Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
  • B29C37/0053—Moulding articles characterised by the shape of the surface, e.g. ribs, high polish
  • B29C37/0057—Moulding single grooves or ribs, e.g. tear lines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/18—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/32—Component parts, details or accessories; Auxiliary operations
  • B29C43/36—Moulds for making articles of definite length, i.e. discrete articles
  • B29C43/42—Moulds for making articles of definite length, i.e. discrete articles for undercut articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/021—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface
  • B29C2043/022—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface having locally depressed lines, e.g. hinges
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/021—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface
  • B29C2043/023—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface having a plurality of grooves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/32—Component parts, details or accessories; Auxiliary operations
  • B29C43/36—Moulds for making articles of definite length, i.e. discrete articles
  • B29C43/3642—Bags, bleeder sheets or cauls for isostatic pressing
  • B29C2043/3652—Elastic moulds or mould parts, e.g. cores or inserts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/32—Component parts, details or accessories; Auxiliary operations
  • B29C43/50—Removing moulded articles
  • B29C2043/5007—Removing moulded articles using cores, i.e. the cores forming part of the mould cavity
  • B29C2043/5015—Removing moulded articles using cores, i.e. the cores forming part of the mould cavity having undercuts or being threaded
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
  • B29C33/442—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles with mechanical ejector or drive means therefor
  • B29C33/444—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles with mechanical ejector or drive means therefor for stripping articles from a mould core, e.g. using stripper plates
  • B29C33/446—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles with mechanical ejector or drive means therefor for stripping articles from a mould core, e.g. using stripper plates and using a rotating movement to unscrew articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/25—Solid
  • B29K2105/253—Preform
  • B29K2105/258—Tubular
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2001/00—Articles provided with screw threads
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/56—Stoppers or lids for bottles, jars, or the like, e.g. closures
  • B29L2031/565—Stoppers or lids for bottles, jars, or the like, e.g. closures for containers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/712—Containers; Packaging elements or accessories, Packages

Definitions

• the invention relates to a method of manufacturing by compression molding of plastic parts having a neck provided with an orifice. These parts are generally containers or parts of containers.
• the invention relates more particularly to the conditions of production in high rates of molded objects which have an axisymmetric neck delimiting a substantially circular orifice, for example flexible plastic tube heads, comprising a neck provided with a orifice. distribution and a shoulder connecting said neck to a flexible cylindrical skirt. We will use these flexible tube heads to illustrate the present invention.
• a flexible tube is produced by assembling two pieces produced separately: a flexible cylindrical skirt of given length (typically 3 to 5 times the diameter) and a head comprising a neck provided with a dispensing orifice and a shoulder connecting said neck with cylindrical skirt.
• the head made of plastic material (s) can be molded separately and then welded to one end of the skirt, but the latter is advantageously molded and welded autogenously to the skirt using either an injection molding technique (FR 1 069 414) or a compression molding technique for an extruded blank (FR 1 324 471).
• the skirt is fitted around a punch, one of its ends protruding slightly from the end of the punch, said punch end serving as a mold for producing the internal surface of the tube head (inside of shoulder and neck).
• a matrix is used which is pressed against the end of the punch, the imprint of this matrix defining the external surface of shoulder and neck.
• French application FR 1 324471 (Karl Mpurrle) describes a compression molding process for tube heads in which the lower mold is formed by the end of a mandrel and the end of a skirt fitted around this mandrel, the end of said skirt projecting from the end of said mandrel; the space delimited by the end of the mandrel and the projecting part of the skirt is supplied by injecting plastic material through several orifices regularly distributed in a nozzle; the plastic is distributed around a counter-punch formed at the end of the mandrel and intended to mold the shape of the interior part of the neck.
• the nozzle is removed, the parts of the upper mold are brought together by radial displacement, then the plastic material is compressed by bringing the lower mold closer to the upper mold.
• the jets are regularly distributed over the circumference and the material thus poured is distributed approximately homogeneously along its circumference before undergoing compression. This gives a substantially uniform thickness around the dispensing orifice.
• the extrusion of the toroidal blank is carried out using an extruder having an annular die, the opening of which is controlled by means of a valve. This closes or not, depending on its position, the annular flow of the plastic and its movement controls the size of the toroidal blank thus obtained.
• the use of toroidal blanks obtained by discontinuous extrusion of plastic material controlled using a valve is therefore the only means known in the prior art for efficiently and directly obtaining by compression molding a neck provided with an orifice having a sharp edge.
• such a technique is imprecise and does not allow good reproducibility by weight of the toroidal blank, which complicates the conditions of compression molding, the latter not having for example the flexibility of injection molding where all excess material can be more easily removed.
• the toroidal blank is cooled relatively quickly by conduction in the tooling.
• the cooling is heterogeneous and a large part of the advantage provided by the toric geometry of the blank is lost, namely a good distribution of the material before compression.
• Many solutions such as that proposed in WO96 / 09151 (Karl Mpurrle whi) make it possible to reduce the extent and the heterogeneity of the cooling of the blank before compression but they require the introduction of additional tooling elements (for example the auxiliary support sliding around the central protuberance described in WO96 / 09151) as well as means making it possible to control their movement.
• Such sophistication makes tooling economically unprofitable, even prohibitive if one wishes to make the moving parts of the tool follow a continuous overall movement.
• EP 0 841 258 describes a molding manufacturing process
• the Applicant has therefore sought to develop a process for manufacturing by compression molding of plastic parts provided with a neck having an orifice which is not subject to the problems mentioned above and which can therefore be easily implemented. implemented using tools driven by continuous kinematics.
• the object according to the invention is a method of manufacturing by compression molding of plastic parts having a neck provided with an orifice comprising a first step of producing a plastic blank and a second step of compressing the said blank, in which said blank, brought to an appropriate temperature, is placed 0 in the air gap comprised between at least two movable parts of the compression tooling is then compressed by mutual approximation of said mobile parts of the tooling, the plastic material of the blank flowing so as to fill the cavities of the impressions of said mobile parts until relative immobilization of said mobile parts, footprints of said movable parts of the tool once joined defining the volume of said piece having a neck, said footprints being drawn so that said neck, once molded, has a top wall which comprises a thinned zone whose outline delimits the desired shape of the orifice, said method being characterized in that said thinned zone is bordered by a notch, the section of which by a diametral plane passing through the axis of the neck is oriented in a direction
• Said notch has a section through a diametral plane passing through the axis of the neck oriented in a direction substantially parallel to the axis of the neck, in that it is made a slight angle with said axis, typically between 0 and 45 °, preferably between 0 ° and 30 °.
• rupture zone or even breakable zone the thinned zone of the summit wall located at the level of the notch.
• the breakable zone is thus a part of the thinned top wall of which one of the faces is provided with a notch.
• This notch can be located on the underside of the top wall but, preferably, it is located on the top face of the top wall so as to prevent possible deformations of the thinned residual zone resulting from the rupture leading to obtaining geometrical defects accessible to sight or to touch (injurious chips).
• the top wall is not necessarily a wall of constant thickness. It can have different parts, some of which can be massive, but it has at least one part that acts as a wall blocking the dispensing orifice.
• the molding tool intended to produce the molded part is conventional: it comprises at least two parts which are movable relative to one another. In the case of a tube head, these two parts are the punch and the die. Very often, the neck must have a screw thread on its outer wall, which requires using a matrix itself in several moving parts which move away from each other - for example by means of radial displacements - to facilitate demolding of the threaded part.
• the molded part according to the invention has a neck which is not immediately provided with an orifice: the latter is produced in a later stage but without the need to use a cutting tool.
• the compression can be carried out with a not necessarily toroidal blank, the massive shape of which on the one hand is easier to obtain in a reproductive manner by weight (improvement of the compression molding conditions) and on the other hand reduces the extent and heterogeneity of cooling.
• the amount of material thus obtained depends on the displacement perpendicular to the direction of extrusion of a shear blade external to the die and not of the displacement of a sliding valve in the axial direction inside the die and having to discontinuously close an annular orifice.
• the neck is surmounted by a top wall which temporarily plugs the orifice and a part of which - which we will call hereafter the seal - is partially or entirely detached in a later stage of the process using the application of a simple mechanical force applied in a part of the top wall, called the mechanical force application zone and distinct from the breakable zone.
• the top wall comprises at least four zones: a zone for applying mechanical force, a zone for transmitting mechanical force, a breakable zone and a support zone.
• the mechanical force is intended to be applied to said top wall, at the level of the application zone, with sufficient intensity to break said top wall at the level of said notch.
• the intensity of the force necessary to cause the rupture depends on the direction of said mechanical force and the distance of its point of application from the breakable zone.
• the cover - that is to say the part of the top wall which detaches partially or entirely after rupture of the breakable zone - is the zone transmitting the forces applied to tear the top wall at the level of the notch and the part corresponding to the attachment of the top wall to the neck is the support zone.
• the cover has any geometry adapted to the type of mechanical force that must be applied to cause the rupture. It can be in the form of a rod to amplify by leverage a force applied at its end, as illustrated in FIG.
• L 'notch follows any curve, not necessarily flat and not necessarily closed. If it is closed, the rupture of the breakable zone leads to complete detachment of the cover. The latter is advantageously removed, preferably using the residual part of the energy supplied to break the breakable zone. The cut can also follow an open contour. In this case, the rupture of the breakable zone leads to a partial detachment of the cover.
• the breakable zone is notched with a notch, the section of which by a diametral plane passing through the axis of the neck is oriented in a direction that is slightly inclined relative to the axis of the neck.
• the bisector of the V is slightly inclined with respect to the axis of the neck and describes a cylinder or a cone having an angle at the center less than 90 °, preferably less than 60 °.
• said bisector makes an angle between 0 and 45 °, preferably between 0 ° and 30 ° with the axis of said neck.
• the angle of the V is between 30 and 90 °, typically between 40 and 50 °.
• the V does not necessarily have its branches symmetrically around its bisector.
• the desired orifice is simply circular and the breakable zone is an annular notch whose section is a V whose internal branch (that is to say the branch closest to the axis) is slightly inclined by relative to the axis and whose outer branch is more strongly inclined.
• the internal branch of the V makes an angle with the axis less than 5 °
• the bisector makes an angle of 25 ° with the axis of the neck
• the external branch makes with said axis an angle less than 55 °.
• the shape of the cut locally favors a concentration of the stresses generated by the application of a mechanical force, whether this is a force or a moment applied in a particular place of the cover.
• the transverse wall may be of small extent, for example limited to the breakable zone, but it must be present to orient the notch so that its axis is substantially parallel to that of the neck.
• the easily breakable area is, by the very presence of the notch, thinner than the neighboring areas.
• the residual thickness under the notch is less than 30% of the overall thickness of the transverse wall outside the notch.
• it is between 0.1 and 0.6 mm. As it is thin, it cools more quickly than the other parts of the neck, which makes it possible to apply forces causing the rupture less brutal than impacts, that is to say with forces generating deformation rates of around 10 3 s- '.
• the mechanical force is for example an axial push or traction, a rotation around the axis of the neck, a combination of the two (during the unscrewing - stripping of the head for example), a force applied to the other end of the lid in the form of a stick, etc.
• the rupture of the cover is carried out during the cooling following the molding, as soon as the material stabilizes, which makes it possible to break the cover before the ejection of the part from the molding tools.
• the blank is also advantageous to place the blank to be compression molded above or directly opposite the end of the protruding part of the molding tool intended to produce the interior surface of the neck.
• the part of the blank which is in contact with the tool cools a little faster than the rest of the blank by conduction.
• the surface imperfections linked to the greater cooling of the plastic material there, the friction and the heterogeneous flow of the resulting material will remain on the seal which will then be detached. They will therefore not see each other.
• Another solution applicable in continuous kinematics consists in giving a part of the cover a rod shape similar to that of Example 1 and in applying a force to the end of the rod as soon as the die is removed from the punch, using, for example, a stationary finger in front of which the punch still fitted with the tube head scrolls. Under the effect of the flexion imposed on the rod and transmitted by it to the transverse wall, the breakable zone is broken and the cover is ejected in a precise and reproducible direction outside the production line in continuous movement.
• the material preferably has a modulus of elasticity in traction at ambient temperature greater than 200 MPa, preferably greater than 500 MPa.
• this method can be applied to molding methods in which machines are used working step by step. Due to the design of the breakable zone which it implies, the method according to the invention makes it possible to choose from a large number of possible mechanical stresses, that making it possible to obtain, at the lowest cost, a controlled tearing of the breakable zone.
• the final stage of the process, in which the cover is torn, can be integrated into the actual production (implemented during the cooling which follows the molding, or just before the output of the manufacturing device in continuous kinematics, etc. .). It can also be deferred until the first use: example 5 illustrates this case, where it is the user who, when he unscrews the cap for the first time, activates the rupture mechanism of the cover.
• Such a method of the invention thus makes it possible to obtain tube heads provided with a system guaranteeing the absence of violation of the tube before its first use.
• FIG. 3 All of the figures illustrate the production of flexible tubes. With the exception of FIG. 3, they show diametrical sections of tube heads, parts of the compression molding tool or caps.
• FIG. 1a illustrates a particular tube head produced according to the invention, before application of the force intended to break the breakable zone.
• FIG. 1 b illustrates a particular shape of the section of the breakable zone according to the invention.
• FIG. 2a illustrates, using a diametral section, the positioning of a blank in a compression molding tool
• Figure 2b illustrates the molding tool and the molded part at the end of compression. This has a cover whose T-shaped profile causes the presence of an annular groove on the external surface of the cover.
• Figure 2c illustrates the distance of the punch provided with the tube head thus molded. Due to the scale used, the annular notch was not shown.
• L ⁇ 2d illustrates the evacuation of the lid after rupture of the breakable zone, the latter having been caused by the axial displacement imposed by a fork whose fingers come to fit into the annular groove.
• FIG. 3 illustrates in perspective a solution in which the tubes of FIGS. 2a to 2d are produced using molding tools which follow a continuous rotational movement and in which the removal of the lids is carried out simply by trapping the ends said movable lids in a static rail not tangent to the path of the tubes.
• Figure 4 illustrates another case where the cover is torn and then removed using an axial thrust
• FIG. 5 illustrates another case where the cover is torn and then removed using a loosening carried out during the stripping of the matrix.
• FIG. 6 illustrates, in three variants, a modality of the invention in which the neck is overmolded by compression on a plug which has been placed beforehand in a cavity of the matrix.
• Figure 6a) illustrates the device before overmolding by compression of the tube head on the plug
• FIG. 6b illustrates the device after overmolding by compression of the tube head on the stopper
• Figures 6c), 6e) and 6g) illustrate the parts of the tooling provided with the toric edge which makes it possible to shape the breakable zone (6c): punch; 6e) and 6g): plug
• Figures 6d), 6f) and 6h) detail the assembly of the tube head + plug obtained after overmolding in three different cases.
• the tube head 1 illustrated in FIG. 1 a has a shoulder 2 and a neck 3 the upper end of which is surmounted by a top wall 4 which has at least one thinned zone 6, the upper face of which is provided with a notch 5, the closed contour of which delimits the desired shape of the orifice.
• This thinned zone 6, also called breakable zone is surrounded by two zones 7 and 8 able to resist the mechanical force F which is necessary to break said breakable zone, one of them (7) being intended to transmit said mechanical force and the other (8) to serve as support.
• the cover 14 is the part of the top wall 4 which is detached and, in the present case, removed by the application of mechanical force F on the end 91 of the stick 9.
• the area of application of the force is the end 91 of the stick 9.
• the zone capable of transmitting the mechanical force comprises the stick 9 and the web 7.
• the breakable zone 6 is notched with a V-shaped notch 5, with an internal branch 61 which forms an angle of 5 ° with the axis of the neck, an external branch 62 which forms an angle of 55 ° with said axis and the bisector 63 of the V which makes an angle of 25 ° with the axis of the neck.
• the head is molded with high density polyethylene.
• Its neck 3 has an external diameter of 11.5 mm and an average thickness of 1.5 mm (excluding screw thread.
• the transverse web 7, about 1 mm thick, is connected to the top end 8 of the neck 3 , which serves as a support zone
• the rod 9 has a height of 10 mm, the residual thickness of the veil at the level of the breakable zone is 0.3 mm.
• the neck 3 has a 7 mm diameter orifice which does not show any burrs or local deformation.
• Example 2 molding tools are used which move in continuous kinematics, the punch provided with the head 1 of the tube is scrolled in front of a stationary finger. The latter retains the end 91 of the rod 9 in motion and, under the effect of the bending imposed on the rod and transmitted by the latter to the transverse wall 5, the breakable zone 6 is ruptured and the cover is ejected according to a precise and reproducible steering outside the production chain in continuous motion.
• the Applicant has obtained frank and clear breaks in the breakable zone with a linear speed close to or greater than 0.2 meters per second. Very satisfactory results have been obtained with a speed of 0.8 meters per second with molded heads made of high density polyethylene.
• the flexible tube is produced by assembling two parts produced separately: a flexible cylindrical skirt 10 and a head, similar to that described above.
• the head of high density polyethylene is molded and welded autogenously on one end 11 of the skirt 10 using a compression molding technique of an extruded blank 20.
• FIG. 2a illustrates, using a diametral section, the positioning of a blank 20 of high density polyethylene in a compression molding tool.
• This molding tool comprises a punch assembly 35 and a die assembly 30. Compression is obtained by relative approximation of the punch assembly 35 and the die assembly 30 until relative immobilization of the two parts of the tool.
• Each of these parts tooling comprises parts (respectively 350 and 351, 300 and 301) which can be movable between them but which are immobile and integral with each other during compression. The relative movement of these parts does not require the introduction of specific control: it is controlled by the relative overall movement between the punch assembly and the die assembly.
• the central protuberance 352 is integral with the peripheral portion 351, which forms the punch assembly 35.
• the portions 300 are adjacent as a result of a radial displacement imposed by a conical fitting and the whole, integral with the upper part 301 forms therewith the matrix assembly 30.
• the skirt 10 is fitted around the peripheral part 35 of the punch, one of its ends 11 projecting slightly from the end of this part 35 of the punch, which serves as a mold for producing the internal surface of the tube head (interior shoulder and neck).
• the end 352 of the central part 350 of the punch is a central protuberance intended to mold the inside of the neck.
• the moving parts 30 of the die move radially to disengage the screw thread, once it has been molded.
• FIG. 2b illustrates the molding tools and the molded part 21 at the end of compression: it is a flexible tube 21 comprising the cylindrical skirt 10, the shoulder 22 and the neck 23 surmounted by a top wall 24.
• the head has been molded and welded autogenously on the end 11 of the skirt 10.
• the top wall 24 comprises a transverse wall 25 acting as a seal blocking the dispensing orifice and a protuberance 29 having a T-shaped profile, so that it has an annular groove 28 on its side wall.
• FIG. 2c illustrates the distance of the punch assembly from the matrix assembly.
• the flexible tube thus produced remains integral with the assembly punch and cool.
• a fork 40 is brought close to the tube head after a few seconds of cooling when the high density polyethylene is stabilized.
• FIG. 2d illustrates the evacuation of the top wall 24 after rupture of the breakable zone, this having been caused by the axial displacement imposed by the fork 40 whose fingers come to fit in the annular groove 28.
• the breakable zone 26 has a geometry with an annular V-shaped notch identical to that of the breakable zone of Example 1. In this way, the head of the finished tube 50 has a cylindrical neck provided with a dispensing orifice.
• FIG. 3 illustrates an alternative solution to that illustrated in FIG. 2d: the molding tools, and in particular the punches, follow a continuous rotational movement R, such as that imposed by the device referenced 10 in FIG. 2 of French application no. 01 03706. LesOnce formed, the tubes 50 remain integral with said punches after molding and the removal of the lids is carried out by a simple trapping of the ends of the T-shaped lids, their annular grooves 28 coming to fit in a rail 40 'static and not tangent to the trajectory of the tube heads.
• FIG. 4 illustrates another embodiment of a tube in which the head is also compression molded and welded simultaneously to the skirt, in which the top part 64 comprises a simple veil 65 having an annular notch in the vicinity of its attachment to the neck. The veil is torn and then removed using an axial push.
• the cover may, as illustrated in FIG. 4, have a geometry limited to the veil 65 or else, as illustrated in FIG. 1, include the said veil and also be provided with a rod-shaped part to facilitate gripping and the axial thrust. .
• EXAMPLE 4 Figure 5
• FIG. 5 illustrates another embodiment of a tube in which the head is also compression molded and welded simultaneously to the skirt, in which the top wall 74 which comprises a protuberance 75 of non-convex polygonal section (typically a star) and a part bass acting as a seal.
• the die 30 'does not have radially movable parts (300) and the release of the head with its threaded neck is carried out by unscrewing.
• the non-convex polygonal protuberance 75 still occupies the cavity of the mold which formed it, it is blocked in rotation, the breakable zone tears under the effect of the resulting twist, the protuberance is thus detached and then removed during unscrewing.
• This example makes it possible to solve the delicate problem imposed by the extremely fine adjustment of the air gap existing at the end of the travel between the mobile parts of the tool, in particular in the vicinity of the cavity used to shape the breakable zone.
• This delicate adjustment of the air gap is long, which limits the production rate, especially since it must be carried out frequently (adjustments linked to the expansion of the tools, to the wear of the active parts, etc.).
• the tool is subject to a significant risk of breakage in the event of adjustment failure, lack of plastic material in the tool, presence of a foreign body, etc.
• the tool is also exposed at an increased risk of endurance failure due to its sensitivity to wear.
• a compression tooling comprising a first movable part and a second movable part, said first movable part being, at least in the part of the imprint contributing to the shaping of said breakable zone, in a less rigid material than that of said second movable part.
• one of the movable parts of the tool can be provided with a plug intended to close said orifice.
• the latter is positioned so that its internal surface at least partially serves as a molding imprint for shaping said neck, at least at its breakable zone.
• the molding of the neck on the stopper can be carried out by proceeding in a similar manner to the process described in Example 4 of international application PCT / FR02 / 00686 filed by the applicant. In this process, it is a question of making a flexible tube.
• the tube head is molded and welded to a cylindrical skirt obtained by cutting from a sleeve. In this particular case, the head is welded to the skirt simultaneously with its shaping.
• FIG. 6a a plug 805 which is placed in the cavity of the matrix 830.
• this plug may have been itself molded shortly before using the same matrix but it can also have been obtained independently on another molding device. Outside this cavity, the imprint of the matrix 830 has a shape which defines the outer surface of the shoulder 82 of the tube.
• the internal surface of the plug 805 defines the external surface of the neck 83 and of the base of the neck.
• the punch 835 is provided with a skirt 801.
• the stopper 805 has an average thickness of 1 mm.
• the internal surface of the plug possibly provided with one or more screw threads, defines the external surface of the neck to be shaped.
• the part of the imprint of the matrix 830 not covered by the stopper defines the outer surface of the shoulder.
• the matrix 830 acts as a support tool.
• a blank 820 made of low density polyethylene taken from the extruder outlet is placed either on the end of the punch or in the cavity of the die 820. It is compressed by bringing the punch and the die together until the intended shape is obtained. of the head.
• the blank 820 deforms and the flow of the plastic material is guided by the free surfaces of the residual air gap which gradually decreases in volume.
• the punch 835 and the die 830 are joined, they define a molding cavity where the end 802 of the skirt is trapped.
• the plastic material of the blank flows and fills the various parts of the volume delimited by the imprints of the punch and of the die, thus forming the shoulder 82 and the neck 83, provided with 'a transverse top wall 84 and a breakable zone 86.
• the plastic material also comes into contact with the end 802 of the skirt.
• the plastics of the head and the skirt are welded together without further heat or material. They remain welded together after a slight pressure maintenance and after cooling.
• the breakable zone (86, 86 ', 86 ") is shaped using a molding part which has the shape of a toric edge (90, 90', 90").
• This O-ring belongs either to the male tool (punch - Figure 6 c) - 90), or to the plug ( Figure 6e) (90 ') and Figure 6g) (90 ")).
• the rupture is made on the external surface but the risk of appearance of burr is low since the steel toric edge makes it possible to impose sharp angles, therefore a high coefficient of multiplication of the stresses prevailing in the area separable when broken. In other cases, a possible burr resulting from the rupture of the breakable zone may remain invisible inside the neck.
• the breakable element can be secured to the plug, including a protuberance 89 or 89 ′ undercut therein.
• the tube will only be effectively opened during the first unscrewing of the stopper and the rupture force may then be associated with inviolability.
• a slight relief such as a grain of rice, can be provided at the end of the screw thread.
• the undercut protrusion can pass through the thickness of the stopper (89 ") and the material thus extruded through the stopper can be used to fill the top of the stopper and in particular to integrate a personalized decoration, for example a customer logo.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Closures For Containers (AREA)

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• 2002
  • 2002-03-18 FR FR0203332A patent/FR2837132B1/fr not_active Expired - Fee Related
• 2003
  • 2003-03-17 EP EP03744402A patent/EP1485240A2/de not_active Withdrawn
  • 2003-03-17 RU RU2004130495/12A patent/RU2004130495A/ru not_active Application Discontinuation
  • 2003-03-17 JP JP2003576163A patent/JP2005527399A/ja not_active Abandoned
  • 2003-03-17 CN CNA038056143A patent/CN1638935A/zh active Pending
  • 2003-03-17 MX MXPA04008940A patent/MXPA04008940A/es active IP Right Grant
  • 2003-03-17 PL PL03370833A patent/PL370833A1/xx unknown
  • 2003-03-17 BR BR0308514-7A patent/BR0308514A/pt not_active IP Right Cessation
  • 2003-03-17 US US10/501,929 patent/US8025825B2/en not_active Expired - Fee Related
  • 2003-03-17 WO PCT/FR2003/000837 patent/WO2003078126A2/fr active Application Filing
  • 2003-03-17 AU AU2003232291A patent/AU2003232291A1/en not_active Abandoned

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