Device for heating plastic preforms, holding device for retaining elements for holding plastic containers and method for assembling or disassembling retaining elements and shielding elements

Abstract

Device for heating plastic preforms (10), comprising a transport device (2) which transports the plastic preforms along a predetermined transport path (P), wherein a plurality of holding elements (22) for holding the plastic preforms (10) and a plurality of shielding elements (24) for shielding from heat are arranged on the transport device (2), characterized in that the device (1) has a plurality of support units (30) on which at least a part (22a) of the holding elements (22) and at least a part of the shielding elements (24) are arranged and these support units (30) together with the parts (22a) of the holding elements (22) and the shielding elements (24) arranged thereon are detachable from the transport device (2), wherein the holding elements (22) are holding mandrels which can be inserted into an opening of the plastic preforms (10) in order to hold them.

Description

[0001] The present invention relates to a device and a method for heating plastic preforms. In the plastics processing industry, and particularly in the beverage manufacturing industry, it has long been known that plastic bottles are formed from plastic preforms by blow molding. In this process, these plastic preforms are first heated in a heating device and then expanded in this heated state.

[0002] Various heating devices are known in the prior art. For example, infrared ovens, through which the plastic preforms are transported, and microwave ovens are also known. In such heating devices, a large number of carriers for the individual plastic preforms are typically arranged one behind the other on a main carrier. It is desirable to have a small distance between the adjacent plastic preforms.

[0003] Furthermore, such devices typically also feature shielding elements that protect the openings of the plastic preforms, which are not themselves formed, from excessive heat. However, with such devices, it is often necessary to replace the components at regular intervals. For this purpose, both the retaining elements and the aforementioned shielding plates are replaced individually, which can be quite time-consuming.

[0004] From US patent 2013 / 0200642 A1, an element for gripping vessels is known, comprising: a carrier that moves along a transport path of the vessel; a nose containing a prong that can grip a neck of the vessel, the nose being detachably attached to a lower axial end of the carrier, the nose comprising an ejection plate that is axially slidable around the prong between a draped position, into which it is elastically returned and in which the prong projects axially downwards, and a draped position, in which the prong is axially retracted over an underside of the plate.

[0005] From DE 10 2008 030 863 A1, a method for converting a device for heating a large number of preforms is known. First, a force is applied such that the magnetic holding force of a retaining element, which is magnetically detachable from the head of a transport element for a single preform, is overcome, and the retaining element is released from the head of the transport element. Then, a retaining element of a different dimension is inserted into the transport element, so that the magnetic holding force is established between the retaining element of a different dimension and the head of the transport element. Subsequently, all previous steps are repeated until one of the differently dimensioned retaining elements is detachably attached to each of the transport elements of the device.

[0006] From US Patent 7,284,778 B1, a device for carrying a preform in a temperature-conditioning oven is known, comprising a gripping device equipped with gripping claws that enclose an outer surface of the preform's neck. An inner core is provided that penetrates axially into the interior of the neck over a distance substantially equal to the axial length of the neck, thus forming a lower transverse surface. When the preform is placed on the gripping device, it rests substantially axially at the boundary between the neck and the body of the preform.

[0007] From DE 101 45 456 A1, a device for heating thermoplastic preforms having a support ring for blow molding hollow bodies is disclosed. The device comprises a conveying means, several holding elements arranged on the conveying means and encompassing the head region of the preforms between the support ring and the mouth, and radiant heaters arranged along the path of movement of the preforms held by the holding elements. Each holding mandrel is equipped with a shield, supported by the conveying means, in the form of a baffle located at the level of the support ring and having a bore to accommodate the support ring. Furthermore, a cooling device is provided that directly acts on the exposed head region. This ensures optimal protection of the non-deformable head region of the preforms against impermissible heating.

[0008] The present invention is therefore based on the objective of making it easier or less time-consuming to change the components of such devices for heating plastic preforms.

[0009] This problem is solved according to the invention by means of a device for heating plastic preforms with the features of main claim 1, a holding device for holding elements for holding plastic containers with the features of dependent claim 10, and by means of a method for assembling or disassembling holding elements and shielding elements with the features of dependent claim 11. Advantageous embodiments and further developments of the present invention are the subject of dependent claims 2 to 9 and 12 and 13, respectively.

[0010] An inventive device for heating plastic preforms comprises a transport device that moves the plastic preforms along a predetermined transport path. A plurality of holding elements for retaining the plastic preforms and a plurality of shielding elements for shielding heat (from areas of the plastic preforms) are arranged on this transport device. According to the invention, the device comprises a plurality of carrier units on which at least one part (component and / or portion), in particular two or more parts, of the holding elements and at least one part (component and / or portion), in particular two or more parts, of the shielding elements are arranged. These carrier units, together with the parts of the holding elements and the shielding elements arranged thereon, can be mounted and / or dismounted from the transport device.

[0011] In this way, the respective retaining element and the shielding element can be removed simultaneously (i.e., in a single disassembly step) and / or installed simultaneously (i.e., in a single assembly step). Preferably, each shielding element is assigned to exactly one retaining element. However, it would also be conceivable for one shielding element to be assigned to several retaining elements, or conversely, for several shielding elements to be assigned to one retaining element. Advantageously, the entire shielding element is arranged on the carrier unit. In contrast to prior art devices, the invention makes it possible, for example, to replace the entire carrier unit for a change of accessories. In this way, changeover times can be significantly reduced.

[0012] In other words, it is advantageous that the retaining elements and the shielding elements can be removed together and / or removed or replaced in a combined state.

[0013] It would be preferable for the shielding elements and retaining elements to each be attached to a common holder and, for example, to be removable from the device together with these.

[0014] In particular, a shielding element and a holding element are each assigned to a common holder and are detachably connected to the device or transport equipment with this holder.

[0015] Advantageously, the shielding element is a shielding plate which, during operation, is located at least temporarily below the opening of the plastic preform, thus protecting it from excessive heating. "At least temporarily" means that the shielding plate can also be located above the opening during the moment the preform is picked up and / or dispensed. "Below" in this sense means, in particular, that the shielding element is arranged on a plane that intersects the preform, especially perpendicular to its longitudinal axis, in an area that forms the boundary between the area of ​​the preform that is to be heated and the area that is not.

[0016] In a further advantageous embodiment, the device comprises a plurality of heating units for heating the plastic preforms. Advantageously, these heating units are arranged in a stationary position. For example, a plurality of heating boxes could be provided, arranged along the transport path of the plastic preforms, which heat the plastic preforms using infrared radiation. However, the heating devices could also be microwave, hot air, or laser heating devices.

[0017] The advantage is that the respective carrier unit can be removed from the transport device without the use of tools. For example, bayonet-like fasteners could be provided, which allow the carrier unit to be removed by hand.

[0018] Advantageously, the carrier unit can be removed from the transport device by a movement that occurs only in one direction or in one plane. In the devices mentioned here, as stated above, the individual plastic preforms are arranged as close together as possible, and therefore the retaining elements are also positioned very close together. In particular, a very convenient removal of the carrier unit with its shielding and retaining elements is conceivable by a movement that is perpendicular to a transport path of the plastic preforms.

[0019] Advantageously, the transport device has a circulating chain or belt. However, a support device arranged around a predetermined axis of rotation could also be provided.

[0020] In a further advantageous embodiment, at least one retaining element is formed in at least two parts, and a detachable connection exists between the parts of the retaining element. In this way, for example, an upper part of the retaining element, which preferably does not come into direct contact with the plastic preform, can remain on the transport device, and a lower part of the retaining element, which holds or carries the plastic preform, can be removed with the carrier unit. According to the invention, the retaining elements are retaining mandrels that can be inserted into an opening of the plastic preforms in order to hold them. However, they could also be external grippers that grip or clamp the plastic preform radially from the outside.

[0021] This means that the shielding element and the retaining element can preferably be removed from the heating device together with a carrier.

[0022] The gripping function of the holding element can be achieved actively (via clamping jaws that can be controlled or moved by means of a drive (fixed control cam, motor, piezo element, magnet etc.)) or passively (via spring-loaded clamping jaws).

[0023] The invention proposed here can be used in both rotary and linear ovens. During operation, a longitudinal movement of the holding element, i.e., a movement in a longitudinal direction of the plastic preform to be heated, is often performed, for example, to ensure that the holding element is immersed in the opening of this plastic preform. With regard to this longitudinal movement, the holding element or the support unit is preferably designed such that the part of the holding element that holds the plastic preform is fixed in an axial direction. It would also be conceivable for a part of the holding element to be rotationally fixed to a support unit or a receptacle.

[0024] Advantageously, the device also features rotating units that allow the plastic preforms to be rotated around their longitudinal axis during heating. This ensures uniform heating of the plastic preforms.

[0025] However, it is also conceivable that the retaining element, or at least a component thereof, is secured only in one axial direction (for receiving), but is rotatably mounted relative to the support unit. In this case, it is conceivable that, for example, an engagement with a transport chain or a toothed belt for the purpose of rotation takes place below the aforementioned mounting point.

[0026] In a further embodiment, it would also be conceivable that the shielding element (especially when directly attached to the mounting element) rotates with the mounting element. In this embodiment, it would be conceivable that the shielding element has a circular cross-section.

[0027] In a further advantageous embodiment, the aforementioned detachable connection between the parts of the holding element enables the transmission of torques. For example, a non-circular projection of one part could engage with a corresponding non-circular receiving section of the other part of the holding element. Advantageously, this detachable connection can be separated by a linear movement. In particular, the part of the holding element that holds the plastic preform itself can be pulled away from another part by a movement with a component in the longitudinal direction of the plastic preform being heated.

[0028] In a further advantageous embodiment, the part of the retaining element arranged on the carrier unit is rotatably arranged relative to this carrier unit. In particular, said part of the retaining element is rotatably arranged with respect to a longitudinal direction of the plastic preform to be heated or a longitudinal direction of the retaining element.

[0029] In a further advantageous embodiment, the support unit has a receiving space for receiving components of the retaining element. Advantageously, this support unit also has a stop element which limits movement of the retaining element in the aforementioned longitudinal direction and thus, in particular, prevents the retaining element from falling out of the support unit.

[0030] In a further advantageous embodiment, fastening devices are arranged on the transport device, to which the support units are detachably attached. For example, base holders or base supports could be arranged on chains or on a transport chain, to which the individual support units can then be detachably attached.

[0031] The aforementioned second parts of the retaining elements can be attached to these base supports. It is particularly possible for these second parts to be rotatably mounted relative to the base supports. However, as mentioned above, a rotationally fixed arrangement of these second parts of the retaining elements on the base supports would also be conceivable.

[0032] In a further advantageous embodiment, the support units are arranged on the transport device via detachable fastening devices. Advantageously, the support units are attached via these detachable fastening devices to the aforementioned base supports, which can, for example, be permanently arranged on the transport device.

[0033] Advantageously, at least one of these fastening devices, as mentioned above, is a fastening device that can be released by manual intervention, and preferably the fastening device is selected from a group of fastening devices which includes bayonet-type fastening devices or magnetic fastening devices.

[0034] In another advantageous embodiment, the retaining element is designed in two parts or in multiple parts.

[0035] In a further advantageous embodiment, the part of the retaining element arranged on the carrier unit is displaceable in its longitudinal direction relative to the carrier unit. This displaceable arrangement particularly facilitates the insertion of the retaining elements into the plastic preforms and / or the withdrawal of the retaining elements from the plastic preforms.

[0036] In a further advantageous embodiment, the carrier unit has a pretensioning means to pretension the part of the retaining element arranged on the carrier unit in its longitudinal direction. Advantageously, the retaining element, or the part of the retaining element, is thereby tensioned against the other part of the retaining element. In a device in which the plastic preforms are transported hanging with their openings pointing upwards, the retaining element that holds the plastic preform is thus pretensioned upwards.

[0037] The present invention further relates to a support module or a holding device for holding elements for holding plastic containers, in particular plastic preforms. This holding and shielding module comprises a support unit on which a shielding element for heat shielding and a holding element are arranged.

[0038] According to the invention, the carrier unit further comprises fastening means in order to be mounted on and / or removed from a transport device together with the shielding element and the retaining element.

[0039] Preferably, the support module is designed as described above. Advantageously, the retaining element is movably arranged on the support unit. Particularly preferably, the retaining element is rotatably and / or slidably arranged on the support unit.

[0040] In a further advantageous embodiment, at least one retaining element is assigned exactly one shielding element, and preferably exactly one retaining element is assigned to exactly one shielding element. Particularly preferably, this retaining element and this shielding element are arranged on exactly one carrier unit. Particularly preferably, this carrier unit is detachably connected to a transport device. This transport device can, in particular, be the transport device mentioned above.

[0041] In a further advantageous embodiment, the shielding element has an opening that is larger than the diameter of a plastic preform to be transported. Preferably, the holding device is further designed such that the plastic preform protrudes through this opening with its mouth area – particularly during transport.

[0042] The designs described here with reference to the holding device can also be applied accordingly to the device for heating plastic preforms described above or to the transport device also described above.

[0043] The present invention further relates to a method for mounting or dismounting retaining elements and shielding elements to or from a device for heating plastic preforms. The retaining elements serve to hold the plastic preforms, and the shielding elements serve to prevent heat from reaching a threaded area of ​​the plastic preforms.

[0044] According to the invention, at least parts of the retaining elements and at least parts of the shielding elements are arranged on carrier units, and these carrier units, together with the parts of the retaining elements and shielding elements arranged thereon, are mounted to or removed from a transport device. It would also be possible for the retaining elements and the shielding elements to be replaced simultaneously, i.e., in particular in a single operation.

[0045] However, it is also possible that this shielding element itself has a support on which the retaining element is formed, or conversely, that the retaining element itself also constitutes the support on which the shielding element is attached. Thus, the support unit and the retaining and shielding elements do not necessarily have to be separate components.

[0046] If, for example, the retaining element also represents a support unit, it would be conceivable that this support unit is formed by the section of the retaining element on which the shielding element is also arranged.

[0047] Advantageously, the retaining elements are mounted or dismounted at the same time as the associated shielding elements.

[0048] In particular, the transport path of the preforms within the device lies essentially in a horizontal plane. Specifically, the immersion movement of the holding elements into the preforms occurs in a direction perpendicular to this plane. This direction is therefore directed towards the Earth's center. The (extended) axis of rotation of the holding elements or preforms also intersects the Earth's center.

[0049] In particular, the carrier unit is detachably connected to a base carrier, and the retaining element and / or the shielding element are also detachably connected to the carrier unit. Specifically, at least one, and in particular all, of these detachable connections are manually releaseable (without the use of tools), especially a bayonet fitting or a magnetic (plug-in) connection. However, it would also be possible to use other fastening means such as screws.

[0050] The shielding element is preferably rectangular or square and has a hole in its center through which the preform or the retaining element extends, at least temporarily and partially. This design allows, in particular, an arrangement of two adjacent shielding elements such that as little heat or radiation as possible can penetrate between them into the area of ​​the openings of the preforms. The gap between two shielding elements is preferably less than 1 cm, and preferably less than 3 mm. In this case, the shielding plates are arranged in a stationary or immovable position relative to the base support.

[0051] The function "rotating the holding element" can be accomplished by a drive which transmits its torque via a coupling at the separation point to release the holding element, or by a drive which acts directly on the holding element.

[0052] The same applies to the function "lowering or raising the holding element": here the drive can either act directly on the holding element and move it, or the drive drives an element that is not replaced and the force is transferred to the holding element via this element.

[0053] Alternatively, magnetically actuated drives can be used in both cases, so that mechanical couplings or additional transmission elements are not necessary.

[0054] The device is operated in a continuous manner, meaning that a continuous transport of the preforms is realized during heating.

[0055] In particular, a large number of preforms are picked up by the holding elements of the device at equidistant intervals from each other and are also transported in this way.

[0056] In particular, a changeover can be performed automatically by a machine located next to the device. This machine could operate intermittently or continuously, removing retaining elements and / or shields from the device with an arm and replacing them with new ones. A magazine containing a supply of interchangeable parts can be mounted on the machine. It would also be conceivable to trigger a quick-change mechanism on the stationary machine shortly before or upon reaching the changeover position using an adjustable actuating cam, so that the machine only needs to remove and insert the parts without activating the mechanism. Alternatively, the retaining elements, including shields, could be dropped into a box by the cam, so that the machine only needs to attach the new retaining elements, including shields. After the changeover operation, the machine can then be reloaded manually.

[0057] Further advantages and embodiments are shown in the accompanying drawings. These show: Fig. 1 A schematic representation of a device for manufacturing plastic containers; Fig. 2 a representation of a carrier unit with a shielding element and a holding element; Fig. 3 a representation of a holding element with support unit in a device for heating plastic preforms; Fig. 4 three representations of different operating states of a holding element; Fig. 5a, Fig. 5b two illustrations to demonstrate a fastening mechanism for securing the retaining element; Fig. 6 a representation of a shielding element; Fig. 7 a representation of an arrangement according to the invention in a further embodiment; Fig. 8 a representation of an arrangement according to the invention in a further embodiment; Fig. 9 a representation of an arrangement according to the invention taking into account guide curves; Fig. 10 a representation similar Fig. 9, but without an upper guide curve; Fig. 11 a representation of an arrangement according to the invention, particularly for sterile applications; Fig. 12 a representation of an engagement element of a holding element; Fig. 13 another representation of the in Fig. 12 shown intervention element; Fig. 14 a perspective view of an intervention element; and Fig. 15. A representation of an automatic format part change.

[0058] Fig. Figure 1 shows a schematic representation of a system for manufacturing plastic containers. A device 1 according to the invention is provided for heating plastic preforms 10. This device has a plurality of heating elements 4 arranged along a transport path P of the plastic preforms. The heating elements 4 are also present on the other side of the device 1, but are not labeled.

[0059] Reference numeral 50 schematically designates a holding device for holding the plastic preforms 10. These are first separated in a singulation device 134 via a feeding device 132, such as a feeding rail, and then fed to the device 1. Reference numeral 2, in its entirety, designates a transport device for transporting the plastic preforms, which here are specifically designed as a circulating chain.

[0060] Reference numeral 156 designates a transport device which transfers the heated plastic preforms to another device, such as in particular a stretch blow molding machine or a sterilization device.

[0061] Fig. Figure 2 shows a detailed representation of a device according to the invention. A transport device 2 (shown only schematically) is provided, for example, in the form of a chain, on which the holding device 50 is arranged. This holding device 50 has a base support 6 that is fixedly arranged (e.g., on a transport chain or conveyor belt). The support unit 30 is arranged on the base support 6 via a releasable fastening device 40. This fastening device 40 can, for example, be a fastening device with a hand lever that is pre-tensioned in a starting position by means of a pre-tensioning device such as a spring. Alternatively, this hand lever 78 can also be fixed in a receptacle, for example, if a holder has a corresponding insertion cone.

[0062] Reference numeral 22b designates a second part of the retaining element, which, in this embodiment, is arranged on the transport device and remains on the transport device even after disassembly. A gear 25, which serves to rotate the heating mandrel or the retaining element, can be arranged on this second part 22b of the retaining element. As mentioned above, this gear can also be attached to the lower part 22a of the retaining element, particularly if the retaining element or the support unit 30 has a lateral recess (not shown) through which a chain can pass. In that case, the second part 22b could be omitted. Reference numeral 64 designates a rotary driver that transmits the rotation from the second part 22b of the retaining element 22 to the first part 22a of the retaining element 22.

[0063] The reference numeral 10 designates a plastic preform which has a support ring 10a and which is held by an engagement of the first part 22a of the retaining element 22.

[0064] Reference numeral 24 identifies the shielding element mentioned above, which serves to shield heat from a threaded area of ​​the plastic preform 10. Reference numeral 25 identifies retaining pins with which the shielding element is attached to the carrier unit 30. Alternatively, a retaining plate can be used instead of the retaining pins. Preferably, additional fastening means (not shown) are provided, which also allow the shielding element 24 to be removed from the carrier unit 30. Advantageously, the shielding element 24 is additionally screwed in a removable manner or can also be attached to the carrier unit with a quick-release fastener.In practice, it is conceivable that in individual cases only the shielding element 24 or only the retaining element 22, 22a needs to be replaced, for example, if two plastic preforms 10 with the same inner diameter are to be heated, but which have differently sized support rings. In this case, only the replacement of the shielding element 24 would be necessary. Reference numeral 54 denotes an upper stop of the retaining element or its part 22a, and reference numeral 62 denotes a bearing with which part 22a of the retaining element is rotatably mounted relative to the support unit 30. A preloading element 52, which rests against a stop 56, allows the first part 22a of the retaining element to be preloaded upwards, thereby also preloading the second part 22b of the retaining element. This means that, in the case of a curve control system, only a curve pointing in one direction is necessary. In other words, the curve does not need to raise the retaining element again.

[0065] Fig. Figure 3 shows a further representation of a device according to the invention. This representation also shows the heating elements 4, past which the plastic preform 10 is transported. Each heating element 4 has several infrared emitters arranged at different heights, which can be controlled separately from one another. This allows different areas along the longitudinal axis of the preform to be heated differently. Two adjacent heating elements 4 can also be controlled differently with respect to their power output. The transport chain is again shown, as well as a rotating element, such as a drive element, a toothed gear 53, or a chain, which enables rotation of the holding element or mandrel. Alternatively, however, it would also be conceivable that each individual holding element has its own separate drive, and in particular a direct drive, instead of the drive element 53.For example, electric motors could be provided to drive the retaining elements to rotate with respect to their longitudinal direction L. Alternatively, a magnetic curve would also be conceivable if the gear 25 were replaced by permanent magnets. Here it can be seen that the shield 24 and the support ring 10a of the preform 10, concealed within or above it, are located directly above the uppermost position of the heating elements 4.

[0066] Fig. Figure 4 shows three different operating positions of a holding element according to the invention. The left illustration shows an operating mode in which the holding element, with the plastic preform 10 attached to it, is transported, for example, through a heating tunnel. The middle illustration shows a quick-change operation in which the carrier unit with the shielding element or the holding element attached to it has just been detached from the base carrier. The right illustration shows a position in which the holding element is immersed in the plastic preform 10. Here, a guide cam 55 is provided, which effects this immersion in the plastic preform 10. The element 22b transmits the force of the drive 54 to the holding element.

[0067] The Fig. 5a, Fig. Figure 5b shows the fastening device with which the support unit 30 is attached to the base support. This fastening device has an engagement element 72 arranged on the base support 6, which is located on a projection 34. This engagement element 72 can, in turn, engage behind a section of the support unit. Reference numeral 82 designates a pre-tensioning device, which pre-tensions a hand lever 78 here to the left, i.e., into a closed position. By pressing the hand lever 78, the opening 76 can be moved to the right, thus releasing the engagement element from the actuating element 78. However, it would also be possible for the fastening device to be configured in the opposite way, i.e., for example, for the engagement element 72 to be arranged on the support unit.

[0068] Fig. Figure 5b illustrates a position in which the support unit 30 is attached to the base support 6. An inclined plane can also be attached to the element 72, which interacts with the edge of the opening 76 in such a way that the support unit is pre-tensioned upwards by the spring 82 to achieve precise vertical positioning.

[0069] Fig. Figure 6 shows a representation of the shielding element 24. It can be seen that this shielding element 24 has an opening 24a through which the plastic preform can be at least partially passed. Advantageously, this shielding element 24 is designed to be reflective on its underside in order to reflect radiation, particularly infrared radiation. Advantageously, the shielding element 24 is also rectangular or square in shape so that no gap is created between two adjacent shielding elements through which thermal radiation could pass. It would be possible and preferred that the opening 24a be chosen to be large enough to also allow the support ring of the plastic preform to pass through it. This is advantageous when the plastic preform is lifted from below or the shielding element is lowered.

[0070] Fig. Figure 7 shows a further embodiment of an arrangement according to the invention. In this embodiment, the engagement between the first part 22a and the second part 22b of the retaining element is modified. A spring element 73 and a coupling device 75, such as a pre-tensioned clutch disc, can be seen here. In this way, it is no longer necessary to thread the second part 22b of the retaining element into the first part. The torques are transmitted via the coupling element 75.

[0071] Fig. Figure 8 shows another embodiment of an arrangement according to the invention. Here, too, a coupling element 75 is provided, which transmits the rotational moments or torques. However, the connection mechanism between the support unit 30 and the base support is modified. Here, magnets 82 and 84 are provided, which hold these two elements together. In addition, a centering element 86 is provided, which ensures that the support unit 30 is held precisely in the position intended for this purpose. Both magnets 82 and 84 are, in particular, permanent magnets, but it would also be conceivable to design at least one magnet 82 or 84 as an electromagnet.

[0072] Fig. Figure 9 shows a further embodiment of the device according to the invention. Here, a first guide roller 94 is provided, which interacts with a guide cam 92. This causes the immersion movement of the retaining element into the plastic preform. The second dashed part of the guide cam 92 could be used to heat certain areas of the plastic preform differently than others. In this way, it would be possible to decouple the retaining element from the rotational movement (by lowering or raising the first part 22a), so that the rotational movement is regularly suspended for this time and the plastic preform is heated only on the desired side (preferential heating).

[0073] Reference numeral 93 indicates an optional spring for pushing up the second part 22b of the retaining element, for example, to preload it against a guide cam. It should be noted that the guide cam is not as shown in Fig. The guide cam 96 and guide roller 98 are shown in Figure 10, but are located behind the drawing plane. The guide cam 96 and guide roller 98 enable the lowering and raising of the retaining element 22. The positions of the two guide cams 96 and 92 and their strokes are shown schematically here. The stroke initiated by cam 92 can be very small. In contrast, the stroke of cam 96 should be at least as long as the mouth area of ​​the preform 10 to be protected, so that it can be completely lifted above the shield during the immersion movement when picking up the preform. Fig. Figure 10 shows a further embodiment of a device according to the invention. In this embodiment, no guide roller 98 is provided, but only a rotary drive. An additional linear drive could also be provided, for example, to achieve the longitudinal movement of the holding element, i.e., the movement in the longitudinal direction of the plastic preform. Here, the function of "lowering the mandrel" to receive a preform is completely taken over by the cam 92.

[0074] Fig. Figure 11 shows an embodiment of the device according to the invention, particularly for sterile applications. An additional sealing element 68, such as a bellows, is shown, arranged on the carrying unit 30. Advantageously, this sealing element 68 is rotatable at one end. This is particularly useful when the preforms are already sterilized by a sterilization unit upstream of the transport device 2. Further sealing elements of the device are not shown here, but may be present in addition.

[0075] The Fig. Figures 12 to 14 show three illustrations of a retaining mandrel for holding the plastic containers, in particular the section that extends into the openings of the plastic preforms. A fastening element 37 is visible, with which a lower retaining section is attached to the remaining part of the retaining element. Reference numeral 36 denotes pretensioning elements that apply a positioning element 35 to the inner wall of the opening of the plastic preform. Reference numeral 34 denotes a support element. Fig. Figure 13 shows a further embodiment, in which a pressing effect is achieved by ring-shaped elastic elements 38, which press an adjusting element 39 radially outwards. In the Fig. In the illustration shown in Figure 14, a basic body 43 can again be seen, at the lower end of which adjustment elements 39 are provided, which can press outwards. The reference numeral 45 designates an engagement section (in its entirety) that immerses into the plastic preforms.

[0076] Fig.Figure 15 shows a schematic diagram illustrating a changeover operation. As mentioned above, the exchange of the shielding elements and retaining elements is preferably carried out fully automatically. For this purpose, it is possible for a changeover device 100 to be moved to the transport device 2 and to exchange the individual retaining elements with the shielding elements one by one. In the embodiment shown here, it is particularly conceivable to exchange three different groups of retaining elements and shielding elements (A, B, C). In the illustration shown here, the elements marked C are being removed from the device and the elements marked A are being fed in. Reference numeral 120, as mentioned above, designates a blow molding machine on which different elements can also be exchanged.For example, 122 blow molds can be exchanged via a changing machine, elements such as the horizontal bars can be exchanged via a docking point 124, and holding elements such as gripping clamps can be exchanged via a docking point 126.

[0077] The changeover between groups A, B, and C can be operated in a cycle-like manner. The transport device is moved by a predefined number of divisions (distance between the center axes of two holding elements), stops, and the elements are exchanged at that point. It would also be possible to remove the predetermined number of elements at one position along the circumference of the transport device and insert the next set of elements to be used at a second, particularly adjacent, position.

[0078] The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they are novel individually or in combination compared to the prior art. Reference symbol list 1 Device 2 Transport equipment 4 heating elements 10 plastic preforms 10a Support ring 22 retaining element 22a lower (first) part of the retaining element 22b upper (second) part of the retaining element 24 shielding element 24a Opening 25 gear 30 carrier units 34 Support element 35 delivery bodies 37 Fasteners 38 ring-shaped elements 39 Delivery element 40 Fastening device 43 Basic body 45 Intervention section 50 Holding device 52 Preload element 53 Propulsion devices 54 upper stop of the retaining element 55 Lead curve 56 stops 62 Storage 64 rotary actuators 68 Sealing device 72 Intervention device 73 Spring element 74 Coupling element / projection 75 Coupling device 76 Opening 78 hand levers 82 Pre-tensioning devices 82, 84 magnets 86 Centering element 92 Leading curve 93 optional springs 94, 98 Leadership role 96 Lead curve 100 exchange unit 120 blow molding machine 122 Change machine 124, 126 Docking point 132 Feeding device 134 Single-person access control device 156 Transport equipment P Transport route L Longitudinal direction A, B, C groups of holding and shielding elements

Claims

[1] Device for heating plastic preforms (10), with a transport device (2) which transports the plastic preforms along a predetermined transport path (P), wherein a plurality of holding elements (22) for holding the plastic preforms (10) and a plurality of shielding elements (24) for shielding heat are arranged on the transport device (2), characterized by , that the device (1) has a plurality of carrier units (30) on which at least a part (22a) of the retaining elements (22) and at least a part of the shielding elements (24) are arranged and these carrier units (30) together with the parts (22a) of the retaining elements (22) and the shielding elements (24) arranged thereon are demountable from the transport device (2), wherein the retaining elements (22) are retaining mandrels which can be inserted into an opening of the plastic preforms (10) in order to hold them. [2] Device (1) according to claim 1, characterized by , that at least one retaining element (22) is formed in at least two parts and that a detachable connection exists between the parts (22a, 22b) of the retaining element (22). [3] Device (1) according to claim 2, characterized by , that the detachable connection between the parts (22a, 22b) enables the transmission of torques. [4] Device (1) according to at least one of the preceding claims, characterized by , that the part (22a) of the retaining element (22) arranged on the carrier unit (30) is rotatably arranged relative to the carrier unit (30). [5] Device (1) according to at least one of the preceding claims, characterized by , that on the transport device (2) support devices (6) are arranged on which the carrying units (30) are detachably arranged. [6] Device (1) according to at least one of the preceding claims, characterized by, that the carrying units (30) are arranged on the transport device (2) via detachable fastening devices (40). [7] Device (1) according to claim 6, characterized by , that at least one of these fastening devices (40) is selected from a group of fastening devices (40) which includes bayonet-type fastening devices (40) or magnetic fastening devices (40). [8] Device (1) according to at least one of the preceding claims, characterized by , that the part (22a) of the retaining element arranged on the support unit (30) is arranged to be displaceable in its longitudinal direction relative to the support unit (30). [9] Device (1) according to at least one of the preceding claims, characterized by , that the support unit (30) has a prestressing means (82) to prestress the part (22a) of the retaining element (22) arranged on the support unit (30) in its longitudinal direction. [10] Holding device (50) for holding elements (22) for holding plastic containers, in particular plastic preforms (10), with a carrier unit (30) on which a shielding element (24) for shielding from heat and at least a part (22a) of the holding element (22) are arranged, characterized by , that the carrier unit (30) further comprises fastening means (40) in order to be mounted on and / or removed from a transport device (2) together with the shielding element (24) and the retaining element (22), wherein the retaining elements (22) are retaining mandrels which can be inserted into an opening of the plastic preforms (10) in order to hold them. [11] Method for mounting or dismounting retaining elements (22) and shielding elements (24) to or from a device for heating plastic preforms (10), wherein the retaining elements (22) serve to hold plastic preforms (10) and the shielding elements (24) serve to prevent heat from a threaded area of ​​the plastic preforms, characterized by , that at least parts (22a) of the retaining elements (22) and at least parts of the shielding elements (24) are arranged on carrier units (30) and that these carrier units (30) together with the parts (22a) of the retaining elements (22) and shielding elements (24) arranged thereon are mounted on or removed from a transport device (2), wherein the retaining elements (22) are retaining mandrels which can be inserted into an opening of the plastic preforms (10) in order to hold them. [12] Method for mounting or dismounting retaining elements (22) and shielding elements (24) to or from a device for heating plastic preforms (10), wherein the retaining elements (22) serve to hold plastic preforms (10) and the shielding elements (24) serve to prevent heat from a threaded area of ​​the plastic preforms (10), characterized by , that the shielding elements (24) and the retaining elements (22) are replaced simultaneously, the retaining elements (22) being retaining mandrels which can be inserted into an opening of the plastic preforms (10) in order to hold them in place. [13] Method according to claim 12, characterized by , that the shielding elements (24) are arranged in a rotationally fixed manner on a support (30) relative to the rotating retaining elements (22).

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