DE19858618A1 - Thermal separation of electrically non-conducting materials, esp. concrete with/without steel reinforcement, involves continuously melting cutting gap along defined line of any shape, direction - Google Patents

Abstract

The method involves the use of a mobile plasma cutting system, whereby a cutting gap (15) is continuously melted along a predefined line irrespective of its shape or direction. The material is not fully separated along a line, but only a furrow (16) is formed and then the rest of the material is destroyed by macro cracks (17) caused by thermal stresses. An Independent claim is also included for a mobile plasma cutting system.

Description

It is the concern of this invention, one Method and device for thermal separation and / or destruction of electrically non-conductive materials, like rock, natural or artificial stone and especially of concrete with and without Steel reinforcement or combinations to provide these materials that mobile and independent of the respective Ambient conditions applied can be.

Thermal separation or destruction of these materials realized according to the invention in that a DC plasma generator with non- transferred arc used for this will melt those materials and either in the form of a continuous separate or cut additionally the energy of thermal To exploit tensions caused by the Heating the materials for are usually poor heat conductors and where the individual components, for example, very much of concrete different thermal expansion have coefficients, as well as by the Expansion and evaporation of trapped water arise and to Cause macro cracks.

Such cracks can be used according to the invention in that:

• a) in the case of materials without Reinforcement of the material is not complete thermally severed, but only in Cut into a furrow shape, where the cooling down emerging cracks preferably in the Direction of the greatest temperature spread gradient and the material thus destroy in depth.
• b) by means of a DC plasma generator perforation-like holes in one certain distance are generated this distance depending on Material itself, as well as from the introduced heat is chosen so that the gaps through thermal Tensions are destroyed.

The invention further includes that Tracking a conventional one Gas burner, its thermal and kinetic energy is used so that especially with deep cuts on thick ones Made of molten lava the joint, or the furrow more intensely is blown out.

The flexibility, mobility and complete The device becomes independent realized that all necessary Facilities for operating the Plasma generator or gas burner, consisting of energy (by a compact and diesel engine powered Combined heat and power plant, the generator with a DC power supply is coupled) and gas supply (e.g. cryogenic tanks), as well as a closed water Circulation cooling system as a module on one transportable pallet are mounted, and the DC plasma generator, the Gas burner as well as the necessary Handling and control systems in any great distance from the supply module and are connected by lines can. The device and method is preferably as a termination method old building fabric, so preferably for Building materials, such as concrete with and without Steel reinforcement suitable.

BACKGROUND AND STATE OF THE TECHNOLOGY

The large number of building materials, especially types of concrete, the diverse Kind of their reinforcement and the There is one possible application comparatively small number of Opportunities, such Separate materials effectively, or old ones Demolish the building fabric. Especially for Constructions with a high proportion of Steel reinforcement, such as that used for high industrial chimneys, bunkers plants or nuclear reactors are, is the number of possible Procedure limited.  

Then there are further restrictions present if mechanical procedures or explosions from space or other reasons are omitted, or if vibration and / or if possible must be worked dust-free.

The most common and cheapest Technology for cutting stone or Concrete is probably sawing using Diamond saw blades. But kick here too Problems when strong steel reinforcements or loose material in the Inside is there because of the hooking of the Saw blades on such obstacles usually leads to their destruction. Such reinforced concrete is usually used structures demolished in that first the steel reinforcement mechanically exposed and this in another Working step using flame cutting or other process is separated.

Some special procedures and attachments for separating electrically non-conductive Materials are known like that Application of lasers or high pressure Water jets (partly with additive abrasive powder), but in their Possibilities for thin workpieces are limited because both rays with increasing depth rapidly in energy to lose.

There are also a number of thermal ones Processing and destruction processes known from stone and concrete, the the best known of these is oxygen Core lance is the deep holes in walls and can melt foundations, however because of the necessary process gases and some additives used very much is expensive to use. Also kick Blowout problems viscous lava from deep holes. Also arcs and plasma generators were already for editing or Destruction of stone or concrete suggested their industrial Application is not known.

A DC plasma generator with no transmitted arc is a device at with a high current arc between them a tungsten cathode and one nozzle-shaped, water-cooled copper anode is ignited. This one Gas flow superimposed on the power and Depending on the plasma day, temperatures up to heated up well over 10,000 K and through the expansion to very high Speeds is accelerated and the nozzle as a current-free plasma free jet leaves. The application of such Plasma generator is for cutting electrically non-conductive materials required, as this is not - as usual when cutting metals with plasma transferred arc (between the Cathode and the workpiece) usual - as Counter electrode can be used. The amount of heat transferred is sufficient for almost all materials, even with high Melting temperature and density melt and the plasma speed can with appropriate nozzles design (Laval nozzles) supersonic achieve speed, what for Blow out the lava is important.

In U.S. Patent 3,788,703 (1974) M. THORPE a method and Device for melting rock in the Tunnel construction, where two DC plasma generators with separate power supplies be used to rock it melt that existing circuit from the two plasma beams and the Melt that is closed after a single burner was used melt a thin lava film, the melting process, so to speak transferred arc. On Cold gas or liquid flow was used for Quenching and blowing out the molten material.

SHIPAI et. al. patented in 1981 (U.S. patent 4,301,352) a device for surface Melting treatment for artificial stones, where the melting by one Arc was realized between two rotating drum electrodes was run parallel to the surface.  

In 1988 the Japanese company turned MAEDA Construction Corp. a procedure at which reinforced concrete is destroyed was that the steel reinforcement inside of concrete through high electrical current was warmed up, which was thermal Tensions that the Destroyed workpiece.

J. JUREWICZ had a method for Surface treatment of granite patent (U.S. Patent 5,211,156) to a DC plasma generator very quickly over that surface to be treated was led. A subsequent stream of water startled these areas abruptly, and the resulting thermal stresses led to flaky flaking a thin surface layer.

MURAKAMI (Japanese patent 07062899 and U.S. Patent 5,532,449) suggested the application of a Dummy electrode immediately on the to melting concrete surface that as Counter electrode for an arc served. The plasma was in through a hole this electrode on the one to be melted Transfer material. The same author developed a process in 1996 in which the arc between two electrodes existed, which melted in the process were and where the electrode material should also react with the lava (Japanese patent 08332627).

Another special device was developed by TAKEUSHI et. al. Patented in 1996 where an electrode as a continuous band in Formed a hollow electrode and was also consumed. In addition have been reactive powders to accelerate of the melting process.

ADVANTAGES OF THE INVENTION

The invention includes a novel, flexible and mobile, as well as of Ambient conditions perfectly independent plasma cutting system for electrically non-conductive materials too with great density and for great depths, with a DC plasma generator not transferred arc as he uses principally from thermal Coating industry for a long time is known. Necessary modifications concern only the composition of the working gas, as well as the shape of the nozzle and cathode. It is state of the art that these wear parts of the device optimized parameters over a long time Downtimes are relatively cheap and exchangeable within a very short time are.

The generated by this plasma generator Electroless plasma jet is at appropriate performance capable of each electrically non-conductive material to melt and separate, regardless of possible material com combinations and reinforcements. Except the This happens to electrodes and working gases without additional additives or Substances.

It is because of the specific Material properties often do not required, the workpiece to be cut completely cut it but it others can according to the invention destructive forces, such as the formation of Macro cracks due to thermal stresses or that evaporating in the workpiece Water can be exploited whatever the Cutting speed or Separation increases and the effort involved lowers.

The process is almost vibration-free starting the development of the environment hazardous flue gases and large Amounts of dust are prevented.

The separation can be done with correspondingly high Services quickly and inexpensively a variety of materials also great Thickness can be applied, with the Change of material within one Workpiece or the type and degree any reinforcement Cause problems.

Steel reinforcement even has a positive effect on the cutting process because it is liquid Iron the viscosity of the melt reduced and thus the blowing out of the melted lava simplified.  

The inventive method of thermal separation and that device described is mainly as a supplement or alternative to conventional demolition of the Construction industry thought, mainly on separating building materials, preferably directed reinforced concrete.

The goal is the separation process location-independent and independent of the Environmental conditions and that too cutting material in one To carry out the work step. The number the parameters to be checked (Current, voltage, gas throughput Cooling water and feed) is low, that Procedure can be done by hand or apply fully automated.

DESCRIPTION OF PICTURES

Fig. 1 shows the scheme of the device according to this invention

Fig. 2 describes the DC plasma generator in more detail and illustrates the continuous melting of continuous joints or non-continuous furrows

Fig. 3 illustrates the destruction of a workpiece by melting perforation-like holes and using thermal stresses to destroy the gaps

DETAILED DESCRIPTION THE DEVICE AND EXPLANATION OF THE METHOD

A compact cogeneration plant, consisting of a fuel tank ( 1 ), internal combustion engine ( 2 ) and generator ( 3 ) provides the electrical energy of the device, which is supplied to a direct current supply ( 4 ). This supplies current and voltage for generating a high-current arc ( 12 ) between the cathode ( 13 ) and the nozzle-shaped anode ( 14 ) of the DC plasma generator ( 7 ). The process gas is fed from a tank system ( 5 ) and superimposed on the arc. It emerges as a current-free plasma jet ( 10 ) at high temperature and speed from the nozzle ( 14 ). The plasma generator ( 7 ) - optionally together with a conventional gas burner (not shown separately in the figures) - the handling and movement system ( 9 ) and the control unit ( 8 ) form the so-called UNIT II, which is arranged directly in front of the workpiece to be cut becomes.

It is connected via lines to UNIT I, on which all other components are mounted on a transportable pallet, so that the device can operate completely independently of the ambient conditions ( Figure 1).

After igniting the arc and setting the necessary parameters, the workpiece can be cut using the following methods:

• a) The plasma jet is placed on an edge or in a through hole and immediately begins to melt the material. If there is a continuous cutting gap ( 15 ), the plasma generator can be continuously moved in any direction and the material can thus be separated. The speed of the cut depends on the type of material and its thickness and can be easily controlled via the performance of the plasma generator. The molten material is blown out - optionally with the help of a tracked, conventional gas burner - on the side of the workpiece facing away from the plasma generator.
  The width of a kerf is usually in the range of four to eight times the nozzle diameter of the plasma generator. This method can be used for all materials, in any combination, with and without reinforcement ( Figure 2).
• b) In some cases it is not necessary to cut the workpiece completely.
  Similar to method (a), the workpiece is melted continuously and with any geometry, but not in a cut through the entire thickness, but in the form of a groove ( 16 ) to a certain depth of the workpiece, usually up to Center. The macro cracks ( 17 ) caused by the thermal stresses are usually sufficient to destroy the remaining part.
  This method can be used especially for materials without reinforcement and is characterized by a higher speed and therefore lower energy and gas consumption.
  Since the plasma jet is deflected in the joint against the cutting direction, which is accompanied by a loss of energy, it is advantageous for the variants (a) and (b) to position the plasma generator at an angle against this deflection.
• c) Holes, similar to a perforation, are partially or completely melted into the material at regular intervals along a preferably horizontal or vertical line. Depending on the type and thickness of the workpiece, as well as the amount and duration of the heat input, the distance can be chosen so that the areas between the individual holes are torn apart by thermal stresses.
  Due to the favorable conditions of the vertical heat transfer and the impact flow, thermal drilling can be realized much faster than continuous cutting. This method is also preferably suitable for materials without reinforcement ( Fig. 3).

Claims (5)

1. A mobile plasma cutting system for electrically non-conductive materials, the the complete devices for Supply of electrical energy and Working gas, for cooling and handling a DC plasma torch with not transferred arc and one contains additional gas burner to the System completely independent of the Environmental conditions operate too can. 2. Cutting rock, natural or artificial stone and especially from Concrete with and without reinforcement with one Device according to claim 1 by the continuous melting one Cutting gap along a predetermined Line, regardless of their shape or Direction. 3. The separation of materials according to Claim 2 with a device according to Claim 1, realized in that the No material along a line is completely severed, but just melted a furrow and the Rest of the material due to macro cracks, caused by thermal stress, gets destroyed. 4. Forcing the blowing out of the lava when separating according to claim 2 and 3 by taking advantage of thermal and kinetic energy of a tracked, conventional gas burner. 5. The separation of materials, according to Claim 2 with a device according to Claim 1, realized in that along a line at regular intervals Holes partially in or completely through the material is melted and used to Destroying the gaps macro cracks, caused by thermal stresses be exploited.