GB2142611A - Method and apparatus for filling a toothpaste tube - Google Patents

Abstract

A method for filling a tube with a main body of extrudable material such as toothpaste and dissimilar extrudable material as a plurality of longitudinal stripes which appear on the main body when the materials are first dispensed from the tube is effected by forming the main body of material into an annular flow, dividing the annular flow into spaced segments and interposing therebetween discrete streams of the striping material, combining the streams and filling the tube progressively from one end to the other. The apparatus for carrying out the above method comprises an outer tube, insertable within the tube to be filled, and an inner tube 2 forming an annular passage which is divided into spaced annular segments 16 by walls 6a, 6b which form channels 8 for the striping material. The end of the inner tube is closed by end plate 15. This arrangement ensures that the toothpaste tube is filled (Fig. 5) so that the material dispensed from the tube is striped immediately. <IMAGE>

Description

SPECIFICATION Method and apparatus for filling tubes This invention relates to the filling of tubes such as collapsible tubes with two or more dissimilar extrudable materials such as toothpaste, gel shampoo and food products like mayonnaise or cream, arranged so that a main body of material is dispensed from the tube with longitudinal stripes of a dissimilar material or materials.

An extrudable material is any type of paste or the like having an adequately structured rheology and particularly a sufficient viscosity to enable it to be extruded into a tube, stored and dispensed from the tube without undue distortion of the desired pattern of the stripes in the paste as it is dispensed from the tube. The term "dissimilar" includes any difference of colour or composition.

It is well known (BP813 514) to form a pattern of stripes on a main body material, eg a white toothpaste, as it is dispensed from a collapsible tube by providing within the tube adjacent the outlet a separate reservoir of a striping material, eg a red toothpaste, the red toothpaste passing through striping apertures in the reservoir onto the white toothpaste as it is dispensed from the tube. In this way well defined stripes can be produced and the proporation of striping material can be as low as 4% of the total volume of material in the tube but has the disadvantage that as well as the cost of providing the reservoir for the striping material the striping material and the main body material are usually filled separately into the tube which complicates the filling operation.

It is also known (BP 962 757) to fill tubes with toothpaste of two different colours through a filling nozzle in which the striping paste is applied to the main body of paste as it leaves the outlet orifice of the filling nozzle. As previously proposed the main body of toothpaste issues from the nozzle as a solid plug of material having radially directed longitudinal grooves in its periphery into which grooves the striping paste is extruded. This method of filling can be satisfactory when the amount of striping paste, divided into five stripes, is about 20% or above of the total volume of paste in the tube.When the volume of the striping paste is below this level a disadvantage which arises is that when the tube is filled in the usual way starting with the cap end of the tube the initial 1 to 3 cm of the paste squeezed from the tube by the user comprises main body paste only and does not have a striped pattern thereon. Furthermore since the stripes as they issue from the outlet of the tube extend some way into the main body of toothpaste quite large quantities of striping paste are required for the stripes to remain visible to the user.

According to the present invention there is provided a method of filling a tube with a main body of extrudable material and a plurality of longitudinal stripes of dissimilar extrudable material exteriorly of the main body comprising passing a stream of each of the materials through discrete passages in a filling nozzle inserted within the tube, forming one of the streams of material into an annular stream, dividing that annular stream into a plurality of spaced segments of an annulus and interposing only in the spaces between the segments discrete streams of other material, combining said streams together and filling the tube with the combined streams of material progressively from one end to the other as the filling nozzle is withdrawn from the tube.As the streams of material first combine they form an annular flow comprising alternate segments of the divided annular stream and the interposed material with no material at the centre of the stream.

Depending upon the viscosities of the materials the materials converge and meet to form a solid plug beyond the plane in which they combine. By filling a tube in this way the striping material is found to be so arranged in the tube that even when the volume of the striping material in any one stripe is less than 4% of the total volume of the tube the stripes appear together with the main body of material even when the contents are first dispensed. Furthermore at these relatively low levels of striping material stripes of contrasting colour to the main material are clearly defined and can be readily seen. Thus the volume of striping material can be reduced below that previously possible without the use of a separate reservoir within the tube for the striping material.

When the striping material contains a relatively expensive component, eg a dye, colour, pigment or flavour, which it is desired to incorporate within a small volume of material this is obviously an advantage.

Preferably the annular stream comprises the main body material and the striping material is interposed between the segments of the divided annular stream.

Conveniently the volume of any one of the stripes can be between 1% and 3% and preferably 2% to 3% of the total volume of the tube at which level the stripes are still sharp and well defined.

The combined streams of material are preferably constrained to flow in a convergent path before leaving the filling nozzle and beginning to fill the tube. This permits the end of the nozzle to be inwardly tapered at its open end to facilitate insertion into the tube to be filled.

When the tube is filled the combined flow of material can be severed by an air blast or a vacuum applied to the material in the nozzle to cause it to 'suck-back' to provide a clean cut-off facilitating both the closing of the end of the filled tube and an accurate start to the filling of the subsequent tube.

The air blast can conveniently issue centrally of the annular flow path where the streams of material combine.

According to another aspect of the present invention there is provided a nozzle assembly for filling a tube with a main body of extrudable material having a plurality of peripheral longitudinal stripes of dissimilar striping material comprising an outer tube adapted to be inserted within the tube to be filled and an inner tube coaxial with the outer tube to form an annular passage therebetween, an outlet nozzle at one end thereof having hollow flow dividers in the annular passage which divide the annular passage into a plurality of spaced annular segments, outlets from the hollow dividers being interposed between each of said segments, ports in the inner tube communicating the inner tube with the interior of the hollow flow dividers, and an end plate closing the end of the inner tube in the plane of the hollow flow divider outlets.Thus material passing through the annular passage is subdivided into a plurality of spaced annular segments by the flow dividers and material passing through the inner tube enters the hollow dividers through the ports and leaves by the outlets interposed between the annular segments.

The materials from the annular passage and the inner tube combine in the plane of the end plate after passing the flow dividers, and form an annularflow which becomes a solid plug beyond the end plate at a distance depending upon the viscosities of the materials.

One of the inner tube or annular passage can be sub-divided to form two or more discrete passages so that a main body of material can be provided with stripes of two or more materials dissimilarto each other and to the main body material.

The main body of material can flow through either the inner tube or the annular passage but preferably flows through the annular passage. The end plate can be adapted to restrict the size of the outlets from the hollow flow dividers so that striping material emerges only adjacent the outer tube.

A conical nose extension can be provided on the outer tube of the filling nozzle extending from the plane of the end plate to facilitate entering the nozzle into tubes to be filled.

The invention will now be more particularly described with reference to the accompanying diagrammatic drawings in which Figure 1 is a partly cut away perspective view of a filling nozzle assembly not in accordance with the invention; Figure 2 is a sectional elevation of a tube filled by the nozzle of Figure 1; Figure 3 is a photograph of material dispensed from the tube of Figure 2; Figure 4 is a perspective view similar two Figure 1 showing an assembly according to the invention; Figure 5 is a view similar to Figure 2 showing a tube filled by the nozzle of Figure 4; Figures 6and 7 are photographs of material dispensed from the tube of Figure 4; Figure 8 is a sectional side elevation of a preferred nozzle filling assembly; and Figure 9 is view in the direction of arrows IX-IX in Figure 8.

Referring to Figure 1 there is shown the outlet end of a filling nozzle comprising an outer tube 1 and a coaxial inner tube 2 to form an annular passage 3 therebetween. Adjacent the end of the nozzle the annular passage is partly closed by segmental annular plates 4 leaving gaps 5 which connect with longitudinal channels 6 defined between side walls 6a, 6b and secured to and closed by the inner surface 7 of the outer tube 1. The inner tube terminates in the plane of the plates 4.

The inner tube 2 is adapted to be connected two a source of main body material and the annular passage 3 is adapted to be connected to a dissimilar striping material. In use the main body material passes through the inner tube 2 and after passing beyond the plane of the segmented plates 4the main body material fills the outer tube with the exception of that space occupied by the channels 6. Striping material passes through the annular passage 3 and the channels 6 to emerge from the channel outlets and combine with the solid plug of main body material emerging from the outer tube.

When such a nozzle is used to fill a tube the nozzle is inserted into the tube before filling begins and then progressively withdrawn as material leaves the nozzle and fills the tube. Collapsible tubes such as toothpaste tubes are provided with their caps and filled through the opposite end which is thereafter sealed.

Figure 2 shows a longitudinal cross-section through such a tube after having been filled with the nozzle of Figure 1. As can be seen the main body material 9 begins to fill the neck 10 of the tube which is provided with an external thread 11 to receive a cap (not shown for clarity). The striping material 12 extends only along the interior of the tube walls 12 and does not extend across the shoulder 14 or into the neck 10 of the tube. Thus when the tube is first used a quantity of main body material will be dispensed from the tube without any striping material, some 1 cm to 3 cm depending upon the relative proportions of the tube and its neck and only thereafter will striping material be dispensed together with the main body material.

The photograph of Figure 3 shows material extruded from a tube filled as shown in Figure 2 and it is clearly apparent at the left hand side that the striping material is not present for some distance.

The striping material in this example was 15% of the total volume and divided into four stripes.

Referring now to Figure 4 there is shown a nozzle assembly similar to that of Figure 1 but in which an end plate 15 is provided at the plane of the channel outlets 8 so that the nozzle outlet comprises alternate channel outlets 8 of the channels 6 and outlets 16 from the inner tube 2.

The inner tube and annular passage are connected in use to sources of main body material 9 and striping material 12 respectively as before. Again as before the annular passage 3 is divided by the plates 4 into four spaced segmental annular passages formed by the channels 6. Each end plate 4 and the respective walls 6a, 6b of adjacent channels 6 form a hollow divider having ports 17 defined bythe innermost edges of the walls 6a, 6b the outer edge of the end plate 15 and the inner edge of plates 4. Thus the interior of the hollow dividers are connected by the ports 17 to the inner tube, the outlets 16 being the outlets from the hollow dividers.

In use the striping material passes in an annular stream through the annular passage 3 and is subdivided into spaced segments of an annulus by the hollow dividers. The main body material passes through the inner tube and ports 17 into the hollow dividers and is interposed in the spaces between the annular segments of striping material.

Immediately after leaving the nozzle, ie at the plane of the end plate 15, the flow of material is substantially without material issuing from the nozzle at the centre because of the presence of the end plate 15.

At a distance from the end plate 15 determined primarily by the viscosities of the materials the materials conbine to form a solid plug and Figure 5 shows a tube filled using the nozzle of Figure 4 in the same way as before. It will be seen that the striping material 12 extends from the tube walls across the shoulder 14 and into the neck of the tube with the result that when the contents of the tube are first dispensed by the user the striping effect is immediately apparent on the main body of material. This can be clearly seen in the photograph of Figure 6 which shows a ribbon of material dispensed from the tube of Figure 5 and the striping effect at the left hand end of the ribbon first dispensed from the tube is present from the very beginning. Again the striping material is 15% of the total volume divided into four stripes.

Figure 7 is a photograph of a further example of material dispensed from a tube filled with a nozzle as shown in Figure 5 in which the striping material comprises only 6% of the total volume of material in the tube. Again it can be seen on the left hand end of the ribbon first dispensed from the tube that the striping is present from the beginning and that the striping effect is clear and well defined along the ribbon even when each of the stripes are only 1.5% by volume of the material dispensed.

It will be appreciated that in the embodiment of Figure 4 the width and depth of the channels 6 can be varied to produce different sizes of stripes on the main body material. Furthermore the width of the channels 6 can be increased so that the outlets 8 therefrom are of larger area than the outlets 16 and the main body material passed through the annular passage whilst the striping material is passed through the inner tube and out of the outlets 16.

Figures 8 and 9 show a preferred form of nozzle assembly according to the invention having an outer tube 1 and coaxial inner tube 2 with an annular passage 3 therebetween. The tubes 1 and 2 are mounted at one end in a supply block 18 having a feed pipe 19 connecting with the annular passage and a feed pipe 20 connecting with the inner tube 2.

On the other end of the tube 2 are five hollow dividers 21 equally spaced around the tube and communicating with the inner tube via ports 17. The open ends of the dividers form outlet openings 16.

End plate 15 blanks off the end of the inner tube 2 and also part of the open ends of the hollow dividers to reduce the size of the outlets 16.

As shown in Figure 8 the outer tube is releasably joined at 22 for manufacturing and servicing reasons and beyond the end plate 15 is formed with a conical extension 23 to facilitate insertion of the nozzle into the container to be filled.

A main body material is supplied by pipe 19 to the annular passage 3 along which it flows before being subdivided into spaced segments of an annulus by the hollow dividers 21 and emerging through outlets 8. Striping material is supplied by pipe 20 along the inner tube and passes through ports 17 into the hollow dividers 21, and thus interposed between the segments of the annular flow, and out of the divider outlets 16. The flows from the outlets 8 and 16 combine after passing the end plate 15.

Nozzle assemblies as shown in Figures 4,8 and 9 have been used to fill collapsible tubes with the toothpaste materials and have been found suitable to provide stripes each having a volume of 1% or more of the total volume of toothpaste filled into the tube, the stripes being sharp and well defined when the paste is subsequently dispensed from the tube by the user even when the stripe volume is as low as 1%. Whilst the invention is particularly useful for filling tubes with toothpaste it is equally suitable for filling containers with any other adequately structured extrudable materials.

When a tube has been filled severing of the flow of material from the nozzle can be assisted as is well known by applying suction to material in the nozzle.

Alternatively the blanking of the inner tube 2 by the end plate 15 can provide a suitable central location for a supply of air under pressure to assist such severing and in the embodiment of Figures 8 and 9 the air blast can issue from a plunger the end of which is movable between the end plate 15 and the open end of the conical extension 23.

Claims (12)

1. A method of filling a tube with a main body of extrudable material and a plurality of longitudinal stripes of dissimilar extrudable material exteriorly of the main body comprising passing a stream of each of the materials through discrete passages in a filling nozzle inserted within the tube, forming one of the streams of material into an annular stream, dividing that annular stream into a plurality of spaced segments of an annulus and interposing only in the spaces between the segments discrete streams of other material, combining said streams together and filling the tube with the combined streams of material progressively from one end to the other as the filling nozzle is withdrawn from the tube.

2. A method according to Claim 1 in which the annular stream comprises the main body material and the striping material is interposed between the segments of the divided annular stream.

3. A method of filling a tube according to Claim 1 in which the volume of the striping material in any one stripe is less than 4% of the total volume of the tube.

4. A method of filling a tube according to Claim 2 in which the volume of the striping material is between 1% and 3% of the total volume of the tube.

5. A method according to any of the preceding claims in which the combined streams of material are constrained to flow in a converging path before beginning to fill the tube.

6. A method according to any one of the preceding claims in which the combined flow of material is severed by an air blast when a tube is filled.

7. A method according to Claim 5 in which the air blast issues centrally of the annular flow path where the streams combine.

8. A method according to any one of the preceding claims in which the plurality of stripes are each of the same material.

9. A nozzle assembly for filling a tube with a main body of extrudable material having a plurality of peripheral longitudinal stripes of dissimilar striping material comprising an outer tube adapted to be inserted within the tube to be filled and an inner tube coaxial with the outer tube to form an annular passaage therebetween, an outlet nozzle at one end thereof having hollow flow dividers in the annular passage which divide the annular passage into a plurality of spaced annular segments, outlets from the hollow dividers being interposed between each of said segments, ports in the inner tube communicating the inner tube with the interior of the hollow flow dividers, and an end plate closing the end of the inner tube in the plane of the hollow flow divider outlets.

10. A nozzle assembly according to Claim 9 in which one of the inner tube or annular passage is subdivided to form two or more discrete passages.

11. A nozzle assembly according to Claim 9 or Claim 10 in which the end plate is adapted to restrict the size of the outlets from the hollow flow dividers, the outlets being disposed adjacent the outer tube.

12. A nozzle assembly according to any of Claims 9 to 11 having a conical nose extension on the outer tube extending from the plane of the end plate.