Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
  • B21D22/20—Deep-drawing
  • B21D22/201—Work-pieces; preparation of the work-pieces, e.g. lubricating, coating

Definitions

• This invention relates to an improved formable metal sheet and the drawing of said sheet into hollow or cupshaped articles.
• this invention relates to sheet comprising a metal substrate having a resinous coating thereon containing a metal-working lubricant, and to the drawing of such sheet.
• Earing is the name given to the formation of scallops (ears) around the top or free edge of a drawn hollow article as a resultof differences in the directional properties of the sheet metal used. Eating can develop in various metals and in the formation of different shapes of drawn hollow articles. Earing of aluminum and aluminum base alloy sheet metal, particularly in drawing cylindrically shaped hollow articles, is particularly troublesome. It is pointed out in How T 0 Determine Characteristics of Earing in Aluminum, Light Metal Age, December 1953, page 12, the types of eating which develop in drawing of aluminum and aluminum base alloy sheet. 0-90 degree ears result from a predominance of the annealing texture, and 45 degree ears are caused by a predominance of the rolling texture.
• Drawn metal containers are used for packaging a great variety of foodstuffs, beverages and other materials.
• a resistant lining or coating to prevent contact between the metal and the product in the filled container.
• Such coatings should adhere tenaciously to the underlying metal surface of the container.
• the coating should be free from harmful toxic or flavor conferring constituents and have a high degree of stability towards organic acids, fats and greases, alcohols, dilute inorganic acids, alkalies, and other constituents that may be present in the packaged products.
• the outside surface of the drawn containers are also coated with a protective or decorative finish.
• Commonly used coating materials are the resinous type such as epoxy, acrylic, and phenolic resin compositions, with or without other components such as stabilizers, plasticizers, and pigments. It is common practice to produce the containers by drawing sheet metal having the coating material already applied to the sheet.
• Procedures for applying resinous coatings to metal sheet are well-known and depend to some extent on the nature of the particular resin or resins employed. In general, they consist of cleaning the surface of the sheet, coating the cleaned surface with a liquid containing the resin, and converting the coating to a dry film. Examples of such procedures are found in United States Patents 3,114,725 and 3,206,848.
• coated sheet is ready for the forming operation.
• a disc or circular blank is cut.
• the circular blank is then coated with an additional outside or external layer of a suitable drawing lubricant, such as mineral oil, and placed in a holder, over an annular die cavity within a hydraulic or mechanical press.
• a punch then forces the blank through the die cavity thereby forming a hollow article having a cylindrical side wall and an end wall.
• a second drawing operation is sometimes employed to obtain a deeper drawn article.
• the layer of external lubricant heretofore employed in drawing metal sheet contributes to the formation of ears in the free edge or open end of drawn hollow articles such as containers, and by eliminating the layer of external lubricant between the metal sheet and the forming tools by introducing a small amount of lubricant into the coating, the formation of ears in the drawing operation is substantially reduced. It will be appreciated that there will be a small amount of lubricant at the outer surface of the coating even though the lubricant is incorporated in the coating. This small amount of lubricant is sufiicient to permit satisfactory drawing of the blank without breakout.
• the lubricant incorporated in the resinous coating should be one which is not adversely affected by heating, baking or other operations employed in producing the resin film on the metal sheet, and which is not harmful or otherwise objectionable in the use to be made of the drawn article.
• Lanolin, polyethylene, waxes, butyl stearate, fluorocarbon telomers, mineral oils and petrolatum are examples of lubricants which produce satisfactory results.
• the lubricant in the resin coating on the metal sheet should constitute 2-6% by weight of the coating.
• the preferred amount of lubricant has been found to be from 3% to 5% by weight of the coating.
• the amount of lubricant to be added for best results depends somewhat upon the lubricating efliciency of the particular lubricant used, as well as on the compatibility of the lubricant with the resinous coating material.
• the amount of lubricant should not be such that it detrimentally affects the drawn article in use, such as imparting an objectionable taste, odor, or appearance to material packaged in the article.
• the proper amount of lubricant can be blended with the resin prior to coating the sheet.
• the blending process should be such that the lubricant is dispersed throughout the coating material before application of the resultant mixture to the metal sheet.
• the more thoroughly dispersed the lubricant is throughout the coating material the better.
• polyethylene as an internal lubricant for instance
• a sufificient amount of lubricant has been mixed with the resinous coating material so that the final coating will have the desired percent of lubricant therein, it is desirable to agitate the mixture severely for approximately minutes, as by means of a high speed dispersion mill. This assures that finely divided lubricant particles are well dispersed throughout the coating material.
• the resultant mixture of internal lubricant and coating material can be applied to flat sheet metal in any conventional manner, such as by spraying, dipping or roller coating.
• flat metal sheet as used herein means both separate sheets and coiled strip metal from which blanks may be cut. Except for minor differences in mechanical handling, the procedure for separate sheets or coiled strip is the same. It is generally cheaper and more convenient to used coiled strip, however. Applying the mixture of internal lubricant and coating material to both sides of the fiat sheet metal has been found to be beneficial in obtaining drawn hollow articles with minimum earing.
• the blanks cut from coated flat metal sheet are drawn into hollow articles, such as in conventional drawing apparatus, but without the addition of an external lubricant to the blanks.
• the drawn products may be trimmed if need be; however, by employing this invention the trimming operation may, in many cases, be entirely eliminated.
• the sheets selected were composed of one of the aluminum base magnesium alloys employed extensively in commercial sheet drawing applications and in the extra hard H19 temper.
• percent of earing was calcucated on the basis of the formula:
• h the measured straight line distance from the closed bottom of the drawn article to the lowest valley between the ears.
• Sheet No. 1 was coated on the outside with a clear epoxy amine resin.
• the epoxy amine resin coating material was purchased from Midland Industrial Finishing Company under their product designation V683.
• the inside was coated with an epoxy phenol-aldehyde, and vinyl chloride copolymer vinyl dispersion resin coating which was purchased from Midland Industrial Finishing Company and sold under their trade name Mark II.
• lubricants were incorporated or mixed into either the inside or outside coatings.
• Sheet No. 2 was coated on the inside and outside exactly as Sheet No. 1.
• Sheet No. 3 was coated on the outside with a mixture of Midlands V683 clear epoxy amine resin and 2% lanolin. The inside was coated with Midlands Mark 11 vinyl dispersion resin. No internal lubricant was mixed with the Mark II inside coating material.
• Sheet No. 4 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous material and 2% lanolin. The inside of Sheet No. 4 was coated with the above-mentioned Midland Mark II coating with no internal lubricant mixed in with it.
• Sheet No. 5 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous material and 2% lanolin. The inside of Sheet No. 5 was coated with a mixture of Midlands Mark II vinyl dispersion resin and 2% polyethylene lubricant.
• Sheet No. 6 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous material and 2% lanolin. The inside of Sheet No. 6 was coated with a mixture of Midlands Mark II vinyl dispersion resin and 5% polyethylene lubricant.
• Sheet No. 7 was coated on the outside with Midlands V683 epoxy amine resinous material. Sheet No. 7 was coated on the inside with an acrylic resin coating composition purchased from the Glidden Company and sold under the product designated Glidden 66225.
• Sheet No. 8 was coated on the inside and outside exactly as Sheet No. 7.
• Sheet No. 9 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous coating material and 3% polyethylene lubricant. Sheet No. 9 was coated on the inside with a mixture of Gliddens 66225 acrylic resin coating composition and 3% polyethylene lubricant.
• Sheet No. 10 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous material and 2% lanolin lubricant. The inside was coated with a mixture of Midlands Mark II vinyl dispersion resin coating and 2% polyethylene.
• Sheet No. 11 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous material and 3% polyethylene coating. The inside was coated with a mixture of Midlands Mark II vinyl dispersion resin and 3% polyethylene lubricant.
• Sheet No. 12 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous material and 2% lanolin. The inside was coated with a mixture of Midlands Mark II vinyl dispersion resin and 3% polyethylene lubricant.
• Sheet No. 13 was coated on the outside with a mixture of Midlands V683 epoxy amine resinous coating material and 3% polyethylene lubricant. The inside was coated with a mixture of a vinyl resin purchased from Pittsburgh Plate Glass Company and sold under their product designation PPG X786 and 4 /2 petrolatum.
• the coating solvents were driven off from all of the sample sheet coatings by means of a medium velocity air oven to produce a dry coating film.
• the oven temperatures were selected so that normal curing of the coating materials was obtained.
• the amount of dry coating on all of the above sample sheets was approximately 3 mgs. per square inch on the outside and from 8 to 10 mgs. per square inch on the inside.
• the polyethylene lubricant was mixed thoroughly by slowly adding the coating material to the lubricant while agitating. The mixture was blended for 30 minutes by using a high speed Eppenbach dispersion mill.
• All thirteen of the coated sheets were cut to a round blank size of 5.66 inches diameter.
• Each of the blanks were inserted into a conventional blank and draw press which first formed a shallow shell of 303 X which was then redrawn in another press to a final 208 x 207 size shell.
• the clearance between the stationary post and cavity punch was approximately sheet gauge plus 25% of gauge per side.
• the clearance between the post and punch was increased to sheet gauge plus approximately 35% of gauge per side.
• Outside or external lubricants normally used in prior sheet metal drawing operations were applied in the amount of between 4 and 8 mgs. per square foot to both sides of the blanks cut from sheet Nos. 2, 3, 8 and 10.
• the blanks cut from the rest of the sheets did not have any external lubricant applied to them or to the forming die faces prior to or during drawing.
• the method of making a drawn hollow article from metal sheet comprising the steps of coating flat metal sheet which tends to ear upon being drawn with a mixture of resinous coating material and a metal-drawing lubricant selected from the group consisting of lanolin, polyethylene and petrolatum, the said lubricant constituting 2 6% by weight of the coating, the said coated sheet having less tendency to ear upon being drawn than it would have without the said lubricant in the coating, and drawing the said sheet into said hollow article.
• the method of making a drawn hollow article from metal sheet comprising the steps of coating both sides of flat metal sheet of an aluminum base magnesium alloy in H19 temper which tends to ear upon being drawn with a mixture of resinous coating material and a metalairawing lubricant selected from the group consisting of lanolin, polyethylene and petrolatum, the said lubricant constituting 26% by weight of the coating, the said coated sheet having less tendency to ear upon being drawn than it would have without the said lubricant in the coating, and drawing the said sheet into said hollow article. 6.
• the method of making a drawn hollow article from flat metal sheet comprising the steps of coating flat metal sheet which tends to ear upon being drawn with a resinous coating having a metal drawing lubricant selected from the group consisting of lanolin, polyethylene and petrolatum dispersed throughout the coating, the said lubricant constituting 26% by weight of the coating, the said coated sheet having less tendency to ear upon being drawn than it would have without the said lubricant in the coating, and drawing the said sheet into said hollow article without adding external lubricant.
• a metal drawing lubricant selected from the group consisting of lanolin, polyethylene and petrolatum dispersed throughout the coating, the said lubricant constituting 26% by weight of the coating, the said coated sheet having less tendency to ear upon being drawn than it would have without the said lubricant in the coating, and drawing the said sheet into said hollow article without adding external lubricant.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Laminated Bodies (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Lubricants (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Metal Extraction Processes (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

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Family Applications (1)

Country Status (11)

Cited By (9)

Families Citing this family (4)

Citations (6)

• 1967
  • 1967-05-26 US US641475A patent/US3478554A/en not_active Expired - Lifetime
• 1968
  • 1968-05-08 NO NO01789/68A patent/NO128102B/no unknown
  • 1968-05-20 ES ES354104A patent/ES354104A1/es not_active Expired
  • 1968-05-20 GB GB1226205D patent/GB1226205A/en not_active Expired
  • 1968-05-20 DE DE1752396A patent/DE1752396B2/de not_active Withdrawn
  • 1968-05-20 FR FR1581538D patent/FR1581538A/fr not_active Expired
  • 1968-05-20 NL NL6807141A patent/NL6807141A/xx not_active Application Discontinuation
  • 1968-05-21 JP JP43033812A patent/JPS4914068B1/ja active Pending
  • 1968-05-21 SE SE6891/68A patent/SE344025B/xx unknown
  • 1968-05-21 DK DK234268A patent/DK133181C/da active
  • 1968-05-24 CH CH772668A patent/CH512961A/fr not_active IP Right Cessation
• 1969
  • 1969-05-30 ES ES1969149110U patent/ES149110Y/es not_active Expired

Patent Citations (6)

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