DE102017105106A1 - COMPOSITE STEEL BAR - Google Patents

Abstract

A composite grate bar for a grate comprising a steel alloy body having a top surface and at least one side portion. A cast iron alloy sprue at least partially covers the top of the body.

Description

The present description relates to feed grates, backbones, and more particularly to composite grate bars for combustion grates.

Grate firing is a solid-fuel firing in which the fuel burns horizontally on a grate, an apertured bearing surface. The openings in the grate bar serve to supply the underwind, which contains the gases necessary for the combustion, and the discharge of the remaining ash. A movement to circulate or stoke the fire and to remove the ash is done in simple grate firings manually with a poker, in larger grate firing automatically by proper movement of the grate.

In an industrial grate firing, the fuel supply to the grate takes place automatically and continuously, for example by means of screw conveyors, mechanical slides or double flaps. Through this conveyor a conclusion is made at the same time to the fuel storage tank and prevents burn-back.

The fuel is continuously conveyed by a moving mechanism from the entry to the ash discharge and automatically circulated. In the first area of the grate, a drying and degassing of the fuel takes place. It is followed by the main combustion zone, and in the last grate section, the burnout takes place.

A stair grate or bulkhead looks similar to a flat staircase with a gradient of 8 to 15 degrees.

The fuel is moved across the grate by oscillating back and forth a few steps, for example every second or two out of three, pushing the fuel forward. Depending on the direction of the grate bar movement, the stair grate is also called feed grate or return grate. In both cases, however, creates a forward movement for the fuel.

The present specification discloses a composite grate bar in which the grate bar is designed not as a one-piece casting but as a metal composite part, whereby characteristics of the grate bar can be improved.

The composite grate bar is especially intended for installation in a stair grate or sliding grate. However, the composite grate bar may also be designed for use in a stationary grate, in a traveling grate or in a roller grate.

During operation of a pushroof, thermal and mechanical wear occurs at an upper portion of the grate bar, in which another layer of grate bars rests and moves relative to the grate bar. At a front area of the grate bar occurs mainly thermal wear.

Accordingly, in an embodiment of a grate bar according to the present description, a refractory material may be provided on the surface of the grate bar. In contrast, the ribs and the supporting portion of the grate bar, when not exposed to such high temperatures, may be made of another less heat-resistant material. In particular, the main body of the grate bar can be made of sheet steel or cast iron.

In this case, a wall thickness of the base body can be dimensioned so thin that it is possible to produce the basic body in a flat configuration, for example by cutting, punching or casting, and then to bend, assemble or add it to a final shape.

According to a manufacturing method of the composite grate bar, a steel-made portion of the grate bar is cut out of sheet steel, and then folded or bent, so that after a later pouring correction is no longer necessary. The steel-made area is placed in a mold and the refractory but fracture-prone, lower tensile material is poured over it. This type of production is also referred to as composite casting.

This production of the grate bar by a composite casting requires, inter alia, the following property: it requires less casting material and can be used as a casting material cheaper and more durable Use heat-resistant material, for example, a material with a high nickel and chromium content. The brittleness of the casting material is a minor problem, because the made of steel area in the tensile stress region of the grate bar has a relatively high tensile strength, while the more sensitive to tension and consisting of cast material area of the grate bar located in the compressive stress range of the grate bar. If, during operation of the grate bar, a crack occurs in the heat-resistant area, then the entire grate bar does not immediately break because the main body assumes a supporting function.

The casting material may be added to a chromium portion, which may be, for example, at least 12 wt .-%. Among other things, the chromium component causes a passivation that protects the casting material from corrosion. The passivation comes about through contact with the oxygen from the surrounding media. As a result, a thin, only a few atomic layers thick transparent layer of chromium oxide forms on the surface of the casting material. In addition, the chromium content increases the hardness.

Other alloying elements that can be added to the casting material to increase the hardness of the casting material include manganese, silicon, nickel, tungsten, vanadium, molybdenum, and cobalt. Hot strength can be increased in particular by adding tungsten, vanadium, molybdenum or cobalt, but also by adding silicon, chromium or nickel.

For example, a cobalt-containing alloy may include 2.0% -4.5% silicon, 0.5% -5% cobalt, 2.0% -4.5% carbon, and 0.3% -1.48% molybdenum. In the present description, percentages of alloying elements and material additives should refer to percentages by weight (% by weight, wt .-%), unless stated otherwise.

Among others, for example, the following nickel chromium alloys can be used: Surname C% Si% Ni% Cu% Cr% Alferon 0.4-0.6 2-3 18-20 - 18-20 Niresist 2.5-3.3 up to 2 15-20 5-10 2-6 mmoles 2.5-3.3 - 15-20 5-10 until 20 Nicrosil 2.5-3.3 Till 8 12-20 5-9 2-6 Nicrosilal z. B. 1.8 6 18 - 2 EN-GJSA-XNiCr20-2 to 3.0 1.5-3.0 18.0 to 22.0 to 0.5 1.0-3.5 EN-GJSA-XNiSiCr35-5-2 to 2.0 4.0-6.0 34.0 to 36.0 to 0.5 1.0-3.5 EN-GJSA-XNiCr30-3 to 2.6 1.5-3.0 28.0 to 32.0 to 0.5 2.5-3.5 EN-GJSA-XNiSiCr30-5-5 to 2.6 5.0-6.0 28.0 to 32.0 to 0.5 4.5-5.5

Other suitable materials include, but are not limited to, the following heat resistant cast steel materials DIN EN 10259 : the alloyed stainless steels with a nickel content of> = 2.5% according to material index 1.4837, GX40CrNiSi25-12 and material index 1.4823, GX40CrNiSi27-4 and the alloyed stainless steel with a nickel content <2.5% according to material index 1.4723, GX160CrSi18. Furthermore, among other things, the valve steel alloy is after DIN EN 10090 according to material code 1.4747, X80CrNiSi20.

As a special material, an austenitic cast material can be used, such as the materials mentioned in the above table GJSA-X NiSiCr 35-5-2 or GJSA-X NiSiCr 30-5-5.

A composite grate bar according to the present specification is a composite metal component manufactured by a pouring method. In particular, the composite grate bar can have castings made of steel and / or cast iron, in particular GGG, GJV or GGL, and sprues or cast-on parts made of the material steel, cast iron or light metal.

Cast iron can be characterized by steel, for example, by the carbon content. According to such a classification steel has a carbon content of <2.06% and cast iron a carbon content of> 2.06%. Typically, cast iron has a carbon content of 2.5% -4% but may be lower or higher.

The term "GGG" refers to spheroidal graphite cast iron, also referred to as ductile iron, globular cast iron or ductile cast iron. After current European standard EN 1563 is the term for "GJS", and after the earlier DIN 1693 "GGG". The globular shaping of the graphite can be effected in particular by additions of magnesium or cerium.

"GGL" refers to cast iron with lamellar graphite or lamellar gray cast iron (designation after current European standard EN 1561 "GJL" or earlier after DIN 1691 "GGL") and "GJV" refers to vermicular graphite casting (designation GJV after current ISO 16112 , formerly GGV). The lamellar gray cast iron has better thermal conductivity compared to nodular cast iron, but is more brittle and can absorb less tension. The properties of vermicular graphite cast lie between those of lamellar and globular gray cast iron.

In particular, GJL cast iron may include the materials GJL-100-GJL-400, GJV cast iron the materials GJV-300-GJV-500, and GJS cast iron the materials GJS-400-GJS-800, where the three-digit code indicates a minimum tensile strength in megapascals.

The material types GJL, GJV, GJS are also called gray cast iron, whereas malleable cast iron and chilled cast iron are also called white cast iron.

In particular, the present description discloses a composite grate bar for a combustion grate, in particular feed grate or roller grate, wherein the composite grate bar has a base body made of a steel alloy, an upper side and at least one side part. The upper side is formed on an upper part and the at least one side part adjoins the upper part on an underside of the upper part and is oriented in a longitudinal direction or longitudinal extension of the grate bar.

For example, the composite grate bar may have a T-shaped profile, wherein the at least one side portion is formed by a web of the T-shaped profile. In a further embodiment, the composite grate bar may have a U-shaped profile, wherein the at least one side part has a first side part, which is formed by a first web of the U-shaped profile and has a second side part, which by a second web of the U-shaped profile is formed.

The composite grate bar has a sprue of cast iron alloy, the sprue at least partially covering the top of the body. In particular, the gate may cover the top of the body more than 50%, more than 90%, or substantially all.

In particular, an iron alloy for the sprue may have a lower tensile strength than the steel alloy of the main body. This is made possible by the fact that the main body absorbs the tensile stresses that occur when a load of the grate bar from above below a neutral fiber of the grate bar.

Optimizing an upper portion of the grate bar to desired material properties, such as heat resistance, abrasion resistance, or material cost, is simplified because the sprue material, particularly located on top of the grate bar, need not exhibit as high a tensile strength as the body material. For example, a cast iron that is cheaper than the steel alloy of the main body can be used for the sprue. In particular, the sprue may consist entirely or essentially of cast iron.

Alternatively, or in addition, the gate may have certain advantageous properties that are beneficial where the gate is applied. In particular, the sprue may have a higher heat resistance or a higher abrasion resistance than the main body. These properties are particularly advantageous on the top of the grate bar on which rest the fuel and optionally other grate bars.

It is also possible that the sprue has an iron or steel alloy that has a higher material price than the base body. Also in this case, there is an advantage that the Sprue material and the body can be optimized separately to the desired material properties. For example, the material of the body may be selected to have improved weldability to the gate material in addition to higher tensile strength.

According to a further embodiment, the sprue is at least partially an encapsulation enclosing a portion of the body. This can be realized, for example, by providing passage openings of the base body in the base body, which are filled with the sprue, whereby rivets are formed. Thus, a better connection between the body and sprue can be made. Furthermore, the connection between the base body and sprue can be improved by applying a flux to corresponding regions of the base body before applying the sprue.

According to a further embodiment, the base body is formed from a steel sheet, for example by plasma cutting or laser cutting and subsequent forming into the desired final shape. Possible advantages over a base made of cast steel, for example, result from an easier formability or from a cost or weight savings.

In this case, a side facing the bulk material can be formed from a metal casting and a side facing away from the bulk material can be a preformed sheet steel component. The steel sheet component is inserted in the production in a grate bar mold and then connected in a composite casting cohesively with the casting material.

This can form a grate bar surface that is not prone to cracking. Thus it can be avoided impact loads acting on the bulk material side on the grate bar cause cracking on the side facing away from the bulk material of the grate bar. This applies in a similar form to the other embodiments of the present description.

In particular, the steel sheet can be formed by bending. Accordingly, the main body may comprise a bent steel sheet or consist of a bent steel sheet, wherein bent portions of the steel sheet have at least a first transition region which is arranged between the upper side and the side part.

With regard to an improvement in heat resistance and / or abrasion resistance, the sprue may particularly include the following material compounds.

According to a first embodiment, the gate comprises iron, carbon and at least one of manganese, tungsten, vanadium, molybdenum, cobalt, silicon, chromium or nickel in an amount of at least 2%.

In particular, the gate may comprise metal compounds with nickel or cobalt and / or with chromium and / or with nickel. According to one embodiment, the gate comprises at least one of nickel and cobalt with a weight fraction of at least 2%. According to a further embodiment, the sprue has chromium with a weight proportion between 2% and 20% amounts to.

According to a further embodiment, the sprue comprises nickel, wherein a weight fraction of the nickel is between 10% and 36%. According to a further embodiment, the sprue comprises chromium and nickel, wherein a chromium portion of the sprue is between 2% and 20% and wherein a nickel content of the sprue is between 10% and 36%.

According to a further embodiment, the sprue material detects an alloyed stainless steel DIN EN 10259 in particular GX40CrNiSi25-12, GX40CrNiSi27-4 or GX160CrSi18 comes into consideration. The sprue can be predominantly, substantially or completely made from the alloyed stainless steel DIN EN 10259 consist, for example, with a weight fraction of more than 50%, more than 90% or more than 99%.

According to a further embodiment, the sprue material after a valve steel DIN EN 10090 in particular X80CrNiSi20 comes into consideration. The sprue can predominantly, substantially or completely out of the valve steel DIN EN 10259 consist, for example, with a weight fraction of more than 50%, more than 90% or more than 99%.

In particular, a thickness of a sprue material on the surface of the composite grate bar may be a predetermined thickness, such as at least 3 mm.

As already mentioned above, the base body of the composite grate bar can have through holes which are filled with the sprue material. These through-holes can be oriented in particular transversely to a longitudinal extent of the composite grate bar. For example, the body may have at least two, at least five, or at least eight through holes.

Furthermore, the composite grate bar may have a second cast area, the second cast area covering portions of the at least one side portion. These portions may also be at least partially below the neutral fiber. In particular, the second molded portion may improve material properties of ribs of the composite grate bar, wherein the ribs are connected to the at least one side member. In particular, a first side part and a second side part of the base body may each have at least a first rib and a second rib.

Furthermore, the present disclosure discloses a furnace grate, in particular a stair grate or a roller grate with an assembly of a plurality of composite grate bars according to any one of the preceding claims, wherein at least some, such as 20%, half, or all of the plurality of composite grids. Grate bars are connected to a drive of the Feuerungsrostes.

In another aspect, the present disclosure discloses a method of making a composite grate bar for a grate.

According to this method, a base body made of a steel alloy is provided, wherein the base body has an upper side and at least one side part which extends in the longitudinal direction of the main body, which is, for example, a first side part and a second side part opposite the first side part.

A flux is applied to the body, the body is placed in a mold and a sprue having an iron alloy is applied to the body by placing the molten sprue in the mold such that the sprue at least partially covers the top of the body. In particular, the gate may cover the top of the body more than 50%, more than 90%, or substantially all.

Furthermore, the casting of the sprue can be repeated so that the sprue forms multiple layers, for example to produce a higher total thickness or to produce certain material properties.

The main body can in particular be formed from a steel sheet, for example by laser cutting or plasma cutting or punching and other forming processes such as bending. Furthermore, a plurality of through holes can be formed from the main body.

In the following, the subject of the present description will be explained with reference to the following figures.

1 shows a sheet metal part of a composite grate bar in a developed configuration,

2 shows a side view of a composite grate bar, the sheet metal part of 1 containing an area showing a casting material,

3 shows a cross section through the composite grate bar of 2 .

4 shows a further cross section through the composite grate bar of 2 .

5 shows another side view of the composite grate bar of 2 in which a shape of the sheet metal part of 1 clarified in a casting,

6 shows a side view of the sheet metal part of 1 after the bend,

7 shows a flowchart of a method for producing the composite grate bar of 2 .

8th shows a cross section of another embodiment of the composite grate bar in a mold,

9 shows a cross section of another embodiment of the composite grate bar in a mold, and

10 shows a cross section of another embodiment of the composite grate bar in a mold,

11 shows a composite grate bar according to another embodiment,

12 illustrates a behavior of the composite grate bar under bending stress,

13 shows a composite grate bar for a roller grate,

14 shows a view of the grate bar of 12 .

15 shows a longitudinal section through the grate bar of 13 .

16 shows a first cross section through the grate bar of 13 .

17 shows a second cross section through the grate bar of 13 , and

18 shows a perspective view of the grate bar of 13 ,

1 shows a main body 10 a composite grate bar in an unwound configuration in which a top surface 11 , a first side part 12 and a second side part 13 lie in one plane.

The shape of the body 10 according to 1 represents an exemplary embodiment. Other shapes are also possible.

The main body 10 has the aforementioned top 11 , the first side part 12 and the second side part 13 on. The shape of the first side part 12 is essentially the shape of the second side part 13 identical. The side parts 12 . 13 point to a suspension page 14 a rounded engagement area 15 on.

From the rounded engagement area 15 extends a middle range 16 or transition area 16 in the embodiment of 1 to about the middle of the body 10 enough. Between the transition area 16 and a head area 17 of the basic body 10 there is another intervention area 18 whose cross-section is in the form of a downwardly open rounded rectangle.

The head area 17 of the basic body 10 is rounded off on a front of the main body. The head area 17 the side parts 12 . 13 protrudes down over the other areas of the body 10 out and has on its underside a flat bearing surface 19 on. The bearing surface 19 is to the suspension page 14 of the basic body 10 slanted slightly upwards.

Here, the terms "top" and "bottom" refer to a folded or bent configuration of the main body 10 in which the in 1 shown upper surface of the top 11 located at the top.

Due to the round shape of the rounded engagement area 15 For example, the grate bar may rotate about an axis of a bar that is in the rounded engagement area and that in FIG 2 . 5 and 6 indicated by a dashed line. Due to the rotatability, among other things, a replacement of the grate bar can be facilitated.

The shaping of the second engagement area 18 allows the introduction of a mounting rod from the side of the body ago. At the second engagement area 18 are two lateral tabs 20 . 21 trained in the 1 Do not hold down the attachment rod, pointing downwards. By the mounting rod adjacent grate bars can be connected together.

In 1 are bending areas 22 . 23 the side parts 12 . 13 by dashed lines 24 . 25 indicated. After bending the main body 10 set the bending ranges 22 . 23 a transition from the horizontal top 11 to the vertical, aligned at right angles to the top side panels 12 . 13 dar. Another dashed line 26 shows an axis of symmetry of the body 10 at.

The 2 and 5 show side views of a composite grate bar 29 who is the one in 1 shown basic body 10 contains, wherein each cast areas and the basic body 10 are highlighted. The grate bar 29 corresponds to those in the PCT application WO / 2012/032492 shown grate bars, and in particular the grate bars 10 . 42 . 44 . 62 . 63 . 80 . 120 , and 140 which, inter alia, in the 1 . 6 . 7 . 18 . 19 . 20 are shown.

In 2 is a lower cast area 30 and an upper cast area 31 highlighted by black coloring. The lower cast area 30 has a header 32 , a horizontal area 33 , a first rib 35 , a second rib 36 and an end area 34 on.

The upper cast area 31 extends over the entire top 11 of the basic body 10 and has a rounded head area 37 , a flat surface area 38 , and a bent rear area 39 on. The upper cast area 31 forms a layer of approximately uniform thickness on the top 11 of the basic body 10 and thus follows the outer shape of the top 11 of the basic body 10 ,

The upper cast area 31 has a heat and abrasion resistant material, such as a steel-nickel-chromium alloy. The lower cast area 30 however, may have a less heat and abrasion resistant material.

3 shows a cross section through the composite grate bar 29 along the cross-section line AA, where the main body 10 is highlighted by a black coloring. A boundary between the lower cast area and the upper cast area is by a horizontal line 40 indicated.

4 shows another cross section through the composite grate bar 29 along the cross-section line AA, with all the material of the composite grate bar 29 that is both the main body 10 as well as the cast area 30 . 31 includes, shown in black.

5 shows another side view of the composite grate bar 29 from 2 , where the main body 10 indicated by outlines.

6 shows a side view of the curved body 10 in which one of the side panels 13 of the basic body 10 is shown. A drive rod with a round cross section, which is in the engagement area 15 engages is in 5 and 6 each indicated by a dashed line. The drive rod may be stationary or in the longitudinal direction of the composite grate bar 29 be driven.

7 FIG. 12 is a flowchart of a method for manufacturing a composite grate bar according to the present description. FIG.

First, a base body made of a steel alloy is provided. The base body may be made, for example, by cast steel or by molding from a steel sheet. When the base body is made of a steel sheet, according to an exemplary embodiment, a base body 10 in a first step 50 formed from a steel sheet or separated by a separation process of the steel sheet. The steel sheet may be specially pretreated, for example, it may be rolled, hammered or sintered.

The separation process used is preferably a thermal separation process such as laser cutting, plasma cutting or flame cutting. If a smaller sheet thickness is selected, a punching method or a fine blanking method may also be used. A fineblanking process is typically suitable for sheet thicknesses up to 20 mm, whereas laser cutting can still be used for sheet thicknesses of up to 25-30 mm and plasma cutting even for sheet thicknesses of 160 mm.

In a further step 51 becomes the basic body 10 bent into a desired shape. In this case, the basic body 10 optionally heated for easier molding. In a further step 52 becomes the finished bent body 10 placed in a mold. Alternatively, the side panels or the side part of the body and the upper part of the body are also made separately and in the step 51 the side parts or the side part are welded to the upper part.

After the main body 10 is introduced into the basic form is in a further step 53 a lower cast area 30 made, and it will be in a further step 54 an upper cast area 31 produced. The cast material used includes a suitable iron alloy, such as heat and abrasion resistant steel alloy or a cast iron alloy with suitable properties. In a further step 55 becomes the composite grate bar 29 let cool.

According to a further embodiment, a flux is applied between the main body or the cast part and the sprue material. The coating with a flux has the advantage that, when the coated casting is overmolded, the oxide skin of the casting is reduced, dissolved and washed away, and thus the casting material can form a metallurgical bond with the metal of the casting. For better connectivity and to achieve a better adhesion of the base body can also be coated with a metal layer, for example, the main body can be galvanized or hot-dip galvanized.

In particular, the flux may include alkali or alkaline earth borates, fluorides and / or phosphates, as well as additives suitable for pouring iron alloys such as steel or cast iron. The proportion of aggregates is typically 1 to 25 percent by weight. In the amounts needed for the effect as a flux, there is no adverse effect on the alloy composition in the joining zone between the sprue and the casting material.

In particular, the fluxes are suitable for the combinations steel / steel, steel / cast iron and cast iron / cast iron. The same applies to the combination of steel / aluminum alloy and cast iron / aluminum alloy if a first layer of Sn, Sn alloy, Ni, and / or Ni alloy is applied to the cast part. With regard to the composite grate bar of the present description, the steel / cast iron combination is particularly important.

Further fluxes are, for example, eutectic compositions of K ₃ AlF ₆ and KAlF ₄ or K ₂ ZrF ₆ . According to another method of preparing the gate for connection to the gate or casting, a metallic layer of Al-Si or Fe is applied to the body. Then, the body is sandblasted and / or sprayed with silicon powder and / or borax (Na ₂ B ₄ O ₇ -10H ₂ O, hydrated sodium borate), and the coated body is cast.

The flux preferably contains borax (Na ₂ B ₄ O ₇ -10H ₂ O), boron oxide, NaF, KF, K ₂ ZrF ₆ , K ₃ AlF ₆ , KAlF ₄ or Na ₃ PO ₄ or MgF ₂ . Most preferably, the flux contains borax and KAlE ₄ in a ratio of 1: 5 to 5: 1.

The additives present in the flux can be subdivided in particular into casting aids or coating aids. The content of aggregates may range from 1 to 50% by weight of the flux. The content of coating aids is preferably at the lower limit of the range, in particular from 1 to 5 percent by weight.

Casting aids include metallic powders which are low melting or eutectic. The metallic additives also act as metallic reducing agents. In particular, these are also suitable for reducing the formation of new oxides on the surface of the casting during preheating or casting.

In this case, Sn alloys, Sn / Cu alloys, Ni and / or Ni alloys are preferably used. Particularly suitable Sn alloys include SnCu _0.7 Ni _0.1 or SnCu _0.7 . These casting aids promote the reduction of the oxide layer and its removal, and in particular the melting of the surface of the sprue by forming low-melting alloys.

The coating aids have the task of adjusting the viscosity or thixotropy, if appropriate, of liquid coatings and of binding or solidifying the coating applied to the surface. The coating auxiliaries are preferably selected from organometallic polymers, silane and / or siloxane resins which are used as binders. The silane resins and siloxane resins have the additional advantage of reducing the oxide layers.

In a preferred embodiment, the flux is applied to the casting in the form of an aqueous solution or suspensions. As alkaline earth borates, fluorides, complex fluorides and / or phosphates and aggregates.

Depending on the consistency, the flux can be applied, for example, by screen printing (paste) or spraying or brushing or dipping (liquid). If the flux is applied as a liquid coating, a separate drying of the flux is required before the sprue takes place. The layer thickness of the flux in the dried state is preferably in a range of 0.1-1.0 mm.

As a casting method, a low-pressure casting or a medium-pressure casting method is preferably selected. This is especially true when steel or cast iron is chosen as the casting metal. The pressure used in low-pressure casting is usually between 0.02 and 0.1 MPa depending on the necessary height of rise and the density of the cast material. The casting pressure is in steel and cast iron is preferred as a material at an overpressure of about 0.3 to 5 bar.

A precise control of the casting pressure, as well as the pressure profile with pressure build-up, holding phase and holding pressure is advantageous for a uniform and void-free mold filling. Preferably 0.5 to 1.5 bar are used. However, a casting method without application of compressed air or inert gas may also be used.

The process-related slow inflow of the melt in this case favors both the dissolution and Wegschwemmen the oxide layer, as looking for the melting of the casting surface. The melt can also flow largely laminar beyond.

In a preferred embodiment, the melt of the sprue or Umgussmetalls is supplied from below into the mold. This has the advantage that the dissolved oxide layer or the forming slag is discharged from the forming composite casting, since oxides or slag float on top. An unfavorable backmixing with the melt is thereby largely prevented.

Particularly preferably, the feeders or the sprue are not placed in the immediate vicinity of the casting, or of the joining zones. The insert is preferably fitted into the mold so that the outgassing of the reaction products of the flux upwards can be carried out as undisturbed.

The casting mold or the melt supply are preferably designed such that the melt can flow largely laminar and without backmixing along the surface of the casting. This results in favorable flow conditions, which favors the washing away of the oxides or slag and the melting of the surface of the sprue.

Due to the favorable thermal and flow conditions, comparatively thicker layers of the flux can be used with thicknesses in the range of 0.5-1.0 mm in this variant. Depending on the geometry and relative position of the casting in the mold, the thickness of the flux can be adjusted differently.

The 8th - 10 show an example of a composite grate bar 29 ' . 29 '' . 29 ''' in a mold 61 , The mold 61 consists of an upper half 62 and a lower half 63 , The upper half 62 has an inlet or feeder 64 for introducing an alloy or a sprue material 65 on.

The main body 10 is in a cavity 66 the mold 61 arranged. The main body 10 is with the molds 56 ' . 61 '' of the 9 and 10 within the cutting plane on the respective lower half of the mold 63 ' . 63 '' supported downwards. In contrast, the main body 10 at the mold 61 of the 8th through areas of the mold 61 supported outside the cutting plane of the 8th lie. The sprue or encapsulation is formed by areas of the alloy, which is the main body 10 surround.

In a casting process, the body is first 10 in the lower half of the mold 61 used. Then the top half 62 the mold 61 put on and poured a predefined amount of the alloy through the inlet. In particular, for a better connection of the main body 10 with the sprue or casting material before pouring a flux on the body 10 may be applied or the flux may be poured into the mold prior to pouring the sprue material 61 be filled.

The main body 10 can, as described above, be made by bending from a cut, stamped or cast mold, but also by other manufacturing processes, such as casting, joining or welding. In order to improve the weldability, a carbon content of less than 0.22% steel base body may be selected.

According to the 8th is the main body 10 completely covered by the sprue or casting compound, while the main body 10 according to 9 above and on the outer side surfaces of the body 10 is covered by the sprue or Umgussmasse and according to 10 only on an upper side of the main body 10 is covered by the sprue or Umgussmasse. In particular, in the embodiments of the 8th and 9 the basic body needs 10 not to be covered along the entire length of the main body as shown in the cross section of the sprue or Umgussmasse. For example, in the embodiment of the 10 Be provided areas in which the main body to the mold 51 is supported.

Furthermore, the molded or the cast-over area can also be divided into two or more areas separated areas, each of which is fed by a separate channel. For example, the top of the main body 10 and individual, separate areas of the side surfaces of the body 10 be covered by sprue or Umgussmaterial. Furthermore, the cast-over area can also be cast by a composite casting process in several layers, wherein the individual layers may consist of different alloys.

The view from 8th - 10 serves to illustrate the casting process and is merely a simplified, schematic representation. For example, in gravity casting additional wind tunnels may be used to escape the air from the mold 61 be provided. Furthermore, within the mold 61 or a core may be arranged between the halves of the mold.

Especially if the mold 61 provided by a metallic mold, the channel for pouring the casting material can also extend between the two mold halves. The casting mold can in particular also be divided vertically into a left and a right mold half. By chill casting with a metallic mold rapid cooling and a fine texture can be achieved with correspondingly advantageous properties.

Furthermore, instead of in 8th - 10 Gravity casting, in which the casting material is forced by gravity into the mold, also uses a die casting process, such as low pressure casting. In particular, during die casting, the inlet can also be arranged on an underside of the casting mold or laterally.

In a further process step, the cast-on base body may be subjected to a heat treatment in a heat treatment furnace after casting, in order to thereby achieve a predetermined microstructure.

The 11 shows a further embodiment of a composite grate bar 10 in which through holes 67 are provided, which are transverse to a longitudinal axis of the composite grate bar 10 and near an upper surface of the composite grate bar 10 ' run. During the casting process, the through-holes are filled by the sprue material, so that the over-molding is the composite grate bar 10 ' as a rivet connection encloses.

12 illustrates a behavior of a composite grate bar 10 ' according to the application under bending stress. The grate bar 10 ' is at its front end and at its rear end, which is symbolized by a front and a rear bearing. Through on the grate bar 10 ' Overlying fuel and possibly also by other resting grate bars acts on the grate bar 10 ' from above a bending force F a.

This bending force F leads to a deformation of the grate bar 10 ' , In an upper area 70 of the grate bar 10 ' above a neutral fiber 68 becomes the material of the grate bar 10 ' while the material is compressed in a lower area 71 of the grate bar 10 ' is stretched. In a range of neutral fiber 68 the material is neither compressed nor stretched. The neutral fiber 68 passes through the centroid of a cross section perpendicular to the longitudinal extent of the grate bar 10 ' , For the sake of simplicity, the neutral fiber 68 about halfway up the grate bar 10 ' located.

The strain or compression ε of the grate bar 10 ' increases with increasing distance from the neutral fiber 68 to. This increase is, to a good approximation, linear. The linear increase is along a selected cross section of the grate bar 10 ' through triangular areas 69 indicated. Similarly, the increase in compressive stress σ as a function of the distance from the neutral fiber is linearly approximate.

In a grate bar according to the present application, a portion of the area below the neutral fiber 68 consist of a cast material having a good tensile strength, such as a steel alloy. In contrast, an area above the bending line can be made of a material which has a lower tensile strength and at the same time has a good compressive strength. For this purpose also steel alloys are considered, but also other iron materials that are suitable for casting, such as cast iron.

Cast iron is usually cheaper than steel. Thus, a layer of cast iron of sufficient thickness can be provided. Furthermore, a worn grate bar can be provided in a cost effective manner with a new layer of cast iron.

The 13 to 18 show different views of a composite grate bar 10 '' for a roller grate. The abovementioned method steps can also be used in a similar form for a grate bar for a roller grate, such as in 13 shown.

Show in detail 13 a side view of the composite grate bar for a roller grate, 14 a view of the composite grate bar, 15 a longitudinal section through the composite grate bar, 16 a cross section through the composite grate bar, 17 a second cross section through the composite grate bar, and 18 a perspective view of the composite grate bar.

In the following, the subject matter of the present description is explained by exemplary combinations of features that can be combined with each other and with the features and embodiments described above.

According to one embodiment, a method for producing a composite grate bar for a firing grate is disclosed, according to which a base body made of a steel alloy is provided, wherein the main body has an upper side and at least one side part. A flux is applied to this body at locations where a sprue is to be applied, the body is placed in a mold, and the sprue comprising an iron alloy is poured into a casting mold so that the sprue at least partially covers the top of the body covered.

According to a further embodiment, a thickness of the sprue material on the surface is expediently chosen so that the sprue material is not removed again too quickly. In particular, according to one embodiment, the thickness of the sprue material on the upper side of the main body can be at least 3 mm.

In the following, the subject matter of the present description will be explained by feature combinations in the form of an enumeration. These features may be combined with each other and with the features and embodiments described above.

• 1. Komposit-Roststab für einen Verbrennungsrost, der aufweist:
• – einen Grundkörper aus einer Stahllegierung, der eine Oberseite und wenigstens ein Seitenteil aufweist,
• – ein Anguss aus einer gegossenen Eisenlegierung, wobei der Anguss eine Oberseite des Grundkörpers wenigstens teilweise bedeckt.
• 2. Komposit-Roststab nach Ziffer 1, wobei der Anguss zumindest teilweise als ein Umguss ausgebildet ist.
• 3. Komposit-Roststab nach Ziffer 1 oder Ziffer 2, wobei die Eisenlegierung für den Anguss eine geringere Zugfestigkeit aufweist als die Stahllegierung des Grundkörpers.
• 4. Komposit-Roststab nach Ziffer 3, wobei der Anguss Gußeisen aufweist.
• 5. Komposit-Roststab nach Ziffer 4, wobei das Gusseisen ein Gusseisen mit Vermiculargraphit oder ein Gusseisen mit Kugelgraphit ist.
• 6. Komposit-Roststab nach einem der vorhergehenden Ziffern, wobei der Anguss zumindest eines von Nickel und Kobalt mit einem Gewichtsanteil von mindestens 2% aufweist.
• 7. Komposit-Roststab nach einem der Ziffern 1 bis 3, wobei der Anguss einen legierten Edelstahl nach DIN EN 10259 und/oder einen Ventilstahl-Legierung nach DIN EN 10090 aufweist.
• 8. Komposit-Roststab nach einem der vorhergehenden Ziffern, wobei der Anguss die Oberseite des Grundkörpers zu mindestens 90% bedeckt.
• 9. Komposit-Roststab nach einem der Ziffern 1 bis 8, wobei der Grundkörper aus einem Stahlblech ausgeformt ist.
• 10. Komposit-Roststab nach Ziffer 9, wobei der Grundkörper ein gebogenes Stahlblech aufweist, wobei gebogene Bereiche des Stahlblechs mindestens einen ersten Übergangsbereich aufweisen, der zwischen der Oberseite und dem wenigstens einen Seitenteil angeordnet ist.
• 11. Komposit-Roststab nach einem der vorhergehenden Ziffern, wobei der Grundkörper Durchgangslöcher aufweist, die mit dem Angussmaterial ausgefüllt sind.
• 12. Komposit-Roststab nach Ziffer 11, wobei sich die Durchgangslöcher senkrecht zu einer Längsrichtung des Grundkörpers erstrecken.
• 13. Feuerungsrost mit einer Anordnung aus einer Vielzahl von Komposit-Roststäben gemäß einem der vorhergehenden Ziffern, wobei zumindest einige der Vielzahl von Komposit-Roststäben mit einem Antrieb des Feuerungsrostes verbunden sind.
• 14. Feuerungsrost nach Ziffer 13, wobei der Feuerungsrost als ein Treppenrost ausgebildet ist, wobei der Treppenrost eine erste Lage aus Roststäben und eine zweite Lage aus Roststäben aufweist, wobei die zweite Lage von Roststäben auf der ersten Lage von Roststäben aufliegt und wobei mindestens die erste Lage von Roststäben aus Komposit-Roststäben gemäß einem der Ziffern 1 bis 12 gebildet ist.
• 15. Feuerungsrost nach Ziffer 13, wobei der Feuerungsrost als ein Walzenrost ausgebildet ist, der mindestens eine erste Rostwalze und eine zweite Rostwalze aufweist, wobei die erste Rostwalze und die zweite Rostwalze jeweils mindestens einen Komposit-Roststab gemäß einem der Ziffern 1 bis 12 aufweisen, und wobei mindestens eine der ersten Rostwalze und der zweiten Rostwalze mit dem Antrieb des Feuerungsrostes verbunden ist.

List of characteristics:

• A composite grate bar for a combustion grate comprising:
• A basic body of a steel alloy which has an upper side and at least one lateral part,
• - A sprue of a cast iron alloy, wherein the sprue at least partially covers an upper side of the body.
• 2. Composite grate bar according to paragraph 1, wherein the sprue is at least partially formed as an encapsulation.
• 3. Composite grate according to item 1 or item 2, wherein the iron alloy for the sprue has a lower tensile strength than the steel alloy of the body.
• 4. Composite grate bar according to item 3, wherein the sprue has cast iron.
• 5. Composite grate bar according to item 4, wherein the cast iron is a vermicular graphite cast iron or a ductile iron cast iron.
• A composite grate bar according to any one of the preceding paragraphs, wherein the sprue has at least one of nickel and cobalt with a weight fraction of at least 2%.
• 7. Composite grate bar according to one of the numbers 1 to 3, wherein the sprue has an alloyed stainless steel according to DIN EN 10259 and / or a valve steel alloy according to DIN EN 10090.
• 8. Composite grate bar according to one of the preceding figures, wherein the sprue covers the top of the body to at least 90%.
• 9. Composite grate bar according to one of the numbers 1 to 8, wherein the base body is formed from a steel sheet.
• 10. Composite grate bar according to item 9, wherein the base body comprises a bent steel sheet, wherein bent portions of the steel sheet have at least a first transition region which is arranged between the upper side and the at least one side part.
• 11. Composite grate bar according to one of the preceding figures, wherein the main body has through holes which are filled with the sprue material.
• 12. Composite grate bar according to item 11, wherein the through holes extend perpendicular to a longitudinal direction of the base body.
• 13. A firing grate comprising an assembly of a plurality of composite grate bars according to any preceding digit, wherein at least some of the plurality of composite grate bars are connected to a drive of the firing grate.
• 14. firing grate according to item 13, wherein the grate is formed as a stair grate, the grate having a first layer of grate bars and a second layer of grate bars, wherein the second layer of grate bars rests on the first layer of grate bars and wherein at least the first Location of grate bars made of composite grate bars according to one of the numbers 1 to 12.
• 15. A firing grate according to item 13, wherein the firing grate is formed as a roller grate having at least a first grate roller and a second grate roller, wherein the first grate roller and the second grate roller each have at least one composite grate bar according to one of the numbers 1 to 12, and wherein at least one of the first grate roller and the second grate roller is connected to the drive of the Feuerungsrostes.

LIST OF REFERENCE NUMBERS

10

body

11

top

12

side panel

13

side panel

14

Suspension Page

15

engagement area

16

Transition area

17

head area

18

engagement area

19

bearing surface

20

lateral projection

21

lateral projection

22

bending area

23

bending area

24

dashed line

25

dashed line

26

axis of symmetry

29

Composite grate bar

30

lower cast area

31

upper cast area

32

head area

33

horizontal area

34

end

35

first rib

36

second rib

37

head area

38

surface area

39

the backstage area

40

horizontal line

50

step

51

step

52

step

53

step

54

step

55

step

61, 61 ', 61' '

mold

62

upper half

63

bottom half

64

Inlet, feeder

65

Alloy, sprue material

66

cavity

67

Through opening

68

neutral fiber

69

fiber elongation

70

upper area

71

lower area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2012/032492 [0081]

Cited non-patent literature

• DIN EN 10259 [0018]
• DIN EN 10090 [0018]
• European standard EN 1563 [0022]
• DIN 1693 [0022]
• European standard EN 1561 [0023]
• DIN 1691 [0023]
• ISO 16112 [0023]
• DIN EN 10259 [0042]
• DIN EN 10259 [0042]
• DIN EN 10090 [0043]
• DIN EN 10259 [0043]

Claims (10)

Composite grate for a combustion grate comprising: A basic body of a steel alloy which has an upper side and at least one lateral part, - A sprue of a cast iron alloy, wherein the sprue at least partially covers an upper side of the body. Composite grate bar according to claim 1, wherein the sprue is at least partially formed as an encapsulation. Composite grate bar according to claim 1 or claim 2, wherein the iron alloy for the sprue has a lower tensile strength than the steel alloy of the body. The composite grate bar of claim 3, wherein the sprue comprises cast iron. A composite grate bar according to claim 4, wherein the cast iron is a vermicular graphite cast iron or a ductile iron cast iron. Composite grate bar according to one of claims 1 to 3, wherein the sprue has an alloyed stainless steel according to DIN EN 10259 and / or a valve steel alloy according to DIN EN 10090. Composite grate bar according to one of claims 1 to 6, wherein the base body is formed from a steel sheet. The composite grate bar according to claim 7, wherein the base body comprises a bent steel sheet, wherein bent portions of the steel sheet have at least a first transition area disposed between the upper surface and the at least one side portion. Composite grate bar according to one of the preceding claims, wherein the base body has through holes which are filled with the sprue material. A firing grate comprising an assembly of a plurality of composite grate bars according to any one of the preceding claims, wherein at least some of the plurality of composite grate bars are connected to a drive of the firing grate.

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