DE19822301C1 - Method and device for applying a plastic layer on the inner surfaces of hollow bodies - Google Patents

Abstract

The invention relates to a method and a device for applying a plastic layer consisting of at least two components to the inner surface of a hollow body. A coating device which has been introduced into the hollow body travels through the same, providing the hollow body with a coating. After, the components of the plastic have been mixed inside the coating device, the axial speed at which they are conveyed propels them out of a mixer outlet opening (8) inside the centrifuge chamber (3) onto a cone (9) facing said mixer outlet opening (8). The components accelerate considerably, with the result that the plastic is more rapidly distributed on an impact plate (5) and is spun onto the inner surface of the hollow body in a sheet, via a discharge opening (7).

Description

The invention relates to a method and an apparatus for application a plastic layer on the inner surface of hollow bodies, the front Protects wear and corrosion, especially in supply and Waste disposal lines where the flow behavior of the Medium can be improved.

Methods are known in which using a rotating spray nozzle a plastic is applied to the inner wall of pipes. This Methods have the disadvantage that they are used to tear the beam required pressure loss the possible insertion length into the coating tube significantly limits (DE-OS 27 15 849).

The use of a spin plate, due to its rotational movement brings the flow rate to a high coating energy is cheaper, especially if radially arranged baffles on the centrifuge plate are attached or radial arms are used (DE-OS 28 08 903, 28 26 628, 35 18 584 A1, DE 297 16 585 U1).

Furthermore, methods are known which work with centrifugal plates which the plastic mixture opened against the direction of pull Centrifugal disc is applied. This will result in the mixture accelerated in a spiral on the spin plate, which makes the relatively long Stay - when using very highly reactive PUR - for premature Curing of the mixture can result. Furthermore, can Set segregation effects.

The present invention has for its object the above To improve methods and devices.

The production of thick layers from 1 to <20 mm in one pass requires highly reactive plastics e.g. B. polyurethanes or polyureas (PUR) the thixotropic behavior and pot life of 0.5 to 10 seconds exhibit. When processing such plastics, there is a risk that  that prematurely hardening constituents clog the device can. It is therefore necessary to stay PUR after the Keep mixing in the coating device as short as possible.

According to the invention the object is solved by claims 1 and 9. Advantageous developments of the invention are in the respective associated Claims included.

According to a preferred feature of the invention, at least 2 Components of composite plastic on the inner surfaces a hollow body, preferably a tube, applied by one in the Coating device introduced into the hollow body passes through, the components of the plastic according to their Mixing within the coating device by the axial Conveying speed via a mixer outlet opening within a Spin chamber onto one of the mixer outlet openings opposite cone hit and increased acceleration experienced, causing an accelerated distribution of the plastic on a Baffle plate takes place and the plastic on a discharge opening on the The inner surface of the hollow body is flung onto the surface.

According to a further feature of the invention, the Coating device pulled through the hollow body.

The plastic can also according to another feature of the invention accelerated via baffles arranged inside the centrifugal chamber and be thrown out.

According to a further feature of the invention, the from The discharge opening of the mixer is additionally discharged with a plastic granular and / or fibrous filler are mixed, these Fillers are fed via a feed and distribution device, which in is arranged in the immediate vicinity of the coating device.  

According to a preferred feature of the invention, the insertion length of the Coating can be increased by inside the hose package additional feed pumps can be integrated.

The present invention further includes an apparatus for Apply one of at least two components yourself composite plastic layer on the inner surfaces of Hollow bodies, the at least one mixing device and at least one related spin plate includes. Here is the Mixing device within a rotating hollow shaft of the rotating Centrifugal disc arranged, one on the hollow shaft Centrifugal plate forming centrifugal chamber connects, which consists of a Baffle plate and a support plate is formed, with baffle plate and Carrier disc connected to each other by a profiled discharge opening and the baffle plate is directed towards the mixer outlet opening Has cone.

According to a preferred feature of the invention Coating device executed twice, the spin plate are set at an angle to each other and the outlet openings are preferably are designed as interlocking radial arms.

According to a further feature of the invention, in addition to the Coating device on the transport device a feed and Distributing device for granular and / or fibrous fillers arranged.

The invention will be described in more detail below using an exemplary embodiment are explained. In the drawings, the

Fig. 1 shows a schematic representation of the coating apparatus in cross-section,

Fig. 2 shows a schematic representation of the overall system.

The reference numerals are on the list of reference numerals used explained.  

The centrifugal technology consists of a PUR system (material container, pumps, heating, control, etc.), supply hose package, transport device and coating device, as shown in FIG. 2, as well as a compressed air compressor and e-generator. These are described in more detail below.

The PUR plastics in question have viscosities up to 20 ° C to 15,000 mPas and at 70 ° C z. B. 80 mPas. PUR are thixotropic Fluids. In order to be able to process these viscosities, at least in Storage tank on the isocyanate side requires an agitator, which the Keeps material flowable.

The isocyanate component is hydrophilic, which means that at least this storage container is sealed airtight and with nitrogen must be applied. An alternative to nitrogen is dried air or air that is dried by filters that z. B. contain silica gel. The storage containers have a capacity of approx. 100 l. The content of this before However, the container is for larger insertion lengths, d. H. at a Pipe diameter of 500 mm and 5 mm layer thickness after approx. 24 m used up. Therefore, a refill system is required that ensures ongoing supply.

The heater can e.g. B. consist of a downdraft heater that Brings material to processing temperature. The temperature will then held by the separately heated material hoses up to the mixer.

Due to the required funding lengths and the expected high Pressure drops of 300 to 500 bar are necessary. So be so high pressure systems needed. These high pressures are associated with Piston pumps are achieved using either compressed air or electrical power operate. The metering can be done via balance beam systems - which are set manually - or special volume flow devices respectively.

To use such volume flow control systems, a PLC Control makes sense. Via a PLC (programmable logic controller) can control the entire system such as delivery pressure, metering, Temperature control etc. can be programmed or regulated.  

The supply hose package consists at least of the material hoses and the compressed air line for the centrifugal disc drive. The Material hoses consist of high pressure hoses, such as z. B. are common in hydraulics. The heating is done by creating a def. Current through the flow resistance of the metal reinforcement Generates heat.

Depending on the monitoring and control needs of Coating device, however, signal lines are to be provided that the Data transmission from e.g. B. volume flow measuring device, Temperature monitoring and speed measurement serve.

Depending on the task, a pull rope can be placed in the supply hose package be integrated, see transport device.

The coating in a single pass appears cheap. The times for the introduction of the coating device or the number of Required rope entries in the pipe can be as low as possible be kept possible. The insertion length and the feed should be as large as possible. Due to the high performance of the Systems also increases the effect of any errors that may occur. The appearance of Errors can e.g. B. cause the complete PUR system premature curing becomes unusable.

The prerequisite for high performance is the behavior of the PUR the application: It should be in the intended layer thickness, the 10 mm is a uniform layer thickness and a smooth surface exhibit. However, this is only possible if the material after Hitting the wall loses its flow property. For this the pot life of the material and / or the thixotropy can be correspondingly short or set high. In order to be able to maintain these properties, the mixing ratio as well as the temperature must be precise be respected.

The coating device consists of a transport device the mixer, spin plate, motor and monitoring devices as well any additional devices are installed.

The residence time of the reactive mixture should be kept so short that there can be no hardening inside the head. Mixing must be very thorough.  

The application energy of the material should be as high as possible because it is assumed that the mixture up to a high kinetic energy penetrates into the "last roughness". Furthermore, the necessary high Ge speed gradient supports which thixotropic fluid is only fluid makes. The impact energy is necessary to ensure the necessary adhesion of the material to ensure the wall and continue to adapt different diameters (especially when passing through arches) support.

No pressure loss due to redirecting the flow to the wall. Self-cleaning of the mixer and the disc, therefore fewer errors Due date. Self-cleaning is urgently required, especially with large ones Insertion length stops should be unavoidable, furthermore this will partial renovation or repairs.

To keep the mixing and dwell time as short as possible, counter-current injection mixers can be used. Of the Material is likely to be emitted as a jet, but it scatters. Around To be able to absorb this scatter, the invention Flow directed towards the "opposite" disc and through there the distribution cone immediately directed to the circumference. The advantage of this The arrangement consists in completely collecting the mixture flow, especially at high discharge speeds from the mixer. The mixture flow is centered on the in this arrangement Spin plate led, resulting in an even distribution of the Mixture leads over the circumference of the disc with the shortest possible residence time. The acceleration of the mixture can be increased significantly by the use of baffles. These cause the mixture to stop immediately is "channeled" after hitting the disc and thus immediately Angular speed of the disc reached. This will also Application energy of the mixture increased significantly because of friction losses by slippage are hereby excluded constructively.

The "channeling" of the mixture should have another advantage bring: By using further baffles that the way of the Extending the mixture significantly is a further mixing of the Mixtures possible. The one caused by the rotational acceleration Centrifugal force "pushes" the mixture towards the circumference. Static  Mixers work with the same effect, but this is the necessary one Conveying energy generated by the delivery pressure.

In this case, the baffles could also be get supported. However, this principle can only be achieved through Channeling the mixture on the centrifugal disc works, one Removing the baffles could have the effect of a centrifuge: The mixture segregates again, because the components do have approximately the same densities, but a very different flow behavior. The high speed of the centrifugal disc should in any case be sufficient to the disc - even if there is further mixing takes place - to clean automatically.

The use of mixing on the slinger could be the use rel. simply designed mixers enable those with less agitated Share get along.

"Conventional" counterflow injection mixers spray the components, to achieve better wetting. This creates at the expense of possible hose length a pressure loss that should be avoided. A flushing device is also necessary.

Using a needle valve would offer several advantages: The valves to shut off the component supply separately replaced by the needle valve, which both components simultaneously cordoned off. The cleaning is also done by the needle valve, which a possible plug of material is pressed out. The use of the simultaneous shutdown, however, requires absolutely the same material pressures of the components so that no component is fed into the other can reach. The use of the needle valve thus increases the System susceptibility to errors and should therefore be thoroughly reconsidered or tried out.

A counterflow injection mixer can also be replaced by a dynamic mixer. However, this should be used as a "friction mixer" be carried out as these are self-cleaning. The components are driven by a high-speed screw (12 000 to 20 000 U / min), which is conical and wall-accessible, through the high shear stress between worm and cylinder wall mixed. However, an additional motor is required for this mixer.  

An alternative to both of the aforementioned mixers is the static one Mixer, which is then equipped with a compressed air purge have to be.

When selecting the mixers, only mixers should be taken into account which can be cleaned with compressed air. Compressed air is in contrast to Solvents for driving the centrifugal disc have already been added, whereas the use of solvents requires additional effort, which should be avoided for cost, environmental and space reasons. Because the centric application of the mixture to the spin plate is advantageous, the attachment of the spin plate is in any case a hollow shaft is required.

The shape of the centrifugal disc should ensure rapid, even discharge promote the mixture as well as an application as flat as possible guarantee. The areal application is necessary to make uneven To be able to compensate feed. The flat discharge can be achieved are by a sawtooth profile on the circumference. The host of the Mixing takes place over the entire width of the profile. Another The method is to carry out the channeling such that the individual channels e.g. B. shaped tubular and staggered.

The size of the centrifugal disc should be as large as possible to increase the application energy to a maximum. Here is make sure that different pipe diameters with little Devices can be coated as possible.

It seems sensible to increase the application energy by high speeds increase, avoiding too fine atomization. Cheap "drops" appear here that carry little air with them (and so the Reduce the void content of the layer), but due to its size more "bind" kinetic energy as smallest "droplets".

The transport device serves to receive the coating device.

The adaptation to different pipe diameters can be done by Use of e.g. B. pneumatic actuators. This can the passage of z. B. Reductions are made. The reduction will recognized by a carried TV camera or by the  sudden stoppage of the coating (the material supply immediately (automatically) must be stopped).

Longer insertion distances and 3-D geometries can be used Require self-propelled. While the feed of the Device over the supply hose package, possibly via a pull rope and Can occur, the occurring friction of the pull rope and the mass increasing in proportion to the length of insertion Feed hose package when passing arches and longer Lines no longer suffice. The drive can be electrical Energy or compressed air.

A self-propelled rapid traverse has the main advantage that there is no rope connection must be made before coating begins. The Coating can be retracted automatically, for which only one opening of the pipe is required.

The combination of scissors and self-propelled should continue to "climb" enable in lines. With climbing is the passage of 3-D Geometries in z. B. Industrial plants also possible uphill. The remotely adjustable scissors in conjunction with friction-increasing wheels enable a "clamping" in the pipe, which is the prerequisite for that Represents climbing.

Because the core of the coating consists of a centrifugal disc, mixer and motor exists, this is rel. small. It could therefore also be based on an existing one Renovation robots are put on.

The more functions spin technology can perform, the more too Monitoring and control parameters are required. It is therefore necessary to create a place where all data converge to to be controlled and controlled in this way. A control center is available for this. A very powerful system has a lot of sources of error, that need to be recognized and eliminated quickly.

The control should take place via a PLC.

The control center should be housed in a vehicle.

Instead of the coating device, a spray gun can be used connect, which enables the manual coating of surfaces. Is the Transport device z. B. unable to drive through arches  these are coated by hand. There are also some plants e.g. B. wastewater treatment plants not only from pipes, but from basins or containers, that cannot be coated with the coating device. To this All cross-sections that can be walked on can be coated in this way.

The increase in insertion length can be achieved if Booster pumps are used. These booster pumps come with the supply hose package into the pipe. This way theoretically realize several kilometers of insertion length. For this it appears however, it is necessary to use a source of energy other than compressed air because the pressure drops over such a long distance should become uncontrollable. Electricity seems cheaper.

The coating device shown in Fig. 1 can be equipped with additional components with which fillers can be introduced into the spun material. These fillers can e.g. B. consist of fibers or granular parts. The introduction of fibers enables the production of a composite material, which - particularly when spinning hard PUR or synthetic resins - can achieve higher static strengths.

The device for this consists of a fiber feed, which consists of a Reel exists and is outside the pipe. The fibers are through a flexible hose that is integrated into the supply hose package is involved. There is then a shredder on the coating device attached, which cuts the fibers so that they into the spin stream are transported and in this way enclosed by the mixture.

If the fibers are long enough, it can be assumed that a holes or cracks can also be covered in this way. The fibers In contrast to the pure material, they do not penetrate the hole, but stick to the edges, because they are already with the impact wetted the mixture and longer than crack width. The fibers therefore represent subsequent fibers and material an obstacle that cannot be penetrated and are covered by other fibers.

The use of granular fillers is used in the industry not only use the solid plastic for cost reasons  have to. Furthermore, fillers - like fibers - are also suitable for Change in mechanical properties. The necessary for this However, the system requires pneumatic conveying, in which the solids e.g. B. first in a container attached to the coating device attached, conveyed and then the material flow by screw or the like fed. This happens exactly like the one described Introducing fibers so that the pumps and other components through the No wear and tear due to increased abrasion are.

The coating of outlets when using a Centrifugal disc the disadvantage that exits only in the direction of centrifugation be coated. This is circumvented when two disks are used become. The direction of spin of a plate is only capable of one To coat one side of an outlet. Two plates become different Direction of rotation used, both sides can be coated so that there is a transition from coating to pipe.

Reference list

1

Spin plate

2nd

Mixing device

3rd

Spin chamber

4th

Hollow shaft

5

Baffle plate

6

Carrier disc

7

Discharge opening

8th

Mixer outlet opening

9

cone

10th

storage

11

/

12th

Storage container for the components of the coating material

13

pump

14

Hose package reel

15

pipe to be coated

16

Traction rope

17th

Hose package

18th

Coating device

19th

coated inner pipe surface

20th

Traction device

Claims (15)

1. A method for applying a plastic layer composed of at least two components to the inner surfaces of a hollow body, a coating device introduced into the hollow body passing through the hollow body and providing it with a coating, characterized in that the components of the plastic after they have been mixed within the coating device ( 18 ) hit by the axial conveying speed via a mixer outlet opening ( 8 ) within a centrifugal chamber ( 3 ) on a cone ( 9 ) opposite the mixer outlet opening ( 8 ) and experience increased acceleration, whereby an accelerated distribution of the plastic on a baffle plate ( 5 ) takes place and the plastic is flung onto a surface of the hollow body via a discharge opening ( 7 ). 2. The method according to claim 1, characterized in that coating the inside surface of the hollow body in a thick layer of 1 to 20 mm is applied. 3. The method according to any one of the above claims, characterized in that coating with plastics made from highly reactive Components are formed that have a thixotropic behavior and have pot lives of 0.5 to 10 s. 4. The method according to any one of the above claims, characterized in that the coating device is pulled through the hollow body.   5. The method according to any one of the above claims, characterized in that the plastic is accelerated and ejected via baffles arranged within the centrifugal chamber ( 3 ). 6. The method according to any one of the above claims, characterized in that the plastic discharged from the discharge opening ( 7 ) is additionally mixed with a granular and / or fibrous filler. 7. The method according to claim 6, characterized in that the granular and / or fibrous filler via a feed and Distribution device is supplied, which is in the immediate vicinity of the Coating device is arranged. 8. The method according to any one of the above claims, characterized in that the insertion length of the coating is increased by within the Hose package additional feed pumps can be integrated. 9. Apparatus for applying a plastic layer composed of at least two components to the inner surfaces of hollow bodies, which comprises at least one mixing device and at least one centrifugal disc connected thereto, characterized in that the mixing device ( 2 ) within a rotating hollow shaft ( 4 ) of the rotating spreader disk (1) is arranged to give a the whirler plate (1) forming the spinning chamber (3) adjoining the hollow shaft (4), which is formed from a baffle plate (5) and a carrier plate (6), said baffle plate (5) and the carrier disk ( 6 ) are connected to one another by a profiled discharge opening ( 7 ) and the baffle disk ( 5 ) has a cone ( 9 ) directed towards the mixer outlet opening ( 8 ). 10. The device according to claim 9, characterized in that the mixing device ( 2 ) is self-cleaning and / or has a flushing device. 11. Device according to one of the above claims, characterized in that baffles are arranged within the centrifugal chamber ( 3 ). 12. Device according to one of the above claims, characterized in that the centrifugal chamber ( 3 ) is double, the centrifugal plates are set at an angle to each other and the outlet openings are preferably designed as interlocking radial arms. 13. Device according to one of the above claims, characterized in that the coating device on a transport device is arranged. 14. Device according to one of the above claims, characterized in that in addition to the coating device on the carrier and a feed Distributing device for granular and / or fibrous fillers arranged is. 15. Device according to one of the above claims, characterized in that Additional feed pumps integrated into the hose package are.