Method for producing a container
11472074 · 2022-10-18
Assignee
Inventors
Cpc classification
B29C45/0062
PERFORMING OPERATIONS; TRANSPORTING
B29K2023/065
PERFORMING OPERATIONS; TRANSPORTING
F01N2610/1406
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B29C2045/0063
PERFORMING OPERATIONS; TRANSPORTING
B29L2031/712
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A method for producing a thermoplastic container (1) for gases or liquids. First, in an injection mould having a first (28) and a second mould (29), in a first position providing each a cavity (34) for an upper (2) and a lower shell (3), producing the shells in parallel. Next, opening the mould, the shells (2, 3) remaining in a respective mould. Then, turning or shifting at least one of the two moulds such that the concave interior sides of the shells are aligned against each other and closing the mould, so that the edge regions (7, 8) of the shells come into face-to-face contact. Injection material is injected into a cavity (49) between or adjacent to the edge areas (7, 8), forming an all-round welded seam (11) between the upper part (2) and the lower part (3). Finally the mould is opened and the at least one container is removed.
Claims
1. A method for producing a container for carrying or storing gases or liquids which is made from a thermoplastic plastics material, wherein the method has the following step sequence: in an injection mold having a first mold and a second mold, which, in a first injection molding position, together provides at least one cavity for an upper shell of said container as well as at least one cavity for a lower shell of said container, at least one upper shell and at least one lower shell are produced in parallel in an injection molding method; opening the injection mold, wherein the at least one upper shell remains in the first mold and the at least one lower shell remains in the second mold; at least one of rotating or displacing at least one of the two molds so that, after the rotation or displacement, the concave inner sides of the shells are directed towards one another and closing the mold to realize a second injection molding position, so that substantially congruent edge regions of the shells come into at least partial planar contact; injecting injection molding material into a cavity between or adjoining the edge regions to form a circumferential weld seam between the upper shell and lower shell and to form said container; and opening the injection mold and removing the at least one container; wherein the position of the first mold relative to the second mold, as seen in a closing direction, is arranged at a different height in the first injection molding position than in the second injection molding position.
2. The method as claimed in claim 1, wherein the step sequence is followed by the following step: at least one of rotating or displacing at least one of the two molds so that a first injection molding position is in turn assumed, which provides at least one cavity for an upper shell and at least one cavity for a lower shell, and cyclically repeating the step sequence to produce a plurality of containers.
3. The method as claimed in claim 1, Wherein a closing force in the range of 300-3000 t is built up both in the first injection molding position and in the second injection molding position.
4. The method as claimed in claim 1, wherein the upper shell and lower shell each have a concave inner side and a convex outer side, and in that the edge regions have a outwardly or inwardly directed flange, and wherein, in a contact surface of at least one of the flanges, or both flanges, which faces the other flange in each case, or mutually abutting wall regions adjoining the flanges, a circumferential channel is provided so that, when the flanges or wall regions of the upper shell and lower shell are in planar contact, a cavity is formed into which thermoplastic plastics material is injected in the second injection molding position to form the weld seam.
5. The method as claimed in claim 4, wherein the edge regions have a circumferential flange, and wherein, in the contact surface of at least one or both of the flanges, which faces the other flange in each case, or the mutually abutting wall regions adjoining the flanges, a circumferential channel is provided so that, when the flanges or wall regions of the upper shell and lower shell are in planar contact, a cavity is formed into which thermoplastic plastics material is injected in the second injection molding position to form the weld seam.
6. The method as claimed in claim 1, wherein at least one of the molds is formed such that baffles projecting into the interior of the container are formed.
7. The method as claimed in claim 6, wherein a protruding contour is formed on at least one angled slide and, for releasing the formed container, an angled slide is displaced laterally to release a depression generated by the contour, or a hole generated by the contour, in the injection molded component.
8. The method as claimed in claim 1, wherein a further structural element is connected to the container after the production of the container.
9. The method as claimed in claim 8, wherein, after previously fastening an adapter plate to a dosing unit, the dosing unit is placed in the mold before the first injection molding position is assumed and, when forming a corresponding half shell, the dosing unit is overmolded with the material of the half shell to form a tight connection between the dosing unit and half shell or the adapter plate and half shell.
10. The method as claimed in claim 1, wherein the thermoplastic material of at least one of the shells or the weld seam, is a polyolefin material.
11. The method as claimed in claim 1, wherein, when opening the injection mold after the production of the two shells, the at least one upper shell remains in the first mold and the at least one lower shell remains in the second mold.
12. The method as claimed in claim 1, wherein the step sequence is followed by the following step: at least one of rotating or displacing at least one of the two molds so that a first injection molding position is in turn assumed, which provides at least one cavity for an upper shell and at least one cavity for a lower shell, and cyclically repeating the step sequence to produce a plurality of containers, wherein the injection mold is designed for simultaneous production of a container and the rotation of one of the two molds takes place through 180°, or the injection mold is designed for simultaneous production of n containers and the rotation of one of the two molds takes place through an angle of 360°/2n.
13. The method as claimed in claim 1, wherein a closing force in the range of 400-2000 t, is built up both in the first injection molding position and in the second injection molding position.
14. The method as claimed in claim 1, wherein the upper shell and lower shell each have a concave inner side and a convex outer side, and in that the edge regions have a circumferential, outwardly directed flange, and wherein, in a contact surface of at least one of the flanges, or both flanges, which faces the other flange in each case, or the mutually abutting wall regions adjoining the flanges, a circumferential channel is provided so that, when the flanges or wall regions of the upper shell and lower shell are in planar contact, a cavity is formed into which thermoplastic plastics material is injected in the second injection molding position to form the weld seam.
15. The method as claimed in claim 5, wherein the at least one channel, or both channels, have a substantially semi-circular, semi-elliptical, polygonal, rectangular, triangular or trapezoidal cross-section, or wherein at least one recess or hole, or a plurality of recesses and/or holes which are distributed over the circumference, is provided in at least one of the flanges, or in both flanges, so that a weld seam having at least one peg is formed, wherein the recesses or holes can be formed radially outwardly between the flanges or such that they pass through the respective flange.
16. The method as claimed in claim 1, wherein at least one of the molds is formed such that baffles projecting into the interior of the container are formed, wherein these baffles have holes which are realized via at least one angled slide in at least one of the molds.
17. The method as claimed in claim 1, wherein a further structural element, in the form of a dosing unit or a seal, is connected to the container after the production of the container, or during the production of the container, wherein this connection takes place via an adapter plate.
18. The method as claimed in claim 1, wherein the thermoplastic material of at least one of the shells or the weld seam, the thermoplastic material of the two shells and the weld seam, is a polyolefin material with a high density of at least 0.94 g/cm3, or HD-PE or PP, in a glass-fiber reinforced or non-reinforced form.
19. The method as claimed in claim 1, wherein, when opening the injection mold after the production of the two shells, the at least one upper shell remains in the first mold and the at least one lower shell remains in the second mold, in a respective concave mold contour which forms the outer side of a respective half shell, and wherein ejectors and/or undercuts are used to ensure that the respective shell remains in the corresponding mold.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Preferred embodiments of the invention are described below with reference to the drawings, which merely serve for explanation and should not be seen as restrictive. The drawings show:
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DESCRIPTION OF PREFERRED INVENTIVE EMBODIMENTS
(17) A container produced according to the inventive method is illustrated in various views in
(18) The container 1 is formed by an upper shell 2 and a lower shell 3, which adjoin one another along a planar parting plane 56, which extends essentially horizontally. In this parting plane, the upper shell 2 has a circumferential flange 7 and the lower shell 3 has a corresponding circumferential flange 8. The two half shells enclose a substantially closed cavity 50.
(19) The top surface 17 of the upper shell 2 is formed substantially as a plane, whilst the bottom surface 19 of the lower shell 3 has a stepped form. Specifically, in the lower shell 3, there is a depressed region 4 which is deeper and in which a hole 15 is provided. A dosing unit 5 is arranged in this hole 15, wherein this dosing unit 5 is tightly fastened to the lower shell 3 via an adapter plate 6, which will be returned to further below.
(20) Such a container has an approximate length of 550 mm and a width of circa 450 mm. Its height is in the region of circa 250 mm and such a container can be used, for example, in the automotive field for storing liquids, in particular for storing urea in diesel motor vehicles. The individual half shells are produced in an injection molding method from a thermoplastic plastics material, notably HD-PE here, in a multi-stage injection molding method, as will be explained further below.
(21) So-called baffles 9 are arranged in the interior 50 of the container; more precisely, both projecting into the interior 50 from the top surface 17 of the upper shell and into the interior 50 from the bottom surface 19 of the lower shell 3. These baffles a prevent the liquid which is located in the interior 50 of the container from being shaken up too much during movement of the container and, in particular, irritating noises from occurring.
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(23) As can likewise be seen, the upper shell 2 has a top surface 17, from which a wall 18 is formed circumferentially downwards and on the lower edge of which the said flange 7 is circumferentially formed. The flange 7 has holes distributed uniformly over its circumferential length, which will likewise be returned to later.
(24) Similarly, the lower shell 3 has a closed circumferential wall 20, on the upper edge of which the said flange 8 is formed. In this flange 8, there are also holes distributed over its circumferential length.
(25) In a circumferential groove 24/25 of flange 7 or flange 8, a container weld seam 11 made from the same material as the two shells 2, 3 is formed in the respective contact region with the corresponding counter shell. Since both flange 7 and flange 8 have holes, this container weld seam has a corresponding number of pegs 14 which are directed perpendicularly to the main plane of the weld seam and result in a form fit also being provided to a certain extent between the two half shells 2 and 3 in addition to the material fit generated by the weld seam 11. Moreover, this design of the flanges 7, 8 results in the material which is injected as the container weld seam 11 being distributed as homogeneously as possible in the corresponding circumferential cavity, formed by the grooves 24/25, in the injection molding process.
(26) The design of the weld seam 11 in the region of the mutually adjoining flanges 7, 8 is illustrated specifically in
(27) Similarly, the flange 8 of the lower part 3 in turn has a circumferential channel 24 on its surface facing the upper part 2. These channels are delimited externally by an outer contact region 26, in which the two flanges 7, 8 adjoin one another directly, and via an inner contact region 27, in which the two flanges 7, 8 likewise lie directly against one another. Therefore, when the two separately injection molded shells 2, 3 are placed correctly against one another so that the surfaces of the flanges come to lie against one another, a circumferential cavity into which the material for the container weld seam 11 can be injected directly, as will be explained further below, is formed between the two flanges 7, 8 via two corresponding channels 24, 25. So that this injection procedure into this cavity formed by the channels 24/25 proceeds as optimally as possible, i.e. both the mechanical strength and the leak-tightness can be ensured by the seal 11, a labyrinth seal is essentially formed in this case on that side of the respective flange 7, 8 which faces the inside of the container. Specifically, the flange 8 of the lower shell 3 has a circumferential ridge 22 and the flange 7 of the upper shell 2 has a corresponding circumferential groove 23. The groove 23 of the flange of the upper shell and the ridge 22 of the flange of the lower shell engage in one another with planar contact and therefore form a leak-tight delimitation of the cavity provided for forming the weld seam 22 (in the manner of a tongue-and-groove connection), which delimitation also withstands the injection molding process of the weld seam.
(28) As already mentioned above, the two flanges 7, 8 have holes which are formed perpendicularly to the plane of the flanges and distributed over the circumferential length of the flanges 7, 8. During the injection of the weld seam 11, injection molding material is likewise incorporated into these holes, whereupon a plurality of pegs 14 is formed. On the one hand, this design of the flanges with the holes has the advantage that the injection molding material, which is usually introduced into injection points distributed along the circumference of the flange at 3-4 injection molding points, can be distributed as effectively as possible around the entire circumference and an optimal mechanical strength and leak-tightness are ensured. However, a further consequence of this is that, in addition to a purely material fit, a substantial contribution can be provided by a form fit between the respective shell and the material of the weld seam 11.
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(30) The process begins with the closed mold illustrated as 4.1. The mold is formed by the core-side mold 29 and the nozzle-side mold 28. The nozzle-side mold 28 is stationary—the injection molding materials are fed in here—whereas the core-side mold 29 can be rotated through 180 degrees. The closed mold 4.1 provides the cavity for the upper shell 2 at the top and the cavity for the lower shell 3 at the bottom.
(31) As illustrated in the following state 4.2, the injection molding material for the upper shell and lower shell is now introduced into this closed mold in a first step and the upper and the lower cavity are filled accordingly. In this 1.sup.st step, therefore, the upper shell and lower shell are individually manufactured in an injection molding process in a single mold.
(32) After cooling of the mold, the mold is opened, wherein, as a result of undercuts, formed accordingly in the cavities, and/or ejectors, it is ensured that the upper shell 2 remains in the nozzle-side mold and the lower shell 3 remains in the core-side mold 29. The open mold is illustrated in 4.3.
(33) As illustrated in 4.4, the left half shell of the mold is now rotated, in that the core-side mold 29 is turned through 180 degrees so that the lower part 3 and upper part 2, which have been newly injection molded in step 4.2, are brought into the correct position provided for closing.
(34) As illustrated in 4.5, the mold is subsequently closed again so that the flanges 7 and 8 already discussed above now come into correct complementary tight contact and the cavity is formed accordingly in the channels 24 and 25 for the weld seam to be formed and so that, as illustrated in 4.6, the material for the weld seam 11 can now be injected into this cavity and the upper shell 2 and lower shell 3 can therefore be connected to one another.
(35) As illustrated in 4.7, the mold is subsequently allowed to cool and then, as illustrated in 4.8, the mold is opened, wherein it is deliberately provided that the finished container is retained in the desired mold—in the core-side mold 29 here (undercuts and/or ejectors).
(36) As illustrated in 4.9, the finished container is subsequently removed from the mold, typically via a robot, and possibly subjected to further processing steps.
(37) As illustrated in 4.10, the core-side mold 29 is in turn subsequently rotated back through 180 degrees and the mold is closed again so that, at the end, the original state 4.1 is in turn reached and the process can be carried out again in a cyclical manner.
(38) The individual steps of this method shall now be explained in detail with reference to the illustrations of
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(40) It can likewise be seen how an angled slide 42 is arranged there. This angled slide 42 is provided to enable the formation of the holes 10 in the baffles 9. This is done such that, on the angled slide 42, on the surface remote from the lifting segment 41 and the surface facing the baffle segment to be formed, the corresponding contours for forming the holes are provided (in the form of pegs). Therefore, with reference to the holes in the baffles 9, the region 46 is essentially topologically prescribed by the angled slide 42. After the injection procedure, when the newly injection molded upper shell 2 is then to be released, the angled slide 42 can be displaced slightly, relative to the lifting segment 41, the peg-shaped shaping elements on the angled slide 42, which reach into the holes formed in the corresponding baffle 9, are thus drawn out of these holes and the formed molded part 2 is released and can then be removed. The pin ejectors 40 for the lower shell can likewise be seen here.
(41) The cavity 34 for the upper shell 2 is formed in the upper region between the nozzle-side mold 28 and the core-side mold 29. It is formed by the delimiting contour 36 on the core-side mold and the delimiting contour 37 on the nozzle-side mold.
(42) Analogously, the lower shell 3 is formed in the lower region of the tool by the cavity 35, which is formed by the delimiting contour 38 on the core-side mold and by the delimiting contour 39 on the nozzle-side mold.
(43) In this case, the parting plane of the mold has a stepped form. In the upper region for producing the upper shell 2, the parting plane 47 is arranged further to the left in this first injection molding position and, in the lower region for producing the lower shell 3, the parting plane 48 is arranged further to the right. Accordingly, in the closing direction 57, the parting plane of the region for producing the lower shell 3 is arranged further forwards in the first injection molding position. When the two half shells 2, 3 are different, this stepped parting plane is then important to prevent the regions which are not used, which are the regions which form the concave inner surface of the respective shell, from colliding with one another in the second injection molding position, as illustrated, for example, in
(44) As illustrated in
(45) In this first position, which is denoted by a number 1 in the circle below the figure, the necessary closing force of, for example, 500-1000 t for this procedure is applied. The injection molding machine carrying the mold should be capable of applying this closing force in the first injection molding position.
(46) As illustrated in
(47) The core-side mold 29 is subsequently rotated through 180 degrees via the rotary plate 32, as is then illustrated in the end position in
(48) In the next step, the mold is closed, which leads to the end state as illustrated in
(49) The two flanges 7, 8 now adjoin one another with direct and planar contact so that a circumferential cavity 49 is formed in the two circumferential channels 24, 25 discussed above. Material is now injected directly into this cavity 49 via 3-4 injection-molding material feed channels 44 so that a material-fitting connection, supported by a form-fitting connection, is formed between the two half shells, specifically via the weld seam 11. The material injected here is typically the same as the material for the half shells, i.e. HD-PE in the present case.
(50) In this second position, which is denoted by a number 3 in the circle below the figure, the necessary closing force for this procedure, again of 500-1000 t, for example, is applied.
(51) The injection molding machine carrying the mold should be capable of applying this closing force in the second injection molding position, which is arranged at a different height in the closing direction, notably further back in the closing direction 57 in this case.
(52) As can be seen in
(53) In turn, after an appropriate cooling time, the mold is opened again, as illustrated in
(54) Subsequently, using the pin ejectors 40, as illustrated in
(55) Subsequently, as illustrated in
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(57) This dosing unit 5 connected to the adapter plate 6 is preferentially subsequently placed directly into a corresponding cavity in the contour 38, and, in an in-mold method, an edge taper 53 of the adapter plate 6 is subsequently overmolded directly with the material of the lower shell in the region 54 and a durably fixed and tight connection is thus ensured between the adapter plate 6 with the dosing unit 5 on the lower part 3 of the container 1.
(58) The individual steps, now shown in terms of the parts rather than in terms of the tool, are summarized once again in
(59) In the following step 7.2, the separately produced dosing unit 5 is connected to the adapter plate 6 in a hot plate welding method.
(60) Then, in step 7.3, after the dosing unit 5 with the adapter plate 6 fastened thereto has been inserted into the mold (specifically into the cavity 35), the step sequence which is indicated in 7.3-7.5 and which generates the closed container (as illustrated bottom right in a perspective illustration) via the weld seam 11, will take place in the tool, as illustrated in
(61) According to the conventional method, such containers are typically produced in that the upper shell 2 and the lower shell 3 are produced in an individual production process and the two shells are subsequently connected to one another along the equator line in a hot plate method. As a result, this method substantially only enables constructions which, as illustrated in the upper row in
(62) A substantial advantage of the method proposed here is that this connecting line no longer necessarily has to be formed as a plane. As illustrated in the lower row of
(63) In
(64) Various design options for the mutually adjoining edge region of the upper shell 2 and lower shell 3 are illustrated in
(65) In the actual joint region of the walls of the upper shell 2 and lower shell 3, these adjoin one another such that a mechanical labyrinth seal 21 is formed, substantially analogously to the situation which was illustrated in
(66) As illustrated on the bottom right of
(67) As illustrated in
(68) Likewise in contrast to
(69) In general, the injection point is preferably arranged externally along the connecting lines of the two bottle or the wall portions adjoining one another edge to edge; this will also be returned to in particular in association with
(70) A further alternative design of such a weld connection is illustrated in
(71) In this case, the pegs 14 are also formed by a series of preferentially uniformly spaced holes in the respective flange 7/8 which are distributed over the circumference of the weld connection. In this case, there are also webs 61 as retention means for component shrinkage. This construction is, in particular, also particularly stable with regard to a torque load when a torque 60 is applied, as illustrated schematically in
(72) A container in the form of a fill pipe is illustrated in
(73) In
(74) As can be seen with reference to
(75) The weld seam connection proposed here can also be used in association with other containers, as illustrated here in
(76) In
(77) A possible mold for producing such a container body according to
(78) The upper shell 2 formed in the first step now lies directly opposite the lower shell 3 formed in the first step and the flange regions adjoin one another, wherein a cavity for the weld seam 11 is formed, as can best be seen in
(79) To enable the required molding pressure to be exerted on the molds in both positions without tilting moments occurring, tool supports 77 are advantageously provided, as well as the guide pegs 78 already mentioned above and the corresponding guide openings 79.
(80) Owing to the corresponding arrangement of a plurality of such guide pegs 78 and corresponding openings 79, it is possible to be able to ensure both optimum guidance and optimum support, also via the tool support columns 77, in both production positions. To enable the forces to be absorbed, it is furthermore advantageous if an auxiliary cavity 75 is arranged on the core side. This auxiliary cavity 75 has a complementary mold 81 which, in the second production step, comes into contact with the nozzle-side mold for the first step for the lower shell.
(81) The containers according to
(82) TABLE-US-00001 LIST OF REFERENCE SIGNS 1 Container 2 Upper shell of 1 3 Lower shell of 1 4 Depressed region von 3 5 Dosing unit 6 Adapter plate 7 Flange on 2 8 Flange on 3 9 Baffle 10 Holes in 9 11 Container weld seam 12 Circumferential rib of 5 13 Hole in 6 14 Peg on 11 15 Hole in the base of 4 16 Regions of 5 projecting into the container 17 Top surface of 2 18 Circumferential wall of 2 19 Bottom surface of 3 20 Circumferential wall of 3 21 Mechanical Labyrinth-Seal 22 Ridge on 8 23 Groove in 7 24 Circumferential channel in 8 25 Circumferential channel in 7 26 Outer contact region between 7 and 8 27 Inner contact region between 7 und 8 28 Nozzle-side mold 29 Core-side mold 30 Production machine nozzle-side, clamping plate 31 Production machine core side, clamping plate 32 Rotary plate for 29 33 Rotation of 29 34 Cavity for 2 35 Cavity for 3 36 Delimiting contour of 34 on 29 37 Delimiting contour of 34 on 28 38 Delimiting contour of 35 on 29 39 Delimiting contour of 35 on 28 40 Pin ejector 41 Lifting segment 42 Angled slide 43 Injection-molding material feed for 2 to 34 in 28 44 Injection-molding material feed for 11 in 28 45 Injection-molding material feed for 3 to 35 in 28 46 Region of 34 for 9 47 Parting plane/closure plane of region for upper shell of 28 48 Parting plane/closure plane of region for lower shell of 28 49 Cavity formed between 7 and 8 through 24 and 25 for 11 50 Enclosed cavity of 1 51 Upper edge of 12 52 Lower side of 13 53 Edge taper of 13 54 Overmolded region 55 Weld seam 56 Parting plane between 2 and 3 57 Closing direction 58 Support, extension 59 Contact surface of 58 60 Torque load 61 Retention means Component shrinkage 62 Injection opening for weld seam material 63 Connecting flange 64 Insertion region 65 Holding tongue 66 Non-equatorial weld seam region 67 Equatorial weld seam region 68 Flow openings in 3 69 Connecting piece 70 Clamping plate, nozzle side 71 Molding plate, nozzle side 72 Clamping plate, core side 73 Molding plate, core side 74 Mold inserts, core side 75 Auxiliary cavity, core side 76 Hydraulic cylinder, core side 77 Tool support 78 Guide pegs on 71 79 Guide openings in 73 80 Ejector system, core side 81 Complementary mold of 75 4.1 Tool closed 4.2 Injection 01, Upper shell/lower shell 4.3 Tool open 4.4 Rotate open tool with injection molded shells +180° 4.5 Close tool with injection molded shells 4.6 Injection 02, weld seam 4.7 Cooling time, tool closed 4.8 Tool open 4.9 Remove tool from mold 4.10 Rotate tool −180° 7.1 Single component injection molding of 13 from HD-PE 7.2 Hot seal welding of 13 to 5 7.3 Injection 01 according to 4.2, Upper shell and lower shell from HD-PE 7.4 Change position 7.5 Injection 02 of 11 from HD- PE l Length of 1 b Width of 1 h Height of 1