DE202007009025U1 - Model arrangement, model and model material for thermoforming a plastic body - Google Patents

Abstract

arrangement (A) for thermoforming a sanitary object (S) from a plastic semi-finished product by means of negative pressure, wherein the arrangement a model (1) and a plastic semi-finished product (7) and a holding device that has the over the actual shaping area of the model protruding edge of the plastic semi-finished product (7) characterized in that the model (1) consists of a rigid foam block exists in one the desired one Contour of the sanitary object Milled in the imaging contour is, so that the hard foam block a shaping recess (4) has, whose walls in hard foam block the plastic semi-finished product the desired shape mediate, with the rigid foam block provided with suction lines is over which seals the shaping, also in the area of its main opening to the outside Deepening (4) can be subjected to negative pressure.

Description

The The invention relates to an arrangement for thermoforming a sanitary object made of plastic according to the preamble of claim 1, as well as a sanitary object made of plastic with a corresponding substructure according to the preamble of claim 5 and the use of a suitable material therefor Purposes according to claim 10.

It is known, by so-called. Thermoforming sanitary objects from Sanitäracrylplatten to manufacture, namely in particular shower trays and bathtubs. Occasionally will open this way also toilet bowls or bidets made of plastic, the two last-mentioned types of sanitary objects usually consist of several parts accomplished and locked or welded together to the necessary undercuts to be able to realize.

To the The purposes of such thermoforming usually become steel molds or "modeling", ie steel blocks, in the shape of the relevant sanitary object is milled and: the sanitary acrylic panel give shape when under the influence of for the purpose of thermoforming applied vacuum is drawn into the mold and at the Walls inserted.

The Production of steel Modeling is expensive because of the high material and labor costs. In the serial production of sanitary objects, this still plays No matter, because with the model thousands of the same sanitary objects produced, to which the high tooling costs are assigned can. For the production of individual pieces come steely But modeling is not an option.

To excessive tooling costs To avoid, the individual production of large, demanding three-dimensional takes place curved, shell-like plastic bodies mostly by so-called lamination. This is usually from a easy to model material produced a positive shape, d. H. a complementary curved Moldings, in particular the bowl-like Picture shows that the sanitary object should have later. Be on this molding with a suitable plastic (usually polyester) soaked fiber or fabric mats hung up, which subsequently Harden. The shell-like plastic body thus produced is then of the positive mold decreased. As far as high demands on the surface of the Plastic body i. d. R. a surface finishing (grinding, To fill and / or painting or coating), which requires effort and costs caused. Although you can in this way unique pieces produced, but only at high cost. The latter in particular also because the lamination process is difficult to automate is.

Finally is in vehicle manufacturing in the production of larger body parts made of plastic (eg spoilers) has already been observed that where small series are required, do not use steel molds, but of wood or plastic parts composite forms. Their shaping surfaces get their finish, however, by the fact that the shaping surfaces after a the main contour producing roughing troweled and be sanded. Such trowelling and grinding will cause it some effort and limits the circle of materials used as material for the model be considered. Useful here are only those materials whose surface Spachtelbar is and of the spatula even under load not flakes off.

In contrast, is It is the object of the invention to provide a possibility for the cost-effective small series or individual production of sanitary objects made of plastic and in particular bathtubs and shower trays.

These Task is inventively characterized solved, that the model is made of a hard foam block, in the the desired contour of the sanitary object milled in is, so that the hard foam block has a shaping recess, their walls in this hard foam block the plastic semi-finished product the desired shape convey. As far as between the shaping surface of the Hard foam block and the semi-finished product to be formed is still an intermediate layer is inserted, this is when milling the shaping cavity considered.

Such a model can be produced very rationally. Rigid foams are generally easy and quick to machine, in particular, this applies to the (common) plastic hard foams. The milled into the hard foam surfaces but also have a good dimensional stability. The production of such a model can be largely automated. It only has to be constructed by means of a suitable CAD system, the desired shape of the sanitary object, the design freedom are virtually unlimited due to the invention. The data set thus generated can then be passed on to an automatic milling machine, which essentially independently mills out the required contour from a rigid foam block. Despite their size, the relatively lightweight blocks of hard foam are easy to handle. Since rigid foam has only a low density because of its comparatively high air entrapment, large-volume rigid foam blocks, such as those used to mill a model for one, also cause Bathtub are needed, only low material costs.

Preferably is in the context of the invention, a separate compensating film or Balancing mat used between the forming surface of the Model and the semi-finished plastic to be molded by it and which is so yielding that formally common surface defects of shaping surface only in the compensation position, at least not through you through to the visible side of the finished plastic body. On this way lets Even without special processing of the shaping surface of the Model ensure that the shaping surface of the Model to find surface roughness or surface defects are not at the sanitary object depict. This is very important for sanitary objects. Because of sanitary objects will be a high gloss surface requires that even minor surface defects mercilessly "unmasked." Under such a Compensation film or leveling mat is doing a web-like Understood material, which, at least at the beginning of thermoforming, not connected to the shaping surface of the model. Instead, this compensating foil or leveling mat is usually on the shaping surface the model facing side of the later sanitary object forming plastic plate be laminated.

A Substantial improvement is that the model after the Completion of the actual thermoforming will not turn into waste, but (straight because it is made of hard foam) finds further use. So can the model will find further use as transport packaging. To This is the purpose of the model and the sanitary objects made in it taken as a whole from the thermoforming machine, with an outer packaging provided and then delivered. That's the way it is actual sanitary object, as such, yes only from a comparatively thin plastic shell which is correspondingly susceptible to breakage and scratching transport damage protected and at the same time well stackable. Another advantage is that in the Production does not occur due to disused models waste.

Ideally However, the model has not served its purpose even after being transported. Rather, it is still used, namely as a substructure, with in the building is installed. Such a substructure holds the actual shower tray or bathtub safely in their mounting positions. He isolated at the same time, prevented So for example, that the bath water is prematurely cold. Especially It is advantageous that the plastic insert (on the basis of the fact that he was made in the model and therefore one Image of the forming cavity of the model) is almost ideal Way clings to the model and therefore optimally supported. this makes possible it to make the actual plastic insert thinner, or at the same thickness the plastic insert to achieve a much higher stability. This not only results in a higher resistance to breakage, but also above all, even without additional effort a subjective feeling of higher value. moreover let yourself This saves a separate holder, as they otherwise would be required to the water-holding or water-bearing plastic insert in Installation and use position to keep.

advantageously, At this stage, the model also serves as a support for the sanitary covering, ie for the tiles, the marble slabs or other wall cladding. This saves Walling the fitter, the bathtub or the shower basin first to have to, around the bathtub or the shower basin with the tiling etc. to dress up.

Ideally The block is made from a layered stack. there will first in every single layer milled in the required contour. Then the layers are stacked and stacked to form the layer stack bonded. In this way, the tool cost can be pronounced be kept low because of the milling of individual, not too thick layers not necessarily a 5-axis milling machine need becomes. Also, the foams are cheaper in plate material.

A preferred development provides that the compensation position together is thermoformed with the plastic semi-finished product. In this way it comes virtually wrinkle-free on the shaping surface of the Model to the plant - what can not be easily achieved, for example tries to insert the compensation layer by hand into the mold and at all points to the forming surface.

Ideally is the leveling before starting the thermoforming with the Model facing surface connected the semifinished product. This is best done by the Compensation under heat on the said surface semi-finished product is laminated, or more or less welded to it, or at least flat attached to her. In this way it prevents the Compensation situation too early in the shaping cavity of the model sags and turns it into an undesirable Air inclusion between the plastic semi-finished product and the compensation layer comes.

The compensation films or mats used are extremely inexpensive, since they are standard products. To a leveling layer in the form of a film or mat can be kept easily stored, namely, for example, in roll form. It can also be easily applied, regardless of whether it is connected to the plastic semi-finished product before use or whether it is placed on the model before the plastic semi-finished product is placed.

One very reasonably priced and yet very effective material for the compensating film or mat is soft foam. Preferably, a warm-stretchable, this means under the influence of heat Thermoformable soft foam used. Preferably, the Soft foam closed pores, as closed-cell foam no relevant impressions leaves on the plastic semi-finished product. For the purposes of the invention Ideally, a flexible polypropylene foam is used.

Further Effects and advantages of the invention will become apparent from the following Description of the embodiments.

The 1 shows the equipment of the model with a still undeformed plate made of sanitary acrylic and the underlying mat made of soft foam

The 2 shows a cross section through the model at the moment of forming the actual bath forming plastic body.

The 3 shows model used in a kind of molding box.

The 4 shows a side view of what is in 3 is shown.

The 5 shows a model constructed of plates or individual layers.

Primary is coming the inventive method for the production of individual sanitary objects. Therefore This application is also illustrative of the invention embodiments selected.

In a first embodiment, the method according to the invention proceeds as follows:
First, taking into account the customer's wishes, the individual shape of the desired sanitary object is determined and converted into a data set for computer-aided manufacturing with the aid of a CAD system. The created CAD model can additionally be used for process simulations or other CAE applications, for example for pre-simulation of the thermoforming process in order to reduce the number of preliminary tests required.
Then the production of the model takes place. Based on 1 and 2 can quite nicely see how such a model looks in the finished state - the 2 shows a finished model for thermoforming a bathtub from which the finished bathtub is being pulled straight out, which is why it is shown raised a few inches from the model.

To make the model 1 a self-contained block of rigid foam, preferably a plastic foam in the form of a polyurethane or unsaturated polyester foam is used. By means of a computer-controlled milling machine, a cavity is milled out of the closed block. The boundary walls of the cavity thus produced form the outer contour of the later plastic insert, which later forms the actual bathtub. In the case of a bathtub, it is usually not important that the outer contour of the plastic insert is accurate to the millimeter. If, however, with this method, not a bathtub or sanitary objects, but other plastic parts are to be produced, such as exactly dimensionally stable body parts, a machining allowance must be provided during milling under certain circumstances, to take into account the fact that the thermoformed semi-finished product not directly with the shaping surface of the model comes into contact, but under inter mediate position of the leveling layer. For more complex parts, the dimensional accuracy of which is measured within very narrow limits, it may be necessary to determine by experimentation how far the leveling layer will yield at certain points in order to be able to provide appropriate additions in the production of the model. Conveniently, such machining allowance is of course also provided routinely in the manufacture of a bathtub or sanitary object. This can be done easily with today's CAD systems.

Of Furthermore, the model is processed in the area of the top so that there later the characteristic edge, as you know it from a bathtub, is shown.

The next step will be the plastic semi-finished product 7 and the compensation situation 8th prepared. As a plastic semi-finished product 7 usually a flat, up to 10 mm thick, usually at least 3 mm thick plate of sanitary acrylic (PMMA) or other suitable material, such as ABS used. As a compensatory situation 8th serves a flat, up to 10 mm, preferably 4 to 6 mm thick mat or sheet of closed-cell soft foam, preferably polypropylene soft foam. The ideal thickness of the mat or film depends on how strong the surface defects are, which must be absorbed and how yielding the material forming the mat or film is. The ideal thickness can therefore not but can be determined by a person skilled in the art by a few experiments and / or computer-based process simulations. Experiments or simulations are u. For example, in more complex 3-D shapes, it may be necessary anyway to determine if the desired shape can be readily made by thermoforming.

This preparation runs off so that initially the semi-finished product 7 is further heated until it reaches a temperature just below its softening point. This is at sanitary acrylic at about 220 degrees. The heating is expediently not convective, but by means of a suitable radiation source, preferably by means of an infrared radiator.

Now The soft foam mat can thermally with the sanitary acrylic panel be connected, in particular laminates on these become. In this way it is ensured that the soft foam mat not early sags and thereby unwanted Air accumulations between the sanitary acrylic panel and the soft foam mat result.

This is followed by the semi-finished plastic product 7 and the soft foam mat 8th continue to heat until they reach their forming temperature. It is important that a temperature gradient is maintained, namely in such a way that it is ensured that on the one hand the plastic semi-finished product 7 already has a sufficient temperature for forming, but on the other hand, the soft foam mat 8th not yet so soft that it collapses and thus can no longer fulfill its task. In order to achieve this, it is therefore preferred during the heating to ensure that the mean end temperature of the soft foam mat 8th about 25 to 60 degrees below the mean final temperature of the semifinished product 7 lies.

Once the plastic semi-finished product 7 and the soft foam mat 8th , which are clamped in a frame of the thermoforming machines, have reached their forming temperature, they are lowered to the model.

Once the plastic semi-finished product 7 has reached its final temperature is via the vacuum distribution channels 2 and the vacuum mouth channels 3 Vacuum to the shaping cavity 4 created. This vacuum pulls the softened by the heat plastic semi-finished product 7 and with her the soft foam mat 8th in the shaping cavity 4 into it, until the plastic semi-finished product 7 with interposition of the soft foam mat 8th completely abuts the walls of the shaping cavity.

Here unfolds now the soft foam mat its effect. It is sufficient thick and yielding or compressible, around imperfections that on the walls of the shaping cavity are to be "absorbed", that is, to be leveled that these flaws at best still slightly on the outside the bathtub (ie the plastic body), but not down to the visible side of the bathtub.

In general, it can be said that the key point is that the balancing layer ( 8th ) at least at the temperature at which the thermoforming process takes place, is so soft and / or so easily plastically deformable or "displaceable" that the compensating layer fills in surface depressions or absorbs local surface elevations without correspondingly large stress peaks on the surface As a rule of thumb, it can be said that the leveling layer at thermoforming temperature should be much softer or significantly easier plastically deformable than the plastic of the semifinished product to be shaped.

Occasionally the soft foam mat also has another function - namely the u. Not necessarily temperatures up to 230 degrees endurance hard foam protect the model from that the heat of the semi-finished plastic all too fast on the hard foam the model transferred becomes.

Remarkable at this point is that the Model 1 is set for the purpose of thermoforming as a whole in a molding box, which may be, for example, a construction made of wood. This molding box is provided on its underside with seals and is there against a corresponding, provided with suction pipes surface. In this way, on the bottom of the model 1 a vacuum can be applied through the vacuum manifolds 2 and the vacuum mouth channels 3 in the model continues into the shaping cavity of the model. Also on the top is the molding box with gaskets 12 Mistake. Against these seals 12 is the frame, which is the plastic semi-finished product 7 and the soft foam mat 8th holds. In this way, the shaping cavity 4 the model 1 also sealed from above.

To End of the actual thermoforming process goes through the Process a cooling phase. The finished bath S (if it does not remain in the model, immediately) from the model.

Then become the function openings (eg drain and overflow) cut into the plastic body forming the bathtub. Furthermore Any handles are mounted.

if necessary The plastic body forming the bathtub S is now reinforced by his original the model facing back at least locally a strengthening layer is applied (eg by lamination of fiber mats or Fiber spraying).

It should be noted at this point that it may be useful to work with "supporting air", ie the shaping cavity 4 the model 1 At least in the final phase of heating to put under slight overpressure, so as to push the soft foam mat from the inside against the plastic semi-finished product and thus counteract an uncontrolled sagging.

The just described method can also be carried out modified. Namely such that the compensating layer or compensating film or mat is thermoformed separately from the plastic semi-finished product. in the The framework of this is therefore first just put the leveling on the model, brought to temperature and thermally reformed by applying vacuum to the model, that they are the shaping surface the model is lining. This development of the invention has the Advantage that the compensation layer also consist of a material can, its for the thermoforming to be reached final temperature clearly from the corresponding Deviates final temperature of the thermally reshaped plastic semi-finished product, without any special consideration has to be taken - different as in the common thermoforming of the semifinished product together with the Compensation layer.

Preferably, the leveling layer is (usually after being thermoformed) provided with a perforation, ie one or more holes, which allow, during the subsequent thermoforming of the semifinished product through the leveling position, a vacuum to the shaping cavity 4 to apply.

apart of those differences, that runs Just described process variant as well as the first Alternative, so that what is said here applies equally here.

Another modification of the above-described manufacturing method is that the leveling is not connected before the start of thermoforming, or only at the edge or partially with the model facing surface of the semifinished product and that the leveling position until the beginning of the actual thermoforming with supporting air against uner wished Sagging is secured in the shaping cavity of the model, ie by the fact that the shaping cavity 4 is placed under slight pressure, whereby the leveling position is pressed against the semi-finished product.

Also in this way If necessary, the production process can accelerate. So it is possible that Plastic semi-finished products and the leveling layer (which, for example, also here as Soft foam mat or running as a foil) possibly only on their outer edges together to connect (eg with possibly double-sided adhesive tape or adhesive paper) or the leveling only at points to the plastic semi-finished product attach, which is often faster than a real lamination.

apart of those differences, that runs just described, third method variant exactly as from the first alternative, so that what is said here in the same Way applies.

As indicated above, it is imperative in any of the described production routes, the plastic body forming the actual bathtub after thermoforming and cooling from the model 1 to mold. In particular, in individual pieces, it is instead extremely useful to the plastic body forming the actual bathtub in the model 1 to leave. The model is in this case only locally cut out to z. B. to cut the drain and the overflow in the plastic body to install the drain and possibly the handles. The model then serves as a transport packaging that protects the plastic body forming the actual bathtub and makes it easy to stack and handle.

It is best not to remove the model even when the delivery arrives at its destination. Because the model 1 can be used in many cases as a base for the bathtub. It then makes it superfluous to first have to build a special substructure or walls, in which then the actual bath forming plastic body is installed. Instead, the model is installed together with the actual bath forming plastic body in place. It must be placed "in the water", ie leveled so that the water runs out of the bath completely after the bath, for this the model is either aligned in a damp mortar bed or by chocks or the like or (in luxury versions or self-installation versions by do-it-yourselfers) are placed on an underframe provided with height-adjustable screw feet.

All in the end, then the visuals of the model with the help one of the usual plastic-bound Tile adhesive covered with tiles, stoneware, marble or the like.

So is then from the process of the invention for the production of a plastic molding an inventive method for the production and installation of a sanitary object.

The 3 shows another embodiment of the method according to the invention. In contrast to the embodiment described above here is the model 1 not from a one-piece block. Rather, it is made up of individual layers or plates that pass over the holes 5 be accurately centered relative to each other and glued together as a rule. Such a model has the advantage that much less stringent requirements are placed on the milling tool required for its production, which reduces the tooling expenditure. Because to mill the individual layers, you do not necessarily need a 5-axis milling machine. Rather, a simple milling machine is sufficient for this purpose.

The inventive method can also be then apply it beneficially, if not the entire model out of one Hard foam exists, but only parts thereof. In such a Case, a model of steel is used, which is essentially the Shape of the sanitary object pretends. The shape of the steel model is, however, then by appropriate Inserts, which are usually made of the above-mentioned rigid foam exist, modified. Just to give an example, the customer wants a bathtub, which essentially corresponds to a standard bath. Indeed he claims that there is an armrest on both sides of the bathtub shall be. To realize this armrest, will be appropriate Hard foam inserts inserted or glued into the steel model. Then the method according to the invention according to the above Description in the thus modified steel model carried out to to make the individualized bathtub.

Important is that to the embodiments in the form of a bathtub given explanations and comments mutatis mutandis to all other types of plastic bodies are applicable.

Of further it should be noted that, for example, as an equivalent Replacement for the hard foam blocks according to the invention actually also wooden blocks (preferably laminated or glued wood and pressboard products) in particular made of light wood can be used - especially balsa wood has Properties that are largely comparable to those of hard foam are. In practice, however, the essential here in particular higher costs for such Materials in the way, at least as long as not economic considerations determine the choice of material. something similar applies to the lightweight material "gas concrete" or "fine-pored aerated concrete", which is based on the principle However, it can be regarded as hard foam in the literal sense of the invention.

1

Model

2

Vacuum distribution channel

3

Vacuum outlet channel

4

form obtainable cavity

5

centering

6

Not busy

7

Workpiece

8th

leveling layer

9

Not busy

10

shaping surface

11

molding box

12

poetry

Claims (14)

Arrangement (A) for thermoforming a sanitary object (S) from a semi-finished plastic product by means of negative pressure, the arrangement being a model ( 1 ) and a plastic semi-finished product ( 7 ) and a holding device, which comprises the edge of the plastic semifinished product which projects beyond the actual shaping area of the model ( 7 ), characterized in that the model ( 1 ) consists of a rigid foam block, in a the desired contour of the sanitary object-imaging contour is milled, so that the hard foam block a shaping recess ( 4 ), whose walls in the rigid foam block impart the desired shape to the plastic semifinished product, wherein the rigid foam block is provided with suction lines, via which the shaping, also in the region of its main opening to the outside sealed recess ( 4 ) can be subjected to negative pressure. Arrangement according to claim 1, characterized in that the arrangement has a separate compensating film or compensating layer ( 8th ) formed between the shaping surface ( 10 ) the model ( 1 ) and the semi-finished plastic product to be molded by it ( 7 ) and which is so yielding that formally common surface defects of the shaping surface ( 10 ) only at the level of compensation ( 8th ), but not through them to the visible side of the finished plastic body. Arrangement according to one of the preceding claims, characterized in that the arrangement comprises a molding box ( 11 ), which the model ( 1 ) during the actual thermoforming process, wherein the molding box ( 11 ) the model ( 1 ) seals on its underside, so that at the bottom of the model ( 1 ) Vacuum can be applied, extending through the suction lines in the model propagated through to the shaping well. Arrangement according to claim 3, characterized in that the molding box ( 11 ) the model ( 1 ) seals at its top. sanitary object with substructure consisting of a water-retaining or water-draining plastic insert and one made of hard foam body Substructure for support the plastic insert, characterized in that in the substructure milled in a depression whose image is the plastic insert, and that the hard foam body has channels, temporarily removing air from said well have served. sanitary object with substructure according to claim 5, characterized in that between the plastic body and the depression of the substructure, which he clings to, one Foam or mat made of soft foam is located. sanitary object according to claim 5 or 6, characterized in that the substructure consists of several layers, each through rigid foam panels formed, placed one on top of the other, preferably glued together. sanitary object with substructure according to claim 5 to 7, characterized in that the plastic insert made of sanitary acrylic (PMMA). sanitary object Substructure according to one of Claims 5 to 8, characterized that cut out of the substructure after deep drawing certain areas or -broken to make room for a waste and / or overflow set to accomplish. sanitary object Substructure according to one of Claims 5 to 9, characterized that the substructure is a sanitary covering in the form of tiles, marble slabs or the like, which preferably firmly connected to it. Use of a hard foam block for the production a model for thermoforming a bathtub or a shower tray from a plastic semi-finished product, preferably from a plastic plate, by milling the desired contour of the sanitary object, so that the rigid foam block has a shaping depression, their walls in hard foam block of the plastic plate during deep drawing the desired shape convey. Use of a rigid foam block according to claim 11, characterized in that the rigid foam block after deep drawing used as a transport packaging, which is the bath or shower tray surrounds as far as possible and protects against damage. Use of a rigid foam block according to claim 11 or 12, characterized in that the foam block after deep drawing as in the building to be installed carrier is used, the bathtub or shower tray in its intended use position holds. Use of the rigid foam block according to claim 13, characterized in that the rigid foam block as a support for a sanitary pad in the form of tiles, marble slabs or the like is used.