FR2861328A1 - METHOD FOR MANUFACTURING PACKAGING TUBE, PACKAGING TUBE AND DEVICE FOR CARRYING OUT SAID METHOD. - Google Patents

Abstract

Extrusion blow molding process for packaging tubes, in which a parison is extruded which is then projected by blowing against the walls of a mold (1), characterized in that the thickness of the wall (2) of the tube is variable and predefined by a setting of the parison, said setting taking place preferably at the time of extrusion using a suitable software. The invention also relates to a packaging tube, characterized in that it consists of a skirt and a neck made simultaneously by extrusion blow molding, said skirt (7) being of a variable and predefined thickness, and in particular thicker at the the gas exchange zone (8) at the level of the compression zone (9) by the user. Preferably, the lower end (5) of said tube, opposite to the neck (4), comprises a chamfered zone (10). The invention also relates to a device for implementing the method characterized in that it comprises a mold (1) in two parts (1a) and (1b), the length of said mold being equal to the length of one or two conditioning tubes, and in that it comprises at least one blowing rod and at least one calibration jig (3) whose shape is preferably frustoconical.

Description

A method of manufacturing a conditioning tube, tube

  packaging and device for implementing said method.

  The present invention relates to a method of manufacturing an extrusion blow molding tube. The present invention also relates to a device for implementing this method.

  Extrusion blow molding is a known method for the manufacture of packaging tubes. The tubes are generally made of plastic, of the PE, PP, PET, coextruded or linear PE type. It has been observed that these tubes are not always perfectly impermeable to gases, and in particular to air. The entry of air into the tubes inflates the tubes and causes oxidation of the contents of the tube by the oxygen of the air. This air intake is conventionally carried out in the tube through the wall of the tube, at the filling limit of the tube by the product. This frontier zone is known to be a gaseous exchange zone. To answer this problem, thicker tubes have been manufactured: reinforcing the thickness of the wall has the effect of reducing the permeability of the tube, and limiting the air intake. This solution is however not satisfactory because it requires the user to apply a high pressure on the tube, and limits the possibility for the user to expel all the product contained in the tube. There is therefore a need for tubes whose wall would be on the one hand thin enough to allow easy expulsion of the product by the user, and on the other hand reinforced at the level of the gaseous exchange zone, to avoid the air inlet into the tube.

  A tube consists of a skirt and a head, constituting the neck of the tube. In the processes of the prior art, the skirt and the head are made separately, and welded together. The head is usually injected. The skirt can be injected or extruded. The injection technique for the manufacture of skirts requires the exercise of high pressures which have the effect of deteriorating the physical and chemical properties of the constituent material of the tube. Extrusion techniques allow to obtain better results, however the thickness of the wall 2 is not completely controlled and in particular the internal diameter of the tube is not constant.

  To overcome these drawbacks, the Applicant proposes a new method of manufacturing at least one concentric tube, which is formed in one piece, wherein the thickness of the skirt is variable and predefined. The method according to the invention makes it possible to use any mold, and thus to obtain all kinds of tube shapes, without any constraint, all kinds of diameters and tubes of all kinds of capacities. The parison used may be a thermoplastic resin or a coextruded, or any other material used to make a tube. According to a preferred embodiment of the invention, the manufactured tube is frustoconical, which is an important advantage for stacking and storing the tubes before filling.

  The process according to the invention is a particular extrusion blow molding process in which a parison is parameterized and extruded. The parameterization is intended to pre-define the thickness of the wall of the tube at different horizontal planes passing through the tube. By horizontal plane, any plane perpendicular to the axis of the tube is understood.

  According to a preferred embodiment of the invention, the wall of the skirt of the tube is reinforced at the level of the gaseous exchange zone and is thinner at the level of the pressure zone of the tube by the user. The parameterization software used for this purpose is of the type used for the parameterization of flasks and which are known to those skilled in the art. The setting is preferably at the time of extrusion of the parison. Extrusion is continuous.

  According to the invention, the parison is extruded to a diameter smaller than the diameter of the desired tube (s). According to a preferred embodiment of the invention, the tube according to the invention also comprises a stiffening zone of the tube shape, which is preferably a chamfered zone located at the lower end of the tube opposite the neck. The presence of this chamfered zone prevents the tube from taking an oval shape, which is a tendency often observed and which is either spontaneous or generated during storage or transport; the oval shape makes it difficult to enter the heating nozzle for subsequent welding of the tube and represents a real disadvantage in industrial processing.

  According to another embodiment of the invention, the tube comprises a calibrated welding zone which stiffens it as well. The invention also includes tubes that have both a chamfered area and a weld area.

  The invention will be better understood on reading the detailed description which follows, which is read with reference to FIGS. 1 and 2. These figures are given for explanatory purposes only, and in no way limit the scope of the claimed invention.

  FIG. 1 is a longitudinal section of a device implementing a first embodiment of the invention, in which only one conditioning tube is produced at a time.

  FIG. 2 is a longitudinal section of a device embodying a second embodiment of the invention, in which two conditioning tubes are produced at a time.

  The subject of the invention is a packaging tube, characterized in that it consists of a skirt 7 and a neck 4 made simultaneously by extrusion blow molding, said skirt 7 being of a variable and predefined thickness, and especially thicker at level of the gaseous exchange zone 8 at the level of the compression zone 9 by the user.

  According to a preferred embodiment of the invention, the lower end of said tube is chamfered. This chamfered zone 10 gives the tube sufficient rigidity to avoid spontaneous deformation of the tube shape in the horizontal plane perpendicular to the vertical plane of the axis of the tube.

  According to another embodiment of the invention, the tube contains a weld zone of the calibrated tube, which has the consequence that its thickness is constant over the entire circumference of the tube. This embodiment has the advantage that the subsequent heating of the welding zone by a heating nozzle will cause a homogeneous temperature rise over the entire inner circumference and a constant reaction of the polymer at this temperature rise, which ensures a good weld higher.

  Advantageously, the inside diameter of the tube is constant on the welding zone 6 outside the chamfered zone 10: thus, the subsequent entry of a heating nozzle is ensured in good conditions.

  Advantageously, the wall 2 of the tube is concentric in each horizontal plane containing it.

  The subject of the invention is also a process for manufacturing extrusion blow molding tubes, in which a parison is extruded which is then blown against the walls of a mold 1), characterized in that the thickness of the the wall 2 of the tube is variable and predefined by a setting of the parison.

  Advantageously, the parison is of a length slightly greater than the length of the mold 1 and a diameter slightly smaller than the diameter of the mold 1 when closed; the parison is positioned by gravity against the two parts la and lb of the mold 1). This positioning can be natural or forced.

  According to a first embodiment of the invention, illustrated in Figure 1, it seeks to manufacture a single tube at a time. In this case, the length of the parison is chosen slightly greater than the length of the conditioning tube that is to be manufactured; the lower part of the parison is trapped in the lower part of the mold, which corresponds to the base of the tube, between the mold 1 in the closed position and a calibration jig 3. The shape of this template 3 of calibration must be adapted to enter the mold 1; it is generally preferred to use jigs 3 of frustoconical shape, and whose diameter of the base of the frustoconical portion is substantially equal to or slightly less than the inside diameter of the mold 1 in the closed position. This positioning between two pieces corrects any deformation of the base of the parison, due to environmental conditions. This imprisonment of the parison between mold 1 and 3 gauge has the function of calibrating the parison in the trapped area. The part of the parison thus calibrated between two parts, which are the wall 2 of the mold 1 and the calibration template 3, has a constant thickness, a perfect concentricity, and has good rigidity: this part of the tube will constitute, in this mode the welding zone, which will then be heated and welded.

  In all the embodiments of the invention, the parison can be trapped between closed mold 1 and calibration template 3 at the neck 4 of the tube or tubes that are to be manufactured, to calibrate said collar 4). However, the invention also includes the manufacture of tubes whose neck 4 is not calibrated.

  In particular, in the embodiment of the method where the mold 1 corresponds to the manufacture of a single tube at a time, the calibration can be performed at the weld zone 6 of the tube only, at the neck 4 of the tube only, or both at the neck 4 and at the level of the weld zone 6.

  The blowing of the parison is carried out simultaneously or after the calibration. The closure of the mold 1 and the blowing action together constitute the elements that will allow the forming of the tube. The blowing has the particular function of pressing the entire skirt 7 on the parts of the mold 1).

  According to a particular embodiment of the invention, the mold 1 can be engraved, carved, worked, so that the forming gives the tube a particular patterned appearance. According to a particular embodiment of the invention, the mold 1 is cooled, so as to reduce the temperature of the polymer constituting the tube. This polymer may be any polymer used for the manufacture of the tubes, and in particular a thermoplastic resin or a co-extruded polymer.

  In the embodiment of the method where the mold 1 corresponds to the manufacture of a single tube at a time, the length of the tube is made due to the closure of the mold 1 and the movement of the template 3 calibration.

  In another embodiment of the invention, shown in FIG. 2, the method makes it possible to manufacture two tubes at the same time, in a mold 1 whose shape allows the forming of two tubes interconnected by their base 5). In this embodiment, the length of the parison is slightly greater than the length of two tubes and the parison is molded in this mold 1 for the simultaneous manufacture of two conditioning tubes; the upper part and / or the lower part of the parison is then trapped in the part or parts of the mold 1 which corresponds (ent) to the neck 4 of a tube, between the mold 1 in the closed position and a calibration jig 3, whose shape is preferably frustoconical.

  In all embodiments of the invention, when the mold 1 is closed or closed, one or more blowing rods (not shown) is / are introduced (s) over a length of a few millimeters inside the mold . According to the embodiments, the blowing rods are introduced through the neck 4 or the base 5 of the tube. In the embodiment where only one tube is manufactured at a time, the blowing can be effected by the neck 4), or by the base 5 of the tube, or on both sides. According to a variant of the invention, the blowing rod passes through the entire height of the tube.

  The method according to the invention provides that the calibration of the base 5 and / or the neck 4 of the tube and the blowing can be successive or simultaneous. Simultaneously or after blowing, the top and / or bottom of the tube is removed. Of course, the decarbonization of the bottom of the tube takes place only in the embodiment where only one tube is manufactured at a time.

  In the embodiment of the invention in which two tubes are manufactured, the method according to the invention comprises a recovery step which consists in making a cut at the level of the enlarged medium of the mold 1 to separate the two tubes while maintaining each tube has a chamfered zone 10 at its base.

  The method according to the invention further comprises a step of closing the neck 4 of each tube by a shutter or a plug, a step of filling each tube with the product to be packaged, and a welding step at the level of the solder 6 of each tube. This soldering step comprises heating the welding zone 6 of the tube. Preferably, the heating required for welding is applied by means of a heating nozzle delivering hot air very close to the weld zone. Advantageously, the space between the nozzle and the weld zone is less than 1 mm.

  For the realization of this step, it is particularly important that the tube has kept a round shape, and has not been deformed laterally: a lateral deformation is an obstacle to the entry of the heating nozzle into the tube. In addition, maintaining the round shape ensures that the temperature rise of the polymer is identical over the entire circumference of the tube. This constancy in the temperature rise of the polymer is further improved when the weld zone is calibrated.

  After heating, the welding is performed by approximation and pinching of the weld zone 6). and the successive clamping of the walls between two heating tongs will be performed with the same force and have the same effects on the two parts to be welded. The quality of the weld will be consistent, reproducible, and assured.

  According to a preferred embodiment of the invention, the filling of the tube with the material to be dispensed is effected by the bottom of the tube.

  The invention also relates to an extrusion blowing device characterized in that it comprises a mold 1 in two parts; this mold preferably comprises at least one chamfer; the length of the mold 1 is equal to the length of one or two conditioning tubes; this device comprises at least one blowing rod and at least one calibration jig 3 whose shape is preferably frustoconical and an extrusion device associated with a parameterization software.

  According to a particular embodiment of the invention, the two parts 1a and 1b of the mold 1 are preferably provided with a cooling system and / or a heating system of the parison. According to another particular embodiment of the invention the blow pipe (s) may be provided with a blown gas cooling system, and / or with a blown gas heating system.

  The calibration template 3 can consist of one or more parts, is movable or stationary, is optionally combined with a heating and cooling system of the parison, and is optionally combined with a blowing rod. For the purposes of the present invention, the calibration jig 3 is combined with a blowing rod when it is constituted by the external shape of the end of a blowing rod. When the calibration template 3 is mobile, the closing of the mold 1 can be simultaneous with the establishment of the calibration template or templates, or intervene before or after the introduction of the calibration template or templates. This calibration template has a portion of constant diameter smaller than the inner diameter of the mold 1 so that the thickness of the wall of the tube on the calibration zone is one and a half to five times thicker than in the other parts of the tube. According to a preferred embodiment of the invention, the base of the calibration jig is chamfered and the mold is also chamfered so that the introduction of the calibration jig into the mold causes a section of the parison and the formation of the jig. a chamfered area 10 on the tube. Any means leading to the formation of a chamfered area on the tube forms part of the present invention.

  Advantageously, the device according to the invention comprises a device for decarrating the neck 4 and / or the base 5 of the tube.

  According to a first embodiment of the invention where one tube is manufactured at a time, the length of the mold 1 is substantially equal to the length of a packaging tube. In this embodiment, the device preferably comprises a gauge 3 for calibrating the base 5 of the tube in order to calibrate the welding zone 6). The closure of the mold 1 against the calibration template causes in particular the lengthening of the base of the tube: in fact, the base of the mold 1 is preferably provided with a chamfer or forms a cutting edge which will come into abutment on the 3 gauge calibration and cut the parison clearly, at an angle of 0 to 90, preferably from 30 to 60, and very preferably of the order of 45. A chamfered zone 10 is thus formed on the base of the tube, and this chamfered zone stiffens the tube, and thus allows a good maintenance of the concentric shape of the tube.

  According to a second embodiment where two tubes are manufactured at a time, the length of the mold 1 is substantially equal to the length of two conditioning tubes. In this case, the shape of said mold 1 is such that the closed mold 1 defines a neck 4 of tube at the top of said mold 1 and a neck 4 of tube at the bottom of said mold, and the middle of the length of the mold 1 comprises a zone 11 wider corresponding to a cutting zone for the separation of said two tubes. In this embodiment, the device comprises two tubing neck calibration jigs, one entering the upper part of the mold, and the other entering the lower part of the mold.

  According to a preferred embodiment of the invention, this cutting zone is configured to define a chamfer at the base of each tube after cutting. According to another embodiment, no cutting zone is determined in the device, and the two tubes are cut on demand and may finally be tubes of the same or different length.

Claims (2)

12 CLAIMS   A method of manufacturing extrusion blow molding tubes, in which is extruded a parison which will then be projected by blowing against the walls of a mold (1), characterized in that the thickness of the wall (2). of the tube is variable and predefined by parison parameterization, said setting taking place preferably at the time of extrusion using a suitable software.   2. Method according to claim 1, characterized in that said parison is of a length slightly greater than the length of the mold (1) and of a diameter slightly smaller than the diameter of the mold (1) once closed and in that said parison is positioned by gravity against the two parts (la) and (lb) of said mold (1). 3. Method according to any one of claims 1 or 2, characterized in that said length of the parison is slightly greater than the length of a tube.   4. Method according to claim 3, characterized in that the lower part of said parison is calibrated in the lower part (6) of the mold (1), which corresponds to the base of the tube, between the mold (1) in the closed position and a calibration jig (3), the shape of which is preferably frustoconical.   5. Method according to any one of claims 3 or 4, characterized in that the length of the tube is effected by closing the mold (1) and the movement of the calibration jig (3).   6. Method according to any one of claims 1 or 2, characterized in that said length of the parison is slightly greater than the length of two tubes and in that said parison is molded in a mold (1) for manufacturing simultaneous two conditioning tubes.   7. Method according to any one of the preceding claims, characterized in that the upper part and / or the lower part of said parison is calibrated in the part or parts of the mold (1) which corresponds (ent) to the neck (4) of a tube, between the mold (1) in the closed position and a calibration jig (3).   8. Method according to any one of the preceding claims, characterized in that, when the mold (1) is closed or closed, one or more blowing rods is (are) introduced into the mold ( 1).   9. Method according to any one of the preceding claims, characterized in that the calibration of the base (5) and / or the neck (4) of the tube and the blow are successive or simultaneous.   10. Process according to any one of the preceding claims, characterized in that, simultaneously or after blowing, the top and / or bottom of the tube are removed.   11. Method according to any one of the preceding claims, characterized in that, when the mold (1) is of the type intended for the simultaneous manufacture of two conditioning tubes, it comprises a recovery step which consists in making a cut at level of the expanded medium of the mold (1) to separate the two tubes.   12. Method according to any one of the preceding claims, characterized in that it further comprises a step of closing the neck (4) of each tube by a shutter, a filling step of each tube with the product to condition, and a soldering step of the base (5) of each tube.   13. Method according to any one of the preceding claims, characterized in that said soldering step comprises heating the weld zone of the tube and welding by approximation and pinching of the weld zone.   14. Packaging tube, characterized in that it consists of a skirt and a neck made simultaneously by extrusion blow molding, said skirt being of a variable and predefined thickness, and especially thicker at the gaseous exchange zone. only at the level of the compression zone by the user.   15. Packaging tube according to claim 14, characterized in that the lower end of said tube, opposite the neck, is chamfered.   16. Packaging tube according to any one of claims 14 or 15, characterized in that its weld area is of sufficient rigidity to avoid spontaneous deformation of the tube shape in the horizontal plane perpendicular to the vertical plane of the tube. axis of the tube.   17. Packaging tube according to claim 16 characterized in that its weld zone is of perfectly constant thickness over the entire circumference of the tube.   18. Packaging tube according to any one of claims 14 to 17, characterized in that its wall is concentric in each horizontal plane containing it.   19. Packaging tube according to any one of claims 14 to 18 characterized in that its inner diameter is constant over the non-chamfer welding area.   20. Extrusion blowing device characterized in that it comprises a mold in two parts, the length of said mold being equal to the length of one or two conditioning tubes, in that it comprises at least one blow pipe and at least one calibration jig whose shape is preferably frustoconical and in that it comprises an extrusion device associated with a parameterization software.   21. Device according to claim 20, characterized in that said mold comprises at least one chamfer or a means of forming a chamfered zone at the base and / or the neck of the tube, said means being able in particular to be a cutting edge which comes into stop on the calibration template when the mold is closed.   22. Device according to any one of claims 20 or 21, characterized in that said two parts of the mold are preferably provided with a cooling system and / or a heating system of the parison.   23. Device according to any one of claims 20 to 22, characterized in that said blowing rod can be provided with a cooling system of the blown gas, and / or a heating system of the blown gas.   24. Device according to any one of claims 20 to 23, characterized in that said calibration jig consists of one or more parts, is movable or stationary, is optionally combined with a heating and cooling system of the parison, and is possibly combined with a blowing rod.   25. Device according to claim 24, characterized in that said calibration jig is combined with a blowing rod because it is constituted by the outer shape of the end of a blowing rod.   26. Device according to any one of claims 20 to 25, characterized in that it comprises a decarter device of the neck and / or the base of the tube.   27. Device according to any one of claims 20 to 26, characterized in that the length of the mold (1) is substantially equal to the length of a conditioning tube.   28. Device according to claim 27, characterized in that said device comprises a template (3) for calibrating the base of the tube for the calibration of the weld zone (6).   29. Device according to any one of claims 20 to 26, characterized in that the length of the mold (1) is substantially equal to the length of two conditioning tubes.   30. Device according to claim 29, characterized in that the shape of said mold (1) is such that the closed mold defines a neck (4) tube at the top of said mold (1) and a neck (4) tube down said mold (1), and in that, preferably, the middle of the length of the mold (1) comprises a wider zone (11), said wider zone also corresponding to a cutting zone with a view to the separation of said two tubes and preferably being configured to define a chamfered area at the base of each tube after cutting.   31. Device according to any one of claims 29 or 30, characterized in that it comprises two calibration gauges tube necks, one entering the upper part of the mold, and the other entering the lower part. of the mold.