Device and method for the widening and forming of a can body
The invention relates to an apparatus for spreading and shaping can bodies, having a pin-like shaping tool that is forced from one end into the can body to be widened and a counter tool.
 The invention relates to an apparatus for spreading and shaping can bodies, having a pin-like shaping tool that is forced from one end into the can body to be widened and a counter tool.
 The invention also relates to a method of spreading and shaping can bodies where a pin-like shaping tool is forced into a can body and moved toward a counter tool.
 Such an apparatus and method are described in German 100 40 173. This apparatus has a hard and massive shaping block made of steel or another hard material and of cylindrical cross section that has over most of its length a large diameter corresponding to an inside diameter of the spread can body and near its upper end a frustoconical portion. Above this frustoconical portion is a short region of smaller diameter that corresponds to the inside diameter of the unspread can body. The shaping block is used by forcing it into the can body to be spread. The shaping block can further have on its lower end a tool for forming a flange and constituted as a steel plate that is formed on its upper face with an annular groove of undercut section that is reached by the lower end of the cylindrical can body as it is being spread so as to engage it. The counter tool according to German 100 40 173 serves for forming a flange on the upper end of a can and also is formed as a steel plate having a face turned toward the shaping block and formed with an annular undercut groove having a small annular overhanging edge that forms the inner flank of the groove. The overhanging edge engages during the spreading operation the upper end of the can body. As the shaping block is forced into a readied can body, the can body is shaped by the outer surface of the shaping block with its diameter being increased and formed in a single step with a so-called “neck in.” The grooves of the two steel plates form the two end rims of the can. The can-body shape is the same at the end of the operations as the outer surface of the shaping body, that is the can body has a cylindrical upper part above the neck-in region.
 To distinguish over competitors, the fillers want individually designed cans. The present mass-production method of shaping can bodies is mechanical expansion or spreading. The tool for doing this is comprised of a plurality of segments arranged in a cylinder and forming an outer surface of the desired shape. The tool is fitted into the welded cylinder and is spread radially outward by means of an internal cone so as to deform the can body. The disadvantage of this method is that the finished can body is somewhat polygonal, the can-body material is locally very greatly stretched, the rim is irregular, and the spreading does not extend to the rim and thus there is not a precisely shaped edge.
 Other methods use a shape-imparting hollow die in which the rims are deformed. Highly pressurized air or a water stream serves for the deformation. Such methods are expensive, slow, and inflexible.
 Embossing the desired shape can also be done by so-called spin-flow shaping which is actually a roller-pressing operation which does not spread but instead reduces the diameter of the weld rim. This method can only produces rotation-symmetrical shapes.
 Based on this state of the art, it is an object of the present invention to provide a method and apparatus of the above-described type that produces cost-efficient, flexible, and easily changed can-body shapes, including nonrotation-symmetrical shapes. The machine elements serving this purpose should be as robust as possible and permit deformations right up to the edge of the can rim.
 This object is achieved by the apparatus of claims 1 to 7 and the method of claim 9.
 According to the invention the can blank has a diameter that is equal to or smaller than the smallest diameter of the finished can. In contrast to the state of the art a first embodiment of the invention has two pin-like shaping tools that are forced into opposite ends of the can body so as to deform and spread the can body until the ends of the pin-like shaping tools reach an end position. The cross-sectional profile of the two pin-like shaping tools have at least at their outer ends a region that is radially inset from other regions. This can be a frustoconical pin end or tangentially interengaging rounded surfaces or a combination of the two, and on the outer surface it is possible to have a noncircular cross section or a combination of these shapes. The pin ends have a maximum diameter that is smaller than, equal to, or slightly larger than the diameter of the can blank. In particular the cross section at least of the end tapers outward. The pin end faces can either be perpendicular to the longitudinal tool axis, inclined, or even wavy or otherwise shaped. This latter formation allows insets to be formed in the can body that extend at angles, are wavy, or otherwise deviate from perpendicular to the axis.
 An object of the present invention is also a method and use of the described pin-like shaping tools.
 Further embodiments of the invention as well as advantages are described with reference to the drawing. Therein:
 FIG. 1 is a schematic representation of two pin-like shaping tools that are movable toward each other through holes in strippers, shown in the starting position before can-blank deformation;
 FIG. 2 is a view like FIG. 1 with the can-shaping tools moved partly together;
 FIG. 3 is the end position of the shaping tools in which the can body has its final shape;
 FIG. 4 is a side view of the can profile produced according to FIGS. 1 to 3;
 FIGS. 5 to 9 are differently shaped can bodies; and
 FIG. 10 is a stackable can body with a rotation-symmetrical decorative shape.
 As already mentioned, the can blank is welded to a diameter that is equal to or less than the smallest diameter of the finished shape and then is deformed by forcing into one or both ends shaping tools to impart to it the final greater diameter of the outside of the shaping tool. The formation of the pin ends and of the pins is the same as the desired shape and the can geometry. If according to the desired finished shape, the pin end is of equal or greater diameter than the inside diameter of the welded can blank, the blank end is slightly spread in a first step so that the pin can be forced automatically into it.
 As shown in FIG. 1, two pin-like shaping tools 1 and 2 that can pass through holes of spaced strippers 3 and 4 serve as shaping tools for a can blank 5 whose ends are slightly frustoconically spread so that the outer ends of the shaping tools 1 and 2 can be fitted into them. The open blank 5 is positioned by unillustrated means known in the art between the strippers 3 and 4 and is aligned coaxially with the axes 6 of the shaping tools 2 shown in their upper and lower end positions.
 As shown in FIG. 2, the shaping tools 1 and 2 are moved together as shown by arrows 7 and 8 so that they spread the can blank 5 until they reach the end position of FIG. 3. The shape of the shaping tools has been imparted to the can blank 5 which is formed in its lower third with an outwardly open recess 9 that is formed by the tapered ends of the shaping tools. The ends of the shaping tools in the FIG. 3 end position abut each other flatly. After deforming the can blank 4 the shaping tools 1 and 2 are pulled apart so that the deformed blank is left between the stripers 3 and 4 and can then be carried off by a conveyor as is known in the art. FIGS. 1 to 3 show that not only the shaped end of the shaping tools but their entire outside shape has been imparted to the blank 5 so that not only the smooth round shapes of FIG. 4 and 4 can be produced, but also nonround shapes corresponding to FIGS. 6 and 7 can be produced as well as longitudinally shaping corresponding to FIG. 8 or FIG. 9 in addition to combinations of these shapes.
 FIG. 5 shows a spread blank 10 with a shape having a protective recess 11 that is formed by pushing the lower shaping tool almost to the upper end of the blank and making the upper shaping tool much shorter. In this case the end faces of the tools abut on a plane perpendicular to the longitudinal axis 6.
 FIG. 6 shows a spread blank 12 with an asymmetrical wave-like decorative shape. The recess 11 is annular but not orthogonal to the longitudinal axis 6, but inclined thereto and is also wavy. This is created by two pin-line shaping tools with correspondingly shaped ends whose end faces meet at an angled or wavy surface extending across the axis 6 and inclined or crossing a plane. These tools according to the invention only spread the can blank so have no insets and their frustoconical ends meet according to the desired shape and position of the recess.
 The blank 14 of FIG. 7 is also asymmetrical and has two nonlinear regions 15 and 16 in which they taper to a smaller diameter which in the intermediate region 17 is constant according to the shape of the pin ends. In general the shape can be oriented according to the drawing.
 In the can blank 18 of FIG. 8 there is a combination of a rotation-symmetrical decorative shape and longitudinal profiling 19 that are made by the outer surface of the shaping tool. In order to produce this can blank two pin-like shaping tools are used whose end faces abut inside the can blank at a plane 20 in the end position. In addition to the inset 21 the lower shaping tool also makes a lower large-diameter region 22 that is the same or different diameter as the upper cylindrical region 23 of the blank.
 The can blank 24 has an outer surface that flares outward to upper and lower end regions 25 and 26 from a central plane 27, that is the shape is basically concave.
 FIG. 10 shows how two can blanks 5 according to FIG. 4 can be stacked. The same is also true for the other can blanks.
 The above-described pin widening method has the following advantages over the prior-art spreading method:
 The spread blank, depending on the pin shape and not including longitudinal profiling, is circularly round and not inherently polygonal.
 In addition the sheet metal is stretched uniformly so that more stretching is possible with the same metal deformation. There are no significant length changes. The shaping extends right to the blank end.
 In addition there is a desired uniform reduction in the thickness of the sheet metal in the cylindrical part, while in the stressed shape region the original sheet thickness is retained.
 The shaping tools that are used are simple, robust, and easy to retrofit to or install in existing equipment, when different shapes are needed.
 The shapes shown in FIGS. 1 to 10 can be varied greatly, the limits to the shapes being small, with respect to the use of the sheet metal and lacquer. As already stated, one is not restricted to recessed formations.
1. An apparatus for spreading and shaping can bodies (5), having a pin-like shaping tool (1) that is forced from one end into the can body (5) to be widened and a counter tool (2), characterized in that
- the counter tool (2) is also a pin-like shaping tool insertable from an opposite end into the can body (5), the shapes of the ends of the two pin-like shaping tools (1 and 2) being the same or complementary according to the desired shape.
2. The apparatus according to claim 1, characterized in that the shape of the two pin-like shaping tools (1 and 2) at their ends has in regions inset toward the longitudinal pin axis (6) from other regions.
3. The apparatus according to claim 1 or 2, characterized in that the pin ends have a maximum diameter that is less than, equal to, or slightly greater than the diameter of the unspread can blank (5).
4. The apparatus according to one of claims 1 to 3, characterized in that the pin ends taper outward axially at their outer ends.
5. The apparatus according to one of claims 1 to 4, characterized in that the pin end faces meet at least partially in regions not orthogonal to the pin longitudinal axis (6).
6. The apparatus according to one of claims 1 to 5, characterized in that the pin outer surfaces deviate at least locally from a cylindrical shape.
7. An apparatus for spreading and shaping can bodies (5), having a pin-like shaping tool (1) that is forced from one end into the can body (5) to be widened and a counter tool (2), characterized in that the pin outer surfaces deviate at least locally from a cylindrical shape.
8. The apparatus according to one of claims 1 to 7, characterized in that the pin-like shaping tools are movable relative to strippers (3 and 5).
9. A method of spreading and shaping can bodies (5, 10, 12, 14, 18, and 24), wherein a pin-like shaping tool (1) is forced from one end into the can body (5) against a counter tool (2), characterized by use of an apparatus according to one of claims 1 to 8.
International Classification: B21D041/00;