Lubricating adhesive solution for steel sheet stamping.

Description

1 / 10 DESCRIPTIVE REPORT Lubricating adhesive solution for steel sheet stamping. Field of Invention

[001] This descriptive report of the Invention Patent concerns a lubricating adhesive solution for stamping rolled steel sheets, hereinafter referred to as Lubricating Adhesive Solution, which corresponds to a product to be applied to the surface of steel sheets produced by steel rolling mills, contributing to technological innovation in the field of the steel and manufacturing industry. History of the Invention

[002] During the steel rolling process, several problems can occur due to poor maintenance, inadequate quality control, or lack of real-time monitoring of the rolling process, highlighting problems that can affect the quality of the final product and the efficiency of the process.

[003] Among the most common problems in the rolling process, the following stand out: the appearance of cracks and fissures, deformations, undulations, lack of uniformity in thickness, surface scaling, residual stress and inclusion of impurities, notably that such problems can occur due to wear or failure in the adjustment of the rolling cylinders, failures in temperature control, problems in the cooling system, inefficient or ineffective lubrication, contamination of the material during the process or lack of control in the treatment of the raw material.

[004] In sheet metal stamping operations, which are very common in the automotive industry, for example, increasingly thinner sheets are used, that is, sheets with smaller thicknesses to reduce the mass of vehicles, which are subjected to increasingly greater deformations, making them more susceptible Petition 870250047354, dated 06 / 06 / 2025, page 3 / 16 2 / 10 to cracks or ruptures, which compromises efficiency and increases costs due to process losses.

[005] With the aim of obtaining a solid lubricant capable of improving the formability levels of metal sheets, but at low cost and with a quick solution, the initial search was for materials available on the market that could be applied to metal sheets. The development of a specific product for this application would imply a high cost and a medium- or long-term solution to industrial problems.

[006] Based on this, a material with great potential was found to be low-tack transparent vinyl "mask" type adhesive, which is characterized by low adhesion to the application surface, serving only as a support for the precise positioning of the final adhesive. Thus, the glue used in the "mask" type adhesive allows its removal from the application surface without damaging the coating or leaving residue on the surface of the sheets.

[007] The smooth surface, characterized by a low coefficient of friction, and the low adhesion to the application surface and the high resistance of the "mask" type adhesive, gave this material potential characteristics for its application as a solid lubricant in stamping processes.

[008] The application of lubricating vinyl adhesive allows steel sheets to reach higher levels of deformation without rupture, enabling the manufacture of parts with more complex designs and reducing process losses, contributing to significant cost reduction and increased efficiency in the stamping process. State of the Art

[009] The mills that supply the steel sheets apply films as coatings during the rolling process to protect the surfaces of the steel sheets during rolling, transport and storage; these films are used only as product packaging, with the aim of preventing damage such as scratches, stains or corrosion marks, which can compromise the quality of the rolled steel, it being noted that these films are Petition 870250047354, dated 06 / 06 / 2025, page 4 / 16 3 / 10 designed to be removed from the surface of the sheet metal during the manufacturing of the stamped part.

[010] The protective films applied typically include plastics, polyester, polyethylene (PE), polyvinyl chloride (PVC); oils (anti-corrosive, mineral or industrial) and some manufacturers also coat the sheets with wax.

[011] Patent PI0900870-5, filed on 08 / 04 / 2009 and granted on 26 / 01 / 2021, comprises a final product formed by laminating printed or unprinted polyester / PET (polyethylene terephthalate) films onto metallic surfaces, such as: galvanized steel (HDG), electro-galvanized steel (EG), cold-rolled steel (CRS), uncoated steel (BNR), aluminum and tinplate; laminating these films in continuous metal pre-painting lines, known as coil coating.

[012] Unlike the solution proposed here, which proposes the application of a vinyl adhesive film at the end of the lamination process of the steel sheets to be used in stamping, patent PI0900870-5 reveals that the lamination of polyester films will be applied specifically to continuous metal pre-painting lines, whose final product is intended for the manufacture of packaging, and establishes that polyester / PET adhesives will be laminated onto metallic surfaces, where galvanized and cold-rolled steel sheets are used. It also mentions that the lamination of the films must guarantee the necessary characteristics for subsequent transformation by processes such as bending, stamping, embossing, pasteurization, reclaving, etc., which are classic sheet metal forming operations intended to obtain various products, such as packaging, and clarifies that its invention is intended for the lamination of adhesives aimed at the appearance of the final product, mentioning various textures used, that is, the invention aims at an adhesive that is more resistant to delamination (adhesive coming off the surface of the sheet metal) and combines the lamination technology by the "Coil Coating" process with the technology of printing polyester films by the Rotogravure process, always with a view to the metal packaging markets. Petition 870250047354, dated 06 / 06 / 2025, p. 5 / 16 4 / 10

[013] Another important difference to be highlighted is that patent PI0900870-5 clarifies that the invention is intended for the lamination of adhesives aimed at the appearance of the final product, mentioning various textures used and highlighting that the invention aims for a more delamination-resistant adhesion, preventing the adhesive from detaching from the metal sheet. The "Final Specifications and Tests" section demonstrates the importance of the film's adhesion in PI0900870-5, for galvanized, electro-galvanized and cold-rolled steels, where the results of the Adhesion (ASTM D 3359), Flexibility (ASTM D 4145), Impact (ASTM D 2794) and Embedding (NBR 5902) tests were presented. In addition to these, resistance tests to certain products and environments susceptible to damage to the coating were carried out.The tests performed, in accordance with the aforementioned standards, demonstrate the author's objective of evaluating the resistance of the film applied to the surface of the metal sheet, since it must be durable during the packaging manufacturing process, for the products it is intended for, and in the environment.

[014] Unlike patent PI0900870-5, the solution proposed here produces a low-tack adhesive for sheet metal surfaces, precisely so that it can be easily removed from parts after stamping, without leaving glue residue on the part. In this work, the main test performed was the Nakazima stamping test (ISO 12004-2 standard), which was not performed in the patent found. The Nakazima test aims, through the forming limit curves, to evaluate the efficiency of the sheet metal when subjected to stamping operations, that is, the evaluation in question concerns the efficiency of the sheet metal in obtaining the part. In this case, the proposed invention lies in the application of the vinyl adhesive to the surface of the sheet metal (product: sheet supplied by the mill with the adhesive), which acts as a "lubricant" in the process, increasing the stampability (performance) of the sheet during the part manufacturing process.This benefit of the vinyl adhesive, associated with improved sheet performance during the stamping process, was proven in the results of the tests presented. Petition 870250047354, dated 06 / 06 / 2025, page 6 / 16 5 / 10

[015] One of the objectives of the invention proposed here is to provide a solid adhesive lubricant as a new lubrication solution for forming AHSS steel sheets in the manufacture of stamped parts for the automotive industry, capable of improving the stampability levels of metal sheets with low implementation and operating costs.

[016] Thus, in order to allow for a better elucidation of the object in question, its description will proceed with reference to the following figures and tables, where:

[017] figure 1 presents a diagram with the classification of adhesive films;

[018] figure 2 illustrates the main stages of sheet metal production, including the application of the adhesive film on the surface of the already laminated sheet;

[019] Figure 3 illustrates the comparative Limit Forming curves for straight and circular steel specimens - highlighting the greater formability provided by the adhesive film proposed here;

[020] Table 1 illustrates the characteristics of the proposed adhesive film. Features: Transparent adhesive film with low "tack". Material: Monomeric polyvinyl chloride laminate, 80 µm thick. Adhesive: Water-based acrylic transfer adhesive, low tack. Paper: 60 g / m² Glassine paper with silicone. Durability: 1 year. Supply Conditions: Roll: 1.0 m wide x 50 m. Applications: Boats, automobiles, visual communication, and architecture. Table 1. - Characteristics of vinyl adhesive film.

[021] In accordance with what is illustrated in the figures mentioned above, the “LUBRICATING ADHESIVE SOLUTION FOR STEEL SHEET STAMPING”, the subject of this Invention Patent, consists of a vinyl adhesive lubricant (1), more specifically monomeric polyvinyl chloride with low adhesion to the application surface and known as low “tack” or low adhesion application, mask-type adhesive, applied to the surface of the metal sheet (2), at the end of its rolling process by steel rolling mills, preparing said sheet for the Petition 870250047354, dated 06 / 06 / 2025, page 7 / 16 6 / 10 stamping process in the automotive and metallurgical industry in general, with the aim of improving the technical stampability characteristics of steel sheet (2) in order to reduce defects in critical products.

[022] The monomeric polyvinyl chloride film (1) has as its main characteristic low adhesion to the application surface, serving only as a support for the precise positioning of the final adhesive. Thus, the glue used in the “mask” type adhesive allows its removal from the application surface without detaching the final adhesive from the surface.

[023] The smooth surface, which has a low coefficient of friction, as well as the low adhesion to the application surface and the high resistance of the “mask” type adhesive, gave this material characteristics for its application as a solid lubricant in stamping processes, highlighting that the application of monomeric polyvinyl chloride (1) is carried out at the end of the lamination line.

[024] The materials used in the tests are low-adhesion Monomeric Polyvinyl Chloride (2), which corresponds to a polyvinyl chloride film with added monomeric plasticizers, and DP600 Double-Sided Steel, as it is an AHSS steel widely used in the manufacture of structural components for vehicle bodies.

[025] The characteristics and properties of the materials used in the tests are presented below: i-) MONOMERIC POLYVINYL CHLORIDE (2) - Material: Monomeric Polyvinyl Chloride laminate with a thickness of 80 µm. - Adhesive: Low-tack, water-based transfer acrylic. - Paper: Glassine crystal paper 60 g / m2 with silicone. ii-) DP600 DOUBLE-SIDED STEEL Tests Performed

[026] The tests performed on the final product, i.e., after application of Monomeric Polyvinyl Chloride, were as follows: Petition 870250047354, dated 06 / 06 / 2025, page 8 / 16 7 / 10 - Tensile test according to NBR 6673; - Stamping tests according to the modified Nakazima method, which allows the use of different geometries of the drawings or figures (drawbeads) with the flat geometry referring to the test without the tooth, with the blank holder surface without protrusion, and also with the circular geometry, which refers to the hemispherical shape of the tooth.

[027] It is worth highlighting the different geometries of specimens used in the stamping tests. Eight geometries were used to determine the complete CLC curve, without lubricant. For tests with lubricant, specimens with widths of 200, 175, 150, and 125 mm were used. For the lubricant evaluation, the tests were limited only to the wider specimens, which characterize the stretching deformation mode of the material, since in this condition the blank holder and the geometry (drawbead) have a more effective role in controlling the sheet flow during stamping. This condition is more similar to the characteristics of industrial tools. In the narrower specimens, with widths of 100, 90, 80, and 70 mm, the free sides from the action of the blank holder make the evaluation of lubrication and other process parameters less precise.

[028] The tests were carried out with a plate press force of 80 tf for all tests. All test specimens had a grid of circles with a diameter of 5 mm engraved on the surface by a “silk screen” printing process.

[029] The Vinyl Adhesive Detachment Force Measurement Tests, according to the proprietary method, refer to tests performed to measure the force required to remove the vinyl adhesive from the metal sheet after stamping. The test was performed manually, both to hold the sample and to apply the force to detach the adhesive, since this operation will also be performed manually in the industry. The force measurement was performed with a digital scale with a capacity of 50 kg, attached to one end of the adhesive.

[030] The results obtained from the tests are presented below: Petition 870250047354, dated 06 / 06 / 2025, page 9 / 16 8 / 10 Analysis of Vinyl Adhesive Stamping a) Adhesive adhesion and resistance to sheet metal during stamping: as a first analysis regarding the behavior of the vinyl adhesive in stamping, its adhesion to the sheet metal and resistance to deformation during the test can be observed. In all four test specimens, the adhesive remained intact across the entire surface of the sample, without detaching in any region, attesting to the excellent adhesion of the material to the sheet metal without detaching, even when subjected to compressive stress between the tool and the sheet metal and the flow of the material during its deformation. Another relevant aspect that attests to the efficiency of the solid lubricant is that in none of the test specimens was the adhesive rupture observed, especially in the central region of the sample, where the punch acts. In this way, the permanence of a uniform lubricating film is guaranteed throughout the deformation region of the sheet metal that is subject to frictional forces with the surface of the punch; b) Adhesive removal: when pulled manually, the adhesive detached easily from the sheet surface, requiring a force of 0.740 kg to completely detach it. Other important aspects to be observed are that the adhesive did not tear when pulled quickly, nor did it leave any residue on the material surface; that is, it meets two requirements that would cause a loss of time in a production line. Thus, it can be said that the vinyl adhesive also meets the third requirement of the proposal, that is, it is a material that is easy to remove; c) Adhesive efficiency in sheet metal stamping: visually, the incorporated images show that the samples stamped with the solid lubricant presented the crack exactly in the region of the punch pole, while in the samples stamped without the lubricant, the crack occurred in the region of the punch radius. For the tests performed with liquid lubricant (lubricating oil), the crack in the sheets remained in the same position as in the tests without lubricant. The crack in the punch radius, in tests without lubricant, indicates a greater concentration of stresses and deformations in this region. As the pole is in direct contact with the sheet being deformed under the action of the punch Petition 870250047354, dated 06 / 06 / 2025, page 10 / 16 9 / 10 There are inevitably frictional forces that hinder the flow of material in this region, causing cracking of the material in an area of ​​lower friction. Based on this, the cracking of the stamped sheets with lubricant, at the punch pole, clearly indicates a reduction in friction in this region, due to the use of the lubricant. The reduction in frictional forces at the punch pole was sufficiently large to cause a greater concentration of stresses and deformations in this location, even with direct metallic contact between the sheet and the tool. Thus, this preliminary visual analysis qualitatively attests to the high efficiency of the vinyl adhesive as a lubricant in stamping; d) Forming Limit Curves: To verify the gain in formability resulting from the use of vinyl adhesive in the stamping of DP600 steel, forming limit curves were constructed for two test conditions: with flat geometry (drawbead) and with circular geometry (drawbead), illustrated in Figure 3. In both cases, a large gain in formability of DP600 steel is observed when vinyl adhesive is used, due to the expansion of the curve to the right side of the graph (represented by the blue line). The solid lubricant achieves a gain of approximately 0.20 for the smaller deformation (x-axis of the graph) and approximately 0.04 for the larger deformation (y-axis of the graph), values ​​that are extremely significant in terms of formability.

[031] The Lubricating Adhesive Solution presents as an innovation the application of low-adhesion vinyl adhesive (1) to the surface of the metal sheet (2) at the end of the lamination process (when the steel sheet is produced and supplied to stamping companies). The technical solution is that the vinyl adhesive (1) is not removed from the surface of the steel sheet (2) when received by the stamping plant, which will carry out the stamping process of the parts with the adhesive (1), improving process performance and reducing failures in critical products.

[032] The vinyl adhesive (1) applied to the surface of the steel sheet (2) acts as a solid lubricant in the stamping process, that is, it makes lubrication (friction reduction) more efficient than liquid lubricants used. Petition 870250047354, dated 06 / 06 / 2025, page 11 / 16 10 / 10 normally. However, stamping companies cannot use solid lubricants because the stamping process is high-production (reaching one piece per second) because the adhesive application time is much longer than the part production time, making its use unfeasible. Applying the adhesive to the steel sheet during the final lamination phase solves this problem, so that the raw material arrives at the stamping plant already adhered, making its use viable.

[033] Thus, the transparent vinyl adhesive (2), of the low-adhesion “mask” type, represents an excellent solution for its use as a solid lubricant in stamping operations, meeting all the initial design needs, namely, being easy to apply, increasing the formability limit of metal sheets and being easily removed from the manufactured product and representing a quick and low-cost solution for reducing the rates of parts lost in stampings.

[034] This descriptive report dealt with a new “LUBRICATING ADHESIVE SOLUTION FOR STEEL SHEET STAMPING”, presenting, as can be seen from the description and figures presented, some advantages and differentiated applications in relation to existing conventional methods.

[035] Having therefore described and illustrated the best embodiment currently contemplated for the realization of the present Invention Patent, numerous modifications and variations in its embodiment may be readily introduced by technicians and specialists in the field. However, it is understood that the present invention is not limited to the practical aspects illustrated and described in this report, encompassing within its scope all obvious variations and modifications not described.

[036] Because of the advantages it offers and also because it is novel, has industrial application and is inventive, it fulfills all the requirements and meets the necessary conditions to obtain an Invention Patent. Petition 870250047354, dated 06 / 06 / 2025, page 12 / 16

Claims

1 / 1 CLAIMS 1.- “LUBRICATING ADHESIVE SOLUTION FOR STEEL SHEET STAMPING”, applied to the sheet rolling process in steel rolling mills, preparing them for the stamping process in the automotive and metallurgical industry in general, characterized by a low-adhesion vinyl adhesive lubricating film (1), applied to the surface of the metal sheet (2), at the end of its rolling process, the film (1) being composed of a layer of laminated Monomeric Polyvinyl Chloride, with a thickness of 80 μm, a layer of low-adhesion acrylic glue and aqueous transfer on 60 g / m2 Glassine paper with silicone.

2. "LUBRICATING ADHESIVE SOLUTION FOR STEEL SHEET STAMPING", according to claim 1, characterized by allowing the stamping process of steel sheets (2) to be carried out together with the vinyl adhesive (1) adhered to the surface thereof.

3. "LUBRICATING ADHESIVE SOLUTION FOR STEEL SHEET STAMPING", according to claim 1, characterized in that said film (1) allows its complete removal immediately after stamping of the metal part, due to its low adhesiveness. Petition 870240109114, dated 12 / 20 / 2024, pp. 19 / 23

Images