FR3031928A1 - FORMING INSTALLATION COMPRISING A MEASURING DEVICE OF WHICH AT LEAST ONE PART IS JOINED JOINTLY IN MOTION WITH A BODY FOR HOLDING A HOLLOW BODY - Google Patents

Abstract

The invention relates to an installation (10) for forming containers (11) made of thermoplastic material from blanks (13) which run in the installation along a production path passing through treatment stations, the installation comprising: a transport device (20, 22, 14) comprising at least one hollow body holding member (28, 34, 16) (11, 13) which is moved along a closed circuit; a device (42, 66) for measuring a state parameter of the hollow body (11, 13), a moving portion (52, 58, 76) of the measuring device (42, 66) being movable together with a holding member (28, 34, 16A) on at least a portion of said open section of production path; characterized in that the movable portion (52, 58, 76) is jointly mounted in motion with the holding member (28, 34, 16A) on the whole of said closed circuit.

Description

The invention relates to a plant for forming containers made of thermoplastic material. A forming device comprising a measuring device, at least a part of which is mounted jointly in displacement with a body for holding a hollow body. TECHNICAL FIELD OF THE INVENTION , especially by blowing or by stretch-blow molding.

BACKGROUND OF THE INVENTION The invention relates more particularly to a forming plant, in particular by blow molding or stretch-blow molding, of containers made of thermoplastic material from blanks that pass through the installation along a production path passing through the stations. treatment, the installation comprising: - at least one hollow body transport device comprising at least one member for holding a hollow body which is moved along a closed circuit, a useful section of the closed circuit forming a section open production path; at least one device for measuring a state parameter of the hollow body, at least one moving part of the measuring device being movable together with a holding member on at least a portion of said open section of the production path. The invention relates to the manufacture of containers from plastic blanks such as polyethylene terephthalate or "PET". The term "blank" is used here to designate both a preform and an intermediate container which has undergone a first deformation, in particular blow molding, and intended to undergo a second one in order to obtain the final container.

In general, the term "hollow body" refers to a container or a blank. In what follows, it is assumed for simplicity, which is by no means restrictive as to the type of manufacturing used, that the blanks are preforms. The container manufacturing operations comprise, in a known manner, a heating operation in which the blanks are exposed to electromagnetic heating radiation, such as infrared, ultraviolet, radio or even microwave radiation. The electromagnetic heating radiation is emitted by heating elements, such as lamps or diodes, a heating station in which the blanks transit. In order to allow a relatively uniform heating of the blanks, they are hooked by their neck to rotary lines called spinners. At the outlet of the heating station, each blank is introduced hot into a mold where it undergoes a stress forming operation by means of a press forming fluid, for example air or liquid, possibly doubled. stretching performed by means of an elongation rod. The heating of the blanks, also called thermal conditioning, is a delicate operation because of the importance of the temperature of the material for subsequent blowing or blow-molding operations.

On the one hand, the average temperature of the blank must be greater than the glass transition temperature of the material of which it is made (about 80 ° C. for "PET"), so as to allow a biorientation of the material during blowing or stretch-blow molding, while being lower than a temperature (about 140 ° C. for "PET") beyond which the material presents risks of spherulitic crystallization which would render the blank unfit for blowing .

On the other hand, the temperature distribution within the blank itself affects the quality of the final container, and in particular its transparency and the distribution of the material in the body and the bottom of the container. container, which degrades the mechanical performance and barriers of the final container. The temperature distribution has several aspects: on the circumference of the blank (that is to say angularly around the main axis of the blank), axially (that is to say parallel to the axis), and in the thickness of its wall.

Due to the rotation of the blanks during heating, the circumferential temperature distribution is generally uniform, although for some applications it is useful to obtain a non-uniform circumferential distribution. It is also possible to control the heating profile parallel to the axis of the blank, by controlling the power radiated by the heating elements of the heating station. While axial temperature uniformity is generally desired, some applications require non-uniform profiles.

The distribution of the temperature in the thickness of the wall of the blank, on the other hand, is much more complex to control, even though this distribution is essential for the control of blowing or stretch-blow molding. Despite a certain homogenization of the temperature by conduction and / or convection during heating, a temperature gradient generally persists in the thickness of the blank, and the complexity of heat exchange occurring in the heating station as well as the difficulty to measure the heat exchange coefficients (with the air within the blank, and with the air 30 outside thereof) have not made it possible to model with sophistication the distribution of the temperature in At the present time, the solutions proposed to allow a better control of the temperature distribution in the thickness of the wall are, however, unsatisfactory from one point of contact. industrial view because of implementation too complex. Samples must be taken from the production line to allow spot measurements, partly manual, on a sample of blanks. Samples generate a transfer time from the chain to the test stand, during which the temperature profile is changed (tending to diffusion homogenization), so that the measurements do not accurately reflect the temperature distribution. within the drafts present on the production line. As for the measurements made on the fly, they require expensive sensors whose reliability of measurements remains to be demonstrated, especially with regard to the temperature of the inner wall of the blank, measured remotely and instantly by the outside. of it. It has also been proposed to install a carousel of sensors 20 rotating opposite the passage of the blanks. Thus, the sensors accompany the blanks over part of their path, allowing accurate measurements to be made using inexpensive sensors. Nevertheless, the manufacture of such a carousel and its synchronization with the transport means of the blanks makes its design expensive and not easy. Such a carousel of sensors is also bulky. Moreover, the geometry of the blanks entering the heating station also influences the heating profile. Thus, it happens that the blanks of the same batch have dimensional anomalies that influence the heating profile.

It would therefore be advantageous to detect such anomalies as soon as the blanks enter the heating station to adapt the heating to their dimensions. The invention aims in particular to overcome the aforementioned drawbacks, by proposing a solution for measuring with increased reliability the wall temperature of a blank. The invention makes it possible to carry out these measurements by means of a compact, simple and inexpensive device. BRIEF SUMMARY OF THE INVENTION The invention thus proposes an installation of the type described above, characterized in that the movable part is mounted jointly in displacement with the holding member 15 on the whole of said closed circuit. According to other features of the invention: the holding member is embedded on a mobile support, the mobile part of the measuring device being also embedded on said mobile support; The measuring device comprises at least one measuring sensor; the measuring sensor forms a mobile element jointly with the holding member along said closed circuit; The measuring device comprises a transmitter of a signal measured by the sensor; the transmitter forms a mobile element jointly with the holding member along said closed circuit; one of the emitter and the sensor forms a movable element together with the holding member along said closed circuit, while the other of the two elements forms an element independent of the holding member; The transport device ensures the transfer of hollow bodies without treatment between two treatment stations; - The transport device is part of a forming station which comprises a plurality of holding members 5 each comprising a mold; in the mold which is associated with the onboard measuring device, the forming means are inactive, the unformed blank being ejected from the production path after having traversed the entire section of the production path followed by the mold; The transport device comprises a plurality of holding members, only part of the holding members being associated with a measuring device; the transport device comprises a plurality of holding members, all of the holding members being associated with a measuring device. BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become apparent upon reading the following detailed description for the understanding of which reference will be made to the appended drawings in which: FIG. 1 is a diagrammatic view from above which represents a container forming installation carried out according to the teachings of the invention; FIG. 2 is a cross-sectional view showing, in detail, a device for measuring the temperature of a blank; FIG. 3 is a view from above which represents a transfer wheel 30 of the installation of FIG. 1 on which each holding member is associated with a device for measuring the temperature; FIG. 4 is a view similar to that of FIG. 2, which shows a device for measuring the thickness of the wall of a blank; FIG. 5 is a view similar to that of FIG. 3 which represents another transfer wheel of the installation of FIG. 1 in which each holding member is associated with a device for measuring the thickness of a wall; FIG. 6 is a cross-sectional view showing a molding unit of a forming station of the forming plant of FIG. 1 in which the molding unit is equipped with means for forming a container. final assets; FIG. 7 is a view similar to that of FIG. 6 in which the molding unit is equipped with a device for measuring the internal and external temperature of a blank. DETAILED DESCRIPTION OF THE FIGURES In the rest of the description, elements having an identical structure or similar functions will be designated by the same references. In the remainder of the description, it will adopt, without limitation, and locally for each hollow body, longitudinal orientations directed in the direction of displacement of the hollow body, vertical and transverse indicated by the trihedron "L, V, T" FIGS. 2, 4, 6 and 7. Thereafter, the term "on-line measurement" of a state parameter means that said state parameter of a blank is measured while the blank is running continuously and without slowing down the production path. Subsequently, the term "holding member" means gripping member or support member of a blank which is capable of transporting the blank from one point to another.

FIG. 1 shows a plant 10 for forming containers 11 of thermoplastic material, such as "PET", from blanks 13. The blanks 13 are generally made beforehand by injection molding, in the form of preforms. These preforms are generally cold when they are delivered to the inlet of the forming apparatus. The installation 10 mainly comprises a heating station 12 and a forming station 14 provided with a plurality of molding units 16 mounted on the periphery of a carousel 18. Non-limitingly It is a forming installation 10 of containers 11 continuously, as opposed to an installation operating sequentially with regular interruptions of the displacement of the blanks 13. In other words, the blanks 13 are constantly in motion between their entry into the installation and their exit under 11. This provides a greater flow rate of production of containers 11. For this purpose, the installation comprises several hollow body transport devices which are described later. Alternatively, the invention is applicable to an installation operating sequentially. The installation 10 comprises a first transfer wheel 20 at the inlet of the heating station 12, a second transfer wheel 22 at the outlet of the heating station 12, and a third transfer wheel 24 interposed between the second wheel 22. transfer and forming station 14. Finally, a fourth transfer wheel 25 is arranged at the exit of the forming station 14 to transfer the containers 11 to a conveyor 27 such as a carpet or an air conveyor. The blanks 13 scroll in the installation 10 according to a given production path which is shown in bold line in Figure 1.

The blanks 13 arrive successively one after the other by a ramp 26 which feeds the first transfer wheel 20, forming a first device for transporting the hollow bodies. The first transfer wheel 20 is in the form of a disc 21 whose periphery is equipped with several support notches each forming a member 28 for holding a blank 13. The holding members 28 are thus embarked on the 21. The disk 21 is rotatably mounted about a vertical central axis "A" in a counterclockwise direction with reference to FIG. 1. The holding members 28 thus move in a closed circle-shaped circuit around the vertical axis. 'A' axis. The blanks 13 are conveyed from the ramp 26 to an inlet of the heating station 12 along the production path. When a blank 13 has been transmitted to the heating station 12, the holding member 28 continues its empty motion along the closed circuit to return to its starting point and load a new blank 13. A useful section, shown in bold line in Figure 1, said circuit forms an open section of the production path. In variant not shown of the invention, the holding members of the first transfer wheel are formed by grippers gripping a blank. Then the blanks 13 are conveyed through the heating station 12 to be heated prior to the blow-molding or stretch blow molding operations. For this purpose, the heating station 12 is equipped with lamps or diodes (not shown) emitting electromagnetic heating radiation, for example infrared radiation at a predetermined power and on a spectrum. The power and the spectrum are controlled by means of a controller not shown.

Each blank 13 is carried by a rotating hanger, also called a whirlpool, which forms a holding member associated with the heating station 12. Such a holding member 30 conventionally comprises a mandrel (not shown) which is fitted into a neck of the blank 13, as well as a pinion meshing with a fixed rack running along the production path so as to ensure a rotation substantially uniform of the blank 13 during its heating. The holding members 30 are carried by a closed chain 10 which is driven in a clockwise direction by driving wheels 32 which are rotatably mounted about vertical "B" axes. This chain of holding members 30 set in motion thus forms a second device for transporting the hollow bodies. Each holding member 30 is moved continuously, i.e. without interruptions, along a closed circuit. A useful section, shown in bold line in Figure 1, said circuit forms an open section of the production path. At the outlet of the heating station 12, the hot blanks 13 are transmitted to the second transfer wheel 22 which has a structure similar to that of the first transfer wheel 20. This second transfer wheel 22 forms a third device for transporting the hollow bodies. After transmission of the hot blank 13 to the second transfer wheel 22, each holding member 30 of the heating station 12 continues its empty path along the closed circuit to return to its starting point and load a new one. The second transfer wheel 22 is in the form of a disk 23, the periphery of which is equipped with a plurality of support notches each forming a member 34 for holding a blank 13. The holding members 34 are thus embedded. on the disk 23.

The disc 23 is rotatably mounted about a vertical central axis "C" in a counterclockwise direction with reference to FIG. 1. The holding members 34 thus move in a closed circuit of circular shape around the axis. "VS".

The blanks 13 are conveyed from the outlet of the heating station 12 to the third transfer wheel 24 along the production path. When a blank 13 has been transmitted to the third transfer wheel 24, the associated holding member 32 continues its empty motion along the closed circuit to return to its starting point and load a new blank 13. useful, shown in bold line in Figure 1, said circuit forms an open section of the production path. As a variant not shown of the invention, the holding members of the second transfer wheel are formed by grip grippers of a blank. At the outlet of the second transfer wheel 22, the hot blanks 13 are transmitted to the third transfer wheel 24. This third transfer wheel 24 forms a fourth hollow-body transport device. Thus, the third transfer wheel 24 is in the form of a central hub whose periphery is equipped with several arms 36 radiating from the hub. The free end of each arm 36 is equipped with a clamp forming a member 38 for holding a blank 13. The hub is rotatably mounted about a vertical central axis "D" in a clockwise direction with reference to FIG. Figure 1. The holding members 38 thus move in a closed circuit around the axis "D". The arms 36 are able to pivot about a vertical axis 30 relative to the hub or to extend telescopically to allow the spacing between two blanks 13 to be varied.

The blanks 13 are thus conveyed from the transfer wheel 22 to the forming station 14 along the production path. When a blank 13 has been transmitted to the forming station 14, the associated holding member 38 continues its empty motion along the closed circuit to return to its starting point and load a new blank 13. A useful section , shown in bold line in Figure 1, said circuit forms an open section of the production path. Upon transfer to the forming station 14, each blank 13 is inserted into one of the molding units 16 of the forming station 14. The molding units 16 are driven in continuous and regular motion around the vertical axis "E" of the carousel 18 in a counterclockwise direction with reference to FIG. 1. The molding units 16 thus move in a closed circuit 15 of FIG. circular shape around the axis "E". The carousel 18 equipped with its molding units 16 thus forms a fifth device for transporting the hollow bodies. Each molding unit 16 thus forms a blank holding member 13 which is embedded on the carousel 18.

During their forming, the blanks 13 are thus conveyed from the third transfer wheel 24 to the fourth transfer wheel 25. During their conveying, the blanks 13 are converted into containers 11 by forming means which will be described schematically thereafter.

When a container 11 has been transmitted to the fourth transfer wheel 25, the associated molding unit 16 continues its empty motion along the closed circuit to return to its starting point and load a new blank 13. 1, said circuit forms an open section of the production path. At the exit of the forming station 14, the containers 11 are transmitted to the fourth transfer wheel 25 which has a structure identical to that of the first transfer wheel 20.

This fourth transfer wheel 25 forms a sixth device for transporting the hollow bodies. Thus, the fourth transfer wheel 25 is in the form of a disc 29 whose periphery is equipped with a plurality of notches each of which forms a member 40 for holding a blank 13. The holding members 40 are thus embarked on the Disc 29. The disc 29 is rotatably mounted about a central axis "F" vertical in a clockwise direction with reference to Figure 1. The 10 holding members 40 and move in a closed circuit of circular shape around the axis "F". The blanks 13 are thus conveyed from the exit of the forming station 14 to the conveyor 27 along the production path. When a blank 13 has been transmitted to the conveyor 27, the associated holding member 40 continues its empty motion along the closed circuit to return to its starting point and load a new blank 13. A useful section, shown in FIG. bold line in Figure 1, said circuit forms an open section of the production path.

As a variant not shown of the invention, the holding members of the fourth transfer wheel are formed by clamps. The installation 10 comprises at least one device for measuring at least one state parameter of the hollow bodies in order to improve the quality of the final container 11 obtained. As will be described in more detail below, the measuring device comprises at least one sensor, or, alternatively, at least one pair of elements formed by a transmitter and an associated sensor. According to a first embodiment of the invention shown in FIGS. 2 and 3, the installation 10 comprises a plurality of devices 42 for measuring the temperature. The measuring devices 42 are here arranged to measure the temperature of blanks 13 carried by the second transfer wheel 22, after their exit from the heating station 12. Each measurement device 42 is here formed of a single mobile part 43 which is embedded on a transport device, here the second transfer wheel 22, which transfers the blanks 13 without treatment between two treatment stations. The heating of the blanks 13 is carried out in such a way that the parts to deform the blanks 13 have at the input of the forming station 14 an average temperature greater than the glass transition temperature of the material (ie about 80.degree. "FART"). The quality of the final container 11 depends largely on the quality of the heater. On the other hand, a non-optimized heating of the blanks 13 can cause, at least, defects in the shape of the final containers 11, or even inadaptation of the blanks 13 to blow-molding. More specifically, one of the essential parameters to take into account to ensure the success of the blow molding or the stretch-blow molding is the temperature distribution in the thickness of the blank 13.

In the absence of optimization, the ordinary temperature profile generally has a strong gradient between the inner wall and the outer wall of the blank 13, with a comparatively higher temperature on the outer wall. The inventors have found that the final container 11 exhibited good visual and structural qualities (in particular a good transparency and a relatively homogeneous thickness) if the temperature distribution had an optimized profile having a small gradient between the inner wall and the outer wall, and presenting a comparatively higher temperature in the inner wall. Control of this distribution can be achieved by adjusting various parameters of the heating station 12, in particular: the ventilation setpoint (cooling) of the blanks 13, the thermal stabilization time of the blanks 13, the time of exposure of the blanks 13 to the radiation, 5 and - the speed of rotation of the blanks 13 on themselves. These adjustments are made manually or automatically on the basis of temperature measurements made on the blanks 13 at the output of the heating station 12 under the conditions which will now be described. An example of a device 42 for measuring the temperature made of a single moving part 43 is shown in FIG. 2. The movable part 43 of the measuring device 42 comprises a tubular probe 44 intended to be introduced into a hollow body , here a blank 13, to perform in the blank 13 a temperature measurement on the inner wall 46 thereof. The probe 44 comprises a hollow cylindrical body 48 extending along a main vertical axis and surmounted by a head 50 in which is mounted, at the junction with the body 48 at an upper end thereof, an infrared sensor 52 coupled to a signal processing electronics (not shown). According to the embodiment illustrated in Figure 2, the measuring device is a single-sensor, the body 48 of the probe 25 forming a waveguide formed by a cylindrical inner wall lined with a reflective coating. A mirror 54 is mounted in the body 48 away from the sensor 52, at a lower end of the waveguide. The mirror 54 is disposed at and opposite a window 56 formed in the body 48 and is inclined, with respect to the vertical axis, by an angle of approximately 45 °, so that the infrared radiation penetrating through the window 56 perpendicular to the axis of the body is collected by the mirror 54 and reflected by the latter substantially parallel to the vertical axis 3031928 16 towards the sensor 52. This configuration makes it possible to take a temperature at an altitude The angle of inclination of 45 ° of the mirror 54 is here given by way of example, the return of the right-angle wave 5 corresponding to greater architectural simplicity. of the measuring device. The movable part 43 of each measurement device 42 also comprises a second sensor 58 arranged to take a temperature measurement on the external wall 60 of the blank 13 at the same level as the internal temperature measurement, so as to have above an absolute temperature measurement, an evaluation of the temperature difference between the inner wall 46 and outer wall 60. The internal and external measurements are made at the same level, that is, at the same cylindrical coordinates on the blank 13 (same height and angle). For this purpose, the two sensors 52, 58 are arranged radially vis-a-vis. The movable portion 43 of the measurement device 42 comprises a common support 62 on which the internal and external sensors 58 58 are preferably fixed, so as to ensure perfect coincidence of the measurement axes, as well as a synchronized displacement of the sensors 52 and 58 in the vertical direction. The sensors 52, 58 thus belong to the movable portion 43 of the measuring device 42 which is movably mounted together with an associated holding member 34 on at least a portion of said open section of the production path. The movable portion 43 of the measuring device 42 is more particularly mounted jointly in displacement with the retaining member 34 on the whole of said closed circuit.

The measurement sensors 52, 58 thus form moving elements which accompany the holding member 34 along said closed circuit.

To do this, the measurement device 42 is here formed of a single movable portion 43 which is embedded on the disc 23 of the transfer wheel 22. In other words, the measurement device 42 is fixed on the transfer wheel 22 and jointly rotated with the latter. The movable portion 43 of the measuring device 42 also comprises a jack 64 which is fixed on the transfer wheel 22, so that the support 62 of the sensors 52, 58 is capable of being displaced vertically with respect to the associated maintenance 10, the right of a blank 13 gripped by said associated holding member 34. As can be seen in FIG. 2, each measurement device 42 is fixed on the support 62 mounted to slide vertically (for example by means of a cam or, as shown in FIG. 2, of the jack 64) between: waiting position (or high position in the illustrated configuration where the blanks 13 are conveyed neck up), adopted by the measuring device 42 in the buffer section, in which the device 42 extends above the blanks 13 a measuring position (or low position in the configuration illustrated in particular in FIG. 2), adopted by the measuring device 42, in which the device 42 extends at the level of the blanks 13 to enable the temperature to be taken 25 the inner wall 46. According to a variant of the invention, the measurement device 42 is capable of occupying several determined measurement positions. According to another variant not shown of the invention, the second external sensor 58 is fixedly mounted relative to the associated holding member. According to yet another variant not shown of the invention, the second external sensor is slidably mounted relative to the associated holding member independently of the internal sensor. For this purpose, the movable portion 43 of the measuring device comprises a second jack fixed to the transfer wheel which makes it possible to slide the second sensor in a different direction and / or at a time delayed with respect to the sliding of the internal sensor. In the example shown in FIG. 3, the second transfer wheel 22 has a plurality of holding members 34, and all of the holding members 34 are associated with a measuring device 42. Thus, the temperature is measured in line for all the blanks 13 coming out of the heating station 12. In a non-illustrated variant of the invention, the temperature is measured online for a sample of blanks. To do this, only a part of the holding members being associated with a measuring device. For example, one of two holding members of the transfer wheel is equipped with a measuring device, so that the temperature of half of the blanks is measured. According to another example, a single member for holding the transfer wheel on the "x" holding members is equipped with a measuring device. Thus, the temperature is measured every "x" blank. Since the measuring devices 42 are movable together with the blanks 13 carried by the second transfer wheel 22, the measurement of the temperature can be carried out in line for a longer period than "on-the-go" measurements. Thus, the measurement can be made while the blank 13 passes through a portion, if not all, of the useful section of the path of the holding members 34 of the transfer wheel 22, as represented by the sector "S" In addition, since the sensors 52, 58 are mounted directly on the transfer wheel 22, their displacement is naturally synchronized with respect to the displacement of the associated holding members 34. In addition, such an arrangement is inexpensive to manufacture because the drive in displacement of each holding member 34 and the associated measuring device 42 is made by a common drive means. According to a second embodiment of the invention which is represented in FIGS. 4 and 5, the invention is applied to a measuring device 66 able to measure other parameters of the blank 13 such as geometric dimensions, and in particular the height of the blank 13, the thickness of the wall or the diameter of the body of the blank 13. In the example shown in FIG. 5, the device 66 for measuring the geometric parameters is arranged on the first Transfer wheel 20 to verify that the geometry of the blanks 13 entering the heating station 12 complies with a set of specifications. This ensures that the heating station is optimally adjusted according to the geometry of the blanks 13.

According to a not shown variant of the invention, the device for measuring the geometrical parameters is arranged on the fourth transfer wheel to check that the geometry of the containers leaving the molding station complies with a set of specifications, the containers nonconforming, for example being discarded. An example of a device 66 for measuring the thickness of a wall is shown in FIG. 4. The measuring device 66 comprises a first movable part 43 together with the associated holding member 28 along the closed circuit. traveled by the holding member 28. This first portion 43 movable comprises a vertical rod 68, a free bottom end is intended to be inserted in a blank 13 carried by the first wheel 20 of transfer.

The upper end of the rod 68 is attached to a support 70 belonging to said first movable portion 43. The measuring device 66 mainly comprises a transmitter 76 of a signal, for example in the form of a light beam 74, and a sensor 72 able to detect said signal. The lower end of the rod 68 is provided with the sensor 72 able to detect the light ray 74 after passing through the wall of the blank 13 when the rod 68 is inserted therein. The rod 68, and consequently the sensor 72, is embarked on the disk 21 of the first transfer wheel 20. The rod 68 is more particularly slidably mounted vertically in line with an associated holding member 28. The mobile part 43 of the measuring device 66 thus comprises the sensor 72.

The movable portion 43 of the measuring device 66 comprises means (not shown) for sliding the rod 68 relative to the holding member 28, such as a jack or a cam control system, between: a lower measurement position in which the rod 68 is inserted in the blank carried by the holding member; and an upper waiting position in which the lower end of the rod 68 is arranged above the blank 13. The rod 68 is controlled towards its measurement position on the useful section of the path of the organ 28 of associated maintenance. The rod 68 occupies its rest position on the rest of the path of the associated holding member 28. The measuring device 66 also comprises the signal transmitter 76, this being the light ray 74 which is emitted along a radial axis 30 so as to pass through the wall of the blank 13. The emitter 76 is arranged outside the blank 13, facing the sensor 72 which is able to measure the deflection of the beam 74 emitted after its refraction as it passes through the wall of the blank 13. From this deviation, an electronic control unit (not shown) is able to determine the thickness of the wall of the blank 13. In the embodiment of the invention shown in FIG. 5, a single transmitter 76 is arranged in a second fixed portion 77 of the measuring device 66, which is arranged next to the first transfer wheel 20. The transmitter 76 is more particularly arranged on a portion of the useful section of the path of the member 28 holding. This single transmitter 76 10 thus belongs to the second fixed portion 77 of the measuring device 66 which is independent of the member 28 for holding. The measurement is made at the parade. When the blank 13 passes in front of the transmitter 76, the rod 68 occupies its measurement position. The sensor 72 is thus able to intercept the spoke 74 as it passes through the blank 13. In the example shown in FIG. 5, each member 28 for holding the first transfer wheel 20 is associated with an individual movable portion 43. of the measuring device 66, said movable portion 43 comprises a rod 68 carrying a sensor 72. The fixed portion 77 of the measuring device 66 comprising the transmitter 76 is common to all the sensors 72. This arrangement is particularly advantageous because it allows to reduce the manufacturing cost of measuring devices 66 due to the presence of a single common transmitter 76.

In a variant not shown of the invention, the transmitter is on board the first transfer wheel. In this case, each measuring device comprises a single mobile part comprising an individual transmitter coupled with the associated onboard sensor. In this case, the transmitter is for example fixedly mounted relative to the associated holding member, while the sensor is slidably mounted as previously described.

The measuring devices 66 arranged according to this second embodiment advantageously make it possible to introduce the sensor 76 into the interior of the blank 13, which was not possible during measurements taken on the fly, and required 5 use very expensive sensors. According to another variant not shown of the invention, the positions of the transmitter and the sensor are reversed. Thus, the rod carries the transmitter so that the transmitter is arranged inside the blank while the sensor is arranged outside the blank. This position reversal is applicable to all the variants described above. Thus, it is possible to arrange, next to the transfer wheel, a single sensor common to all onboard transmitters. If such an arrangement is satisfactory, however, experience has shown that a more reliable measurement is obtained by arranging the sensor inside the blank and the emitter outside the blank. According to a third embodiment of the invention which is shown in FIGS. 6 and 7, the temperature of a blank sample 13 is measured at the forming station 14. While it is very advantageous to know the thermal profile of a blank 13 as soon as it leaves the heating station 12, it is nevertheless probable that the blank 13 undergoes a modification of its thermal profile as long as it is transported. from the heating station 12 to the forming station 14, for example by cooling its outer face, but also by raising the temperature of the inner wall by thermal conduction. To further improve the quality of the containers 11 produced by the installation 10, the invention proposes to measure the temperature of certain blanks 13 inside a molding unit 16.

To this end, as shown in FIG. 1, one of the molding units 16, which will be referenced 16A thereafter, has been modified to allow measurement to be taken. This modified molding unit 16A, however, will not be able to produce a final container. The blank 13 which is the subject of this measurement will therefore be ejected from the production path downstream of the forming station 14 by ejection means which are already known and which will therefore not be described later. As shown in FIG. 6, a traditional production unit 16 comprises a mold 78 having an impression of the final container. The blank 13 is received in this cavity so that a neck of the blank 13 opens into an upper wall of the mold 78. The mold 78 thus forms a holding member of the blank.

The molding unit 16 also comprises means for forming the blank 13 housed in the mold 78. The forming means comprise a device for injecting fluid under pressure into the blank 13 and a drawing rod 82. from sketch 13.

The injection device comprises a blowing nozzle 80 associated with said mold 78 which is fed with pressurized fluid. The nozzle 80 is embarked on the carousel 18, the nozzle 80 is thus moved together with the mold 78. It is arranged at the neck of the blank 13.

The nozzle 80 is slidably mounted vertically with respect to the mold 78 between an upper standby position in which it is arranged at a distance above the mold 78 so as to allow the insertion of a new blank 13 or else the extracting a finished container 11, and a lower blowing position 30 in which the nozzle 80 is sealingly connected with the blank 13 so as to allow the injection of a press forming fluid during the rotation of the carousel 18. The blank 13 is thus transformed into final receptacle 3031928 24 during its transport on the useful section of the circuit traversed by the molding units 16. In the case of a stretch-blow molding process, the nozzle 80 is further provided with the vertically sliding draw rod 8 which is intended to come into contact with a bottom of the blank 13 to vertically stretch its walls. . The drawing rod 82 is automatically slidably controlled by known sliding means, for example a cam control means or an electric motor.

In the modified molding unit 16A, the forming means are inactive. The modified molding unit 16A is equipped with a measuring device 42 similar to that described in the first embodiment of the invention. This measuring device 42 thus comprises a single moving part 43 which is movable together with the modified molding unit 16A. Thus, the drawing rod 82 has been replaced by the tubular probe 44, intended to be introduced into the blank 13, in order to take a temperature measurement on the inside wall 46 of the latter. The probe 44 comprises the hollow cylindrical body 48 extending along a main vertical axis and surmounted by the head 50 in which is mounted, at the junction with the body 48 at an upper end thereof, the infrared sensor 52 coupled to signal processing electronics (not shown).

The sliding of the probe 44 is controlled by the sliding means of the drawing rod 82 which it replaces. In this configuration, these sliding means thus belong to the measuring device 24. The measurement of the internal temperature of the blank 13 can be performed at different axial height during the descent and / or the ascent of the probe 44. In addition, the nozzle 80 is not fed with pressurized fluid. The measuring device 42 is controlled vertically by the same means as the drawing rod 82 which it replaces. To allow the second sensor 58 to measure the temperature of the outer wall of the blank 13, the associated mold 78 5 has a notch 84 allowing the passage of the sensor 58 during the vertical sliding of the measuring device 42 to its measuring position. The notch 84 is open radially on the outer wall of the blank 13 to allow the measurement of its temperature.

In a variant not shown of the invention, the infrared sensor is pivotally mounted about a vertical axis relative to the blank so that the infrared sensor 52 makes a measurement of the temperature at different points of an annular section of the internal face. This makes it possible to obtain a temperature profile all around the inner face. Such a variant is particularly advantageous when the final container to be obtained has a shape that is not axisymmetric. The pivoting angle is for example between + 180 ° and -180 ° on either side of a reference position in order to allow measurement to be taken all round the blank. In a first design of this variant, the body 48 of the probe 44 is pivotally mounted relative to the holding member of the pivot angle determined about its axis. In this variant, the pivoting of the probe 44 is controlled by a suitable motor when the probe 44 has been slid to one of its measurement positions. According to a second design of this variant, the relative pivoting movement is formed by rotating the blank while the infrared sensor remains fixed in rotation relative to the holding member. According to a third conception of this variant, the relative movement is formed by the simultaneous rotation or pivoting of the infrared sensor and the blank.

During the operation of the installation 10, the blanks 13 delivered to the unmodified molding units 16 are formed by the stretch blow-molding means in final containers 11 as they move along the useful section of the circuit.

At each passage of the modified unit 16A, a blank 13 is loaded into the mold 78, as are the unmodified molding units 16. Along the useful section of the displacement circuit of the modified molding unit 16A, the measuring device 42 is controlled to its lower measurement position so as to perform the on-line temperature measurements. The size of the measuring device 42 replacing the nozzle 80, on the one hand, and the presence of the notch 84 in the mold 78, on the other hand, thus make this modified molding unit 16A unsuitable for the transformation of the Thus, when the modified molding unit 16A reaches the end of the useful section, the mold 78 opens to transmit the unformed blank 13 to the fourth transfer wheel 25. The unformed blank is then ejected from the production path 20 after having traversed the entire section of the production path followed by the mold 78. It will thus be noted that, during the measurement of the temperature of the blank 13, the latter follows the same production path as the other final blanks 13 / containers 11 loaded onto the other unmodified molding units 16. This makes it possible to obtain a very reliable measurement of the temperature of the blanks during their forming on the molding units 16. The invention has been described in application to a forming apparatus comprising a forming station 14 forming the final 11 containers by blow molding or stretch blow molding. The invention is also applicable for containers 11 formed by injection under pressure of a liquid in the previously heated blank.

The invention is also applicable for the measurement of state parameters of finished containers when the installation comprises, downstream of the forming station, labeling, filling and / or capping stations. 5

Claims (12)

REVENDICATIONS1. Apparatus (10) for forming, in particular by blow-molding or stretch-blow molding, containers (11) made of thermoplastic material from blanks (13) which pass through the installation along a production path passing through treatment stations, installation comprising: - at least one hollow body conveying device (20, 22, 14) (11, 13) comprising at least one hollow body holding member (28, 34, 16) (11, 13) which is moved along a closed circuit, a useful section of the closed circuit forming an open section of the production path; at least one device (42, 66) for measuring a state parameter of the hollow body (11, 13), at least one moving part (43) of the measurement device (42, 66) being movable together with a holding member (28, 34, 16A) on at least a portion of said open section of production path; characterized in that the movable portion (43) is jointly mounted in displacement with the member (28, 34, 16A) for holding on the whole of said closed circuit. 2. Installation (10) according to the preceding claim, characterized in that the member (28, 34, 16A) for holding is embedded on a support (21, 23, 18) movable, the portion (43) movable device ( 42, 66) being also embedded on said movable support (21, 23, 18). 3. Installation (10) according to any one of the preceding claims, characterized in that the measuring device (42, 66) comprises at least one sensor (52, 58, 72) measurement. 4. Installation according to the preceding claim, characterized in that the movable portion (43) of the measuring device comprises the sensor (52, 58) measurement. 5. Installation (10) according to any one of claims 3 or 4, characterized in that the device (66) 3031928 29 measurement comprises a transmitter (76) of a signal measured by the sensor (72). 6. Installation (10) according to the preceding claim, characterized in that the portion (43) movable measuring device comprises the transmitter (76). 7. Installation (10) according to claim 5, characterized in that the movable portion (43) of the measuring device comprises one of the transmitter (76) and the sensor (72), while the other both elements belong to a portion (77) of the measuring device which is independent of the holding member (28). 8. Installation (10) according to any one of the preceding claims, characterized in that the device (20, 22) conveys the transfer of hollow bodies without treatment between two treatment stations. 9. Installation (10) according to any one of claims 1 to 7, characterized in that the device (18) is part of a forming station (14) which comprises a plurality of members (16) of holding each having a mold (78). 10. Installation (10) according to the preceding claim, characterized in that in the mold (78) which is associated with the onboard measuring device (42), the forming means are inactive, the unformed blank (13) being ejected. of the production path after having traveled the entire section of the production path followed by the mold (78). 11. Installation (10) according to any one of the preceding claims, characterized in that the device (14) comprises a plurality of transport members (16), only a portion of the holding members being associated with a device (42) measurement. 12. Installation (10) according to any one of the preceding claims, characterized in that the device 3031928 30 (20, 22) for transport comprises a plurality of members (28, 34) for holding, the totality of the organs (28 , 34) being associated with a measuring device (42, 66). 5