EP2468645B1 - Thermoplastic material container - Google Patents

Description

The invention relates to a container made of a thermoplastic material, in particular a plastic bottle.

Thermoplastic material containers, for example in the food industry, are often used as containers for liquid products, such as beverages. The containers are usually formed in a blow molding machine or stretch blow molding machine from plastic preforms. For this, the plastic preforms are first thermally conditioned and then shaped in so-called blow molding under compressed air to containers.

The geometric shape of the container produced usually depends on requirements that places the product to be filled to the container. In addition, the consumer demands, for example, on the weight or stability of the container.

An important element of a container is its bottom. The bottom of plastic containers is often specially designed to have a higher stability. From the DE 60 2004 010 814 For example, a container with a bottom is known having a plurality of grooves leading outwardly from the center of the bottom. Also from the US 2009/0308835 For example, a container is known whose bottom region has ribs in the form of outwardly open grooves. A container according to the preamble of claim 1 is also made US 5,353,954 A1 known.
A disadvantage of known containers is that they can only be produced by high blowing pressures during the blowing process. Due to the shape of the soil to be achieved, in particular, the formability of the containers in the blow molding machine or stretch blow molding machine is particularly difficult.

Therefore, it is an object of the present invention to provide a container made of a thermoplastic material which is easier to mold in the production. This object is achieved by a container according to claim 1.

• einen Boden, der einen ersten und einen zweiten Oberflächenbereich aufweist,
• wobei der erste und der zweite Oberflächenbereich bei konstantem Radius bezüglich der Längsachse des Behälters jeweils einen konstanten Abstand zu einer ebenen Fläche, die senkrecht zur Längsachse angeordnet ist, aufweisen,
• wobei der erste Oberflächenbereich gegenüber dem zweiten Oberflächenbereich in Richtung des Behälterinneren hin versetzt ist,
• wobei der erste und der zweite Oberflächenbereich durch einen dritten Oberflächenbereich verbunden werden, der in Form eines zusammenhängenden Schleifenbandes ausgebildet ist und wenigstens drei Schleifen aufweist, und
• wobei der Übergang zwischen dem ersten Oberflächenbereich und dem dritten Oberflächenbereich und/oder der Übergang zwischen dem zweiten Oberflächenbereich und dem dritten Oberflächenbereich wenigstens einmal, insbesondere wenigstens zweimal, stetig differenzierbar sind; und wobei eine Schleife des Schleifenbandes in Querrichtung durch eine Spline n-tem Grades beschrieben wird, wobei n größer oder gleich 2 und kleinen oder gleich 7 ist. Dadurch dass die zu erreichenden Übergänge zwischen dem ersten und dem dritten bzw. dem zweiten und dem dritten Oberflächenbereich des Behälterbodens wenigstens einmal stetig differenzierbar sind, kann der Behälter, insbesondere der Boden, in einem Blasformprozess einfacher hergestellt werden. Insbesondere kann der notwendige Blasdruck zum Herstellen des Behälters geringer sein als der nötige Blasdruck für im Stand der Technik bekannte Behälter, der üblicherweise zwischen 20 und 25 bar liegt.

The container according to the invention made of a thermoplastic material, in particular a plastic bottle, comprises:

• a bottom having a first and a second surface area,
• wherein the first and second constant radius surface areas are each at a constant distance from a plane surface perpendicular to the longitudinal axis with respect to the longitudinal axis of the container,
• wherein the first surface area is offset from the second surface area towards the interior of the container,
• wherein the first and second surface areas are joined by a third surface area formed in the form of a continuous loop band and having at least three loops, and
• wherein the transition between the first surface area and the third surface area and / or the transition between the second surface area and the third surface area are continuously differentiable at least once, in particular at least twice; and wherein a loop of the ribbon is transversely described by a spline nth grade, where n is greater than or equal to 2 and less than or equal to seven. Because the transitions to be achieved between the first and the third or the second and the third surface region of the container bottom are continuously differentiable at least once, the container, in particular the bottom, can be manufactured more easily in a blow molding process. In particular, the necessary blowing pressure for producing the container may be less than the required blowing pressure for containers known in the prior art, which is usually between 20 and 25 bar.

Container bottoms known from the prior art often have edge-shaped formations with fillets, that is to say transitions which are continuous, but not continuous, but not at least once, in particular at least twice, continuously differentiable. In order to produce such edge-shaped formations, usually a preform has to be blown in a blow mold around corresponding edges of a blow mold bottom. This usually high blowing pressures are required. In the production of containers according to the invention, the necessary blowing pressure can be reduced on account of the at least once, in particular at least twice, continuously differentiable transitions.

The thermoplastic material may in particular comprise a thermoplastic, for example PET (polyethylene terephthalate). The container can be produced in particular in a blow molding process from a plastic preform by applying compressed air in a blow mold. In addition, a stretching of the preform in the blow mold can be carried out by means of a stretching rod (so-called stretch blow molding method).

As the bottom of the container can be referred to herein in particular the region of the container, which comprises the base or storage area of the container. The bottom may in particular be arranged opposite the mouth of the container.

The container may be formed substantially in the shape of a cylinder. In particular, the container may have concave and / or convex shaped portions, in particular in the region of the mouth and / or the lateral surface of the container. In the region of the mouth of the container, an opening may be provided. The lateral surface may be tapered conically towards the opening.

The bottom of the container may also comprise a lower portion of the lateral surface of the container. In particular, the ratio of the diameter of the container to the height of the lower portion may be 2 to 6. The height of the lower area can be measured perpendicular to a surface on which the container is placed in the intended orientation. The diameter of the container may correspond to the maximum, minimum or average diameter of the container. The diameter of the container may be 30 mm to 170 mm, in particular 40 mm to 150 mm.

In particular, the lower region can have a height of less than or equal to 1/3, 1/4, 1/5 or 1/6 of the container height.

The longitudinal axis of the container may in particular correspond to the axis of symmetry, in particular the rotational symmetry axis, of the container. In other words, the container may be rotationally symmetrical with respect to the longitudinal axis.

The container may in particular be a bottle.

The first, second and / or third surface area may, in particular, face outward. In other words, the first, second and / or third surface area may be arranged on the outer surface of the container.

The flat surface perpendicular to the longitudinal axis may in particular correspond to a surface on which the container, in particular in its intended orientation, is turned off. The flat surface may in particular correspond to a horizontal surface.

The first and the second surface area may each have, in particular in a predetermined radial area, ie between a first predetermined radius and a second predetermined radius, at a constant radius a constant distance to a flat surface, which is arranged perpendicular to the longitudinal axis.

"Offset towards the interior of the container" may mean, in particular, that when the planar surface is a storage surface on which the container is placed standing on the bottom of the container, the first surface area has a greater distance from the storage area in a predetermined radial area as the second surface area.

By "distance" herein can be understood in particular a normal distance.

In a further radial region, in which the first and the second surface region are arranged in particular in the region of a lateral surface of the container, "offset in the direction of the container interior" may also mean that the first surface region has a smaller distance from the longitudinal axis than the second surface region.

In other words, the ground can have at least one constant radius in the circumferential direction several, in particular three or more, elevations and a plurality, in particular three or more depressions, in particular alternately. The elevations and depressions may have a constant distance to a flat surface, which is arranged perpendicular to the longitudinal axis of the container. The elevations and depressions may each be connected to each other by a surface area with a variable distance to the flat surface, wherein the transition between a survey and / or a depression and the surface area with variable distance to the flat surface at least once, in particular at least twice continuously differentiable is.

The term "in the form of a coherent ribbon" may mean herein, in particular, that the third surface area completely surrounds the bottom. At a predetermined azimuthal angle, the third surface area may extend from an inner radius to an outer radius with respect to the longitudinal axis of the container. The inner radius and the outer radius can vary depending on the azimuthal between a minimum inner radius and a maximum outer radius, in particular periodically. The connection of the points on the inner radius can be referred to as the inner boundary line of the loop band. The connection of the points on the outer radius can be referred to as the outer boundary line of the loop band.

The inner or outer boundary line can also be referred to as inner or outer boundary contour.

In this case, the "polar angle" of cylindrical coordinates can be understood as "azimuthal angle", wherein the radial coordinate or the radius of the longitudinal axis or symmetry axis of the container and the height parallel to the longitudinal axis or axis of symmetry of the container can be measured. In other words, in this case, for points on the longitudinal axis or symmetry axis, the radius is 0.

At least three loops can then mean that the minimum inner radius and the maximum outer radius are achieved at least three times.

The loops or loop segments of the ribbon can correspond in particular bays. In other words, the center line of the loop band may be a continuous line that has the same normal distance at each point of the line from both boundary lines of the loop band, and in particular does not intersect itself.

The distance of the center line from the longitudinal axis and / or the sign of the curvature of the center line may vary periodically when circulating around the container. In particular, the centerline may include convex (positive) curvature portions and concave (negative) curvature portions that alternate periodically. The value of the curvature in a portion of convex or concave curvature may be constant or variable.

In particular, "continuously differentiable" means that at the point of transition, a derivative exists and the derivative is continuous. The transition between the first surface area and the third surface area and / or the transition between the second surface area and the third surface area may be continuously differentiable at least once, in particular at least twice, in particular in the circumferential direction.

Once continuously differentiable can also be called "tangent-continuous" and twice continuously differentiable can also be referred to as "curvature continuous".

"In the circumferential direction" may mean in particular at a constant radius or distance from the longitudinal axis along the circumference of the container about the longitudinal axis.

In other words, the derivative can be formed tangentially to a circle of predetermined radius concentric with the longitudinal axis. In particular, the derivative can be formed in a direction perpendicular to the centerline of the loop band at the constant radius. The derivative can be formed in particular along the surface of the soil.

In particular, at least once, in particular at least twice, can mean continuously differentiable that the radius of curvature in the transition region between the first surface region and the third surface region and / or in the transition region between the second surface region and the third surface region continuously varies, in particular has no discontinuities.

In this case, a transition region may be, in particular, a partial region of the third surface region adjacent to the first or second surface region in which the distance to the planar surface approaches the constant value of the first or second surface region, but differs therefrom. In particular, the transition region may have an extent which is ≦ 1/3, in particular ≦ 1/4, in particular ≦ 1/5, the width of a loop in the transverse direction.

The outer surface of the bottom of the container may include or correspond to a free-form surface. A "free-form surface" may be understood herein to mean, in particular, an area that can be described at least in part by means of splines, that is, piecewise polynomial functions. As a result, it is advantageously possible to achieve continuously differentiable transitions at least once, in particular at least twice.

A loop of the ribbon is described in the transverse direction by a spline n th degree. As a result, particularly soft shapes can be realized in the container bottom. As a transverse direction can be referred to here in particular a direction perpendicular to the direction of the loop belt. The running direction of the loop band can run along the center line of the loop band. In particular, the transition from the spline n th degree to the first and / or second surface area at least once, in particular at least twice, be continuously differentiable.

A spline nth degree is a function piecewise composed of polynomials of maximum degree n, where n is an integer greater than or equal to 2, and less than or equal to 7. The degree n may in particular be 2, 3, 5 or 7.

The transition between the first or second surface area and the third surface area may be that, in particular continuous, line or curve at which the first or second surface area merges into the third surface area. The transition from the first to the third surface area may in particular correspond to the inner boundary line or boundary contour of the loop band. The transition from the second to the third surface area may in particular correspond to the outer boundary line or boundary contour of the loop band.

The outer and / or inner boundary line of a loop of the loop band can be described at least in sections by at least one spline n th degree and / or by at least one circular arc.

The transitions between the at least one spline n-th degree and the at least one circular arc may be continuously differentiable at least once, in particular at least twice. As a result, soft transitions can be achieved, whereby the container can be easily formed during manufacture in a blow molding machine as known in the art containers.

The loop band may have at least 3 and at most 24 loops, in particular 3, 5, 6, 7, 8, 10 or 12 loops.

The loop band can be rotationally symmetrical to the longitudinal axis of the container.

The opening angle of a loop may be indirectly proportional to the number of loops of the loop band.

The geometry of a loop of the loop band may be mirror-symmetrical to the bisector of the opening angle of the loop.

In the area of the first and second surface areas, the floor may at least partially have a curvature pointing to the interior of the container. As a result, the stability of the soil can be further increased.

The first surface area can have a first and a second partial area with a curvature pointing to the interior of the container, wherein the curvature of the first partial area differs from the curvature of the second partial area.

The container may be a container for still or pressurized products up to 200,000Pa (2 bar), especially up to 500,000Pa (5bar), internal pressure.

The container may have a filling volume of 100 ml to 5 l, in particular from 250 ml to 2.5 l.

• Konstruieren eines ersten und eines zweiten Oberflächenbereichs,
• wobei der erste und der zweite Oberflächenbereich bei konstantem Radius bezüglich der Längsachse des Behälters jeweils einen konstanten Abstand zu einer ebenen Fläche, die senkrecht zur Längsachse angeordnet ist, aufweisen,
• wobei der erste Oberflächenbereich gegenüber dem zweiten Oberflächenbereich in Richtung des Behälterinneren hin versetzt ist,
• Konstruieren eines dritten Oberflächenbereichs,
• wobei der erste und der zweite Oberflächenbereich durch den dritten Oberflächenbereich verbunden werden, der in Form eines zusammenhängenden Schleifenbandes ausgebildet ist und wenigstens drei Schleifen aufweist, und
• wobei der Übergang zwischen dem ersten Oberflächenbereich und dem dritten Oberflächenbereich und/oder der Übergang zwischen dem zweiten Oberflächenbereich und dem dritten Oberflächenbereich wenigstens einmal, insbesondere wenigstens zweimal, stetig differenzierbar sind; und wobei eine Schleife des Schleifenbandes in Querrichtung durch ein Spline n-ten Grades beschrieben wird, wobei n größer oder gleich 2 und kleiner oder gleich 7 ist. Durch dieses Verfahren kann ein einfach herstellbarer, insbesondere einfach ausformbarer, Boden eines Behälters konstruiert werden.

The invention also provides a method of constructing a bottom of a container from a thermoplastic material, comprising the steps of:

• Constructing a first and a second surface area,
• wherein the first and second constant radius surface areas are each at a constant distance from a plane surface perpendicular to the longitudinal axis with respect to the longitudinal axis of the container,
• wherein the first surface area is offset from the second surface area towards the interior of the container,
• Construct a third surface area,
• wherein the first and second surface regions are joined by the third surface region, which is formed in the form of a continuous loop band and has at least three loops, and
• wherein the transition between the first surface area and the third surface area and / or the transition between the second surface area and the third surface area are continuously differentiable at least once, in particular at least twice; and wherein a loop of the ribbon is transversely described by a spline of the nth degree, where n is greater than or equal to 2 and less than or equal to 7. By this method, a simple producible, in particular easy to shape, bottom of a container can be constructed.

In particular, the method may be used to construct a container as described above, in particular for constructing a bottom of a container as described above. The floor, in particular the first, second and / or third surface area may in particular have one or more of the above-mentioned features.

Constructing the bottom of the container may include constructing a freeform surface.

In particular, constructing the first surface area may include constructing a first surface of revolution from a first contour. The first contour may comprise a circular arc with a first radius of curvature, a second circular arc with a second, in particular different from the first, radius of curvature and an n-th order spline. The transition between the first circular arc and the second circular arc and / or between the second circular arc and the spline can be continuously differentiable at least once, in particular at least twice. The first surface area may correspond to a partial area of the first rotation area.

Constructing the second surface area may include constructing a second surface of revolution from a second contour. The second contour may comprise a circular arc with a first radius of curvature, a second circular arc with a second, in particular different from the first, radius of curvature and an n-th order spline. The transition between the first arc and the second arc and / or between The second circular arc and the spline may be continuously differentiable at least once, in particular at least twice. The second surface area may correspond to a partial area of the second rotational area.

The first radius of curvature of the first contour may be equal to or different from the first radius of curvature of the second contour. The second radius of curvature of the first contour may be equal to or different from the second radius of curvature of the second contour. The spline of the first contour may be of the same order or of different order from the spline of the second contour.

Constructing the third surface region may also include constructing a loop of the ribbon. The constructing of the loop will involve constructing an outer and an inner boundary line of the loop, in particular wherein the inner and / or outer boundary line comprise at least one circular arc and / or at least one n-th order spline.

The invention also provides a container whose bottom has been constructed according to a method as described above.

The container, the bottom of the container and / or the method for constructing the floor may in particular have one or more of the above-mentioned features.

The invention also provides a blow mold comprising a bottom having a first and a second surface area,
wherein the first and the second surface area at constant radius with respect to the longitudinal axis of the blow mold each have a constant distance to a flat surface which is arranged perpendicular to the longitudinal axis,
wherein the first surface area is offset from the second surface area in the direction of the blow mold interior,
wherein the first and second surface areas are joined by a third surface area formed in the form of a continuous loop band and having at least three loops, and
wherein the transition between the first surface area and the third surface area and / or the transition between the second surface area and the third surface area at least once, in particular at least twice, are continuously differentiable; and wherein a loop of the ribbon is transversely described by a spline nth degree, where n is greater than or equal to 2 and equal to or equal to 7.

Blow mold bases known from the prior art often have almost sharp-edged transitions, ie transitions which are not continuously differentiable at least once, in particular at least twice. To blow a preform around such edges usually high blowing pressures are required. In a blow mold according to the invention, the necessary blowing pressure can be reduced due to the at least once, in particular at least twice, continuously differentiable transitions.

The blow mold can be used or used in particular for producing a container mentioned above in a blow molding machine, in particular from a plastic preform. The blow mold, in particular the blow mold bottom, can in particular be designed such that an above-mentioned container can be produced therewith.

The bottom of the blow mold may, in particular, have one or more of the abovementioned features of the bottom of an above-mentioned container. The surface of the bottom of the blow mold can in particular include or correspond to a free-form surface.

• Figuren erläutert. Dabei zeigen:

  Fig. 1A-1C

  eine beispielhafte Draufsicht, Seitenansicht und einen beispielhaften Querschnitt durch einen beispielhaften Boden eines Behälters aus einem thermoplastischen Material;

  Fig. 2A und 2B

  eine Draufsicht und eine Seitenansicht eines beispielhaften Bodens eines beispielhaften Behälters aus einem thermoplastischen Material;

  Fig. 3

  eine Draufsicht auf zwei beispielhafte Böden von zwei beispielhaften Behältern aus einem thermoplastischen Material;

  Fig. 4

  ein Schleifensegment eines Schleifenbandes eines beispielhaften Bodens eines Behälters aus einem thermoplastischen Material;

  Fig. 5

  einen Querschnitt durch einen beispielhaften Boden eines Behälters aus einem thermoplastischen Material;

  Fig. 6

  einen Querschnitt durch einen beispielhaften Boden eines Behälters aus einem thermoplastischen Material;

  Fig. 7

  einen Querschnitt durch einen beispielhaften Boden eines Behälters aus einem thermoplastischen Material;

  Fig. 8

  eine Überlagerung von zwei Querschnitten durch einen beispielhaften Boden eines Behälters aus einem thermoplastischen Material;

  Fig. 9

  eine Projektion eines halben Schleifensegments eines beispielhaften Bodens eines Behälters aus einem thermoplastischen Material;

  Fig. 10

  eine Projektion eines halben Schleifensegments eines weiteren beispielhaften Bodens eines Behälters aus einem thermoplastischen Material;

  Fig. 11

  eine Projektion eines halben Schleifensegments eines weiteren beispielhaften Bodens eines Behälters aus einem thermoplastischen Material;

  Fig. 12

  eine Schleife eines beispielhaften Bodens eines Behälters aus einem thermoplastischen Material;

  Fig. 13

  eine perspektivische Ansicht einer Schleife eines Schleifenbandes eines beispielhaften Bodens eines Behälters aus einem thermoplastischen Material; und

  Fig. 14

  eine Seitenansicht einer Schleife eines Schleifenbandes eines beispielhaften Bodens eines Behälters aus einem thermoplastischen Material.

Other features and advantages of the invention will become apparent from the following examples

• Figures explained. Showing:

  Fig. 1A-1C

  an exemplary plan view, side view and an exemplary cross section through an exemplary bottom of a container made of a thermoplastic material;

  FIGS. 2A and 2B

  a plan view and a side view of an exemplary bottom of an exemplary container made of a thermoplastic material;

  Fig. 3

  a plan view of two exemplary floors of two exemplary containers made of a thermoplastic material;

  Fig. 4

  a loop segment of a loop band of an exemplary bottom of a thermoplastic material container;

  Fig. 5

  a cross-section through an exemplary bottom of a container made of a thermoplastic material;

  Fig. 6

  a cross-section through an exemplary bottom of a container made of a thermoplastic material;

  Fig. 7

  a cross-section through an exemplary bottom of a container made of a thermoplastic material;

  Fig. 8

  a superposition of two cross sections through an exemplary bottom of a container made of a thermoplastic material;

  Fig. 9

  a projection of a half loop segment of an exemplary bottom of a container made of a thermoplastic material;

  Fig. 10

  a projection of a half loop segment of another exemplary bottom of a container made of a thermoplastic material;

  Fig. 11

  a projection of a half loop segment of another exemplary bottom of a container made of a thermoplastic material;

  Fig. 12

  a loop of an exemplary bottom of a container of a thermoplastic material;

  Fig. 13

  a perspective view of a loop of a loop band of an exemplary bottom of a container made of a thermoplastic material; and

  Fig. 14

  a side view of a loop of a loop band of an exemplary bottom of a container made of a thermoplastic material.

Fig. 1A shows a plan view of an exemplary bottom of a container made of a thermoplastic material. The container may in particular be a plastic bottle, for example a PET bottle. The top view in Fig. 1A is in particular a plan view of the outer surface of the underside of the container, ie that side which faces the mouth of the bottle and on which the bottle is usually placed on a shelf, such as a table.

The floor has a first surface area 1 and a second surface area 2. The first and the second surface area 1, 2 have a constant distance R with respect to the longitudinal axis 4 of the container at a constant distance to a flat surface which is perpendicular to the longitudinal axis, for example, the table on which the container is arranged or parked.

The first surface area 1 is offset from the second surface area 2 in the direction of the container interior. In other words, the distance of the first surface area 1 to the storage space for the container at a predetermined radius R is greater as the distance of the second surface area 2 at the same radius R. This may be valid in particular in a predetermined radial area, ie between a first predetermined radius and a second predetermined radius.

In other words, at a predetermined radius, a plurality of elevations and / or indentations may be present along the circumference of the container bottom, in particular alternately.

The first surface area 1 and the second surface area 2 are connected by a third surface area 3. The third surface area 3 is in the form of a continuous loop band, which in this example has five loops.

The third surface area 3 has, compared with the first surface area 1 and / or with respect to the second surface area 2, a different distance from the flat area, which is arranged perpendicular to the longitudinal axis and / or to the longitudinal axis 4 of the container.

In Fig. 1A also a predetermined radial area A is shown, on which the container usually rests on the shelf.

Within the storage area A, the first surface area 1 and the second surface area 2 have a curvature indicative of the container interior.

The curve or the contour profile of the ribbon which separates the first surface area 1 and the second surface area 2 from the third surface area 3 may be referred to herein as the transition between the first and the second surface area 1, 2 and the third surface area 3, respectively. The transition 5 between the second surface region 2 and the third surface region 3 and / or the transition 6 between the first surface region 1 and the third surface region 3 is continuously differentiable at least once, in particular at least twice.

As a result, a particularly smooth transition between the first and the third or the second and the third surface area is achieved, which in turn allows a simple manufacture of the container, in particular at low blowing pressures.

Fig. 1 B shows a side view of the exemplary floor Fig. 1A , It can be seen that the first surface area 1 is offset from the second surface area 2 in the direction of the container interior.

Fig. 1C shows a cross section through part of the exemplary floor Fig. 1 A at a predetermined constant radius R. At the constant radius R, the first surface area 1 and the second surface area 2 each have a constant distance, especially normal distance, to a flat surface E which is perpendicular to the longitudinal axis of the container. However, the distance between the two surface regions to the flat surface E is different, in which case in particular the first surface region 1 is offset relative to the second surface region 2 in the direction of the container interior.

The transition 6 between the first surface region 1 and the third surface region 3 and the transition 5 between the second surface region 2 and the third surface region 3 is continuously differentiable at least once, in particular at least twice.

The portion of the third surface area 3 between the transition 5 and the transition 6 is described by a spline n th degree.

Fig. 2A shows a plan view of another exemplary container bottom made of a thermoplastic material. The continuous loop band of the third surface area 3 has ten loops in this example.

Fig. 2A also shows an injection point 7 for centering the preform in the blow mold of a blow molding machine. In this example, the first surface area at least partially has a curvature pointing to the interior of the container. In the region 1 ', the curvature has a different value than in subregions of the first surface region outside the region 1'.

Fig. 2B shows a side view of the exemplary floor Fig. 2A ,

Fig. 3 shows a plan view of two further exemplary bottoms of containers made of a thermoplastic material. Both floors have the same number of loops. However, the geometry of the loops is different for the two trays. By the loop geometry, the width of the third surface area 3 can be determined.

In addition, the two exemplary floors differ in Fig. 3 through the radial region in which the third surface region 3 is arranged. In the example on the left side of the Fig. 3 The third surface region 3 extends radially from a first to a second predetermined radius and on the right side of the Fig. 3 from a third predetermined radius to a fourth predetermined radius. In this example are both the third and fourth predetermined radii are smaller than the first and second predetermined radii, respectively.

Due to the shape of the continuous loop band of the third surface area 3, the area contents and / or the ratio of the areas of the surface areas 1 and 2 can be varied.

In Fig. 3 In addition, the range of a loop 8 is indicated schematically. The ribbon is in this example rotationally symmetrical to the longitudinal axis of the container, which in this example is perpendicular to the plane of the drawing.

The opening angle of the loop 8 can be chosen in proportion to the number of loops of the loop band. The loop band may comprise 3 to 24 loops. In particular, the opening angle of a loop can be determined according to the expression 360 ° / (number of loops).

The geometry of a loop of the loop band may be mirror-symmetrical to the bisector of the opening angle of the loop.

Fig. 4 shows a perspective view of a portion of an exemplary bottom of a container made of a thermoplastic material, in which a loop segment of the ribbon of the third surface portion 3 is arranged. In the radial direction, the distance to a flat surface, which is arranged perpendicular to the longitudinal axis, vary. At a constant radius with respect to the longitudinal axis, however, points of the first surface region 1 and the second surface region 2 are at a constant distance from a planar surface arranged perpendicular to the longitudinal axis.

It is also in Fig. 4 the centerline of the loop segment is shown as a dashed line.

Fig. 5 illustrates the construction of the second surface area of an exemplary bottom of a thermoplastic material container. In particular, the second surface area may be a partial area of a surface of revolution caused by rotation of the in Fig. 5 shown contour around the longitudinal axis 4 is formed.

This contour is defined by: a first dome radius 9, a radius of curvature 10, a second dome radius 11, the outer contour foot radius 12 and an nth-order spline 13 which forms the transition to the lateral surface of the container.

The transitions of the regions passing through the first dome radius 9, the radius of curvature 10, the second dome radius 11 and the outer contour foot radius 12 may be continuously differentiable at least once. The transition from Außenkonturfußradius 12 to spline 13 may be continuously differentiable at least once, in particular at least twice.

The curvature of the spline 13 is described by an n-th degree polynomial. The degree n of the spline 13 can be 2-7.

Fig. 6 illustrates further parameters for constructing an exemplary bottom of a container, in particular that in FIG Fig. 5 shown contour.

The outer dimensions of the floor are determined by the outer diameter 14 and the ground level 15. The dimension of the stand diameter 16 is determined by a ratio to the outer diameter 14. The circle diameter refers to the diameter at which the bottom of the bottle rests on a flat surface on the flat surface when placed on a level surface. The stander diameter may in particular correspond to the mean or median of the radii in which the bottom of the bottle rests on a flat surface on the flat surface when it is parked.

The ratio of the dimension of the stub diameter 16 to the outer diameter 14 may be between 0.615 and 0.935. The height 17 of the first dome radius 9 and / or the height 18 of the second dome radius 11 can be described by, in particular different, ratios to the outer diameter.

The starting point 23 of the spline 13 can be generated by a straight line between the points 21 and 22. The straight line between 21 and 22 is arranged tangentially at the root radius. The starting point 23 of the spline can be determined by means of an angle on the outer contour root radius 12 between the points 20 and 22. The tangent point of the straight line between 21 and 22 at the root radius can be perpendicular to the center of the outer contour root radius 12.

Fig. 7 illustrates further aspects of a method of constructing a bottom of a container from a thermoplastic material. In particular shows Fig. 7 a contour from which a surface area is formed when rotating about the axis 4, wherein the first surface area in the examples shown above may be a subset of the surface area obtained by rotation of the contour.

The contour in Fig. 7 is described by a first Domradius 9, a radius of curvature 24, a third Domradius 25, a Innenkonturfußradius 26 and a spline 27. The transitions The individual regions can in turn be continuously differentiable at least once, in particular at least twice.

Fig. 8 shows further aspects of a method for constructing a container bottom according to one of the previous examples. In Fig. 8 are the in Fig. 7 shown contour and parts of in Fig. 5 and 6 shown contour shown. The spline 27 is at least once, in particular at least twice, continuously differentiable in the point 31 in a straight line, which is parallel to the outer diameter of the container. The line between points 31 and 32 is parallel to the line between points 21 and 22 in FIG Fig. 6 , The distance between these two straight lines can be defined by measure 28. The curvature of the spline 27 for the in Fig. 7 The contour shown can be described by an n-th degree polynomial.

The distance between the inner contour and the outer contour can be defined via the dimension 29a. The distance between point 34 and point 20 in Fig. 6 can be defined by measure 29b. At points 34 and 20, the tangent to the inner contour or to the outer contour can be perpendicular to the longitudinal axis or parallel to a horizontal surface.

Dimension 29a and dimension 29b may be different. In particular, the dimension 29a may be smaller, equal to or greater than the dimension 29b.

Also, the distance 28 may be different or equal to the distance 29b. In particular, the distance 29b may be smaller, equal to or greater than the distance 28.

By the dimensions 28 and 29b it can be determined how far the first surface area is offset from the second surface area towards the container interior.

The starting point 33 of the spline of the inner contour is generated by a straight line between the points 31 and 32. The straight line between 31 and 32 is tangent to the root radius 26. The starting point 33 can be determined by means of an angle 30 on the root radius 26 between the points 34 and 32. The measure of the root radius 26 can be specified in relation to the root radius of the outer contour 12.

In the Fig. 9-11 Three different loop geometries for the contiguous loop band of the third surface area are illustrated. In particular, aspects of the construction of the loop band are illustrated in these figures.

Since the loops are mirror symmetric to the bisector, are in the Fig. 9-11 only half a loop segment shown.

Fig. 9 shows a first alternative for a loop geometry. The longitudinal axis of the container 4 is shown together with the bisector 35 and a straight line 36 of the opening angle. In other words, the angle 37 between the straight lines 35 and 36 is half the opening angle of the loop.

Point 51 is the next point to the longitudinal axis 4, thus defining the inner boundary of the loop band (minimum inner radius of the loop band). The limitation in the radial direction for the point 51 is greater than or equal to the dimension or the radial extent of the first dome radius 9 in the preceding figures. The maximum point 51 at the stub diameter 16 ( Fig. 6 ) lie.

The point 50, which represents the outer limit of the loop band (maximum outer radius), ie the maximum radius that a point of the third surface area assumes, can be selected between twice the dome radius 9 and the dimension of the outer diameter 14. In other words, the maximum radius that a point of the third surface area assumes may be inside or outside the stand diameter 16.

The distance dimensions 38 and 39 define the width of the loop band along the bisector 35 and along the straight line 36 of the opening angle. The distance dimensions 38 and 39 may be the same or different. In particular, the ratio of the distance measure 38 to the distance measure 39 can be from 0.215 to 3.

The inner boundary line of the loop, that is to say the transition between the first surface area and the third surface area and / or the outer boundary line, that is to say the transition between the second surface area and the third surface area, can be realized at least in sections by at least one spline of the nth degree and / or by at least one circular arc of predetermined radius.

On the bisector 35 midpoints 58 and 59 are arranged with radii 42 and 43.

The basic construction of the inner boundary of the loop is described by midpoints 56 and 58 and by radii 41 and 43.

The point 52 of the inner boundary of the loop is formed by the connection of the center 58 with an auxiliary line 46, which is tangent to the radius 41. The tangent point is the transition point between the radius 41 and the spline 44. The point 54 of the inner boundary of the loop is formed by the connection of the center 56 with a Auxiliary line 49, which is tangent to the radius 43. The tangent point is the transition point between the radius 43 and the spline 44.

The basic construction of the outer boundary of the loop is described by the center 57 and 59 and the radii 42 and 40.

The point 53 on the outer boundary of the loop is formed by the connection of the center 57 with an auxiliary straight line 48 which becomes tangent to the radius 42. The tangent point is the transition point between the radius 42 and the spline 45. The point 55 of the outer boundary of the loop is formed by the connection of the center 59 with an auxiliary line 47 that is tangent to the radius 40. The tangent point is the transition point between the radius 40 and the spline 45.

The inner boundary line of the loop, ie the transition between the first surface area and the third surface area, is thus described by a circular arc with radius 41, a spline n-th degree 44 and a circular arc with radius 43. The transition from the circular arc with radius 41 to spline 44 at point 52 can be continuously differentiable at least once, in particular at least twice. The spline 44 is at point 54 at least once, in particular at least twice, continuously differentiable in the circular arc with radius 43 on.

The curvature of the spline 44 between points 52 and 54 may be described by an nth degree polynomial, where n may be chosen in particular between 2 and 7.

The outer boundary of the loop, that is the transition between the second surface area and the third surface area, is described by a radius 40 arc, a spline 45, and a radius 42 radius arc. The transition from the arc of radius 40 to the spline 45 at point 55 may be continuously differentiable at least once, in particular at least twice. The spline 45 is at point 53 at least once, in particular at least twice, continuously differentiable in the circular arc with radius 42 on.

The curvature of the spline 45 between points 55 and 53 can also be described by an nth degree polynomial, where n is chosen between 2 and 7.

Fig. 10 shows a second alternative for a loop geometry for the contiguous loop band of the third surface area.

Point 67 is the next point to the longitudinal axis 4, thus defining the inner boundary of the loop band. The boundary in the radial direction for the point 67 is greater than or equal to the dimension or radial extent of the first dome radius 9 in the previous figures. The maximum point 67 at the stand diameter 16 ( Fig. 6 ) lie.

The point 76, which represents the outer boundary of the ribbon, ie the maximum radius that a point of the third surface area assumes, can be between twice the dome radius 9 and the dimension of the outer diameter 14. In other words, the maximum radius that a point of the third surface area assumes may be inside or outside the stand diameter 16.

The distance dimensions 61 and 62 define the width of the loop band along the bisector 35 and along the straight line 36 of the opening angle. The distance dimensions 61 and 62 may be the same or different. In particular, the ratio of the distance measure 61 to the distance measure 62 can be from 0.215 to 3.

In Fig. 10 Auxiliary straight lines 65 and 66 are shown, which are perpendicular to the straight line 36 of the opening angle. The end points 67 and 68 of the auxiliary straight lines 65 and 66 lie on the straight line 36 of the opening angle.

In addition, show Fig. 10 two additional auxiliary lines 73 and 74, which are perpendicular to the bisector 35 of the opening angle. The end points 75 and 76 of the auxiliary straight lines 73 and 74 lie on the bisector 35.

The basic construction of the inner boundary of the loop is described by the auxiliary straight lines 65 and 73 and the straight line perpendicular to 36 and perpendicular to 35.

The inner boundary line of the loop is described by the auxiliary line 65, a spline 64 and the auxiliary line 73. The transition from the auxiliary straight line 65 at the point 67 into the spline 64 can be continuously differentiable at least once, in particular at least twice. The spline 64 is at point 75 at least once, in particular at least twice, continuously differentiable in the auxiliary straight line 73 on. Spline 64 between points 67 and 75 can be changed using the straight lines 69 and 61. The dimensions for positioning the support lines 69 and 61 may be different or in relation to each other.

The curvature of the spline 64 between points 67 and 75 may be described by an nth degree polynomial, in particular n of 2 to 7.

The basic construction of the outer boundary line of the loop is described by the auxiliary straight line 66 and the auxiliary straight line 74 as well as by the support straight line perpendicular to 36 and perpendicular to 35.

The outer boundary of the loop is described by the auxiliary straight line 66, a spline 63 and the auxiliary straight 74. The transitions between these elements in points 68 and 76 can be continuously differentiable at least once, in particular at least twice. The shape of the spline 63 can be changed by means of the support straight lines 70 and 72. The dimensions for positioning the support line may be different or in relation to each other.

The curvature of the spline can be described by an nth degree polynomial, in particular with n from 2 to 7.

Fig. 11 shows a further alternative for a loop geometry for the contiguous ribbon of the third surface area.

Point 86 is the next point to the longitudinal axis 4, thus defining the inner boundary of the loop band. The boundary in the radial direction for the point 86 is greater than or equal to the dimension or radial extent of the first dome radius 9 in the previous figures. A maximum of 86 points on the stand diameter 16 ( Fig. 6 ) lie.

The point 93, which represents the outer boundary of the ribbon, ie the maximum radius that a point of the third surface area assumes, can be between twice the dome radius 9 and the dimension of the outer diameter 14. In other words, the maximum radius that a point of the third surface area assumes may be inside or outside the stand diameter 16.

The distance dimensions 78 and 79 define the width of the loop band along the bisector 35 and along the straight line 36 of the opening angle. The distance dimensions 78 and 79 may be the same or different. In particular, the ratio of the distance measure 78 to the distance measure 79 can be from 0.215 to 3.

The inner boundary of the loop contour is defined by the radii 82 and 85. The outer boundary of the loop contour is defined by the radii 83 and 84.

Between the radius 82 and the radius 85, as well as between the radius 83 and the radius 84 results in tangential connections. The tangent points 87 and 91 are transition points for a spline 81 of the inner contour of the loop and tangent points 89 and 90 are transition points for the spline 80 of the outer contour of the loop.

The inner contour of the loop is described by an arc of radius 82, a spline 81 and a radius 85 arc. The transitions between these elements can be continuously differentiable at least once, in particular at least twice. The radii 82 and 85 may be in relation to each other. The curvature of the spline 81 can again be described by an nth degree polynomial, in particular with n from 2 to 7.

The position of the centers of the radii may be the same or different, in particular in a relationship to each other.

However, the radii 82 and 85 as well as the distances 78 and 79 may also be in a relationship to one another.

The outer contour of the loop is described by a circular arc with radius 83, a spline 80 and a circular arc with radius 84. The transition between these elements can be continuously differentiable at least once, in particular at least twice.

The radii 83 and 84 may be in relation to each other. The curvature of the spline 80 can again be described by an nth degree polynomial, in particular n of 2 to 7.

The position of the centers of the radii may be the same or different, in particular in a relationship to each other.

However, the radii 83 and 84 and the distances 78 and 79 may also be in a relationship to one another.

Fig. 12 shows a perspective view of a portion of a bottom of an exemplary container, wherein the part comprises a loop of the loop band. The first surface region 1 merges into the third surface region 3 in the region of the inner contour of the loop, and the third surface region 3 merges into the second surface region 2 at the outer contour of the loop.

In the construction of the soil, cutting curves are produced on the first surface area 1 and the second surface area 2 by means of auxiliary surfaces. Endpoints 102-115 of the cut curves are connected to splines 95-101. The transitions of splines 95-101 in the end points 102-115, at least once, in particular at least twice, are continuously differentiable.

The splines 95-101 have a curvature curve which is described by an nth-degree polynomial, in particular where n is greater than or equal to 2 and less than or equal to 7.

By means of the inner and outer boundary contour of the loop and the splines 95 - 101, a freeform surface corresponding to the third surface region 3 can be constructed. The curvature course in u and v direction of the free-form surface of the loop band can be described by polynomials of the nth degree.

The angle segment can then be multiplied by the number of loops that has been previously defined around the axis of rotation. As a result, the construction of the loop band can be completed.

Fig. 13 shows another perspective view of the part of the exemplary bottom of a container made of a thermoplastic material, which in Fig. 12 is shown. FIG. 14 shows a corresponding side view.

It is understood that in the embodiments described above mentioned features are not limited to these specific combinations and are also possible in any other combinations. The preceding examples can be applied analogously to bottoms of blow molds and their construction instead of container bottoms.

Claims (14)

1. Container of a thermoplastic material, in particular a plastic bottle, comprising:

   a bottom comprising a first and a second surface area (1; 2),

   wherein the first and the second surface area (1; 2), at a constant radius with respect to the longitudinal axis of the container, each have a constant distance to a plane surface (E) arranged to be perpendicular to the longitudinal axis,

   wherein the first surface area (1) is offset with respect to the second surface area (2) towards the interior of the container,

   wherein the first and the second surface area (1; 2) are connected by a third surface area (3) which is embodied in the form of a coherent loop band and comprises at least three loops,

   wherein the transition (6) between the first surface area (1) and the third surface area (3),

   and/or the transition (5) between the second surface area (2) and the third surface area (3) is continuously differentiable at least once, in particular at least twice; and

   characterized in that

   a loop of the loop band is described in the transverse direction by a spline of the n-th degree (95 - 101), wherein n is greater or equal 2 and smaller or equal 7.
2. Container according to claim 1, wherein an outer and/or an inner boundary line of a loop of the loop band are described at least in sections by at least one spline of the n-th degree (44; 45) and/or by at least one arc of a circle.
3. Container according to claim 2, wherein the transitions between the at least one spline of the n-th degree and the at least one arc of a circle are continuously differentiable at least once, in particular at least twice.
4. Container according to one of the preceding claims, wherein the loop band comprises at least 3 and at most 24 loops, in particular 3, 5, 6, 7, 8, 10 or 12 loops.
5. Container according to one of the preceding claims, wherein the loop band is rotationally symmetric to the longitudinal axis of the container.
6. Container according to one of the preceding claims, wherein the opening angle of a loop is indirectly proportional to the number of loops of the loop band.
7. Container according to one of the preceding claims, wherein the geometry of a loop of the loop band is mirror-symmetrical to the bisector (35) of the opening angle of the loop.
8. Container according to one of the preceding claims, wherein the bottom at least partially comprises, in the region of the first and the second surface area, a curvature facing the interior of the container.
9. Container according to claim 8, wherein the first surface area comprises a first and a second partial area with a curvature facing to the interior of the container, wherein the curvature of the first partial area differs from the curvature of the second partial area.
10. Container according to one of the preceding claims, wherein the container is a container for still or slightly pressurized products up to an internal pressure of 500 000 Pa (5 bar).
11. Container according to one of the preceding claims, wherein the container comprises a filling volume of 100 ml to 5 l.
12. Method of designing a bottom of a container of a thermoplastic material, comprising the steps of:

    designing a first and a second surface area (1; 2),

    wherein the first and the second surface area (1; 2), at a constant radius with respect to the longitudinal axis of the container, each have a constant distance to a plane surface (E) arranged to be perpendicular to the longitudinal axis,

    wherein the first surface area (1) is offset with respect to the second surface area (2) towards the interior of the container,

    designing a third surface area (3),

    wherein the first and the second surface area (1; 2) are connected by the third surface area (3) which is embodied in the form of a coherent loop band and comprises at least three loops,

    wherein the transition (6) between the first surface area (1) and the third surface area (3) and/or the transition (5) between the second surface area (2) and the third surface area (3) is continuously differentiable at least once, in particular at least twice; and

    wherein a loop of the loop band is described in the transverse direction by a spline of the n-th degree (95 - 1001), wherein n is greater or equal 2 and smaller or equal 7.
13. Container, in particular according to one of claims 1 - 11, whose bottom was designed according to a method according to claim 12.
14. Blow mold comprising:

    a bottom comprising a first and a second surface area,

    wherein the first and the second surface area, at a constant radius with respect to the longitudinal axis of the blow mold, each have a constant distance to a plane surface arranged to be perpendicular to the longitudinal axis,

    wherein the first surface area is offset with respect to the second surface area towards the interior of the blow mold,

    wherein the first and the second surface area are connected by a third surface area which is embodied in the form of a coherent loop band and comprises at least three loops,

    wherein the transition between the first surface area and the third surface area, and/or the transition between the second surface area and the third surface area are continuously differentiable at least once, in particular at least twice; and

    a loop of the loop band is described in the transverse direction by a spline of the n-th degree (95 - 101), wherein n is greater or equal 2 and smaller or equal 7.

Images