Seaming roll/roller : It is the part of the seamer that performs the deforming operation of the metal, to configure the lid and body hooks and the link between them, giving rise to the seam. There are two types, the first operation, which forms the hooks and binds them, and the second operation, which crushes them together. It also receives other names such as: Wheelbarrows, seaming wheels, molars, seaming rollers
Seaming roll 2nd operation: As we have said, it is the one that crushes the body hooks and lid of the seam. Its function is less important than that of the 1st operation, and its proper definition admits certain margins when it comes to achieving a good seam.
There are many types in the market and their design can vary between them, although it is always linked to the type of seam that is to be made and the characteristics of the materials used in the manufacture of the container.
Its critical zone of the seaming roll is the throat, which acts on the incipient hooks of cover and body initiated by the seaming roll of 1º operation. This area is called the profile of the seaming roll and usually has a curved contour, formed by several arcs of different radii.
This work only aims to give some guidance on the dimensioning of the profile of the 2nd operation seaming rolls, depending on the type of seam used. Other considerations such as the material to be used in its construction, mechanical characteristics, adjustment of the same in the seaming machine, etc. they are treated in other works published on this Web page.
DESIGN OF THE PROFILE OF A SEAMING ROLL 2nd OPERATION
The upper part of this profile starts with a slightly inclined plane, approximately 2º of slope, followed by a small radius arc that links with another of greater radius, which ends in a lower double radius bead. radios can vary between 5 maximum and at least 3, although most often they are 3. See figure nº 1
Figure nº 1: Generic profile of a 2nd operation seaming roll
Keeping in mind this drawing, it is worth highlighting the following as important points of the profile of a seaming roll of 2nd operation:
Control point : This is where the top inclined plane ends and the small radius input arc starts. The vertical axis that passes through it is taken as reference to delimit the different height and depth of the profile, this axis is called the base line, and is usually tangent to the lower heel of the seaming roll. From this point the seaming roll is adjusted in height in relation to the lip of the seaming chuck. The set that must exist between this point and the upper part of the lip of the chuck is 0.02 mm .. See figure n ° 2
Figure nº 2: Adjustment seaming roll – chuck
Radius : Figure 1 shows a profile of three radios, which is the most used in this type of pieces. Of these, the most decisive is the central one (R2), of greater value, which defines the external silhouette of the seam.
Measurements : There are a few means that can remain constant whatever the profile of the seaming roll, these are the upper angle and the lower radius of the heel. The rest varies as we have said with the type of seam, which in turn is linked to the dimensions of the wing of the lid and the body flange, as well as the characteristics of the materials used in the container. Each company develops the ideal profiles to be used in each case, keeping some discretion in its dissemination. This gives rise to a multitude of solutions. We have selected in the table that follows the measures that the experience has given as good in each case, although we insist that there are many other alternatives.
|ROLLER MEASURES FOR 2nd SEAM OPERATION|
|* = Approximate measurements|
On this table it is convenient to make the following comments:
– All measurements are rounded to the hundredth of a millimeter. Therefore, in an exact geometrical tracing, slight errors may appear.
– The dimensions marked with an asterisk (*) are approximate
– Tolerances are not indicated. These should be the least possible.
The practical results of seaming rolls with these profiles, not only depend on their geometrical configuration, but also on the quality of the materials used in their construction, the surface finish, adjustment in machine, design of the seaming head, etc.