DE2035251A1 - Process for the production of Vorma tenal uniform cross-section from Me tall, in particular steel - Google Patents

Description

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Essen, July 14th PZ 2024

Patent application:

"Process for the production of primary material with a uniform cross-section from metal, in particular steel ¹ Applicant: Rheinstahl Gießerei AG, Mülheim (Ruhr)

The production of many rotationally symmetrical parts, such as rings, railway wheels, gastric tires or containers or pipes on bumpers is partially or fully automated and therefore requires starting material with a uniform piece weight and a uniform cross-section .. ^;

It is known to produce such molding material; by casting the steel in conical molds, rolling or forging the resulting | conical block to ensure a uniform! Obtain a cross-section with a good surface finish and then divide the deformed block into sections of equal length. Bieses known method provides though proper ¥ armaterial ,, which is to be further processed well because of the same cross-sections and the 'because of the .gleichen cross sections by dividing it into sections of equal length slightly in ¥ oxmaterial same) ¹ weight to be divided; However, it is disadvantageous that the cast block has to be subjected to additional testing.

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It is also known to cast conical large blocks and these blocks without further deformation; to be used after division into pieces of equal weight for further processing in ring rolling mills. The technical part of this procedure consists in the fact that the sections are different because of the different. Must be cut cross-section of different lengths and required constant weight is difficult maintainable r. In addition, the Efinisatz in semi- or fully automatic systems often excludes a different cross-section of the material. Besides deta

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is known to single blocks too. pour and without further Division ^ or deformation for the manufacture of a rifle

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to add. 'This procedure is [generally un ™

I economical, since the effort beijjsm pouring ,, -cleaning and transport higher and the spreading, less favorable

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than with the angblock (Stahl and [Elsen 79 (1959) P. 1913

Based on this state of the Teelteik, the task of the invention is added ,,! At ¥ © reaterial _f at the e # for the partially full .. ^: ;; d'der fealbautoraati running further processing, such as rolling in a ring rolling mill or Ämf ^ rtigamg won pipes or containers on a push bench: d! araaiif ankosrait that the raw material had the same weight for the same garage and also uniform middle of the individual. Pieces has: this imme walkende o-der '-schmiedende deformation in, eSjss & e die _; aseiestorupg ^ free; Further processing safetelleMert, "'QEiiaiitat ζω he ,,'

In a process for the production of primary material Uniform piece weight and cross-section made of steel, especially for ring or tube rolling mills, this object is achieved according to the invention in that the primary material by casting blocks with constant cross-section over their total length while avoiding the usability impairing Grooves or elevations over the circumference in standing molds and by dividing the blocks into equal lengths Sections is made.

Furthermore, the invention can advantageously be configured as follows be.

For the casting of blocks with a round or polygonal cross-section with a diameter of 200 to 350 mm, the invention recommends casting as cold as possible with rising speeds of 30 to 80 cm per minute and uncovered surface of the melt in the mold. Care must be taken that the inlet into the mold is exactly centered. In the case of blocks with larger diameters of more than 300 mm, the surface of the melt in the mold is covered with heat-insulating powder and poured centrally, rising as cold as possible, at rates of rise between 10 and 30 cm / min. Due to the rather slow pouring, a uniform solidification from the block base to the block head is achieved with significantly smaller differences in concentration due to segregation between the base and head of the blocks than with the known 109884/0889

conical blocks. In addition, the slow pour allows the use of a smaller hood for sealed feeding of the block and improves the yield.

In a process for the production of primary material, in which the melt is subjected to the application of gas pressure is conveyed onto its surface from below into the standing mold, a fast mold filling is achieved with the possibility of cold casting, which leads to a uniform solidification with little segregation leads.

To carry out the method, the invention recommends a mold made of carbon-rich iron, in particular Hematite, the inner cross-section of which is the same over its entire length, and which is undivided in the axial direction whose length is greater than 2 m and whose clear width is greater than 250 mm. The mold draws are characterized by the fact that their weight is at least 1.3 times the weight of the block. The mold weight depends on the block diameter, the weight ratio with decreasing diameter up to rises above 3.

The known molds are generally designed to be conical in order to allow the solidified blocks to be stripped to facilitate. You also have a heavy block shape with a weight of 114 t and a length of 5.20 m entire length made of the same cross-section, since one

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dacpclt calculated that the blocks to be cast would, owing to their large diameter, shrink sufficiently to. pulled out of the iron mold even without tapering

to
can be (Stahl und Eisen 1922, p. 653). About the behavior - this mold at. Font has nothing been reported to I. In "Stahl und Eisen" 1931 on page 1225, left column, it is stated that the smallest possible conicity should be aimed for for the shape that widens downwards. A taper of 1.3 down to ^! 0 * 7 is considered sufficient to eliminate difficulty; to avoid during the stripping work. It would currently s even repeated experiments with parallel-walled molds. In addition, in the case of molds with the same cross-section over their entire length, the removal of the; cast block made possible by longitudinal division of the molds (e.g. DBF 95 515, DBP 67 035). Longitudinally divided molds of this type make it easier to remove the blocks, but they easily lead to elevations on the block (ridge) due to the inflow of the liquid metal during casting. This mistake is made by the material cast in longitudinally divided molds. Can only be used as a starting material for further processing to a limited extent or only after considerable cleaning work, since it can easily lead to cracking or overrolling at these points when upsetting, stretching and rolling in the axial direction. Furthermore, divided molds, especially in the case of long blocks, are unfavorable because of the sensitivity to distortion and the difficulty of sealing the separating point during casting. The high sensitivity to cracks poured in the conventional way

109884/0889 _ _{6 m}

Blocks with circular versus those with polygonal Cross-section or corrugated surface and that of blocks with the same cross-section over the length Expected difficulties in stripping have so far resulted in no long blocks with over the length of the same, in particular round, cross-section can be cast. Experiments by the applicant have shown that in the case of molds which are undivided in the axial direction and have the same cross-section over their entire length, they are free of cracks Blocks can be cast without difficulty, even without machining the inner mold surfaces can be stripped if the mold weight is at least 1.3 times the block weight. A lower ratio of the mold weight to the ingot weight, i.e. a lower mold wall thickness, resulted in cracking and, as a result of distortion, difficulties in stripping. Compliance with the above Casting conditions have proven to be advantageous.

The influence of the mold weight on the formation of Cracking was not expected for the following reasons. Have an influence on the crack formation; except the geometric ones Conditions of block form; the steel composition, the casting temperature and the rate of rise mainly the cooling conditions. the The former influencing variables are not influenced by the weight of the mold. This only has an influence on the cooling conditions mentioned last,

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however, at such a late point in time that any Effect on the crack formation is not understandable. After calculations of the time course of the temperature indentation curves in ingot molds, which have been confirmed in their qualitative course by experimental investigations (Stahl and Eisen 1943 p. 204) occurs immediately after liquid steel has been poured into a hematite mold, a temperature on its inner wall from around 1000 C to, e.g. when pouring a 5 t block in a square mold of the same weight with a wall thickness of around 12 cm, the heat would be if the inner wall the mold is kept constant at 1000 C, penetrate to the outside in around 6 min and the temperature there increase by around 70 C. If the mold weight were increased to one and a half times the block weight - that would correspond to a mold wall thickness of 17 cm - would be the outer wall temperature at this point the mold has not yet increased. At a distance of 12 cm from the inner mold wall would be the However, in this case too, the temperature after 6 minutes is around 70 C. For the temperature gradient on the inner wall the mold, which apart from the heat transfer conditions that cannot be influenced by the mold weight from Block to the mold wall alone is decisive for the amount of heat per unit of time from the surface of the solidifying block are transported away into the mold, so there is no change through the increase in the mold weight has come. One would have to therefore assume that 6 minutes after the start of solidification

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of the cast ingot in the ingot with a weight equal to the ingot weight, the same conditions should prevail as in a ingot with one and a half times the ingot weight. At this point in time, however, according to the rough formula, D = 2.5 χ k χ | / t - with D = solidified thickness in cm, k between 0.9 and 1.22 and t time in minutes - (Basic Open Hearth Steelmaking, 1964 , Page 437) about 6 cm of steel has already solidified. If one also takes into account that the formation of the air gap by the lifting of the block when it is contracted makes the heat transfer more difficult after about 1 minute, and that the influence on the gradient also at later times, when the mold wall has already noticeably increased in temperature on the inner mold wall is extremely small, it is not clear how the mold weight should influence the heat dissipation from the block at such a point in time when the solidified layer is still so thin that it is still prone to cracking, for example as a result of internal pressure could be. Experiments by the applicant have shown that despite these theoretical concerns by the inventive increase in the mold weight over the known with over the entire length of the same cross-section completely crack-free blocks he could be generated, which can be stripped without difficulty and divided into equally long sections with even piece weights and withstood a compressive deformation without failures without prior deformation. , '

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The inner cross section of the mold is particularly advantageously circular. Blocks with a circular cross-section are particularly suitable as starting materials for ring rolling mills, pipe rolling mills, push benches, forging machines, Extrusion or 'for further forging deformation into shafts and axles. Even In the case of the round block material, which is particularly susceptible to cracks, no faults occurred due to cracks.

To reduce the mold costs, the mold can be divided into several sections in the transverse direction. The lowest section is the one when pouring is particularly stressed by the running-in of the liquid steel and therefore shorter service life has than the upper sections, expediently the shortest. The subdivision of the mold into Sections also allow blocks of different lengths to be poured by simply stacking them on top of each other of the sections without differing for the long blocks correspondingly many special molds would have to be kept in stock.

A casting machine is particularly suitable for carrying out the process, in particular for long blocks - Die-casting process - from a fire-proof lined container with a detachable attached pressure-tight Lid with lock, a refractory lined exiting at the bottom of the container, outside of the container upwards at least up to

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its upper edge guided pouring pipe, a pouring plate adjoining the pouring pipe and the dichL these subsequent, undivided in the axial direction Mold made of high-carbon iron with the same cross-section over the entire length. The casting machine allows the mold to be filled very quickly, precisely dosed and at the same time gentle, relatively. cold casting and complete "avoidance of air oxidation during casting, which reduces the solidification conditions. are inexpensive and homogeneous blocks with the highest surface quality can be produced.

The blocks produced by the method according to the invention, however, have a uniform cross-section not only to be used advantageously when starting material with uniform piece weights is required. Even with primary material with different unit weights, For example, for rings of different sizes, this is because of the same cross-section over the entire length preset individual piece weight can be set quickly and precisely via a simple length measurement. Of furthermore, there are structural advantages in further processing, even with different piece weights, of the cast blocks according to the invention for carrying.

In the following an embodiment of the invention is explained with reference to a drawing.

They show in detail:

109884 / 08-8-9 "- ¹¹ ".

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Fig. 1 shows a mold in cross section, used in the clamping casting,

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2 a mold with a holding device,

3 shows a casting machine with a permanent mold in ■ cross section.

The mold 1 consists of hematite. Their circular inner cross-section is the same over their entire length. Their total length is 7 m, their clear width 377 mm and their wall thickness on average 165 mm. The block to be cast in it has a weight of approx. 6 t. The coconut weight is 1.84 times the weight of the block. i The mold is. divided into several sections 2, 3, 4, of which the lowest section 2 is the shortest. The individual sections are stacked on top of each other without sealing the joints and are centered by grooves and lock washers worked into the mold sections. A hood 5 of refractory Materi- al} is used for desserts of the blow hole in -ΐ solidification of the block. The mold rests on a pouring plate 6; so that one or more molds can be poured into the pouring funnel 7 at the same time.

The following is an example of the inventive \

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dimensions Manufacture of 'VcTrmateirial uniform pieces- j weight and cross-section for a ring rolling mill in rising cast by means of this mold.

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Example 1:

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Quality 46 Cr 2

Casting temperature: 1,585 ° C - 5 ° C

Mold diameter rise speed inside mm cm / min

36

38.5

14th

11.9

Quality X 20 Cr 13

Casting temperature: 1,550 ° C - 5 ° C

250 .0 300 0 370 0 500 0 600 0 example 2:

Mold diameter rise speed inside mm cm / min

250 0
300 0
330 0

55 58 65

The blocks with the formats 250 mm, 300 mm and 330 mm were round without covering the liquid level in the mold and with painting the mold with a bitumen-based mold varnish, the blocks with the larger diameters under cover with heat insulating powder. The application of this

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long in relation to the diameter of the mold is due to the low head and foot scrap proportions in particular high. This long mold can be used with the same advantages in tension casting as well as in casting machines can be used. ·

In Figure 2, a three-part mold is shown which is held by a frame 8 with a Staircase 9 is provided to simplify work on the mold, such as painting.

With a casting machine according to FIG. 3, blocks were cast as follows after the process according to the invention. The steel produced by a known steelmaking process is tapped into a pouring ladle with a stopper. By opening the stopper, the steel flows without slag into the container 10, which is provided with a refractory lining 11. After the container 10 has been filled, it is closed with a lid. The lid is connected to the container 10 in an airtight manner by means of a seal 13 and locks 14. By applying compressed air to the melt level 15 through the compressed air line 16, the steel is pressed through the refractory-lined pouring pipe 17 and the pouring plate 18 with a central opening 19 into the upright multi-part mold 1. As soon as the mold is filled, the slide 20 in the casting plate 18 is closed, whereby the steel is prevented from flowing back

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will. By venting the container 10, the steel in the pouring pipe 17 flows back. The mold 1 is removed with the casting plate 18 and replaced by a new mold that is the same Process can be filled. The mold 1 is designed in detail like that according to FIG.

Expectations:

109884/0889

Claims (8)

Patent claims: 1. Process for the production of raw material of uniform piece weight and cross-section of metals, in particular made of steel, for ring tube rolling mills, push benches, forging machines, extrusion presses, etc., characterized in that the starting material is made by casting blocks with constant Cross-section over their total length, avoiding them of the usability impairing grooves and / or elevations over the circumference in standing molds and is made by dividing the blocks into sections of equal length. 2. The method according to claim 1, characterized show that the blocks are round or polygonal in cross-section with inner diameters from 250 to 350 mm in internally painted molds with rising speeds of 30 to 80 cm per minute Poured with an uncovered surface of the melt in the mold and as cold as possible in a centrically rising manner will. 3. The method according to claim!, Characterized that the blocks with round or polygonal cross-section with inner diameters over 300 mm while covering the surface of the melt in the mold with insulating powder with rising speeds from 10 to 30 cm per minute if possible 109884 / 0.889. - 16 - be poured cold centrically rising. 4. Process for the production of primary material one of claims 1 to 3, characterized that the melt is conveyed into the free-standing mold from below by applying gas pressure to its surface. 5. Mold, in particular for carrying out the method according to one of the above claims from kohlensEoffieichtm Iron, especially hematite, the internal cross-section of which is the same over its entire length, which is undivided in the axial direction, whose length is greater than 2 m »and whose clear width is greater than 250 mm, characterized in that its weight is at least 1.3 times the weight of the block amounts to. 6. Mold räch claim 5, characterized in that its inner cross-section is circular or polygonal is. 7. Mold according to claim 5 or 6, characterized ze ichnet that it is in the transverse direction is divided several times into sections (2,3,4) and preferably the lowest section (2) the shortest is. 8. Casting machine to carry out the process according to Claim 4 from a refractory lined container 109884/0889 - 17 - (10) with pressure-tight, removable cover (12) with a lock (14), a fire-proof lined exterior that emerges at the bottom of the container of the container (10) guided pouring pipe (17), with a pouring plate (18) adjoining the pouring pipe Closing slide (20) and one on the pouring plate (18) standing mold, characterized in that the mold after one or several of claims 5 to 7 is configured. 10988A / 0889 ΛΒ Blank page