Coating processes – Brush or absorbent applicator utilized
Reexamination Certificate
2002-02-04
2004-03-30
Edwards, Laura (Department: 1734)
Coating processes
Brush or absorbent applicator utilized
C184S065000, C184S102000
Reexamination Certificate
active
06713133
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to devices and methods for applying a lubricating coating to one or more surfaces of metallic sheet materials such as, for example, tin-plated steel stock, and aluminum sheet stock used to make aluminum beverage cans.
BACKGROUND OF THE INVENTION
Metallic sheet materials are used in the fabrication of a wide variety of articles of manufacture including beverage cans, metal housings, metal panels, metal tools, structural metal components, etc. Such metallic sheet materials are pressed, forged, stamped, drawn, ironed or otherwise formed using pressure applied in various ways to shape the metal sheet materials into useful products. In many such forming processes, it is essential that one or more surfaces of the metallic sheet materials are coated with one or more lubricant compositions of petroleum and vegetable oils, petroleum distillates, esters, fatty acids and other components that provide lubricating properties to metallic sheet surfaces.
In many manufacturing processes, the lubricant coatings are applied to the sheet surfaces as the sheet material moves through the forming process. The lubricants perform functions including the primary function of reducing the coefficient of friction between the metallic sheet surfaces and the surfaces of handling equipment, press components, forming dies and other related forming equipment. Thus, the proper application of lubricant coatings to the moving sheet surfaces is essential to such manufacturing processes and prevents substantial product defects, waste of materials, product failures, excessive forming and handling equipment wear, excess maintenance costs and other undesired adverse effects.
For example, such lubricant coatings are used in the process for forming tin-plated steel stock into various articles of manufacture, and for forming aluminum sheet stock into beverage can bodies. In forming aluminum stock into beverage can bodies, a continuous strip of aluminum sheet stock is fed from a supply coil to a “cupping press.” In that press, metal dies punch disks of aluminum from the sheet stock and press the disks into shallow cup-shaped blanks. The “cups” are transferred to a “body maker” where they are drawn and ironed into the shape of an elongated can body. The can body typically is trimmed and then cleaned, coated, printed and often subject to one or more additional shaping steps before it is filled with a beverage and sealed.
In the “cup” forming step, substantial frictional engagement occurs between the surfaces of the aluminum sheet stock and portions of the cupping press contacting the sheet stock surfaces, including the forming dies, stripping plates and other press surfaces. Consequently, one or more lubricating coatings are applied to the exposed upper and lower surfaces of the moving aluminum sheet stock while it is fed into the cupping press. The lubricating coating reduces the coefficient of friction at the interface surfaces of the aluminum sheet and the cupping press, and particularly the surfaces of the forming dies, to facilitate the proper pressing of the aluminum “cups” The lubricant coating also assists in proper passage of the sheet material into the press and waste materials out of the press. Those waste materials include the remaining web of aluminum sheet after the “cups” are punched from the aluminum sheet stock.
The inconsistent, inadequate, and non-uniform application of the lubricant coating to the moving aluminum sheet stock surfaces (as well as the surfaces of tin-plated steel and other metallic sheet materials) can result in under-lubrication of portions of the metallic sheet surfaces and, in some instances, over-lubrication of other portions of the sheet surfaces. As a result, excessive frictional forces may develop on the under-lubricated portions of the sheet surfaces at various stages of the forming process that interfere with or even prevent proper operation of the forming process. Inadequate lubrication of the sheet surfaces also may result in excessive defects in portions of the formed product, damage and excessive wear to the presses and forming dies, loss of materials and production time due to improperly formed products, increased press down time, sheet or product jams, increased costs of material and labor, and similar undesirable interruptions and inefficiencies in the manufacturing process.
For example, if an inadequate amount of lubricant coating is applied to the aluminum sheet metal used to make can bodies, then the aluminum “cups” may not properly form during the cupping stage. The “cups” may have holes or gaps in their sides or bottom, they may acquire undesirable draw marks or scratches on their sides and bottoms, they may have inconsistent dimensions or other such defects rendering them unacceptable for further processing. If such difficulties with the lubricant coatings persist, the defects rates, materials waste, and cost inefficiencies can quickly reach commercially unacceptable levels.
Similarly, the application of excessive amounts of lubricant to the sheet material surfaces also is undesirable. Over lubrication of part or all of the sheet material surfaces may result in inadequate forming pressures, sticking between press and sheet material surfaces, feed jams, improper forming, product ejection jams, jams in waste material ejection systems and other similar adverse effects. The use of excessive amounts of lubricants also may result in unwanted build up of lubricants on the forming and handling equipment requiring increased cleaning and maintenance cost and excessive lubricant expenses.
Thus, in most, if not all, applications it is desirable to apply such lubricant compositions to the sheet material surfaces in a generally uniform layer to ensure that the sheet surfaces are provided with a sufficient, but not excessive, amount of the lubricant composition. The amount of the lubricant composition and its distribution may vary from one manufacturing process to another depending on the composition of the metallic sheet materials, the surface properties and characteristics of the materials, the surface area exposed for contact with the handling and forming equipment, the size and shape of the formed product, and the forming conditions (pressures, temperatures, speeds, etc.), among other considerations that affect the necessary amount and distribution of the lubricant coating. In some applications, those amounts and distribution may be calculated, in others they are determined by field testing and analysis.
The careful control of the amount and application rate of a lubricant coating also provides substantial opportunities to optimize the necessary amount of lubricant applied and the distribution of the lubricant to enhance the operation of the forming and handling process and to minimize manufacturing expenses. Such improved controls and application methods also permit the consideration of improved forming processes, increased production speeds, alternative sheet material compositions, improved production schedules and desirable cost containment approaches.
Such improved controls are a concern in many forming processes, including aluminum can body forming processes where the sheet material feed rates are inconsistent and vary over short periods of time from relatively slow rates to relatively fast rates. Such improved controls are of particular concern where it is desirable to reduce or minimize the amount of lubricant applied to the metallic sheet surfaces. In that instance, even small variations in the lubricant coating as one approaches the minimum required lubricant amount may result in significant production difficulties due to the potential for inadequate lubrication of portions or all of the sheet material surfaces. The need for improved control over the application of the lubricant coating is further necessary where increased sheet feed rates are desired.
In prior conventional systems, a variety of approaches were used to apply and distribute the necessary lubricant coatings to sheet material surfaces. For example, i
DeBlois Robert E.
Hugill W. J. Alexander
Tracy Daniel L.
Coral Chemical Company
Edwards Laura
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