GB2097748A

GB2097748A - Metal containers and method and apparatus for their manufacture

Info

Publication number: GB2097748A
Application number: GB8139178A
Authority: GB
Original assignee: Nittetsu Steel Drum Co Ltd
Current assignee: Nippon Steel Drum Co Ltd
Priority date: 1981-04-30
Filing date: 1981-12-31
Publication date: 1982-11-10
Also published as: JPS627056B2; KR860000484B1; JPS57183947A; PH18088A; KR830005921A; GB2097748B; AU542114B2; AU7214081A; IN152442B

Abstract

A cylindrical metal container has a body and end joined by a triple seam having a generally elongate rectangular cross section, the top (5a) and bottom (5d) parts of the seam having a convex substantially semi-elliptical or semi-circular profile. The outer face of the seam bulges outward adjacent its top (5b), or its top and its bottom, and the middle part (5c) between the top and bottom is formed to define a depression interconnecting the top and bottom and substantially parallel to the axis of the container. Body and end flanges (11, 21) are held in overlapping contact with each other in the centre of the seam, a sealing compound (9) being sealed in a void left between the edge of one flange and the curved portion of the other. The seam is formed by nip-bending the edge of the end flange with the first (entry-side) corner of a forming groove in a nip-bending and press forming roll, seaming together the body and end flanges with the forming groove in a seaming roll, then, upon completion of seaming, press forming the seam thus formed into a desired shape with the forming groove in the nip-bending and press forming roll. A nip-bending recess is provided at the first or entry-side corner of the forming groove in the nip-bending and press forming roll. <IMAGE>

Description

SPECIFICATION Metal containers and method and apparatus for their manufacture This invention relates to metal containers and more particularly to cylindrical metal containers with relatively large holding capacities such as steel drums. Such containers are made by fastening end plates to both ends of a cylindrical body be seaming. The invention also relates to a method and apparatus for making the aforesaid containers.

A steel drum is a typical example of the metal containers with which this invention is concerned.

A steel drum is made by fastening a round end plate to each end of a cylindrical body.

The fastening is generally accomplished by overlapping the peripheral flanges at each end of the body and the peripheral flanges of the end plates and then bending them over in folds. During the forming processes, a sealing compound is applied between the folds or in the seams to prevent the leakage of drum contents therethrough.

In forming a seam, a tray-like end plate is first fitted in both ends of a cylindrical can body. Each end of the body has a flange extending perpendicular to the longitudinal axis of the body. A seaming chuck having a cylindrical forming face is fitted in the end plates, which are then held, and turned, with the body. A seaming roll having a forming groove is pressed against the forming face of the seaming chuck, with the edges of the flange on the body and end plate held in the forming groove. Consequently, the flange edges are guided along the side and bottom of the forming groove and thereby become folded and seamed together. Then, the seam is pressed and corrected in shape between the seaming roll and the forming face of the seaming chuck to give a closer contact between the flanges.

The drum seam thus formed has an important bearing on the quality of a drum and in particular whether it is strong and leakproof.

Because they are formed along the outer edges of the drum, the seams are likely to strike against other objects when the drum is lifted or lowered or during transportation, which will probably result in loosening,#de- forming or cracking of the seam which may result in leakage. To avoid such problems, many proposals have been put forward and implemented as to the structure of the seam and the method and apparatus for making the seam. For example, structures of the seam are disclosed in US Patents 3,736,893 and 3,987,927.

The seam according to US Patent 3,736,893 is formed by overlaying the body and end plate flanges and helically wrapping them. The resulting seam is of round cross section and is claimed to develop a large moment of inertia and therefore great strength in the radius direction. In this seam, however, the flanges of the body and end plate are held in contact with each other simply as a result of enfolding. In addition, this seam has a relatively large void in the centre, so that a filler has to be introduced into the void to ensure adequate leakage-proofness. This use of the sealing compound not only entails an increase in production cost, but also involves a risk that the contents may come into contact with the sealing compound and be deteriorated as a result.

A seam according to US Patent 3,987,927 has an egg-like or elliptical cross section, with a relatively small radius of curvature at the top of the seam where the first fold is made. The strength at the seam top is increased because of the work hardening resulting from the reduced radius of curvature. But it is likely that excessive deformation will be involved in making the seam which may lead to cracking.

No great pressure is applied to the seam in the final stage of the seaming process, and so the contact between the hooked edges in the centre of the seam is less close than with methods involving application of great pressure. Again, if sufficient force is applied to the seam to tighten it adequately, work hardening takes place and cracks may develop.

There is therefore a need for a reliable and reproducible way of forming drum seams with high leakage-proofness and strength. Furthermore, there is an increasing demand for drums of lighter-gauge steel sheets where the use of a triple seam is popular in order to impart the necessary strength.. We have found a way of manufacturing metal containers with a triple seam, at a small cost which can be carried out by modifying existing equipment.

In the metal container according to this invention, the top of the seam has a generally semi-elliptical or semi-circular cross section, with the external sides thereof arched out to provide a large radius of curvature. Accordingly the top is subjected to less stress concentration under shock loads. The cross section of the seam as a whole is generally rectangular cross section with its long side extending vertically and with rounded corners.

Therefore, the body flange and end plate flange are parallel to the axis of the body and are held in contact with each other. The middle part of the seam is subjected to strong pressure in the direction of the radius of the body during seam end finishing using a nipbending and press forming roll so that the gap between the two flanges is eliminated and they are brought into metal-to-metal contact, increasing the strength and tightness of the seam. Because the radial pressure results in only a small internal space, the seam can give adequate leak-proofness with the application of only a small quantity of the sealing compound. The sealing compound fills the very limited space left and adds to the tightness of the seam. Furthermore since the two pressed flanges maintain metal-to-metal contact, the sealing compound is substantially free from contact with the container contents.

So the radial pressure step is significant in that it minimises contamination of the container contents by the sealing compound and deterioration of the sealing compound by the container contents.

In one preferred form of the metal container according to the invention the exterior of the seam presents a wavy configuration, bulging out at the top and bottom. This cross sectional shape permits the pressure to be concentrated in the recessed part (or pressed or indented groove) between the top and bottom projection which eliminates the residual space between the body flange and end plate flanges and thereby brings them into closer contact.

Furthermore, this pressure applied to the central part of the seam also involves the top and bottom of the seam into forming the desired shape. Damage of the seam may be classified as tearing-off or cracking of the seam element.

The seam will develop a leak when it becomes loose or tears off and some part of the seam cracks. So the strength of the seam may be defined in terms of its resistance to such tearing-off loosening and cracking. Pressure applied to the middle part of the seam minimises residual space and so produces a tightly interengaged seam which is resistant to loosening. A seam which is formed by strong radial pressure over its whole surface so as to make it resistant to loosening may become excessively work hardened and develop local cracking, particularly in regions exposed to external forces. Such cracks mostly develop at the top and bottom of the seam. It is therefore desirable to confine the pressure to the central portion of the seam that receives scarcely any such external force. Crack development can also be minimised by appropriate material selection.And the bottom part of the seam is subjected to relatively smaller external forces since it is the top part of the seam that is mainly involved in striking against other objects. Therefore, radial forming pressure can be applied to both the bottom and the middle of the seam provided that an appropriate quality of metal is employed.

In the method of manufacturing a metal container according to this invention, the edge of the end plate flange is first turn bent, prior to seaming by a nip-bending groove (hereinafter called "the recess") which comprises two different circular arcs including a circular arc having a radius of curvature less than the thickness of the end plate flange specially provided at the first or entry-side corner in the forming groove of the nip-bending and press forming roll. This edge bending permits the body and end plate flanges to be enfolded readily into a triple seam. Because it uses the nip-bending and press forming roll both for this edge bending and also for finishing the shape of the seam, the method and apparatus according to this invention allows separate rolls for nip-bending and for pressing to be dispensed with.This results in one and the same roll being used effectively for two different operations, thereby simplifying the apparatus required and increasing operational efficiency.

In the metal container manufacturing apparatus according to this invention, furthermore, there is provided a recess, having an arched cross section comprising two curves in the first or entry side corner of the forming groove in the nip-bending and press forming roll.

The edge of the end plate flange is first formed by the entry side curved portion of the recess which has a relatively small radius of curvature, approximately 2.0 to 2.5 times greater that the thickness of the material sheet and is nip-bent or turn bent to an angle of not less than 90 not more than 1 50', preferably 120-140 by the entry side curved portion of the recess which has a relatively very small radius of curvature, approximately 0.1 to 1.0 times the thickness of the material sheet.

Then the nip bending and press forming roll halts and comes to a waiting position while the seaming roll further rolls the end plate flange which has been nip-bent at its edges with the flange of the body plate to form a triple seam. Since the forming groove in the seaming roll is shaped to form a seam of generally spiral cross section the end plate flange is smoothly formed into a spiral without being subjected to localised excess working and after making one turn comes into contact with the body plate flange. At this time the end plate flange has been curved through an angle of more than 280 degrees. After the first spiral has been formed, the seaming roll completes a triple seam comprising seven layers but the edges of the flanges in the centre of the seam have not been interengaged. Then the seaming roll halts and retracts and simultaneously the nip-bending and press forming roll starts to roll and press form the seam. The recess of the forming groove therein finishes the shape of the previously mentioned projecting parts and the middle part of the forming groove which is either flat or convex press forms or indents the middle part of the seam. Thus, the recess in the forming groove has a dual function: to nipbend the flange edge, and (2) to press form a press groove on the middle part of the seam and to finish the shape of the projected parts in the seam.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a partial cross sectional view showing an end plate offered up to a body; Figure 2 is a cross section of the flange portion of the body and end plate on an enlarged scale; Figure 3 is a substantially front view of a seaming apparatus; Figure 4(a) is a cross section of the forming section of a seaming chuck according to this invention; Figure 4(b) is a cross section on an enlarged scale of a fillet provided on said forming section; Figure 5 is a detailed cross section of a forming groove cut in a seaming roll according to this invention; Figure 6 is a detailed cross section of a forming groove cut in a nip-bending and press forming roll according to this invention;; Figure 7 is a cross section of the forming groove in Fig. 6 on an enlarged scale; Figure 8 illustrates the nip-bending process of this invention; Figures 9(at, (b) and (c) illustrate successive stages in the seaming process; Figure 10 illustrates the finishing process; Figure 11 shows diagrammatically the relationship between the angle of rotation of a cam that raises and lowers the seaming and nip-bending and press forming rolls and the descent of the rolls; Figure 12 is a cross section on an enlarged scale of a seam finished by the nip-bending and press forming roll in Fig. 6; Figure 13 is a cross section on an enlarged scale of a forming groove in another nipbending and press forming roll of this invention; Figure 14 is a cross section on an enlarged scale of a seam finished by the nip-bending and press forming roll in Fig. 13; and Figure 15 is a cross section on an enlarged scale of a forming groove in still another nipbending and press-forming roll according to this invention.

Fig. 1 shows a stage preliminary to the seaming operation, in which a tray-like end plate 21 is offered up to a cylindrical body 11 of a steel drum 1. As shown, each end of the body 11 is formed with a circumferential flange 12 directed perpendicular to the axis 2 of the body. Likewise, the periphery of the end plate 21 is also bent upwardly and then outwardly so as to define a flange 22. Thus the plate 21 fits in the end of the body 11 with the flange 22 overlying the flange 12.

Fig. 2 is a cross section of the flanges 12 and 22 on an enlarged scale. As shown, the base portions of the flanges 12 and 22 are bent with radii of curvature I and m respectively, the flange 22 of the end plate 21 being formed longer than the flange 12 of the body 11. The flange lengths A and B must be great enough to form a triple seam as described below. The radii of curvature I and m at the flange base are such that the flanges 12 and 22 smoothly enter the forming groove in a seaming roll where they are to be bent.

According to the experience of the inventors, the preferable radii of curvature are as follows: I =(10#6) Xt m=(5'-'10)Xt wherein t = thickness of sheet metal.

The pre-assembled body and end plate are held by a seaming chuck and seamed together by a seaming roll.

Fig. 3 is a schematic front view of a seaming apparatus. A seaming chuck 31 is attached to a base plate 32. The seaming chuck 31 and base plate 32 are rotated together in the direction of arrow C through a drive shaft 33. The seaming chuck 31 is fitted in an indented part of the end plate 21, whereby the body 11 of the drum and end plate 21 are held by the seaming chuck 31.

A seaming roll 41 and a nip-bending and press forming roll 51 are provided near the seaming chuck 31. The two rolls 41 and 51 are circumferentially spaced at a suitable angle (for example, 15 degrees) with respect to a vertical centre line N. The rolls 41 and 51 are each rotatably supported, through a spindle 63, by the lower end of a press-down member 62 that moves up and down guided by a casing 61. The rolls 41 and 51 rotate, following the rotation of the seaming chuck 31 through the seamed part of the body and end plate. A follower roller 64 is rotatably attached to the top of the press-down member 62, and a cam 65 is held in contact with the follower roller 64. As the cam 65 rotates, the press-down member 62 moves up and down and moves the seaming roll 41 and nipbending and press forming roll 51 in the direction of the radius of the seaming chuck 31.

A guide 71 is provided adjacent to the seaming chuck 31. The guide is maintained spaced apart from the seaming roll 41 in a clockwise direction at a suitable angle (for example, 45 degrees). The guide 71 has a guide roll (not shown) provided thereon and directs the flanges of the body and end plate into the forming groove of the nip-bending and press forming roll 51 and the seaming roll 41.

Fig. 4 shows a preferred shape of the forming section of the seaming chuck. As shown, the seaming chuck 31 has a fillet 35 of generally triangular profile on the cylindrical forming section 34 thereof. One surface 36 of the fillet 35 extends along a datum plane 38 that lies close and opposite to the entry-side guide plane 48 (Fig. 5) of the seaming roll 41. The other surface of the fillet 35 forms an inclined surface (hereinafter called the inclined filler surface 37).

When the seaming roll 41 approaches the seaming chuck 31, the inclined filler surface 37 faces the exit-side corner 46 of the forming groove 42 of the seaming roll shown in Fig. 5.

The seaming chuck need not always have said fillet but it is preferred that it should do so because with such a forming face the corner of the inner edge of the seam is smoothly bent to make the seam angle-free, solid and tightly packed.

The seaming roll 41 bends, rolls in, and seams the flanges 12 and 22 of the body 11 and end plate 21 respectively, the two being held together. Fig. 5 is a cross section of the seaming roll 41, which has a circumferential forming groove 42. The forming groove 42 is substantially D-shaped, opening toward the forming face 39 of the seaming chuck 31. In the forming groove 42, a portion defining a first corner 44 between the entry-side surface (from which the flanges enter; on the right side in the figure) and the groove bottom 45 is substantially quadrantal in section. The groove bottom 45 following the first corner 44 is flat. The flat part gives smooth and trouble-free seaming. A second corner 46 following the groove bottom 45 is defined by a quadrant whose radius of curvature is smaller than that of the first corner 44.The exitside surface 47 follows the second corner 46 and extends straight therefrom. The guide plane 48 extends downward below the entryside surface 43 so that the flanges 12 and 22 entering the forming groove 42 are guided therealong.

To form a good-shaped, tight seam, the cross sectional dimensions of the forming groove 42 should fall within the following ranges: Radius of curvature of the first corner p = (3.O'--'6.0) X t Radius of curvature of the second corner q = (1.5-3.0) X t Length of the straight groove bottom D = (0-3.0) X t Length of the exit-side surface E = (1.5-4.0) X t (wherein t has the meaning previously given).

But since substantial space remains within the seam after it has been rolled, the seaming operation is not yet complete. The nip-bending and press forming roll 51 corrects the shape of the seam formed by the seaming roll 41 and tightly interlocks the seam by applying pressure to the middle portion thereof.

Fig. 6 is a cross section of a nip-bending and press forming roll that sets the formed seam into a substantially rectangular shape in cross section. The nip-bending and press forming roll 51 has a circumferential forming groove 52 of substantially rectangular cross section, opening toward the forming face 39 of the seaming chuck 31. A first corner 54 and a second corner 56 of the forming groove 52 are substantially defined by quadrants. The depth h and width W of the forming groove 52 are equal to 1/2 of the thickness and to the height of the seam, respectively. At the first corner 54 of the forming groove 52 there is provided a recess 57 that is arched in cross section. As shown in Fig. 7, the bottom of the recess 57 is substantially defined by a sextant, having a radius x, which follows the quadrant (radius = u) that substantially defines the first corner 54.Preferably, the radius of curvature u = 2t - 2.5t, the radius of curva turex=0.1t-1.Otandthedepthyofthe recess equals 1 /2t where t is the thickness of the sheet metal in mm. A guide plane 58 extends downward from the entry-side surface 53 of the forming groove 52 along which the seamed flanges entering the forming groove 52 are guided.

The method of seaming the flanges of the body and end plate using the above apparatus will now be described. To begin with, the edge 23 of the end plate flange 21 is nip-bent by means of the nip-bending and press forming roll 51. The nip-bending finishing roll 51 is pressed down toward the cylindrical forming part 39 of the seaming chuck 31, whereupon the flange edge 23 of the end plate 2, held by the seaming chuck 31, enters the forming groove 52, guided along the guide plane 58. The flange edge 23 travels along plane 58 until it encounters the bottom of the recess 57 in the forming groove 52 where it becomes sharply bent or nip-bent as shqwn in Fig. 8 into an angle of over 90 degrees by the very sharply curving exit arc of radius of curvature x less that the thickness of the end plate flange.The tip of the flange 23 is not bent but the part following the tip is abruptly bent because bending in a radius of curvature so small as to be less than the flange thick- ness is extremely difficult. A sealing compound is supplied to near the flange edge 13 of the body 11 either before or after this nipbending process.

Upon completion of nip-bending, the nipbending and press forming roll 51 is returned to standby and the seaming roll 41 is pressed down to roll together the body flange 12 and end plate flange 22. Fig. 9(a) shows an initial stage, Fig. 9(b) an intermediate stage, and Fig. 9(c) a later stage of the rolling or seaming process.

In these figures, it will be seen that as the seaming roll 41 is pushed down toward the seaming chuck 31, the flanges 12 and 22 pass through the guide plane 38 into the forming groove 42. The flanges 12 and 22 are shaped by the first corner 44, pass along the flat groove bottom 45 and then into the second corner 46 where they become more sharply curved. Thus, the forming groove 42 curves the flanges 12 and 22 in two steps, with different radii of curvature. This enables smooth fabrication, applying great seaming action on the flanges 12 and 22 and without causing excess deforming stress. As the seaming roll 41 descends fully to the position shown in Fig. 9(c) the flanges 10 and 22 are rolled or coiled about one another as shown to form the seam.

shape and further pressed for strengthening.

Fig. 10 is a cross section of the seam thus corrected and strengthened. When the seam 5, shown in Fig. 9(c) has been formed, the seaming roll 41 withdraws (upward) as the nip-bending and press forming roll descends.

Then, the external half (or the upper half in Fig. 10) of the seam 5 enters the rectangular forming groove 52, where the forming plane 39 of the seaming chuck 31 and the bottom 55 of the forming groove 52 press the seam in the direction of the thickness thereof. Simultaneously the inclined filler surface 37 and the exit-side corner 56 of the forming groove 52 press the seam in a diagonal direction.

Consequently, the seam 5 is exactly and tightly formed into the desired shape with the space between the two flanges removed and the two flanges in metal-to-metal contact.

Fig. 11 shows graphically the relationship between the angle of rotation of the cams that raise and lower the seaming and nip-bending and press forming rolls and the amount of descent of the two rolls. In Fig. 11, curves I and 11 show the seaming and nip-bending and press forming rolls, respectively. Intervals K, L and M, respectively show the nip-bending, seaming and press forming processes. First, as shown in this figure, the tip of the end plate flange is nip-bent by lowering the nipbending and press forming roll towards the forming face of the seaming chuck and below the seaming roll by turning the cam thereof.

Then the body and end plate flanges are seamed together by lowering the seaming roll below the nip-bending and press forming roll.

Finally, the seamed joint is finished by lowering the nip-bending and press forming roll below the seaming roll which is actually accomplished by raising the seaming roll back to its original position. This figure also shows the relationship of the forming processes shown in Figs. 2, 8, 9(a), (b) and (c), and 10 with the angle of rotation of the cam by indicating those Figures' numbers on the abscissa.

Fig. 12 is an enlarged cross section of the seam 5 that has been formed as described above. The top 5a which is substantially semielliptical in cross section, was formed on the entry-side of the forming groove 52 of the nip-bending and press forming roll 51 shown in Figs. 6 and 10. The projecting part 5b has that shape because it projects out into the recess 57 in the forming groove 52 of the nip-bending and press forming roll 51 when finishing pressure is applied. Preferably, the amount Z by which the projected part 5b stands out from the middle part 5c equals substantially 1/2 of the thickness of the metal sheet.All the layers of the body flange 12 and end plate flange 22 constituting the middle part 5c are pressed by the flat bottom of the forming groove 52 in the nip-bending and press forming roll 51 and run parallel to the axis of the body. Because of the strong pressure in the direction of the radius of the body, the flanges 12 and 22 in the middle part 5c are held in intimate contact with each other.

The sealing compound 9 is held in separate voids left between the edges and curved portions of the body flange 12 and end plate flange 22. The bottom 5d of the seam 5 is similar in shape to the top 5a, though smaller in cross section.

Fig. 13 shown another embodiment of the forming groove cut in the nip-bending and press forming roll. Fig. 14 is a cross section on an enlarged scale of a seam finished by this forming groove.

This forming groove 74 in the nip-bending and press forming roll 73 has an arched recess 76 of the same size and shape on each of the entry and exit sides. The radius u of the corner 75 and the depth y of the recess 76 are substantially the same as those shown in Fig. 7. But the arc following the flat part 77, with the radius u, is substantially trisected.

The portion 78 lying between two recesses 76 defines either a generally convex curve or a parallel straight line with respect to the axis of the body. Fig. 14 shows a seam 6 finished by the nip-bending and press forming roll 73 which has a projecting part 6a in the top and bottom thereof. The amount of projection Z is substantially the same as that shown in Fig.

12. As the seam is finish-formed, great pressure is applied on the middle part 6b between the two projected parts 6a. Since the finishing load applied by the nip-bending and press forming roll 73 is concentrated on the midregion 6b of the seam 6, its top and bottom portions are not subjected to excess working.

Accordingly the seam 6 undergoes less work hardening at its bottom extremity that the seam 5 of Fig. 12. Therefore, even if the seam 6 is significantly deformed as the container is being handled the probability of cracks developing is significantly reduced.

Fig. 15 shows still another embodiment of the forming groove in the nip-bending and press forming roll. This forming groove 80 in the nip-bending and press forming roll 79 has a recess 82 of the same size and shape on each of the entry and exit sides. There is an arched recess 83 between the two recesses 82. The seam finished by this nip-bending and press forming roll 79 has a ripple in the middle part 6b.

Various modifications may be made to the embodiments described above without departing from the invention, the scope of which is defined in the appended claims. For example there is no restriction as to the profile of the press formed depression or grooves in the middle part of the seam.

Claims

1. A metal container comprising a cylindrical body and a tray-like end plate fastened to each end of said body, the body having a body flange formed by bending each end thereof perpendicular to the axis of the body, the end plate having an end plate flange formed by bending the edge thereof so as to extend along and project beyond the body flange, the end plate being fitted in each end of the body with the body and end plate flanges laid together one on top of the other and the body and end plate flanges being seamed into a triple seam, wherein the seam as a whole has the general shape of an elongated rectangle when viewed in profile with top and bottom portions of its external surface convex and generally semi-elliptical or semi-circular and a middle portion thereof directed generally parallel to the axis of the container, the body and end plate flanges overlapping one another in the centre of the seam and at least the middle portion of the seam being press formed to define a depression such that the body and end plate flanges are in intimate contact with one another.

2. A container according to claim 1, in which a sealing compound is present in the void between the edge of one flange and the curved part of the other flange.

3. A metal container having at least one seam substantially as hereinbefore described with reference to and as illustrated in Figs.

10, 12 or 14 of the accompanying drawings.

4. In a method of manufacturing a metal container which comprises the steps of: fitting an end plate in an end of a cylindrical body so that a body flange formed by bending the edge of the body outward perpendicular to the body axis overlaps an end plate flange formed by bending the edge of a tray-like end plate outward to extend along and beyond the body flange;; holding the body and end plate together with a seaming chuck having a cylindrical forming face, the seaming chuck being fitted in the indented part of the end plate and sequentially pressing down a seaming roll and a finishing roll, each having a circumferential forming groove opening toward the forming face of the seaming chuck, the forming face of the seaming chuck being rotated so that the forming groove seams the body and end plate flanges into a triple seam, the improvement comprising the steps of nip-bending the edge of the end plate flange with the first (entry-side) corner of the forming groove in the finishing roll; seaming together the body and end plate flanges with the forming groove of the seaming roll, and then, after completion of seaming, finish press forming the seam into a desired shape with the forming groove of said finishing roll.

5. A method according to claim 4, wher ein the nip-bending operation is discontinued when the nip-bending roll has reached a position such that the end plate flange has been bent to a constant angle of 90-1 50 and has a length appropriate to the characteristics of the seaming roll, the seaming roll is caused to seam together the body and end plate flanges in its forming groove, and when seaming is complete the seaming roll is retracted and the seam is rolled with a forming portion of the finishing roll to depress the middle portion of the seam.

6. In a metal container manufacturing apparatus which comprises a seaming chuck, the seaming chuck having a rotatable cylindrical forming face and being adapted to hold together a cylindrical body and a tray-like end plate fitted in each end thereof, a seaming and a finishing roll, each roll being rotatable and movable toward the forming face of the seaming chuck and having a circumferential forming groove opening toward said forming face of the seaming chuck the seaming and finishing rolls respectively seaming and finishing the body and end plate flange, both extending perpendicular to the body axis, into a triple seam, the improvement which comprises a nip-bending recess that is provided at the first (entry-side) corner of the forming groove in the finishing roll.

7. Apparatus according to claim 6, in which a recess is provided at each of the first (entry-side) and second (exit-side) corners of the forming groove in the finishing roll.

8. Apparatus according to claim 6, wherein a recess is provided at each of the first (entry-side) and second (exit-side) corners of the forming groove in the finishing roll and a flat or generally convex portion is provided between the first corner recess and the second corner recess.

9. In a metal container manufacturing apparatus which comprises a seaming chuck, the seaming chuck having a rotatable cylindrical forming face and being adapted to hold together a cylindrical body and a tray-like end plate fitted in each end thereof, a seaming and a finishing roll, each roll being rotatable and movable toward the forming face of the seaming chuck and having a circumferential forming groove opening toward said forming face of the seaming chuck the seaming and finishing rolls respectively seaming and finishing the body and end plate flanges, both extending perpendicular to the body axis, into a triple seam, the improvement which com prises a seaming groove that is constituted to a D-shape comprising a straight line between a relatively large circular arc following an entry straight line and a relatively small circular arc followed by a delivery straight line.

10. Apparatus for manufacturing a metal container from a body and an end plate substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2 of the accompanying drawings, said apparatus being constructed arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in Figs. 3, 4(a), 4(b), 5, 6, 7, 8, 9(a)-9(c), 10 and 11 of the accompanying drawings.

11. Apparatus for manufacturing a metal container from a body and an end plate substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2 of the accompanying drawings, said apparatus being constructed arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in Figs. 3, 4(a), 4(b), 5 and 13 or 15 of the accompanying drawings.