METHOD AND APPARATUS FOR THE PRODUCTION OF PLASTIC CONTAINERS WITH NONCIRCULAR CROSS SECTION

Abstract

Plastic preforms are transported during their heating along a predetermined transport path and rotated with respect to their longitudinal axis during transport along a first transport path section to achieve uniform heating of the plastic preforms in the circumferential direction. The plastic preforms remain at least in sections in a predetermined first rotational position with respect to their longitudinal axis during their transport along a second transport path section so that first predetermined circumferential sections of the plastic preforms are heated differently from second predetermined circumferential portions of the plastic preforms. The plastic preforms remain at least in sections in a predetermined second rotational position with respect to their longitudinal axis during their transport along the second transport path section, the first and the second rotational position differing from one another by a predetermined differential angle.

Claims

1. A method for producing plastic containers, wherein plastic preforms are heated by a heating device and subsequently these heated plastic preforms are formed into the plastic containers, wherein the plastic preforms are transported during their heating along a predetermined transport path and wherein the plastic preforms are rotated with respect to their longitudinal axis during transport along a first transport path section in order to achieve uniform heating of the plastic preforms in the circumferential direction and wherein the plastic preforms remain at least in sections in a predetermined first rotational position with respect to their longitudinal axis during their transport along a second transport path section so that first predetermined circumferential sections of the plastic preforms are heated differently from second predetermined circumferential portions of the plastic preforms, wherein the plastic preforms remain at least in sections in a predetermined second rotational position with respect to their longitudinal axis during their transport along the second transport path section, wherein the first and the second rotational position differing from one another by a predetermined differential angle.

2. The method according to claim 1, wherein the differential angle is greater than 20° and/or that the differential angle is less than 160°.

3. The method according to claim 1, wherein the plastic preforms are rotated from the first rotational position into the second rotational position by a mechanical setting device.

4. The method according to claim 1, wherein during a transport of the plastic preforms in the second transport path section, mutually opposite circumferential sections are heated differently at least in sections.

5. The method according to claim 1, wherein the forming device forms plastic containers from the plastic preforms with a cross-section deviating from a circular cross-section.

6. The method according to claim 1, wherein the plastic preforms are cooled at least in sections during their transport along the transport path on their outer surface.

7. The method according to claim 1, wherein a detection device detects a rotational position of the plastic preforms with respect to their longitudinal direction.

8. An apparatus for producing plastic containers, having a heating device which heats plastic preforms, wherein the heating device has a transport device which transports the plastic preforms along a predetermined transport path during their heating, wherein the heating device has at least one heating unit, which is configured to heat the plastic preforms by applying electromagnetic radiation, and wherein the heating device having a rotating device which is configured to rotate the plastic preforms with respect to their longitudinal axis during transport along a first transport path section in order to achieve uniform heating of the plastic preforms in the circumferential direction, and wherein the heating device has a setting device which is configured to cause the plastic preforms to be transported during their transport along a second transport path section at least in sections in a predetermined first rotational position with respect to their longitudinal axis, so that first predetermined circumferential sections of the plastic preforms are heated differently from second predetermined circumferential sections of the plastic preforms, wherein the setting device is configured to cause the plastic preforms to be transported during their transport along the second transport path section at least in sections in a predetermined second rotational position with respect to their longitudinal axis, wherein the first and the second rotational position differ from one another by a predetermined differential angle.

9. The apparatus according to claim 8, wherein the setting device has at least one guide cam which is arranged in a stationary manner, which enables the plastic preforms to be transported in a predetermined rotational position.

10. The apparatus according to claim 9, wherein the guide cam comprises at least three successive curve sections, wherein one of these curve sections is a catching curve section which is configured to align the plastic preforms with respect to the rotational position relative to the longitudinal axis of the plastic preforms, at least one curve section is a first holding curve section which is configured to hold the plastic preforms in the first rotational position during their transport, and at least one curve section is a second holding curve section which is configured to hold the plastic preforms in the second rotational position during their transport.

11. The apparatus according to claim 10, wherein the guide cam has a transfer section which rotates the plastic preforms from the first rotational position into the second rotational position and the guide cam has a further transfer section which is configured to rotate the plastic preforms from the second rotational position into a further rotational position.

12. The apparatus according to claim 8, wherein heating units are arranged at least in sections in the second transport path section on both sides of the transport path of the plastic preforms, wherein these heating units are preferably controllable independently of one another.

13. The apparatus according to claim 8, wherein the apparatus comprises at least one inspection device which is configured for detecting a rotational position of the plastic preforms with respect to their longitudinal direction.

14. The apparatus according to claim 8, wherein the apparatus comprises a forming device which is configured to form the plastic preforms heated by the heating device into plastic containers, wherein said forming device is configured for producing plastic containers with a cross-section deviating from a circular cross-section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Further advantages and embodiments can be seen in the attached drawings.

[0049] In the drawings:

[0050] FIG. 1 shows a schematic representation of an apparatus according to the invention;

[0051] FIG. 2 shows a representation of a holding device for holding the plastic preforms;

[0052] FIG. 3 shows a top view of the holding device from FIG. 2;

[0053] FIG. 4 shows a detailed representation of the heating device;

[0054] FIG. 5 shows a representation of the setting device for changing the rotational position of the plastic preforms;

[0055] FIG. 6 shows an illustration for changing the rotational position of the plastic preforms;

[0056] FIG. 7 shows a further illustration of a holding device for holding the plastic preforms;

[0057] FIG. 8 shows a top view of the holding device from FIG. 7;

[0058] FIG. 9a,b show an illustration for the production of a container;

[0059] FIG. 10a,b show an illustration for the production of a plastic container with an asymmetrical cross-section;

[0060] FIG. 11 shows a schematic representation of an apparatus for producing a plastic container with an asymmetrical cross-section;

[0061] FIG. 12a,b show an illustration of the production of a plastic container with an asymmetrical cross-section on the short sides;

[0062] FIG. 13 shows a representation illustrating the plastic container shown in FIG. 12b; and

[0063] FIG. 14 shows a guide cam arrangement for producing the plastic container shown in FIG. 12b.

DETAILED DESCRIPTION OF THE INVENTION

[0064] FIGS. 1-8 show an apparatus for manufacturing containers according to the internal prior art and serve to illustrate the invention. However, it is noted that all features of the apparatus shown in FIGS. 1-8 can also be used with the invention.

[0065] FIG. 1 shows a schematic representation of an apparatus 1 for manufacturing containers. The reference sign 2 refers to a heating device such as an oven which heats plastic preforms 10. Preferably, this is an infrared heating device. This heating device has a transport device 22, shown only schematically, which is designed here as a circulating chain on which a plurality of holding devices (not shown) are arranged for holding the plastic preforms 10.

[0066] The reference sign 24 indicates a heating unit such as a heating box, which is preferably stationary and past which the plastic preforms are transported. In a preferred embodiment, heating units are also provided on the inside of the transport path.

[0067] In a preferred embodiment, the heating device also has cooling devices which are suitable for cooling a surface of the plastic preforms, for example by applying air. In this way, uniform heating of the plastic preforms along their wall can be achieved.

[0068] As mentioned at the beginning, the plastic preforms are to be heated at preferred areas 10a, here at the areas shown in FIG. 1. For this purpose, the plastic preforms are aligned in their rotation so that some sections 10a are heated more than others.

[0069] The plastic preforms heated in this way are transferred by means of a transport device 14, such as a transport star, to the forming device designated in its entirety as 4. This has a plurality of forming stations 40, which are arranged on a transport device 43 such as a blowing wheel. The plastic preforms are fed into these forming stations or blow moulds and formed into containers.

[0070] Several transport devices such as transport stars, for example at least two and preferably at least three transport devices, can also be arranged between the heating device and the forming device.

[0071] In the area marked K, a correction of the rotational position of the plastic preforms can be made. In the forming device 4, the more heated surfaces of the plastic preforms are aligned with the respective longer sides of the blow moulds. Preferably, the plastic preforms are aligned in such a way that a parting side or parting plane is arranged on the narrow side of the container. The reference sign 28 roughly schematically indicates a drive device or rotating device for rotating the plastic preforms 10 with respect to their longitudinal directions. This drive device can, for example, be designed as a toothed rack which meshes with gearwheels (not shown) which are assigned to the individual holding devices of the plastic preforms.

[0072] Preferably, the holding devices are each equipped with a coupling device (not shown), which can cancel a coupling of the rotational movement of the gearwheel and the individual holding elements such as holding mandrels, so that at least in sections the holding devices 26a (cf. FIG. 7) are freely rotatable.

[0073] The reference sign 40 indicates an alignment device which serves to align the rotational position of the plastic preforms with respect to the holding devices holding them. This alignment device 40 preferably has an inspection device 42 which detects a rotational position of the plastic preforms 10. In addition, a turning device is provided which changes the rotational position of the plastic preforms, in particular turns the plastic preforms into a desired rotational position.

[0074] The reference sign 46 indicates a preform feed device such as a feed rail, which feeds the plastic preforms 10 one after the other to the alignment device 40. The reference sign 48 indicates a separating device which separates the plastic preforms 10 fed in a row. This separating device can be a saw-tooth starwheel.

[0075] The reference sign 50 indicates an optional rotational position alignment device, which can be provided instead of or in addition to the alignment device. This rotational position alignment device is preferably arranged in a deflection area of the heating device 2. The reference sign 52 indicates an inspection device which detects a rotational position of the plastic preforms 10 (held by the holding devices such as, in particular, holding mandrels).

[0076] The reference sign 54 indicates a decoupling device which at least briefly removes a coupling between the drive device 28 and the holding devices so that the plastic preforms are free with respect to their longitudinal directions. The reference sign 56 indicates a rotational position adjustment device which adjusts a rotational position of the plastic preforms to a desired position.

[0077] However, it would also be possible that the drive device, such as a toothed rack, is not present in the area of the deflection and for this reason the holding devices with the plastic preforms arranged on them can rotate freely.

[0078] FIG. 2 shows a representation of a holding device 26, which has a carrier 29 that can be arranged on a circulating transport means such as a transport chain. The reference sign 32 indicates a rotatable plate on which a cam follower 34 is arranged. This plate is rotatable with respect to the longitudinal direction L. This longitudinal direction also corresponds to the longitudinal direction of the plastic preform (not shown).

[0079] The reference sign 36 indicates a gear wheel or a gear rim which can roll with respect to or engage with a (not shown) stationary toothed rack. A coupling device (not shown) can be arranged between this gear rim and the (not shown) holding mandrel, which can decouple the rotary movement of the gear rim from the rotary movement of the plastic preform.

[0080] The reference sign 37 indicates an alignment surface which serves to pre-direct the rotational position of the plastic preform. In this way, a defined rotational position of the plastic preform can be achieved.

[0081] FIG. 3 shows a top view of the holding device shown in FIG. 2. Here again the cam follower 34 is provided, which is arranged on the rotatable plate 32. The gear wheel 36 can also be seen.

[0082] The reference sign P1 indicates a travel path of a corresponding guide curve when an angular correction, for example by 90°, is to be made. The reference sign S1 indicates a curve position for directional heating or preferential heating of certain areas of the plastic preform.

[0083] FIG. 4 shows a detailed representation of the apparatus shown in FIG. 1. The reference sign 30 indicates a setting device which serves to align the plastic preforms or their rotational position. Preferably, this setting device is arranged in the second half of the transport path along which the plastic preforms are transported during their heating.

[0084] FIG. 5 shows a detailed representation of this setting device. Here, it has cam segments 35a, 35b and 35c arranged one behind the other along the transport path T. The reference sign 35a indicates a catching cam which is suitable and intended for catching the cam follower 34 or gripping it in any position. In this catching cam a pre-alignment of the cam follower 34 is carried out. This catching cam 35a is followed by a process curve or a holding curve section 35b, within which the plastic preforms are preferably heated in the given position.

[0085] The process curve or the holding curve section 35b is followed by a transfer curve 35g, which aligns the rotational position of the plastic preforms in a desired shape in order to transfer the plastic preforms to a further transport device 14. In a preferred embodiment, the positions of the process curve and/or the transfer curve can be changed in order to adapt the rotational position to different process conditions.

[0086] In a further preferred embodiment, the apparatus has a drive device to adjust the process curve and/or the transfer curve. For example, an electromotive drive device can be provided which causes an adjustment of the process curve and/or the transfer curve.

[0087] FIG. 6 illustrates the transfer curve by means of which a spindle rotation is initiated in a clockwise direction (top view). As a result, the oven-outer side of the plastic preform in the blow mould will be oriented against the direction of rotation of the blow wheel.

[0088] FIG. 7 shows a further illustration of the holding device. Here again, the guide roller 34 is shown on the rotatable plate 32. The reference sign 26A indicates a mandrel which engages in the mouths of the plastic preforms in order to hold them in place. This mandrel 26a can also have clamping mechanisms which serve to clamp the plastic preform.

[0089] FIG. 8 shows a top view of the holding device shown in FIG. 7. Here again, the guide roller 34 is arranged on an arm 35, which in turn is attached to the plate 32. The guide curves allow a 90° correction of the rotational position of the spindle drive or the guide roller.

[0090] Due to the preferably adjustable or shiftable process curve or the holding curve section 35b (cf. FIG. 5), all concepts described below can also be used to control or adjust the average transfer angle. For this purpose, the drive of the process curve is preferably readjusted depending on a measured transfer angle.

[0091] In this way, for example, process control of preferential heating machines can be carried out (for example, to counteract a drift of the transfer angle during the warm-up of the oven).

[0092] However, new customer objects can also be used on corresponding machines that allow preferential heating.

[0093] FIG. 9a, b show an illustration of the production of a plastic container. This container can also be produced using the apparatus shown in FIGS. 1-8. FIG. 9a shows a top view of a plastic preform 10 to be heated, which has four sections A1, A2, A3 and A4 on its outer surface. Sections A1 and A3 are heated more than sections A2 and A4. The more heated sections A1 and A3 result in the longer container sides A1 and A3 during forming and the less heated sections result in the shorter container sides A2 and A4 (cf. FIG. 9b). The reference sign M indicates a marking arranged on the plastic preform, which can be used to align the rotational position.

[0094] FIG. 10a,b show an illustration for the production of a plastic container. The production of this plastic container is also possible with the apparatus shown in FIGS. 1-8. Here, sections A1 and A3 are also heated differently (sections A2 and A4, however, are heated in the same way and to a lesser extent). More precisely, section A3 is heated even more than section A1. Accordingly, there is also a section A1 that is more stretched (compared to sections A2 and A4) and a section A3 that is even more stretched compared to this section A1 and thus in overall an asymmetrically shaped plastic container.

[0095] FIG. 11 shows a schematic representation of an apparatus for producing such oval cross-sections. The individual features of this apparatus were described in detail in FIGS. 1-8, so reference is made to them here.

[0096] In this process, plastic preforms are first guided through a first heating lane H1 or along the first transport path section T1 in which they are irradiated on one side by heating units and at the same time rotated in order to achieve the required basic thermal level for stretching in the subsequent blow moulding process. After this has been achieved, the rotation is stopped and the plastic preforms are guided through a heating lane H2, more precisely, the left part of the heating lane 2 with irradiation on both sides, i.e. along the transport path section T2. If it is necessary that the sides of the plastic preforms heated during this process do not have the same temperature, this can be very easily implemented in terms of control via the radiator output.

[0097] FIG. 12a, 12b illustrate the production of oval and asymmetrical plastic containers.

[0098] For the production of unevenly shaped, in particular oval, containers with asymmetrical short container side, two opposite sections A1 and A3 with highest temperature and two opposite preform sides with medium (section A4) and lowest temperature (section A2) are required. This heat distribution cannot be achieved by adjusting the radiator power alone.

[0099] Preferably, there are transition areas between the circumferential sections, or between said sections and the sections adjacent to these sections (A1 to A2, A2 to A3, etc.). These transition areas result, among other things, from the not only orthogonally incident IR radiation, but also from thermal conduction and other relationships.

[0100] FIG. 13 illustrates the method proposed within the scope of the invention for the production of such containers. In order to achieve the required heat distribution for the production of oval containers which are at the same time asymmetrical on the short side of the container, a swivel in the preferential heating module, i.e. the heating device 2, is proposed.

[0101] First, the plastic preforms, which have already been uniformly preheated, are fed in on the right side (I). Then the rotary position is held and these plastic preforms are transported (II) past the heating units 4a-4d and heated from both sides. There is significantly more heating at the sections A1 and A3 shown above.

[0102] If desired, the heating units 4a,c can also emit a different radiant power than the heating units 4b,d. In this way, asymmetrical heating of sections A1 and A3 can be achieved.

[0103] In a further step, the plastic preforms are rotated by 90° (III) and now the heating units 4e, 4f heat the sections A2 and A4 shown above more strongly.

[0104] At the outlet of the heating device, plastic preforms therefore result with two strongly heated sections (A1, A3), one moderately heated section (A2) and one weakly heated section (A4).

[0105] FIG. 14 shows an illustration of an actuator for implementing the method described in FIG. 13.

[0106] As already described above, a guide roller at the upper end of the spindles is used to guide the preforms in the heating device 2. Due to the guide rollers on the spindles, which are already in use, the 90° swivel can be carried out very easily via the guide curve above the heating device. For this purpose, the previous nominal position of 45° with respect to the spindle centre point can be changed from outside to 45° inside. In order to maintain the previous overall concept, it is advisable to return to the previous target position at the end of the Preferential Heating process by a −90°-swivel.

[0107] The upper partial illustration in FIG. 14 shows the procedure according to the applicant's internal prior art.

[0108] The bottom illustration shows a method according to the invention. The plastic preforms coming from the right can still have any orientation. A catch cam section aligns the guide roller in such a way that it lags outwards by 45° relative to the spindle centre.

[0109] A first holding cam section 35b holds the holding devices or spindles in this position and thus guides the plastic preforms past the heating units 4a-4d shown in FIG. 13. However, the guide curve section 35b is preferably adjustable along the arrow Y, so that this setting angle can also be changed.

[0110] In a transition section 35c, the rotational position of the plastic preforms is rotated by 90°, which is done by moving the guide roller to a position in which it lags inwards by 45° relative to the spindle centre.

[0111] In this rotational position, the plastic preforms are now heated by the heating units 4e, 4f shown in FIG. 13, which takes place during transport with the holding curve section 35d. In a further optional transition section, the plastic preforms are rotated by −90° to return to the initial position after the catch curve section 35a.

[0112] The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided they are individually or in combination new compared to the prior art. It is further pointed out that the individual figures also describe features which may be advantageous in themselves. The skilled person immediately recognises that a certain feature described in a figure can also be advantageous without adopting further features from this figure. Furthermore, the skilled person recognises that advantages can also result from a combination of several features shown in individual figures or in different figures.