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ROTATIONAL MOLDING APPARATUS AND METHOD FOR OPERATING A ROTATIONAL MOLDING APPARATUS

20230241809 ยท 2023-08-03

    Inventors

    Cpc classification

    International classification

    Abstract

    The invention relates to a method for operating a rotational molding apparatus that comprises a rotatably mounted rotational-molding mold holder having a rotational-molding mold. The method is characterised in that a trajectory of a reference point of a component for a rotation process, in particular a component of the rotational-molding mold holder or the rotational-molding mold, which component rotates during a rotation process, is selected from one of a plurality of possible trajectories that can be achieved by the rotational molding apparatus, and in that a rotation process is subsequently performed in which rotational-molding material introduced into the rotational-molding mold accumulates on the inner face of the rotational-molding mold and in which the reference point moves along the determined trajectory.

    Claims

    1. A method for operating a rotational-molding device, which comprises a rotatably mounted rotational-mold holder with a rotational mold, characterized in that a trajectory of a reference point on a component, in particular the rotational-mold holder or the rotational mold, rotating in the course of a rotation operation is selected for a rotation operation from one of multiple possible trajectories that can be performed by the rotational-molding device, and in that then a rotation operation is performed, during which rotational-molding material introduced into the rotational mold accumulates on the inner side of the rotational mold and during which the reference point moves along the established trajectory.

    2. The method as claimed in claim 1, characterized in that the trajectory is selected depending on the design of the rotational mold.

    3. The method as claimed in claim 1, characterized in that the trajectory is selected such that at least one location on the inner side of the rotational mold remains free of rotational-molding material during the rotation operation.

    4. The method as claimed in claim 1, characterized in that the trajectory is selected such that at least one location on the inner side of the rotational mold is never arranged at the bottom during the rotation operation.

    5. The method as claimed in claim 1, characterized in that the trajectory is selected such that at least one location on the inner side of the rotational mold is arranged at the bottom more often than all other locations during the rotation operation.

    6. The method as claimed in claim 1, characterized in that the trajectory is selected such that, during the rotation operation, an especially large amount of rotational-molding material accumulates at least at one location on the inner side of the rotational mold.

    7. The method as claimed in claim 1, characterized in that at least one trajectory from the multiple possible trajectories that can be performed by the rotational-molding device is input, in particular via an interface of the rotational-molding device.

    8. The method as claimed in claim 1, characterized in that the reference point is selected such that the trajectory runs exclusively on one spherical surface.

    9. The method as claimed in claim 1, characterized in that the trajectory is established by inputting trajectory segments and joining together the trajectory segments that were input.

    10. The method as claimed in claim 9, characterized in that each trajectory segment is assigned a speed at which the reference point moves along the trajectory segment during a rotation operation, or in that each trajectory segment is assigned a speed variation over time with which the reference point moves along the trajectory segment during a rotation operation.

    11. The method as claimed in claim 9, characterized in that the inputting of a trajectory segment comprises the input of at least one parameter from the following group: trajectory segment length, trajectory segment curvature, trajectory segment curvature profile.

    12. The method as claimed in claim 9, characterized in that trajectory segments directly following one another differ from one another in terms of the trajectory segment length and/or the trajectory segment curvature and/or the trajectory segment curvature profile and/or in terms of an assigned speed and/or an assigned speed variation.

    13. The method as claimed in claim 9, characterized in that the inputting of at least one of the trajectory segments comprises making a selection from a selection display of different trajectory segment types.

    14. The method as claimed in claim 13, characterized in that the trajectory segment types are each depicted in a perspective depiction.

    15. The method as claimed in claim 13, characterized in that the trajectory segment types in the selection display are each depicted as a projection onto a planar surface.

    16. The method as claimed in claim 15, characterized in that the projection is a stereoscopic projection or a parallel projection or a Mercator projection.

    17. The method as claimed in claim 15, characterized in that the selection display comprises at least one trajectory segment type the projection of which is a projection from the following group: segment of a circle, segment of a parabola, segment of a straight line, 90 degree arc, 180 degree arc, 270 degree arc, 360 degree arc, segment of a loop, projection of an involute of a circle onto a spherical surface, segment of a spiral, stop segment.

    18. The method as claimed in claim 1, characterized in that the established trajectory is displayed in a projection onto a two-dimensional plane.

    19. The method as claimed in claim 18, characterized in that the projection is a parallel projection or a stereographic projection or a Mercator projection.

    20. The method as claimed in claim 1, characterized in that the rotational-molding device is a spherical rotational device.

    21. The method as claimed in claim 1, characterized in that a temporal sequence of control signals for at least one drive motor generating the rotation is created from the profile of the trajectory.

    22. The method as claimed in claim 1, characterized in that the rotational-mold holder is in the form of a sphere, which is driven in rotation during the rotation operation.

    23. The method as claimed in claim 22, characterized in that the rotational-mold holder is driven by means of a drive wheel, which rolls on the surface of the sphere.

    24. A rotational-molding device, which comprises a rotatably mounted rotational-mold holder with a rotational mold, characterized in that a trajectory of a reference point on a component, in particular the rotational-mold holder or the rotational mold, rotating in the course of a rotation operation can be selected for a rotation operation from one of multiple possible trajectories that can be performed by the rotational-molding device, and in that, after a selection operation, a control device controls a rotation operation during which rotational-molding material introduced into the rotational mold accumulates on the inner side of the rotational mold in such a way that the reference point moves along a selected trajectory.

    25. The rotational-molding device as claimed in claim 24, characterized in that it is possible to select a trajectory which is formed such that at least one location on the inner side of the rotational mold remains free of rotational-molding material during the rotation operation.

    26. The rotational-molding device as claimed in claim 24, characterized in that it is possible to select a trajectory which is formed such that at least one location on the inner side of the rotational mold is never arranged at the bottom during the rotation operation.

    27. The rotational-molding device as claimed in claim 24, characterized in that it is possible to select a trajectory which is formed such that at least one location on the inner side of the rotational mold is arranged at the bottom more often than all other locations during the rotation operation.

    28. The rotational-molding device as claimed in claim 24, characterized in that it is possible to select a trajectory which is formed such that, during the rotation operation, an especially large amount of rotational-molding material accumulates at least at one location on the inner side of the rotational mold.

    29. The rotational-molding device as claimed in claim 24, characterized in that at least one trajectory which can be performed by the rotational-molding device can be input, in particular via an interface of the rotational-molding device, and can be added to the multiple possible trajectories which can be performed by the rotational-molding device and from which a trajectory can be selected.

    30. The rotational-molding device as claimed in claim 24, characterized in that individual trajectory segments can be input, and in that the control device establishes the trajectory from the trajectory segments that were input by stringing together the trajectory segments that were input.

    31. The rotational-molding device as claimed in claim 30, characterized in that an input device by means of which the trajectory segments can be input is present.

    32. The rotational-molding device as claimed in claim 31, characterized in that the input device comprises a display device, which displays a selection display of different trajectory segment types from which trajectory segments can be selected by means of an input unit.

    33. The rotational-molding device as claimed in claim 32, characterized in that the display device depicts each of the trajectory segment types in a perspective depiction.

    34. The rotational-molding device as claimed in claim 31, characterized in that the display device depicts each of the trajectory segment types in the selection display as a projection onto a planar surface.

    35. The rotational-molding device as claimed in claim 34, characterized in that the projection is a stereoscopic projection or a parallel projection or a Mercator projection.

    36. The rotational-molding device as claimed in claim 34, characterized in that the selection display comprises at least one trajectory segment type the projection of which is a projection from the following group: segment of a circle, segment of a parabola, segment of a straight line, 90 degree arc, 180 degree arc, 270 degree arc, 360 degree arc, segment of a loop, projection of an involute of a circle onto a spherical surface, segment of a spiral, stop segment.

    37. The rotational-molding device as claimed in claim 30, characterized in that a. for each trajectory segment that was input, a speed at which the reference point moves along the trajectory segment during a rotation operation can be input, which speed is assigned to the trajectory segment by the control device, or in that b. for each trajectory segment that was input, a speed variation with which the reference point moves along the trajectory segment during a rotation operation can be input, which speed variation is assigned to the trajectory segment by the control device.

    38. The rotational-molding device as claimed in claim 30, characterized in that the inputting of a trajectory segment comprises the input of at least one parameter from the following group: trajectory segment length, trajectory segment curvature, trajectory segment curvature profile.

    39. The rotational-molding device as claimed in claim 24, characterized in that the established trajectory is displayed in a projection onto a two-dimensional plane.

    40. The rotational-molding device as claimed in claim 39, characterized in that the projection is a parallel projection or a stereographic projection or a Mercator projection.

    41. The rotational-molding device as claimed in claim 24, characterized in that the rotational-molding device is a spherical rotational device.

    42. The rotational-molding device as claimed in claim 24, characterized in that, from the profile of the trajectory, the control device creates a temporal sequence of control signals for at least one drive motor generating the rotation.

    43. The rotational-molding device as claimed in claim 24, characterized in that the rotational-mold holder is in the form of a sphere, which is driven in rotation during the rotation operation.

    44. The rotational-molding device as claimed in claim 43, characterized in that the rotational-mold holder is driven by means of a drive wheel, which rotates about a first axis of rotation and which rolls on the surface of the sphere.

    45. The rotational-molding device as claimed in claim 44, characterized in that the drive wheel is mounted so as to be able to rotate about a second axis of rotation which is perpendicular to the first axis of rotation.

    Description

    BRIEF DESCRIPTION OF THE DRAWING VIEWS

    [0084] In the drawing, the subject matter of the disclosure is illustrated schematically and by way of example and will be described below with reference to the figures, with elements that are the same or have the same action are usually provided with the same reference signs even in different exemplary embodiments. In the figures:

    [0085] FIG. 1 shows an exemplary embodiment of a rotational-molding device according to the disclosure,

    [0086] FIG. 2 shows an exemplary embodiment of an input device of a rotational-molding device according to the disclosure,

    [0087] FIG. 3 shows another exemplary embodiment of an input device of a rotational-molding device according to the disclosure,

    [0088] FIG. 4 shows an exemplary embodiment of a rotational-molding installation according to the disclosure as per an independent concept of the disclosure,

    [0089] FIG. 5 shows the exemplary embodiment after a spherical rotational-mold holder together with a rotational mold held therein has been introduced,

    [0090] FIG. 6 shows the exemplary embodiment of the rotational-molding installation after the entire rotational device has been moved vertically upward into the heating station,

    [0091] FIG. 7 shows the exemplary embodiment of the rotational-molding installation after the rotational device has been moved back into the cooling station,

    [0092] FIG. 8 shows a further exemplary embodiment of a rotational-molding installation according to the disclosure as per the independent concept of the disclosure,

    [0093] FIG. 9 shows the further exemplary embodiment after a spherical rotational-mold holder together with a rotational mold held therein has been introduced,

    [0094] FIG. 10 shows the further exemplary embodiment of the rotational-molding installation after the entire rotational device has been moved vertically upward into the heating station,

    [0095] FIG. 11 shows the further exemplary embodiment of the rotational-molding installation after the rotational device has been moved back into the cooling station.

    DETAILED DESCRIPTION

    [0096] FIG. 1 shows an exemplary embodiment of a rotational-molding device according to the disclosure, which comprises a rotational-mold holder 1 and a rotational mold 2. The rotational-mold holder 1 is in the form of a sphere, which is driven in rotation during a rotation operation. In the example shown, the rotational mold 2 is designed to produce a plant pot. In terms of the type of object to be produced, however, there are no fundamental restrictions.

    [0097] The rotational-mold holder 1 consists of a first hemisphere 3 and a second hemisphere 4, which can be detachably connected to one another.

    [0098] The rotational mold 2 likewise has a two-part structure and has a first rotational-mold part 5 and a second rotational-mold part 6. The first rotational-mold part 5 is fastened to the inside of the first hemisphere 3 by means of first springs 7, whereas the second rotational-mold part 6 is fastened to the inside of the second hemisphere 4 by means of second springs 8. The first hemisphere 3 together with the first rotational-mold part 5 can be lifted off from the second hemisphere 4 together with the second rotational-mold part 6, in order to be able to introduce rotational-molding material 9 into the rotational mold 2 before a rotation operation and to be able to remove the produced product after a rotation operation.

    [0099] After introducing the rotational-molding material 9, the first rotational-mold part 5 is fitted onto the second rotational-mold part 6 and thus closes the rotational-mold holder 1. Then, the rotation operation can begin. During the rotation operation, the rotational mold 2 is rotated and heated at the same time, in order that the previously introduced rotational-molding material 9 can melt and accumulate on the inner side of the rotational mold 2.

    [0100] The rotational-mold holder 1 is driven in rotation by means of a drive device 10. The drive device 10 contains a drive motor 11, which drives a drive wheel 12 in rotation about a horizontal axis. The drive wheel 12 is in frictional contact with the outer side of the rotational-mold holder 1 and drives it in rotation together with the rotational mold held therein.

    [0101] The entire drive device 10 may be rotated about a vertical axis by means of a further drive device 13 comprising a second drive motor 14, in order to be able to change the alignment of the horizontal axis of rotation about which the drive wheel 12 rotates. In the event of a change in alignment of the horizontal axis of rotation about which the drive wheel 12 rotates, the alignment of the axis of rotation about which the rotational mold 1 rotates also changes automatically.

    [0102] The rotational-mold holder 1 is held in position whilst it rotates by means of laterally arranged grinding plates 15. The rotational-mold holder 1 remains stationary during the rotation operation.

    [0103] The rotational-molding device 1 comprises an input device 16. The input device 16 comprises a display device 17 and an input unit 18, which is in the form of a computer mouse 27. The input device 16 can be used to select a trajectory 25 of a reference point 28 on the rotational-mold holder 1 or the rotational mold 2 for a rotation operation from multiple possible trajectories which can be performed by the rotational-molding device 1.

    [0104] The control device 19 controls the drive device 10 and the further drive device 13 during a rotation operation in such a way that the reference point 28 moves along a selected trajectory. To that end, from the profile of the trajectory 25, the control device 19 creates a temporal sequence of control signals for the drive device 10 and the further drive device 13. The reference point 28 may (as in this exemplary embodiment) for example be that point on the outer side of the rotational-mold holder 1 that is right at the bottom and in contact with the drive wheel 12 at the beginning of the rotation operation. The trajectory runs exclusively on a spherical surface, specifically the spherical surface corresponding to the outer side of the rotational-mold holder 1.

    [0105] It is important for the rotational-mold holder 1 at the beginning of the rotation operation to be aligned such that the reference point is at the start of the selected trajectory. It is also important for the control device at the beginning of the rotation operation to know the precise rotational alignment of the rotational-mold holder 1. To that end, advantageously, sensors may be present on the drive device 10 and/or the further drive device 13 and/or alignment sensors may be present on the rotational-mold holder 1 or the rotational mold 2 which transmit information about the respective current alignment of the rotational-mold holder 1 to the control device 19.

    [0106] In particular, it may advantageously be provided that trajectory segments can be input and transmitted to a control device 19, with the control device 19 establishing the trajectory 25 from the trajectory segments that were input by stringing together the trajectory segments that were input.

    [0107] FIG. 2 shows an exemplary embodiment of an input device 16 of a rotational-molding device according to the disclosure. The input device 16 comprises a display device 17 in the form of a monitor. Moreover, the input device 16 comprises an input unit 18 in the form of a computer mouse 27.

    [0108] The display device 17 displays to the user a selection display 29 of different trajectory segment types 20, from which the user can select successive individual trajectory segments 22, 23, 24 by means of the input unit 18 and arrange them in a timeline 21. The arrangement of the individual trajectory segments 22, 23, 24 is effected in that the user clicks on a respective one of the trajectory segment types 20 by means of the input unit 18 in the form of a computer mouse 27 and moves the trajectory segment types that were clicked on to the timeline 21 when a mouse button is pressed, as a result of which the symbol is duplicated and the duplicate is deposited on the timeline 21. This operation is indicated symbolically in FIG. 2 by the dashed-line arrows.

    [0109] The result of stringing together the trajectory segments 22, 23, 24 is the trajectory 25, along which the reference point 28 moves during a rotation operation.

    [0110] The display device 17 moreover displays to the user a preview display 26, in which the surface of the rotational-mold holder 1 is depicted in two dimensions. Moreover, the trajectory 25 assembled from the trajectory segments 22, 23, 24 is displayed to the user in the preview display 26.

    [0111] The user has the option, in addition to each trajectory segment 22, 23, 24, of inputting a parameter from the following group: trajectory segment length, trajectory segment curvature and trajectory segment curvature profile. Moreover, the user has the option of assigning a speed or speed variation to each trajectory segment 22, 23, 24. The speed or speed variation specifies the dynamics with which the reference point 28 moves along the respective trajectory segment 22, 23, 24 during a rotation operation.

    [0112] FIG. 3 shows another exemplary embodiment of a display device 17 of a rotational-molding device according to the disclosure. The display device shown in FIG. 3 differs from the embodiment illustrated in FIG. 2 in terms of the preview display 26. The preview display 26 is a Mercator projection of the spherical surface of the rotational-mold holder 1 into a plane, similar to the projection of a satellite orbit onto a two-dimensional map.

    [0113] Since FIGS. 4 to 11 relate to an independent concept of the disclosure, which may also be realized in combination with the exemplary embodiments illustrated in FIGS. 1 to 3 or else on its own, distinct reference signs are used as specified below: [0114] 1 Heating station [0115] 2 Cooling station [0116] 3 Cooling station housing [0117] 4 Heating station housing [0118] 5 Insulating device [0119] 6 Spacer [0120] 7 Downwardly aligned opening in the heating station housing 4 [0121] 8 Upper opening in the cooling station housing [0122] 9 Rotational device [0123] 10 Rotational-molding material [0124] 11 Rotary drive [0125] 12 First drive motor [0126] 13 Drive wheel [0127] 14 Rotational-mold holder [0128] 15 Receptacle [0129] 16 Rotational mold [0130] 17 Second drive motor [0131] 18 Vertical carrier [0132] 19 Platform [0133] 20 Cold-air nozzle [0134] 21 Hot-air nozzle [0135] 22 Grinding plate [0136] 23 Pyrometer [0137] 24 Temperature measuring device [0138] 25 First hemisphere [0139] 26 Second hemisphere [0140] 27 First rotational molding [0141] 28 Second rotational molding [0142] 29 First springs [0143] 30 Second springs [0144] 31 First brush seal [0145] 32 Cover plate [0146] 33 Second brush seal [0147] 34 Brush seal [0148] 35 Rotatably mounted plate [0149] 36 Frame plate

    [0150] FIG. 4 shows an exemplary embodiment of a rotational-molding installation according to the disclosure, which comprises a heating station 1 and a cooling station 2. The heating station 1 is arranged vertically above the cooling station 2.

    [0151] The cooling station 2 has a cooling station housing 3 and the heating station 1 has a heating station housing 4. The heating station housing 4 has a thermally insulating design. In particular, it may advantageously be provided that the heating station housing 4 has a double-walled design, it advantageously being possible to arrange a thermally insulating material, for example glass wool or foam glass or at least one vacuum insulation panel or another insulation material, between the walls.

    [0152] A thermal insulation device 5 is arranged between the heating station housing 4 and the cooling station housing 3. The thermal insulation device 5 contains pointed spacers 6, via which the heating station 1 standing on the cooling station 2 is supported. The thermal insulation device 5 adjoins the four lower edges of the heating station housing 4 and the four upper edges of the cooling station housing 3 around the periphery. The thermal insulation device 5 reduces the transfer of heat from the heating station housing 4 to the cooling station housing 3.

    [0153] The rotational-molding installation comprises a rotational device 9 with a rotary drive 11. The rotational drive 11 contains a first drive motor 12, which drives a drive wheel 13 in rotation about a horizontal axis. The drive wheel 13 is designed to be in frictional contact with the outer side of a rotational-mold holder 14 (not illustrated in this figure), which can be inserted into a receptacle 15 of the rotational device 9.

    [0154] A spherical rotational-mold holder 14 holding a rotational mold 16 may be arranged and driven in rotation in the receptacle 15. This is illustrated in FIGS. 5, 6 and 7. The receptacle 15 comprises laterally arranged grinding plates 22, which hold a rotational-mold holder 14 in position during the rotation operation.

    [0155] The drive wheel 13 together with the first drive motor 12 may be rotated about a vertical axis by means of a second drive motor 17, in order to be able to change the alignment of the horizontal axis of rotation about which the drive wheel 13 rotates. In the event of a change in alignment of the horizontal axis of rotation about which the drive wheel 13 rotates, the alignment of the axis of rotation about which the rotational mold 14 together with the rotational mold 16 held therein rotates also changes automatically.

    [0156] The heating station housing 4 has a downwardly aligned opening 7 and the cooling station housing 3 has an upwardly aligned opening 8. The upper opening 8 in the cooling station housing 3 is in line with the downwardly aligned opening 7 of the heating station housing 4 such that the entire rotational device 9 together with a rotational-mold holder 14 located in the receptacle 15 can be transferred vertically from the cooling station 2 to the heating station 1 and, in reverse, from the heating station 1 back to the cooling station 2. To that end, an elevator with guide rails (not illustrated) is present. A platform 19 of the rotational device 9 is mounted displacably in a motor-driven manner on the guide rails (not illustrated).

    [0157] Along its outer peripheral edge, the platform 19 has a first brush seal 31, which first brush seal 31 is in contact with the inner side of the cooling station housing 3 as long as the elevator is in the lower position (FIGS. 4, 5 and 7) and in contact with the inner side of the heating station housing 4 when the elevator is in the upper position (FIG. 6). The platform 19 closes the downwardly aligned opening 7 in the heating station housing 4 when the elevator is in the upper position (FIG. 6).

    [0158] The platform 19 bears four vertical carriers 18, which for their part bear a thermally insulating cover plate 32, which is arranged parallel to the platform 19. Along its outer peripheral edge, the cover plate 32 has a second brush seal 33 which is in contact with the inner side of the heating station housing 4. The cover plate 32 closes the downwardly aligned opening 7 in the heating station housing 4 when the elevator is in the lower position (FIGS. 4, 5 and 7).

    [0159] The cooling station 2 comprises a cold-air fan (not illustrated in more detail) with a slot-shaped cold-air nozzle 20. The cold-air nozzle 20 is aligned and arranged in such a way that the stream of cold air flowing through it is aligned symmetrically to a rotational-mold holder 14 arranged in the cooling station 2. Specifically, the cold-air nozzle 20 is aligned in such a way that the stream of cold air impinges the spherical rotational-mold holder 14 in an equatorial plane. In this way, it is advantageously ensured that the spherical rotational-mold holder 14 is not additionally driven in rotation by the stream of cold air.

    [0160] The heating station 1 comprises a hot-air fan (not illustrated in more detail), which contains a slot-shaped hot-air nozzle 21. The hot-air nozzle 21 is aligned and arranged in such a way that the stream of hot air flowing through it is aligned symmetrically to a rotational-mold holder 14 arranged in the heating station 1. Specifically, the hot-air nozzle 21 is aligned in such a way that the stream of hot air impinges the spherical rotational-mold holder 14 in an equatorial plane. In this way, it is advantageously ensured that the spherical rotational-mold holder 14 is not additionally driven in rotation by the stream of hot air.

    [0161] A temperature measuring device 24, which is in the form of a pyrometer 23 and by means of which the temperature of the rotational mold 16 can be measured, is present.

    [0162] FIG. 7 shows the exemplary embodiment of the rotational-molding installation according to the disclosure in a situation in which the rotational-molding installation is ready to receive a spherical rotational-mold holder 14 with a rotational mold 16 held therein. The spherical rotational mold holder 14 can be brought into the receptacle 15 horizontally through a lateral opening (not illustrated further) in the cooling station housing 2.

    [0163] Before inserting a rotational-mold holder 14 with a rotational mold 16 held therein into the receptacle 15, it is necessary to charge the rotational mold 16 with rotational-molding material 10. In the exemplary embodiment illustrated, the rotational mold 16 is designed to produce a plant pot. In terms of the type of object to be produced, however, there are no fundamental restrictions.

    [0164] The spherical rotational-mold holder 14 consists of a first hemisphere 25 and a second hemisphere 26, which can be detachably connected to one another. The rotational mold 16 likewise has a two-part structure and has a first rotational-mold part 27 and a second rotational-mold part 28. The first rotational-mold part 27 is fastened to the inside of the first hemisphere 25 by means of first springs 29, whereas the second rotational-mold part 28 is fastened to the inside of the second hemisphere 26 by means of second springs 30. The first hemisphere 25 together with the first rotational-mold part 27 can be lifted off from the second hemisphere 26 together with the second rotational-mold part 28, in order to be able to introduce rotational-molding material 10 into the rotational mold 16 before a rotation operation and to be able to remove the produced product after a rotation operation.

    [0165] After introducing the rotational-molding material 10, the first rotational-mold part 27 is fitted onto the second rotational-mold part 28 and thus closes the rotational-mold holder 16. Subsequently, the rotational-mold holder 14 with a rotational mold 16 held therein can be brought into the receptacle 15 of the rotational device 9 through a lateral opening in the cooling station 2.

    [0166] FIG. 5 shows the exemplary embodiment of the rotational-molding installation after a spherical rotational-mold holder 14 together with a rotational mold 16 held therein has been introduced into the receptacle 15. Subsequently, the entire rotational device 9, together with the rotational-mold holder 14 located in the receptacle and the rotational mold 16, is transferred vertically upward into the heating station 1 by means of the elevator.

    [0167] FIG. 6 shows the situation after the entire rotational device, together with the rotational-mold holder 14 and the rotational mold 16, has been brought vertically upward into the heating station 1 by means of the elevator.

    [0168] In the heating station 1, the rotational mold 16 is heated by means of the hot-air fan. The rotational-mold holder 14 has a plurality of apertures through which the stream of hot air expelled by the hot-air nozzles 21 impinges the rotational mold 16. The rotational mold 16 is rotated and heated at the same time, in order that the previously introduced rotational-molding material 10 can melt and accumulate on the inner side of the rotational mold 16. In the process, the rotational-mold holder 14 is held in position whilst it rotates by means of the laterally arranged grinding plates 22. The rotational-mold holder 14 remains stationary within the heating station 1 during the rotation operation.

    [0169] After all of the rotational-molding material 10 has accumulated on the inner wall of the rotational mold 16, the entire rotational device 9, together with the rotational-mold holder 14 located in the receptacle 15 and the rotational mold 16, is transferred vertically downward into the cooling station 2 by means of the elevator. In the process, the rotational-mold holder 14 together with the rotational mold 16 continues to be rotated.

    [0170] FIG. 7 shows the situation after the entire rotational device, together with the rotational-mold holder 14 and the rotational mold 16, has been brought vertically downward back into the heating station 2 by means of the elevator.

    [0171] In the cooling station 2, the rotational mold 16 is actively cooled by means of the cold-air fan, whilst the drive device uninterruptedly drives the spherical rotational-mold holder 14 in rotation.

    [0172] As soon as the temperature measuring device 24 has established that the rotational mold 16 has cooled down enough, the spherical rotational-mold holder 14 together with the rotational mold 16 can be removed through the lateral opening (not illustrated) in the cooling station housing 3. The rotational-molding installation is then ready to receive a spherical rotational-mold holder 14, freshly charged with rotational-molding material 10, together with a rotational mold 16 held therein and to begin the depicted sequence anew.

    [0173] FIG. 8 shows a further exemplary embodiment of a rotational-molding installation according to the disclosure, which comprises a heating station 1 and a cooling station 2. The heating station 1 is arranged vertically above the cooling station 2.

    [0174] The cooling station 2 has a cooling station housing 3 and the heating station 1 has a heating station housing 4. The heating station housing 4 has a thermally insulating design. In particular, it may advantageously be provided that the heating station housing 4 has a double-walled design, it advantageously being possible to arrange a thermally insulating material, for example glass wool or foam glass or at least one vacuum insulation panel or another insulation material, between the walls.

    [0175] A thermal insulation device 5 and an inwardly protruding brush seal 34 are arranged between the heating station housing 4 and the cooling station housing 3. The thermal insulation device 5 contains pointed spacers 6, via which the heating station 1 standing on the cooling station 2 is supported. The thermal insulation device 5 adjoins the four lower edges of the heating station housing 4 and the four upper edges of the cooling station housing 3 around the periphery. The thermal insulation device 5 reduces the transfer of heat from the heating station housing 4 to the cooling station housing 3.

    [0176] The rotational-molding installation comprises a rotational device 9 with a rotary drive 11. The rotational drive 11 contains a first drive motor 12, which drives a drive wheel 13 in rotation about a horizontal axis. The drive wheel 13 is designed to be in frictional contact with the outer side of a rotational-mold holder 14 (not illustrated in this figure), which can be inserted into a receptacle 15 of the rotational device 9.

    [0177] A spherical rotational-mold holder 14 holding a rotational mold 16 may be arranged and driven in rotation in the receptacle 15. This is illustrated in FIGS. 5, 6 and 7. The receptacle 15 comprises laterally arranged grinding plates 22, which hold a rotational-mold holder 14 in position during the rotation operation.

    [0178] The drive wheel 13 together with the first drive motor 12 may be rotated about a vertical axis by means of a second drive motor 17, in order to be able to change the alignment of the horizontal axis of rotation about which the drive wheel 13 rotates. In the event of a change in alignment of the horizontal axis of rotation about which the drive wheel 13 rotates, the alignment of the axis of rotation about which the rotational mold 14 together with the rotational mold 16 held therein rotates also changes automatically.

    [0179] The drive wheel 13 protrudes through a slot in a round plate 35, which is rotatably mounted and which is always rotated together with the drive wheel 13 about a vertical axis. The plate 35 is rotatably mounted in a frame plate 36.

    [0180] The heating station housing 4 has a downwardly aligned opening 7 and the cooling station housing 3 has an upwardly aligned opening 8. The upper opening 8 in the cooling station housing 3 is in line with the downwardly aligned opening 7 of the heating station housing 4 such that the entire rotational device 9 together with a rotational-mold holder 14 located in the receptacle 15 can be transferred vertically from the cooling station 2 to the heating station 1 and, in reverse, from the heating station 1 back to the cooling station 2. To that end, an elevator with guide rails (not illustrated) is present. A platform 19 of the rotational device 9 is mounted displacably in a motor-driven manner on the guide rails (not illustrated).

    [0181] By bearing against the brush seal 34, the plate 35 and the frame plate 36 close the downwardly aligned opening 7 in the heating station housing 4 when the elevator is in the upper position, as shown in FIG. 10.

    [0182] The platform 19 bears four vertical carriers 18, which for their part bear a thermally insulating cover plate 32, which is arranged parallel to the platform 19. By bearing against the brush seal 34, the cover plate 32 closes the downwardly aligned opening 7 in the heating station housing 4 when the elevator is in the lower position (FIGS. 8, 9 and 11).

    [0183] The cooling station 2 comprises a cold-air fan (not illustrated in more detail) with a slot-shaped cold-air nozzle 20. The cold-air nozzle 20 is aligned and arranged in such a way that the stream of cold air flowing through it is aligned symmetrically to a rotational-mold holder 14 arranged in the cooling station 2. Specifically, the cold-air nozzle 20 is aligned in such a way that the stream of cold air impinges the spherical rotational-mold holder 14 in an equatorial plane. In this way, it is advantageously ensured that the spherical rotational-mold holder 14 is not additionally driven in rotation by the stream of cold air.

    [0184] The heating station 1 comprises a hot-air fan (not illustrated in more detail), which contains a slot-shaped hot-air nozzle 21. The hot-air nozzle 21 is aligned and arranged in such a way that the stream of hot air flowing through it is aligned symmetrically to a rotational-mold holder 14 arranged in the heating station 1.

    [0185] Specifically, the hot-air nozzle 21 is aligned in such a way that the stream of hot air impinges the spherical rotational-mold holder 14 in an equatorial plane. In this way, it is advantageously ensured that the spherical rotational-mold holder 14 is not additionally driven in rotation by the stream of hot air.

    [0186] A temperature measuring device 24, which is in the form of a pyrometer 23 and by means of which the temperature of the rotational mold 16 can be measured, is present. A tube of the pyrometer 23, through which the pyrometer receives radiation, protrudes through an opening in the frame plate 36.

    [0187] FIG. 8 shows the exemplary embodiment of the rotational-molding installation according to the disclosure in a situation in which the rotational-molding installation is ready to receive a spherical rotational-mold holder 14 with a rotational mold 16 held therein. The spherical rotational mold holder 14 can be brought into the receptacle 15 horizontally through a lateral opening (not illustrated further) in the cooling station housing 2.

    [0188] Before inserting a rotational-mold holder 14 with a rotational mold 16 held therein into the receptacle 15, it is necessary to charge the rotational mold 16 with rotational-molding material 10. In the exemplary embodiment illustrated, the rotational mold 16 is designed to produce a plant pot. In terms of the type of object to be produced, however, there are no fundamental restrictions.

    [0189] The spherical rotational-mold holder 14 consists of a first hemisphere 25 and a second hemisphere 26, which can be detachably connected to one another. The rotational mold 16 likewise has a two-part structure and has a first rotational-mold part 27 and a second rotational-mold part 28. The first rotational-mold part 27 is fastened to the inside of the first hemisphere 25 by means of first springs 29, whereas the second rotational-mold part 28 is fastened to the inside of the second hemisphere 26 by means of second springs 30. The first hemisphere 25 together with the first rotational-mold part 27 can be lifted off from the second hemisphere 26 together with the second rotational-mold part 28, in order to be able to introduce rotational-molding material 10 into the rotational mold 16 before a rotation operation and to be able to remove the produced product after a rotation operation.

    [0190] After introducing the rotational-molding material 10, the first rotational-mold part 27 is fitted onto the second rotational-mold part 28 and thus closes the rotational-mold holder 16. Subsequently, the rotational-mold holder 14 with a rotational mold 16 held therein can be brought into the receptacle 15 of the rotational device 9 through a lateral opening in the cooling station 2.

    [0191] FIG. 9 shows the exemplary embodiment of the rotational-molding installation after a spherical rotational-mold holder 14 together with a rotational mold 16 held therein has been introduced into the receptacle 15. Subsequently, the entire rotational device 9, together with the rotational-mold holder 14 located in the receptacle and the rotational mold 16, is transferred vertically upward into the heating station 1 by means of the elevator.

    [0192] FIG. 10 shows the situation after the entire rotational device, together with the rotational-mold holder 14 and the rotational mold 16, has been brought vertically upward into the heating station 1 by means of the elevator.

    [0193] In the heating station 1, the rotational mold 16 is heated by means of the hot-air fan. The rotational-mold holder 14 has a plurality of apertures through which the stream of hot air expelled by the hot-air nozzles 21 impinges the rotational mold 16. The rotational mold 16 is rotated and heated at the same time, in order that the previously introduced rotational-molding material 10 can melt and accumulate on the inner side of the rotational mold 16. In the process, the rotational-mold holder 14 is held in position whilst it rotates by means of the laterally arranged grinding plates 22. The rotational-mold holder 14 remains stationary within the heating station 1 during the rotation operation.

    [0194] After all of the rotational-molding material 10 has accumulated on the inner wall of the rotational mold 16, the entire rotational device 9, together with the rotational-mold holder 14 located in the receptacle 15 and the rotational mold 16, is transferred vertically downward into the cooling station 2 by means of the elevator. In the process, the rotational-mold holder 14 together with the rotational mold 16 continues to be rotated.

    [0195] FIG. 11 shows the situation after the entire rotational device, together with the rotational-mold holder 14 and the rotational mold 16, has been brought vertically downward back into the heating station 2 by means of the elevator.

    [0196] In the cooling station 2, the rotational mold 16 is actively cooled by means of the cold-air fan, whilst the drive device uninterruptedly drives the spherical rotational-mold holder 14 in rotation.

    [0197] As soon as the temperature measuring device 24 has established that the rotational mold 16 has cooled down enough, the spherical rotational-mold holder 14 together with the rotational mold 16 can be removed through the lateral opening (not illustrated) in the cooling station housing 3. The rotational-molding installation is then ready to receive a spherical rotational-mold holder 14, freshly charged with rotational-molding material 10, together with a rotational mold 16 held therein and to begin the depicted sequence anew.

    [0198] The exemplary embodiment illustrated in FIGS. 7 to 11 has the particular advantage that the rotary drive 11 (except for a small part of the drive wheel 13 protruding through the plate 35) always remains outside of the heating station 1. As a result, the rotary drive 11 is not conjointly heated, thereby conserving the rotary drive 11 and contributing to a saving on energy.

    [0199] LIST OF REFERENCE SIGNS:

    [0200] 1 Rotational-mold holder

    [0201] 2 Rotational mold

    [0202] 3 First hemisphere

    [0203] 4 Second hemisphere

    [0204] 5 First rotational molding

    [0205] 6 Second rotational molding

    [0206] 7 First springs

    [0207] 8 Second springs

    [0208] 9 Rotational-molding material

    [0209] 10 Drive device

    [0210] 11 Drive motor

    [0211] 12 Drive wheel

    [0212] 13 Further drive device

    [0213] 14 Second drive motor

    [0214] 15 Grinding plate

    [0215] 16 Input device

    [0216] 17 Display device

    [0217] 18 Input unit

    [0218] 19 Control device

    [0219] 20 Trajectory segment type

    [0220] 21 Timeline

    [0221] 22 Trajectory segment

    [0222] 23 Trajectory segment

    [0223] 24 Trajectory segment

    [0224] 25 Trajectory

    [0225] 26 Preview display

    [0226] 27 Computer mouse

    [0227] 28 Reference point

    [0228] 29 Selection display