阅读说明：本技术 通过壁拉延生产罐体的方法和设备 (Method and apparatus for producing can bodies by wall drawing ) 是由 A·伯丁 F·琼克 于 2019-02-04 设计创作，主要内容包括：本发明涉及一种由金属片材生产包含底部和管状体的罐体(9)的方法,所述金属片材的一侧或两侧上涂覆有聚合物层,在该方法中,首先由金属片材制造圆盘,然后将该圆盘深冲成至少在外侧上具有聚合物层的杯状物(3),然后通过壁拉延将该杯状物(3)成型为罐体(9),所述壁拉延通过使杯状物(3)移动连续穿过再冲压模具和一个或多个壁拉延环(6,7)而在单一冲程中进行。(The invention relates to a method for producing a can body (9) comprising a bottom and a tubular body from a metal sheet which is coated on one or both sides with a polymer layer, in which method a disc is first produced from the metal sheet, the disc is then deep-drawn into a cup (3) having the polymer layer on at least the outside, and the cup (3) is then formed into the can body (9) by wall drawing which is carried out in a single stroke by moving the cup (3) continuously through a redraw die and one or more wall drawing rings (6, 7).)

1. Method for producing a can body (9) comprising a bottom and a tubular body from a metal sheet which is coated on one or both sides with a polymer film (12), in which method a disc is produced from the coated metal sheet (11), which disc is then deep-drawn into a cup (3), which cup is subsequently re-drawn and which cup (5) is subsequently formed into the can body (9) by wall drawing, which wall drawing is carried out in a single stroke by a punch (1) moving the cup (5) continuously through one or more wall drawing rings (6,7), characterized in that the punch (1) has a cylindrical front end (1c) with a diameter D0 and a rear end (1a) towards its rear end with a diameter D1, wherein D1< D0 and wherein the front end (1c) is separated from the rear end (1a) by a transition (1b), wherein the diameter of the punch is gradually reduced over a transition, and wherein the shape of the transition (1b) of the front end to the rear end of the punch is a continuous curve, wherein the cone angle (a) between the tangent of the curve and the centre line of the punch is not constant over the transition, and wherein the first derivative of the curve in the transition has at least one inflection point.

2. The method according to the invention, wherein said metal sheet is a steel sheet.

3. The method according to claim 1 or 2, wherein the coated metal sheet is obtained by coating at least one surface of the metal sheet (11) with an organic resin (12) by film lamination or direct extrusion, wherein the organic resin is a polyester resin, and the thickness of a resin film is 5 to 100 μ ι η in the case of a single-layer film, or 5 to 100 μ ι η in total thickness in the case of a multilayer film.

4. A method according to claim 3, wherein the metal sheet (11) is coated on both sides with a polymer film (12, 13).

5. The method according to any one of claims 1 to 4, wherein the inlet angle (a) of the first wall draw ring is between 3.5 ° and 4.5 ° and the outlet angle (β) of the first wall draw ring is between 2.5 ° and 3.5 °.

6. A method according to any one of claims 1 to 5, wherein no external coolant is applied directly to the can body during the wall drawing operation.

7. The method according to any one of claims 1 to 6, wherein the metal sheet is selected from the group consisting of: (uncoated steel sheet (black plate), tin-plated steel sheet (tin plate), chromium-chromium oxide coated steel sheet (ECCS), tin-plated plate which has been diffusion annealed to form thereon an iron-tin alloy comprising at least 80% FeSn (50 at% iron and 50 at% tin), chromium-chromium oxide coated steel sheet (TCCT) produced by electroplating from trivalent chromium electrolyte).

8. Wall-drawing apparatus having a punch (1) and one or more wall-drawing rings (6,7) for reducing the wall thickness of a redrawn cup (5) by forcing the redrawn cup through the one or more wall-drawing rings with the punch, wherein the punch (1) has a cylindrical front end (1c) with a diameter D0 and a rear end (1a) towards its rear end with a diameter D1, wherein D1< D0, and wherein the front end (1c) is separated from the rear end (1a) by a transition (1b), wherein the diameter of the punch is gradually reduced over a transition, and wherein the shape of the transition (1b) of the front end to the rear end of the punch is a continuous curve, wherein an angle between a tangent of the curve and a centerline of the punch is not constant over a transition, and wherein a first derivative of the curve has at least one inflection point in the transition.

9. Apparatus according to claim 8, characterized in that the tangent of the continuous curve at the connection point (14) between the curve and the front end and/or at the connection point (15) between the curve and the rear end is equal at both ends to the tangent of the front end and/or the rear end, respectively (i.e. a smooth transition from the curve to the punch).

10. The apparatus of claim 8 or 9, wherein D0 is constant, or wherein D0 and D1 are both constant.

11. Apparatus according to any one of claims 8 to 10, wherein the inlet angle (a) of the first wall-drawing ring is between 3.5 ° and 4.5 ° and the outlet angle (β) of the first wall-drawing ring is between 2.5 ° and 3.5 °.

12. Apparatus according to any one of claims 8 to 11, wherein an additional wall-drawing ring (7) is used which is located after the first wall-drawing ring (6), wherein the entry angle of each successive wall-drawing ring is smaller than the entry angle of the preceding ring.

13. Apparatus according to any one of claims 8 to 12, wherein the entry angle (a) of the second wall drawing ring (7), if present, is at least 1.75 ° and/or at most 2.25 °.

14. A tank produced according to the method of any one of claims 1 to 7.

Examples

Three-layer polymer coating system with a total thickness of 30 μm is applied by film lamination to one side of a steel strip with a thickness of 0.10 to 0.50mm, which side becomes the outside of the can, hi this example a cup with a diameter of 73mm is produced in two steps using the obtained coated steel strip, the polymer coated side forming the outside of the cup, hi the first step a cup with a diameter of 100mm is deep drawn from a disc with a diameter of 150mm, hi the second step the cup is formed into a cup with a final diameter of 73mm by a further deep drawing operation, see schematic representation in fig. 1 the cup is fed to a wall drawing machine, where the wall thickness of the cup is reduced by wall drawing at a speed of 180 to 600 strokes per minute and using a re-drawing ring, followed by an entry angle of α₁And exit angle of β₁And a first wall draw ring (which reduces the wall thickness of the cup by a value of 10% to 60% (RED1)) and a gate angle of α₂And exit angle of β₂A second wall draw ring (which reduces the wall thickness of the cup by a value RED2 of 2% to 25%).

These experiments show that an entrance angle of 4 ° and an exit angle of 3 ° provide excellent results for most polymer coated tapes without external coolant. No scratching was observed. Comparative experiments show that the angle is crucial to obtain good results. According to the inventionThe method of (3) is particularly suitable for polymer coatings which contain no or only minor amounts of titanium dioxide. However, the inventors have found that, due to the loading of the film with hard particles, for example TiO with an abrasive action₂The inventors have found that the inlet angle α of the first wall draw ring is preferably about 1.5 to 2.5 when a white coating colored with titanium dioxide is used on the desired outside of the can, this is believed to be caused by hard titanium dioxide particles having a scouring (scraping) action, which increases the risk of damage to the film when processed at an inlet angle of the first wall draw ring of 3.5 to 4.5 deg. similar to the method according to the invention, a white titanium dioxide colored coating may be further processed at an outlet angle of the first ring of 2.5 to 3.5 deg. (β), an inlet angle of the second wall draw ring of 1.5 to 2.5 deg. (α), if present, and an outlet angle of 2.75 to 3.25 deg. (β).

Examples of successful combinations (good as no scratch, not good as scratch or damage, still acceptable) exit angles of 3 °. White film, TiO₂A pigment.

The polymer coated steel substrate that can be processed by the process according to the invention is preferably based on polycondensates, such as polyesters, copolyesters (including PET, PBT, polyethylene furandicarboxylate (PEF), polylactic acid (PLA)) or polyamides, polyolefins, elastomers, crystallizable addition polymers, or any other polymer that can be formed into a film by extrusion. The polymer coating may consist of one or more layers. Preferably, the polymer coating comprises or consists of: polyethylene terephthalate, IPA modified polyethylene terephthalate, CHDM modified polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene furan dicarboxylate, polylactic acid, or copolymers or blends thereof.

The sequence of the new method and apparatus is shown in more detail in the attached drawings, where fig. 1 shows the various processing systems in the various processing stages, and fig. 2 shows a schematic cross-sectional view of a polymer-coated metal sheet, in this case with a polymer film on both sides. Fig. 3 shows a schematic and enlarged part of the punch with a rear end 1a, a transition 1b and a front end 1c, as well as connection points 14 and 15, and a cut-out for explaining the meaning of the cone angle (Φ) in the transition. Fig. 4 shows details of the wall drawing operation and fig. 5 shows schematic details of the working face of the drawing ring with a straight section between the (frustoconical) inlet and outlet planes.

Fig. 1 shows how a preformed deep drawn cup 3 is formed into a finished wall drawn can body 9. The cup 3 is placed between the redraw sleeve 2 and the redraw die 4. When the punch 1 moves to the right, the cup 3 is brought to the inner diameter of the finished can 9 by a re-punching step.

The punch 1 then forces the product successively through (in this example) two wall drawing rings 6 and 7. Ring 8 is an optional upper stripper ring. The wall drawing allows the can body 9 to be formed with its final wall thickness and wall length. Finally, the bottom of can body 9 is formed by moving punch 1 towards optional bottom tool 10.

Retracting the punch 1 allows the can 9 to be disengaged from the punch 1 so that it can be released in the transverse direction. An optional upper stripper ring may assist in this. The can 9 is then trimmed, optionally necked, and provided with a lid after filling.

Fig. 2 provides a detailed illustration of a channel, such as a wall draw ring 5, of a portion of a wall of a can to be formed. The punch 1 is schematically shown.

The entry plane of the wall-drawing ring 5 is at an entry angle alpha with respect to the axial direction of the wall-drawing ring. The material thickness of the wall to be formed is reduced between the punch 1 and the wall drawing ring 5. This material constitutes the actual metal tank wall 11, which has polymer layers 12 and 13 on either side. The polymer layer 12 becomes the outside of the can body and the polymer layer 13 becomes the inside of the can body, eventually contacting the contents of the can. The figure shows how the thickness of all three layers 11, 12 and 13 is reduced.

Fig. 5 shows a schematic detail of the working face of a drawing ring with a straight section between the (frustoconical) inlet plane and the outlet plane. The radius of the transition between the straight section and the inlet plane and the radius of the transition between the straight section and the outlet plane are between 0.1 and 10mm, preferably between 0.2 and 5 mm.

The wall-drawing ring preferably has a flat section of length L at the junction between the frustoconical inlet surface and the frustoconical outlet surface of the ring. The flat section is a cylindrical ring and has a length of at most 0.6mm, preferably at most 0.5mm, even more preferably at most 0.3 mm.

Fig. 6 shows an example of a prior art method with a straight punch, where there is significant fuzz formation (a), while in the lower half (B), the punch according to the invention shows no fuzz formation.