The object of this invention is an apparatus and method for manufacture of plastic object. The mentioned plastic object is made of plastic profile.

With the help of the invention one can produce curved so called cupola like and straight plastic objects.

The use of the invention is a vessel like for instance a container. When manufacturing a cupola like vessel in accordance with the invention, a container head is made. A use can also be a well or a certain place in a pump station, a cover or covers or bottom is made in accordance with the invention about cupola like pieces. Cupola like and straight objects can be used also as parts of other constructions to be welded. One method of the known technology to produce a cupola like object has been presented in the patent publication number ZA200402063 B. In this solution, between cupola like male and female mold pieces, a large plastic tube wall part of spiral joint technique is pressed. About the tube, a suitable piece for the head unfinished work is cut and it is heated up to a suitable working temperature and pressed between the mold parts so that it gets the shape of cupola. After this, the mold and the cupola like piece in it are cooled. After cooling, the object retains the shape that it got under the pressure and its ring is machined so that it is suitable for its use, for example a container head. Another way to produce cupola like plastic objects is to turn round tubes horizontally to desired shape plates.

The greatest disadvantage of the before presented known technology is the difficulty of bending large and thick wall tube parts when pressing. One of its important disad- vantages and an aspect that raises the production costs is the need of press of heavy work machines.

The greatest disadvantage of the later presented known technology is the difficulty to bend the large tubes. A common disadvantage of both of the before mentioned known technologies is the need of a lot of space, Containers and other mentioned vessels where the cupola like parts are used are large and thus these before mentioned parts are large especially in the direction of their diameter

Another apparatus according to known technology to manufacture cupola like objects has been described in the publication 6102241 A. The apparatus contains a central support and a support organ. The support has been adapted to keep the plastic profile that is fed around it in favorable position and the plastic profile is fed from an extruder lengthwise and with a rise that corresponds the width of the plastic profile upon the support. The plastic profile is hot and flexible and fastens (gets melted) by its side to the previous layer. This apparatus does not have a welding head and in this method the plastic profile is not welded to the construction that is being formed. In the center of the apparatus we are talking about there is not spiral surface and the plastic profile is not fed against such. The apparatus of the publication differs from the invention essentially also in that its center is not put to move following a certain route forced by the support organ. The publication DE 19539745 A1 presents one known apparatus and method to manufacture a plastic object. The plastic profile is wound layer per layer upon the support and the layers are welded together. The support is cylinder also in this solution, it does not contain spiral surface that the plastic profile is fed against and it is not put to move to follow a certain route ahead forced by a support organ.

The intention of this invention is to get such an apparatus and method to manufacture that avoids the disadvantages of the known technology. It is characteristic for the apparatus according to the invention what is presented in the characterizing parts of the claims 1 and 9.

The greatest advantage of the invention in comparison to the known technology is that there is no need to press the large parts to the shape of cupola or to bend difficult-to- bend comparatively large tubes Large mold or bending machines are not needed. The reduced need of space is a notable advantage when using the invention. The invention is described in more detail in the following drawings, where fig. 1 presents the first phase of one manufacture process according to the invention, fig. 2 presents a later phase of the before mentioned process, figs. 3 a- 3 g present different plas- tic profiles that are used in the manufacture process of the cupola like plastic object, figs 4a- 4d present arrangements when using a certain open profile, fig. 5 is another solution according to the invention.

Following, the different phases of a favorable realization of a method according to the invention are described referring to the before mentioned figures.

The beginriing phase of a solution of the method according to the invention is presented in fig. 1 when manufacturing a cupola like plastic object with the apparatus 100 (marking in fig. 2) according to the invention. In the middle of the setting there is the center 1 of the mentioned apparatus the outer ring of which consists of the first surface 1.1 that is a spiral surface and the second surface 1.2 that is the surface that joins together the spiral surface ends. It has been wound against the first surface 1.1 of the center by turning the center to the direction A around its center axis 1.3 plastic profile 2 the head 2.1 of which has been adapted against the second surface 1.2 of the ring or near it. The head 2.1 of this plastic profile 2 is supported to its place during the first round against the second surface 1.2 of the center or near it. After this, as the center 1 continues round movement around its center axis 1.3 to the direction A and when the second round of the plastic profile settles against the first round outside it the plastic profile 2 to be fed to the shape of spiral around the center is to be supported to stay to its place lengthwise. The support is made using a support 3 that is permanently in its place so that the plastic profile 2 is able to move into the direction B supported by the mentioned support and settle to the spiral structure 10 round the previous (outer most) round. As the spiral structure 10 demands continuously more space when the process advances between the center axis 1.3 and inner surface 3.1 of the support 3 as the space Dw grows, the center 1 moves to the direction C, that is farther from the inner surface 3.1 of the support . At the same time as the spiral structure 10 builds up the weld head 4 in the advancement direction of the process after the support 3 performs the welding together of the two side by side settled plastic profile rounds and thus there is a welding joint 5 in the spiral structure. The welding is performed in this ap- plication of the invention with double head welding head 4 by extruding additional material to the welding joint 5.

In fig 2 there is a cross section cut of the position X - X of fig 1 where the advance- ment from the situation of fig 1 is about three spiral rounds. In the spiral structure 10 wall center point there has been drawn a ring arch 6 that follows the shape of the wall. The geometric center axis of the ring arch 6 is same as the geometric center axis 6.1 of the spiral structure 10 and it is essentially of Hie same direction as the inner surface 3.1 of the support 3. The center 1 has been connected and supported with the support organ 7 with this mentioned geometric axis concentrically to its place adapted axis 8. In the center 1 there is a concentric hole 1.4 with the center axis 1.3 and there has been adapted the axis 7.1 of the first end 7a of the support 7 either with sliding adaptation or rolling bearings so that the center is able to rotate in the axis 7.1. The hole 7.2 at the other end 7b of the support organ 7 has been adapted to rotate the axis 8 to the direc- tion C while the center 1 moves in the direction C, which is along the ring arch 6. The center 1 and the support organ 7 move at the levels that are perpendicular to the geometric center axis 6.1 or the ring arch 6. When the ring arc 6 in this example is in the center of the spiral structure 10 wall, the space Dw is understood in this example to be the arched distance between the inner surface 3.1 of the support 6 in the ring arch and the center axis 1.3. The spiral structure 10 getting shape is thus a ball dome and the wall center ball surface radius R is also ring arch 6 radius.

When the spiral structure 10 is in the process sufficiently large to get a plastic object the feeding of the plastic profile 2 is ended, it is cut, the center 1 is removed by cutting from the spiral structure and the spiral structure is removed from the manufacture apparatus after sufficient cooling. Then the plastic object is machined from the sides and the center to get the desired plastic object.

The plastic profile 2 is in the previous example a round tube with the outside diameter of dl. It can also be a square tube, rectangular tube or a tube combination of these forming the plastic profile 2. One shape of tube like profile 2 that is suitable to be used in the invention is so called wrinkly tube that bends because of it corrugation better than a straight tube around the center 1. The plastic profile can as well be different from previous for example an open profile, like U profile. The asymmetric surface plastic profile can be fed to the spiral construction in alternative positions.

In figures 3a- 3f, there have been presented cross section cuts of some of the previous- ly mentioned plastic profiles 2 and in the figure 3g there is a principle picture of the wrinkly tube seen from above. The width d1- d7 of the plastic profile 2 to be fed is its outside dimension from the inside surface 3.1 of the support 3 into the direction of the center 1. The center 1 is always adapted to be suitable of its dimensions for the bending capabilities of the plastic profile 2 and the dimensions of the plastic profile 2, like outside dimensions and the wall thicknesses are selected for the plastic object suitable among other things the desired strength capabilities. The center 1 moves during the manufacture process of the plastic object into the direction C the measure d1- d7 of the plastic profile 2 during one fed spiral round. When the feeding speed of the plastic profile 2 in the direction B is set constant so the angle speed of the center 1 into the direction C diminishes all the time as the spiral ring grows .The change speed of the angle speed is dependent among other things on the size of the plastic object in the manufacture, the width d1- d7 of the plastic profile 2 in use and its feeding speed. It is in the previous example the diameter dl of the plastic profile that is also its width.

When the plastic profile 2 is an open profile, like U profile, it can also be made of a wide dome like plastic object during the manufacture process. In figures 4a- 4d this kind of case has been presented. In figure 4a there is a setting where a U shape plastic profile 2 being fed to the spiral construction 10 is manufactured just before feeding. In accordance with the picture 4b cuts 11.1 are made to a plastic plate 11 to the corners of the profile to come and the edge parts 11.2 of the plastic plate are turned 90° of the center part 11.3. During the bending it is possible to use a counterpart 12 to facilitate the bending. In this example, the modification of the plastic plate 11 is made as it advances in the area L of the picture 4a to the direction B. After this, the edges 2.1, the collars, can be supported to stand perpendicular in relation to the center part 2.2, like shown in picture 4c. In figure 4d there is a situation where the plastic profile 2 has been welded to the spiral structure 10 in its corners. The figures 4c and 4d are cross section cuts of the picture 4a in positions Y- Y and Z-Z.

It can be seen in the pictures 4a- 4d that the counterpart 12 has as its continuation the first welding support 13 and inside the outermost plastic profile layer, between its center and collars of the forming spiral structure 10 there is another welding support 14 so that the center of the plastic profile 2 to be fed to the spiral construction 10 is supported using the mentioned welding supports to a favorable welding position and location between them. The first and the second welding support 13, 14 have both extended over the location where the welding takes place and so they support the construction when the weld joint cools. The part after the welding location of the second welding support 14 has been adapted to be flexible by making cuts 14.1 to its inside and thus it is capable to bend along the changing radius Dr of the spiral. In this example, the plastic profile 2 is in the position according to the picture 3f and so its center in the center side hinders and outermost collars stretch to eliminate the length difference between the parts. The second welding support 14 is able to support also the out ring of the spiral construction 10 into a favorable position, in this example especially its outward directing collars. The counterpart 12 and the first welding support 13 of this example have been realized as an apparatus where there is a chain 16 going round the chain wheels 15 and side plates 17 installed to the sides. When at least one chain wheel is pulling to the direction presented in the picture 4a and the friction surface of the chain has been pressed to the inside surface of the center part 2.2 of the plastic profile so that there is no glid- ing between the mentioned surfaces the chain has been adapted to feed plastic profile 2 to the spiral structure 10 and at the same time to rotate the spiral construction around the center axis 1.3 of the center. The side plates 17 support the side parts 2.1 of the plastic profile to keep in a favorable position. Outside support of the mentioned collars can thus be used to help them.

In this example, the second welding support 14 has been formed to fill for certain length essentially the space between the side parts 2.1 and the center part 2.2 of the plastic profile that has been welded to the spiral construction. It has been adapted to begin lengthwise before the welding location and to continue over the welding loca- tion. Its outer surfaces are glide surfaces and inside surfaces of the middle parts and sides glide against its surfaces. The outside surface of the middle part 2.2 of the plastic profile 2 to be fed can as well be adapted to glide against the out surface of the second welding support.

The rise h (figures 2 and 4d) of the first surface 1.1 of the center 1, in other words the spiral surface, is in previous examples favorably the same as the width dl, d6 of the plastic profile. The first and/or the second surface of the center can also be made so that they are not solid surfaces. As an example, a net surface can be mentioned.

The counterpart 12 and the first welding support 13 that have been presented schematically in figures 4a- 4d can also be made as separate organs.

The first and the second welding supports 13, 14 can also be made in some other way than what has been presented before. It is characteristic for them that they support the plastic profile into a favorable shape and position for the time of welding it to its location for a sufficient long time for welding and after it for the cooling of the weld joint.

One application of the invention is to use the first and/or the second welding support 13, 14 to feed the plastic profile 2 to the spiral construction 10 and the other to rotate the spiral construction 10 around the center axis 1.3 of the center.

The mentioned welding supports can thus be realized as glide or roll operated. In roll operated welding support, rolls, chains, belt etc. can be used to direct, support and feed the plastic profile. In glide operated welding supports, heatproof gliding surfaces are used. As an example of this, a lamella deck can be mentioned where the layers nearest the welding location are of sufficiently heatproof material, like for example PTFE. The flexibility of the welding supports 13, 14 after the welding location can be realized in many different ways. In addition to what has been stated previously can also an articulation technique be mentioned. When the plastic profile 2 is a U profile its parts can be pre-stretched. The need for pre-stretching diminishes when the changing radius Dr of the spiral grows during the process advances. The feeding of the plastic profile 2 to the spiral construction 10 can also be realized using a separate apparatus according to some way of the known technology. Likewise, rotating the spiral construction around the center axis 1.3 of the center can be realized using any known technology way. These ways can be selected case by case. The method according to the invention can also be realized so that the feeding speed of the plastic profile into the direction B is changed during the process.

The support 3 that supports the plastic profile 2 to stay in for itself favorable position when being fed to the spiral construction can be slide or roll operated. It can be an organ or an apparatus with a slide surface that consists of one or more rolls, track, chain conveyor, belt etc.

The inside surface 3.1 of the support is in reference to the previous either a physic surface, like for example essentially straight level surface or a circuitous surface or a ge- ometric surface that is tangent to the round roll organs of the before mentioned apparatuses in their center 1 side.

The support 3 can also have other functions than supporting the plastic profile 2 to a certain position. It is possible to join to it the feeding of the plastic profile or a sepa- rate feeding apparatus to keep the feeding speed and the welding speed constant.

A separate support 3 is not necessarily always needed from the apparatus 100 according to the invention. When using the before described first welding support 13 it can be used to take care of the task that has been described for the support 3. In the figure 4a there has been described one this kind apparatus.

When using a solid (hollow or not-hollow) plastic profile 2 together with the first welding support 13 the mentioned welding support is adapted against the outside surface of the plastic profile. The same applies when an open plastic profile center is in some other position than what has been described before. The mentioned outside surface is understood to be the surface that is farthest from the center 1 or a part of curved surface in this position or a corner that connects the surfaces. The welding head 4 can also be realized if desired to be suitable for one sided welding. The welding head can also have a pre-heater of the plastic profile, a feeding organ or apparatus of the plastic profile, an apparatus to finalize the joint and/or the cooling apparatus. It is also possible to add material in the welding head to the surface layer of the spiral construction 10 and to finalize the surface of the spiral construction.

The support organ 7 can be realized in many different ways. From the point of view of the invention it is central for it that:

1) it supports the center 1 into such a position that the plastic profile 2 can be fed around the center in the way of the invention,

2) it allows the rotation of the center 1 in relation to its geometric center axis 1.3 and supports it during this movement,

3) it allows the advancement of the center 1 along a certain arc or direct route into the direction C supporting the center to keep it in this mentioned track so that its center axis 1.3 is all the time essentially perpendicular in relation to the arc or direct line.

The axis 8 can be equipped with bearings either to the manufacture apparatus 100 frame or to the hole 7.2 of the second head 7b of the support organ 7 or even to both of these. The second head 7b of the support organ can be fixed to the axis 8 also by some other known way than with the help of the hole in it. From the point of view of the function of the axis 8, it is central that it conducts and supports the center supporting support organ 7 to turn with a certain angle speed (changing or constant) in relation to geometric center axis 6.1 of the ring 6. In figure 5 there has been described a solution that is different from the previous one to manufacture a plastic object using the apparatus 100 and the method according to the invention. In this solution the center 1 has been set to rotate with its geometric center axis 1.3 concentrically the support organ T that is an axis in this example and this mentioned support organ has been fixed to a stand 21 or to a corresponding thing. The stand 21 has been adapted to move in the base 22 to the direction C when feeding the plastic profile 2 to the spiral construction 10.

The base 22 can be for example rails and the fixing of the stand or a corresponding organ can be realized so that it glides on the mentioned base into the desired direction C. The stand 21 can be supported to the base so that its movement sideways is not possible.

When the stand 21 has been adapted to move directly the spiral object 10 becomes a direct plate when following the line 6' .

The stand can be set to move in this solution of the invention also to follow a circuitous base 22', like for instance along an arc base so that the plastic object 10 becomes correspondingly circuitous, in this example an arc. The circuitous base 22' that has been presented in figure 5 manufactures circuitous 6", in this example round arc shape that is dome shape spiral object 10.

The spiral construction 10 can be supported during the manufacture process with for example rolls, slide supports etc. Depending on the size of the object to be manufac- tured, its size and strength capabilities the number and quality of the supports can be decided case by case.

The plastic object that is manufactured means an object the raw material of which is mainly plastic.

It should be noted that even though this description sticks to only one type for invention favorable solution example this does not by any way want to limit the usage of the invention for only this type of example, instead, many variations are possible according to the invention idea defined in the claims.