Device for opening a tubular bag and its application

Abstract

Device for opening a tubular bag with a blade attached to an inserting tube, wherein the blade is equipped with at least one edge for lancing the tubular bag and with at least one edge for cutting the tubular bag and the shape of the blade is aligned to the inner wall of the outlet for the material contained in the bag.

Description

The invention concerns a device for the opening of a tubular bag and also for its application.

BACKGROUND OF THE INVENTION

In the dental field, particularly, pastes of varying consistencies are offered in tubular bags with increasing frequency. In doing so it is necessary to guarantee a simple, clean and safe application for the consumer.

For this purpose the tubular bags are combined with opening mechanisms as have been described already in EP 787 655 (=U.S. Pat. No. 6,012,610), EP 1 121 195 (=U.S. Pat. No. 6.394.643), EP 1 227 049 (=US 2002/0113089). However, the known mechanisms have certain disadvantages depending on the consistency of the products in these tubular bags.

EP 787 655 describes a device, wherein the bag stretches out under pressure beyond its original shape, before it bursts due to a device arranged behind the top plate. The disadvantage of this system, particularly in the case of multi-component paste systems, is that a paste can be held back temporarily until this bag bursts open under partly high pressure and the paste, particularly in the case of freely flowing pastes, spills over, until the pressure is counter-balanced. Thus this leads to fluctuating mixing ratios, before and after opening both the components as well.

In the case of pastes with high viscosity and poor ability to flow freely, a slit-formed bottle opening (A) as mentioned in EP 1 227 049, leads to a high pressure buildup in the bag.

The device described in it creates an opening that is bigger than just a slit. However, in the application of pastes with very high viscosity and very poor ability to flow freely, the blade 1 (of FIG. 3) attached to the flow channel causes a disturbed flow resistance in the case of this enlarged bottle opening.

The task of the invention is to offer a system for tubular bags that is comfortable for the user, guarantees an even discharge flow from the beginning and also causes as little flow resistance as possible even in the case of products with high consistency and high viscosity.

SUMMARY OF THE INVENTION

The task is solved by a device with a blade that is attached to an inserting tube, wherein the switchblade is fitted to the inner wall of the outlet for the material contained in the bag for lancing and cutting the tubular bag. That is, the shape of the blade follows the wall of the opening and/or represents the wall of the opening. If the outlet is cylindrical, then the blade is preferentially curved such that it conforms to the shape of a cylinder. The invention particularly concerns a device for opening a tubular bag with

• • A) an inserting tube with an opening (D) facing the tubular bag at one end and an outlet at the other end connected to it by means of a flow channel for the pasty material contained in the tubular bag.
  • B) a blade attached to the inserting tube.
  • C) wherein the blade is equipped for lancing the tubular bag with at least one pointed tip facing the tubular bag and at least one edge connected to the pointed tip for cutting the tubular bag, characterized by the fact that
  • D) the shape of the blade follows the inner wall of the outlet for the material contained in the tubular bag.

In a convenient design form one or several bars connected to a toothed wheel in the channel prevent the twisting of the tube when the bag is being pierced or is pierced.

DETAILED DESCRIPTION

It proves to be advantageous that the inserting tube and the blade are made of different materials, namely, the tube is made of a sealing material and the blade is made of a sturdy material. Furthermore, it is advantageous if the blade has at least two pointed tips that are connected by a slanting or bent cutting edge. The blade preferentially creates a non-linear opening in the foil of the tubular bag by which the resistance for viscous pastes can be kept low.

The blade preferentially has at least two pointed tips that are connected by a cutting edge. In order to guarantee the optimal functioning of the blade, it is necessary to design the blade such that it is very pointed, sharp-edged and stiff, as would be possible using steel or ceramics for instance.

It is possible to design the blade and opening tube out of one unit (combination component). Since the side of the opening tube facing away from the blade must be essentially more flexible and softer in order to be easily attachable and again removable as a plug connection to the mixer, and also in order to have a caulking effect, the ‘combination component’ should be manufactured out of at least two different materials. The piercing tubes described in EP 1 121 195 do not exhibit material combinations of stiff pointed tip and elastic sealing edge or even their faultless functioning.

Preferred materials for the sealing component are thermoplastic materials like polypropylene or polyethylene and the preferred materials for the cutting blade are stainless steel, spring steel, light metal, ceramics or thermoplastic with a high elastic modulus, approximately >=3000 MPa.

In order to be applicable also for very viscous, resistant pastes, the opening pricked into the foil should be as large as possible, the flow channel should be designed with the largest possible cross-section area and its surface touching the product should be as small as possible for reduction in friction.

Since normally the length and the height of the flow channel are predetermined by the necessary compatibility to the existing systems, the required characteristics are guaranteed above all by the shape and seat of the opening blade.

Since the blade is designed such that it is an integral part of the flow channel wall, and also causes an end-to-end incision that is not linear in the foil, the frictional resistance (viscous drag) of the pastes drops conspicuously. This represents an appropriate advantage as opposed to the blades that are arranged such that they obstruct the flow of the product.

The cut foil piece is furthermore conveniently connected to the bag and is placed at the wall of the outlet channel by the product flow.

The cut surface can be L-, V-, or U-shaped, or semicircular to almost circular. The smallest press-out strength while simultaneously avoiding the foil parts from getting into the product—when the bag is opened—can be achieved if the incision is ¾-circular.

Through this the press-out strength of a paste (viscosity of approximately 500 Pa s) drops from 4000-5000 N to approximately 2000 N with a linear slit and the blade arranged in the flow channel.

The structural design of the blade has proved to be optimal if the blade has at least two pointed tips for piercing the foil that are connected by the slanting and/or curved blade edge.

In order to avoid an unchecked tear propagation of the foil, both the pointed tips of the blade must be advantageously designed

• at the end of the cutting edge
• at the side away from the cutting edge
• with an angle of at least 180° to the piercing direction.

The pointed tip should not exceed an angle of 45° in order to function efficiently.

It is functionally convenient to maintain the wall thickness of the cutting edge below 0.5 mm.

An anti-twist device is necessary to avoid the blade from getting twisted when or after the bag is pierced. This is ensured when at least one or several bars are affixed to the tube that engage a toothed wheel affixed to the bottle cap in the channel if the tube is inserted. Conversely, the toothed wheel can even be arranged in the tube and the bar/s can be arranged in the channel. In the absence of an anti-twist device, in certain circumstances in the pierced state, a part of the bag foil can be separated by a rotary motion of the tube.

For products with extremely high consistencies (kneadable) it is necessary that the bag is opened by the outlet channel to the maximum possible cross-section diameter by slitting and piercing the bag, expanding the hole and even punching out the foil. However if this is carried out by the user by means of a separate tool, the desired convenience of the system is lost. In addition, the foil parts can get into the product.

The opening function can also be coupled with a closing function, so that a device is developed for the opening and resealing of a tubular bag with a blade affixed to a plug and a sealing element. In doing so the plug and the blade are preferentially made of different materials, namely, the plug is made of a sealing material and the blade is made of a sturdy material.

It has proved to be practicable to insert the plug in an open position during the manufacturing process in the outlet channel that acts as an opening mechanism and also as a plug for the storage time and transport. The end user must then simply remove the plug and then has a product that is open and ready for use.

However, because the part for lancing the bag must always be pointed, sharp and stiff, the risk of injury by the pointed plug can be avoided if the bag is pierced during the manufacturing process and subsequently sealed with a plug without a pointed tip, which then can be pulled off and can be disposed of safely by the user. This would shift the application of the device according to the invention at hand completely to the manufacturer's side.

In this respect the invention concerns also the production and application of preopened and resealed tubular bags wherein the foil of the bag in the area of the outlet channel is pierced before delivery and resealed with a sealing plug until application, as well as preopened tubular bags of such a type wherein the foil piece is punched out and removed before the sealing plug is inserted.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained more closely with the figures:

FIGS. 1 and 2 illustrate the tubular bag and the opening device before and after piercing.

FIG. 3 illustrates a device of the state of art technology with a switchblade with a straight and pointed blade 1.

FIG. 4 illustrates the solution according to the invention at hand with a blade 2 based on a cylindrical shape (top view 10, three quarters of a circle) and two pointed tips 12, and two bars (21) at the tube that provide twist protection.

FIG. 5 illustrates the detailed top, front and side view of a blade with 2 pointed tips (12).

FIG. 6 illustrates the detailed top, front and side view of a blade with 3 pointed tips (12).

FIG. 7 illustrates a preopened tubular bag with a closure part (core plug) (19) consisting of blade (20) and plug (23).

FIG. 8 illustrates a solution without switchblade and with preopened bag (C) and sealing plug (24).

FIG. 9 illustrates the detailed side view of a toothed wheel (25) affixed to the channel that functions as twist protection.

FIG. 10 illustrates the top view of the channel with the toothed wheel (25).

FIG. 11 illustrates the tubular bag after lancing, wherein the bars (21) engage the toothed wheel (25) in order to prevent twisting.

In FIG. 1 (unopened state) a safety spacer can be seen as attribute 26 that is arranged between the edge of the channel 3 and the broader part of the inserting tube 8 for preventing the unintended opening of the device.

The blade 2, 6 in (FIG. 4, 5, 6) is introduced through the channel 3 (FIG. 2) and is then arranged opposed to EP 787 655 conspicuously in front of the level 4 of the top plate 5.

In order to guarantee the optimal function of this blade 2, 6 it is necessary to design it such that it is very pointed, sharp-edged and stiff as is possible for example with steel or ceramics.

Since the other side 8 of this opening tube (7,8, FIG. 4) however must be essentially more elastic and softer, in order to be easily attachable and again removable as plug-in connection to the mixer and also have a caulking effect, each tube 7, 8 must be manufactured out of at least two different materials. The piercing tubes described in EP 1 121 195 do not exhibit material combinations of stiff pointed tip and elastic sealing edge or even their faultless functioning.

Preferred material for the part 7, 8 are thermoplastic materials like polypropylene or polyethylene and the preferred materials for the part 2, 6 are stainless steel, spring steel, light metal, ceramics or thermoplastic with high elastic modulus.

In order to be applicable also for very viscous, resistant pastes, the opening B that is pricked into the foil should be as large as possible, the flow channel must be designed with a cross-section area that is as large as possible and its surface touching the product should be as small as possible for friction reduction.

Since normally the length and the height of the flow channel are predetermined by the necessary compatibility to the existing systems, the required characteristics are guaranteed above all by the shape and seat of the opening blade.

Since the blade is designed such that it is an integral part of the flow channel wall 9, and also causes an end-to-end incision that is not linear in the foil, the frictional resistance (viscous drag) of the pastes drops considerably. This represents an appropriate advantage as opposed to the blades that are arranged such that they obstruct the flow of the product. (FIG. 3).

The cut surface can be L-, V-, or U-shaped or semicircular to almost circular (FIG. 4, B, 10).

The smallest press-out strength while simultaneously avoiding the foil parts from getting into the product of an opened bag of such type can be achieved if the incision B is ¾-semicircular 10.

Through this the press-out strength of a paste (viscosity of approximately 500 Pa s) drops from 4000-5000 N to approximately 2000 N with a linear slit and the blade 1 arranged in the flow channel 11 (FIG. 3)

The structural design of the blade has proved to be optimal if the blade has at least two pointed tips 12, 13 for piercing the foil that are connected to each other by the slanting and/or bent blade edge 14.

In order to avoid an unchecked tear propagation of the foil 15 (FIG. 2), both the pointed tips 12 must be designed at the end of the cutting edge 14 at the side 16 facing away from the cutting edge with an angle 17 of at least 180° to the piercing direction. The pointed tip 12, 13 should not exceed an angle 18 of 45° in order to function efficiently.

It is functionally convenient to maintain the wall thickness of the cutting edge 14 below 0.5 mm.

An anti-twist device is necessary to avoid the blade from getting twisted when or after the bag is pierced. This is ensured when at least one or several bars 21 are affixed to the tube 7 that engage a toothed wheel 25 affixed to the bottle cap in the channel 3, if the tube is inserted.

Conversely, even the toothed wheel can be arranged at the tube and the bars can be arranged in the channel.

In the absence of an anti-twist device, in pierced state a part of the bag foil can be separated by a rotary motion of the tube.

For products with extremely high consistencies (kneadable) it is necessary that the bag is opened by the outlet channel to the maximum possible cross section diameter by slitting and piercing the bag, expanding the hole and even punching out the foil.

However if this is carried out by the user by means of a separate tool, the desired convenience of the system is lost. In addition, through this the foil parts can get into the product.

It has proved to be practicable to insert a part 19 (FIG. 7) during the manufacturing process in the outlet channel 22 that acts as an opening mechanism 20 and also as a plug 23 for the storage time and transport. The end user must then simply remove the plug 23 and then has a product that is open and ready for use.

However because the part for lancing the bag must always be pointed, sharp and stiff, a further advantage can be obtained for the user if the risk of injury by the pointed plug is avoided. This is achieved if the bag is pierced during the manufacturing process and subsequently sealed with a plug 24 without a pointed tip, which then can be pulled off by the user and can be disposed of safely.

The inserting tube 7, 8 and the blade 2, 6 are preferentially made of different materials, namely, the tube is made of a sealing material and the blade is made of a sturdy material.

Thermoplastic resins can be used as sealing material. The preferred materials for the cutting blade are stainless steel, light metal, ceramics or thermoplastic with a high elastic modulus, approximately >=3000 MPa.

In a convenient design form one or several bars 21 at the tube 7 connected to a toothed wheel 25 in the channel 3 prevent the twisting of the tube when the bag is being pierced or is pierced.

The cut out foil piece 10 is furthermore conveniently connected with the bag 15 and is placed at the wall 9 of the outlet channel 7 by the product flow.

The opening function can also be coupled with a closing function, so that a device is developed for the opening and resealing of a tubular bag 15 with a blade 2, 6 affixed to a plug 19 and a sealing element 23. In doing so the plug (23) and the blade (2, 6) are preferentially made of different materials, namely, the plug is made of a sealing material and the blade is made of a sturdy material.

In this respect the invention also concerns the production and application of preopened and resealed tubular bags, wherein the foil of the bag 15 in the area of the outlet channel 22 is pierced before delivery, and resealed with a sealing plug 24 until application; as well as preopened tubular bags of such a type, wherein the foil piece is punched out and removed before the sealing plug is inserted.

Claims

1. Device for opening a tubular bag comprising

A) an inserting tube with an opening adapted to face a tubular bag at one end and an outlet connected to it at the other end via a flow channel for material contained in the tubular bag,

B) a blade fitted to the inserting tube,

C) wherein the blade is equipped with at least one pointed tip for lancing the tubular bag and with at least one edge connected to the pointed tip for cutting the tubular bag and wherein

D) the shape of the blade conforms to that of the inner wall of the outlet for the material contained in the tubular bag.

2. Device according to claim 1, wherein the blade has the shape of a part of a cylinder wall.

3. Device according to claim 1, wherein the blade has the form of three quarters of a cylinder wall.

4. Device according to claim 1, wherein the blade has at least two pointed tips that are connected by a slanting or bent edge.

5. Device according to claim 1, wherein the inserting tube is made of a sealing material and the blade is made of a sturdy material.

6. Device according to claim 5, wherein the inserting tube is made of a thermoplastic resin and the blade is made of bent steel.

7. Device according to claim 5, wherein the inserting tube is made of a thermoplastic resin and the blade is made of light metal.

8. Device according to claim 5, wherein the inserting tube is made of a thermoplastic resin and the blade is made of ceramics.

9. Device according to claim 5, wherein the inserting tube is made of a thermoplastic resin with an elastic modulus <=≦2000 MPa and the blade is made of a thermoplastic resin with an elastic modulus >=≧3000 MPa.

10. Device according to claim 1, comprising at least one bar in the tube and a toothed wheel in the flow channel to prevent the tube from getting twisted when the tubular bag is being pierced or has been pierced and the device is engaged with the bag.

11. Device according to claim 1, comprising at least one bar in the channel and a toothed wheel in the tube to prevent the tube from getting twisted when the tubular bag is being pierced or 3has been pierced and the device is engaged with the bag.

12. Method of opening a tubular bag with device of claim 1, wherein a piece of the tubular bag is cut and remains partially connected with the bag and is placed by the product flow at the wall of the outlet channel.

13. Device according to claim 1 disposed as a sealing plug for the outlet to which the blade is attached at the side facing the tubular bag.

14. Device according to claim 13, wherein the plug comprises a separate sealing element for sealing the outlet.

15. Device according to claim 13, wherein the plug or the sealing element are made of a sealing material and the blade is made of a sturdy material.

16. Process for the manufacture of preopened and resealed tubular bags wherein a tubular bag is pierced in the area of its outlet channel with the device of claim 1 before delivery and is resealed until application by a sealing plug inserted in the device.

17. Process according to claim 16, wherein a piece of the tubular bag is punched out and removed before the sealing plug is inserted.