.8m. 3 Conclusion The research and development of the leather vacuum drum is a traditional constant pressure revolution of the leather industry. Drum breakthrough, it is the first time to organically combine the vacuum mechanism, temperature mechanism, mechanical action and applied to the wet processing of leather.

The PF aldehyde agglutinant from ZschimmerSchwarz was used to facilitate the homogeneous distribution of the chrome tanning agent. It has a mild effect on the grain surface, improves the fullness and softness of the skin, has a bright color, and has a strong ability to predetermine the skin, which is very beneficial to chromium. The permeation distribution of the tanning agent and the chromium tanning agent with low alkalinity in combination with chrome powder have good solubility and permeability, uniform distribution in the skin, uniform color of the blue leather, and soft hand feeling. The alkali agent is selected from Tio's Ciomno FB. Its mild alkali and temperature-raising function can further improve the even distribution of chromium and evenness of surface color, as well as the fixation of chromium, so that the skin can achieve a more ideal tanning effect. 25 Retanning and fatliquoring With the improvement of people's living standards, people are increasingly pursuing the softness and fullness of leather. Comfortable crocodile leather is a kind of special, high-grade leather. Dry finishing generally requires polishing and light treatment. Therefore, combining these two aspects, the emphasis is placed on selecting performance. With a mild, highly permeable material, there is a purposeful strengthening of tanning. In terms of process operations, the focus is on neutralization. In the neutralization materials, PAK neutralizing tannins with good permeability and buffering properties are used. Combined with sodium formate, the drums are stopped overnight, so that the entire skin is uniform and uniform. Open the fiber channel to create a good condition for the future retanning, dyeing and fatliquoring. Finally, the leather will be colored uniformly and deeply. The soft and rich Relugan RV will be the main ingredient, and a certain amount of Wattle Bark Glue will be used to make the leather full. The soft and firm purpose; fatliquor selected Trumpler's TrumponDB and TrumponBRDTrumponLGGS used together, so that the fullness and softness of leather can meet the requirements of soft upper leather; dye selection BASF's Luganil and Lurazol, make the dye not only through Full and fast, pregnancy 2.6 Alligator crocodile skin is polished due to grain protrusion and bones as support. The polishing process is used in the finishing process. The material is mainly selected from Clariant's WAX187P53 and BASF's. LuronELuronU and Stahl's RA1079RU3901 are used in combination, polished and then re-sprayed for 1 pass. The bright layer is selected by Clariant's GC2030. Once polished, so there is a strong two-color three-dimensional effect crocodile leather appeared in front of us.

3 Conclusions Starting with the structural characteristics of crocodile skin, combined with tanning practice, a set of processes for manufacturing high-grade crocodile leather was developed to solve the problem of excessive leather wear through the control of mechanical action; through the strict selection of chemical materials, The effective control of the liming and bleaching process solves the problem of bleaching scales; through the proper mix of tanning and retanning materials and scientific process design, the leather is full and soft and compact; the final polishing process makes the whole The process is more reasonable and the effect is more ideal

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