Abstract
The invention relates to a stretch rod for the form-and-fill head of a machine for forming and filling of containers produced from preforms. The object of the invention is to devise a stretch rod of this type which can be cleaned and/or disinfected without being disassembled and without any other intervention. According to the invention, the object is achieved by a stretch rod (5) for the form-and-fill head (3) of a machine for forming and filling (molding and filling) of containers produced from preforms (2), which rod comprises a drive unit for axially moving said stretch rod (5). At least the part (6) of the drive unit which is connected to the stretch rod (5) is arranged in a drive chamber (11) which is sealed off from the regions of the form-and-fill head (3) which come into contact with the filling material (the material with which the container is being filled). The inventive stretch rod is characterized in that the sealing action is achieved by a seal (12) which surrounds the stretch rod (5).
Claims
1. A stretch rod for a form-and-fill head of a machine for forming and filling containers produced from preforms, which rod comprises a drive unit for axially moving said stretch rod, wherein at least a part of the drive unit which is connected to the stretch rod is arranged in a drive chamber which is sealed off from regions of the form-and-fill head which come into contact with filling material, said filling material being material with which the containers are filled, and wherein a sealing action is achieved by a seal which surrounds the stretch rod.
2. The stretch rod according to claim 1, wherein a sealing surface of the seal is in a fixed position and surrounds the stretch rod.
3. The stretch rod according to claim 2, wherein the seal is a cylindrical bellows, roll bellows, or expandable sleeve.
4. The stretch rod according to claim 1, wherein the stretch rod is axially movable relative to the seal, and for a cleaning process is movable into a position in which it is not in contact with the seal.
5. The stretch rod according to claim 4, wherein the stretch rod has an encircling groove in a region which does not come into contact with the seal during a stretching process.
6. The stretch rod according to claim 1, wherein the seal which surrounds the stretch rod is pressure resistant on one side.
7. The stretch rod according to claim 6, wherein the seal is a lip seal.
8. The stretch rod according to claim 1, wherein the drive unit comprises a magnetic coupling, with a first magnet unit connected to the stretch rod and with a second magnet unit, wherein the first magnet unit is disposed in the drive chamber and the second magnet unit is disposed outside the drive chamber.
9. The stretch rod according to claim 8, wherein the second magnet unit is axially displaceable.
10. The stretch rod according to claim 8, wherein the second magnet unit is in a fixed position and a magnetic field of the second magnet is dynamically controllable.
11. The stretch rod according to claim 8, wherein the first magnet unit is supported at a distance from walls of the drive chamber.
12. The stretch rod according to claim 11, wherein the first magnet unit is supported at the distance from walls of the drive chamber by spacer means.
Description
[0026] Some exemplary embodiments of the invention will be described in more detail hereinbelow, with reference to the accompanying drawings.
[0027] FIGS. 1ato 1c illustrate schematically a forming and filling station of a machine for simultaneous forming and filling of bottles produced (being produced) from preforms, with a first embodiment of a stretch rod which permits a CIP cleaning process, in a cross sectional view;
[0028] FIGS. 2a to 2c illustrate schematically a second embodiment of an inventive stretch rod, in a cross sectional view;
[0029] FIGS. 3a and 3b illustrate schematically a third embodiment of an inventive stretch rod, in a cross sectional view;
[0030] FIGS. 4a and 4b illustrate schematically a fourth embodiment of an inventive stretch rod, in a cross sectional view;
[0031] FIG. 5 illustrates schematically a fifth embodiment of an inventive stretch rod, in a cross sectional view;
[0032] FIGS. 6a to 6d illustrate schematically a drive unit for an inventive stretch rod; and
[0033] FIGS. 7a and 7b illustrate schematically yet another embodiment of an inventive stretch rod, in a cross sectional view.
[0034] FIGS. 1a to 1c illustrate schematically a forming and filling station of a machine for simultaneous forming and filling of bottles produced from preforms. The forming and filling station is essentially comprised of the form-and-fill head 3 and the mold 1, within which mold a preform 2 undergoes forming to produce a container, by means of a filling material supplied under pressure.
[0035] FIG. 1a illustrates the start of the forming and filling phase, in which a preform 2 is inserted into a mold 1. The form-and-fill head 3 is comprised of a feed line 4 with a filling valve 26, for liquid filling material which is fed under high pressure, and a stretch rod 5 which can be moved in the axial direction A by means of a drive unit 6. The form-and-fill head 3 is placed on the mouth 8 of the preform 1 in a manner such that a seal is achieved, by means of the seal 7.
[0036] At the start of the forming and filling phase, the stretch rod 5 rests against or almost rests against the bottom 9 of the preform 1. For forming and simultaneous filling of the container, then filling material is fed via the feed line 4 and through the opening of the filling valve 26, under pressure, and the stretch rod 5 is simultaneously forced downward in the axial direction toward the bottom 10 of the mold 1.
[0037] The stretch rod 5 is moved by means of the drive unit 6, not further described here, which is disposed in a closed drive chamber 11 which is closed off against the regions of the form-and-fill head which guide the filling material. In the exemplary embodiment shown, the drive chamber 11 is sealed against the regions of the form-and-fill head which guide the filling material, such sealing being by means of a seal 12 which surrounds the stretch rod 5.
[0038] As illustrated in FIG. 1b, the preform 2 is initially deformed to form a “bubble”, in the course of the forming and filling process. As the deformation proceeds, it is limited by the wall of the mold 1, wherewith the container is formed. During the deformation of the preform, the stretch rod 5 guides the bottom 9 of the preform (namely the bottom of the container 2 undergoing forming), by persistently exerting a moderate stretching force on the bottom 9. As a result, the “bubble” which is being formed cannot be displaced laterally, and thus the forming of the container proceeds in a uniform manner.
[0039] It is necessary to clean the regions of the form-and-fill head 3 which guide the filling material, at regular intervals of time. For this purpose, these regions are rinsed with a cleaning medium; in this connection, a preform is inserted into the mold, unless one intends to clean the mold at the same time.
[0040] The inventive stretch rod can be brought into a position which allows complete cleaning without disassembly or de-mounting of apparatus parts. This position is illustrated in FIG. 1c. For the described purpose, the stretch rod 5 has an encircling constriction, in the form of a groove 13, in a region of the stretch rod which region is not contacted by the seal 12 during the stretching process. In the embodiment illustrated, the groove 13 is disposed below this region.
[0041] In order to make it possible for the seal 12 which surrounds the stretch rod 5 to be properly cleaned, the stretch rod can be moved into a position in which the seal 12 is aligned with the groove 13. For this purpose, the stretch rod 5 can be moved upward from its initial position. Under these circumstances, the seal 12 will no longer be in contact with the stretch rod 5. The stretch rod and the seal 12 will be completely accessible, and can be rinsed with the cleaning medium. For this, the cleaning medium may be introduced through either the filling material line 4 or the cleaning line 14, which cleaning line leads to the chamber 11 through the valve 15 (which may be a check valve), or through a combination of these.
[0042] The preform 2 used for the cleaning process may be an ordinary preform or may have a changed volume compared to ordinary preforms in order to be able to accommodate the volume of cleaning medium used for the cleaning. It is also possible to use a cap (not shown) instead of a preform, which cap preferably has a drain via which the cleaning medium can be diverted or can be recycled in a circulation loop.
[0043] The exemplary embodiment illustrated in FIG. 2a essentially corresponds to the exemplary embodiment according to FIG. 1a, but here the groove 13 is disposed above the region of the stretch rod which region is in contact with the seal during the “stretching” process.
[0044] The stretch rod can then be moved into a cleaning position, as illustrated in FIG. 2b, by moving it downward past its normal end position, so that the groove 13 and the seal 12 are aligned. Once again, a preform 2 for the CIP cleaning is inserted into the mold 1. Since according to this exemplary embodiment the stretch rod 5 must be moved downward farther than usual, the preform 2 used for the cleaning is longer than a usual preform. The mold 1 has a closable opening 16 in its bottom 10, which opening must be opened prior to starting the cleaning operation.
[0045] In order to avoid the need for a modified mold and a special preform as illustrated in FIG. 2b, it is also possible to use an additional “collar” (extension tube insert) 17, disposed between the preform 2 and the forming and filling station 3, for the CIP cleaning, as illustrated in FIG. 2c.
[0046] FIGS. 3a and 3b illustrate a third exemplary embodiment of an inventive stretching rod, which differs from those of the exemplary embodiments of FIGS. 1 and 2 in that the stretching rod 5 has no circumferential groove. However, in this embodiment, the housing of the drive unit is extended upward such that the stretching rod 5 can be moved upward above its starting position, to the extent that it is no longer in contact with the seal 12. CIP cleaning is again possible by introducing a cleaning medium through the filling material line 4 or through the cleaning line 14 leading to the drive chamber 11, or a combination thereof. In the exemplary embodiment according to FIG. 3a, an ordinary preform 2 is used for collecting the cleaning medium. In the exemplary embodiment according to FIG. 3b, instead of being connected to a preform, the form-and-fill head 3 is connected to a separate cleaning cap 24, through which the cleaning medium is collected, and said cleaning medium can be passed through the drain line 25 to a collecting container (not shown) or can be recirculated in a circulation loop. Such cleaning caps can be used with any of the described embodiments of the invention, instead of preforms, with the configuration of the cleaning cap being adjusted to the position of the stretch rod in the cleaning position. It is also possible to employ special preforms having drain means for the cleaning medium.
[0047] If and to the extent that the preform is employed in the mold as a holding element, an opening may be provided in the mold, for drainage.
[0048] The embodiment of the inventive stretch rod illustrated in FIG. 4a has an elastic membrane 18 as a seal, which separates the drive chamber 11 from the regions of the form-and-fill head 3 which guide the filling material. The membrane 18 is applied such that, when the stretch rod 5 is in its starting position, the membrane is un-stressed but is substantially fold-free (FIG. 4a).
[0049] In FIG. 4b the stretch rod 5 is shown in its end position. The membrane is under stress. In both positions, it is possible to carry out cleaning in a CIP process. Here the cleaning medium is introduced through the filling material line 4.
[0050] FIG. 5 illustrates still another embodiment of a stretching rod 5 according to the invention, in which the sealing against the working chamber 11 is accomplished via a “lip seal” 19. The seal 19 is pressure-resistant on one side and from the other side it is permeable at a relatively low pressure. With a forming and filling pressure of up to 40 bar, the seal 19 will seal effectively to protect the drive chamber 11. For cleaning, the valve 15 is opened and a cleaning medium is fed through the cleaning line 14 at a cleaning pressure of up to 2 bar. From the side of the drive chamber 11, the seal 19 does not withstand this pressure and allows flow. The cleaning medium can flow through the seal 19 and can clean all areas.
[0051] To make it possible for the drive chamber 11 to itself be cleaned and disinfected in an easy manner, the part of the drive means 6 of the stretch rod 5 in the chamber 11 should have a structure which is maximally simple and easy to clean. FIG. 6a illustrates an embodiment of a drive unit for a stretch rod, wherein a magnet 6 is disposed on the upper end of the stretch rod 5, which magnet is located within an external magnetic field which can be varied. This variable magnetic field may be generated, e.g., by magnets 20 disposed outside the chamber 11, which magnets may be moved up and down.
[0052] This external magnetic field may also be generated by a coil arrangement 21, as illustrated in FIG. 6b, with the coils therein producing magnetic fields which are variable by means of different signals, and which control the movement of the drive element 6 and thereby the stretch rod 5. Advantageously, in application of the principle of a linear motor, the magnetic element 6 on the stretch rod 5 may be employed as the driven element, for which a permanent magnet may be used, whereas coil elements may be used for the variable magnetic stator.
[0053] FIG. 6c illustrates, in an axial cross section, an exemplary embodiment comprising a magnet 6 disposed on the end of the stretch rod, in the drive chamber 11. The magnet 6 is triangular, wherewith only its corners 22 are in contact with the path in the chamber in which it moves; accordingly, it does not present any appreciable surface area which is not accessible to CIP cleaning. A cleaning medium can be caused to flow around the magnet 6.
[0054] FIG. 6d illustrates a magnet 6 which is held in its path of movement by small spacers 23. Preferably three such spacers are employed (as illustrated in this exemplary embodiment), because this arrangement is sufficient to hold the magnet 6 without entailing an excessive amount of contact surface.
[0055] FIGS. 7a and 7b illustrate still another embodiment of a stretch rod 5 in a form-and-fill head 3. Here the filling material is fed via a feed line 4 which can be closed off by a valve 26. The stretch rod 5 is disposed within the flow path, and during the filling process it is surrounded by the filling material. The stretch rod is driven by a drive element 6 which is coupled to a drive unit (not shown) disposed outside the flow path. Suitable drive possibilities have been described above in connection with FIG. 6. Alternatively, it is possible to drive the stretch rod 5 by pneumatic means.
[0056] On its lower end, the stretch rod 5 has a sealing sleeve 27 which is movably (slidably) disposed on the stretch rod 5 and is sealable by the seal 28. The sealing sleeve 27 can be driven by a drive unit, similarly to the stretch rod 5, which drive unit has a drive element which is fixed to the sealing sleeve 27, which drive element is coupled to a drive unit (drive means) disposed outside the flow path. The coupling may advantageously be by magnetic means, as described above in connection with FIG. 6. Alternatively, the sealing sleeve may be driven by pneumatic means.
[0057] If the stretch rod is moved downward, together with the sealing sleeve 27, out of the position illustrated in FIG. 7a, the sealing sleeve 27 will seal the chamber 11 against the mouth 8 of the preform. A formed and filled container can be separated after the forming and filling from the form-and-fill head, and a new preform may be applied to the form-and-fill head. There will be no risk of filling material which is still present in the chamber 11 flowing out therefrom. The seal 28 seals the sealing sleeve against the stretch rod.
[0058] For carrying out the forming and filling process, the sealing sleeve is moved upward on the stretch rod 5. The outlet opening of the form-and-fill head is opened and made available, wherewith filling material can flow into the preform. The stretch rod 5 can be moved downward at the same time, where it can assist in the axial stretching of the preform.
[0059] The assembly can be cleaned without disassembling it, namely with movement of the stretch rod upward and out of the sealing sleeve (FIG. 7b). The seal 28 is then opened and a path through it is made available. Feeding of the filling material through the feed line 4 can be blocked via the valve 26, and the cleaning medium can be fed via the cleaning line 14, by opening the valve 15. The in-flowing cleaning medium can be collected, as described above, by a preform disposed in the mold which preform may be provided with drain means. Alternatively, a special cleaning cap may be used, as described above.
