US3416222A

US3416222A - Manufacture of elongate articles

Info

Publication number: US3416222A
Application number: US706188A
Authority: US
Inventors: Pearson John
Original assignee: British Iron and Steel Research Association BISRA
Current assignee: British Iron and Steel Research Association BISRA
Priority date: 1964-05-05
Filing date: 1968-02-16
Publication date: 1968-12-17
Anticipated expiration: 1985-12-17
Also published as: BE663459A; DE1282861B; GB1049698A; NO123617B; SE317778B

Description

J. PEARSON MANUFACTURE OF ELONGATE ARTICLES Original Filed April 29. 1965 3 Sheets-a'ohet 1 Fl l hl 1.

Iouvasnoe JOHN PEARSON mg, Maw (Ll-A;

Avenues: S

Dec. 17, 1968 J. PEARSON MANUFAGTURE OF ELONGATE ARTICLE S- Original Filed April 29. 1965 s Sheets-Sheet- 2' k\ \\m\\\ 1/14! I f z. I

ruva ufl'oa JOAN PEARSON MM, MM Mw Dec. 17, 1968 J. PEARSON 3,416,222

MANUFACTURE OF ELONGATE ARTICLES, I Original Filed April 29. 1965 I s Sheets-Sheet a v INvzM oQ Joan PEARsoN M 4 M Mm United States Patent 3,416,222 MANUFACTURE OF ELONGATE ARTICLES John Pearson, Dore, Sheflield, England, assignor to The British Iron and Steel Research Association Continuation of application Ser. No. 451,785, Apr. 29, 1965. This application Feb. 16, 1968, Ser. No. 706,188 Claims priority, application Great Britain, May 5, 1964, 18,713/ 64 4 Claims. (Cl. 29-528) ABSTRACT OF THE DISCLOSURE A method of making an elongate metal article having a cross-section which is constant longitudinally of the article and has a re-entrant portion, which method comprises the steps of feeding molten metal into an openended mold defining a cavity having a transverse crosssection larger than but of substantially the same geometric shape as the cross-section of said article, withdrawing the casting from the mold and rolling it while completely solidified to produce a reduction of at least 5:1 in the cross-sectional area of the casting.

This application is a continuation of Ser. No. 451,785, filed Apr. 29, 1965, now abandoned.

This invention is concerned with improvements in and relating to the production of elongate ferrous articles of constant transverse section which section is profiled. Such articles include for example such symmetric sectioned articles as flanged beams, joists or columns and such asymmetric sectioned articles as beams having fianges of unequal Width.

It is the practice to produce such articles by casting the ferrous metal to provide a rectangular sectioned ingot which is rolled in essentially three stages. The first stage transforms the ingot into a billet or bloom. The second stage employing profiled rolls converts the billet or bloom into a shape approximating to that of the finished article. The product at this stage is known as a blank. In the third stage the blank is further rolled in a section mill to the profiled section desired for the finished article.

There have been proposals to cast the billets or blooms in an open ended mould; such a procedure results only in the elimination of the first stage of rolling and not the second stage of rolling. It is not possible to dispense with the third stage of rolling because this is necessary to give the metal its deserved physical and mechanical properties.

It has also been suggested that the end product or a product closely related to it might be cast by means of an open mould but this is unsatisfactory because a reduction in cross section of more than about 5 :1 is necessary for adequate properties.

However, it has always been considered impractical to cast in an open ended mould any product of steel to which the mould would have to impart anything but a simple cross sectional shape though there have been produced castings being a number of square section castings united at their corners by a web. However in such cases the existence of such webs merely arose from the desire to interconnect the individual mould sections for pouring purposes. When cast the component castings were separated and then treated in accordance with the desired end product.

It is an object of this invention to provide a new and improved method of producing elongate ferrous metal articles of constant profiled cross section and according to the present invention there is provided a method of making an elongate ferrous metal article or blank of profiled transverse cross section constant longitudinally of the 3,416,222 Patented Dec. 17, 1968 article, the method comprising feeding molten ferrous metal into an open ended cooled mould having a cavity of transverse cross-section which approximates to the shape desired for the transverse section of the end product but of greater dimension, withdrawing the cast metal in solid or part solid state from the mould and passing the solidified blank through a rolling mill or mills to reduce it to the desired dimensions.

By this method there is a cast blank having a high quality shape and surface, and uniform physical characteristics fed to a rolling mill with a cross section whose areas to either side of a mean plane are proportional to the equivalent areas in the end product so that during reduction metal has not tobe spread transversely, which is the case particularly with the production of asymmetric sections when rolled from a symmetric workpiece such as a rectangular billet. There is no need for the first and second stages of rolling referred to above. The reduction of the casting will be such as will impart to the metal the physical characteristics required for the end product.

In order that the present invention may be well understood there will now be described some embodiments thereof, given byway of example only, reference being had to the accompanying drawings in which:

FIGURE 1 is a plan view of a mould for the production of symmetrical beam blanks,

FIGURE 2 is an elevation of the mould,

FIGURE 3 is a section on the line III-III of FIG- URE 2,

FIGURE 4 is an elevation of the nip between the rolls of a breakdown mill in the third stage of rolling to roll the casting produced by the mould of FIGURES 1 to 3,

FIGURE 5 is an elevation of the nip of the rougher for working the flanges of the workpiece following the breakdown operation,

FIGURE 6 is an elevation of the nip of the edging mill,

FIGURE 7 is an elevation of the nip of the rolls in the final rolling procedure,

FIGURE 8 is a plan view of a mould for producing an alternative shape of blank.

FIGURE 9 is a section of a beam with flanges of unequal width,

FIGURE 10 is a perspective view of the above beam rolled from a symmetrical casting, and

FIGURE 11 is a plan view of a mould for producing a blank for rolling to the finished shape of FIGURE 9.

Referring to FIGURES 1 to 3 the mould is of high conductivity silver bearing copper of analysis: 0.1% silver and less than .005 phosphorous and .007% arsenic. The mould is in complementary cast, forged and machined

halves

1, 2 each having an internal surface profiled so that together they define an open ended cavity a of a shape which approximates to the shape of the end product but of greater dimensions.

The overall dimensions of the mould are 24 in. long x 14 in. wide x 20 in. high and the cavity c is in the shape of a universal beam blank 18 /2 in. long with 10%" flanges and 3.075" web thickness. The two halves are located by dowels and clamped together with 14 /s-in. dia. high tensile steel bolts 3. Two brackets (not shown) are attached to the ends, and these are fastened to a resiliently mounted frame which is supported on four helical coil springs rated at 350 lb./inch with vertical guiding columns inside the springs.

The water cooling of the mould passes through 60 vertical channels 4 formed by boring in. holes from the bottom of the mould at approximately 1% in. centres, set back /8 in. from the cavity. Restrictor rods 5, circular in section with a segment machined away leaving a flat face 5a, are inserted and sealed as shown at 6, to ensure adequate water velocity through the channels.

The water is supplied to and removed from the channels by way of eight manifolds 7 in each half flexibly connected to branched inlet and outlet stand pipes by connectors 8. The water flow rate during casting is 350 gal. per minute and the rise in temperature is between 7 and 8 C. This is equivalent to an average heat transfer to 30 cals./sq. cm. of mould face/sec.

Below the mould is fixed a set of four guide rollers to prevent any transverse stress on the emerging casting. Below these are fixed eight banks of support rolls which guide the outside faces of the flanges and both sides of the web portion of the casting and prevent bulging of the solidifying shell due to ferrostatic pressure within the liquid core. The length of this train of rolls is ft.- 6 in.

Between the guide rolls are placed rings of water spray nozzles to assist the cooling of the ingot. In practice a total flow of 35 gallons per minute is used for this secondary cooling.

Before casting is started a dummy head is inserted halfway up the mould and the gap sealed with asbestos rope to prevent liquid steel passing between the head and the mould. The head is attached to a dummy bar which is withdrawn by rolls at predetermined speeds.

Mounted over the mould is a tundish with two refractory nozzles of %-in. or 'Ms-in. diameter, 14 in. apart, so that the two emerging streams pour on to the centre of a circle meeting the outer side of the flanges and the fillet radii between the web and flanges. The tundish, which is lined with alumino-silicate refractory bricks and fitted with a stopper for each nozzle, is preheated by a gas/air burner to approximately 1450 C. and the parts of the nozzles emerging below the steel casing of the tundish are heated by a ring of gas jets.

CASTING 22 cwt. of steel to analysis of 20% C, 1.0% Mn, 25% Si, made by a double slag process in a basic electric arc furnace are tapped at 1630 C. into a ladle preheated to 800 C.

The ladle is then transferred to the casting plant and when the temperature of the steel in the ladle is 1570? C. the steel is bottom poured into the tundish, whence it flows into the mould.

When the metal level in the mould has risen to about 3 in. from the top of the mould the dummy head is withdrawn vertically downwards at a steady rate of between 1 /2 and 4 ft. per minute, and the liquid metal level is maintained by judicious use of the stoppers in the tundish.

There is generally a downward displacement of the mould on its spring supports equivalent to a frictional force of 500-1000 lbs.

When the ingot has completely solidified, it is removed from the plant.

ROLLING The casting with a cross-section of approximately 18 in. x in. with 3 in. web thickness is reheated to 1290 C. in a 3 zone continuous bloom reheating furnace and reduced by rolling on a 32 in. reversing 2 high breakdown mill having a nip as shown in FIGURE 4 by 5 passes turning over between passes, to give an intermediate shape of 18%; in. x 7 in. with 1% web thickness.

This is then further rolled in the 50 in. roughing and 36 in. horizontal edging stands shown in FIGURES 5 and 6 of a universal wide flange beam mill in 7 passes, followed by a single small pass on the finishing stand (FIGURE 7) to give the normal finished section of a 14 x 6% in., 34 lb./foot universal beam.

This practice enables blanks to be rolled through a fully automated wide flange beam mill with no difllcuL ties of changes to mill settings and satisfactory beams have been produced by normal rolling and handling procedures.

Mechanical properties and metallurgical characteristics of the rolled beams are found to be the same as those of conventionally rolled beams and compatible with the chemical composition of the steel and the surface quality of the finished product is rated excellent.

It will be seen that because the mould imparts to the casting the profile normally given during the first two rolling stages, such initial rolling is not necessary and only rolling applied to the casting is that which is sufficient to reduce the profiled casting to the desired dimensioned H-shape.

It is possible to cast blanks of a shape to suit any desired end product and such shapes are shown in FIG-

URES

1, 8 and 11.

The mould may be shaped longitudinally as shown by the chain dot lines in FIGURES 1 and 8. The faces of walls 14 which abut the inwardly facing parts of the flanges on the same side of the casting may converge downwards as shown by the chain dot lines which indicate the shape of the mould section at the exit from the mould. The purpose of this is to prevent an increase of friction between the inward facing flange faces of the casting and the mould walls caused by contraction and bind ing of the ingot during solidification and cooling. The amount of taper depends on the metal being cast, the size and shape of the section, the withdrawal speed and the cooling etficiency of the mould.

The outer walls 15 may also converge downwards, as shown by the chain dot lines. The purpose of this convergence is to increase the rate of heat transfer between ingot and the mould walls, by minimising the gap between the contracting ingot and the mould wall. The convergence should be such as will not cause binding. The inner surface of the mould may be lubricated by means well known in the art and the ingots may be withdrawn from each mould rectilinearly, along a straight and then a curved path, or along a curved path beginning at the exit from the mould, or beginning within the mould where such mould has a :curved or partly curved axis.

Where the end product has an asymmetric cross-section, the use of a symmetric sectioned workpiece involves certain difiiculties. For example, in the end product shown in FIGURE 9 because of the difference in the cross-sectional areas of the

end flanges

23, 24, the area of the section to the left of the centre line 25 is greater than the area to the right of this line. As illustrated, the area to the left of the line 25 is twice the area to the right of this line.

In rolling an elongate article having the cross-sectional shape of an article cast from the mould of FIGURE 1 to an article having the cross-sectional shape shown in FIG- URE 9, metal is moved both in the direction of rolling and perpendicular to the direction of rolling. The movement of metal perpendicular to the direction of rolling is referred to as spread. Difficulty is experienced in containing the spread and directing the flow of metal to the desired areas of the section. To obtain the final required cross-section involves a large number of rolling operations and considerable skill is required in the design of the passprofile for each stage. Furthermore, and because that part of the metal which goes into spread is not evenly distributed about the central axis of the section, one side of the section undergoes a greater elongation than the other with the result that the rolled product is curved in the longitudinal direction. The rolled product so curved is shown in FIGURE 10.

To minimise this curvature it is necessary to use guides on the exit side of the mill. These guides are massive and have to be accurately located; this process requires considerable manual skill and is time consuming.

If however the article prior to being given its final cross sectional shape is given the asymmetrical cross sectional shape of the cavity of the mould shown in FIG- URE 11 in which the area to the left of the centre line 26 is twice the area to the right of this line instead of 5 the shape of the article cast from the mould of FIGURE 1, and is then subjected to rolling, it is possible without difiiculty to roll a section shown in FIGURE 9.

An ingot having the cross-sectional shape of the cavity of the mould of FIGURE 11 while not easily made by rolling it can be made by the process of casting in an open ended mould as illustrated in FIGURE 11.

The mould of FIGURE 11 has two relatively

wide sections

27, 28 and a relatively narrow section 30. It will be apparent that the material cast in

sections

27 and 28 will form the

flanges

23, 24 of the article shown in FIGURE 9, and the material cast in section 30 will form the web of this article. Having been given an asymmetrical cross-section approximating to, but larger than, the shape of the desired final cross-section, the casting is rolled to the desired cross-sectional shape shown in FIGURE 9.

The

mould sections

27, 28 can be slightly tapered as indicated by chain dot lines as already discussed in relation to FIGURES 1 and 8.

Liquid metal is poured into the section 30 and/ or into either or both of the

end sections

27, 28. Inequality of flow is accommodated by the liquid metal finding its own level within the mould as with the moulds of FIGURES 1, 2, 3 or of FIGURE 8. Metal is preferably poured directly into the mould there being no head of metal common to all the mould sections though this practice may be adopted if the head is accommodated in a receptacle of suitable material Which will not result in freezing of the metal above the actual mould cavity as is present in certain prior continuous casting apparatus.

What is claimed is:

1. A method of making a completely solidified elongate ferrous metal article of predetermined dimensions having a cross-section which is constant longitudinally of the article and Which has at least one re-entrant portion, said method comprising the steps of feeding molten ferrous metal into an open-ended cooled mold defining a cavity having a transverse cross-section larger than but of substantially the same geometric shape as the crosssection of said completely solidified article, withdrawing the casting in at least part solid state from said mold and rolling said casting to reduce it to said predetermined dimensions, the entire rolling operation being performed after said casting has completely solidified, and acting on all external surfaces of said casting to produce a reduction of at least 5:1 in the cross-sectional area of the casting.

2. A method according to claim 1, wherein the completely solidified casting is fed through a rolling mill comprising a profiled breakdown stand, a rougher stand, an edging stand and a finisher stand.

3. A method according to claim 1, wherein the mold cavity has a cross-section shaped to form a beam having a profiled section including a web and a flange at each end thereof.

4. A method according to claim 1, wherein the mold cavity has an asymmetric cross-section.

References Cited UNITED STATES PATENTS JOHN F. CAMPBELL, Primary Examiner.

P. M. COHEN, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,4l6, 222 December 17 l968 John Pearson It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5 line 3 after "into" insert one end of same line 37 "detinlng" should read formed by mould walls which are stationary relative to each other while forming said mould and WhlCh define Column 6, line 2 after "from" insert the other end of Signed and sealed this 24th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer