Title of Invention

AN IMPROVED TANNING DEVICE

Abstract

The present invention relates to an improved tanning device for leather making. The device of the present invention has potential application in both pre-tanning and post tanning wet operations in leather processing industry. The outer shell of the device undergoes rocking action which makes it convenient to unload the processed stock by gravity automatically. The novelty of the invention lies in selecting fabrication friendly material for inner vessel and also in providing an oscillating outer shell and transferring its rocking action to the inner vessel that is subjected to an additional movement with the help of gear and pinion and by the weight acting on the shelves contained in it through the rollers on which it is positioned, the rollers being fixed on the outer shell thereby avoiding the presence of any moving part linked with inner vessel ensuring absence of either wear and tear or loss of the pressure generated in the device.

Full Text

The present invention relates to an improved tanning device for leather making. The device of the present invention has potential application in both pertaining and post tanning wet operations in leather processing industry. The wet processing of hides and skins is conventionally done in pit, vat, paddle and wooden drum. While using pit and vat, the hides/skins to be processed are put in the process liquor and occasionally handled manually. It prompted the tanners to use paddle, where it has been possible to impart the agitation in the liquor, contained in the vessel, by rotating of the blades of the paddle using motor, thereby providing mechanical agitation to the stock to be processed. Much better effect of the desired mechanical action under dynamic condition on the hide/skin to be processed is however provided in a tanning drum. During rotation of the drum, the skins/hides are lifted up by the shelves or pegs and then fall down to the processing liquor of the drum resulting considerable mechanical action. The main limitations associated with drumming are as follows. 1. It involves the possibility of damage of the hides/skins under processing, by scrapping, scuffing, knotting, shape distortion, wrinkling, grain pebbling, loosening of fiber structure or loss in area. 2. it is associated with difficulty in thorough cleaning of the stock, which lets out lot of water adding to the effluent disposal problem. 3. It involves the inconvenience in opening the drum for unloading or intermediate checking. 4. Since the float of the drum cannot go beyond the axle level, the effective capacity utilization is very low to the tune of only 45% of the volume of the drum. 5. The starting torque required for running a drum is about 2.5 to 3 times of the running torque due to the maximum load lifted by the baffle or pegs and due to the own weight of the drum, thereby necessitating for higher capacity motor, which may be around 10 kW for a drum of size 2m length and 2.5m diameter for running the drum. 6. The turbulence within the tanning bath which results from this rotation causes a fall in the surface resistance which oppose the diffusion of the chemical products but at the same time, creates a greater friction between the skins/hides. This friction has a negative ifecjLpn the resistance and •«•«£" ' ~ the solidity of the grain patterns. The above limitations have prompted the researchers to explore better options of processing device. Tombetti et al (Abstract published in Journal of American Leather Chemists Association, 75. 62, 1980) developed a pressure vessel for leather tanning having a rotating inner drum (2) divided into three perforated compartments, each having a door (6), housed in a stationary exterior casing (1) provided with a door (7) and an inlet for chemical and water housed on a frame assembly (3), the said inner drum (2) being rotated with the help of main shaft (4), held by two bearings and housing (5) and connected to a power transmission assembly source (8), the pressure inside the inner drum (2) being generated with the help of a pneumatic system (9). The main advantage of this device over the conventional tanning drum is that the capacity utilization is enhanced to 60%. Moreover, the starting torque required for running the device is around 2 times of the running torque. Thus while 5 kW motor is required for running a typical vessel of such kind having dimension 1.5m length and 2.5m diameter, 2 kW motor is required for running the pneumatic system for maintaining the internal pressure as well as the opening and closing the door of the stationary outer shell. However, the main limitations associated with the hitherto known devices are the following i) Since the inner vessel is connected to a rotating main shaft, the system is likely to have leakage of air, resulting ultimately in quick loss of pressure inside the vessel. ii) Association of moving parts with the inner vessel has also greater implication of wear and tear. iii) The stationary outer shell does not give any option for automatic unloading of the leathers, which have to be taken out manually, thereby implying more labor as well as time. iv) Employing of stainless steel body for the inner vessel involves certain fabrication limitation like difficulty in bending, riveting of stainless steel sheet. The main objective of the present invention is to provide an improved tanning device, which obviates the drawbacks stated above. Another objective of the present invention is to provide a device to employ pressure technique for the hides/skins to be processed. Yet another objective of the present invention is to provide a device for using at a rotational speed not exceeding 3 rpm to minimize the limitational effects arising out of the rotational movements encountered in the hitherto known tanning drums. Still another objective of the present invention is to provide a device having an option of multi mechanical action to ensure minimizing energy input and low rotational speed of the device, resulting ultimately in the reduction of the processing time. Yet another objective of the present invention is to provide a device devoid of any leakage so as to maintain the internal pressure while processing leathers. Still another objective of the present invention is to provide an option for automatic unloading of the processed stock. Yet another objective of the present invention is to increase the capacity utilization of the device to more than 65%. Still another objective of the present invention is to ensure that the power consumption and the processing time for running the device is reduced as compared to that in the existing art. Yet another objective of the present invention is to provide a device ensuring uniform absorption of chemicals into leather with the help of pressure and mechanical action. In the drawings accompanying this specification, Fig 1 represents the assembly of the existing pressure drum. Fig. 2 represents the assembly of the improved tanning device Fig. 3 represents the pictorial view of the inner vessel of the improved tanning device. Fig 4. represents the pictorial view of the shell of the improved tanning device. Different parts of Fig. 1 are as follows. 1 refers to the stationary exterior casing 2 refers to the perforated inner rotating drum 3 refers to the frame assembly 4 refers to the center shaft 5 refers to the bearings and housings 6 refers to the perforated three compartments with one door for each Compartment. 7 refers to the door to the exterior casing. 8 refers to the power transmission source. 9 refers to the inlet for chemical and water and with pneumatic system. Different parts of Fig. 2 are as follows 10. refers to the oscillating exterior shell. 11. refers to the frame assembly. 12. refers to the power transmission assembly. 13. refers to the mechanism for rocking action of the device 14 refers to the source for the power transmission. Different parts of Fig. 3 are as follows. 15 refers to the perforated inner vessel 16 refers to doors of the inner vessel 17 refers to the shelves/ compartments inside the inner vessel 18 refers to the non corrosive rollers fixed on the inner side of the outer vessel 19 refers to the non-corrosive, chemical resistant pinion & gear fixed on the outer side of the inner vessel Different parts of Fig 4 are as follows. 20. refers to the dome shaped caps 21. refers to the leak proof packing 22. refers to the outer vessel 23. refers to the inlet for chemical and water 24. refers to the conventional regulated temperature device 25. refers to the pressure nozzle connected with pressure regulator and compressor 26. refers to the outlet for discharging liquid. Accordingly the present invention provides an improved tanning device for leather making comprising characterized in that a perforated inner vessel (15) made from fabrication friendly material and having shelves more than one (17) and a door (16), the said inner vessel (15) being housed on non-corrosive chemical resistant rollers (18) fixed on the inner wall of the outer vessel(22) made up of a non-corrosive material capable of withstanding pressure of minimum 5 Kg/cm2, and the said outer vessel (22) being provided with a leak-proof packing (21) and dome shaped caps (20) on either side out of which at least one is being open able, the said outer shell is also being provided with inlet for chemicals and water(23), conventional regulated temperature device (24), discharge for liquid (26), a pressure nozzle(25) connected to a compressor and regulator externally for developing air pressure inside the vessel, the entire oscillating exterior shell (10), along with all accessories defined herein before is placed on center shaft being attached to the frame assembly (11) the conventional rocking mechanism (13) is also provided on the outer shell and connected to the normal power transmission assembly (12) which in turn connected to the source for the power transmission (14) thereby ensuring rocking action as well as rotational movement of the inner perforated vessel (15) with the help of non corrosive chemical resistance pinion and gear (19) fixed on the outside of the inner vessel. In an embodiment of the present invention, the material used for the inner vessel may be such as poly vinyl chloride (PVC), chemical resistant fiber glass reinforced polymer, Non corrosive Stainless Steel. In another embodiment of the present invention, the material used for outer shell may be such as non-corrosive stainless steel, chemical resistant fiber glass reinforced polymer. In yet another embodiment of the present invention, the leak proof packing material used may be such as rubber, polyurethane, polyvinyl chloride and flat asbestos sheet. In still another embodiment of the present invention, the power transmission assembly source used may be such as gear drive, chain drive. In yet another embodiment of the present invention, the rocking mechanism used may be such as cam mechanism, hydraulic system, and pneumatic system. In still another embodiment of the present invention, the non-corrosive, chemical resistant material used for rollers and gears may be such as rubber, Teflon, polyvinyl chloride, polyurethane. In yet another embodiment of the present invention, the non-corrosive, chemical resistant material used for outer vessel and domed shaped caps may be such as Stainless steel, fiber reinforced plastic. The vessel of the present invention is described below in detail. The device is essentially a frame assembly (11) housing two vessels (15 & 22), one inside the other, along with the power transmission assembly (12). Hides/skins to be processed are taken in the perforated inner vessel (15) through the vessel door (16). This inner vessel is placed on non-corrosive roller (18) fitted inside of the outer vessel (22), which is incorporated, with an inlet (23) through which water and chemicals are poured inside. A leak-proof packing (21) provided on the outer vessel ensures that no leakage takes place while carrying out the wet processing. A regulated temperature device (24) is provided on the shell to ensure proper monitoring of the temperature during processing. There are two dome shaped caps (20), out of which at least one is openable, for getting access to the inner vessel door (16), while putting the skins/hides to be processed inside the vessel. The outer vessel (22) is also provided with an outlet (26) through which the float is drained out whenever necessary. The pressure inside the vessel is maintained at minimum of 2kg/cm2 with the help of a pressure nozzle (25), provided on the vessel, connected to a compressor. While processing, the chemicals can be added through the inlet, which has necessarily to be closed after the addition every time in order to maintain the internal pressure that can be adjusted with the help of compressor and pressure gauge. While the whole system is held by a frame assembly (11), the power supply comes from the power transmission assembly (12) linked to the source for the power transmission (14). After taking the leathers to be processed inside the inner vessel, both the inner vessel door and one of the outer vessel dome shaped cap are closed and the system is started. While the outer shell is subjected to the rocking action through the rocking mechanism (13), to which it is connected, using the power transmission assembly source (14), the inner perforated vessel (15), which is provided with shelves (17), experiences rocking action as well as rotational movement with the help of the pinion & gear (19), fixed at the outer side of the inner vessel, thereby ensuring that the leathers under processing are subjected to mechanical action. The generated pressure inside the vessel and the multiple mechanical actions of the vessel ensures that the processing is accelerated with uniform result. After processing, the leathers are taken out by opening the outer shell door followed by the inner vessel door. The novelty and non-obviousness of the present invention lies not only in selecting fabrication friendly material especially for the inner vessel, but also in providing an oscillating outer shell and transferring its rocking action to the inner vessel, that is subjected to an additional rotational movement with the help of the gear and pinion and by the weight acting on the shelves contained in it, through the rollers on which it is positioned, the rollers being fixed on the outer shell, thereby avoiding the presence of any moving part linked with the inner vessel, ensuring absence of either wear and tear or loesr of the pressure generated in the device, resulting ultimately in the economy of energy consumption, capacity utilization, time and human labor, with uniform absorption of chemicals while processing leathers. The following examples are given by way of illustration only and therefore should not be construed to limit the scope of the present invention. Example 1 Five cut-piece of a limed buffalo pelt, duly fleshed and washed thoroughly, weighing 1 Kg were taken in the fiber reinforced plastic inner vessel of the device and the doors of the inner vessel as well as the outer shell were then closed one by one. The leak-proof material used for the outer shell was rubber. Water, measuring 2 Its, was added to the vessel through the inlet. The motor was then switched on to impart hydraulic rocking action to the device by gear drive, when the outer shell started oscillating at 40 oscillations per minute ( opm), while the inner vessel containing the pelt cut-pieces started rotating at 3 revolutions per minute (rpm) with the help of the teflon rollers and gear mounted inside the outer shell. 10 gms of ammonium sulphate was then dissolved in 100 gms of water and the resulting solution was added to the device through the inlet. Then compressed air was passed at a pressure of 3v5 kg/cm2 through the pressure nozzle into the device. After a period of 60 seconds the compressor valve was closed while the pressure gauge displayed the maintenance of pressure in the device at 3.5 kg/cm2. After a period of 45 minutes, the internal pressure of the vessel was brought down to zero by opening the pressure gauge valve and the vessel was switched off. Both the doors of the device were then opened and the completion of deliming was confirmed using phenolphthalein indicator. The inner vessel was then closed and the device was positioned in such a way that the outer shell door faced downward, thereby draining the float by gravity. Then the outer shell door was closed. The subsequent operation of washing, pickling, chrome tanning were carried out in a similar way by employing a pressure of 3.5 kg/cm2 inside the vessel. The completion of pickling operation was confirmed by opening the outlet and checking the pH of the float, which was found to be 2.8. Exhaustion of chrome was checked in a similar way by opening the outlet and taking out a sample of the float after chrome tanning operation. Finally the tanned cut-pieces were taken out by opening the inner vessel door as well as the outer shell door and were piled. Example 2 Ten cow wet blue cut-pieces duly shaved, weighing 1 Kg were taken in the ploy vinyl chloride (PVC Pipe) inner vessel of the device and the doors of the inner vessel as well as the outer shell were then closed one by one. The leak-proof material used for the outer shell was polyvinyl chloride. 2 It. of water was added to the device through the inlet. The motor was then switched on to impart rocking action, generated by cam mechanism, to the device by chain drive, when the outer shell started oscillating at 40 oscillations per minute (opm), while the inner vessel containing the wet blue cut-pieces started rotating at 3 revolutions per minute (rpm) with the help of the polyurethane rollers and gear mounted inside the outer shell. 10 gms of sodium bicarbonate dissolved in 100 gms of water and the resulting solution was added to the device through the inlet. Then compressed air was passed at a pressure of 2.5 kg/cm2 through the pressure nozzle into the device. After a period of 30 seconds the compressor valve was closed while the pressure gauge displayed the maintenance of pressure in the device at 2.5 kg/cm2. After a period of 40 minutes, the internal pressure of the vessel was brought down to zero by opening the pressure gauge valve and the vessel was switched off. The completion of neutralization operation was confirmed by opening the outlet and checking the pH of the float, which was found to be 4.5. The device was again switched on. 15 gms of brown dye was dissolved in hot water and the resulting dye solution was added to the device through the inlet. The pressure inside the device was maintained at 2.5 kg/cm2. 80 gms of synthetic fatliquor was emulsified well in hot water and after a period of 35 minutes the resulting fatliquor emulsion was added to the oscillating device through the inlet, while allowing the device to oscillate for another 35 minutes and then 5 gms of formic acid, dissolved in 50 gms of water was added to the oscillating device through the inlet. After each addition, the inlet was closed and the pressure inside the vessel was maintained at 2.5 kg/cm2 by passing air. After a period of 30 minutes, the internal pressure of the vessel was brought down to zero by opening the pressure gauge valve and the vessel was switched off. Finally the leather cut-pieces were taken out by opening the inner vessel door as well as the outer shell door and were piled. Example 3 Eight goat wet blue cut-pieces duly shaved, weighing 0.8 Kg were taken in the fiber reinforced plastic inner vessel of the device and the doors of the inner vessel as well as the outer shell were then closed one by one. The leak-proof material used for the outer shell was polyurethane. 1.5 Its of water was added to the device through the inlet. The handle of the main gear was then rotated manually to impart rocking action to the device, when the outer shell started oscillating at 40 oscillations per minute (opm), while the inner vessel containing the wet blue cut-pieces started rotating at 3 revolutions per minute (rpm) with the help of the polyvinyl chloride rollers mounted inside the outer shell. 8 gms of sodium formate dissolved in 80 ml of water and the resulting solution was added to the device through the inlet. Then compressed air was passed at a pressure of 2 kg/cm2 through the pressure nozzle into the device. After a period of 30 seconds the compressor valve was closed while the pressure gauge displayed the maintenance of pressure in the device at 2 kg/cm2. After a period of 30 minutes, it was ensured with the help of the pressure gauge that the pressure inside the vessel had come to zero and the device was stopped. The completion of neutralization operation was confirmed by opening the outlet and checking the pH of the float, which was found to be 4.5. The device was again started by manually rotating the handle. 8 gms of brown dye was dissolved in hot water and the resulting dye solution was added to the device through the inlet. The pressure inside the device was maintained at 2 kg/cm2 after closing the inlet. 80 gms of synthetic fatliquor was emulsified well in hot water and after a period of 30 minutes the resulting fatliquor emulsion was added to the oscillating device through the inlet, while allowing the device to oscillate for another 30 minutes and then 5 gms of formic acid, dissolved in 50 gms of water was added to the oscillating device through the inlet. After each addition, the inlet was closed and the pressure inside the vessel was maintained at 2 kg/cm2 by passing air. After a period of 30 minutes, the internal pressure of the vessel was brought down to zero by opening the pressure gauge valve and the vessel was switched off. Finally the leather cut-pieces were taken out by opening the inner vessel door as well as the outer shell door and were piled. Example 4 Ten cow wet blue cut-pieces duly shaved, weighing 1 Kg were taken in the stainless steel inner vessel of the device and the doors of the inner vessel as well as the outer shell were then closed one by one. The leak-proof material used for the outer shell was asbestos. Water, measuring 2 Its, was added to the device through the inlet. The pneumatic system was then opened to impart rocking action to the device, when the outer shell started oscillating at 30 oscillations per minute (opm), while the inner vessel containing the wet blue cut-pieces started rotating at 2.5 revolutions per minute (rpm) with the help of the rubber rollers mounted inside the outer shell. 10 gms of sodium formate dissolved in 100 gms of water and the resulting solution was added to the device through the inlet. Then compressed air was passed at a pressure of 2.5 kg/cm2 through the pressure nozzle into the device. After a period of 40 seconds the compressor valve was closed while the pressure gauge displayed the maintenance of pressure in the device at 2.5 kg/cm2. After a period of 40 minutes, the internal pressure of the vessel was brought down to zero by opening the pressure gauge valve and the vessel was stopped. The completion of neutralization operation was confirmed by opening the outlet and checking the pH of the float, which was found to be 4.5. The device was again started. 15 gms of brown dye was dissolved in hot water and the resulting dye solution was added to the device through the inlet. The pressure inside the device was maintained at 2.5 kg/cm2. 80 gms of synthetic fatliquor was emulsified well in hot water and after a period of 35 minutes the resulting fatliquor emulsion was added to the oscillating device through the inlet, which was immediately closed to maintain the internal pressure at 2.5 kg/cm2, while allowing the device to oscillate for another 35 minutes and then 5 gms of formic acid, dissolved in 50 gms of water was added to the oscillating device through the inlet. After each addition, the inlet was closed and the pressure inside the vessel was maintained at 2.5 kg/cm2 by passing air. After a period of 30 minutes, the internal pressure of the vessel was brought down to zero by opening the pressure gauge valve and the vessel was stopped. Finally the leather cut-pieces were taken out by opening the inner vessel door as well as the outer shell door and were piled. The main advantages of the present invention are the following. 1. The outer shell of the device undergoes rocking action, which enables an operator to adjust it in a convenient position so as to unload the processed stock by gravity automatically, thereby not only doing away with the extra labor associated with unloading, but also in reducing unloading time. 2. Since the inner vessel is rotated by the rollers fixed to the inside of the outer shell of the device, no leakage of internal pressure is envisaged and at the same time long life is ensured for the device. 3. The use of materials like fiber reinforced plastic (FRP) ensures ease in fabrication for the inner vessel, which is provided as a molded single unit structure. 4. Unlike the existing systems, the starting torque of the device is only about 1.5 times of the running torque as against much higher values for the existing devices, thereby reducing the power requirement considerably. 5. Capacity utilization of the device is around 70% as against 45% in the - existing wooden device. 6. Even without opening the vessel door, the critical parameters like pH, temperature of the float can be measured only by opening the outlet. 7. Since the leathers under processing are subjected to mechanical action under pressure, better absorption of chemicals is ensured, resulting in higher exhaustion of bath and less effluent load. We Claim: 1. An improved tanning device for leather making comprising characterized in that a perforated inner vessel (15) made from fabrication friendly material and having shelves more than one (17) and a door (16), the said inner vessel (15) being housed on non-corrosive chemical resistant rollers (18) fixed on the inner wall of the outer vessel(22) made up of a non-corrosive material capable of withstanding pressure of minimum 5 Kg/cm2, and the said outer vessel (22) being provided with a leak-proof packing (21) and dome shaped caps (20) on either side out of which at least one is being open able, the said outer shell is also being provided with inlet for chemicals and water(23), conventional regulated temperature device (24), discharge for liquid (26), a pressure nozzle(25) connected to a compressor and regulator externally for developing air pressure inside the vessel, the entire oscillating exterior shell (10), along with all accessories defined herein before is placed on center shaft being attached to the frame assembly (11) the conventional rocking mechanism (13) is also provided on the outer shell and connected to the normal power transmission assembly (12) which in turn connected to the source for the power transmission (14) thereby ensuring rocking action as well as rotational movement of the inner perforated vessel (15) with the help of non corrosive chemical resistance pinion and gear (19) fixed on the outside of the inner vessel. 2. An improved device, as claimed in claim 1, wherein the fabrication friendly material for inner vessel used is of poly vinyl chloride (PVC), chemical resistant fiberglass reinforced polymer (FRP) and Stainless Steel. 3. An improved device, as claimed in claims 1 and 2, wherein the material used for outer shell is selected from non corrosive stainless steel, chemical resistant fiber glass reinforced polymer. 4. An improved device, as claimed in claims 1 to 3, wherein the leak proof packing material used is selected from rubber, polyurethane, polyvinyl chloride and flat asbestos sheet. 5. An improved device, as claimed in claims 1 to 4, wherein the power transmission assembly source used is gear drive, chain drive. 6. An improved device, as claimed in claims 1 to 5, wherein the rocking mechanism used is cam mechanism, hydraulic system, and pneumatic system. 7. An improved device, as claimed in claims 1 to 6, wherein the non-corrosive, chemical resistant material used for rollers and gears are selected from rubber, Teflon, polyvinyl chloride, polyurethane. 8. An improved tanning device for leather making, substantially as herein described with reference to the examples and drawings accompanying the specification.

Documents:

791-del-2000-abstract.pdf

791-del-2000-claims.pdf

791-del-2000-correspondence-others.pdf

791-del-2000-correspondence-po.pdf

791-del-2000-description (complete).pdf

791-del-2000-drawings.pdf

791-del-2000-form-1.pdf

791-del-2000-form-19.pdf

791-del-2000-form-2.pdf

791-del-2000-form-3.pdf