DE1458206A1 - Method and device for compressing metal that solidifies in a casting mold - Google Patents

Description

2.9.1968

For disclosure

Title: .Method and device for compacting metal that solidifies in a casting mold by pressure

iiis is known to be metal when it is cast and used for more or less rapid solidification is brought about by the shrinking process When it cools, it gets cavities, which are kept as liquid as possible until the end of the solidification process by suction Metal from the risers or lost heads no longer filled in can be.

It is also known that these cavities, also called blowholes, can be avoided if the jewel is in liquid or semi-rigid Pressurize the condition * and keep it under constant pressure until it has completely solidified. (Please refer German patent specification 159 118, class 31c, group 26/01, from 18. 2.19o3) · In the process cited in this patent specification, a low, constant pressure is passed through a pipe from a pressurized gas reservoir into the metal-filled and closed mold and maintain this pressure connection during the solidification process.

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Eeraer is published in "Stahl und Eisen", 81 (17.8.1961) 17, page 1146/48, a process known in which steel in a semi-rigid state in pormen, which are cooled with water, on hydraulic presses as long through the upper part of the lorm underneath constant pressure of 6 to 10 kg / mm is kept until solidification of steel is complete. The resulting cast steel is free from voids and grass bubbles, has a very dense structure and higher tensile strength, yield strength, elongation and notched impact strength than rolled material of the same analysis. While the former The process only works with low pressure, which is too low to achieve a structural improvement, are the characteristics of this process occurring pressures are sufficient to improve the structure.

However, this method has the disadvantage that a large number of Presses and chilled molds must be used if one large numbers of castings, around 60 to 120 pieces per hour, are to be produced. The number of presses and molds is increasing also with the wall thickness, the cross-section and the weight of the castings, because these factors determine the solidification time. The effort for the many presses affects the economics of the process.

Furthermore, it is through the German patents 202 271 and 222 011 known, for compacting in a mold to a .Block solidifying metal by pressure, the steel by an outside on the

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Compress mold pressure exerted. This known method results in a block with good material properties, since a considerable external pressure can be used here. The disadvantage of this procedure However, there is a great deal of presses and molds and also in an often complicated structure of the casting molds.

The object of the invention is now to create a method according to which one block can be obtained, the one with greater profitability than those of the known method mentioned, at least the same material properties as one obtained by this method Has block. To this end, the invention is based on a method for compacting metal that solidifies in a casting mold Pressure at which the internal pressure of a gaseous pressure medium pressed into the casting mold when the casting mold is closed by additional Heat supply is increased.

Such a method is known from German patents 3,724, 12 037 and 17 056 and, like another, has it by the German patent specification 159 118 and the Austrian patent specification 191 324 known method in which a gaseous Pressure medium is pressed into the casting mold during the entire solidification process, the advantage that at least the structure of the casting mold is simpler can be. In the known method of this type, the internal pressure of the gaseous pressure medium pressed into the casting mold increased by the fact that the mold is closed. Because of the In addition, the heat content of the metal, which heats the gas, can

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-Φάβη increase the internal pressure of the grass. The level of internal pressure that can be achieved with this known method is, however, lower than the durdi Reducing the mold by means of external pressure achievable. This is why the process has not caught on in practice. Also is. At This process depends on the internal pressure of the gas that can be achieved as a function of the injection pressure and on the temperature of the metal, which is perceived as disadvantageous.

The inventive solution to the task at hand consists in that the internal pressure of the inert grass by electrical, preferably by means of an electric arc, generated heat supply is increased. Although the use of electrical heating means to keep an excess metal mass liquid while the metal is rigid in the Mold is known, the use of electrical heating means to increase the pressure of the injected gas is not known. By using this agent according to the invention, a method which has been known for a long time and is hardly used in practice is improved in such a way that that ee can now be carried out with the same success as other types of processes that pursue the same purpose while avoiding the parts of these other types of process. Essential for this is, among other things, the very rapid heat supply to the enclosed gas, which is why the heat supply by means of an electric arc is preferred.

To secure the cast piece dimensions and to avoid deformation of the cast seams under the internal pressure and to keep it tight

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the forms are according to a further embodiment of the invention for The casting molds used in the method according to the invention are placed under an external preload pressure that exceeds the internal pressure before the internal pressure is generated. This is preferably done by wedging against appropriately strong dumbbells and frames. This corresponding device must be designed so that it operates very quickly can be.

Argan gas is preferably used as the gas, since it does not form any connection with metals or any other substance. Because Due to the high price of the gas, it is preferably used several times. It is circulated through storage and compression systems.

Often there is an interest, the degree of quickness of freezing of the block in advance, or the interest in allowing the block to solidify in a certain direction, for example only from the cylindrical circumference and from the core. This can can be achieved according to a further embodiment of the invention that the mold is covered on individual mold surfaces with molded pieces made of metal and / or refractory metal. For example, are on the Bottom of the mold and immediately after filling the mold on the upper liquid level, molded pieces made of refractory material are placed, like this there is almost no cooling from below and above.

To carry out the method, a pressure vessel without any mechanical means for generating it is therefore preferably used

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or increasing the internal pressure is used. This differs the form according to the invention differs from the expensive forms, which are described in more detail in the above publication in "Stahl und Eisen".

Further details of the invention are the following description as well as the drawing and the claims.

Ss shows

1 shows a vertical longitudinal section through a casting mold according to the invention,

Pig. 2 a half-section H-II of the Pig. 1, Pig. 3 a half-section HI-III of the Pig. 1,

Pig. 4 shows a view of the casting mold after being clamped in a frame shown in section and FIG

Pig. 5 explains the various positions which the devices necessary to carry out the method take in chronological order.

According to Pig. 1 is a base plate 1 on a 2 wheeled base Lower plate 3 set. The base plate has an inner recess 4 into which a filler piece 5 is inserted. The bottom plate also has a cylindrical recess 6 into which the copper inner jacket 7 the mold to be built is set. From the Pig. 2 and 3 is the Fora of the copper inner jacket 7 can be seen. He has four in total Make 8 very thin walls. The resulting recesses in the jacket 7 are filled by wedges 9 approximately triangular Cross-sectional. The inner jacket 7? which forms the eggs of the mold;

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θ is based on a core support 10, made of steel. There are cooling elements in it 11 used with holes for the cooling water, which have connection to a cooling water line 12 in the lower plate 5 and at 15 ins Free flow. The eggs 7 are cylindrical on the outside, but conical on the inside, the core support 10 having a correspondingly conical shape. the The outer wall of the casting mold is formed by a two-part copper wall 14 with butt joints 15 The copper wall is cylindrical inside and out and is supported against a two-part steel jacket 16, whose ropes collide at the butt joint 17, whose flanges 18 are held together by means of screws 19. The steel jacket 16 is provided with cooling elements 20, with holes for the cooling water, which find a continuation in the channels 21 of the base plate 1 and at 22 open into the open. Cooling water or wet steam can be introduced and discharged through them. The outer wall of the two-part steel jacket 16 is conical and is encompassed by an internally conical door tensioning ring 23 which, when pressed down, forms the steel moldings 16 and the copper moldings 14 presses together.

The form is closed by a lid 24 »which is closed with a Filler piece 25 is placed on the core jacket 7 and also receives the upper edge of the outer mold wall 14 * 16 in an annular groove 24a. One Bore 26 with an Ans cliluß in front of device 27 enables the pressing Clay gas in the cavity of the mold. A bore 28 with an outlet valve 29 enables the gas, which is under maximum tension, to be released from the mold. Hit 50 is a pressure gauge labeled and 51 a safety valve which opens the channel 31a as soon as the

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Pressure in the casting mold overshoots a certain amount. Sine electric Heating device 32, which is set up, for example, as a heating coil, filament or arc for capacitor discharge, has a electrical supply via channel 33a at 33.

The corners 34 indicated in black mean sighting rings or; Sealing material. With 58 and 59 are heat-insulating panels E.g. made of ceramic material.

The parts 7 and 14 can also consist of a material other than copper, but it should have good thermal conductivity. On the ropes is preferable a wear protection film made of refractory metal oxides is applied. The core of the mold, consisting of the copper part 7 and of the steel core support 10 is so strong that it absorbs the hydrostatic pressure of the liquid or solidifying metal can accommodate, which corresponds to the increase in pressure of the high pressure gas in the mold. In addition, he must reduce the shrinkage pressure of the solidifying Withstand metal. The cone angles are chosen in each case so that the parts sliding on each other are self-locking.

Look the Pig. 5 »Figure a to s, the course of the invention is now Procedure outlined.

On the base plate 1, which rests on the movable lower plate 3, the core 7,10 is first placed with the help of a crane; see.

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Figure a. Then the outer shape 14 * 16 is placed on the base plate 1, Fig. B. Then the ionic YgrspaTmring 23 is pushed onto the steel jacket 16, Bi ^, d, e., Then the bottom plate 3 moves in a press 35 * by which the door clamping ring 23 is pressed down. The casting mold is then filled with a precisely measured amount of metal, as shown in Figure e. As soon as possible after the end of the pouring, the cover 24 is put on, Figure f. The mobile bottom plate 3 now rolls into a frame 36, the two frame members of which are held together at the bottom by a frame plate 37. The frame 36 stands on a frame wall 38; Daily I ¹ Ig. 4 and image g of FIG. 5. The frame carriage 38 can be moved so deep in a recess 39 of the workshop floor that the rails 40 carried by it are aligned with rails 41 lying on the .Werkstattflur_ 42, so that _r the movable lower plate 3 without further it. can be pushed into the frame 36. In. In this position, a press 43 suspended from the crane moves over the frame 36 and presses a wedge 44 between ... the cover and a counter wedge 45? -the © it to the frame .36 is firmly connected, the cover 24 is thereby firmly on, the mold is pressed on, ^ r etz is through the inlet valve 2.7 argon gas from a bottle 46 into the cavity between the plate 58 and the cover 24 passed. After closing the Sinaassyen ^ lJ ^ L 27 ^ he ^. ., Earusell 47, image h. On this K ^ u ^ el ^ ^ nno several, J ^ wenwa ^ eai find places at the same time; because the frame wagons should remain on the carousel until. the argon ^ s, the witched and thus the desired, Druci: - e ^ hold :; haifc _f; . ejitw ^ jaier heat transfer from the melt material or through a special above

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imagined electrical heating and until the semolina has solidified under this pressure. After completion of this doorway · the argon gas is released and. caught. · The. Frame wagon. 38 drives about, on the opposite side of the carousel. 47 down under another press .48, - image!, The; the rope 44 drives out again. Then the mobile bottom plate 3 moves back onto the plur 42, where the casting mold cover 24 is lifted with the aid of a crane. * The frame carriage 3 & returns to the carousel. Then the fsh bare; Base plate 3 under a press 49 (Figure 1), which pushes the press ring 23 from below, while the steel jacket. 16 together with copper jacket. 14 are held from above *. ■ _ ......

According to Figure m, the press ring 23 is lifted up and returns in circulation. Picture c back. The mold core 7 * 10 is then removed quickly, as this is under the constantly growing shrinkage tension of the cooled hollow casting material:.; -to enable the removal of the core, according to Figure η der.Oßenmantel 1 mit. the base plate. 1, -the at 50 (lig. ·. 1) screwed to it. is lifted and raised by a crane. a bumper car 51> ^ set, picture .o. This takes up the base plate 1. and has an inner opening 52 * into which the core support, through the press, 55. ,: uniter which "the ejection carriage 51 is pushed * is ejected downwards ^ ,; :; Picture p. Here, of course, there is an additional support for the ejector carriage 5t. s & inen rags, -54 necessary. Jfachdem according to _; rBjiJd-; the, core support .1.0 downward .- ^ usi-dem-Eupf enasantelr.7 herstusgesrteS ¹ ^? is, the latter no longer has a firm seat in the block, since it is the thin

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has flexible ropes 8 (see. Fig. 2) and the wedges 9 after Pull out the core support 10 immediately fall through by itself. If the jacket 7 is also ejected downwards with the aid of the press 53, Thus, by means of a crane, see Fig. q., the outer jacket 16 can be lifted upwards, with the cast block together with the base plate follows. According to picture r, the mold core 10.7 is lifted out of the ejection carriage 51. The outer jacket 14 »16 with base plate 1 is now placed on a lower plate 3 again. By means of expanding pliers which engage in the inner cavity of the cast block the ingot pulled out of the mold 14 »16. That is without difficulty possible because the cast material has shrunk in the meantime. All parts are now ready for a new use.

The time required to heat the argon gas is generally only a few seconds. The duration of the solidification of a block with a block length of 850 mm with a temperature drop from 1350 to about 1250 ⁰ O, an outer diameter of 250 mm and an inner diameter of 100 mm, on the other hand, is, for example. 60 to 80 seconds · Due to the above-mentioned attachment of cool metal or ceramic inserts 58. the time for the pressure development, ie for the heating of the argon gas, of ex. 2 seconds can be increased to about 50 seconds. - -

The cooling of the molded parts is continued during the entire operation - ^r according to Fig. 5 _r image e to s, preferably continuously, "-so-

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that the molded parts are quickly ready for new use. At least the cooling is continued until the solidified but still very hot casting metal has been removed from the mold. I ¹ For smooth work, it is of course desirable that the argon gas according to Pig. 5, Fig. G, is always fed with the same pressure. If the argon gas is stored in a cylinder battery, the goal is achieved by interposing a conventional pressure reducing valve.

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Claims (9)

s 1588 For Disclosure. Pstent claims P 14 58 206.0 1. The process of densifying metal solidifying in a casting mold by means of pressure, in which the internal pressure of a gaseous X & ruckmediTEas pressed into the casting mold is increased by additional heat supply when the mold is closed, characterized in that the internal pressure of the inert gas is increased electrically, preferably by means of an electric arc. generated heat input is increased. 2 »Method according to claim 1, characterized in that the desired pressure during the solidification process is on the preselected. Height is kept constant. 5. Method according to claim 1, characterized in that before the internal pressure is increased, the casting mold is placed under an external, known gate pressure which exceeds the increased line pressure. 4-. Method according to claim 5 *, characterized in that the gate tension is pressed onto the casting mold in a manner known per se by wedging while utilizing the self-locking of ropes. -Z- OFMGlNAL IMSPECTED _COP y 80981t / 051T -; .... 5. The method according to one of claims t to 4 » characterized « in that the thermal conductivity of the casting mold is modified * 6. Casting mold for the production of cylindrical castings according to the Yerfahren according to any one of claims 1 to 5, characterized in that it consists of inner, thin-walled, multi-part, mutually sealing or sealed moldings (14), which by a thick-walled, also multi-part and, zxtsammeüsehraubbaren »with water or barrel steam cooled, externally conical jacket (16) are held together by means of an outer, internally conical pretensioning ring (25) known per se, and that they are held together by a base plate (1) sealed against the inner mold parts and a cover (1) sealing the casting mold 24) is lockable. 7. Casting mold according to claim 6, characterized in that it is covered on individual inner surfaces with molded pieces (58, 59) made of cold metal and / or refractory material. 8. Casting mold for the production of hollow cylindrical castings according to claim 5 or 6, characterized in that it has a coolable, hollow core (7) which consists of thin-walled »multi-part, mutually supporting moldings which form a self-locking conical tube on its inside and are supported from the inside by a one-piece, self-locking, oppositely conical, cooled, strong core support (10). -3- 809811/0517 9. The method according to claims 1 to 4 using casting molds according to claim 5 to 8, characterized in that an internally conical Torspannring (23) is pressed under a press on the outer mold (14 »16), after the subsequent filling of the semolina mold the cover (24) is put on and the overall shape is pushed into a frame (36,37) and in this the cover is wedged against the frame upper part by horizontal ropes, that argon gas is then passed into the tree under the cover and after being heated by the melted material and a additional electric arc heating is released to the desired temperature and pressure, whereupon the cover is lifted off after the Eeile has been ejected and the door tensioning ring is lifted under a press (49). 80 9 811/0517