It is very important to exercise extreme care when unpacking the rubber belt and removing it from its packing case. All screws must be completely removed from the packing case lid. The packing case lid must be lifted clear (not dragged across the rubber belt). The special protective poly film should be carefully removed by stripping off the adhesive tape holding it in place. Never cut away the film or use any sharp instrument around the rubber belt.
A suitable diameter, clean metal pipe section, free from burrs or sharp edges, at least 6 inches (150mm) longer than the rubber belt overall width should be carefully inserted inside the rubber belt and used to lift the rubber belt clear from the packing case. A chain may be fed through the pipe section, or lifting straps may be used on the ends of the lifting pipe section to lift the belt. The packing case should be quickly removed from the work area, so that the rubber belt may be lowered onto a clean prepared area of floor covered with carton and/or heavy cloth. Ample amounts of talc should be applied to the belt interior to aid with machine roll insertion.
Before installing the rubber belt on the shrinking machine it is very important to thoroughly clean, inspect and lubricate the rubber belt unit. Check all bearings for smooth free operation.
While installing the rubber belt special care must be given to several points.
Make sure to cover all sharp or rough machine surfaces with cloth taped in place to prevent damage to the belt during installation.
When inserting rolls or lifting devices into the rubber belt, take very special care to avoid bruising or scuffing the belt interior.
Make absolutely certain that the pressure roll is perfectly parallel to the heated cylinder. Carefully clean the inside and outside cooling/lubricating water spray pipes, making sure that all orifices are open and that the sprays are aimed properly. The inside spray should not be aimed directly at the belt surface, but should be adjusted so that the water contacts the belt at a glancing angle. The outside spray should not be aimed at the belt surface, but should be pointed into the dam of cooling water formed by the intersection of the felt doctor with the belt surface. The felt doctor should be in good condition and should make contact with the rubber belt face across the entire belt width. There must be at least 1 inch (25mm) of clearance between the limit rollers and the rubber belt edge. The limit rollers should be angled slightly upward from a right angle intersection with the belt edges. The rubber belt thickness gauge should be precisely re-set to the new belt thickness. Water removal rolls should be checked for parallel closure and diaphragm air pressure should be set at about 35 psi. (2.3 kg./cm sq.) Rubber belt tension should be adjusted with tension set at the same level on both sides of the rubber belt (belt tracking is adjusted as a last step, with the steam cylinder heated to operating temperature and at least 1/4 inch (6mm) of compression applied to the rubber belt).
Installation and Use - Tension
Correct belt operating tension for a 2 5/8 inch (67mm) thick belt is 1/4 inch (6.4 mm) of stretch for each 12 inches (305 mm) of belt length. It is perfectly normal for rubber belts to require increased operating tension as the belts become thinned out from successive belt surface grinding. New rubber belts which are 2 inches (51 mm) thick, or older belts which have been reduced to 2 inches (51 mm) or less by grinding, require at least 1/2 inch (12.7 mm) of belt stretch for each 12 inches (305 mm) of rubber belt length. For more specific details about this adjustment, see the book "pre-shrinking of textile fabrics".
Improper rubber belt tension will very often result in difficulty to obtain sufficient fabric warp pre-shrinkage and may cause generalized fabric corrugations. Insufficient belt tension will often result in belt interior scuffing and eventual cracking.
Figure 18
Compressor Unit Profile (Mirror)
Figure 19
Water Spray at Tension Roll
Installation and Use - Lubricating Water Spray
The rubber belt internal lubricating water spray is perhaps the leading cause of premature rubber belt failure. As this spray is not readily visible by operators, if water pressure should drop or fail altogether during operation, even for only a relatively short period of time, the entire internal rubber belt surface may become roughened and quickly develop cracks.
This internal lubricating spray is installed in the wrong location on most machines. The only point on the rubber belt machine requiring internal belt lubrication is at the nip roll. This is because the rubber belt under nip pressure will elongate and expand width- wise. In doing so, the belt internal surface must slip against the pressure roll surface. Unfortunately most shrinking machines have the lubricating spray installed inside the rubber belt just below the tension roll. In such cases, all of the internal lubricating water is removed by the action of the water removal rolls before the belt reaches the nip pressure roll. The correct location for the internal rubber belt lubricating spray is just after the water removal rolls and just before the nip pressure roll. The lubricating water, in addition to allowing the rubber belt to slip against the pressure roll surface to avoid abrasion of the belt inner surface, also allows the rubber belt to elongate and subsequently recoil more freely, creating a greater warp compacting potential, thus allowing the rubber belt to be used for longer useful life while easily obtaining the required cloth warp pre-shrinkage.
Figure 14c • Effects of Grinding
Figure 20 • Setting Tension
Installation and Use - Air Nozzles
Because wider fabrics are being woven today and many mills still have narrower shrinking machines, in addition to using the straight edge rubber belt as a means of being able to pre-shrink wider fabrics, there is one additional machine modification which may be useful when wider fabrics must be processed on a slightly narrower shrinking machine than would normally be recommended. Air nozzles may be formed by flattening a piece of 1/4 inch (6mm) diameter copper tubing. Plant compressed air may be delivered through the nozzles formed by the flattened ends of the copper tubes and used to blow the excess water off the rubber belt edges just before the fabric comes into contact with the rubber belt, just below the nip pressure roll. This will be useful when excessive fabric width results in wavy selvages due to excess water carried on the rubber belt surface near to the belt edges.
It is very important to exercise extreme care when unpacking the rubber belt and removing it from its packing case. All screws must be completely removed from the packing case lid. The packing case lid must be lifted clear (not dragged across the rubber belt). The special protective poly film should be carefully removed by stripping off the adhesive tape holding it in place. Never cut away the film or use any sharp instrument around the rubber belt.
A suitable diameter, clean metal pipe section, free from burrs or sharp edges, at least 6 inches (150mm) longer than the rubber belt overall width should be carefully inserted inside the rubber belt and used to lift the rubber belt clear from the packing case. A chain may be fed through the pipe section, or lifting straps may be used on the ends of the lifting pipe section to lift the belt. The packing case should be quickly removed from the work area, so that the rubber belt may be lowered onto a clean prepared area of floor covered with carton and/or heavy cloth. Ample amounts of talc should be applied to the belt interior to aid with machine roll insertion.
Before installing the rubber belt on the shrinking machine it is very important to thoroughly clean, inspect and lubricate the rubber belt unit. Check all bearings for smooth free operation.
While installing the rubber belt special care must be given to several points.
Make sure to cover all sharp or rough machine surfaces with cloth taped in place to prevent damage to the belt during installation.
When inserting rolls or lifting devices into the rubber belt, take very special care to avoid bruising or scuffing the belt interior.
Make absolutely certain that the pressure roll is perfectly parallel to the heated cylinder. Carefully clean the inside and outside cooling/lubricating water spray pipes, making sure that all orifices are open and that the sprays are aimed properly. The inside spray should not be aimed directly at the belt surface, but should be adjusted so that the water contacts the belt at a glancing angle. The outside spray should not be aimed at the belt surface, but should be pointed into the dam of cooling water formed by the intersection of the felt doctor with the belt surface. The felt doctor should be in good condition and should make contact with the rubber belt face across the entire belt width. There must be at least 1 inch (25mm) of clearance between the limit rollers and the rubber belt edge. The limit rollers should be angled slightly upward from a right angle intersection with the belt edges. The rubber belt thickness gauge should be precisely re-set to the new belt thickness. Water removal rolls should be checked for parallel closure and diaphragm air pressure should be set at about 35 psi. (2.3 kg./cm sq.) Rubber belt tension should be adjusted with tension set at the same level on both sides of the rubber belt (belt tracking is adjusted as a last step, with the steam cylinder heated to operating temperature and at least 1/4 inch (6mm) of compression applied to the rubber belt).
Correct belt operating tension for a 2 5/8 inch (67mm) thick belt is 1/4 inch (6.4 mm) of stretch for each 12 inches (305 mm) of belt length. It is perfectly normal for rubber belts to require increased operating tension as the belts become thinned out from successive belt surface grinding. New rubber belts which are 2 inches (51 mm) thick, or older belts which have been reduced to 2 inches (51 mm) or less by grinding, require at least 1/2 inch (12.7 mm) of belt stretch for each 12 inches (305 mm) of rubber belt length. For more specific details about this adjustment, see the book "pre-shrinking of textile fabrics".
Improper rubber belt tension will very often result in difficulty to obtain sufficient fabric warp pre-shrinkage and may cause generalized fabric corrugations. Insufficient belt tension will often result in belt interior scuffing and eventual cracking.
The rubber belt internal lubricating water spray is perhaps the leading cause of premature rubber belt failure. As this spray is not readily visible by operators, if water pressure should drop or fail altogether during operation, even for only a relatively short period of time, the entire internal rubber belt surface may become roughened and quickly develop cracks.
This internal lubricating spray is installed in the wrong location on most machines. The only point on the rubber belt machine requiring internal belt lubrication is at the nip roll. This is because the rubber belt under nip pressure will elongate and expand width- wise. In doing so, the belt internal surface must slip against the pressure roll surface. Unfortunately most shrinking machines have the lubricating spray installed inside the rubber belt just below the tension roll. In such cases, all of the internal lubricating water is removed by the action of the water removal rolls before the belt reaches the nip pressure roll. The correct location for the internal rubber belt lubricating spray is just after the water removal rolls and just before the nip pressure roll. The lubricating water, in addition to allowing the rubber belt to slip against the pressure roll surface to avoid abrasion of the belt inner surface, also allows the rubber belt to elongate and subsequently recoil more freely, creating a greater warp compacting potential, thus allowing the rubber belt to be used for longer useful life while easily obtaining the required cloth warp pre-shrinkage.
Because wider fabrics are being woven today and many mills still have narrower shrinking machines, in addition to using the straight edge rubber belt as a means of being able to pre-shrink wider fabrics, there is one additional machine modification which may be useful when wider fabrics must be processed on a slightly narrower shrinking machine than would normally be recommended. Air nozzles may be formed by flattening a piece of 1/4 inch (6mm) diameter copper tubing. Plant compressed air may be delivered through the nozzles formed by the flattened ends of the copper tubes and used to blow the excess water off the rubber belt edges just before the fabric comes into contact with the rubber belt, just below the nip pressure roll. This will be useful when excessive fabric width results in wavy selvages due to excess water carried on the rubber belt surface near to the belt edges.
