Method for producing a tub-shaped sanitary appliance made of plastic having a visible side and a bottom

Description

[0001] The invention relates to a method for producing a tub-shaped sanitary article made of plastic having a visible side and a bottom.

[0002] Generic methods and forming devices are described in the patents EP2295162B1, US4750967A, CN111805878A and US2011 / 000013A1.

[0003] Such tub-shaped sanitary ware is usually a bathtub or shower tray and is manufactured from a plastic sheet, usually an acrylic sheet, using a deep-drawing process, often also called thermoforming. In this process, the plastic sheet is preheated to 180-200°C so that it softens and assumes a malleable state. The plastic sheet is placed in a mold, clamped in place at the sides, and sucked against the mold from the mold side by applying negative pressure. The mold thereby reproduces the entire flat underside of the tub-shaped formed part, including all edges, recesses, and surfaces. A plurality of suction channels are distributed across the mold surface so that the plastic sheet is sucked in at several points. After suction and the resulting reproduction of the mold surface onto the plastic sheet, the formed plastic sheet is cooled and then removed from the mold.The formed part is then provided with a reinforcement layer, usually a GRP layer, on its underside to increase stability. If necessary, additional reinforcement elements such as reinforcement plates made of flax, wood, or fibers are added to the GRP reinforcement and embedded, for example, in the reinforcement layer.

[0004] During deep drawing, the plastic sheet is stretched inhomogeneously, which leads to an inhomogeneous thickness of the formed object. For this reason, a suitably thick plastic sheet must always be used, whereby the thickness ultimately depends on the degree of forming. The thickness must be selected so that in the areas where the material is stretched the most, the resulting thickness after deep drawing is still sufficient. Since the material is sucked against the forming surface and lies against it, it inevitably cannot flow freely due to the corresponding friction and adhesion caused by the contact and suction, which is one of the causes of inhomogeneous forming. If the material is stretched too much, the appearance of the product deteriorates. An orange peel effect typically occurs in areas of high stretch. Any imperfection that occurs in the mold is imprinted on the plastic sheet.Further limitations arise from the fact that the material must adapt to the inner radii, i.e. the geometry of the deep-drawing mold in the area of ​​bends. This means that the inner radii are usually in the range of 40 mm; sharper radii are not possible. In any case, the inside of the molded part, i.e. the visible side of the future sanitary object, must be manually reworked, i.e. sanded and polished, in order to eliminate any defects or ensure homogeneity. A further disadvantage of the deep-drawing process is that only one type of object can be produced with one mold, for example a shower tray or bathtub with a defined, unchanging geometry such as a defined depth. If a tray of this kind that is somewhat deeper is to be produced, a new mold must be built and used. Even for trays that only differ in the position of the drain, a separate mold is necessary.

[0005] The invention is therefore based on the problem of providing an improved method for producing such a sanitary article.

[0006] To solve this problem, the invention provides a method for producing a tub-shaped sanitary article made of plastic having a visible side and a bottom, comprising the following steps: Providing a plastic sheet to be formed to form the sanitary article, providing a forming device comprising a frame arrangement with a first frame with a first frame-shaped bending structure and a second frame with a second frame-shaped bending structure, wherein the plastic sheet is to be formed via the bending structures, arranging and fastening the heated plastic sheet on the first frame, moving the second frame into the open first frame into a forming position in such a way that the second frame takes the plastic sheet with it when moving in with its bending structure, wherein the plastic sheet is formed into a trough shape via both the first and the second bending structure, cooling the plastic sheet.

[0007] The method according to the invention no longer uses a flat mold, as is the case with deep drawing, but rather two nestable frames, each of which has frame-shaped bending structures for geometric deformation. This is based on the fact that a tub-shaped sanitary article is ultimately characterized by only a few bending areas near its upper edge and near the tub base, with these bending areas being approximately linear or very narrow linear sections. These edge and bottom bending areas are connected to one another via straight surface sections.

[0008] In the method according to the invention, the heated plastic sheet is clamped onto the first frame and fixed thereto. The first frame has a first bending structure. It is open so that the second frame can move into it from above. The second frame has a second bending structure, wherein this second bending structure, when the second frame is moved into the first frame, runs against the plastic sheet and, because it has been softened by the heating, takes it along and lowers it into the first frame. The plastic sheet is hereby reshaped via the first bending structure of the first frame, i.e. a corresponding circumferential edge bend is created in the upper edge region, by means of which the edge region is delimited from the tub region. The second frame-shaped bending structure defines and forms the transition from the tub walls to the tub floor, i.e. the circumferential bottom bend is defined and formed via it.During this movement into the final forming position, the plastic sheet only comes into contact with the first bending structure and the second bending structure, whereby the respective contact there is only approximately linear, since these bending structures only define the narrow, linear bending sections in which a transition from one adjacent surface to another adjacent surface occurs. There is no other surface contact during this forming process into the tub shape. This means that during this forming process only the smallest possible contact occurs between the two frames or the bending structures and the plastic surface, since the forming device is ultimately reduced to the characteristic lines, i.e. the two bending structures that are essential for forming and forming the bends.

[0009] These frame-like first and second bending structures can, as is usually the case, be rectangular or square, since bathtubs or shower trays are usually rectangular or square in shape, both at the edges and at the base. However, it is also conceivable for the bending structures to be round or oval, polygonal in shape, or, for example, in the case of corner tubs, to have two straight legs and one curved leg. This means that different bending structure geometries are conceivable, since even such tub shapes can be reduced to a few characteristic lines represented by the bending structures.

[0010] Since, according to the invention, there is only a very small, quasi-linear contact between the bending structures and the plastic plate, over which only the bends are formed, the soft plastic material can be stretched completely homogeneously in all intermediate regions, i.e., all surface areas (i.e., the side walls and the base), since the material can flow freely in these regions and can therefore change its thickness homogeneously. In these regions, there is no surface contact between the plastic material and any surface area of ​​the mold, since, as described, the contact area is reduced exclusively to the bending structures. The final thickness of the formed object is therefore extremely uniform in the respective surface areas, as well as in the bending areas.The surface quality of the inside, i.e. the visible side, is also excellent and does not require any further processing, since the surface areas are, as described, virtually freely stretched in space and are therefore not subject to any friction or similar that could lead to inhomogeneities.

[0011] Since, in the method according to the invention, the second frame is inserted into the first frame and the depth of the sanitary article is therefore also determined by the insertion depth, the use of the forming device according to the invention also readily permits a corresponding variation of the formed article. This is because, for example, with a constant basic geometry (e.g. rectangular shape), the depth of the shower tray, for example, can be easily changed by inserting the second frame slightly further into the first frame, for example from 3 cm to 5 cm or 7 cm and the like. This means that the method according to the invention is also significantly more flexible with regard to the use of the forming device, so that one and the same forming device can be used to produce a sanitary article with a slightly different geometry, in particular depth.

[0012] If a sufficiently thick plastic plate is used which is sufficiently stable even after forming, no additional reinforcing layer needs to be applied to the back of the formed component. However, if it is necessary for reasons of stability and rigidity, according to the invention a reinforcing layer can be applied, in particular sprayed, to the underside or back of the formed object after it has cooled. This can preferably be a fiber-reinforced plastic layer, e.g. a layer reinforced with glass fibers (GRP layer) or a layer reinforced with carbon fibers (CFRP layer). If necessary, an additional reinforcing element can be embedded in this reinforcing layer at one or more specific locations, e.g. beneath the base or along an edge. Such a reinforcing element can be plate-shaped, but also strip-shaped or designed as an angled strip-shaped profile.It can be made of wood or a fiber material, but plastic reinforcement parts are also conceivable.

[0013] In a further development of the method according to the invention, it is provided that a frame arrangement is used with a first frame, the first bent structure of which has an outer first structural section and a second structural section running parallel thereto and located within the first structural section, wherein the heated plastic plate is arranged on the first frame in such a way that its side edge is bent around the further outwardly located first structural section, forming an edge section of the sanitary article. The quasi two-part geometry of the first bent structure makes it possible to form a doubly bent edge region, as is common with bathtubs and shower trays. A beveled edge is formed over the outer first structural section, which regularly runs vertically downwards and has a height of approximately 1-10 cm.This is followed by a mostly horizontal edge section, which then transitions into the adjacent tub surface via a bend formed by the inner, second structural section. This means that a doubly curved edge structure can be formed by these two structural sections.

[0014] The plastic sheet can be positioned resting on the two structural sections, which run in a common plane. Both frame-shaped structural sections, with their supporting edges on which the plastic sheet rests, lie in a common plane. This means that the plastic sheet rests on both, not just on one, and is only guided against the other during forming. This inevitably results in the formation of a horizontally running upper edge, which is beveled on the outside and merges into the tub surface on the inside.

[0015] Alternatively, it is also conceivable for the plastic sheet to be arranged only on the outer first structural section and only when the second frame is retracted is it moved against the lower second structural section and formed over this. In this case, the heated plastic sheet, after being arranged on the first frame, only rests on the outer first frame-like structural section. Only when the second frame begins to retract, i.e. when the second bending structure moves against the plastic sheet and takes it into the first frame, does the plastic sheet come into contact with the inner first structural section and is then bent around it. This means that the resulting upper edge runs at a slight angle to the interior of the tub, depending on the height difference between the two structural cuts.This has the advantage, especially with shower trays, that water cannot collect on them, but rather that the water runs off the edge into the tray area.

[0016] As described, for forming, the second frame with its frame-shaped second bending structure is inserted into the first frame. The insertion depth necessarily defines the depth of the tub area. It is expedient for the second frame to be inserted into the first frame until it reaches a stop against which the second frame runs or against which the plastic sheet is moved during forming. This stop therefore limits the insertion depth, ensuring that the second frame always inserts the same depth during each manufacturing process and, consequently, that the formed objects are identical.

[0017] In this context, it is advantageous to use a frame arrangement in which the stop is height-adjustable. This makes it easy to produce different depths, for example of a shower tray, although the shower tray itself always has the same basic shape. By simply changing the height of the stop, the tray depth can be adjusted, so that different tray types for different markets or similar can be produced using the same forming device. In this context, it is even conceivable that, if the frame arrangement is rectangular, shower trays and bathtubs with the same rectangular basic shape can be produced using the same frame arrangement. This is because it is fundamentally conceivable to produce a lower shower tray and a deeper bathtub by using different insertion depths.If the first bending structure with its two structural sections is not arranged interchangeably on a frame, the different trays will have the same edge geometry. However, if the first bending structure can be replaced, this simple exchange also makes it possible to produce different tray types with different edge geometries despite using the same frame arrangement.

[0018] A tub-like sanitary article typically has a drain that allows the connection of a pipe. The drain is defined or formed by a corresponding drain geometry that is molded into the plastic material. In order to form such a drain geometry, the invention can further provide that, upon retraction of the second frame or after reaching the final forming position, a male mold element provided on the second frame locally reshapes the plastic sheet to form a drain geometry. The second frame is therefore provided with a corresponding mold element that locally reshapes the plastic sheet to form a specific local drain geometry. This then only needs to be opened by cutting it out.

[0019] It is expedient if the male-type mold element is brought into operative connection with a female-type mold element provided on the first frame in the final forming position. The male-type mold element thus interacts with a female-type mold element, with the section of the plastic sheet being received between the two mold elements and formed according to the geometry of the mold elements. Both mold elements are the only parts that define corresponding forming surfaces, since the flow geometry usually has a ring-shaped, slightly curved structure.

[0020] The die-like forming element is fixed in its height during the forming process, but can be adjusted vertically if necessary to adjust its height. During forming, the male-type forming element is preferably moved vertically only after the bending structure has reached its final forming position. This can be done, for example, via a hydraulic or pneumatic actuating cylinder or an electric motor. This allows the male-type forming element to move against the die-like forming element, driving the plate section with it, thus forming the discharge geometry.

[0021] It is particularly advantageous if a frame arrangement is used in which, if only the male mold element is provided, this male mold element is arranged on the first frame so that its position can be changed, or in which both the male mold element and the female mold element are arranged on the first and second frames so that their position can be changed. This embodiment of the invention therefore allows a change in the position of the mold element(s), which is equivalent to changing the position of the drain geometry on the sanitary article. By changing the position accordingly, it is possible to form the drain geometry, for example, in the middle or at a longitudinal end of a rectangular bathtub, or in a desired corner of a shower tray, and the like.It is only necessary to position one or both of the form elements accordingly in their longitudinal and transverse position on the respective frame.

[0022] In addition to the method itself, the invention further relates to a forming device for producing a tub-shaped sanitary article made of plastic and having a visible side and a bottom side, comprising a frame arrangement with a first frame with a first frame-shaped bending structure and a second frame with a second frame-shaped bending structure, wherein the second frame can be moved into the first frame while taking along a plastic plate fixed to the first frame and the plastic plate can be formed via the bending structures of both frames to form bends.

[0023] The forming device is therefore a pure frame structure, comprising only the two frames with their two frame-shaped bending structures. No forming surfaces or similar features are provided in the forming device according to the invention.

[0024] The first frame can have a first frame on which the first bending structure is arranged, and the second frame can have a second frame on which the second bending structure is arranged. Both frames therefore have corresponding frames that serve as supports for the respective bending structures. The bending structures can be arranged on the frame in a fixed manner or, preferably, detachably and thus interchangeably. This interchangeability allows a certain degree of flexibility and adaptability of the frame's bending structure, so that different edge geometries can be produced by simply replacing, for example, the first bending structure.

[0025] The first bending structure can be formed by frame-like, rectangular-cross-sectional flat struts, and the second bending structure by frame-like, round or oval struts. As described, the first bending structure serves to form the tub's edge, with somewhat sharper bends, i.e., bends with a smaller radius, usually being provided in this area. These are expediently formed by suitable flat struts, i.e., thinner, strip-like metal struts, which are appropriately rounded on the edges, thus creating the corresponding roundness of the bend, i.e., the radius.

[0026] In contrast, the second bending structure, which defines the bend on the visible side of the sanitary ware at the transition from the tub surface to the floor, is formed by struts with a round or oval cross-section, as the radius there is usually slightly larger than in the edge area. These round or oval struts are conveniently designed as tubes or rods.

[0027] The method according to the invention and the forming device according to the invention fundamentally allow the formation of significantly sharper bends, i.e., bends with a significantly smaller radius than is possible with deep drawing. With the second bending structure, inner radii of a minimum of 8 mm can be easily formed, whereby the resulting inner radius depends on the diameter or geometry of the struts of the second bending structure.

[0028] The struts of the respective bending structures each form a closed frame. They are preferably made of metal and are therefore firmly connected to each other, for example, by welding. However, plug-in connections, screw connections, or similar are also conceivable to maintain modularity.

[0029] To form a double-curved edge on the sanitary article, the first bending structure preferably has an outer first frame-like structural section and a second frame-like structural section running parallel thereto and located within the first structural section. Thus, two nested flat strut frames are provided, the struts of which ultimately run parallel to each other. The edge of the plastic plate is bent downward around the outer structural section, and the central plate surface is bent inward around the inner structural section to form the tub area.

[0030] The two structural sections can run in a common plane, which makes it possible to create a flat, horizontal edge on the sanitary ware, as the plastic sheet rests on both structural sections during forming. Alternatively, the outermost first structural section can be higher than the lower second structural section. When the second frame is retracted, the plastic sheet is moved toward the lower second structural section, so that the resulting edge slopes slightly toward the interior of the tub.

[0031] Furthermore, a fixing device for fastening the plastic plate to the first frame is expediently provided. After the plastic plate has been placed on the first frame or the fastening structure, it is appropriately fixed and clamped by this fixing device so that it cannot move when the second frame is retracted. The fixing device is preferably designed to clamp an edge portion of the plastic plate bent around the first bending structure, in particular the outer first structural portion. The plastic plate is thus fixed by simple clamping.

[0032] It is expedient here if the fixing device comprises clamping strips that can be placed laterally against the first bent structure or the first structural section and clamp the edge section against it. The edge section is already bent during this clamping process, so that the angled edge described above is formed in a simple and expedient manner. The clamping strips expediently extend over the entire length and width of the bent structure so that the edge can also be bent over the entire length and width of the plastic sheet. The clamping strips can either be pressed on manually and clamped using a suitable mechanism. However, it is also conceivable to press them on hydraulically or pneumatically.

[0033] In a further development of the invention, a stop can be provided on the first frame, against which the second frame or the plastic sheet can be moved during forming. This stop defines the insertion depth or the immersion depth of the second frame into the first frame, thus the tub depth.

[0034] The stop is preferably height-adjustable, allowing different depths of the molded object to be easily produced by varying the stop height. By changing the stop height, shallower or deeper trays can be formed.

[0035] For easy height adjustment, the first frame preferably has a height-adjustable frame section arranged on vertical supports, on which the stop is located. The frame thus comprises a corresponding frame with a vertically adjustable frame section, which can be adjusted to different heights. The stop is arranged on this frame section and can thus be easily positioned as desired.

[0036] The frame section is preferably frame-like, thus also having four struts in a rectangular frame shape. Two offset stop elements are provided on it, thus providing a corresponding stop at two positions. This is particularly useful when designing a correspondingly long bathtub.

[0037] To form a drain geometry required on the final sanitary article to enable water drainage and to arrange a drain line, a male mold element is expediently provided on the second frame for forming the plastic sheet to form a drain geometry. The plastic sheet is formed accordingly via this male mold element, which is designed such that it can form a funnel shape as a drain geometry in the plastic sheet. The forming element is preferably only moved against the plastic sheet when the second frame is in the final forming position.

[0038] It is advantageous here if a die-like forming element is provided on the first frame, which can be brought into operative connection with the male-type forming element in the final forming position. The two forming elements thus interact directly with one another, with the die-like forming element being fixed in position and the male-type forming element supporting it, with the plastic plate held between them. Naturally, the die-like forming element has a correspondingly complementary shape, which also allows the formation of the corresponding funnel shape. In this way, the two forming elements can be used to locally form the discharge geometry.

[0039] The male mold element is preferably movable via an adjusting means from a rest position, in which it is removed from the plastic sheet, into a forming position in which it forms the plastic sheet to create the drain geometry. As described, the male mold element is preferably only moved against the plastic sheet when the second frame has reached the final forming position. Only then is the forming element moved vertically against the plastic sheet, so that the latter is formed into the preferably provided female mold element. The movement of the male mold element is effected via a suitable adjusting means, such as an adjusting cylinder, which can be actuated hydraulically or pneumatically; an electric motor would also be conceivable. This type of forming also ensures that there is a gradient in the direction of the drain from every position of the tub bottom.This may not be possible with thermoforming if the shape has not been precisely designed in its geometry.

[0040] According to a particularly advantageous development of the invention, the male molded element or, if both are provided, both molded elements are arranged on the first and second frame so that their position can be changed. This configuration makes it possible to vary the location at which the drain geometry is formed. For example, in a bathtub, the drain geometry can be provided at the center of a longitudinal end or in the center of the floor. In a shower tray, depending on the tray geometry, the drain can be provided in a corner or, in the case of an elongated rectangular shower tray, also at a longitudinal end. The corresponding position of the drain can be easily adjusted by simply repositioning the molded element(s).

[0041] For easy repositioning, it is expedient for the matrix-like mold element to be arranged on a support displaceably arranged on the first frame, and for the male mold element to be arranged on a support displaceably arranged on the second frame. The supports are displaceable in one direction, for example, in the longitudinal direction in a rectangular frame arrangement.

[0042] To enable a change in the discharge position not only in one direction, but in two orthogonal directions, it is expedient for the two form elements to be arranged so that they can be moved on the respective support. By moving the form elements along the support, movement in the transverse direction is also possible, so that virtually any positioning of the form element(s) is possible via the two degrees of freedom of movement.

[0043] Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings. Fig. 1 is a schematic diagram of a forming device according to the invention of a first embodiment, wherein the second frame is moved into the final forming position in the first frame, Fig. 2 is a perspective view of the first frame, Fig. 3 is a perspective view of the second frame, Fig. 4 is a side view of the forming device from Fig. 1 , Fig. 5 an enlarged partial view of the forming device from Fig. 1 showing the two form elements forming the flow geometry, Fig. 6 a perspective view of the forming device from Fig. 1 with formed plastic plate, Fig. 7 a longitudinal sectional view of the arrangement Fig. 7 , Fig. 8 a view of the forming area in the transition from a side wall to the floor, Fig. 9 a view of the forming area of ​​the drain geometry, Fig. 10 a schematic diagram of a forming device according to the invention of a second embodiment for producing a shower tray with a second frame retracted into the first frame, Fig. 11 a sectional view through the arrangement of Fig. 10 , Fig. 12 a sectional view corresponding Fig. 11 with the formed plastic plate shown, Fig. 13 the arrangement of Fig. 12 with cooperating form elements, Fig. 14 a perspective view of a forming device according to the invention of a third embodiment for producing an elongated shower tray, and Fig. 15 a perspective view of the forming device from Fig. 14 to create a flatter shower tray.

[0044] Fig. 1 shows a forming device 1 according to the invention for producing a tub-shaped sanitary article made of plastic, having a visible side and a bottom. The forming device 1 shown is designed for producing a bathtub. The forming device 1 has a frame arrangement 2, which frame arrangement 2 has a first frame 3 and a second frame 4. The first frame 3 is an open frame, so that the somewhat smaller second frame 4 can be inserted vertically into the first frame 3 from above, as shown in Fig. 1 shown. On the first frame 3, a first frame-like bending structure 5 is provided, which is described below with reference to Fig. 2 will be explained in more detail. This bending structure 5 is arranged on a frame 6, on which a height-adjustable frame section 7 is also arranged, on which a stop comprising two stop elements 8 is provided, which serves as a stop for limiting the end-of-retraction position of the second frame 4. Furthermore, a die-like forming element 9 is fastened to a carrier 10 on the frame section 7, which carrier 10 can be moved along the frame section 7 and positioned as desired. The die-like forming element 9 is also displaceable along the carrier 10.

[0045] The second frame 4 also has a frame 11 on which a second frame-like bending structure 12 is provided, which subsequently also Fig. 3 will be described in detail. A male mold element 13 is arranged on the frame 11 via a carrier 14, wherein the carrier 14 is also displaceable along the frame 11. The male mold element 11 is vertically movable via an adjusting element 15, wherein the adjusting element 15 is arranged displaceably in a suitable manner along the carrier 14. Like the female mold element 9, the male mold element 13 can therefore also be displaced longitudinally and transversely. The two mold elements 9, 13 interact to form a discharge geometry, which will be described below.

[0046] Fig. 2 shows a detailed view of the first frame 3. Shown is the rectangular frame 6, on which the frame section 7 is arranged in a suitable height-adjustable manner, as indicated by arrow P1. Also shown are the two stop elements 8, which are arranged in the area of ​​the frame ends.

[0047] Also shown is the first bent structure 5. This first bent structure 5 serves to form an edge section of the sanitary article. It has a first outer frame-like structural section 16, which is formed by four narrow, strip-shaped flat struts 17 that are connected to form a frame or rectangular shape. Arranged inside the first structural section 16 is a second frame-like structural section 18, which also consists of four strip-shaped struts 19 that are also connected to form a rectangular shape, but have rounded corners. An edge geometry is produced via the two structural sections 16, 18, comprising an outer, short and vertically downwardly folded edge section, followed by a substantially horizontal edge section that then transitions into the tub area. The two structural sections 16, 18 can lie in the same plane with their preferably rounded upper edges.This results in the manufactured upper edge section running horizontally, since the plastic sheet to be formed rests on both upper sides or upper edges of the structural sections 16, 18 in the undeformed state. Alternatively, the inner structural section 18 can also be slightly deeper than the outer structural section 16, which results in the formed edge section running slightly obliquely to the interior of the tub, since the plastic sheet first runs against the inner second structural section 18 when the second frame is retracted, after which the plastic sheet is further formed to form the tub walls.

[0048] Also shown is the quasi-pot-like, matrix-like mold element 9, which has a frustoconical mold surface 20. As shown, it is displaceably arranged on the support 10, as shown by the arrow P2, wherein the support 10 can be displaced along the frame section 7, as shown by the arrow P3.

[0049] Fig. 3 shows a schematic diagram of the second frame 4. Shown is its framework 11, which is also rectangular in shape. It has an upper section 21, from which several struts 22 run vertically downwards. At the lower end of the struts 22, the second bending structure 12 is arranged, which is also formed from four struts 23 connected to form a rectangular shape, which merge into one another via corresponding bends 24 in the corner regions. While, as described, the structural sections 16, 18 of the first bending structure 5 are formed by flat, strip-shaped struts, the struts 23 of the second bending structure 12 are formed by struts that are preferably round in cross-section, possibly also oval, and can also be tubular.

[0050] Also shown are the male-shaped mold element 13, the adjusting means 15, and the support 14, which is arranged longitudinally displaceably on the upper section 21 (see arrow P4), whereas the adjusting means 15 together with the mold element 13 is movable along the support 14 as described (see arrow P5). The mold element 13 is designed in the manner of a truncated cone and has a corresponding conical surface 25, corresponding to the conical surface 20 of the mold element 9. They thus fit together in a form-compatible manner, allowing the discharge geometry to be formed.

[0051] As described, and as Fig. 1 shows, the first frame 3 is open at the top and is laterally limited only by the first bending structure 5. This allows the second frame 4 to be moved into the first frame 3 from above with the second bending structure leading and brought into a final forming position which is limited by the stop elements 8. A side view of the forming device 1 from Fig. 1 is in Fig. 4 shown, whereby here too the second frame 4 is in the final forming position.

[0052] Fig. 5 shows an enlarged partial view of the area of ​​the two mold elements 9 and 13. The male mold element 13 can be moved vertically via the adjusting element 15, as shown by the arrow P6, so that it can be moved into the female mold element 9.

[0053] Fig. 6 shows the forming device 1 according to the invention, with which a plastic sheet 26 was formed to form a sanitary article 27 in the shape of a bathtub. At the beginning of the process, the second frame 4 is positioned above the first frame 3 so that the flat plastic sheet 26 can be placed on the bent structure 5 of the first frame 3. It is assumed that the two structural sections 16, 18 lie in the same plane, which results in the plastic sheet 1 resting on both upper edges of the rectangular structural sections 16, 18. In a next step, an edge section 28 of the plastic sheet 26 is angled vertically downwards and fixed with a fixing device 29. The fixing device 29 has four elongated clamping strips 30, which can be actuated hydraulically or pneumatically, for example, and which clamp the angled edge section 28 against the outside of the first structural section 16.This is how the plastic plate 26, which as mentioned is still undeformed and therefore flat, is fixed.

[0054] The second frame 4 is then moved from above against the plastic plate 26, which causes the leading second bending structure 12 to run against the upper side 31 of the plastic plate 26. During further lowering, the plastic plate 26 is taken along and stretched bit by bit to form the trough structure, so that on the one hand the corresponding trough walls 32 are formed, but also the bottom 33. The lowering movement continues until the final forming position is reached, in which the formed plastic plate 26 is moved against the stop elements 8, wherein the stop elements 8, see Fig. 7 , preferably run exactly below the transverse struts 23 of the second bending structure 12. The plastic material is accommodated between the stop elements 8 and the struts 23. Instead of such stop elements 8, a stop can also be provided elsewhere, against which the second frame 4 runs, e.g., with its frame structure.

[0055] The sectional view according to Fig. 7 shows the corresponding shape very clearly. On the one hand, the clamping strips 30 are shown, which clamp the edge section 28 against the first structural section 16. Also shown is the horizontal edge section 34, which forms the upper tub edge. This edge section 34, which naturally also runs around all four sides, merges into the corresponding side walls 32. The angle at which the side walls 32 are positioned to the upper edge section 34 and to the floor 33 depends on the size and positioning of the second bending structure 12. Because, as Fig. 7 shows that the second bending structure 12 takes the plastic material downwards with it, whereby the corresponding bends in the transition from the tub walls 32 to the base 33 are defined and formed via the second bending structure 12, i.e. the struts 23 with a round cross-section, and thus also the bending radius. It is clear that, depending on where the struts 23 are positioned relative to the second structural section 18, around which the plastic material is bent in the transition from the upper edge section 34 to the tub walls 32, the angle of the tub walls 32 to the upper edge section 34 can be larger or smaller, as can the angle to the base 33. The closer a strut 23 is positioned to one of the struts 19, the steeper the tub wall 32, and vice versa.

[0056] Shown in the Figuren 6 and 7furthermore also the matrix-like first mold element 9 and the patrix-like second mold element 13, wherein, see the sectional view according to Fig. 7 , the male mold element 13 is inserted into the female mold element 9. It is evident that the formed plastic material forms a corresponding funnel- or conical discharge geometry 35, as already shown in Fig. 7 shown.

[0057] After reaching the final forming position and moving the forming element 13 into the forming element 9 to form the discharge geometry 35, the assembly remains in this position for a while until the heated plastic material has cooled. Subsequently, the second frame 4 is raised again and the forming element 13 is returned, so that the formed plastic article can be removed from the first frame 3 after releasing the fixing device 29.

[0058] Fig. 8 shows in the form of an enlarged partial view the area of ​​the transition of a tub wall 32 to the floor 33. The area of ​​the bend is defined as described via the second bending structure 12, i.e. via the struts 23 in the radius, whereby, as described, the angle that a tub wall 32 assumes to the floor 33 is also adjusted via this. The second bending structure 12 engages a visible side 36 of the plastic plate 26, i.e. the formed bend 37 is visible from the inside. This is different with the first bending structure 5, which, as Fig. 7 shows, engages the opposite underside 38 of the plastic plate, ie the linear contact areas there are not visible.

[0059] In any case, for forming, only approximately linear contact exists between the plastic plate 26 on the one hand and the bending structures 5 and 12 on the other, which is defined solely by the contact surface or the wrap angle of the respective bending structure with the plastic plate 26. All other surface areas of the plastic plate 26 do not come into contact with any part of the two frames 3, 4 during forming. Rather, all surface areas, i.e., the peripheral edge section 34 as well as the tub walls 32 and the base 33, are formed or stretched virtually freely in space.

[0060] Fig. 9 shows an enlarged partial view of the interaction of the matrix-like mold element 9 and the male mold element 13. The plastic plate 26, here already in the unformed state, is clearly accommodated between them, so that the corresponding funnel-shaped drain geometry 35 is formed. This can subsequently be opened simply by removing the bottom section of the drain geometry 35.

[0061] Fig. 10 shows a perspective view of another forming device 1 according to the invention, wherein the same reference numerals are used for the same components. The forming device 1 comprises a frame arrangement 2 with a first frame 3 and a second frame 4 which can be inserted into the open first frame 3 from above. As the sectional view according to Fig. 11 shows, the first frame 3 again has a first bending structure 5 with the two structural sections 16, 18, which serve to form the edge, wherein the fixing device 29 is also shown. Also shown is the matrix-like forming element 9, which is attached to the frame section 7 in the manner already described above for the first embodiment, and which is also longitudinally and transversely displaceable. The frame section 7 is furthermore vertically displaceable on the vertical frame 6 and is therefore height-adjustable. The stop elements 8 are also arranged on the frame section 7.

[0062] The second frame 4 also has a frame 11, with the upper section 21, on which corresponding vertically extending struts 22 are arranged, at the lower end of which the second bending structure 12, also in the form of a frame, is arranged. As the sectional view according to Fig. 11 shows, this is again formed by cross-sectionally round struts 23, while the structural sections 16,18 are formed by corresponding strip-shaped, narrow struts 17,19.

[0063] The second frame 4 also has the second male-like mold element 13, which can be moved vertically via the adjusting element 15 and brought into operative connection with the mold element 9. The adjusting element 15 is in turn arranged on the carrier 14 and is displaceable along it, just as the carrier 14 is displaceable along the section 21.

[0064] The depth of entry is clearly smaller than in the design shown in the previous figures, which are used to create a deep bathtub. A shower tray is significantly lower than a bathtub. Figuren 12 und 13 show sectional views according to the Fig. 11 , where the carrier plate 26 is shown in the formed position. Fig. 12 the plastic plate 26 fixed by the clamping device 29 after reaching the final forming position on the part of the second frame 4. The corresponding, double-curved or angled edge geometry is again visible, forming the upper edge section 34, as well as the corresponding tub walls 32 and the bottom 33. The two forming elements 9 and 13 do not yet interact, ie the drainage geometry is not yet formed. This shows, however, Fig. 13 in which the male mold element 13 is lowered so that the plastic plate 26 is deformed accordingly, forming the drain geometry 35.

[0065] The Figuren 10-13 clearly demonstrate that simply changing the height position of the stop elements 8 by vertically moving the frame section 7 along the frame 6 makes it possible to change the insertion depth and, consequently, also the depth of the manufactured shower tray. This is because the plastic plate 26 is clamped at the top or edge, so this position is fixed. However, by changing the height of the stop elements 8, the depth of the insertion movement is changed accordingly, and thus also the tray depth.

[0066] Fig. 14 shows a schematic diagram of another forming device 1, with the frame arrangement 2, as already shown in Fig. 1 A first frame 3 and a second frame 4 that can be retracted into it are provided. The structure is identical to the design according to Fig. 1 . Only the second frame 4 is slightly longer, ie the second bending structure 12 is slightly longer than in the embodiment according to Fig. 1 This results in the angle of the front and rear tub walls 32 being somewhat steeper. Likewise, the frame section 7 is positioned significantly higher, meaning that the stop elements 8 are significantly higher and, consequently, only a reduced insertion depth is provided. Fig. 14 The design shown is used to produce an elongated, rectangular shower tray.

[0067] Fig. 15 shows the Fig. 14 already known forming device 1, also in the final forming position, whereby the plastic plate is not shown here for reasons of clarity. Here, the frame section 7 with the stop elements 8 is positioned even higher, so that the insertion depth of the second frame 4 into the first frame 3 is smaller than in the embodiment according to Fig. 14 The shower tray that can be manufactured has an identical basic geometry, but is flatter than the shower tray that can be manufactured with the design according to 14.

[0068] As a comparison of the Figuren 1 and 14shows, the frame arrangements 2 provided there are almost identical. Only the second frame 4 is slightly longer. It is conceivable that a bathtub and a shower tray can be designed with the same dimensions, apart from the depth. Only the angles at which the tub walls run to the tub floor can vary, which depends on the length of the second frame 4. It is now conceivable that the second frame 4, as far as its frame is concerned, can be adjusted in length, thus being able to be made slightly shorter or longer. For example, the frame is telescopic in its longitudinal direction. The second bending structure 12 is detachable, meaning it can be easily replaced with another bending structure adapted to the selected length. This is because the bending structure 12 must not have any unevenness, as would be the case with a telescopic or plug-in design, but must be completely homogeneous in its external shape.In this way, a simple modification of the second frame 4 is possible, so that with one and the same first frame 3 both a bathtub and a shower tray could be produced.

[0069] The bending structures 5, 12 are preferably formed from corresponding metal struts which are surface-treated accordingly so that the surfaces are as smooth and homogeneous as possible, which applies in particular to the second bending structure 12 which forms a bend on the visible side.

[0070] Because contact is only made between the quasi-linear bending structures 5 and 12 and the plastic material, but not in the area of ​​the corresponding surfaces, homogeneous forming with a flawless surface or visible surface of the formed object is possible. In particular, the tub walls 32 and the base 33 exhibit a uniform thickness across the surface, as they are evenly stretched during forming, since there is no contact with any molded part that would impede the expansion.

[0071] After removing the formed object from the first frame 3, the underside, which is not visible, can be back-injected with a reinforcing material, for example, a plastic material reinforced with fibers such as glass fibers, to provide stiffening. However, machining of the visible surface is not required in any case, as it is not negatively affected by either the forming process or the application of the reinforcing material.

Claims

1. Method for producing a tub-shaped sanitary object made of plastic with a visible side and a bottom, comprising the following steps: - providing a plastic sheet (26) to be moulded to form the sanitary object, - providing a forming device (1) comprising a frame arrangement (2) having a first frame (3) with a first frame-shaped bending structure (5) and a second frame (4) with a second frame-shaped bending structure (12), wherein the plastic sheet (26) is to be formed by means of the bending structures (5, 12), - arranging and attaching the heated plastic sheet (26) to the first frame (3), - inserting the second frame (4) into the open first frame (3) into a forming end position in such a way that the second frame (4) takes along the plastic sheet (26) with its bending structure (12) when it is inserted, wherein the plastic sheet (26) is formed into a tub shape by means of both the first and the second bending structure (5, 12), - cooling the formed plastic sheet (26).

2. Method according to Claim 1, characterized in that a reinforcing layer is applied to the bottom after cooling.

3. Method according to Claim 1 or 2, characterized in that a frame arrangement (2) having a first frame (3) is used, the first bending structure (5) of which comprises an outer first structural section (16) and a second structural section (18) which extends parallel thereto and is lying inside the first structural section (16), wherein the heated plastic sheet (26) is arranged on the first frame (3) in such a way that it is bent with its side edge around the first structural section (16) which is lying further outside, forming an edge section (28) of the sanitary object.

4. Method according to Claim 3, characterized in that the plastic sheet (26) is arranged resting on the two structural sections (16, 18) which extend in a common plane, or in that the plastic sheet (26) is arranged resting only on the first structural section (16) which is lying further outside and is only moved against the second structural section (18) which is lying lower and is formed over this when the second frame (4) is inserted.

5. Method according to one of the preceding claims, characterized in that the second frame (4) is inserted into the first frame (3) until a stop is reached against which the second frame (4) runs or against which the plastic sheet (26) is moved during forming, wherein a frame arrangement (2) is preferably used in which the stop is height-adjustable.

6. Method according to one of the preceding claims, characterized in that, when the second frame (4) is inserted or after reaching the forming end position, a patrix-shaped forming element (13) which is provided on the second frame (4) locally forms the plastic sheet (26), while forming a drain geometry (35), wherein the patrix-shaped forming element (13) is preferably brought into operative connection with a matrix-shaped forming element (9) which is provided on the first frame (3) in the forming end position.

7. Method according to Claim 6, characterized in that a frame arrangement (2) is used in which the patrix-shaped forming element (13) or both forming elements (9, 13) are arranged on the first and on the second frame (3, 4) in their position which can be changed.

8. Method according to one of the preceding claims, characterized in that a frame arrangement (2) is used in which the second frame (4) can be adjusted relative to the first frame (3) in at least one direction in order to change the inserted position.

9. Forming device for producing a tub-shaped sanitary object made of plastic with a visible side and a bottom, comprising a frame arrangement (2) having a first frame (3) with a first frame-shaped bending structure (5) and a second frame (4) with a second frame-shaped bending structure (12), wherein the second frame (4) can be inserted into the first frame (3) while taking with it a plastic sheet (3) which is fixed to the first frame (3) and the plastic sheet (26) can be formed by means of the bending structures (5, 12) of both frames (3, 4) while forming bends.

10. Forming device according to Claim 9, characterized in that the first frame comprises a first framework structure (6), on which the first bending structure (5) is arranged, and the second frame (4) comprises a second framework structure (11), on which the second bending structure (12) is arranged.

11. Forming device according to Claim 9 or 10, characterized in that the first bending structure (5) is formed by means of flat struts (17, 19) which have a rectangular cross-section and are connected in a frame-shaped manner and the second bending structure (12) is formed by means of round or oval struts (23) which are connected in a frame-shaped manner.

12. Forming device according to one of Claims 9 to 11, characterized in that the first bending structure (5) comprises an outer first frame-shaped structural section (16) and a second frame-shaped structural section (18) which extends parallel thereto and is lying inside the first structural section (16).

13. Forming device according to Claim 12, characterized in that the two structural sections (16, 18) extend in a common plane, or in that the first structural section (16) which is lying further outside is higher than the second structural section (18) which is lying inside.

14. Forming device according to one of Claims 9 to 13, characterized in that a fixing device (29) is provided for attaching the plastic sheet (26) to the first frame (3).

15. Forming device according to Claim 14, characterized in that the fixing device (29) is designed to clamp an edge section (28) of the plastic sheet (26) which is bent around the first bending structure (5), in particular the outer first structural section (16), wherein the fixing device (29) preferably comprises clamping strips (30) which can be placed laterally against the first bending structure (5) or the first structural section (16) and clamp the edge section (28) thereto.

16. Forming device according to one of Claims 9 to 15, characterized in that a stop, which is preferably height-adjustable, is provided on the first frame (3), against which the second frame (4) or against which the plastic sheet (26) can be moved during forming.

17. Forming device according to Claim 16, characterized in that the first framework structure (6) comprises a framework section (7) which is arranged in a height-adjustable manner on vertical carriers and on which the stop is arranged, wherein the framework section (7) is preferably frame-shaped and is provided with two stop elements (8) which are positioned offset with respect to one another.

18. Forming device according to one of Claims 9 to 17, characterized in that a patrix-shaped forming element (13) is provided on the second frame (4) for forming the plastic sheet (26) while forming a drain geometry (35), wherein a matrix-shaped forming element (9) is preferably provided on the first frame (3), which can be brought into operative connection with the patrix-shaped forming element (13) in the forming end position.

19. Forming device according to Claim 18, characterized in that the patrix-shaped forming element (13) is movable by means of an adjusting means (15) from a rest position, in which it is at a distance from the plastic sheet (26), into a forming position, in which it forms the plastic sheet (26) while forming the drain geometry (35).

20. Forming device according to either of Claims 18 and 19, characterized in that the patrix-shaped forming element (13) or both forming elements (9, 13) are arranged on the first and on the second frame (3, 4) in their position which can be changed.

21. Forming device according to Claim 20, characterized in that the matrix-shaped forming element (9) is arranged on a carrier (10) that is displaceably arranged on the first framework structure (6) and the patrix-shaped forming element (13) is arranged on a carrier (14) that is displaceably arranged on the second framework structure (11), wherein both forming elements (9, 13) are preferably displaceably arranged on the carrier (10, 14).