Field of the Invention The non-circular tube is applicable to the packing industry.

Prior Art

Non-circular tube is known [US3307738], consisting of tubular body (1) with a head (3) attached to one end (2) incorporating a central round opening (4) to allow the product to be dispensed. In the area where the body (1) is fixed to the head (3) the head (3) can have a non-circular cross section. The head (3) profile ensures transition of the head (3) surface along the tangent to the rounding (5) of the welding seam (6). The closing of the tube after filling is with a transverse end seam (7) formed in a plane (9) passing through the axis of the tube as close as possible to the longitudinal seam (10). The tubular body (1 ) is made from laminated foil and after welding follows the rounding (5) of the head (3). The plane of the front end (2) of the tubular body (1) prior to the welding to the head (3) is perpendicular to the axis of the tubular body (1).

The known non-circular tube has some disadvantages, illustrated in

FIG.2. The head (3) has an elliptical cross-section in the plane of the welding seam (6) to the tubular body (1), the opening (4) in the head (3) has a circular cross section and its projection in the plane of the base of the head (3) is located in the center of the ellipse. Seam (6) between the tubular body (1) and head (3) has a rounding (5) with a constant radius along the entire periphery of head (3).

To explain the disadvantages, FIG. l shows two overlapped cross- sections of the known tube - one is A-A through the long ellipse axis and the other B-B - through the short ellipse axis, representing the cross-section of head (3) in the rounding zone (5). The radius R of the rounding (5) is constant along the entire periphery of head (3), and the tubular body (1) is cut in a plane perpendicular to its axis and is positioned against the head (3) in a way so that in the widest part of the head (3) (section A- A) the front end (2) of the foil is at point A on the tangent of the inclined part of head (3) and rounding (5). Due to the different geometry of the surface of the head (3) in different sections, the height H of the tubular body (1) relative to the base of the head (3) changes along the periphery of head (3) (point B of section B-B), which results in poor appearance of the welding as the welding line is not in a plane along the entire periphery of the head (3).

Objective and summary of the invention

The objective of the invention is to develop a non-circular tube with improved appearance of the welding between the tubular body (1) and the head

(3)·

The objective is achieved by developing a non-circular tube which comprises of a tubular body (1) made from laminated foil and a head (3). The front end (2) of the body (1) is rounded (5) on the head (3) and is sealed. The head (3) has an opening (4) for expelling the product. At the region where the body (1 ) is sealed to the head (3) the cross-section can be non-circular. The end seam (7) of the tube is in a plane (9) passing through the tube axis and this axis may pass into the zone of end seam (7) as near as possible to the longitudinal seam (10) of the tubular body (1). The front end (2) of the tubular body (1) before welding to the head (3) is shaped into a 3-D curve, which, considering the shape and size of the head (3), ensures in each head (3) cross section a constant height H between the front end (2) of the tubular body (1) and the base of the head (3) according to the following relation:

Where: L is the variable length of the forming curve of the tubular body (1) in each of its sections;

a is constant length;

R is constant radius of the rounding (5);

a is variable angle between the surface line and head (3) axis;

a _max is the biggest value of the variable angle a.

It is possible (FIG. 5) that the rounding (5) can be located inside a step (1 1) on the head (3) within the welding seam zone in a way that ensures, after welding the tubular body (1) to the head (3), a smooth transition from the tube body ( 1 ) to the head (3 ) surface.

An advantage of the non-circular tube is that the welding between the tubular body (1) and the head (3) has an improved appearance.

Description of the figures enclosed

- Fig.1 shows two overlapped sections of the known tube - one along the major axis of the ellipse - A- A, and the other B-B - along the minor axis, representing sections of the head (3) in the rounding zone (5).

- Fig.2 shows that, in the known tube, the height of the front end (2) of the tubular body (1) relative to the head (3) base changes along the periphery of the head- (3).

- Fig.3 represents the appearance of the tube with a constant radius of rounding (5) in the welding zone and modified body (1);

- Fig.4 shows two overlapped sections of the invented tube - A-A along the major axis of the ellipse, and B-B - along the minor axis, representing sections of the head (3) in the rounding zone (5) with modified body (1) ;

- Fig.5 is a section of the tube with a head (3), having a step (1 1) in the rounding zone (5);

- Fig.6 shows the profile of the front end (2) of the tubular body (1) with the modified 3D cut curve on its front end (2). An exemplary realization and performance of the invention

The invention is described in more detail with an exemplary realization of the tube shown in the figures, where:

The non-circular tube in FIG.3 consists of tubular body (1) made from laminated foil, having in its front end (2) a rounding (5) around the head (3) where welding seam (6) is made. In the head (3) there is an opening (4) for expelling the product. In the welding seam (6) zone between the tubular body (1) and the head (3), the cross section is non-circular. The seam (7) at the bottom end (8) of the tube is in a plane (9) passing through the tube axis, plane (9) may be as close as possible to the longitudinal seam (10) of the tubular body (1). The front end (2) of the tubular body (1) before welding to the head (3) is shaped into a 3D curve, which, taking into account the shape and size of the head (3), provides a constant height H between the front end (2) of the tubular body (1) and the head (3), based upon the following relation:

Where:

L is variable length of the forming curve of the tubular body (1) in each of its sections;

a is constant length;

R is constant radius of the rounding (5);

a is variable angle between the surface line and head (3) axis;

a _max is the biggest value of the variable angle a.

The definition of this relation is extracted from the geometrical correlations of the tube construction (FIG.4), namely:

The length b of the part of the body (1) in the rounding zone (5) depends on the value of the angle a and is:

Ra

b =

180

The height h of the point where the surface line of the head (3) touches the rounding (5) is equal to

h - R sin a

Accordingly, the height H for angle a _max is equal to

H = Rsm a _max

The linear part of the body (1) between the start of rounding (5) and the front end (2) of the foil (1) is equal to:

H - h _{= R} sin g _max - sin a

cos a cos

The total length of the body (1) in any given section is equal to:

L = a + b + c

And, respectively:

It is possible that the rounding (5) can be located inside a step (11) on the head (3) within the welding seam zone (6) in a way that ensures, after welding the tubular body (1) to the head (3), a smooth transition from the tube body (1) to the surface of the head (3).