DE2717068A1 - METHOD FOR REPAIRING DAMAGED HANDLING PROJECTS OF CHILLERS - Google Patents

Description

. "- Ά '. EL ί \!" · A N ■ VÄ LT E

A. GRUNECKER

DCPL ING

H. KINKELDEY

or-: ng

W. STOCKMAIR

DR-ING Atft (CALTEOt

K SCHUMANN

DR HER. NAT UITl. fWS

P. H. JAKOB

DIHL-IMG

G. BEZOLD

DR RCR NAT. I.

8 MUNICH 22

MAXIMILIANSTRASSE 43

USS Engineers and Consultants, Inc.

600 Grant Street Pittsburgh, Pennsylvania 15230

P 11

April 18, 1977

Method for repairing damaged handling projections of molds

The present invention relates to repairing damaged mold handling protrusions.

In general, casting molds are provided with projections which cooperate with rim tongs in order to handle the molds to allow. These projections, sometimes also known as "ears", protrude from the mold body and are therefore exposed to the risk of damage. In addition, new molds in the casting pit or foundry can be damaged because they are cast with insufficient projections or the projections are damaged in the course of foundry operations became. In any case, however, an unusable mold projection must be repaired when the mold does not have to be taken out of service. Albeit already

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various repair methods for mold handling protrusions These are well-known processes So far too expensive and / or not feasible the repair costs, for example, approach or even exceed those costs that result from the production costs minus the scrap value of a specific mold. Otherwise, the repair process may also stop using require of special materials, such as a rapid supply of coke oven gas for preheating purposes, being in addition or, alternatively, the use of specialist staff is also required. Because of these difficulties with known In Measures for Repairing Projections, repairing such projections is not widely used. This has the consequence that many molds, which are otherwise in a perfectly ready-to-use condition, are prematurely discarded or discarded because they have damaged protrusions.

The inventive method for repairing damaged mold handling projections is characterized in that the mold is placed on one of its sides in such a way that the damaged protrusion to be repaired comes to rest on top, that a refractory enclosure is placed around the damaged projection so that the inner surface of the refractory enclosure the boundary of the desired projection defines that a corpuscular refractory material within the refractory enclosure against an area of the existing projection that is not in need of repair is introduced that within the refractory enclosure in the area of the damaged surface of the existing projection a recess or cavity is formed that an aluminothermic reaction mixture in the of the Refractory enclosure formed cavity introduced and arranged above the corpuscular refractory material is that the reaction mixture is ignited to within

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the refractory enclosure is molten iron and molten. Produce slag that the high-viscosity Metal and slag phases are allowed to separate such that the metal phase is damaged at the bottom Area of the existing protrusion settles, while the slag phase over and above the corpuscular Refractory material forms that the two molten Phases are allowed to cool and solidify and that the refractory enclosure, the corpuscular refractory material and removing the solidified slag to expose the repaired protrusion.

A preferred concept resides in a method of repairing damaged mold handling protrusions, in which a refractory enclosure placed around the damaged protrusion and sand is deposited against the undamaged surfaces of the existing protrusion, thereby in the area a cavity or a Pormraum is formed on the damaged surface of the projection. An aluminothermic reaction mixture is then introduced into the enclosure and ignited, which causes a metal melt that the mold space fills and solidifies in it. Finally, the refractory enclosure, the sand and the reaction product formed slag is removed, whereupon the aluminothermically deposited metal is shaped in the desired manner.

Further features, advantages and details of the invention emerge from the following description of an exemplary embodiment with reference to the drawing, which shows a section through a section of the mold wall along with the necessary equipment and materials for Represents implementation of the procedure.

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In the preferred embodiment of the method according to the invention, a damaged projection is used Mold laid on its side so that the damaged protrusion is on top. The drawing is in section a section of the mold wall 10 and the damaged projection 12 can be seen. A typical mold handling protrusion has an inclined surface which, as shown in the drawing, extends from the upper end of the mold wall extends to a downwardly projecting elevation which can be gripped by the tongs of a crane. In which The projection 12 shown in the drawing is the increase (praise) canceled.

Before performing the repair, remove any large protrusions immediately adjacent to the damaged protrusion 12 are present, removed by grinding or the like. Grounding in order to arrange and seal the device described below to facilitate. Ideally, the mold should be arranged so that the mold wall 10 runs in the plane. Slight inclinations from end to end and / or from side to side of the mold can be tolerated up to about 10 °.

Once the mold has been arranged in the desired manner and has been cleaned of protrusions and foreign matter, a rectangular refractory enclosure is placed around the damaged protrusion 12. This enclosure serves primarily as a container for an aluminothermic (ASR) mixture and then also as a mold for the molten product of the aluminothermic reaction. The enclosure consists of two boxes with open bottoms, which are preferably made of graphite plates. One box, namely the inner enclosure 14 *, preferably consists of 50-8 mm thick graphite plates, the internal dimensions of which are selected so that they fit around the largest conventional projections, the

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Dimensions are typically 31.2 χ 4-2.1 cm.

An adaptation can be made to shorter and / or narrower projections by simply pulling out slide-in plates Graphite can be inserted along the inside walls and / or end walls of the box. The height of the inner Enclosure 14 is chosen to be large enough to accommodate the required Can absorb amount of reaction mixture. A height of 16 inches for the enclosure is for most Cases enough to accommodate the batch. To simplify handling, however, it is preferred that stack two enclosures 8 inches (8 inches) high on top of each other. In the usual case where even larger batches are needed, which is close to replacing a full projection, three or even four enclosures are placed on top of each other. The walls of the enclosure 14 are preferably with the help of for example screws and / or angle irons held together.

The other box, namely the outer enclosure 16, consists of 25.4 mm thick and 27.9 cm high graphite plates, wherein the dimensions are chosen so that the inner enclosure 14 is encircled with excess, so that between the inner enclosure 14 and the outer enclosure 16 a 76.7 mm wide gap 18 is given. The gap 18 between the boxes are filled with a dry corpiscular refractory material 20 such as sand. The 27.9 cm high outer enclosure 16 is sufficiently high to permit use of a 16 inch high inner enclosure 14. If a higher inner enclosure is required, one or more additional outer enclosures can be used stacked on top of the first outer enclosure. Finally, a graphite plate provided with an opening 22 is used

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used as a cover 24, the hole 22 penetrating the cover approximately in its center. The cover 24 must be sufficient be long to rest on the shorter walls of the inner enclosure 14. The cover 24 serves the purpose of providing heat and to keep the splashing around as little as possible during the course of the aluminothermic reaction.

It will be understood that the enclosures 14 and 16 are sufficiently sealed to prevent leakage. Before the arrangement of the enclosures, the inner enclosure 14 is therefore first turned over in a preferred manner and becomes a layer a high-temperature mortar applied to the bottom surfaces of the enclosing walls. The enclosure 14 is then raised, brought back into its upright position, arranged around the projection 12 and then pressed on, to squeeze out any excess mortar. Any excess mortar will then be removed from the inside of the enclosure removed. The enclosure 14 is positioned so that one end wall of the enclosure is intact with the tapered End of protrusion 12 is in alignment, with protrusion 12 in enclosure 14 in terms of size centered from side to side. Any gaps remaining between the enclosure 14 and the mold surface are then closed if necessary by applying additional mortar. Some molds are designed so that conical end of the projection coincides with the end of the mold. In this case, only touches the inner surface of the Enclosing end wall the mold. This connection must be sealed by means of a mortar layer.

The inner enclosure is preferably designed to fit snugly against the sides of a 11 inch wide projection. If 25.4 cm wide protrusions are repaired, so will

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Inserted two 25.4 mm thick graphite plates not shown, a plate being placed on each side of the protrusion. If 20.3 cm wide protrusions are being repaired, 50.8 mm thick graphite plates are inserted in this way. Instead of the inserted side panels, it is possible to arrange the main enclosure so that one of the long enclosing walls is well on one side of the projection is applied so that the enclosure is not centered on the projection. The graphite plates are then in the required number and thickness in the gap between the other side of the protrusion and the other long Graphite wall inserted. The length of the slide-in parts should be about 12.5 mm shorter than the inside length of the Main enclosure to ensure easy insertion this way. After the bottom edges of the slide-in parts smeared with mortar, they are simply pressed into place. All large gaps between the ends of the Inserts and the walls of the main enclosure are filled with mortar.

The number and size of the required end slide-in parts depends on the length of the projection. Usually, a minimum of about 25.4 mm of metal should be at the machining end of a Projections are added in addition to the metal required to restore the projection. Thus, for a 42.1 cm long protrusion, the inside length of the enclosure should be 48.2 cm, with a 50.8mm thick end insert is used to close the inside Reduce the length of the main enclosure to this length. Correspondingly, when repairing a 35.5 cm long projection, the inside length should be 40.6 cm, so that two 50.8 mm thick insert parts and one 25.4 mm thick Insert part are required. In a case in which both side and end slots are required,

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the end inserts should be installed first because the side inserts exert pressure on the end inserts and provided that the courtesy is that the same in the repair area fall into it. The end inserts are installed in the same way as the side inserts with the The difference is that it takes some effort to avoid introducing large quantities of mortar into the repair area. That This is because the presence of larger quantities of mortar can adversely affect the repair.

If necessary, an extension of the inner enclosure is made 14- used. After the bottom edges of a comparable enclosure 14-A have been coated with mortar, the enclosure is simply placed on the upper edge of the first enclosure 14- and fastened in place by pressure. Any remaining gaps between the enclosures will then be sealed with the help of additional mortar. Additional slide-in parts are not required because the purpose of the second enclosure 14-A is only to provide a sufficient To provide volume for taking up the aluminothermic reaction mixture. The shape of the spiked Enclosure is given by the lower enclosure. Has the batch calculation shown that a weight of more than 100 kg Batch is needed, so a third 8 "high inner Enclosure can be used, which is placed on top of the first two sections. Occasionally it can even use a fourth containment section may be advantageous in order to avoid material loss during the reaction when "boiling over" to avoid.

As already mentioned, the outer enclosure 16 is dimensioned so that it encloses the inner enclosure 14 while leaving a 76.2 mm wide gap between the two enclosures.

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leaves that with dry sand or a corpuscular refractory material 18 is to be filled. Although the requirements for the outer enclosure 16 are by no means so high, such as the requirements placed on the inner enclosure 14, so the outer enclosure 16 must nevertheless be tightly sealed against the mold surface in order to prevent it from flowing out to avoid loose sand.

Because the bottom edges of the outer enclosure work well with the Columns whether they have to close off surfaces that are not flat, vüede the use of an enclosure with flat or straight lines Bottom edges lead to the formation of large gaps. Accordingly, the bottom edge is an end enclosure wall designed so that its contour corresponds to the curvature of most mold surfaces. It goes without saying that it can only be an approximate match. The side walls are generally sufficient well on the mold surface, which is why no contouring is required there. The seat of the remaining end enclosure wall is usually more difficult. As previously described, the outer surface is one of the inner containment end walls either substantially flush with the top of the mold or about 50.8 mm above the top The end of the Kokillenwandting 10 also dimensioned. By a 76.2 mm To form a wide gap 20 at this end, it is necessary to have a bottom in the outer casing at this point to insert. For this purpose, a 25.4 mm thick graphite plate 26 is attached to the underside of the enclosure 16. the Plate 26 spans the width of outer enclosure 16.

After the outer enclosure 16 has been neatly aligned, the enclosure is sealed against the mold with the aid of layers or beads of mortar, the mortar between the bottom edges of the enclosure and the mold

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surface is introduced. If necessary, any large gaps can be made between the enclosure and the mold surface before applying the mortar with steel washers or the like. Then sand or another corpuscular refractory material 20 is in the Gap 18 is filled. Contact between the molten, superheated reaction products of the aluminothermic reaction with easily vaporizable substances such as water lead to violent results. For this reason the enclosure should be dried before use. To this Purpose, a burning or drying process can be carried out with the help of a natural gas burner. Usually the inner enclosure 16 baked or dried for about 30 minutes. The outer enclosure 18 is then baked for about 15 minutes. Finally, the inner enclosure 16 reburned for an additional 15 minutes.

If a whole or almost a whole projection is to be replaced, then there is no additional machining of the inner enclosure 16 necessary. However, only a section or part of a projection needs to be replaced, as shown in the drawing As illustrated, some devices must be used to keep the deposited metal from moving to collect at the undamaged conical end of the projection 12. All metal that is attached to the conical protrusion end is wasted and must be burned away. To prevent this, a particulate refractory material, like sand 30, poured on the tip of the conical protrusion end, until the sand level or the sand level approximately with the thickest section of the undamaged area of the projection 12 is aligned. Care should be taken to prevent sand from accumulating on the damaged projection surface.

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After all, there is a single mold cavity within the Enclosure 14 formed, which on three sides of the walls of the enclosure 14 and enclosed on the fourth side by the damaged surface of the projection 12 is. In some cases it can be beneficial to not one To use the refractory insert shown, which bridges the width of the inner enclosure and as a sand barrier serves. This sand barrier allows sand 30 to be poured to a greater height without the risk of that sand collects on the damaged surface of the protrusion.

The weight of the amount of aluminothermic needed for the repair The reaction mixture must be calculated with an estimate of the required metal volume, which must be taken into account is that about 0.5 kg of batch results in about 32.7 car of metal. This calculation or estimate should be made liberally, as superfluous material can be removed, but missing material Material can only be added by repeating the process. The calculated amount of aluminothermic reaction mixture 32 is then introduced into the enclosure 14, leaving the mold space in the area of the damaged protrusion fills and of course the sand filling 30 is superimposed. the aluminothermic reaction mixture 32 typically consists from a stoichiometric mixture of granulated iron oxide and aluminum.

The cover 24, which consists of a graphite plate, is then placed on top of the inner enclosure 14. One special ignition device can be built into the lid using the following procedure: a small piece Aluminum foil is pressed into the ignition opening 22 in the cover 24, to form a small cup. The prepared beaker is then filled with reaction mixture and a small amount ignition mix is then added to the top of the batch

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dripped. Such an ignition mixture typically consists of 90% barium peroxide and τ / Ό aluminum. The ignition nucleus is easily ignited on contact with a fusee flame. This reaction in turn initiates the ignition of the charge material in the aluminum cup. When the charge contained in the cup burns through the cup, the hot reaction products fall onto the top of the main charge, igniting the same will.

Once there is the aluminothermic reaction mixture 32 ignited, its burn gradually increases in intensity, with peak intensity after about 30 seconds or less is reached. Occasionally some of the overheated molten liquid reaction products of the aluminothermic The reaction will boil out over the top of the enclosure and be lost. This can occur especially when large batches are implemented. In general, however, the loss of material due to overcooking is negligible, but it can also be completely eliminated, as previously mentioned, by placing a sufficient number of containment sections on top of one another will use. Ideally, the inner containment should be approximately three inches above the batch surface extend.

After ignition of the aluminothermic reaction mixture 32 the assembly remains undisturbed until it has cooled sufficiently to permit work on it. Usually it is pleasant to let the arrangement cool down overnight. However, such a long downtime cannot be tolerated the assembly can be baixed apart after about 1 hour, provided the workers are using heat-resistant Safety equipment are provided.

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The outer enclosure 16 is first removed, from proceeding from top to bottom. The sections are simply separated from each other and then from the mold surface removed and raised above the inner containment sections. The sand JO is used during the mining of the outer U) Dclosure run out of the gap 18 between the enclosures. During the dismantling of the outer enclosure, care must be taken that the outer enclosure sections with Care should be taken to avoid damaging these sections.

Next, the graphite lid 24 is removed and the inner containment sections are dismantled one at a time, with : ait of the top section is started. The enclosures are separated from each other by gently pulling the connections is vibrated between the enclosing elements. Again, care must be taken to avoid serious damage to prevent the enclosures or the elements. The bottom portion of enclosure 14 that is the main weight the reaction products can usually not simply be removed from the mold surface. As a result Preferably, the containment section is partially disassembled prior to removal. By loosening a few screws, for example the enclosure can be divided into two L-shaped halves that can be easily removed. The enclosure is then put together by simply screwing in the screws again. The containment sections are then used for Prepare for the next repair operation by simply removing all excess mortar from the surfaces which form sealing surfaces with other enclosing elements and / or with the mold surfaces. Also be removes all reaction products of the aluminothermic reaction that adhere to the inner walls of the enclosure. All large cracks and crevices that are in the enclosing

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elements formed during the repair process are closed with Nortel.

The schiacken phase deposited on top of the deposited metal the aluminothermic reaction can usually with the help of a Meiseis or the like. At the junction between the slag phase and the top surface of the deposited metal are removed. Usually the slag goes in one big piece. In some cases, the slag phase can adhere firmly, making it necessary will work the edges of the slag phase with a hammer to induce loosening and / or attack To create a gap to pry open.

The top surface of the deposited metal is usually quite rough and can contain pieces of invaded slag contain. It is not necessary to meticulously remove all slag, as the presence of slag residues does not has an adverse effect on the operational properties of the repaired projection.

If necessary, the repaired projection is then subjected to processing in order to give it its original shape and configuration restore normal lead. This process does not need to be carried out with the greatest care and should essentially be limited to restoring the machining end of a protrusion and excess To remove metal, which could interfere with a good interaction between the projection and the rim clamps. Since the composition of the deposited metal is more like that of steel than that of molten iron, For example, the protrusion can be machined quickly and easily using a conventional cutting torch. In some The repaired lead can also be in the unprocessed situations

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State, i.e. can be used without subsequent treatment or shaping.

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Claims (4)

ι tL N VAN vVÄLTE A. GRÜMECKER OlPl -ING H. KINKELD ^ / t «ING OT Λ Π nC O W. STOCKMAIR £ / I / \ JQQ DRItJG MCAllFil K. SCHUMANN DR OEK ΝΛΤ ■ CjcPL-FMySL PH JAKOB Olrt_-ING G. BKZOLD on fcjn NAr ■ MPi. c> cm 8 MUNICH 22 MAXIMILIANSTRAS & E «3 P 11 512- claims 1. Procedure for repairing damaged haridhabuiigs protrusions of ingot molds, in which a batch of an aluminothermic Reaction mixture is ignited above the damaged surface in such a way that iron is removed from the melt flow on the damaged surface Surface settles, characterized that around the damaged projection (12) a refractory enclosure (14) is formed, that a corpxiskulares Refractory material introduced into the refractory enclosure in contact with an undamaged surface of the projection (12) and that the aluminothermic reaction mixture on the corpuscular refractory and on the damaged one Surface is arranged. 2. The method according to claim 1, characterized in that the refractory enclosure (14) opposite the The mold is sealed with the help of high-temperature mortar. 809808/0581 TELEPHONE (O6O) 39 38 02 TELEX Οβ-ϋΒ3βΟ TELEGRAMS MONAPAT TEIEKOPICRER ORIGINAL INSPECTED 3. The method according to claim 1 or 2, characterized in that around the inner enclosure (14-) an outer enclosure (16) is formed and that a corpuscular refractory material (18) in the gap between the inner enclosure and the outer enclosure. 4. The method according to any one of claims 1 to 3, characterized in that a cover (24) over the inner Enclosure (14) is placed and that the reaction mixture (32) ignited through an opening (22) formed in the cover will - 809808/0581