Patent Application
20150300959
1. Field of Invention
This invention relates to a method of making a pulley lagging laminate which provides an indication of lagging wear.
2. Discussion of Prior Art
Drive pulleys such as used with coal mine conveyor belts frequently have a lagging on their surface to reduce conveyor belt slippage. This lagging is usually a black rubber.
After time in service, the rubber lagging compound on these pulleys becomes worn and must be replaced. If conveyor belt operation continues after the lagging is completely worn out, the metal pulley surface will be damaged and the pulley will have to be repaired or even may have to be scrapped. Mine operators visually inspect the lagging in an attempt to determine the approximate depth of lagging wear. To be done thoroughly and safely, the conveyor belt must be shut for this visual inspection.
One disadvantage of all present lagging compounds is that there is no way to determine when the wear of the lagging is down to the specific point where the lagging must be replaced. If the lagging wears out and is not replaced, the pulley drum will be damaged and repairs will be costly.
Accordingly, several objects and advantages of our method which has all of the advantages of the prior art and none of the disadvantages are:
Further objects and advantages of our method will become apparent from a consideration of the drawings and ensuing description.
The present invention relates to a method of making a lagging laminate containing at least one inner layer of material with different light reflectance than the outer layer or layers. The inner layer(s) may be a different color than the outer layer, different material, reflective, fluorescent, phosphorescent, or a combination of these different reflective components. This inner layer of material with different light reflectance will provide a visual, safe, and non-shutdown method of determining the rubber wear on a pulley lagging.
Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The following is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
For outer layer 3, preferably black 60 Shore A Durometer flame-retardant styrene butadiene rubber (SBR) is applied approximately 12 mm thick. Many compound, hardness and color variations exist for outer layer 3. Common rubber options include Chloroprene (neoprene), Natural, Butadiene Acrylonitrile (nitrile), and Ethylene Propylene (EPDM). Hardness ranges from 45-85 shore A Durometer. Color is optional and is usually black. The thickness of outer layer 3 rubber can range from 2 mm to 50 mm.
A rubber solvent, such as Xylene sold by Brenntag Mid-South in the U.S., is usually applied by brush, wiper or roller in less than a 1 mm coat to the surfaces between outer layer 3 and inner layer 4 which will be in contact during vulcanization.
For outer layer 3 and inner layer 4, Table 1 lists the ingredients and the amounts mixed to form the laminate of the present embodiment. Columns 1 and 3 of Table 1 show the chemical or trade names of the ingredient, and columns 2 and 4 list the amounts used in parts per hundred units (pphr) by weight for the present embodiment of the invention. The thickness of inner layer 4 will be approximately 3 mm, but can be between 0.8 mm to 50 mm.
It is understood that the preceding description is given merely by way of illustration and not in limitation of the invention and that various modifications may be made thereto without departing from the spirit of the invention as claimed. From the description above, a number of advantages of our method for constructing a pulley lagging laminate having at least one inner layer with different light reflectance than the outer layer become evident.
For outer layer 3, preferably black 60 Shore A Durometer flame retardant styrene butadiene rubber (SBR) is applied approximately 12 mm thick, but can be between 2 mm to 50 mm thick. Many compound, hardness and color variations exist for outer layer 3. Common rubber options include Chloroprene (neoprene), Natural, Butadiene Acrylonitrile (nitrile), and Ethylene Propylene (EPDM). Hardness ranges from 45-85 shore A Durometer. Color is optional and is usually black. The typical method of vulcanizing this rubber uses a sulfur cure system.
A rubber solvent, such as Xylene sold by Brenntag Mid-South in the U.S., is usually applied by brush, wiper or roller in less than a 1 mm coat to the surfaces between outer layer 3 and inner layer 4 which will be in contact during vulcanization.
Inner layer 4 and outer layer 3 components can be separately mixed using rubber processing techniques known to those skilled in the art and using standard rubber processing equipment. For example, a wide variety of machines and methods can be used to mix the ingredients, such as open mills, internal mixers, etc. Thickness of inner layer 4 will be approximately 3 mm, but can be between 0.8 mm to 50 mm. The contrasting color layer 4 must have a rubber composition that is compatible with the rubber in layer 3. Further, layer 4 must have a cure system that is the same or similar in composition to the cure system used in the rubber layer 3. If either the rubber composition or the cure systems are not matched correctly, the contrasting color layer 4 could separate from layer 3. Table 1 shows an example of a layer 4 white rubber compound for use with a layer 3 black rubber compound. Columns 1 and 3 of Table 1 show the chemical or trade names of the ingredient, and columns 2 and 4 list the amounts used in parts per hundred units (pphr) by weight for the present embodiment of the invention.
The following components for layers 3 and 4 will be separately thoroughly mixed:
It will be apparent to one skilled in the arts when the separate mixing of inner layer 4 and outer layer 3 components is complete.
A rubber solvent, such as Xylene sold by Brenntag Mid-South in the U.S., is usually applied by brush, wiper or roller in less than a 1 mm coat to the surfaces between outer layer 3 and inner layer 4 which will be in contact during vulcanization.
After applying the solvent, outer layer 3 and inner layer(s) 4 are placed together to be vulcanized. A wide variety of machines and methods can be used to vulcanize the lagging laminate, including but not limited to, a double band press, a rotary curing press (e.g., rotocure), a autoclave, etc. Curing pressure of approximately 50 psi and cure times sufficient to reach internal lagging temperatures of approximately 260 degrees F. will complete the vulcanization of layers 3 and 4 into a lagging laminate.
In a second embodiment of the lagging laminate, the differing light reflectance of layer 4 is achieved by using materials in layer 4 which make the layer florescent. This list of materials for the laminate with preferred florescent layer 4 is shown in table 2. Columns 1 and 3 of Table 2 show the chemical or trade names of the ingredient, and columns 2 and 4 list the amounts used in parts per hundred units (pphr) by weight for the present embodiment of the invention.
In a third embodiment of the lagging laminate, the differing light reflectance of layer 4 is achieved by using materials in layer 4 which make the layer phosphorescent. Standard sulfur cure systems for rubber do not work for this embodiment because they will nullify the phosphorescence. Further, the polymers used must be clear in nature. As most polymers range in the milky to blown color range, their use will also nullify the desired visual enhancements.
Thus, two areas must be addressed. This invention covers a cure system change for the rubber compound in layers 3 and 4 from a “sulfur cure system” to a “peroxide cure system” for the third embodiment. Also, our invention uses clear polymers like certain polyurethanes, ethylene vinyl acetate, clear pale crepes, polybutadiene, and others cured with a “peroxide cure system” in layer 4.
This list of materials for the laminate with a black rubber layer 3 and a phosphorescent layer 4 is shown in table 3. Columns 1 and 3 of Table 3 show the chemical or trade names of the ingredient, and columns 2 and 4 list the amounts used in parts per hundred units (pphr) by weight for the present embodiment of the invention.
In a forth embodiment of the lagging laminate, the differing light reflectance of layer 4 is achieved by using materials in layer 4 which make the layer “sparkle” as they reflect much of the incident light directed at it. This list of materials for a laminate with a “sparkling” incident light reflecting layer 4 is shown in table 4. Columns 1 and 3 of Table 4 show the chemical or trade names of the ingredient, and columns 2 and 4 list the amounts used in parts per hundred units (pphr) by weight for the present embodiment of the invention.
While the present inventions have been described in conjunction with various embodiments and examples, it is not intended that the present inventions be limited to such embodiments or examples. On the contrary, the present inventions encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art.
While the inventions have been particularly shown and described with reference to specific illustrative embodiments, it should be understood that various changes in form and detail can be made without departing from the spirit and scope of the present inventions. Therefore, all embodiments that come within the scope and spirit of the present inventions, and equivalents thereto, are claimed.
The present inventions pertain to lagging laminates, and in particular, to lagging laminates that contain layers of different light reflectance such that the level of laminate wear can be shown by the different reflectance of an inner layer. Various embodiments of the present inventions can be used, for example, in the mining, cement, concrete and aggregate sectors in applications where determining the level of wear of rubber parts is critical. Examples of possible applications, include, but are not limited to, use as a lining material to protect surfaces handling abrasive material such as for chutes, hoppers, cyclones, pipes, elbows, tanks, collectors, truck bins, silos, vibrators, etc.; use on conveyor belt skirting and scrapers; use on pulley lagging; use on sand blasting curtains; etc., and in general on any application that involves wear of a rubber material.
Although the descriptions above contain many specifics, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Many other variations are possible. Other combinations of outer and inner layers are possible. Other thickness and shapes of outer and inner layers are possible. Other materials to achieve differing light reflectance are possible. Thus the scope of our invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
