Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
2002-09-05
2004-08-03
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S796000, C072S379400, C413S073000, C413S077000
Reexamination Certificate
active
06769164
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and an apparatus for making cans such as cans for storing and preserving food, cans for containing paint and the like. More specifically the invention relates to the production of cans, which are made from three pieces, namely a bottom part, a body part and a lid or closure and to cost efficient production of cans in small batch sizes.
BACKGROUND OF THE INVENTION
A large number of different methods and apparatuses for making cans are known. Cans are typically produced in large numbers by specially crafted tools and machines and thereby the production cost for each piece can be kept at a reasonable level. On the other hand, facilities for producing cans are custom made and adapted to produce one specific can size and can shape and the lacking flexibility results in relatively high costs for changing can type.
DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a method and an apparatus enabling fast and cost efficient shifts between cans of different sizes and shapes thus enabling smaller batch sizes in can production.
Accordingly the present invention provides a method of making a tubular can body from a blank of sheet material having a pair of opposite co-extending rim portions, method comprising gripping the rim portions by gripping means, mutually moving the gripping means so as to bring the rim portions into adjacent positions, and interconnecting the rim portions of the blank by a seam so as to form the tubular can body, while a major intermediate portion extending between the rim portions remains unsupported, at least internally.
The sheet blank is thus formed into a tubular can body without using any internal mandrel of a predefined shape. This method enables cans of different sizes to be made by use of the same tools without any reconfiguration of such tools. Only the gripping positions of the gripping means have to correspond to the size of the blank of sheet material.
Each of the gripping means may preferably be provided with at least two linear degrees of freedom and one rotational degrees of freedom. Thereby easy supply and discharge of respectively raw material and can bodies will be achieved. The gripping means should preferably be actuated by power driven means, controlled by a control system so as to enable forming of can bodies of different size. In one embodiment of the invention the gripping position can be set automatically by means of detectors determining the size of the blank of sheet material being processed.
The interconnecting seam can be made by interlocking engagement folded, hook-shaped rim portions, by seaming, welding, gluing, soldering or any other conventional seam making process. Preferably seam is made by interlocking pre-folded rim portions of the blank. The provided 3 degrees of freedom enables the the pre-folded rim portions to be interlocked while the folded parts are being pressed together.
According to a further aspect, the present invention provides a method of forming a tubular can body into a desired cross-sectional shape by means of a shape-defining device having a plurality of co-extending elongated contact surface parts for contacting the can body, said method comprising inserting the tubular can body in the shape-defining device such that the contact surface parts thereof each extends substantially axially in relation to the can body and adjacent to the inner or outer side surface thereof, and mutually moving the contact surface parts laterally into contact with the can body side surface or surfaces at peripherally spaced positions so as to peripherally extend the can body and impart the desired cross-sectional shape thereto. The tubular can bodies being formed into a desired cross-sectional shape may be formed by the method described above or by any known method. However, by using this shape-defining device it is less critical whether the cross-sectional shape of the tubular can body being formed has an accurate circular cross-section or any other cross-sectional shape. As mentioned above, this way of forming the can body into a predefined shape can be performed in connection with the above described method of making a tubular, cylindrical can body, or it can be performed in connection with can bodies made in any other way, such as by extrusion, moulding etc. The method enables different shapes to be imparted into the can body just by an exchange of simple tools and therefore a relatively small number of can bodies may be shaped rather cost efficiently.
The lateral movement of the contact surface parts may preferably be actuated by power driven means controlled by a controller in a way enabling a variable stroke length of the lateral movement. As an example the contact surface parts may be moved by pneumatically, hydraulically or electrically driven actuators controlled by a computer system. Cans of different size and/or shape may thus be formed without any physical changes to the shape-defining device.
According to another aspect of the invention, the tubular can body, or a sheet blank may be formed into a desired cross-sectional shape, by passing the blank or the tubular body wall through the nips of at least three pairs of co-operating, rotating shape defining rollers extending in the same general direction, and mutually transversely or rotationally moving said pairs of rollers so as to provide said desired cross-sectional shape. Each pair of rollers may be moved one by one or simultaneously and they may be moved either linearly or rotationally in relation to the path of the sheet or can body. The distance between the rollers in a pair of rollers may be varied so as to enable various sheet thickness or wall thickness of the can bodies. This way of forming a tubular can body into a desired cross-sectional shape may preferably be combined with the earlier described way of making a tubular can body from a blank of sheet material, thus providing a unified flexible means for forming cans from blanks of a sheet material.
Another aspect of the invention relates to a method of flanging, beading and curling a tubular body, such as a can body, or a sheet blank therefor. The sheet blank or the tubular body wall is passed into the nip of a pair of co-operating, rotating rollers having at a first end thereof flange forming means, which form a flange at an adjacent first end of the tubular body or blank and bead forming means being axially spaced from the flange forming means and forming a bead in an intermediate part of the blank or tubular body, and engaging a curling tool with an opposite, second end portion of the blank or body so as to curl said second end portion. In a preferred embodiment of the invention the flanging, beading and curling may be performed simultaneously with the forming of the sheet or can body according to the previous described way of forming a can body by use of rollers. The same pairs of rollers or at least the one pair of shape defining rollers may be used. The rollers must for this purpose be adapted for the flanging by means of a flanging edge at one end of at least one of the rollers. This could be an end portion of one of the co-operating rollers having an increased diameter and extending axially beyond the adjacent end of the other roller of said pair. The rollers must furthermore be adapted for beading by bead forming means such as an peripherally extending ridge formed on one of the co-operating rollers and a ridge receiving peripheral groove formed in the other of the co-operating rollers. A curling tool can preferably be movably positioned so as to enable engagement with an opposite end of the blank or body in relation to the end where the flange is made.
The seam of the tubular can body may be made in any conventional manner. As an example, the rim portions of the can body blank may be pre-formed so as to define seam parts, which are interlocked and subsequently flattened so as to form said seam. This procedure enables a simple and cheap tool for making the seam. Alternatively, the seaming tool may bend both rim po
Bryant David P.
Glud & Marstrand A/S
Harness Dickey
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