EP3414071A1

EP3414071A1 - Device for continuously dosing plastic material, especially for a unit for producing components made of plastic material or the like

Info

Publication number: EP3414071A1
Application number: EP17705094.5A
Authority: EP
Inventors: Jean-Pierre Voigtmann; Daniel KOHLENBRENNER
Original assignee: Inovia Technologies SA
Current assignee: Polytype SA
Priority date: 2016-02-10
Filing date: 2017-02-10
Publication date: 2018-12-19
Also published as: WO2017137615A1; CN108602209A; US20200276744A1

Abstract

The invention relates to a dosing device (8) for dosing plastic material or the like, comprising an extrusion head (10) that has a dispensing opening (12) commonly called a die and a punch (11) extending into the dispensing opening (12), coaxially thereto, for continuously extruding a plastic material in the form of a tubular or annular body, and cutting means (14) for separating a dose of said plastic material in the form of a tubular or annular section. Said device is characterised in that said cutting means (14) consist of at least two elements (16) having at least one sharp or cutting edge, extending on either side of the dispensing opening (12) and secured to driving means generating a symmetrical movement of said elements (15, 16) in relation to the longitudinal axis of the extruded tubular body until the tubular body is severed by said elements in order to form a dose.

Description

DEVICE FOR THE CONTINUOUS ASSAY OF PLASTIC MATERIAL, IN PARTICULAR FOR A PLASTIC COMPONENT PRODUCTION UNIT

OR SIMILAR

Technical area

The present invention relates to the field of plastic metering devices or the like, for the determination of any type of pasty material cold or hot such as a thermoplastic (PE, PP, PA, etc.) or an elastomer (natural or synthetic rubber) for example. More particularly, it relates to a metering device adapted for a unit for producing plastic components, such as flexible plastic tubes comprising a skirt and a shoulder, obtained from prefabricated tubular bodies.

State of the art

It is well known that, in general, a flexible tube is made by assembling two pieces manufactured separately, namely a flexible cylindrical skirt of predetermined length and a head comprising a neck with a dispensing orifice and a shoulder connecting said neck to said cylindrical skirt.

Said head, which is generally made of plastic, may be either separately molded and then welded to one end of the cylindrical skirt is molded and soldered in an autogenous manner to the cylindrical skirt by any method well known to those skilled in the art such by an injection molding process or a compression molding process of an extruded blank for example.

For this purpose, it is known to use a so-called integrated dosing device on a tube production machine. Said dosing unit deposits on a mandrel or in a mold the quantity necessary for molding the head comprising a neck with a dispensing orifice, according to a process commonly called compression-molding.

However, the metering devices of the prior art have many disadvantages. A first disadvantage consists in the fact that these devices operate most often in batch mode which does not achieve a high production rate.

This is particularly the case of WO2005 / 072051 which discloses a discontinuous plastic metering device in which, in a first phase, a cavity is filled by a filling duct and, in a second phase, the cavity is isolated by closing the filler pipe before a third and final phase in which the material is expelled from the cavity with the aid of a piston when opening a valve. The material is cut when closing the valve to form the dose.

When closing the filler pipe, the material from the extruder must be stored in a battery that fills and empties each cycle because the extruder can not be stopped and restarted as quickly.

In addition, these different channels filled with material and these multitudes moving parts, also in contact with the material, make it more difficult and longer to change color.

[0009] Plastic metering devices are also described in WO 2007/028723, WO 03/047823, WO 2015/181668 and WO 97/18073.

WO 2007/028723 which discloses an apparatus which comprises an extrusion die provided with a dispensing opening for extruding a flowable material along an exit direction through the dispensing aperture and an cutting medium used to separate a dose of said fluidifiable material, the cutting means being removable with a movement component parallel to the exit direction. More specifically, the cutting means consist of a blade integral with a support means driven in rotation by an electric motor, said blade extending in an oblique plane with respect to the longitudinal axis of the shaft. driving said electric motor.

[001 1] This type of device does not allow the formation of a dose having a tubular or annular shape.

WO 03/047823 discloses a device for forming annular blanks, intended to cut rings of a predetermined thickness of an extruded tube made of a synthetic material comprising, above the outlet mouth of the extruder, a removable body carrying at least one fixed rear blade and at least one removable blade between a working position in which it interacts with the inner edge of a portion of said tube and a rest position in which it is remote of said edge.

This type of device has the disadvantage of transferring the annular dose transversely to the extrusion direction which may deform the dose during transfer, especially for low viscosity plastics at the exit of the die extrusion. Moreover, it is not suitable for forming tubular doses or doses of annular shape and very small section.

WO 2015/181668 discloses a method and apparatus for forming annular doses, a flow of plasticized material, provided by an extruder, passing through a channel which is first cylindrical, then annular, and outgoing by an annular outlet in front of which passes a cutting element which separates an annular dose of material, the latter being deposited on a surface of a capsule whose capacity to stick to the dose is greater than that of the element cutting; the surface and the cutting element being placed at a some distance from each other in such a way that the annular dose, remaining glued to the capsule, is detached from the element; the detachment can be favored by a flow of air. This type of device has the disadvantage of operating discontinuously, ie the flow of plastic material at the outlet of the extrusion die is interrupted at each cutting for the formation of an annular dose, so that it allows a production rate lower than the rate of manufacture of a device operating continuously. In addition, extruded plastic material is housed between the cylindrical cutting element, which is in the form of a ring moving in a reciprocating vertical movement, and the outer wall of the extrusion head so that the movements of the ring heats and then carbonizes said plastic material providing fine black particles that tend to pollute the doses produced.

WO 97/18073 discloses a metering device comprising a mandrel directed upwards, the upper end is formed as an inner compression matrix for the head and the shoulder of the tube, and a metering device for extruding the intended amount of plastic material to subsequently make the head and the shoulder. The metering device has a polystructured hollow body, in which a delivery member is longitudinally displaceable by means of a push rod. The structure of the hollow body is constituted by a feed chamber, a discharge chamber, a first intermediate chamber and a second intermediate chamber. At the second intermediate chamber is connected the extrusion nozzle which may have, in the desired form of a plastic blank to achieve, an annular space or a circular opening. The first intermediate chamber is connected to the second through openings. The delivery member carries the push rod, a discharge piston and, on the side opposite the push rod, a rod which terminates in a piston. valve. By displacement of the push rod, the discharge piston expels the desired quantity of plastic material forming the annular blank from the compression chamber, said plastic material being expelled into the annular space, cut by a blade. annularly displaced vertically and brought into the internal compression matrix. During the next operating cycle, the blank (5) is configured to take the form of the head and shoulder of the tube and is compressed together with the body of the tube attached to the mandrel.

In the same manner as before, this type of device has the disadvantage of operating discontinuously so that it allows a manufacturing rate lower than the rate of manufacture of a device operating continuously.

Disclosure of the invention

One of the objects of the invention is to remedy at least one of these disadvantages by providing a dosing device of simple and inexpensive design for the formation of doses from a plastic or similar extruded material. continued.

For this purpose, and according to the invention, there is provided a plastic metering device or the like comprising an extrusion head having a dispensing orifice commonly called die and a punch extending into the orifice dispensing apparatus coaxially therewith for continuously extruding a plastic material in the form of a tubular or annular body and cutting means for separating a dose of said plastic material in the form of a tubular or annular section; said device is remarkable in that said cutting means consist of at least two elements having at least one sharp or sharp edge, extending on either side of the orifice of distribution, and integral drive means providing a symmetrical movement of said elements relative to the longitudinal axis of the extruded tubular body until the tubular body is cut by said elements to form a dose.

Advantageously, the trajectory performed by the sharp edge or the cutting edge of each element is a closed path.

Furthermore, the sharp edge or the cutting edge of each element comprises, on at least part of the path, a displacement speed component in a direction perpendicular to the extrusion direction and a displacement speed component. in the same direction as the extrusion direction.

Preferably, the displacement speed component in the same direction as the extrusion direction is substantially identical to the displacement speed of the extruded tubular body continuously.

Preferably, after the cutting of the tubular body, the trajectory of the sharp edge or cutting edge of each element comprises a displacement speed component in the extrusion direction greater than the displacement speed of the tubular body in order to propel the dose in the extrusion direction.

[0024] Said punch comprises at least a first portion said cylindrical inner diameter slightly smaller than the inner diameter of the dispensing orifice and a so-called transition portion projecting from the dispensing orifice and frustoconical shape.

According to an alternative embodiment of the metering device according to the invention, said punch comprises a first portion said inner cylindrical diameter slightly smaller than the inner diameter of the dispensing orifice and a second so-called outer portion also cylindrical diameter greater than the diameter of the inner portion, the transition between the inner portion and the outer portion of the punch being in the form of a truncated cone.

Preferably, each element has an ajour positioned at the sharp edge or cutting edge of said element.

Said aperture has a shape of a circular arc radius of curvature substantially equal to the radius of curvature of the outer portion of the punch.

Preferably, said ajour has dimensions slightly greater than the dimensions of the outer portion of the punch so as to provide a clearance between said elements and said punch.

Furthermore, the trajectory performed by the sharp edge or the cutting edge of each element is a closed path comprising at least three distinct parts, a first so-called cutting portion in which the sharp edge or cutting edge of each element present. a displacement velocity component substantially in a direction perpendicular to the extrusion direction until the sharp edge or cutting edge is in line with the extrusion head, a second so-called evacuation portion in which the sharp end or cutting edge of each member has a displacement velocity component substantially in a direction parallel to the extrusion direction, the sharp edge or cutting edge of each member providing the severing of the tubular body to form the dose when said elements reach the distal end of the transition portion of the punch, and a so-called return portion in which the stop vi or the cutting edge of each element has a displacement velocity component in a direction parallel to the extrusion direction and a displacement velocity component in a direction perpendicular to the extrusion direction. According to an alternative embodiment, the trajectory performed by the sharp edge or the cutting edge of each element is a closed trajectory comprising at least three distinct parts, a first so-called cutting portion in which the sharp edge or sharp edge each element has a displacement velocity component in a direction perpendicular to the extrusion direction and a velocity component in a direction parallel to the extrusion direction until the sharp edge or the cutting edge passes through the wall of the tubular body extruded at the transition portion of the punch protruding from the dispensing orifice, the sharp end or the cutting edge of each element then providing the sectioning of the tubular body to form the dose, a second part called in which the sharp edge or cutting edge of each element has a displacement speed component essentially in a direction parallel to the extrusion direction, and a so-called return portion in which the sharp edge or cutting edge of each member has a displacement velocity component in a direction parallel to the extrusion direction and a velocity component moving in a direction perpendicular to the extrusion direction.

According to another variant embodiment, the trajectory performed by the sharp edge or the cutting edge of each element is a closed trajectory comprising at least three distinct parts, a first so-called cutting part in which the sharp edge or the cutting edge of each member has a displacement velocity component in a direction perpendicular to the extrusion direction and a displacement velocity component in a direction parallel to the extrusion direction until the sharp edge or cutting edge passes through the wall of the extruded tubular body at the outer portion of the punch projecting from the dispensing orifice, the sharp edge or the cutting edge of each element then providing the sectioning of the tubular body to form the dose, a so-called evacuation second portion in which the sharp edge or the cutting edge of each element has a movement speed component essentially in a direction parallel to the extrusion direction, and a so-called return portion in which the The sharp end or cutting edge of each element has a displacement velocity component in a direction parallel to the extrusion direction and a displacement velocity component in a direction perpendicular to the extrusion direction. Preferably, the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the distal end of the outer portion of the punch protruding from the dispensing orifice.

Alternatively, the sharp edge or cutting edge through the wall of the extruded tubular body at the outer portion of the punch protruding from the dispensing orifice in the central portion of said outer portion.

According to another alternative, the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the outer portion of the punch protruding from the dispensing orifice, in the proximal portion of said outer portion, ie to near the transition portion of said punch.

Brief description of the drawings

Other details of the invention will emerge more clearly on reading the description which follows, given with reference to the appended drawing in which:

FIG. 1 is a perspective view of the turret, the tool station and the transfer means of a flexible tube assembly device comprising a so-called metering device consisting of an extruder device and cutting means for to separate a dose according to the invention, FIG. 2 is a perspective view of the metering device according to the invention,

FIG. 3 is a diagrammatic elevational view of the metering device according to the invention,

FIGS. 4 to 7 are perspective views of the metering device according to the invention, during the different cutting steps of the extruded tubular body to form the dose,

FIG. 8 is an elevational view of the metering device according to the invention showing the trajectory of the cutting blades,

FIG. 9 is a diagrammatic elevational view of a first alternative embodiment of the metering device according to the invention,

FIGS. 10 to 13 are perspective views of the first alternative embodiment of the metering device according to the invention, during the different cutting steps of the extruded tubular body to form the dose,

FIG. 14 is a diagrammatic elevational view of the first variant embodiment of the metering device according to the invention, showing the trajectory of the cutting blades; FIG. 15 is a diagrammatic elevational view of a second variant of FIG. execution of the metering device according to the invention, representing the trajectory of the cutting blades,

- Figures 16 to 18 are schematic perspective views of a third alternative embodiment of the metering device according to the invention during the different cutting steps of the extruded tubular body to form the dose.

Embodiment of the Invention [0036] An installation for the manufacture and filling of flexible tubes will be described below, and more particularly a device for assembling flexible tubes comprising a metering device according to the invention; However, it is obvious that the metering device according to the invention can be adapted for the determination of any type of cold or hot pasty material such as a thermoplastic (PE, PP, PA, etc.) or an elastomer (Natural or synthetic rubber) for example without departing from the scope of the invention.

With reference to FIG. 1, said assembly device, which is described in greater detail in the applicant's international patent application PCT / EP2016 / 052861, consists of transport means 1 along a so-called main closed trajectory. and a plurality of so-called satellite turrets 2 rotatably mounted on said transport means 1, said satellite turrets 2 having retaining means of a plurality of skirts and each satellite turret 2 being rotated at a predetermined angle around its axis of rotation when said satellite turret 2 reaches at least one predetermined point of the main trajectory. Said transport means 1 consist of a so-called main turret 1 driven in rotation about its vertical axis of symmetry and the retaining means of the satellite turrets 2 consist of hemi-cylindrical cavities 3 whose axes extend parallel to the axis rotation of each satellite turret 2, each cavity 3 having suction means for holding the prefabricated tubular bodies, ie the skirts, in place in said cavities 3. [0038] Furthermore, the device comprises a plurality of mandrels 4 s extending to the right of said retaining means 3 and able to move from a retracted position to a so-called processing position in which said mandrels 4 extend inside the prefabricated tubular bodies, ie skirts. Said device also comprises means for actuating the mandrels 4 from their retracted position to their processing position, said actuating means not being shown in FIG. 1. These means for actuating the mandrels 4 preferably consist of in actuating means mechanical consist of fixed mechanical cams extending around the main turret. However, said means for actuating mandrels 4 may consist of electrical and / or pneumatic and / or hydraulic actuating means without departing from the scope of the invention.

Said assembly device comprises work stations 5 extending above the main turret 1 and satellite turrets 2, and a load turret 6 and a discharge turret 7 positioned on the periphery of the main turret 1. Said main turrets 1, charge 6 and discharge 7 all run continuously. Preferably, the tangential velocity of the skirts in the cavities of the charge and discharge turrets 6 is substantially identical to the tangential speed of the skirts in the outer cavities 3 of the satellite turrets 2, which allows easy transfer of the skirts.

The cavities of the load 6 and discharge turrets 7 are provided with gripping members comprising a slot, not shown in the figures, through which a vacuum is exerted to achieve suction and optionally blowing, this to ensure effective attachment (suction) or withdrawal (blowing) of the skirts.

Each satellite turret 2 has the same batch of workstations 5.

Each batch of workstations 5 includes one or more workstations which will perform successively the different steps to assemble the tube components. The work stations 5 are movably mounted along an axis of vertical displacement so as to come into contact with the tube components as soon as the satellite turret 2 is no longer in rotation or in radial displacement, and to clear the satellite turret 2 just before the start of the rotation of the latter. It is obvious that the means of transport 1 may be substituted by any other means of transport well known to those skilled in the art without departing from the scope of the invention. Moreover, with reference to FIGS. 2 to 7, one of the tools of the work stations 5 of the assembly device consists of a so-called dosing unit 8 which is positioned above the stopping point of the satellite turrets. 2. This dosage unit 8 produces doses of plastic material of a toric shape, that is to say a tubular or annular shape, with a central hole more commonly called "donut" or "rolling". The metering unit 8 is composed of an extruder 9 for melting the plastic granules and continuously transferring this viscous material under high pressure into a metering head 10 also called extrusion die. Said metering head 10 will extrude a tubular or annular body of plastic material vertically downwards around a punch 1 1 extending from the dispensing orifice 12, coaxially with said extrusion orifice 12, projecting from this latest. This punch 1 1 therefore extends inside the dispensing orifice 12 and has a first inner portion 1 1a cylindrical diameter slightly smaller than the inner diameter of the dispensing orifice 12 and a second so-called outer portion 1 1 b also cylindrical in diameter greater than the inner diameter of said dispensing orifice 12, the transition between the inner portion 1 1 a and the outer portion 1 1 b of the punch 1 1 in the form of a truncated cone 1 1 vs.

Advantageously, and depending on the behavior of the extruded material, for example depending on its viscosity, an air knife 13 is created around the punch 1 1 facilitating the advancement of the material of the extruded tubular body against the bottom without having a gluing effect on said punch 1 1. This air gap 13 is created under the effect of the rapid exit of the material to the dispensing orifice 12 as a function of space and geometry between the punch 1 1 and the extrusion die. The metering unit 8 also comprises a cutting device 14 which cuts the tubular body in equal lengths so as to create doses of annular or tubular shape, which are then directly deposited successively on the mandrel heads 4. Ledit cutting device 14 placed under the metering head 10 comprises a gearbox actuated for example with a servomotor which drives two axes opening out of the gearbox. On each axis is a blade holder 15 respectively carrying a blade 16 so that said blades 16 are found on either side of the punch 1 1.

These blades 16 perform a movement along a closed path with a velocity component perpendicular to the extrusion direction and a velocity component parallel to the extrusion direction, the extrusion direction being parallel to the axis of the extrusion head. extrusion, and directed downwards in this embodiment, with respect to the tubular body extruded continuously around the punch 1 1, approaching each other until touching, thereby cutting the tubular body extruded around the outer portion 1 1 b of the punch 1 1, just below the transition portion 1 1 c of said punch 1 1.

It will be observed that the blades 16 may not touch, but overlap slightly, a few hundredths of a millimeter, without departing from the scope of the invention. Thus, at first, when the blades 16 are close to the punch 1 1, at the outer portion 1 1 b of the punch 1 1, just below the transition portion 1 1 c of said punch 1 1 , the trajectory made by the cutting edge of each blade 16 is substantially horizontal with a displacement speed component perpendicular to the extrusion direction and a displacement speed in the extrusion direction, ie downwards, substantially identical to the rate of displacement of the extruded tubular body continuously until the extruded tubular body is severed to form a dose. The thus obtained cup is clean without stretching the extruded tubular body. Indeed, during the cutting movement, the relative speed between the cutting edge of each blade 16 and the extruded tubular body is zero.

In a second step, when the blades 16 move away from the punch 1 1, the path performed by the cutting edge of each blade is also carried out horizontally but with a component of movement speed against the bottom much larger than the speed of displacement of the tubular body with a great acceleration at the beginning of the movement, decreasing rapidly thereafter, thus creating a propulsion of the dose against the bottom and a fast and safe removal, on the chuck heads thanks to the accompaniment blades.

This movement can be obtained by means of a linkage suitably placed and driven by a continuously rotating shaft adapted to move perpendicularly and parallel to the extrusion direction for example and by any other equivalent means.

Preferably, the blades 16 are perforated towards the center of the cutting edge of the blade 16 of a half-moon shape to the dimension slightly greater than the diameter of the outer portion 1 1b of the punch 1 1, so that when the blades 16 touch or overlap, an infinitely small game resides between the blades 16 and the punch 1 1. Thus, each blade 16 has a hemi-circular opening 17.

However, it goes without saying that the opening 17 may have any shape corresponding to the shape of the cross section of the punch 1 1. Moreover, the ajour 17 is not necessarily in the central part of the cutting edge. of the blade 16 without departing from the scope of the invention. By infinitely small clearance is meant a set of a few hundredths of a millimeter to a few tenths of a millimeter depending on the external diameter of the extruded tubular body to be cut. This cutting system thus guarantees the central hole in the dose. Note that the devices of the prior art are likely to close the central hole, because when the blades come into contact with the tubular body, they crush and bring closer the walls of the tubular body thus closing the central hole. However, the central hole is essential to ensure proper molding of a tube shoulder with a hole in a skirt.

It will be observed that, in this particular embodiment, the cutting device comprises two blades 16 extending on either side of the punch 1 1, symmetrically on either side of the axis of the head. extrusion, ie on either side of the flow axis of the extruded tubular body; however, it is obvious that the cutting device may comprise more than two blades 16 without departing from the scope of the invention.

Furthermore, the horizontal and vertical movement of the blades 16 may be sequential and not combined without departing from the scope of the invention.

Referring to Figure 8, the closed path (T) of the cutting edge of the blades 16 comprising at least three distinct parts, a first portion (T1) said section in which the sharp edge or the cutting edge of each blade a displacement speed component essentially in a direction perpendicular to the extrusion direction until the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the outer portion 11b of the punch 1 1, a second part (T2) called evacuation in which the sharp edge or cutting edge of each blade 16 has a movement speed component essentially in a direction parallel to the extrusion direction, ie downwards in this example of realization, the sharp edge or sharpness of each blade 16 then providing the sectioning of the tubular body to form the dose when said blades reach the punch 1 1, and a third part (T3) said return in which the sharp edge or the cutting edge of each blade 16 has a displacement speed component in a direction parallel to the extrusion direction and a displacement speed component in a direction perpendicular to the extrusion direction away from the punch 1 1 to move the cutting edge of each blade 16 to its initial position for a new cycle. According to a first variant embodiment of the device according to the invention, with reference to FIGS. 9 to 13, the linkage driving the blade holders 15 is chosen in such a way that the movements of the blades 16 are modified so as to obtain a sectioning tubular body extruded vertically from top to bottom and not laterally as described in the previous variant. In a first step, (FIG. 10) the blades 16 are brought into concentric contact with the dosing head 10 just above the beginning of the formation of the extruded tubular body on the punch 1 1. To do this, the blades 16 are moved along a closed path with a travel speed substantially perpendicular to the extrusion direction. In a second step (figure

1 1), the path performed by the cutting edge of each blade 16 is performed with a movement speed substantially parallel to the extrusion direction, ie against the bottom, with a displacement speed component substantially identical to the moving speed. of the extruded tubular body until the extruded tubular body is severed, the sectioning of the extruded tubular body being performed when the cutting edge of each blade 16 is at the height of the base of the punch 1, which corresponds to the location or the space between the cutting edge of each blade 16 and the punch 1 1 is virtually zero. The cut thus obtained is clean and without stretching of the extruded tubular body. Indeed, during the cutting movement, the relative speed between the cutting edge of each blade 16 and the extruded tubular body is zero. In a third step, (Figure 1 1) when the blades 16 move away from the Punch 1 1, the trajectory made by the cutting edge of each blade 16 is carried out horizontally with a component of speed of movement against the bottom much larger than the speed of displacement of the extruded tubular body with a large acceleration at the beginning of the movement, s rapidly attenuating thereafter, thus creating a propulsion of the material dose against the bottom and a quick and safe removal, on the chuck heads (FIG. 13) thanks to the accompaniment of the blades 16.

It will be observed that, in the same manner as above, the horizontal and vertical movement of the blades can be sequential and not combined without departing from the scope of the invention.

Furthermore, it will be observed that the two blades 16 may be substituted by another cutting element such as a ring in at least two parts, each portion of the ring having a sharp or sharp edge without departing from the scope of the invention.

In addition, it will be noted that the cutting zone of the extruded tubular body, ie the position in which the blades 16 come into contact or overlap, can be located at any point on the punch 1 1, namely on the transition portion 1 1 c and the outer portion 1 1b of the punch 1 1, but also just below the distal end of the outer portion 1 1b of said punch 1 1 without departing from the scope of the invention.

Referring to FIG. 14, the trajectory performed by the sharp edge or the cutting edge of each blade 16 is thus a closed trajectory (T) comprising at least three distinct parts, a first portion (T1) called a cutting section in wherein the sharp edge or cutting edge of each blade 16 has a displacement velocity component substantially in a direction perpendicular to the extrusion direction until the sharp edge or cutting edge extends to the right of the head dosing 10, a so-called evacuation second portion (T2) in which the sharp edge or the cutting edge of each blade 16 has a displacement speed component essentially in a direction parallel to the extrusion direction, the sharp stop or the cutting edge of each blade 16 providing the sectioning of the tubular body to form the dose when said blades 16 reach the dispensing orifice 12, and a third part (T3) said return in which the sharp edge or the cutting edge of each blade 16 has a displacement velocity component in a direction parallel to the extrusion direction and a displacement velocity component in a direction perpendicular to the extrusion direction away from the metering head 10 to return the blade 16 to its initial position for a new cycle. Note that in this embodiment shown in FIG.

14, the punch 1 1 has no outer portion 1 1 b, the latter being useless even if it is shown in Figure 9.

According to a second alternative embodiment of the device according to the invention, with reference to Figure 15, the linkage driving the blade holders 15 on which are fixed the blades 16 provides a closed path different from that previously described. In this variant embodiment, the trajectory performed by the sharp edge or cutting edge of each blade 16 is a closed trajectory comprising at least three distinct parts (T), a first portion (T1) called a section in which the edge or the cutting edge of each blade 16 has a displacement speed component in a direction perpendicular to the extrusion direction and a displacement speed component in a direction parallel to the extrusion direction until the stop or the cutting edge of each blade 16 passes through the wall of the extruded tubular body at the transition portion 1 1 c of the punch 1 1 protruding from the dispensing orifice 12, the stop alive or the cutting edge of each blade 16 then providing the sectioning of the tubular body to form the dose, a second part (T2) called evacuation in which the sharp edge or the cutting edge of each blade 16 has a movement speed component essentially in a direction parallel to the extrusion direction, and a third so-called return portion (T3) in which the sharp edge or cutting edge of each blade 16 has a displacement speed component in a direction parallel to the extrusion direction and a displacement velocity component in a direction perpendicular to the extrusion direction away from the metering head 10 to return the blade 16 to its initial position for a new cycle.

According to a third alternative embodiment of the device according to the invention, with reference to FIGS. 15 to 18, the linkage driving the blade holders 15 is chosen in such a way that the cutting edges of the blades 16 perform a circular movement and symmetrical with respect to the extruded tubular body, approaching each other until touching, thus severing the tubular body on the cylindrical portion of the punch 1 1. When the blades 16 move away punch 1 1 (FIG. 14 and 15), the tangential speed of the cutting edge of each blade 16 undergoes a great acceleration, subsequently decreasing, thus creating a propulsion of the dose of material against the bottom and a quick and safe removal, on the chuck heads thanks to to the accompaniment of the blades 16.

[0064] Incidentally, the device according to the invention may include means for cooling the blades in order to prevent any sticking of the material on the blades. These cooling means, not shown in the figures may consist in a water circuit, or any other suitable heat transfer fluid, made in the blade holder for example.

[0065] Advantageously, the device according to the invention may also comprise blowing nozzles placed around the punch and above the sectioned dose blowing down to help set up the dose and avoid sticking on the slides.

Furthermore, it is obvious that the device according to the invention can be used for molding components alone as a shoulder without the body of the tube, the speed of movement of the blades is not necessarily identical to the advance speed of the tubular body.

In addition, the shapes of the tubular body, the dose and parts such as the punch 1 1 may be any and not necessarily circular. The blades 16 can perform a cyclic movement in a specific path and stop at a given moment before starting (blow by blow) or perform a continuous movement.

It will be observed that the skilled person can easily adjust the shape and volume of the dose depending on the cutting rate (length), the extrusion rate of the material (length), the space between the transition part of the punch and the wall of the dispensing orifice (thickness of the wall of the dose), diameter of the punch (internal diameter of the dose).

[0069] Incidentally, said punch may be mounted movably along the extrusion axis by any appropriate means to adjust the thickness of the wall of the dose.

Finally, it is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made without departing from the scope of the appended claims.

Claims

Claims 1. Metering device (8) for plastic or similar material comprising an extrusion head (10) having a distribution orifice (12) commonly called a die and a punch (1 1) extending into the distribution orifice (12) coaxially therewith for continuously extruding a plastic material in the form of a tubular or annular body and cutting means (14) for separating a dose of said plastic material in the form of a tubular or annular section , characterized in that said cutting means (14) consist of at least two elements (16) having at least one sharp or sharp edge, extending on either side of the dispensing orifice (12) , and integral with drive means providing symmetrical movement of said elements (15,16) relative to the longitudinal axis of the extruded tubular body until the tubular body is sectioned by said elements to form a dose.

2. Device according to claim 1 characterized in that the trajectory carried out by the sharp edge or the cutting edge of each element (16) is a closed trajectory (T).

3. Device according to claim 2 characterized in that the sharp edge or the cutting edge of each element (16) comprises, on at least part of the trajectory (T), a component of movement speed in a direction perpendicular to the extrusion direction and a movement speed component in the same direction as the extrusion direction.

4. Device according to claim 3 characterized in that the movement speed component in the same direction as the extrusion direction is substantially identical to the movement speed of the continuously extruded tubular body.

5. Device according to any one of claims 1 to 4 characterized in that, after the sectioning of the tubular body, the trajectory of the sharp edge or the cutting edge of each element (16) comprises a component of movement speed in the direction of extrusion greater than the speed of movement of the tubular body in order to propel the dose in the direction of extrusion.

6. Device according to any one of claims 1 to 5, characterized in that said punch (1 1) comprises at least a first so-called internal cylindrical part (1 1a) of diameter slightly less than the internal diameter of the distribution orifice (12) and a so-called transition part (1 1 c) projecting from the distribution orifice and of frustoconical shape.

7. Device according to claim 6 characterized in that said punch (1 1) comprises a first so-called inner part (1 1 a) cylindrical with a diameter slightly smaller than the inner diameter of the dispensing orifice (12) and a second so-called inner part (1 1 a). exterior (1 1 b) also cylindrical with a diameter greater than the diameter of the interior part (1 1 a), the transition part (1 1 c) between the interior part (1 1 a) and the exterior part (1 1 b) of the punch (1 1) in the form of a truncated cone.

8. Device according to any one of claims 6 or 7 characterized in that each element (16) has an opening (17) positioned at the level of the sharp edge or the cutting edge of said element (16).

9. Device according to claim 8 characterized in that said aperture (17) has the shape of an arc of a circle with a radius of curvature substantially equal to the radius of curvature of the exterior part (1 1 b) of the punch (1 1).

10. Device according to any one of claims 8 or 9 characterized in that said aperture (17) has dimensions slightly greater than the dimensions of the exterior part (1 1 b) of the punch (1 1) so as to provide clearance between said elements (16) and said punch (1 1).

1. Device according to any one of claims 6 to 10 characterized in that the trajectory carried out by the sharp edge or the cutting edge of each element (16) is a closed trajectory (T) comprising at least three distinct parts, a first so-called cutting part (T1) in which the sharp edge or the cutting edge of each element (16) presents a movement speed component essentially in a direction perpendicular to the direction of extrusion until the sharp edge or the cutting edge is located to the right of the extrusion head (10), a second so-called evacuation part (T2) in which the sharp edge or the cutting edge of each element (16) presents a movement speed component essentially in a direction parallel to the direction of extrusion, the sharp edge or the cutting edge of each element (16) providing the sectioning of the tubular body to form the dose when said elements (16) reach the distal end of the transition part ( 1 1 c) of the punch (1 1), and a so-called return part (T3) in which the sharp edge or the cutting edge of each element (16) has a movement speed component in a direction parallel to the direction d extrusion and a movement speed component in a direction perpendicular to the direction of extrusion.

2. Device according to any one of claims 6 to 10 characterized in that the trajectory carried out by the sharp edge or the cutting edge of each element (16) is a closed trajectory (T) comprising at least three distinct parts, a first so-called cutting part (T1) in which the sharp edge or cutting edge of each element (16) has a movement speed component in a direction perpendicular to the direction of extrusion and a movement speed component in a parallel direction in the direction of extrusion until the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the level of the transition part (1 1 c) of the punch

(1 1) protruding from the distribution orifice

(12), the sharp edge or the cutting edge of each element (16) then providing the sectioning of the tubular body to form the dose, a second so-called evacuation part (T2) in which the sharp edge or the cutting edge of each element (16) has a movement speed component essentially in a direction parallel to the direction of extrusion, and a so-called return part (T3) in which the sharp edge or cutting edge of each element (16) has a movement speed component in a direction parallel to the direction of extrusion and a movement speed component in a perpendicular direction to the extrusion direction.

13. Device according to any one of claims 7 to 10 characterized in that the trajectory carried out by the sharp edge or the cutting edge of each element (16) is a closed trajectory (T) comprising at least three distinct parts, a first so-called cutting part (T1) in which the sharp edge or cutting edge of each element (16) has a movement speed component in a direction perpendicular to the direction of extrusion and a movement speed component in a parallel direction in the direction of extrusion until the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the level of the outer part (1 1 b) of the punch (1 1) projecting from the distribution orifice (12), the sharp edge or the cutting edge of each element (16) then providing the sectioning of the tubular body to form the dose, a second so-called evacuation part (T2) in which the sharp edge or the cutting edge of each element (16) has a movement speed component essentially in a direction parallel to the direction of extrusion, and a so-called return part (T3) in which the sharp edge or the cutting edge of each element (16) has a component of movement speed in a direction parallel to the extrusion direction and a movement speed component in a direction perpendicular to the extrusion direction.

14. Device according to claim 13 characterized in that the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the level of the distal end of the external part (1 1 b) of the punch projecting from the orifice of distribution (12).

15. Device according to claim 13 characterized in that the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the level of the external part (1 1 b) of the punch (1 1) projecting from the distribution orifice (12), in the central part of said exterior part (1 1 b).

16. Device according to claim 13 characterized in that the sharp edge or the cutting edge passes through the wall of the extruded tubular body at the level of the exterior part (11b) of the punch (11) projecting from the distribution orifice (12) , in the proximal part of said exterior part (11b), i.e. near the transition part (11c) of said punch (11).