DEVICE FOR BLOW MOULDING CONTAINERS

Abstract

The device is used for the blow-molding of containers. A preform made of thermoplastic material, following a thermal conditioning within a blow-mold, is stretched by a stretching rod and is reshaped by effects of blowing pressure into the form of a container. A specification for the positioning of the stretching rod occurs through the use of a linear drive. Blowing pressure is created through the use of at least one positionable blowing gas supply. The linear drive is at least intermittently mechanically coupled with the positionable blowing gas supply and the stretching rod in such a way that coordinated movement kinetics are carried out. The coupling means and the coupled elements are constructed in such a manner that the axis of motion and the resulting force-effect axis form a common spatial axis.

Claims

1: A device for blow-molding a container from a preform made of a thermoplastic material comprising: a stretching rod for stretching the preform, a blowing nozzle for supplying a blowing gas in the preform and for building up a blowing pressure for expanding the preform, and coupling means for coupling the blowing nozzle and the stretching rod to achieve coordinated movement kinetics, wherein a drive motion line of a linear drive motion that is transmitted into the device and axes of motion of the blowing nozzle and the stretching rod run parallel to one another and lay together in a substantially congruent spatial direction such that a common spatial axis is generated.

2: The device according to claim 1, wherein the axes of motion are arranged in a symmetrical central position of the device, in such a manner that a common symmetrical spatial axis is generated relative to the device.

3: The device according to claim 1, wherein the coupling means are mechanical coupling means comprising one drive member, at least one toggle lever and at least one coupling rod.

4: The device according to claim 3, wherein the mechanical coupling means are arranged symmetrically within the device, in such a manner that a resulting line of action of force is congruent with the axis of motion of the stretching rod.

5: The device according to claim 3, wherein the toggle lever and the coupling rod are arranged in such a manner that reaction forces of the blowing nozzle in terms of the common spatial axis are absorbed by the device free of any shear force and torque.

6: The device according to claim 3, wherein the at least one toggle lever, when in its locked setting, is adjacent to a stop and interacts with a holding magnet in such a manner that the at least one toggle lever is maintained in the locked setting.

7: Device (3) for the blow-molding of containers made of a thermoplastic material according to claim 3, characterized by the fact that the at least one toggle lever (10) can be monitored in its locked setting by a limit stop switch (19).

8: The device according to claim 3, wherein the at least one toggle lever is arranged at or in a vicinity of a dead point in the locked setting.

9: The device according to claim 1, wherein the coupling means are made up of fluid coupling means comprising at least one driving cylinder and at least one blowing nozzle cylinder.

10: The device according to claim 9, wherein the at least one blowing nozzle cylinder is arranged in such a manner that a resulting line of action of forces is congruent with the axis of motion of the stretching rod.

11: The device according to claim 9, wherein the fluid coupling means further comprise at least one control unit for controlling fluid flow between the driving cylinder and the blowing nozzle cylinder (36), and wherein fluid is routed through valves and conduits.

12: The device according to claim 9, wherein the driving cylinder has a cylinder rod on a terminal end, wherein the terminal end is received in guidance grooves having a curved cross-section of a drive member in such a manner that in a linear path of motion of the drive member in a direction of the blowing nozzle, a fluid volume of the driving cylinder on a piston-side is displaceable through conduits in a piston-side fluid volume of the blowing nozzle cylinder.

13: The device according to claim 3, wherein a coupling bracket is arranged between the blowing nozzle and the coupling means.

14: The device according to claim 13, wherein the coupling bracket and the drive member are guided on a stretch slide guide.

15: The device according to claim 14, wherein the stretch slide guide is a lubrication-free slide guide.

16: The device according to claim 1, wherein the linear drive motion is transmitted by a linear drive and/or a coupler mechanism.

17: The device according to claim 1, wherein the linear drive motion is transmitted by a coupler mechanism.

18: The device according to claim 17, wherein the coupler mechanism is driven by a rotary drive motor and the linear drive motion is transmitted through a thrust rod in the device.

19: The device according to claim 17, wherein the coupler mechanism comprises a hypocycloid linear guide.

20: The device according to claim 17, wherein the coupler mechanism comprises a Cartwright linear guide.

21: The device according to claim 16, wherein one separation means generates at least one separation plane between the coupling means and the linear drive.

22: The device according to claim 21, wherein the separation means comprises a round latch lock.

23: A blowing station for blow-molding a container from a preform made of a thermoplastic material, the blowing station comprising a control block that is attached to a device according to claim 1.

Description

[0060] Execution examples according to the invention are schematically represented in the Figures. They show:

[0061] FIG. 1 a schematic, abstract representation of a blowing station with the device for the blow-molding of containers from preforms, attached on a valve block and with a drive for the generation of a linear motion or alternatively linear force, which respectively couples the stretching rod and the blowing nozzle through the coupling means,

[0062] FIG. 2 a perspective representation of a blowing station with the device for the blow-molding of containers from preforms, attached on a valve block, in a first preferred embodiment with coupling means in the form of toggle levers and coupling rods in the situation before the linear motion path of the blowing nozzle and the stretching rod,

[0063] FIG. 3 a perspective representation of the blowing nozzle with stretching rod, which extends beyond the blowing nozzle mouth (left figure), the control block with blowing nozzle in a position, before the blowing process (middle image), the control block with blowing nozzle in a position, after the blowing nozzle has travelled the distance of the blowing nozzle stroke HB in the path of motion and has realized the mechanical preload of the sealing element against the support ring of the preform, whereby for illustration purposes both the preform as well as the container are represented (right image),

[0064] FIG. 4 the blowing station in various temporal stages during the blowing procedure from left to right,

[0065] FIG. 5 the detailed representation of the drive members and the coupling means for the blowing nozzle of a first preferred embodiment in various temporal stages during the blowing process from left to right,

[0066] FIG. 6 the detailed cross-sectional representation of the toggle lever locking as a first preferred embodiment of the coupling means,

[0067] FIG. 7 the detailed cross-sectional A-A representation of FIG. 6 with stretch slide guide,

[0068] FIG. 8 a representation of the blowing station with the device for the blow-molding of containers from preforms, attached on a valve block, in a further preferred embodiment with coupling means in the form of toggle levers and coupling rod in the situation before (left image) and after (right image) the linear travel path of the blowing nozzle and stretching rod, whereby a hypocycloid linear guide is interposed between a rotary driven motor and the blowing station,

[0069] FIG. 9 a representation of the blowing station with the device for the blow-molding of containers from preforms, attached on a valve block, in a further referred embodiment with coupling means in the form of toggle levers and coupling rods in the situation following the linear travel of the blowing nozzle for the mechanical preload of the sealing element against the support ring of the preform (left image) and a partial linear motion of the stretching rod (right image), whereby a coupler mechanism in the form of a Cartwright linear guide is interposed between a rotary driven motor and the blowing station, and

[0070] FIG. 10 a representation of the blowing station with the device for the blow-molding of containers from preforms, attached on a valve block, in a further preferred embodiment with coupling means realized through fluid, here hydraulic coupling by means of blowing nozzle and driving cylinders in the situation before (left image) and after (right image) the linear travel path of the blowing nozzle and stretching rod, whereby every previously represented linear drive can be used.

[0071] FIG. 1 shows a schematic abstract representation of a blowing station (40) with the device (3) for the blow-molding of containers from preforms. The preforms are attached on a valve block (2). A drive (41) is used for the generation of a linear motion or alternatively for linear force, which is transmitted through coupling means (44, 45) which respectively couple the stretching rod (9) and the blowing nozzle (5). There is furthermore the schematic representation of the linear stretch slide guide (16) for the guidance of the coupling means (44, 45), the stretching rod (9) and the blowing nozzle (5). The technical teaching according to the invention recognizes that, for the achievement of the easiest possible linear guidance without any lubrication, it is advantageous to arrange the coupling means (44, 45) in a symmetrical manner with respect to a spatial axis (30) and concurrently also both align the linear axes of motion or alternatively force axes (22, 23) of the linear drive (41), of the blowing nozzle (5) as well as of the stretching rod (9) to the same, as well as also in have the same coincide in a spatial direction, in such a manner that only reduced additional torque forces are transmitted to the linear stretch slide guides (16). The illustration of the principle of the blowing station (40) is demonstrated by the symmetrical construction.

[0072] FIG. 2 shows the perspective representation of a blowing station (40) with the device (3) for the blow-molding of containers from preforms attached on a valve block (2), in a first preferred embodiment with coupling means (44) in the form of toggle levers (10) and coupling rods (8) in the situation before the linear travel path of the blowing nozzle (5) and of the stretching rod (9).

[0073] The drive (41) for the generation of a linear motion or alternatively of a linear force is realized in the execution example represented in FIG. 2 by a linear motor (4), which is attached to the device (3) and by means of the posts of the device (17) on the valve block (2). The posts (17) of the device absorb the linear reaction forces of the blowing nozzle (5) and stretching rod (9) during their linear travel paths and, as regards their common spatial axes (30), are symmetrically designed in such a manner that no reactive torque loads are introduced in the construction.

[0074] A further advantage according to the invention can be found in that, upon execution of the blowing procedure, any occurring kickback will be deviated without torque and be supported by means of the toggle lever by the construction.

[0075] A slight tipping that occurs on the basis of inertia is likewise tolerated according to the invention and eventually occurring forces and torque are absorbed.

[0076] The symmetrically-arranged toggle levers (10) are deflected by the linear movable drive member (11) in such a manner that the coupling rods (8) that are movably attached on the toggle levers (10), as a result of the linear motion of the common circular arc path of the coupling points of toggle levers (10) and coupling rods (8), impress, in the direction of the valve block (2), a linear motion on a thrust rod that is equal to the one at the opposite end of the coupling bracket (6) that is movably attached to the coupling rods (8).

[0077] The blowing nozzle (5) that is positively connected with the coupling bracket (6) is likewise moved in a linear manner and thereby realizes the mechanical preload of the mouth-sided sealing element of the blowing nozzle (5) against the support ring of the preform.

[0078] In the left image, FIG. 3 shows a perspective representation of the blowing nozzle (5) with stretching rod (9), which extends beyond the blowing nozzle mouth. The middle image shows the control block (2) with blowing nozzle (5) in a position before the blowing process, which is to say in a positioning that is concentric and above the threaded end of a preform.

[0079] The right image shows the blowing position. When compared to the middle representation, the control block (2) with blowing nozzle (5) in the right image has travelled the distance HB, which is to say the stroke of the blowing nozzle, in the path of motion. In so doing, the mechanical preload of the sealing element against the support ring of the preform is realized.

[0080] FIG. 4 shows the blowing station (40), as represented in FIG. 2, in various temporal stages of the blowing process. The movement kinetics that are made possible by the coupling means (8, 10) will be expounded upon here below as the strokes of the individual components. The linear drive (4) that is shown here, simply as an example, as an electrical linear motor induces a downward linear motion both of the drive member (11) as well as of the stretching rod (9).

[0081] It is preferred when the drive member (11) and stretching rod (9) are positively or force-fittingly connected, so that the induced linear motion drives both equally. In the H0 setting, the drive member (11) is located in its upper position within the device (3). After a travel path H1, the drive member (11) has deflected the toggle lever (10) and as a consequence of the coupled motion by the symmetric coupling rods (8) with the coupling bracket (6), the blowing nozzle (5) is moved into the blowing position by the blowing nozzle stroke HB. Concurrently, the stretching rod (9) is moved a distance of the stroke H1 (HB unequal to H1), it is however arranged in such a manner in relation to the blowing nozzle (5) that the end portion of the stretching rod (9) still does not exit out of the blowing nozzle mouth (5) after the travel path H1.

[0082] Following a travel path H2, the drive member (11) takes on a position beneath the toggle lever (10). The stretching rod (9) is likewise moved the distance of the stroke H2, depending on the relative location prior to the travel path, the tip of the stretching rod protrudes by the amount H2H1x beyond the mouth of the blowing nozzle (5).

[0083] The maximum required linear deflection of the stretching rod (9) is reached following a travel path H3, which is independent of the container height that is to be realized. The linear deflection stroke H3 means the final position for the stretching rod (9) and the drive member (11), in this position the container is both conclusively extended as well as also blown out.

[0084] FIG. 5a through FIG. 5c illustrate, by means of three images, the operating principle and the cooperation of drive member (11) and toggle levers (10). In the H0 setting, the drive member (11) has reached its upper position within the device (3). Following a travel path H1, the drive member (11) has deflected the toggle lever (10) by means of the support roll (13) and locked it. The locking, which is to say, the persistence in the deflected position, occurs when the coupling rods (8) are coupled with the toggle levers in a coupling point (12) in such a manner that in the deflected toggle lever position have travelled up to or beyond the dead point.

[0085] The dead point is defined as the relative situation of the coupling point (12) to the pivot point (15) of the toggle lever (10), in which the force vectors that affect the toggle lever are generated in a manner such that the resulting triangle of forces coincide in a spatial line and only work along this line. On the basis of its linear setting following the motion path H1, the drive member (11) limits the deflection of the toggle lever (10) to the dead point setting since the counter rollers (14) of the toggle lever (10) abut longitudinally. Following a travel path H2, the drive member (11) has released the toggle lever (10).

[0086] FIG. 6 shows the coupling through the toggle lever (10) in a detailed longitudinal section. A linear motion and force is induced in the device (3) and the stretching posts (17) of the blowing station (40) by means of the linear axis of motion (22) of the linear drive (41), here in the form of a linear motor (4). The force and motion axes (22, 23) of the linear motor (4) and the stretching rod (9) have an identical central location. The same also holds true for the resulting line of action of the force of the coupling rods (8) on the basis of their symmetrical and central arrangement, which absorb the blowing nozzle forces (20).

[0087] Given the lack of offset, lever arms are practically non-existent, the sole direction of force application cannot therefore create any appreciable torque or alternatively any tilting moment. In order to be able to ensure the toggle lever stop position at or near the dead point, only limited retaining force is required.

[0088] The teaching according to the invention furthermore suggests holding magnets (24), which are attached to the posts of the device (17) and correspond both with the toggle levers (10) as well as also with the coupling rods (8) in such a manner that the location of the dead point is maintained, as long as there are no forces on the system that exceed the magnetic holding forces. A limit stop switch (19) can be foreseen, to monitor the stop position.

[0089] FIG. 7 represents the A-A cross-section from FIG. 6 and shows an example according to the invention of the constructive design of the stretch slide guide (16), which is here depicted as a round-shaped slide guide. A holding magnet (26) can be foreseen on the drive member (11) on the longitudinal side to the bar posts (17). It is also recognizable from this cross-sectional view that the force and motion effect lines (22, 23) are parallel to one another and are centrally and symmetrically positioned within the device (17).

[0090] FIG. 8 shows the representation of the blowing station (40) with the device for the blow-molding of containers (3) from preforms, attached on a valve block (2), in a further preferred embodiment with coupling means (44) in the form of toggle levers (11) and coupling rods (8) in the situation before (left image) and after (right image) the linear motion path of the blowing nozzle (5) and the stretching rod (9), whereby a hypocycloid linear guide (27) is interposed between a rotary driven motor and the blowing station (40).

[0091] In this embodiment variant, the previously described electric driven motor (4) is thus replaced as the linear drive by a hypocycloid drive (27) and a thrust rod (29). The drive is powered by a rotary, for example, by an electric direct current motor, an alternating current motor or a servomotor (28). A highly-accurate linear guiding of the drive member (11) is not in particular required, due to the use of a thrust rod (29), if necessary combined with separation means (42), which is to say, the previously described stretch slide guide (16) can be omitted in this variant.

[0092] FIG. 9 shows the representation of the blowing station (40) with the device for the blow-molding of containers (3) from preforms, attached on a valve block (2), in a further preferred embodiment with coupling means (44) in the form of toggle levers (11) and coupling rods (8) in the situation following the linear motion of the blowing nozzle (5) for the mechanical preload of the sealing element opposite the support ring of the preform (left image) and after a partial linear motion of the stretching rod (9) (right image), whereby a coupler mechanism in the form of a Cartwright linear guide (30) is interposed between a rotary driven motor (28) and the blowing station (40).

[0093] In this embodiment variant, the previously described electric driven motor (4) is thus replaced as the linear drive by a Cartwright linear guide (30) and a thrust rod (29). The drive is powered by a rotary, for example, by an electric direct current motor, an alternating current motor or a servomotor (28). A highly-accurate linear guiding of the drive member (11) is not in particular required, due to the use of a thrust rod (29), if necessary combined with separation means (42), which is to say the previously described stretch slide guide (16) can be omitted in this variant.

[0094] FIG. 10 shows a representation of the blowing station (40) with the device for the blow-molding of containers (3) from preforms, attached to a valve block (2), in a further preferred embodiment with coupling means (44), realized through fluid coupling, in this case hydraulic, by means of blowing nozzle and cylinders (31, 36) in the situation before (left image) and after (right image) the linear travel path of the blowing nozzle (5) and stretching rod, whereby every previously represented linear drive can be used.

[0095] In the case of these coupling means, the drive member (11) is provided with curved guidance grooves (32), in which the driving cylinder (31) with the end portions of its cylinder rods is guided in such a manner that, in the case of a linear travel path of the drive member (11), the piston-side fluid volume is displaced by means of conduits (33) and an optional control unit (34) as well as valves (35) in a piston-side fluid volume of the blowing nozzle cylinder (36).

[0096] The fluid volumes of the cylinders (31, 36) and the design of the curved guidance grooves (32) are coordinated with one another in such a manner that with a drive member stroke H4, the driving cylinder (31) is stimulated to a stroke distance H5 and that, as a consequence, the piston-side fluid volume that is displaced out of the driving cylinder (31) into the blowing nozzle cylinders (36) forces the stroke H6.

[0097] Response characteristics, movement characteristics and damping can be influenced through the use of control units (34) and/or valves (35). It is however also imaginable to design the cylinders (31, 36) and the conduits (33) in such a manner that no further components are necessary.